Search

Both human and animal experiments have demonstrated that energy metabolism dysfunction in neurons after seizures is associated with an imbalance in mitochondrial fusion/fission dynamics. Effective neuronal mitochondrial dynamics regulation strategies remain elusive. Nicotinamide mononucleotide (NMN) can ameliorate mitochondrial functional and oxidative stress in age‐related diseases. But whether NMN improves mitochondrial energy metabolism to exert anti‐epileptic effects is unclear. This study aims to clarify if NMN can protect neurons from pentylenetetrazole (PTZ) or Mg2+‐free‐induced mitochondrial disorder and apoptosis via animal and cell models. We established a continuous 30‐day PTZ (37 mg/kg) intraperitoneal injection‐induced epileptic mouse model and a cell model induced by Mg2+‐free solution incubation to explore the neuroprotective effects of NMN. We found that NMN treatment significantly reduced the seizure intensity of PTZ‐induced epileptic mice, improved their learning and memory ability, and enhanced their motor activity and exploration desire. At the same time, in vitro and in vivo experiments showed that NMN can inhibit neuronal apoptosis and improve the mitochondrial energy metabolism function of neurons. In addition, NMN down‐regulated the expression of mitochondrial fission proteins (Drp1 and Fis1) and promoted the expression of mitochondrial fusion proteins (Mfn1 and Mfn2) by activating the SIRT1‐PGC‐1α pathway, thereby inhibiting PTZ or Mg2+‐free extracellular solution‐induced mitochondrial dysfunction, cell apoptosis, and oxidative stress. However, combined intervention of SIRT1 inhibitor, Selisistat, and PGC‐1α inhibitor, SR‐18292, eliminated the regulatory effect of NMN pre‐treatment on mitochondrial fusion and fission proteins and apoptosis‐related proteins. Therefore, NMN intervention may be a new potential treatment for cognitive impairment and behavioral disorders induced by epilepsy, and targeting the SIRT1‐PGC‐1α pathway may be a promising therapeutic strategy for seizures. [ABSTRACT FROM AUTHOR]

Mitochondrial homeostasis plays a crucial role in degenerative joint diseases, including cartilaginous endplate (CEP) degeneration. To date, research into mitochondrial dynamics in IVDD is at an early stage. Since Piezo1 is a novel Ca2+‐permeable channel, we asked whether Piezo1 could modulate mitochondrial fission through Ca2+ signalling during CEP degeneration. In vitro and in vivo models of inflammation‐induced CEP degeneration were established with lipopolysaccharide (LPS). We found increased expression of Piezo1 in degenerated CEP tissues and LPS‐treated CEP cells. The Piezo1 activator Yoda1 exacerbated CEP cell senescence and apoptosis by triggering Ca2+ influx. Yoda1 also induced mitochondrial fragmentation and dysfunction. In contrast, the Piezo1 inhibitor GsMTx4 exerted cytoprotective effects in LPS‐treated CEP cells. Additionally, the CaMKII inhibitor KN‐93 reversed Yoda1‐induced mitochondrial fission and restored mitochondrial function. Mechanistically, the phosphorylation and mitochondrial translocation of Drp1 were regulated by the Ca2+/CaMKII signalling. The Drp1 inhibitor Mdivi‐1 suppressed mitochondrial fission, then reduced mitochondrial dysfunction and CEP cell death. Moreover, knockdown of Piezo1 by siRNA hindered CaMKII and Drp1 activation, facilitating the redistribution of mitochondrial Drp1 to the cytosol in LPS‐treated CEP cells. Piezo1 silencing improved mitochondrial morphology and function, thereby rescuing CEP cell senescence and apoptosis under inflammatory conditions. Finally, subendplate injection of GsMTx4 or AAV‐shPiezo1 alleviated CEP degeneration in a rat model. Thus, Piezo1 may exacerbate inflammation‐induced CEP degeneration by triggering mitochondrial fission and dysfunction via the Ca2+/CaMKII/Drp1 axis. [ABSTRACT FROM AUTHOR]

Mitochondrial DNA (mtDNA) is present in multiple copies within cells and is required for mitochondrial ATP generation. Even within individual cells, mtDNA copies can differ in their sequence, a state known as heteroplasmy. The principles underlying dynamic changes in the degree of heteroplasmy remain incompletely understood, due to the inability to monitor this phenomenon in real time. Here, we employ mtDNA-based fluorescent markers, microfluidics, and automated cell tracking, to follow mtDNA variants in live heteroplasmic yeast populations at the single-cell level. This approach, in combination with direct mtDNA tracking and data-driven mathematical modeling reveals asymmetric partitioning of mtDNA copies during cell division, as well as limited mitochondrial fusion and fission frequencies, as critical driving forces for mtDNA variant segregation. Given that our approach also facilitates assessment of segregation between intact and mutant mtDNA, we anticipate that it will be instrumental in elucidating the mechanisms underlying the purifying selection of mtDNA. Synopsis: The basis for dynamic changes in mitochondria DNA variations in cell populations, known as heteroplasmy, remains unclear. Here, live-cell tracking of mtDNA variants in yeast populations reveals mechanistic principles underlying mtDNA variant segregation. mtDNA variants encoding fluorescent reporters facilitate microscopy approaches for monitoring mtDNA variant segregation in real-time in a dividing yeast population. Asymmetric partitioning of mtDNA copies between mother and daughter cells as well as mitochondrial fission rates determine the rate of mtDNA variant segregation. mtDNA variant segregation is delayed in ∆mrx6 cells with increased mtDNA copy number. The imaging approach allows monitoring of purifying selection against mutant mtDNA. Tracking mtDNA variants in live yeast populations reveals asymmetric partitioning of mtDNA copies during cell division as well as limited mitochondrial fusion/fission frequencies as critical drivers of mtDNA variant segregation. [ABSTRACT FROM AUTHOR]

Cisplatin-induced acute kidney injury (AKI) is characterized by mitochondrial damage and apoptosis, and safe and effective therapeutic agents are urgently needed. Renal tubular epithelial cells, the main site of AKI, are enriched with a large number of mitochondria, which are crucial for the progression of AKI with an impaired energy supply. Vincamine has anti-inflammatory and antioxidant effects in mouse AKI models. As a natural compound derived from Tabernaemontana pandacaqui , (+)-14, 15-Dehydrovincamine and Vincamine differ in structure by only one double bond, and the role and exact mechanism of (+)-14, 15-Dehydrovincamine remains to be elucidated in AKI. The present study demonstrated that (+)-14,15-Dehydrovincamine significantly ameliorated mitochondrial dysfunction and maintained mitochondrial homeostasis in a cisplatin-induced AKI model. Furthermore, (+)-14,15-Dehydrovincamine ameliorates cytochrome C-dependent apoptosis in renal tubular epithelial cells. c-Jun NH2-terminal kinase (JNK) was identified as a potential target protein of (+)-14,15-Dehydrovincamine attenuating AKI by network pharmacological analysis. (+)-14,15-Dehydrovincamine inhibited cisplatin-induced JNK activation, mitochondrial fission factor (Mff) phosphorylation, and dynamin-related protein 1 (Drp1) translocation to the mitochondria in renal tubular epithelial cells. Meanwhile, the JNK activator anisomycin restored Mff phosphorylation and Drp1 translocation, counteracting the protective effect of (+)-14,15-Dehydrovincamine on mitochondrial dysfunction in cisplatin-induced TECs injury. In conclusion, (+)-14,15-Dehydrovincamine reduced mitochondrial fission, maintained mitochondrial homeostasis, and attenuated apoptosis by inhibiting the JNK/Mff/Drp1 pathway, which in turn ameliorated cisplatin-induced AKI. [Display omitted] • (+)-14,15-Dehydrovincamine is superior to Vincamine against cisplatin-induced TEC injury. • (+)-14,15-Dehydrovincamine attenuates cisplatin-induced AKI in a mouse model. • (+)-14,15-Dehydrovincamine reduces mitochondrial fission through the JNK/Mff/Drp1 pathway. [ABSTRACT FROM AUTHOR]

Mitochondria are dynamic organelles that continuously undergo fusion/fission to maintain normal cell physiological activities and energy metabolism. When mitochondrial dynamics is unbalanced, mitochondrial homeostasis is broken, thus damaging mitochondrial function. Accumulating evidence demonstrates that impairment in mitochondrial dynamics leads to lung tissue injury and pulmonary disease progression in a variety of disease models, including inflammatory responses, apoptosis, and barrier breakdown, and that the role of mitochondrial dynamics varies among pulmonary diseases. These findings suggest that modulation of mitochondrial dynamics may be considered as a valid therapeutic strategy in pulmonary diseases. In this review, we discuss the current evidence on the role of mitochondrial dynamics in pulmonary diseases, with a particular focus on its underlying mechanisms in the development of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), lung cancer and bronchopulmonary dysplasia (BPD), and outline effective drugs targeting mitochondrial dynamics‐related proteins, highlighting the great potential of targeting mitochondrial dynamics in the treatment of pulmonary disease. [ABSTRACT FROM AUTHOR]

Vascular endothelial senescence is a major risk factor for diabetic vascular complications. Abnormal mitochondrial fission by dynamically related protein 1 (DRP1) accelerates vascular endothelial cell senescence. Homoplantaginin (Hom) is a flavonoid in Salvia plebeia R. Br. with protecting mitochondrial and repairing vascular properties. However, the relevant mechanism of Hom against diabetic vascular endothelial cell senescence remains unclear. Here, we used db/db mice and high glucose (HG)‐treated human umbilical vein endothelial cells (HUVECs) to assess the anti‐vascular endothelial cell senescence of Hom. We found that Hom inhibited senescence‐associated β‐galactosidase activity, decreased the levels of senescence markers, and senescence‐associated secretory phenotype factors. Additionally, Hom inhibited the expression of cGAS–STING pathway and downstream inflammatory factors. STING inhibitor H‐151 delayed endothelial senescence, whereas STING overexpression attenuated the anti‐endothelial senescence effect of Hom. Furthermore, we observed that Hom reduced mitochondrial fragmentation and inhibited abnormal mitochondrial fission using transmission electron microscopy. Importantly, Hom has a stronger effect on mitochondrial fission protein than mitochondrial fusion protein, especially downregulated the expression of DRP1. DRP1 inhibitor Mdivi‐1 suppressed cGAS‐STING pathway and vascular endothelial senescence, yet DRP1 agonist FCCP attenuated the effect of Hom. Surprisingly, Hom blunted abnormal mitochondrial fission mediated by DRP1 mitochondrial localization, suppressed interaction of DRP1 with VDAC1 and prevented VDAC1 oligomerization, which was necessary for mtDNA escape and subsequent cGAS–STING pathway activation. These results revealed a previously unrecognized mechanism that Hom alleviated vascular endothelial senescence by inhibited mtDNA–cGAS–STING signaling pathway via blunting DRP1–mitochondrial fission–VDAC1 axis. [ABSTRACT FROM AUTHOR]

Dystrophic calcinosis, which is the accumulation of insoluble calcified crystalline materials within tissues with normal circulating calcium and phosphorus levels, is a frequent finding in systemic sclerosis (SSc) and represents a major burden for patients. In SSc, calcinosis poses significant challenges in management due to the associated risk of severe complications such as infection, ulceration, pain, reduction in functional capacity and quality of life, and lack of standardized treatment choices. The exact pathogenesis of calcinosis is still unknown. There are multifaceted factors contributing to calcinosis development, including osteogenic differentiation of cells, imbalance between promoter and inhibitors of mineralization, local disturbance in calcium and phosphate levels, and extracellular matrix as a template for mineralization. Several pathophysiological changes observed in SSc such as ischemia, exacerbated production of excessive reactive oxygen species, inflammation, production of inflammatory cytokines, acroosteolysis, and increased extracellular matrix production may promote the development of calcinosis in SSc. Furthermore, mitochondrial dynamics, particularly fission function through the activity of dynamin-related protein-1, may have an effect on the dystrophic calcinosis process. In-depth investigations of cellular mechanisms and microenvironmental influences can offer valuable insights into the complex pathogenesis of calcinosis in SSc, providing potential targeting pathways for calcinosis treatment. [ABSTRACT FROM AUTHOR]

Background: During the aging process, the number and functional activity of endothelial progenitor cells (EPCs) are impaired, leading to the unsatisfactory efficacy of transplantation. Previous studies demonstrated that Yiqihuoxue decoction (Ginseng-Sanqi-Chuanxiong, GSC) exerts anti-vascular aging effects. The purpose of this study is to evaluated the effects of GSC on D-galactose (D-gal)induced senescence and the underlying mechanisms. Methods: The levels of cellular senescence-related markers P16, P21, P53, AMPK and p-AMPK were detected by Western blot analysis (WB). SA-β-gal staining was used to evaluate cell senescence. EPCs function was measured by CCK-8, Transwell cell migration and cell adhesion assay. The morphological changes of mitochondria were detected by confocal microscopy. The protein and mRNA expression of mitochondrial fusion fission Drp1, Mff, Fis1, Mfn1, Mfn2 and Opa1 in mitochondria were detect using WB and RT–qPCR. Mitochondrial membrane potential, mtROS and ATP of EPCs were measured using IF. H&E staining was used to observe the pathological changes and IMT of the aorta. The expressions of AGEs, MMP-2 and VEGF in aorta were measured using Immunohistochemical (IHC). The levels of SOD, MDA, NO and ET-1 in serum were detected by SOD, MDA and NO kits. Results: In vitro, GSC ameliorated the senescence of EPCs induced by D-gal and reduced the expression of P16, P21 and P53. The mitochondrial morphology of EPCs was restored, the expression of mitochondrial Drp1, Mff and Fis1 protein was decreased, the levels of mtROS and ATP were decreased, and mitochondrial function was improved. Meanwhile, the expression of AMPK and p-AMPK increased. The improvement effects of GSC on aging and mitochondrial morphology and function were were hindered after adding AMPK inhibitor. In vivo, GSC improved EPCs efficiency, ameliorated aortic structural disorder and decreased IMT in aging mice. The serum SOD level increased and MDA level decreased, indicating the improvement of antioxidant capacity. Increased NO content and ET-1 content suggested improvement of vascular endothelial function. The changes observed in SOD and MMP-2 suggested a reduction in vascular stiffness and the degree of vascular damage. The decreased expression of P21 and P53 indicates the delay of vascular senescence. [ABSTRACT FROM AUTHOR]

Alzheimer's diseases (AD) patients suffer from more serious bone loss than cognitively normal subjects at the same age. Type H blood vessels were tightly associated with bone homeostasis. However, few studies have concentrated on bone vascular alteration and its role in AD‐related bone loss. In this study, APP/PS1 mice (4‐ and 8‐month‐old) and age‐matched wild‐type mice were used to assess the bone vascular alteration and its role in AD‐related bone loss. Transmission electron microscopy, immunofluorescence staining and iGPS 1.0 software database were utilized to investigate the molecular mechanism. Mitochondrial division inhibitor (Mdivi‐1) and GSK‐3β inhibitor (LiCl) were used to rescue type H blood vessels injury and verify the molecular mechanism. Our results revealed that APP/PS1 mice exhibited more serious bone blood vessels injury and bone loss during ageing. The bone blood vessel injury, especially in type H blood vessels, was accompanied by impaired vascularized osteogenesis in APP/PS1 mice. Further exploration indicated that beta‐amyloid (Aβ) promoted the apoptosis of vascular endothelial cells (ECs) and resulted in type H blood vessels injury. Mechanistically, Aβ‐induced excessive mitochondrial fission was found to be essential for the apoptosis of ECs. GSK‐3β was identified as a key regulatory target of Aβ‐induced excessive mitochondrial fission and bone loss. The findings delineated that Aβ‐induced excessive mitochondrial fission drives type H blood vessels injury, leading to aggravate bone loss in APP/PS1 mice and GSK‐3β inhibitor emerges as a potential therapeutic strategy. [ABSTRACT FROM AUTHOR]

The aberrant acetylation of mitochondrial proteins is involved in the pathogenesis of multiple diseases including neurodegenerative diseases and cerebral ischemic injury. Previous studies have shown that depletion of mitochondrial NAD+, which is necessary for mitochondrial deacetylase activity, leads to decreased activity of mitochondrial deacetylase and thus causes hyperacetylation of mitochondrial proteins in ischemic brain tissues, which results in altered mitochondrial dynamics. However, it remains largely unknown about how mitochondrial dynamics-related protein Drp1 is acetylated in ischemic neuronal cells and brain tissues. Here, we showed that Drp1 and GCN5L1 expression was up-regulated in OGD-treated neuronal cells and ischemic brain tissues induced by dMCAO, accompanied by the increased mitochondrial fission, mtROS accumulation, and cell apoptosis. Further, we confirmed that ischemia/hypoxia promoted Drp1 interaction with GCN5L1 in neuronal cells and brain tissues. GCN5L1 knockdown attenuated, while its overexpression enhanced Drp1 acetylation and mitochondrial fission, indicating that GCN5L1 plays a crucial role in ischemia/hypoxia-induced mitochondrial fission by acetylating Drp1. Mechanistically, ischemia/hypoxia induced Drp1 phosphorylation by CDK5 upregulation-mediated activation of AMPK in neuronal cells, which in turn facilitated the interaction of GCN5L1 with Drp1, thus enhancing Drp1 acetylation and mitochondrial fission. Accordingly, inhibition of AMPK alleviated ischemia/hypoxia- induced Drp1 acetylation and mitochondrial fission and protected brain tissues from ischemic damage. These findings provide a novel insight into the functional roles of GCN5L1 in regulating Drp1 acetylation and identify a previously unrecognized CDK5-AMPK-GCN5L1 pathway that mediates the acetylation of Drp1 in ischemic brain tissues. [ABSTRACT FROM AUTHOR]

The dynamicity of the mitochondrial network is crucial for meeting the ever‐changing metabolic and energy needs of the cell. Mitochondrial fission promotes the degradation and distribution of mitochondria, while mitochondrial fusion maintains mitochondrial function through the complementation of mitochondrial components. Previously, we have reported that mitochondrial networks are tubular, interconnected, and well‐organized in young, healthy C. elegans, but become fragmented and disorganized with advancing age and in models of age‐associated neurodegenerative disease. In this work, we examine the effects of increasing mitochondrial fission or mitochondrial fusion capacity by ubiquitously overexpressing the mitochondrial fission gene drp‐1 or the mitochondrial fusion genes fzo‐1 and eat‐3, individually or in combination. We then measured mitochondrial function, mitochondrial network morphology, physiologic rates, stress resistance, and lifespan. Surprisingly, we found that overexpression of either mitochondrial fission or fusion machinery both resulted in an increase in mitochondrial fragmentation. Similarly, both mitochondrial fission and mitochondrial fusion overexpression strains have extended lifespans and increased stress resistance, which in the case of the mitochondrial fusion overexpression strains appears to be at least partially due to the upregulation of multiple pathways of cellular resilience in these strains. Overall, our work demonstrates that increasing the expression of mitochondrial fission or fusion genes extends lifespan and improves biological resilience without promoting the maintenance of a youthful mitochondrial network morphology. This work highlights the importance of the mitochondria for both resilience and longevity. [ABSTRACT FROM AUTHOR]

Background: N6-methyladenosine (m6A) modification of messenger RNA (mRNA) is crucial for liquid-liquid phase separation in mammals. Increasing evidence indicates that liquid-liquid phase separation in proteins and RNAs affects diabetic cardiomyopathy. However, the molecular mechanism by which m6A-mediated phase separation regulates diabetic cardiac fibrosis remains elusive. Methods: Leptin receptor-deficient mice (db/db), cardiac fibroblast-specific Notch1 conditional knockout (POSTN-Cre × Notch1flox/flox) mice, and Cre mice were used to induce diabetic cardiac fibrosis. Adeno-associated virus 9 carrying cardiac fibroblast-specific periostin (Postn) promoter-driven small hairpin RNA targeting Alkbh5, Ythdf2, or Notch1, and the phase separation inhibitor 1,6-hexanediol were administered to investigate their roles in diabetic cardiac fibrosis. Histological and biochemical analyses were performed to determine how Alkbh5 and Ythdf2 regulate Notch1 expression in diabetic cardiac fibrosis. NOTCH1 was reconstituted in ALKBH5- and YTHDF2-deficient cardiac fibroblasts and mouse hearts to study its effects on mitochondrial fission and diabetic cardiac fibrosis. Heart tissue samples from patients with diabetic cardiomyopathy were used to validate our findings. Results: In mice with diabetic cardiac fibrosis, decreased Notch1 expression was accompanied by high m6A mRNA levels and mitochondrial fission. Fibroblast-specific deletion of Notch1 enhanced mitochondrial fission and cardiac fibroblast proliferation and induced diabetic cardiac fibrosis in mice. Notch1 downregulation was associated with Alkbh5-mediated m6A demethylation in the 3'UTR of Notch1 mRNA and elevated m6A mRNA levels. These elevated m6A levels in Notch1 mRNA markedly enhanced YTHDF2 phase separation, increased the recognition of m6A residues in Notch1 mRNA by YTHDF2, and induced Notch1 degradation. Conversely, epitranscriptomic downregulation rescues Notch1 expression, resulting in the opposite effects. Human heart tissues from patients with diabetic cardiomyopathy were used to validate the findings in mice with diabetic cardiac fibrosis. Conclusions: We identified a novel epitranscriptomic mechanism by which m6A-mediated phase separation suppresses Notch1 expression, thereby promoting mitochondrial fission in diabetic cardiac fibrosis. Our findings provide new insights for the development of novel treatment approaches for patients with diabetic cardiac fibrosis. [ABSTRACT FROM AUTHOR]

Heterocyclic compounds play a crucial role in the drug discovery process and development due to their significant presence and importance. Here, we report a comprehensive analysis of α-aminophosphonates containing pyridine (3a–g), prepared according to a clear-cut, uncomplicated procedure. The phosphonates are thoroughly characterized using various methods, such as elemental analysis, mass spectrometry, proton and carbon NMR, and FT-IR. The molecular docking interactions between the phosphonate and DRP-1 target protein observed that compound 3d had the top-ranked binding energy towards DRP-1 with a value equal to − 9.54 kcal/mol and this theoretically proves its inhibitory efficacy against DRP-1 arbitrated mitochondrial fission. Besides, the anticancer characteristics of compound 3d showed the best IC50 against HepG-2, MCF-7, and Caco-2 which confirmed our results towards suppressing DRP-1 protein (in-silico), and it elucidated no cytotoxic effects against human normal cell line (WI-38). Further, its pharmacokinetics were observed theoretically using ADMET. Moreover,compound 3d investigated the most potent antimicrobial ability against two pathological fungal strains, A. flavus and C. albicans, and four bacterial strains, E. coli, B. subtillis, S. aureus, and P. aregeunosa. Additionally, compound 3d clarified a powerful antioxidant scavenging activity against DPPH and ABTS free radicals (in-vitro). Furthermore, Density functional theory (DFT) was used to study the molecular structures of the synthesized compounds 3a–g, utilizing 6–311++G(d,p) as the basis set and to learn more about the molecules' reactive sites, the energies of the molecular electrostatic potential (MEP), the lowest unoccupied molecular orbital (LUMO), and the highest occupied molecular orbital (HOMO) were observed. Theoretically, FT-IR and Nuclear magnetic resonance (NMR) measurements are calculated for every compound under investigation to show how theory and experiment relate. It was found that there was an excellent agreement between the theoretical and experimental data. Conclusively, all novel synthesized phosphonates could be used as pharmaceutical agents against pathogenic microbial strains and as anticancer candidates by inhibiting DRP-1-mediated mitochondrial mitophagy. [ABSTRACT FROM AUTHOR]

The relationship of Amyotrophic Lateral Sclerosis, Parkinson's disease, and other age-related neurodegenerative diseases with mitochondrial dysfunction has led to our study of the mitochondrial fission gene Drp1 in Drosophila melanogaster and aspects of aging. Previously, the Drp1 protein has been demonstrated to interact with the Drosophila Bcl-2 mitochondrial proteins, and Drp1 mutations can lead to mitochondrial dysfunction and neuronal loss. In this study, the Dopa decarboxylase-Gal4 (Ddc-Gal4) transgene was exploited to direct the expression of Drp1 and Drp1-RNAi transgenes in select neurons. Here, the knockdown of Drp1 seems to compromise locomotor function throughout life but does not alter longevity. The co-expression of Buffy suppresses the poor climbing induced by the knockdown of the Drp1 function. The consequences of Drp1 overexpression, which specifically reduced median lifespan and diminished climbing abilities over time, can be suppressed through the directed co-overexpression of pro-survival Bcl-2 gene Buffy or by the co-knockdown of the pro-cell death Bcl-2 homologue Debcl. Alteration of the expression of Drp1 acts to phenocopy neurodegenerative disease phenotypes in Drosophila, while overexpression of Buffy can counteract or rescue these phenotypes to improve overall health. The diminished healthy aging due to either the overexpression of Drp1 or the RNA interference of Drp1 has produced novel Drosophila models for investigating mechanisms underlying neurodegenerative disease. [ABSTRACT FROM AUTHOR]

After seizures, the hyperactivation of extracellular signal‐regulated kinases (ERK1/2) causes mitochondrial dysfunction. Through the guidance of dynamin‐related protein 1 (DRP1), ERK1/2 plays a role in the pathogenesis of several illnesses. Herein, we speculate that ERK1/2 affects mitochondrial division and participates in the pathogenesis of epilepsy by regulating the activity of DRP1. LiCl‐Pilocarpine was injected intraperitoneally to establish a rat model of status epilepticus (SE) for this study. Before SE induction, PD98059 and Mdivi‐1 were injected intraperitoneally. The number of seizures and the latency period before the onset of the first seizure were then monitored. The analysis of Western blot was also used to measure the phosphorylated and total ERK1/2 and DRP1 protein expression levels in the rat hippocampus. In addition, immunohistochemistry revealed the distribution of ERK1/2 and DRP1 in neurons of hippocampal CA1 and CA3. Both PD98059 and Mdivi‐1 reduced the susceptibility of rats to epileptic seizures, according to behavioral findings. By inhibiting ERK1/2 phosphorylation, the Western blot revealed that PD98059 indirectly reduced the phosphorylation of DRP1 at Ser616 (p‐DRP1‐Ser616). Eventually, the ERK1/2 and DRP1 were distributed in the cytoplasm of neurons by immunohistochemistry. Inhibition of ERK1/2 signaling pathways downregulates p‐DRP1‐Ser616 expression, which could inhibit DRP1‐mediated excessive mitochondrial fission and then regulate the pathogenesis of epilepsy. [ABSTRACT FROM AUTHOR]

Aims: Seawater immersion significantly aggravated organ dysfunction following hemorrhagic shock, leading to higher mortality rate. However, the effective treatment is still unavailable in clinic. Mitochondria were involved in the onset and development of multiple organ function disorders; whether mitochondria participate in the cardiac dysfunction following seawater immersion combined with hemorrhagic shock remains poorly understood. Hence, we investigated the role and possible mechanism of mitochondria in seawater immersion combined with hemorrhage shock–induced cardiac dysfunction. Results: Mitochondrial fission protein dynamin-related protein 1 (Drp1) was activated and translocated from the cytoplasm to mitochondria in the heart following seawater immersion combined with hemorrhagic shock, leading to excessive mitochondrial fission. Excessive mitochondrial fission disrupted mitochondrial function and structure and activated mitophagy and apoptosis. At the same time, excessive mitochondrial fission resulted in disturbance of myocardial structure and hemodynamic disorders and ultimately provoked multiple organ dysfunction and high mortality. Further studies showed that the mitochondrial division inhibitor mitochondrial division inhibitor-1 can significantly reverse Drp1 mitochondrial translocation and inhibit mitochondrial fragmentation, reactive oxygen species (ROS) accumulation, mitophagy, and apoptosis and then protect circulation and vital organ functions, prolonging animal survival. Innovation: Our findings indicate that Drp1-mediated mitochondrial fission could be a novel therapeutic targets for the treatment of seawater immersion combined with hemorrhagic shock. Conclusion: Drp1 mitochondrial translocation played an important role in the cardiac dysfunction after seawater immersion combined with hemorrhage shock. Drp1-mediated excessive mitochondrial fission leads to cardiac dysfunction due to the mitochondrial structure and bioenergetics impairment. [ABSTRACT FROM AUTHOR]

Oxidative stress plays a pivotal role in the development of diabetic cardiomyopathy (DCM). Previous studies have revealed that inhibition of mitochondrial fission suppressed oxidative stress and alleviated mitochondrial dysfunction and cardiac dysfunction in diabetic mice. However, no research has confirmed whether mitochondria fission accentuates hyperglycemia‐induced cardiomyoblast oxidative stress through regulating fatty acid oxidation (FAO). We used H9c2 cardiomyoblasts exposed to high glucose (HG) 33 mM to simulate DCM in vitro. Excessive mitochondrial fission, poor cell viability, and lipid accumulation were observed in hyperglycemia‐induced H9c2 cardiomyoblasts. Also, the cells were led to oxidative stress injury, lower adenosine triphosphate (ATP) levels, and apoptosis. Dynamin‐related protein 1 (Drp1) short interfering RNA (siRNA) decreased targeted marker expression, inhibited mitochondrial fragmentation and lipid accumulation, suppressed oxidative stress, reduced cardiomyoblast apoptosis, and improved cell viability and ATP levels in HG‐exposed H9c2 cardiomyoblasts, but not in carnitine palmitoyltransferase 1 (CPT1) inhibitor etomoxir treatment cells. We also found subcellular localization of CPT1 on the mitochondrial membrane, FAO, and levels of nicotinamide adenine dinucleotide phosphate (NADPH) were suppressed after exposure to HG treatment, whereas Drp1 siRNA normalized mitochondrial CPT1, FAO, and NADPH. However, the blockade of FAO with etomoxir abolished the above effects of Drp1 siRNA in hyperglycemia‐induced H9c2 cardiomyoblasts. The preservation of mitochondrial function through the Drp1/CPT1/FAO pathway is the potential mechanism of inhibited mitochondria fission in attenuating oxidative stress injury of hyperglycemia‐induced H9c2 cardiomyoblasts. [ABSTRACT FROM AUTHOR]

Higher levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a TLR4 agonist, are associated with poor clinical outcomes in sepsis-induced acute lung injury (ALI). Little is known regarding the mechanisms by which eNAMPT is involved in ALI. Our recent work has identified a crucial role for mitochondrial dysfunction in ALI. Thus, this study aimed to determine if eNAMPT-mediated inflammatory injury is associated with the loss of mitochondrial function. Our data show that eNAMPT disrupted mitochondrial bioenergetics. This was associated with cytoskeleton remodeling and the loss of endothelial barrier integrity. These changes were associated with enhanced mitochondrial fission and blocked when Rho-kinase (ROCK) was inhibited. The increases in mitochondrial fission were also associated with the nitration-mediated activation of the small GTPase activator of ROCK, RhoA. Blocking RhoA nitration decreased eNAMPT-mediated mitochondrial fission and endothelial barrier dysfunction. The increase in fission was linked to a RhoA-ROCK mediated increase in Drp1 (dynamin-related protein 1) at serine(S)616. Another TLR4 agonist, lipopolysaccharide (LPS), also increased mitochondrial fission in a Drp1 and RhoA-ROCK-dependent manner. To validate our findings in vivo , we challenged C57BL/6 mice with eNAMPT in the presence and absence of the Drp1 inhibitor, Mdivi-1. Mdivi-1 treatment protected against eNAMPT-induced lung inflammation, edema, and lung injury. These studies demonstrate that mitochondrial fission-dependent disruption of mitochondrial function is essential in TLR4-mediated inflammatory lung injury and identify a key role for RhoA-ROCK signaling. Reducing mitochondrial fission could be a potential therapeutic strategy to improve ARDS outcomes. [Display omitted] • eNAMPT disrupts endothelial barrier integrity and mitochondrial function in pulmonary endothelial cells. • Mitochondrial fission induced by eNAMPT depends on actin cytoskeleton remodeling via Rho-kinase (ROCK). • eNAMPT increases superoxide generation, subsequently activating the small GTPase activator of ROCK (RhoA) via nitration. • Activation of RhoA contributes to the effects of eNAMPT on mitochondrial network dynamics through the activation of Drp1. • Drp1 inhibition is protective against eNAMPT-induced inflammatory lung injury in mice. [ABSTRACT FROM AUTHOR]

The mitochondrial distribution and morphology family 33 gene (MDM33) regulates mitochondrial homeostasis by mediating the mitochondrial fission process in yeast. The wheat head blight Fusarium graminearum contains an FgMdm33 protein that is orthologous to Saccharomyces cerevisiae Mdm33, albeit its function remains unknown. We have reported here the roles of FgMdm33 in regulating fungal morphogenesis, mitochondrial morphology, autophagy, apoptosis, and fungal pathogenicity. The ΔFgmdm33 mutants generated through a homologous recombination strategy in this study exhibited defects in terms of mycelial growth, conidia production, and virulence. Hyphal cells lacking FgMDM33 displayed elongated mitochondria and a dispensable respiratory-deficient growth phenotype, indicating the possible involvement of FgMDM33 in mitochondrial fission. The ΔFgmdm33 mutants displayed a remarkable reduction in the proteolysis of GFP-FgAtg8, whereas the formation of autophagic bodies in the hyphal cells of mutants was recorded under the induction of mitophagy. In addition, the transcriptional expression of the apoptosis-inducing factor 1 gene (FgAIF1) was significantly upregulated in the ΔFgmdm33 mutants. Cumulatively, these results indicate that FgMDM33 is involved in mitochondrial fission, non-selective macroautophagy, and apoptosis and that it regulates fungal growth, conidiation, and pathogenicity of the head blight pathogen. [ABSTRACT FROM AUTHOR]

Background: Mutations in several translation initiation factors are closely associated with premature ovarian insufficiency (POI), but the underlying pathogenesis remains largely unknown. Methods and results: We generated eukaryotic translation initiation factor 5 (Eif5) conditional knockout mice aiming to investigate the function of eIF5 during oocyte growth and follicle development. Here, we demonstrated that Eif5 deletion in mouse primordial and growing oocytes both resulted in the apoptosis of oocytes within the early‐growing follicles. Further studies revealed that Eif5 deletion in oocytes downregulated the levels of mitochondrial fission‐related proteins (p‐DRP1, FIS1, MFF and MTFR) and upregulated the levels of the integrated stress response‐related proteins (AARS1, SHMT2 and SLC7A1) and genes (Atf4, Ddit3 and Fgf21). Consistent with this, Eif5 deletion in oocytes resulted in mitochondrial dysfunction characterized by elongated form, aggregated distribution beneath the oocyte membrane, decreased adenosine triphosphate content and mtDNA copy numbers, and excessive accumulation of reactive oxygen species (ROS) and mitochondrial superoxide. Meanwhile, Eif5 deletion in oocytes led to a significant increase in the levels of DNA damage response proteins (γH2AX, p‐CHK2 and p‐p53) and proapoptotic proteins (PUMA and BAX), as well as a significant decrease in the levels of anti‐apoptotic protein BCL‐xL. Conclusion: These findings indicate that Eif5 deletion in mouse oocytes results in the apoptosis of oocytes within the early‐growing follicles via mitochondrial fission defects, excessive ROS accumulation and DNA damage. This study provides new insights into pathogenesis, genetic diagnosis and potential therapeutic targets for POI. Key points: Eif5 deletion in oocytes leads to arrest in oocyte growth and follicle development.Eif5 deletion in oocytes impairs the translation of mitochondrial fission‐related proteins, followed by mitochondrial dysfunction.Depletion of Eif5 causes oocyte apoptosis via ROS accumulation and DNA damage response pathway. [ABSTRACT FROM AUTHOR]

Mitochondrial fission and fusion are vital dynamic processes for mitochondrial quality control and for the maintenance of cellular respiration; they also play an important role in the formation and maintenance of cells with high energy demand including cardiomyocytes and neurons. The DNM1L (dynamin-1 like) gene encodes for the DRP1 protein, an evolutionary conserved member of the dynamin family that is responsible for the fission of mitochondria; it is ubiquitous but highly expressed in the developing neonatal heart. De novo heterozygous pathogenic variants in the DNM1L gene have been previously reported to be associated with neonatal or infantile-onset encephalopathy characterized by hypotonia, developmental delay and refractory epilepsy. However, cardiac involvement has been previously reported only in one case. Next-Generation Sequencing (NGS) was used to genetically assess a baby girl characterized by developmental delay with spastic–dystonic, tetraparesis and hypertrophic cardiomyopathy of the left ventricle. Histochemical analysis and spectrophotometric determination of electron transport chain were performed to characterize the muscle biopsy; moreover, the morphology of mitochondria and peroxisomes was evaluated in cultured fibroblasts as well. Herein, we expand the phenotype of DNM1L-related disorder, describing the case of a girl with a heterozygous mutation in DNM1L and affected by progressive infantile encephalopathy, with cardiomyopathy and fatal paroxysmal vomiting correlated with bulbar transitory abnormal T2 hyperintensities and diffusion-weighted imaging (DWI) restriction areas, but without epilepsy. In patients with DNM1L mutations, careful evaluation for cardiac involvement is recommended. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) is an acute and severe clinical complication lacking effective therapeutic interventions. The disruption of the lung epithelial barrier plays a crucial role in ARDS pathogenesis. Recent studies have proposed the involvement of abnormal mitochondrial dynamics mediated by dynamin-related protein 1 (Drp1) in the mechanism of impaired epithelial barrier in ARDS. Hydrogen is an anti-oxidative stress molecule that regulates mitochondrial function via multiple signaling pathways. Our previous study confirmed that hydrogen modulated oxidative stress and attenuated acute pulmonary edema in ARDS by upregulating thioredoxin 1 (Trx1) expression, but the exact mechanism remains unclear. This study aimed to investigate the effects of hydrogen on mitochondrial dynamics both in vivo and in vitro. Our study revealed that hydrogen inhibited lipopolysaccharide (LPS)-induced phosphorylation of Drp1 (at Ser616), suppressed Drp1-mediated mitochondrial fission, alleviated epithelial tight junction damage and cell apoptosis, and improved the integrity of the epithelial barrier. This process was associated with the upregulation of Trx1 in lung epithelial tissues of ARDS mice by hydrogen. In addition, hydrogen treatment reduced the production of reactive oxygen species in LPS-induced airway epithelial cells (AECs) and increased the mitochondrial membrane potential, indicating that the mitochondrial dysfunction was restored. Then, the expression of tight junction proteins occludin and zonula occludens 1 was upregulated, and apoptosis in AECs was alleviated. Remarkably, the protective effects of hydrogen on the mitochondrial and epithelial barrier were eliminated after applying the Trx1 inhibitor PX-12. The results showed that hydrogen significantly inhibited the cell apoptosis and the disruption of epithelial tight junctions, maintaining the integrity of the epithelial barrier in mice of ARDS. This might be related to the inhibition of Drp1-mediated mitochondrial fission through the Trx1 pathway. The findings of this study provided a new theoretical basis for the application of hydrogen in the clinical treatment of ARDS. [Display omitted] • Hydrogen could alleviate impaired lung epithelial barrier in Acute Respiratory Distress Syndrome (ARDS). • Drp1-mediated mitochondrial fission in ARDS is a compensatory mechanism. • Hydrogen alleviates ARDS lung injury via inhibiting Drp1-mediated mitochondrial fission through the Trx1 pathway. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) predominantly affects the brain, causing a mixed movement disorder, cognitive decline and behavioural abnormalities. It also causes a peripheral phenotype involving skeletal muscle. Mitochondrial dysfunction has been reported in tissues of HD models, including skeletal muscle, and lymphoblast and fibroblast cultures from patients with HD. Mutant huntingtin protein (mutHTT) expression can impair mitochondrial quality control and accelerate mitochondrial ageing. Here, we obtained fresh human skeletal muscle, a post-mitotic tissue expressing the mutated HTT allele at physiological levels since birth, and primary cell lines from HTT CAG repeat expansion mutation carriers and matched healthy volunteers to examine whether such a mitochondrial phenotype exists in human HD. Using ultra-deep mitochondrial DNA (mtDNA) sequencing, we showed an accumulation of mtDNA mutations affecting oxidative phosphorylation. Tissue proteomics indicated impairments in mtDNA maintenance with increased mitochondrial biogenesis of less efficient oxidative phosphorylation (lower complex I and IV activity). In full-length mutHTT expressing primary human cell lines, fission-inducing mitochondrial stress resulted in normal mitophagy. In contrast, expression of high levels of N-terminal mutHTT fragments promoted mitochondrial fission and resulted in slower, less dynamic mitophagy. Expression of high levels of mutHTT fragments due to somatic nuclear HTT CAG instability can thus affect mitochondrial network dynamics and mitophagy, leading to pathogenic mtDNA mutations. We show that life-long expression of mutant HTT causes a mitochondrial phenotype indicative of mtDNA instability in fresh post-mitotic human skeletal muscle. Thus, genomic instability may not be limited to nuclear DNA, where it results in somatic expansion of the HTT CAG repeat length in particularly vulnerable cells such as striatal neurons. In addition to efforts targeting the causative mutation, promoting mitochondrial health may be a complementary strategy in treating diseases with DNA instability such as HD. [ABSTRACT FROM AUTHOR]

Background: The larval zebrafish tail fin can completely regenerate in 3 days post amputation. mTOR, the main regulator of cell growth and metabolism, plays an essential role in regeneration. Lots of studies have documented the role of mTOR in regeneration. However, the mechanisms involved are still not fully elucidated. Materials and results: This study aimed to explore the role and mechanism of mTOR in the regeneration of larval zebrafish tail fins. Initially, the spatial and temporal expression of mTOR signaling in the larval fin was examined, revealing its activation following tail fin amputation. Subsequently, a mTOR knockout (mTOR-KO) zebrafish line was created using CRISPR/Cas9 gene editing technology. The investigation demonstrated that mTOR depletion diminished the proliferative capacity of epithelial and mesenchymal cells during fin regeneration, with no discernible impact on cell apoptosis. Insight from SMART-seq analysis uncovered alterations in the cell cycle, mitochondrial functions and metabolic pathways when mTOR signaling was suppressed during fin regeneration. Furthermore, mTOR was confirmed to enhance mitochondrial functions and Ca2 + activation following fin amputation. These findings suggest a potential role for mTOR in promoting mitochondrial fission to facilitate tail fin regeneration. Conclusion: In summary, our results demonstrated that mTOR played a key role in larval zebrafish tail fin regeneration, via promoting mitochondrial fission and proliferation of blastema cells. [ABSTRACT FROM AUTHOR]

Background: Cartilaginous endplate (CEP) degeneration, which is an important contributor to intervertebral disc degeneration (IVDD), is characterized by chondrocyte death. Accumulating evidence has revealed that dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and dysfunction lead to apoptosis during CEP degeneration and IVDD. Exosomes are promising agents for the treatment of many diseases, including osteoporosis, osteosarcoma, osteoarthritis and IVDD. Despite their major success in drug delivery, the full potential of exosomes remains untapped. Materials and methods: In vitro and in vivo models of CEP degeneration were established by using lipopolysaccharide (LPS). We designed genetically engineered exosomes (CAP-Nrf2-Exos) expressing chondrocyte-affinity peptide (CAP) on the surface and carrying the antioxidant transcription factor nuclear factor E2-related factor 2 (Nrf2). The affinity between CAP-Nrf2-Exos and CEP was evaluated by in vitro internalization assays and in vivo imaging assays. qRT‒PCR, Western blotting and immunofluorescence assays were performed to examine the expression level of Nrf2 and the subcellular localization of Nrf2 and Drp1. Mitochondrial function was measured by the JC-1 probe and MitoSOX Red. Mitochondrial morphology was visualized by MitoTracker staining and transmission electron microscopy (TEM). After subendplate injection of the engineered exosomes, the degree of CEP degeneration and IVDD was validated radiologically and histologically. Results: We found that the cargo delivery efficiency of exosomes after cargo packaging was increased by surface modification. CAP-Nrf2-Exos facilitated chondrocyte-targeted delivery of Nrf2 and activated the endogenous antioxidant defence system in CEP cells. The engineered exosomes inhibited Drp1 S616 phosphorylation and mitochondrial translocation, thereby preventing mitochondrial fragmentation and dysfunction. LPS-induced CEP cell apoptosis was alleviated by CAP-Nrf2-Exo treatment. In a rat model of CEP degeneration, the engineered exosomes successfully attenuated CEP degeneration and IVDD and exhibited better repair capacity than natural exosomes. Conclusion: Collectively, our findings showed that exosome-mediated chondrocyte-targeted delivery of Nrf2 was an effective strategy for treating CEP degeneration. [ABSTRACT FROM AUTHOR]

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic interstitial lung diseases, which mainly existed in middle-aged and elderly people. The accumulation of reactive oxygen species (ROS) is a common characteristic of IPF. Previous research also shown that lactate levels can be abnormally elevated in IPF patients. Emerging evidence suggested a relationship between lactate and ROS in IPF which needs further elucidation. In this article, we utilized a mouse model of BLM-induced pulmonary fibrosis to detect alterations in ROS levels and other indicators associated with fibrosis. Lactate could induce mitochondrial fragmentation by modulating expression and activity of DRP1 and ERK. Moreover, Increased ROS promoted P65 translocation into nucleus, leading to expression of lung fibrotic markers. Finally, Ulixertinib, Mdivi-1 and Mito-TEMPO, which were inhibitor activity of ERK, DRP1 and mtROS, respectively, could effectively prevented mitochondrial damage and production of ROS and eventually alleviate pulmonary fibrosis. Taken together, these findings suggested that lactate could promote lung fibrosis by increasing mitochondrial fission-derived ROS via ERK/DRP1 signaling, which may provide novel therapeutic solutions for IPF. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mitochondrial quality control is a complex process, which involves three aspects: mitochondrial biogenesis, mitochondrial dynamics change and mitochondrial autophagy, among which mitochondrial dynamics change is the intermediate link between mitochondrial biogenesis and mitochondrial autophagy. Mitochondria can improve their own quality control through dynamics change and then maintain their stable state. OBJECTIVE: To explore the molecular mechanism underlying the influence of exercise on mitochondrial dynamics, so as to provide theoretical basis for improving mitochondrial network homeostasis and promoting functional health. METHODS: Using the method of literature review, CNKI, Bailianyun Library, PubMed, Web of Science, EBCSO were searched for relevant literature with the keywords of “Exercise, Mitochondrial Steady State, Mitochondrial Quality Control, Mitochondrial Dynamics, Mitochondrial Fusion and Mitochondrial Division” in Chinese and English. The finally obtained literature was screened, read, and summarized. RESULTS AND CONCLUSION: Dynamin-related proteins 1/2 are responsible for mitochondrial fission, while mitofusins 1/2 and optic atrophy type 1 mediate the fusion of outer membrane and inner mitochondrial membranes respectively. Exercise training can improve the function of mitochondria by up-regulating the protein expression of mitofusins 1/2 and optic atrophy type 1 and down-regulating the protein expression level of dynamin-related protein 1, promoting mitochondrial fusion and inhibiting mitochondrial fission. The findings that a single acute exercise affects changes in mitochondrial dynamics are controversial. Furthermore, there is tissue variability in exercise-mediated changes in mitochondrial dynamics. [ABSTRACT FROM AUTHOR]

Although the death of hepatocytes is a crucial trigger of liver ischemia–reperfusion (I/R) injury, the regulation of liver I/R-induced hepatocyte death is still poorly understood. Phosphoglycerate mutase 5 (PGAM5), a mitochondrial Serine/Threonine protein phosphatase, regulates mitochondrial dynamics and is involved in the process of both apoptosis and necrotic. However, it is still unclear what role PGAM5 plays in the death of hepatocytes induced by I/R. Using a PGAM5-silence mice model, we investigated the role of PGAM5 in liver I/R injury and its relevant molecular mechanisms. Our data showed that PGAM5 was highly expressed in mice with liver I/R injury. Silence of PGAM5 could decrease I/R-induced hepatocyte death in mice. In subcellular levels, the silence of PGAM5 could restore mitochondrial membrane potential, increase mitochondrial DNA copy number and transcription levels, inhibit ROS generation, and prevent I/R-induced opening of abnormal mPTP. As for the molecular mechanisms, we indicated that the silence of PGAM5 could inhibit Drp1(S616) phosphorylation, leading to a partial reduction of mitochondrial fission. In addition, Mdivi-1 could inhibit mitochondrial fission, decrease hepatocyte death, and attenuate liver I/R injury in mice. In conclusion, our data reveal the molecular mechanism of PGAM5 in driving hepatocyte death through activating mitochondrial fission in liver I/R injury. [ABSTRACT FROM AUTHOR]

Mitochondria constantly fuse and divide for mitochondrial inheritance and functions. Here, we identified a distinct type of naturally occurring fission, tail-autotomy fission, wherein a tail-like thin tubule protrudes from the mitochondrial body and disconnects, resembling autotomy. Next, utilizing an optogenetic mitochondria-specific mechanostimulator, we revealed that mechanical tensile force drives tail-autotomy fission. This force-induced fission involves DRP1/MFF and endoplasmic reticulum tubule wrapping. It redistributes mitochondrial DNA, producing mitochondrial fragments with or without mitochondrial DNA for different fates. Moreover, tensile force can decouple outer and inner mitochondrial membranes, pulling out matrix-excluded tubule segments. Subsequent tail-autotomy fission separates the matrix-excluded tubule segments into matrix-excluded mitochondrial-derived vesicles (MDVs) which recruit Parkin and LC3B, indicating the unique role of tail-autotomy fission in segregating only outer membrane components for mitophagy. Sustained force promotes fission and MDV biogenesis more effectively than transient one. Our results uncover a mechanistically and functionally distinct type of fission and unveil the role of tensile forces in modulating fission and MDV biogenesis for quality control, underscoring the heterogeneity of fission and mechanoregulation of mitochondrial dynamics. [ABSTRACT FROM AUTHOR]

Introduction: Hypoxia is an important characteristic of gastric mucosal diseases, and hypoxia‐inducible factor‐1α (HIF‐1α) contributes to microenvironment disturbance and metabolic spectrum abnormalities. However, the underlying mechanism of HIF‐1α and its association with mitochondrial dysfunction in gastric mucosal lesions under hypoxia have not been fully clarified. Objectives: To evaluate the effects of hypoxia‐induced HIF‐1α on the development of gastric mucosal lesions. Methods: Portal hypertensive gastropathy (PHG) and gastric cancer (GC) were selected as representative diseases of benign and malignant gastric lesions, respectively. Gastric tissues from patients diagnosed with the above diseases were collected. Portal hypertension (PHT)‐induced mouse models in METTL3 mutant or NLRP3‐deficient littermates were established, and nude mouse gastric graft tumour models with relevant inhibitors were generated. The mechanisms underlying hypoxic condition, mitochondrial dysfunction and metabolic alterations in gastric mucosal lesions were further analysed. Results: HIF‐1α, which can mediate mitochondrial dysfunction via upregulation of METTL3/IGF2BP3‐dependent dynamin‐related protein 1 (Drp1) N6‐methyladenosine modification to increase mitochondrial reactive oxygen species (mtROS) production, was elevated under hypoxic conditions in human and mouse portal hypertensive gastric mucosa and GC tissues. While blocking HIF‐1α with PX‐478, inhibiting Drp1‐dependent mitochondrial fission via mitochondrial division inhibitor 1 (Mdivi‐1) treatment or METTL3 mutation alleviated this process. Furthermore, HIF‐1α influenced energy metabolism by enhancing glycolysis via lactate dehydrogenase A. In addition, HIF‐1α‐induced Drp1‐dependent mitochondrial fission also enhanced glycolysis. Drp1‐dependent mitochondrial fission and enhanced glycolysis were associated with alterations in antioxidant enzyme activity and dysfunction of the mitochondrial electron transport chain, resulting in massive mtROS production, which was needed for activation of NLRP3 inflammasome to aggravate the development of the PHG and GC. Conclusions: Under hypoxic conditions, HIF‐1α enhances mitochondrial dysfunction via Drp1‐dependent mitochondrial fission and influences the metabolic profile by altering glycolysis to increase mtROS production, which can trigger NLRP3 inflammasome activation and mucosal microenvironment alterations to contribute to the development of benign and malignant gastric mucosal lesions. [ABSTRACT FROM AUTHOR]

Worldwide, myocardial infarction (MI) is the leading cause of death and disability-adjusted life years lost. Recent researches explored new methods of detecting biomarkers that can predict the risk of developing myocardial infarction, which includes identifying genetic markers associated with increased risk. We induced myocardial infarction in mice by occluding the left anterior descending coronary artery and performed TTC staining to assess cell death. Next, we performed ChIP assays to measure the enrichment of histone modifications at the promoter regions of key genes involved in mitochondrial fission. We used qPCR and western blot to measure expression levels of relative apoptotic indicators. We report that miR-181a inhibits myocardial ischemia-induced apoptosis and preserves left ventricular function after MI. We show that programmed cell death protein 4 (PDCD4) is the target gene involved in miR-181a-mediated anti-ischemic injury, which enhanced BID recruitment to the mitochondria. In addition, we discovered that p53 inhibits the expression of miR-181a via transcriptional regulation. Here, we discovered for the first time a mitochondrial fission and apoptosis pathway which is controlled by miR-181a and involves PDCD4 and BID. This pathway may be controlled by p53 transcriptionally, and we presume that miR-181a may lead to the discovery of new therapeutic and preventive targets for ischemic heart diseases. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cardiac hypertrophy is an adaptive response of the heart to physiological and pathological stimuli such as pressure overload. It is of compensatory significance in the early stage, but if the stimulation continues, it can cause cardiomyopathy leading to heart failure. MicroRNAs are involved in the regulation of cardiac hypertrophy. However, the role of miR-20a in pressure overload-induced cardiac hypertrophy has not been reported. OBJECTIVE: To investigate the role of miR-20a in pressure overload-induced cardiac hypertrophy and the underlying mechanisms. METHODS: Transverse aortic constriction was used to induce cardiac hypertrophy in vivo and angiotensin II was used to induce H9c2 cell models of cardiac hypertrophy in vitro. MiR-20a was overexpressed in vivo by intramyocardial injection of miR-20a overexpressing adenovirus and in vitro by transfecting miR20a mimic into H9c2 cells. Cardiac hypertrophy was assessed by measuring heart weight/body weight ratio, cell surface area, and myocardial fibrosis. The expression levels of atrial natriuretic peptide, brain natriuretic peptide, β-myosin heavy chain and miR-20a were detected by real-time fluorescence quantitative PCR. Mitochondrial fission was detected by MitoTracker. The downstream target genes of miR-20a were predicted by RNAhybrid software. RESULTS AND CONCLUSION: (1) The expression level of miR-20a was significantly decreased in both hypertrophic cardiomyocytes and hearts (P < 0.05). (2) At the animal level, overexpression of miR-20a significantly inhibited transverse aortic constriction-induced cardiac hypertrophy, including decreasing the upregulated expression level of hypertrophic marker genes (P < 0.05), reduced the enlarged heart volume, reducing the increased heart weight/body weight ratio (P < 0.01), reducing the increased myocardial cross-sectional area (P < 0.05), and attenuating fibrosis (P < 0.01). (3) At the cellular level, overexpression of miR-20a significantly inhibited angiotensin II-induced cardiomyocyte hypertrophy, including decreasing the upregulated expression levels of atrial natriuretic peptide (P < 0.05), brain natriuretic peptide (P < 0.01) and β-myosin heavy chain (P < 0.05), reducing the increased protein/DNA ratio (P < 0.01), and suppressing the increased cell surface area (P < 0.05). (4) Overexpression of miR-20a significantly inhibited angiotensin II-induced mitochondrial fission (P < 0.05). (5) The results of RNAhybrid software analysis showed that miR-20a and the mRNA 3’ untranslated region of cAMP-dependent protein kinase inhibitor alpha were well complementary and the predicted binding sites were highly conserved. (6) In conclusion, miR-20a is significantly down-regulated in pressure overload-induced cardiac hypertrophy. Overexpression of miR-20a inhibits cardiac hypertrophy at both the cellular level and animal level and attenuates angiotensin II-induced mitochondrial fission. [ABSTRACT FROM AUTHOR]

Objectives: FTO is known to be involved in cerebral ischemia/reperfusion (I/R) injury. However, its related specific mechanisms during this condition warrant further investigations. This study aimed at exploring the impacts of FTO and the FYN/DRP1 axis on mitochondrial fission, oxidative stress (OS), and ferroptosis in cerebral I/R injury and the underlying mechanisms. Methods: The cerebral I/R models were established in mice via the temporary middle cerebral artery occlusion/reperfusion (tMCAO/R) and hypoxia/reoxygenation models were induced in mouse hippocampal neurons via oxygen–glucose deprivation/reoxygenation (OGD/R). After the gain‐ and loss‐of‐function assays, related gene expression was detected, along with the examination of mitochondrial fission, OS‐ and ferroptosis‐related marker levels, neuronal degeneration and cerebral infarction, and cell viability and apoptosis. The binding of FTO to FYN, m6A modification levels of FYN, and the interaction between FYN and Drp1 were evaluated. Results: FTO was downregulated and FYN was upregulated in tMCAO/R mouse models and OGD/R cell models. FTO overexpression inhibited mitochondrial fission, OS, and ferroptosis to suppress cerebral I/R injury in mice, which was reversed by further overexpressing FYN. FTO overexpression also suppressed mitochondrial fission and ferroptosis to increase cell survival and inhibit cell apoptosis in OGD/R cell models, which was aggravated by additionally inhibiting DRP1. FTO overexpression inhibited FYN expression via the m6A modification to inactive Drp1 signaling, thus reducing mitochondrial fission and ferroptosis and enhancing cell viability in cells. Conclusions: FTO overexpression suppressed FYN expression through m6A modification, thereby subduing Drp1 activity and relieving cerebral I/R injury. [ABSTRACT FROM AUTHOR]

Aims: To investigate the role of FOXO1 in STAT3 activation and mitochondrial quality control in the diabetic heart. Methods: Type 1 diabetes mellitus (T1DM) was induced in rats by a single intraperitoneal injection of 60 mg · kg−1 streptozotocin (STZ), while type 2 diabetes mellitus (T2DM) was induced in rats with a high‐fat diet through intraperitoneal injection of 35 mg · kg−1 STZ. Primary neonatal mouse cardiomyocytes and H9c2 cells were exposed to low glucose (5.5 mM) or high glucose (HG; 30 mM) with or without treatment with the FOXO1 inhibitor AS1842856 (1 μM) for 24 hours. In addition, the diabetic db/db mice (aged 8 weeks) and sex‐ and age‐matched non‐diabetic db/+ mice were treated with vehicle or AS1842856 by oral gavage for 15 days at a dose of 5 mg · kg−1 · d−1. Results: Rats with T1DM or T2DM had excessive cardiac FOXO1 activation, accompanied by decreased STAT3 activation. Immunofluorescence and immunoprecipitation analysis showed colocalization and association of FOXO1 and STAT3 under basal conditions in isolated cardiomyocytes. Selective inhibition of FOXO1 activation by AS1842856 or FOXO1 siRNA transfection improved STAT3 activation, mitophagy and mitochondrial fusion, and decreased mitochondrial fission in isolated cardiomyocytes exposed to HG. Transfection with STAT3 siRNA further reduced mitophagy, mitochondrial fusion and increased mitochondrial fission in HG‐treated cardiomyocytes. AS1842856 alleviated cardiac dysfunction, pathological damage and improved STAT3 activation, mitophagy and mitochondrial dynamics in diabetic db/db mice. Additionally, AS1842856 improved mitochondrial function indicated by increased mitochondrial membrane potential and adenosine triphosphate production and decreased mitochondrial reactive oxygen species production in isolated cardiomyocytes exposed to HG. Conclusions: Excessive FOXO1 activation during diabetes reduces STAT3 activation, with subsequent impairment of mitochondrial quality, ultimately promoting the development of diabetic cardiomyopathy. [ABSTRACT FROM AUTHOR]

The cytoplasm of eukaryotes is dynamically zoned by membrane-bound and membraneless organelles. Cytoplasmic zoning allows various biochemical reactions to take place at the right time and place. Mitochondrion is a membrane-bound organelle that provides a zone for intracellular energy production and metabolism of lipids and iron. A key feature of mitochondria is their high dynamics: mitochondria constantly undergo fusion and fission, and excess or damaged mitochondria are selectively eliminated by mitophagy. Therefore, mitochondria are appropriate model systems to understand dynamic cytoplasmic zoning by membrane organelles. In this review, we summarize the molecular mechanisms of mitochondrial fusion and fission as well as mitophagy unveiled through studies using yeast and mammalian models. [ABSTRACT FROM AUTHOR]

Purpose: Though exercise generates beneficial effects on diabetes‐associated cardiac damage, the underlying mechanism is largely unclear. Therefore, we prescribed a program of 8‐week treadmill training for type 2 diabetes mellitus (T2DM) rats and determined the role of irisin signaling, via interacting with AMP‐activated protein kinase (AMPK), in mediating the effects of exercise on myocardial injuries and mitochondrial fission. Methods: Forty 8‐week‐old male Wistar rats were randomly divided into groups of control (Con), diabetes mellitus (DM), diabetes plus exercise (Ex), and diabetes plus exercise and Cyclo RGDyk (ExRg). Ex and ExRg rats received 8 weeks of treadmill running, and the rats in the ExRg group additionally were treated with a twice weekly injection of Cyclo RGDyk, an irisin receptor‐αV/β5 antagonist. At the end of the experiment, murine blood samples and heart tissues were collected and analyzed with methods of ELISA, Western blot, real‐time quantitative polymerase chain reaction, as well as immunofluorescence staining. Results: Exercise effectively mitigated T2DM‐related hyperglycemia, hyperinsulinemia, lipid dysmetabolism, and inflammation, which could be diminished by Cyclo RGDyk treatment. Additionally, exercise alleviated T2DM‐induced myocardial injury and excessive mitochondrial fission, whereas the beneficial effects were blocked by the administration of Cyclo RGDyk. T2DM significantly decreased serum irisin concentrations and fibronectin type III domain‐containing protein 5 (FNDC5)/irisin gene and protein expression levels in the rat heart, whereas exercise could rescue T2DM‐reduced FNDC5/irisin expression. Blocking irisin receptor signaling diminished the exercise‐alleviated mitochondrial fission protein expression and elevated AMPK phosphorylation. Conclusion: Exercise is effective in mitigating diabetes‐related insulin resistance, metabolic dysfunction, and inflammation. Irisin signaling engages in exercise‐associated beneficial effects on myocardial injury and excessive mitochondrial fission in diabetes rats involving elevated AMPK phosphorylation. [ABSTRACT FROM AUTHOR]

Novel components of the mitochondrial fission machinery, mitochondrial dynamics proteins of 49 kDa (MiD49) and 51 kDa (MiD51), have been recently described, and their potential therapeutic targets for treating cardiovascular disease have been shown, including acute myocardial infarction (AMI), anthracycline cardiomyopathy and pulmonary arterial hypertension (PAH). Here, we examined the role of MiD49 and MiD51 in atherosclerosis. MiD49/51 expression was increased in the aortic valve endothelial cells (ECs) of high-fat diet-induced atherosclerosis in ApoE-/-mice and IL-8-induced human umbilical vein endothelial cells (HUVECs), which accelerated dynamin-related protein 1 (Drp1)-mediated mitochondrial fission. Silencing MiD49/51 reduced atherosclerotic plaque size, increased collagen content, and decreased the IL-8-induced adhesion and proliferation of HUVECs. MiD51 upregulation resulted from decreased microRNA (miR)-107 expression and increased hypoxia-inducible factor-1a (HIF-1a) expression. Treatment with miR-107 mimics decreased atherosclerotic plaque size by reducing HIF-1α and MiD51 production. Both MiD49 and MiD51 were involved in atherosclerotic plaque formation through Drp1-mediated mitochondrial fission, and the involvement of MiD51 in this process was the result of decreased miR-107 expression and increased HIF-1α expression. The miR-107–HIF-1α–MiD51 pathway might provide new therapeutic targets for atherosclerosis. [ABSTRACT FROM AUTHOR]

Excessive mitochondrial fission following ischemia and hypoxia relies on the formation of contacts between the endoplasmic reticulum and mitochondria (ER‐Mito); however, the specific mechanisms behind this process remain unclear. Confocal microscopy and time course recording are used to investigate how ischemia and hypoxia affect the activation of dynamin‐related protein 1 (Drp1), a protein central to mitochondrial dynamics, ER‐Mito interactions, and the consequences of modifying the expression of Drp1, shroom (Shrm) 4, and inverted formin (INF) 2 on ER‐Mito contact establishment. Both Drp1 activation and ER‐Mito contact initiation cause excessive mitochondrial fission and dysfunction under ischemic‐hypoxic conditions. The activated form of Drp1 aids in ER‐Mito contact initiation by recruiting Shrm4 and promoting actin bundling between the ER and mitochondria. This process relies on the structural interplay between INF2 and scattered F‐actin on the ER. This study uncovers new roles of cytoplasmic Drp1, providing valuable insights for devising strategies to manage mitochondrial imbalances in the context of ischemic‐hypoxic injury. [ABSTRACT FROM AUTHOR]

Background: Type 2 diabetes mellitus (T2DM) induced diabetes-associated cognitive dysfunction (DACD) that seriously affects the self-management of T2DM patients, is currently one of the most severe T2DM-associated complications, but the mechanistic basis remains unclear. Mitochondria are highly dynamic organelles, whose function refers to a broad spectrum of features such as mitochondrial dynamics, mitophagy and so on. Mitochondrial abnormalities have emerged as key determinants for cognitive function, the relationship between DACD and mitochondria is not well understood. Methods: Here, we explored the underlying mechanism of mitochondrial dysfunction of T2DM mice and HT22 cells treated with high glucose/palmitic acid (HG/Pal) focusing on the mitochondrial fission-mitophagy axis with drug injection, western blotting, Immunofluorescence, and electron microscopy. We further explored the potential role of caveolin-1 (cav-1) in T2DM induced mitochondrial dysfunction and synaptic alteration through viral transduction. Results: As previously reported, T2DM condition significantly prompted hippocampal mitochondrial fission, whereas mitophagy was blocked rather than increasing, which was accompanied by dysfunctional mitochondria and impaired neuronal function. By contrast, Mdivi-1 (mitochondrial division inhibitor) and urolithin A (mitophagy activator) ameliorated mitochondrial and neuronal function and thereafter lead to cognitive improvement by inhibiting excessive mitochondrial fission and giving rise to mitophagy, respectively. We have previously shown that cav-1 can significantly improve DACD by inhibiting ferroptosis. Here, we further demonstrated that cav-1 could not only inhibit mitochondrial fission via the interaction with GSK3β to modulate Drp1 pathway, but also rescue mitophagy through interacting with AMPK to activate PINK1/Parkin and ULK1-dependent signlings. Conclusions: Overall, our data for the first time point to a mitochondrial fission-mitophagy axis as a driver of neuronal dysfunction in a phenotype that was exaggerated by T2DM, and the protective role of cav-1 in DACD. Graphic Summary Illustration. In T2DM, excessive mitochondrial fission and impaired mitophagy conspire to an altered mitochondrial morphology and mitochondrial dysfunction, with a consequent neuronal damage, overall suggesting an unbalanced mitochondrial fission-mitophagy axis. Upon cav-1 overexpression, GSK3β and AMPK are phosphorylated respectively to activate Drp1 and mitophagy-related pathways (PINK1 and ULKI), ultimately inhibits mitochondrial fission and enhances mitophagy. In the meantime, the mitochondrial morphology and neuronal function are rescued, indicating the protective role of cav-1 on mitochondrial fission-mitophagy axis. 4fVNd5UMHP9GEmZKs4s8VH Video Abstract [ABSTRACT FROM AUTHOR]

Background: Ovarian cancer is often characterized by aggressive growth and chemoresistance, leading to a poor prognosis. The energy and nutrient acquisition through metabolic reprogramming has been reported to facilitate cancer cell proliferation, invasion, and metastasis. Therefore, a therapeutic strategy to consider is to rewire energy metabolism. Mitochondrial dynamics have a profound impact on the metabolic profiles. In this review, we summarize the current understanding of the molecular mechanisms governing mitochondrial dynamics and their impact on cell proliferation and invasion and discuss future perspectives for therapeutic strategies and research directions. Methods: A search was conducted for literature published up to 30 June 2023 using the online databases PubMed and Google Scholar in this narrative literature review. Results: Mitochondria are essential for regulating metabolic reprogramming to meet the increasing energy demand for rapid cancer cell proliferation and invasion. A metabolic switch from OXPHOS to glycolysis may promote invasion, and OXPHOS-driven metabolism may be associated with proliferation, chemoresistance, and stemness. Many ovarian cancer cells are known to favor glycolysis over OXPHOS, but the opposite takes place in the subpopulation of cancer cells. The preference for glycolysis versus OXPHOS in ovarian cancer cells may be determined by histopathologic types, the unique genetic profile of energy metabolism, and intrinsic (e.g., oncogenic signaling) and extrinsic (e.g., nutritional status and hypoxia) factors. Conclusions: Preclinical studies suggest that mitochondrial dynamics regulators have therapeutic potential in ovarian cancer, but some factors limit their beneficial effects. [ABSTRACT FROM AUTHOR]

The following review considers current concepts concerning the characteristics of DRP1-related mitochondrial division in brain cells during hypoxic-ischemic pathology. The functional role of DRP1 in neurons and astroglia in cerebral ischemia conditions was analyzed. We discuss the potential for regulating DRP1 activity through the selective inhibitor of mitochondrial fission, mdivi-1. The article also presents data on DRP1 involvement in astro- and microglia-mediated intercellular mitochondrial transport. Understanding of the molecular mechanisms responsible for mitochondrial fission during hypoxic-ischemic exposure will allow us to consider DRP1 as an effective therapeutic target for treating conditions with a hypoxic component. [ABSTRACT FROM AUTHOR]

Introduction: Emerging evidence suggests that mitochondrial dysfunction plays a crucial role in the pathogenesis of postoperative delayed neurocognitive recovery (dNCR). Mitochondria exist in a dynamic equilibrium that involves fission and fusion to regulate morphology and maintains normal cell function via the removal of damaged mitochondria through mitophagy. Nonetheless, the relationship between mitochondrial morphology and mitophagy, and how they influence mitochondrial function in the development of postoperative dNCR, remains poorly understood. Here, we observed morphological alterations of mitochondria and mitophagy activity in hippocampal neurons and assessed the involvement of their interaction in dNCR following general anesthesia and surgical stress in aged rats. Methods: Firstly, we evaluated the spatial learning and memory ability of the aged rats after anesthesia/surgery. Hippocampal mitochondrial function and mitochondrial morphology were detected. Afterwards, mitochondrial fission was inhibited by Mdivi‐1 and siDrp1 in vivo and in vitro separately. We then detected mitophagy and mitochondrial function. Finally, we used rapamycin to activate mitophagy and observed mitochondrial morphology and mitochondrial function. Results: Surgery impaired hippocampal‐dependent spatial learning and memory ability and caused mitochondrial dysfunction. It also increased mitochondrial fission and inhibited mitophagy in hippocampal neurons. Mdivi‐1 improved mitophagy and learning and memory ability of aged rats by inhibiting mitochondrial fission. Knocking down Drp1 by siDrp1 also improved mitophagy and mitochondrial function. Meanwhile, rapamycin inhibited excessive mitochondrial fission and improved mitochondrial function. Conclusion: Surgery simultaneously increases mitochondrial fission and inhibits mitophagy activity. Mechanistically, mitochondrial fission/fusion and mitophagy activity interact reciprocally with each other and are both involved in postoperative dNCR. These mitochondrial events after surgical stress may provide novel targets and modalities for therapeutic intervention in postoperative dNCR. [ABSTRACT FROM AUTHOR]

It has been reported that cadherin 6 (CDH6) upregulation is associated with enhanced epithelial-to-mesenchymal transition (EMT) in several types of solid tumor cells. The current study aimed to explore the effect of CDH6 on the migration and invasion of stomach adenocarcinoma (STAD) cells, the transcription factors involved in CDH6 dysregulation and their effect on mitochondrial fission. Bioinformatics analysis was performed using data extracted from the Genotype-Tissue Expression Project, the Cancer Genome Atlas and Kaplan-Meier plotter. AGS and HGC27 cells were used to establish an in vitro STAD cell model. The results showed that higher CDH6 expression was associated with significantly shorter overall survival in patients with STAD. In addition, CDH6 overexpression promoted wound healing, enhanced the invasion ability of tumor cells and increased mitochondrial fission. Glioma-associated oncogene family zinc finger 2 (GLI2) could bind to the CDH6 promoter and activate its transcription. Fluorescent labeling also showed that GLI2 overexpression promoted mitochondrial fission. However, CDH6 silencing significantly reduced mitochondrial fragmentation. Besides, GLI2 overexpression notably upregulated phosphorylated-focal adhesion kinase and dynamin-related protein 1. However, the above effects were largely abrogated by CDH6 knockdown. In conclusion, the present study suggested that the novel GLI2/CDH6 axis could enhance the migration, invasion and mitochondrial fission of STAD cells. • CDH6 upregulation was associated with poor prognosis of stomach adenocarcinoma. • CDH6 positively modulates migration, invasion and mitochondrial fission of STAD cells. • GLI2 binds to the CDH6 promoter and activates its transcription. • GLI2-CDH6 axis increases STAD cell migration, invasion and mitochondrial fission. [ABSTRACT FROM AUTHOR]

Long-term cocaine abuse is associated with cardiovascular and pulmonary vascular complications. The vascular toxicity of cocaine can lead to vascular remodeling characterized by excessive proliferation of vascular smooth muscle cells. Though hypoxia-inducible factor (HIF) signaling and mitochondrial fission have been suggested to play essential roles in the pathogenesis of hypoxia-induced vascular remodeling, pathogenetic mechanism for cocaine-related vascular remodeling remains to be elucidated. In this study, we explore the effect of cocaine on the proliferation of vascular smooth muscle cells by in vitro experiments. The findings indicated that the cocaine-induced vascular smooth muscle cell hyperproliferation is achieved by enhancing DRP1-mediated mitochondrial fission and activating PI3K/HIF-1α signaling. Current findings suggested that mitochondrial fission would play a pivotal role in cocaine-related vascular remodeling and would be helpful in understanding the vascular toxicity of cocaine. • Cocaine induces vascular smooth muscle cells (vSMCs) hyperproliferation. • Cocaine enhances DRP1-mediated mitochondrial fission in vSMCs. • Cocaine activates PI3K/HIF-1α signaling in vSMCs. • Inhibition of mitochondrial fission alleviated cocaine-induced vSMCs hyperproliferation. [ABSTRACT FROM AUTHOR]

Background: Extracellular matrix stiffness is emerging as a crucial mechanical cue that drives the progression of various diseases, such as cancer, fibrosis, and inflammation. The matrix stiffness of the nucleus pulposus (NP) tissues increase gradually during intervertebral disc degeneration (IDD), while the mechanism through which NP cells sense and react to matrix stiffness remains unclear. In addition, mitochondrial dynamics play a key role in various cellular functions. An in-depth investigation of the pathogenesis of IDD can provide new insights for the development of effective therapies. In this study, we aim to investigate the effects of matrix stiffness on mitochondrial dynamics in IDD. Methods: To build the gradient stiffness model, NP cells were cultured on polystyrene plates with different stiffness. Western blot analysis, and immunofluorescence staining were used to detect the expression of mitochondrial dynamics-related proteins. Flow cytometry was used to detect the mitochondrial membrane potential and intracellular Ca2+ levels. Apoptosis related proteins, ROS level, and TUNEL staining were performed to assess the effect of substrate stiffness on NP cells. Results: Stiff substrate increased phosphorylation of dynamin-related protein 1 (Drp1) at Ser616 by activating extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, which promoted mitochondrial fission and apoptosis in NP cells. Furthermore, Piezo1 activation was involved in the regulation of the post-translational modifications of Drp1 and mitochondrial fission caused by matrix stiffness. Inhibition of Piezo1 and ERK1/2 can effectively reduce stiffness-induced ROS elevation and apoptosis in NP cells. Conclusions: Our results revealed that stiff substrate causes Piezo1 activation and Ca2+ influx, results in ERK1/2 activation and phosphorylation of Drp1 at S616, and finally leads to mitochondrial fission and apoptosis in NP cells. These findings reveal a new mechanism of mechanotransduction in NP cells, providing novel insights into the development of therapies for treating IDD. [ABSTRACT FROM AUTHOR]

Placenta synthesizes hormones that play a vital role in adapting maternal physiology and supporting fetal growth. This study aimed to explore the link between progesterone, a key steroid hormone produced by placenta, and mitochondrial fission and protein kinase R through the use of chemical inhibition in trophoblasts subjected to endotoxin lipopolysaccharide and double-stranded RNA analog polyinosinic:polycytidylic acid stress. Expressions of protein kinase R, dynamin-related protein 1, mitochondrial fission protein 1, and heat shock protein 60 were determined by applying lipopolysaccharide and polyinosinic:polycytidylic acid to BeWo trophoblast cells. Next, cells were treated with protein kinase R inhibitor 2-aminopurine and mitochondrial division inhibitor 1 to examine changes in progesterone levels and expression levels of proteins and mRNAs involved in progesterone biosynthesis. Last, effect of 2-aminopurine on mitochondrial fission was determined by immunoblotting and quantitative PCR (qPCR). Mitochondrial structural changes were also examined by transmission electron microscopy. Lipopolysaccharide and polyinosinic:polycytidylic acid stimulation induced mitochondrial fission and activated protein kinase R but decreased heat shock protein 60 levels and progesterone synthesis. Chemical inhibition of mitochondrial fission elevated progesterone synthesis and protein and mRNA levels of genes involved in progesterone biosynthesis. Inhibition of protein kinase R with 2-aminopurine prevented lipopolysaccharide and polyinosinic:polycytidylic acid induced mitochondrial fission and increased progesterone biosynthesis. Use of chemical inhibitors to treat placental stress caused by pathogens has potential to stabilize the production of progesterone. The study reveals that inhibiting mitochondrial fragmentation and reducing activity of stress kinase protein kinase R in syncytiotrophoblasts leads to an increase in progesterone synthesis when exposed to lipopolysaccharide and polyinosinic:polycytidylic acid. [ABSTRACT FROM AUTHOR]

To explore mechanism of prohibitin 2(PHB2) inhibition on the apoptosis of non-small cell lung cancer cell line A549. Methods For stable knockdown of PHB2, A549 strain was infected with lentiviruses. A549 cells with PHB2 depletion were incubated with Mdivi-1(DRP1 inhibitor). Apoptotic index of A549 cells was evaluated by TUNEL and annexin V-FITC/PI. Mitochondrial morphology was visualized by MitoTracker. ATP content, citrate synthase activity and the level of cytochrome c in cytosolic and mitochondrial fractions were analyzed by commercially available kits. Western blot was used to measure the levels of PHB2, DRP1 and p-DRP1 protein expression. Results Compared with the shCtrl group, the apoptosis of A549 cells increased significantly (P＜0.05) with up-regulated DRP1-dependent mitochondrial fission (P＜0.05), down-regulated ATP content (P＜0.05) and citrate synthase activity (P＜0.05). The level of cytochrome C was decreased in mitochondrial fractions (P＜0.05). Compared with the shPHB2 group, the apoptosis of A549 cells decreased significantly (P＜0.05) with alleviated DRP1-dependent mitochondrial fission (P＜0.05), increase of ATP content (P＜0.05) and citrate synthase activity(P＜0.05). The level of cytochrome C was increased in mitochondrial fractions (P＜0.05) in the shPHB2+Mdivi-1 group. Conclusions PHB2 inhibition can significantly enhance the apoptosis rate of A549 cells, potentially through promoting DRP1-dependent mitochondrial fission. [ABSTRACT FROM AUTHOR]

Mitochondria are versatile organelles that continuously change their morphology via fission and fusion. However, the detailed functions of mitochondrial dynamics-related genes in pluripotent stem cells remain largely unclear. Here, we aimed to determine the effects on energy metabolism and differentiation ability of mouse embryonic stem cells (ESCs) following deletion of the mitochondrial fission-related gene Dnml1. Resultant Dnm1l−/− ESCs maintained major pluripotency characteristics. However, Dnm1l−/− ESCs showed several phenotypic changes, including the inhibition of differentiation ability (dissolution of pluripotency). Notably, Dnm1l−/− ESCs maintained the expression of the pluripotency marker Oct4 and undifferentiated colony types upon differentiation induction. RNA sequencing analysis revealed that the most frequently differentially expressed genes were enriched in the glutathione metabolic pathway. Our data suggested that differentiation inhibition of Dnm1l−/− ESCs was primarily due to metabolic shift from glycolysis to OXPHOS, G2/M phase retardation, and high level of Nanog and 2-cell-specific gene expression. [ABSTRACT FROM AUTHOR]

Neurodegenerative diseases (NDs) are a diverse group of disorders characterized by the progressive degeneration and death of neurons, leading to a range of neurological symptoms. Despite the heterogeneity of these conditions, a common denominator is the implication of mitochondrial dysfunction in their pathogenesis. Mitochondria play a crucial role in creating biomolecules, providing energy through adenosine triphosphate (ATP) generated by oxidative phosphorylation (OXPHOS), and producing reactive oxygen species (ROS). When they're not functioning correctly, becoming fragmented and losing their membrane potential, they contribute to these diseases. In this review, we explore how mitochondria fuse and undergo fission, especially in the context of NDs. We discuss the genetic and protein mutations linked to these diseases and how they impact mitochondrial dynamics. We also look at the key regulatory proteins in fusion (MFN1, MFN2, and OPA1) and fission (DRP1 and FIS1), including their post-translational modifications. Furthermore, we highlight potential drugs that can influence mitochondrial dynamics. By unpacking these complex processes, we aim to direct research towards treatments that can improve life quality for people with these challenging conditions. [ABSTRACT FROM AUTHOR]

Pharmacological ascorbate (P-AscH-; high dose given intravenously) generates H 2 O 2 that is selectively cytotoxic to cancer compared to normal cells. The RAS-RAF-ERK1/2 is a major signaling pathway in cancers carrying RAS mutations and is known to be activated by H 2 O 2. Activated ERK1/2 also phosphorylates the GTPase dynamin-related protein (Drp1), which then stimulates mitochondrial fission. Although early generation of H 2 O 2 leads to cytotoxicity of cancer cells, we hypothesized that sustained increases in H 2 O 2 activate ERK-Drp1 signaling, leading to an adaptive response; inhibition of this pathway would enhance the toxicity of P-AscH-. Increases in phosphorylated ERK and Drp1 induced by P-AscH- were reversed with genetic and pharmacological inhibitors of ERK and Drp1, as well as in cells lacking functional mitochondria. P-AscH- increased Drp1 colocalization to mitochondria, decreased mitochondrial volume, increased disconnected components, and decreased mitochondrial length, suggesting an increase in mitochondrial fission 48 h after treatment with P-AscH-. P-AscH- decreased clonogenic survival; this was enhanced by genetic and pharmacological inhibition of both ERK and Drp1. In murine tumor xenografts, the combination of P-AscH- and pharmacological inhibition of Drp1 increased overall survival. These results suggest that P-AscH- induces sustained changes in mitochondria, through activation of the ERK/Drp1 signaling pathway, an adaptive response. Inhibition of this pathway enhanced the toxicity P-AscH- to cancer cells. [Display omitted] • Increases in phosphorylated ERK and Drp1 induced by pharmacological ascorbate (P-AscH-) were reversed with genetic and pharmacological inhibitors of ERK and Drp1. • Pharmacological ascorbate increased mitochondrial fission after treatment with pharmacological ascorbate. • Pharmacological ascorbate decreased in vitro and in vivo growth which was enhanced by genetic and pharmacological inhibition of both ERK and Drp1. • Pharmacological ascorbate induces sustained increases in mitochondrial oxidative stress and changes in mitochondrial dynamics, through activation of the ERK/Drp1 signaling pathway. [ABSTRACT FROM AUTHOR]