Search

Ferroptosis, triggered by discoordination of iron, thiols and lipids, leads to the accumulation of 15-hydroperoxy (Hp)-arachidonoyl-phosphatidylethanolamine (15-HpETE-PE), generated by complexes of 15-lipoxygenase (15-LOX) and a scaffold protein, phosphatidylethanolamine (PE)-binding protein (PEBP)1. As the Ca2+-independent phospholipase A2β (iPLA2β, PLA2G6 or PNPLA9 gene) can preferentially hydrolyze peroxidized phospholipids, it may eliminate the ferroptotic 15-HpETE-PE death signal. Here, we demonstrate that by hydrolyzing 15-HpETE-PE, iPLA2β averts ferroptosis, whereas its genetic or pharmacological inactivation sensitizes cells to ferroptosis. Given that PLA2G6 mutations relate to neurodegeneration, we examined fibroblasts from a patient with a Parkinson's disease (PD)-associated mutation (fPDR747W) and found selectively decreased 15-HpETE-PE-hydrolyzing activity, 15-HpETE-PE accumulation and elevated sensitivity to ferroptosis. CRISPR-Cas9-engineered Pnpla9R748W/R748W mice exhibited progressive parkinsonian motor deficits and 15-HpETE-PE accumulation. Elevated 15-HpETE-PE levels were also detected in midbrains of rotenone-infused parkinsonian rats and α-synuclein-mutant SncaA53T mice, with decreased iPLA2β expression and a PD-relevant phenotype. Thus, iPLA2β is a new ferroptosis regulator, and its mutations may be implicated in PD pathogenesis.

We have previously shown that blockade of ATP-binding cassette transporter A1 (ABCA1) with cyclosporine A (CsA) stimulates the epithelial sodium channel (ENaC) in cultured distal nephron cells. Here we show that CsA elevated systolic blood pressure in both wild-type and apolipoprotein E (ApoE) knockout (KO) mice to a similar level. The elevated systolic blood pressure was completely reversed by inhibition of cholesterol (Cho) synthesis with lovastatin. Inside-out patch-clamp data show that intracellular Cho stimulated ENaC in cultured distal nephron cells by interacting with phosphatidylinositol‑4,5‑bisphosphate (PIP2), an ENaC activator. Confocal microscopy data show that both α‑ENaC and PIP2 were localized in microvilli via a Cho-dependent mechanism. Deletion of membrane Cho reduced the levels of γ‑ENaC in the apical membrane. Reduced ABCA1 expression and elevated intracellular Cho were observed in old mice, compared to young mice. In parallel, cell-attached patch-clamp data from the split-open cortical collecting ducts (CCD) show that ENaC activity was significantly increased in old mice. These data suggest that elevation of intracellular Cho due to blockade of ABCA1 stimulates ENaC, which may contribute to CsA-induced hypertension. This study also implies that reduced ABCA1 expression may mediate age-related hypertension by increasing ENaC activity via elevation of intracellular Cho.

Daily intake of tea has been known to relate to a low risk of depression. In this study, we report that a special variety of tea in China, Camellia assamica var. kucha (kucha), possesses antidepressant effects but with less adverse effects as compared to traditional tea Camellia sinensis. This action of kucha is related to its high amount of theacrine, a purine alkaloid structurally similar to caffeine. We investigated the antidepressant-like effects and mechanisms of theacrine in chronic water immersion restraint stress and chronic unpredictable mild stress mice models. PC12 cells and primary hippocampal neural stem cells were treated with stress hormone corticosterone (CORT) to reveal the potential antidepression mechanism of theacrine from the perspective of adult hippocampus neurogenesis. Results of behavioral and neurotransmitter analysis showed that intragastric administration of theacrine significantly counteracted chronic stress-induced depression-like disorders and abnormal 5-hydroxytryptamine (5-HT) metabolism with less central excitability. Further investigation from both in vivo and in vitro experiments indicated that the antidepressant mechanism of theacrine was associated with promoting adult hippocampal neurogenesis, via the modulation of the phosphodiesterase-4 (PDE4)/cyclic adenosine monophosphate (cAMP)/cAMP response-element binding (CREB)/brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway. Collectively, our findings could promote the prevalence of kucha as a common beverage with uses for health care and contribute to the development of theacrine as a potential novel antidepressant medicine.

Objective Acylcarnitine metabolism disorder contributes significantly to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). There are, however, few ideal medications for NAFLD, which work by targeting acylcarnitine metabolism. The aim of this study was to investigate the protective effects of theacrine, a rare purine alkaloid isolated from Camellia assamica var. kucha, against acylcarnitine metabolism disorder in NAFLD. Methods The pharmacological activities of theacrine were studied using high-fat diet (HFD)-fed ApoE−/− and C57BL/6J mice models. Oleate-treated HepG2 and L-02 cells were used to investigate the molecular mechanism of theacrine on acylcarnitine metabolism. The target of theacrine was confirmed in vitro as the blockade of sirtuin 3 (SIRT3) and protein kinase A. Results Theacrine inhibits hepatic steatosis and liver inflammation and improves energy expenditure in HFD-fed mice. Theacrine ameliorates acylcarnitine metabolism disorder in HFD-fed mice and oleate-treated hepatocytes by improving fatty acid oxidation. The underlying mechanism involves theacrine's activation of the mitochondrial deacetylase SIRT3 and consequently, the increased activity of long-chain acyl coenzyme A dehydrogenase (LCAD) through deacetylation. Conclusion Theacrine promotes acylcarnitine metabolism in NAFLD through the SIRT3/LCAD signaling pathway. The target of theacrine's activities on NAFLD is identified as SIRT3.

Oral submucous fibrosis (OSF) induced by chewing of the areca nut has been considered to be a precancerous lesion with a high probability of developing oral squamous cell carcinoma. Tanshinone (TSN) is the main component extracted from Salvia miltiorrhiza, a traditional Chinese medicine, which was found to have diverse pharmacological effects, such as anti-inflammatory and antitumor. In the current study, we aimed to identify the inhibitory effects and the underlying mechanism of TSN on OSF progress. We found that treatment with TSN inhibited the arecoline-mediated proliferation of primary human oral mucosal fibroblasts and reversed the promotive effects of arecoline on the EMT process. By RNA deep sequencing, we screened two possible targets for TSN: LSD1 and p53. We confirmed that p53 is much lower in OSF than in normal mucous tissues. In addition, p53 and its downstream molecules were decreased by arecoline treatment in oral mucosal fibroblasts, which was reversed by treatment with TSN in a dose-dependent manner. Our results also revealed that arecoline stimulation resulted in hypermethylation of the promoter of TP53 and subsequent downregulation of p53 levels, which was reversed by TSN. Furthermore, we identified that LSD1 could epigenetically activate TP53 by recruiting H3K27me1 and H3K4m2 to its promoter. Our findings provide new insights into the mechanism by which TSN influences arecoline-induced OSF and rationale for the development of clinical intervention strategies for OSF and even oral squamous cell carcinoma.

The beneficial effect of caffeine-containing food on non-alcoholic fatty liver disease (NAFLD) has been widely reported. The aim of this study was to explore the effect of caffeine on hepatic steatosis. C57BL/6 mice were randomly assigned to a normal diet or a high energy diet (HED). Caffeine was given to HED mice by oral gavage. Body weights, lipids in the liver and liver damage were measured. Meanwhile, cAMP, SIRT3 or AMPK inhibitors were treated respectively before incubation with caffeine in oleate-treated HepG2 cells. SIRT3 was further silenced by siRNA to confirm the results. Caffeine significantly decreased the mass of fat tissues, lipids, ALT and AST levels in the liver of HED-treated mice. Caffeine increased the transformation of ADP to ATP and activated the cAMP/CREB/SIRT3/AMPK/ACC pathway in the liver. Nile red staining demonstrated that suppression of cAMP, SIRT3 or AMPK in oleate-treated HepG2 cells counteracted the effect of caffeine. Moreover, knocking down SIRT3 could down-regulate AMPK and ACC phosphorylation by caffeine. These results demonstrate that caffeine could improve HED-induced hepatic steatosis by promoting lipid metabolism via the cAMP/CREB/SIRT3/AMPK/ACC pathway. SIRT3 functioned as a molecular bridge connecting caffeine and lipid metabolism.

It has been suggested that voltage-dependent anion channels (VDACs) control the release of superoxide from mitochondria. We have previously shown that reactive oxygen species (ROS) such as superoxide (O2˙̄) and hydrogen peroxide (H2O2) stimulate epithelial sodium channels (ENaCs) in sodium-transporting epithelial tissue, including cortical collecting duct (CCD) principal cells. Therefore, we hypothesized that VDACs could regulate ENaC by modulating cytosolic ROS levels. Herein, we find that VDAC3-knockout(KO) mice can maintain normal salt and water balance on low-salt and high-salt diets. However, on a high-salt diet for 2 weeks, VDAC3-KO mice had significantly higher systolic blood pressure than wildtype mice. Consistent with this observation, after a high-salt diet for 2 weeks, ENaC activity in VDAC3-KO mice was significantly higher than wildtype mice. EM analysis disclosed a significant morphological change of mitochondria in the CCD cells of VDAC3-KO mice compared with wildtype mice, which may have been caused by mitochondrial superoxide overload. Of note, compared with wildtype animals, ROS levels in VDAC3-KO animals fed a normal or high-salt diet were consistently and significantly increased in renal tubules. Both the ROS scavenger 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (TEMPOL) and the mitochondrial ROS scavenger (2-(2,2,6,6-tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride (mito-TEMPO) could reverse the effect of high-salt on ENaC activity and systolic blood pressure in the VDAC3-KO mice. Mito-TEMPO partially correct the morphological changes in VDAC3-KO mice. Our results suggest that knocking out mitochondrial VDAC3 increases ROS, alters renal sodium transport, and leads to hypertension.

Cyclophosphamide is one of the most widely used chemotherapeutic agents in treating cancers. Chemotherapy drug-induced oxidative stress produces side effects. The severity of myelosuppression increases with a high dose of cyclophosphamide. Chicken soup or chicken essence, a traditional Chinese aliment, is a popular health supplement for patients with cancers or other diseases in Asia. As a major functional component of chicken meat extract, carnosine (beta-alanyl-L-histidine), a dipeptide of the amino acids beta-alanine and histidine, has been shown to have strong antioxidant activities. In the present study, we investigated the effects of carnosine on hematopoietic suppression in mice treated with cyclophosphamide. As expected, we found that cyclophosphamide administration (with a single dose of 150 mg/kg) induced a rapid (within 24 hours) and severe hematopoietic suppression in mice. We further showed that carnosine administration (100 mg/kg/day or 200 mg/kg/day for continuous seven days) could substantially improve suppressed hematopoietic functions and accelerate the recovery of leukocyte counts, bone marrow spontaneous proliferation, colony stimulating activity (CSA) in serum, and production of endogenous cytokines such as interleukin-3 (IL-3) and stem cell factor (SCF). These results indicate that carnosine has the potential to promote the recovery from hematopoietic suppression induced by cyclophosphamide. Our data suggest that carnosine holds a potential in clinical application to minimize the side effects induced by chemotherapeutic agents such as cyclophosphamide and thus will substantially improve the overall anti-tumor effects of the standard chemotherapies.

Theacrine (1,3,7,9-tetramethyluric acid), a purine alkaloid, has proven to be beneficial in maintaining several brain functions and is being studied for potential medicinal uses in recent years. In this study, we isolated theacrine from Camellia assamica var. kucha and investigated its protective effects on liver damage induced by restraint stress in mice. Results showed that 18 h of restraint stress could induce liver damage, with an obvious increase in levels of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). This finding was further confirmed by hepatic pathological examination, which showed inflammatory cell infiltration and focal necrosis of hepatocytes. However, oral administration of theacrine (10, 20, 30 mg/kg for 7 consecutive days) was found to decrease plasma ALT and AST levels, reduce hepatic mRNA levels of inflammatory mediators (IL-1β, TNF-α, IL-6, and IFN-γ), and reverse the histologic damages in stressed mice. Simultaneously, theacrine also significantly decreased the content of malondialdehyde and increased oxygen radical absorbance capacity (ORAC) level in the plasma and liver of stressed mice. These results suggested that the protective effects of theacrine on stress-induced liver damage might be correlated with its antioxidative activity. The antioxidative capacity of theacrine was further evaluated by in vitro ORAC and cellular antioxidant activity assay. The results suggested that the antioxidative capacity of theacrine was not due to the direct action on free radical clearance. Moreover, the elevated activities and gene expressions of superoxide dismutase, catalase, and glutathione peroxidase, as well as the reduced activity of xanthine oxidase by theacrine treatment in stressed mice suggested that the antioxidative activity might be due to the strengthening of the antioxidant system in vivo. On the basis of the above results, theacrine is possibly a good candidate for protecting against or treating lifestyle diseases and might contribute to the study of natural products.

A Ca2+-activated nonselective cation channel (NSCCa) is found in principal cells of the mouse cortical collecting duct (CCD). However, the molecular identity of this channel remains unclear. We used mpkCCDc14cells, a mouse CCD principal cell line, to determine whether NSCCarepresents the transient receptor potential (TRP) channel, the melastatin subfamily 4 (TRPM4). A Ca2+-sensitive single-channel current was observed in inside-out patches excised from the apical membrane of mpkCCDc14cells. Like TRPM4 channels found in other cell types, this channel has an equal permeability for Na+and K+and has a linear current-voltage relationship with a slope conductance of ~23 pS. The channel was inhibited by a specific TRPM4 inhibitor, 9-phenanthrol. Moreover, the frequency of observing this channel was dramatically decreased in TRPM4 knockdown mpkCCDc14cells. Unlike those previously reported in other cell types, the TRPM4 in mpkCCDc14cells was unable to be activated by hydrogen peroxide (H2O2). Conversely, after treatment with H2O2, TRPM4 density in the apical membrane of mpkCCDc14cells was significantly decreased. The channel in intact cell-attached patches was activated by ionomycin (a Ca2+ionophore), but not by ATP (a purinergic P2receptor agonist). These data suggest that the NSCCacurrent previously described in CCD principal cells is actually carried through TRPM4 channels. However, the physiological role of this channel in the CCD remains to be further determined.

While beneficial health properties of tea leaves have been extensively studied, less attention is paid to the flowers of tea. In this study, the anti-inflammatory effects of hot water extract of tea (Camellia sinensis) flowers were investigated. Pharmacological studies found that administration of tea flowers extract (TFE) could effectively inhibit croton oil-induced ear edema and carrageenin-induced paw edema. Furthermore, administration of TFE also protected againstPropionibacterium acnes(P. ances) plus lipopolysaccharide-(LPS-) induced liver inflammation by reversing the histologic damage and plasma alanine aminotransferase (ALT) increase. Moreover, the levels of nitric oxide (NO), tumor necrosis factor-(TNF)-αand interleukin-(IL-) 1βmRNA in mouse liver were markedly suppressed after treatment with TFE in mice with immunological liver inflammation. These results indicated that tea flowers had potent anti-inflammatory effects on acute and immunological inflammationin vivo, and may be used as a functional natural food.

In this study, we investigated the protective effects of the extract of chicken meat (EC) on liver damage in mice caused by restraint stress. Our results showed that 18 h of restraint stress-induced liver damage was marked by an increase of plasma alanine aminotransferase (ALT) and aspartate aminotransferase(AST) levels. However, oral administration of EC (0.12 and 0.24 mL/10 g per day, 7 d) was found to reduce the increased plasma ALT and AST levels in stressed mice. Meanwhile, EC significantly decreased the contents of malondialdehyde and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in plasma or liver of stressed mice. The gene expressions of antioxidative enzymes (Cu/Zn-SOD, Mn-SOD and GPX) were also up-regulated in the EC-treated group when compared with the stressed group. In addition, EC administration was found to resist a stress-induced increase of plasma corticosterone levels and down-regulation of liver glucocorticoid receptor gene expression. These results suggested that EC could protect against restraint stress-induced liver damage by smoothing stress and promoting antioxidative processes.

Objective To study the effects of Vitex negundo var. heterophylla seeds ethanol extract(VSE) on immunological hepatitis and acute inflammation mice model. Method Hepatic function in the immunological liver injury model was evaluated by assessing the levels of ALT in plasma, and the content of MDA, ORAC, NO and iNOS mRNA in liver tissues. VSE effect on the acute inflammation caused by croton oil and carrageenan was observed. Result Compared to the model group, 125 and 500 mg x kg(-1) VSE could inhibit the activities of ALT in mice plasma, and enhanced levels of ORAC and decreased levels of MDA and modulated levels of NO in liver tissues. Meanwhile, VSE could ameliorate the ear swelling induced by croton oil and reduced the thickness of mice hind paw induced by carrageenan as well. Conclusion The results indicated that VSE exerted potential effects on immunological hepatitis and the mechanisms might be partly related to free radical scavenging activity and inhibit release of iNOS. VSE also showed partial effects on acute inflammation.