Search

Heparan sulfate (HS) is degraded in lysosome by a series of glycosidases. Before the glycosidases can act, the terminal glucosamine of HS must be acetylated by the integral lysosomal membrane enzyme heparan-α-glucosaminide N-acetyltransferase (HGSNAT). Mutations of HGSNAT cause HS accumulation and consequently mucopolysaccharidosis IIIC, a devastating lysosomal storage disease characterized by progressive neurological deterioration and early death where no treatment is available. HGSNAT catalyzes a unique transmembrane acetylation reaction where the acetyl group of cytosolic acetyl-CoA is transported across the lysosomal membrane and attached to HS in one reaction. However, the reaction mechanism remains elusive. Here we report six cryo-EM structures of HGSNAT along the reaction pathway. These structures reveal a dimer arrangement and a unique structural fold, which enables the elucidation of the reaction mechanism. We find that a central pore within each monomer traverses the membrane and controls access of cytosolic acetyl-CoA to the active site at its luminal mouth where glucosamine binds. A histidine-aspartic acid catalytic dyad catalyzes the transfer reaction via a ternary complex mechanism. Furthermore, the structures allow the mapping of disease-causing variants and reveal their potential impact on the function, thus creating a framework to guide structure-based drug discovery efforts.

Background: N-acetyltransferase 10 (NAT10) is involved in several cellular processes. NAT10 expression is essential for the promotion of mRNA translation and stability. In some situations, deregulation of NAT10 has been attributed to the development of multiple types of cancer. NAT10 is significantly upregulated in various gastrointestinal tumors, including esophageal, colorectal, pancreatic, and liver cancers, and is correlated with poor prognosis. Additionally, NAT10 expression contributes to chemotherapy resistance in both esophageal and colorectal cancers. Nevertheless, the role of NAT10 in gastric cancer (GC), a type of gastrointestinal tumor, is not fully understood. Methods: Throughout this investigation, our team evaluated NAT10 expression levels in GC patient samples and databases available to the general public. Based on the knockdown and overexpression of NAT10, in vitro experiments were conducted to examine the effects of NAT10 on GC progression and resistance to chemotherapy. Results: Our study demonstrated that GC tissues exhibit increased levels of NAT10. Downregulation of NAT10 decreased GC cell proliferation, migration, and invasiveness. Conversely, upregulation of NAT10 resulted in the opposite effect. Furthermore, NAT10 fosters the progression of GC cells by activating the Wnt/β-catenin signaling pathway. NAT10 also promotes resistance to cisplatin chemotherapy. Conclusions: Our findings indicated that expression of NAT10 promoted GC progression through activation of the Wnt/β-catenin signaling pathway. We investigated the effect of NAT10 on the viability of GC cells treated with different doses of cisplatin. The results showed that NAT10 expression could impact the effectiveness of chemotherapy resistance in GC. This implies that using NAT10 as a target may be a potential therapeutic strategy for treating GC. [ABSTRACT FROM AUTHOR]

This study investigates heterocyclic gamma-butyrobetaine (GBB) analogs as metabolic modulators through an integrated approach involving rational design, molecular docking, synthesis, and in vitro evaluation. The compounds synthesized demonstrated promising inhibitory potential toward carnitine acetyltransferase (CAT) and presumably other enzymes within the carnitine transferase family, with IC50 values ranging from 2.24 to 43.6 mM. Notably, some compounds demonstrated superior activity to the reference drug Meldonium (IC50 = 11.39 mM). A substantial outcome of the study that might serve as a foundation for future optimization and synthesis of more potent compounds was that a bulky, hydrophobic substituent at the gamma position enhances inhibitory activity, whereas esterification and increased polarity diminish it. The most effective compound was determined to be a reversible competitive inhibitor of CAT, with a Ki value of 3.5 mM comparable to Meldonium's Ki of 1.63 mM. These results suggest that heterocyclic GBB analogs present potential candidates for regulating metabolic processes and treating conditions including ischemic diseases, diabetes, and specific cancers. [ABSTRACT FROM AUTHOR]

Autophagy, a conserved catabolic process implicated in a diverse array of human diseases, requires efficient fusion between autophagosomes and lysosomes to function effectively. Recently, SNAP47 has been identified as a key component of the dual-purpose SNARE complex mediating autophagosome-lysosome fusion in both bulk and selective autophagy. However, the spatiotemporal regulatory mechanisms of this SNARE complex remain unknown. In this study, we found that SNAP47 undergoes acetylation followed by deacetylation during bulk autophagy and mitophagy. The acetylation status of SNAP47 is regulated by the acetyltransferase CBP and the deacetylase HDAC2. Notably, the spatiotemporal regulatory dynamics of SNAP47 acetylation differ between bulk autophagy and mitophagy due to distinct regulation on the activity of acetyltransferase and deacetylase. Acetylated SNAP47 inhibits autophagosome-lysosome fusion by indirectly impeding SNARE complex assembly. Mechanistically, deacetylated SNAP47 recruits HOPS components to autophagic vacuoles independently of STX17 and STX17-SNAP47 interaction, while acetylated SNAP47 inhibits this recruitment, consequently leading to the failure of SNARE complex assembly. Taken together, our study uncovers a SNAP47 acetylation-dependent regulatory mechanism governing autophagosome-lysosome fusion by modulating the recruitment of HOPS to autophagic vacuoles without involving STX17, SNAP47-STX17 interaction and ternary SNARE complex formation. Autophagy involves autophagosome-lysosome fusion, regulated by the SNAP47-containing SNARE complex. This study reveals how acetylation and deacetylation of SNAP47 control fusion by modulating HOPS recruitment. [ABSTRACT FROM AUTHOR]

Background: Precise localization of intracerebral implants in rodent brains is required for physiological and behavioral studies, particularly if targeting deep brain nuclei. Traditional histological methods, based on manual estimation through sectioning can introduce errors and complicate data interpretation. Methods: Here, we introduce an alternative method based on recent advances in tissue-clearing techniques and light-sheet fluorescence microscopy. This method uses a simplified recipe of the Clear, Unobstructed Brain/Body Imaging Cocktails and Computational Analysis (CUBIC) method, which is a rapid clearing procedure using an aqueous-based solution compatible with fluorescence and fluorescence markers. We demonstrate the utility of this approach in anesthetized transgenic mice expressing channelrhodopsin-2 (ChR2) and enhanced yellow fluorescent fusion (EYFP) protein under the choline acetyltransferase (ChAT) promoter/enhancer regions (ChAT-ChR2-EYFP mice) with implanted linear silicon optrode probes into the midbrain interpeduncular nucleus (IPN). Results: By applying the red fluorescent DiD' dye (DiIC18(5) solid (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindodicarbocyanine, 4-Chlorobenzenesulfonate Salt) to the electrode surface, we precisely visualize the electrode localization in the IPN of ChAT-ChR2-EYFP mice. Three-dimensional brain videos from different orientations highlight the potential of this method. Optogenetic responses recorded from electrodes placed in the IPN validate these findings. Conclusions: This method allows for precise localization of brain implantation sites in transgenic mice expressing cell-specific fluorescence markers. It enables virtual brain slicing in any orientation, making it a useful tool for functional studies in mice. [ABSTRACT FROM AUTHOR]

Background: Orthodontic treatment applies specific corrective forces to teeth, transmitting stress to periodontal tissue, thereby regulating the growth and development of periodontal ligament stem cells (PDLSCs). Recently, N-acetyltransferase 10 (NAT10) mediated N4-acetylcytidine (ac4C) modification is demonstrated to play a key role in the osteogenic differentiation of stem cells. Therefore, this study aimed explore the effects of Orthodontic treatment on the NAT10 mediated ac4C modification and osteogenic differentiation of PDLSCs. Methods: Compressive force was used to treat PDLSCs to simulate orthodontic force treatment. The ALP and ARS staining was performed to analyze the osteogenic differentiation of PDLSCs. Besides, ac4C dot blot and ac4C-RIP assays were performed to detect the global ac4C levels and BMP2 ac4C levels. The relationship between NAT10 and BMP2 was confirmed by RIP assay and immunofluorescence staining. The mRNA and protein levels of RUNX2, Oxterix and BMP2 were detected by RT-qPCR and western blot assays. Results: Compressive force treatment promoted the osteogenic differentiation of PDLSCs, and enhanced the global ac4C levels and NAT10 levels in PDLSCs. NAT10 overexpression further promoted the osteogenic differentiation of compressive force treated PDLSCs. Besides, NAT10 overexpression increased ac4C levels of BMP2 and enhanced the mRNA stability of BMP2. Remodelin treatment significantly decreased the ac4C and mRNA levels of BMP2. Furthermore, BMP2 silencing reversed the role of NAT10 in the compressive force treated PDLSCs. Conclusion: This study demonstrated that compressive force promotes cell viability and osteogenic differentiation of PDLSCs by regulating BMP2 levels mediated by NAT10. NAT10 mediated ac4C levels of BMP2 is the key signaling axis of orthodontic stress in promoting cell growth and osteogenic differentiation of PDLSCs. [ABSTRACT FROM AUTHOR]

Objective: Among the most common chronic kidney diseases, kidney stones are second only to hypertension. Kidney stones pose a public health threat due to their increased incidence, high recurrence rate, and heavy economic burden. In this work, we investigated the potential mechanism of N-acetyltransferase 10 (NAT10) in oxidative stress and pyroptosis of renal tubular epithelial cells (RTECs). Material and Methods: A kidney-stone cell model was simulated using calcium oxalate monohydrate (COM) in vitro. Western blot analysis of NAT10 expression and N4-acetylcytidine RNA immunoprecipitation verified the regulatory efficacy of NAT10 in Unc-51 like autophagy activating kinase 1 (ULK1) ac4C modification. The luciferase reporter gene assay further verified the interaction between NAT10 and ULK1. A kidney stone model was established using BALB/c mice injected with glyoxylic acid. Results: COM can dose-dependently suppressed the cell viability and superoxide dismutase activity of HK-2 cells and promoted the release of lactate dehydrogenase and malondialdehyde levels (P < 0.05). COM also promoted apoptosis in HK-2 cells, upregulated the protein levels of caspase-1 and gasdermin D-N, and simultaneously enhanced the HK-2 cell secretion of interleukin-1b (IL-1b) and IL-18 (P < 0.05). The overexpression of NAT10 in HK-2 cells reversed the aforementioned effects, and that of NAT10 upregulated the messenger RNA (mRNA) levels of ULK1 and increased ac4C modification (P < 0.01). Furthermore, only the luciferase activity of the wild-type ULK1 containing NAT10 binding sites was enhanced with the upregulation of NAT10 (P < 0.001). Actinomycin D treatment showed that NAT10 overexpression extended the half-life of ULK1 mRNA (P < 0.01). Silencing of ULK1 neutralized the effects of NAT10 overexpression on COM-induced cell injury (P < 0.05). In addition, the increased expression of NAT10 inhibited crystal deposition, oxidative stress, and apoptosis in vivo (P < 0.05). Conclusion: This study confirmed that NAT10 inhibits RTECs oxidative stress and cell pyrodeath through the enhanced ac4C modification of ULK1 and impedes kidney stone progression. [ABSTRACT FROM AUTHOR]

Purpose: Glioblastomas are resistant to conventional therapies, including radiotherapy. Our previous study proved that epigenetic regulation influences the radiation response of glioma cells. This study evaluated the role of the acetyltransferase Tip60 on the radiation response. Material and Methods: Tip60 expression was down-regulated by transfecting specific siRNA's in A7 and MO59K cells with high and low expression of Tip60, respectively, and its effect on survival was assessed. DNA repair was analyzed by foci scoring (γH2AX, Rad51, 53BP1, pATM). The interaction of Tip60 with ATM and DNA-PK was investigated using the specific inhibitors KU55933 and NU7441, respectively. Results: Knockdown of Tip60 significantly (p <.001) reduced survival in both cell lines, but the effect was more pronounced in A7 cells. ATMi and DNA-PKi significantly reduced the surviving fraction following irradiation. However, no further effect of siTip60 on the radiosensitivity of ATMi treated A7 cells was observed. In contrast, DNA-PKi effectively enhanced the sensitizing effect of siTip60. Mechanistically, siTip60 reduced the number of initial Rad51 and ATM foci formation after irradiation and prevented their dissolution at 24 h. siTip60 had no impact on the formation of 53BP1 and γH2AX foci and did not further affect these end-points if combined with ATMi or DNA-PKi. Conclusions: Downregulation of Tip60 enhances the radiation sensitivity of both glioma cells and markedly elevates the radiation sensitivity when combined with DNA-PKi. Therefore, treatment with DNA-PK inhibitors represents a promising approach to augment the radiation sensitivity of glioma cell lines with deficient Tip60 activity in a synergistic manner. [ABSTRACT FROM AUTHOR]

Abiotic stress that plants face may impact their growth and limit their productivity. In response to abiotic stress, several endogenous survival mechanisms get activated, including the synthesis of quaternary amines in plants. Acetylcholine (ACh), a well-known quaternary amine, and its components associated with cholinergic signaling are known to contribute to a variety of physiological functions. However, their role under abiotic stress is not well documented. Even after several studies, there is a lack of a comprehensive understanding of how cholinergic components mitigate abiotic stress in plants. Acetylcholine hydrolyzing enzyme acetylcholinesterase (AChE) belongs to the GDSL lipase/acylhydrolase protein family and has been found in several plant species. Several studies have demonstrated that GDSL members are involved in growth, development, and abiotic stress. This review summarizes all the possible mitigating effects of the ACh-AChE system on abiotic stress tolerance and will try to highlight all the progress made so far in this field. [ABSTRACT FROM AUTHOR]

Background: Whole genome sequencing of clinical bacterial isolates holds promise in predicting their susceptibility to antibiotic therapy, based on a detailed understanding of the phenotypic manifestation of genotypic variation. The aac(6′) aminoglycoside acetyltransferase gene family is the most abundant aminoglycoside resistance determinant encountered in clinical practice. A variety of AAC(6′) isozymes have been described, suggesting a phenotypic distinction between subtype I, conferring resistance to amikacin (AMK), and subtype II, conferring resistance to gentamicin (GEN) instead. However, the epidemiology and thus clinical relevance of the various and diverse isozymes and their phenotypic distinction demand systematic and contemporary re-assessment to reliably predict bacterial susceptibility to aminoglycoside antibiotics. Methods: We analyzed the resistance gene annotations of 657,603 clinical bacterial isolates to assess the prevalence and diversity of aac(6′) genes. Seventeen unique aac(6′) amino acid sequences were cloned and expressed under defined promoter control in otherwise isogenic E. coli cells for phenotypic analysis with twenty distinct aminoglycoside antibiotics. A panel of clinical isolates was analyzed for the genotype–phenotype correlation of aac(6′). Results: An aac(6′) resistance gene annotation was found in 139,236 (21.2%) of the clinical isolates analyzed. AMK resistance-conferring aac(6′)-I genes dominated in Enterobacterales (28.5%). In Pseudomonas aeruginosa and Acinetobacter baumannii, a gene conferring the aac(6′)-II phenotype but annotated as aac(6′)-Ib4 was the most prevalent. None of the aac(6′) genes were annotated as subtype III, but gene aac(6′)-Ii identified in Gram-positive isolates displayed a subtype III phenotype. Genes that were annotated as aac(6′)-Ib11 in Enterobacterales conferred resistance to both AMK and GEN, which we propose constitutes a novel subtype IV when applying established nomenclature. A phenotypic assessment facilitated structural re-assessment of the substrate promiscuity of AAC(6′) enzymes. Conclusions: Our study provides the most comprehensive analysis of clinically relevant aac(6′) gene sequence variations to date, providing new insights into a differentiated substrate promiscuity across the genotypic spectrum of this gene family, thus translating into a critical contribution towards the development of amino acid sequence-based in silico antimicrobial susceptibility testing (AST). [ABSTRACT FROM AUTHOR]

Platelet-activating factor (PAF) is a potent lipid mediator, involved in thrombosis, inflammation, and atherosclerosis. The protective effect of wine and olive oil against atherosclerotic diseases is largely attributed to their phenolic compounds and mostly to resveratrol and tyrosol. Both compounds have been reported to inhibit PAF biosynthesis in interleukin-1β (IL-1β)-stimulated monocytes and also to attenuate PAF biosynthesis in cell lysates. The aim of this study was to investigate the effects of resveratrol, tyrosol, and their derivatives on unstimulated U937 cells and to explore the intracellular messaging pathways that participate in the activation of PAF biosynthesis in the same cell line. Tyrosol and its derivatives did not exert any substantial effect on PAF biosynthesis. Resveratrol (50 and 100 μM), as well as its methoxy derivative (5–20 μM), caused a reduction in the PAF biosynthetic enzymes' activity by 20–43% after 24 h of incubation. On the other hand, lower resveratrol concentration (10 μM) and higher concentration of the methoxy derivative (50 μM) increased the Ca2+-dependent lyso–PAF acetyltransferase (LysoPAF-ATC) activity by 28–45% after half-hour incubation via p38 mitogen-activated protein kinase (p38-MAPK) action. IL-1β activated PAF biosynthetic pathways via different signaling pathways, with phospholipase C-β (PLC-β) being a key enzyme. [ABSTRACT FROM AUTHOR]

Complex neurophysiological and morphologic experiments require suitable animal models for investigation. The rabbit is one of the most successful models for studying spinal cord functions owing to its substantial size. However, achieving precise surgical access to specific spinal regions requires a thorough understanding of the spinal cord's cytoarchitectonic structure and its spatial relationship with the vertebrae. The comprehensive anatomo–neurochemical atlases of the spinal cord are invaluable for attaining such insight. While such atlases exist for some rodents and primates, none exist for rabbits. We have developed a spinal cord atlas for rabbits to bridge this gap. Utilizing various neurochemical markers—including antibodies to NeuN, calbindin 28 kDa, parvalbumin, choline acetyltransferase, nitric oxide synthase, and non-phosphorylated heavy-chain neurofilaments (SMI-32 antibody)—we present the visualization of diverse spinal neuronal populations, various spinal cord metrics, stereotaxic maps of transverse slices for each spinal segment, and a spatial map detailing the intricate relationship between the spinal cord and the vertebrae across its entire length. [ABSTRACT FROM AUTHOR]

Ubiquitin (Ub) signals are recognized and decoded into cellular responses by Ub-receptors, proteins that tether the Ub-binding domain(s) (UBDs) with response elements. Typically, UBDs bind mono-Ub in highly dynamic and weak affinity manners, presenting challenges in identifying and characterizing their binding interfaces. Here, we report the development of a new approach to facilitate the detection of these weak interactions using split-reporter systems where two interacting proteins are proximally co-translated from a single mRNA. This proximity significantly enhances the readout signals of weak protein–protein interactions (PPIs). We harnessed this system to characterize the ultra-weak UBD and ENTH (Epsin N-terminal Homology) and discovered that the yeast Ent1-ENTH domain contains two Ub-binding patches. One is similar to a previously characterized patch on STAM1(signal-transducing adaptor molecule)-VHS (Vps27, Hrs, and STAM), and the other was predicted by AlphaFold. Using a split-CAT selection system that co-translates Ub and ENTH in combination with mutagenesis, we assessed and confirmed the existence of a novel binding patch around residue F53 on ENTH. Co-translation in the split-CAT system provides an effective tool for studying weak PPIs and offers new insights into Ub-receptor interactions. [ABSTRACT FROM AUTHOR]

The DNA damage response (DDR) constitutes a vital cellular process that safeguards genome integrity. This biological process involves substantial alterations in chromatin structure, commonly orchestrated by epigenetic enzymes. Here, we show that the epigenetic modifier N-terminal acetyltransferase 4 (Nat4), known to acetylate the alpha-amino group of serine 1 on histones H4 and H2A, is implicated in the response to DNA damage in S. cerevisiae. Initially, we demonstrate that yeast cells lacking Nat4 have an increased sensitivity to DNA damage and accumulate more DNA breaks than wild-type cells. Accordingly, upon DNA damage, NAT4 gene expression is elevated, and the enzyme is specifically recruited at double-strand breaks. Delving deeper into its effects on the DNA damage signaling cascade, nat4-deleted cells exhibit lower levels of the damage-induced modification H2AS129ph (γH2A), accompanied by diminished binding of the checkpoint control protein Rad9 surrounding the double-strand break. Consistently, Mec1 kinase recruitment at double-strand breaks, critical for H2AS129ph deposition and Rad9 retention, is significantly impaired in nat4Δ cells. Consequently, Mec1-dependent phosphorylation of downstream effector kinase Rad53, indicative of DNA damage checkpoint activation, is reduced. Importantly, we found that the effects of Nat4 in regulating the checkpoint signaling cascade are mediated by its N-terminal acetyltransferase activity targeted specifically towards histone H4. Overall, this study points towards a novel functional link between histone N-terminal acetyltransferase Nat4 and the DDR, associating a new histone-modifying activity in the maintenance of genome integrity. Author summary: Chromatin structure alterations are central for cells to efficiently respond to DNA damage since DNA assaults do not simply occur on 'naked' DNA but in the context of chromatin. Cells have developed an integral process to mitigate DNA damage, known as the DNA damage response (DDR), which involves instrumental chromatin dynamic changes often regulated by histone-modifying enzymes. Our work demonstrates that N-terminal acetyltransferase Nat4 regulates the response to DNA damage. Importantly, cells lacking Nat4 are more susceptible to genotoxic-induced DNA damage, as well as accumulate higher number of DNA breaks. Accordingly, Nat4 expression is induced by DNA damage and specifically localizes at DNA double-strand breaks. In agreement with this, the absence of Nat4 impairs the DDR signaling, since the distribution of DNA damage-induced phosphorylation on serine 129 of histone H2A and the subsequent binding of Rad9 surrounding the break are robustly reduced. Both events are regulated by Mec1 kinase, whose recruitment at the DNA double-strand break is significantly decreased when Nat4 is absent. Consistently, downstream activation of the DNA damage checkpoint, indicative by Rad53 phosphorylation, is significantly reduced. Finally, this work supports that Nat4 functions in DNA damage response through its N-terminal acetyltransferase activity, specifically towards histone H4. Collectively, our data reveal a novel molecular and biological role for Nat4 in the response to DNA damage, and thus implicating a new player in genome integrity. [ABSTRACT FROM AUTHOR]

The Allis group identified Gcn5 as the first transcriptionrelated lysine acetyltransferase in 1996, providing a molecular "missing link" between chromatin organization and gene regulation. This review will focus on functions subsequently identified for Gcn5 and the closely related PCAF protein, in the context of two major complexes, SAGA and ATAC, and how the study of these enzymes informs long standing questions regarding the importance of lysine acetylation. [ABSTRACT FROM AUTHOR]

An increased understanding of how the acceptor site in Gcn5-related N-acetyltransferase (GNAT) enzymes recognizes various substrates provides important clues for GNAT functional annotation and their use as chemical tools. In this study, we explored how the PA3944 enzyme from Pseudomonas aeruginosa recognizes three different acceptor substrates, including aspartame, NANMO, and polymyxin B, and identified acceptor residues that are critical for substrate specificity. To achieve this, we performed a series of molecular docking simulations and tested methods to identify acceptor substrate binding modes that are catalytically relevant. We found that traditional selection of best docking poses by lowest S scores did not reveal acceptor substrate binding modes that were generally close enough to the donor for productive acetylation. Instead, sorting poses based on distance between the acceptor amine nitrogen atom and donor carbonyl carbon atom placed these acceptor substrates near residues that contribute to substrate specificity and catalysis. To assess whether these residues are indeed contributors to substrate specificity, we mutated seven amino acid residues to alanine and determined their kinetic parameters. We identified several residues that improved the apparent affinity and catalytic efficiency of PA3944, especially for NANMO and/or polymyxin B. Additionally, one mutant (R106A) exhibited substrate inhibition toward NANMO, and we propose scenarios for the cause of this inhibition based on additional substrate docking studies with R106A. Ultimately, we propose that this residue is a key gatekeeper between the acceptor and donor sites by restricting and orienting the acceptor substrate within the acceptor site.

Poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] is a highly promising valuable biodegradable material with good biocompatibility and degradability. Vibrio natriegens, owing to its fast-growth, wide substrate spectrum characteristics, was selected to produce P(3HB-co-LA). Herein, the crucial role of acetyltransferase PN96-18060 for PHB synthesis in V. natriegens was identified. Heterologous pathway of P(3HB-co-LA) was introduced into V. natriegens successfully, in addition, overexpression of the dldh gene led to 1.84 fold enhancement of the lactate content in P(3HB-co-LA). Finally, the production of P(3HB-co-LA) was characterized under different carbon sources. The lactate fraction in P(3HB-co-LA) was increased to 28.3 mol% by the modification, about 1.84 times of that of the control. This is the first successful case of producing the P(3HB-co-LA) in V. natriegens. Collectively, this study showed that V. natriegens is an attractive host organism for producing P(3HB-co-LA) and has great potential to produce other co-polymers. [ABSTRACT FROM AUTHOR]

N-terminal acetyltransferase B (NatB) is a major contributor to the N-terminal acetylome and is implicated in several key cellular processes including apoptosis and proteostasis. However, the molecular mechanisms linking NatB-mediated N-terminal acetylation to apoptosis and its relationship with protein homeostasis remain elusive. In this study, we generated mouse embryonic fibroblasts (MEFs) with an inactivated catalytic subunit of NatB (Naa20-/-) to investigate the impact of NatB deficiency on apoptosis regulation. Through quantitative N-terminomics, label-free quantification, and targeted proteomics, we demonstrated that NatB does not influence the proteostasis of all its substrates. Instead, our focus on putative NatB-dependent apoptotic factors revealed that NatB serves as a protective shield against UBR4 and UBR1 Arg/N-recognin-mediated degradation. Notably, Naa20-/- MEFs exhibited reduced responsiveness to an extrinsic pro-apoptotic stimulus, a phenotype that was partially reversible upon UBR4 Arg/N-recognin silencing and consequent inhibition of procaspase-8 degradation. Collectively, our results shed light on how the interplay between NatB-mediated acetylation and the Arg/N-degron pathway appears to impact apoptosis regulation, providing new perspectives in the field including in therapeutic interventions. [ABSTRACT FROM AUTHOR]

Members of the domain of unknown function 231/trichome birefringence–like (TBL) family have been shown to be O -acetyltransferases catalyzing the acetylation of plant cell wall polysaccharides, including pectins, mannan, xyloglucan and xylan. However, little is known about the origin and evolution of plant cell wall polysaccharide acetyltransferases. Here, we investigated the biochemical functions of TBL homologs from Klebsormidium nitens , a representative of an early divergent class of charophyte green algae that are considered to be the closest living relatives of land plants, and Marchantia polymorpha , a liverwort that is an extant representative of an ancient lineage of land plants. The genomes of K. nitens and Marchantia polymorpha harbor two and six TBL homologs, respectively. Biochemical characterization of their recombinant proteins expressed in human embryonic kidney 293 cells demonstrated that the two K. nitens TBLs exhibited acetyltransferase activities acetylating the pectin homogalacturonan (HG) and hence were named KnPOAT1 and KnPOAT2. Among the six M. polymorpha TBLs, five (MpPOAT1 to 5) possessed acetyltransferase activities toward pectins and the remaining one (MpMOAT1) catalyzed 2- O - and 3- O -acetylation of mannan. While MpPOAT1,2 specifically acetylated HG, MpPOAT3,4,5 could acetylate both HG and rhamnogalacturonan-I. Consistent with the acetyltransferase activities of these TBLs, pectins isolated from K. nitens and both pectins and mannan from M. polymorpha were shown to be acetylated. These findings indicate that the TBL genes were recruited as cell wall polysaccharide O -acetyltransferases as early as in charophyte green algae with activities toward pectins and they underwent expansion and functional diversification to acetylate various cell wall polysaccharides during evolution of land plants. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus CC239-MRSA-III is an ancient pandemic strain of hospital-associated, methicillin-resistant S. aureus that spread globally for decades and that still can be found in some parts of the world. In Kuwait, microarray-based surveillance identified from 2019 to 2022 a series of isolates of a hitherto unknown variant of this strain that carried a second set of recombinase genes, ccrA/B-2. To elucidate the structure of its SCCmec element, two isolates were subjected to nanopore sequencing. This revealed, in addition to ccrA/B-2, several SCC-associated genes including speG (spermidine N acetyltransferase) and a gene encoding a large "E-domain containing protein" (dubbed as edcP-SCC). This gene contained three regions consisting of multiple repeating units. In terms of sequence and structure it was similar but not identical to the biofilm-related aap gene from S. epidermidis. A review of published sequences identified edcP-SCC in eighteen genome sequences of S. aureus, S. epidermidis and S. capitis, and frequently it appears in a similar cluster of genes as in the strains sequenced herein. Isolates also carried a prophage with the adhesion factor sasX/sesI and aminoglycoside resistance genes. This is consistent with an affiliation to the "South-East Asian" Clade of CC239. The emergence of edcP-SCC and sasX-positive CC239 strain shows that, against a global trend towards community-associated MRSA, the ancient pandemic CC239 hospital strain still continues to evolve and to cause outbreaks. [ABSTRACT FROM AUTHOR]

N-alpha-acetyltransferase 40 (NAA40) is an evolutionarily conserved N-terminal acetyltransferase (NAT) linked to oncogenesis and chemoresistance. A recent study reported the generation of a second, shorter NAA40 isoform (NAA40S) through alternative translation, which we proceeded to further characterise. Notably, recombinant NAA40S had a greater in vitro enzymatic activity and affinity towards its histone H2A/H4 substrates compared to full-length NAA40 (NAA40L). Within cells, NAA40S was enzymatically active, based on its ability to suppress the H2A/H4S1Ph antagonistic mark in CRISPR-generated NAA40 knockout cells. Finally, we show that in addition to alternative translation, the NAA40S isoform could be derived from a primate and testis-specific transcript, which may align with the "out-of-testis" origin of recently evolved genes and isoforms. To summarise, our data reveal an even greater functional divergence between the two NAA40 isoforms than had been previously recognised. [ABSTRACT FROM AUTHOR]

Interleukin-1α is a suggested dual-function cytokine that diverged from interleukin-1β in mammals potentially by acquiring additional biological roles that relate to highly conserved regions in the pro-domain of interleukin-1α, including a nuclear localisation sequence and histone acetyltransferase-binding domains. Why evolution modified pro-interleukin-1α's subcellular location and protein interactome, and how this shaped interleukin-1α's intracellular role, is unknown. Here we show that TurboID proximity labelling with pro-interleukin-1α suggests a nuclear role for pro-interleukin-1α that involves interaction with histone acetyltransferases, including EP300. We also identify and validate inactivating mutations in the pro-interleukin-1α nuclear localisation sequence of multiple mammalian species, including toothed whales, castorimorpha and marsupials. However, histone acetyltransferase-binding domains are conserved in those species that have lost pro-interleukin-1α nuclear localisation. Together, these data suggest that histone acetyltransferase binding and nuclear localisation occurred together, and that while some species lost the nuclear localisation sequence in their pro-interleukin-1α, histone acetyltransferase binding ability was maintained. The nuclear localisation sequence was lost from several distinct species at different evolutionary times, suggesting convergent evolution, and that the loss of the nuclear localisation sequence confers some important biological outcome. Interleukin (IL)-1α is a critical inflammatory cytokine and yet its intracellular role is poorly understood. Here, the authors use proximity labelling of pro-IL-1α and assess its interactome, and dissect the presence and impact on a conserved nuclear interaction and its impact on the immunobiology and evolutionary convergence/divergence between species. [ABSTRACT FROM AUTHOR]

Streptomycetes are well-known antibiotic producers possessing in their genomes numerous silent biosynthetic pathways that might direct the biosynthesis of novel bio-active specialized metabolites. It is thus of great interest to find ways to enhance the expression of these pathways to discover most needed novel antibiotics. In this study, we demonstrated that the over-expression of acetyltransferase SCO0988 up-regulated the production of specialized metabolites and accelerated sporulation of the weak antibiotic producer, Streptomyces lividans and that the deletion of this gene had opposite effects in the strong antibiotic producer, Streptomyces coelicolor. The comparative analysis of the acetylome of a S. lividans strain over-expressing sco0988 with that of the original strain revealed that SCO0988 acetylates a broad range of proteins of various pathways including BldKB/SCO5113, the extracellular solute-binding protein of an ABC-transporter involved in the up-take of a signal oligopeptide of the quorum sensing pathway. The up-take of this oligopeptide triggers the “bald cascade” that regulates positively specialized metabolism, aerial mycelium formation and sporulation in S. coelicolor. Interestingly, BldKB/SCO5113 was over-acetylated on four Lysine residues, including Lys425, upon SCO0988 over-expression. The bald phenotype of a bldKB mutant could be complemented by native bldKB but not by variant of bldKB in which the Lys425 was replaced by arginine, an amino acid that could not be acetylated or by glutamine, an amino acid that is expected to mimic acetylated lysine. Our study demonstrated that Lys425 was a critical residue for BldKB function but was inconclusive concerning the impact of acetylation of Lys425 on BldKB function. [ABSTRACT FROM AUTHOR]

Simple Summary: Individualized medicine means understanding how each tumor is different from normal cells and how each tumor is different from other tumors, including profiling mutations, non-mutational epigenetic changes, and differences in gene expression. This allows the discovery of key processes each tumor absolutely depends on for survival and growth, which are intrinsic weaknesses. This profiling means selecting treatments to specifically target each tumor's survival-dependent pathways, killing them. Tip60 is a master controller of processes that maintain genome stability and signaling regulating gene expression. While disrupted in many cancers, Tip60 is essential for cell survival, and inhibiting Tip60 kills tumors. While we understand some key aspects of the molecular roles Tip60 plays, much more remains to be discovered. A more complete understanding of the diverse roles and functions of Tip60 in cancer, and how targeting Tip60 kills cancer cells, will lead to better treatments for patients and increased survival. Precision (individualized) medicine relies on the molecular profiling of tumors' dysregulated characteristics (genomic, epigenetic, transcriptomic) to identify the reliance on key pathways (including genome stability and epigenetic gene regulation) for viability or growth, and then utilises targeted therapeutics to disrupt these survival-dependent pathways. Non-mutational epigenetic changes alter cells' transcriptional profile and are a key feature found in many tumors. In contrast to genetic mutations, epigenetic changes are reversable, and restoring a normal epigenetic profile can inhibit tumor growth and progression. Lysine acetyltransferases (KATs or HATs) protect genome stability and integrity, and Tip60 is an essential acetyltransferase due to its roles as an epigenetic and transcriptional regulator, and as master regulator of the DNA double-strand break response. Tip60 is commonly downregulated and mislocalized in many cancers, and the roles that mislocalized Tip60 plays in cancer are not well understood. Here we categorize and discuss Tip60-regulated genes, evaluate Tip60-interacting proteins based on cellular localization, and explore the therapeutic potential of Tip60-targeting compounds as epigenetic inhibitors. Understanding the multiple roles Tip60 plays in tumorigenesis will improve our understanding of tumor progression and will inform therapeutic options, including informing potential combinatorial regimes with current chemotherapeutics, leading to improvements in patient outcomes. [ABSTRACT FROM AUTHOR]

Objective To investigate the effects of hyperbaric oxygen combined with ulinastatin on choline acetyltransferase (ChAT), malondialdehyde (MDA), and myocardial function in rats with acute organophosphorus pesticide poisoning. Methods 50 specific-pathogen-free (SPF) male SD rats were randomly divided into five groups of ten each: normal group (N), model group (M), hyperbaric oxygen group (H), and ulinastatin group (U), and hyperbaric oxygen combined ulinastatin (O) group. The model of acute organophosphorus pesticide poisoning was established in the M, H, U, and O groups via cumulative subcutaneous injections on the neck back, and the N group did not set up the model. After the success of the modeling, the H group was treated with hyperbaric oxygen therapy, and the U group was intraperitoneally injected with ulinastatin at a dose of 100 000 U/kg.The O group received a combination of hyperbaric oxygen and ulinastatin treatment, whereas the N and M groups were gavaged with an equivalent volume of saline. The rats' myocardial function was assessed through cardiac echocardiography, brain tissue pathology was examined using hematoxylin and eosin (HE) staining and Nissl staining, cardiomyocyte apoptosis was evaluated by TUNEL assay, and ChAT and acetylcholine (Ach) content in rat brain tissues were determined through histochemical methods. Serum levels of MDA and superoxide dismutase (SOD) were measured using the thiobarbituric acid reactive substances (TBARS) assay. Statistical analysis was performed by SPSS 22.0. Results Compared with Group N, the left ventricular end systolic dimension (LVSD) and left ventricular end diastolic dimension (LVDD) in Group M were both enlarged, with increased interventricular septum (IVS) thickness, aggravated left ventricular strain (LVS), increased number of apoptotic cardiomyocytes, and elevated Ach and MDA levels (P<0.05). Additionally, the left ventricular ejection fraction (LVEF) decreased, while ChAT and SOD levels also decreased (P<0.05). When compared to Group M, both Groups H and U exhibited reduced LVSD and LVDD, thinner IVS, decreased LVS, and fewer apoptotic cardiomyocytes. Furthermore, Ach and MDA levels were lower (P<0.05), while LVEF, ChAT, and SOD levels were higher (P<0.05). No statistically significant difference was observed between Groups U and H (P>0.05), while Group O showed more pronounced changes compared to Group U (P<0.05). Rats in Group N exhibited normal brain tissue pathological morphology, while those in Group M suffered severe damage to brain tissue structure. Compared to Group M, significant improvements in symptoms were observed in Groups H, U, and O. Conclusions Hyperbaric oxygen combined with ulinastatin has a significant effect on acute organophosphorus pesticide poisoning rats, which can significantly increase ChAT content, decrease MDA content, and effectively improve myocardial function. [ABSTRACT FROM AUTHOR]

Gcn5-related N-acetyltransferases catalyze the transfer of an acetyl group to a primary amino group of a wide class of substrates. Deprotonation of the amino group upon binding to the enzyme is necessary to activate the nucleophilic attack on the substrate. The process of binding of glutamate to N-acetylglutamate synthase is considered using the methods of molecular modeling and quantum chemistry. It is shown that deprotonation of the primary amino group of glutamate occurs upon its incorporation into the active site of the enzyme with the participation of the side chain of the aspartate residue. [ABSTRACT FROM AUTHOR]

The pyruvate dehydrogenase complex (PDHc) is a key megaenzyme linking glycolysis with the citric acid cycle. In mammalian PDHc, dihydrolipoamide acetyltransferase (E2) and the dihydrolipoamide dehydrogenase-binding protein (E3BP) form a 60-subunit core that associates with the peripheral subunits pyruvate dehydrogenase (E1) and dihydrolipoamide dehydrogenase (E3). The structure and stoichiometry of the fully assembled, mammalian PDHc or its core remained elusive. Here, we demonstrate that the human PDHc core is formed by 48 E2 copies that bind 48 E1 heterotetramers and 12 E3BP copies that bind 12 E3 homodimers. Cryo-electron microscopy, together with native and cross-linking mass spectrometry, confirmed a core model in which 8 E2 homotrimers and 12 E2-E2-E3BP heterotrimers assemble into a pseudoicosahedral particle such that the 12 E3BP molecules form six E3BP-E3BP intertrimer interfaces distributed tetrahedrally within the 60-subunit core. The even distribution of E3 subunits in the peripheral shell of PDHc guarantees maximum enzymatic activity of the megaenzyme. [ABSTRACT FROM AUTHOR]

Higher plants have developed complex mechanisms to adapt to fluctuating environmental conditions with light playing a vital role in photosynthesis and influencing various developmental processes, including photomorphogenesis. Exposure to ultraviolet (UV) radiation can cause cellular damage, necessitating effective DNA repair mechanisms. Histone acetyltransferases (HATs) play a crucial role in regulating chromatin structure and gene expression, thereby contributing to the repair mechanisms. HATs facilitate chromatin relaxation, enabling transcriptional activation necessary for plant development and stress responses. The intricate relationship between HATs, light signaling pathways and chromatin dynamics has been increasingly understood, providing valuable insights into plant adaptability. This review explores the role of HATs in plant photomorphogenesis, chromatin remodeling and gene regulation, highlighting the importance of chromatin modifications in plant responses to light and various stressors. It emphasizes the need for further research on individual HAT family members and their interactions with other epigenetic factors. Advanced genomic approaches and genome-editing technologies offer promising avenues for enhancing crop resilience and productivity through targeted manipulation of HAT activities. Understanding these mechanisms is essential for developing strategies to improve plant growth and stress tolerance, contributing to sustainable agriculture in the face of a changing climate. [ABSTRACT FROM AUTHOR]

H3K4 methylation by Set1-COMPASS (complex of proteins associated with Set1) is a conserved histone modification. Although it is critical for gene regulation, the posttranslational modifications of this complex that affect its function are largely unexplored. This study showed that N-terminal acetylation of Set1-COMPASS proteins by Nterminal acetyltransferases (NATs) can modulate H3K4 methylation patterns. Specifically, deleting NatA substantially decreased global H3K4me3 levels and caused the H3K4me2 peak in the 5' transcribed regions to shift to the promoters. NatA was required for N-terminal acetylation of three subunits of Set1-COMPASS: Shg1, Spp1, and Swd2. Moreover, deleting Shg1 or blocking its N-terminal acetylation via proline mutation of the target residue drastically reduced H3K4 methylation. Thus, NatA-mediated N-terminal acetylation of Shg1 shapes H3K4 methylation patterns. NatB also regulates H3K4 methylation, likely via N-terminal acetylation of the Set1-COMPASS protein Swd1. Thus, N-terminal acetylation of Set1-COMPASS proteins can directly fine-tune the functions of this complex, thereby substantially shaping H3K4 methylation patterns. [ABSTRACT FROM AUTHOR]

Here, we report a novel role for the yeast lysine acetyltransferase NuA4 in regulating phospholipid availability for organelle morphology. Disruption of the NuA4 complex results in 70% of cells displaying nuclear deformations and nearly 50% of cells exhibiting vacuolar fragmentation. Cells deficient in NuA4 also show severe defects in the formation of nuclear-vacuole junctions (NJV), as well as a decrease in piecemeal microautophagy of the nucleus (PMN). To determine the cause of these defects we focused on Pah1, an enzyme that converts phosphatidic acid into diacylglycerol, favoring accumulation of lipid droplets over phospholipids that are used for membrane expansion. NuA4 subunit Eaf1 was required for Pah1 localization to the inner nuclear membrane and artificially tethering of Pah1 to the nuclear membrane rescued nuclear deformation and vacuole fragmentation defects, but not defects related to the formation of NVJs. Mutation of a NuA4-dependent acetylation site on Pah1 also resulted in aberrant Pah1 localization and defects in nuclear morphology and NVJ. Our work suggests a critical role for NuA4 in organelle morphology that is partially mediated through the regulation of Pah1 subcellular localization. [ABSTRACT FROM AUTHOR]

Infectious diseases have been jeopardized problem that threaten public health over a long period of time. The growing prevalence of drug‐resistant pathogens and infectious cases have led to a decrease in the number of effective antibiotics, which highlights the urgent need for the development of new antibacterial agents. Serine acetyltransferase (SAT), also known as CysE in certain bacterial species, and O‐acetylserine sulfhydrylase (OASS), also known as CysK in select bacteria, are indispensable enzymes within the cysteine biosynthesis pathway of various pathogenic microorganisms. These enzymes play a crucial role in the survival of these pathogens, making SAT and OASS promising targets for the development of novel anti‐infective agents. In this comprehensive review, we present an introduction to the structure and function of SAT and OASS, along with an overview of existing inhibitors for SAT and OASS as potential antibacterial agents. Our primary focus is on elucidating the inhibitory activities, structure–activity relationships, and mechanisms of action of these inhibitors. Through this exploration, we aim to provide insights into promising strategies and prospects in the development of antibacterial agents that target these essential enzymes. [ABSTRACT FROM AUTHOR]

Background: Acne vulgaris (AV) is a highly prevalent skin inflammatory disorder. Histone modifications are common epigenetic processes, which happen secondary to environmental conditions. One of the many biological pathways' epigenetic regulation mechanisms is histone acetylation and deacetylation. Objective: To evaluate the serum levels of histone deacetylase 1 (HDAC1) enzyme in AV cases and to examine their correlation with AV severity. Patients and Methods: A case-control study was conducted on 90 participants: 45 patients with acne vulgaris and 45 healthy controls (HC). Global acne grading system (GAGS) was calculated. Then, serum HDAC1 level was measured by using ELISA. Results: Cases showed significantly higher HDAC1 level when compared to control group. HDAC1 among case group showed a significant gradual increase in mild, moderate, severe, and very severe grades. Moreover, positive significant correlation with the score of acne vulgaris was demonstrated (p<0.001). Conclusion: Human histone deacetylases1 (HDAC1) appears to be dysregulated in cases with AV. This could suggest a possible therapeutic opportunity for HDAC inhibitors for AV management. [ABSTRACT FROM AUTHOR]

BackgroundPolycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants originating from petrogenic and pyrogenic sources. PAH compounds can cross the placenta, and prenatal PAH exposure is linked to adverse infant and childhood health outcomes.ObjectiveIn this first human transcriptomic assessment of PAHs in the placenta, we examined associations between prenatal PAH exposure and placental gene expression to gain insight into mechanisms by which PAHs may disrupt placental function.MethodsThe ECHO PATHWAYS Consortium quantified prenatal PAH exposure and the placental transcriptome from 629 pregnant participants enrolled in the CANDLE study. Concentrations of 12 monohydroxy-PAH (OH-PAH) metabolites were measured in mid-pregnancy urine using high performance liquid chromatography tandem mass spectrometry. Placental transcriptomic data were obtained using paired-end RNA sequencing. Linear models were fitted to estimate covariate-adjusted associations between maternal urinary OH-PAHs and placental gene expression. We performed sex-stratified analyses to evaluate whether associations varied by fetal sex. Selected PAH/gene expression analyses were validated by treating HTR-8/SVneo cells with phenanthrene, and quantifying expression via qPCR.ResultsUrinary concentrations of 6 OH-PAHs were associated with placental expression of 8 genes. Three biological pathways were associated with 4 OH-PAHs. Placental expression of SGF29 and TRIP13 as well as the vitamin digestion and absorption pathway were positively associated with multiple metabolites. HTR-8/SVneo cells treated with phenanthrene also exhibited 23 % increased TRIP13 expression compared to vehicle controls (p = 0.04). Fetal sex may modify the relationship between prenatal OH-PAHs and placental gene expression, as more associations were identified in females than males (45 vs 28 associations).DiscussionOur study highlights novel genes whose placental expression may be disrupted by OH-PAHs. Increased expression of DNA damage repair gene TRIP13 may represent a response to double-stranded DNA breaks. Increased expression of genes involved in vitamin digestion and metabolism may reflect dietary exposures or represent a compensatory mechanism to combat damage related to OH-PAH toxicity. Further work is needed to study the role of these genes in placental function and their links to perinatal outcomes and lifelong health.

Background: Fibrogenesis within ovarian endometrioma (endometrioma), mainly induced by transforming growth factor-β (TGF-β), is characterized by myofibroblast over-activation and excessive extracellular matrix (ECM) deposition, contributing to endometrioma-associated symptoms such as infertility by impairing ovarian reserve and oocyte quality. However, the precise molecular mechanisms that underpin the endometrioma- associated fibrosis progression induced by TGF-β remain poorly understood. Methods: The expression level of lysine acetyltransferase 14 (KAT14) was validated in endometrium biopsies from patients with endometrioma and healthy controls, and the transcription level of KAT14 was further confirmed by analyzing a published single-cell transcriptome (scRNA-seq) dataset of endometriosis. We used overexpression, knockout, and knockdown approaches in immortalized human endometrial stromal cells (HESCs) or human primary ectopic endometrial stromal cells (EcESCs) to determine the role of KAT14 in TGF-β-induced fibrosis. Furthermore, an adeno-associated virus (AAV) carrying KAT14-shRNA was used in an endometriosis mice model to assess the role of KAT14 in vivo. Results: KAT14 was upregulated in ectopic lesions from endometrioma patients and predominantly expressed in activated fibroblasts. In vitro studies showed that KAT14 overexpression significantly promoted a TGF-β-induced profibrotic response in endometrial stromal cells, while KAT14 silencing showed adverse effects that could be rescued by KAT14 re-enhancement. In vivo, Kat14 knockdown ameliorated fibrosis in the ectopic lesions of the endometriosis mouse model. Mechanistically, we showed that KAT14 directly interacted with serum response factor (SRF) to promote the expression of α-smooth muscle actin (α-SMA) by increasing histone H4 acetylation at promoter regions; this is necessary for TGF-β-induced ECM production and myofibroblast differentiation. In addition, the knockdown or pharmacological inhibition of SRF significantly attenuated KAT14-mediating profibrotic effects under TGF-β treatment. Notably, the KAT14/SRF complex was abundant in endometrioma samples and positively correlated with α-SMA expression, further supporting the key role of KAT14/SRF complex in the progression of endometrioma-associated fibrogenesis. Conclusion: Our results shed light on KAT14 as a key effector of TGF-β–induced ECM production and myofibroblast differentiation in EcESCs by promoting histone H4 acetylation via co-operating with SRF, representing a potential therapeutic target for endometrioma-associated fibrosis. [ABSTRACT FROM AUTHOR]

Transposable elements are DNA sequences capable of moving within genomes and significantly influence genomic evolution. The nematode Caenorhabditis inopinata exhibits a much higher transposable element copy number than its sister species, Caenorhabditis elegans. In this study, we identified a novel autonomous transposable element belonging to the hAT superfamily from a spontaneous transposable element-insertion mutant in C. inopinata and named this transposon Ci-hAT1. Further bioinformatic analyses uncovered 3 additional autonomous hAT elements—Ci-hAT2, Ci-hAT3, and Ci-hAT4—along with over 1,000 copies of 2 nonautonomous miniature inverted-repeat transposable elements, mCi-hAT1 and mCi-hAT4, likely derived from Ci-hAT1 and Ci-hAT4 through internal deletion. We tracked at least 3 sequential transpositions of Ci-hAT1 over several years. However, the transposition rates of the other 3 autonomous hAT elements were lower, suggesting varying activity levels. Notably, the distribution patterns of the 2 miniature inverted-repeat transposable element families differed significantly: mCi-hAT1 was primarily located in the chromosome arms, a pattern observed in the transposable elements of other Caenorhabditis species, whereas mCi-hAT4 was more evenly distributed across chromosomes. Additionally, interspecific transcriptome analysis indicated that C. inopinata genes with upstream or intronic these miniature inverted-repeat transposable element insertions tend to be more highly expressed than their orthologous genes in C. elegans. These findings highlight the significant role of de-silenced transposable elements in driving the evolution of genomes and transcriptomes, leading to species-specific genetic diversity. [ABSTRACT FROM AUTHOR]

Simple Summary: TWIST1 is a transcription factor that induces epithelial-mesenchymal transition (EMT), and EMT is positively associated with programmed death ligand 1 (PD-L1) expression and immune escape in breast cancer cells. However, the relationship between TWIST1 and PD-L1 or immune evasion in breast cancer is unknown. In this study, we found that PD-L1 is a target gene of TWIST1. TWIST1 interacts with the TIP60 acetyltransferase complex in a BRD8-dependent manner to robustly upregulate PD-L1 expression. The knockdown of TWIST1 or BRD8 largely diminished PD-L1 expression and enhanced the CD8+ T-cell-mediated inhibition of breast cancer cell growth. Furthermore, the blockade of PD-L1 expressed in TWIST1-positive breast cancer cells also abolished the TWIST1-mediated suppression of CD8+ T cells and reinvigorated CD8+ T cells to inhibit cancer cells. These results suggest that TWIST1 may be a potential target for silencing PD-L1 expression to prevent the exhaustion of cytotoxic CD8+ T cells. In breast cancer, epithelial-mesenchymal transition (EMT) is positively associated with programmed death ligand 1 (PD-L1) expression and immune escape, and TWIST1 silences ERα expression and induces EMT and cancer metastasis. However, how TWIST1 regulates PD-L1 and immune evasion is unknown. This study analyzed TWIST1 and PD-L1 expression in breast cancers, investigated the mechanism for TWIST1 to regulate PD-L1 transcription, and assessed the effects of TWIST1 and PD-L1 in cancer cells on cytotoxic CD8+ T cells. Interestingly, TWIST1 expression is correlated with high-level PD-L1 expression in ERα-negative breast cancer cells. The overexpression and knockdown of TWIST1 robustly upregulate and downregulate PD-L1 expression, respectively. TWIST1 binds to the PD-L1 promoter and recruits the TIP60 acetyltransferase complex in a BRD8-dependent manner to transcriptionally activate PD-L1 expression, which significantly accelerates the exhaustion and death of the cytotoxic CD8+ T cells. Accordingly, knockdown of TWIST1 or BRD8 or inhibition of PD-L1 significantly enhances the tumor antigen-specific CD8+ T cells to suppress the growth of breast cancer cells. These results demonstrate that TWIST1 directly induces PD-L1 expression in ERα-negative breast cancer cells to promote immune evasion. Targeting TWIST1, BRD8, and/or PD-L1 in ERα-negative breast cancer cells with TWIST1 expression may sensitize CD8+ T-cell-mediated immunotherapy. [ABSTRACT FROM AUTHOR]

l -cysteine, a primary building block of mycothiol, plays an essential role in the defense mechanism of Mycobacterium tuberculosis (Mtb). However, it is unclear how Mtb regulates cysteine biosynthesis as no study has reported the cysteine regulatory complex (CRC) in Mtb. Serine acetyltransferase (SAT) and cysteine synthase (CS) interact to form CRC. Although Mt CS has been characterized well, minimal information is available on Mt SAT, which synthesizes, O-acetylserine (OAS), the precursor of cysteine. This study fills the gap and provides experimental evidence for the presence of Mt CRC and a non-canonical multi-oligomeric Mt SAT. We employed multiple analytical methods to characterize the oligomeric and kinetic properties of Mt SAT and Mt CRC. Results show that Mt SAT, lacking >75 N-terminal amino acids exists in three different assembly states; trimer, hexamer, and dodecamer, compared to the single hexameric state of SAT of other bacteria. While hexamers display the highest catalytic turnover, the trimer is the least active. The predominance of trimers at low physiologically relevant concentrations suggests that Mt SAT displays the lowest catalytic potential known. Further, the catalytic potential of Mt SAT is also significantly reduced in CRC state, in contrast to enhanced activity of SAT in CRC of other organisms. Our study provides insights into multi-oligomeric Mt SAT with reduced catalytic potential and demonstrates that both Mt SAT and Mt CS of Mycobacterium interact to form CRC, although with altered catalytic properties. We discuss our results in light of the altered biochemistry of the last step of canonical sulfate-dependent cysteine biosynthesis of Mycobacterium. [Display omitted] • Serine acetyltransferase from Mycobacterium tuberculosis (Mt SAT) lacks four N-terminal helices. • Mt SAT exists in three states, with the trimer demonstrating the least catalytic efficiency. • Only hexamers can form cysteine regulatory complex (CRC) with cysteine synthase, not trimers. • Together, results indicate that compromised catalytic efficiency of Mt SAT may be an evolutionary adaptation. [ABSTRACT FROM AUTHOR]

Mice with skeletal muscle-specific and inducible double knockout of the lysine acetyltransferases, p300 (E1A binding protein p300) and CBP (cAMP-response element-binding protein binding protein), referred to as i-mPCKO, demonstrate a dramatic loss of contractile function in skeletal muscle and ultimately die within 7 days. Given that many proteins involved in ATP generation and cross-bridge cycling are acetylated, we investigated whether these processes are dysregulated in skeletal muscle from i-mPCKO mice and, thus, whether they could underlie the rapid loss of muscle contractile function. Just 4–5 days after inducing knockout of p300 and CBP in skeletal muscle from adult i-mPCKO mice, there was ∼90% reduction in ex vivo contractile function in the extensor digitorum longus (EDL) and a ∼65% reduction in in vivo ankle dorsiflexion torque, as compared with wild type (WT; i.e., Cre negative) littermates. Despite this profound loss of contractile force in i-mPCKO mice, there were no genotype-driven differences in fatigability during repeated contractions, nor were there genotype differences in mitochondrial-specific pathway enrichment of the proteome, intermyofibrillar mitochondrial volume, or mitochondrial respiratory function. As it relates to cross-bridge cycling, remarkably, the overt loss of contractile function in i-mPCKO muscle was reversed in permeabilized fibers supplied with exogenous Ca2+ and ATP, with active tension being similar between i-mPCKO and WT mice, regardless of Ca2+ concentration. Actin-myosin motility was also similar in skeletal muscle from i-mPCKO and WT mice. In conclusion, neither mitochondrial abundance/function, nor actomyosin cross-bridge cycling, are the underlying driver of contractile dysfunction in i-mPCKO mice. NEW & NOTEWORTHY: The mechanism underlying dramatic loss of muscle contractile function with inducible deletion of both E1A binding protein p300 (p300) and cAMP-response element-binding protein binding protein (CBP) in skeletal muscle remains unknown. Here, we find that impairments in mitochondrial function or cross-bridge cycling are not the underlying mechanism of action. Future work will investigate other aspects of excitation-contraction coupling, such as Ca2+ handling and membrane excitability, as contractile function could be rescued by permeabilizing skeletal muscle, which provides exogenous Ca2+ and bypasses membrane depolarization. [ABSTRACT FROM AUTHOR]

Aspirin, also named acetylsalicylate, can directly acetylate the side‐chain of lysine in protein, which leads to the possibility of unexplained drug effects. Here, the study used isotopic‐labeling aspirin‐d3 with mass spectrometry analysis to discover that aspirin directly acetylates 10 HDACs proteins, including SIRT1, the most studied NAD+‐dependent deacetylase. SIRT1 is also acetylated by aspirin in vitro. It is also identified that aspirin directly acetylates lysine 408 of SIRT1, which abolishes SIRT1 deacetylation activity by impairing the substrates binding affinity. Interestingly, the lysine 408 of SIRT1 can be acetylated by CBP acetyltransferase in cells without aspirin supplement. Aspirin can inhibit SIRT1 to increase the levels of acetylated p53 and promote p53‐dependent apoptosis. Moreover, the knock‐in mice of the acetylation‐mimic mutant of SIRT1 show the decreased production of pro‐inflammatory cytokines and maintain intestinal immune homeostasis. The study indicates the importance of the acetylated internal functional site of SIRT1 in maintaining intestinal immune homeostasis. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a multifactorial and progressive neurodegenerative disease, associated with aging. A total of forty benzylidene‐indenone derivatives were synthesized in search of multi‐target‐directed ligands (MTDL) against AD. Compound 9 was found as the most promising MTDL in this study. It was demonstrated to selectively inhibit human butyrylcholinesterase, increase the gene expression of choline acetyltransferase (CHAT), and promote neurite outgrowth in SH‐SY5Y cells. The compound was also predicted to be able to permeate across the lipid‐infused bilayer, indicating its ability to cross the blood‐brain barrier. The abovementioned findings show compound 9 and its analogs warrant further exploration as potential MTDL anti‐AD agents. [ABSTRACT FROM AUTHOR]

Background: Epigenetic modifications of histones play important roles in the response of eukaryotic organisms to environmental stress. However, many histone acetyltransferases (HATs), which are responsible for histone acetylation, and their roles in mediating the tick response to cold stress have yet to be identified. In the present study, HATs were molecularly characterized and their associations with the cold response of the tick Haemaphysalis longicornis explored. Methods: HATs were characterized by using polymerase chain reaction (PCR) based on published genome sequences, followed by multiple bioinformatic analyses. The differential expression of genes in H. longicornis under different cold treatment conditions was evaluated using reverse transcription quantitative PCR (RT-qPCR). RNA interference was used to explore the association of HATs with the cold response of H. longicornis. Results: Two HAT genes were identified in H. longicornis (Hl), a GCN5-related N-acetyltransferase (henceforth HlGNAT) and a type B histone acetyltransferase (henceforth HlHAT-B), which are respectively 960 base pairs (bp) and 1239 bp in length. Bioinformatics analysis revealed that HlGNAT and HlHAT-B are unstable hydrophilic proteins characterized by the presence of the acetyltransferase 16 domain and Hat1_N domain, respectively. RT-qPCR revealed that the expression of HlGNAT and HlHAT-B decreased after 3 days of cold treatment, but gradually increased with a longer period of cold treatment. The mortality rate following knockdown of HlGNAT or HlHAT-B by RNA interference, which was confirmed by RT-qPCR, significantly increased (P < 0.05) when H. longicornis was treated at the lowest lethal temperature (− 14 °C) for 2 h. Conclusions: The findings demonstrate that HATs may play a crucial role in the cold response of H. longicornis. Thus further research is warranted to explore the mechanisms underlying the epigenetic regulation of the cold response in ticks. [ABSTRACT FROM AUTHOR]

Deciphering lipid metabolism in white adipose tissue (WAT) depots during weight gain is important to understand the heterogeneity of WAT and its roles in obesity. Here, we examined the expression of key enzymes of lipid metabolism and changes in the morphology of representative visceral (epididymal) and subcutaneous (inguinal) WAT (eWAT and iWAT, respectively)-in adult male rats acclimated to cold (4 ± 1 °C) for 45 days and reacclimated to room temperature (RT, 22 ± 1 °C) for 1, 3, 7, 12, 21, or 45 days. The relative mass of both depots decreased to a similar extent after cold acclimation. However, fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH), and medium-chain acyl-CoA dehydrogenase (ACADM) protein level increased only in eWAT, whereas adipose triglyceride lipase (ATGL) expression increased only in iWAT. During reacclimation, the relative mass of eWAT reached control values on day 12 and that of iWAT on day 45 of reacclimation. The faster recovery of eWAT mass is associated with higher expression of FAS, acetyl-CoA carboxylase (ACC), G6PDH, and ACADM during reacclimation and a delayed increase in ATGL. The absence of an increase in proliferating cell nuclear antigen suggests that the observed depot-specific mass increase is predominantly due to metabolic adjustments. In summary, this study shows a differential rate of visceral and subcutaneous adipose tissue weight regain during post-cold reacclimation of rats at RT. Faster recovery of the visceral WAT as compared to subcutaneous WAT during reacclimation at RT could be attributed to observed differences in the expression patterns of lipid metabolic enzymes. [ABSTRACT FROM AUTHOR]

Background: Periodontitis is a chronic osteolytic inflammatory disease, where anti-inflammatory intervention is critical for restricting periodontal damage and regenerating alveolar bone. Ropinirole, a dopamine D2 receptor agonist, has previously shown therapeutic potential for periodontitis but the underlying mechanism is still unclear. Methods: Human gingival fibroblasts (HGFs) treated with LPS were considered to mimic periodontitis in vitro. The dosage of Ropinirole was selected through the cell viability of HGFs evaluation. The protective effects of Ropinirole on HGFs were evaluated by detecting cell viability, cell apoptosis, and pro-inflammatory factor levels. The molecular docking between NAT10 and Ropinirole was performed. The interaction relationship between NAT10 and KLF6 was verified by ac4C Acetylated RNA Immunoprecipitation followed by qPCR (acRIP-qPCR) and dual-luciferase reporter assay. Results: Ropinirole alleviates LPS-induced damage of HGFs by promoting cell viability, inhibiting cell apoptosis and the levels of IL-1β, IL-18, and TNF-α. Overexpression of NAT10 weakens the effects of Ropinirole on protecting HGFs. Meanwhile, NAT10-mediated ac4C RNA acetylation promotes KLF6 mRNA stability. Upregulation of KLF6 reversed the effects of NAT10 inhibition on HGFs. Conclusions: Taken together, Ropinirole protected HGFs through inhibiting the NAT10 ac4C RNA acetylation to decrease the KLF6 mRNA stability from LPS injury. The discovery of this pharmacological and molecular mechanism of Ropinirole further strengthens its therapeutic potential for periodontitis. [ABSTRACT FROM AUTHOR]

Background: N-acetyltransferase 10 (NAT10) serves as a critical enzyme in mediating the N4-acetylcytidine (ac4C) that ensures RNA stability and effective translation processes. The role of NAT10 in driving the advancement of breast cancer remains uninvestigated. Methods: We observed an increase in NAT10 expression, both at mRNA level through the analysis of the Cancer Genome Atlas (TCGA) database and at the protein level of tumor tissues from breast cancer patients. We determined that a heightened expression of NAT10 served as a predictor of an unfavorable clinical outcome. By screening the Cancer Cell Line Encyclopedia (CCLE) cell bank, this expression pattern of NAT10 was consistency found across almost all the classic breast cancer cell lines. Results: Functionally, interference of NAT10 expression exerts an inhibitory effect on proliferation and invasion of breast cancer cells. By using ac4C RNA immunoprecipitation (ac4c-RIP) and acRIP-qPCR assays, we identified a reduction of ac4C enrichment within the ATP binding cassette (ABC) transporters, multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP), consequent to NAT10 suppression. Expressions of MDR1 and BCRP exhibited a positive correlation with NAT10 expression in tumor tissues, and the inhibition of NAT10 in breast cancer cells resulted in a decrease of MDR1 and BCRP expression. Therefore, the overexpressing of MDR1 and BCRP could partially rescue the adverse consequences of NAT10 depletion. In addition, we found that, remodelin, a NAT10 inhibitor, reinstated the susceptibility of capecitabine-resistant breast cancer cells to the chemotherapy, both in vitro and in vivo. Conclusion: The results of our study demonstrated the essential role of NAT10-mediated ac4c-modification in breast cancer progression and provide a novel strategy for overcoming chemoresistance challenges. [ABSTRACT FROM AUTHOR]

Histone modifications commonly integrate environmental cues with cellular metabolic outputs by affecting gene expression. However, chromatin modifications such as acetylation do not always correlate with transcription, pointing towards an alternative role of histone modifications in cellular metabolism. Using an approach that integrates mass spectrometry-based histone modification mapping and metabolomics with stable isotope tracers, we demonstrate that elevated lipids in acetyltransferase-depleted hepatocytes result from carbon atoms derived from deacetylation of hyperacetylated histone H4 flowing towards fatty acids. Consistently, enhanced lipid synthesis in acetyltransferase-depleted hepatocytes is dependent on histone deacetylases and acetyl-CoA synthetase ACSS2, but not on the substrate specificity of the acetyltransferases. Furthermore, we show that during diet-induced lipid synthesis the levels of hyperacetylated histone H4 decrease in hepatocytes and in mouse liver. In addition, overexpression of acetyltransferases can reverse diet-induced lipogenesis by blocking lipid droplet accumulation and maintaining the levels of hyperacetylated histone H4. Overall, these findings highlight hyperacetylated histones as a metabolite reservoir that can directly contribute carbon to lipid synthesis, constituting a novel function of chromatin in cellular metabolism. Synopsis: It remains unclear if chromatin modifications directly influence cellular metabolic pathways. This study reveals that hyperacetylated histone H4 acts as an acetate reservoir that contributes carbon atoms to lipid synthesis in hepatocytes. Depletion of histone and non-histone acetyltransferases in hepatocytes leads to elevated lipids, with hyperacetylated histone H4 contributing carbon atoms to fatty acids. Enhanced lipid synthesis in acetyltransferase-depleted hepatocytes depends on histone deacetylation and acetyl-CoA synthetase ACSS2. Overexpression of acetyltransferases inhibits diet-induced lipogenesis and maintains hyperacetylated histone H4 levels in vitro and mouse liver. Acetylated histones represent a reservoir for acetyl-CoA, via which acetyltransferases and deacetylases can directly modulate lipid accumulation. [ABSTRACT FROM AUTHOR]

Histone modifications, especially the lysine acetylation, have drawn increasing attention in cancer research area. The aim of this research is to explore the molecular mechanisms underlying the regulation of lysine acetyltransferase 2 A (KAT2A) on colorectal cancer (CRC). Clinical samples were collected from patients with CRC. The expression and correlation between KAT2A and ferroptosis suppressor SLC7A11 and glutathione peroxidase 4 (GPX4) were measured by qPCR and Pearson correlation analysis. NCP cells were transfected with KAT2A overexpression vectors or siRNAs. The proliferation of cells was measured by CCK-8 and colony formation assay. Cell migration and invasion was analyzed by Transwell. The accumulation of lipid peroxidation, ferrous iron, and malondialdehyde (MDA) were analyzed to determine cell ferroptosis. The expression of cell metastasis biomarkers was measured by western blotting assay. Interaction between KAT2A with GPX4 gene was measured by chromatin immunoprecipitation (ChIP). The KAT2A, GPX4, and SLC7A11 expression was notably elevated in tumor tissues compared with the paired non-tumor tissues from CRC patients. The expression of KAT2A showed positive correlation with GPX4 and SLC7A11. Overexpression of KAT2A recovered the cell proliferation, migration, and invasion of CRC cells that suppressed by ferroptosis inducer erastin, along with deceased levels of ROS, iron, Fe2+, and MDA. Overexpression of KAT2A suppressed E-cadherin level and increased N-cadherin, Snail, and Vimentin expression in CRC cells. KAT2A interacted with GPX4 promoter region. In conclusion, our findings demonstrated that KAT2A modulates the histone acetylation of GPX4 to regulate proliferation, metastasis, and ferroptosis of CRC cells. [ABSTRACT FROM AUTHOR]

Carnitine acetyltransferase (CAT) and Enoyl-CoA hydratase short-chain 1 (ECHS1) are considered key enzymes that regulate the β-oxidation of fatty acids. However, very few studies have investigated their full length and expression in genetically improved farmed tilapia (GIFT, Oreochromis niloticus), an important aquaculture species in China. Here, we cloned CAT and ECHS1 full-length cDNA via the rapid amplification of cDNA ends, and the expressions of CAT and ECHS1 in the liver of juvenile GIFT were detected in different fat and carnitine diets, as were the changes in the lipometabolic enzymes and serum biochemical indexes of juvenile GIFT in diets with different fat and carnitine levels. CAT cDNA possesses an open reading frame (ORF) of 2167 bp and encodes 461 amino acids, and the ECHS1 cDNA sequence is 1354 bp in full length, the ORF of which encodes a peptide of 391 amino acids. We found that juvenile GIFT had higher lipometabolic enzyme activity and lower blood CHOL, TG, HDL-C, and LDL-C contents when the dietary fat level was 2% or 6% and when the carnitine level was 500 mg/kg. We also found that the expression of ECHS1 and CAT genes in the liver of juvenile GIFT can be promoted by a 500 mg/kg carnitine level and 6% fat level feeding. These results suggested that CAT and ECHS1 may participate in regulating lipid metabolism, and when 2% or 6% fat and 500 mg/kg carnitine are added to the feed, it is the most beneficial to the liver and lipid metabolism of juvenile GIFT. Our results may provide a theoretical basis for GIFT feeding and treating fatty liver disease. [ABSTRACT FROM AUTHOR]

Background: Whole genome sequencing of clinical bacterial isolates holds promise in predicting their susceptibility to antibiotic therapy, based on a detailed understanding of the phenotypic manifestation of genotypic variation. The aac(6′) aminoglycoside acetyltransferase gene family is the most abundant aminoglycoside resistance determinant encountered in clinical practice. A variety of AAC(6′) isozymes have been described, suggesting a phenotypic distinction between subtype I, conferring resistance to amikacin (AMK), and subtype II, conferring resistance to gentamicin (GEN) instead. However, the epidemiology and thus clinical relevance of the various and diverse isozymes and their phenotypic distinction demand systematic and contemporary re-assessment to reliably predict bacterial susceptibility to aminoglycoside antibiotics. Methods: We analyzed the resistance gene annotations of 657,603 clinical bacterial isolates to assess the prevalence and diversity of aac(6′) genes. Seventeen unique aac(6′) amino acid sequences were cloned and expressed under defined promoter control in otherwise isogenic E. coli cells for phenotypic analysis with twenty distinct aminoglycoside antibiotics. A panel of clinical isolates was analyzed for the genotype–phenotype correlation of aac(6′). Results: An aac(6′) resistance gene annotation was found in 139,236 (21.2%) of the clinical isolates analyzed. AMK resistance-conferring aac(6′)-I genes dominated in Enterobacterales (28.5%). In Pseudomonas aeruginosa and Acinetobacter baumannii, a gene conferring the aac(6′)-II phenotype but annotated as aac(6′)-Ib4 was the most prevalent. None of the aac(6′) genes were annotated as subtype III, but gene aac(6′)-Ii identified in Gram-positive isolates displayed a subtype III phenotype. Genes that were annotated as aac(6′)-Ib11 in Enterobacterales conferred resistance to both AMK and GEN, which we propose constitutes a novel subtype IV when applying established nomenclature. A phenotypic assessment facilitated structural re-assessment of the substrate promiscuity of AAC(6′) enzymes. Conclusions: Our study provides the most comprehensive analysis of clinically relevant aac(6′) gene sequence variations to date, providing new insights into a differentiated substrate promiscuity across the genotypic spectrum of this gene family, thus translating into a critical contribution towards the development of amino acid sequence-based in silico antimicrobial susceptibility testing (AST).