SIRT2-mediated FOXO3a deacetylation drives its nuclear translocation triggering FasL-induced cell apoptosis during renal ischemia reperfusion

SIRT2-dependent DKK1 deacetylation aggravates polycystic ovary syndrome by targeting the TGF-β1/Smad3 signaling pathway

BACKGROUND

Polycystic ovarian syndrome (PCOS) is a prevalent metabolic and endocrine condition in females of reproductive age. This work was to discover the underlying role of Dickkopf 1 (DKK1) and its putative regulating mechanism in P COS.

METHODS

Mice recieved dehydroepiandrosterone (DHEA) injection to establish the in vivo P COS model.Hematoxylin and eosin (H&E) staining was performed for histological analysis. RT-qP CR and Western blotting were used to detect gene and protein expression. CCK-8 and flow cytometry assays were applied to detect cell viability and apoptosis. Co-immunoprecipitation (Co-IP) and immunoprecipitation (IP) were applied to assess association between DKK1 and SIRT2.

RESULTS

In this work, DKK1 is downregulated in P COS rats. It was revealed that DKK1 knockdown induced apoptosis and suppressed proliferation in KGN cells, whereas DKK1 overexpression had exactly the opposite effects. In addition, DKK1 deactivates the T GF-β1/SMad3 signaling pathway, thereby controlling KGN cell proliferation and apoptosis. Besides, SIRT2 inhibition reversed the impact of DKK1 overexpression on KGN cell proliferation and apoptosis. Furthermore, SIRT2 downregulated DKK1 expression by deacetylating DKK1 in KGN cells.

DISCUSSION

Altogether, we concluded that SIRT2-induced deacetylation of DKK1 triggers T GF-β1/Smad3 hyperactivation, thereby inhibiting proliferation and promoting apoptosis of KGN cells. The above results indicated that DKK1 might function as a latent target for P COS treatment.

Investigating the mechanism of tricyclic decyl benzoxazole -induced apoptosis in liver Cancer cells through p300-mediated FOXO3 activation

OBJECTIVE

To investigate whether tricyclic decylbenzoxazole (TDB) regulates liver cancer cell proliferation and apoptosis through p300-mediated FOXO acetylation.

METHODS

Sequencing, adenovirus, and lentivirus transfection were performed in human liver cancer cell line SMMC-7721 and apoptosis was detected by Tunel, Hoechst, and flow cytometry. TEM for mitochondrial morphology, MTT for cell proliferation ability, Western blot, and PCR were used to detect protein levels and mRNA changes.

RESULTS

Sequencing analysis and cell experiments confirmed that TDB can promote the up-regulation of FOXO3 expression. TDB induced FOXO3 up-regulation in a dose-dependent manner, promoted the expression of p300 and Bim, and enhanced the acetylation and dephosphorylation of FOXO3, thus promoting apoptosis. p300 promotes apoptosis of cancer cells through Bim and other proteins, while HAT enhances the phosphorylation of FOXO3 and inhibits apoptosis. Overexpression of FOXO3 can increase the expression of exo-apoptotic pathways (FasL, TRAIL), endo-apoptotic pathways (Bim), and acetylation at the protein level and inhibit cell proliferation and apoptotic ability, while FOXO3 silencing or p300 mutation can partially reverse apoptosis. In tumor tissues with overexpression of FOXO3, TDB intervention can further increase the expression of p53 and caspase-9 proteins in tumor cells, resulting in loss of mitochondrial membrane integrity during apoptosis, the release of cytoplasm during signal transduction, activation of caspase-9 and synergistic inhibition of growth.

CONCLUSION

TDB induces proliferation inhibition and promotes apoptosis of SMMC-7721 cells by activating p300-mediated FOXO3 acetylation.

Therapeutic Potential of Natural Compounds Acting through Epigenetic Mechanisms in Cardiovascular Diseases: Current Findings and Future Directions

Cardiovascular diseases (CVDs) remain a leading global cause of morbidity and mortality. These diseases have a multifaceted nature being influenced by a multitude of biochemical, genetic, environmental, and behavioral factors. Epigenetic modifications have a crucial role in the onset and progression of CVD. Epigenetics, which regulates gene activity without altering the DNA's primary structure, can modulate cardiovascular homeostasis through DNA methylation, histone modification, and non-coding RNA regulation. The effects of environmental stimuli on CVD are mediated by epigenetic changes, which can be reversible and, hence, are susceptible to pharmacological interventions. This represents an opportunity to prevent diseases by targeting harmful epigenetic modifications. Factors such as high-fat diets or nutrient deficiencies can influence epigenetic enzymes, affecting fetal growth, metabolism, oxidative stress, inflammation, and atherosclerosis. Recent studies have shown that plant-derived bioactive compounds can modulate epigenetic regulators and inflammatory responses, contributing to the cardioprotective effects of diets. Understanding these nutriepigenetic effects and their reversibility is crucial for developing effective interventions to combat CVD. This review delves into the general mechanisms of epigenetics, its regulatory roles in CVD, and the potential of epigenetics as a CVD therapeutic strategy. It also examines the role of epigenetic natural compounds (ENCs) in CVD and their potential as intervention tools for prevention and therapy.

Sirtuins in kidney diseases: potential mechanism and therapeutic targets

Sirtuins, which are NAD+-dependent class III histone deacetylases, are involved in various biological processes, including DNA damage repair, immune inflammation, oxidative stress, mitochondrial homeostasis, autophagy, and apoptosis. Sirtuins are essential regulators of cellular function and organismal health. Increasing evidence suggests that the development of age-related diseases, including kidney diseases, is associated with aberrant expression of sirtuins, and that regulation of sirtuins expression and activity can effectively improve kidney function and delay the progression of kidney disease. In this review, we summarise current studies highlighting the role of sirtuins in renal diseases. First, we discuss sirtuin family members and their main mechanisms of action. We then outline the possible roles of sirtuins in various cell types in kidney diseases. Finally, we summarise the compounds that activate or inhibit sirtuin activity and that consequently ameliorate renal diseases. In conclusion, targeted modulation of sirtuins is a potential therapeutic strategy for kidney diseases. Video Abstract.

FOXO3a-interacting proteins' involvement in cancer: a review

Due to its role in apoptosis, differentiation, cell cycle arrest, and DNA damage repair in stress responses (oxidative stress, hypoxia, chemotherapeutic drugs, and UV irradiation or radiotherapy), FOXO3a is considered a key tumor suppressor that determines radiotherapeutic and chemotherapeutic responses in cancer cells. Mutations in the FOXO3a gene are rare, even in cancer cells. Post-translational regulations are the main mechanisms for inactivating FOXO3a. The subcellular localization, stability, transcriptional activity, and DNA binding affinity for FOXO3a can be modulated via various post-translational modifications, including phosphorylation, acetylation, and interactions with other transcriptional factors or regulators. This review summarizes how proteins that interact with FOXO3a engage in cancer progression.

The forkhead box O3 (FOXO3): a key player in the regulation of ischemia and reperfusion injury

Forkhead box O3 is a protein encoded by the FOXO3 gene expressed throughout the body. FOXO3 could play a crucial role in longevity and many other pathologies, such as Alzheimer's disease, glioblastoma, and stroke. This study is a comprehensive review of the expression of FOXO3 under ischemia and reperfusion (IR) and the molecular mechanisms of its regulation and function. We found that the expression level of FOXO3 under ischemia and IR is tissue-specific. Specifically, the expression level of FOXO3 is increased in the lung and intestinal epithelial cells after IR. However, FOXO3 is downregulated in the kidney after IR and in the skeletal muscles following ischemia. Interestingly, both increased and decreased FOXO3 expression have been reported in the brain, liver, and heart following IR. Nevertheless, these contribute to stimulating ischemia and reperfusion injury via the induction of inflammatory response, apoptosis, autophagy, mitophagy, pyroptosis, and oxidative damage. These results suggest that FOXO3 could play protective effects in some organs and detrimental effects in others against IR injury. Most importantly, these findings indicate that controlling FOXO3 expression, genetically or pharmacologically, could contribute to preventing or treating ischemia and reperfusion damage.

SIRT7 silencing by miR-152-3p confers cell apoptosis and renal functional impairment induced by renal ischaemia/reperfusion injury

PURPOSE

Acute kidney injury (AKI) induced by renal ischaemia/reperfusion (I/R) during renal transplantation has been reported to be linked to the regulation of SIRT2, one of the members of SIRTUINS family. Current work is attempted to explore the influence and mechanism of SIRT7 in renal cell apoptosis controlled by miR-152-3p during renal I/R injury.

METHODS

Three databases were used to select the miRNAs regulating the expression of SIRT7. Overexpression and inhibition of miR-152-3p and Luciferase assay were employed to certify the modulation of miR-152-3p to SIRT7 in cells. RT-qPCR assay was used to measure the mRNA levels. Western blot assay was employed to determine the expression of proteins. TUNEL assay and Flow Cytometry were conducted to analyze cell apoptosis.

RESULTS

SIRT7 expression decreased in tissues of AKI patients and rats underwent renal I/R, which was associated with enhanced impairment of renal function. SIRT7 downregulation was attributed to the direct inhibition by miR-152-3p due to binding and inhibiting its seed sequence in 3'-UTR of SIRT7 mRNA. Consequently, the upregulation of miR-152-3p led to an inhibition of SIRT7 expression, an increase in expression of extrinsic apoptosis molecules containing FOXO3a, Bim, and caspase3, and apoptotic renal cells; while miR-152-3p inhibition abolished these phenotypes.

CONCLUSION

SIRT7 downregulation by miR-152-3p is a leading cause of renal cell apoptosis and functional impairment induced by renal I/R. Inhibition of miR-152-3p to restore SIRT7 expression can be a promising strategy against renal I/R injury.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Bombesin receptor-activated protein exacerbates cisplatin-induced AKI by regulating the degradation of SIRT2

BACKGROUND

Acute kidney injury (AKI) is a public health problem with no specific therapies in the clinic and the underlying pathogenesis of AKI remains obscure. Bombesin receptor-activated protein (BRAP, C6ORF89 protein) was initially discovered as a ligand for a previously orphan G-protein-coupled receptor bombesin-like receptor-3. At present, accepted biological effects of BRAP include cell cycle progression, wound repair and the activation of histone deacetylases. However, its role in kidney disease is unknown. In this study we have investigated the role of BRAP and underlying mechanisms involved in cisplatin (CP)-induced AKI.

METHODS

Here we used Bc004004 (homologous of C6ORF89 in mice) knockout mice and HK2 cells to investigate the effect of BRAP on AKI in vitro and in vivo. We analyzed ChIP-Seq and RNA-Seq data to search for the upstream regulators of BRAP and downstream mediators of BRAP action in AKI. Immunostaining, real-time polymerase chain reaction (PCR), co-immunoprecipitation, a dual-luciferase reporter assay and ChIP-PCR assay were applied to reveal the upstream and downstream regulation mechanism of BRAP during cisplatin-induced AKI.

RESULTS

BRAP was downregulated in mice and human kidneys with AKI. Global Bc004004 deletion alleviated tubular cell apoptosis and necroptosis in CP-induced AKI mice, whereas local overexpression of BRAP in kidneys aggravated them. Pan-caspase inhibitor Z-VAD pretreatment attenuated CP-induced blood creatinine increase and kidney injury in wild-type mice but not in BRAP -/- mice. The activation of mixed lineage kinase like-domain was magnified by Z-VAD in CP-treated mice, especially in BRAP -/- mice. The cytoprotective effect of Z-VAD was more substantial than necrostatin-1 (Nec-1, an inhibitor of necroptosis) in CP-treated human kidney proximal tubular epithelial (HK2) cells. Furthermore, Nec-1 pretreatment reduced the CP-induced cell death in BRAP overexpression HK2 cells but did not work in cells with normal BRAP levels. We determined that CP treatment activated the nuclear factor-κB subunit P65 and inhibition of P65 increased the messenger RNA (mRNA) levels of BRAP in HK2 cells. The chromatin immunoprecipitation assay and dual-luciferase reporter gene assay verified P65 binding to the C6ORF89 promoter and reduced its mRNA expression upon CP treatment. Next we found that sirtuin 2 (SIRT2) was downregulated in CP-induced AKI and BRAP levels directly impacted the protein levels of SIRT2. Our findings further confirmed that BRAP regulates the SIRT2 protein levels by affecting SIRT2's interactions with E3 ubiquitin ligase HRD1 and subsequent proteasomal degradation.

CONCLUSIONS

Our results demonstrated that BRAP played an important role in tubular cell apoptosis and necroptosis during CP-induced AKI. Safe and efficient BRAP inhibitors might be effective therapeutic options for AKI.

Sirtuins as novel pharmacological targets in podocyte injury and related glomerular diseases

Podocyte injury is a major cause of proteinuria in kidney diseases, and persistent loss of podocytes leads to rapid irreversible progression of kidney disease. Sirtuins, a class of nicotinamide adenine dinucleotide-dependent deacetylases, can promote DNA repair, modify transcription factors, and regulate the cell cycle. Additionally, sirtuins play a critical role in renoprotection, particularly against podocyte injury. They also have pleiotropic protective effects on podocyte injury-related glomerular diseases, such as improving the immune inflammatory status and oxidative stress levels, maintaining mitochondrial homeostasis, enhancing autophagy, and regulating lipid metabolism. Sirtuins deficiency causes podocyte injury in different glomerular diseases. Studies using podocyte sirtuin-specific knockout and transgenic models corroborate this conclusion. Of note, sirtuin activators have protective effects in different podocyte injury-related glomerular diseases, including diabetic kidney disease, focal segmental glomerulosclerosis, membranous nephropathy, IgA nephropathy, and lupus nephritis. These findings suggest that sirtuins are promising therapeutic targets for preventing podocyte injury. This review provides an overview of recent advances in the role of sirtuins in kidney diseases, especially their role in podocyte injury, and summarizes the possible rationale for sirtuins as targets for pharmacological intervention in podocyte injury-related glomerular diseases.

Mitochondrial sirtuin 3 and various cell death modalities

Sirtuin 3, a member of the mammalian sirtuin family of proteins, is involved in the regulation of multiple processes in cells. It is a major mitochondrial NAD⁺-dependent deacetylase with a broad range of functions, such as regulation of oxidative stress, reprogramming of tumor cell energy pathways, and metabolic homeostasis. One of the intriguing functions of sirtuin 3 is the regulation of mitochondrial outer membrane permeabilization, a key step in apoptosis initiation/progression. Moreover, sirtuin 3 is involved in the execution of various cell death modalities, which makes sirtuin 3 a possible regulator of crosstalk between them. This review is focused on the role of sirtuin 3 as a target for tumor cell elimination and how mitochondria and reactive oxygen species (ROS) are implicated in this process.

Epigenetic regulation in cardiovascular disease: mechanisms and advances in clinical trials

Epigenetics is closely related to cardiovascular diseases. Genome-wide linkage and association analyses and candidate gene approaches illustrate the multigenic complexity of cardiovascular disease. Several epigenetic mechanisms, such as DNA methylation, histone modification, and noncoding RNA, which are of importance for cardiovascular disease development and regression. Targeting epigenetic key enzymes, especially the DNA methyltransferases, histone methyltransferases, histone acetylases, histone deacetylases and their regulated target genes, could represent an attractive new route for the diagnosis and treatment of cardiovascular diseases. Herein, we summarize the knowledge on epigenetic history and essential regulatory mechanisms in cardiovascular diseases. Furthermore, we discuss the preclinical studies and drugs that are targeted these epigenetic key enzymes for cardiovascular diseases therapy. Finally, we conclude the clinical trials that are going to target some of these processes.

SIRT2 tyrosine nitration by peroxynitrite in response to renal ischemia/reperfusion injury

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are the production of renal ischemia/reperfusion (I/R). The current study is to elucidate a mechanism of SIRT2 tyrosine nitration to accelerate the cell apoptosis induced by peroxynitrite (ONOO‾), the most reactive and deleterious RNS type in renal ischemia/reperfusion (I/R) injury. Our results demonstrate that there is a significant enhancement of the 3-nitrotyrosine levels in renal tissues of Acute Kidney Injury (AKI) patients and rats that underwent renal I/R, and a positive correlation between the 3-nitrotyrosine level and renal function impairment, indicative of an accumulation of peroxynitrite. Notably, peroxynitrite-evoked nitration of SIRT2 destroyed its enzymatic activity and the capability to deacetylate FOXO3a, and enhanced expression of Bim and caspase3, facilitating renal cell apoptosis in renal ischemia/reperfusion and SIN-1(peroxynitrite donor) treatment in vitro, and these effects were reversed by FeTMPyP, a peroxynitrite decomposition scavenger. Importantly, we identified that the tyrosine 86 is responsible for SIRT2 nitration and inactivation using site-mutation assay and Mass Spectrography analysis. Altogether, these findings point to a novel protective mechanism that an inhibition of SIRT2 tyrosine nitration can be a promising strategy to prevent ischemic renal diseases involving AKI.

Acetylation of ANXA1 reduces caspase-3 activation by enhancing the phosphorylation of caspase-9 under OGD/R conditions

SIRT2, a Class III HDACs, aggravates cell damage and activates caspase-3 under oxygen-glucose deprivation/reoxygenation and glucose (OGD/R) conditions. In this paper, we demonstrated the adverse effects of SIRT2 on cells after OGD/R attacks, which were mediated by increased interactions between SIRT2 and ANXA1, and explicated the mechanisms by which acetylated ANXA1 affects the activation and cleavage of caspase-3. We found that the acetylation level of ANXA1 was decreased through the its increased interactions with SIRT2 after the OGD/R insult. The lysine 312 residue (K312) was selected as the target site in ANXA1 because it is associated with SIRT2, and its mimic (K312Q) and silent (K312R) mutants were then established through site mutagenesis. Under OGD/R conditions, the acetylation mimic of K312Q ANXA1 accumulated in the cytoplasm, decreasing the activity levels of caspase-3 and the upstream initiator caspase-9, compared with the levels of WT and K312R ANXA1. Furthermore, K312Q ANXA1 intervened in the interactions of caspase-3 to caspase-9 by increasing the phosphorylation levels of caspase-9 and inhibited its cleavage by downregulating PRKAR2B, a regulatory subunit of protein kinase A (PKA). In this process, K312Q ANXA1 was found to be directly associated with PRKAR2B, diminishing its restriction on the catalytic subunit of PKA. In conclusion, acetylated ANXA1 can promote the phosphorylation of caspase-9 to decrease the activation of caspase-3 by enhancing the expression of a kinase upstream of caspase-9 after the OGD/R stimulation.

Sirtuins and Renal Oxidative Stress

Renal failure is a major health problem that is increasing worldwide. To improve clinical outcomes, we need to understand the basic mechanisms of kidney disease. Aging is a risk factor for the development and progression of kidney disease. Cells develop an imbalance of oxidants and antioxidants as they age, resulting in oxidative stress and the development of kidney damage. Calorie restriction (CR) is recognized as a dietary approach that promotes longevity, reduces oxidative stress, and delays the onset of age-related diseases. Sirtuins, a type of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, are considered to be anti-aging molecules, and CR induces their expression. The sirtuin family consists of seven enzymes (Sirt1–7) that are involved in processes and functions related to antioxidant and oxidative stress, such as DNA damage repair and metabolism through histone and protein deacetylation. In fact, a role for sirtuins in the regulation of antioxidants and redox substances has been suggested. Therefore, the activation of sirtuins in the kidney may represent a novel therapeutic strategy to enhancing resistance to many causative factors in kidney disease through the reduction of oxidative stress. In this review, we discuss the relationship between sirtuins and oxidative stress in renal disease.

Association of T2285C polymorphism in PARP1 gene coding region with its expression, activity and NSCLC risk along with prognosis

Poly (ADP-ribose) polymerase-1(PARP1), a DNA repair gene, is the crucial player in the maintenance of genome integrity. T2285C polymorphism in coding region of PARP1 has been reported to be associated with susceptibility to tumors. We explored the relation and mechanism of T2285C polymorphism of PARP1 to its expression and activity along with risk and prognosis in NSCLC. mRNA expression was measured using qRT-PCR assay or collected from TCGA dataset. Protein expression was examined with immunoblotting assay. Genotypes were determined by PCR-RFLP and sequencing approaches. PARP1 activity was determined with enzyme activity assay. Regulation of SIRT7 to PARP1 were determined by over-expression and small interference experiment. Association of PARP1 T2285C polymorphism with NSCLC risk was evaluated via multiple logistic regression analysis. Comparison of treatment response and PFS of NSCLC patients among different genotypes or regimens was made by Chi-square test. Results indicated that mRNA and protein expression of PARP1 dramatically increased in NSCLC tissues in comparison to paired para-carcinoma tissues (P<0.05). TC/CC mutant genotypes were associated with markedly enhanced PARP1 mRNA level compared with TT genotype (P=0.011). No significant difference was discovered in PARP1 protein expression among TT, TC or CC genotypes (P>0.05). Subjects with variant allele C had higher risk of NSCLC in comparison to allele T carriers [odds ratio (OR) =1.560; P=0.000]. NSCLC patients carrying mutational TC or CC genotypes were correlated with unfavorable response to platinum-based chemotherapy (TT vs.TC vs.CC, P=0.010), and shorter PFS compared to TT genotype (TT vs.TC vs.CC, P=0.009). T2285C mutation of PARP1 resulted in the enhancement of its mRNA, but the decrease of enzyme activity in tumor cell. Overexpression of SIRT7 attenuated PARP1 expression and activity. These findings suggest the variant allele C of T2285C polymorphism of PARP1 linked to an increase of NSCLC risk, and unfavorable efficacy and prognosis of NSCLC patients with platinum-based chemotherapy, which might be associated with enhancement of its mRNA expression and the diminishment of activity. Identification of PARP1 T2285C polymorphism and mRNA expression may be the promising way for the individualized treatment of NSCLC.

The link between deacetylation and hepatotoxicity induced by exposure to hexavalent chromium

•

Cr(VI) can induce inflammatory, oxidative stress, and apoptosis in rat liver.

•

Cr(VI) induces inflammatory response in the liver by inhibiting deacetylation.

•

Oxidative stress caused by Cr(VI) is related to the inhibition of deacetylation.

•

Cr(VI) aggravates hepatocyte apoptosis by inhibiting deacetylation in rats.

•

Cr(VI) induces liver injury via inhibition of the deacetylation of Sirt1.

Introduction

Hexavalent chromium (Cr(VI)), one of the toxic heavy metals, poses a serious threat to human and animal health. Protein acetylation regulates the structure and function of most proteins in a variety of ways. However, the hepatotoxicity of Cr(VI) and whether it is related to deacetylation remains largely unknown.

Objectives

We aimed to explore the link between the deacetylation of silent information regulator two ortholog 1 (Sirt1) and hepatotoxicity induced by Cr(VI) exposure, and to better clarify the biological mechanism of liver injury induced by Cr(VI).

Methods

We established a model of liver injury of K₂Cr₂O₇ by injecting rats intraperitoneally for 35 days continuously and adding resveratrol (Res) to further explore the link between deacetylation and hepatotoxicity.

Results

The results revealed that Cr(VI) induced inflammatory response and apoptosis in hepatocytes. Furthermore, Cr(VI) reduced Sirt1 expression and inhibited the deacetylation of Sirt1 to downstream key transcription factors, including nuclear factor erythroid 2-related factor 2 (Nrf2), Forkhead box O3 (FOXO3), and nuclear factor-kappa B (NF-κB). Conversely, when Res was administered as an activator of Sirt1, the deacetylation of Sirt1 was enhanced, and inflammatory response and apoptosis were significantly alleviated.

Conclusion

In summary, this work firstly demonstrates that Cr(VI) induces liver injury in rat by inhibiting the deacetylation of Sirt1, which is of positive significance for protecting the natural environment and animal health from chronic Cr poisoning.

Role of Circular RNA in Kidney-Related Diseases

The kidney is vital in maintaining fluid, electrolyte, and acid–base balance. Kidney-related diseases, which are an increasing public health issue, can happen to people of any age and at any time. Circular RNAs (circRNAs) are endogenous RNA that are produced by selective RNA splicing and are involved in progression of various diseases. Studies have shown that various kidney diseases, including renal cell carcinoma, acute kidney injury, and chronic kidney disease, are linked to circRNAs. This review outlines the characteristics and biological functions of circRNAs and discusses specific studies that provide insights into the function and potential of circRNAs for application in the diagnosis and treatment of kidney-related diseases.

Post-translational modifications of EZH2 in cancer

Enhancer of zeste homolog 2 (EZH2), as a main component of Polycomb Repressive Complex 2, catalyzes histone H3K27me3 to silence its target gene expression. EZH2 upregulation results in cancer development and poor prognosis of cancer patients. Post-translational modifications (PTMs) are important biological events in cancer progression. PTMs regulate protein conformation and diversity functions. Recently, mounting studies have demonstrated that EZH2 stability, histone methyltransferase activity, localization, and binding partners can be regulated by PTMs, including phosphorylation, O-GlcNAcylation, acetylation, methylation and ubiquitination. However, the detailed molecular mechanisms of the EZH2-PTMs and whether other types of PTMs occur in EZH2 remain largely unclear. This review presents an overview of different roles of EZH2 modification and EZH2-PTMs crosstalk during tumorigenesis and cancer metastasis. We also discussed the therapeutic potential of targeting EZH2 modifications for cancer therapy.

Recent advancements in understanding the role of epigenetics in the auditory system

Sensorineural deafness in mammals is most commonly caused by damage to inner ear sensory epithelia, or hair cells, and can be attributed to genetic and environmental causes. After undergoing trauma, many non-mammalian organisms, including reptiles, birds, and zebrafish, are capable of regenerating damaged hair cells. Mammals, however, are not capable of regenerating damaged inner ear sensory epithelia, so that hair cell damage is permanent and can lead to hearing loss. The field of epigenetics, which is the study of various phenotypic changes caused by modification of genetic expression rather than alteration of DNA sequence, has seen numerous developments in uncovering biological mechanisms of gene expression and creating various medical treatments. However, there is a lack of information on the precise contribution of epigenetic modifications in the auditory system, specifically regarding their correlation with development of inner ear (cochlea) and consequent hearing impairment. Current studies have suggested that epigenetic modifications influence differentiation, development, and protection of auditory hair cells in cochlea, and can lead to hair cell degeneration. The objective of this article is to review the existing literature and discuss the advancements made in understanding epigenetic modifications of inner ear sensory epithelial cells. The analysis of the emerging epigenetic mechanisms related to inner ear sensory epithelial cells development, differentiation, protection, and regeneration will pave the way to develop novel therapeutic strategies for hearing loss.

Proximal Tubular Transcription Factors in Acute Kidney Injury: Recent Advances

The proximal tubule (PT) is a major target in acute kidney injury (AKI), leading to profound changes in PT cell biology. Amongst the genes with early and robust changes in expression are many transcription factors (TFs), which themselves account for other transcriptomic changes. Potentially important TFs are being revealed in large sequencing datasets; however, to understand whether these TFs account for adaptive or maladaptive changes requires further mechanistic studies, which may reveal novel therapeutic targets. This mini review will highlight the identification and biology of 3 novel TFs in AKI: Sox9, Foxm1, and Foxo3.

The Roles of Sirtuin Family Proteins in Cancer Progression

Sirtuin family members are characterized by either mono-ADP-ribosyltransferase or deacylase activity and are linked to various cancer-related biological pathways as regulators of transcriptional progression. Sirtuins play fundamental roles in carcinogenesis and maintenance of the malignant phenotype, mainly participating in cancer cell viability, apoptosis, metastasis, and tumorigenesis. Although sirtuin family members have a high degree of homology, they may play different roles in various kinds of cancer. This review highlights their fundamental roles in tumorigenesis and cancer development and provides a critical discussion of their dual roles in cancer, namely, as tumor promoters or tumor suppressors.

c-Myc promotes tubular cell apoptosis in ischemia-reperfusion-induced renal injury by negatively regulating c-FLIP and enhancing FasL/Fas-mediated apoptosis pathway

c-Myc plays an important role in cell proliferation, differentiation, and cell apoptosis. FasL/Fas pathway is a key regulator of cell apoptosis. This study was aimed to investigate the effects of c-Myc on the FasL/Fas pathway in ischemia-reperfusion (I/R)-induced renal injury. Rats were objected to bilateral renal ischemia for 60 min and reperfused for 24 or 48 h. NRK-52E cells were treated with hypoxia-reoxygenation (H/R) or FasL. Immunohistochemistry was used to identify the distribution of c-Myc. Cell apoptosis was assessed by TUNEL staining. Ad-c-Myc and recombinant pcDAN 3.0 were used to overexpress c-Myc and c-FLIP, respectively. ChIP assay and luciferase assay were used to detect the binding of c-Myc to c-FLIP promoter. In I/R rats, c-Myc was increased significantly and mainly located in renal tubular epithelial cells; meanwhile, c-FLIP was decreased, cleaved caspase-8, cleaved caspase-3 and TUNEL-positive staining cells were increased. Treatment of I/R rats with c-Myc inhibitor 10058-F4 significantly attenuated the decrease in c-FLIP, the increase in cleaved caspase-8, cleaved caspase-3, TUNEL-positive cells, Scr and BUN in I/R rats. In NRK-52E cells, hypoxia and reoxygen induced the increase in c-Myc and decrease in c-FLIP. ChIP and luciferase assay results indicated that c-Myc binds to the promoter region of c-FLIP gene. Overexpression of c-Myc markedly decreased c-FLIP. Overexpression of c-FLIP inhibited the increase in cleaved caspase-8 and caspase-3 induced by FasL. Data indicated that c-Myc is increased in kidneys of I/R rats and negatively regulates the expression of c-FLIP, then enhanced FasL-induced cell apoptosis in I/R stress.

SIRT2 Inhibition Results in Meiotic Arrest, Mitochondrial Dysfunction, and Disturbance of Redox Homeostasis during Bovine Oocyte Maturation

SIRT2, a member of the sirtuin family, has been recently shown to exert important effects on mitosis and/or metabolism. However, its roles in oocyte maturation have not been fully clarified. In this study, SIRT2, located in the cytoplasm and nucleus, was found in abundance in the meiotic stage, and its expression gradually decreased until the blastocyst stage. Treatment with SIRT2 inhibitors resulted in the prevention of oocyte maturation and the formation of poor-quality oocytes. By performing confocal scanning and quantitative analysis, the results showed that SIRT2 inhibition induced prominent defects in spindle/chromosome morphology, and led to the hyperacetylation of α-tubulin and H4K16. In particular, SIRT2 inhibition impeded cytoplasmic maturation by disturbing the normal distribution of cortical granules, endoplasmic reticulum, and mitochondria during oocyte meiosis. Meanwhile, exposure to SirReal2 led to elevated intracellular reactive oxygen species (ROS) accumulation, low ATP production, and reduced mitochondrial membrane potential in oocytes. Further analysis revealed that SIRT2 inhibition modulated mitochondrial biogenesis and dynamics via the downregulation of TFAM and Mfn2, and the upregulation of DRP1. Mechanistically, SIRT2 inhibition blocked the nuclear translocation of FoxO3a by increasing FoxO3a acetylation, thereby downregulating the expression of FoxO3a-dependent antioxidant genes SOD2 and Cat. These results provide insights into the potential mechanisms by which SIRT2-dependent deacetylation activity exerts its effects on oocyte quality.

Chrysin protects against renal ischemia reperfusion induced tubular cell apoptosis and inflammation in mice

Renal ischemia reperfusion (IR) is a major cause of acute kidney injury with no effective treatment. Chrysin is an anti-inflammatory, anti-oxidant and anti-cancer agent. However, the effect of chrysin on renal IR injury remains unknown. In this study, sham operation, IR and IR+chrysin group mice were treated with or without renal IR injury. For renal IR, bilateral renal pedicles were clamped for 30 min and then released for 48 h of reperfusion. Blood and kidney samples were collected for analysis. Results demonstrated that chrysin pretreatment remarkably decreased the levels of serum creatinine and blood urea nitrogen and attenuated morphological abnormalities in renal IR injury. Consistently, tubular cell apoptosis and inflammation were more attenuated in the chrysin pretreatment group compared with the IR group. Chrysin pretreatment decreased the expression of Bax and cleaved caspase-3 and increased the expression of Bcl-2 in renal IR injury. Furthermore, chrysin administration decreased the mRNA and protein levels of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. Furthermore, the IκBα/nuclear factor-κB signaling pathway was more suppressed in the chrysin pretreatment group compared with the IR group. In conclusion, chrysin protects against tubular cell apoptosis and inflammation in renal IR injury.

Vincristine ablation of Sirt2 induces cell apoptosis and mitophagy via Hsp70 acetylation in MDA-MB-231 cells

Cancer cells are continuously challenged by adverse environmental stress and adopt diverse strategies to survive. Hsp70 plays pivotal roles in invasion, migration, drug resistance, and the survival of tumor cells. Hsp70 functions as molecular chaperone to protect tumor cells from stress-induced cell death. Hsp70 acetylation alters its chaperone activity in cell death pathways, but its relevance in the process of cell death and the underlying mechanisms involved are not well understood. In this study, we demonstrated that vincristine induces mitophagy via the disruption of Hsp70 binding with Sirt2, leading to Hsp70 acetylation at K126 and elevated sequestration of Bcl2 by Hsp70 for autophagosome creation. Acetylation at K126 significantly changes the physiological function of Hsp70 compared to acetylation at other sites. It also attenuates the protein folding and renaturation function of Hsp70 by altering the binding co-chaperones. In addition, acetylation at K126 inhibits Hsp70-mediated tumor cell invasion and migration, and the binding of Hsp70 to AIF1 and Apaf1 for promoting mitochondrial-mediated apoptosis. In conclusion, this study describes the molecular mechanism of vincristine induction of cell apoptosis and mitophagy via ablation of Sirt2 induced Hsp70 acetylation at K126 in MDA-MB-231 cells.

SIRT2 regulates oxidative stress-induced cell death through deacetylation of c-Jun NH2-terminal kinase

c-Jun NH₂-terminal kinases (JNKs) are responsive to stress stimuli and their activation regulate key cellular functions, including cell survival, growth, differentiation and aging. Previous studies demonstrate that activation of JNK requires dual phosphorylation by the mitogen-activated protein kinase kinases. However, other post-translational mechanisms involved in regulating the activity of JNK have been poorly understood. In this work, we studied the functional significance of reversible lysine acetylation in regulating the kinase activity of JNK. We found that the acetyl transferase p300 binds to, acetylates and inhibits kinase activity of JNK. Using tandem mass spectrometry, molecular modelling and molecular dynamics simulations, we found that acetylation of JNK at Lys153 would hinder the stable interactions of the negatively charged phosphates and prevent the adenosine binding to JNK. Our screening for the deacetylases found SIRT2 as a deacetylase for JNK. Mechanistically, SIRT2-dependent deacetylation enhances ATP binding and enzymatic activity of JNK towards c-Jun. Furthermore, SIRT2-mediated deacetylation favours the phosphorylation of JNK by MKK4, an upstream kinase. Our results indicate that deacetylation of JNK by SIRT2 promotes oxidative stress-induced cell death. Conversely, SIRT2 inhibition attenuates H₂O₂-mediated cell death in HeLa cells. SIRT2-deficient (SIRT2-KO) mice exhibit increased acetylation of JNK, which is associated with markedly reduced catalytic activity of JNK in the liver. Interestingly, SIRT2-KO mice were resistant to acetaminophen-induced liver toxicity. SIRT2-KO mice show lower cell death, minimal degenerative changes, improved liver function and survival following acetaminophen treatment. Overall, our work identifies SIRT2-mediated deacetylation of JNK as a critical regulator of cell survival during oxidative stress.

Extracellular vesicles from human-induced pluripotent stem cell-derived mesenchymal stromal cells (hiPSC-MSCs) protect against renal ischemia/reperfusion injury via delivering specificity protein (SP1) and transcriptional activating of sphingosine kinase 1 and inhibiting necroptosis

Renal ischemia-reperfusion is a main cause of acute kidney injury (AKI), which is associated with high mortality. Here we show that extracellular vesicles (EVs) secreted from hiPSC-MSCs play a critical role in protection against renal I/R injury. hiPSC-MSCs-EVs can fuse with renal cells and deliver SP1 into target cells, subsequently active SK1 expression and increase S1P formation. Chromatin immunoprecipitation (ChIP) analyses and luciferase assay were used to confirm SP1 binds directly to the SK1 promoter region and promote promoter activity. Moreover, SP1 inhibition (MIT) or SK1 inhibition (SKI-II) completely abolished the renal protective effect of hiPSC-MSCs-EVs in rat I/R injury mode. However, pre-treatment of necroptosis inhibitor Nec-1 showed no difference with the administration of hiPSC-MSCs-EVs only. We then generated an SP1 knockout hiPSC-MSC cell line by CRISPR/Cas9 system and found that SP1 knockout failed to show the protective effect of hiPSC-MSCs-EVs unless restoring the level of SP1 by Ad-SP1 in vitro and in vivo. In conclusion, this study describes an anti-necroptosis effect of hiPSC-MSCs-EVs against renal I/R injury via delivering SP1 into target renal cells and intracellular activating the expression of SK1 and the generation of S1P. These findings suggest a novel mechanism for renal protection against I/R injury, and indicate a potential therapeutic approach for a variety of renal diseases and renal transplantation.

Tisp40 deficiency attenuates renal ischemia reperfusion injury induced apoptosis of tubular epithelial cells

Renal ischemia reperfusion (IR) is a major cause of acute kidney injury (AKI) and no effective treatments have been established. Tisp40 is a transcription factor of the CREB/ATF family and involves in cell apoptosis, proliferation and differentiation, but its role in renal IR remains unknown. Here, we investigated the role of Tisp40 in renal IR injury. In vivo, Tisp40 knockout (KO) and wild-type (WT) mice were subjected to thirty minutes of bilateral renal ischemia and 48h reperfusion, the blood and kidneys were harvested for analysis. In vitro, Tisp40 overexpression and vector cells were subjected to hypoxia/reoxygenation (HR), the apoptosis rate and the expressions of related proteins were measured. Following IR, the expressions of Tisp40 protein, serum creatinine (sCr), blood urea nitrogen (BUN) and apoptosis of tubular cells were significantly increased in WT mice. However, Tisp40 deficiency significantly attenuated the increase of sCr, BUN and apoptosis of tubular cells. Following HR, apoptosis of tubular cells was increased in Tisp40 overexpression cells compared with vector cells. Mechanistically, Tisp40 promoted the expressions of C/EBP homologous protein (CHOP), Bax and Cleaved caspase3 and suppressed the expression of Bcl-2 in renal IR injury. In conclusion, Tisp40 aggravates tubular cells apoptosis in renal IR injury.

Histone deacetylases in hearing loss: Current perspectives for therapy

Hearing loss is one of the most frequent health issues in industrialized countries. The pathogenesis and molecular mechanisms of hearing loss are still unclear. Histone deacetylases (HDACs) are emerging as key enzymes in many physiological processes, including chromatin remodeling, regulation of transcription, DNA repair, metabolism, genome stability and protein secretion. Recent studies indicated that HDACs are associated with the development and progression of hearing loss. Dysfunction of HDACs could promote the oxidative stress and aging in the inner ear. In light of considering the current stagnation in the development of therapeutic options, the need for new strategies in the treatment of hearing loss has never been so pressing. In this review, we will summarize the reported literatures for HDACs in hearing loss and discuss how HDAC family members show different performances for the possibility of process of diseases development. The possibility of pharmacological intervention on hearing loss opens a novel path in the treatment of hearing loss.