Upregulation of Mitochondrial Sirt3 and Alleviation of the Inflammatory Phenotype in Macrophages by Estrogen.

BACKGROUND: Aging and comorbidities like type 2 diabetes and obesity contribute to the development of chronic systemic inflammation, which impacts the development of heart failure and vascular disease. Increasing evidence suggests a role of pro-inflammatory M1 macrophages in chronic inflammation. A shift of metabolism from mitochondrial oxidation to glycolysis is essential for the activation of the pro-inflammatory M1 phenotype. Thus, reprogramming the macrophage metabolism may alleviate the pro-inflammatory phenotype and protect against cardiovascular diseases. In the present study, we hypothesized that the activation of estrogen receptors leads to the elevation of the mitochondrial deacetylase Sirt3, which supports mitochondrial function and mitigates the pro-inflammatory phenotype in macrophages. MATERIALS AND METHODS: Experiments were performed using the mouse macrophage cell line RAW264.7, as well as primary male or female murine bone marrow macrophages (BMMs). Macrophages were treated for 24 h with estradiol (E2) or vehicle (dextrin). The effect of E2 on Sirt3 expression was investigated in pro-inflammatory M1, anti-inflammatory/immunoregulatory M2, and naïve M0 macrophages. Mitochondrial respiration was measured by Seahorse assay, and protein expression and acetylation were determined by western blotting. RESULTS: E2 treatment upregulated mitochondrial Sirt3, reduced mitochondrial protein acetylation, and increased basal mitochondrial respiration in naïve RAW264.7 macrophages. Similar effects on Sirt3 expression and mitochondrial protein acetylation were observed in primary female but not in male murine BMMs. Although E2 upregulated Sirt3 in naïve M0, pro-inflammatory M1, and anti-inflammatory/immunoregulatory M2 macrophages, it reduced superoxide dismutase 2 acetylation and suppressed mitochondrial reactive oxygen species formation only in pro-inflammatory M1 macrophages. E2 alleviated the pro-inflammatory phenotype in M1 RAW264.7 cells. CONCLUSIONS: The study suggests that E2 treatment upregulates Sirt3 expression in macrophages. In primary BMMs, female-specific Sirt3 upregulation was observed. The Sirt3 upregulation was accompanied by mitochondrial protein deacetylation and the alleviation of the oxidative and pro-inflammatory phenotype in M1 macrophages. Thus, the E2-Sirt3 axis might be used in a therapeutic strategy to fight chronic systemic inflammation and prevent the development of inflammation-linked diseases.

The epigenetic changes are affected by sex and valproic acid treatment in a rat model of post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) presents distinct sex-specific differences in both symptom expression and treatment outcomes, with the underlying biological mechanisms still remain unclear. Epigenetic modifications, particularly histone acetylation, have been increasingly recognized as critical factors in the pathophysiology of PTSD. Valproic acid (VPA), a potent histone deacetylase (HDAC) inhibitor, has shown promise in modulating epigenetic responses and improving therapeutic outcomes is PTSD, though its effect may differ between sexes. This study aimed to explore the sex-specific epigenetic changes in response to trauma and the impact of VPA treatment in a rat model of PTSD induced by predator scent stress. Sprague-Dawley rats of both sexes were randomly assigned to stressed and non-stressed groups and treated with either VPA (100 mg/kg) or vehicle. Anxiety levels were assessed using the elevated plus maze, followed by analysis of histone H3 and H4 acetylation, HDAC activity, and c-fos expression in the hippocampus. Our findings revealed that traumatic stress led to increased freezing time and anxiety levels, with more pronounced effects observed in females. Additionally, we have identified sex-specific differences in hippocampal epigenetic modifications; stressed females exhibited higher H3 acetylation, and VPA-treated stressed males showed increased H4 acetylation. These results highlight the importance of considering sex differences in the epigenetic mechanism underlying PTSD and suggest that personalized therapeutic approaches may be necessary to address these complexities.

Systematic Analysis of the BrHAT Gene Family and Physiological Characteristics of Brassica rapa L. Treated with Histone Acetylase and Deacetylase Inhibitors under Low Temperature.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Melatonin Prevents Thioacetamide-Induced Gut Leakiness and Liver Fibrosis Through the Gut-Liver Axis via Modulating Sirt1-Related Deacetylation of Gut Junctional Complex and Hepatic Proteins.

Intestinal barrier dysfunction with high serum endotoxin is common in patients with liver fibrosis, but the mechanisms underlying liver fibrosis remain unclear. Melatonin is a well-recognized antioxidant and an anti-inflammatory agent that benefits multiple organs. However, the beneficial effects of melatonin on gut leakiness-associated liver fibrosis have not been systemically studied. Here, we investigated the protective mechanisms of melatonin against thioacetamide (TAA)-induced gut barrier dysfunction and hepatic fibrosis by focusing on posttranslational protein modifications through the gut-liver axis. Our results showed that gut leakiness markers, including decreased gut tight/adherens junction proteins (TJ/AJs) with increased intestinal deformation, apoptosis, and serum endotoxin, were observed early at 1 week after TAA exposure. Liver injury, apoptosis, and fibrosis were prominent at 2 and 4 weeks. Mechanistically, we found that gut TJ/AJs were hyper-acetylated, followed by ubiquitin-dependent proteolysis, leading to their degradation and gut leakiness. Gut dysbiosis, hepatic protein hyper-acetylation, and SIRT1 downregulation were also observed. Consistently, intestinal Sirt1 deficiency greatly enhanced protein hyper-acetylation, gut leakiness, endotoxemia, and liver fibrosis. Pretreatment with melatonin prevented or improved all these changes in both the gut and liver. Furthermore, melatonin blunted protein acetylation and injury in TAA-exposed T84 human intestinal and AML12 mouse liver cells. Overall, this study demonstrated novel mechanisms by which melatonin prevents gut leakiness and liver fibrosis through the gut-liver axis by attenuating the acetylation of intestinal and hepatic proteins. Thus, melatonin consumption can become a potentially safe supplement for liver fibrosis patients by preventing protein hyper-acetylation and gut leakiness.

Fluoride Alters Gene Expression via Histone H3K27 Acetylation in Ameloblast-like LS8 Cells.

Excessive fluoride ingestion during tooth development can cause dental fluorosis. Previously, we reported that fluoride activates histone acetyltransferase (HAT) to acetylate p53, promoting fluoride toxicity in mouse ameloblast-like LS8 cells. However, the roles of HAT and histone acetylation status in fluoride-mediated gene expression remain unidentified. Here, we demonstrate that fluoride-mediated histone modification causes gene expression alterations in LS8 cells. LS8 cells were treated with or without fluoride followed by ChIP-Seq analysis of H3K27ac. Genes were identified by differential H3K27ac peaks within ±1 kb from transcription start sites. The levels of mRNA of identified genes were assessed using rea-time PCR (qPCR). Fluoride increased H3K27ac peaks associated with Bax, p21, and Mdm2 genes and upregulated their mRNA levels. Fluoride decreased H3K27ac peaks and p53, Bad, and Bcl2 had suppressed transcription. HAT inhibitors (Anacardic acid or MG149) suppressed fluoride-induced mRNA of p21 and Mdm2, while fluoride and the histone deacetylase (HDAC) inhibitor sodium butyrate increased Bad and Bcl2 expression above that of fluoride treatment alone. To our knowledge, this is the first study that demonstrates epigenetic regulation via fluoride treatment via H3 acetylation. Further investigation is required to elucidate epigenetic mechanisms of fluoride toxicity in enamel development.

Nuclear ATP-citrate lyase regulates chromatin-dependent activation and maintenance of the myofibroblast gene program.

Differentiation of cardiac fibroblasts to myofibroblasts is necessary for matrix remodeling and fibrosis in heart failure. We previously reported that mitochondrial calcium signaling drives α-ketoglutarate-dependent histone demethylation, promoting myofibroblast formation. Here we investigate the role of ATP-citrate lyase (ACLY), a key enzyme for acetyl-CoA biosynthesis, in histone acetylation regulating myofibroblast fate and persistence in cardiac fibrosis. We show that inactivation of ACLY prevents myofibroblast differentiation and reverses myofibroblasts towards quiescence. Genetic deletion of Acly in post-activated myofibroblasts prevents fibrosis and preserves cardiac function in pressure-overload heart failure. TGFß stimulation enhances ACLY nuclear localization and ACLY-SMAD2/3 interaction, and increases H3K27ac at fibrotic gene loci. Pharmacological inhibition of ACLY or forced nuclear expression of a dominant-negative ACLY mutant prevents myofibroblast formation and H3K27ac. Our data indicate that nuclear ACLY activity is necessary for myofibroblast differentiation and persistence by maintaining histone acetylation at TGFß-induced myofibroblast genes. These findings provide targets to prevent and reverse pathological fibrosis.

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2.

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

HDAC6 inhibition disrupts HDAC6-P300 interaction reshaping the cancer chromatin landscape.

BACKGROUND: Histone deacetylases (HDACs) are crucial regulators of gene expression, DNA synthesis, and cellular processes, making them essential targets in cancer research. HDAC6, specifically, influences protein stability and chromatin dynamics. Despite HDAC6's potential therapeutic value, its exact role in gene regulation and chromatin remodeling needs further clarification. This study examines how HDAC6 inactivation influences lysine acetyltransferase P300 stabilization and subsequent effects on chromatin structure and function in cancer cells. METHODS AND RESULTS: We employed the HDAC6 inhibitor ITF3756, siRNA, or CRISPR/Cas9 gene editing to inactivate HDAC6 in different epigenomic backgrounds. Constantly, this inactivation led to significant changes in chromatin accessibility, particularly increased acetylation of histone H3 lysines 9, 14, and 27 (ATAC-seq and H3K27Ac ChIP-seq analysis). Transcriptomics, proteomics, and gene ontology analysis revealed gene changes in cell proliferation, adhesion, migration, and apoptosis. Significantly, HDAC6 inactivation altered P300 ubiquitination, stabilizing P300 and leading to downregulating genes critical for cancer cell survival. CONCLUSIONS: Our study highlights the substantial impact of HDAC6 inactivation on the chromatin landscape of cancer cells and suggests a role for P300 in contributing to the anticancer effects. The stabilization of P300 with HDAC6 inhibition proposes a potential shift in therapeutic focus from HDAC6 itself to its interaction with P300. This finding opens new avenues for developing targeted cancer therapies, improving our understanding of epigenetic mechanisms in cancer cells.

Acetylation of Steroidogenic Acute Regulatory Protein Sensitizes 17ß-Estradiol Regulation in Hormone-Sensitive Breast Cancer Cells.

An imbalance in estrogen signaling is a critical event in breast tumorigenesis. The majority of breast cancers (BCs) are hormone-sensitive; they majorly express the estrogen receptor (ER+) and are activated by 17ß-estradiol (E2). The steroidogenic acute regulatory protein (StAR) mediates the rate-limiting step in steroid biosynthesis. The dysregulation of the epigenetic machinery, modulating E2 levels, is a primary occurrence for promoting breast tumorigenesis. StAR expression, concomitant with E2 synthesis, was reported to be aberrantly high in human and mouse hormone-dependent BC cells compared with their non-cancerous counterparts. However, the mechanism of action of StAR remains poorly understood. We discovered StAR as an acetylated protein and have identified a number of lysine (K) residues that are putatively acetylated in malignant and non-malignant breast cells, using LC-MS/MS (liquid chromatography-tandem mass spectrometry), suggesting they differently influence E2 synthesis in mammary tissue. The treatment of hormone-sensitive MCF7 cells with a variety of histone deacetylase inhibitors (HDACIs), at therapeutically and clinically relevant doses, identified a few additional StAR acetylated lysine residues. Among a total of fourteen StAR acetylomes undergoing acetylation and deacetylation, K111 and K253 were frequently recognized either endogenously or in response to HDACIs. Site-directed mutagenesis studies of these two StAR acetylomes, pertaining to K111Q and K253Q acetylation mimetic states, resulted in increases in E2 levels in ER+ MCF7 and triple negative MB-231 BC cells, compared with their values seen with human StAR. Conversely, these cells carrying K111R and K253R deacetylation mutants diminished E2 biosynthesis. These findings provide novel and mechanistic insights into intra-tumoral E2 regulation by elucidating the functional importance of this uncovered StAR post-translational modification (PTM), involving acetylation and deacetylation events, underscoring the potential of StAR as a therapeutic target for hormone-sensitive BC.

Sodium Acetate Enhances Neutrophil Extracellular Trap Formation via Histone Acetylation Pathway in Neutrophil-like HL-60 Cells.

Neutrophil extracellular trap formation has been identified as a new cell death mediator, termed NETosis, which is distinct from apoptosis and necrosis. NETs capture foreign substances, such as bacteria, by releasing DNA into the extracellular environment, and have been associated with inflammatory diseases and altered immune responses. Short-chain fatty acids, such as acetate, are produced by the gut microbiota and reportedly enhance innate immune responses; however, the underlying molecular mechanisms remain unclear. Here, we investigated the effects of sodium acetate, which has the highest SCFA concentration in the blood and gastrointestinal tract, on NETosis by focusing on the mechanisms associated with histone acetylation in neutrophil-like HL-60 cells. Sodium acetate enhanced NETosis, as shown by fluorescence staining with SYTOX green, and the effect was directly proportional to the treatment duration (16-24 h). Moreover, the addition of sodium acetate significantly enhanced the acetylation of Ace-H3, H3K9ace, and H3K14ace. Sodium acetate-induced histone acetylation rapidly decreased upon stimulation with the calcium ionophore A23187, whereas histone citrullination markedly increased. These results demonstrate that sodium acetate induces NETosis via histone acetylation in neutrophil-like HL-60 cells, providing new insights into the therapeutic effects based on the innate immunity-enhancing effect of dietary fiber.

Alcohol- and Low-Iron Induced Changes in Antioxidant and Energy Metabolism Associated with Protein Lys Acetylation.

Understanding the role of iron in ethanol-derived hepatic stress could help elucidate the efficacy of dietary or clinical interventions designed to minimize liver damage from chronic alcohol consumption. We hypothesized that normal levels of iron are involved in ethanol-derived liver damage and reduced dietary iron intake would lower the damage caused by ethanol. We used a pair-fed mouse model utilizing basal Lieber-DeCarli liquid diets for 22 weeks to test this hypothesis. In our mouse model, chronic ethanol exposure led to mild hepatic stress possibly characteristic of early-stage alcoholic liver disease, seen as increases in liver-to-body weight ratios. Dietary iron restriction caused a slight decrease in non-heme iron and ferritin (FeRL) expression while it increased transferrin receptor 1 (TfR1) expression without changing ferroportin 1 (FPN1) expression. It also elevated protein lysine acetylation to a more significant level than in ethanol-fed mice under normal dietary iron conditions. Interestingly, iron restriction led to an additional reduction in nicotinamide adenine dinucleotide (NAD+) and NADH levels. Consistent with this observation, the major mitochondrial NAD+-dependent deacetylase, NAD-dependent deacetylase sirtuin-3 (SIRT3), expression was significantly reduced causing increased protein lysine acetylation in ethanol-fed mice at normal and low-iron conditions. In addition, the detection of superoxide dismutase 1 and 2 levels (SOD1 and SOD2) and oxidative phosphorylation (OXPHOS) complex activities allowed us to evaluate the changes in antioxidant and energy metabolism regulated by ethanol consumption at normal and low-iron conditions. We observed that the ethanol-fed mice had mild liver damage associated with reduced energy and antioxidant metabolism. On the other hand, iron restriction may exacerbate certain activities of ethanol further, such as increased protein lysine acetylation and reduced antioxidant metabolism. This metabolic change may prove a barrier to the effectiveness of dietary reduction of iron intake as a preventative measure in chronic alcohol consumption.

Comparative Analysis of Acetylated Flavonoids' Chemopreventive Effects in Different Cancer Cell Lines.

Flavonoids, a class of natural compounds with anticancer activity, exhibit varying biological activities and potencies based on their structural differences. Acylation, including acetylation of flavonoids, generally increases their structural diversity, which is closely related to the diversity of bioactivity within this group of compounds. However, it remains largely unknown how acetylation affects the bioactivity of many flavonoids. Based on our previous findings that O-acetylation enhances quercetin's bioactivity against various cancer cells, we synthesized 12 acetylated flavonoids, including seven novel compounds, to investigate their anticancer activities in the MDA-MB-231, HCT-116, and HepG2 cell lines. Our results showed that acetylation notably enhanced the cell proliferation inhibitory effect of quercetin and kaempferol across all cancer cell lines tested. Interestingly, while the 5,7,4'-O-triacetate apigenin (3Ac-A) did not show an enhanced the effect of inhibition of cell proliferation through acetylation, it exhibited significantly strong anti-migration activity in MDA-MB-231 cells. In contrast, the 7,4'-O-diacetate apigenin (2Ac-Q), which lacks acetylation at the 5-position hydroxy group, showed enhanced cell proliferation inhibitory effect but had weaker anti-migration effects compared to 3Ac-A. These results indicated that acetylated flavonoids, especially quercetin, kaempferol, and apigenin derivatives, are promising for anticancer applications, with 3Ac-A potentially having unique anti-migration pathways independent of apoptosis induction. This study highlights the potential application of flavonoids in novel chemopreventive strategies for their anti-cancer activity.

Paricalcitol attenuates oxidative stress and inflammatory response in the liver of NAFLD rats by regulating FOXO3a and NFκB acetylation.

The lack of therapeutics along with complex pathophysiology made non-alcoholic fatty liver disease (NAFLD) a research hotspot. Studies showed that the deficiency of Vitamin D plays a vital role in NAFLD pathogenesis. While several research studies focused on vitamin D supplementation in NAFLD, there is still a need to understand the regulatory mechanism of direct vitamin D receptor activation in NAFLD. In the present study, we explored the role of direct Vitamin D receptor activation using paricalcitol in choline-deficient high-fat diet-induced NAFLD rat liver and its modulation on protein acetylation. Our results showed that paricalcitol administration significantly reduced the fat accumulation in HepG2 cells and the liver of NAFLD rats. Paricalcitol attenuated the elevated serum level of alanine transaminase, aspartate transaminase, insulin, low-density lipoprotein, triglyceride, and increased high-density lipoprotein in NAFLD rats. Paricalcitol significantly decreased the increased total protein acetylation by enhancing the SIRT1 and SIRT3 expression in NAFLD liver. Further, the study revealed that paricalcitol reduced the acetylation of NFκB and FOXO3a in NAFLD liver along with a decrease in the mRNA expression of IL1ß, NFκB, TNFα, and increased catalase and MnSOD. Moreover, total antioxidant activity, glutathione, and catalase were also elevated, whereas lipid peroxidation, myeloperoxidase, and reactive oxygen species levels were significantly decreased in the liver of NAFLD after paricalcitol administration. The study concludes that the downregulation of SIRT1 and SIRT3 in NAFLD liver was associated with an increased acetylated NFκB and FOXO3a. Paricalcitol effectively reversed hepatic inflammation and oxidative stress in NAFLD rats through transcriptional regulation of NFκB and FOXO3a, respectively, by inhibiting their acetylation.

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.

Epigenetic-based differentiation therapy for Acute Myeloid Leukemia.

Despite the development of novel therapies for acute myeloid leukemia, outcomes remain poor for most patients, and therapeutic improvements are an urgent unmet need. Although treatment regimens promoting differentiation have succeeded in the treatment of acute promyelocytic leukemia, their role in other acute myeloid leukemia subtypes needs to be explored. Here we identify and characterize two lysine deacetylase inhibitors, CM-444 and CM-1758, exhibiting the capacity to promote myeloid differentiation in all acute myeloid leukemia subtypes at low non-cytotoxic doses, unlike other commercial histone deacetylase inhibitors. Analyzing the acetylome after CM-444 and CM-1758 treatment reveals modulation of non-histone proteins involved in the enhancer-promoter chromatin regulatory complex, including bromodomain proteins. This acetylation is essential for enhancing the expression of key transcription factors directly involved in the differentiation therapy induced by CM-444/CM-1758 in acute myeloid leukemia. In summary, these compounds may represent effective differentiation-based therapeutic agents across acute myeloid leukemia subtypes with a potential mechanism for the treatment of acute myeloid leukemia.

Spermidine supplementation in honey bees: Autophagy and epigenetic modifications.

Polyamines (PAs), including putrescine (Put), spermidine (Spd), and spermine (Spm), are essential polycations with wide-ranging roles in cellular functions. PA levels decline with age, making exogenous PA supplementation, particularly Spd, an intriguing prospect. Previous research in honey bees demonstrated that millimolar Spd added to their diet increased lifespan and reinforced oxidative resilience. The present study is aimed to assess the anti-aging effects of spermidine supplementation at concentrations of 0.1 and 1 mM in honey bees, focusing on autophagy and associated epigenetic changes. Results showed a more pronounced effect at the lower Spd concentration, primarily in the abdomen. Spd induced site-specific histone 3 hypoacetylation at sites K18 and 27, hyperacetylation at K9, with no change at K14 in the entire body. Additionally, autophagy-related genes (ATG3, 5, 9, 13) and genes associated with epigenetic changes (HDAC1, HDAC3, SIRT1, KAT2A, KAT6B, P300, DNMT1A, DNMT1B) were upregulated in the abdomens of honey bees. In conclusion, our findings highlight profound epigenetic changes and autophagy promotion due to spermidine supplementation, contributing to increased honey bee longevity. Further research is needed to fully understand the precise mechanisms and the interplay between epigenetic alterations and autophagy in honey bees, underscoring the significance of autophagy as a geroprotective mechanism.

SAHA/5-AZA Enhances Acetylation and Degradation of mutp53, Upregulates p21 and Downregulates c-Myc and BRCA-1 in Pancreatic Cancer Cells.

Epigenetic changes are common in cancer and include aberrant DNA methylation and histone modifications, including both acetylation or methylation. DNA methylation in the promoter regions and histone deacetylation are usually accompanied by gene silencing, and may lead to the suppression of tumor suppressors in cancer cells. An interaction between epigenetic pathways has been reported that could be exploited to more efficiently target aggressive cancer cells, particularly those against which current treatments usually fail, such as pancreatic cancer. In this study, we explored the possibility to combine the DNA demethylating agent 5-AZA with HDAC inhibitor SAHA to treat pancreatic cancer cell lines, focusing on the acetylation of mutp53 and the consequences on its stability, as well as on the interaction of this protein with c-myc and BRCA-1, key molecules in cancer survival. The results obtained suggest that SAHA/5-AZA combination was more effective than single treatments to promote the degradation of mutp53, to upregulate p21 and downregulate c-Myc and BRCA-1, thus increasing DNA damage and cytotoxicity in pancreatic cancer cells.

Inhibition of HDAC activity directly reprograms murine embryonic stem cells to trophoblast stem cells.

Embryonic stem cells (ESCs) can differentiate into all cell types of the embryonic germ layers. ESCs can also generate totipotent 2C-like cells and trophectodermal cells. However, these latter transitions occur at low frequency due to epigenetic barriers, the nature of which is not fully understood. Here, we show that treating mouse ESCs with sodium butyrate (NaB) increases the population of 2C-like cells and enables direct reprogramming of ESCs into trophoblast stem cells (TSCs) without a transition through a 2C-like state. Mechanistically, NaB inhibits histone deacetylase activities in the LSD1-HDAC1/2 corepressor complex. This increases acetylation levels in the regulatory regions of both 2C- and TSC-specific genes, promoting their expression. In addition, NaB-treated cells acquire the capacity to generate blastocyst-like structures that can develop beyond the implantation stage in vitro and form deciduae in vivo. These results identify how epigenetics restrict the totipotent and trophectoderm fate in mouse ESCs.

Regulation of STAT1 Signaling in Human Pancreatic ß-Cells by the Lysine Deacetylase HDAC6: A New Therapeutic Opportunity in Type 1 Diabetes?

Type 1 diabetes arises from the selective destruction of pancreatic ß-cells by autoimmune mechanisms, and intracellular pathways driven by Janus kinase (JAK)-mediated phosphorylation of STAT isoforms (especially STAT1 and STAT2) are implicated as mediators of ß-cell demise. Despite this, the molecular mechanisms that regulate JAK-STAT signaling in ß-cells during the autoimmune attack remain only partially disclosed, and the factors acting to antagonize proinflammatory STAT1 signaling are uncertain. We have recently implicated signal regulatory protein α (SIRPα) in promoting ß-cell viability in the face of ongoing islet autoimmunity and have now revealed that this protein controls the availability of a cytosolic lysine deacetylase, HDAC6, whose activity regulates the phosphorylation and activation of STAT1. We provide evidence that STAT1 serves as a substrate for HDAC6 in ß-cells and that sequestration of HDAC6 by SIRPα in response to anti-inflammatory cytokines (e.g., IL-13) leads to increased STAT1 acetylation. This then impairs the ability of STAT1 to promote gene transcription in response to proinflammatory cytokines, including interferon-γ. We further found that SIRPα is lost from the ß-cells of subjects with recent-onset type 1 diabetes under conditions when HDAC6 is retained and STAT1 levels are increased. On this basis, we report a previously unrecognized role for cytokine-induced regulation of STAT1 acetylation in the control of ß-cell viability and propose that targeted inhibition of HDAC6 activity may represent a novel therapeutic modality to promote ß-cell viability in the face of active islet autoimmunity.

Pomiferin targeting SLC9A9 based on histone acetylation modification pattern is a potential therapeutical option for gastric cancer with high malignancy.

Changes in histone acetylation status are associated with gastric cancer (GC) progression. Pomiferin is a natural flavonoid, however, the specific role of pomiferin in the treatment of GC is still unclear, and its targets are not well clarified. In this work, the prognostic genes related with histone acetylation in GC were screened by univariate Cox analysis. Next, a risk model of was constructed using least absolute shrinkage and selection operator-Cox regression analyses, and multivariate Cox analysis was used for identifying the independent risk factor. Molecular docking was performed using AutoDock Vina to validate the interaction between solute carrier family 9 member A9 (SLC9A9) and pomiferin. In vitro and in vivo models were applied to investigate the tumor-suppressive role of pomiferin against GC. The inhibitory effects of pomiferin on EGFR/PI3K/AKT signaling were valdiated by Western blotting, immunofluorescence staining and qPCR. Here, a prognostic risk model based on histone acetylation regulators was established, and SLC9A9 was identified as a risk factor associated with histone acetylation status in GC. SLC9A9 expression was associated with abnormal immune microenvironment of tumor. Pomiferin had a high binding affinity with SLC9A9, and both pomiferin treatment and depletion of SLC9A9 repressed the malignant phenotypes of GC cells. Mechanistically, pomiferin inactivates EGFR/PI3K/AKT signaling in GC cells. In summary, SLC9A9, as a indicator of abnormal histone acetylation status of GC, functions as an oncogenic factor. Pomiferin binds with SLC9A9 to inactivate EGFR/PI3K/AKT pathway, to block GC progression, suggesting it is a promising drug for the patients with highly malignant GC.