Huanglian-Jiedu decoction promotes adipose thermogenesis in obese mice by suppressing the expression of HDAC3.

ETHNOPHARMACOLOGICAL RELEVANCE: Huanglian Jiedu Decoction (HLJDD) is an ancient formula of traditional Chinese medicine that is commonly utilized in a range of disorders, and it has been shown to have pharmacological effects on glucose and lipid metabolism. However, the specific mechanism of HLJDD for the treatment of obesity and related metabolic disorders remains to be further investigated. AIM OF THE STUDY: It has been thought that encouraging adipose thermogenesis to raise the body's energy expenditure is a useful tactic for improving metabolic abnormalities and losing weight. In this study, we investigated the ability and underlying mechanisms of HLJDD to regulate fat cell thermogenesis to improve energy expenditure in obesity. METHODS: The obese mouse model was established on a high-fat diet for 12 weeks. All mice were divided into NC, HFD, HFD with HLJDD of a low dose (2.25 g/kg/d), and HFD with HLJDD of a high dose (4.5 g/kg/d) groups and kept for 4 weeks. In vitro experiments were conducted to evaluate the effects of 5% and 10% HLJDD-containing serum on differentiated 3T3-L1 cells and HDAC3-knocking-down 3T3-L1 cells. RESULTS: The results showed that HLJDD treatment significantly improved glucose and insulin tolerance and decreased the adipocyte radius of WATs, as well as increased energy consumption in obese mice. Besides, HLJDD treatment dramatically increased the levels of thermogenic genes UCP-1 and PGC-1α while suppressing HDAC3 levels in WATs and 3T3-L1 adipocytes. Importantly, the effects of HLJDD on PGC-1α and UCP-1 were blocked in HDAC3 knockdown adipocytes. CONCLUSIONS: Therefore, these results suggest that HLJDD enhanced adipose thermogenesis and improved energy expenditure by inhibiting HDAC3, thereby increasing UCP-1 and PGC-1α expression. These findings amplified the mechanisms of HLJDD and its potential to treat obesity and related metabolic disorders.

Advances in understanding the roles of plant HAT and HDAC in non-histone protein acetylation and deacetylation.

MAIN CONCLUSION: This review focuses on HATs and HDACs that modify non-histone proteins, summarizes functional mechanisms of non-histone acetylation as well as the roles of HATs and HDACs in rice and Arabidopsis. The growth and development of plants, as well as their responses to biotic and abiotic stresses, are governed by intricate gene and protein regulatory networks, in which epigenetic modifying enzymes play a crucial role. Histone lysine acetylation levels, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), are well-studied in the realm of transcriptional regulation. However, the advent of advanced proteomics has unveiled that non-histone proteins also undergo acetylation, with its underlying mechanisms now being clarified. Indeed, non-histone acetylation influences protein functionality through diverse pathways, such as modulating protein stability, adjusting enzymatic activity, steering subcellular localization, influencing interactions with other post-translational modifications, and managing protein-protein and protein-DNA interactions. This review delves into the recent insights into the functional mechanisms of non-histone acetylation in plants. We also provide a summary of the roles of HATs and HDACs in rice and Arabidopsis, and explore their potential involvement in the regulation of non-histone proteins.

Identification of HDAC10 as a candidate oncogene in clear cell renal carcinoma that facilitates tumor proliferation and metastasis.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC) remains one of the most lethal urological malignancies even though a great number of improvements in diagnosis and management have achieved over the past few decades. Accumulated evidence revealed that histone deacetylases (HDACs) play vital role in cell proliferation, differentiation and apoptosis. Nevertheless, the biological functions of histone deacetylation modification related genes in ccRCC remains poorly understood. METHOD: Bulk transcriptomic data and clinical information of ccRCC patients were obtained from the TCGA database and collected from the Chinese PLA General Hospital. A total of 36 histone deacetylation genes were selected and studied in our research. Univariate cox regression analysis, least absolute shrinkage and selection operator (LASSO) regression, random forest (RF) analysis, and protein-protein interaction (PPI) network analysis were applied to identify key genes affecting the prognosis of ccRCC. The 'oncoPredict' algorithm was utilized for drug-sensitive analysis. Gene Set Enrichment Analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to explore the potential biological function. The ssGSEA algorithm was used for tumor immune microenvironment analysis. The expression levels of HDAC10 were validated by RT-PCR and immunohistochemistry (IHC). 5-ethynyl-2'-deoxyuridine (EdU assay), CCK-8 assay, cell transwell migration and invasion assay and colony formation assay were performed to detect the proliferation and invasion ability of ccRCC cells. A nomogram incorporating HDAC10 and clinicopathological characteristics was established to predict the prognosis of ccRCC patients. RESULT: Two machine learning algorithms and PPI analysis identified four histone deacetylation genes that have a significant association with the prognosis of ccRCC, with HDAC10 being the key gene among them. HDAC10 is highly expressed in ccRCC and its high expression is associated with poor prognosis for ccRCC patients. Pathway enrichment and the experiments of EdU staining, CCK-8 assay, cell transwell migration and invasion assay and colony formation assay demonstrated that HDAC10 mediated the proliferation and metastasis of ccRCC cells and involved in reshaping the tumor microenvironment (TME) of ccRCC. A clinically reliable prognostic predictive model was established by incorporating HDAC10 and other clinicopathological characteristics ( https://nomogramhdac10.shinyapps.io/HDAC10_Nomogram/ ). CONCLUSION: Our study found the increased expression of HDAC10 was closely associated with poor prognosis of ccRCC patients. HDAC10 showed a pro-tumorigenic effect on ccRCC and promote the proliferation and metastasis of ccRCC, which may provide new light on targeted therapy for ccRCC.

Inhibition of HDAC8 mitigates AKI by reducing DNA damage and promoting homologous recombination repair.

Nephrotoxicity is a major side effect of platinum-based antineoplastic drugs, and there is currently no available therapeutic intervention. Our study suggests that targeting histone deacetylase 8 could be a potential treatment for cisplatin-induced acute kidney injury (AKI). In a murine model of AKI induced by cisplatin, the administration of PCI-34051, a selective inhibitor of HDAC8, resulted in significant improvement in renal function and reduction in renal tubular damage and apoptosis. Pharmacological inhibition of HDAC8 also decreased caspase-3 and PARP1 cleavage, attenuated Bax expression and preserved Bcl-2 levels in the injured kidney. In cultured murine renal epithelial cells (mRTECs) exposed to cisplatin, treatment with PCI-34051 or transfection with HDAC8 siRNA reduced apoptotic cell numbers and diminished expression of cleaved caspase-3 and PARP1; conversely, overexpression of HDAC8 intensified these changes. Additionally, PCI-34051 reduced p53 expression levels along with those for p21, p-CDK2 and γ-H2AX while preserving MRE11 expression in the injured kidney. Similarly, pharmacological and genetic inhibition of HDAC8 reduced γ-H2AX and enhanced MRE11 expression; conversely, HDAC8 overexpression exacerbated these changes in mRTECs exposed to cisplatin. These results support that HDAC8 inhibition attenuates cisplatin-induced AKI through a mechanism associated with reducing DNA damage and promoting its repair.

MTA2 knockdown suppresses human osteosarcoma metastasis by inhibiting uPA expression.

The relationship between metastasis-associated protein 2 (MTA2) overexpression and tumor growth and metastasis has been extensively studied in a variety of tumor cells but not in human osteosarcoma cells. This study aims to elucidate the clinical significance, underlying molecular mechanisms, and biological functions of MTA2 in human osteosarcoma in vitro and in vivo. Our results show that MTA2 was elevated in osteosarcoma cell lines and osteosarcoma tissues and was associated with tumor stage and overall survival of osteosarcoma patients. Knockdown of MTA2 inhibited osteosarcoma cell migration and invasion by reducing the expression of urokinase-type plasminogen activator (uPA). Bioinformatic analysis demonstrated that high levels of uPA in human osteosarcoma tissues correlated positively with MTA2 expression. Furthermore, treatment with recombinant human uPA (Rh-uPA) caused significant restoration of OS cell migration and invasion in MTA2 knockdown osteosarcoma cells. We found that ERK1/2 depletion increased the expression of uPA, facilitating osteosarcoma cell migration and invasion. Finally, MTA2 depletion significantly reduced tumor metastasis and the formation of lung nodules in vivo. Overall, our study suggests that MTA2 knockdown suppresses osteosarcoma cell metastasis by decreasing uPA expression via ERK signaling. This finding provides new insight into potential treatment strategies against osteosarcoma metastasis by targeting MTA2.

A novel dual-epigenetic inhibitor enhances recombinant monoclonal antibody expression in CHO cells.

Epigenetic regulation plays a central role in the regulation of a number of cellular processes such as proliferation, differentiation, cell cycle, and apoptosis. In particular, small molecule epigenetic modulators are key elements that can effectively influence gene expression by precisely regulating the epigenetic state of cells. To identify useful small-molecule regulators that enhance the expression of recombinant proteins in Chinese hamster ovary (CHO) cells, we examined a novel dual-HDAC/LSD1 inhibitor I-4 as a supplement for recombinant CHO cells. Treatment with 2 µM I-4 was most effective in increasing monoclonal antibody production. Despite cell cycle arrest at the G1/G0 phase, which inhibits cell growth, the addition of the inhibitor at 2 µM to monoclonal antibody-expressing CHO cell cultures resulted in a 1.94-fold increase in the maximal monoclonal antibody titer and a 2.43-fold increase in specific monoclonal antibody production. In addition, I-4 significantly increased the messenger RNA levels of the monoclonal antibody and histone H3 acetylation and methylation levels. We also investigated the effect on HDAC-related isoforms and found that interference with the HDAC5 gene increased the monoclonal antibody titer by 1.64-fold. The results of this work provide an effective method of using epigenetic regulatory strategies to enhance the expression of recombinant proteins in CHO cells. KEY POINTS: • HDAC/LSD1 dual-target small molecule inhibitor can increase the expression level of recombinant monoclonal antibodies in CHO cells. • By affecting the acetylation and methylation levels of histones in CHO cells and downregulating HDAC5, the production of recombinant monoclonal antibodies increased. • It provides an effective pathway for applying epigenetic regulation strategies to enhance the expression of recombinant proteins.

Melatonin Attenuates Diabetic Retinopathy by Regulating EndMT of Retinal Vascular Endothelial Cells via Inhibiting the HDAC7/FOXO1/ZEB1 Axis.

Diabetic retinopathy (DR) is characterized as a microvascular disease. Nonproliferative diabetic retinopathy (NPDR) presents with alterations in retinal blood flow and vascular permeability, thickening of the basement membrane, loss of pericytes, and formation of acellular capillaries. Endothelial-mesenchymal transition (EndMT) of retinal microvessels may play a critical role in advancing NPDR. Melatonin, a hormone primarily secreted by the pineal gland, is a promising therapeutic for DR. This study explored the EndMT in retinal microvessels of NPDR and its related mechanisms. The effect of melatonin on the retina of diabetic rats was evaluated by electroretinogram (ERG) and histopathologic slide staining. Furthermore, the effect of melatonin on human retinal microvascular endothelial cells (HRMECs) was detected by EdU incorporation assay, scratch assay, transwell assay, and tube formation test. Techniques such as RNA-sequencing, overexpression or knockdown of target genes, extraction of cytoplasmic and nuclear protein, co-immunoprecipitation (co-IP), and multiplex immunofluorescence facilitated the exploration of the mechanisms involved. Our findings reveal, for the first time, that melatonin attenuates diabetic retinopathy by regulating EndMT of retinal vascular endothelial cells via inhibiting the HDAC7/FOXO1/ZEB1 axis. Collectively, these results suggest that melatonin holds potential as a therapeutic strategy to reduce retinal vascular damage and protect vision in NPDR.

Hdac3 deficiency limits periosteal reaction associated with Western diet feeding in female mice.

Diet-induced obesity is associated with enhanced systemic inflammation that limits bone regeneration. HDAC inhibitors are currently being explored as anti-inflammatory agents. Prior reports show that myeloid progenitor-directed Hdac3 ablation enhances intramembranous bone healing in female mice. In this study, we determined if Hdac3 ablation increased intramembranous bone regeneration in mice fed a high-fat/high-sugar (HFD) diet. Micro-CT analyses demonstrated that HFD-feeding enhanced the formation of periosteal reaction tissue of control littermates, reflective of suboptimal bone healing. We confirmed enhanced bone volume within the defect of Hdac3-ablated females and showed that Hdac3 ablation reduced the amount of periosteal reaction tissue following HFD feeding. Osteoblasts cultured in a conditioned medium derived from Hdac3-ablated cells exhibited a four-fold increase in mineralization and enhanced osteogenic gene expression. We found that Hdac3 ablation elevated the secretion of several chemokines, including CCL2. We then confirmed that Hdac3 deficiency increased the expression of Ccl2. Lastly, we show that the proportion of CCL2-positve cells within bone defects was significantly higher in Hdac3-deficient mice and was further enhanced by HFD. Overall, our studies demonstrate that Hdac3 deletion enhances intramembranous bone healing in a setting of diet-induced obesity, possibly through increased production of CCL2 by macrophages within the defect.

Development of a First-in-Class DNMT1/HDAC Inhibitor with Improved Therapeutic Potential and Potentiated Antitumor Immunity.

Epigenetic therapies have emerged as a key paradigm for treating malignancies. In this study, a series of DNMT1/HDAC dual inhibitors were obtained by fusing the key pharmacophores from DNMT1 inhibitors (DNMT1i) and HDAC inhibitors (HDACi). Among them, compound (R)-23a demonstrated significant DNMT1 and HDAC inhibition both in vitro and in cells and largely phenocopied the synergistic effects of combined DNMT1i and HDACi in reactivating epigenetically silenced tumor suppressor genes (TSGs). This translated into a profound tumor growth inhibition (TGI = 98%) of (R)-23a in an MV-4-11 xenograft model, while displaying improved tolerability compared with single agent combination. Moreover, in a syngeneic MC38 mouse colorectal tumor model, (R)-23a outperformed the combinatory treatment in reshaping the tumor immune microenvironment and inducing tumor regression. Collectively, the novel DNMT1/HDAC dual inhibitor (R)-23a effectively reverses the cancer-specific epigenetic abnormalities and holds great potential for further development into cancer therapeutic agents.

Role of histone deacetylases and their inhibitors in neurological diseases.

Histone deacetylases (HDACs) are zinc-dependent deacetylases that remove acetyl groups from lysine residues of histones or form protein complexes with other proteins for transcriptional repression, changing chromatin structure tightness, and inhibiting gene expression. Recent in vivo and in vitro studies have amply demonstrated the critical role of HDACs in the cell biology of the nervous system during both physiological and pathological processes and have provided new insights into the conduct of research on neurological disease targets. In addition, in vitro and in vivo studies on HDAC inhibitors show promise for the treatment of various diseases. This review summarizes the regulatory mechanisms of HDAC and the important role of its downstream targets in nervous system diseases, and summarizes the therapeutic mechanisms and efficacy of HDAC inhibitors in various nervous system diseases. Additionally, the current pharmacological situation, problems, and developmental prospects of HDAC inhibitors are described. A better understanding of the pathogenic mechanisms of HDACs in the nervous system may reveal new targets for therapeutic interventions in diseases and help to relieve healthcare pressure through preventive measures.

Unbiased screening identifies regulators of cell-cell adhesion and treatment options in pemphigus.

Cell-cell junctions, and specifically desmosomes, are crucial for robust intercellular adhesion. Desmosomal function is compromised in the autoimmune blistering skin disease pemphigus vulgaris. We combine whole-genome knockout screening and a promotor screen of the desmosomal gene desmoglein 3 in human keratinocytes to identify novel regulators of intercellular adhesion. Kruppel-like-factor 5 (KLF5) directly binds to the desmoglein 3 regulatory region and promotes adhesion. Reduced levels of KLF5 in patient tissue indicate a role in pemphigus vulgaris. Autoantibody fractions from patients impair intercellular adhesion and reduce KLF5 levels in in vitro and in vivo disease models. These effects were dependent on increased activity of histone deacetylase 3, leading to transcriptional repression of KLF5. Inhibiting histone deacetylase 3 increases KLF5 levels and protects against the deleterious effects of autoantibodies in murine and human pemphigus vulgaris models. Together, KLF5 and histone deacetylase 3 are regulators of desmoglein 3 gene expression and intercellular adhesion and represent potential therapeutic targets in pemphigus vulgaris.

Suppression of SlHDT1 expression increases fruit yield and decreases drought and salt tolerance in tomato.

Histone deacetylation, one of most important types of post-translational modification, plays multiple indispensable roles in plant growth and development and abiotic stress responses. However, little information about the roles of histone deacetylase in regulating inflorescence architecture, fruit yield, and stress responses is available in tomato. Functional characterization revealed that SlHDT1 participated in the control of inflorescence architecture and fruit yield by regulating auxin signalling, and influenced tolerance to drought and salt stresses by governing abscisic acid (ABA) signalling. More inflorescence branches and higher fruit yield, which were influenced by auxin signalling, were observed in SlHDT1-RNAi transgenic plants. Moreover, tolerance to drought and salt stresses was decreased in SlHDT1-RNAi transgenic lines compared with the wild type (WT). Changes in parameters related to the stress response, including decreases in survival rate, chlorophyll content, relative water content (RWC), proline content, catalase (CAT) activity and ABA content and an increase in malonaldehyde (MDA) content, were observed in SlHDT1-RNAi transgenic lines. In addition, the RNA-seq analysis revealed varying degrees of downregulation for genes such as the stress-related genes SlABCC10 and SlGAME6 and the pathogenesis-related protein P450 gene SlCYP71A1, and upregulation of the pathogenesis-related protein P450 genes SlCYP94B1, SlCYP734A7 and SlCYP94A2 in SlHDT1-RNAi transgenic plants, indicating that SlHDT1 plays an important role in the response to biotic and abiotic stresses by mediating stress-related gene expression. In summary, the data suggest that SlHDT1 plays essential roles in the regulation of inflorescence architecture and fruit yield and in the response to drought and salt stresses.

Synthesis and biological evaluation of ortho-phenyl phenylhydroxamic acids containing phenothiazine with improved selectivity for class IIa histone deacetylases.

Class IIa histone deacetylases (HDACs) have been linked to tumorigenesis in various cancers. Previously, we designed phenylhydroxamic acid LH4f as a potent class IIa HDAC inhibitor. However, it also unselectively inhibited class I and class IIb HDACs. To enhance the compound's selectivity towards class IIa HDACs, the ortho-phenyl group from the selective HDAC7 inhibitor 1 is incorporated into ortho position of the phenylhydroxamic acid in LH4f. Compared to LH4f, most resulting compounds displayed substantially improved selectivity towards the class IIa HDACs. Notably, compound 7 g exhibited the strongest HDAC9 inhibition with an IC50 value of 40 nM. Molecular modelling further identified the key interactions of compound 7 g bound to HDAC9. Compound 7 g significantly inhibited several human cancer cells, induced apoptosis, modulated caspase-related proteins as well as p38, and caused DNA damage. These findings suggest the potential of class IIa HDAC inhibitors as lead compounds for the development of cancer therapeutics.

Phosphatase LHPP confers prostate cancer ferroptosis activation by modulating the AKT-SKP2-ACSL4 pathway.

LHPP, a novel, recognized tumor suppressor, exerts a critical influence on the regulation of tumor cell proliferation and survival by modulating various signaling pathways with its phosphatase activity. Here, we unveil a robust correlation between reduced LHPP expression and adverse prognosis in prostate cancer. We demonstrate that LHPP interacts with AKT, thereby dampening AKT phosphorylation and subsequently inhibiting ACSL4 phosphorylation at the T624 site. This interaction impedes phosphorylation-dependent ubiquitination, thwarting SKP2 from recognizing and binding to ACSL4 at the K621 site. As a result, ACSL4 is spared from lysosomal degradation, leading to its accumulation and the promotion of lipid peroxidation, and ferroptosis. Moreover, our findings reveal that Panobinostat, a potent histone-deacetylase inhibitor, intricately regulates LHPP expression at multiple levels through the inhibition of HDAC3. This complex modulation enhances the ferroptosis pathway, offering a novel mechanism for curtailing the growth of prostate tumors and highlighting its significant translational potential for clinical application.

MeCP2 is a naturally supercharged protein with cell membrane transduction capabilities.

The intrinsically disordered protein MeCP2 is a global transcriptional regulator encoded by the MECP2 gene. Although the structured domains of MeCP2 have been the subject of multiple studies, its unstructured regions have not been that extensively characterized. In this work, we show that MeCP2 possesses properties akin to those of supercharged proteins. By utilizing its unstructured portions, MeCP2 can successfully transduce across cell membranes and localize to heterochromatic foci in the nuclei, displaying uptake levels a third lower than a MeCP2 construct fused to the cell-penetrating peptide TAT. MeCP2 uptake can further be enhanced by the addition of compounds that promote endosomal escape following cellular trafficking by means of macropinocytosis. Using a combination of in silico prediction algorithms and live-cell imaging experiments, we mapped the sequence in MeCP2 responsible for its cellular incorporation, which bears a striking resemblance to TAT itself. Transduced MeCP2 was shown to interact with HDAC3. These findings provide valuable insight into the properties of MeCP2 and may be beneficial for devising future protein-based treatment strategies.

Effective enhancement of the ability of Monascus pilosus to produce lipid-lowering compound Monacolin K via perturbation of metabolic flux and histone acetylation modification.

Monacolin K (MK), also known as lovastatin, is a polyketide compound with the ability to reduce plasma cholesterol levels and many other bio-activities. Red yeast rice (also named Hongqu) rich in MK derived from Monascus fermentation has attracted widespread attention due to its excellent performance in reducing blood lipids. However, industrial Monascus fermentation suffers from the limitations such as low yield of MK, long fermentation period, and susceptibility to contamination. In this study, we firstly blocked the competitive pathway of MK biosynthesis to create polyketide synthase gene pigA (the key gene responsible for the biosynthesis of Monascus azaphilone pigments) deficient strain A1. Then, based on the strategies to increase precursor supply for MK biosynthesis, acetyl-CoA carboxylase gene acc overexpression strains C1 and C2 were constructed with WT and A1 as the parent, respectively. Finally, histone deacetylase gene hos2 overexpression strain H1 was constructed by perturbation of histone acetylation modification. HPLC detection revealed all these four strains significantly increased their abilities to produce MK. After 14 days of solid-state fermentation, the MK yields of strains A1, C1, C2, and H1 reached 2.03 g/100 g, 1.81 g/100 g, 2.45 g/100 g and 2.52 g/100 g, which increased by 28.5 %, 14.7 %, 43.9 % and 36.1 % compared to WT, respectively. RT-qPCR results showed that overexpression of hos2 significantly increased the expression level of almost all genes responsible for MK biosynthesis after 5-day growth. Overall, the abilities of these strains to produce MK has been greatly improved, and MK production period has been shortened to 14 days from 20 days, providing new approaches for efficient production of Hongqu rich in MK.

Transgenerational response of germline histone acetyltransferases and deacetylases to nanoplastics at predicted environmental doses in Caenorhabditis elegans.

Nanoplastics could cause toxic effects on organism and their offsprings; however, how this transgenerational toxicity is formed remains largely unclear. We here examined potential involvement of germline histone acetylation regulation in modulating transgenerational toxicity of polyetyrene nanoparticle (PS-NP) in Caenorhabditis elegans. At parental generation (P0-G), PS-NP (1-100 µg/L) decreased expressions of germline cbp-1 and taf-1 encoding histone acetyltransferases, as well as germline expressions of sir-2.1 and hda-3 encoding histone deacetylase. Decrease in these 4 germline genes were also observed in the offspring of PS-NP (1-100 µg/L) exposed nematodes. Germline RNAi of cbp-1, taf-1, sir-2.1 and hda-3 resulted in more severe transgenerational PS-NP toxicity on locomotion and brood size. Meanwhile, in PS-NP exposed nematodes, germline RNAi of cbp-1, taf-1, sir-2.1 and hda-3 increased expression of genes encoding insulin, FGF, Wnt, and/or Notch ligands and expressions of their receptor genes in the offspring. Susceptibility to transgenerational PS-NP toxicity in cbp-1(RNAi), taf-1(RNAi), sir-2.1(RNAi), and hda-3 (RNAi) was inhibited by RNAi of these germline ligands genes. Moreover, histone deacetylase inhibition served as molecular initiating event (MIE) leading to transgenerational toxicity in epigenetic adverse outcome pathway (AOP) for nanoplastics. Our data provided evidence that germline histone acetylation regulation functioned as an important mechanism for transgenerational toxicity of nanoplastics at predicted environmental doses (PEDs) by affecting secreted ligands in organisms.

HDAC/H3K27ac-mediated transcription of NDUFA3 exerts protective effects on high glucose-treated human nucleus pulposus cells through improving mitochondrial function.

Diabetes mellitus (DM) is a well-documented risk factor of intervertebral disc degeneration (IVDD). The current study was aimed to clarify the effects and mechanisms of NADH: ubiquinone oxidoreductase subunit A3 (NDUFA3) in human nucleus pulposus cells (HNPCs) exposed to high glucose. NDUFA3 was overexpressed in HNPCs via lenti-virus transduction, which were co-treated with high glucose and rotenone (a mitochondrial complex I inhibitor) for 48 h. Cell activities were assessed for cell viability, cell apoptosis, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) ratio, oxygen consumption rate (OCR) and mitochondrial complexes I activities. High glucose decreased cell viability, increased apoptotic cells, increased ROS production, decreased MMP levels and OCR values in HNPCs in a dose-dependent manner. Rotenone co-treatment augmented the high glucose-induced injuries on cell viability, apoptosis, ROS production and mitochondrial function. NDUFA3 overexpression counteracted the high glucose-induced injuries in HNPCs. HDAC/H3K27ac mechanism was involved in regulating NDUFA3 transcription. NDUFA3 knockdown decreased cell viability and increased apoptotic cells, which were reversed by ROS scavenger N-acetylcysteine. HDAC/H3K27ac-mediated transcription of NDUFA3 protects HNPCs against high glucose-induced injuries through suppressing cell apoptosis, eliminating ROS, improving mitochondrial function and oxidative phosphorylation. This study sheds light on candidate therapeutic targets and deepens the understanding of molecular mechanisms behind DM-induced IVDD.

Nucleosome remodeler exclusion by histone deacetylation enforces heterochromatic silencing and epigenetic inheritance.

Heterochromatin enforces transcriptional gene silencing and can be epigenetically inherited, but the underlying mechanisms remain unclear. Here, we show that histone deacetylation, a conserved feature of heterochromatin domains, blocks SWI/SNF subfamily remodelers involved in chromatin unraveling, thereby stabilizing modified nucleosomes that preserve gene silencing. Histone hyperacetylation, resulting from either the loss of histone deacetylase (HDAC) activity or the direct targeting of a histone acetyltransferase to heterochromatin, permits remodeler access, leading to silencing defects. The requirement for HDAC in heterochromatin silencing can be bypassed by impeding SWI/SNF activity. Highlighting the crucial role of remodelers, merely targeting SWI/SNF to heterochromatin, even in cells with functional HDAC, increases nucleosome turnover, causing defective gene silencing and compromised epigenetic inheritance. This study elucidates a fundamental mechanism whereby histone hypoacetylation, maintained by high HDAC levels in heterochromatic regions, ensures stable gene silencing and epigenetic inheritance, providing insights into genome regulatory mechanisms relevant to human diseases.

Suppressed testicular macrophage M1 polarization by HDAC5 enforces insensitivity to LPS-elicited blood-testis barrier damage.

Infertility caused by lipopolysaccharide (LPS) exposure due to infection is endangering male fertility worldwide, but the mechanism remains unclear. The blood-testis barrier (BTB) is essential for maintaining spermatogenesis and male fertility. In the present study, we showed that LPS (5.0 mg/kg) treatment markedly down-regulated the expression of BTB-related proteins, expanded the biotin penetration distance and caused histopathological injury in seminiferous tubules in mouse testes. Notably, testicular macrophage M1 polarization induced by LPS seems to be related to BTB damage, which was well confirmed by co-culture of RAW264.7 and TM4 cells in vitro. Interestingly, a low-dose LPS (0.1 mg/kg) pretreatment attenuated down-regulation of BTB-related proteins expression and histopathological injury and shorten biotin penetration distance in seminiferous tubules caused by LPS. Correspondingly, a low-dose LPS pretreatment suppresses testicular macrophage M1 polarization induced by LPS in mouse testes. Further experiments revealed that histone deacetylase 5 (HDAC5) was markedly down-regulated at 2 h and slightly down-regulated at 8 h, but up-regulated at 24 h in mouse testes after LPS treatment. Additionally, low-dose LPS pretreatment against the down-regulation of HDAC5 protein caused by LPS treatment. Notably, the suppressed testicular macrophage M1 polarization by low-dose LPS pretreatment was broken by BRD4354, a specific inhibitor of HDAC5 in vitro. These results suggest suppressed testicular macrophage M1 polarization by HDAC5 enforces insensitivity to LPS-elicited BTB damage.