Histone Hyperacetylation Research Articles

The Rad53CHK1/CHK2-Spt21NPAT and Tel1ATM axes couple glucose tolerance to histone dosage and subtelomeric silencing

The DNA damage response (DDR) coordinates DNA metabolism with nuclear and non-nuclear processes. The DDR kinase Rad53CHK1/CHK2 controls histone degradation to assist DNA repair. However, Rad53 deficiency causes histone-dependent growth defects in the absence of DNA damage, pointing out unknown physiological functions of the Rad53-histone axis. Here we show that histone dosage control by Rad53 ensures metabolic homeostasis. Under physiological conditions, Rad53 regulates histone levels through inhibitory phosphorylation of the transcription factor Spt21NPAT on Ser276. Rad53-Spt21 mutants display severe glucose dependence, caused by excess histones through two separable mechanisms: dampening of acetyl-coenzyme A-dependent carbon metabolism through histone hyper-acetylation, and Sirtuin-mediated silencing of starvation-induced subtelomeric domains. We further demonstrate that repression of subtelomere silencing by physiological Tel1ATM and Rpd3HDAC activities coveys tolerance to glucose restriction. Our findings identify DDR mutations, histone imbalances and aberrant subtelomeric chromatin as interconnected causes of glucose dependence, implying that DDR kinases coordinate metabolism and epigenetic changes.

A class I histone deacetylase is implicated in the encystation of Entamoeba invadens

Epigenetic mechanisms such as histone acetylation and deacetylation participate in regulation of the genes involved in encystation of Entamoeba invadens. However, the histones and target residues involved, and whether the acetylation and deacetylation of the histones leads to the regulation of gene expression associated with the encystation of this parasite, remain unknown. In this study, we found that E. invadens histone H4 is acetylated in both stages of the parasite and is more highly acetylated during the trophozoite stage than in the cyst. Histone hyperacetylation induced by Trichostatin A negatively affects the encystation of E. invadens, and this inhibition is associated with the downregulation of the expression of genes implicated in the synthesis of chitin, polyamines, gamma-aminobutyric acid pathways and cyst wall proteins, all of which are important in the formation of cysts. Finally, in silico analysis and activity assays suggest that a class I histone deacetylase (EiHDAC3) could be involved in control of the expression of a subset of genes that are important in several pathways during encystation. Therefore, the identification of enzymes that acetylate and/or deacetylate histones that control encystation in E. invadens could be a promising therapeutic target for preventing transmission of other amoebic parasites such as E. histolytica, the causative agent of amoebiasis in humans.

Pancreatic cancers suppress negative feedback of glucose transport to reprogram chromatin for metastasis

Although metastasis is the most common cause of cancer deaths, metastasis-intrinsic dependencies remain largely uncharacterized. We previously reported that metastatic pancreatic cancers were dependent on the glucose-metabolizing enzyme phosphogluconate dehydrogenase (PGD). Surprisingly, PGD catalysis was constitutively elevated without activating mutations, suggesting a non-genetic basis for enhanced activity. Here we report a metabolic adaptation that stably activates PGD to reprogram metastatic chromatin. High PGD catalysis prevents transcriptional up-regulation of thioredoxin-interacting protein (TXNIP), a gene that negatively regulates glucose import. This allows glucose consumption rates to rise in support of PGD, while simultaneously facilitating epigenetic reprogramming through a glucose-fueled histone hyperacetylation pathway. Restoring TXNIP normalizes glucose consumption, lowers PGD catalysis, reverses hyperacetylation, represses malignant transcripts, and impairs metastatic tumorigenesis. We propose that PGD-driven suppression of TXNIP allows pancreatic cancers to avidly consume glucose. This renders PGD constitutively activated and enables metaboloepigenetic selection of additional traits that increase fitness along glucose-replete metastatic routes.

Assays for Validating Histone Acetyltransferase Inhibitors.

Lysine acetyltransferases (KATs) catalyze acetylation of lysine residues on histones and other proteins to regulate chromatin dynamics and gene expression. KATs, such as CBP/p300, are under intense investigation as therapeutic targets due to their critical role in tumorigenesis of diverse cancers. The development of novel small molecule inhibitors targeting the histone acetyltransferase (HAT) function of KATs is challenging and requires robust assays that can validate the specificity and potency of potential inhibitors. This article outlines a pipeline of three methods that provide rigorous in vitro validation for novel HAT inhibitors (HATi). These methods include a test tube HAT assay, Chromatin Hyperacetylation Inhibition (ChHAI) assay, and Chromatin Immunoprecipitation-quantitative PCR (ChIP-qPCR). In the HAT assay, recombinant HATs are incubated with histones in a test tube reaction, allowing for acetylation of specific lysine residues on the histone tails. This reaction can be blocked by a HATi and the relative levels of site-specific histone acetylation can be measured via immunoblotting. Inhibitors identified in the HAT assay need to be confirmed in the cellular environment. The ChHAI assay uses immunoblotting to screen for novel HATi that attenuate the robust hyperacetylation of histones induced by a histone deacetylase inhibitor (HDACi). The addition of an HDACi is helpful because basal levels of histone acetylation can be difficult to detect via immunoblotting. The HAT and ChHAI assays measure global changes in histone acetylation, but do not provide information regarding acetylation at specific genomic regions. Therefore, ChIP-qPCR is used to investigate the effects of HATi on histone acetylation levels at gene regulatory elements. This is accomplished through selective immunoprecipitation of histone-DNA complexes and analysis of the purified DNA through qPCR. Together, these three assays allow for the careful validation of the specificity, potency, and mechanism of action of novel HATi.

Microbiota-derived butyrate limits the autoimmune response by promoting the differentiation of follicular regulatory T cells

BackgroundRheumatoid arthritis (RA) is a chronic debilitating autoimmune disorder with a high prevalence, especially in industrialized countries. Dysbiosis of the intestinal microbiota has been observed in RA patients. For instance, new-onset untreated RA (NORA) is associated with the underrepresentation of the Clostridium cluster XIVa, including Lachnospiraceae, which are major butyrate producers, although the pathological relevance has remained obscure. Follicular regulatory T (TFR) cells play critical regulatory roles in the pathogenesis of autoimmune diseases, including RA. Reduced number of circulating TFR cells has been associated with the elevation of autoantibodies and disease severity in RA. However, the contribution of commensal microbe-derived butyrate in controlling TFR cell differentiation remains unknown.MethodsWe examined the contribution of microbe-derived butyrate in controlling autoimmune arthritis using collagen-induced arthritis (CIA) and SKG arthritis models. We phenotyped autoimmune responses in the gut-associated lymphoid tissues (GALT) in the colon and joint-draining lymph nodes in the CIA model. We developed an in vitro CXCR5+Bcl-6+Foxp3+ TFR (iTFR) cell culture system and examined whether butyrate promotes the differentiation of iTFR cells.FindingsMicrobe-derived butyrate suppressed the development of autoimmune arthritis. The immunization of type II collagen (CII) caused hypertrophy of the GALT in the colon by amplifying the GC reaction prior to the onset of the CIA. Butyrate mitigated these pathological events by promoting TFR cell differentiation. Butyrate directly induced the differentiation of functional TFR cells in vitro by enhancing histone acetylation in TFR cell marker genes. This effect was attributed to histone deacetylase (HDAC) inhibition by butyrate, leading to histone hyperacetylation in the promoter region of the TFR-cell marker genes. The adoptive transfer of the butyrate-treated iTFR cells reduced CII-specific autoantibody production and thus ameliorated the symptoms of arthritis.InterpretationAccordingly, microbiota-derived butyrate serves as an environmental cue to enhance TFR cells, which suppress autoantibody production in the systemic lymphoid tissue, eventually ameliorating RA. Our findings provide mechanistic insights into the link between the gut environment and RA risk.FundingThis work was supported by 10.13039/100009619AMED-Crest (16gm1010004h0101, 17gm1010004h0102, 18gm1010004h0103, and 19gm1010004s0104 to KH), the Japan Society for the Promotion of Science (JP17KT0055, JP16H01369, and JP18H04680 to KH; JP17K15734 to DT), Keio University Special Grant-in-Aid for Innovative Collaborative Research Projects (KH), Keio Gijuku Fukuzawa Memorial Fund for the Advancement of Education and Research (DT), the SECOM Science and Technology Foundation (KH), the Cell Science Research Foundation (KH), the Mochida Memorial Foundation for Medical and Pharmaceutical Research (DT), the Suzuken Memorial Foundation (KH and DT), the Takeda Science Foundation (KH and DT), The Science Research Promotion Fund, and The Promotion and Mutual Aid Corporation for Private Schools of Japan (KH).

Cardioprotection by AN-7, a prodrug of the histone deacetylase inhibitor butyric acid: Selective activity in hypoxic cardiomyocytes and cardiofibroblasts

The anticancer prodrug butyroyloxymethyl diethylphosphate (AN-7), upon metabolic hydrolysis, releases the histone deacetylase inhibitor butyric acid and imparts histone hyperacetylation. We have shown previously that AN-7 increases doxorubicin-induced cancer cell death and reduces doxorubicin toxicity and hypoxic damage to the heart and cardiomyocytes. The cardiofibroblasts remain unprotected against both insults. Herein we examined the selective effect of AN-7 on hypoxic cardiomyocytes and cardiofibroblasts and investigated mechanisms underlying the cell specific response. Hypoxic cardiomyocytes and cardiofibroblasts or H2O2-treated H9c2 cardiomyoblasts, were treated with AN-7 and cell damage and death were evaluated as well as cell signaling pathways and the expression levels of heme oxygenase-1 (HO-1). AN-7 diminished hypoxia-induced mitochondrial damage and cell death in hypoxic cardiomyocytes and reduced hydrogen peroxide damage in H9c2 cells while increasing cell injury and death in hypoxic cardiofibroblasts. In the cell line, AN-7 induced Akt and ERK survival pathway activation in a kinase-specific manner including phosphorylation of the respective downstream targets, GSK-3β and BAD. Hypoxic cardiomyocytes responded to AN-7 treatment by enhanced phosphorylation of Akt, ERK, GSK-3β and BAD and a significant 6-fold elevation in HO-1 levels. In hypoxic cardiofibroblasts, AN-7 did not activate Akt and ERK beyond the effect of hypoxia alone and induced a limited (~1.5-fold) increase in HO-1. The cell specific differences in kinase activation and in heme oxygenase-1 upregulation may explain, at least in part, the disparate outcome of AN-7 treatment in hypoxic cardiomyocytes and hypoxic cardiofibroblasts.

Valproic Acid Significantly Improves CRISPR/Cas9-Mediated Gene Editing.

The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system has emerged as a powerful technology, with the potential to generate transgenic animals. Particularly, efficient and precise genetic editing with CRISPR/Cas9 offers immense prospects in various biotechnological applications. Here, we report that the histone deacetylase inhibitor valproic acid (VPA) significantly increases the efficiency of CRISPR/Cas9-mediated gene editing in mouse embryonic stem cells and embryos. This effect may be caused through globally enhanced chromatin accessibility, as indicate by histone hyperacetylation. Taken together, our results suggest that VPA can be used to increase the efficacy of CRISPR/Cas9 in generating transgenic systems.

Multiple mechanisms regulate H3 acetylation of enhancers in response to thyroid hormone

Hormone-dependent activation of enhancers includes histone hyperacetylation and mediator recruitment. Histone hyperacetylation is mostly explained by a bimodal switch model, where histone deacetylases (HDACs) disassociate from chromatin, and histone acetyl transferases (HATs) are recruited. This model builds on decades of research on steroid receptor regulation of transcription. Yet, the general concept of the bimodal switch model has not been rigorously tested genome wide. We have used a genomics approach to study enhancer hyperacetylation by the thyroid hormone receptor (TR), described to operate as a bimodal switch. H3 acetylation, HAT and HDAC ChIP-seq analyses of livers from hypo- and hyperthyroid wildtype, TR deficient and NCOR1 disrupted mice reveal three types of thyroid hormone (T3)-regulated enhancers. One subset of enhancers is bound by HDAC3-NCOR1 in the absence of hormone and constitutively occupy TR and HATs irrespective of T3 levels, suggesting a poised enhancer state in absence of hormone. In presence of T3, HDAC3-NCOR1 dissociates from these enhancers leading to histone hyperacetylation, suggesting a histone acetylation rheostat function of HDACs at poised enhancers. Another subset of enhancers, not occupied by HDACs, is hyperacetylated in a T3-dependent manner, where TR is recruited to chromatin together with HATs. Lastly, a subset of enhancers, is not occupied directly by TR yet requires TR for histone hyperacetylation. This indirect enhancer activation involves co-association with TR bound enhancers within super-enhancers or topological associated domains. Collectively, this demonstrates various mechanisms controlling hormone-dependent transcription and adds significant details to the otherwise simple bimodal switch model.

Histone Deacetylases Inhibitors in Neurodegenerative Diseases, Neuroprotection and Neuronal Differentiation.

Histone deacetylases (HADC) are the enzymes that remove acetyl group from lysine residue of histones and non-histone proteins and regulate the process of transcription by binding to transcription factors and regulating fundamental cellular process such as cellular proliferation, differentiation and development. In neurodegenerative diseases, the histone acetylation homeostasis is greatly impaired, shifting towards a state of hypoacetylation. The histone hyperacetylation produced by direct inhibition of HDACs leads to neuroprotective actions. This review attempts to elaborate on role of small molecule inhibitors of HDACs on neuronal differentiation and throws light on the potential of HDAC inhibitors as therapeutic agents for treatment of neurodegenerative diseases. The role of HDACs in neuronal cellular and disease models and their modulation with HDAC inhibitors are also discussed. Significance of these HDAC inhibitors has been reviewed on the process of neuronal differentiation, neurite outgrowth and neuroprotection regarding their potential therapeutic application for treatment of neurodegenerative diseases.

Cannabinoid exposure in rat adolescence reprograms the initial behavioral, molecular, and epigenetic response to cocaine

The initial response to an addictive substance can facilitate repeated use: That is, individuals experiencing more positive effects are more likely to use that drug again. Increasing evidence suggests that psychoactive cannabinoid use in adolescence enhances the behavioral effects of cocaine. However, despite the behavioral data, there is no neurobiological evidence demonstrating that cannabinoids can also alter the brain's initial molecular and epigenetic response to cocaine. Here, we utilized a multiomics approach (epigenomics, transcriptomics, proteomics, and phosphoproteomics) to characterize how the rat brain responds to its first encounter with cocaine, with or without preexposure to the synthetic cannabinoid WIN 55,212-2 (WIN). We find that in adolescent (but not in adult) rats, preexposure to WIN results in cross-sensitization to cocaine, which correlates with histone hyperacetylation and decreased levels of HDAC6 in the prefrontal cortex (PFC). In the PFC, we also find that WIN preexposure blunts the typical mRNA response to cocaine and instead results in alternative splicing and chromatin accessibility events, involving genes such as Npas2 Moreover, preexposure to WIN enhances the effects of cocaine on protein phosphorylation, including ERK/MAPK-targets like gephyrin, and modulates the synaptic AMPAR/GluR composition both in the PFC and the nucleus accumbens (NAcc). PFC-NAcc gene network topological analyses, following cocaine exposure, reveal distinct top nodes in the WIN preexposed group, which include PACAP/ADCYAP1. These preclinical data demonstrate that adolescent cannabinoid exposure reprograms the initial behavioral, molecular, and epigenetic response to cocaine.

Histone hyperacetylation mediates enhanced IL-1β production in LPS/IFN-γ-stimulated macrophages.

SummaryUnder the condition of lipopolysaccharide (LPS)/interferon (IFN)‐γ activation, macrophage metabolism is converted from oxidative phosphorylation to glycolysis. In the present work, we analysed whether glycolysis could affect interleukin (IL)‐1β expression through altering histone acetylation levels in mouse bone marrow‐derived macrophages. Immunocytochemistry and Western blot analysis are used to characterize histone acetylation in macrophages stimulated by LPS/IFN‐γ. Real‐time polymerase chain reaction and enzyme‐linked immunosorbent assay were used to determine IL‐1β production. The metabolism of macrophages was monitored in real‐time by the Seahorse test. Our results showed that glycolytic metabolism could enhance histone acetylation and promote IL‐1β production in LPS/IFN‐γ‐activated macrophages. Moreover, increased production of IL‐1β by glycolysis was mediated through enhanced H3K9 acetylation. Importantly, it was found that a high dose of histone deacetylase inhibitor could also significantly increase the expression of IL‐1β in the absence of glycolytic metabolism. In conclusion, this study demonstrates that glycolytic metabolism could regulate IL‐1β expression by increasing histone acetylation levels in LPS/IFN‐γ‐stimulated macrophages.

Chromatin Hyperacetylation Impacts Chromosome Folding by Forming a Nuclear Subcompartment

Delineating how chromosomes fold at length scales beyond one megabase remains obscure relative to smaller-scale folding into TADs, loops, and nucleosomes. We find that rather than simply unfolding chromatin, histone hyperacetylation results in interactions between distant genomic loci separated by tens to hundreds of megabases, even in the absence of transcription. These hyperacetylated "megadomains" are formed by the BRD4-NUT fusion oncoprotein, interact both within and between chromosomes, and form a specific nuclear subcompartment that has elevated gene activity with respect to other subcompartments. Pharmacological degradation of BRD4-NUT results in collapse of megadomains and attenuation of the interactions between them. In contrast, these interactions persist and contacts between newly acetylated regions are formed after inhibiting RNA polymerase II initiation. Our structure-function approach thus reveals that broad chromatin domains of identical biochemical composition, independent of transcription, form nuclear subcompartments, and also indicates the potential of altering chromosome structure for treating human disease.

Skin wound healing triggers epigenetic modifications of histone H4

BackgroundThe skin is the largest organ of the human body. Upon injury, the skin triggers a sequence of signaling pathways that induce epithelial proliferation, migration, and ultimately, the re-establishment of the epithelial barrier. Our study explores the unknown epigenetic regulations of wound healing from a histone perspective. Posttranslational modifications of histones enhance chromatin accessibility and modify gene transcription.MethodsFull-thickness wounds were made in the dorsal skin of twenty-four C57/B6 mice (C57BL/6J), followed by the use of ring-shaped silicone splints to prevent wound contraction. Tissue samples were collected at three time points (post-operatory day 1, 4, and 9), and processed for histology. Immunofluorescence was performed in all-time points using markers for histone H4 acetylation at lysines K5, K8, K12, and K16.ResultsWe found well-defined histone modifications associated with the stages of healing. Most exciting, we showed that the epidermis located at a distance from the wound demonstrated changes in histone acetylation, particularly the deacetylation of histone H4K5, H4K8, and H4K16, and hyperacetylation of H4K12. The epidermis adjacent to the wound revealed the deacetylation of H4K5 and H4K8 and hyperacetylation of H4K12. Conversely, the migratory epithelium (epithelial tongue) displayed significant acetylation of H4K5 and H4K12. The H4K5 and H4K8 were decreased in the newly formed epidermis, which continued to display high levels of H4K12 and H4K16.ConclusionsThis study profiles the changes in histone H4 acetylation in response to injury. In addition to the epigenetic changes found in the healing tissue, these changes also took place in tissues adjacent and distant to the wound. Furthermore, not only deacetylation but also hyperacetylation occurred during tissue repair and regeneration.

Crosstalk between DNA methylation and histone acetylation triggers GDNF high transcription in glioblastoma cells

BackgroundGlial cell line-derived neurotrophic factor (GDNF) is highly expressed in glioblastoma (GBM) and blocking its expression can inhibit the initiation and development of GBM. GDNF is a dual promoter gene, and the promoter II with two enhancers and two silencers plays a major role in transcription initiation. We had previously reported that histone hyperacetylation and DNA hypermethylation in GDNF promoter II region result in high transcription of GDNF in GBM cells, but the mechanism remains unclear. In this study, we investigated whether these modifications synergistically regulate high GDNF transcription in GBM.ResultsCyclic AMP response element binding protein (CREB) expression and phosphorylation at S133 were significantly increased in human GBM tissues and GBM cell lines (U251 and U343). In U251 GBM cells, high expressed CREB significantly enhanced GDNF transcription and promoter II activity. CREB regulated GDNF transcription via the cyclic AMP response elements (CREs) in enhancer II and silencer II of GDNF promoter II. However, the two CREs played opposite regulatory roles. Interestingly, hypermethylation of CRE in silencer II occurred in GBM tissues and cells which led to decreased and increased phosphorylated CREB (pCREB) binding to silencer II and enhancer II, respectively. Moreover, pCREB recruited CREB binding protein (CBP) with histone acetylase activity to the CRE of GDNF enhancer II, thereby increasing histone H3 acetylation and RNA polymerase II recruitment there and at the transcription start site (TSS), and promoted GDNF high transcription in U251 cells. The results indicated that high GDNF transcription was attributable to DNA hypermethylation in CRE of GDNF silencer II increasing pCREB binding to CRE in enhancer II, which enhanced CBP recruitment, histone H3 acetylation, and RNA polymerase II recruitment there and at the TSS.ConclusionsOur results demonstrate that pCREB-induced crosstalk between DNA methylation and histone acetylation at the GDNF promoter II enhanced GDNF high transcription, providing a new perspective for GBM treatment.

Histone hyperacetylation may improve the preimplantation development and epigenetic status of cloned embryos

The current study investigated the mechanism of mini pig fetal fibroblasts in improving the epigenetic modification and preimplantation development of cloned embryos. The results showed that the increased AcH3K14 level was dose- and time-dependent. Histone hyperacetylation had no significant effect on cell morphology, cell viability, cell cycle, and relative gene (HDAC1, HAT1, DNMT3A, and BAX) expression. The treated cloned embryos had significantly higher development rates and the total nuclei number than the control (27.62 ± 6.94 % vs. 16.14 ± 10.55 %; 43.90 ± 18.39 vs. 33.06 ± 15.87; P < 0.05). The AcH3K14 level in the treated cloned blastocysts was close to that of IVF blastocysts (5.17 ± 0.93 vs. 5.45 ± 1.91, P > 0.05). The gene transcription (CDX2 and OCT4) of the treated cloned blastocysts was significantly up-regulated than the control (3.32 ± 0.51 vs. 2.05 ± 0.30; 1.21 ± 0.18 vs. 0.81 ± 0.09; P < 0.05). The improvement in the cloned embryo development and the partial correction of abnormal acetylation modification were not necessarily related to the cellular characteristics. This could be caused by histone hyperacetylation of mini pig fetal fibroblasts.

Neonatal Injury Increases Gut Permeability by Epigenetically Suppressing E-Cadherin in Adulthood.

Altered intestinal epithelial integrity is an important susceptibility trait in inflammatory bowel disease (IBD), and early life stressors are reported to contribute to this disease susceptibility in adulthood. To identify disease mechanisms associated with early-life trauma that exacerbate IBD in adulthood, we used a "double-hit" neonatal inflammation (NI) and adult inflammation (AI) model that exhibits more severe mucosal injury in the colon later in life. In this study, we explore the underlying mechanisms of this aggravated injury. In rats exposed to both NI and AI, we found sustained increases in colonic permeability accompanied by significantly attenuated expression of the epithelial junction protein E-cadherin. Quantitative RT-PCR revealed a decreased Cdh1 (gene of E-cadherin) mRNA expression in NI + AI rats compared with NI or AI rats. Next, we performed microRNA microarrays to identify potential regulators of E-cadherin in NI + AI rats. We confirmed the overexpression of miR-155, a predicted regulator of E-cadherin, and selected it for further analysis based on reported significance in human IBD. Using ingenuity pathway analysis software, the targets and related canonical pathway of miR-155 were analyzed. Mechanistic studies identified histone hyperacetylation at the Mir155 promoter in NI + AI rats, concomitant with elevated RNA polymerase II binding. In vitro, E-cadherin knockdown markedly increased epithelial cell permeability, as did overexpression of miR-155 mimics, which significantly suppressed E-cadherin protein. In vivo, NI + AI colonic permeability was significantly reversed with administration of miR-155 inhibitor rectally. Our collective findings indicate that early-life inflammatory stressors trigger a significant and sustained epithelial injury by suppressing E-cadherin through epigenetic mechanisms.

Autophagy Inhibition Potentiates the Anticancer Effects of a Bendamustine Derivative NL-101 in Acute T Lymphocytic Leukemia.

Acute T lymphocytic leukemia (T-ALL) is an aggressive hematologic resulting from the malignant transformation of T-cell progenitors. Drug resistance and relapse are major difficulties in the treatment of T-ALL. Here, we report the antitumor potency of NL-101, a compound that combines the nitrogen mustard group of bendamustine with the hydroxamic acid group of vorinostat. We found NL-101 exhibited efficient antiproliferative activity in T-ALL cell lines (IC50 1.59–1.89 μM), accompanied by cell cycle arrest and apoptosis, as evidenced by the increased expression of Cyclin E1, CDK2, and CDK4 proteins and cleavage of PARP. In addition, this bendamustine-derived drug showed both a HDACi effect as demonstrated by histone hyperacetylation and p21 transcription and a DNA-damaging effect as shown by an increase in γ-H2AX. Intriguingly, we found that NL-101-induced autophagy in T-ALL cells through inhibiting Akt-mTOR signaling pathway, as indicated by an increase in LC3-I to LC3-II conversion and decrease of p62. Furthermore, inhibition of autophagy by 3-methyladenine increased apoptotic cell death by NL-101, suggesting a prosurvival role of autophagy. In summary, our finding provides rationale for investigation of NL-101 as a DNA/HDAC dual targeting drug in T-ALL, either as a single agent or in combination with autophagy inhibitors.

A histone K-lysine acetyltransferase CqKAT2A-like gene promotes white spot syndrome virus infection by enhancing histone H3 acetylation in red claw crayfish Cherax quadricarinatus

In contrast to that hypoacetylation of histones is associated with condensed chromatin and gene silencing, the hyperacetylation of histones can promote an “open chromatin” conformation and transcriptional activation, which is recruited by some viruses to enhance the viral genome replication in host cells. However, the function of histone acetylation modification in the infection of white spot syndrome virus (WSSV), one of the most virulent pathogens for crustaceans like shrimp and crayfish at present, is still unknown. Previously, we found that the transcript of a histone K-Lysine acetyltransferase CqKAT2A-like gene was down-regulated in a differentially expressed transcriptome library of the haematopietic tissue (Hpt) cells from red claw crayfish Cherax quadricarinatus upon WSSV infection at 12 hpi. To further reveal its possible role in anti-WSSV response, CqKAT2A-like gene was then identified with an open reading frame (ORF) of 2523 bp encoding 840 amino acids, which contained a conserved PCAF-N domain, acetyltransf1 domain and bromo domain. Gene expression analysis showed that CqKAT2A-like was distributed in all tissues examined with high presence in haemocyte and muscle, and the transcript was significantly down-regulated after WSSV infection in Hpt cells. Furthermore, the level of histone H3 acetylation (H3ac) was strongly reduced by gene silencing of CqKAT2A-like, which was accompanied with the significantly decreased gene expression of WSSV in Hpt cells, suggesting that CqKAT2A-like gene can promote the activity H3ac and the replication of WSSV. When the H3ac was induced by histone deacetyltransferase inhibitor TSA, the transcription of WSSV genes including both IE1 and VP28 genes was significantly increased, indicating that H3ac participated in WSSV infection in Hpt cells. Taken together, these data suggest that CqKAT2A-like gene might promote the replication of WSSV by regulating H3ac, which sheds new light on the pathogenesis of WSSV in crustaceans.

Heterochromatin formation in Drosophila requires genome-wide histone deacetylation in cleavage chromatin before mid-blastula transition in early embryogenesis

Su(var) mutations define epigenetic factors controlling heterochromatin formation and gene silencing in Drosophila. Here, we identify SU(VAR)2-1 as a novel chromatin regulator that directs global histone deacetylation during the transition of cleavage chromatin into somatic blastoderm chromatin in early embryogenesis. SU(VAR)2-1 is heterochromatin-associated in blastoderm nuclei but not in later stages of development. In larval polytene chromosomes, SU(VAR)2-1 is a band-specific protein. SU(VAR)2-1 directs global histone deacetylation by recruiting the histone deacetylase RPD3. In Su(var)2-1 mutants H3K9, H3K27, H4K8 and H4K16 acetylation shows elevated levels genome-wide and heterochromatin displays aberrant histone hyper-acetylation. Whereas H3K9me2- and HP1a-binding appears unaltered, the heterochromatin-specific H3K9me2S10ph composite mark is impaired in heterochromatic chromocenters of larval salivary polytene chromosomes. SU(VAR)2-1 contains an NRF1/EWG domain and a C2HC zinc-finger motif. Our study identifies SU(VAR)2-1 as a dosage-dependent, heterochromatin-initiating SU(VAR) factor, where the SU(VAR)2-1-mediated control of genome-wide histone deacetylation after cleavage and before mid-blastula transition (pre-MBT) is required to enable heterochromatin formation.

Zinc Dependent Histone Deacetylase Inhibitors in Cancer Therapeutics: Recent Update.

Histone deacetylases (HDAC) are an important class of enzymes that play a pivotal role in epigenetic regulation of gene expression that modifies the terminal of core histones leading to remodelling of chromatin topology and thereby controlling gene expression. HDAC inhibitors (HDACi) counter this action and can result in hyperacetylation of histones, thereby inducing an array of cellular consequences such as activation of apoptotic pathways, generation of reactive oxygen species (ROS), cell cycle arrest and autophagy. Hence, there is a growing interest in the potential clinical use of HDAC inhibitors as a new class of targeted cancer therapeutics. Methodology and Result: Several research articles spanning between 2016 and 2017 were reviewed in this article and presently offer critical insights into the important strategies such as structure-based rational drug design, multi-parameter lead optimization methodologies, relevant SAR studies and biology of various class of HDAC inhibitors, such as hydroxamic acids, benzamides, cyclic peptides, aliphatic acids, summarising the clinical trials and results of various combination drug therapy till date. This review will provide a platform to the synthetic chemists and biologists to cater the needs of both molecular targeted therapy and combination drug therapy to design and synthesize safe and selective HDAC inhibitors in cancer therapeutics.