Expression Of Histone Acetyltransferases Research Articles

Changes in histone lysine acetylation, but not DNA methylation during facultative hibernation in Syrian hamster liver

BackgroundHibernation (torpor) is a strategy to survive extreme environmental conditions, associated with a significant decrease in metabolism and body temperature. The inducibility by the environment of torpor for facultative hibernators designates epigenetic mechanisms as likely candidates for regulation. Therefore, we set out to unravel epigenetics in the liver of a facultative hibernator, Syrian hamster (Mesocricetus auratus), sampled at different phases during hibernation, by assessing the expression of epigenetic writer and eraser enzymes, histone acetylation dynamics, and DNA methylation levels.ResultsExpression of epigenetic writers/erasers confirmed previously reported results obtained in obligatory hibernators, but might point to a mechanism specific for facultative hibernators, e.g., differential expression of histone acetyltransferases (HATs; KAT6A, KAT6B, KAT7, and KAT13D/CLOCK). These findings were in accordance with observed changes in histone H3 and H4 acetylation changes. Overall histone deacetylase (HDAC) activity was highest in torpor. No differences were detected in DNA methylation throughout all phases.ConclusionOur study thus points to histone acetylation as an important player in facultative hamster hibernation, which may underlie the orchestration of gene expression changes throughout hibernation.

Endoplasmic reticulum stress caused by traumatic injury promotes cardiomyocyte apoptosis through acetylation modification of GRP78.

Cardiomyocyte apoptosis is an important cause of trauma-induced secondary cardiac injury (TISCI), in which the endoplasmic reticulum stress (ERS)-mediated apoptosis signaling pathway is known to be first activated, but the mechanism remains unclear. In this study, rat models of traumatic injury are established by using the Noble-Collip trauma device. The expression of glucose-regulating protein 78 (GRP78, a molecular chaperone of the cardiomyocyte ER), acetylation modification of GRP78 and apoptosis of cardiomyocytes are determined. The results show that ERS-induced GRP78 elevation does not induce cardiomyocyte apoptosis in the early stage of trauma. However, with prolonged ERS, the GRP78 acetylation level is elevated, and the apoptosis of cardiomyocytes also increases significantly. In addition, in the early stage of trauma, the expression of histone acetyl-transferase (HAT) P300 is increased and that of histone deacetylase 6 (HDAC6) is decreased in cardiomyocytes. Inhibition of HDAC function could induce the apoptosis of traumatic cardiomyocytes by increasing the acetylation level of GRP78. Our present study demonstrates for the first time that post-traumatic protracted ERS can promote cardiomyocyte apoptosis by increasing the acetylation level of GRP78, which may provide an experimental basis for seeking early molecular events of TISCI.

Abstract 17359: UCP2 Induced Glycolysis Promotes Histone Acetylation to Regulate Cardiomyocyte Cell Cycle After Injury

Developmental cardiac tissue is proliferative capable of robust regenerative response after myocardial injury, but this ability is lost by P7 when cardiomyocytes (CMs) exit the cell cycle and become terminally differentiated. Postnatal CMs exhibit a specialized metabolic state that supports rapid proliferation and is altered with loss of regeneration in the heart. Studies have shown that reliance on glycolysis for energy generation is preferred by proliferating CMs and activation of glycolysis promotes cardiac repair. Nevertheless, the role of glycolysis in regulating CM gene program linked to cell cycle and repair in the heart remains poorly studied. Here, we identify a novel role for mitochondrial uncoupling protein 2 (UCP2) in the heart regulating CM cell cycle dynamics. UCP2 was found to be primarily active during cardiac development, rapidly decreases after birth and is expressed at low levels in the adult heart. UCP2 overexpression in human IPS derived CMs increases cell cycle progression as assessed by immunostaining and flow cytometry-based DNA content analysis. In parallel, neonatal rat ventricular myocytes (NRVMs) overexpressing UCP2 showed increased glycolysis and glycolytic metabolites, reduced mitochondrial membrane potential and mitochondrial activity compared to controls. Next, we generated αMHC-UCPKO mice that showed reduction in total number of CMs and pHH3 levels, increased CM size and ploidy during postnatal development. Adult αMHC-UCPKO subjected to myocardial infarction injury showed significant cardiac dysfunction and fibrosis at 4 weeks compared to controls. Mechanistically, UCP2 induced glycolysis increases ATP-citrate lyase (ACLY) mediated acetyl-CoA generation in the CMs. Additionally, CMs isolated from P1 αMHC-UCPKO showed several histone modifications including decrease in histone acetylation marks. Similarly, NRVMs overexpressing UCP2 showed increased histone H3 acetylation and expression of histone acetyltransferases (HATs) and corresponding decrease in histone deacetylases (HDACs). In conclusion, UCP2 is a novel developmental metabolic regulator of CM cell cycle in the neonatal and adult heart. Moreover, UCP2 induced glycolysis increases cell cycle via altering CM histone acetylation.

Molecular characterization and modulated expression of histone acetyltransferases during cold response of the tick Dermacentor silvarum (Acari: Ixodidae)

BackgroundHistone acetylation is involved in the regulation of stress responses in multiple organisms. Dermacentor silvarum is an important vector tick species widely distributed in China, and low temperature is a crucial factor restricting the development of its population. However, knowledge of the histone acetyltransferases and epigenetic mechanisms underlying cold-stress responses in this tick species is limited.MethodsHistone acetyltransferase genes were characterized in D. silvarum, and their relative expressions were determined using qPCR during cold stress. The association and modulation of histone acetyltransferase genes were further explored using RNA interference, and both the H3K9 acetylation level and relative expression of KAT5 protein were evaluated using western blotting.ResultsThree histone acetyltransferase genes were identified and named as DsCREBBP, DsKAT6B, and DsKAT5. Bioinformatics analysis showed that they were unstable hydrophilic proteins, characterized by the conserved structures of CBP (ZnF_TAZ), PHA03247 super family, Creb_binding, and MYST(PLN00104) super family. Fluorescence quantitative PCR showed that the expression of DsCREBBP, DsKAT6B, and DsKAT5 increased after 3 days of cold treatment, with subsequent gradual decreases, and was lowest on day 9. Western blotting showed that both the H3K9 acetylation level and relative expression of KAT5 in D. silvarum increased after treatment at − 4, 4, and 8 °C for 3 and 6 days, whereas they decreased significantly after a 9-day treatment. RNA interference induced significant gene silencing, and the mortality rate of D. silvarum significantly increased at the respective semi-lethal temperatures.ConclusionThese results imply that histone acetyltransferases play an important role in tick adaptation to low temperatures and lay a foundation for further understanding of the epigenetic regulation of histone acetylation in cold-stressed ticks. Further research is needed to elucidate the mechanisms underlying histone acetylation during cold stress in ticks.Graphical

Targeting BRPF3 moderately reverses olaparib resistance in high grade serous ovarian carcinoma.

PARP inhibitors (PARPi) kill cancer cells by stalling DNA replication and preventing DNA repair, resulting in a critical accumulation of DNA damage. Resistance to PARPi is a growing clinical problem in the treatment of high grade serous ovarian carcinoma (HGSOC). Acetylation of histone H3 lysine 14 (H3K14ac) and associated histone acetyltransferases (HATs) and epigenetic readers have known functions in DNA repair and replication. Our objectives are to examine their expression and activities in the context of PARPi-resistant HGSOC, and to determine if targeting H3K14ac or associated proteins has therapeutic potential. Using mass spectrometry profiling of histone modifications, we observed increased H3K14ac enrichment in PARPi-resistant HGSOC cells relative to isogenic PARPi-sensitive lines. By reverse-transcriptase quantitative PCRand RNA-seq, we also observed altered expression of numerous HATs in PARPi-resistant HGSOC cells and a PARPi-resistant PDX model. Knockdown of HATs only modestly altered PARPi response, although knockdown and inhibition of PCAF significantly increased resistance. Pharmacologic inhibition of HBO1 depleted H3K14ac but did not affect PARPi response. However, knockdown and inhibition of BRPF3, a bromodomain and PHD-finger containing protein that is known to interact in a complex with HBO1, did reduce PARPi resistance. This study demonstrates that depletion of H3K14ac does not affect PARPi response in HGSOC. Our data suggest that the bromodomain function of HAT proteins, such as PCAF, or accessory proteins, such as BRPF3, may play a more direct role compared to direct HATsfunction in PARPi response.

Histone acetyltransferases and histone deacetyl transferases play crucial role during oogenesis and early embryo development.

Dynamic epigenetic regulation is critical for proper oogenesis and early embryo development. During oogenesis, fully grown germinal vesicle oocytes develop to mature Metaphase II oocytes which are ready for fertilization. Fertilized oocyte proliferates mitotically until blastocyst formation and the process is called early embryo development. Throughout oogenesis and early embryo development, spatio-temporal gene expression takes place, and this dynamic gene expression is controlled with the aid of epigenetics. Epigenetic means that gene expression can be altered without changing DNA itself. Epigenome is regulated through DNA methylation and histone modifications. While DNA methylation generally ends up with repression of gene expression, histone modifications can result in expression or repression depending on type of modification, type of histone protein and its specific residue. One of the modifications is histone acetylation which generally ends up with gene expression. Histone acetylation occurs through the addition of acetyl group onto amino terminal of the core histone proteins by histone acetyltransferases (HATs). Contrarily, histone deacetylation is associated with repression of gene expression, and it is catalyzed by histone deacetylases (HDACs). This review article focuses on what is known about alterations in the expression of HATs and HDACs and emphasizes importance of HATs and HDACs during oogenesis and early embryo development.

Abrin inactivating mitochondrial ribosome induced anther abortion in cotton CMS line LD6A by damaging mitochondrial membrane structure

Cytoplasmic male sterile (CMS) system has extensively been exploited for hybrid vigor in plant breeding programs. However, its application in many crops is limited due to poor understanding of molecular mechanism of fertility restoration. Using advanced analytical approaches, we aimed to elucidate the molecular pathways, regulating CMS induction and fertility restoration in cotton. Reproductive structures of a novel CMS (LD6A) and its maintainer (LD6B) lines were analyzed for physiological and proteomic changes during the development process. Transmission electron micrographs of anther tapetum showed a relatively indistinct inner ridge of CMS than of LD6B mitochondria at tetrad stage. Furthermore, at pollen mother cell and tetrad stages, CMS anthers accumulated a significantly higher reactive oxygen species than the maintainer line. At the protein level, CMS anthers induced significantly higher Abrin (XP_016705148.2), lower tricarboxylic acid cycle enzyme (malate dehydrogenase, malic enzyme, isocitrate dehydrogenase), and histone acetyltransferase expression than its maintainer line. Suggesting that abnormal sequence of mitochondrial ribosome gene rps4 and rpl10 and high expression of ribosome-inactivating protein Abrin in CMS line damaged mitochondrial membrane. This inhibited energy supply from the non-degraded tapetum, and consequently induced pollen sterility in LD6A. These data provide new insights into CMS mechanism in cotton crops that can be used for developing new CMS germplasm resources.

Comprehensive Characterization of HATs and HDACs in Human Cancers Reveals Their Role in Immune Checkpoint Blockade.

Histone acetylation that controlled by two mutually antagonistic enzyme families, histone acetyl transferases (HATs) and histone deacetylases (HDACs), as one of major epigenetic mechanisms controls transcription and its abnormal regulation was implicated in various aspects of cancer. However, the comprehensive understanding of HDACs and HATs in cancer is still lacking. Systematically analysis through 33 cancer types based on next-generation sequence data reveals heterogeneous expression pattern of HDACs and HATs across different cancer types. In particular, HDAC10 and HDAC6 show significant downregulation in most cancers. Principal components analysis (PCA) of pan-cancer reveals significant difference of HDACs and HATs between normal tissues and normal tissue adjacent to the tumor. The abnormal expression of HDACs and HATs was partially due to CNV and DNA methylation in multiple types of cancer. Prognostic significance (AUC reached 0.736) of HDACs and HATs demonstrates a five-gene signature including KAT2A, HAT1, KAT5, CREBBP and SIRT1 in KIRC. Analysis of NCI-60 drug database reveals the cytotoxic effect of several drugs are associated with dysregulated expression of HDACs and HATs. Analysis of immune infiltration and immunotherapy reveals that KAT2B and HDAC9 are associated with immune infiltration and immunotherapy. Our analysis provided comprehensive understanding of the regulation and implication of HDACs and HATs in pan-cancer. These findings provide novel evidence for biological investigating potential individual HDACs and HATs in the development and therapy of cancer in the future.

Down-regulation of MAPK pathway alleviates TRPV4-mediated trigeminal neuralgia by inhibiting the activation of histone acetylation

Our objective of this study is to determine the molecular mechanism of MAPKs (mitogen activated protein kinase systems) on TRPV4 (transient receptor potential vanilloid 4)-mediated trigeminal neuralgia (TN). Partial chronic constriction injury of the infraorbital nerve (CCI-ION) ligation model was used in this research. When treated with antagonists of p38, JNK or ERK, the mechanical hyperalgesia threshold, nerve fiber disorder, myelinoclasis, and Schwann cells proliferation could be reversed. RT-PCR (real-time quantitative polymerase chain reaction), Western blot and IHC (immunohistochemistry) showed that TRPV4 mRNA and protein levels, TRPV4-positive cells and small positive neurons decreased remarkably in TN group treated with antagonists of p38, JNK or ERK. ELISA (enzyme-linked immunosorbent assay) was performed to discover inhibition of MAPK pathway can down-regulate the expression of HATs (histone acetyltransferases), and up-regulate the expression of HDACs (histone deacetylases) in TN, thus inhibiting histone acetylation. Finally, Western blot was performed to identify the phosphorylation status of p38, JNK and ERK, finding decreased phosphorylation forms in antagonists treated TN groups compared with TN groups. Based on the above investigation method, on a whole, our study showed that down-regulation of MAPK pathway could alleviate TRPV4-mediated trigeminal neuralgia, via inhibiting the activation of histone acetylation.

Epigenetic immunomodulatory effect of eugenol and astaxanthin on doxorubicin cytotoxicity in hormonal positive breast Cancer cells

BackgroundHormonal receptor positive (HR+) breast cancer is the most commonly diagnosed molecular subtype of breast cancer; which showed good response to doxorubicin (DOX)-based chemotherapy. Eugenol (EUG) and astaxanthin (AST) are natural compounds with proved epigenetic and immunomodulatory effects in several cancer cell lines. This study has been initiated to investigate the molecular mechanism (s) whereby EUG and AST could enhance DOX cytotoxicity in MCF7 cells.MethodsCytotoxic activity of DOX alone and combined with either 1 mM EUG or 40 μM AST was performed using sulphorhodamine-B assay in MCF7 cells. Global histones acetylation and some immunological markers were investigated using ELISA, western blotting and quantitative RT-PCR techniques. Functional assay of multidrug resistance was performed using rhodamine 123 and Hoechst 3342 dyes. Flow cytometry with annexin V and propidium iodide were used to assess the change in cell cycle and apoptosis along with the expression of some differentiation, apoptosis and autophagy proteins.ResultsDOX alone resulted in concentration-dependent cytotoxicity with IC50 of 0.5 μM. Both EUG and AST significantly increased DOX cytotoxicity which is manifested as a significant decrease in DOX IC50 from 0.5 μM to 0.088 μM with EUG and to 0.06 μM with AST. Combinations of DOX with 1 mM EUG or 40 μM AST significantly increased the level of histones acetylation and histone acetyl transferase expression, while reduced the expression of aromatase and epidermal growth factor receptor (EGFR) when compared with 0.25 μM DOX alone. Also both combinations showed higher uptake of rhodamine but lower of Hoechst stains, along with increased the percentage of caspase 3, and decreased the expression of CK7 and LC3BI/II ratio. EUG combination induced IFγ but reduced TNFα causing shifting of cells from G2/M to S and G0/ G1 phases. Combination of DOX with EUG induced apoptosis through the higher BAX/ BCl2 ratio, while with AST was through the increase in caspase 8 expressions.ConclusionEUG and AST potentiated the anticancer activity of DOX through epigenetic histones acetylation along with the immunonomodulation of different apoptotic approaches in MCF7 cells.

Genome-wide identification of citrus histone acetyltransferase and deacetylase families and their expression in response to arbuscular mycorrhizal fungi and drought

ABSTRACT Histone acetyltransferase (HAT) and histone deacetylase (HDAC) family members control histone acetylation levels to regulate gene expression and play significant roles in microbe interactions and abioticstress responses. However, the HAT and HDAC family members in citrus have not yet been identified, and their responses to drought (abiotic stress) and arbuscular mycorrhizal fungi (AMF) colonization, remain unknown. In the present study, HAT and HDAC family genes were characterized in the citrus genome. A total of 14 CsHATs and 11 CsHDACs were identified in the citrus genome, of which 8 CsHATs and 7 CsHDACs showed syntenic relationships with Arabidopsis HATs and HDACs, respectively. Furthermore, the 14 CsHATs were classified into GNAT-MYST, TAFII250, MYST, CBP, and one citrus-unique family. The 11 CsHDACs were classified into SIR2, HD2, and RPD3/HDA1. Gene expression analysis showed AMF colonizationor drought induced the expression of CsHAT1, 2, 6, 7, 9, 11, 12, and 14, and repressed CsHDAC1, 2, 5, 6, 8, and 10. The regulation of HAT and HDAC expression was not always consistent with the cis-elements identified in their promoters. The present study offers useful insights into the citrus HAT and HDAC gene families and their expression in response to AMF colonization and drought stress.

Histone Deacetylase 11 Knockdown Blocks Larval Development and Metamorphosis in the Red Flour Beetle, Tribolium castaneum.

Post-translational modifications (PTM) such as methylation, acetylation, phosphorylation, and ubiquitination of histones and other proteins regulate expression of genes. The acetylation levels of these proteins are determined by the balance of expression of histone acetyltransferase (HATs) and histone deacetylases (HDACs). We recently reported that class I HDACs (HDAC1 and HDAC3) play important roles in juvenile hormone (JH) suppression of metamorphosis in the red flour beetle, Tribolium castaneum. Here, we report on the function of a single class IV HDAC member, HDAC11. Injection of dsRNA targeting T. castaneum HDAC11 gene into newly molted last instar larvae induced knockdown of the target gene and arrested larval development and prevented metamorphosis into the pupal stage. Dark melanized areas were detected in larvae that showed developmental arrest and mortality. Developmental expression studies showed an increase in HDAC11 mRNA levels beginning at the end of the penultimate larval stage. These higher levels were maintained during the final instar larval and pupal stages. A JH analog, hydroprene, suppressed HDAC11 expression in the larvae. Sequencing of RNA isolated from control and dsHDAC11 injected larvae identified several differentially expressed genes, including those involved in JH action, ecdysone response, and melanization. The acetylation levels of core histones showed an increase in TcA cells exposed to dsHDAC11. Also, an increase in histone H3 acetylation, specifically H3K9, H3K18 and H3K27, were detected in HDAC11 knockdown larvae. These studies report the function of HDAC11 in insects other than Drosophila for the first time and show that HDAC11 influences the acetylation levels of histones and expression of multiple genes involved in T. castaneum larval development.

Altered expression of norepinephrine transporter participate in hypertension and depression through regulated TNF-α and IL-6

ABSTRACTAim: We explored the role of histone modification in the association of depression-hypertension by comparing norepinephrine transporter (NET) gene levels in different depression-hypertensive patients. Then, we analyzed the expression of NET correlation with inflammatory cytokines to provide a new direction for detecting the association mechanism between depression and hypertension.Methods: NE expression levels in serum of diverse groups were detected by enzyme-linked immunosorbent assay. Then histone acetyltransferase (HAT), histone deacetylase (HDAC), H3K27ac, NET, TNF-α, and interleukin-6 (IL-6) were detected by western blot in nine female subjects in different depression and hypertension groups, and Chromatin immunoprecipitation-polymerase chain reaction (Chip-PCR) were used to confirm the degree of acetylation affecting on the transcription level of NET gene. Meanwhile, correlation between NET with TNF/IL-6 was analyzed by SPSS19.0 software program. Finally, Quantitative real-time polymerase chain reaction (qPCR) and western blot were used to detect TNF-α and IL-6 expression levels after NET overexpression or interference treatment in human umbilical vein endothelial cells and Neuro-2a cells.Results: The expression of HAT and H3K27ac had lower levels in D-H and nonD-H group than nonD-nonH group. The results showed that higher acetylation could promote expression of NET genes. Meanwhile, the expression of NET had a significant negative correlation with IL-6 (R = −0.933, p < 0.01) and tumor necrosis factor (TNF) (R = −0.817, p < 0.01) in subjects. In addition, the results confirmed that TNF-α and IL-6 mRNA and protein partial expressions could be inhibited by NET in both HUVECs and Neuronal cells (p < 0.01).Conclusion: In conclusion, differential expression of NET gene might function as an important factor in interaction between depression and hypertension by partially targeting TNF-α and IL-6.

Histone acetyltransferase 1 up regulates Bcl2L12 expression in nasopharyngeal cancer cells

The deregulation of Bcl2L12 expression in cancer has been recognized, but the causative factors are unknown. Histone acetyltransferases (HAT) play critical roles in the regulation gene transcription. This study tests a hypothesis that the aberrant activities of HAT induce deregulation of Bcl2L12 in nasopharyngeal cancer (NPC). In this study, human NPC tissues were collected from the clinic. The expression of Bcl2L12 and HATs in NPC cells was analyzed by real time RT-PCR and Western blotting. NPC cell apoptosis was analyzed by flow cytometry. The results showed that by screening the subtypes of HAT, the levels of HAT1 were uniquely higher in NPC as compared with non-cancer nasopharyngeal tissue. The levels of Bcl2L12 in NPC cells were positively correlated with HAT1. HAT1 involved in the STAT5 binding to the Bcl2L12 promoter. HAT1 increased the expression of Bcl2L12. Bcl2L12 mediated the effects of HAT1 on suppressing NPC cell apoptosis. Absorption of the HAT1 shRNA plasmid-carrying liposomes induced NPC cell apoptosis. In conclusion, inhibition of HAT1 can induce NPC cell apoptosis via increasing Bcl2L12 expression, which can be a potential therapy for NPC treatment.

The effects of acetaldehyde exposure on histone modifications and chromatin structure in human lung bronchial epithelial cells.

As the primary metabolite of alcohol and the most abundant carcinogen in tobacco smoke, acetaldehyde is linked to a number of human diseases associated with chronic alcohol consumption and smoking including cancers. In addition to direct DNA damage as a result of the formation of acetaldehyde-DNA adducts, acetaldehyde may also indirectly impact proper genome function through the formation of protein adducts. Histone proteins are the major component of the chromatin. Post-translational histone modifications (PTMs) are critically important for the maintenance of genetic and epigenetic stability. However, little is known about how acetaldehyde-histone adducts affect histone modifications and chromatin structure. The results of protein carbonyl assays suggest that acetaldehyde forms adducts with histone proteins in human bronchial epithelial BEAS-2B cells. The level of acetylation for N-terminal tails of cytosolic histones H3 and H4, an important modification for histone nuclear import and chromatin assembly, is significantly downregulated following acetaldehyde exposure in BEAS-2B cells, possibly due to the formation of histone adducts and/or the decrease in the expression of histone acetyltransferases. Notably, the level of nucleosomal histones in the chromatin fraction and at most of the genomic loci we tested are low in acetaldehyde-treated cells as compared with the control cells, which is suggestive of inhibition of chromatin assembly. Moreover, acetaldehyde exposure perturbs chromatin structure as evidenced by the increase in general chromatin accessibility and the decrease in nucleosome occupancy at genomic loci following acetaldehyde treatment. Our results indicate that regulation of histone modifications and chromatin accessibility may play important roles in acetaldehyde-induced pathogenesis. Environ. Mol. Mutagen. 59:375-385, 2018. © 2018 Wiley Periodicals, Inc.

NLRP3 inflammasome activation contributes to VSMC phenotypic transformation and proliferation in hypertension

Inflammation is involved in pathogenesis of hypertension. NLRP3 inflammasome activation is a powerful mediator of inflammatory response via caspase-1 activation. The present study was designed to determine the roles and mechanisms of NLRP3 inflammasome in phenotypic modulation and proliferation of vascular smooth muscle cells (VSMCs) in hypertension. Experiments were conducted in spontaneously hypertensive rats (SHR) and primary aortic VSMCs. NLRP3 inflammasome activation was observed in the media of aorta in SHR and in the VSMCs from SHR. Knockdown of NLRP3 inhibited inflammasome activation, VSMC phenotypic transformation and proliferation in SHR-derived VSMCs. Increased NFκB activation, histone acetylation and histone acetyltransferase expression were observed in SHR-derived VSMCs and in media of aorta in SHR. Chromatin immunoprecipitation analysis revealed the increased histone acetylation, p65-NFκB and Pol II occupancy at the NLRP3 promoter in vivo and in vitro. Inhibition of NFκB with BAY11-7082 or inhibition of histone acetyltransferase with curcumin prevented the NLRP3 inflammasome activation, VSMC phenotype switching and proliferation in VSMCs from SHR. Moreover, curcumin repressed NFκB activation. Silencing of NLRP3 gene ameliorated hypertension, vascular remodeling, NLRP3 inflammasome activation and phenotype switching in the aorta of SHR. These results indicate that NLRP3 inflammasome activation response to histone acetylation and NFκB activation contributes to VSMC phenotype switching and proliferation and vascular remodeling in hypertension.

Histone Deacetylase Is Required for GA-Induced Programmed Cell Death in Maize Aleurone Layers.

Recent discoveries have shown that epigenetic regulation is an integral part of phytohormone-mediated processes. The phytohormone gibberellin (GA) triggers a series of events in cereal aleurone cells that lead to programmed cell death (PCD), but the signaling cascade mediating GA-induced PCD in cereal aleurone layers remains largely unknown. Here, we showed that histone deacetylase (HDAC) activity gradually increased relative to histone acetyltransferase (HAT) activity, leading to a global decrease in histone H3 and H4 acetylation levels during PCD of maize (Zea mays) embryoless aleurone layers after 3 d of treatment with GA. HDAC inhibition prevented GA-induced PCD in embryoless aleurone cells, whereas HAT inhibition resulted in PCD even in the absence of GA. Hydrogen peroxide concentrations increased in GA- or HAT inhibitor-treated aleurone cells due to reduced levels of reactive oxygen species scavengers. Hydrogen peroxide-treated aleurone cells showed no changes in the activity or expression of HATs and HDACs. We show that it is possible to predict whether epigenetic modification enzymes serve as a regulator of the GA-triggered PCD signaling pathway in maize aleurone layers. Taken together, these findings reveal that HDAC activity is required for GA-induced PCD in maize aleurone layers and regulates PCD via the reactive oxygen species-mediated signal transduction pathway.

Differential Effects of Histone Acetyltransferase GCN5 or PCAF Knockdown on Urothelial Carcinoma Cells.

Disturbances in histone acetyltransferases (HATs) are common in cancers. In urothelial carcinoma (UC), p300 and CBP are often mutated, whereas the GNAT family HATs GCN5 and PCAF (General Control Nonderepressible 5, p300/CBP-Associated Factor) are often upregulated. Here, we explored the effects of specific siRNA-mediated knockdown of GCN5, PCAF or both in four UC cell lines (UCCs). Expression of various HATs and marker proteins was measured by qRT-PCR and western blot. Cellular effects of knockdowns were analyzed by flow cytometry and ATP-, caspase-, and colony forming-assays. GCN5 was regularly upregulated in UCCs, whereas PCAF was variable. Knockdown of GCN5 or both GNATs, but not of PCAF alone, diminished viability and inhibited clonogenic growth in 2/4 UCCs, inducing cell cycle changes and caspase-3/7 activity. PCAF knockdown elicited GCN5 mRNA upregulation. Double knockdown increased c-MYC and MDM2 (Mouse Double Minute 2) in most cell lines. In conclusion, GCN5 upregulation is especially common in UCCs. GCN5 knockdown impeded growth of specific UCCs, whereas PCAF knockdown elicited minor effects. The limited sensitivity towards GNAT knockdown and its variation between the cell lines might be due to compensatory effects including HAT, c-MYC and MDM2 upregulation. Our results predict that developing drugs targeting individual HATs for UC treatment may be challenging.

Compound 21 and Telmisartan combination mitigates type 2 diabetic nephropathy through amelioration of caspase mediated apoptosis

The current study aimed to understand the role of novel, highly selective, orally active, non-peptide Angiotensin II type 2 receptor (AT2R) agonist, Compound 21 and its potential additive effect with Telmisartan on apoptosis and underlying posttranslational modifications in a non-genetic murine model for type 2 diabetic nephropathy (T2DN). An experimental model for T2DN was developed by administering low dose Streptozotocin in high fat diet fed male Wistar rats, followed by their treatment with Telmisartan, C21 or their combination. Our results demonstrated that C21 and Telmisartan combination attenuated metabolic and renal dysfunction, renal morphological and micro-architectural aberrations and hemodynamic disturbances in type 2 diabetic rats. The anti-apoptotic and anti-inflammatory effects of Telmisartan were significantly accentuated by C21 indicated by expression of apoptotic markers (Parp1, Caspase 8, Caspase 7, cleaved PARP and cleaved Caspase 3) and NF-κB mediated inflammatory molecules like interleukin 6, tumour necrosis factor alpha; monocyte chemoattractant protein 1 and vascular cell adhesion molecule 1. C21 was found to improve Telmisartan mediated reversal of histone H3 acetylation at lysine 14 and 27 and expression of histone acetyl transferase, p300/CBP-associated factor also known to regulate NF-κB activity and DNA damage response. C21 in combination with Telmisartan markedly mitigates caspase mediated apoptosis and NF-κB signalling in T2D kidney, which could be partially attributed to its influence on PCAF mediated histone H3 acetylation. Hence further research should be done to develop this combination to treat T2DN.

Immunoexpression of HDAC1, HDAC2, and HAT1 in actinic cheilitis and lip squamous cell carcinoma.

Acetylation and deacetylation are the most studied covalent histone modifications resulting in transcriptional regulation with histone deacetylases (HDAC) and histone acetyltransferases (HAT) as the main associated enzymes. These enzymes overexpression induces abnormal transcription of key genes that regulate important cellular functions, such as proliferation, cell cycle regulation, and apoptosis. Thus, the expression of different HATs and HDACs has been evaluated in various cancers. To investigate HDAC1, HDAC2 and HAT1 expression in lip squamous cell carcinoma (LSCC) and actinic cheilitis (AC) and to demonstrate their correlation with DNA metyltransferases (DNMTs). Thirty cases of lip squamous cell carcinoma (LSCC), thirty cases of actinic cheilitis (AC), and 28 cases of non-neoplastic epithelium as control were selected for immunohistochemical investigation. Nuclear HDAC2 immunopositivity was significantly higher in AC (75.07%±29.70) when compared with LSCC (51.06%±39.02). HDAC1 and HAT1 nuclear immunostaining were higher in AC, with no statistical significance. When comparing data with our previous study, we found a positive correlation between HDAC1 X DNMT1/DNMT3b, HDAC2 X DNMT3b, and HAT1 X DNMT1/DNMT3b for certain studied groups. This study showed higher levels of nuclear HDAC2 immunopositivity in AC, possibly indicating that this enzyme plays a key role in lip photocarcinogenesis early stages.