The Experts below are selected from a list of 42852 Experts worldwide ranked by ideXlab platform
Edward Seto - One of the best experts on this subject based on the ideXlab platform.
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The Rpd3/Hda1 family of lysine deacetylases: from bacteria and yeast to mice and men
Nature Reviews Molecular Cell Biology, 2008Co-Authors: Xiang-jiao Yang, Edward SetoAbstract:Protein lysine deacetylases have a pivotal role in numerous biological processes and can be divided into the Rpd3/Hda1 and sirtuin families, each having members in diverse organisms including prokaryotes. In vertebrates, the Rpd3/Hda1 family contains 11 members, traditionally referred to as histone deacetylases (HDAC) 1–11, which are further grouped into classes I, II and IV. Whereas most class I HDACs are subunits of multiprotein nuclear complexes that are crucial for transcriptional repression and epigenetic landscaping, class II members regulate cytoplasmic processes or function as signal transducers that shuttle between the cytoplasm and the nucleus. Little is known about class IV HDAC11, although its evolutionary conservation implies a fundamental role in various organisms. In the past decade, protein Lys acetylation has emerged as a major post-translational modification that occurs even in bacteria. This modification not only regulates chromatin-templated nuclear processes, but also controls classical metabolism, cytoskeleton dynamics, apoptosis, protein folding and cellular signalling in the cytoplasm. Lys deacetylases, the enzymes that are responsible for reversing this modification, are divided into the Rpd3/Hda1 (or classical) and sirtuin families, with the classical family having 11 members in mammals. These members are referred to as histone deacetylases (HDAC) 1–11. HDAC1, HDAC2 and HDAC3 are deacetylase subunits of multiprotein complexes that are crucial for chromatin modification and epigenetic landscaping. These complexes comprise subunits that are required for interplay with other chromatin modifications such as DNA and histone methylation, as well as with ATP-dependent chromatin remodelling. HDAC4, HDAC5, HDAC7 and HDAC9 are novel signal transducers that are tightly regulated by phosphorylation-dependent nucleocytoplasmic trafficking. Conceptually, they are similar to the cytokine-stimulated STAT and TGFβ-regulated SMAD signal-responsive transcription factors. By binding to ubiquitin and deacetylating α-tubulin, cortactin and HSP90, HDAC6 regulates various cytoplasmic processes including cytoskeleton dynamics, ciliogenesis, aggresome formation, autophagy, nuclear receptor maturation and, possibly, endocytosis of Tyr kinase receptors. HDAC inhibitors are promising therapeutic agents for cancer and other major diseases, as evidenced by the recent approval of one such inhibitor for the treatment of cutaneous T-cell lymphoma. The Rpd3/Hda1 family of protein lysine deacetylases has numerous substrates and diverse functions. Whereas class I enzymes are multiprotein histone deacetylase complexes that are crucial for chromatin modification and transcriptional regulation, some class II enzymes function as signal transducers that are regulated by nucleocytoplasmic translocation.
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histone deacetylase 3 interacts with and deacetylates myocyte enhancer factor 2
Molecular and Cellular Biology, 2007Co-Authors: Serge Grégoire, Edward Seto, Lin Xiao, Xiaohong Zhang, Minghong Xu, Jiarong Li, Jiemin Wong, Xiang-jiao YangAbstract:The myocyte enhancer factor 2 (MEF2) family of transcription factors is not only important for controlling gene expression in normal cellular programs, like muscle differentiation, T-cell apoptosis, neuronal survival, and synaptic differentiation, but has also been linked to cardiac hypertrophy and other pathological conditions. Lysine acetylation has been shown to modulate MEF2 function, but it is not so clear which deacetylase(s) is involved. We report here that treatment of HEK293 cells with trichostatin A or nicotinamide upregulated MEF2D acetylation, suggesting that different deacetylases catalyze the deacetylation. Related to the trichostatin A sensitivity, histone deacetylase 4 (HDAC4) and HDAC5, two known partners of MEF2, exhibited little deacetylase activity towards MEF2D. In contrast, HDAC3 efficiently deacetylated MEF2D in vitro and in vivo. This was specific, since HDAC1, HDAC2, and HDAC8 failed to do so. While HDAC4, HDAC5, HDAC7, and HDAC9 are known to recognize primarily the MEF2-specific domain, we found that HDAC3 interacts directly with the MADS box. In addition, HDAC3 associated with the acetyltransferases p300 and p300/CBP-associated factor (PCAF) to reverse autoacetylation. Furthermore, the nuclear receptor corepressor SMRT (silencing mediator of retinoid acid and thyroid hormone receptor) stimulated the deacetylase activity of HDAC3 towards MEF2 and PCAF. Supporting the physical interaction and deacetylase activity, HDAC3 repressed MEF2-dependent transcription and inhibited myogenesis. These results reveal an unexpected role for HDAC3 and suggest a novel pathway through which MEF2 activity is controlled in vivo.
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Negative Regulation of Histone Deacetylase 8 Activity by Cyclic AMP-Dependent Protein Kinase A
Molecular and cellular biology, 2004Co-Authors: Heehyoung Lee, Natalie Rezai-zadeh, Edward SetoAbstract:In eukaryotes, genomic DNA is wrapped tightly around core histones to form nucleosomes, the fundamental building blocks of chromatin. Nucleosomes, once regarded as inert structural particles, are now considered integral and dynamic components of the machineries responsible for gene regulation. Many different enzymes and protein complexes are known to bring about changes in the state of chromatin by numerous mechanisms, with resultant effects on gene expression. One class of complexes alters DNA packaging (remodels chromatin) in an ATP-dependent manner (4, 29). Another class of chromatin-altering factors acts by covalently modifying histone proteins (5). These modifications include acetylation, phosphorylation, methylation, ubiquitination, and ADP-ribosylation. The best-characterized posttranslational histone modification is acetylation, which is catalyzed by histone acetyltransferase (HAT) enzymes. Histone acetylation is a reversible process that is regulated by the opposing activities of HATs and histone deacetylases (HDACs). Generally, hyperacetylation of histones results in transcriptional activation whereas deacetylation correlates with transcriptional silencing. Consistent with this generalization, transcriptional activators are often associated with HAT activity whereas HDACs frequently form complexes with transcriptional repressors (24). Therefore, these two regulatory processes work in harmony to achieve appropriate levels of gene expression. Several oncogenes and tumor suppressors (pRb, BRCA-1, BRCA-2, PML-RAR, and a zinc finger protein mutated in leukemia) have been shown to be associated with HATs or HDACs (41). HDAC proteins are vital regulators of fundamental cellular events, including cell cycle progression, differentiation, and tumorigenesis (37, 45). A small-molecule inhibitor of HDAC, trichostatin A (TSA), arrests mammalian cells in both G1 and G2 (31, 44), while overexpression of HDAC1 in mouse cells reduces their growth rate by lengthening the duration of G2 and M (3). TSA induces terminal differentiation of mouse erythroleukemia cells and apoptosis of lymphoid and colorectal cancer cells. In addition, TSA treatment of cells expressing the PML zinc finger protein derepresses transcription and allows cells to differentiate normally (18). With this precedent, HDAC inhibitors are being actively explored as potential agents for the treatment of certain forms of cancer (22, 23, 27). The human HDACs are organized into three different classes based on their similarity to yeast HDAC proteins (37, 45). Class I enzymes are ubiquitously expressed and include HDAC1, -2, -3, and -8, which are homologous to the yeast RPD3 protein. Class II includes HDAC4, -5, -6, -7, -9, and -10, which are similar to yeast HDA1 and are expressed in a tissue-specific manner. The Sir2-like class III HDACs, including SIRT1 to -7, require NAD+ for enzymatic activity. The most recent addition to the human HDAC family, HDAC11, uniquely shares sequence homology with the catalytic regions of both class I and II HDAC enzymes (15). By far, the most frequently studied and best-characterized human HDACs are HDAC1 and HDAC2. Early studies elegantly demonstrated that HDAC1 and HDAC2 were associated with proteins that modulate their enzymatic activity and their recruitment to genomic regions. Three large multisubunit protein complexes, called Sin3, NuRD/Mi2, and CoREST, contain HDAC1 and HDAC2 (1, 17, 21, 25, 30, 38, 42, 46-48). In addition to complex formation, recent studies have revealed that the activity of class I HDACs is regulated by posttranslational modifications. For example, HDAC1 is a substrate for SUMO-1 (small ubiquitin-related modifier 1), and mutations of the target residues decrease transcriptional repression without affecting the ability of HDAC1 to associate with mSin3 (10). In addition, like those of many class II HDACs, the actions of HDAC1 and HDAC2 are regulated by phosphorylation. Phosphorylation of HDAC1 by protein kinase CK2 alters HDAC1's enzymatic activity and its capacity to form protein complexes (7, 13, 33). Similarly, phosphorylation of HDAC2 by protein kinase CK2 is essential for HDAC2's deacetylase activity and its association with mSin3, Mi2, Sp1, and Sp3 (36, 39). Our previous studies showed that, like HDAC1 and HDAC2, HDAC3 also is phosphorylated by protein kinase CK2 (39). Surprisingly, unlike other members of the class I HDAC family, HDAC8 is not phosphorylated by protein kinase CK2 (39). However, it is possible that kinases other than protein kinase CK2 phosphorylate HDAC8 and modulate its activity. A complete understanding of how phosphorylation regulates the actions of class I HDACs requires a thorough determination of whether HDAC8 is a phosphoprotein and, if so, what kinase is responsible and what the functional consequences are. HDAC8 cDNA was identified initially by three independent groups using sequence homology database searches with class I HDAC proteins (6, 20, 40). The HDAC8 gene encodes a 377-amino-acid protein with a predicted molecular mass of 45 kDa and is located on the X chromosome at position q21.2-q21.3 or q13 (6, 40). Protein sequence comparisons of HDAC8 reveal a 37% similarity to HDAC1. In Northern blot analyses, the size of HDAC8 mRNA is between 1.7 and 2.4 kb, and HDAC8 mRNA is expressed in multiple human organs, including the liver, heart, brain, lung, pancreas, placenta, prostate, and kidney. Consistent with the presence of a stretch of basic residues that could serve as a nuclear localization signal, HDAC8 is predominantly located in the nucleus. A recent report suggests that the inv (16) fusion protein specifically associates with HDAC8 (11). Although sequence analysis of HDAC8 revealed consensus phosphorylation sites for protein kinase A (PKA) and protein kinase CK2, our previous studies showed that HDAC8 was not phosphorylated by protein kinase CK2 in vitro (39). In the present study, we show that HDAC8 is phosphorylated instead by PKA both in vitro and in vivo. Most interestingly, phosphorylation of HDAC8 by PKA inhibits its deacetylase activity, which results in the hyperacetylation of histones H3 and H4. Thus, our findings uncover a novel mechanism of class I HDAC regulation.
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functional domains of histone deacetylase 3
Journal of Biological Chemistry, 2002Co-Authors: Wenming Yang, Shihchang Tsai, Gyorgy Fejer, Edward SetoAbstract:Abstract Post-translational modifications of histones, in general, and acetylation/deacetylation, in particular, can dramatically alter gene expression in eukaryotic cells. In humans, four highly homologous class I HDAC enzymes (HDAC1, HDAC2, HDAC3, and HDAC8) have been identified to date. Although HDAC3 shares some structural and functional similarities with other class I HDACs, it exists in multisubunit complexes separate and different from other known HDAC complexes, implying that individual HDACs might function in a distinct manner. In this current study, to understand further the cellular function of HDAC3 and to uncover possible unique roles this protein may have in gene regulation, we performed a detailed analysis of HDAC3 using deletion mutations. Surprisingly, we found that the non-conserved C-terminal region of HDAC3 is required for both deacetylase and transcriptional repression activity. In addition, we discovered that the central portion of the HDAC3 protein possesses a nuclear export signal, whereas the C-terminal part of HDAC3 contributes to the protein's localization in the nucleus. Finally, we found that HDAC3 forms oligomers in vitro and in vivo and that the N-terminal portion of HDAC3 is necessary for this property. These data indicate that HDAC3 comprises separate, non-overlapping domains that contribute to the unique properties and function of this protein.
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the histone deacetylase 3 complex contains nuclear receptor corepressors
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Valentina Perissi, Lena Staszewski, Wenming Yang, Anna Krones, Christopher K Glass, Michael G Rosenfeld, Edward SetoAbstract:Acetylation and deacetylation of nucleosomal histones have profound effects on gene transcription in all eukaryotes. In humans, three highly homologous class I and four class II histone deacetylase (HDAC) enzymes have been identified to date. The class I deacetylases HDAC1 and HDAC2 are components of multisubunit complexes, one of which could associate with the nuclear hormone receptor corepressor, N-CoR. N-CoR also interacts with class II deacetylases HDAC4, HDAC5, and HDAC7. In comparison with HDAC1 and HDAC2, HDAC3 remains relatively uncharacterized, and very few proteins have been shown to interact with HDAC3. Using an affinity purification approach, we isolated an enzymatically active HDAC3 complex that contained members of the nuclear receptor corepressor family. Deletion analysis of N-CoR revealed that HDAC3 binds multiple N-CoR regions in vitro and that all of these regions are required for maximal binding in vivo. The N-CoR domains that interact with HDAC3 are distinct from those that bind other HDACs. Transient overexpression of HDAC3 and microinjection of Abs against HDAC3 showed that a component of transcriptional repression mediated by N-CoR depends on HDAC3. Interestingly, data suggest that interaction with a region of N-CoR augments the deacetylase activity of HDAC3. These results provide a possible molecular mechanism for HDAC3 regulation and argue that N-CoR is a platform in which distinct domains can interact with most of the known HDACs.
Eric N Olson - One of the best experts on this subject based on the ideXlab platform.
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specific control of pancreatic endocrine β and δ cell mass by class iia histone deacetylases HDAC4 hdac5 and hdac9
Diabetes, 2011Co-Authors: Olivia Lenoir, Eric N Olson, Antonello Mai, Kathleen Flosseau, Feng Xia, B Blondeau, Rhonda Basselduby, Philippe Ravassard, Cecile Haumaitre, Raphael ScharfmannAbstract:OBJECTIVE Class IIa histone deacetylases (HDACs) belong to a large family of enzymes involved in protein deacetylation and play a role in regulating gene expression and cell differentiation. Previously, we showed that HDAC inhibitors modify the timing and determination of pancreatic cell fate. The aim of this study was to determine the role of class IIa HDACs in pancreas development. RESEARCH DESIGN AND METHODS We took a genetic approach and analyzed the pancreatic phenotype of mice lacking HDAC4, -5, and -9. We also developed a novel method of lentiviral infection of pancreatic explants and performed gain-of-function experiments. RESULTS We show that class IIa HDAC4, -5, and -9 have an unexpected restricted expression in the endocrine β- and δ-cells of the pancreas. Analyses of the pancreas of class IIa HDAC mutant mice revealed an increased pool of insulin-producing β-cells in Hdac5 −/− and Hdac9 −/− mice and an increased pool of somatostatin-producing δ-cells in HDAC4 −/− and Hdac5 −/− mice. Conversely, HDAC4 and HDAC5 overexpression showed a decreased pool of insulin-producing β-cells and somatostatin-producing δ-cells. Finally, treatment of pancreatic explants with the selective class IIa HDAC inhibitor MC1568 enhances expression of Pax4 , a key factor required for proper β-and δ-cell differentiation and amplifies endocrine β- and δ-cells. CONCLUSIONS We conclude that HDAC4, -5, and -9 are key regulators to control the pancreatic β/δ-cell lineage. These results highlight the epigenetic mechanisms underlying the regulation of endocrine cell development and suggest new strategies for β-cell differentiation-based therapies.
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The many roles of histone deacetylases in development and physiology: implications for disease and therapy
Nature Reviews Genetics, 2009Co-Authors: Michael Haberland, Rusty L. Montgomery, Eric N OlsonAbstract:Histone deacetylases (HDACs) are part of a vast family of enzymes that have crucial roles in numerous biological processes, largely through their repressive influence on transcription. The expression of many HDAC isoforms in eukaryotic cells raises questions about their possible specificity or redundancy, and whether they control global or specific programmes of gene expression. Recent analyses of HDAC knockout mice have revealed highly specific functions of individual HDACs in development and disease. Mutant mice lacking individual HDACs are a powerful tool for defining the functions of HDACs in vivo and the molecular targets of HDAC inhibitors in disease. Mammalian genomes encode eleven proteins of the classical histone deacetylase (HDAC) family. They are numbered HDAC1 to HDAC11 and can be classified into four distinct groups (class I, IIa, IIb and IV), which differ in structure, enzymatic function, subcellular localization and expression patterns. Class I HDACs (HDAC1, 2, 3 and 8) are ubiquitously expressed highly active enzymes which localize predominantly to the nucleus. Genetic deletion is lethal in all cases with phenotypes ranging from gastrulation defects to cardiovascular malformation. Class IIa HDACs (HDAC4, 5, 7 and 9) are signal-responsive transcriptional repressors that interact with the transcription factor myocyte enhancer factor 2 (MEF2) and have minimal enzymatic activity towards classical histone substrates, owing to a conserved amino-acid change in the catalytic pocket. Genetic deletion leads to superactivation of MEF2 with resulting phenotypes in the heart, skeleton and endothelial cells. HDAC6 and HDAC10 form the class IIb HDAC family, with HDAC6 being the main cytoplasmic deacetylase in mammalian cells. HDAC6 has numerous targets, including tubulin and intracellular chaperones. Genetic deletion of HDAC6 does not lead to an overt phenotype. HDAC11 is the sole member of the class IV HDACs. Little is known about its function. Genetic deletion of individual HDACs leads to surprisingly specific phenotypes. Analysis of the resulting mutants has shown that HDACs control specific gene expression programmes. One major challenge for the future will be to decipher the role of individual HDACs in specific disease processes and to develop isoform-specific inhibitors. It is expected that this will lead to a broader therapeutic window of HDAC inhibitors, and possibly to a clinical application in non-oncological disease states. The expression of many histone deacetylase (HDAC) isoforms in eukaryotic cells raises questions regarding their specificity and the programmes of gene expression that they control. HDAC knockout mice are a powerful tool for addressing these questions and have revealed that individual HDACs have specific functions in development and disease.
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histone deacetylase 5 acquires calcium calmodulin dependent kinase ii responsiveness by oligomerization with histone deacetylase 4
Molecular and Cellular Biology, 2008Co-Authors: Johannes Backs, Thea Backs, Timothy A Mckinsey, Svetlana Bezprozvannaya, Eric N OlsonAbstract:Calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylates histone deacetylase 4 (HDAC4), a class IIa HDAC, resulting in the cytosolic accumulation of HDAC4 and the derepression of the transcription factor myocyte enhancer factor 2. Phosphorylation by CaMKII requires docking of the kinase to a specific domain of HDAC4 not present in other HDACs. Paradoxically, however, CaMKII signaling can also promote the nuclear export of other class IIa HDACs, such as HDAC5. Here, we show that HDAC4 and HDAC5 form homo- and hetero-oligomers via a conserved coiled-coil domain near their amino termini. Whereas HDAC5 alone is unresponsive to CaMKII, it becomes responsive to CaMKII in the presence of HDAC4. The acquisition of CaMKII responsiveness by HDAC5 is mediated by HDAC5's direct association with HDAC4 and can occur by phosphorylation of HDAC4 or by transphosphorylation by CaMKII bound to HDAC4. Thus, HDAC4 integrates upstream Ca2+-dependent signals via its association with CaMKII and transmits these signals to HDAC5 by protein-protein interactions. We conclude that HDAC4 represents a point of convergence for CaMKII signaling to downstream HDAC-regulated genes, and we suggest that modulation of the interaction of CaMKII and HDAC4 represents a means of regulating CaMKII-dependent gene programs.
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Histone Deacetylase 5 Acquires Calcium/Calmodulin-Dependent Kinase II Responsiveness by Oligomerization with Histone Deacetylase 4
Molecular and Cellular Biology, 2008Co-Authors: Johannes Backs, Thea Backs, Timothy A Mckinsey, Svetlana Bezprozvannaya, Eric N OlsonAbstract:Calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylates histone deacetylase 4 (HDAC4), a class IIa HDAC, resulting in the cytosolic accumulation of HDAC4 and the derepression of the transcription factor myocyte enhancer factor 2. Phosphorylation by CaMKII requires docking of the kinase to a specific domain of HDAC4 not present in other HDACs. Paradoxically, however, CaMKII signaling can also promote the nuclear export of other class IIa HDACs, such as HDAC5. Here, we show that HDAC4 and HDAC5 form homo- and hetero-oligomers via a conserved coiled-coil domain near their amino termini. Whereas HDAC5 alone is unresponsive to CaMKII, it becomes responsive to CaMKII in the presence of HDAC4. The acquisition of CaMKII responsiveness by HDAC5 is mediated by HDAC5's direct association with HDAC4 and can occur by phosphorylation of HDAC4 or by transphosphorylation by CaMKII bound to HDAC4. Thus, HDAC4 integrates upstream Ca2+-dependent signals via its association with CaMKII and transmits these signals to HDAC5 by protein-protein interactions. We conclude that HDAC4 represents a point of convergence for CaMKII signaling to downstream HDAC-regulated genes, and we suggest that modulation of the interaction of CaMKII and HDAC4 represents a means of regulating CaMKII-dependent gene programs.
David Waltregny - One of the best experts on this subject based on the ideXlab platform.
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histone deacetylase 4 is required for tgfβ1 induced myofibroblastic differentiation
Biochimica et Biophysica Acta, 2007Co-Authors: Wendy Glenisson, Vincenzo Castronovo, David WaltregnyAbstract:Abstract Transforming Growth Factor β1 (TGFβ1) is a crucial cytokine triggering myofibroblastic (MF) differentiation, a process involved in tissue healing as well as in pathologic conditions such as fibrosis and cancer. Together with cell shape modifications, TGFβ1-mediated differentiation of fibroblasts into myofibroblasts is characteristically associated with the neo-expression of smooth muscle α-actin (α-SMA), a cytoskeletal protein that enhances their contractile activity. Several cellular differentiation programs have been linked to epigenetic regulation of gene expression, including gene methylation and histone acetylation. Herein, we sought to investigate the role of histone deacetylases (HDAC) in TGFβ1-induced MF differentiation. We found that TSA, a global inhibitor of class I and class II HDACs, prevented α-SMA transcript and protein expression and morphological changes mediated by TGFβ1 in cultured human skin fibroblasts. In order to identify the HDAC(s) participating in MF differentiation, the impact of specific HDAC silencing (HDAC1 through HDAC8) using RNA interference was investigated in fibroblasts exposed to TGFβ1. Among the eight HDACs tested, silencing of HDAC4, HDAC6, and HDAC8 expression impaired TGFβ1-induced α-SMA expression. HDAC4 silencing most efficiently abrogated α-SMA expression and also prevented TGFs1-mediated morphological changes. Forced down-regulation of HDAC4 stimulated the expression of 5′-TG-3′-Interacting Factor (TGIF) and TGIF2 homeoproteins, two known endogenous repressors of the TGFβ signaling pathway, but not of the inhibitory Smad7. Collectively, these data suggest that HDAC4 is an essential epigenetic regulator of MF differentiation and unveil HDAC4 as a potential target for treating MF-related disorders.
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histone deacetylase hdac8 associates with smooth muscle alpha actin and is essential for smooth muscle cell contractility
The FASEB Journal, 2005Co-Authors: David Waltregny, Wendy Glenisson, Siv Ly Tran, Brian J North, Eric Verdin, Alain Colige, Vincent CastronovoAbstract:Although originally characterized as nuclear enzymes controlling the stability of nucleosomes, histone deacetylases (HDACs) may also exert their activity within the cytosol. Recently, we have demonstrated that HDAC8, a class I HDAC, is a novel, prominently cytosolic marker of smooth muscle differentiation. As HDAC8 displays a striking stress fiber-like pattern of distribution and is coexpressed in vivo with smooth muscle alpha-actin (alpha-SMA) and smooth muscle myosin heavy chain, we have explored the possible participation of this HDAC in smooth muscle cytoskeleton regulation. Cell fractionation assays performed with primary human smooth muscle cells (HSMCs) showed that HDAC8, in contrast to HDAC1 and HDAC3, was enriched in cytoskeleton-bound protein fractions and insoluble cell pellets, suggesting an association of HDAC8 with the cystoskeleton. Coimmunoprecipitation experiments using HSMCs, NIH-3T3 cells, and human prostate tissue lysates further demonstrated that HDAC8 associates with alpha-SMA but not with beta-actin. HDAC8 silencing through RNA interference strongly reduced the capacity of HSMCs to contract collagen lattices. Mock transfections had no effect on HSMC contractily, and transfections with small interfering RNAs (siRNAs) specific for HDAC6, a cytosolic HDAC that functions as an alpha-tubulin deacetylase, resulted in a weak contraction inhibition. Although mock- and HDAC6 siRNA-transfected HSMCs showed no noticeable morphological changes, HDAC8 siRNA-transfected HSMCs displayed a size reduction with diminished cell spreading after replating. Altogether, our findings indicate that HDAC8 associates with the smooth muscle actin cytoskeleton and may regulate the contractile capacity of smooth muscle cells.
Holger Gohlke - One of the best experts on this subject based on the ideXlab platform.
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Effects of novel HDAC inhibitors on urothelial carcinoma cells
Clinical Epigenetics, 2018Co-Authors: Aline Kaletsch, Maria Pinkerneil, Michèle J. Hoffmann, Ananda A. Jaguva Vasudevan, Chenyin Wang, Finn K. Hansen, Constanze Wiek, Helmut Hanenberg, Christoph Gertzen, Holger GohlkeAbstract:Background Histone deacetylase inhibitors (HDACi) are promising anti-cancer drugs that could also be employed for urothelial carcinoma (UC) therapy. It is unclear, however, whether inhibition of all 11 zinc-dependent HDACs or of individual enzymes is more efficacious and specific. Here, we investigated the novel HDACi 19i (LMK235) with presumed preferential activity against class IIA HDAC4/5 in comparison to the pan-HDACi vorinostat (SAHA) and the HDAC4-specific HDACi TMP269 in UC cell lines with basal expression of HDAC4 and characterized two HDAC4-overexpressing UC cell lines. Methods Cytotoxic concentrations 50% (CC_50s) for HDACi were determined by MTT assay and high-content analysis-based fluorescent live/dead assay in UC cell lines with different expression of HDAC4 and as well as in normal urothelial cell cultures, HBLAK and HEK-293 cell lines. Effects of HDACis were analyzed by flow cytometry; molecular changes were followed by qRT-PCR and Western blots. UC lines overexpressing HDAC4 were established by lentiviral transduction. Inhibitor activity profiles of HDACi were obtained by current state in vitro assays, and docking analysis was performed using an updated crystal structure of HDAC4. Results In UC cell lines, 19i CC_50s ranged around 1 μM; control lines were similarly or less sensitive. Like SAHA, 19i increased the G2/M-fraction, disturbed mitosis, and elicited apoptosis or in some cells senescence. Thymidylate synthase expression was diminished, and p21^CIP1 was induced; global histone acetylation and α-tubulin acetylation also increased. In most cell lines, 19i as well as SAHA induced HDAC5 and HDAC4 mRNAs while rather repressing HDAC7. UC cell lines overexpressing HDAC4 were not significantly less sensitive to 19i. Reevaluation of the in vitro HDAC isoenzyme activity inhibition profile of 19i and its docking to HDAC4 using current assays suggested rather low activity against class IIA HDACs. The specific class IIA HDAC inhibitor TMP269 impeded proliferation of UC cell lines only at concentrations > 10 μM. Conclusions Anti-neoplastic effects of 19i on UC cells appear to be exerted by targeting class I HDACs. In fact, HDAC4 may rather impede UC growth. Our results suggest that targeting of class IIA HDACs 4/5 may not be optimal for UC therapy. Moreover, our investigation provides further evidence for cross-regulation of class IIA HDACs by class I HDACs.
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histone deacetylase hdac inhibitors with a novel connecting unit linker region reveal a selectivity profile for HDAC4 and hdac5 with improved activity against chemoresistant cancer cells
Journal of Medicinal Chemistry, 2013Co-Authors: Linda Marek, Finn K. Hansen, Holger Gohlke, Alexandra Hamacher, Krystina Kuna, Matthias U Kassack, Thomas KurzAbstract:The synthesis and biological evaluation of new potent hydroxamate-based HDAC inhibitors with a novel alkoxyamide connecting unit linker region are described. Biological evaluation includes MTT and cellular HDAC assays on sensitive and chemoresistant cancer cell lines as well as HDAC profiling of selected compounds. Compound 19i (LMK235) (N-((6-(hydroxyamino)-6-oxohexyl)oxy)-3,5-dimethylbenzamide) showed similar effects compared to vorinostat on inhibition of cellular HDACs in a pan-HDAC assay but enhanced cytotoxic effects against the human cancer cell lines A2780, Cal27, Kyse510, and MDA-MB231. Subsequent HDAC profiling yielded a novel HDAC isoform selectivity profile of 19i in comparison to vorinostat or trichostatin A (TSA). 19i shows nanomolar inhibition of HDAC4 and HDAC5, whereas vorinostat and TSA inhibit HDAC4 and HDAC5 in the higher micromolar range.
Vincent Castronovo - One of the best experts on this subject based on the ideXlab platform.
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histone deacetylase hdac8 associates with smooth muscle alpha actin and is essential for smooth muscle cell contractility
The FASEB Journal, 2005Co-Authors: David Waltregny, Wendy Glenisson, Siv Ly Tran, Brian J North, Eric Verdin, Alain Colige, Vincent CastronovoAbstract:Although originally characterized as nuclear enzymes controlling the stability of nucleosomes, histone deacetylases (HDACs) may also exert their activity within the cytosol. Recently, we have demonstrated that HDAC8, a class I HDAC, is a novel, prominently cytosolic marker of smooth muscle differentiation. As HDAC8 displays a striking stress fiber-like pattern of distribution and is coexpressed in vivo with smooth muscle alpha-actin (alpha-SMA) and smooth muscle myosin heavy chain, we have explored the possible participation of this HDAC in smooth muscle cytoskeleton regulation. Cell fractionation assays performed with primary human smooth muscle cells (HSMCs) showed that HDAC8, in contrast to HDAC1 and HDAC3, was enriched in cytoskeleton-bound protein fractions and insoluble cell pellets, suggesting an association of HDAC8 with the cystoskeleton. Coimmunoprecipitation experiments using HSMCs, NIH-3T3 cells, and human prostate tissue lysates further demonstrated that HDAC8 associates with alpha-SMA but not with beta-actin. HDAC8 silencing through RNA interference strongly reduced the capacity of HSMCs to contract collagen lattices. Mock transfections had no effect on HSMC contractily, and transfections with small interfering RNAs (siRNAs) specific for HDAC6, a cytosolic HDAC that functions as an alpha-tubulin deacetylase, resulted in a weak contraction inhibition. Although mock- and HDAC6 siRNA-transfected HSMCs showed no noticeable morphological changes, HDAC8 siRNA-transfected HSMCs displayed a size reduction with diminished cell spreading after replating. Altogether, our findings indicate that HDAC8 associates with the smooth muscle actin cytoskeleton and may regulate the contractile capacity of smooth muscle cells.
