Role Of Histone Deacetylases Research Articles

Role of histone deacetylases in pancreas: Implications for pathogenesis and therapy.

In the last years, our knowledge of the pathogenesis in acute and chronic pancreatitis (AP/CP) as well as in pancreatic cancerogenesis has significantly diversified. Nevertheless, the medicinal therapeutic options are still limited and therapeutic success and patient outcome are poor. Epigenetic deregulation of gene expression is known to contribute to development and progression of AP and CP as well as of pancreatic cancer. Therefore, the selective inhibition of aberrantly active epigenetic regulators can be an effective option for future therapies. Histone deacetylases (HDACs) are enzymes that remove an acetyl group from histone tails, thereby causing chromatin compaction and repression of transcription. In this review we present an overview of the currently available literature addressing the role of HDACs in the pancreas and in pancreatic diseases. In pancreatic cancerogenesis, HDACs play a role in the important process of epithelial-mesenchymal-transition, ubiquitin-proteasome pathway and, hypoxia-inducible-factor-1-angiogenesis. Finally, we focus on HDACs as potential therapeutic targets by summarizing currently available histone deacetylase inhibitors.

The Role of Histone Deacetylases in Glucose Metabolism: a Mini- Review

Histone deacetylases (HDACs) and histone acetyltransferases (HATs) maintain the balance of histone acetylation, and play important role in chromosome modification and gene expression. Histone deacetylases have been identified to modify acetylation of proteins other than histones and inhibit gene expression. Here we summarize the functions of histone deacetylases in glycometabolism including the expression of histone deacetylases in different energy conditions, effects of histone deacetylases on islet development, glucose uptake in skeletal muscle, hepatic gluconeogenesis as well as the role of histone deacetylases inhibitors in glycometabolism. Modulation of histone deacetylases provides an alternative opportunity of a therapy for both type 1 and type 2 diabetes.

Histone Deacetylase 11 (HDAC11) As a Novel Transcriptional Regulator of C/EBP-β, in Immature Myeloid Cell to Myeloid Derived Suppressor Cell Transition

In normal myelopoiesis, immature myeloid cells (IMCs) differentiate into macrophages, dendritic cells, and neutrophils. However, in pathological conditions such as in cancer, these immature cells differentiate into myeloid derived suppressor cells (MDSCs). Transcription factor CCAAT-enhancer-binding protein beta (C/EBP-β) plays a crucial role in the accumulation of MDSCs in several pathological conditions. Of note, mice lacking C/EBP-β in the bone marrow compartment lose the ability to differentiate IMCs into pathologically active MDSCs2.In contrast, up-regulation of C/EBP-β can partly induce MDSC expansion through a mechanism involving the STAT3 pathway3.Epigenetic changes, such as histone acetylation status, have been recently shown to modulate the regulatory function of MDSCs4. However, the epigenetic mechanism(s) involved in regulation of C/EBP-β gene expression in MDSCs are poorly understood. Here we show for the first time that among all the HDACs known, HDAC11, the newest member of this family of enzymes, is recruited to the C/EBP-β gene promoter region of primary myeloid cells isolated from C57BL/6 mice. Such a finding led us to explore the functional consequences of disrupting HDAC11 in myeloid cells. First, we observed a markedly higher expression of C/EBP-β mRNA (194 fold difference) in the CD11b+/Ly6G+ granulocytic compartment and a 6.7 fold difference in the CD11b+/Ly6C+monocytic compartments of HDAC11KO mice relative to control wild type mice. Second, MDSCs from HDAC11 KO mice display a higher suppressive phenotype and mechanistically we have found that they have increased expression of the immunosuppressive STAT3/IL10 axis. Third, inoculation of EL4 tumor cells into HDAC11KO mice and controls resulted in a higher expansion capacity of splenic MDSCs in mice devoid of HDAC11. Such an effect was associated with a more rapid tumor growth in HDAC11KO mice as compared to WT mice. Similar aggressive tumor growth was also observed in HDAC11 myeloid conditional KO mice (LyZ-Cre-HDAC11KO).Taken together, we have uncovered a previously unknown role for HDAC11 as a transcriptional regulator of C/EBP-β in MDSCs. Indeed, in the absence of this epigenetic checkpoint of C/EBP-β gene expression, the fully suppressive potential of MDSCs was fully unleashed. A better understanding of this novel role of HDAC11 in myeloid biology will ultimately lead to targeted epigenetic therapies to manipulate the suppressive abilities of these immunoregulatory cells.1. Hirai H, Zhang P, Dayaram T, et al. C/EBPbeta is required for 'emergency’ granulopoiesis. Nat Immunol 2006; 7(7): 732-9.2. Marigo I, Bosio E, Solito S, et al. Tumor-induced tolerance and immune suppression depend on the C/EBPbeta transcription factor. Immunity 2010; 32(6): 790-802.3. Condamine T, Gabrilovich DI. Molecular mechanisms regulating myeloid-derived suppressor cell differentiation and function. Trends Immunol 2011; 32(1): 19-25.4. Youn JI, Kumar V, Collazo M, et al. Epigenetic silencing of retinoblastoma gene regulates pathologic differentiation of myeloid cells in cancer. Nat Immunol 2013; 14(3): 211-20. DisclosuresNo relevant conflicts of interest to declare.

Selective Inhibition of HDAC6 Decreases Viability of Cutaneous T-Cell Lymphoma and Improves Immune Recognition

Cutaneous T-cell lymphoma (CTCL) includes a spectrum of non-Hodgkin’s T-cell lymphomas. While most patients with CTCL experience non-life threatening skin symptoms, those who do progress to later stages of the disease may develop serious complications. For patients with tumor stage or lymph node involvement there is a significant decline in treatment response & few treatment options are available. Current available therapeutic options include the use of histone deacetylase (HDAC) inhibitors as Romidepsin, Panobinostat and Vorinostat. However, their mechanism of action is still unknown. The role of histone deacetylases (HDACs) in cell biology, initially limited to their effects upon histones, now encompasses more complex regulatory functions that are dependent on their tissue expression, cellular compartment distribution, pathophysiological conditions and stage of cellular differentiation. Although major advances have been made in understanding the role of specific HDACs in cell proliferation and the survival of cancer cells, their individual participation in specific intracellular pathways is not completely understood. Here we present data demonstrating the changes in several immune-related pathways in two CTCL cell lines after exposure to both pan-HDAC inhibitors and selective HDAC6 inhibitors.We compared the pharmacological effects of the pan-HDAC inhibitor LBH589 (Panbinostat), the class I selective Romidepsin, and the selective HDAC6 inhibitors such as TubastatinA and NexturstatB, on two CTCL cell lines (HuT78, HuT102). Our findings thus far demonstrate the following: First, we observed a marked inhibition of proliferation capacity of both cell lines when treated with either pan-HDACi or the more selective HDAC6 inhibitors. However, the selective HDAC6 inhibitors showed less cytotoxicity. Second, we observed important changes in the expression of the co-inhibitory molecules, such as PD-L1. Given our results, we conclude that the selective targeting of HDAC6 could recapitulate the anti-tumor effects of pan-HDAC inhibitors without having the non-target cytotoxic effects often encountered when using pan-HDAC inhibitors. DisclosuresNo relevant conflicts of interest to declare.

Regulation of neuronal gene expression and survival by basal NMDA receptor activity: a role for histone deacetylase 4.

Neuronal gene expression is modulated by activity via calcium-permeable receptors such as NMDA receptors (NMDARs). While gene expression changes downstream of evoked NMDAR activity have been well studied, much less is known about gene expression changes that occur under conditions of basal neuronal activity. In mouse dissociated hippocampal neuronal cultures, we found that a broad NMDAR antagonist, AP5, induced robust gene expression changes under basal activity, but subtype-specific antagonists did not. While some of the gene expression changes are also known to be downstream of stimulated NMDAR activity, others appear specific to basal NMDAR activity. The genes altered by AP5 treatment of basal cultures were enriched for pathways related to class IIa histone deacetylases (HDACs), apoptosis, and synapse-related signaling. Specifically, AP5 altered the expression of all three class IIa HDACs that are highly expressed in the brain, HDAC4, HDAC5, and HDAC9, and also induced nuclear accumulation of HDAC4. HDAC4 knockdown abolished a subset of the gene expression changes induced by AP5, and led to neuronal death under long-term tetrodotoxin or AP5 treatment in rat hippocampal organotypic slice cultures. These data suggest that basal, but not evoked, NMDAR activity regulates gene expression in part through HDAC4, and, that HDAC4 has neuroprotective functions under conditions of low NMDAR activity.

PINK1 positively regulates HDAC3 to suppress dopaminergic neuronal cell death

Deciphering the molecular basis of neuronal cell death is a central issue in the etiology of neurodegenerative diseases, such as Parkinson's and Alzheimer's. Dysregulation of p53 levels has been implicated in neuronal apoptosis. The role of histone deacetylase 3 (HDAC3) in suppressing p53-dependent apoptosis has been recently emphasized; however, the molecular basis of modulation of p53 function by HDAC3 remains unclear. Here we show that PTEN-induced putative kinase 1 (PINK1), which is linked to autosomal recessive early-onset familial Parkinson's disease, phosphorylates HDAC3 at Ser-424 to enhance its HDAC activity in a neural cell-specific manner. PINK1 prevents H2O2-induced C-terminal cleavage of HDAC3 via phosphorylation of HDAC3 at Ser-424, which is reversed by protein phosphatase 4c. PINK1-mediated phosphorylation of HDAC3 enhances its direct association with p53 and causes subsequent hypoacetylation of p53. Genetic deletion of PINK1 partly impaired the suppressive role of HDAC3 in regulating p53 acetylation and transcriptional activity. However, depletion of HDAC3 fully abolished the PINK1-mediated p53 inhibitory loop. Finally, ectopic expression of phosphomometic-HDAC3(S424E) substantially overcomes the defective action of PINK1 against oxidative stress in dopaminergic neuronal cells. Together, our results uncovered a mechanism by which PINK1-HDAC3 network mediates p53 inhibitory loop in response to oxidative stress-induced damage.

Abstract 5537: Histone deacetylase 11 (HDAC11) regulates B cell lymphopoiesis and potentiates plasma cell survival in multiple myeloma

Abstract Initially studied mainly for its role as a regulator of neural cell differentiation and development, expression of HDAC11 was once thought to be restricted exclusively to brain, kidney and testes. Hence, our recent discovery that HDAC11 acts as an important modulator of antigen presentation and T cell activation, downregulating IL-10 transcription via interactions with the IL-10 promoter at the chromatin level, exposes a previously unknown capacity and tissue specificity for this enzyme. Transgenic mice harboring an eGFP reporter construct driven by the HDAC11 promoter (Tg-HDAC11-eGFP) (Heinz, N Nat. Rev. Neuroscience 2001) clearly illustrate the dynamic changes in HDAC11 gene expression in hematopoietic cell lineages, additionally unveiling an important role for HDAC11 in B cell lymphopoiesis and plasma cell biology. While common lymphoid progenitors appear to be devoid of HDAC11 transcriptional activation as indicated by minimal detectable eGFP expression, eGFP intensity markedly increases in the B-1 stage of differentiation in the periphery. Interestingly, examination of both the bone marrow (BM) and peripheral blood (PB) plasma cell compartment demonstrates an increase in expression of eGFP/HDAC11 mRNA at the steady-state, and these results are consistent with HDAC11 expression measured in PB from healthy human subjects. Furthermore, mice globally deficient in HDAC11 expression (HDAC11KO mice) exhibit a 50% decrease in plasma cells in both the bone marrow and peripheral blood plasma cell compartments relative to wild-type mice. The concordance of HDAC11 expression and plasma cell differentiation leads us to hypothesize that HDAC11 may also be critical to malignant plasma cell survival. A comparison of normal bone marrow and malignant plasma cells isolated from multiple myeloma patient samples reveals a significantly higher level of HDAC11 expression associated with malignancy. Similar results are observed in 8 of 12 myeloma cell lines suggesting that HDAC11 expression may provide a distinct survival advantage to malignant plasma cells. Further stratification of patients into “newly diagnosed” and “proteasome inhibitor resistant” categories defines a positive correlation between HDAC11 expression and refractory disease. Treatment of the myeloma cell lines with Quisinostat, a second-generation HDAC inhibitor with enhanced selectivity for HDAC 1, 2, 4, 10 and 11 induces growth retardation at low nanomolar concentrations. Future studies will entail direct targeting of HDAC11 in myeloma cell lines and patient specimens to determine the contribution of HDAC11 to Quinsinostat activity. Taken together, we have unveiled a previously unknown role for HDAC11 in plasma cell differentiation and survival. The demonstration of HDAC11 overexpression in primary human myeloma cells provides a framework for therapeutics targeting this HDAC in multiple myeloma. Citation Format: Eva Sahakian, Jason Brayer, John Powers, Mark Meads, Susan Deng, Allison Distler, Melissa Alsina, Taiga Nishihori, Rachid Baz, Alejandro Villagra, Javier Pinilla-Ibarz, Eduardo Sotomayor, Kenneth Shain. Histone deacetylase 11 (HDAC11) regulates B cell lymphopoiesis and potentiates plasma cell survival in multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5537. doi:10.1158/1538-7445.AM2014-5537

Abstract 4089: Histone deacetylase 6 (HDAC6) as a regulator of PD-L1 expression through STAT3 modulation in melanoma

Abstract In spite of the progress made in the understanding of the cell biology, genetics and immunology of melanoma, the outcome for patients with advanced-stage disease has remained poor with a median survival ranging from 2-16 months. Some optimism was recently provided in metastatic melanoma by the improved clinical outcomes observed in patients receiving PD-L1 blocking antibodies. A better understanding of the environmental, genetic and epigenetic factors limiting the efficacy of melanoma immunotherapy will provide appropriate partner(s) for combination with Ipilimumab or PD1/PDL1 antibodies. Among the epigenetic factors, we have found that one member of the histone deacetylase family, HDAC6, plays a critical role not only in the regulation of survival/apoptosis of melanoma cells but also in limiting their immunogenicity and recognition by immune effector cells. Particularly, we found a major role of HDAC6 as a modulator of the immunosuppresive STAT3/IL-10 pathway and down-regulation of tolerogenic PD-L1 molecules in melanoma cells. By analyzing HDAC6 knock-down melanoma cell lines (HDAC6KD) we demonstrated the inactivation of the STAT3 pathway and the subsequent down-regulation of its target genes, including the expression of PD-L1. We also observed that the PD-L1 expression and phosphorylation of STAT3 was decreased in melanoma isolated from xenograph tumor growth models after in vivo treatment with specific HDAC6 inhibitors Fortunately, there are multiple HDAC6-selective inhibitors available to mechanistically study the role of HDAC6 on these processes and provide a viable therapeutic avenue, which may minimize undesirable side effects that are characteristic of pan-HDACi such as SAHA. By building on our understanding of HDAC6 and applying these findings to novel experimental design, we hope to identify innovative therapeutic options to benefit cancer patients. Citation Format: Maritza Lienlaf, Patricio Perez-Villarroel, Calvin Lee, Fengdong Cheng, Jorge Canales, Tessa Knox, Danay Marante, Amod Sarnaik, Pedro Horna, Ed. Seto, Keiran Smalley, Jeffrey S. Weber, Eduardo M. Sotomayor, Alejandro Villagra. Histone deacetylase 6 (HDAC6) as a regulator of PD-L1 expression through STAT3 modulation in melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4089. doi:10.1158/1538-7445.AM2014-4089

Abstract 4086: Histone deacetylase 6 (HDAC6) as a new target modulating the proliferation and immune-related pathways in melanoma

Abstract Histone deacetylases (HDACs), originally described as histone modifiers, have more recently been demonstrated to modify a variety of other proteins involved in diverse cellular processes unrelated to the chromatin environment. This includes the deacetylation of multiple non-histone targets, such as proteins involved in cell cycle/apoptosis and immune regulation. Specifically, HDACs have garnered significant interest due to the availability of drugs that selectively inhibits HDACs. We recently identified that the pharmacological or genetic abrogation of a single HDAC, HDAC6, modifies the immunogenicity and proliferation of melanoma in both in vitro and in vivo models. Using specific HDAC6 inhibitors (HDAC6i) we observed decreased proliferation and G1 cell cycle arrest in all melanoma cell lines measured by MTS assay and flow cytometry. These results were also observed in stable HDAC6 knockdown melanoma cell lines (HDAC6KD) generated by specific lentiviral shRNA for HDAC6. In addition to the effects observed in proliferation and apoptosis after inhibiting HDAC6, we found important changes in the expression of immune-related pathways, including increased expression of MHC, co-stimulatory molecules, and specific melanoma tumor associated antigens such as gp100, MART-1, Tyrp1 and Tyrp2. Our in vitro results were further supported by in vivo tumor growth studies. We observed a delayed tumor growth of inoculated B16 melanoma cells in C57BL/6 mice treated with selective HDAC6i. A similar outcome was identified after inoculation of HDAC6KD B16 melanoma cells in C57BL/6 mice. Such an effect was reverted partially in CD4+ and CD8+ depleted C57BL/6 mice challenged with HDAC6KD cells, suggesting that the disruption of HDAC6 enhances immune system recognition of melanoma cells. This delay in tumor growth could be a reflection of their diminished proliferation and an increase in their immunogenicity leading to improved immune recognition and clearance. These studies provide critical insights into the molecular pathways that are involved in the regulatory role of HDAC6 in cell proliferation, survival, and cytokine signaling of human melanoma cells. Collectively, our data has identified HDAC6 as an attractive therapeutic target in melanoma. Citation Format: Patricio Perez-Villarroel, Maritza Lienlaf, Calvin Lee, Fengdong Cheng, David Woods, Kelly Barrios, Karrune Woan, Jorge Canales, Tessa Knox, Danay Marante, Hongwei Wang, Pedro Horna, Keiran Smalley, Esteban Celis, Ed Seto, Jeffrey S. Weber, Eduardo M. Sotomayor, Alejandro Villagra. Histone deacetylase 6 (HDAC6) as a new target modulating the proliferation and immune-related pathways in melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4086. doi:10.1158/1538-7445.AM2014-4086

Role of histone deacetylase in spinal cord in maintenance of neuropathic pain in rats

Objective To evaluate the role of histone deacetylase in the spinal cord in the maintenance of neuropathic pain (NP) in rats.Methods Twenty-seven male Sprague-Dawley rats,weighing 230-270 g,were randomly divided into 3 groups (n =9 each) using a random number table:sham operation group (group S),group NP,and NP + intrathecal Trichostatin A (TSA) group (group T).NP was induced by chronic constrictive injury.At 7 days after operation,5％ DMSO,5％DMSO and TSA 10 μg (10 μl) were injected intrathecally once a day for 3 consecutive days in S,NP and T groups,respectively.Mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 1 day before operation and 3,7,10,14 and 21 days after operation (T0-5).Results Compared with group S,MWT was significantly decreased and TWL was shortened at T2-5 in NP and T groups.Compared with group NP,MWT was significantly increased and TWL was prolonged at T3,4 in group T.Conclusion Histone deacetylase in the spinal cord is involved in the maintenance of neuropathic pain in rats. Key words: Histone deacetylases; Neuralgia

A role for histone deacetylases in the cellular and behavioral mechanisms underlying learning and memory.

Histone deacetylases (HDACs) are a family of chromatin remodeling enzymes that restrict access of transcription factors to the DNA, thereby repressing gene expression. In contrast, histone acetyltransferases (HATs) relax the chromatin structure allowing for an active chromatin state and promoting gene transcription. Accumulating data have demonstrated a crucial function for histone acetylation and histone deacetylation in regulating the cellular and behavioral mechanisms underlying synaptic plasticity and learning and memory. In trying to delineate the roles of individual HDACs, genetic tools have been used to manipulate HDAC expression in rodents, uncovering distinct contributions of individual HDACs in regulating the processes of memory formation. Moreover, recent findings have suggested an important role for HDAC inhibitors in enhancing learning and memory processes as well as ameliorating symptoms related to neurodegenerative diseases. In this review, we focus on the role of HDACs in learning and memory, as well as significant data emerging from the field in support of HDAC inhibitors as potential therapeutic targets for the treatment of cognitive disorders.

A novel role for histone deacetylase 6 in the regulation of the tolerogenic STAT3/IL-10 pathway in APCs.

APCs are critical in T cell activation and in the induction of T cell tolerance. Epigenetic modifications of specific genes in the APC play a key role in this process, and among them histone deacetylases (HDACs) have emerged as key participants. HDAC6, one of the members of this family of enzymes, has been shown to be involved in regulation of inflammatory and immune responses. In this study, to our knowledge we show for the first time that genetic or pharmacologic disruption of HDAC6 in macrophages and dendritic cells results in diminished production of the immunosuppressive cytokine IL-10 and induction of inflammatory APCs that effectively activate Ag-specific naive T cells and restore the responsiveness of anergic CD4(+) T cells. Mechanistically, we have found that HDAC6 forms a previously unknown molecular complex with STAT3, association that was detected in both the cytoplasmic and nuclear compartments of the APC. By using HDAC6 recombinant mutants we identified the domain comprising amino acids 503-840 as being required for HDAC6 interaction with STAT3. Furthermore, by re-chromatin immunoprecipitation we confirmed that HDAC6 and STAT3 are both recruited to the same DNA sequence within the Il10 gene promoter. Of note, disruption of this complex by knocking down HDAC6 resulted in decreased STAT3 phosphorylation--but no changes in STAT3 acetylation--as well as diminished recruitment of STAT3 to the Il10 gene promoter region. The additional demonstration that a selective HDAC6 inhibitor disrupts this STAT3/IL-10 tolerogenic axis points to HDAC6 as a novel molecular target in APCs to overcome immune tolerance and tips the balance toward T cell immunity.

The role of histone deacetylase 6 (HDAC6) in neurodegeneration

HDAC6 is an enzyme that regulates a variety of biological pathways in dividing cells, but also in post-mitotic neurons. In these cells, different cellular functions and survival are dependent on HDAC6-mediated processes such as intracellular trafficking, antioxidation, chaperone-mediated stress responses, and protein degradation. As a consequence, the interest in HDAC6 as a potential target to treat several neurodegenerative disorders has grown signifi - cantly over the last decade. This review summarizes the current knowledge on the interaction partners and functions of HDAC6 as well as the most important arguments for its involvement in several neurodegenerative diseases. As many of these disorders are hallmarked by alterations in HDAC6-mediated pathways, it is hypothesized that HDAC6 could play a pivotal role in the pathophysiology of neurodegeneration. HDAC6-dependent deacetylation of its substrates could result in neurotoxicity, while the ubiquitin-dependent functions of HDAC6 could be essential for neuroprotection. Therefore, targeting the deacetylating activity of HDAC6, while leaving its other functions unhampered, might be an interesting strategy to treat neurodegenerative

Nuclear localization signal domain of HDAC3 is necessary and sufficient for the expression regulation of MDR1

Histone acetylation/deacetylation has been known to be associated with the transcriptional regulation of various genes. The role of histone deacetylase-3 in the expression regulation of MDR1 was investigated. The expression level of HDAC3 showed an inverse relationship with the expression level of MDR1. Wild-type HDAC3, but not catalytic mutant HDAC3S424A, negatively regulated the expression of MDR1. Wild-type HDAC3, but not catalytic mutant HDAC3S424A, showed binding to the promoter sequences of HDAC3. HDAC3 regulated the expression level, and the binding of Ac-H3K9/14 and Ac-H4K16 around the MDR1 promoter sequences. The nuclear localization signal domain of HDAC3 was necessary, and sufficient for the binding of HDAC3 to the MDR1 promoter sequences and for conferring sensitivity to microtubule-targeting drugs. [BMB Reports 2014; 47(6): 342-347]

Histone deacetylase 8 regulates cortactin deacetylation and contraction in smooth muscle tissues.

Histone deacetylases (HDACs) are a family of enzymes that mediate nucleosomal histone deacetylation and gene expression. Some members of the HDAC family have also been implicated in nonhistone protein deacetylation, which modulates cell-cycle control, differentiation, and cell migration. However, the role of HDACs in smooth muscle contraction is largely unknown. Here, HDAC8 was localized both in the cytoplasm and the nucleus of mouse and human smooth muscle cells. Knockdown of HDAC8 by lentivirus-encoding HDAC8 shRNA inhibited force development in response to acetylcholine. Treatment of smooth muscle tissues with HDAC8 inhibitor XXIV (OSU-HDAC-44) induced relaxation of precontracted smooth muscle tissues. In addition, cortactin is an actin-regulatory protein that undergoes deacetylation during migration of NIH 3T3 cells. In this study, acetylcholine stimulation induced cortactin deacetylation in mouse and human smooth muscle tissues, as evidenced by immunoblot analysis using antibody against acetylated lysine. Knockdown of HDAC8 by RNAi or treatment with the inhibitor attenuated cortactin deacetylation and actin polymerization without affecting myosin activation. Furthermore, expression of a charge-neutralizing cortactin mutant inhibited contraction and actin dynamics during contractile activation. These results suggest a novel mechanism for the regulation of smooth muscle contraction. In response to contractile stimulation, HDAC8 may mediate cortactin deacetylation, which subsequently promotes actin filament polymerization and smooth muscle contraction.

Histone deacetylase HDAC4 promotes gastric cancer SGC-7901 cells progression via p21 repression.

Gastric cancer (GC) is one of the leading causes of cancer death in the world. The role of histone deacetylase 4 (HDAC4) in specific cell and tissue types has been identified. However, its biological roles in the development of gastric cancer remain largely unexplored. Quantitative real time PCR (qRT-PCR) and western blot were used to analyze the expression of HDAC4 in the clinical samples. siRNA and overexpression of HDAC4 and siRNA p21 were used to study functional effects in a proliferation, a colony formation, a adenosine 5′-triphosphate (ATP) assay and reactive oxygen species(ROS) generation, cell cycle, cell apoptosis rates, and autophagy assays. HDAC4 was up-regulated in gastric cancer tissues and several gastric cancer cell lines. The proliferation, colony formation ability and ATP level were enhanced in HDAC4 overexpression SGC-7901 cells, but inhibited in HDAC4 knockdown SGC-7901 cells. HDAC4 knockdown led to G0/G1 phase cell arrest and caused apoptosis and ROS increase. Moreover, HDAC4 was found to inhibit p21 expression in gastric cancer SGC-7901 cells. p21 knockdown dramatically attenuated cell proliferation inhibition, cell cycle arrest, cell apoptosis promotion and autophagy up-regulation in HDAC4-siRNA SGC-7901 cells. We demonstrated that HDAC4 promotes gastric cancer cell progression mediated through the repression of p21. Our results provide an experimental basis for understanding the pro-tumor mechanism of HDAC4 as treatment for gastric cancer.

Chromatin analysis of an Arabidopsis Phytochrome A allele reveals the correlation of transcriptional repression with recalcitrance to histone acetylation

Phytochrome A (phyA) is a major photoreceptor of red light that regulates seedling de-etiolation. The wild-type PHYA is abundantly expressed in dark and repressed by light through chromatin modification involving histone hypoacetylation and enrichment of the repressive histone mark, H3 lysine 27 trimethylation (H3K27me3). Earlier, an Arabidopsis phyA allele, phyA-17, was reported that contains hypermethylation in the gene body, and is repressed constitutively (transcriptional repression in the dark). In this study, chromatin analysis of phyA-17 was done to understand the basis of its transcriptional repression. Specifically, this study analyzed four different histone modifications on phyA-17 and the wild-type PHYA (Columbia-0) in light and dark conditions. This analysis revealed hypoacetylation of phyA-17 chromatin in both conditions correlating with its constitutive repression. However, relative enrichment of H3K27me3 on phyA-17 chromatin was not detected in either condition. Histone hypoacetylation suggested a role of histone deacetylases in phyA-17 repression. Chemical inhibitors of histone deacetylases, Trichostatin A and Sodium Butyrate, induced partial de-etiolation of phyA-17 seedlings without activating the resident phyA gene. Gene expression analysis revealed activation of the phyA-signaling pathway by Trichostatin A, suggesting a role of histone deacetylases downstream in the seedling de-etiolation pathway. However, since phyA-17 repression is not dependent on histone deacetylases, recalcitrance to histone acetylation by histone acetyl transferases, possibly due to hypermethylation, is likely the basis of its hypoacetylated chromatin.

HDAC3 acts as a negative regulator of angiogenesis

Histone deacetylase-3 (HDAC3) is involved in cellular proliferation, apoptosis and transcriptional repression. However, the role of HDAC3 in angiogenesis remains unknown. HDAC3 negatively regulated the expression of angiogenic factors, such as VEGF and plasminogen activator inhibitor-1 (PAI-1). HDAC3 showed binding to promoter sequences of PAI-1. HDAC3 activity was necessary for the expression regulation of PAI-1 by HDAC3. VEGF decreased the expression of HDAC3, and the down-regulation of HDAC3 enhanced endothelial cell tube formation. HDAC3 negatively regulated tumor-induced angiogenic potential. We show the novel role of HDAC3 as a negative regulator of angiogenesis. [BMB Reports 2014; 47(4): 227-232]

Bone defects: Molecular and cellular therapeutic targets

Bone defects are one of the most serious pathologies that need tissue regeneration therapies. Studies on mesenchymal stem cells are changing the way we treat bone diseases. MSCs have been used for the treatment of osteogenesis imperfecta, hypophosphatasia, osteonecrosis of the femoral head, osteoporosis, rheumatoid arthritis and osteoarthritis. In this context, it is becoming ever more clear that the future of therapies will be based on the use of stem cells. In this concise review, we highlight the importance of the use of MSCs in bone diseases, focusing on the role of histone deacetylases and Wnt pathways involved in osteogenesis. A better understanding of MSC biology and osteogenesis is needed in order to develop new and targeted therapeutic strategies for the treatment of bone diseases/disorders.

Histone Deacetylase-3 Mediates Positive Feedback Relationship between Anaphylaxis and Tumor Metastasis

Allergic inflammation has been known to enhance the metastatic potential of tumor cells. The role of histone deacetylase-3 (HDAC3) in allergic skin inflammation was reported. We investigated HDAC3 involvement in the allergic inflammation-promotion of metastatic potential of tumor cells. Passive systemic anaphylaxis (PSA) induced HDAC3 expression and FcεRI signaling in BALB/c mice. PSA enhanced the tumorigenic and metastatic potential of mouse melanoma cells in HDAC3- and monocyte chemoattractant protein 1-(MCP1)-dependent manner. The PSA-mediated enhancement of metastatic potential involved the induction of HDAC3, MCP1, and CD11b (a macrophage marker) expression in the lung tumor tissues. We examined an interaction between anaphylaxis and tumor growth and metastasis at the molecular level. Conditioned medium from antigen-stimulated bone marrow-derived mouse mast cell cultures induced the expression of HDAC3, MCP1, and CCR2, a receptor for MCP1, in B16F1 mouse melanoma cells and enhanced migration and invasion potential of B16F1 cells. The conditioned medium from B16F10 cultures induced the activation of FcεRI signaling in lung mast cells in an HDAC3-dependent manner. FcεRI signaling was observed in lung tumors derived from B16F10 cells. Target scan analysis predicted HDAC3 to be as a target of miR-384, and miR-384 and HDAC3 were found to form a feedback regulatory loop. miR-384, which is decreased by PSA, negatively regulated HDAC3 expression, allergic inflammation, and the positive feedback regulatory loop between anaphylaxis and tumor metastasis. We show the miR-384/HDAC3 feedback loop to be a novel regulator of the positive feedback relationship between anaphylaxis and tumor metastasis.