trichostatin-a and Diabetes-Mellitus--Type-1

Diabetic peripheral neuropathy (DPN) is the common complication of diabetes mellitus. Histone deacetylase (HDAC) inhibitor trichostatin A (TSA) is reported to ameliorate the peripheral nerves degeneration of DPN. However, the exact mechanism is still not well elucidated. Here, we first revealed that TSA promoted nerve conduction and brain derived neurotrophic factor (BDNF) expression in the sciatic nerves of diabetic mice. In line, TSA also reversed high glucose-reduced mature BDNF expression in vitro cultured rat Schwann cells (RSC96). Then unexpectedly, the downstream targets of TSA HDAC1 and HDAC5 were not involved in TSA-improved BDNF expression. Furthermore, unfolded protein response (UPR) chaperone GRP78 was revealed to be downregulated with high glucose stimulation in RSC96 cells, which was avoided with TSA treatment. Also, GRP78 upregulation mediated TSA-improved mature BDNF expression in high glucose-cultured RSC96 cells by binding with BDNF. As well, TSA treatment enhanced the binding of GRP78 with BDNF in RSC96 cells. Again, UPR-associated transcription factors XBP-1s and ATF6 were involved in TSA-increased GRP78 expression in high glucose-stimulated RSC96 cells. Finally, conditioned medium from high glucose-cultured RSC96 cells delayed neuron SH-SY5Y differentiation and that from TSA-treated high glucose-cultured RSC96 cells promoted SH-SY5Y cell differentiation. Taken together, our findings suggested that TSA increased BDNF expression to ameliorate DPN by improving XBP-1s/ATF6/GRP78 axis in Schwann cells.

Topics: Activating Transcription Factor 6; Animals; Brain-Derived Neurotrophic Factor; Cell Line, Tumor; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Neuropathies; Endoplasmic Reticulum Chaperone BiP; Heat-Shock Proteins; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Male; Mice, Inbred C57BL; Rats; Schwann Cells; Sciatic Nerve; Signal Transduction; Up-Regulation; X-Box Binding Protein 1

Modulation of histone deacetylase (HDAC) activity has been implicated as a potential therapeutic strategy for multiple diseases. Recent studies have put a greater spotlight on metabolic diseases, in particular Type 1 and Type 2 diabetes, as potential indications for which HDAC inhibition could be beneficial. Evidence suggests that inhibition of HDAC3 protects β-cells from cytokine-induced apoptosis, an important event in the development of Type 1 diabetes. On the other hand, the pathogenesis of Type 2 diabetes involves a combination of peripheral insulin resistance and pancreatic β-cell failure. Again, data from the literature indicate that HDAC3 regulates genes involved in key metabolic events. Together, these results suggest that selective inhibition of HDAC3 may be an attractive strategy for targeting these diseases.

Topics: Animals; Apoptosis; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Histone Deacetylase 1; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Insulin Resistance; Insulin-Secreting Cells; Mice; Rats; RNA Interference; RNA, Small Interfering

Epigenetic alteration of the genome has been shown to provide palliative effects in mouse models of certain human autoimmune diseases. We have investigated whether chromatin remodeling could provide protection against autoimmune diabetes in NOD mice. Treatment of female mice during the transition from prediabetic to diabetic stage (18-24 weeks of age) with the well-characterized histone deacetylase inhibitor, trichostatin A effectively reduced the incidence of diabetes. However, similar treatment of overtly diabetic mice during the same time period failed to reverse the disease. Protection against diabetes was accompanied by histone hyperacetylation in pancreas and spleen, enhanced frequency of CD4(+) CD62L(+) cells in the spleen, reduction in cellular infiltration of islets, restoration of normoglycemia and glucose-induced insulin release by beta cells. Activation of splenic T lymphocytes derived from protected mice in vitro with pharmacological agents that bypass the antigen receptor or immobilized anti-CD3 antibody resulted in enhanced expression of Ifng mRNA and protein without altering the expression of Il4, Il17, Il18, Inos and Tnfa genes nor the secretion of IL-2, IL-4, IL-17 and TNF-α proteins. Consistently, expression of the transcription factor involved in Ifng transcription, Tbet/Tbx21 but not Gata3 and Rorgt, respectively, required for the transcription of Il4 and Il17, was upregulated in activated splenocytes of protected mice. These results indicate that chromatin remodeling can lead to amelioration of diabetes by using multiple mechanisms including differential gene transcription. Thus, epigenetic modulation could be a novel therapeutic approach to block the transition from benign to frank diabetes.

Topics: Acetylation; Animals; Chromatin Assembly and Disassembly; Diabetes Mellitus, Type 1; Epigenomics; Female; Gene Expression Regulation; Histone Deacetylase Inhibitors; Histones; Hydroxamic Acids; Immune System; Inflammation; Interferon-gamma; Islets of Langerhans; Mice; Mice, Inbred NOD; T-Box Domain Proteins; T-Lymphocyte Subsets; Up-Regulation

Excessive accumulation of extracellular matrix (ECM) in the kidneys and epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells contributes to the renal fibrosis that is associated with diabetic nephropathy. Histone deacetylase (HDAC) determines the acetylation status of histones and thereby controls the regulation of gene expression. This study examined the effect of HDAC inhibition on renal fibrosis induced by diabetes or transforming growth factor (TGF)-beta1 and determined the role of reactive oxygen species (ROS) as mediators of HDAC activation. In streptozotocin (STZ)-induced diabetic kidneys and TGF-beta1-treated normal rat kidney tubular epithelial cells (NRK52-E), we found that trichostatin A, a nonselective HDAC inhibitor, decreased mRNA and protein expressions of ECM components and prevented EMT. Valproic acid and class I-selective HDAC inhibitor SK-7041 also showed similar effects in NRK52-E cells. Among the six HDACs tested (HDAC-1 through -5 and HDAC-8), HDAC-2 activity significantly increased in the kidneys of STZ-induced diabetic rats and db/db mice and TGF-beta1-treated NRK52-E cells. Levels of mRNA expression of fibronectin and alpha-smooth muscle actin were decreased, whereas E-cadherin mRNA was increased when HDAC-2 was knocked down using RNA interference in NRK52-E cells. Interestingly, hydrogen peroxide increased HDAC-2 activity, and the treatment with an antioxidant, N-acetylcysteine, almost completely reduced TGF-beta1-induced activation of HDAC-2. These findings suggest that HDAC-2 plays an important role in the development of ECM accumulation and EMT in diabetic kidney and that ROS mediate TGF-beta1-induced activation of HDAC-2.

Topics: Acetylcysteine; Amides; Animals; Antioxidants; Biphenyl Compounds; Cell Line; Cell Transdifferentiation; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Enzyme Inhibitors; Extracellular Matrix Proteins; Fibrosis; Gene Expression Regulation; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Kidney; Male; Mice; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Recombinant Proteins; Repressor Proteins; RNA Interference; RNA, Messenger; Transforming Growth Factor beta1; Valproic Acid

Transcriptional coactivators are essential mediators of signal amplification in the regulation of gene expression in response to hormones and extracellular signals. We previously identified Bridge-1 (PSMD9) as a PDZ-domain coregulator that augments insulin gene transcription via interactions with the basic helix-loop-helix transcription factors E12 and E47, and that increases transcriptional activation by the homeodomain transcription factor PDX-1. In these studies, we find that transcriptional activation by Bridge-1 can be regulated via interactions with the histone acetyltransferase and nuclear receptor coactivator p300. In transfection assays, transcriptional activation by Bridge-1 is increased by the inhibition of endogenous histone deacetylase activity with trichostatin A, indicating that the transcriptional activation function of Bridge-1 can be regulated by histone modifications. The exogenous expression of p300 enhances the transcriptional activation by Bridge-1 in a dose-dependent manner. In contrast, the sequestration of p300 by the overexpression of the adenoviral protein E1A, but not by an E1A mutant protein that is unable to interact with p300, suppresses the transcriptional activation by Bridge-1. We demonstrate that p300 and Bridge-1 proteins interact in immunopre-cipitation and glutathione-S-transferase (GST) pull-down assays. Bridge-1 interacts directly with multiple regions within p300 that encompass C/H1 or C/H2 cysteine- and histidine-rich protein interaction domains and the histone acetyltransferase domain. Deletion or point mutagenesis of the Bridge-1 PDZ domain substantially reduces transcriptional activation by Bridge-1 and interrupts interactions with p300. We propose that p300 interactions with Bridge-1 can augment the transcriptional activation of regulatory target genes by Bridge-1.

Topics: Adenovirus E1A Proteins; Animals; Blotting, Western; Cells, Cultured; Diabetes Mellitus, Type 1; Dose-Response Relationship, Drug; Gene Deletion; Glutathione Transferase; Helix-Loop-Helix Motifs; Histone Deacetylase Inhibitors; Hydroxamic Acids; Immunoprecipitation; Insulin; Mutagenesis, Site-Directed; p300-CBP Transcription Factors; Point Mutation; Proteasome Endopeptidase Complex; Protein Structure, Tertiary; Proteins; Transcription, Genetic; Transcriptional Activation; Yeasts