Lysine deacetylases are produced in pancreatic beta cells and are differentially regulated by proinflammatory cytokines

Abstract

Cytokine-induced beta cell toxicity is abrogated by non-selective inhibitors of lysine deacetylases (KDACs). The KDAC family consists of 11 members, namely histone deacetylases HDAC1 to HDAC11, but it is not known which KDAC members play a role in cytokine-mediated beta cell death. The aim of the present study was to examine the KDAC gene expression profile of the beta cell and to investigate whether KDAC expression is regulated by cytokines. In addition, the protective effect of the non-selective KDAC inhibitor ITF2357 and interdependent regulation of four selected KDACs were investigated. The beta cell line INS-1 and intact rat and human islets were exposed to cytokines with or without ITF2357. Expression of mRNA was assessed by real-time PCR and selected targets validated at the protein level by immunoblotting. Effects on cytokine-induced toxicity were investigated by in vitro assays. Hdac1 to Hdac11 were expressed and differentially regulated by cytokines in INS-1 cells and rat islets. HDAC1, -2, -6 and -11 were found to be expressed and regulated by cytokines in human islets. ITF2357 protected against cytokine-induced beta cell apoptosis and counteracted cytokine-induced attenuation of basal insulin secretion. In addition, cytokine-induced regulation of Hdac2 and Hdac6, but not Hdac1 and Hdac11, was reduced by KDAC inhibition. All classical KDAC genes are expressed by beta cells and differentially regulated by cytokines. Based on the relative expression levels and degree of regulation by cytokines, we propose that HDAC1, -2, -6 and -11 are of particular importance for beta cell function. These observations may help in the design of specific KDAC inhibitors to prevent beta cell destruction in situ and in islet grafts.