Evidence for the phosphorylation of serine259 of histone deacetylase 5 by protein kinase Cδ

Signaling via pro-growth G protein coupled receptors triggers phosphorylation of HDAC5 on two serine residues (Ser259 and Ser498), resulting in nuclear export of HDAC5 and de-repression of downstream target genes. In the previous paper we reported the important role of PKD isozymes in the regulation of HDAC5 by phosphorylating Ser498 of HDAC5 [Q.K. Huynh, T.A. Mckinsey, Arch. Biochem. Biophys. 450 (2006) 141–148]. In the present paper, we provide evidence that PKCδ can directly phosphorylate Ser259 of HDAC5. The evidence is based on the following facts (a) isolated kinase fraction from human failing heart tissues contained PKCδ that phosphorylated HDAC5 Ser259 peptide and no significant activity was found for the unbound fraction after they were immunoprecipitated with PKCδ specific antibody; (b) specific inhibitors for PKCδ inhibited kinase activity from isolated fraction and recombinant human PKCδ with similar IC50 values; (c) recombinant human PKCδ can directly phosphorylate full length Ser259 HDAC5 protein and HDAC5 Ser259 peptide. The results suggest that in addition to activation of protein kinase D isozymes by phosphorylating Ser744 and Ser748 at their activation sites, PKCδ may also play a role in the regulation of HDAC5 by phosphorylation of Ser259.

Research highlights► Phosphorylation of HDAC5 on Ser259 and Ser498 resulted in its nuclear export and de-repression of downstream target genes. The identity of kinase(s) that phosphorylated HDAC5 Ser259 is however still not clear. ► During the course of isolating HDAC5 kinase(s) from human tissues, we found that the final purified fraction contained PKCdelta that can directly phosphorylate HDAC5 Ser259. ► The results indicate that PKCdelta may play a role in the regulation of HDAC5 phosphorylation.