PKA phosphorylates histone deacetylase 5 and prevents its nuclear export, leading to the inhibition of gene transcription and cardiomyocyte hypertrophy

Abstract

Dynamic nucleocytoplasmic shuttling of class IIa histone deacetylases (HDACs) is a fundamental mechanism regulating gene transcription. Recent studies have identified several protein kinases that phosphorylate HDAC5, leading to its exportation from the nucleus. However, the negative regulatory mechanisms for HDAC5 nuclear exclusion remain largely unknown. Here we show that cAMPactivated protein kinase A (PKA) specifically phosphorylates HDAC5 and prevents its export from the nucleus, leading to suppression of gene transcription. PKA interacts directly with HDAC5 and phosphorylates HDAC5 at serine 280, an evolutionarily conserved site. Phosphorylation of HDAC5 by PKA interrupts the association of HDAC5 with protein chaperone 14-3-3 and hence inhibits stress signal-induced nuclear export of HDAC5. An HDAC5 mutant that mimics PKA-dependent phosphorylation localizes in the nucleus and acts as a dominant inhibitor for myocyte enhancer factor 2 transcriptional activity. Molecular manipulations of HDAC5 show that PKA-phosphorylated HDAC5 inhibits cardiac fetal gene expression and cardiomyocyte hypertrophy. Our findings identify HDAC5 as a substrate of PKA and reveal a cAMP/PKA-dependent pathway that controls HDAC5 nucleocytoplasmic shuttling and represses gene transcription. This pathway may represent a mechanism by which cAMP/PKA signaling modulates a wide range of biological functions and human diseases such as cardiomyopathy.nucleocytoplasmic shuttling | phosphorylation G ene transcription is governed in part by the acetylation and deacetylation of histones, the latter of which is mediated by histone deacetylases (HDACs) (1-4). In particular, class IIa HDACs, such as HDAC5, acting as transcriptional repressors, have been implicated in cardiac hypertrophy, skeletal muscle differentiation, and angiogenesis (5-10). Dynamic nucleocytoplasmic shuttling has been proposed as a fundamental mechanism regulating the function of class IIa HDACs (1, 11-13). Recent studies have identified several protein kinases, including calmodulin-dependent protein kinases (CaMKs), protein kinase D (PKD) and salt-inducible kinase, that phosphorylate HDAC5, leading to its export from the nucleus (1, 9, 14). However, much less is understood about the negative regulatory mechanisms for the nuclear exclusion of HDAC5 (15). To date, specific protein kinases that may inhibit export of HDAC5 from the nucleus have not been identified.The cAMP/protein kinase A (PKA) signaling pathway regulates a variety of cellular functions and numerous important biological processes (16,17). Many of the effects of cAMP/PKA are mediated via changes in gene transcription. A large body of research has defined the cAMP-response element binding (CREB) proteins as PKA substrates that mediate an increase in gene expression in response to cAMP (18)(19)(20). However, whether and how the cAMP/PKA pathway inhibits gene expression remains unclear. In this study, we found that cAMP/PKA signaling represses gene transcription and cardiomyocyte hypertrophy by phosphorylating HDAC5 ...

Klotho Protects Against Indoxyl Sulphate-Induced Myocardial Hypertrophy

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Dephosphorylation at a Conserved SP Motif Governs cAMP Sensitivity and Nuclear Localization of Class IIa Histone Deacetylases*

“…Ser-279 of HDAC5 was just reported to be a target of cAMP signaling and PKA phosphorylation (81) and was independently identified as a phosphorylation site by mass spectrometry (79). Together, these findings provide further support for the importance of phosphorylation at Ser-266 of HDAC4 and Ser-279 of HDAC5.…”

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