Spatiotemporally Distinct Protein Kinase D Activation in Adult Cardiomyocytes in Response to Phenylephrine and Endothelin

Abstract

Protein kinase D (PKD) is a nodal point in cardiac hypertrophic signaling. It triggers nuclear export of class II histone deacetylase (HDAC) and regulates transcription. Although this pathway is thought to be critical in cardiac hypertrophy and heart failure, little is known about spatiotemporal aspects of PKD activation at the myocyte level. Here, we demonstrate that in adult cardiomyocytes two important neurohumoral stimuli that induce hypertrophy, endothelin-1 (ET1) and phenylephrine (PE), trigger comparable global PKD activation and HDAC5 nuclear export, but via divergent spatiotemporal PKD signals. PE-induced HDAC5 export is entirely PKD-dependent, involving fleeting sarcolemmal PKD translocation (for activation) and very rapid subsequent nuclear import. In contrast, ET1 recruits and activates PKD that remains predominantly sarcolemmal. This explains why PE-induced nuclear HDAC5 export in myocytes is totally PKD-dependent, whereas ET1-induced HDAC5 export depends more prominently on InsP 3 and CaMKII signaling. Thus ␣-adrenergic and ET-1 receptor signaling via PKD in adult myocytes feature dramatic differences in cellular localization and translocation in mediating hypertrophic signaling. This raises new opportunities for targeted therapeutic intervention into distinct limbs of this hypertrophic signaling pathway.Various stresses trigger cardiac hypertrophy, remodeling, and functional alterations (1, 2). Prolonged stress can also become maladaptive, leading to heart failure, cardiac arrhythmias, and sudden death. Many of these changes are mediated by altered gene expression, and Class II histone deacetylases (HDACs) 3 (e.g. HDAC5) are recognized as key modulators of this genetic reprogramming. HDAC5 represses transcription by promoting more condensed DNA, and represses transcription factors such as myocyte enhancing factor 2 (MEF2). HDAC5 phosphorylation triggers its nuclear export (allowing gene activation (Fig. 1a)). Both protein kinase D (PKD) and calmodulin-dependent protein kinase II (CaMKII) are key HDAC kinases (1, 2) and accumulating evidence indicates both kinases are more active in heart failure and can contribute directly to cardiac pathogenesis (3-6). Cardiac PKD is activated in response to hypertension, pressure overload, and chronic neurohumoral signaling (7). Overexpression of constitutively active PKD (and CaMKII␦) cause cardiac hypertrophy followed by chamber dilation (8, 9). Moreover there is increased expression of PKD (and CaMKII␦) in failing rat, rabbit, and human myocardium (8, 10). Thus, whereas PKD and CaMKII activation may be involved in a wide variety of cell functions (11-14), they are attractive potential therapeutic targets in cardiac disease. Therapeutic benefit of PKD/CaMKII inhibition may be largely due to prevention of HDAC (class II) phosphorylation, thereby maintaining the repressive effects of HDAC on transcription. Indeed, HDAC5 knock-out mice develop profound pathological cardiac hypertrophy and HDAC5 overexpression can limit progression of cardiac hypertrophy (15,16)...

Calcium-mediated histone modifications regulate alternative splicing in cardiomyocytes

“…Specifically, a number of studies have demonstrated that elevated intracellular calcium levels activate the calcium/calmodulin-dependent protein kinase (CaMK) or the protein kinase C/D (PKC/PKD) (20)(21)(22)(23)(24)(25). Consequently, the activated kinases lead to increased transcription of a number of cardiac-specific transcription factors through a cascade of events including changes in histone modifications (20)(21)(22)(23)(24)(25).…”

Cardiac Alpha1-Adrenergic Receptors: Novel Aspects of Expression, Signaling Mechanisms, Physiologic Function, and Clinical Importance

“…Several mechanisms for a 1 -AR-mediated hypertrophic signaling are proposed, and a multitude of signal transducers are implicated (Jensen et al, 2011). Certain molecules, based on frequency in the literature, might be considered essential or "core" molecules required for a 1 -AR-mediated hypertrophic signaling, including PLC (Filtz et al, 2009;Zhang et al, 2013), PKC (a, d, and «, three main isotypes activated by a 1 -ARs) (Henrich and Simpson, 1988;Kariya et al, 1991Kariya et al, , 1993Kariya et al, , 1994Karns et al, 1995;Haworth et al, 2000;Rohde et al, 2000;Braz et al, 2002Braz et al, , 2004Vega et al, 2004;Carnegie et al, 2008), PKD (Haworth et al, 2000;Vega et al, 2004;Harrison et al, 2006;Avkiran et al, 2008;Bossuyt et al, 2008Bossuyt et al, , 2011Carnegie et al, 2008;Liu et al, 2009), ERK (Bueno et al, 2000;Xiao et al, 2001;Barron et al, 2003;O'Connell et al, 2003), and class 2 histone deacetylase (Vega et al, 2004;Backs et al, 2006Backs et al, , 2008 Evidence also exists that transactivation of the EGFR is involved in a 1 -mediated hypertrophy (Morris et al, 2004;Guo et al, 2009;Li et al, 2011;Papay et al, 2013).…”

Regulation of Protein Kinase D1 Activity

“…Spatiotemporal differences in PKD1 activation also have been detected in adult cardiomyocytes. Here, phenylephrine (␣ 1 -AR agonist) and endothelin-1 act in a similar manner to induce rapid PKD1 translocation to the sarcolemma (Bossuyt et al, 2011). However, the activated form of PKD1 remains stably associated with the sarcolemma only in endothelin-1-treated cardiomyocytes.…”

“…However, the activated form of PKD1 remains stably associated with the sarcolemma only in endothelin-1-treated cardiomyocytes. In phenylephrine-treated cardiomyocytes, activated PKD1 shuttles to the nucleus, where it phosphorylates the class IIa histone deacetylase HDAC5 (Haworth et al, 2000;Harrison et al, 2006;Bossuyt et al, 2008Bossuyt et al, , 2011; because HDAC5 phosphorylation creates docking sites for 14-3-3 proteins that escort HDAC5 from the nucleus, this pathway provides a mechanism to derepress pathologic gene programs that promote cardiomyocyte hypertrophy ( Fig. 2A).…”