Cardiac Protein Kinase D1 ablation alters the myocytes β-adrenergic response

• Published in: Journal of molecular and cellular cardiology 2023-07, Vol.180, p.33-43
• Main Authors: Mira Hernandez, Juliana, Ko, Christopher Y., Mandel, Avery R., Shen, Erin Y., Baidar, Sonya, Christensen, Ashley R., Hellgren, Kim, Morotti, Stefano, Martin, Jody L., Hegyi, Bence, Bossuyt, Julie, Bers, Donald M.
• Format: Article
• Language: English
• Subjects: Adrenergic Agents - pharmacology; Adrenergic beta-Agonists - metabolism; Adrenergic beta-Agonists - pharmacology; Animals; Ca2+ sparks; Calcium - metabolism; Calcium handling; Calcium Signaling; Calcium-Calmodulin-Dependent Protein Kinase Type 2 - metabolism; EC-coupling; Mice; Mice, Knockout; Myocytes, Cardiac - metabolism; Phosphorylation; Protein Kinase C - genetics; Protein kinase D; Ryanodine receptor; Ryanodine Receptor Calcium Release Channel - metabolism; Sarcoplasmic Reticulum - metabolism; β-Adrenergic stimulation
• ISSN: 0022-2828; 1095-8584; 1095-8584
• DOI: 10.1016/j.yjmcc.2023.05.001

β-adrenergic (β-AR) signaling is essential for the adaptation of the heart to exercise and stress. Chronic stress leads to the activation of Ca2+/calmodulin-dependent kinase II (CaMKII) and protein kinase D (PKD). Unlike CaMKII, the effects of PKD on excitation-contraction coupling (ECC) remain unclear. To elucidate the mechanisms of PKD-dependent ECC regulation, we used hearts from cardiac-specific PKD1 knockout (PKD1 cKO) mice and wild-type (WT) littermates. We measured calcium transients (CaT), Ca2+ sparks, contraction and L-type Ca2+ current in paced cardiomyocytes under acute β-AR stimulation with isoproterenol (ISO; 100 nM). Sarcoplasmic reticulum (SR) Ca2+ load was assessed by rapid caffeine (10 mM) induced Ca2+ release. Expression and phosphorylation of ECC proteins phospholambam (PLB), troponin I (TnI), ryanodine receptor (RyR), sarcoendoplasmic reticulum Ca2+ ATPase (SERCA) were evaluated by western blotting. At baseline, CaT amplitude and decay tau, Ca2+ spark frequency, SR Ca2+ load, L-type Ca2+ current, contractility, and expression and phosphorylation of ECC protein were all similar in PKD1 cKO vs. WT. However, PKD1 cKO cardiomyocytes presented a diminished ISO response vs. WT with less increase in CaT amplitude, slower [Ca2+]i decline, lower Ca2+ spark rate and lower RyR phosphorylation, but with similar SR Ca2+ load, L-type Ca2+ current, contraction and phosphorylation of PLB and TnI. We infer that the presence of PKD1 allows full cardiomyocyte β-adrenergic responsiveness by allowing optimal enhancement in SR Ca2+ uptake and RyR sensitivity, but not altering L-type Ca2+ current, TnI phosphorylation or contractile response. Further studies are necessary to elucidate the specific mechanisms by which PKD1 is regulating RyR sensitivity. We conclude that the presence of basal PKD1 activity in cardiac ventricular myocytes contributes to normal β-adrenergic responses in Ca2+ handling. [Display omitted] •PKD1 cKO and WT mice have similar baseline Ca2+ handling and contractility.•ISO-induced increase in Ca2+ transient amplitude is smaller in PKD1 cKO mice.•ISO-induced acceleration of [Ca2+]i decline is blunted in PKD1 cKO mice.•ISO-induced contractile response is similar in PKD1 cKO and WT mice.•ISO-induced increase in RyR2 phosphorylation is lower in PKD1 cKO mice.