Königstein David, Fender Hauke, Plačkić Jelena, Kisko Theresa M, Wöhr Markus, Kockskämper Jens
Institute of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, University of Marburg, 35032 Marburg, Germany.
Center for Mind, Brain and Behavior (CMBB), University of Marburg, 35032 Marburg, Germany.
Int J Mol Sci. 2024 Dec 22;25(24):13713. doi: 10.3390/ijms252413713.
encodes the α1c subunit of the L-type Ca channel, Cav1.2. Ventricular myocytes from haploinsufficient () rats exhibited reduced expression of Cav1.2 but an apparently normal sarcolemmal Ca influx with an impaired response to sympathetic stress. We tested the hypothesis that the altered phosphorylation of Cav1.2 might underlie the sarcolemmal Ca influx phenotype in myocytes using immunoblotting of the left ventricular (LV) tissue from versus wildtype (WT) hearts. Activation of cAMP-dependent protein kinase A (PKA) increases L-type Ca current and phosphorylates Cav1.2 at serine-1928. Using an antibody directed against this phosphorylation site, we observed elevated phosphorylation of Cav1.2 at serine-1928 in LV myocardium from rats under basal conditions (+110% versus WT). Sympathetic stress was simulated by isoprenaline (100 nM) in Langendorff-perfused hearts. Isoprenaline increased the phosphorylation of serine-1928 in LV myocardium by ≈410%, but the increase was significantly smaller than in WT myocardium (≈650%). In conclusion, our study reveals altered PKA-dependent phosphorylation of Cav1.2 with elevated phosphorylation of serine-1928 under basal conditions and a diminished phosphorylation reserve during β-adrenergic stimulation. These alterations in the phosphorylation of Cav1.2 may explain the apparently normal sarcolemmal Ca influx in myocytes under basal conditions as well as the impaired response to sympathetic stimulation.
编码L型钙通道Cav1.2的α1c亚基。来自单倍体不足（）大鼠的心室肌细胞显示Cav1.2表达降低，但肌膜钙内流明显正常，对交感神经应激的反应受损。我们使用来自与野生型（WT）心脏的左心室（LV）组织进行免疫印迹，测试了Cav1.2磷酸化改变可能是肌细胞中肌膜钙内流表型基础的假设。环磷酸腺苷依赖性蛋白激酶A（PKA）的激活增加L型钙电流并使Cav1.2在丝氨酸-1928处磷酸化。使用针对该磷酸化位点的抗体，我们观察到在基础条件下，来自大鼠LV心肌中Cav1.2在丝氨酸-1928处的磷酸化升高（与WT相比增加110%）。在Langendorff灌注心脏中用异丙肾上腺素（100 nM）模拟交感神经应激。异丙肾上腺素使大鼠LV心肌中丝氨酸-1928的磷酸化增加约410%，但增加幅度明显小于WT心肌（约650%）。总之，我们的研究揭示了在基础条件下Cav1.2的PKA依赖性磷酸化改变，丝氨酸-1928磷酸化升高，以及在β-肾上腺素能刺激期间磷酸化储备减少。Cav1.2磷酸化的这些改变可能解释了在基础条件下肌细胞中明显正常的肌膜钙内流以及对交感神经刺激的反应受损。
