El-Armouche Ali, Pohlmann Lutz, Schlossarek Saskia, Starbatty Jutta, Yeh Yung-Hsin, Nattel Stanley, Dobrev Dobromir, Eschenhagen Thomas, Carrier Lucie
Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, D-20246, Germany.
J Mol Cell Cardiol. 2007 Aug;43(2):223-9. doi: 10.1016/j.yjmcc.2007.05.003. Epub 2007 May 13.
Cardiac myosin-binding protein-C (cMyBP-C) is an important regulator of cardiac contractility, and its phosphorylation by PKA is a mechanism that contributes to increased cardiac output in response to beta-adrenergic stimulation. It is presently unknown whether heart failure alters cMyBP-C phosphorylation. The present study determined the level of phosphorylated cMyBP-C in failing human hearts and in a canine model of pacing-induced heart failure. A polyclonal antibody directed against the major phosphorylation site of cMyBP-C (Ser-282) was generated and its specificity was confirmed by PKA phosphorylation with isoprenaline in cardiomyocytes and Langendorff-perfused mouse hearts. Left ventricular myocardial tissue from (i) patients with terminal heart failure (hHF; n=12) and nonfailing donor hearts (hNF; n=6) and (ii) dogs with rapid-pacing-induced end-stage heart failure (dHF; n=10) and sham-operated controls (dNF; n=10) were used for quantification of total cMyBP-C and phospho-cMyBP-C by Western blotting. Total cMyBP-C protein levels were similar in hHF and hNF as well as in dHF and dNF. In contrast, the ratio of phospho-cMyBP-C to total cMyBP-C levels were >50% reduced in hHF and >40% reduced in dHF. In summary, cMyBP-C phosphorylation levels are markedly decreased in human and experimental heart failure. Thus, the compromised contractile function of the failing heart might be in part attributable to reduced cMyBP-C phosphorylation levels.
心肌肌球蛋白结合蛋白C（cMyBP-C）是心脏收缩力的重要调节因子，蛋白激酶A（PKA）对其进行磷酸化是一种有助于在β-肾上腺素能刺激下增加心输出量的机制。目前尚不清楚心力衰竭是否会改变cMyBP-C的磷酸化。本研究测定了衰竭的人类心脏和犬类起搏诱导性心力衰竭模型中磷酸化cMyBP-C的水平。制备了一种针对cMyBP-C主要磷酸化位点（Ser-282）的多克隆抗体，并通过在心肌细胞和Langendorff灌注小鼠心脏中用异丙肾上腺素进行PKA磷酸化来确认其特异性。使用来自（i）终末期心力衰竭患者（hHF；n = 12）和非衰竭供体心脏（hNF；n = 6）以及（ii）快速起搏诱导的终末期心力衰竭犬（dHF；n = 10）和假手术对照组（dNF；n = 10）的左心室心肌组织，通过蛋白质印迹法对总cMyBP-C和磷酸化cMyBP-C进行定量。hHF和hNF以及dHF和dNF中的总cMyBP-C蛋白水平相似。相比之下，hHF中磷酸化cMyBP-C与总cMyBP-C水平的比率降低了>50%，dHF中降低了>40%。总之，在人类和实验性心力衰竭中，cMyBP-C的磷酸化水平显著降低。因此，衰竭心脏收缩功能受损可能部分归因于cMyBP-C磷酸化水平降低。
