Hypophosphorylation of the Stiff N2B Titin Isoform Raises Cardiomyocyte Resting Tension in Failing Human Myocardium
Hypophosphorylation of the Stiff N2B Titin Isoform Raises Cardiomyocyte Resting Tension in Failing Human Myocardium
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DOI：
10.1161/circresaha.108.193326
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发表时间：
2009-03-27
影响因子：
20.1
通讯作者：
Paulus, Walter J.
中科院分区：
文献类型：
--
作者：
Borbely, Attila;Falcao-Pires, Ines;Paulus, Walter J.
衰竭心肌的高舒张刚度是由间质纤维化和心肌细胞静息张力（F-被动）升高引起的。肌联蛋白亚型表达从N2 BA转变为N2 B亚型，肌联蛋白的整体磷酸化降低，肌联蛋白磷酸化从N2 B转变为N2 BA亚型，可以提高心肌细胞的F-钝化。因此，在心力衰竭（HF）患者、主动脉瓣狭窄（AS）患者和对照组（CON）的左心室活检中，我们将分离的心肌细胞的F-被动与肌联蛋白亚型的表达以及肌联蛋白和肌联蛋白亚型的磷酸化相关。通过经血管技术（44例HF，3例CON）、围手术期（25例AS，4例CON）或从心脏瓣膜（4例HF，8例CON）获得活检。无冠状动脉疾病。将分离的透化心肌细胞拉伸至2.2 μ m肌节长度以测量F被动。使用凝胶电泳用ProQ Diamond和SYPRO Ruby染色分析肌联蛋白同种型的表达和磷酸化，并报告为肌联蛋白（N2 BA/N2 B）或磷酸化肌联蛋白（P-N2 BA/P-N2 B）同种型的比率。HF组的F被动（6.1 +/- 0.4 kN/m2）高于CON组（2.3 +/- 0.3 kN/m2; P < 0.01）或AS组（2.2 +/- 0.2 kN/m2; P < 0.001）。肌联蛋白亚型表达在HF（N2 BA/N2 B = 0.73 +/- 0.06）和CON（N2 BA/N2 B = 0.39 +/- 0.05; P < 0.001）之间不同，并且在HF和AS中相当（N2 BA/N2 B = 0.59 +/- 0.06）。总体肌联蛋白磷酸化在HF和AS中也是相当的，但是在HF（P-N2 BA/P-N2 B = 0.77 +/- 0.05）中刚性N2 B肌联蛋白同种型的相对磷酸化显著低于AS（P-N2 BA/P-N2 B = 0.54 +/- 0.05; P < 0.01）。刚性N2 B肌联蛋白亚型的相对低磷酸化是导致人HF心肌细胞F被动升高的新机制。(Circ Res. 2009; 104：780-786）。
High diastolic stiffness of failing myocardium results from interstitial fibrosis and elevated resting tension (F-passive) of cardiomyocytes. A shift in titin isoform expression from N2BA to N2B isoform, lower overall phosphorylation of titin, and a shift in titin phosphorylation from N2B to N2BA isoform can raise F-passive of cardiomyocytes. In left ventricular biopsies of heart failure (HF) patients, aortic stenosis (AS) patients, and controls (CON), we therefore related F-passive of isolated cardiomyocytes to expression of titin isoforms and to phosphorylation of titin and titin isoforms. Biopsies were procured by transvascular technique (44 HF, 3 CON), perioperatively (25 AS, 4 CON), or from explanted hearts (4 HF, 8 CON). None had coronary artery disease. Isolated, permeabilized cardiomyocytes were stretched to 2.2-mu m sarcomere length to measure Fpassive. Expression and phosphorylation of titin isoforms were analyzed using gel electrophoresis with ProQ Diamond and SYPRO Ruby stains and reported as ratio of titin (N2BA/N2B) or of phosphorylated titin (P-N2BA/P-N2B) isoforms. Fpassive was higher in HF (6.1 +/- 0.4 kN/m(2)) than in CON (2.3 +/- 0.3 kN/m2; P < 0.01) or in AS (2.2 +/- 0.2 kN/m2; P < 0.001). Titin isoform expression differed between HF (N2BA/N2B = 0.73 +/- 0.06) and CON (N2BA/N2B = 0.39 +/- 0.05; P < 0.001) and was comparable in HF and AS (N2BA/N2B = 0.59 +/- 0.06). Overall titin phosphorylation was also comparable in HF and AS, but relative phosphorylation of the stiff N2B titin isoform was significantly lower in HF (P-N2BA/P-N2B = 0.77 +/- 0.05) than in AS (P-N2BA/P-N2B = 0.54 +/- 0.05; P < 0.01). Relative hypophosphorylation of the stiff N2B titin isoform is a novel mechanism responsible for raised Fpassive of human HF cardiomyocytes. (Circ Res. 2009; 104: 780-786.)