Functional consequences of the mutations in human cardiac troponin I gene found in familial hypertrophic cardiomyopathy
Functional consequences of the mutations in human cardiac troponin I gene found in familial hypertrophic cardiomyopathy
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DOI：
10.1006/jmcc.2001.1473
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发表时间：
2001-12-01
影响因子：
5
通讯作者：
Ohtsuki, I
中科院分区：
文献类型：
--
作者：
Takahashi-Yanaga, F;Morimoto, S;Ohtsuki, I
利用纯化的重组人cTnI研究了引起家族性肥厚性心肌病（HCM）的心肌肌钙蛋白I （cTnI）中6个突变（R145G、R145Q、R162W、DeltaK183、G203S、K206Q）的功能后果。cTnI抑制区的错义突变R145G和R145Q降低了cTnI的内在抑制活性，但不改变cTnI对actin的表观亲和力。另一方面。第二肌钙蛋白C结合区的错义突变R162W和第二肌动蛋白-原肌球蛋白区附近的缺失突变DeltaK183降低了cTnI对肌动蛋白的表观亲和力，但不改变其内在抑制活性。荧光探针标记的人心脏肌钙蛋白C （cTnC）的Ca2+滴定显示，只有R162W突变破坏了cTnC- ctni的相互作用，决定了cTnC n端调控域的Ca2+亲和力。将人心脏肌钙蛋白交换到分离的心肌原纤维或皮肤心肌纤维中显示突变R145G， R145Q。R162W、DeltaK183和K206Q诱导皮肤肌纤维中肌纤维atp酶活性的Ca2+敏感性和力的产生明显增加。虽然突变G203S在肌原纤维和皮肤肌纤维中也表现出增加Ca2+敏感性的趋势，但与野生型cTnI相比，没有统计学意义上的差异。这些结果表明，大多数hcm相关的cTnI突变确实影响涉及cTnI分子的调控过程，并且至少有5个突变（R145G, R145Q, R162W, AK183, K206Q）增加了心肌收缩的Ca2+敏感性。(C) 2001学术出版社。
Functional consequences of the six mutations (R145G, R145Q, R162W, DeltaK183, G203S, K206Q) in cardiac troponin I (cTnI) that cause familial hypertrophic cardiomyopathy (HCM) were studied using purified recombinant human cTnI. The missense mutations R145G and R145Q in the inhibitory region of cTnI reduced the intrinsic inhibitory activity of cTnI without changing the apparent affinity for actin. On the other hand. the missense mutation R162W in the second troponin C binding region and the deletion mutation DeltaK183 near the second actin-tropomyosin region reduced the apparent affinity of cTnI for actin without changing the intrinsic inhibitory activity. Ca2+ titration of a fluorescent probe-labeled human cardiac troponin C (cTnC) showed that only R162W mutation impaired the cTnC-cTnI interaction determining the Ca2+ affinity of the N-terminal regulatory domain of cTnC, Exchanging the human cardiac troponin into isolated cardiac myofibrils or skinned cardiac muscle fibers showed that the mutations R145G, R145Q. R162W, DeltaK183 and K206Q induced a definite increase in the Ca2+-sensitivity of myofibrillar ATPase activity and force generation in skinned muscle fibers. Although the mutation G203S also showed a tendency to increase the Ca2+ sensitivity in both myofibrils and skinned muscle fibers, no statistically significant difference compared with wild-type cTnI could be detected. These results demonstrated that most of the HCM-linked cTnI mutations did affect the regulatory processes involving the cTnI molecule, and that at least five mutations (R145G, R145Q, R162W, AK183, K206Q) increased the Ca2+ sensitivity of cardiac muscle contraction. (C) 2001 Academic Press.