心肌病心肌肌钙蛋白Ⅰ磷酸化及降解的初步研究

目的探讨心肌肌钙蛋白Ⅰ（cTnⅠ）在心室扩张、心力衰竭患者心肌组织中的磷酸化与降解及其信号通路调节。方法4例原发性扩张型心肌病患者。3例其他病因继发心室扩张,心脏移植术受体心脏,1例行双瓣膜置换及左心室改良术,部分左心室切除心肌组织。6例正常心脏。分别行光镜、电镜病理学检测,Western blot方法检测左心室心肌组织cTnⅠ磷酸化、去磷酸化,cTnⅠ降解片段及蛋白激酶C（PKC）表达,甘油醛-3-磷酸脱氢酶（GAPDH）作为内参半定量。结果扩张左心室心肌内均检测到cTnⅠ表达及降解片段,正常左心室心肌内均可见cTnⅠ表达,未见降解条带。扩张左心室心肌均有明显磷酸化cTnⅠ表达,半定量结果均明显高于正常对照组（P〈0．05）,两组心肌病表达比较差异无统计学意义。扩张左心室心肌内均可见程度不同的去磷酸化cTnⅠ表达,正常组未出现明显去磷酸化cTnⅠ表达。扩张左心室及正常对照组左心室心肌组织内均未检测到明显的PKCβ1、PKCβ2表达。结论扩张心室心肌组织内cTnⅠ降解片段的存在可能与心肌病变的发生、发展有关,并在长期慢性心功能的损害中起重要作用。衰竭心肌组织内cTnⅠ磷酸化程度显著增强,PKCβ1、PKCβ2与其磷酸化程度增高可能不相关。

Association between cardiac troponin I phosphorylation/degradation and cardiomyopathies

OBJECTIVE: To investigate the association between cTnI phosphorylation/degradation and cardiomyopathies in extransplanted myocardium. METHODS: cTnI phosphorylation and degradation as well as PKC (beta1, beta2) expressions were determined in extransplanted hearts from patients with cardiomypathies (n = 8) and from traffic accidents (n = 6) by Western blot. RESULTS: The cTnI bands were observed in LV myocardium of cardiomyopathy patients and normal myocardium while and cTnI degradation bands were only detected in LV myocardium from patients with cardiomyopathies. The phosphorylated cTnI bands were significantly upregulated in LV myocardium of cardiomyopathy patients compared to normal myocardium (P < 0.05). There was no myocardial PKCbeta1, PKCbeta2 expression in all examined hearts. CONCLUSION: The cTnI degradation products and increased phosphorylated cTnI expression are likely involved in the pathogenesis and development of cardiomyopathy.