结蛋白相关心肌病转基因小鼠闰盘重塑

Intercalated disc remodeling in a transgenic mouse model of desmin-related cardiomyopathy

目的 探讨结蛋白相关心肌病 (DRC)闰盘相关蛋白表达和分布的变化。方法 以 1个月DRC转基因小鼠为模型 ,采用Western印迹和免疫标记共聚焦显微镜观察闰盘相关蛋白在心室中的表达和分布。结果 与野生型结蛋白转基因小鼠和非转基因小鼠相比 ,突变型结蛋白小鼠 pan cadherin、α catenin、β catenin总蛋白升高 (P <0 0 5 ) ;α catenin和 β catenin以胞浆部分显著 (P <0 0 5 ) ;pan cadherin膜蛋白部分和胞浆部分升高 (P <0 0 5 ) ,而细胞骨架蛋白 (TIF)部分降低 ;Cx4 3总蛋白和TIF则明显降低 (P <0 0 5 ) ,存在着再分布。野生型结蛋白小鼠与非转基因小鼠比较 ,各蛋白均无显著变化。免疫标记证实这一结果。结论 DRC早期已发生闰盘重塑 ,闰盘蛋白表达和分布改变可能促进心律失常和心功能衰竭的发生。

Objective To investigate the changes of the intercalated disc in the heart with desmin-related cardiomyopathy. Methods One month old transgenic mice expressing either a 7-amino acid (R173-E179) deletion desmin (D7-des) or wild type desmin (WT-des) specifically in the heart were used for analyzing the intercalated disc proteins. Total lysate and Triton extractions from ventricles were immunoblotted for pan-cadherin, α-catenin, β-catenin, γ-catenin, connexin40 (Cx40), Cx43 and Cx45. Frozen ventricular sections from D7-des and non-transgenic littermate mice (NTG) were immunofluorescence labeled for the same antibodies and visualized by confocal microscopy. Results Compared with WT-des or NTG, immunoblotting of total myocardium homogenates revealed that expression of pan-cadherin, α-catenin, and β-catenin was increased significantly while total Cx43 was significantly decreased in D7-des (P<0.05). Pan-cadherin was up in both cytosolic fraction (CF) and the membrane skeleton fraction (MSF), and down in TritonX-100 insoluble fraction (TIF); α-catenin and β-catenin were up especially in CF. Marked reduction of Cx43 in TIF was observed in D7-des group (P<0.05). However, expression of γ-catenin and Cx45 was not significantly altered (P>0.05). Cx40 was not detectable among three groups. No differences in expression of the intercalated disc proteins were seen between WT-des and NTG (P>0.05). Confocal microscopy of hearts verified the same results. Fluorescence density of pan-cadherin, α-catenin, and β-catenin was up and Cx43 was down and distributed heterogeneously in D7-des. Conclusion Disruption of the desmin filament network by abnormal desmin aggregation appears to cause significant remodeling of the intercalated disc in the early stage of desmin-related cardiomyopathy. Altered expression of the intercalated disc proteins may contribute to arrhythmias and contractile dysfunction in desmin-related cardiomyopathy.