The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Ji'nan, Shandong Province, China.
Int J Biochem Cell Biol. 2013 Sep;45(9):2027-35. doi: 10.1016/j.biocel.2013.06.018. Epub 2013 Jul 2.
Cardiomyocyte apoptosis is an important pathological change of diabetic cardiomyopathy. How the elevated glucose levels cause cell apoptosis remains unknown. The aim of our study was to investigate whether activin receptor-like kinase 7 (ALK7)-Smad2/3 signaling pathway plays an important role in high glucose-induced cardiomyocyte apoptosis. H9c2 cardiomyoblasts and neonatal rat cardiomyocytes were treated with 33mmol/l glucose. The expression of ALK7, Smad2 and Smad3 were inhibited by small interfering RNA respectively. The level of ALK7, total Smad2/3, phosphorylated Smad2/3, B-cell lymphoma-2 (Bcl-2) and cleaved Caspase3 were evaluated using western blot. The apoptosis rate was detected by flow cytometer. High glucose treatment caused the apoptosis of H9c2 cardiomyocyte and the inhibition of Smad2 or Smad3 attenuated this apoptosis. ALK7 existed in both H9c2 cardiomyoblasts and neonatal rat cardiomyocytes and high ambient glucose upregulated its expression. The increased expression level of cleaved Caspase3 and apoptosis rate and decreased expression of Bcl-2 were reversed after ALK7 was inhibited. The expression of phosphorylated Smad2/3 also decreased after the knockdown of ALK7. Our findings suggest that ALK7 mediates high ambient glucose-induced H9c2 cardiomyoblasts apoptosis through the activation of Smad2/3.
心肌细胞凋亡是糖尿病心肌病的重要病理变化。高血糖如何导致细胞凋亡尚不清楚。本研究旨在探讨激活素受体样激酶 7（ALK7）-Smad2/3 信号通路在高糖诱导的心肌细胞凋亡中是否起重要作用。用 33mmol/l 葡萄糖处理 H9c2 心肌细胞和新生大鼠心肌细胞。用小干扰 RNA 分别抑制 ALK7、Smad2 和 Smad3 的表达。用 Western blot 检测 ALK7、总 Smad2/3、磷酸化 Smad2/3、B 细胞淋巴瘤-2（Bcl-2）和裂解 Caspase3 的水平。用流式细胞仪检测细胞凋亡率。高糖处理可导致 H9c2 心肌细胞凋亡，抑制 Smad2 或 Smad3 可减轻这种凋亡。ALK7 存在于 H9c2 心肌细胞和新生大鼠心肌细胞中，高环境葡萄糖可上调其表达。抑制 ALK7 后，裂解 Caspase3 的表达水平增加和凋亡率降低以及 Bcl-2 的表达减少得到逆转。ALK7 敲低后，磷酸化 Smad2/3 的表达也降低。我们的研究结果表明，ALK7 通过激活 Smad2/3 介导高环境葡萄糖诱导的 H9c2 心肌细胞凋亡。
