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钙蛋白酶介导模拟失重大鼠心肌肌钙蛋白抑制亚基的降解

徐彭涛, 宋振, 李全, 张琳, 王云英, 余志斌^*

第四军医大学航空航天生理教研室，西安 710032

摘要

本文旨在观察尾部悬吊模拟失重大鼠心肌钙蛋白酶(calpain)与钙蛋白酶抑素(calpastatin)表达的变化，以探讨心肌肌钙蛋白抑制亚基(cardiac troponin I, cTnI)降解的可能机制。采用尾部悬吊模拟失重大鼠模型，Western blotting 技术观测心肌calpain-1、calpain-2 与calpastatin 的表达；PD150606 抑制calpain 活性，分析cTnI 降解程度的变化。结果显示：与同步对照组相比，悬吊2 周与4 周组大鼠心肌calpastatin 表达呈显著性降低(P<0.05)，calpain-1 表达未改变，calpain-2 表达略有降低；但是，心肌calpain-1/calpastatin 及calpain-2/calpastatin 的比值在悬吊2 周与4 周组明显增高(P<0.05, P<0.01)。悬吊4 周组cTnI 降解显著高于对照组(P<0.01)；然而，用 calpain 非特异性抑制剂PD150606 处理后，对照组及悬吊组cTnI的降解均被显著抑制(P<0.01)。这些结果提示模拟失重大鼠心肌calpain 活性增高可能增加cTnI 的降解。

关键词： 钙蛋白酶; 钙蛋白酶抑素; 心肌肌钙蛋白抑制亚基; 模拟失重; 蛋白降解

分类号：R337.2

[Calpain mediates cardiac troponin I degradation in tail-suspended rats.] [Ariticle in Chinese]

XU Peng-Tao, SONG Zhen, LI Quan, ZHANG Lin, WANG Yun-Ying, YU Zhi-Bin^*

Department of Aerospace Physiology, the Fourth Military Medical University, Xi'an 710032, China

Abstract

The aim of the present study was to investigate the expressions of calpain and calpastatin in the myocardium of simulated
weightlessness rats, and to elucidate the underlying mechanism of cardiac troponin I (cTnI) degradations. Tail-suspended (SUS) rats were
used as a simulated weightlessness model on the ground. The myocardium of rats was homogenized, and the expressions of calpain-1,
calpain-2, calpastatin and cTnI were analyzed by Western blotting technique. Calpastatin expression was significantly decreased in 2-
and 4-week SUS groups compared with that in the synchronous controls (P<0.05). Calpain-2 expression was slightly decreased, whereas
calpain-1 expression was unaltered in SUS groups. However, calpain-1/calpastatin and calpain-2/calpastatin ratios were increased after tailsuspension,
being significantly higher in 2- and 4-week SUS groups than those in the synchronous controls (P<0.05, P<0.01). Cardiac TnI
degradation was significantly increased after tail-suspension (P<0.01), but cTnI degradation in both SUS and control groups was
significantly inhibited by a non-specific inhibitor of calpain, PD150606 (P<0.01). These results suggest that an increase in calpain activity
may enhance cTnI degradation in the myocardium of tail-suspended rats.

Key words: calpain; calpastatin; cardiac troponin I; simulated weightlessness; protein degradation

收稿日期：2010-07-06　　录用日期：2010-08-04

通讯作者：余志斌　　E-mail: yuzhib@fmmu.edu.cn

引用本文：

徐彭涛, 宋振, 李全, 张琳, 王云英, 余志斌. 钙蛋白酶介导模拟失重大鼠心肌肌钙蛋白抑制亚基的降解[J]. 生理学报 2010; 62 (5): 415-420.

XU Peng-Tao, SONG Zhen, LI Quan, ZHANG Lin, WANG Yun-Ying, YU Zhi-Bin. [Calpain mediates cardiac troponin I degradation in tail-suspended rats.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (5): 415-420 (in Chinese with English abstract).