Comparison of Lp82- and m-calpain-mediated proteolysis during cataractogenesis in Shumiya cataract rat (SCR)
Comparison of Lp82- and m-calpain-mediated proteolysis during cataractogenesis in Shumiya cataract rat (SCR)
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DOI：
10.1076/ceyr.25.4.207.13486
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发表时间：
2002-01
影响因子：
2
通讯作者：
M. Inomata;M. Hayashi;Yoshimasa Ito;Y. Matsubara;M. Takehana;S. Kawashima;S. Shumiya
中科院分区：
文献类型：
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作者：
M. Inomata;M. Hayashi;Yoshimasa Ito;Y. Matsubara;M. Takehana;S. Kawashima;S. Shumiya
目的.众所周知，m-钙蛋白酶是一种普遍存在的钙蛋白酶，参与啮齿动物透镜中白内障的形成。晶状体特异性钙蛋白酶Lp 82也参与了白内障的形成。然而，Lp 82介导的蛋白水解和透镜混浊之间的确切关系尚未建立。因此，我们比较了白内障形成过程中Lp 82和m-钙蛋白酶介导的aA-晶状体蛋白的蛋白水解，以阐明Lp 82是否参与白内障形成。方法.为了分析Lp 82和m-钙蛋白酶介导的蛋白水解，我们开发了分别对由Lp 82和m-钙蛋白酶作用产生的α A-晶状体蛋白的蛋白水解产物特异的抗体。采用Western blotting和免疫组织化学染色方法，分析晶状体囊膜中Lp 82和m-calpain对晶状体蛋白的蛋白水解作用。结果虽然m-钙蛋白酶介导的蛋白水解主要在白内障晶状体中检测到，但Lp 82介导的蛋白水解不仅在白内障晶状体中检测到，而且在正常晶状体中检测到。m-钙蛋白酶介导的蛋白水解在发展和注定发展浑浊的限制区域中观察到，即，透镜的核和核周区域。另一方面，Lp 82介导的蛋白水解不仅在相同的区域中观察到，而且在不透明的皮质区域中也观察到。与m-钙蛋白酶介导的蛋白水解不同，Lp 82介导的蛋白水解不受口服氨基胍（AG）的抑制，氨基胍（AG）可防止透镜混浊。结论.从这些结果，它表明，有没有直接的贡献Lp 82介导的蛋白水解白内障形成的SCR。相反，由于Lp 82介导的蛋白水解发生在正常透镜的皮质区，因此Lp 82可能在生理条件下透镜成熟期间的纤维细胞发育和/或纤维细胞重塑中起作用。
Purpose. It is well known that m-calpain, a ubiquitous calpain, is involved in cataract formation in rodent lens. Involvement of Lp82, a lens-specific calpain, in the cataract formation is also suggested. However, the exact relationship between Lp82-mediated proteolysis and lens opacification has not yet been established. We therefore compared Lp82-and m-calpain-mediated proteolyses of aA-crystallin during cataractogenesis to clarify whether Lp82 is involved in cataract formation. Methods. In order to analyze the Lp82- and m-calpain-mediated proteolyses, we developed antibodies exclusively specific to the proteolytic products of aA-crystallin produced by Lp82 and m-calpain actions, respectively. The proteolytic profiles of aA-crystallin by Lp82 and m-calpain during cataractogenesis in SCR lenses were analyzed by Western blotting and immunohistochemical staining. Results. While m-calpain-mediated proteolysis was detected predominantly in cataractous lenses, Lp82-mediated proteolysis was detected not only in cataractous but in normal lenses. The m-calpain-mediated proteolysis was observed in restricted areas developing and destined to develop opacification, i.e., the nuclear and perinuclear regions of lens. On the other hand, Lp82-mediated proteolysis was observed not only in the same regions but also in the cortical region where opacity does not develop. Unlike m-calpain-mediated proteolysis, Lp82-mediated proteolysis was not inhibited by the oral administration of aminoguanidine (AG), which acts to prevent lens opacification. Conclusions. From these results, it is shown that there is no direct contribution of Lp82-mediated proteolysis to cataract formation in SCR. Rather, Lp82 may function in fiber cell development and/or fiber cell remodeling during lens maturation under physiological conditions, since Lp82-mediated proteolysis occurs in the cortical region of normal lens.