Cathepsin S, but not cathepsin L, participates in the MHC class II-associated invariant chain processing in large yellow croaker (Larimichthys crocea).
Cathepsin S, but not cathepsin L, participates in the MHC class II-associated invariant chain processing in large yellow croaker (Larimichthys crocea).
复制标题
DOI：
10.1016/j.fsi.2015.10.009
复制
发表时间：
2015-12
影响因子：
4.7
通讯作者：
Qiuhua Li;J. Ao;Yinnan Mu;Zhijun Yang;Ting Li;Xin Zhang;Xinhua Chen
中科院分区：
文献类型：
--
作者：
Qiuhua Li;J. Ao;Yinnan Mu;Zhijun Yang;Ting Li;Xin Zhang;Xinhua Chen
组织蛋白酶S（CatS）和组织蛋白酶L（CatL）是哺乳动物中参与恒定链（Ii链）加工的关键酶。然而，很少有人知道的鱼组织蛋白酶的Ii链加工中的作用。本研究对大黄鱼组织蛋白酶S（LycCatS）和L（LycCatL）进行了鉴定和表征。序列比较和系统发育分析表明，LycCatS和LycCatL与硬骨鱼类中的相应序列高度保守。这两种组织蛋白酶组成型表达在所有组织和免疫相关细胞测试，虽然在不同的水平。重组LycCatS（rLycCatS）和LycCatL（rLycCatL）都具有典型的半胱氨酸蛋白酶活性。与其他哺乳动物内肽酶组织蛋白酶一样，rLycCatS和rLycCatL可以自催化活化以除去前肽并释放活性成熟肽。另一方面，重组大黄鱼Ii链（rLyc-TR-Ii）可抑制rLycCatL的自催化活性，而对rLycCatS的自催化活性无影响。此外，活化的rLycCatS在体外能以逐步的方式有效地加工rLyc-TR-Ii，而活化的rLycCatL不能。这些数据表明，组织蛋白酶S可能是主要的组织蛋白酶参与的Ii链加工的硬骨鱼。
Two cysteine proteases, cathepsin S (CatS) and cathepsin L (CatL), have been identified as the key enzymes involved in the processing of invariant chain (Ii chain) in mammals. However, little is known about the roles of fish cathepsins in the Ii chain processing. In this study, large yellow croaker cathepsin S (LycCatS) and L (LycCatL) were identified and characterized. Based on the sequence comparison and phylogenetic analysis, both LycCatS and LycCatL are highly conserved to their counterparts in teleost. These two cathepsins were constitutively expressed in all tissues and immune-related cells tested, although at different levels. Both recombinant LycCatS (rLycCatS) and LycCatL (rLycCatL) possess the typical cysteine protease activity. Like other mammalian endopeptidase cathepsins, rLycCatS and rLycCatL could be autocatalytically activated to remove propeptides and release active mature peptides. On the other hand, the autocatalytic activation of rLycCatL could be inhibited by recombinant large yellow croaker Ii chain (rLyc-TR-Ii), but the autocatalytic activation of rLycCatS was not affected by rLyc-TR-Ii. Furthermore, the activated rLycCatS can efficiently process rLyc-TR-Ii in a stepwise mannerin vitro, while the activated rLycCatL can not. These data indicate that cathepsin S may be the main cathepsin involved in the Ii chain processing in bony fish.