A prominent role of PDIA6 in processing of misfolded proinsulin
A prominent role of PDIA6 in processing of misfolded proinsulin
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DOI：
10.1016/j.bbapap.2016.03.002
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发表时间：
2016-06-01
影响因子：
3.2
通讯作者：
Purcell, Anthony W.
中科院分区：
文献类型：
--
作者：
Gorasia, Dhana G.;Dudek, Nadine L.;Purcell, Anthony W.
尽管胰岛素原在维持葡萄糖稳态中起着关键作用，但令人惊讶的是，人们对胰岛素原在内质网中的折叠知之甚少。在这项研究中，我们的目的是了解分子伴侣参与胰岛素原的成熟和降解。我们产生了表达FLAG标记的胰岛素原的胰腺β细胞系。几种分子伴侣（包括BiP，PDIA 6，钙连接蛋白，钙网蛋白，GRP 170，Erdj 3和ribophorin II）与胰岛素原共免疫沉淀，表明这些蛋白质在折叠中的作用。为了研究负责靶向错误折叠的胰岛素原以降解的分子伴侣，我们还创建了表达携带秋田突变（Cys 96 Tyr）的FLAG标记的胰岛素原的β细胞系。发现与野生型胰岛素原相关的所有分子伴侣也与秋田胰岛素原共免疫沉淀。然而，与秋田胰岛素原和大约10倍多的PDIA 6特异性沉淀的一种另外的蛋白质，即p58（IPK），而不是其它PDI家族成员，与秋田胰岛素原结合。后者表明PDIA 6可能作为一个关键的还原酶和靶向错误折叠的胰岛素原的ER-降解途径。PDIA 6与秋田胰岛素原的优先结合也在另一种β细胞系（β TC-6）中得到证实。此外，第一次证明了PDIA 6的生理学相关底物。因此，本研究已经鉴定了与野生型胰岛素原相关的几种分子伴侣/折叠酶，并且还为秋田错误折叠的胰岛素原提供了全面的相互作用组。皇冠版权所有（C）2016由Elsevier B. V.出版。保留所有权利。
Despite its critical role in maintaining glucose homeostasis, surprisingly little is known about proinsulin folding in the endoplasmic reticulum. In this study we aimed to understand the chaperones involved in the maturation and degradation of proinsulin. We generated pancreatic beta cell lines expressing FLAG-tagged proinsulin. Several chaperones (including BiP, PDIA6, calnexin, calreticulin, GRP170, Erdj3 and ribophorin II) co-immunoprecipitated with proinsulin suggesting a role for these proteins in folding. To investigate the chaperones responsible for targeting misfolded proinsulin for degradation, we also created a beta cell line expressing FLAG tagged proinsulin carrying the Akita mutation (Cys96Tyr). All chaperones found to be associated with wild type proinsulin also co-immunoprecipitated with Akita proinsulin. However, one additional protein, namely p58(IPK), specifically precipitated with Akita proinsulin and approximately ten fold more PDIA6, but not other PDI family members, was bound to Akita proinsulin. The latter suggests that PDIA6 may act as a key reductase and target misfolded proinsulin to the ER-degradation pathway. The preferential association of PDIA6 to Akita proinsulin was also confirmed in another beta cell line (beta TC-6). Furthermore, for the first time, a physiologically relevant substrate for PDIA6 has been evidenced. Thus, this study has identified several chaperones/foldases that associated with wild type proinsulin and has also provided a comprehensive interactome for Akita misfolded proinsulin. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.