Proinsulin maturation, misfolding, and proteotoxicity
Proinsulin maturation, misfolding, and proteotoxicity
复制标题
DOI：
10.1073/pnas.0702697104
复制
发表时间：
2007-10-02
影响因子：
11.1
通讯作者：
Arvan, Peter
中科院分区：
文献类型：
--
作者：
Liu, Ming;Hodish, Israel;Arvan, Peter
作为研究胰岛素原(PI)转运的工具，我们将绿色荧光蛋白(GFP)融合到C肽中，构建了人PI的cDNA。在含有适当的前激素转换酶的调节分泌细胞中，hProCPepGFP结构对CPepGFP和天然人胰岛素进行内切蛋白处理，并与内源性胰岛素平行检测和协同分泌。C(A7)Y突变PI的表达导致秋田小鼠常染色体显性糖尿病。我们直接鉴定了Akita胰岛中错误折叠的PI，还发现C(A7)Y突变体Pl，无论是否在hProCPepGFP嵌合体的背景下，都直接与非突变体PI的蛋白质复合体结合，损害了非突变体Pl的转运和恢复。这种捕获机制减少了P细胞中胰岛素的产生。此后，我们观察到13个细胞活力的丧失。这些数据表明，Pl的错误折叠导致非突变体131的内质网出口受损，可能是导致糖尿病发生和发展的连锁反应中的关键早期步骤。
As a tool to explore proinsulin (PI) trafficking, a human PI cDNA has been constructed with GFP fused within the C peptide. In regulated secretory cells containing appropriate prohormone convertases, the hProCpepGFP construct undergoes endoproteolytic processing to CpepGFP and native human insulin, which are specifically detected and cosecreted in parallel with endogenous insulin. Expression of C(A7)Y mutant PI results in autosomal dominant diabetes in Akita mice. We directly identify the misfolded PI in Akita islets and also showthatC(A7)Y mutant Pl, either in the context of the hProCpepGFP chimera or not, engages directly in protein complexes with nonmutant PI, impairing the trafficking and recovery of nonmutant Pl. This trapping mechanism decreases insulin production in P cells. Thereafter we observe a loss of 13 cell viability. The data imply that Pl misfolding leading to impaired endoplasmic reticulum exit of nonmutant 131 may be a key early step in a chain reaction of 13 cell dysfunction and demise leading to onset and progression of diabetes.