Biological behaviors of mutant proinsulin contribute to the phenotypic spectrum of diabetes associated with insulin gene mutations.
Biological behaviors of mutant proinsulin contribute to the phenotypic spectrum of diabetes associated with insulin gene mutations.
复制标题
突变胰岛素原的生物学行为有助于与胰岛素基因突变相关的糖尿病表型谱
DOI：
10.1016/j.mce.2020.111025
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发表时间：
2020-12-01
影响因子：
4.1
通讯作者：
Huang Y
中科院分区：
文献类型：
--
作者：
Wang H;Saint-Martin C;Xu J;Ding L;Wang R;Feng W;Liu M;Shu H;Fan Z;Haataja L;Arvan P;Bellanné-Chantelot C;Cui J;Huang Y
胰岛素基因突变是新生儿糖尿病（NDM）的第二大最常见原因。它也是年轻（Mody）成熟 - 发作性糖尿病的基因之一。我们旨在研究可能与糖尿病表型的临床光谱相关的不同INS基因变异的分子行为。在这项研究中，我们集中于两个先前未表征的Mody引起的突变体，Proinsulin-p.gly444arg [g（b20）R]和P.Pro52leu [P（B28）L]（在一个法国家族中鉴定出的新型突变体）和nDM引起proinsulin-p。（cys96tyr）[c（a7）y]。我们发现，这些促硫蛋白突变体在内质网（ER）中表现出受损的氧化折叠，而ER出口，ER应激和凋亡则表现出氧化折叠。重要的是，蛋白酶突变体形成异常的分子间二硫键，不仅涉及突变蛋白，而且还涉及共表达的WT-胰岛素，形成了错误折叠的二硫键链接的蛋白酶络合物。这损害了WT-胰岛素的细胞内运输，并限制了生物活性成熟胰岛素的产生。值得注意的是，尽管所有三个突变体在折叠，运输和主要的负面行为方面都存在相似的缺陷，但这些缺陷的程度似乎不同。具体而言，与Mody突变体G（B20）R和P（B28）L相比，部分影响共表达WT-ProInsusin的折叠和运输，NDM突变体C（A7）y几乎完全阻止了ER的ER导出WT-胰岛素，减少胰岛素的产生，诱导更严重的ER应激和凋亡。因此，我们证明了不同蛋白突变体之间细胞生物学行为的差异与由不同的INS基因突变引起的糖尿病表型相关。
Insulin gene mutation is the second most common cause of neonatal diabetes (NDM). It is also one of the genes involved in maturity-onset diabetes of the young (MODY). We aim to investigate molecular behaviors of different INS gene variants that may correlate with the clinical spectrum of diabetes phenotypes. In this study, we concentrated on two previously uncharacterized MODY-causing mutants, proinsulin-p.Gly44Arg [G(B20)R] and p.Pro52Leu [P(B28)L] (a novel mutant identified in one French family), and an NDM causing proinsulin-p.(Cys96Tyr) [C(A7)Y]. We find that these proinsulin mutants exhibit impaired oxidative folding in the endoplasmic reticulum (ER) with blocked ER export, ER stress, and apoptosis. Importantly, the proinsulin mutants formed abnormal intermolecular disulfide bonds that not only involved the mutant proinsulin, but also the co-expressed WT-proinsulin, forming misfolded disulfide-linked proinsulin complexes. This impaired the intracellular trafficking of WT-proinsulin and limited the production of bioactive mature insulin. Notably, although all three mutants presented with similar defects in folding, trafficking, and dominant negative behavior, the degrees of these defects appeared to be different. Specifically, compared to MODY mutants G(B20)R and P(B28)L that partially affected folding and trafficking of co-expressed WT-proinsulin, the NDM mutant C(A7)Y resulted in an almost complete blockade of the ER export of WT-proinsulin, decreasing insulin production, inducing more severe ER stress and apoptosis. We thus demonstrate that differences in cell biological behaviors among different proinsulin mutants correlate with the spectrum of diabetes phenotypes caused by the different INS gene mutations.