Insulin Signalling: The Inside Story

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• 作者：Barry I. Posner ; OC ; CQ ; MD ; FRSC ; FRCPC ; FACP ; ^{barry.posner@mcgill.ca}
• 关键词：endosomal acidic insulinase ; endosomes ; insulin receptor ; phosphorylation ; phosphotyrosine phosphatase ; tyrosine kinase
• 刊名：Canadian Journal of Diabetes
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：41
• 期：1
• 页码：108-113
• 全文大小：1087 K
• 卷排序：41

文摘

Insulin signalling begins with binding to its cell surface insulin receptor (IR), which is a tyrosine kinase. The insulin receptor kinase (IRK) is subsequently autophosphorylated and activated to tyrosine phosphorylate key cellular substrates that are essential for entraining the insulin response. Although IRK activation begins at the cell surface, it is maintained and augmented following internalization into the endosomal system (ENS). The peroxovanadium compounds (pVs) were discovered to activate the IRK in the absence of insulin and lead to a full insulin response. Thus, IRK activation is both necessary and sufficient for insulin signalling. Furthermore, this could be shown to occur with activation of only the endosomal IRK. The mechanism of pV action was shown to be the inhibition of IRK-associated phosphotyrosine phosphatases (PTPs). Our studies showed that the duration and intensity of insulin signalling are modulated within ENS by the recruitment of cellular substrates to ENS; intra-endosomal acidification, which promotes dissociation of insulin from the IRK; an endosomal acidic insulinase, which degrades intra-endosomal insulin; and IRK-associated PTPs, which dephosphorylate and, hence, deactivate the IRK. Therefore, the internalization of IRKs is central to insulin signalling and its regulation.