脂肪细胞质膜上的 GLUT4 散布:超分辨率之旅。

GLUT4 dispersal at the plasma membrane of adipocytes: a super-resolved journey.

机构信息

Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, U.K.

Department of Biology, University of York, Heslington, York, U.K.

出版信息

Biosci Rep. 2023 Oct 31;43(10). doi: 10.1042/BSR20230946.

Abstract

In adipose tissue, insulin stimulates glucose uptake by mediating the translocation of GLUT4 from intracellular vesicles to the plasma membrane. In 2010, insulin was revealed to also have a fundamental impact on the spatial distribution of GLUT4 within the plasma membrane, with the existence of two GLUT4 populations at the plasma membrane being defined: (1) as stationary clusters and (2) as diffusible monomers. In this model, in the absence of insulin, plasma membrane-fused GLUT4 are found to behave as clusters. These clusters are thought to arise from exocytic events that retain GLUT4 at their fusion sites; this has been proposed to function as an intermediate hub between GLUT4 exocytosis and re-internalisation. By contrast, insulin stimulation induces the dispersal of GLUT4 clusters into monomers and favours a distinct type of GLUT4-vesicle fusion event, known as fusion-with-release exocytosis. Here, we review how super-resolution microscopy approaches have allowed investigation of the characteristics of plasma membrane-fused GLUT4 and further discuss regulatory step(s) involved in the GLUT4 dispersal machinery, introducing the scaffold protein EFR3 which facilitates localisation of phosphatidylinositol 4-kinase type IIIα (PI4KIIIα) to the cell surface. We consider how dispersal may be linked to the control of transporter activity, consider whether macro-organisation may be a widely used phenomenon to control proteins within the plasma membrane, and speculate on the origin of different forms of GLUT4-vesicle exocytosis.

摘要

在脂肪组织中,胰岛素通过介导 GLUT4 从细胞内囊泡向质膜的易位来促进葡萄糖摄取。2010 年,胰岛素被揭示对质膜中 GLUT4 的空间分布也有根本影响,质膜中有两种 GLUT4 群体存在:(1) 作为固定簇,(2) 作为可扩散单体。在这个模型中,在没有胰岛素的情况下,质膜融合的 GLUT4 被发现表现为簇。这些簇被认为是由保留 GLUT4 在融合部位的出胞事件产生的;这被认为是 GLUT4 出胞和再内化之间的中间枢纽。相比之下,胰岛素刺激诱导 GLUT4 簇分散成单体,并有利于一种独特类型的 GLUT4-囊泡融合事件,称为融合释放出胞作用。在这里,我们回顾了超分辨率显微镜方法如何允许研究质膜融合的 GLUT4 的特性,并进一步讨论了 GLUT4 分散机制涉及的调节步骤,引入了支架蛋白 EFR3,它将磷脂酰肌醇 4-激酶 IIIα (PI4KIIIα) 定位到细胞表面。我们考虑了分散如何与转运体活性的控制相关,是否宏观组织可能是一种广泛用于控制质膜内蛋白质的现象,并推测不同形式的 GLUT4-囊泡出胞作用的起源。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/ebe4/10600063/aa6da087baf4/bsr-43-bsr20230946-g1.jpg

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