View : 46 Download: 0

Transient changes in four GLUT4 compartments in rat adipocytes during the transition, insulin-stimulated to basal: Implications for the GLUT4 trafficking pathway

Title
Transient changes in four GLUT4 compartments in rat adipocytes during the transition, insulin-stimulated to basal: Implications for the GLUT4 trafficking pathway
Authors
Hah J.S.Ryu J.W.Lee W.Kim B.S.Lachaal M.Spangler R.A.Jung C.Y.
Ewha Authors
하종식
SCOPUS Author ID
하종식scopus
Issue Date
2002
Journal Title
Biochemistry
ISSN
0006-2960JCR Link
Citation
vol. 41, no. 48, pp. 14364 - 14371
Indexed
SCI; SCIE; SCOPUS scopus
Abstract
In rat adipocytes, insulin-induced GLUT4 recruitment to the plasma membrane (PM) is associated with characteristic changes in the GLUT4 contents of three distinct endosomal fractions, T, H, and L. The organelle-specific marker distribution pattern suggests that these endosomal GLUT4 compartments are sorting endosomes (SR), GLUT4-storage endosomes (ST), and GLUT4 exocytotic vesicules (EV), respectively, prompting us to analyze GLUT4 recycling based upon a four-compartment kinetic model. Our analysis revealed that insulin modulates GLUT4 trafficking at multiple steps, including not only the endocytotic and exocytotic rates, but also the two rate coefficients coupling the three intracellular compartments. This analysis assumes that GLUT4 cycles through PM T, H,L, and back to PM, in that order, with transitions characterized by four first-order coefficients. Values assigned to these coefficients are based upon the four steady-state GLUT4 pool sizes assessed under both basal and insulin stimulated states and the transition time courses observed in the plasma membrane GLUT4 pool. Here we present the first reported experimental measurements of transient changes in each of the four GLUT4 compartments during the insulin-stimulated to basal transition in rat adipocytes and compare these experimental results with the corresponding model simulations. The close correlation of these results offers clearq support for the general validity of the assumed model structure and the assignment of the T compartment to the sorting endosome GLUT4 pool. Variations in the recycling pathway from that of an unbranched cyclic topography are also considered in the light of these experimental observations. The possibility that H is a coupled GLUT4 storage compartment lying outside the direct cyclic pathway is contraindicated by the data. Okadaic acid-induced GLUT4 recruitment is accompanied by modulation of the rate coefficients linking individual endosomal GLUT4 compartments, further demonstrating a significant role of the endosomal pathways in GLUT4 exocytosis.
DOI
10.1021/bi026474n
Appears in Collections:
의과대학 > 의학과 > Journal papers
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE