Cell Structure and Function
Online ISSN : 1347-3700
Print ISSN : 0386-7196
ISSN-L : 0386-7196
Internalization of AMPA-type Glutamate Receptor in the MIN6 Pancreatic β-cell Line
The Mon LaHiroshi YamadaSayaka SeirikiShun-AI LiKenshiro FujiseNatsuho KatsumiTadashi AbeMasami WatanabeKohji Takei
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2020 Volume 45 Issue 2 Pages 121-130

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Abstract

The activity of AMPA-type glutamate receptor is involved in insulin release from pancreatic β-cells. However, the mechanism and dynamics that underlie AMPA receptor-mediated insulin release in β-cells is largely unknown. Here, we show that AMPA induces internalization of glutamate receptor 2/3 (GluR2/3), AMPA receptor subtype, in the mouse β-cell line MIN6. Immunofluorescence experiments showed that GluR2/3 appeared as fine dots that were distributed throughout MIN6 cells. Intracellular GluR2/3 co-localized with AP2 and clathrin, markers for clathrin-coated pits and vesicles. Immunoelectron microscopy revealed that GluR2/3 was also localized at plasma membrane. Surface biotinylation and immunofluorescence measurements showed that addition of AMPA caused an approximate 1.8-fold increase in GluR2/3 internalization under low-glucose conditions. Furthermore, internalized GluR2 largely co-localized with EEA1, an early endosome marker. In addition, GluR2/3 co-immunoprecipitated with cortactin, a F-actin binding protein. Depletion of cortactin by RNAi in MIN6 cells altered the intracellular distribution of GluR2/3, suggesting that cortactin is involved in internalization of GluR2/3 in MIN6 cells. Taken together, our results suggest that pancreatic β-cells adjust the amount of AMPA-type GluR2/3 on the cell surface to regulate the receptive capability of the cell for glutamate.

Key words: endocytosis, GluR2, AMPA, cortactin, MIN6

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© 2020 The Author(s) CC-BY 4.0 (Submission before October 2016: Copyright © Japan Society for Cell Biology)

Copyright: ©2020 The Author(s). This is an open access article distributed under the terms of the Creative Commons BY (Attribution) License (https://creativecommons.org/licenses/by/4.0/legalcode), which permits the unrestricted distribution, reproduction and use of the article provided the original source and authors are credited.
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