DHHC7 Palmitoylates Glucose Transporter 4 (Glut4) and Regulates Glut4 Membrane Translocation

Keyong Du,Shoko Murakami,Yingmin Sun,Casey L Kilpatrick,Bernhard Luscher

doi:10.1074/jbc.m116.747139

Keyong Du, Shoko Murakami + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m116.747139

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Abstract

Insulin-dependent translocation of glucose transporter 4 (Glut4) to the plasma membrane plays a key role in the dynamic regulation of glucose homeostasis. We recently showed that this process is critically dependent on palmitoylation of Glut4 at Cys-223. To gain further insights into the regulation of Glut4 palmitoylation, we set out to identify the palmitoyl acyltransferase (PAT) involved. Here we report that among 23 mammalian DHHC proteins, DHHC7 is the major Glut4 PAT, based on evidence that ectopic expression of DHHC7 increased Glut4 palmitoylation, whereas DHHC7 knockdown in 3T3-L1 adipocytes and DHHC7 KO in adipose tissue and muscle decreased Glut4 palmitoylation. Moreover, inactivation of DHHC7 suppressed insulin-dependent Glut4 membrane translocation in both 3T3-L1 adipocytes and primary adipocytes. Finally, DHHC7 KO mice developed hyperglycemia and glucose intolerance, thereby confirming that DHHC7 represents the principal PAT for Glut4 and that this mechanism is essential for insulin-regulated glucose homeostasis.

Highlights

Insulin-dependent translocation of glucose transporter 4 (Glut4) to the plasma membrane plays a key role in the dynamic regulation of glucose homeostasis
Given our previous findings that overexpression palmitoyl acyltransferase (PAT) can form stable complexes with cognate substrates on overexpression in HEK cells [14], we examined whether DHHC proteins form similar substrates with Glut4
Because DHHC3 and -7, but not DHHC2 and -15, showed strong interaction with Glut4 (Fig. 1B), our first conclusion was that DHHC3 and DHHC7 might represent PATs for Glut4

Summary

Introduction

Insulin-dependent translocation of glucose transporter 4 (Glut4) to the plasma membrane plays a key role in the dynamic regulation of glucose homeostasis. To determine whether the increase in Glut4 palmitoylation contributes to Glut4 plasma membrane (PM) translocation, we examined the impact of ectopic expression of DHHC3 or DHHC7 on the level of Glut4 in the PM of CHO-IR cells. CHO-IR cells were transduced with adenoviral vectors that simultaneously express HA-Glut4 and either scrambled shRNA or DHHC7 shRNA followed by treatment with or without 10 nM insulin for 15 min.

Results

Conclusion