Glucosamine-induced insulin resistance is coupled to O-linked glycosylation of Munc18c

Guoli Chen, Ping Liu, Debbie C. Thurmond, Jeffrey S. Elmendorf

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Abstract

Evidence suggests that glucosamine inhibits distal components regulating insulin-stimulated GLUT4 translocation to the plasma membrane. Here we assessed whether key membrane docking and fusion events were targeted. Consistent with a plasma membrane-localized effect, 3T3-L1 adipocytes exposed to glucosamine displayed an increase in cell-surface O-linked glycosylation and a simultaneously impaired mobilization of GLUT4 by insulin. Analysis of syntaxin 4 and SNAP23, plasma membrane-localized target receptor proteins (t-SNAREs) for the GLUT4 vesicle, showed that they were not cell-surface targets of O-linked glycosylation. However, the syntaxin 4 binding protein, Munc18c, was targeted by O-linked glycosylation. This occurred concomitantly with a block in insulin-stimulated association of syntaxin 4 with its cognate GLUT4 vesicle receptor protein (v-SNARE), VAMP2. In conclusion, our data suggest that the mechanism by which glucosamine inhibits insulin-stimulated GLUT4 translocation involves modification of Munc18c.

Original languageEnglish (US)
Pages (from-to)54-60
Number of pages7
JournalFEBS Letters
Volume534
Issue number1-3
DOIs
Publication statusPublished - Jan 16 2003

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All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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