First published online March 21, 2007
Journal of Cell Science 120, 702e (2007)
© The Company of Biologists Limited
Synapsin makes sweet moves
Glucose transport in adipocytes is controlled by regulating the number of glucose transporters - particularly the Glut4 isoform - at the cell surface. In response to insulin, Glut4 moves from an intracellular, vesicular pool to the plasma membrane. This insulin-stimulated exocytosis uses many proteins involved in other aspects of membrane trafficking but, as Cynthia Corley Mastick and colleagues report on p. 1168, it also involves synapsin IIb, a protein that helps to organize a reserve pool of synaptic vesicles in neuronal cells. The authors show that adipocytes express synapsin IIb and that it colocalizes with Glut4. Then, because phosphorylation of synapsins affects their function in synaptic vesicle trafficking, the authors use a non-phosphorylatable mutant (S10A synapsin IIb) to investigate whether synapsins are involved in Glut4 trafficking. They report that expression of S10A (but not wild-type) synapsin IIb in adipocytes increases the level of Glut4 on the basal cell surface fourfold. Together with other results, this finding indicates that synapsin IIb plays an important role in Glut4 traffic in adipocytes.
Related articles in JCS:
- Expression of a synapsin IIb site 1 phosphorylation mutant in 3T3-L1 adipocytes inhibits basal intracellular retention of Glut4
- Joseph M. Muretta, Irina Romenskaia, Patrick A. Cassiday, and Cynthia Corley Mastick
JCS 2007 120: 1168-1177.
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