Research ArticleCell Biology

Phosphorylation of the exocyst protein Exo84 by TBK1 promotes insulin-stimulated GLUT4 trafficking

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Sci. Signal.  21 Mar 2017:
Vol. 10, Issue 471, eaah5085
DOI: 10.1126/scisignal.aah5085

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Kinase for both inflammatory and insulin responses

After a meal, insulin released from the pancreas triggers glucose uptake by cells in part by promoting the translocation of the glucose transporter GLUT4 from intracellular vesicles to the plasma membrane. GLUT4 translocation requires a protein complex called the exocyst, which tethers GLUT4-containing vesicles to the plasma membrane. Uhm et al. found that the kinase TBK1, which mediates inflammatory responses, also phosphorylated exocyst subunits. These phosphorylation events were required for the fusion of GLUT4-containing vesicles with the plasma membrane. Insulin increased glucose uptake in adipocytes from wild-type mice but not in those from TBK1-deficient mice. The authors speculate that the involvement of TBK1 in insulin responses may be a means to counter the catabolic effects of inflammation.