Insulin-Induced Dephosphorylation of C/EBP{alpha}

doi:10.1126/stke.1999.11.tw3

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Sci. STKE, 7 December 1999
Vol. 1999, Issue 11, p. tw3
[DOI: 10.1126/stke.1999.11.tw3]

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TRANSCRIPTION Insulin-Induced Dephosphorylation of C/EBP ${alpha}$

Abstract: The transcription factor C/EBP ${alpha}$ is critical for normal adiposetissue development and metabolism. When it is inhibited ornot expressed, adipocytes fail to take up glucose in responseto insulin. In normal adipocytes, insulin causes a decreasein the expression, activity, and phosphorylation of C/EBP ${alpha}$ . Ross et al. demonstrate that two threonine residues in a conservedregion of this transcription factor are phosphorylated by aglycogen synthase kinase (GSK3) in vivo and in vitro. Dephosphorylationof C/EBP ${alpha}$ not only involved inactivation of GSK3, but also theactivation of the protein phosphatases PP1 and PP2A, enzymesknown to be activated by insulin. Hence, a decrease in thephosphorylation of this transcription factor in response toinsulin involves two mechanisms. Phosphorylation also alteredaccessibility of C/EBP ${alpha}$ to proteases, suggesting that its stateof phosphorylation may regulate interaction with other nuclearproteins or transcriptional coactivators. However, the preciserole of this modification remains to be determined. The reportsuggests a signaling mechanism in adipocytes through which C/EBP ${alpha}$ is regulated by insulin.

Ross, S.E., Erickson, R.L., Hemati, N., and MacDougald, O.A. (1999) Glycogen synthase kinase 3 is an insulin-regulatedC/EBP ${alpha}$ kinase. Mol. Cell. Biol. 19: 8433-8441. [Online Journal]

Citation: Insulin-Induced Dephosphorylation of C/EBP ${alpha}$ . Sci. STKE 1999, tw3 (1999).

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