Inhibition of glycogen synthase kinase-3 by insulin mediated by protein kinase B

DAE Cross, DR Alessi, P Cohen, M Andjelkovich… - Nature, 1995 - nature.com
Nature, 1995nature.com
Abstract GLYCOGEN synthase kinase-3 (GSK3) 1 is implicated in the regulation of several
physiological processes, including the control of glycogen2 and protein3 synthesis by
insulin, modulation of the transcription factors AP-1 and CREB4–6, the specification of cell
fate in Drosophila 7 and dorsoventral patterning in Xenopus embryos8. GSK3 is inhibited by
serine phosphorylation in response to insulin or growth factors3, 9–11 and in vitro by either
MAP kinase-activated protein (MAPKAP) kinase-1 (also known as p90rsk) or p70 ribosomal …
Abstract
GLYCOGEN synthase kinase-3 (GSK3)1 is implicated in the regulation of several physiological processes, including the control of glycogen2 and protein3 synthesis by insulin, modulation of the transcription factors AP-1 and CREB4–6, the specification of cell fate in Drosophila7 and dorsoventral patterning in Xenopus embryos8. GSK3 is inhibited by serine phosphorylation in response to insulin or growth factors3,9–11 and in vitro by either MAP kinase-activated protein (MAPKAP) kinase-1 (also known as p90rsk) or p70 ribosomal S6 kinase (p70S6k)12,13. Here we show, however, that agents which prevent the activation of both MAPKAP kinase-1 and p70S6k by insulin in vivo do not block the phosphorylation and inhibition of GSK3. Another insulin-stimulated protein kinase inactivates GSK3 under these conditions, and we demonstrate that it is the product of the proto-oncogene protein kinase B (PKB, also known as Akt/RAC). Like the inhibition of GSK3 (refs 10, 14), the activation of PKB is prevented by inhibitors of phosphatidylinositol (PI) 3-kinase.
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