Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 283, Issue 41, Pages 27653-27667Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M802623200
Keywords
-
Categories
Funding
- Medical Research Council
- AstraZeneca
- Boehringer-Ingelheim
- GlaxoSmithKline
- Merck
- Pfizer
- Swedish Wenner-Gren Foundations
- European Commission [LSHM-CT-20004-005272]
- Diabetes Research and Wellness Foundation
- Merck KGaA
- Diabetes UK
- MRC [MC_U127088492, G9403619, MC_U127015387] Funding Source: UKRI
- Medical Research Council [G9403619, MC_U127088492, MC_U127015387] Funding Source: researchfish
Ask authors/readers for more resources
Protein kinase B (PKB)/Akt has been strongly implicated in the insulin-dependent stimulation of GLUT4 translocation and glucose transport in skeletal muscle and fat cells. Recently an allosteric inhibitor of PKB (Akti) that selectively targets PKB alpha and -beta was reported, but as yet its precise mechanism of action or ability to suppress key insulin-regulated events such as glucose and amino acid uptake and glycogen synthesis in muscle cells has not been reported. We show here that Akti ablates the insulin-dependent regulation of these processes in L6 myotubes at submicromolar concentrations and that inhibition correlates tightly with loss of PKB activation/phosphorylation. Similar findings were obtained using 3T3-L1 adipocytes. Akti did not inhibit IRS1 tyrosine phosphorylation, phosphatidylinositol 3-kinase signaling, or activation of Erks, ribosomal S6 kinase, or atypical protein kinases C but significantly impaired regulation of downstream PKB targets glycogen synthase kinase-3 and AS160. Akti-mediated inhibition of PKB requires an intact kinase pleckstrin homology domain but does not involve suppression of 3-phosphoinositide binding to this domain. Importantly, we have discovered that Akti inhibition is critically dependent upon a solvent-exposed tryptophan residue (Trp-80) that is present within the pleckstrin homology domain of all three PKB isoforms and whose mutation to an alanine (PKBW80A) yields an Akti-resistant kinase. Cellular expression of PKBW80A antagonized the Akti-mediated inhibition of glucose and amino acid uptake. Our findings support a critical role for PKB in the hormonal regulation of glucose and system A amino acid uptake and indicate that use of Akti and expression of the drug-resistant kinase will be valuable tools in delineating cellular PKB functions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available