A pharmacological map of the PI3-K family defines a role for p110alpha in insulin signaling.
Phosphoinositide 3-kinases (PI3-Ks) are an important emerging class of drug targets, but the unique roles of PI3-K isoforms remain poorly defined. We describe here an approach to pharmacologically interrogate the PI3-K family. A chemically diverse panel of PI3-K inhibitors was synthesized, and their target selectivity was biochemically enumerated, revealing cryptic homologies across targets and chemotypes. Crystal structures of three inhibitors bound to p110gamma identify a conformationally mobile region that is uniquely exploited by selective compounds. This chemical array was then used to define the PI3-K isoforms required for insulin signaling. We find that p110alpha is the primary insulin-responsive PI3-K in cultured cells, whereas p110beta is dispensable but sets a phenotypic threshold for p110alpha activity. Compounds targeting p110alpha block the acute effects of insulin treatment in vivo, whereas a p110beta inhibitor has no effect. These results illustrate systematic target validation using a matrix of inhibitors that span a protein family.
Knight
Zachary A
ZA
Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA.
Gonzalez
Beatriz
B
Feldman
Morri E
ME
Zunder
Eli R
ER
Goldenberg
David D
DD
Williams
Olusegun
O
Loewith
Robbie
R
Stokoe
David
D
Balla
Andras
A
Toth
Balazs
B
Balla
Tamas
T
Weiss
William A
WA
Williams
Roger L
RL
Shokat
Kevan M
KM
D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D001665:Binding Sites; D058534:Class I Phosphatidylinositol 3-Kinases; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D015394:Molecular Structure; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010750:Phosphoproteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D058534:Class I Phosphatidylinositol 3-Kinases; D004791:Enzyme Inhibitors; D005947:Glucose; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010750:Phosphoproteins; C526292:IRS1 protein, human; C526295:Irs1 protein, mouse; C509622:1-phosphatidylinositol 3-kinase p110 subunit, mouse