title: A pharmacological map of the PI3-K family defines a role for p110alpha in insulin signaling.
abstract: 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.
authors.affiliation: Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Knight
authors.forename: Beatriz
authors.initials: B
authors.lastname: Gonzalez
authors.forename: Morri E
authors.initials: ME
authors.lastname: Feldman
authors.forename: Eli R
authors.initials: ER
authors.lastname: Zunder
authors.forename: David D
authors.initials: DD
authors.lastname: Goldenberg
authors.forename: Olusegun
authors.initials: O
authors.lastname: Williams
authors.forename: Robbie
authors.initials: R
authors.lastname: Loewith
authors.forename: David
authors.initials: D
authors.lastname: Stokoe
authors.forename: Andras
authors.initials: A
authors.lastname: Balla
authors.forename: Balazs
authors.initials: B
authors.lastname: Toth
authors.forename: Tamas
authors.initials: T
authors.lastname: Balla
authors.forename: William A
authors.initials: WA
authors.lastname: Weiss
authors.forename: Roger L
authors.initials: RL
authors.lastname: Williams
authors.forename: Kevan M
authors.initials: KM
authors.lastname: Shokat
mesh_terms: 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*
chemical_list: 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