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The phosphoinositide 3-kinase p110α is an essential mediator of insulin signaling and glucose homeostasis. We interrogated the human serine, threonine, and tyrosine kinome to search for novel regulators of p110α and found that the Hippo kinases phosphorylate p110α at T1061, which inhibits its activity. This inhibitory state corresponds to a conformational change of a membrane-binding domain on p110α, which impairs its ability to engage membranes. In human primary hepatocytes, cancer cell lines, and rodent tissues, activation of the Hippo kinases MST1/2 using forskolin or epinephrine is associated with phosphorylation of T1061 and inhibition of p110α, impairment of downstream insulin signaling, and suppression of glycolysis and glycogen synthesis. These changes are abrogated when MST1/2 are genetically deleted or inhibited with small molecules or if the T1061 is mutated to alanine. Our study defines an inhibitory pathway of PI3K signaling and a link between epinephrine and insulin signaling., Competing Interests: Declaration of interests N.V. reports consultant and advisory board activities for Novartis, Petra Pharmaceuticals, Reactive Biosciences, and Magnet Biomedicine. E.A.K. is a shareholder of Eli Lilly and Company, and E.A.K. and K.K. are employees of Loxo Oncology at Lilly. L.C.C. is a founder and member of the board of directors of Agios Pharmaceuticals; is a founder and receives research support from Petra Pharmaceuticals; has equity in and consults for Cell Signaling Technologies, Volastra, Larkspur, and 1 Base Pharmaceuticals; and consults for Loxo-Lilly. J.L.J. has received consulting fees from Scorpion Therapeutics and Volastra Therapeutics. J.L.J. reports consultant activities for Scorpion Therapeutics and Volastra Therapeutics. M.D.G. reports personal fees from Novartis AG, Pfizer, Inc., and Scorpion Therapeutics. L.C.C., B.D.H., and M.D.G. are inventors on patents for Combination Therapy for PI3K-associated Disease or Disorder and The Identification of Therapeutic Interventions to Improve Response to PI3K Inhibitors for Cancer Treatment. B.D.H., L.C.C., and M.D.G. are co-founders and shareholders in Faeth Therapeutics. R.E.S. is on the sponsored advisory board for Miromatrix, Inc., and Lime Therapeutics and is a consultant and speaker for Alnylam, Inc. T.M.Y. is a stockholder and on the board of directors of DESTROKE, Inc., an early-stage start-up developing mobile technology for automated clinical stroke detection., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Insulin stimulates the conversion of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P 2 ) to phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P 3 ), which mediates downstream cellular responses. PI(4,5)P 2 is produced by phosphatidylinositol-4-phosphate 5-kinases (PIP5Ks) and by phosphatidylinositol-5-phosphate 4-kinases (PIP4Ks). Here, we show that the loss of PIP4Ks (PIP4K2A, PIP4K2B, and PIP4K2C) in vitro results in a paradoxical increase in PI(4,5)P 2 and a concomitant increase in insulin-stimulated production of PI(3,4,5)P 3 . The reintroduction of either wild-type or kinase-dead mutants of the PIP4Ks restored cellular PI(4,5)P 2 levels and insulin stimulation of the PI3K pathway, suggesting a catalytic-independent role of PIP4Ks in regulating PI(4,5)P 2 levels. These effects are explained by an increase in PIP5K activity upon the deletion of PIP4Ks, which normally suppresses PIP5K activity through a direct binding interaction mediated by the N-terminal motif VMLΦPDD of PIP4K. Our work uncovers an allosteric function of PIP4Ks in suppressing PIP5K-mediated PI(4,5)P 2 synthesis and insulin-dependent conversion to PI(3,4,5)P 3 and suggests that the pharmacological depletion of PIP4K enzymes could represent a strategy for enhancing insulin signaling., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)