title: Sprouty2 regulates PI(4,5)P2/Ca2+ signaling and HIV-1 Gag release.
abstract: We reported recently that activation of the inositol 1,4,5-triphosphate receptor (IP3R) is required for efficient HIV-1 Gag trafficking and viral particle release. IP3R activation requires phospholipase C (PLC)-catalyzed hydrolysis of PI(4,5)P(2) to IP3 and diacylglycerol. We show that Sprouty2 (Spry2), which binds PI(4,5)P(2) and PLCγ, interfered with PI(4,5)P(2) in a manner similar to that of U73122, an inhibitor of PI(4,5)P(2) hydrolysis, suggesting that Spry2 negatively regulates IP3R by preventing formation of its activating ligand, IP3. Mutation to Asp of R252, a crucial determinant of PI(4,5)P(2) binding in the C-terminal domain of Spry2, prevented the interference, indicating that binding to the phospholipid is required. By contrast, deletion of the PLCγ binding region or mutation of a critical Tyr residue in the region did not prevent the interference but Spry2-PI(4,5)P(2) colocalization was not detected, suggesting that PLC binding is required for their stable association. Like U73122, Spry2 over-expression inhibited wild type Gag release as virus-like particles. Disrupting either binding determinant relieved the inhibition. IP3R-mediated Ca(2+)signaling, in turn, was found to influence Spry2 subcellular distribution and ERK, a Spry2 regulator. Our findings suggest that Spry2 influences IP3R function through control of PI(4,5)P(2) and IP3R influences Spry2 function by controlling its distribution and ERK activation.
authors.affiliation: Department of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794-5222, USA.
authors.forename: Lorna S
authors.initials: LS
authors.lastname: Ehrlich
authors.forename: Gisselle N
authors.initials: GN
authors.lastname: Medina
authors.forename: Carol A
authors.initials: CA
authors.lastname: Carter
mesh_terms: D000818:Animals; D019556:COS Cells; D020013:Calcium Signaling; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000378:metabolism; D011485:Protein Binding; D014771:Virion / Q000378:metabolism; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D050505:Mutant Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; C485561:SPRY2 protein, human; D054301:gag Gene Products, Human Immunodeficiency Virus; D048049:Extracellular Signal-Regulated MAP Kinases; D051966:Phospholipase C gamma