Insulin selectively stimulates nuclear phosphoinositide‐specific phospholipase C (PI‐PLC) β1 activity through a mitogen‐activated protein (MAP) kinase‐dependent serine phosphorylation

FEBS Letters

Manzoli, Lucia²  Martelli, Alberto M.²  Billi, Anna Maria²  Cocco, Lucio²  Aluigi, Michela²  Faenza, Irene²  Gilmour, R.Stewart⁴  De Pol, Anto¹  Falconi, Mirella³ 

[1] Department of Morphological Sciences, University of Modena, Modena, Italy;Cellular Signalling Laboratory, Department of Anatomical Sciences, University of Bologna, Via Irnerio 48, I-40126 Bologna, Italy;Institute of Cytomorphology, Italian C.N.R., I.O.R., Bologna, Italy;Liggins Institute, School of Medicine, University of Auckland, Private Bag 92019, Auckland, New Zealand

关键词: Nucleus;    Phosphoinositide;    Phospholipase C;    Mitogen-activated protein kinase;    Phosphorylation;    Serine;    bFGF;    basic fibroblast growth factor;    5′-BrdU;    5′-bromodeoxyuridine;    BSA;    bovine serum albumin;    DAG;    diacylglycerol;    ECL;    enhanced chemiluminescence;    EGF;    epidermal growth factor;    FITC;    fluorescein isothiocyanate;    IGF-I;    insulin-like growth factor-I;    Ins(1;    4;    5)P3;    inositol 1;    4;    5-trisphosphate;    MAP kinase;    mitogen-activated protein kinase;    MEK;    MAP kinase kinase;    PBS;    phosphate-buffered saline;    PI-PLC;    phosphoinositide-specific phospholipase C;    PtdIns(4;    5)P2;    phosphatidylinositol 4;    5-bisphosphate;   

DOI  :  10.1016/S0014-5793(00)02313-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Using NIH 3T3 cells, we have investigated nuclear phosphoinositide metabolism in response to insulin, a molecule which acts as a proliferating factor for this cell line and which is known as a powerful activator of the mitogen-activated protein (MAP) kinase pathway. Insulin stimulated inositol lipid metabolism in the nucleus, as demonstrated by measurement of the diacylglycerol mass produced in vivo and by in vitro nuclear phosphoinositide-specific phospholipase C (PI-PLC) activity assay. Despite the fact that nuclei of NIH 3T3 cells contained all of the four isozymes of the β family of PI-PLC (i.e. β1, β2, β3, and β4), insulin only activated the β1 isoform. Insulin also induced nuclear translocation of MAP kinase, as demonstrated by Western blotting analysis, enzyme activity assays, and immunofluorescence staining, and this translocation was blocked by the specific MAP kinase kinase inhibitor PD98059. By means of both a monoclonal antibody recognizing phosphoserine and in vivo labeling with [³²P]orthophosphate, we ascertained that nuclear PI-PLC-β1 (and in particular the b subtype) was phosphorylated on serine residues in response to insulin. Both phosphorylation and activation of nuclear PI-PLC-β1 were substantially reduced by PD98059. Our results conclusively demonstrate that activation of nuclear PI-PLC-β1 strictly depends on its phosphorylation which is mediated through the MAP kinase pathway.

【 授权许可】

Unknown