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Muise-Helmericks RC , Grimes HL , Bellacosa A , Malstrom SE , Tsichlis PN , Rosen N
Cyclin D expression is controlled post-transcriptionally via a phosphatidylinositol 3-kinase Akt-dependent pathway
Journal of Biological Chemistry. 1998 Nov;273(45) :29864-29872
PMID: ISI:000076798300080   
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Cyclin D expression is regulated by growth factors and is necessary for the induction of mitogenesis. Herbimycin A, a drug that binds to Hsp90, induces the destruction of tyrosine kinases and causes the down-regulation of cyclin D and an Rb-dependent growth arrest in the G(1) phase of the cell cycle. We find that the induction of D cyclin expression by serum and its repression by herbimycin A are regulated at the level of mRNA translation. Induction of cyclin D by serum occurs prior to the induction of its mRNA and does not require transcription. Herbimycin A repression is characterized by a decrease in the synthetic rate of D-cyclins prior to changes in mRNA expression and in the absence of changes in the half-life of the protein, This effect on D-cyclin translation is mediated via a phosphatidylinositol 3-kinase (PI 3-kinase)-dependent pathway. PI 3-kinase inhibitors such as wortmannin and LY294002, and rapamycin, an inhibitor of FRAP/TOR, cause a decline in the level of D-cyclins, whereas inhibitors of mitogen-activated protein kinase kinase and farnesyltransferase do not. Cells expressing the activated, myristoylated form of Akt kinase, a target of PI 3-kinase, are refractory to the effects of herbimycin A or serum starvation on D-cyclin expression. These data suggest that serum induction of cyclin D expression results from enhanced translation of its mRNA and that this results from activation of a pathway that is dependent upon PI 3-kinase and Akt kinase.
ISI Document Delivery No.: 135JJ Times Cited: 311 Cited Reference Count: 74 AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC