title: Rho activity can alter the translation of p27 mRNA and is important for RasV12-induced transformation in a manner dependent on p27 status.
abstract: The amount of p27(Kip1) establishes a threshold to which G(1) cyclin-cyclin-dependent kinase complexes must surpass prior to cells progressing into S-phase. The amount of p27 is greatest in G(0) cells, intermediate in G(1) cells, and lowest in S-phase cells. However, there is little known regarding the pathways and mechanisms controlling p27 accumulation in G(0) cells. We report that inhibition of Rho, by either lovastatin or C3 exoenzyme, can increase the translational efficiency of p27 mRNA. Similar pharmacologic inhibition of the phosphatidylinositol 3-kinase, the S6 kinase, and the Mek1 kinase pathways all fail to increase translational efficiency in MDA468 cells. This Rho-responsive element lies within a 300-nucleotide region at the 3'-end of the mRNA. By supporting the significance of this signaling pathway to Rho function, we showed that the suppression of Ras(V12) transformation by RhoA(N19) is blocked in p27-/- cells. In contrast this activity is not blocked in Rb-/- or p16-/- cells. The resistance of p27-/- cells to RhoA(N19) is not associated with a failure of RhoA(N19) to accumulate to amounts sufficient to block Rho activity as measured by the organization of actin stress fibers. Together these results indicate a link between Rho and p27.
authors.affiliation: Programs in Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, New York 10021, USA.
authors.forename: Anxo
authors.initials: A
authors.lastname: Vidal
authors.forename: S Sean
authors.initials: SS
authors.lastname: Millard
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Miller
authors.forename: Andrew
authors.initials: A
authors.lastname: Koff
mesh_terms: D020413:3' Untranslated Regions; D016475:3T3 Cells; D036002:ADP Ribose Transferases / Q000494:pharmacology; D000818:Animals; D001905:Botulinum Toxins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008148:Lovastatin / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D016196:S Phase; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D036002:ADP Ribose Transferases; D001905:Botulinum Toxins; D018797:Cell Cycle Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D008148:Lovastatin; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D019893:Ribosomal Protein S6 Kinases; D025521:Tumor Suppressor Proteins; D018631:ras Proteins; D020741:rho GTP-Binding Proteins; C493961:Cdkn1b protein, mouse; C063007:exoenzyme C3, Clostridium botulinum; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse