title: Rac1-dependent transcriptional up-regulation of p27Kip1 by homophilic cell-cell contact in vascular endothelial cells.
abstract: The mechanism for the transcriptional up-regulation of p27Kip1 due to the formation of the cell-cell contact was investigated in vascular endothelial cells. The induction of the cell-cell contact by adding an extra number of endothelial cells activated Rac1, up-regulated p27Kip1 mRNA and protein, and also facilitated the cell cycle arrest. Transduction of the Rac1 inhibitor protein using the cell-penetrating peptide or treatment with a Rac1 inhibitor NSC23766 inhibited the p27Kip1 up-regulation and delayed the cell cycle arrest. Rac1 was therefore suggested to mediate the contact-induced transcriptional up-regulation of p27Kip1. The role of Rac1 in the regulation of the p27Kip1 promoter activity was next examined with a luciferase reporter assay. The promoter activity was increased by inducing the cell-cell contact, which was significantly inhibited by the Rac1 inhibitory protein and NSC23766. The evaluation of various truncated promoter regions determined region -620 to -573 nucleotides from the initiation codon to be responsible for the contact-induced, Rac1-dependent activation of the p27Kip1 promoter. The present study thus demonstrated for the first time that the activation of Rac1 due to the cell-cell contact plays a critical role in the transcriptional up-regulation of p27Kip1 in vascular endothelial cells.
authors.affiliation: Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Hirano
authors.forename: Hideo
authors.initials: H
authors.lastname: Kanaide
authors.forename: Katsuya
authors.initials: K
authors.lastname: Hirano
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology*; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011743:Pyrimidines / Q000494:pharmacology; D013552:Swine; D015854:Up-Regulation; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000634:Aminoquinolines; C487513:NSC 23766; D011743:Pyrimidines; D050760:Cyclin-Dependent Kinase Inhibitor p27; D020830:rac1 GTP-Binding Protein