title: Adhesion-dependent Skp2 transcription requires selenocysteine tRNA gene transcription-activating factor (STAF).
abstract: Cell adhesion is essential for cell cycle progression in most normal cells. Loss of adhesion dependence is a hallmark of cellular transformation. The F-box protein Skp2 (S-phase kinase-associated protein 2) controls G(1)-S-phase progression and is subject to adhesion-dependent transcriptional regulation, although the mechanisms are poorly understood. We identify two cross-species conserved binding elements for the STAF (selenocysteine tRNA gene transcription-activating factor) in the Skp2 promoter that are essential for Skp2 promoter activity. Endogenous STAF specifically binds these elements in EMSA (electrophoretic mobility-shift assay) and ChIP (chromatin immunoprecipitation) analysis. STAF is sufficient and necessary for Skp2 promoter activity since exogenous STAF activates promoter activity and expression and STAF siRNA (small interfering RNA) inhibits Skp2 promoter activity, mRNA and protein expression and cell proliferation. Furthermore, ectopic Skp2 expression completely reverses the inhibitory effects of STAF silencing on proliferation. Importantly, STAF expression and binding to the Skp2 promoter is adhesion-dependent and associated with adhesion-dependent Skp2 expression in non-transformed cells. Ectopic STAF rescues Skp2 expression in suspension cells. Taken together, these results demonstrate that STAF is essential and sufficient for Skp2 promoter activity and plays a role in the adhesion-dependent expression of Skp2 and ultimately cell proliferation.
authors.affiliation: Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, Bristol BS2 8HW, UK.
authors.forename: Ivette
authors.initials: I
authors.lastname: Hernández-Negrete
authors.forename: Graciela B
authors.initials: GB
authors.lastname: Sala-Newby
authors.forename: Andras
authors.initials: A
authors.lastname: Perl
authors.forename: Gary R
authors.initials: GR
authors.lastname: Kunkel
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Newby
authors.forename: Mark
authors.initials: M
authors.lastname: Bond
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D049109:Cell Proliferation; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D008297:Male; D011401:Promoter Regions, Genetic; D051381:Rats; D044786:S-Phase Kinase-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D044786:S-Phase Kinase-Associated Proteins; D015534:Trans-Activators; C114253:ZNF143 protein, human; C562321:Zfp143 protein, rat