title: Transcriptional factor HBP1 targets P16(INK4A), upregulating its expression and consequently is involved in Ras-induced premature senescence.
abstract: Oncogene-mediated premature senescence has emerged as a potential tumor-suppressive mechanism in early cancer transitions. Many studies showed that Ras and p38 mitogen-activated protein kinase (MAPK) participate in premature senescence. Our previous work indicated that the HMG box-containing protein 1 (HBP1) transcription factor is involved in Ras- and p38 MAPK-induced premature senescence, but the mechanism of which has not yet been identified. Here, we showed that the p16(INK4A) cyclin-dependent kinase inhibitor is a novel target of HBP1 participating in Ras-induced premature senescence. The promoter of the p16(INK4A) gene contains an HBP1-binding site at position -426 to -433 bp from the transcriptional start site. HBP1 regulates the expression of the endogenous p16(INK4A) gene through direct sequence-specific binding. With HBP1 expression and the subsequent increase of p16(INK4A) gene expression, Ras induces premature senescence in primary cells. The data suggest a model in which Ras and p38 MAPK signaling engage HBP1 and p16(INK4A) to trigger premature senescence. In addition, we report that HBP1 knockdown is also required for Ras-induced transformation. All the data indicate that the mechanism of HBP1-mediated transcriptional regulation is important for not only premature senescence but also tumorigenesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Beijing, PR China.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: K E
authors.initials: KE
authors.lastname: Paulson
authors.forename: A S
authors.initials: AS
authors.lastname: Yee
authors.forename: X
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008954:Models, Biological; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology; D014183:Transplantation, Heterologous; D015854:Up-Regulation
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; C486328:HBP1 protein, human; D006609:High Mobility Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D015689:Oncogene Protein p21(ras)