title: Host cell factor-1 interacts with and antagonizes transactivation by the cell cycle regulatory factor Miz-1.
abstract: Human host cell factor-1 (HCF-1) is essential for cell cycle progression and is required, in conjunction with the herpes simplex virus transactivator VP16, for induction of viral immediate-early gene expression. We show here that HCF-1 directly binds to the Myc-interacting protein Miz-1, a transcription factor that induces cell cycle arrest at G(1), in part by directly stimulating expression of the cyclin-dependent kinase inhibitor p15(INK4b). A domain encompassing amino acids 750-836, contained within a subregion of HCF-1 required for cell cycle progression, was sufficient to bind Miz-1. Conversely, HCF-1 interacted with two separate regions in Miz-1: the N-terminal POZ domain and a C-terminal domain (residues 637-803) previously shown to harbor determinants for interaction with c-Myc and the coactivator p300. The latter functioned as a potent transactivation domain when tethered to DNA, indicating that HCF-1 targets a transactivation function in Miz-1. HCF-1 or a Miz-1-binding fragment of HCF-1 repressed transactivation by Gal4-Miz-1 in transfection assays. Moreover, HCF-1 repressed Miz-1-mediated transactivation of a reporter gene linked to the p15(INK4b) promoter. Protein/protein interaction studies and transient transfection assays demonstrated that HCF-1 interferes with recruitment of p300 to Miz-1, similar to what has been reported with c-Myc. Our findings identify Miz-1 as a novel HCF-1-interacting partner and illustrate cross-talk between these two proteins that may be of consequence to their respective functions in gene regulation and their opposing effects on the cell cycle.
authors.affiliation: Department of Biochemistry, McMaster University, Hamilton, Ontario L8N 3Z5, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Piluso
authors.forename: Patricia
authors.initials: P
authors.lastname: Bilan
authors.forename: John P
authors.initials: JP
authors.lastname: Capone
mesh_terms: D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D051863:Host Cell Factor C1; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000502:physiology*; D025521:Tumor Suppressor Proteins
chemical_list: D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D017931:DNA Primers; D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D011506:Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins