ABSTRACT
Accumulation of histone proteins is necessary for packaging of replicated DNA during the S phase of the cell cycle. Different mechanisms operate to regulate histone protein levels, and induction of human histone gene expression at the G1-S phase transition plays a critical role. The zinc finger HiNF-P and coactivator p220 (NPAT) proteins are key regulators of histone gene expression. Here, we describe a novel HiNF-P-specific conserved region (PSCR) located within the C-terminus that is present in HiNF-P homologues of all metazoan species that have been examined. The PSCR motif is required for activation of histone H4 gene transcription and contributes to DNA binding of HiNF-P. Thus, the PSCR module represents an auxiliary DNA-binding determinant that plays a critical role in mediating histone gene expression during the cell cycle and defines HiNF-P as a unique cell cycle regulatory member of the zinc finger transcription factor family.
Subject(s)
Repressor Proteins/chemistry , Repressor Proteins/metabolism , Amino Acid Motifs , Amino Acid Sequence , Base Sequence , Binding Sites , Cell Cycle , Cell Cycle Proteins/chemistry , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Line , Conserved Sequence , DNA/genetics , DNA/metabolism , HeLa Cells , Histones/genetics , Humans , Models, Molecular , Molecular Sequence Data , Multiprotein Complexes , Mutagenesis , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , RNA, Small Interfering/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Repressor Proteins/genetics , Sequence Homology, Amino Acid , Zinc FingersABSTRACT
HiNF-P and its cofactor p220(NPAT) are principal factors regulating histone gene expression at the G(1)-S phase cell cycle transition. Here, we have investigated whether HiNF-P controls other cell cycle- and cancer-related genes. We used cDNA microarrays to monitor responsiveness of gene expression to small interfering RNA-mediated depletion of HiNF-P. Candidate HiNF-P target genes were examined for the presence of HiNF-P recognition motifs, in vitro HiNF-P binding to DNA, and in vivo association by chromatin immunoprecipitations and functional reporter gene assays. Of 177 proliferation-related genes we tested, 20 are modulated in HiNF-P-depleted cells and contain putative HiNF-P binding motifs. We validated that at least three genes (i.e., ATM, PRKDC, and CKS2) are HiNF-P dependent and provide data indicating that the DNA damage response is altered in HiNF-P-depleted cells. We conclude that, in addition to histone genes, HiNF-P also regulates expression of nonhistone targets that influence competency for cell cycle progression.
