Title
Tumor suppressor pRB functions as a co-repressor of the CCAAT displacement protein (CDP/cut) to regulate cell cycle controlled histone H4 transcription
GSBS Program
Biochemistry & Molecular Pharmacology
UMMS Affiliation
Graduate School of Biomedical Sciences; Department of Cell Biology and Cancer Center
Date
8-2-2003
Document Type
Article
Medical Subject Headings
Animals; Base Sequence; CDC2 Protein Kinase; *Cell Cycle; Cell Line; Cyclin A; Gene Expression Regulation; Histones; Homeodomain Proteins; Humans; Mice; Molecular Sequence Data; Nuclear Proteins; Phosphorylation; Promoter Regions (Genetics); Protein Binding; Repressor Proteins; Retinoblastoma Protein; *Transcription, Genetic
Disciplines
Life Sciences | Medicine and Health Sciences
Abstract
The CCAAT displacement protein (CDP-cut/CUTL1/cux) performs a key proliferation-related function as the DNA binding subunit of the cell cycle controlled HiNF-D complex. HiNF-D interacts with all five classes (H1, H2A, H2B, H3, and H4) of the cell-cycle dependent histone genes, which are transcriptionally and coordinately activated at the G(1)/S phase transition independent of E2F. The tumor suppressor pRB/p105 is an intrinsic component of the HiNF-D complex. However, the molecular interactions that enable CDP and pRB to form a complex and thus convey cell growth regulatory information onto histone gene promoters must be further defined. Using transient transfections, we show that CDP represses the H4 gene promoter and that pRB functions with CDP as a co-repressor. Direct physical interaction between CDP and pRB was observed in glutathione-S-transferase (GST) pull-down assays. Furthermore, interactions between these proteins were established by yeast and mammalian two-hybrid experiments and co-immunoprecipitation assays. Confocal microscopy shows that subsets of each protein are co-localized in situ. Using a series of pRB mutants, we find that the CDP/pRB interaction, similar to the E2F/pRB interaction, utilizes the A/B large pocket (LP) of pRB. Thus, several converging lines of evidence indicate that complexes between CDP and pRB repress cell cycle regulated histone gene promoters.
Rights and Permissions
Citation: J Cell Physiol. 2003 Sep;196(3):541-56. Link to article on publisher's site