Tumor suppressor pRB functions as a co-repressor of the CCAAT displacement protein (CDP/cut) to regulate cell cycle controlled histone H4 transcription.
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.
Gupta
Sunita
S
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester 01655, USA.
Luong
Mai X
MX
Bleuming
Sylvia A
SA
Miele
Angela
A
Luong
Michael
M
Young
Daniel
D
Knudsen
Erik S
ES
Van Wijnen
Andre J
AJ
Stein
Janet L
JL
Stein
Gary S
GS
D000818:Animals; D001483:Base Sequence; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D002460:Cell Line; D019925:Cyclin A / Q000378:metabolism; D005786:Gene Expression Regulation; D006657:Histones / Q000235:genetics*; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic
C080632:CUX1 protein, human; C000624101:Cux1 protein, mouse; D019925:Cyclin A; D006657:Histones; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; D014157:Transcription Factors; D016203:CDC2 Protein Kinase