The Pole3 bidirectional unit is regulated by MYC and E2Fs.
Pole3 (DPB4/YBL1/CHRAC17) is one of the subunits of the DNA polymerase e. It contains a histone-like domain required for the hererodimerization with its Pole4 (DPB3) partner. In another interaction, Pole3 heterodimerizes with YCL1/CHRAC15 and associates with the ACF1/SNF2H remodelling complex. We find that the Pol3 gene is regulated in starved NIH3T3 fibroblasts upon induction with serum, with a peak at the entry in the S phase. We characterized the Pole3 promoter, which is linked bidirectionally to C9Orf46, a gene of unknown function: it has no CCAAT nor TATA-boxes, and contains an E box and two potential E2F sites. Mutagenesis analysis points to a minimal promoter region as sufficient for activation; the E box and a neighbouring direct repeat are important for regulation. Cell-cycle regulation was reproduced in stable clones and an additional E2F site was found to be important. Chromatin immunoprecipitation analysis indicates that E2F1/4, as well as MYC, are associated with the Pole3 promoter in a phase-specific way. These data highlight coregulation of a histone-like gene with core histones upon DNA synthesis, and represent a first dissection of the interplay between two essential cell-cycle regulators on a bidirectional promoter.
Bolognese
Fabrizio
F
Dipartimento di Scienze Biomolecolari e Biotecnologie, U. di Milano, Via Celoria 26, 20133 Milano, Italy.
Forni
Claudia
C
Caretti
Giuseppina
G
Frontini
Mattia
M
Minuzzo
Mario
M
Mantovani
Roberto
R
D000818:Animals; D047369:Chromatin Immunoprecipitation / Q000379:methods; D004257:DNA Polymerase II / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D006657:Histones / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D016296:Mutagenesis / Q000235:genetics; D041681:NIH 3T3 Cells; D017354:Point Mutation; D000075223:Poly-ADP-Ribose Binding Proteins; D017434:Protein Structure, Tertiary / Q000235:genetics; D020218:Response Elements / Q000235:genetics; D016196:S Phase / Q000502:physiology*; D016385:TATA Box / Q000235:genetics; D014158:Transcription, Genetic / Q000502:physiology*
D006657:Histones; D000075223:Poly-ADP-Ribose Binding Proteins; D004257:DNA Polymerase II; C485610:Pole protein, mouse