Human U2 snRNA genes exhibit a persistently open transcriptional state and promoter disassembly at metaphase.
In mammals, small multigene families generate spliceosomal U snRNAs that are nearly as abundant as rRNA. Using the tandemly repeated human U2 genes as a model, we show by footprinting with DNase I and permanganate that nearly all sequences between the enhancer-like distal sequence element and the initiation site are protected during interphase whereas the upstream half of the U2 snRNA coding region is exposed. We also show by chromatin immunoprecipitation that the SNAPc complex, which binds the TATA-like proximal sequence element, is removed at metaphase but remains bound under conditions that induce locus-specific metaphase fragility of the U2 genes, such as loss of CSB, BRCA1, or BRCA2 function, treatment with actinomycin D, or overexpression of the tetrameric p53 C terminus. We propose that the U2 snRNA promoter establishes a persistently open state to facilitate rapid reinitiation and perhaps also to bypass TFIIH-dependent promoter melting; this open state would then be disassembled to allow metaphase chromatin condensation.
Pavelitz
Thomas
T
University of Washington, Department of Biochemistry, School of Medicine, Seattle, WA 98195-7350, USA.
Bailey
Arnold D
AD
Elco
Christopher P
CP
Weiner
Alan M
AM
D019313:BRCA1 Protein / Q000235:genetics; D024682:BRCA2 Protein / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D002873:Chromosome Fragility; D004249:DNA Damage; D018983:DNA Footprinting; D004265:DNA Helicases / Q000032:analysis / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000032:analysis / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D017895:Manganese Compounds / Q000737:chemistry; D008677:Metaphase / Q000235:genetics*; D010087:Oxides / Q000737:chemistry; D000075223:Poly-ADP-Ribose Binding Proteins; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012342:RNA, Small Nuclear / Q000235:genetics*; D016385:TATA Box; D051758:Transcription Factor TFIIH / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D019313:BRCA1 Protein; D024682:BRCA2 Protein; D017895:Manganese Compounds; D010087:Oxides; D000075223:Poly-ADP-Ribose Binding Proteins; D012342:RNA, Small Nuclear; C106703:SNAPC protein complex, human; D014157:Transcription Factors; C405484:U2 small nuclear RNA; C048856:permanganic acid; D051758:Transcription Factor TFIIH; D003850:Deoxyribonuclease I; D004265:DNA Helicases; C078673:ERCC6 protein, human; D045643:DNA Repair Enzymes