RNA polymerase II 140wimp mutant and mutations in the TFIIH subunit XPB differentially affect homeotic gene expression in Drosophila.
Mutations in the XPB and XPD helicases of the DNA repair/transcription factor TFIIH are involved in several human genetic disorders. An unanswered problem concerning the complexity of the phenotype-genotype relationship is why mutations in individual subunits of TFIIH produce specific phenotypes and not many others. In order to investigate this question we tested whether mutations in the Drosophila XPB homolog, haywire (hay), would modify homeotic derepression phenotypes. In this work, we report that mutations in hay and in the 140-kDa subunit of the RNA polymerase II (RpII140wimp) act as dominant modifiers of the derepression phenotypes of the Sex combs reduced (Scr) and Ultrabithorax (Ubx) genes. The hay mutations only weakly suppress the Scr derepression phenotype caused by the Antp(Scx) mutation but not by Polycomb. In contrast, the RpII140wimp mutation strongly suppresses both Scr derepression phenotypes. In addition, the RpII140wimp also generates phenotypes indicative of loss of Ubx function. On the other hand, all the derepression homeotic phenotypes are sensitive to the generalized reduction of transcription levels when the flies are grown with actinomycin D. We also show that different promoter control regions have differential sensitivity to different hay alleles. All these results support that although TFIIH is a basal transcription factor, mutations in the subunit encoded by hay have specific effects in the transcription of some genes.
Gutiérrez
Luis
L
Department of Developmental Genetics and Molecular Physiology, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca Morelos, México.
Merino
Carlos
C
Vázquez
Martha
M
Reynaud
Enrique
E
Zurita
Mario
M
D000818:Animals; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000235:genetics*; D003609:Dactinomycin / Q000494:pharmacology; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D005801:Genes, Homeobox / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D012319:RNA Polymerase II / Q000235:genetics*; D012168:Retinal Pigments / Q000235:genetics; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000235:genetics; D019473:Transcription Factors, TFII / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012168:Retinal Pigments; C059627:Scr protein, Drosophila; D014157:Transcription Factors; D019473:Transcription Factors, TFII; C066177:Ubx protein, Drosophila; C072022:XPBC-ERCC-3 protein; D051758:Transcription Factor TFIIH; D003609:Dactinomycin; D012319:RNA Polymerase II; D004265:DNA Helicases