title: SR and SR-related proteins redistribute to segregated fibrillar components of nucleoli in a response to DNA damage.
abstract: Pre-mRNA splicing factors are often redistributed to nucleoli in response to physiological conditions and cell stimuli. In telophase nuclei, serine-arginine rich (SR) proteins, which usually reside in nuclear speckles, localize transiently to active ribosomal DNA (rDNA) transcription sites called nucleolar organizing region-associated patches (NAPs). Here, we show that ultraviolet light and DNA damaging chemicals induce the redistribution of SR and SR-related proteins to areas around nucleolar fibrillar components in interphase nuclei that are similar to, but distinct from, NAPs, and these areas have been termed DNA damage-induced NAPs (d-NAPs). In vivo labeling of nascent RNA distinguished d-NAPs from NAPs in that d-NAPs were observed even after full rDNA transcriptional arrest as a result of DNA damage. Studies under a variety of conditions revealed that d-NAP formation requires both RNA polymerase II-dependent transcriptional arrest and nucleolar segregation, in particular, the disorganization of the granular nucleolar components. Despite the redistribution of SR proteins, splicing factor-enriched nuclear speckles were not disrupted because other nuclear speckle components, such as nuclear poly(A) RNA and the U5-116K protein, remained in DNA-damaged cells. These data suggest that the selective redistribution of splicing factors contributes to the regulation of specific genes via RNA metabolism. Finally, we demonstrate that a change in alternative splicing of apoptosis-related genes is coordinated with the occurrence of d-NAPs. Our results reveal a novel response to DNA damage that involves the dynamic redistribution of splicing factors to nucleoli.
authors.affiliation: Department of Biochemistry, Jichi Medical University School of Medicine, Tochigi, Japan. esaka@jichi.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Sakashita
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D011564:Furocoumarins / Q000494:pharmacology; D057809:HEK293 Cells; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D007399:Interphase; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D012318:RNA Polymerase I / Q000378:metabolism; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000378:metabolism*; D051381:Rats; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
chemical_list: D004275:DNA, Ribosomal; D011564:Furocoumarins; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D017415:Ribonucleoprotein, U5 Small Nuclear; D000068103:Serine-Arginine Splicing Factors; D011061:Poly A; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D002945:Cisplatin