title: Identification of a chemical inhibitor for nuclear speckle formation: implications for the function of nuclear speckles in regulation of alternative pre-mRNA splicing.
abstract: Nuclear speckles are subnuclear structures enriched with RNA processing factors and poly (A)(+) RNAs comprising mRNAs and poly (A)(+) non-coding RNAs (ncRNAs). Nuclear speckles are thought to be involved in post-transcriptional regulation of gene expression, such as pre-mRNA splicing. By screening 3585 culture extracts of actinomycetes with in situ hybridization using an oligo dT probe, we identified tubercidin, an analogue of adenosine, as an inhibitor of speckle formation, which induces the delocalization of poly (A)(+) RNA and dispersion of splicing factor SRSF1/SF2 from nuclear speckles in HeLa cells. Treatment with tubercidin also decreased steady-state MALAT1 long ncRNA, thought to be involved in the retention of SRSF1/SF2 in nuclear speckles. In addition, we found that tubercidin treatment promoted exon skipping in the alternative splicing of Clk1 pre-mRNA. These results suggest that nuclear speckles play a role in modulating the concentration of splicing factors in the nucleoplasm to regulate alternative pre-mRNA splicing.
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Kurogi
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Yota
authors.initials: Y
authors.lastname: Matsuo
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Mihara
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yagi
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Kaya
authors.initials: K
authors.lastname: Shigaki-Miyamoto
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Syukichi
authors.initials: S
authors.lastname: Toyota
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Azuma
authors.affiliation: Laboratory of Disease Biology, Institute of Microbial Chemistry, Shinagawa-ku, Tokyo 141-0021, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Igarashi
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto 860-8555, Japan. Electronic address: ttani@sci.kumamoto-u.ac.jp.
authors.forename: Tokio
authors.initials: T
authors.lastname: Tani
mesh_terms: D039903:Actinobacteria / Q000737:chemistry; D017398:Alternative Splicing / Q000187:drug effects / Q000235:genetics; D022003:Cell Nucleus Structures / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D004353:Drug Evaluation, Preclinical; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D020401:Primed In Situ Labeling; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D062085:RNA, Long Noncoding / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D014372:Tubercidin / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: C557041:MALAT1 long non-coding RNA, human; D009687:Nuclear Proteins; D012322:RNA Precursors; D062085:RNA, Long Noncoding; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; C066780:Clk dual-specificity kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D014372:Tubercidin
keywords: Alternative splicing; Chemical inhibitor; Nuclear speckle; SR proteins; Splicing factor; Tubercidin