title: Intronic CA-repeat and CA-rich elements: a new class of regulators of mammalian alternative splicing.
abstract: We have recently identified an intronic polymorphic CA-repeat region in the human endothelial nitric oxide synthase (eNOS) gene as an important determinant of the splicing efficiency, requiring specific binding of hnRNP L. Here, we analyzed the position requirements of this CA-repeat element, which revealed its potential role in alternative splicing. In addition, we defined the RNA binding specificity of hnRNP L by SELEX: not only regular CA repeats are recognized with high affinity but also certain CA-rich clusters. Therefore, we have systematically searched the human genome databases for CA-repeat and CA-rich elements associated with alternative 5' splice sites (5'ss), followed by minigene transfection assays. Surprisingly, in several specific human genes that we tested, intronic CA RNA elements could function either as splicing enhancers or silencers, depending on their proximity to the alternative 5'ss. HnRNP L was detected specifically bound to these diverse CA elements. These data demonstrated that intronic CA sequences constitute novel and widespread regulatory elements of alternative splicing.
authors.affiliation: Institut für Biochemie, Justus-Liebig-Universität Giessen, Giessen, Germany.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Hui
authors.forename: Lee-Hsueh
authors.initials: LH
authors.lastname: Hung
authors.forename: Monika
authors.initials: M
authors.lastname: Heiner
authors.forename: Silke
authors.initials: S
authors.lastname: Schreiner
authors.forename: Norma
authors.initials: N
authors.lastname: Neumüller
authors.forename: Gregor
authors.initials: G
authors.lastname: Reither
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Haas
authors.forename: Albrecht
authors.initials: A
authors.lastname: Bindereif
mesh_terms: D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D003432:Cross-Linking Reagents; D004274:DNA, Recombinant / Q000235:genetics; D018900:Dinucleotide Repeats; D006367:HeLa Cells; D034664:Heterogeneous-Nuclear Ribonucleoprotein L / Q000378:metabolism; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D019001:Nitric Oxide Synthase / Q000235:genetics; D052250:Nitric Oxide Synthase Type III; D012313:RNA / Q000528:radiation effects; D022821:RNA Splice Sites; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D004274:DNA, Recombinant; D034664:Heterogeneous-Nuclear Ribonucleoprotein L; D022821:RNA Splice Sites; D011993:Recombinant Fusion Proteins; D012313:RNA; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III