title: SC35 and heterogeneous nuclear ribonucleoprotein A/B proteins bind to a juxtaposed exonic splicing enhancer/exonic splicing silencer element to regulate HIV-1 tat exon 2 splicing.
abstract: Splicing of the human immunodeficiency virus, type 1, primary transcript is highly regulated. Maintaining the proper equilibrium among spliced, unspliced, and partially spliced isoforms is essential for the replication of the virus. Here we characterize a complex cis-acting element located in tat exon 2 that is required for the splicing regulation of the upstream intron. An exonic splicing enhancer (ESE) and an exonic splicing silencer (ESS) are both located within the regulatory element. Heterogeneous nuclear ribonucleoprotein (hnRNP) A/B proteins bind the ESS to repress splicing, whereas the SR protein SC35 binds the ESE to activate it. We show that the SC35 and the hnRNP A1 binding sites overlap within the juxtaposed ESE/ESS. We propose that hnRNP A1 binding to the ESS inhibits splicing of the upstream intron by directly masking the SC35 binding site.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology and Center for Molecular Biology of RNA, Sinsheimer Laboratories, University of California, Santa Cruz 95064, USA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Zahler
authors.forename: Christian K
authors.initials: CK
authors.lastname: Damgaard
authors.forename: Jorgen
authors.initials: J
authors.lastname: Kjems
authors.forename: Massimo
authors.initials: M
authors.lastname: Caputi
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005091:Exons; D005786:Gene Expression Regulation; D015696:Gene Products, tat / Q000235:genetics*; D020868:Gene Silencing; D006367:HeLa Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000737:chemistry*; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism; D006801:Humans; D007438:Introns; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012313:RNA / Q000737:chemistry; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012261:Ribonucleoproteins; D000068103:Serine-Arginine Splicing Factors
chemical_list: D015696:Gene Products, tat; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; C439768:hnRNP A2; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors; D012313:RNA