title: Differential hnRNP D isoform incorporation may confer plasticity to the ESSV-mediated repressive state across HIV-1 exon 3.
abstract: Even though splicing repression by hnRNP complexes bound to exonic sequences is well-documented, the responsible effector domains of hnRNP proteins have been described for only a select number of hnRNP constituents. Thus, there is only limited information available for possible varying silencer activities amongst different hnRNP proteins and composition changes within possible hnRNP complex assemblies. In this study, we identified the glycine-rich domain (GRD) of hnRNP proteins as a unifying feature in splice site repression. We also show that all four hnRNP D isoforms can act as genuine splicing repressors when bound to exonic positions. The presence of an extended GRD, however, seemed to potentiate the hnRNP D silencer activity of isoforms p42 and p45. Moreover, we demonstrate that hnRNP D proteins associate with the HIV-1 ESSV silencer complex, probably through direct recognition of "UUAG" sequences overlapping with the previously described "UAGG" motifs bound by hnRNP A1. Consequently, this spatial proximity seems to cause mutual interference between hnRNP A1 and hnRNP D. This interplay between hnRNP A1 and D facilitates a dynamic regulation of the repressive state of HIV-1 exon 3 which manifests as fluctuating relative levels of spliced vpr- and unspliced gag/pol-mRNAs.
authors.affiliation: Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hillebrand
authors.affiliation: Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
authors.forename: Jan Otto
authors.initials: JO
authors.lastname: Peter
authors.affiliation: Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Brillen
authors.affiliation: Institute of Evolutionary Genetics, Heinrich-Heine-University Duesseldorf, Duesseldorf, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Otte
authors.affiliation: Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
authors.forename: Heiner
authors.initials: H
authors.lastname: Schaal
authors.affiliation: Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany. Electronic address: steffen.erkelenz@gmx.de.
authors.forename: Steffen
authors.initials: S
authors.lastname: Erkelenz
mesh_terms: D002460:Cell Line; D063185:Epigenetic Repression / Q000235:genetics*; D005091:Exons / Q000235:genetics*; D005998:Glycine / Q000235:genetics; D057809:HEK293 Cells; D015497:HIV-1 / Q000235:genetics*; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000235:genetics*; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics; D054298:Human Immunodeficiency Virus Proteins / Q000235:genetics*; D006801:Humans; D020033:Protein Isoforms / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D054298:Human Immunodeficiency Virus Proteins; D020033:Protein Isoforms; D012367:RNA, Viral; D054301:gag Gene Products, Human Immunodeficiency Virus; D005998:Glycine
keywords: HIV-1; Splicing; hnRNP D; hnRNP proteins