1. Functional characterization of the AFF (AF4/FMR2) family of RNA-binding proteins: insights into the molecular pathology of FRAXE intellectual disability
- Author
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Mireille Melko, Samantha Zongaro, Jozef Gecz, Dominique Douguet, Barbara Bardoni, Céline Verheggen, Mounia Bensaid, Institut de pharmacologie moléculaire et cellulaire ( IPMC ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Génétique Moléculaire de Montpellier ( IGMM ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ), Department of Genetic Medicine Women's and Children's, University of Adelaide, Université Côte d'Azur ( UCA ), Institut de pharmacologie moléculaire et cellulaire (IPMC), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Génétique Moléculaire de Montpellier (IGMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)
- Subjects
MESH : Cell Line ,MESH : Molecular Sequence Data ,MESH: Sequence Homology, Amino Acid ,Gene Expression ,RNA-binding protein ,MESH: Amino Acid Sequence ,MESH: Gene Order ,Exon ,0302 clinical medicine ,MESH : Protein Transport ,Genes, Reporter ,Transcription (biology) ,Gene Order ,Genetics (clinical) ,Genetics ,0303 health sciences ,MESH : Amino Acid Sequence ,MESH : Sequence Alignment ,RNA-Binding Proteins ,General Medicine ,MESH : Genes, Reporter ,Phenotype ,MESH : Sequence Homology, Amino Acid ,DNA-Binding Proteins ,Protein Transport ,MESH : Fragile X Syndrome ,030220 oncology & carcinogenesis ,RNA splicing ,MESH : RNA Splicing ,MESH : DNA-Binding Proteins ,Intranuclear Space ,MESH: Fragile X Syndrome ,MESH: Protein Transport ,MESH: Gene Expression ,RNA Splicing ,Molecular Sequence Data ,MESH : RNA-Binding Proteins ,MESH: Sequence Alignment ,MESH: Intranuclear Space ,[SDV.BC]Life Sciences [q-bio]/Cellular Biology ,Biology ,Cell Line ,03 medical and health sciences ,MESH : Fibroblasts ,Humans ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,MESH : HeLa Cells ,Amino Acid Sequence ,[ SDV.BBM ] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Molecular Biology ,Gene ,030304 developmental biology ,MESH: Molecular Sequence Data ,MESH: Humans ,MESH : Gene Order ,Sequence Homology, Amino Acid ,[ SDV.BC ] Life Sciences [q-bio]/Cellular Biology ,MESH: Genes, Reporter ,MESH : Humans ,Alternative splicing ,RNA ,Fibroblasts ,MESH: Cell Line ,MESH : Gene Expression ,MESH: RNA-Binding Proteins ,MESH : Intranuclear Space ,MESH: Fibroblasts ,Fragile X Syndrome ,MESH: HeLa Cells ,MESH: RNA Splicing ,Sequence Alignment ,MESH: DNA-Binding Proteins ,HeLa Cells - Abstract
International audience; The AFF (AF4/FMR2) family of genes includes four members: AFF1/AF4, AFF2/FMR2, AFF3/LAF4 and AFF4/AF5q31. AFF2/FMR2 is silenced in FRAXE intellectual disability, while the other three members have been reported to form fusion genes as a consequence of chromosome translocations with the myeloid/lymphoid or mixed lineage leukemia (MLL) gene in acute lymphoblastic leukemias (ALLs). All AFF proteins are localized in the nucleus and their role as transcriptional activators with a positive action on RNA elongation was primarily studied. We have recently shown that AFF2/FMR2 localizes to nuclear speckles, subnuclear structures considered as storage/modification sites of pre-mRNA splicing factors, and modulates alternative splicing via the interaction with the G-quadruplex RNA-forming structure. We show here that similarly to AFF2/FMR2, AFF3/LAF4 and AFF4/AF5q31 localize to nuclear speckles and are able to bind RNA, having a high apparent affinity for the G-quadruplex structure. Interestingly, AFF3/LAF4 and AFF4/AF5q31, like AFF2/FMR2, modulate, in vivo, the splicing efficiency of a mini-gene containing a G-quadruplex structure in one alternatively spliced exon. Furthermore, we observed that the overexpression of AFF2/3/4 interferes with the organization and/or biogenesis of nuclear speckles. These findings fit well with our observation that enlarged nuclear speckles are present in FRAXE fibroblasts. Furthermore, our findings suggest functional redundancy among the AFF family members in the regulation of splicing and transcription. It is possible that other members of the AFF family compensate for the loss of AFF2/FMR2 activity and as such explain the relatively mild to borderline phenotype observed in FRAXE patients.
- Published
- 2011
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