Dataset Information

Modulation of dADAR-dependent RNA editing by the Drosophila fragile X mental retardation protein.

ABSTRACT: Loss of FMR1 gene function results in fragile X syndrome, the most common heritable form of intellectual disability. The protein encoded by this locus (FMRP) is an RNA-binding protein that is thought to primarily act as a translational regulator; however, recent studies have implicated FMRP in other mechanisms of gene regulation. We found that the Drosophila fragile X homolog (dFMR1) biochemically interacted with the adenosine-to-inosine RNA-editing enzyme dADAR. Adar and Fmr1 mutant larvae exhibited distinct morphological neuromuscular junction (NMJ) defects. Epistasis experiments based on these phenotypic differences revealed that Adar acts downstream of Fmr1 and that dFMR1 modulates dADAR activity. Furthermore, sequence analyses revealed that a loss or overexpression of dFMR1 affects editing efficiency on certain dADAR targets with defined roles in synaptic transmission. These results link dFMR1 with the RNA-editing pathway and suggest that proper NMJ synaptic architecture requires modulation of dADAR activity by dFMR1.

SUBMITTER: Bhogal B

PROVIDER: S-EPMC3225737 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Modulation of dADAR-dependent RNA editing by the Drosophila fragile X mental retardation protein.

Bhogal Balpreet B Jepson James E JE Savva Yiannis A YA Pepper Anita S-R AS Reenan Robert A RA Jongens Thomas A TA

Nature neuroscience 20111030 12

Loss of FMR1 gene function results in fragile X syndrome, the most common heritable form of intellectual disability. The protein encoded by this locus (FMRP) is an RNA-binding protein that is thought to primarily act as a translational regulator; however, recent studies have implicated FMRP in other mechanisms of gene regulation. We found that the Drosophila fragile X homolog (dFMR1) biochemically interacted with the adenosine-to-inosine RNA-editing enzyme dADAR. Adar and Fmr1 mutant larvae exhi ...[more]

PMID: 22037499

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Project description:Fragile X syndrome (FXS), the most common inherited determinant of intellectual disability and autism spectrum disorders, is caused by loss of the fragile X mental retardation 1 (FMR1) gene product (FMRP), an mRNA-binding translational repressor. A number of conserved FMRP targets have been identified in the well-characterized Drosophila FXS disease model, but FMRP is highly pleiotropic in function and the full spectrum of FMRP targets has yet to be revealed. In this study, screens for upregulated neural proteins in Drosophila fmr1 (dfmr1) null mutants reveal strong elevation of two synaptic heparan sulfate proteoglycans (HSPGs): GPI-anchored glypican Dally-like protein (Dlp) and transmembrane Syndecan (Sdc). Our recent work has shown that Dlp and Sdc act as co-receptors regulating extracellular ligands upstream of intracellular signal transduction in multiple trans-synaptic pathways that drive synaptogenesis. Consistently, dfmr1 null synapses exhibit altered WNT signaling, with changes in both Wingless (Wg) ligand abundance and downstream Frizzled-2 (Fz2) receptor C-terminal nuclear import. Similarly, a parallel anterograde signaling ligand, Jelly belly (Jeb), and downstream ERK phosphorylation (dpERK) are depressed at dfmr1 null synapses. In contrast, the retrograde BMP ligand Glass bottom boat (Gbb) and downstream signaling via phosphorylation of the transcription factor MAD (pMAD) seem not to be affected. To determine whether HSPG upregulation is causative for synaptogenic defects, HSPGs were genetically reduced to control levels in the dfmr1 null background. HSPG correction restored both (1) Wg and Jeb trans-synaptic signaling, and (2) synaptic architecture and transmission strength back to wild-type levels. Taken together, these data suggest that FMRP negatively regulates HSPG co-receptors controlling trans-synaptic signaling during synaptogenesis, and that loss of this regulation causes synaptic structure and function defects characterizing the FXS disease state.

Dataset Information

Modulation of dADAR-dependent RNA editing by the Drosophila fragile X mental retardation protein.

Publications

Modulation of dADAR-dependent RNA editing by the Drosophila fragile X mental retardation protein.

Similar Datasets

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