The C terminus of fragile X mental retardation protein interacts with the multi-domain Ran-binding protein in the microtubule-organising centre

National Institute for Medical Research, London NW7 1AA, UK.
Journal of Molecular Biology (Impact Factor: 4.33). 11/2004; 343(1):43-53. DOI: 10.1016/j.jmb.2004.08.024
Source: PubMed

ABSTRACT Absence of the fragile X mental retardation protein (FMRP) causes fragile X syndrome, the most common form of hereditary mental retardation. FMRP is a mainly cytoplasmic protein thought to be involved in repression of translation, through a complex network of protein-protein and protein-RNA interactions. Most of the currently known protein partners of FMRP recognise the conserved N terminus of the protein. No interaction has yet been mapped to the highly charged, poorly conserved C terminus, so far thought to be involved in RNA recognition through an RGG motif. In the present study, we show that a two-hybrid bait containing residues 419-632 of human FMRP fishes out a protein that spans the sequence of the Ran-binding protein in the microtubule-organising centre (RanBPM/RanBP9). Specific interaction of RanBPM with FMRP was confirmed by in vivo and in vitro assays. In brain tissue sections, RanBPM is highly expressed in the neurons of cerebral cortex and the cerebellar purkinje cells, in a pattern similar to that described for FMRP. Sequence analysis shows that RanBPM is a multi-domain protein. The interaction with FMRP was mapped in a newly identified CRA motif present in the RanBPM C terminus. Our results suggest that the functional role of RanBPM binding is modulation of the RNA-binding properties of FMRP.

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    • "It was previously suggested that RanBPM interacted with microtubules, but this observation was later dismissed as the original study used an antibody that did not recognize RanBPM (Nakamura et al., 1998; Nishitani et al., 2001). Some studies have subsequently suggested a potential role for RanBPM in microtubule regulation (Menon et al., 2004; Togashi et al., 2006), although a direct association of RanBPM with microtubules remains to be confirmed. Interestingly, the highly similar protein RanBP10, whose expression is restricted to hematopoietic cell lineages, has been shown to function in platelet microtubule organization through an interaction with b1-tubulin (Kunert et al., 2009; Schulze et al., 2008). "
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    ABSTRACT: In conditions of proteasomal impairment, the build-up of damaged or misfolded proteins activates a cellular response leading to the recruitment of damaged proteins into perinuclear aggregates called aggresomes. Aggresome formation involves the retrograde transport of cargo proteins along the microtubule network and is dependent on the histone deacetylase HDAC6. Here we show that ionizing radiation (IR) promotes Ran-Binding Protein M (RanBPM) relocalization into discrete perinuclear foci where it co-localizes with aggresome components ubiquitin, dynein and HDAC6, suggesting that the RanBPM perinuclear clusters correspond to aggresomes. RanBPM was also recruited to aggresomes following treatment with the proteasome inhibitor MG132 and the DNA-damaging agent etoposide. Strikingly, aggresome formation by HDAC6 was markedly impaired in RanBPM shRNA cells, but was restored by re-expression of RanBPM. RanBPM was found to interact with HDAC6 and to inhibit its deacetylase activity. This interaction was abrogated by a RanBPM deletion of its LisH/CTLH domain, which also prevented aggresome formation, suggesting that RanBPM promotes aggresome formation through an association with HDAC6. Our results suggest that RanBPM regulates HDAC6 activity and is a central regulator of aggresome formation.
    Biology Open 05/2014; 3(6). DOI:10.1242/bio.20147021 · 2.42 Impact Factor
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    • "YPEL5 binding site of RanBPM protein Eleven partial cDNA clones for YPEL5-binding protein screened by Y2H covered various regions of RanBPM protein and their minimum overlapping region (MOR) corresponded to a distinct region of 146– 330 aa (Fig. 5A). Human RanBPM has four domains, namely SPRY, LisH, CTLH and CRA (Fig. 5A) [9]. The MOR corresponds to almost entire SPRY domain; hence, the SPRY domain was considered necessary for binding of YPEL5. "
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    ABSTRACT: YPEL5 is a member of the YPEL gene family that is highly conserved in the eukaryotic species and apparently involved in a certain cell division-related function. In this study, we examined the functional and phylogenetic aspects of YPEL5 protein in more detail. During cell cycle, YPEL5 protein was detected at different subcellular localizations; at interphase, it was located in the nucleus and centrosome, then it changed location sequentially to spindle poles, mitotic spindle, and spindle midzone during mitosis, and finally transferred to midbody at cytokinesis. Knockdown of YPEL5 function by siRNA or anti-sense morpholino oligonucleotide inhibited the growth of cultured COS-7 cells and early development of medaka fish embryos, indicating its involvement in cell cycle progression. Interestingly, RanBPM (Ran Binding Protein in the Microtubule organizing center, encoded by RANBP9) was identified as a YPEL5-binding protein by yeast two-hybrid method. A paralog of RanBPM, namely RanBP10 (encoded by RANBP10), was found to be another YPEL5-binding protein, and these two protein genes are highly conserved each other. Comparative genomic analysis allowed us to define a new gene family consisting of RanBPM and RanBP10, named Scorpin, providing a basis to better understand how they interact with YPEL5.
    Genomics 08/2010; 96(2):102-11. DOI:10.1016/j.ygeno.2010.05.003 · 2.79 Impact Factor
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    • "While the presence of RNA-binding and protein interaction domains in the N-terminal amino acids of FMRP and the FXR paralogs have been noted for some time, a role for C-terminal amino acids had been less clear. Recent studies of the hFMRP C-terminal peptide strongly indicate that it has protein interaction capacity, as judged by yeast two-hybrid screening using the C-terminal peptide as a bait (Menon et al., 2004), and the finding that a C-terminal truncation of hFMRP inhibits its interaction with kinesin (Dictenberg et al., 2008). A comparison of the C-terminal 81 amino acids encoded by exons 16-17 of FMR1 and the terminal 81 amino acids of dFMR1 shows significant conservation, with 31 of 81 residues (38%) being identical or similar (Figure 1E). "
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    ABSTRACT: The diversity of protein isoforms arising from alternative splicing is thought to modulate fine-tuning of synaptic plasticity. Fragile X mental retardation protein (FMRP), a neuronal RNA binding protein, exists in isoforms as a result of alternative splicing, but the contribution of these isoforms to neural plasticity are not well understood. We show that two isoforms of Drosophila melanogaster FMRP (dFMR1) have differential roles in mediating neural development and behavior functions conferred by the dfmr1 gene. These isoforms differ in the presence of a protein interaction module that is related to prion domains and is functionally conserved between FMRPs. Expression of both isoforms is necessary for optimal performance in tests of short- and long-term memory of courtship training. The presence or absence of the protein interaction domain may govern the types of ribonucleoprotein (RNP) complexes dFMR1 assembles into, with different RNPs regulating gene expression in a manner necessary for establishing distinct phases of memory formation.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 05/2010; 30(19):6782-92. DOI:10.1523/JNEUROSCI.6369-09.2010 · 6.75 Impact Factor
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