Homodimerization of RBPMS2 through a new RRM-interaction motif is necessary to control smooth muscle plasticity.
Bottom Line: RBPMS2 contains only one RNA recognition motif (RRM) while this motif is often repeated in tandem or associated with other functional domains in RRM-containing proteins.We also show that this specific motif is conserved among its homologs and paralogs in vertebrates and in its insect and worm orthologs (CPO and MEC-8, respectively) suggesting a conserved molecular mechanism of action.Our study demonstrates that RBPMS2 possesses an RRM domain harboring both RNA-binding and protein-binding properties and that the newly identified RRM-homodimerization motif is crucial for the function of RBPMS2 at the cell and tissue levels.
Affiliation: INSERM U1046, Université Montpellier 1, Université Montpellier 2, 34295 Montpellier, France.Show MeSH
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Mentions: We first screened these RBPMS2 mutant forms using PLA approach and we showed that in DF-1 cells that co-express Myc-RBPMS2-L49E and HA-RBPMS2, the interaction between RBPMS2 and RBPMS2-L49E is strongly decreased (Figure 3A). In contrast, the interaction between RBPMS2 and RBPMS2-L49Q is similar to that observed with wild-type RBPMS2 (Supplemental Figure S3A). We also analyzed these interaction using co-IP assays with anti-Myc antibodies in lysates from DF-1 cells that express HA-RBPMS2 and Myc-RBPMS2-L49E and found that L49E substitution decreased by 87% the interaction of RBPMS2 strongly altering the capacity of RBPMS2 to homodimerize (Figure 3B). In order to identify a potential instability or cellular mislocalization of RBPMS2-L49E protein, we analyzed its cellular localization and found that both RBPMS2 and RBPMS2-L49E were detected in stress granules where RNA granules are also localized (Figure 3C).
Affiliation: INSERM U1046, Université Montpellier 1, Université Montpellier 2, 34295 Montpellier, France.