RBPMS2

RBPMS2 is an RRM-domain RNA-binding protein that controls cell-fate decisions across smooth muscle, cardiac, and germline lineages by regulating the translation and splicing of target mRNAs (PMID:25064856, PMID:36367103, PMID:38898112). In visceral smooth muscle, RBPMS2 marks undifferentiated precursors and drives dedifferentiation by upregulating NOGGIN mRNA, thereby lowering BMP activity (PMID:22683258); this activity depends on a conserved homodimerization motif within its single RRM domain (residues 39–51) that is also required for its interaction with the translational elongation factor eEF2, such that mutation of a single conserved leucine abolishes dimerization and all downstream functions (PMID:25064856). In cardiomyocytes, RBPMS2 acts as a conserved alternative-splicing regulator: it is required for proper splicing of a network of cardiac genes (including RBFOX2, SLC8A1, and MYBPC3) in both zebrafish and human iPSC-derived cardiomyocytes (PMID:36367103), and it cooperates redundantly with its paralog RBPMS to safeguard sarcomere assembly, with the binding position on pre-mRNA dictating whether RBPMS2 acts as a splicing activator or repressor (PMID:40859824, PMID:39574760). One critical splicing output is the balance of nuclear versus cytoplasmic Camk2g isoforms, whose disruption causes mitotic defects rescued by the Rbpms2a isoform (PMID:40602408). In zebrafish oocytes, RBPMS2 localizes to germ granules and the Balbiani body and functions as a binary female-fate switch, translationally repressing testis-fate and ribosome-biogenesis factors while promoting nucleolar amplification through the Gator2 component Mios and the mTORC1 pathway (PMID:29975683, PMID:38898112).

1. 2012 Medium

   Established that RBPMS2 is not merely a precursor marker but an active determinant of smooth muscle cell plasticity, working through the NOGGIN/BMP axis.

   Evidence Retroviral misexpression in vivo and in primary chicken SMC cultures with BMP-activity and differentiation-marker readouts

   PMID:22683258

   Open questions at the time

   • Mechanism by which RBPMS2 upregulates NOGGIN (translational vs. transcriptional) not resolved
   • Single-lab functional study without direct RNA-target identification
2. 2014 High

   Defined the structural basis of RBPMS2 activity, showing a conserved RRM-internal homodimerization motif couples self-association to eEF2 binding and to NOGGIN regulation.

   Evidence RRM mutagenesis, co-immunoprecipitation of eEF2, in vivo misexpression rescue, and cross-species conservation analysis

   PMID:25064856

   Open questions at the time

   • No high-resolution structure of the dimer or the eEF2 complex
   • How eEF2 binding translates into NOGGIN mRNA regulation is not mechanistically defined
3. 2018 High

   Resolved domain-specific subcellular targeting and germline function, separating RNA-binding-dependent germ-granule/Balbiani-body localization from C-terminal-dependent centrosome/spindle localization.

   Evidence Zebrafish rbpms2a;2b double mutants, domain-deletion rescue constructs, immunohistochemistry, EM, and live imaging

   PMID:29975683

   Open questions at the time

   • RNA cargo localized to germ granules not identified in this study
   • Role of centrosome/spindle localization in somatic cells unexplained
4. 2022 High

   Identified RBPMS2 as a conserved cardiomyocyte alternative-splicing regulator, linking its loss to contractile dysfunction across zebrafish and human cells.

   Evidence Zebrafish knockout, RNA-seq splicing analysis, human iPSC-derived RBPMS2-deficient cardiomyocytes, and calcium imaging

   PMID:36367103

   Open questions at the time

   • Direct binding sites on cardiac targets not mapped
   • Relationship between splicing role and earlier eEF2/translational role unclear
5. 2023 Medium

   Extended RBPMS2 function to early mammalian development, placing it upstream of BMP signaling in the morula-to-blastocyst transition.

   Evidence Morpholino/siRNA knockdown in mouse embryos, RNA-seq, BMP inhibitor/activator rescue, and E-cadherin immunofluorescence

   PMID:37573751

   Open questions at the time

   • Direct RNA targets mediating the BMP and E-cadherin effects not identified
   • Knockdown rather than genetic deletion
6. 2024 High

   Defined the molecular logic of RBPMS2's female-fate decision in oocytes, connecting translational repression of testis factors to mTORC1-driven nucleolar amplification via Gator2/Mios.

   Evidence RNA immunoprecipitation to identify bound rboRNAs, genetic epistasis of rbpms2 and mios mutants, and polysome/translational assays in zebrafish

   PMID:38898112

   Open questions at the time

   • How RBPMS2 mechanistically activates mTORC1 through Mios not resolved
   • Sequence determinants distinguishing repressed targets not defined
7. 2024 Low

   Tested whether the sex-fate role generalizes to teleost gonadal cells, showing Rbpms2 binds sex-gene transcripts and biases expression toward female fate.

   Evidence siRNA knockdown and overexpression in primary flounder gonadal cells, in silico binding-site analysis, and qRT-PCR

   PMID:39414089

   Open questions at the time

   • No binding confirmation by RIP/CLIP; binding inferred in silico only
   • No in vivo genetic validation
   • Cannot distinguish direct regulation from indirect effects
8. 2025 High

   Demonstrated functional redundancy with the paralog RBPMS in cardiac splicing and established a positional code in which pre-mRNA binding location dictates activator versus repressor activity.

   Evidence Cardiomyocyte-specific single and double Rbpms/Rbpms2 knockout mice, RNA-seq splicing maps, and minigene assays

   PMID:39574760 PMID:40859824

   Open questions at the time

   • Structural basis of positional activator/repressor switching not defined
   • Features of target exons requiring one versus both proteins only partly characterized
9. 2025 High

   Pinpointed a specific splicing output—Camk2g nuclear/cytoplasmic isoform balance—as the cause of mitotic defects in cardiomyocytes lacking RBPMS proteins.

   Evidence Compound knockout mice with cardiomyocyte deletion and Rbpms2a isoform rescue, plus analysis of Camk2g isoform distribution and embryonic lethality

   PMID:40602408

   Open questions at the time

   • How Camk2g isoform imbalance mechanistically triggers mitotic failure not fully resolved
   • Whether other splicing targets contribute to the phenotype unclear
10. 2025 Medium

    Implicated RBPMS2 in suppressing cancer-cell death, linking it to inhibition of NLRP3/caspase-1/GSDMD pyroptosis in gastric cancer.

    Evidence RBPMS2 knockout in gastric cancer cells, western blotting of pyroptosis pathway proteins, MCC950 pharmacological rescue, and membrane-damage assays

    PMID:40595708

    Open questions at the time

    • Direct RNA target connecting RBPMS2 to NLRP3 not identified
    • Whether effect is splicing- or translation-mediated unknown

• How RBPMS2's biochemical activities—RRM-dependent RNA binding, homodimerization, and eEF2 interaction—are mechanistically partitioned between translational regulation and alternative splicing across its diverse tissue contexts remains unresolved.
• No unified model reconciling eEF2-coupled translational control with splicing-factor activity
• Tissue-specific cofactors directing each activity not identified
• No experimental structure of RBPMS2 bound to RNA or partner proteins