RBMS3

RBMS3 is a sequence-specific RNA-binding protein that acts as a post-transcriptional regulator of gene expression by binding the 3'UTRs of target mRNAs to control their stability and translation (PMID:17586524, PMID:30279231, PMID:34608266). Its earliest characterized activity is mRNA stabilization: it binds a defined element in the Prx1 3'UTR to extend transcript half-life and drive Prx1-dependent collagen expression in hepatic stellate cells (PMID:17586524), and analogous 3'UTR binding stabilizes smad2/3 transcripts to support TGF-β/Smad2/3 signaling during chondrogenesis and stimulates Ptf1a translation during pancreatic development (PMID:23091072, PMID:22372950). In cancer, RBMS3 functions predominantly as a tumor suppressor by stabilizing transcripts encoding negative regulators of the Wnt/β-catenin axis—DKK3, AXIN1, BACH1, and NFAT5—thereby restraining β-catenin/CBP signaling, an activity antagonized by miR-126-5p (PMID:30279231), and by suppressing the same axis in BRAFV600E-driven lung tumors (PMID:36112789). It additionally limits EMT and metastasis by destabilizing or restraining EMT effectors and metastasis-linked transcripts including Twist1, PRRX1, and TXNIP (PMID:30819235, PMID:34608266). Beyond its RNA-dependent roles, RBMS3 also acts post-translationally: it physically recruits the E3 ubiquitin ligase TRIM21 to ANGPT2 in an RNA-independent manner to promote K48-linked polyubiquitination and proteasomal degradation, restraining angiogenesis (PMID:40069332). RBMS3 is itself positioned downstream of upstream regulatory inputs, being induced by LKB1/AMPK signaling and targeted by miR-21a-5p (PMID:37781074, PMID:40820584).

1. 2007 High

   Established that RBMS3 is a sequence-specific 3'UTR-binding protein that stabilizes a target mRNA, defining its core molecular activity.

   Evidence RIP/differential display identifying Prx1 mRNA, reporter assays with and without the mapped binding site, and ectopic expression in primary hepatic stellate cells

   PMID:17586524

   Open questions at the time

   • Mechanism of stabilization (decay machinery engaged) not defined
   • Generality of the 60-nt binding element to other targets unknown
2. 2012 High

   Showed RBMS3 acts in developmental signaling by stabilizing smad2/3 transcripts and promoting Ptf1a translation, extending its role from stabilization to translational control in distinct tissues.

   Evidence Zebrafish protein-trap localization, morpholino knockdown with pSmad2 readout, RIP and 3'UTR reporter assays; separately, 3'UTR binding specificity and reporter translation assays in pancreatic exocrine cells

   PMID:22372950 PMID:23091072

   Open questions at the time

   • How RBMS3 distinguishes stabilization versus translational stimulation among targets is unresolved
   • Direct binding partners mediating these outputs not identified
3. 2012 Medium

   Linked RBMS3 to tumor suppression through cell-cycle arrest, apoptosis, and anti-angiogenic phenotypes, broadening its physiological significance.

   Evidence Overexpression/RNAi in nasopharyngeal carcinoma lines with cell-cycle analysis, immunoblotting of p53/p21/cyclin E/CDK2/β-catenin targets, and microvessel assays

   PMID:22957092

   Open questions at the time

   • Phenotypes are correlative; direct mRNA targets driving these outputs not mapped
   • Whether β-catenin downregulation is post-transcriptional unaddressed at this stage
4. 2018 High

   Defined the mechanism by which RBMS3 restrains Wnt/β-catenin signaling: direct stabilization of multiple negative regulator mRNAs, with competition by miR-126-5p.

   Evidence CLIP-seq, RIP, and EMSA mapping direct binding to DKK3/AXIN1/BACH1/NFAT5; in vitro functional assays and intraperitoneal tumor model with pathway inhibitor rescue

   PMID:30279231

   Open questions at the time

   • Relative contribution of each target transcript not dissected
   • Structural basis of multi-target recognition unknown
5. 2019 Medium

   Demonstrated RBMS3 negatively regulates the EMT transcription factor Twist1 via direct 3'UTR binding, connecting RBMS3 to metastasis suppression.

   Evidence Reciprocal RIP, luciferase reporter with Twist1 3'UTR, Transwell assays, and in vivo lung metastasis model in breast cancer

   PMID:30819235

   Open questions at the time

   • Whether RBMS3 destabilizes versus represses translation of Twist1 not clarified
   • Single-lab validation
6. 2021 High

   Showed RBMS3 controls the EMT program through PRRX1 mRNA stability and can both induce and maintain mesenchymal states, refining its context-dependent role.

   Evidence Genome-wide mRNA stability profiling, RIP for PRRX1 mRNA, PRRX1 genetic rescue, and in vivo spontaneous metastasis model in TNBC

   PMID:34608266

   Open questions at the time

   • Reconciling EMT-promoting activity here with metastasis-suppressive roles elsewhere remains open
   • Determinants of cell-context-specific output not defined
7. 2022 High

   Validated RBMS3 as a Wnt/β-catenin suppressor and tumor suppressor in vivo, and identified RBMS3 loss as conferring resistance to BRAF/MEK inhibition but sensitivity to porcupine inhibition.

   Evidence Sleeping Beauty transposon screen, CRISPR knockout, lung organoid and GEM models, qRT-PCR of Wnt targets, and drug treatments

   PMID:36112789

   Open questions at the time

   • Direct mRNA targets mediating Wnt suppression in lung not mapped in this system
   • Mechanism connecting RBMS3 loss to drug resistance not biochemically resolved
8. 2022 Medium

   Revealed a context where RBMS3 stabilizes a pro-tumorigenic transcript (CD274/PD-L1), showing its 3'UTR-stabilization activity is not uniformly tumor-suppressive.

   Evidence RIP, mRNA stability assays, immunoblotting, RBMS3 knockdown in MDA-MB-231 cells, and in vivo T-cell immunity assays

   PMID:36414028

   Open questions at the time

   • What dictates stabilizing versus destabilizing outcomes on different targets is unknown
   • Single-lab finding
9. 2023 Medium

   Placed RBMS3 downstream of the LKB1/AMPK pathway as an effector of AMPK-mediated suppression of invasion, integrating it into upstream metabolic signaling.

   Evidence IHC co-expression, AMPK agonist/inhibitor treatments, RBMS3 knockdown rescue, and Transwell assays in lung cancer cells

   PMID:37781074

   Open questions at the time

   • Mechanism by which AMPK induces RBMS3 (transcriptional vs post-transcriptional) unknown
   • Pharmacological epistasis only
10. 2024 Medium

    Identified LIMS1 as an RBMS3-regulated transcript in colon cancer mediating its anti-proliferative and anti-invasive effects.

    Evidence RBMS3 gain/loss with LIMS1 mRNA stability assays and LIMS1 knockdown rescue, plus xenograft models

    PMID:38618967

    Open questions at the time

    • Direct binding (RIP) only implied
    • Direction of LIMS1 mRNA regulation not fully resolved
11. 2025 High

    Uncovered an RNA-independent function: RBMS3 scaffolds TRIM21 onto ANGPT2 to drive its K48-ubiquitination and degradation, establishing RBMS3 as a dual post-transcriptional/post-translational regulator.

    Evidence IP-MS and co-IP defining the RBMS3–TRIM21–ANGPT2 complex, K48-ubiquitination assays, RNA-independence confirmation, and in vivo functional rescue in HCC

    PMID:40069332

    Open questions at the time

    • Structural basis of TRIM21/ANGPT2 bridging not defined
    • Whether other substrates use this RNA-independent mode unknown
12. 2025 Medium

    Showed RBMS3 forms a complex with ELAVL1 and UPF1 and destabilizes ELAVL1 mRNA to suppress angiogenic signaling, adding a complex-based regulatory layer.

    Evidence Co-IP, immunofluorescence, mRNA stability and methylation assays, and ELAVL1 rescue in ovarian cancer models

    PMID:42002122

    Open questions at the time

    • Functional consequence of RBMS3-mediated UPF1 methylation inhibition uncharacterized
    • Direct vs indirect ELAVL1 mRNA targeting not separated
13. 2025 Medium

    Positioned RBMS3 within upstream miRNA control and downstream TGF-β signaling in a vascular/ischemic context, and in MSC osteogenesis via MAPK signaling, extending its roles beyond cancer.

    Evidence Dual luciferase reporter for miR-21a-5p/RBMS3, AAV knockdown in a TIA model with TGFBR1/SMAD2/3 analysis; and lentiviral Rbms3 perturbation in MSCs with MAPK readouts and in vivo fracture healing

    PMID:40718133 PMID:40820584

    Open questions at the time

    • Direct mRNA targets in these non-cancer contexts not mapped
    • Mechanistic link between RBMS3 and MAPK components unresolved

• What determines whether RBMS3 stabilizes versus destabilizes a given target, and how its RNA-dependent and RNA-independent (TRIM21-scaffold) activities are coordinated, remains unresolved.
• No structural model of RBMS3 target/partner recognition
• Rules governing stabilizing vs destabilizing fate of bound transcripts unknown
• Interplay between post-transcriptional and post-translational modes uncharacterized