TNS3

TNS3 (Tensin3) is a cytoskeletal regulatory protein that organizes the actin cytoskeleton and restrains cell motility, with haploinsufficiency in patient-derived fibroblasts producing broader, shorter cells, loss of Tensin3 localization along cytoskeletal filaments and the cell periphery, and elevated migration (PMID:23809228). Its expression is set epigenetically: the histone H3K4 methyltransferase MLL3 deposits H3K4me1 and H3K27ac on an enhancer ~7 kb upstream that physically loops to the TNS3 promoter, and loss of this enhancer regulation enhances migration in a manner fully rescued by re-expressing TNS3 (PMID:33824309), while CpG-island hypermethylation of the TNS3 promoter silences expression and correlates with reduced TNS3 in renal cell carcinoma (PMID:23803643). In an esophageal squamous cell carcinoma context TNS3 acts as a pro-proliferative factor whose loss impairs growth in vitro and in vivo and sensitizes cells to HDAC inhibition (PMID:34047714). A t(7;17) translocation in multicystic mesothelioma fuses TNS3 to MAP3K3 to generate a chimeric protein kinase (PMID:25484136). Beyond these regulatory and phenotypic findings, the biochemical activities of the Tensin3 SH2 and phosphotyrosine-binding domains have not been characterized in the available corpus.

1. 2013 Medium

   Established that Tensin3 is functionally required for normal cytoskeletal organization and for restraining cell migration, rather than being a passive structural marker.

   Evidence RT-PCR, western blot, immunofluorescence and live-cell scratch-wound migration assays in translocation patient-derived fibroblasts versus controls

   PMID:23809228

   Open questions at the time

   • Does not identify the molecular partners through which Tensin3 organizes filaments
   • Loss-of-function based on a single translocation patient line
   • No biochemical activity assigned to Tensin3 domains
2. 2013 Medium

   Showed that TNS3 expression is controlled by promoter CpG methylation, explaining how the gene is silenced in renal cell carcinoma.

   Evidence Luciferase minimal-promoter assay, pyrosequencing of CpG methylation, and pharmacological demethylation with expression readout in kidney cells

   PMID:23803643

   Open questions at the time

   • Correlative link between methylation and cancer phenotype not causally tested
   • Specific methyltransferases/demethylases not identified
   • Functional consequence of TNS3 loss in renal cells not assayed here
3. 2014 Medium

   Identified a recurrent oncogenic mechanism in which TNS3 is recombined into a chimeric kinase, implicating the locus in tumorigenic fusion events.

   Evidence RNA-seq, RT-PCR and Sanger sequencing of TNS3-MAP3K3 fusion transcripts from multicystic mesothelioma cells

   PMID:25484136

   Open questions at the time

   • Chimeric kinase activity not reconstituted or functionally validated
   • Contribution of the fusion to transformation untested
   • Single tumor sample
4. 2021 High

   Defined the upstream enhancer logic of TNS3, demonstrating that MLL3-deposited active chromatin marks at a looping enhancer drive TNS3 expression and that this axis controls migration.

   Evidence CRISPR MLL3 depletion, RNA-seq, H3K4me1/H3K27ac ChIP-seq, 3C looping assay, dCas9-KRAB enhancer repression and TNS3 rescue

   PMID:33824309

   Open questions at the time

   • Does not connect enhancer regulation to the methylation-based silencing seen elsewhere
   • Downstream effectors of TNS3 in migration not resolved
5. 2021 Medium

   Demonstrated a context-dependent pro-proliferative role for TNS3 in cancer, contrasting with its migration-restraining role in fibroblasts.

   Evidence siRNA knockdown of TNS3 with in vitro and xenograft proliferation assays and LMK-235 HDAC inhibitor sensitization in ESCC cells

   PMID:34047714

   Open questions at the time

   • Mechanism linking TNS3 to proliferation not defined
   • Tissue specificity of the pro-proliferative versus migration phenotype unexplained
6. 2026 Low

   Placed TNS3 downstream of the transcription factor IRF1, extending its regulation into renal stress, fibrosis and aging pathways.

   Evidence Gene-regulation analysis linking IRF1 to TNS3 targeting in a renal context

   PMID:41863168

   Open questions at the time

   • Limited methodological detail on how IRF1 occupancy/targeting was established
   • Direct binding versus indirect regulation not distinguished
   • Functional consequence of the IRF1-TNS3 axis not demonstrated

• The intrinsic biochemical activity of Tensin3 — what its SH2 and phosphotyrosine-binding domains engage to organize the cytoskeleton — remains undefined.
• No direct binding partners identified
• No structural model
• Mechanism connecting Tensin3 to actin filaments unknown