TNRC6B

TNRC6B is a GW-repeat-containing effector of the miRNA silencing pathway that bridges Argonaute-loaded miRNA complexes to the machinery that represses bound transcripts (PMID:19383768). Its N-terminal GW-repeat region binds all four human Argonaute proteins (AGO1–AGO4), recruiting TNRC6B to miRNA targets (PMID:19383768). Once recruited, its C-terminal silencing domain acts autonomously — independently of the AGO interaction — to silence the bound mRNA through translational repression and mRNA destabilization, including deadenylation (PMID:19383768). TNRC6B expression is itself subject to miRNA control, with miR-329-3p binding the TNRC6B 3'UTR to downregulate it (PMID:41882181). A synonymous variant (c.3141G>A) disrupts normal splicing by causing exon 7 skipping, linking TNRC6B sequence integrity to transcript processing (PMID:39115759). Beyond the AGO-binding and silencing-domain architecture established in (PMID:19383768), no further mechanistic detail of substrate selection or recruitment of downstream deadenylation factors has been characterized in the available corpus.

1. 2009 High

   Established how TNRC6B is recruited to miRNA targets by mapping the physical interface to Argonaute proteins, answering whether this GW182-family protein couples to the core silencing effectors.

   Evidence Pulldown/co-immunoprecipitation of the N-terminal GW-repeat domain against AGO1–AGO4 in human cells

   PMID:19383768

   Open questions at the time

   • Does not resolve the stoichiometry or relative affinity across the four AGO paralogs
   • Structural basis of GW-repeat recognition not determined
2. 2009 High

   Defined the downstream effector activity by showing the C-terminal silencing domain is sufficient to repress a tethered mRNA without AGO, distinguishing recruitment from execution of silencing.

   Evidence Tethering assays with isolated C-terminal constructs plus protein-expression, mRNA-stability, and deadenylation readouts

   PMID:19383768

   Open questions at the time

   • Identity of the deadenylase and decay factors recruited by the C-terminal domain not established in the corpus
   • Relative contribution of translational repression versus mRNA decay not quantified
3. 2009 High

   Integrated the two domains into a recruitment-then-silencing model, establishing that N-terminal AGO binding and C-terminal silencing are separable and epistatically ordered.

   Evidence Domain-separation genetic dissection coupled to functional silencing assays

   PMID:19383768

   Open questions at the time

   • In vivo physiological targets of TNRC6B-mediated silencing not identified
   • All three mechanistic findings derive from a single study
4. 2024 Medium

   Addressed how a clinically observed synonymous variant could be pathogenic by showing it disrupts splicing rather than coding, expanding the interpretation of TNRC6B sequence variants.

   Evidence Minigene assay with Sanger sequencing confirming c.3141G>A-induced exon 7 skipping

   PMID:39115759

   Open questions at the time

   • Single lab and single method
   • Effect of the truncated/altered transcript on protein function not assessed
5. 2026 Low

   Identified upstream regulation of TNRC6B itself, showing the silencing effector is a miRNA target, establishing a feedback layer on the pathway.

   Evidence Dual-luciferase reporter assay of miR-329-3p against the TNRC6B 3'UTR with RT-qPCR correlation

   PMID:41882181

   Open questions at the time

   • Single luciferase assay without orthogonal validation or mutagenesis of the seed site
   • No follow-up linking miR-329-3p regulation to TNRC6B protein function or downstream silencing

• The endogenous mRNA targets of TNRC6B and the identity of the decay/deadenylation factors it recruits in cells remain unresolved.
• No transcriptome-wide target set characterized in the corpus
• Downstream deadenylase/decay partners not identified
• No structural model of the AGO–GW interface