Affinage

TAF9B

Transcription initiation factor TFIID subunit 9B · UniProt Q9HBM6

Length
251 aa
Mass
27.6 kDa
Annotated
2026-06-10
9 papers in source corpus 6 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TAF9B (TAF9L/TAFII31L) is a paralog of TAF9 that functions as a bona fide subunit of the general transcription complexes TFIID and TFTC, where it integrates via histone-fold pairing with TAF6 analogous to TAF9 (PMID:15899866). Despite this structural redundancy, TAF9B is essential for cell viability and directs a transcriptional program largely distinct from TAF9, with only minimal overlap in regulated genes (PMID:15899866, PMID:12837753). TAF9B acts as a coactivator and stabilizer of p53, and TAF9B and TAF9 are differentially induced during apoptosis (PMID:15899866). Beyond core transcription, TAF9B supports specialized transcriptional programming, being required for IL-4-dependent TH2 cell expansion and type II immune responses (PMID:41671377). Multiple microRNAs converge on the TAF9B 3'UTR—miR-146a, miR-7-5p, and miR-199—to post-transcriptionally restrict its expression and thereby modulate p53-dependent apoptosis and autophagy in disease contexts including doxorubicin-treated cardiomyocytes and osteosarcoma cells (PMID:31511497, PMID:33958878, PMID:35873641).

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 2003 Medium

    Established whether the TAF9 paralog TAF9L carries an independent, non-redundant function rather than being a mere backup copy, by testing its requirement for cell growth.

    Evidence RNA interference and a conditional TAF9 allele in DT40/HeLa cells with transcription assays

    PMID:12837753

    Open questions at the time
    • Did not define the molecular complex context of TAF9L action
    • Mechanism of the implied transcriptional repression/silencing role unresolved
    • Direct target genes not identified
  2. 2005 High

    Resolved how TAF9B is incorporated into the transcriptional machinery and showed it occupies a genuine subunit role, establishing it as a TFIID/TFTC component that pairs with TAF6 via histone folds.

    Evidence MALDI mass spectrometry, reciprocal Co-IP, and in vitro/in vivo interaction assays

    PMID:15899866

    Open questions at the time
    • Stoichiometry of TAF9 versus TAF9B within individual complexes not defined
    • No structural model of the TAF9B-containing complex
  3. 2005 Medium

    Distinguished TAF9B from TAF9 functionally, showing it regulates a distinct gene set, is essential for viability, and uniquely stabilizes p53 during apoptosis.

    Evidence siRNA knockdown, gene expression microarray, and apoptosis assays

    PMID:15899866

    Open questions at the time
    • Molecular basis for differential gene selectivity versus TAF9 unknown
    • Mechanism of p53 stabilization not defined
    • Single-lab evidence for the apoptosis link
  4. 2021 Medium

    Connected TAF9B to downstream survival signaling, implicating it in AKT/mTOR activation and Bcl-2/Bax-mediated apoptotic control.

    Evidence TAF9B overexpression/knockdown, dual-luciferase reporter, western blotting, and flow cytometry in osteosarcoma cells

    PMID:33958878

    Open questions at the time
    • Whether AKT/mTOR effects are direct transcriptional outputs of TAF9B unknown
    • Single cancer cell-type context
  5. 2019 Medium

    Defined post-transcriptional control of TAF9B, showing microRNAs targeting its 3'UTR govern p53-dependent apoptosis and autophagy.

    Evidence miR-146a, miR-7-5p, and miR-199 overexpression/knockdown, dual-luciferase reporters, and knockout/functional readouts in cardiomyocytes and tumor cells

    PMID:31511497 PMID:33958878 PMID:35873641

    Open questions at the time
    • Endogenous regulatory hierarchy among the three microRNAs unresolved
    • Physiological conditions selecting each microRNA-TAF9B axis not defined
  6. 2026 Medium

    Extended TAF9B function to specialized immune transcriptional programming, showing it is required for TH2 cell expansion and IL-4-dependent type II responses.

    Evidence Taf9b-deficient mouse T cells, adoptive transfer, and murine colitis/arthritis models

    PMID:41671377

    Open questions at the time
    • TAF9B target genes within the TH2 program not identified
    • Whether the role requires TFIID/TFTC incorporation not tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • How TAF9B-containing complexes achieve gene selectivity distinct from TAF9, and how this links to its p53, AKT/mTOR, and TH2 roles, remains unresolved.
  • No mechanistic link between TAF9B complex composition and its distinct target genes
  • No structural data on TAF9B-containing TFIID/TFTC
  • Direct transcriptional targets in p53 and immune programs unidentified

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 3 GO:0005198 structural molecule activity 1
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-74160 Gene expression (Transcription) 2
Partners
TAF6
Complex memberships
TFIIDTFTC

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2005 TAF9b (TAF9L) is a bona fide subunit of both TFIID and TFTC transcriptional regulatory complexes, where it forms histone fold pair interactions with TAF6 analogous to TAF9-TAF6 interactions. MALDI mass spectrometry identification, Co-immunoprecipitation, in vitro and in vivo interaction assays Molecular and cellular biology High 15899866
2005 TAF9b and TAF9 are differentially induced during apoptosis and differ in their ability to stabilize p53, with TAF9b acting as a coactivator/stabilizer of p53. siRNA knockdown, gene expression analysis, apoptosis assays Molecular and cellular biology Medium 15899866
2005 siRNA knockdown of TAF9b is essential for cell viability, and TAF9b regulates a distinct set of genes from TAF9 with only small overlap. siRNA knockdown, gene expression microarray analysis Molecular and cellular biology Medium 15899866
2003 TAF9L (TAF9b) is partly redundant with TAF9, but RNA interference experiments indicate TAF9L is essential for HeLa cell growth and plays a role in transcriptional repression and/or silencing. Conditional TAF9 allele in DT40 cells, RNA interference, transcription assays The Journal of biological chemistry Medium 12837753
2019 miR-146a targets TAF9b (a coactivator and stabilizer of p53), indirectly destabilizing p53 and thereby inhibiting apoptosis and modulating autophagy in cardiomyocytes exposed to doxorubicin. miR-146a overexpression/knockdown in cardiomyocytes, miR-146a knockout mice, target validation (presumably luciferase reporter), apoptosis/autophagy assays Cell death & disease Medium 31511497
2021 TAF9B activates the AKT/mTOR signaling pathway and regulates apoptosis by upregulating Bcl-2 and downregulating Bax and Cleaved-caspase-3 in osteosarcoma cells; miR-7-5p binds the 3'UTR of TAF9B to suppress its translation. TAF9B overexpression and knockdown, dual luciferase reporter assay, western blotting, flow cytometry OncoTargets and therapy Medium 33958878
2022 miR-199 targets TAF9b (confirmed by dual-luciferase reporter assay), and TAF9b knockdown reverses the myocardial protective effect of miR-199 inhibition, placing TAF9b downstream of miR-199 in doxorubicin-induced cardiomyocyte apoptosis and autophagy. Dual-luciferase reporter assay, TAF9b knockdown, TUNEL staining, flow cytometry, western blotting Evidence-based complementary and alternative medicine Medium 35873641
2026 TAF9B is required for magnetoelectric nanoparticle-driven TH2 cell expansion and IL-4-dependent type II immune response; Taf9b-deficient T cells fail to respond to magnetoelectric stimulation, demonstrating TAF9B is essential for this transcriptional programming in TH2 cells. Taf9b-deficient mouse T cells, adoptive transfer experiments, murine colitis and arthritis models, genetic loss-of-function Science advances Medium 41671377

Source papers

Stage 0 corpus · 9 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2019 miR-146a attenuates apoptosis and modulates autophagy by targeting TAF9b/P53 pathway in doxorubicin-induced cardiotoxicity. Cell death & disease 105 31511497
2005 TAF9b (formerly TAF9L) is a bona fide TAF that has unique and overlapping roles with TAF9. Molecular and cellular biology 54 15899866
2003 Genetic mapping of Dn7, a rye gene conferring resistance to the Russian wheat aphid in wheat. TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik 20 12879254
2003 In vivo functional analysis of the histone 3-like TAF9 and a TAF9-related factor, TAF9L. The Journal of biological chemistry 15 12837753
2005 Comparison of Dn4- and Dn7-carrying spring wheat genotypes artificially infested with Russian wheat aphid (Homoptera: Aphididae) biotype 1. Journal of economic entomology 10 16334342
2021 Downregulation of TAF9B by miR-7-5p Inhibits the Progression of Osteosarcoma. OncoTargets and therapy 9 33958878
2022 MiR-199 Aggravates Doxorubicin-Induced Cardiotoxicity by Targeting TAF9b. Evidence-based complementary and alternative medicine : eCAM 6 35873641
2012 [Isolation and identification of aerobic denitrifying bacterium Defluvibacter lusatiensis strain DN7 and its heterotrophic nitrification ability]. Ying yong sheng tai xue bao = The journal of applied ecology 1 23173477
2026 Magnetoelectric nanoparticles drive TAF9B+ TH2 cell expansion to alleviate inflammation. Science advances 0 41671377

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