TBX20 (human, Q9UMR3) curation notes

Automated deep research was unavailable for this session (falcon 402, OpenAI 401), so no
-deep-research-<provider>.md file exists. These notes were compiled manually from cached
publications (abstracts unless noted), UniProt, and QuickGO.

Identity and domains

• T-box transcription factor (TBX1 subfamily); single T-box DNA-binding domain; UniProt function
  is ECO:0000250 (by similarity to mouse): "Acts as a transcriptional activator and repressor
  required for cardiac development and may have key roles in the maintenance of functional and
  structural phenotypes in adult heart."
• Disease: Atrial septal defect 4 (ASD4, MIM:611363) [PMID:17668378; PMID:19762328].
• Alternatively spliced: the long isoform (Tbx20a) carries C-terminal transactivation and
  transrepression domains PMID:14550786.

Molecular function

• Sequence-specific DNA binding at brachyury-like half sites PMID:14550786.
• In vivo ChIP-seq motif in adult mouse heart: AGGTGNTGACAG PMID:22328084.
• Human TBX20 included in HT-SELEX survey of human TF specificities PMID:28473536 (TBX20 data are in supplementary tables; not quotable from the cached text).
• Dual activator/repressor: PMID:22328084.
• Activation of cardiac enhancers with partners: PMID:15843409; PMID:14550786.
• Human TBX20 ChIP/luciferase (Nppa, Gja5), gain-of-function I121M PMID:19762328.
• Interaction with TBX5 PMID:15634698.
• Repression of Tbx2 in chamber myocardium PMID:15843414; mechanism partly non-DNA-binding via Smad sequestration PMID:19661464.

Biological processes (mostly mouse)

• Heart tube elongation / chamber formation [PMID:15901664 "The tube does not elongate, indicating a defect in recruitment of mesenchyme from the secondary heart field"; "Tbx20 is required for progression from the linear heart tube to a multi-chambered heart"].
• Outflow tract, RV, valves (graded knockdown) PMID:15843409.
• AV canal formation and endocardial EMT via Bmp2 PMID:21983003.
• Endocardial cushion mesenchyme proliferation/ECM (chick) PMID:17064679.
• Cardiomyocyte proliferation PMID:23751911.
• Adult cardiomyocyte homeostasis PMID:22080862.
• Motor neurons: [PMID:15843409 role in Isl2/Hb9 regulation]; PMID:17119020.
• Human: ASD, valve defects, cardiomyopathy PMID:17668378; ASDII/PFO GOF variant PMID:19762328; Chinese CHD cohort ASD/TAPVC/TOF [PMID:18834961, abstract-only]; TBX20 expression in TOF biopsies [PMID:18275040, abstract-only].

Points of curation interest

• Rat-derived GO:0043065 "positive regulation of apoptotic process" (RGD IMP, PMID:27572266) is
  directionally inverted relative to the paper: silencing TBX20 induced apoptosis
  PMID:27572266.
• Xenopus-derived endoderm formation / lateral mesoderm formation (ISS) rest on ectopic
  overexpression PMID:14550786, not loss-of-function; over-annotation.
• Module (cardiac_specification_network, tbox_tf annoton): GO:0000981 in heart development —
  consistent with this review.