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Updated: Jun 21, 2026

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Co-activator activator (CoAA) prevents the transcriptional activity of Runt domain transcription factors

Xiaodong Li1, Luke H Hoeppner, Eric D Jensen

  • 1Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA.

Journal of Cellular Biochemistry
|July 9, 2009
PubMed

Insights

Co-activator activator (CoAA) inhibits Runx factors, crucial proteins in development and cancer. Suppressing CoAA reduced osteosarcoma cell viability, suggesting its role in cell proliferation and survival.

Area of Science:

  • Molecular Biology
  • Developmental Biology
  • Cancer Biology

Background:

  • Runx proteins are essential transcription factors involved in development and aberrant in human cancers.
  • Co-activator activator (CoAA) is a nuclear protein that regulates gene expression and is overexpressed in tumors.

Purpose of the Study:

  • To investigate the interaction between CoAA and Runx factors.
  • To determine the functional consequences of CoAA binding to Runx factors.
  • To explore the role of CoAA in osteosarcoma.

Main Methods:

  • Co-immunoprecipitation to identify CoAA as a Runx2 binding protein.
  • Reporter gene assays to assess CoAA's effect on Runx-mediated gene activation and repression.
  • Electrophoretic mobility shift assays (EMSA) to study Runx2-DNA interactions.
  • RNA interference (RNAi) to suppress CoAA expression in osteosarcoma cells.

Main Results:

  • CoAA directly binds to Runx1 and Runx2, with the carboxy-terminus of CoAA being essential for this interaction.
  • CoAA represses Runx factor-dependent gene activation and blocks Runx2-mediated repression of the Axin2 promoter.
  • CoAA inhibits Runx2 binding to DNA.
  • CoAA is highly expressed in osteosarcoma cells, and its suppression reduces cell viability.

Conclusions:

  • CoAA acts as an inhibitor of Runx factors, negatively regulating their transcriptional activity.
  • CoAA plays a role in the proliferation and/or survival of osteoblast lineage cells, particularly in the context of osteosarcoma.
  • CoAA represents a potential therapeutic target in osteosarcoma.

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