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Human regulatory factor X 4 (RFX4) is a testis-specific dimeric DNA-binding protein that cooperates with other human

Keiko Morotomi-Yano1, Ken-ichi Yano, Hiroko Saito

  • 1Department of Molecular Diagnosis, Cancer Institute, Japanese Foundation for Cancer Research, 1-37-1 Kami-ikebukuro, Toshima-ku, Tokyo 170-8455, Japan.

The Journal of Biological Chemistry
|October 30, 2001
PubMed

Insights

Regulatory Factor X 4 (RFX4) is a novel transcription factor identified in human testis. Unlike other RFX family members, RFX4 lacks transcriptional activation domains and may function via interactions with other RFX proteins.

Area of Science:

  • Molecular biology
  • Genetics
  • Cancer research

Background:

  • Regulatory Factor X (RFX) proteins are conserved transcription factors with a winged helix DNA-binding domain.
  • Previous studies identified a partial human RFX4 cDNA in breast cancer, but its full structure and function were unknown.

Purpose of the Study:

  • To clone and characterize the full-length human RFX4.
  • To investigate RFX4's expression, DNA-binding activity, protein interactions, and transcriptional regulatory function.

Main Methods:

  • Molecular cloning and sequencing of human RFX4.
  • In vitro synthesis and DNA-binding assays of RFX4 protein.
  • Immunoprecipitation to analyze protein-protein interactions.
  • Chimeric protein analysis to identify functional domains.

Main Results:

  • Human RFX4 possesses conserved RFX domains and shows structural similarity to RFX1-3.
  • RFX4 expression is specifically detected in the testis.
  • RFX4 binds to canonical RFX binding sites in a sequence-dependent manner.
  • RFX4 physically interacts with RFX2, RFX3, and itself, but not RFX1.
  • RFX4 lacks transcriptional activation domains and its C-terminal region may act as a repression domain.

Conclusions:

  • RFX4 is the first identified mammalian RFX member lacking transcriptional activation capacity.
  • RFX4 likely functions in transcriptional regulation through selective interactions with other RFX family members, particularly in the testis.

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