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Phosphorylation of the transcription factor YY1 by CK2α prevents cleavage by caspase 7 during apoptosis

Sarah Riman1, Raed Rizkallah, Ari Kassardjian

  • 1Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, USA.

Molecular and Cellular Biology
|December 21, 2011
PubMed

Insights

This study reveals how casein kinase II (CK2α) phosphorylates Yin Yang 1 (YY1) at serine 118, a key step that regulates YY1 cleavage during apoptosis and programmed cell death.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Biochemistry

Background:

  • Yin Yang 1 (YY1) is a transcription factor involved in cell growth, differentiation, and apoptosis.
  • YY1 is known to be cleaved by caspases during apoptosis, but regulatory mechanisms are unclear.
  • Casein kinase II (CK2α) is a serine/threonine kinase with diverse cellular functions.

Purpose of the Study:

  • To investigate the role of CK2α in the regulation of YY1 phosphorylation and cleavage.
  • To identify the specific site of YY1 phosphorylation by CK2α.
  • To elucidate the functional consequences of YY1 phosphorylation on its cleavage during apoptosis.

Main Methods:

  • In vitro and in vivo phosphorylation assays.
  • Site-directed mutagenesis (serine-to-alanine substitution at S118).
  • Small interfering RNA (siRNA) knockdown of CK2α.
  • Analysis of YY1 cleavage under apoptotic conditions.

Main Results:

  • CK2α phosphorylates YY1 at serine 118 (S118) in vitro and in vivo.
  • S118 is located near a caspase 7 cleavage site.
  • CK2α inhibition or knockdown enhances YY1 cleavage during apoptosis.
  • Increased CK2α activity elevates S118 phosphorylation.
  • Mutation of S118 to alanine increases YY1 cleavage during apoptosis.

Conclusions:

  • Phosphorylation of YY1 at S118 by CK2α is a critical regulatory mechanism controlling YY1 cleavage during programmed cell death.
  • This finding establishes a direct link between CK2α activity and YY1 stability in apoptosis.
  • Understanding this pathway may offer insights into therapeutic strategies targeting YY1 in cancer and other diseases.

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