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Subunit S5a of the 26S proteasome is regulated by antiapoptotic signals

Yael Gus1, Rotem Karni, Alexander Levitzki

  • 1The Hebrew University, Department of Biological Chemistry, Silberman Institute, Givat Ram, Jerusalem 91904, Israel.

The FEBS Journal
|April 27, 2007
PubMed

Insights

The 26S proteasome subunit S5a acts as an antiapoptotic gene regulated by c-Src. Upregulation of S5a by antiapoptotic signals promotes cell survival.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • The oncoprotein c-Src plays a role in cell survival and apoptosis.
  • Identifying novel antiapoptotic genes regulated by c-Src is crucial for understanding cancer progression.

Purpose of the Study:

  • To identify novel antiapoptotic genes regulated by c-Src.
  • To investigate the role of the 26S proteasome subunit S5a in apoptosis.

Main Methods:

  • Functional genetic screen to identify antiapoptotic genes.
  • Quantitative real-time PCR and Western blotting to assess S5a mRNA and protein levels.
  • Reporter assays and electrophoretic mobility shift assays (EMSA) to analyze S5a promoter activity and transcription factor binding.

Main Results:

  • The 26S proteasome subunit S5a was identified as a novel antiapoptotic gene.
  • S5a expression is downregulated by c-Src inhibition and upregulated in cells with high c-Src activity.
  • S5a transcription is regulated by the Tcf/Lef-1 transcription factor and influenced by signaling pathways including PI3K.

Conclusions:

  • S5a is transcriptionally regulated during apoptosis.
  • Upregulation of S5a by antiapoptotic signals contributes to cell survival.
  • S5a represents a potential therapeutic target in cancers driven by c-Src.

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