Lack of induction of tissue transglutaminase but activation of the preexisting enzyme in c-Myc-induced apoptosis of CHO cells

Zoltán Balajthy, Noémi Kedei, László Nagy, Peter J.A. Davies, László Fésüs

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Abstract

The intracellular activity and expression of tissue transglutaminase, which crosslinks proteins through ε(γ-glutamyl)lysine isodipeptide bond, was investigated in CHO cells and those stably transfected with either inducible c-Myc (which leads to apoptosis) or with c-myc and the apoptosis inhibitor Bcl-2. Protein-bound cross-link content was significantly higher when apoptosis was induced by c-Myc while the concomitant presence of Bcl-2 markedly reduced both apoptosis and enzymatic protein cross-linking. The expression of tissue transglutaminase did not change following the initiation of apoptosis by c-Myc or when it was blocked by Bcl-2. Studying transiently co-transfected elements of the mouse tissue transglutaminase promoter linked to a reporter enzyme revealed their overall repression in cells expressing c-Myc. This repression was partially suspended in cells also carrying Bcl-2. Our data suggest that tissue transglutaminase is not induced when c-Myc initiates apoptosis but the pre-existing endogenous enzyme is activated.

Original languageEnglish
Pages (from-to)280-284
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume236
Issue number2
DOIs
Publication statusPublished - Jul 18 1997

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ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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