Characterization of cell clones stably transfected with short form caspase-9: Apoptotic resistance and Bcl-XL expression

Xiaolan Yi, Jinzhao Wang, Dai Wu Seol, Zheng Dong

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Caspases play important roles in the initiation and progression of apoptosis. In experimental models of ATP depletion, we have demonstrated the activation of caspase-9, -8, and -3, which is followed by the development of apoptotic morphology. To determine the specific contribution of caspase-9 to ATP depletion-induced apoptosis, we transfected renal epithelial cells with its endogenous dominant-negative inhibitor caspase-9S. Two cell clones with stable transfection were obtained. These clones expressed caspase-9S, and the cytosol isolated from these cells was resistant to cytochrome c-induced caspase activation in vitro. The clones were then examined for ATP depletion-induced apoptosis. Compared with the wild-type cells, the caspase-9S clones were markedly resistant to apoptosis in this model. Caspase activation was also inhibited. Surprisingly, these clones also showed significantly less cytochrome c release during ATP-depletion. Moreover, Bax translocation to mitochondria was inhibited, suggesting that these clones were resistant to apoptosis not only at the cytosolic caspase activation level but also at the upstream mitochondrial level. To gain insights into the mitochondrial resistance, we analyzed the expression of Bcl-2 family proteins. While the expression of Bax, Bak, and Bcl-2 was comparable to the wild-type cells, the selected clones showed specific up-regulation of Bcl-XL, an anti-apoptotic protein. We conclude that the selected clones were resistant to apoptosis at two levels. In the cytosol, they expressed dominant negative caspase-9, and at the mitochondria they up-regulated Bcl-XL.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalMolecular and Cellular Biochemistry
Volume282
Issue number1-2
DOIs
StatePublished - Jan 1 2006

Keywords

  • ATP depletion
  • Apoptosis
  • Bax
  • Bcl-XL
  • Caspase
  • Cytochrome c

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

Fingerprint Dive into the research topics of 'Characterization of cell clones stably transfected with short form caspase-9: Apoptotic resistance and Bcl-XL expression'. Together they form a unique fingerprint.

  • Cite this