Role of cytochrome c in apoptosis

Increased sensitivity to tumor necrosis factor alpha is associated with respiratory defects but not with lack of cytochrome c release

Uma D. Vempati, Francisca Diaz, Antonio Barrientos, Sonoko Narisawa, Abdul M. Mian, José Luis Millán, Lawrence H. Boise, Carlos T Moraes

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Although the role of cytochrome c in apoptosis is well established, details of its participation in signaling pathways in vivo are not completely understood. The knockout for the somatic isoform of cytochrome c caused embryonic lethality in mice, but derived embryonic fibroblasts were shown to be resistant to apoptosis induced by agents known to trigger the intrinsic apoptotic pathway. In contrast, these cells were reported to be hypersensitive to tumor necrosis factor alpha (TNF-α)-induced apoptosis, which signals through the extrinsic pathway. Surprisingly, we found that this cell line (CRL 2613) respired at close to normal levels because of an aberrant activation of a testis isoform of cytochrome c, which, albeit expressed at low levels, was able to replace the somatic isoform for respiration and apoptosis. To produce a bona fide cytochrome c knockout, we developed a mouse knockout for both the testis and somatic isoforms of cytochrome c. The mouse was made viable by the introduction of a ubiquitously expressed cytochrome c transgene flanked by loxP sites. Lung fibroblasts in which the transgene was deleted showed no cytochrome c expression, no respiration, and resistance to agents that activate the intrinsic and to a lesser but significant extent also the extrinsic pathways. Comparison of these cells with lines with a defective oxidative phosphorylation system showed that cells with defective respiration have increased sensitivity to TN-α-induced apoptosis, but this process was still amplified by cytochrome c. These studies underscore the importance of oxidative phosphorylation and apoptosome function to both the intrinsic and extrinsic apoptotic pathways.

Original languageEnglish
Pages (from-to)1771-1783
Number of pages13
JournalMolecular and Cellular Biology
Volume27
Issue number5
DOIs
StatePublished - Mar 1 2007

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Cytochromes c
Tumor Necrosis Factor-alpha
Apoptosis
Protein Isoforms
Respiration
Oxidative Phosphorylation
Transgenes
Testis
Apoptosomes
Fibroblasts
Cell Line
Knockout Mice
Lung

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

Role of cytochrome c in apoptosis : Increased sensitivity to tumor necrosis factor alpha is associated with respiratory defects but not with lack of cytochrome c release. / Vempati, Uma D.; Diaz, Francisca; Barrientos, Antonio; Narisawa, Sonoko; Mian, Abdul M.; Millán, José Luis; Boise, Lawrence H.; Moraes, Carlos T.

In: Molecular and Cellular Biology, Vol. 27, No. 5, 01.03.2007, p. 1771-1783.

Research output: Contribution to journalArticle

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