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Metaxin is required for tumor necrosis factor-induced cell death
1Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Abstract:
We used retrovirus insertion-mediated random mutagenesis and tumor necrosis factor (TNF) selection to generate TNF-resistant lines from L929 cells. The metaxin gene, which encodes a protein located on the outer membrane of mitochondria, was identified to be the gene disrupted in one of the resistant lines. The requirement of metaxin in TNF-induced cell death of L929 was confirmed by the restoration of TNF sensitivity after ectopic reconstitution of metaxin expression. Analysis of the cell death induced by other stimuli revealed that metaxin deficiency-mediated death resistance was selective to certain stimuli. Studies using deletion mutants of metaxin showed that mitochondrial association of metaxin is required for the function of metaxin. Over-expression of truncated metaxin lacking the mitochondria anchoring sequence mimicked metaxin deficiency in wild-type cells. Interfering with metaxin prevented TNF-induced necrotic cell death in L929 cells and apoptosis in MCF-7 cells. Our work has thus defined a novel component in the death pathway used by TNF and some other death stimuli.
Insights
Metaxin, a mitochondrial protein, is crucial for tumor necrosis factor (TNF)-induced cell death. Disrupting metaxin confers resistance to TNF and other death stimuli, revealing its novel role in cell death pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Tumor necrosis factor (TNF) is a key mediator of cellular apoptosis and necrosis.
- Understanding the molecular mechanisms of TNF-induced cell death is crucial for developing therapeutic strategies.
Purpose of the Study:
- To identify novel genes involved in TNF-induced cell death.
- To elucidate the role of metaxin in TNF-mediated cell death pathways.
Main Methods:
- Retrovirus insertion-mediated random mutagenesis and TNF selection in L929 cells.
- Gene identification, ectopic expression, and analysis of cell death induction by various stimuli.
- Studies using deletion mutants and over-expression of metaxin.
Main Results:
- Identified metaxin, a mitochondrial outer membrane protein, as essential for TNF-induced cell death.
- Metaxin deficiency conferred resistance to TNF and other death stimuli selectively.
- Mitochondrial localization of metaxin is required for its function in cell death pathways.
Conclusions:
- Metaxin is a novel and essential component of TNF-induced cell death.
- Metaxin plays a critical role in mediating both necrosis and apoptosis induced by specific death stimuli.
- Targeting metaxin could offer new therapeutic avenues for diseases involving aberrant cell death.