Tom70 mediates Sendai virus-induced apoptosis on mitochondria

Area of Science:

• Immunology
• Cell Biology
• Virology

Background:

• Virus infection elicits innate immune responses, including cytokine production and apoptosis.
• Apoptosis is crucial for eliminating infected cells and preventing viral dissemination.
• The precise mechanism of Interferon Regulatory Factor 3 (IRF3)-mediated apoptosis following Sendai virus (SeV) infection requires further elucidation.

Purpose of the Study:

• To characterize the molecular mechanism underlying SeV-induced apoptosis mediated by IRF3.
• To identify the protein complex involved in recruiting IRF3 to mitochondria during viral infection.
• To investigate the roles of specific kinases, IKK-i and TBK1, in this apoptotic pathway.

Main Methods:

• Co-immunoprecipitation assays to detect protein-protein interactions.
• Subcellular fractionation to determine protein localization.
• Western blotting to analyze protein expression and cytochrome c release.
• Virus infection models using Sendai virus (SeV).

Main Results:

• A dynamic protein complex, Tom70/Hsp90/IRF3/Bax, was identified as central to SeV-induced apoptosis.
• Interferon Regulatory Factor 3 (IRF3) interacts with the proapoptotic protein Bax upon SeV infection.
• Mitochondrial import receptor Tom70, via Heat Shock Protein 90 (Hsp90), recruits IRF3 to the mitochondrial outer membrane.
• This recruitment leads to Bax translocation, cytochrome c release, and subsequent apoptosis.
• The IKK-i kinase is essential for this apoptotic process, while TBK1 is dispensable.

Conclusions:

• A novel mechanism for SeV-induced apoptosis involving the Tom70/Hsp90/IRF3/Bax complex is characterized.
• This pathway highlights the critical role of mitochondrial-mediated apoptosis in antiviral defense.
• The findings provide new insights into the regulation of programmed cell death during viral infections.