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TRIM32 regulates mitochondrial mediated ROS levels and sensitizes the oxidative stress induced cell death
Paresh Prajapati1, Dhruv Gohel2, Anjali Shinde2
1Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390 002, Gujarat, India; Spinal Cord and Brain Injury Research Center, Department of Pathology and Laboratory Medicine, University of Kentucky, 800 S. Limestone, Lexington, KY 40536, USA; Neuroscience, University of Kentucky, Lexington, KY 40536, USA.
Abstract:
Emerging evidence suggests that ubiquitin mediated post translational modification is a critical regulatory process involved in diverse cellular pathways including cell death. During ubiquitination, E3 ligases recognize target proteins and determine the topology of ubiquitin chains. Recruitment of E3 ligases to targets proteins under stress conditions including oxidative stress and their implication in cell death have not been systemically explored. In the present study, we characterized the role of TRIM32 as an E3 ligase in regulation of oxidative stress induced cell death. TRIM32 is ubiquitously expressed in cell lines of different origin and form cytoplasmic speckle like structures that transiently interact with mitochondria under oxidative stress conditions. The ectopic expression of TRIM32 sensitizes cell death induced by oxidative stress whereas TRIM32 knockdown shows a protective effect. The turnover of TRIM32 is enhanced during oxidative stress and its expression induces ROS generation, loss of mitochondrial transmembrane potential and decrease in complex-I activity. The pro-apoptotic effect was rescued by pan-caspase inhibitor or antioxidant treatment. E3 ligase activity of TRIM32 is essential for oxidative stress induced apoptotic cell death. Furthermore, TRIM32 decreases X-linked inhibitor of apoptosis (XIAP) level and overexpression of XIAP rescued cells from TRIM32 mediated oxidative stress and cell death. Overall, the results of this study provide the first evidence supporting the role of TRIM32 in regulating oxidative stress induced cell death, which has implications in numerous pathological conditions including cancer and neurodegeneration.
Insights
TRIM32 acts as an E3 ligase, promoting oxidative stress-induced cell death by impacting mitochondria and reducing XIAP levels. Its E3 ligase activity is crucial for apoptosis, with implications for cancer and neurodegeneration.
Area of Science:
- Cellular Biology
- Biochemistry
- Molecular Biology
Background:
- Ubiquitin-mediated post-translational modification regulates cellular pathways, including cell death.
- E3 ligases determine ubiquitin chain topology and target protein recognition.
- The role of E3 ligases in oxidative stress-induced cell death is not fully understood.
Purpose of the Study:
- To investigate the role of TRIM32 as an E3 ligase in regulating oxidative stress-induced cell death.
- To explore TRIM32's cellular localization and interactions under oxidative stress.
- To elucidate the molecular mechanisms by which TRIM32 influences cell death pathways.
Main Methods:
- Characterization of TRIM32 expression and localization in various cell lines.
- Assessment of TRIM32's effect on oxidative stress-induced cell death.
- Analysis of mitochondrial function, reactive oxygen species (ROS) generation, and complex-I activity.
- Evaluation of TRIM32's impact on X-linked inhibitor of apoptosis (XIAP) levels.
- Utilizing pan-caspase inhibitors and antioxidants to rescue cell death.
Main Results:
- TRIM32 is ubiquitously expressed and localizes to cytoplasmic speckles, interacting with mitochondria under oxidative stress.
- Ectopic TRIM32 expression sensitizes cells to oxidative stress-induced death, while knockdown confers protection.
- TRIM32 enhances ROS generation, mitochondrial dysfunction, and complex-I inhibition.
- TRIM32's E3 ligase activity is essential for promoting apoptosis.
- TRIM32 downregulates XIAP, and XIAP overexpression rescues cells from TRIM32-mediated death.
Conclusions:
- TRIM32 functions as an E3 ligase that promotes oxidative stress-induced cell death.
- TRIM32 mediates apoptosis through mitochondrial dysfunction and XIAP downregulation.
- These findings highlight TRIM32's critical role in cellular responses to oxidative stress with implications for diseases like cancer and neurodegeneration.
