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Updated: Jul 30, 2025
Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue
Published on: March 23, 2015
Analysis of Radiation Toxicity in Mammalian Cells Stably Transduced with Mitochondrial Stat3
Alisa Zanin1, Giacomo Meneghetti1, Luca Menilli1
1Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy.
Abstract:
A coordinated action between nuclear and mitochondrial activities is essential for a proper cellular response to genotoxic stress. Several nuclear transcription factors, including STAT3, translocate to mitochondria to exert mitochondrial function regulation; however, the role of mitochondrial STAT3 (mitoSTAT3) under stressed conditions is still poorly understood. In this study, we examined whether the stable expression of mitoSTAT3 wild-type or mutated at the conserved serine residue (Ser727), which is involved in the mitochondrial function of STAT3, can affect the DNA damage response to UVC radiation. To address this issue, we generated mammalian cells (NIH-3T3 and HCT-116 cells) stably transduced to express the mitochondrial-targeted Stat3 gene in its wild-type or Ser727 mutated forms. Our results show that cell proliferation is enhanced in mitoStat3-transduced cells under both non-stressed and stressed conditions. Once irradiated with UVC, cells expressing wild-type mitoSTAT3 showed the highest cell survival, which was associated with a significant decrease in cell death. Low levels of oxidative stress were detected in UVC-irradiated NIH-3T3 cells expressing mitoSTAT3 wild-type or serine-related dominant active form (Ser727D), confirming a role of mitochondrial STAT3 in minimizing oxidant cellular stress that provides an advantage for cell survival.
Insights
Mitochondrial STAT3 (mitoSTAT3) enhances cell proliferation and survival under genotoxic stress. Stable expression of mitoSTAT3 improves cell survival after UVC radiation by reducing oxidative stress.
Area of Science:
- Cellular Biology
- Molecular Biology
- Genetics
Background:
- Nuclear and mitochondrial activities coordinate cellular responses to genotoxic stress.
- Nuclear transcription factors, such as STAT3, can translocate to mitochondria to regulate mitochondrial function.
- The specific role of mitochondrial STAT3 (mitoSTAT3) during cellular stress remains largely unelucidated.
Purpose of the Study:
- To investigate the impact of stable mitoSTAT3 expression on the DNA damage response to UVC radiation.
- To determine if wild-type or mutated mitoSTAT3 (at Ser727) influences cellular responses to UVC-induced genotoxic stress.
Main Methods:
- Generation of mammalian cell lines (NIH-3T3, HCT-116) stably expressing mitochondrial-targeted STAT3 (mitoSTAT3) in wild-type or Ser727 mutant forms.
- Assessment of cell proliferation, cell survival, and oxidative stress levels following UVC irradiation in engineered cell lines.
Main Results:
- Stable expression of mitoSTAT3 enhanced cell proliferation under both normal and stressed conditions.
- Cells expressing wild-type mitoSTAT3 exhibited significantly increased cell survival and reduced cell death after UVC irradiation.
- UVC-irradiated cells with mitoSTAT3 (wild-type or Ser727D) showed diminished oxidative stress, indicating a protective role.
Conclusions:
- Mitochondrial STAT3 plays a crucial role in enhancing cellular resilience to genotoxic stress, particularly UVC radiation.
- mitoSTAT3 contributes to improved cell survival by mitigating oxidative stress within mitochondria.
- Targeting mitochondrial STAT3 may represent a therapeutic strategy for improving cellular responses to DNA damage.
