Random mtDNA mutations modulate proliferation capacity in mouse embryonic fibroblasts.

Area of Science:

• Mitochondrial biology
• Cellular senescence
• Aging research

Background:

• Accumulation of mitochondrial DNA (mtDNA) mutations contributes to organismal aging and tissue dysfunction.
• Senescent cells with altered metabolism may actively disrupt tissue function, a potential link to premature aging.
• Mitochondrial dysfunction is implicated in aging, but its role in premature aging mechanisms requires further elucidation.

Purpose of the Study:

• To investigate the molecular mechanisms underlying premature aging in mtDNA mutator mice.
• To explore the proliferation capacity and metabolic adaptations of mtDNA mutator cells under varying oxygen conditions.
• To determine the role of aerobic glycolysis in the spontaneous immortalization of mtDNA mutator cells.

Main Methods:

• In vitro proliferation assays of mtDNA mutator mouse embryonic fibroblasts (MEFs) and wild-type MEFs.
• Culture of cells under physiological (3% O2) and high oxidative stress (20% O2) conditions.
• Analysis of metabolic function, specifically aerobic glycolysis, in mtDNA mutator cells.

Main Results:

• mtDNA mutator cells showed reduced proliferation at physiological oxygen levels compared to wild-type cells.
• Under high oxidative stress (20% O2), mtDNA mutator MEFs underwent spontaneous immortalization and continuous proliferation.
• Wild-type MEFs, conversely, exhibited senescence under high oxidative stress.
• Increased aerobic glycolysis was observed in mtDNA mutator mice, correlating with spontaneous immortalization.

Conclusions:

• Aerobic glycolysis in mtDNA mutator cells promotes proliferation and metabolite turnover, potentially leading to immortalization under oxidative stress.
• This process involves an energy crisis due to reduced ATP production, possibly causing replication/repair errors and mutations in tumor suppressor genes.
• mtDNA mutations and subsequent metabolic shifts, particularly aerobic glycolysis, offer a novel mechanistic link to premature aging and spontaneous immortalization.