Critical requirement of SOS1 RAS-GEF function for mitochondrial dynamics, metabolism, and redox homeostasis

Area of Science:

• Cell Biology
• Mitochondrial Biology
• Biochemistry

Background:

• The SOS1 protein plays a role in cellular signaling pathways.
• Mitochondrial dysfunction is implicated in various cellular defects.
• Reactive oxygen species (ROS) are key mediators of cellular stress.

Purpose of the Study:

• To investigate the role of SOS1 in cellular oxidative stress and mitochondrial function.
• To elucidate the mechanistic link between SOS1, RAS signaling, and mitochondrial health.

Main Methods:

• Analysis of SOS1-deficient mouse embryonic fibroblasts (MEFs).
• Assessment of intracellular ROS levels and mitochondrial parameters (shape, mass, dynamics).
• Measurement of mitochondrial respiration, glycolysis, and ATP production.
• Investigation of RASless cells to confirm SOS1-GEF activity role.

Main Results:

• SOS1 ablation in MEFs led to increased intracellular ROS, primarily originating from mitochondria.
• Absence of SOS1 caused significant alterations in mitochondrial morphology, dynamics, and function, including reduced electron transport and dysfunctional mitochondria.
• SOS1 deficiency impaired respiratory complexes, mitochondrial supercomplex assembly, and overall cellular energy production (respiration, glycolysis, ATP).
• RASless cells exhibited similar metabolic defects, linking mitochondrial issues to SOS1's GEF activity on RAS.

Conclusions:

• SOS1 is crucial for maintaining mitochondrial integrity and function.
• SOS1-mediated RAS activation is essential for controlling cellular oxidative stress and proper mitochondrial dynamics.
• This study establishes a direct mechanistic link between SOS1 and mitochondrial health.