MSTO1 modulates RAD51 activity to safeguard mitochondrial DNA integrity and control immune responses

Area of Science:

• Mitochondrial biology
• Molecular genetics
• Immunology

Background:

• Pathogenic MSTO1 mutations are linked to cerebellar ataxia and congenital myopathy.
• The precise molecular mechanisms underlying MSTO1-related diseases are not fully understood.

Purpose of the Study:

• To elucidate the molecular function of MSTO1 in maintaining mitochondrial genome integrity.
• To investigate the role of MSTO1 in regulating RAD51 activity within mitochondria.
• To explore the connection between MSTO1 deficiency, mitochondrial dysfunction, and inflammatory responses.

Main Methods:

• Investigated MSTO1's interaction with RAD51 using biochemical assays.
• Assessed mitochondrial DNA (mtDNA) integrity, replication, and stability in MSTO1-deficient models.
• Analyzed mitochondrial membrane potential, oxidative stress susceptibility, and mtDNA leakage.
• Examined the activation of the cGAS-STING pathway and inflammatory markers.
• Performed clinical bioinformatics analysis correlating MSTO1 expression with immune activation in cancers.

Main Results:

• MSTO1 directly interacts with RAD51, regulating its mitochondrial localization and activity.
• MSTO1 deficiency leads to increased RAD51 binding to mtDNA, disrupting replication and causing damage.
• Loss of MSTO1 impairs mitochondrial function, reduces mtDNA content, and increases oxidative stress.
• MSTO1 deficiency causes mtDNA leakage, activating the cGAS-STING pathway and promoting inflammation.
• Low MSTO1 expression correlates with immune activation in human cancers.

Conclusions:

• MSTO1 is a critical regulator of mitochondrial genome stability through its interaction with RAD51.
• MSTO1 dysfunction contributes to disease pathogenesis and triggers inflammatory responses.
• MSTO1 plays a role in modulating anti-tumor immunity, suggesting therapeutic potential in cancer.