Small molecules restore mutant mitochondrial DNA polymerase activity

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Mammalian mitochondrial DNA (mtDNA) replication relies on DNA polymerase gamma (POLγ), a complex with catalytic POLγA and accessory POLγB subunits.
• Over 300 mutations in the POLG gene cause severe POLG disorders, leading to high morbidity and mortality with no current treatments.

Purpose of the Study:

• To discover and characterize a novel small molecule capable of activating mtDNA synthesis.
• To investigate the potential of this molecule to restore function to mutant POLγ variants and treat POLG-related diseases.

Main Methods:

• Discovery and characterization of PZL-A, a small-molecule activator of mtDNA synthesis.
• In vitro assays to assess PZL-A's effect on mutant POLγ activity.
• Cellular studies using patient-derived cells to evaluate PZL-A's impact on mtDNA synthesis and cellular respiration.

Main Results:

• PZL-A binds to an allosteric site on POLγ, unaffected by most disease-causing mutations.
• The compound restored wild-type-like activity to mutant POLγ in vitro.
• PZL-A activated mtDNA synthesis in cells from patients with lethal POLG disease, enhancing oxidative phosphorylation and cellular respiration.

Conclusions:

• Small molecules can restore function to mutant DNA polymerases.
• PZL-A represents a first-in-class therapeutic strategy for POLG disorders.
• This approach holds promise for treating a range of severe conditions linked to mtDNA depletion.