Zebrafish polg2 knock-out recapitulates human POLG-disorders; implications for drug treatment

Area of Science:

• Genetics
• Mitochondrial Biology
• Developmental Biology

Background:

• Mutations in POLG or POLG2 cause POLG-related diseases, leading to mitochondrial DNA depletion and multi-organ defects.
• POLG2 models are scarce, hindering research into these severe inherited mitochondrial disorders.

Purpose of the Study:

• To generate and characterize a zebrafish model for POLG2-related disorders.
• To investigate the pathogenic mechanisms and explore therapeutic strategies for POLG2 mutations.

Main Methods:

• CRISPR/Cas9 gene editing was used to create a stable zebrafish polg2 mutant line (polg2^ia304).
• Phenotypic analyses included developmental assessments, viability studies, mitochondrial function assays, histology, and locomotor activity tests.
• The efficacy of Clofilium tosylate treatment was evaluated in the mutant zebrafish.

Main Results:

• Zebrafish polg2 mutants exhibited slower development, reduced viability, and premature death.
• Mutants displayed mitochondrial DNA depletion, altered mitochondrial networks, reduced respiration, and skeletal muscle disorganization.
• Clofilium tosylate partially rescued mitochondrial DNA depletion in polg2 mutant zebrafish.

Conclusions:

• Zebrafish is an effective model for studying POLG2-related human mitochondrial disorders.
• This model provides a platform for screening drugs targeting POLG-directed therapies for POLG2-associated conditions.