Oocyte mitochondria link maternal environment to offspring phenotype

Area of Science:

• Developmental Biology
• Genetics
• Metabolism

Background:

• Oocytes undergo mitochondrial proteome remodeling during maturation, involving changes in electron transport chain (ETC) subunits, regulated by maternal insulin signaling.
• The adaptive significance of oocyte mitochondrial remodeling remains unclear, with hypotheses suggesting a role in protecting against reactive oxygen species (ROS).
• Intergenerational stress adaptation, like enhanced offspring survival after maternal osmotic stress exposure in *C. elegans*, is also mediated by oocyte insulin signaling.

Approach:

• Utilized proteomics and genetic manipulations in *C. elegans* to investigate the link between oocyte mitochondrial composition and offspring stress adaptation.
• Examined the effects of maternally expressed mutant alleles of ETC genes (*nduf-7*, *isp-1*) on offspring's response to osmotic stress.
• Conducted chemical mutagenesis screens to identify downstream effectors of maternal ETC composition in offspring.

Key Points:

• Maternal insulin signaling regulates offspring stress adaptation through oocyte ETC composition.
• Mutations in maternal *nduf-7* or *isp-1* genes altered offspring osmotic stress response independently of offspring genotype.
• Expression of wild-type *isp-1* in oocytes restored normal offspring stress response, highlighting the importance of maternal genetic contribution.

Conclusions:

• Oocyte ETC composition is crucial for linking maternal environmental exposures to adaptive metabolic changes in offspring.
• Maternal ETC composition influences offspring stress response by modulating AMP kinase activity, thereby regulating ATP and glycerol metabolism.
• Oocyte mitochondrial remodeling may be an evolutionarily conserved mechanism to optimize offspring metabolism for the maternal environment.