Mitochondrial mechanisms of maternal age effects on offspring health and lifespan

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PROJECT SUMMARY Advanced maternal age at the time of reproduction decreases offspring lifespan and health in a range of species, including humans. The mechanisms controlling maternal age effects on offspring are unknown, however. In our parent R01 project, we hypothesize that mitochondrial dysfunction in advanced maternal age causes accumulation of dysfunctional mitochondria in offspring through compensatory biogenesis and decreased autophagy during development. This disrupts offspring mitochondrial function and mitochondrial-nuclear communication, leading to accelerated offspring aging. The objectives of the parent project are to understand the mitochondrial mechanisms by which maternal age determines offspring aging. In the parent R01, we proposed to identify the maternal mitochondrial mechanisms that trigger maternal age effects; identify the developmental mechanisms causing accumulation of mtDNA and damaged mitochondria in old-mother offspring; and identify the offspring mitochondrial mechanisms involved in negative maternal age effects and determine if these mechanisms are ROS- dependent. When the parent project proposal was submitted, a method for CRISPR gene editing in Brachionus rotifers was still in development. We have now successfully created a protocol for high-efficiency CRISPR-mediated mutagenesis in Brachionus manjavacas. As proof-of-principle for this new method, we created knockout mutations of VASA and MLH3, and a knock-in mutation of a stop cassette in MLH3. Mutations were inherited over many generations, demonstrating our ability to establish stable mutant lines. The availability of heritable CRISPR induced mutation in Brachionus rotifers now makes it possible to test mitochondrial mechanisms of maternal age effects more directly. The goal of this small-scale, short-term Administrative Supplement project is to establish 5-7 stable knockout mutants and knock-in fluorescent reporter strains for mitochondria-related genes in Brachionus manjavacas. Establishing mutants for genes related to mitochondrial function and dynamics will allow us to test the role of specific mitochondrial dynamics and metabolic pathways in maternal age effects on lifespan and healthspan in the parent R01 and future studies.