Female-biased embryonic death from genomic instability-induced inflammation

Genomic instability (GIN) can trigger cellular responses including checkpoint activation, senescence, and inflammation (1,2). Though extensively studied in cell culture and cancer paradigms, little is known about the impact of GIN during embryonic development, a period of rapid cellular proliferation. We report that GIN-causing mutations in the MCM2–7 DNA replicative helicase (3,4) render female mouse embryos to be dramatically more susceptible than males to embryonic lethality. This bias was not attributable to X-inactivation defects, differential replication licensing, or X vs Y chromosome size, but rather “maleness,” since XX embryos could be rescued by transgene-mediated sex reversal or testosterone (T) administration. The ability of exogenous or endogenous T to protect embryos was related to its anti-inflammatory properties (5). The NSAID ibuprofen rescued female embryos containing mutations not only in MCM genes but also Fancm, which like MCM mutants have elevated GIN (micronuclei) from compromised replication fork repair (6). Additionally, deficiency for the anti-inflammatory IL10 receptor was synthetically lethal with the Mcm4(Chaos3) helicase mutant. Our experiments indicate that DNA replication-associated DNA damage during development induces inflammation that is preferentially lethal to female embryos, whereas male embryos are protected by high levels of intrinsic T.