Somatic regulation of embryonic germline dynamics by isoprenoids

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PROJECT SUMMARY/ABSTRACT The development and protection of the germline is critical to the fertility and the health of the next generation. My long-term objective is to elucidate the mechanisms, regulation and coordination of embryonic germline processes as an independent investigator. Emerging evidence suggests that the secreted isoprene lipids, retinoic acids and juvenile hormones, have more than one role in the germline lifecycle in vertebrate and invertebrate animals, respectively. Juvenile hormone signaling has been implicated in several aspects adult gametogenesis while retinoic acid has a prominent role in the regulation of meiotic onset timing. However, no shared function for these two isoprenoids have been found to-date despite a high degree of structural similarity, cross-activation capacity, and shared expression patterns during embryonic germline development. Based on a wealth of preliminary studies, the central hypothesis guiding this proposal is that juvenile hormone impacts embryonic germ cell dynamics through a non-classical mechanism and that two functions of retinoic acid and juvenile function in embryonic germ processes are conserved between insects and mammals. Three aims will be completed to test this hypothesis. First, the impact of juvenile hormone will be determined with two approaches. Spatiotemporal juvenile hormone titers will be measured spectrometry-based metabolomics to elucidate the source of juvenile hormone. Then, the impact of juvenile hormone on germ cell dynamics will be determined using live imaging analysis in Drosophila melanogaster embryos. Second, the non-classical, transcription-independent, mechanism of juvenile hormone function will be elucidated by proteomic identification of the juvenile hormone-binding plasma membrane receptors coupled to functional verification, Downstream signaling events will be elucidated using live imaging microscopy in D. melanogaster embryos. Third, the conservation of isoprene lipids on the embryonic germline will be defined by elucidating the impact of retinoic acids on germ cell dynamics in Mus musculus embryos by ex vivo and in vitro necessity and sufficiency assays. Concomitantly, conservation of the post-migratory role for isoprenoids will be examined by defining the role of sex-specific differences in juvenile hormone titers in D. melanogaster germline development. Upon successful completion of this work, the impact, mechanism and conservation of juvenile hormone and retinoic acid on the embryonic germline will be defined. These insights will be important as these bioactive isoprenoids are pervasive in our environment. In fact, juvenile hormone analogues are the active ingredient of many insecticides used throughout the world and have been shown to activate retinoic acid signaling in mammalian cells. Thus, understanding the full impact of these isoprenoids on the embryonic germline is critical and the efforts to gain such understanding align well the general mission of the Eunice Kennedy Shriver National Institute of Child Health and Human Development to ensure every person is born healthy, productive, are free of disease.