Ontogeny of RSPO1, FOXL2, and RUNX1 during ovarian differentiation in the marsupial tammar wallaby.

BACKGROUND: RSPO1 and FOXL2 are female sex-determining genes involved in the differentiation and organization of the ovary in some eutherian mammals. Mutations or loss of function of these genes are associated with partial to full sex reversal in mice, humans, and goats. RUNX1 may also play a role in ovarian development, but its expression in marsupials has not been examined as yet. We studied the conservation and protein localization of RSPO1, FOXL2, and RUNX1 orthologs in the marsupial tammar wallaby (Notamacropus eugenii) compared to other vertebrates. RESULTS: RSPO1, FOXL2, and RUNX1 were highly conserved in their sequences across all vertebrates examined. The localization of these proteins in the tammar ovary was studied from Day 18 postpartum to adulthood. RSPO1, FOXL2, and RUNX1 were expressed in the granulosa cells of the early ovary and granulosa cells of the mature ovary, while RSPO1 expression was also found in the intra-ovarian rete and cell membrane of germ cells during the period of germ cell meiosis and meiotic arrest. CONCLUSIONS: RSPO1, FOXL2, and RUNX1 are highly conserved in the vertebrate ovary-determining pathway and were expressed in the tammar wallaby in a manner consistent with their role in the ovarian differentiation of eutherian mammals.