Poster Presentation The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2014

A combination of growth factors are sufficient to promote testis development and male germ-line development. (#313)

Sonja Gustin 1 , Jessica Stringer 1 , Dagmar Wilhelm 2 , Andrew Sinclair 3 , Patrick Western 1
  1. Centre for Genetic Diseases, MIMR-PHI Institute of Medical Research, Melbourne, VIC, Australia
  2. Department of Anatomy and Biochemistry , Monash University, Melbourne, VIC, Australia
  3. Murdoch Childrens Research Institute, Melbourne, VIC, Australia

Gonad formation and maturation of the testes and ovaries underpin germ-line development and reproductive health. In mice, inter-cellular signaling is central to the ability of the male sex-determining gene Sry to drive testis formation and development of the male germ-line. Ovary development is promoted through R-spondin:B-Catenin signaling in conjunction with the ovarian transcription factor FoxL2, while the retinoic acid responsive gene Stra8 promotes entry of female germ cells into meiosis. Testis determination is initiated through Sry activation of Sox9, which promotes expression of the growth factor Fgf9. FGF9 promotes testis formation and male germ-line development, but represses female germ-line characteristics, including Stra8 expression and meiosis. Activin, Tgfb and prostaglandin signaling also contribute to testis development by promoting Sertoli cell recruitment and proliferation, and mitotic arrest in the male germ-line. However, FGF9, activin or TGFb individually are not considered sufficient to drive testis formation. In this study we demonstrate that testis development can be initiated in XX gonads in the absence of Sry through the combined actions of FGF9, activin and TGFb. This leads to the acquisition of SOX9 positive Sertoli–like cells, the organization of these cells into testis-like cords and the promotion of male germ-line characteristics, indicating that these growth factors are sufficient to drive the male program in somatic cells and the germ-line. Moreover, ovarian development is suppressed, including repression of FoxL2 and Rspo1. These data demonstrate that a combination of growth factors is sufficient to promote testis formation, with implications for understanding environmental influences on sex-determination in mammals, testicular dysgenesis and reproductive health.