Supplementary Material for: mRNA Expression Analysis and the Molecular Basis of Neonatal Testis Defects in <i>Dmrt1</i> Mutant Mice

Transcriptional regulators containing the DM domain DNA binding motif have been found to control sexual differentiation in a diverse group of metazoan animals including vertebrates, insects, and nematodes, suggesting that these proteins may comprise a very ancient group of sexual regulators. <i>Dmrt1</i>, 1 of 7 mammalian DM domain genes, is essential for several aspects of testicular differentiation in mice. The <i>Dmrt1</i> mutant phenotype becomes apparent shortly after birth, and culminates in severe testicular dysgenesis. To better understand the roles of <i>Dmrt1</i> in testicular development we have performed a more detailed analysis of its mutant phenotypes, and we have used mRNA expression profiling to identify genes misregulated in the neonatal <i>Dmrt1</i> mutant testis. We find that <i>Dmrt1</i> mutant germ cells fail to undergo several of the normal postnatal events of germ cell development, including radial movement, mitotic proliferation, differentiation into spermatogonia, and initiation of meiosis, and they die by P14. During this period <i>Dmrt1</i> mutant Sertoli cells fail to polarize and form tight junctions, and fail to cease proliferation, eventually filling the seminiferous tubules. Expression profiling at P1 and P2 in <i>Dmrt1</i> mutant testes indicates defects in several important testicular signaling pathways (Gdnf, retinoic acid, TGFβ, FSH), and detects elevated expression of the pluripotency marker <i>Stella/Dppa3/Pgc7</i>, providing insight into the molecular basis of <i>Dmrt1</i> testis defects. This work also identifies a number of new candidate testicular regulators for further investigation.