The MouseTsxGene Is Expressed in Sertoli Cells of the Adult Testis and Transiently in Premeiotic Germ Cells during Puberty

Abstract

Tsxis a gene of unknown function that was previously shown to be expressed specifically in the testis. In order to gain insight into the function ofTsxits pattern of expression was characterized with regard to both timing and cell type in the testis. Northern blot analysis of early postnatal testes showed not only thatTsxmessage was detectable shortly after birth, but that it increased substantially between 7 and 12 days postpartum (dpp), roughly coincident with the onset of meiosis in the mouse. AlternativeTsxtranscripts, detected by RT-PCR, included a spliced form that first appeared at around 12 dpp.In situhybridization revealedTsxsignal in the somatic Sertoli cells of the adult testis. Consistent with the data from Northern blots,in situhybridization signal was first detectable in normal pubertal testes at 12 dpp. An anti-Tsx polyclonal antiserum specifically stained premeiotic germ cells in addition to Sertoli cells of pubertal testes at 16, 19, and 27 dpp. Tsx immunostaining in germ cells was nuclear, while Sertoli cells displayed signal throughout the cytoplasm and nucleus. In the adult, Tsx was detected exclusively in Sertoli cells. In contrast, in the adult testis of the oligotriche (olt) mutant, where spermatogenesis is blocked after meiosis, Tsx protein was still present in the spermatogonial nuclei of a subset of tubules. Taken together, these results demonstrate thatTsxexpression is induced in both premeiotic germ cells and Sertoli cells during the first wave of spermatogenesis, but that expression is maintained at a detectable level only in Sertoli cells of the normal adult. The persistence ofTsxexpression seen in spermatogonia of the adultoltmutant supports the hypothesis that during the first wave of normal spermatogenesis, the advent of a late-stage cell type, either elongating spermatid or spermatozoan, is responsible for extinguishing expression in spermatogonia in normal adult testis. To our knowledge,Tsxis the first gene to show a pattern of germ cell expression that is apparently specific to the pubertal testis.