Abstract
Signalling by several transforming growth factor (TGF)beta superfamily members has been implicated in driving many somatic and germ cell transitions required for full fertility. Dynamic expression of receptors, ligands and inhibitors in relationship to TGFbetas, activins and BMPs have been described, and analysis of mouse models in which the signalling by these ligands is perturbed has pinpointed specific cells affected by these ligands. Activin, TGFbetas and nodal influence fetal testis events to determine the extent of Sertoli cell proliferation and the fate of male germ cells. In our evaluation of information in the NCBI Geoprofiles database, we identified the transcript encoding a known regulator of nodal function, Nomo1, as present at high levels in the fetal and postnatal mouse testis. The peak value in the 29 days postpartum (dpp; GDS605) testis represents a phase when spermatocytes are the most abundant cell type, in accord with data from isolated mouse germ cell subtypes (GDS2390) showing Nomo1 is most abundant in d pachytene spermatocytes. We use a commercial antibody to examine the presence and cellular expression profile of nomo1 in germ and somatic cells in developing and adult testes. The antibody binds a predominant band of ~130 kDa in whole adult mouse testis lysate by Western blot (predicted size is 134kDa). In Bouin's-fixed testis sections, an intense, intracellular particulate signal is prominent in Sertoli cells at all stages and in spermatocytes. A similar signal was see in most interstitial cells. At younger ages, the strongest reactivity appeared in Sertoli cells, with the signal shifting from dispersed intracellular cytoplasmic staining in fetal and juvenile testes (e.g. embryonic day 17.5 and 5 dpp) to highly localised near regions of contact between Sertoli and germ cells. Gonocytes (0 dpp) also had a strong signal. We propose that Nomo1 contributes to regulation of nodal signalling within the developing and adult testis, while its observed subcellular localisation may reflect its role in membrane protein complex assembly. Research supported by NHMRC Fellowship to KL 545916
Published Version
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