Expression and localisation of ephrin-B1, EphB2, and EphB4 in the mouse testis during postnatal development

EphB2, EphB4, and ephrin-B1 expression and localization in postnatal developing epididymis in mice

BACKGROUND

Eph receptors and ephrin ligands, the transmembrane proteins, function as a mechanism of communication between cells. Therefore, we intended to explore the expression array of EphB2 and EphB4 receptors and ephrin-B1 ligand in postnatal developing mouse epididymis during 1 day to 8 weeks using RT-PCR amplification and immunofluorescence staining.

RESULTS

RT-PCR analysis indicated that the expression levels of EphB2, EphB4, and ephrin-B1 in the epididymis declined with the advancement of age during the initial phases of postnatal development and stayed relatively near to adult levels until 4 weeks. We discovered that the predominant compartments expressing EphB2/B4 and ephrin-B1 emerged in the excurrent duct epithelia of postnatal developing epididymis until 3 weeks. Consequently, even before spermatozoa reach the excurrent duct in epididymis, at the age of 3 weeks, the epididymal excurrent duct system exhibits characteristics similar to those of an adult in terms of expression of EphB2/B4 and ephrin-B1. Moreover, ephrin-B1 was expressed in epididymal epithelial cells throughout the development and EphB4 was expressed only in early postnatal stages while basal cells expressed EphB4 throughout the postnatal development.

CONCLUSION

The study represents the first expression analysis of ephrin-B1, EphB2, and EphB4 in the normal mouse epididymis during the postnatal development.

ARHGEF15 is expressed in undifferentiated spermatogonia but is not required for spermatogenesis in mice

Spermatogenesis is a continual process that relies on the activities of undifferentiated spermatogonia, which contain spermatogonial stem cells (SSCs) that serve as the basis of spermatogenesis. The gene expression pattern and molecular control of fate decisions of undifferentiated spermatogonia are not well understood. Rho guanine nucleotide exchange factor 15 (ARHGEF15, also known as EPHEXIN5) is a guanine nucleotide-exchange factor (GEF) that activates the Rho protein. Here, we reported that ARHGEF15 was expressed in undifferentiated spermatogonia and spermatocytes in mouse testes; however, its deletion did not affect spermatogenesis. Arhgef15-/- mice were fertile, and histological examination of the seminiferous tubules of Arhgef15-/- mice revealed complete spermatogenesis with the presence of all types of spermatogenic cells. Proliferation and differentiation of the undifferentiated spermatogonia were not impacted; however, further analysis showed that Arhgef15 deletion resulted in decreased expression of Nanos2, Lin28a and Ddx4. Together, these findings suggest that ARHGEF15 was specifically enriched in undifferentiated spermatogonia and regulated gene expression but dispensable for spermatogenesis in mice.

Expression and localisation of ephrin-B1 and EphB4 in steroidogenic cells in the naturally cycling mouse ovary

Ephrin receptors and ligands are membrane-bound molecules that modulate diverse cellular functions such as cell adhesion, epithelial-mesenchymal transition, motility, differentiation and proliferation. We recently reported the co-expression of ephrin-B1 and EphB4 in adult and foetal Leydig cells of the mouse testis, and thus speculated that their co-expression is a common property in gonadal steroidogenic cells. Therefore, in this study we examined the expression and localisation of ephrin-B1 and EphB4 in the naturally cycling mouse ovary, as their expression patterns in the ovary are virtually unknown. We found that ephrin-B1 and EphB4 were co-expressed in steroidogenic cells of all kinds, i.e. granulosa cells and CYP17A1-positive steroidogenic theca cells as well as in 3β-HSD-positive luteal cells and the interstitial glands; their co-expression potentially serves as a good marker to identify sex steroid-producing cells even in extra-gonadal organs/tissues. We also found that ephrin-B1 and EphB4 expression in granulosa cells was faint and strong, respectively; ephrin-B1 expression in luteal cells was weak in developing and temporally mature corpora lutea (those of the current cycle) and likely strong in regressing corpora lutea (those of the previous cycle) and EphB4 expression in luteal cells was weak in corpora lutea of the current cycle and likely faint/negative in the corpora lutea of the previous cycle. These findings suggest that a luteinising hormone surge triggers the upregulation of ephrin-B1 and downregulation of EphB4, as this expression fluctuation occurs after the surge. Overall, ephrin-B1 and EphB4 expression patterns may represent benchmarks for steroidogenic cells in the ovary.