Dynamic expression of the prion‐like protein Doppel in ovine testicular tissue

Abstract

Transgenic knockout of the gene encoding the prion-like protein Doppel (Dpl) leads to male infertility in mice. The precise role of Dpl in male fertility is still unclear, but sperm from Dpl-deficient mice appear to be unable to undergo the normal acrosome reaction that is necessary to penetrate the zona pellucida of the ovum. We have investigated the expression pattern and some biochemical properties of Dpl in sheep testicular tissue and spermatozoa. Neither the Dpl protein nor its mRNA was detected in pre-pubertal sheep testis. This was in contrast to the findings in adult rams where both Dpl mRNA and protein were present. The molecular mass and glycosylation pattern of sheep Dpl were similar to that of mice Dpl. The Dpl protein was detected in the seminiferous epithelium during the two final (7 and 8) and the two initial (1 and 2) stages of the spermatogenic cycle in a characteristic pattern. In stage 8, an intense brim of granular Dpl-immunoreactivity associated with maturation phase spermatids was observed, while after the release of spermatozoa in stages 1 and 2, the Dpl-staining was disseminated more diffusely in the epithelium, reaching the basal lamina. From stage 3 to stage 6, Dpl-immunoreactivity could not be detected, indicating that the Dpl protein had disappeared between stages 2 and 3. Dpl was not detected on ejaculated spermatozoa. These patterns of staining indicate that Dpl is enriched in residual bodies, which are phagocytosed and destroyed by Sertoli cells after release of sperm into the lumen of the seminiferous tubule.

Goat PRND expression pattern suggests its involvement in early sex differentiation

“…This result is consistent with previously reported data obtained in bovine (Rondena et al, 2005) but differs from the expression pattern described in sheep, in which no expression was observed in prepubertal testis (Espenes et al, 2006).…”

“…The cellular and subcellular localizations of Doppel appear thus to evolve with the differentiation stage of the male and female gonads (Table 1). The germinal cytoplasmic labeling seen at 62 dpc correlates that observed in other ruminants (Rondena et al, 2005;Espenes et al, 2006). Although the subcellular localization seems to be different, this Doppel expression pattern appears quite similar to that observed for c-Kit, a protein known to be involved in gonad differentiation (for reviews, see Rossi et al, 2000;Choi and Rajkovic, 2006).…”

“…Some species differences in its expression pattern were reported (Tranulis et al, 2001). Similarly, recent immunohistochemical studies performed in human, mouse, rat, boar, ovine, and bovine reproductive tracts revealed both developmental and spatial differences in Doppel expression profiles (Peoc'h et al, 2002;Rondena et al, 2005;Uboldi et al, 2005;Espenes et al, 2006;Serres et al, 2006). Prnd knockout in mice re-sulted in male sterility associated with a sperm inability to perform the acrosome reaction and with elevated levels of oxidative DNA damage (Behrens et al, 2002;Paisley et al, 2004).…”

“…To determine the cellular and subcellular localization of Doppel protein in goat gonads, two previously reported anti-Doppel primary antibodies, directed against the ovine (Espenes et al, 2006) or bovine (Rondena et al, 2005) proteins, were tested. Both antibodies gave the same results, but stronger signals were obtained with the bovine anti-Doppel antibody (boDpl67-81).…”

The doppel gene biology: a scientific journey from brain to testis, and return

“…Furthermore, doppel ablation was not lethal to mice and animals developed normally, except that males were sterile, with their spermatozoa unable to fertilize egg cells without the removal of the zona pellucida [34]. Further refinements on the doppel expression in the reproductive trait were later introduced in mice [36], in humans [37,38], in sheep [39] and in cattle [40]. Prion and doppel double knock-out mice were also produced, excluding a potential role for the prion protein in spermiogenesis [38].…”