Synthesis, characterization and hormonal regulation of epididymal proteins during postnatal development of the mouse

Cytokeratin localization and basal cell differentiation in the epididymal epithelium during postnatal development of the mouse

The epididymis is a male genital organ that has plays various functions, including sperm concentration, maturation, and storage. The epididymal epithelium consists of principal cells, clear cells, and basal cells. To comprehensively understand the occurrence and morphological differentiation of basal cells, we examined the expression and localization of cytokeratins (CKs) in the epididymal epithelium during postnatal development of the mouse. Immunohistochemical staining showed that, in adult mice, CK5 and CK14 were exclusively expressed in the cytoplasm of basal cells. During postnatal development, basal cells that stained positive for CK5 and CK14 first appeared in immature columnar epithelial cells in mice aged 1 week. The immunoreactivity became progressively stronger in mice aged 2-3 weeks. In mice aged 3 weeks, the immunoreactivity was strong in regions IV and V. In mice aged ≥ 4 weeks, strong immunoreactivity was observed in all epididymal regions. CK5 and CK14 could be useful markers of differentiation in epididymal basal cells. These basal cells originate from immature columnar epithelial cells and are of two types—dome-shaped and flask-shaped—. The flask-shaped cells are mainly located in the initial segment of the mouse epididymis.

Morphological and functional alterations in adult boar epididymis: Effects of prenatal and postnatal administration of flutamide

Background

The dynamic cross-talk between epididymal cells is hormonally regulated and, in part, through direct cell-to-cell interactions. To date, no information is available regarding possible impact of anti-androgens on the proteins involved in the gap junctional communication within the boar epididymis. Thus, a question arised whether prenatal or postnatal exposure to an anti-androgen flutamide alters the expression of gap junction protein - connexin43 (Cx43) and androgen receptor (AR) expression in the caput, corpus and cauda epididymis and leads to delayed effects on morphology and function of adult pig epididymis.

Methods

First two experimental groups received flutamide prenatally on gestational days 20-28 and 80-88 (GD20 and GD80) and further two groups were exposed to flutamide postanatally on days 2-10 and 90-98 after birth (PD2 and PD90). Epididymides were collected from adult boars. Routine histology was performed using hematoxylin-eosin staining. The expression of Cx43 and AR were analyzed using immunohistochemistry and Western blotting. Both analyses were supported by quantitative approaches to demonstrate the variations of the expression levels following the treatment. Apoptotic cells were identified using TUNEL assay.

Results

Histological examination revealed differences in epididymal morphology of flutamide-exposed boars when compared to controls. Scarce spermatic content were seen within the corpus and cauda lumina of GD20, PD2 and PD90 groups. Concomitantly, frequency of epididymal cell apoptosis was significantly higher (p < 0.05) after exposure to flutamide at GD20. Moreover, in GD20, PD2, and PD90 groups, significantly lower AR expression (p < 0.05) was found in the principal and basal cells of the corpus and cauda regions, while in the stromal cells AR expression was significantly reduced (p < 0.05) along the epididymal duct. Concomitantly, a decrease in Cx43 expression (p < 0.05) was noticed in the stromal cells of the cauda region of GD20 and PD2 groups. This indicates high sensitivity of the stromal cells to androgen withdrawal.

Conclusions

The region-specific alterations in the epididymis morphology and scarce spermatic content within the lumina of the corpus and cauda indicate that flutamide can induce delayed effects on the epididymal function of the adult boar by decrease in AR protein levels that results in altered androgen signaling. This may cause disturbances in androgen-dependent processes including Cx43 (de)regulation, however, we can not exclude the possibility that in response to flutamide decreased Cx43 expression may represent one mechanism responsible for functional disturbance of the boar epididymis.

Delivery of ferric ion to mouse spermatozoa is mediated by lipocalin internalization

The aim of this study was to illustrate the further process of 24p3 protein after association with epididymal spermatozoa. We have previously identified a caput-initiated 24p3 protein, which interacts with the spermatozoa surface in vitro. In the present study, we investigate another role of the 24p3 protein with spermatozoa. Mouse epididymal spermatozoa exhibit the ability to bind spontaneously with exogenous 24p3 protein, a part of which is further internalized into the spermatozoa in epididymal caput. We have now focused on this issue using freshly prepared spermatozoa from caudal region of epididymis. First, the cytosolic fractionation of spermatozoa has revealed that biotinylated 24p3 protein signal could be detected by supplying biotinylated protein under 37 degrees C incubation after 30 min at this experiment. Further, flow cytometric analysis of FITC-protein containing spermatozoa has revealed two distinct types of fluorescent spermatozoa, and microscopical experimentation with fluorescent FITC-24p3 protein has shown that the 24p3 protein did accumulate in the cytosolic portion of spermatozoa. All of these events, which showed protein uptake into the cell, demonstrated time- and temperature-dependence of endocytotic characteristics, these constituting the critical points in the process of endocytosis for spermatozoa as for other cells. Using a fluorometric method, the binding affinities of ferrous ion and ferric ion to 24p3 protein were shown to be (1.5+/-0.2)x10(6) and (3.0+/-0.4)x10(7)M(-1), respectively. We have also determined the internalization of this protein in the transition of iron into spermatozoa. We report here that spermatozoa, from the caudal epididymis, demonstrate the ability to bind with 24p3 protein and further internalize it and deliver the ferric ion to the spermatozoa via protein internalization. We suggest that the 24p3 protein plays a physiological role in spermatozoa in the context of protein-ligand complex internalization.

Prostaglandin D2 synthase secreted in the caput epididymidis displays spatial and temporal delay between messenger RNA and protein expression during postnatal development

Highly regionalized protein secretory activity is established progressively throughout the epididymal tubule during postnatal development. Prostaglandin D(2) synthase (PGDS) is a major protein in the ovine epididymis, the secretion of which is restricted to the proximal part of the epididymis. We investigated the mRNA and protein expression of PGDS during ontogenesis. PGDS mRNA was present in the testis and epididymis in the 50-day-old sheep fetus and persisted until 4 mo of age (2 mo before puberty) without mRNA translation in the epididymis. At 4.5 mo, mRNA was present in all of the epididymis, but translation occurred in only the proximal caput. The secreted protein present in the lumen from the caput to the cauda had the same molecular mass and isoelectric point (pI) characteristics as the testicular form. At 5.5 mo, both mRNA and protein expression were restricted to the proximal caput. The protein secreted accumulated in the cauda but was not processed after secretion as it is in the adult animal; no changes in molecular mass or pI were observed. Our results show that for at least one gene (PGDS), transcriptional and posttranscriptional regulation during postnatal development is linked to the presence of unidentified translation factors present in testicular fluid.

Expression, immunolocalization and sperm-association of a protein derived from 24p3 gene in mouse epididymis

The cDNA sequence for 24p3 protein in ICR mouse epididymal tissue was determined by PCR using primers designed according to the cDNA sequence derived from 24p3 protein in mouse uterine tissue. In the present study, 24p3 protein was immunolocalized in the epithelial cells and lumen of mouse epididymis. Both immunoblot analysis for protein and northern blot analysis for mRNA level showed a declining gradient of 24p3 expression from the caput to caudal region of the epididymis. The 24p3 protein was undetectable in the testis. These findings suggest that the 24p3 protein is a caput-initiated secretory protein in the mouse epididymis. A postnatal study revealed that 24p3 gene expression occurred in mice at the age of 14 days, before the completion of epididymal differentiation. This expression remained at a constant level until epididymal differentiation was completed. We also found that the secreted 24p3 protein interacted predominantly with the acrosome of caudal spermatozoa. Our findings suggest that the epididymal 24p3 protein is a caput-initiated and sperm-associated gene product and may be important in the reproductive system.

Postnatal development and regulation of proteins secreted in the boar epididymis

The number of proteins secreted by the boar epididymis increased progressively from 1 mo of age to the adult period. The first specific secretory activity was revealed at 2 mo in the distal caput (hexosaminidase, clusterin, and lactoferrin) and in the corpus (train O/HE1). Train A and glutathione peroxidase specific to the proximal caput, and trains E and M specific to the corpus, appeared at 4 mo. At 5 mo, secretion of procathepsin L occurred in the middle caput and that of mannosidase and E-RABP in the distal caput. Approximately 48% of all the proteins secreted in the adult boar epididymis were dependent on the presence of androgens, either stimulated (33.6%) or repressed (14.4%); 47% were modulated by other factors, and 5% were unregulated. In the proximal caput, 50% of the specific secreted proteins were controlled essentially by factors emanating from the testis. In more distal regions, two proteins secreted in the corpus were regulated by factors from the anterior regions. The regionalization of the secretory activity of the epididymal epithelium resulted in a specific regulation for each protein, which was modulated according to the region of expression and influenced by either testicular or epididymal factors that remain to be identified.

Effects of castration on thiol status in rat spermatozoa and epididymal fluid

Mammalian spermatozoa gain their fertilizing ability as they mature in the epididymis, a process which is accompanied by oxidation of sperm protein thiols. Since sperm maturation is dependent upon normal androgenic support to the epididymis, the present work was designed to study the effects of castration on thiol status. Spermatozoa and epididymal fluid were isolated from the epididymides of male rats 5 days after castration or after 11 daily injections of the antiandrogen, cyproterone acetate. Spermatozoa and epididymal fluid were labeled with the fluorescent thiol labeling agent monobromobimane. Intact spermatozoa were evaluated by fluorescence microscopy, protein thiols were analyzed by electrophoresis, and fertilizing ability was examined after insemination of sperm suspension into the uterine horns of immature superovulated female rats. We found that both treatments resulted in an increase in cauda sperm thiols as shown by increased fluorescence in the intact spermatozoa. Protamines and nonbasic proteins were found to have increased levels of reactive thiols. The protein profiles of epididymal fluid from castrated rats were different from those of the controls, and the fluorescence patterns corresponded to the protein profiles. Our results indicate that testosterone withdrawal leads to inhibition of sperm thiol oxidation.

Pax-2: a developmental gene constitutively expressed in the mouse epididymis and ductus deferens

PURPOSE

To characterize expression of the transcriptional activator, Pax-2, in the mouse lower genitourinary tract.

MATERIALS AND METHODS

Expression of Pax-2 was studied by Northern analysis, ribonuclease protection and immunohistochemistry.

RESULTS

Immunostaining revealed localized expression in the epithelium of the ductus deferens and epididymis at all time points from birth to adulthood. Expression in these structures in adult mice was confirmed by Northern analysis and ribonuclease protection assays.

CONCLUSION

Pax-2 is a transcriptional regulator expressed in the epithelium of the ductus deferens and epididymis and may be a regulator of epithelial genes involved in sperm maturation and support.