Essential Roles of Androgen Signaling in Wolffian Duct Stabilization and Epididymal Cell Differentiation

Abstract

The epididymis is a male accessory organ and functions for sperm maturation and storage under the control of androgen. The development of the epididymis is also androgen dependent. The Wolffian duct (WD), anlagen of the epididymis, is formed in both male and female embryos; however, it is stabilized only in male embryos by testicular androgen. Androgen drives subsequent differentiation of the WD into the epididymis. Although the essential roles of androgen in WD masculinization and epididymal function have been established, little is known about cellular events regulated precisely by androgen signaling during these processes. It is also unclear whether androgen signaling, especially in the epithelia, has further function for epididymal epithelial cell differentiation. In this study we examined the cellular death and proliferation controlled by androgen signaling via the androgen receptor (AR) in WD stabilization. Analyses using AR knockout mice revealed that androgen signaling inhibits epithelial cell death in this process. Analysis of AP2α-Cre;AR(flox/Y) mice, in which AR function is deleted in the WD epithelium, revealed that epithelial AR is not required for the WD stabilization but is required for epithelial cell differentiation in the epididymis. Specifically, loss of epithelial AR significantly reduced expression of p63 that is essential for differentiation of basal cells in the epididymal epithelium. We also interrogated the possibility of regulation of the p63 gene (Trp63) by AR in vitro and found that p63 is a likely direct target of AR regulation.

Plasticity of basal cells during postnatal development in the rat epididymis

“…In particular, using the basal cell marker KRT5, we found that basal cells first appear in the VD at PNW1, then in the cauda at PNW2, and subsequently in more proximal segments of the rat epididymis during PNW3–5. In the mouse epididymis, a similar pattern of retrograde maturation has also been reported (Seiler et al 1998), although p63-positive basal cells have been detected as early as postnatal day 5 (Murashima et al 2011). By the end of PNW5, basal cells formed a uniform basal layer in all the epididymal regions, except in the initial segments, where this occurred at later time points.…”

“…Based on immunoreactivity studies carried out for the Yf subunit of glutathione S-transferase P (Yf-GST), a few basal cells have been reported to first appear at postnatal day 21 in the corpus region (Hermo et al 1994). The transcription factor p63 (also known as TP63 or TPR63), which is essential for the differentiation and maintenance of basal cells in several tissues including the epididymis (Murashima et al 2011), has been detected as early as postnatal day 10 in the vas deferens (VD; Atanassova et al 2005), at postnatal days 14–18 in the cauda region, and at postnatal day 18 in the caput of rats (Hayashi et al 2004, Atanassova et al 2005). Analysis of conditional knockout mice in which the androgen receptor was deleted in the Wolffian duct revealed a reduced expression of p63 in the epididymal epithelium when measured at postnatal day 35, indicating an early role of androgen in the establishment of basal cells (Murashima et al 2011).…”

Elimination of the male reproductive tract in the female embryo is promoted by COUP-TFII in mice

“…1D). The identity of the Wolffian duct was confirmed by the presence of Wolffian duct epithelium marker AP-2α (5) (Fig. 1, B and E).…”

Segment-specific regulation of epididymal gene expression

“…However, a considerable amount of research is needed before the reciprocal signaling between the WD epithelium and the surrounding mesenchyme is better characterized. The final differentiation of the epididymis, formation of epithelial cell types, and segmentation occurs after birth and in contrary to the embryonal development requires epithelial AR , Murashima et al 2011, O'Hara et al 2011.…”