Postnatal development of H + ATPase (proton-pump)-rich cells in rat epididymis

Abstract

Active proton secretion and bicarbonate reabsorption by epithelial cells of the mammalian excurrent duct system maintains an acidic luminal pH that is involved in creating a suitable environment for sperm maturation and storage. Both an apical Na/H exchanger and an apical H+ ATPase have been implicated in luminal acidification. The H+ ATPase is located in apical and/or narrow cells in the caput epididymidis, and clear cells in the corpus and cauda epididymidis. As a step toward understanding the acute and chronic regulation of luminal acidification in excurrent ducts, we have followed the appearance of H+ ATPase-rich cells in rat epididymis during postnatal development, using antibodies to subunits of the H+ ATPase. In addition, we performed double staining with antibodies against carbonic anhydrase type II (CAII). H+ ATPase-rich cells were already detectable 2 weeks after birth in all regions of the epididymis, and reached maximum numbers after 3-4 weeks. CAII-rich cells followed a similar developmental pattern. In adult rats, the number of H+ ATPase/CAII-positive cells in the cauda was on average more than double the number in the caput epididymidis, although considerable intertubule variability was seen in both regions. Double immunostaining showed that CAII and H+ ATPase were colocalized in the same cells in the caput and cauda, but H+ ATPase-rich cells in the corpus contained low levels of CAII. These results demonstrate that differentiated subpopulations of proton-secreting epithelial cells appear early during epididymal development, and that the induction of H+ ATPase in these cells occurs prior to sexual maturation.

Relocalization of the V-ATPase B2 subunit to the apical membrane of epididymal clear cells of mice deficient in the B1 subunit

“…The marked increase in B1 expression correlates with the progressive appearance of clear cells during the first 3 wk of postnatal development (9). The subsequent decrease probably represents a "dilution" of B1-expressing clear cells within the epithelium as they are less tightly packed in the mature epithelium, as we have previously described (9). This result, therefore, further indicates that B1 is the predominant B subunit in clear cells of the epididymis.…”

“…The expression of B1 subunit mRNA increases considerably during the first 3 wk of postnatal development (200-fold increase) and remains strong in the adult (although it decreases significantly from its 2-to 4-wk levels), whereas B2 mRNA expression is very stable (maximum of 5-fold increase) from birth to adulthood. The marked increase in B1 expression correlates with the progressive appearance of clear cells during the first 3 wk of postnatal development (9). The subsequent decrease probably represents a "dilution" of B1-expressing clear cells within the epithelium as they are less tightly packed in the mature epithelium, as we have previously described (9).…”

Regulation of luminal acidification in the male reproductive tract via cell–cell crosstalk

“…Their contribution to luminal acidification is, therefore, higher in the distal epididymis than in the proximal epididymis, where bicarbonate reabsorption by principal cells occurs. As mentioned above, proton secretion by clear cells is achieved by apical V-ATPase, which works in conjunction with basolateral bicarbonate transporters (Breton et al, 1998), and cytosolic carbonic anhydrase II (Breton et al, 1996;Breton et al, 1999;Da Silva et al, 2007b). The V-ATPase inhibitors bafilomycin and concanamycin A abolish net proton secretion, as measured with an extracellular proton-selective electrode in cut-open vas deferens, a segment that also contains VATPase-rich clear cells, indicating the contribution of V-ATPase to luminal acidification (Breton et al, 1998;Breton et al, 2000a;Breton et al, 1996;Shum et al, 2008).…”

Cystatin-related epididymal spermatogenic subgroup members are part of an amyloid matrix and associated with extracellular vesicles in the mouse epididymal lumen

“…Immunofluorescence analysis using an anti-H + V-ATPase antibody, a marker for the narrow/apical/clear cells in the epididymis, was next carried out to establish if the cells that showed CRES subgroup immunostaining in apical microvesicle-containing blebs were indeed narrow/apical cells (Breton et al, 1999;Hermo et al, 2000). As shown in Fig.…”

“…Narrow/apical cells were also present, but to a lesser degree, in the initial segment and caput epithelium. We refer to the narrow/apical cells collectively since it is not clear whether these cells represent distinct cell types or are one and the same (Adamali and Hermo, 1996;Breton et al, 1999). The extracellular vesicles containing CRES subgroup members persisted along the epididymal tubule into the cauda lumen.…”