Distinct Expression Patterns of Different Subunit Isoforms of the V-ATPase in the Rat Epididymis1

Abstract

In the epididymis and vas deferens, the vacuolar H(+)ATPase (V-ATPase), located in the apical pole of narrow and clear cells, is required to establish an acidic luminal pH. Low pH is important for the maturation of sperm and their storage in a quiescent state. The V-ATPase also participates in the acidification of intracellular organelles. The V-ATPase contains many subunits, and several of these subunits have multiple isoforms. So far, only subunits ATP6V1B1, ATP6V1B2, and ATP6V1E2, previously identified as B1, B2, and E subunits, have been described in the rat epididymis. Here, we report the localization of V-ATPase subunit isoforms ATP6V1A, ATP6V1C1, ATP6V1C2, ATP6V1G1, ATP6V1G3, ATP6V0A1, ATP6V0A2, ATP6V0A4, ATP6V0D1, and ATP6V0D2, previously labeled A, C1, C2, G1, G3, a1, a2, a4, d1, and d2, in epithelial cells of the rat epididymis and vas deferens. Narrow and clear cells showed a strong apical staining for all subunits, except the ATP6V0A2 isoform. Subunits ATP6V0A2 and ATP6V1A were detected in intracellular structures closely associated but not identical to the TGN of principal cells and narrow/clear cells, and subunit ATP6V0D1 was strongly expressed in the apical membrane of principal cells in the apparent absence of other V-ATPase subunits. In conclusion, more than one isoform of subunits ATP6V1C, ATP6V1G, ATP6V0A, and ATP6V0D of the V-ATPase are present in the epididymal and vas deferens epithelium. Our results confirm that narrow and clear cells are well fit for active proton secretion. In addition, the diverse functions of the V-ATPase may be established through the utilization of specific subunit isoforms. In principal cells, the ATP6V0D1 isoform may have a physiological function that is distinct from its role in proton transport via the V-ATPase complex.

Aberrant expression of long noncoding RNAs in cumulus cells isolated from PCOS patients

“…Furthermore, the coding-non-coding gene co-expression network identified XLOC_011402 and a protein-coding gene (ATP6V1G3) coding for one of the isoforms of a subunit of vacuolar-H + ATPase (V-ATPase), which were coexpressed in cis. The V-ATPase is a multi-subunit enzyme that couples ATP hydrolysis to proton pumping across membranes and regulates the pH of extracellular compartments [50]. In our research, the ATP6V1G3 mRNA level was up-regulated in the CCs of PCOS patients compared to normal patients.…”

V1 and V0 Domains of the Human H+-ATPase Are Linked by an Interaction between the G and a Subunits

“…In rat, a1, a4, G1, and G3 have been shown to be present in narrow and clear cells of the epididymis and vas deferens (16), although we show here that G3 is not expressed in the human male reproductive tract. Therefore, it must be G1 rather than G3 that interacts with a1 and/or a4 in these tissues in man, highlighting the fact that species differences exist between rodent and man with regard to proton pump constituents in tissue-restricted specialized pumps (15,16). Other examples of species difference between proton pump constituents have been noted previously, such as C2 expression in kidney and lung in mouse but only kidney and placenta in man (9,14).…”

“…4). This indicates an important species difference, because in a previous study in rat, both G3 and G1 proteins were detected in narrow and clear cells of the epididymis (16).…”

The Function of Vacuolar ATPase (V-ATPase) a Subunit Isoforms in Invasiveness of MCF10a and MCF10CA1a Human Breast Cancer Cells

“…a4 targets to the apical membrane of renal intercalated cells, where V-ATPases are responsible for acid secretion into * This work was supported, in whole or in part, by National Institutes of Health the urine (8, 19 -21). a4 also localizes to the apical membrane of epididymal clear cells, where acid secretion facilitates sperm maturation (22).…”