S Breton

..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...

..The localization of these isoforms in selected epithelia that are involved in net acid/base transport, such as kidney proximal tubules and collecting ducts, and tubules from the male reproductive tract will be reviewed...

..The colocalization of NHE-RF and H(+)ATPase in B- but not A-intercalated cells suggests a role in generating, maintaining, or modulating the variable H(+)ATPase polarity that characterizes the B-cell phenotype...

..These results suggest that H(+)-ATPase is actively endocytosed and exocytosed in proton-secreting cells of the epididymis and vas deferens and that net proton secretion requires the participation of the v-SNARE cellubrevin...

..We propose that the 'polarity reversal' of the H(+)V-ATPase in B-intercalated cells is mediated by a physiologically regulated transcytotic pathway that may be similar to that existing in some other cell types...

..This acidification mechanism is a potential target for novel strategies aimed at modulating the acidification capacity of parts of the male reproductive tract and, therefore, in regulating male fertility...

..These data indicate that HOE694- and EIPA-sensitive Na+/H+ exchange may participate, together with the H+-ATPase, in luminal acidification in the male excurrent duct...

..Basolateral AE2 may participate in bicarbonate reabsorption and luminal acidification, and/or may be involved in intracellular pH homeostasis of epithelial cells of the male reproductive tract...

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..AQPs may be involved not only in the transepithelial transport of water in the epididymis but also in the postnatal development of this organ, as suggested by the differential expression of AQP2...

..These results suggest that factors that are associated with changes in distal chloride delivery govern pendrin expression in the connecting tubule and cortical collecting duct...

..Modulation of the V-ATPase-rich cell phenotype and the pathophysiology of the V-ATPase in humans and experimental animals are also discussed...

..This relocation compensates for the absence of functional B1 and maintains the luminal pH in an acidic range that is compatible with fertility...

..However, our results show no increase in cell surface V-ATPase activity in response to metabolic acidosis in ICs from these animals, consistent with their inability to appropriately acidify their urine under these conditions...

..This suggests that these enzymes have a close association and could be part of a protein complex that is involved in regulating renal distal proton secretion...

..We propose that CFTR is an important regulator of AQP9 and that the interaction between AQP9, NHERF1, and CFTR may facilitate the activation of AQP9 by cAMP...

..Therefore, modulation of the actin cortex by this severing and capping protein may represent a common mechanism by which these cells regulate their rate of proton secretion...

..The increase in luminal fluid pH in the KO mice could also be contributed to by other epithelial regulating factors including the Na(+)-dependent glutamate transporter EAAC1 formerly reported to be down regulated in the KO...

..We conclude that direct stimulation of PKA activity by cAMP is necessary and sufficient for the alkaline pH-induced accumulation of V-ATPase in clear cell apical microvilli...

..ClC-5 might facilitate endosome trafficking in the epididymis, as has been proposed in the kidney...

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..This technique will facilitate further characterization of kidney function in normal and genetically manipulated animals...

..As sAC is expressed in other acid/base transporting epithelia, including kidney and choroid plexus, this cAMP-dependent signal transduction pathway may be a widespread mechanism that allows cells to sense and modulate extracellular pH...

..These data indicate that the expression of AQP9, a likely candidate for apical transepithelial fluid and solute transport in several regions of the male reproductive tract, is modulated by androgens in the adult rat epididymis...

..These findings indicate that in addition to its role in the acidification of intracellular organelles, the B2 isoform could also contribute to transepithelial proton secretion and the maintenance of acid-base homeostasis...

..This transgenic mouse model can be used in future studies of gene expression during the development, differentiation, and maturation of renal principal cells...

..The exclusive basolateral location of syntaxin 3 in situ, however, contrasts with the apical location of this SNARE protein in some kidney epithelial cells in culture...

..In the present paper, selected aspects of V-ATPase regulation in clear cells are described and potential pathologies associated with mutations of some of the V-ATPase subunits are discussed...

..These data reveal for the first time that chronic hypertonicity can program cells in vitro and in vivo to change the insertion of a protein into the basolateral membrane instead of the apical membrane...

..The present article reviews our current knowledge regarding the distribution and function of aquaporins in the male excurrent duct...

..This loss is accompanied by, but it is not dependent on perturbation of microtubule organization and loss of membrane-associated clathrin...

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..The results provide a framework on which to base and interpret future studies on the role of Arf GTPases in the multitude of cellular trafficking events that occur in renal tubular epithelial cells...

..This regulation is at least in part mediated by various hormones and protein-protein interactions between regulatory proteins and multiple subunits of the pump...