Suppression of CFTR-Mediated Cl− Secretion by Enhanced Expression of Epithelial Na+ Channels in Mouse Endometrial Epithelium

Enhanced Epithelial Na+ Channel (ENaC) Activity in Mouse Endometrial Epithelium by Upregulation of .GAMMA.ENaC Subunit.

“…In that study, only the ␥ENaC expression was found to be enhanced. Together with the present results, it suggests that ␥ENaC may be involved in regulating ENaC functions, including the upregulation of ENaC activity and an inhibitory effect on CFTR activity as previously observed [14]. It should be noted that the C-terminal of the ␥ENaC subunit has a motif known to interact with a ubiquitous protein-ligase, mutations of which cause Liddle's syndrome [27][28][29].…”

“…The importance of a ␥ENaC subunit may be further revealed by our recent demonstration of suppressed CFTR-mediated Cl Ϫ secretion by an enhanced expression of ENaC in mouse endometrium [14]. In that study, only the ␥ENaC expression was found to be enhanced.…”

“…Previous studies have shown that cultured endometrial epithelia exhibit a basal I SC that can be effectively blocked by amiloride, indicative of predominant Na ϩ absorption [10,13]. We recently found that the ENaC activity of endometrial cultures could be affected by coating the permeable support with Matrigel [14], which resembles the extracellular matrix facilitating rapid epithelial reconstitution and differentiation [15,16]. As shown in Fig.…”

Endolymphatic Sodium Homeostasis by Extramacular Epithelium of the Saccule

“…The majority of current was decreased by amiloride analogues where the order of potency was benzamil Ͼ amiloride Ͼ Ͼ EIPA, which suggests that transepithelial Na ϩ transport via ENaC mostly contributes to the current. Some Na ϩ -absorbing epithelia, including semicircular canal duct, are capable of bidirectional salt transport and secrete Cl Ϫ under stimulation of the cAMP signaling pathway (Mall et al, 1999;Chan et al, 2000;Kunzelmann et al, 2000;Milhaud et al, 2002;Choi et al, 2006). In contrast, no immediate response of current to a mixture known to raise intracellular cAMP levels was observed from the saccule.…”

ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells

“…Thus, CFTR is probably not a main pathway for Cl À exit in middle ear epithelium. Since CFTR is known to be suppressed by ENaC (Chan et al, 2000), the enhanced ENaC function could be one of reason for the lowered CFTR function in NHMEE cells.…”