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Cholera toxin enhances Na(+) absorption across MCF10A human mammary epithelia.
Am J Physiol Cell Physiol. 2014 Mar 01; 306(5):C471-84.AJ

Abstract

Cellular mechanisms to account for the low Na(+) concentration in human milk are poorly defined. MCF10A cells, which were derived from human mammary epithelium and grown on permeable supports, exhibit amiloride- and benzamil-sensitive short-circuit current (Isc; a sensitive indicator of net ion transport), suggesting activity of the epithelial Na(+) channel ENaC. When cultured in the presence of cholera toxin (Ctx), MCF10A cells exhibit greater amiloride-sensitive Isc at all time points tested (2 h to 7 days), an effect that is not reduced with Ctx washout for 12 h. Amiloride-sensitive Isc remains elevated by Ctx in the presence of inhibitors for PKA (H-89, Rp-cAMP), PI3K (LY294002), and protein trafficking (brefeldin A). Additionally, the Ctx B subunit, alone, does not replicate these effects. RT-PCR and Western blot analyses indicate no significant increase in either the mRNA or protein expression for α-, β-, or, γ-ENaC subunits. Ctx increases the abundance of both β- and γ-ENaC in the apical membrane. Additionally, Ctx increases both phosphorylated and nonphosphorylated Nedd4-2 expression. These results demonstrate that human mammary epithelia express ENaC, which can account for the low Na(+) concentration in milk. Importantly, the results suggest that Ctx increases the expression but reduces the activity of the E3 ubiquitin ligase Nedd4-2, which would tend to reduce the ENaC retrieval and increase steady-state membrane residency. The results reveal a novel mechanism in human mammary gland epithelia by which Ctx regulates ENaC-mediated Na(+) transport, which may have inferences for epithelial ion transport regulation in other tissues throughout the body.

Authors+Show Affiliations

Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas.No affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

24371040

Citation

Wang, Qian, and Bruce D. Schultz. "Cholera Toxin Enhances Na(+) Absorption Across MCF10A Human Mammary Epithelia." American Journal of Physiology. Cell Physiology, vol. 306, no. 5, 2014, pp. C471-84.
Wang Q, Schultz BD. Cholera toxin enhances Na(+) absorption across MCF10A human mammary epithelia. Am J Physiol Cell Physiol. 2014;306(5):C471-84.
Wang, Q., & Schultz, B. D. (2014). Cholera toxin enhances Na(+) absorption across MCF10A human mammary epithelia. American Journal of Physiology. Cell Physiology, 306(5), C471-84. https://doi.org/10.1152/ajpcell.00181.2013
Wang Q, Schultz BD. Cholera Toxin Enhances Na(+) Absorption Across MCF10A Human Mammary Epithelia. Am J Physiol Cell Physiol. 2014 Mar 1;306(5):C471-84. PubMed PMID: 24371040.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cholera toxin enhances Na(+) absorption across MCF10A human mammary epithelia. AU - Wang,Qian, AU - Schultz,Bruce D, Y1 - 2013/12/26/ PY - 2013/12/28/entrez PY - 2013/12/29/pubmed PY - 2014/4/25/medline KW - ENaC KW - Isc KW - amiloride KW - cholera toxin KW - epithelial Na+ channel KW - mammary gland KW - short-circuit current SP - C471 EP - 84 JF - American journal of physiology. Cell physiology JO - Am J Physiol Cell Physiol VL - 306 IS - 5 N2 - Cellular mechanisms to account for the low Na(+) concentration in human milk are poorly defined. MCF10A cells, which were derived from human mammary epithelium and grown on permeable supports, exhibit amiloride- and benzamil-sensitive short-circuit current (Isc; a sensitive indicator of net ion transport), suggesting activity of the epithelial Na(+) channel ENaC. When cultured in the presence of cholera toxin (Ctx), MCF10A cells exhibit greater amiloride-sensitive Isc at all time points tested (2 h to 7 days), an effect that is not reduced with Ctx washout for 12 h. Amiloride-sensitive Isc remains elevated by Ctx in the presence of inhibitors for PKA (H-89, Rp-cAMP), PI3K (LY294002), and protein trafficking (brefeldin A). Additionally, the Ctx B subunit, alone, does not replicate these effects. RT-PCR and Western blot analyses indicate no significant increase in either the mRNA or protein expression for α-, β-, or, γ-ENaC subunits. Ctx increases the abundance of both β- and γ-ENaC in the apical membrane. Additionally, Ctx increases both phosphorylated and nonphosphorylated Nedd4-2 expression. These results demonstrate that human mammary epithelia express ENaC, which can account for the low Na(+) concentration in milk. Importantly, the results suggest that Ctx increases the expression but reduces the activity of the E3 ubiquitin ligase Nedd4-2, which would tend to reduce the ENaC retrieval and increase steady-state membrane residency. The results reveal a novel mechanism in human mammary gland epithelia by which Ctx regulates ENaC-mediated Na(+) transport, which may have inferences for epithelial ion transport regulation in other tissues throughout the body. SN - 1522-1563 UR - https://www.unboundmedicine.com/medline/citation/24371040/Cholera_toxin_enhances_Na_+__absorption_across_MCF10A_human_mammary_epithelia_ L2 - https://journals.physiology.org/doi/10.1152/ajpcell.00181.2013?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -