title: Mouse mammary epithelial cells express the Na-K-Cl cotransporter, NKCC1: characterization, localization, and involvement in ductal development and morphogenesis.
abstract: Despite the fact that physiological evidence points to the existence of a functional Na-K-Cl cotransporter in the mammary gland, the molecular identity of this transport process remains unknown. We now show that the Na-K-Cl cotransporter isoform, NKCC1, is expressed in mammary tissue. Developmental profiling revealed that the level of NKCC1 protein was significantly influenced by the stage of mammary gland development, and immunolocalization studies demonstrated that NKCC1 was present on the basolateral membrane of mammary epithelial cells. To examine whether functional NKCC1 is required for mammary epithelial cell development, we used NKCC1 -/- mice. We demonstrate that NKCC1 -/- mammary epithelium exhibited a significant delay in ductal outgrowth and an increase in branching morphogenesis during virgin development. These effects were autonomous to the epithelium as assessed by mammary gland transplantation. Although the absence of NKCC1 had no apparent effect on gross mammary epithelial cell morphology during lactation, pups born to NKCC1 -/- mice failed to thrive. Finally, analysis of NKCC1 protein in mouse models that exhibit defects in mammary gland development demonstrate that high levels of NKCC1 protein are indicative of ductal epithelial cells, and the presence of NKCC1 protein is characteristic of mammary epithelial cell identity.
authors.affiliation: Laboratory of Genetics and Physiology, National Institutes of Health, Bethesda, Maryland 20892, USA. jonshi@helix.nih.gov
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Shillingford
authors.forename: Keiko
authors.initials: K
authors.lastname: Miyoshi
authors.forename: Michael
authors.initials: M
authors.lastname: Flagella
authors.forename: Gary E
authors.initials: GE
authors.lastname: Shull
authors.forename: Lothar
authors.initials: L
authors.lastname: Hennighausen
mesh_terms: D000818:Animals; D001940:Breast / Q000254:growth & development* / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D051379:Mice; D008819:Mice, Nude; D009024:Morphogenesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics / Q000378:metabolism*; D064506:Solute Carrier Family 12, Member 2; D016378:Tissue Transplantation
chemical_list: D012333:RNA, Messenger; C578878:Slc12a2 protein, mouse; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2