title: The Ca(2+)/H(+) antiporter TMEM165 expression, localization in the developing, lactating and involuting mammary gland parallels the secretory pathway Ca(2+) ATPase (SPCA1).
abstract: Plasma membrane Ca(2+)-ATPase 2 (PMCA2) knockout mice showed that ~60% of calcium in milk is transported across the mammary cells apical membrane by PMCA2. The remaining milk calcium is thought to arrive via the secretory pathway through the actions of secretory pathway Ca(2+)-ATPase's 1 and/or 2 (SPCA1 and 2). However, another secretory pathway calcium transporter was recently described. The question becomes whether this Golgi Ca(2+)/H(+) antiporter (TMEM165) is expressed sufficiently in the Golgi of lactating mammary tissue to be a relevant contributor to secretory pathway mammary calcium transport. TMEM165 shows marked expression on day one of lactation when compared to timepoints prepartum. At peak lactation TMEM165 expression was 25 times greater than that of early pregnancy. Forced cessation of lactation resulted in a rapid ~50% decline in TMEM165 expression at 24h of involution and TMEM165 expression declined 95% at 96 h involution. It is clear that the timing, magnitude of TMEM165 expression and its Golgi location supports a role for this Golgi Ca2(+)/H(+) antiporter as a contributor to mammary Golgi calcium transport needs, in addition to the better-characterized roles of SPCA1&2.
authors: Ruminant Diseases and Immunology Research Unit, USDA/ARS, National Animal Disease Center, Ames, IA 50010, USA. Electronic address: tim.reinhardt@ars.usda.gov.
authors: Timothy A
authors: TA
authors: Reinhardt
authors: Ruminant Diseases and Immunology Research Unit, USDA/ARS, National Animal Disease Center, Ames, IA 50010, USA.
authors: John D
authors: JD
authors: Lippolis
authors: Ruminant Diseases and Immunology Research Unit, USDA/ARS, National Animal Disease Center, Ames, IA 50010, USA.
authors: Randy E
authors: RE
authors: Sacco
mesh_terms: D000818:Animals; D017920:Antiporters / Q000032:analysis* / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000032:analysis / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000032:analysis* / Q000378:metabolism*; D005260:Female; D055786:Gene Knockout Techniques; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D018613:Microscopy, Confocal; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D055571:Secretory Pathway
chemical_list: D017920:Antiporters; D027682:Cation Transport Proteins; C588275:TMEM165 protein, mouse; D053499:Plasma Membrane Calcium-Transporting ATPases; C506959:Atp2b2 protein, mouse; C492024:Atp2c1 protein, mouse; D000252:Calcium-Transporting ATPases; D002118:Calcium
keywords: Ca(2+)-ATPase; Mammary calcium transport; Mammary gland involution; PMCA; SPCA1; SPCA2; TMEM165