Mammary gland involution is associated with rapid down regulation of major mammary Ca2+-ATPases.
Sixty percent of calcium in milk is transported across the mammary cells apical membrane by the plasma membrane Ca(2+)-ATPase 2 (PMCA2). The effect of abrupt cessation of milk production on the Ca(2+)-ATPases and mammary calcium transport is unknown. We found that 24 h after stopping milk production, PMCA2 and secretory pathway Ca(2+)-ATPases 1 and 2 (SPCA1 and 2) expression decreased 80-95%. PMCA4 and Sarco/Endoplasmic Reticulum Ca(2+)-ATPase 2 (SERCA2) expression increased with the loss of PMCA2, SPCA1, and SPCA2 but did not increase until 72-96 h of involution. The rapid loss of these Ca(2+)-ATPases occurs at a time of high mammary tissue calcium. These results suggest that the abrupt loss of Ca(2+)-ATPases, required by the mammary gland to regulate the large amount of calcium associated with milk production, could lead to accumulation of cell calcium, mitochondria Ca(2+) overload, calcium mediated cell death and thus play a part in early signaling of mammary involution.
Reinhardt
Timothy A
TA
Periparturient Diseases of Cattle Research Unit, Agricultural Research Service/USDA, National Animal Disease Center, 2300 Dayton Ave., Ames, IA 50010, USA. tim.reinhardt@ars.usda.gov
Lippolis
John D
JD
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008815:Mice, Inbred Strains; D008861:Microsomes / Q000201:enzymology / Q000648:ultrastructure; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism
C528285:SPCA2 protein, mouse; D053499:Plasma Membrane Calcium-Transporting ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506947:Atp2a2 protein, mouse; C506959:Atp2b2 protein, mouse; C492024:Atp2c1 protein, mouse; D000252:Calcium-Transporting ATPases