Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA109

Poster Communications

Localization of the Plasma Membrane Ca2+ ATPase 1 (PMCA1) to Renal and Intestinal Epithelia

P. G. Ferreira1, S. Jeromdesella1, M. Gammelgaard1, P. Svenningsen1, K. Skjødt2, H. Dimke1

1. Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark. 2. Department of Cancer and Inflammation, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.

Calcium (Ca2+) is essential for a wide range of physiological processes, such as neurological function, intracellular signalling and the stability of bone. As such, the systemic and intracellular Ca2+ concentration must be tightly regulated within a narrow range for these physiological processes to occur. A stable Ca2+ concentration in the blood is maintained by exchange from bone and by transcellular Ca2+ transport in epithelia of intestine and kidney. The four Plasma membrane Ca2+ ATPase (PMCA) genes are important for cellular Ca2+ transport. In previous studies, we have found high expression of the Ca2+ ATPase PMCA4 in the distal nephron of kidney, where high vectorial transport of Ca2+ occurs, while no PMCA4 expression was detected in intestinal epithelial cells. Using a pan-specific antibody against all PMCA forms, immunoreactivity in the intestinal epithelia was noticeable and we therefore hypothesized that PMCA1 could be the main basolateral transporter expressed in the intestine. To address this question, we raised monoclonal antibodies in mice directed specifically against PMCA1. In mice duodenum, PMCA1 antibodies stained lateral membranes of enterocytes in line with a role in intestinal Ca2+ transport. Unlike PMCA4, no major immunoreactivity was observed in basolateral membranes of tubular epithelial cells. Instead, we found discrete PMCA1 staining in sub-apical membrane domains of the proximal tubules, thick ascending limbs, distal convoluted tubules and collecting ducts. Notably, myogenic cells in peritubular capillaries and mesangial cells showed high intensity staining, and so did the smooth muscle layers in the renal and intestinal vessels. Similar strong immunoreactivity was found in the aorta. Our study finds that PMCA1 is most likely the main PMCA in the intestine, driving transcellular Ca2+ transport while maintaining a "housekeeping" function in renal epithelial cells. Abundant expression in smooth muscle cells points to a role in regulation of contractility, as supported by previous studies. Ongoing investigations aim to determine the cellular expression and regulation of PMCA1 in duodenal epithelial isolates, to provide novel insights into the role of this important calcium transporter.

Where applicable, experiments conform with Society ethical requirements