Plasma membrane Ca²⁺-ATPases can shape the pattern of Ca²⁺ transients induced by store-operated Ca²⁺ entry

Sci Signal. 2015 Feb 17;8(364):ra19. doi: 10.1126/scisignal.2005672.

Katalin Pászty ¹, Ariel J Caride ², Željko Bajzer ³, Chetan P Offord ⁴, Rita Padányi ⁵, Luca Hegedűs ⁶, Karolina Varga ⁷, Emanuel E Strehler ⁸, Agnes Enyedi ⁹

Affiliations

1 Molecular Biophysics Research Group of the Hungarian Academy of Sciences and Department of Biophysics, Semmelweis University, Budapest H-1094, Hungary.
2 Hematology Research, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
3 Division of Biomathematics, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
4 Molecular Medicine Program, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
5 Hungarian National Blood Transfusion Service, Budapest H-1113, Hungary. 2nd Department of Pathology, Semmelweis University, Budapest H-1091, Hungary.
6 Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest H-1117, Hungary.
7 2nd Department of Pathology, Semmelweis University, Budapest H-1091, Hungary. Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest H-1117, Hungary.
8 Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
9 Hungarian National Blood Transfusion Service, Budapest H-1113, Hungary. 2nd Department of Pathology, Semmelweis University, Budapest H-1091, Hungary. Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest H-1117, Hungary. enyedi.agnes@med.semmelweis-univ.hu.

PMID: 25690014 DOI: 10.1126/scisignal.2005672

Abstract

Calcium (CA(2+)) is a critical cofactor and signaling mediator in cells, and the concentration of cytosolic CA(2+) is regulated by multiple proteins, including the plasma membrane CA(2+)-ATPases (adenosine triphosphatases) (PMCAs), which use ATP to transport CA(2+) out of cells. PMCA isoforms exhibit different kinetic and regulatory properties; thus, the presence and relative abundance of individual isoforms may help shape CA(2+) transients and cellular responses. We studied the effects of three PMCA isoforms (PMCA4a, PMCA4b, and PMCA2b) on CA(2+) transients elicited by conditions that trigger store-operated CA(2+) entry (SOCE) and that blocked CA(2+) uptake into the endoplasmic reticulum in HeLa cells, human embryonic kidney (HEK) 293 cells, or primary endothelial cell isolated from human umbilical cord veins (HUVECs). The slowly activating PMCA4b isoform produced long-lasting CA(2+) oscillations in response to SOCE. The fast-activating isoforms PMCA2b and PMCA4a produced different effects. PMCA2b resulted in rapid and highly PMCA abundance-sensitive clearance of SOCE-mediated CA(2+) transients, whereas PMCA4a reduced cytosolic CA(2+), resulting in the establishment of a higher than baseline cytosolic CA(2+) concentration. Mathematical modeling showed that slow activation was critical to the sustained oscillation induced by the "slow" PMCA4b pump. The modeling and experimental results indicated that the distinct properties of PMCA isoforms differentially regulate the pattern of SOCE-mediated CA(2+) transients, which would thus affect the activation of downstream signaling pathways.

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