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Antoni Kowalski

Plasma membrane Ca2+-ATPase isoforms composition regulates cellular pH homeostasis in differentiating PC12 cells in a manner dependent on cytosolic Ca2+ elevations

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  • Tomasz Boczek, Department of Molecular Neurochemistry, Medical University, Poland
  • Malwina Lisek, Department of Molecular Neurochemistry, Medical University, Poland
  • Bozena Ferenc, Department of Molecular Neurochemistry, Medical University, Poland
  • Antoni Kowalski
  • Dariusz Stepinski, Department of Cytophysiology, University of Lodz, Poland
  • Magdalena Wiktorska, Department of Molecular Cell Mechanisms, Medical University, Poland
  • Ludmila Zylinska, Department of Molecular Neurochemistry, Medical University, Poland
Plasma membrane Ca2+-ATPase (PMCA) by extruding Ca2+ outside the cell, actively participates in the regulation of intracellular Ca2+ concentration. Acting as Ca2+/H+ counter-transporter, PMCA transports large quantities of protons which may affect organellar pH homeostasis. PMCA exists in four isoforms (PMCA1-4) but only PMCA2 and PMCA3, due to their unique localization and features, perform more specialized function. Using differentiated PC12 cells we assessed the role of PMCA2 and PMCA3 in the regulation of intracellular pH in steady-state conditions and during Ca2+ overload evoked by 59 mM KCl. We observed that manipulation in PMCA expression elevated pHmito and pHcyto but only in PMCA2-downregulated cells higher mitochondrial pH gradient (ΔpH) was found in steady-state conditions. Our data also demonstrated that PMCA2 or PMCA3 knock-down delayed Ca2+ clearance and partially attenuated cellular acidification during KCl-stimulated Ca2+ influx. Because SERCA and NCX modulated cellular pH response in neglectable manner, and all conditions used to inhibit PMCA prevented KCl-induced pH drop, we considered PMCA2 and PMCA3 as mainly responsible for transport of protons to intracellular milieu. In steady-state conditions, higher TMRE uptake in PMCA2-knockdown line was driven by plasma membrane potential (Ψp). Nonetheless, mitochondrial membrane potential (Ψm) in this line was dissipated during Ca2+ overload. Cyclosporin and bongkrekic acid prevented Ψm loss suggesting the involvement of Ca2+-driven opening of mitochondrial permeability transition pore as putative underlying mechanism. The findings presented here demonstrate a crucial role of PMCA2 and PMCA3 in regulation of cellular pH and indicate PMCA membrane composition important for preservation of electrochemical gradient
Original languageEnglish
Article numbere102352
JournalP L o S One
Volume9
Issue7
Pages (from-to)1-15
Number of pages15
ISSN1932-6203
DOIs
Publication statusPublished - 11 Jul 2014

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