title: Cell volume and monovalent ion transporters: their role in cell death machinery triggering and progression.
abstract: Cell death is accompanied by the dissipation of electrochemical gradients of monovalent ions across the plasma membrane that, in turn, affects cell volume via modulation of intracellular osmolyte content. In numerous cell types, apoptotic and necrotic stimuli caused cell shrinkage and swelling, respectively. Thermodynamics predicts a cell type-specific rather than an ubiquitous impact of monovalent ion transporters on volume perturbations in dying cells, suggesting their diverse roles in the cell death machinery. Indeed, recent data showed that apoptotic collapse may occur in the absence of cell volume changes and even follow cell swelling rather than shrinkage. Moreover, side-by-side with cell volume adjustment, monovalent ion transporters contribute to cell death machinery engagement independently of volume regulation via cell type-specific signaling pathways. Thus, inhibition of Na(+)-K(+)-ATPase by cardiotonic steroids (CTS) rescues rat vascular smooth muscle cells from apoptosis via a novel Na(+)i-K(+)i-mediated, Ca(2+)i-independent mechanism of excitation-transcription coupling. In contrast, CTS kill renal epithelial cells independently of Na(+)-K(+)-ATPase inhibition and increased [Na(+)]i/[K(+)]i ratio. The molecular origin of [Na(+)]i/[K(+)]i sensors involved in the inhibition of apoptosis as well as upstream intermediates of Na(+)i/K(+)i-independent death signaling triggered by CTS remain unknown.
authors.affiliation: Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada. sergei.n.orlov@umontreal.ca
authors.forename: Sergei N
authors.initials: SN
authors.lastname: Orlov
authors.forename: Alexandra A
authors.initials: AA
authors.lastname: Platonova
authors.forename: Pavel
authors.initials: P
authors.lastname: Hamet
authors.forename: Ryszard
authors.initials: R
authors.lastname: Grygorczyk
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002301:Cardiac Glycosides / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects; D019610:Cytoprotection; D006801:Humans; D017136:Ion Transport; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009336:Necrosis; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013816:Thermodynamics; D014882:Water-Electrolyte Balance
chemical_list: D002301:Cardiac Glycosides; D026901:Membrane Transport Proteins; D000254:Sodium-Potassium-Exchanging ATPase
keywords: apoptosis; cell volume; intracellular Na+, intracellular K+; necrosis