BHK cells transfected with NCX3 are more resistant to hypoxia followed by reoxygenation than those transfected with NCX1 and NCX2: Possible relationship with mitochondrial membrane potential.
The specific role played by NCX1, NCX2, and NCX3, the three isoforms of the Na+/Ca2+ exchanger (NCX), has been explored during hypoxic conditions in BHK cells stably transfected with each of these isoforms. Six major findings emerged from the present study: (1) all the three isoforms were highly expressed on the plasma membranes of BHK cells; (2) under physiological conditions, the three NCX isoforms showed similar functional activity; (3) hypoxia plus reoxygenation induced a lower increase of [Ca2+]i in BHK-NCX3-transfected cells than in BHK-NCX1- and BHK-NCX2-transfected cells; (4) NCX3-transfected cells were more resistant to chemical hypoxia plus reoxygenation than NCX1- and NCX2-transfected cells. Interestingly, such augmented resistance was eliminated by CBDMD (10 microM), an inhibitor of NCX and by the specific silencing of the NCX3 isoform; (5) chemical hypoxia plus reoxygenation produced a loss of mitochondrial membrane potential in NCX1- and NCX2-transfected cells, but not in NCX3-transfected cells; (6) the forward mode of operation in NCX3-transfected cells was not affected by ATP depletion, as it occurred in NCX1- and NCX2-transfected cells. Altogether, these results indicate that the brain specifically expressed NCX3 isoform more significantly contributes to the maintenance of [Ca2+]i homeostasis during experimental conditions mimicking ischemia, thereby preventing mitochondrial delta psi collapses and cell death.
Secondo
Agnese
A
Division of Pharmacology, Department of Neuroscience, School of Medicine, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy.
Staiano
Rosaria Ilaria
RI
Scorziello
Antonella
A
Sirabella
Rossana
R
Boscia
Francesca
F
Adornetto
Annagrazia
A
Valsecchi
Valeria
V
Molinaro
Pasquale
P
Canzoniero
Lorella Maria Teresa
LM
Di Renzo
Gianfranco
G
Annunziato
Lucio
L
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D015687:Cell Hypoxia; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004285:Dogs; D006706:Homeostasis / Q000187:drug effects; D007150:Immunohistochemistry; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology*; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D020033:Protein Isoforms; D034741:RNA, Small Interfering; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; D000255:Adenosine Triphosphate; D012964:Sodium; D010100:Oxygen; D002118:Calcium