Cell signaling microdomain with Na,K-ATPase and inositol 1,4,5-trisphosphate receptor generates calcium oscillations.
Recent studies indicate novel roles for the ubiquitous ion pump, Na,K-ATPase, in addition to its function as a key regulator of intracellular sodium and potassium concentration. We have previously demonstrated that ouabain, the endogenous ligand of Na,K-ATPase, can trigger intracellular Ca2+ oscillations, a versatile intracellular signal controlling a diverse range of cellular processes. Here we report that Na,K-ATPase and inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R) form a cell signaling microdomain that, in the presence of ouabain, generates slow Ca2+ oscillations in renal cells. Using fluorescent resonance energy transfer (FRET) measurements, we detected a close spatial proximity between Na,K-ATPase and InsP3R. Ouabain significantly enhanced FRET between Na,K-ATPase and InsP3R. The FRET effect and ouabain-induced Ca2+ oscillations were not observed following disruption of the actin cytoskeleton. Partial truncation of the NH2 terminus of Na,K-ATPase catalytic alpha1-subunit abolished Ca2+ oscillations and downstream activation of NF-kappaB. Ouabain-induced Ca2+ oscillations occurred in cells expressing an InsP3 sponge and were hence independent of InsP3 generation. Thus, we present a novel principle for a cell signaling microdomain where an ion pump serves as a receptor.
Miyakawa-Naito
Ayako
A
Department of Woman and Child Health, Karolinska Institutet, Astrid Lindgren Children's Hospital, S-171 76 Stockholm, Sweden.
Uhlén
Per
P
Lal
Mark
M
Aizman
Oleg
O
Mikoshiba
Katsuhiko
K
Brismar
Hjalmar
H
Zelenin
Sergey
S
Aperia
Anita
A
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007477:Ions; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009991:Oscillometry; D010042:Ouabain / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry*; D013552:Swine; D013997:Time Factors; D014162:Transfection
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007477:Ions; D008164:Luminescent Proteins; D016328:NF-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D049452:Green Fluorescent Proteins; D010042:Ouabain; D005982:Glutathione Transferase; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium