Regulation of calcium signaling in dendritic cells by 1,25-dihydroxyvitamin D3.
Dendritic cells (DCs) are antigen-presenting cells that provide a link between innate and adaptive immunity. Ca(2+)-dependent signaling plays a central regulatory role in DC responses to diverse antigens. DCs are a primary target of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a secosteroid hormone, that, in addition to its well-established action on Ca(2+) homeostasis, possesses immunomodulatory properties. Surprisingly, nothing is known about its effects on DC cytosolic Ca(2+) activity. The present study explored whether 1,25(OH)(2)D(3) modifies the intracellular Ca(2+) concentration ([Ca(2+)](i)) in DCs. Here we show that mouse DCs expressed K(+)-independent (NCX1-3) and K(+)-dependent (NCKX1, 3, 4, and 5) Na(+)/Ca(2+) exchangers. Acute application of LPS (100 ng/ml) to DCs increased [Ca(2+)](i), an effect significantly blunted by prior incubation with 1,25(OH)(2)D(3). 1,25(OH)(2)D(3) increased the membrane abundance of the NCKX1 protein, up-regulated the K(+)- and Na(+)-dependent Ca(2+) entry and enhanced the K(+)-dependent Na(+)/Ca(2+) exchanger currents. The NCKX blocker 3',4'-dichlorobenzamyl (DBZ) reversed the inhibitory effect of 1,25(OH)(2)D(3) on the LPS-induced increase of [Ca(2+)](i). Expression of the costimulatory molecule CD86 was down-regulated by 1,25(OH)(2)D(3), an effect reversed by DBZ. In summary, 1,25(OH)(2)D(3) blunts the LPS-induced increase in [Ca(2+)](i) by stimulation of Na(+)/Ca(2+) exchanger-dependent Ca(2+) extrusion, an effect that contributes to 1,25(OH)(2)D(3)-mediated immunosuppression. The results disclose completely novel mechanisms in the regulation of DC maturation and function.
Shumilina
Ekaterina
E
Department of Physiology, University of Tübingen, Tübingen, Germany.
Xuan
Nguyen Thi
NT
Matzner
Nicole
N
Bhandaru
Madhuri
M
Zemtsova
Irina M
IM
Lang
Florian
F
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019831:Sodium-Calcium Exchanger / Q000235:genetics / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000494:pharmacology
D008070:Lipopolysaccharides; C499849:NCX1 protein, mouse; D012333:RNA, Messenger; C511589:Slc24a3 protein, mouse; C491739:Slc8a2 protein, mouse; C491101:Slc8a3 protein, mouse; D019831:Sodium-Calcium Exchanger; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D002118:Calcium