title: Altered regulation of cytosolic Ca²⁺ concentration in dendritic cells from klotho hypomorphic mice.
abstract: The function of dendritic cells (DCs), antigen-presenting cells regulating naïve T-cells, is regulated by cytosolic Ca²⁺ concentration ([Ca²⁺]i). [Ca²⁺]i is increased by store-operated Ca²⁺ entry and decreased by K⁺-independent (NCX) and K⁺-dependent (NCKX) Na⁺/Ca²⁺ exchangers. NCKX exchangers are stimulated by immunosuppressive 1,25-dihydroxyvitamin D3 [1,25(OH)₂D₃], the biologically active form of vitamin D. Formation of 1,25(OH)₂D₃ is inhibited by the antiaging protein Klotho. Thus 1,25(OH)₂D₃ plasma levels are excessive in Klotho-deficient mice (klothohm). The present study explored whether Klotho deficiency modifies [Ca²⁺]i regulation in DCs. DCs were isolated from the bone marrow of klothohm mice and wild-type mice (klotho+/+) and cultured for 7-9 days with granulocyte-macrophage colony-stimulating factor. According to major histocompatibility complex II (MHC II) and CD86 expression, differentiation and lipopolysaccharide (LPS)-induced maturation were similar in klothohm DCs and klotho+/+ DCs. However, NCKX1 membrane abundance and NCX/NCKX-activity were significantly enhanced in klothohm DCs. The [Ca²⁺]i increase upon acute application of LPS (1 μg/ml) was significantly lower in klothohm DCs than in klotho+/+ DCs, a difference reversed by the NCKX blocker 3',4'-dichlorobenzamyl (DBZ; 10 μM). CCL21-dependent migration was significantly less in klothohm DCs than in klotho+/+ DCs but could be restored by DBZ. NCKX activity was enhanced by pretreatment of klotho+/+ DC precursors with 1,25(OH)₂D₃ the first 2 days after isolation from bone marrow. Feeding klothohm mice a vitamin D-deficient diet decreased NCKX activity, augmented LPS-induced increase of [Ca²⁺]i, and enhanced migration of klothohm DCs, thus dissipating the differences between klothohm DCs and klotho+/+ DCs. In conclusion, Klotho deficiency upregulates NCKX1 membrane abundance and Na⁺/Ca²⁺-exchange activity, thus blunting the increase of [Ca²⁺]i following LPS exposure and CCL21-mediated migration. The effects are in large part due to excessive 1,25(OH)₂D₃ formation.
authors.affiliation: Department of Physiology, University of Tübingen, Tübingen, Germany.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.forename: Meerim K
authors.initials: MK
authors.lastname: Nurbaeva
authors.forename: Wenting
authors.initials: W
authors.lastname: Yang
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.forename: Kalina
authors.initials: K
authors.lastname: Szteyn
authors.forename: Antonella
authors.initials: A
authors.lastname: Russo
authors.forename: Nicole
authors.initials: N
authors.lastname: Heise
authors.forename: Christina
authors.initials: C
authors.lastname: Leibrock
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Xuan
authors.forename: Caterina
authors.initials: C
authors.lastname: Faggio
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuro-o
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D054421:Chemokine CCL21; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism*; D003713:Dendritic Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism*; D000090265:Klotho Proteins; D008070:Lipopolysaccharides; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout
chemical_list: D054421:Chemokine CCL21; D008070:Lipopolysaccharides; D005966:Glucuronidase; D000090265:Klotho Proteins; D002118:Calcium
keywords: CCL21; NCKX; SOCE; calcium; lipopolysaccharides; migration