Critical role of vitamin D in sulfate homeostasis: regulation of the sodium-sulfate cotransporter by 1,25-dihydroxyvitamin D3.
As the fourth most abundant anion in the body, sulfate plays an essential role in numerous physiological processes. One key protein involved in transcellular transport of sulfate is the sodium-sulfate cotransporter NaSi-1, and previous studies suggest that vitamin D modulates sulfate homeostasis by regulating NaSi-1 expression. In the present study, we found that, in mice lacking the vitamin D receptor (VDR), NaSi-1 expression in the kidney was reduced by 72% but intestinal NaSi-1 levels remained unchanged. In connection with these findings, urinary sulfate excretion was increased by 42% whereas serum sulfate concentration was reduced by 50% in VDR knockout mice. Moreover, levels of hepatic glutathione and skeletal sulfated proteoglycans were also reduced by 18 and 45%, respectively, in the mutant mice. Similar results were observed in VDR knockout mice after their blood ionized calcium levels and rachitic bone phenotype were normalized by dietary means, indicating that vitamin D regulation of NaSi-1 expression and sulfate metabolism is independent of its role in calcium metabolism. Treatment of wild-type mice with 1,25-dihydroxyvitamin D3 or vitamin D analog markedly stimulated renal NaSi-1 mRNA expression. These data provide strong in vivo evidence that vitamin D plays a critical role in sulfate homeostasis. However, the observation that serum sulfate and skeletal proteoglycan levels in normocalcemic VDR knockout mice remained low in the absence of rickets and osteomalacia suggests that the contribution of sulfate deficiency to development of rickets and osteomalacia is minimal.
Bolt
Merry J G
MJ
Department of Medicine, University of Chicago, IL 60637, USA.
Liu
Wenhua
W
Qiao
Guilin
G
Kong
Juan
J
Zheng
Wei
W
Krausz
Thomas
T
Cs-Szabo
Gabriella
G
Sitrin
Michael D
MD
Li
Yan Chun
YC
D000818:Animals; D015152:Blotting, Northern; D001842:Bone and Bones / Q000378:metabolism / Q000473:pathology; D002117:Calcitriol / Q000494:pharmacology*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011509:Proteoglycans / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D018167:Receptors, Calcitriol / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates / Q000097:blood / Q000378:metabolism* / Q000652:urine; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D014807:Vitamin D / Q000502:physiology*
D027682:Cation Transport Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D011509:Proteoglycans; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates; D027981:Symporters; D014807:Vitamin D; D012313:RNA; D002117:Calcitriol; D005978:Glutathione