title: Motor neuron-like NSC-34 cells as a new model for the study of vitamin D metabolism in the brain.
abstract: Vitamin D3 is a pro-hormone, which is sequentially activated by 25- and 1α-hydroxylation to form 25-hydroxyvitamin D3 [25(OH)D3] and 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3], respectively. Subsequent inactivation is performed by 24-hydroxylation. These reactions are carried out by a series of CYP450 enzymes. The 25-hydroxylation involves mainly CYP2R1 and CYP27A1, whereas 1α-hydroxylation and 24-hydroxylation are catalyzed by CYP27B1 and CYP24A1, respectively, and are tightly regulated to maintain adequate levels of the active vitamin D hormone, 1α,25(OH)2D3. Altered circulating vitamin D levels, in particular 25(OH)D3, have been linked to several disorders of the nervous system, e.g., schizophrenia and Parkinson disease. However, little is known about the mechanisms of vitamin D actions in the neurons. In this study, we examined vitamin D metabolism and its regulation in a murine motor neuron-like hybrid cell line, NSC-34. We found that these cells express mRNAs for the four major CYP450 enzymes involved in vitamin D activation and inactivation, and vitamin D receptor (VDR) that mediates vitamin D actions. We also found high levels of CYP24A1-dependent 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] production, that was inhibited by the well-known CYP enzyme inhibitor ketoconazole and by several inhibitors that are more specific for CYP24A1. Furthermore, CYP24A1 mRNA levels in NSC-34 cells were up-regulated by 1α,25(OH)2D3 and its synthetic analogs, EB1089 and tacalcitol. Our results suggest that NSC-34 cells could be a novel model for the studies of neuronal vitamin D metabolism and its mechanism of actions.
authors.affiliation: Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
authors.forename: Mokhtar
authors.initials: M
authors.lastname: Almokhtar
authors.affiliation: Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Wikvall
authors.affiliation: Department of Chemistry-Biomedical Center, Analytical Chemistry and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: S J Kumari A
authors.initials: SJKA
authors.lastname: Ubhayasekera
authors.affiliation: Department of Chemistry-Biomedical Center, Analytical Chemistry and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergquist
authors.affiliation: Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden. Electronic address: Maria.Norlin@farmbio.uu.se.
authors.forename: Maria
authors.initials: M
authors.lastname: Norlin
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D045744:Cell Line, Tumor; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D051379:Mice; D009046:Motor Neurons / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000235:genetics; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D014807:Vitamin D; D003577:Cytochrome P-450 Enzyme System
keywords: Central nervous system; Cytochrome P450; Metabolism; Neuron; Vitamin D