24,25-Dihydroxycholecalciferol, also known as 24,25-dihydroxyvitamin D3 and (24R)-hydroxycalcidiol (abbreviated as 24(R),25-(OH)2D3),[1] is a compound which is closely related to 1,25-dihydroxyvitamin D3, the active form of vitamin D3. Like vitamin D3 itself and calcifediol (25-hydroxyvitamin D3), it is inactive as a hormone both in vitro[2] and in vivo.[3] It was first identified in 1972 in the laboratory of Hector DeLuca and Michael F. Holick.[4]
Formation and significance
24,25-dihydroxyvitamin D3 is formed from 25-hydroxyvitamin D3 by the action of CYP24A1 (25-hydroxyvitamin D3-24-hydroxylase). CYP24A1 appears to be "a multicatalytic enzyme catalyzing most, if not all, of the reactions in the C-24/C-23 pathway of 25-OH-D3 metabolism."[5]
It has been proposed that 24,25-dihydroxyvitamin D3 is a metabolite of 25-hydroxyvitamin D3 which is destined for excretion.[5]
It is not known whether the compound might also have some physiologically significant activity. Some evidence of a possible receptor has been obtained.[6]
Because 24,25-dihydroxycholecalciferol is considered an inactive metabolite and its significance is that its concentration is expected to decrease in case of mutations inactivating the vitamin D 24-hydroxylase gene.
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.[§ 1]
^Sørnes S, Bjøro T, Berg JP, Torjesen PA, Haug E (May 1994). "Calcitriol attenuates the basal and vasoactive intestinal peptide-stimulated cAMP production in prolactin-secreting rat pituitary (GH4C1) cells". Mol Cell Endocrinol. 101 (1–2): 183–8. doi:10.1016/0303-7207(94)90233-x. PMID9397951. S2CID42457340.
^Mortensen BM, Gautvik KM, Gordeladze JO (February 1993). "Bone turnover in rats treated with 1,25-dihydroxyvitamin D3, 25-hydroxyvitamin D3 or 24,25-dihydroxyvitamin D3". Biosci Rep. 13 (1): 27–39. doi:10.1007/BF01138176. PMID8392394. S2CID19689388.
^Holick, MF; Schnoes, HK; Deluca, HF; Gray, RW; Boyle, IT; Suda, T (1972). "Isolation and identification of 24,25-dihydroxycholecalciferol, a metabolite of vitamin D made in the kidney". Biochemistry. 11 (23): 4251–5. doi:10.1021/bi00773a009. PMID4342902.
^ abBeckman MJ, Tadikonda P, Werner E, Prahl J, Yamada S, DeLuca HF (June 1996). "Human 25-hydroxyvitamin D3-24-hydroxylase, a multicatalytic enzyme". Biochemistry. 35 (25): 8465–72. doi:10.1021/bi960658i. PMID8679605.
Mata-Granados, J. M.; Luque De Castro, M. D.; Quesada Gomez, J. M. (2008). "Inappropriate serum levels of retinol, α-tocopherol, 25 hydroxyvitamin D3 and 24,25 dihydroxyvitamin D3 levels in healthy Spanish adults: Simultaneous assessment by HPLC". Clinical Biochemistry. 41 (9): 676–680. doi:10.1016/j.clinbiochem.2008.02.003. PMID18313404.