Was the formation of 1,25-dihydroxyvitamin D3 initially a catabolic pathway?
Following solar ultraviolet radiation, epidermal 7-dehydrocholesterol is converted to previtamin D3, which then undergoes a thermal isomerization into vitamin D3. The metabolism of vitamin D3, which is usually considered as an inactive compound, gives rise to the active hormone 1,25-dihydroxyvitamin D3, following two hydroxylation steps occurring in liver and kidney. Here, we propose that this anabolic pathway can also be interpreted as a catabolic one leading to the degradation of the photoproducts of 7-dehydrocholesterol, for which a specific biological role in the skin is proposed.
Chevalier
G
G
INSERM U298, CHU, Angers, France.
Baudet
C
C
Avenel-Audran
M
M
Furman
I
I
Wion
D
D
D002117:Calcitriol / Q000378:metabolism*; D002478:Cells, Cultured; D003684:Dehydrocholesterols / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D005347:Fibroblasts; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008954:Models, Biological; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects; D013472:Sunlight; D014466:Ultraviolet Rays
D003684:Dehydrocholesterols; C016705:7-dehydrocholesterol; D002117:Calcitriol