Conversion of vitamin D3 to hormonally active 1alpha,25-dihydroxyvitamin D3 in cultured keratinocytes: relevance to cell growth and differentiation.
The regulatory potential of intracellularly generated calcitriol on growth and differentiation of cultured keratinocytes is determined by the degree of cell confluence and availability of the highly lipophilic substrate vitamin D3 to these cells. The enzymatic conversion of vitamin D3 to calcitriol is considerably elevated in the presence of the nontoxic surfactant copolymer pluronic F127 (120 microg/ml medium) compared to the control without this agent. We found a positive correlation between the formation rate of calcitriol and inhibition of the 3H-thymidine incorporation rate into the DNA of keratinocytes. Intracellularly generated calcitriol causes a clear increase of the cell diameter, and thus has a prodifferentiating effect on keratinocytes in vitro. These findings corroborate the hypothesis that UVB-induced production of vitamin D3 in human skin results in formation of substantial amounts of calcitriol in keratinocytes which suppress the growth and initiate differentiation of these cells.
Department of Dermatology, Carl Gustav Carus Medical School, Dresden University of Technology, D-01307 Dresden, Fetscherstrasse 74, Germany. Bodo.Lehmann@mailbox.tu-dresden.de
Bodo
B
Lehmann
Katrin
K
Schättiger
Michael
M
Meurer
D002117:Calcitriol / Q000737:chemistry* / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured / Q000166:cytology; D002762:Cholecalciferol / Q000737:chemistry*; D004247:DNA / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology*; D008954:Models, Biological; D020442:Poloxamer / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012867:Skin / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry
D011108:Polymers; D013501:Surface-Active Agents; D020442:Poloxamer; D002762:Cholecalciferol; D004247:DNA; D002117:Calcitriol