Beta-carotene uptake and bioconversion to retinol differ between human melanocytes and keratinocytes.
beta-Carotene is one of the carotenoids that has been considered to play a role in the natural defense against ultraviolet-induced skin cancer. It is not known whether epidermal cells are able to accumulate beta-carotene and, subsequently, convert it to vitamin A. We used normal cultured human keratinocytes and melanocytes to study the uptake, and possible bioconversion to retinol, of authentic or [14C]beta-carotene. The uptake was much higher in melanocytes than in keratinocytes, corresponding to a fivefold difference in the intracellular fraction after two days of incubation. An increased level of cellular retinol was noted after one day of beta-carotene incubation. The conversion of [14C]beta-carotene to [14C]retinol peaked at 24 hours of incubation in keratinocytes and melanocytes. The results suggest that beta-carotene can function as a local supply of vitamin A in the skin and that melanocytes are especially likely to store beta-carotene.
Andersson
E
E
Division of Dermatology, Department of Biomedicine and Surgery, Clinical Research Center, Faculty of Health Sciences, Linköping University, Linköping, Sweden. eva.andersson@kfc.liu.se
Vahlquist
A
A
Rosdahl
I
I
D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D003470:Culture Media; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D007700:Kinetics; D008544:Melanocytes / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*; D019207:beta Carotene / Q000378:metabolism*
D002250:Carbon Radioisotopes; D003470:Culture Media; D019207:beta Carotene; D014801:Vitamin A