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Updated: Apr 21, 2026
Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
DCT protects human melanocytic cells from UVR and ROS damage and increases cell viability
Stephen A Ainger1, Xuan L Yong, Shu S Wong
1Institute for Molecular Bioscience, Melanogenix Group, The University of Queensland, Brisbane, Qld, Australia.
Abstract:
Dopachrome tautomerase (DCT) is involved in the formation of the photoprotective skin pigment eumelanin and has also been shown to have a role in response to apoptotic stimuli and oxidative stress. The effect of DCT on UVR DNA damage responses and survival pathways in human melanocytic cells was examined by knockdown experiments using melanoma cells, neonatal foreskin melanoblasts (MB) in monoculture and in co-culture with human keratinocytes. MB cell strains genotyped as either MC1R WT or MC1R RHC homozygotes, which are known to be deficient in DCT, were transduced with lentivirus vectors for either DCT knockdown or overexpression. We found melanoma cell survival was reduced by DCT depletion and by UVR over time. UVR-induced p53 and pp53-Ser15 levels were reduced with DCT depletion. Knockdown of DCT in MC1R WT and MC1R RHC MB cells reduced their survival after UVR exposure, whereas increased DCT protein levels enhanced survival. DCT depletion reduced p53 and pp53-Ser15 levels in WM266-4 melanoma and MC1R WT MB cells, while MC1R RHC MB cells displayed variable levels. Both MC1R WT and RHC genotypes of MB cells were responsive to UVR at 3 h with increases in both p53 and pp53-Ser15 proteins. MC1R WT MB cell strains in coculture with keratinocytes have an increased cell survival after UVR exposure when compared to those in monoculture, a protective effect which appears to be conferred by the keratinocytes.
Insights
Dopachrome tautomerase (DCT) depletion reduces human melanocytic cell survival and DNA damage response after UVR exposure. Increased DCT enhances survival, while keratinocytes offer UV protection to melanoblasts.
Area of Science:
- Cell Biology
- Genetics
- Dermatology
Background:
- Dopachrome tautomerase (DCT) is crucial for eumelanin production, a photoprotective skin pigment.
- DCT also plays a role in cellular responses to apoptosis and oxidative stress.
- Melanocortin 1 receptor (MC1R) genotype influences UVR response and DCT deficiency.
Purpose of the Study:
- To investigate the effect of DCT on UVR DNA damage responses and survival pathways in human melanocytic cells.
- To examine DCT's role in melanoma cells, neonatal melanoblasts (MB), and co-cultures with keratinocytes.
Main Methods:
- DCT knockdown and overexpression experiments were performed using lentivirus vectors.
- Melanoma cells, MB cells (MC1R WT and MC1R RHC), and MB-keratinocyte co-cultures were exposed to UVR.
- Cell survival and levels of p53 and pp53-Ser15 proteins were analyzed.
Main Results:
- DCT depletion reduced melanoma and MB cell survival following UVR exposure.
- UVR-induced p53 and pp53-Ser15 levels were decreased with DCT depletion in most cell types.
- Increased DCT levels enhanced cell survival after UVR.
- MB cells in co-culture with keratinocytes showed increased survival post-UVR compared to monocultures.
Conclusions:
- DCT plays a significant role in human melanocytic cell survival and DNA damage response to UVR.
- DCT levels directly impact cellular resilience against UV-induced damage.
- Keratinocytes provide a protective effect to melanoblasts against UVR, independent of MC1R genotype.
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