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Tyrosinase protects human melanocytes from ROS-generating compounds
Marzia Perluigi1, Federico De Marco, Cesira Foppoli
1Department of Biochemical Sciences, University "La Sapienza," P.le A. Moro, 5 00185, Rome, Italy. raffaella.coccia@uniromal.it
Biochemical and Biophysical Research Communications
|May 15, 2003
Summary
Tetrahydroisoquinolines (TIQs) like THP and SAL affect melanocyte viability and antioxidant enzymes. Tyrosinase activation by TIQs suggests a protective role against reactive oxygen species when detoxifying mechanisms fail.
Area of Science:
- Biochemistry
- Cell Biology
- Dermatology
Background:
- Tetrahydroisoquinolines (TIQs) are naturally occurring alkaloids formed from dopamine condensation.
- TIQs, including tetrahydropapaveroline (THP) and salsolinol (SAL), are investigated for their biological effects.
- Human primary melanocytes are crucial for skin pigmentation and protection.
Purpose of the Study:
- To investigate the effects of THP and SAL on human primary melanocyte viability.
- To assess the impact of TIQs on antioxidant enzyme activity and tyrosinase expression.
- To elucidate the role of tyrosinase in cellular protection against TIQ-induced toxicity.
Main Methods:
- Human primary melanocytes were treated with varying concentrations of THP and SAL.
- Cell viability was assessed using standard assays.
- Intracellular antioxidant enzyme activities (SOD, DT-diaphorase, glutathione peroxidase) and alpha-ketoglutarate dehydrogenase were measured.
- Tyrosinase-specific mRNA transcription and enzyme activity were analyzed.
- Experiments were conducted with and without tyrosinase inhibitors.
Main Results:
- THP and SAL were tolerated up to ~30 microM; THP showed toxicity at higher concentrations, while SAL did not up to 100 microM.
- TIQ treatment impaired antioxidant enzyme activities and decreased alpha-ketoglutarate dehydrogenase activity, particularly in THP-treated cells.
- Both TIQs increased tyrosinase mRNA, with SAL also activating tyrosinase enzyme.
- In the presence of tyrosinase inhibitors, TIQs exhibited significant cytotoxicity even at lower concentrations.
Conclusions:
- Tyrosinase plays a significant protective role against reactive oxygen species (ROS)-generating compounds like TIQs.
- Impairment of primary cellular detoxification mechanisms enhances TIQ-induced cytotoxicity.
- Melanocyte responses to TIQs highlight the importance of enzymatic defense systems in cellular protection.