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Tryptophan hydroxylase expression in human skin cells.
Andrzej Slominski1, Alexander Pisarchik, Olle Johansson
1Department of Pathology, University of Tennessee Health Science Center, 930 Madison Ave., #519 Memphis, TN 38163, USA. aslominski@utmem.edu
Biochimica Et Biophysica Acta
|October 16, 2003
Summary
This study found tryptophan hydroxylase (TPH) mRNA and protein widely expressed in cultured skin cells. However, in vivo, TPH is mainly found in melanocytes, suggesting localized skin serotonin and melatonin production.
Area of Science:
- Biochemistry
- Dermatology
- Molecular Biology
Background:
- Serotonin and melatonin pathways are crucial in skin physiology.
- Tryptophan hydroxylase (TPH) is the key enzyme in their biosynthesis.
- Understanding TPH expression in skin is vital for characterizing these pathways.
Purpose of the Study:
- To characterize cutaneous serotoninergic and melatoninergic pathways.
- To evaluate the expression and localization of the key enzyme TPH in human skin.
Main Methods:
- Analysis of TPH mRNA expression in various skin cells.
- Western blotting to detect TPH protein.
- Characterization of TPH protein forms using antibodies.
- RP-HPLC to identify serotonin and N-acetylserotonin.
- Immunocytochemistry to localize TPH in skin biopsies.
Main Results:
- TPH mRNA was broadly expressed in cultured human skin cells (melanocytes, fibroblasts, keratinocytes, carcinoma cells).
- TPH protein was detected, including various molecular weight forms, suggesting rapid turnover.
- Serotonin and N-acetylserotonin were detected in skin extracts.
- In vivo, TPH immunoreactivity was localized predominantly to melanocytes.
Conclusions:
- TPH is widely expressed at the mRNA and protein level in cultured skin cells.
- In vivo, TPH expression in human skin is primarily restricted to melanocytes.
- This suggests melanocytes are the main site of cutaneous serotonin and melatonin synthesis.