Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pale ear (ep) mouse strain is a model for the Hermansky-Pudlak syndrome type 1 (HPS-1), an autosomal recessive disorder causing pigmentary dilution, visual disturbances, bleeding diatheses, pulmonary fibrosis, and granulomatous colitis. The ep mice have a coat color very similar to the black-colored parental strain, C57BL/6. However, the ears and tails of ep mice are significantly hypopigmented compared with the control animals, suggesting that the gene mutation in ep mice reveals a differential regulation of melanocyte function in dorsal back skin melanocytes versus tail or ear skin. In this study, we analyzed the mutant phenotype in detail and determined that in the tail, the defective gene causes delayed onset of interfollicular epidermal melanocyte tyrosinase activity, decreased numbers of melanocytes in the interfollicular epidermis and dermis, and severe immaturity of tail epidermal melanosomes, findings not observed in dorsal back follicular melanocytes. These results highlight differences between follicular and interfollicular melanocyte biology and demonstrate that defects in the ep protein not only affect melanosome biogenesis, but also play a developmental role in determining interfollicular epidermal and dermal melanocyte function. The implications of these findings for the mechanisms governing physiologic variation in human pigmentation and for the pathogenesis of vitiligo are discussed.
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PMID:Hermansky-Pudlak HPS1/pale ear gene regulates epidermal and dermal melanocyte development. 1706 83

The eye has pigmented cells of two different embryonic origins and therefore it is a good model for studying melanosome biogenesis and melanin production/deposition. Pale ear mice bear a mutation in the Hermansky-Pudlak syndrome type 1 (HPS-1) gene and exhibit abnormal eye pigmentation. Here, we reported the delayed and reduced pigmentation in eyes of pale ear mice in early postnatal stages and adulthood. Tyrosinase assay and L-3,4-dihydroxyphenylalanine (L-DOPA) gel staining assay revealed that tyrosinase activity in eyes of pale ear mutants was greatly reduced in early postnatal stages and increased gradually after postnatal day 7 (P7). Further histological examination revealed that hypopigmentation in the retinal pigment epithelium (RPE) and pigment epithelium of the iris and ciliary body, which are derived from the optic cup, was more severe than that in neural crest-derived tissues. In addition, macromelanosomes were exclusively present in neural crest-derived melanocytes of pale ear adults, but absent at early postnatal stages. Taken together, the mutation in the HPS-1 gene could cause two distinct phenotypes in pigmented cells of different embryonic origins. Besides, an increased accumulation of lipofuscin in RPE was also observed.
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PMID:Two distinct phenotypes in pigmented cells of different embryonic origins in eyes of pale ear mice. 2436 Oct 37