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)

Pigmentation genes such as TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), DCT (previously TYRP2, or tyrosinase-related protein 2), ASIP (agouti) and MC1R (melanocortin receptor 1) play a major role in cattle coat colour. To understand the genotypic profile underlying coat colour in native Korean Hanwoo cattle and Angus black cattle, portions of the above-mentioned genes were amplified. Sequence analysis revealed variation in the TYRP1 (exon 5) and MC1R genes. Restriction enzyme analysis of these two genes could distinguish between different colours of Hanwoo cattle. Quantitative estimates of melanin and eumelanin in hair from three different-coloured Hanwoo phenotypes and Angus black showed significant differences at the breed and phenotypic levels. Finally, sequence variants in MC1R were associated with total melanin and eumelanin in breeds as well as in Hanwoo phenotypes.
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PMID:Molecular variation in pigmentation genes contributing to coat colour in native Korean Hanwoo cattle. 1855 75

Xanthohumol (XH), the principal prenylflavonoid of the hop plant (Humulus lupulus L.), dose-dependently inhibited isobutylmethylxanthine (IBMX)-induced melanogenesis in B16 melanoma cells, with little cytotoxicity at the effective concentrations. Decreased melanin content was accompanied by reduced tyrosinase enzyme activity, protein and mRNA expression. The levels of tyrosinase-related protein 1 and 2 mRNAs were decreased by XH. XH also inhibited alpha-melanocyte stimulating hormone- or forskolin-induced increases in melanogenesis, suggesting an action on the cAMP-dependent melanogenic pathway. XH downregulated the protein and mRNA expression of microphthalmia-associated transcription factor (MITF), a master transcriptional regulator of key melanogenic enzymes. These results suggest that XH might act as a hypo-pigmenting agent through the downregulation of MITF in the cAMP-dependent melanogenic pathway.
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PMID:Effect of xanthohumol on melanogenesis in B16 melanoma cells. 1858 69

A series of quinolines, including chloroquine and quinine, were identified as potent pigmentation inhibitors through screening a compound library in murine melanocytes. Structure-activity relationship analysis indicated that 4-substituted amino groups with a tertiary amine side chain, such as chloroquine, were associated with robust inhibitory activity. In contrast to many previously identified pigmentation inhibitors, these newly identified inhibitors had no effect on either the level or the enzymatic activity of tyrosinase, the rate-limiting enzyme in melanin production. Rather, our results showed that these quinolines inhibited melanogenesis by disrupting the intracellular trafficking of tyrosinase-related proteins and lysosome-associated membrane protein 1 (Lamp-1). In treated melanocytes, tyrosinase and tyrosinase-related protein 1 accumulated in Lamp-1-positive perinuclear organelles instead of melanosomes, thus preventing melanogenesis. The depigmenting abilities of chloroquine and quinine salicylate were assessed in a human skin equivalent model (MelanoDerm). Both compounds were considerably more effective than arbutin, a widely used lightening agent. Our results indicate that quinolines may be useful agents for "cosmeceutical" skin lightening and treatment of hyperpigmentation disorders.
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PMID:Identification of quinolines that inhibit melanogenesis by altering tyrosinase family trafficking. 1880 17

More than 150 genes have been identified that affect skin color either directly or indirectly, and we review current understanding of physiological factors that regulate skin pigmentation. We focus on melanosome biogenesis, transport and transfer, melanogenic regulators in melanocytes, and factors derived from keratinocytes, fibroblasts, endothelial cells, hormones, inflammatory cells, and nerves. Enzymatic components of melanosomes include tyrosinase, tyrosinase-related protein 1, and dopachrome tautomerase, which depend on the functions of OA1, P, MATP, ATP7A, and BLOC-1 to synthesize eumelanins and pheomelanins. The main structural component of melanosomes is Pmel17/gp100/Silv, whose sorting involves adaptor protein 1A (AP1A), AP1B, AP2, and spectrin, as well as a chaperone-like component, MART-1. During their maturation, melanosomes move from the perinuclear area toward the plasma membrane. Microtubules, dynein, kinesin, actin filaments, Rab27a, melanophilin, myosin Va, and Slp2-a are involved in melanosome transport. Foxn1 and p53 up-regulate skin pigmentation via bFGF and POMC derivatives including alpha-MSH and ACTH, respectively. Other critical factors that affect skin pigmentation include MC1R, CREB, ASP, MITF, PAX3, SOX9/10, LEF-1/TCF, PAR-2, DKK1, SCF, HGF, GM-CSF, endothelin-1, prostaglandins, leukotrienes, thromboxanes, neurotrophins, and neuropeptides. UV radiation up-regulates most factors that increase melanogenesis. Further studies will elucidate the currently unknown functions of many other pigment genes/proteins. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.
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PMID:Physiological factors that regulate skin pigmentation. 1944 48

We have previously described the role of red hair (melanocortin-1 receptor, MC1R) and blue eye (oculocutaneous albinism type II, OCA2) gene polymorphisms in modulating the risk of cutaneous malignant melanoma (CMM) in a highly sun-exposed population of European descent. A number of recent studies, including genome-wide association studies, have identified numerous polymorphisms controlling human hair, eye, and skin color. In this paper, we test a selected set of polymorphisms in pigmentation loci (ASIP (Agouti signalling protein, nonagouti homolog (mouse) gene), TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), MC1R, OCA2, IRF4 (interferon regulatory factor 4), SLC24A4 (solute carrier family 24, member 4), and SLC45A2 (solute carrier family 45, member 2)) for association with CMM risk in a large Australian population-based case-control study. Variants in IRF4 and SLC24A4, despite being strongly associated with pigmentation in our sample, did not modify CMM risk, but the other six did. Three single nucleotide polymorphisms (rs28777, rs35391, and rs16891982) in the MATP gene (SLC45A2) exhibited the strongest crude association with risk, but this was attenuated to approximately the same effect size as that of a MC1R red hair color allele by controlling for ancestry of cases and controls. We also detected significant epistatic interactions between SLC45A2 and OCA2 alleles, and MC1R and ASIP alleles. Overall, these measured variants account for 12% of the familial risk of CMM in our population.
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PMID:Multiple pigmentation gene polymorphisms account for a substantial proportion of risk of cutaneous malignant melanoma. 1971 Jun 84

Melanotic Xp11 translocation renal cancer is a recently recognized aggressive epithelioid neoplasm with features overlapping between PEComa, carcinoma, and melanoma. We describe morphologic and immunohistochemical characteristics of a melanotic Xp11 translocation renal cancer occurring in an 18-year-old girl and perform molecular genetic studies to analyze its genetic alterations and related melanogenetic activities. The tumor was composed of solid nests of epithelioid cells bearing abundant clear to finely granular eosinophilic cytoplasm and separated by delicate vascular septa. Finely granular and nonrefractile brown melanin pigments, highlighted by Fontana-Masson stain, were scattered through the tumor. By immunohistochemistry, the tumor was diffusely and strongly labeled by TFE3 and focally stained by HMB45 in a patchy pattern. In contrast, all other applied immunomarkers, including cytokeratins, epithelial membrane antigen, vimentin, CD10, S-100, smooth muscle actin, desmin, c-kit, CD68, and microphthalmia-associated transcription factor, were nonreactive to the tumor. Reverse transcription-polymerase chain reaction and validating sequencing demonstrated PSF-TFE3 gene fusion, a novel exon composition juxtaposing PSF exon 9 to TFE3 exon 5. Up-regulations of melanogenesis-associated regulators, including microphthalmia-associated transcription factor, tyrosinase (TYR), and tyrosinase-related protein 1 (TYRP1), were identified in the tumor by semiquantitative reverse transcription-polymerase chain reaction. The morphologic and immunohistochemical discrepancies between this intriguing melanotic tumor and other documented renal cell carcinomas bearing identical PSF-TFE3 gene fusion may suggest melanotic Xp11 translocation renal cancer is a distinct entity among the MiT/TFE family neoplasms.
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PMID:Melanotic Xp11 translocation renal cancer: a case with PSF-TFE3 gene fusion and up-regulation of melanogenetic transcripts. 1980 74

Although the influence of endocrine factors is well established, the molecular and cellular mechanisms controlling coat color are not completely understood. A major mechanism for post-transcriptional regulation of gene expression is through the action of microRNAs (miRNAs), which anneal to the 3' untranslated region of mRNAs in a sequence-specific fashion and either block translation or promote transcript degradation. In this study, we investigated the expression of miRNAs in the skin of alpacas with brown vs white coat color using a microarray screen; identified potential mRNA targets for identified miRNAs among coat color genes; and subsequently determined the ability of a specific, differentially expressed miRNA (miR-25) to suppress expression of micropthalmia-associated transcription factor (MITF), a predicted miR-25 target gene that regulates genes linked to coat color. Expression of 10 different miRNA species in the skin of alpacas with brown vs white coat color was identified from microarray screens. Of the 10 alpaca skin miRNAs identified, predicted binding sites in the 3' untranslated region of RNAs encoding for known genes linked to coat color were primarily for miR-25, but sites were also identified for miR-129 and miR-377. Potential miR-25 binding sites were present in transcripts encoding for 11 coat color genes, including MITF. An inverse relationship between transcript abundance for MITF and miR-25 was observed in skin samples collected from alpacas with white vs brown coat color. Furthermore, overexpression of miR-25 in cultured melanocytes reduced MITF mRNA and protein abundance and corresponding mRNA abundance for the MITF-regulated enzymes tyrosinase and tyrosinase-related protein 1. Results support a novel functional role for miRNA-25 in the regulation of gene expression linked to coat color.
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PMID:MicroRNA-25 functions in regulation of pigmentation by targeting the transcription factor MITF in Alpaca (Lama pacos) skin melanocytes. 2003 82

Premelanosomes are presumed to be essential for melanogenesis in melanocytes and pre-natal retinal pigment epithelium (RPE) cells. We analysed melanin synthesis in adenoviral-transduced tyrosinase-gene-expressing amelanotic RPE (ARPE) 19 cells to determine whether premelanosome formation is needed for post-natal melanogenesis. The synthesis of melanogenic proteins and melanin granules was investigated by immunocytochemistry and light and electron microscopy. The occurrence of tyrosinase was analysed ultrastructurally by dihydroxyphenylalanine histochemistry. The viability of transduced cell cultures was examined via MTT assay. We found active tyrosinase in small granule-like vesicles throughout the cytoplasm and in the endoplasmic reticulum and nuclear membrane. Tyrosinase was also associated with multi-vesicular and multi-lamellar organelles. Typical premelanosomes, structural protein PMEL17, tyrosinase-related protein 1 and classic melanosomal stages I-IV were not detected. Instead, melanogenesis took place inside multi-vesicular and multi-lamellar bodies of unknown origin. Viability was not affected up to 10 days after transduction. We thus demonstrate a pathway of melanin formation lacking typical hallmarks of melanogenesis.
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PMID:The classical pathway of melanogenesis is not essential for melanin synthesis in the adult retinal pigment epithelium. 2014 Apr 56

It has been reported that melanocytes play important roles in skin and hair pigmentation and are differentiated from melanocyte stem cells (MSCs) residing in the bulge area of hair follicles. Recently, interest has been growing in MSCs because regulation of the upstream of differentiated melanocytes is essential for the determination of skin and hair pigmentation; however, their precise characteristics remain to be elucidated. The aim of this study is to explore cell-surface markers expressed on MSCs in order to understand their characteristics. To explore genes specifically expressed in the bulge region, we classified a hair follicle into four areas, hair bulb, hair bulb to bulge (lower bulge), bulge, and epidermis to bulge (upper bulge), and collected these areas from back skin sections of C57BL/6 mice by laser microdissection. Real-time RT-PCR performed on these areas revealed that Frizzled (Fzd)-4, Fzd7, low density lipoprotein receptor-related protein 5 (Lrp5), and Lrp6, receptors for Wnt molecules, were expressed higher in the bulge area than other areas. Furthermore, FACS analysis showed that populations of Fzd4(+) cells and Fzd7(+) cells were different from those of Kit(+) cells (precursor of melanocytes: melanoblasts). Fzd4(+) and Fzd7(+) cells isolated by FACS required a longer culture period to differentiate into mature melanocytes than Kit(+) cells. Up-regulation of mRNA expressions of melanocyte markers (dopa chrometautomerase: Dct, tyrosinase: Tyr, tyrosinase-related protein 1: Tyrp1) was observed in Fzd4(+) and Fzd7(+) cells following Kit(+) cells during differentiation. These results suggested that Fzd4(+) and Fzd7(+) cells were more immature than melanoblasts, therefore raising the possibility that Fzd4(+) and Fzd7(+) cells are MSCs.
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PMID:Melanocyte stem cells express receptors for canonical Wnt-signaling pathway on their surface. 2045 Aug 88

The present study was designed to assess the potential inhibitory activity of curcumin on the alpha-melanocyte stimulating hormone (alpha-MSH)-stimulated melanogenesis signal pathway in B16F10 melanoma cells. The molecular mechanism of curcumin-induced inhibitory activity on the alpha-MSH-stimulated melanogenesis signal pathway, including expression of melanogenesis-related proteins and activation of melanogenesis-regulating proteins, was examined in B16F10 cells. Curcumin suppressed the cellular melanin contents and the tyrosinase activity in alpha-MSH-stimulated B16F10 cells. In addition, the expression of melanogenesis-related proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein 1 and 2 was suppressed by curcumin in the alpha-MSH-stimulated B16F10 cells. Notably, a melanogenesis-regulating signal such as mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) or phosphatidylinositol 3-kinase (PI3K)/Akt was activated by curcumin in the B16F10 cells treated with or without alpha-MSH. The suppressive activity of curcumin on alpha-MSH-induced melanogenesis was down-regulated by PD98059 and by LY294002. Our results suggest that the suppressive activity of curcumin on alpha-MSH-stimulated melanogenesis may involve the down-regulation of MITF and its downstream signal pathway through the activation of MEK/ERK or PI3K/Akt.
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PMID:Curcumin suppresses alpha-melanocyte stimulating hormone-stimulated melanogenesis in B16F10 cells. 2051 28


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