Tyrosinase-related Protein-1 Gene Research Articles

Effect of Petai Bark Extract Gel on Tyrosinase and TRP1 Gene Expression (In Vivo Experimental Study on Hyperpigmented Wistar Mice Exposed to UVB Model)

UVB irradiation can induce the formation of Reactive Oxygen Species (ROS) which causes activation of melanin synthesis through activation of tyrosinase and tyrosinase related protein-1 (TRP1). Secondary metabolites contained in petai peel extract are known to play a role in inhibiting ROS production due to exposure to UVB rays. This study aims to determine the effect of administering petai peel extract gel on the expression of the tyrosinase and TRp1 genes in mouse skin tissue exposed to UVB. The research design was posttest only control group with a completely randomized design method. The samples studied were 24 mice exposed to UVB light with a wavelength of 302 nm and an energy of 390mJ/cm2/day 3 times a week for 2 weeks. This research was carried out in four groups, namely the healthy group (K1), the negative control group (K2), treatment 1 (K3) with 10% petai peel extract gel and treatment 2 (K4) with 20% petai peel extract gel. Tyrosinase and TRP1 gene expression was analyzed using qRT-PCR. qRT-PCR analysis showed that there was a significant decrease in tyrosinase and TRP1 gene expression between groups K3 (tyrosinase 3,19±2,12 and TRP1 4,96±3,42) and K4 (tyrosinase 0,65±0,44 and TRP1 2,22±1,18) compared to group K2 (tyrosinase 17,92±3,77 and TRP1 35,91±4,52). Administration of petai peel extract gel can reduce the expression of tyrosinase and TRP1 genes in hyperpigmentation mice exposed to UVB light.

Identification of polymorphisms in TYRP1, DCT and RAB38 genes and their association with coat color in alpacas

ObjectiveThe goal of this study was to characterize and investigate the effect of single nucleotide polymorphisms (SNPs) or InDels in tyrosinase related protein 1 (TYRP1), dopachrome tautomerase (DCT), and Ras-related protein 38 (RAB38) genes on coat color in South American camelids. TYRP1 is among one of the major regulators of pigmentation in mammals. DCT is a pigment cell-specific gene that plays an important role in the melanin synthesis pathway and the expression of skin color. RAB38 is involved in the transport of tyrosinase (TYR) and TYRP1, which are key enzymes in melanin production.MethodsFive fleece color tones from 327 alpacas (white, black, brown, gray and light fawn) were investigated to characterize and identify polymorphisms that play a role in coat color. Among the SNPs and Indels identified in the coding region, statistical analysis was performed to determine the association between the polymorphisms and fleece color in camelids, as well as the determination of allelic frequencies.ResultsTwenty two polymorphisms in the coding region, seven of them were nonsynonymous, eleven were synonymous, three located in the 5’UTR region and one deletion in the 3’UTR region were identified in the TYRP1 gene; in the DCT gene were identified twenty two polymorphisms, where five of them were non-synonymous, twelve were synonymous, one polymorphism in the 5’UTR region and four in the 3’UTR region; in adition, in the RAB38 gene six polymorphisms were identified, one was nonsynonymous, two were synonymous, in addition to three polymorphisms in the 3’UTR region were found in the RAB38 gene. There were low to moderate polymorphisms in the populations. Significant differences (P<0.001) were found with color fiber in the alpaca populations studied for TYRP1 and DCT genes.

Effect of Aspergilus oryzae-fermented broken rice, brewers’ rice and rice bran on melanogenesis in highly pigmented human melanoma, MNT-1

The food and beauty sectors are developing strategies to establish a link between nutrient consumption and skin health, as nutraceuticals offer a promising treatment option for some skin disorders such as hyperpigmentation and premature ageing. As a result, the consumption of food ingredients and supplements claiming to lower the risk of developing such skin problems is increasing. In this study, anti-tyrosinase potential of Aspergillus oryzae-fermented rice by-product water extracts namely fermented broken rice (FBR), brewers’ rice (FBrR), and rice bran (FRB) was assessed through in vitro study using highly pigmented human melanoma MNT-1 cells. The fermented extracts were evaluated for cytotoxicity, anti-tyrosinase activity using intracellular tyrosinase assay as well as melanin content analysis. Their effect on the gene expression of three melanogenic enzymes: tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein 2 (TRP-2) was also assessed by qPCR analysis. As a result, all extracts at tested concentrations of 50 and 100 µg/mL have a low cytotoxicity effect. Together with the positive control kojic acid, the FBR at both concentrations and the FRB at 50 µg/mL significantly decreased intracellular tyrosinase activity. However, their melanin content was not significantly reduced. The qPCR analysis indicated that FBR at 50 and 100 µg/ mL significantly reduced TYR gene expression by up to 71% and 61%, respectively. On the other hand, FBR (100 µg/mL) increased TRP-1 gene expression, whilst FRB (100 µg/ mL) elevated both TRP-1 and TRP-2 gene expression. The positive control kojic acid significantly reduced TYR, TRP-1 and TRP-2 gene expression. However, FBrR demonstrated no significant effect in any of the analyses. Based on these findings, FBR and FRB at 50 µg/mL possess anti-tyrosinase potential. However, further investigation is needed to dissect deeper mechanisms underlying their potential as functional bioingredients for nutraceutical or cosmeceutical applications.

In vitro characterization of the intramelanosomal domain of human recombinant TYRP1 and its oculocutaneous albinism type 3-related mutant variants.

Tyrosinase related protein 1 (TYRP1) is the most abundant melanosomal protein of the melanocyte, where plays an important role in the synthesis of eumelanin, possibly catalyzing the oxidation of 5,6-dihydroxyindole-2-carboxylic acid to 5,6-quinone-2-carboxylic acid. Mutations to the TYRP1 gene can result in oculocutaneous albinism type 3 (OCA3), a rare disease characterized by reduced synthesis of melanin in skin, hair, and eyes. To investigate the effect of genetic mutations on the TYRP1 structure, function, and stability, we engineered the intramelanosomal domain of TYRP1 and its mutant variants mimicking either OCA3-related changes, C30R, H215Y, D308N, and R326H or R87G mutant variant, analogous to OCA1-related pathogenic effect in tyrosinase. Proteins were produced in Trichoplusia Ni larvae, then purified, and analyzed by biochemical methods. Data shows that D308N and R326H mutants keep the native conformations and demonstrate no change in their stability and enzymatic activity. In contrast, mutations C30R and R87G localized in the Cys-rich domain show the variants misfolding during the purification process. The H215Y variant disrupts the binding of Zn2+ in the active site and thus reduces the strength of the enzyme/substrate interactions. Our results, consistent with the clinical and in silico studies, show that mutations at the protein surface are expected to have a negligible phenotype change compared to that of TYRP1. For the mutations with severe phenotype changes, which were localized in the Cys-rich domain or the active site, we confirmed a complete or partial protein misfolding as the possible mechanism of protein malfunction caused by OCA3 inherited mutations.

Baricitinib is Effective in Treating Progressing Vitiligo in vivo and in vitro.

ObjectiveTo evaluate the clinical efficacy and safety of baricitinib, a Janus kinase (JAK) inhibitor, in treating patient with progressing vitiligo, and to further explore the regulation of baricitinib on melanocytes (MCs) in vitro.MethodsFour patients with progressing vitiligo were treated with oral baricitinib for a total of 12 weeks. MCs were cultured in vitro and irradiated by high-dose ultraviolet B (UVB, 150mJ/cm2) to make an MC damaged model (MC-Ds). Baricitinib was added at a final concentration of 25 μM. Dopamine staining and NaOH method were used to measure the tyrosinase activity and melanin level, respectively, real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure the mRNA levels of tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1).ResultsSignificant re-pigmentation was observed in the week 12 without obvious side effects. Depigmentation occurred in 2 patients at the 3-month follow-up. Laboratory research found that higher doses of UVB irradiation (150mJ/cm2) could decrease melanin content of MCs, baricitinib (25 μM) could significantly promote tyrosinase activity, melanin content, and TYR, TRP-1 gene expression of MC-Ds.ConclusionOur preliminary study showed that baricitinib was effective and safe in treating progressing vitiligo. Baricitinib could promote tyrosinase activity, melanin content and TYR, TRP1 gene expression of MC-Ds in vitro.

Factors affecting gene expression associated with the skin color of black-bone chicken in Thailand

The objective of this study was to investigate the effect of breed, sex, and age on the gene expression level of melanocortin 1 receptor (MC1R), DOPA chrome tautomerase (DCT), tyrosinase-related protein 1 (TYRP1), tyrosinase (TYR), and agouti signaling protein (ASIP) genes in Thai commercial chicken lines. All chicken have received Newscastle vaccination, and no antibiotics or any drugs were used in this study. Four chicken breeds including Black-Chinese, KU-Phuparn, Sri Mok, and Pradu Hang Dam were used in this study. These breeds can be classified by their skin color into 3 group including black (Black Chinese and KU-Phuparn), light black (Sri Mok), and yellowish white (Pradu Hang Dam). One hundred chickens per breed were used in this study. Breast skin tissue was randomly collected from 8 chickens (4 males, 4 females) per breed at 4, 8, 12, and 16 wk of age. The mRNA expression was analyzed using qRT-PCR and the gene expression level was calculated as 2−ΔΔCT. From the results, breed significantly (P < 0.01) affected the expression level for the 5 genes evaluated. Birds with the black skin color had greater TYRP1 and TYR gene expression when compared to chickens with light black and yellowish-white skin color, respectively. Whereas, chickens with yellowish-white skin color had greater ASIP gene expression when compared to chickens having the other skin colors. Sex significantly affected DCT, TYRP1, and TYR gene expression where the gene expression in males was greater when compared to females (P < 0.05). Age affected all gene expression levels (P < 0.01). At 4 wk of age, MC1R, DCT, TYRP1, and TYR gene expression was the highest and decreased as bird age increased (P < 0.05); however, ASIP gene expression was greatest at 8 wk of age. After 8 wk of age all gene expression for the genes evaluated in this study decreased as age increased. In addition, an interaction between breed and sex (P < 0.05) impacted DCT and ASIP gene expression. The results from this study showed that all genes evaluated can be used as candidate markers to further improve the blackness of the chicken's skin because the most desired skin color is black in the Thai black-bone chicken population.

55 Melanocytes in Hypopigmented Burn Scar Can Be Stimulated to Produce Melanin

Abstract Introduction Currently, there are limited clinical treatments for dyschromia in burn hypertrophic scars (HTSs). Initial pilot work in a Duroc pig model showed that melanocyte quantity does not influence pigmentation. Regions of scar that are light or dark have equal numbers of melanocytes. This study aims to confirm melanocyte presence in regions of hypo- and hyper-pigmentation. If melanocytes are present, pigmentation stimulators may be a useful therapy. Methods Following IRB approval, patients with dyschromic HTSs were enrolled and demographic, injury and treatment details, and melanin indices by Skin Color Catch probes (SCC) were collected. Punch biopsies were taken of distinct regions of hyper-, hypo-, or normally pigmented scar and skin. Biopsies were processed to obtain epidermal sheets (ESs). A subset of ESs were stained using en face staining with melanocyte marker, S100b. Melanocytes were isolated from a different subset. Melanocytes were treated with NDP a-MSH, a pigmentation stimulator. mRNA was isolated from cells, and qRT-PCR was used to evaluate gene expression of melanin-synthetic genes, tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1) and dopachrome tautomerase (DCT). Results 8 patients were enrolled and the cohort included patients with Fitzpatrick skin types 5 (n=6) and 3 (n=2). HTSs ranged from 4 to 395 months old and dyschromia developed mainly due to healing by re-epithelialization and was refractory to prior scar treatments. By SCC, regions of hyper-, hypo-, and normal pigmentation had significantly different melanin indices (864.9 ± 19.8 vs. 627.1 ± 30.3 vs. 786.5 ± 21.4, p&amp;lt; 0.01). S100b en face staining showed that regions of hyper- and hypo-pigmentation contained the same number of melanocytes (14.6 ± 3.1 vs. 14.5 ± 3.2 melanocytes/HPF (n=5, p=0.99), but these cells had different dendricity, or activity (3.9 ± 0.5 vs. 0.4 ± 0.2 dendrites/cell (n=5, p&amp;lt; 0.0001). When hypo-pigmented melanocytes were treated with NDP a-MSH, cells produced melanin visible by bright-field microscopy (n=3). TYR, TYRP1, and DCT gene expression were upregulated in treated cells compared to controls. Conclusions While traditionally, it may be thought that hypo-pigmented regions of burn HTS display this phenotype because of the absence of pigment-producing cells, these data show that melanocytes are present in these scar regions. The cells are present, but they are inactive in pigment production. By treating the cells with a pigment stimulator, cells can be induced to re-pigment. Applicability of Research to Practice Patients were asked, on a scale of 1–10 with 1 being “no, not at all”, and 10 being “yes, very much”, “Is the scar color different from the color of your normal skin at present?” All patients rated this question as 10/10, indicating that scar dyschromia is a pervasive problem. Patients’ quality of life may be improved with the development of treatments for hypopigmentation.

An examination of melanogenic traits and &amp;lt;i&amp;gt;TYRP1&amp;lt;/i&amp;gt; polymorphism in Nanping and Romney Marsh sheep breeds

Abstract. The effects of mutations of the gene for tyrosinase-related protein 1 (TYRP1) on the black muscles and coat color in Nanping black-boned sheep were investigated. Tyrosinase activity and melanin content in plasma were measured and compared in three random groups of sheep: Nanping black-boned (101 heads), Nanping normal (106 heads) and Romney Marsh sheep (82 heads, Ovis aries). Eight exons and their partial flanking regions of the TYRP1 gene were amplified. Six intronic mutations and six exonic polymorphisms including two non-synonymous mutations [c.203C &gt; T (p.A68V) and c.1202T &gt; C (p.V401A)] were identified. Using a bi-directional polymerase chain reaction allele-specific amplification (bi-PASA) of the mutation c.203C &gt; T it was shown that the frequencies of allele C in the Nanping black-boned, Nanping normal and Romney Marsh sheep were respectively 0.955, 0.967 and 0.744. For the mutation c.1202T &gt; C, the frequencies of allele T in the three populations of sheep were respectively 0.777, 0.745 and 0.793 as measured using the single-strand conformation polymorphism. When the data from sheep of all three populations with the CC genotype of SNP c.203C &gt; T were pooled, it was found that there was significantly higher (P &lt; 0.05) tyrosinase activity, content of alkali-soluble melanin and ratio of eumelanin : total melanin than in the plasma of sheep with the CT and TT genotypes. This was not so within each of the three groups of sheep. No significant effect of the TRYP1 genotype on coat color was found. Further studies will be necessary to determine the cause of the black traits in Nanping black-boned sheep.

CAPN3, DCT, MLANA and TYRP1 are overexpressed in skin of vitiligo vulgaris Mexican patients.

Vitiligo is a disorder causing skin depigmentation, in which several factors have been proposed for its pathogenesis: Environmental, genetic and biological aspects of melanocytes, even those of the surrounding keratinocytes. However, the lack of understanding of the mechanisms has complicated the task of predicting the development and progression. The present study used microarray analysis to characterize the transcriptional profile of skin from Vitiligo Vulgaris (VV) patients and the identified transcripts were validated using targeted high-throughput RNA sequencing in a broader set of patients. For microarrays, mRNA was taken from 20 skin biopsies of 10 patients with VV (pigmented and depigmented skin biopsy of each), and 5 biopsies of healthy subjects matched for age and sex were used as a control. A signature was identified that contains the expression pattern of 722 genes between depigmented vitiligo skin vs. healthy control, 1,108 between the pigmented skin of vitiligo vs. healthy controls and 1,927 between pigmented skin, depigmented vitiligo and healthy controls (P<0.05; false discovery rate, <0.1). When comparing the pigmented and depigmented skin of patients with vitiligo, which reflects the real difference between both skin types, 5 differentially expressed genes were identified and further validated in 45 additional VV patients by RNA sequencing. This analysis showed significantly higher RNA levels of calpain-3, dopachrome tautomerase, melan-A and tyrosinase-related protein-1 genes. The data revealed that the pigmented skin of vitiligo is already affected at the level of gene expression and that the main differences between pigmented and non-pigmented skin are explained by the expression of genes associated with pigment metabolism.

Single-nucleotide polymorphism of MC1R, ASIP, and TYRP2 genes in wild and farmed foxes (Vulpes vulpes)

DNA mutations within genes associated with melanogenesis can affect melanin production, leading to dyschromias. Genes that are involved in synthesis of melatonin and may affect the color of skin are melanocortin 1 receptor (MC1R), agouti locus (ASIP), and tyrosinase-related protein-2 (TYRP2). In this study, SNP identification within ASIP, MC1R, and TYRP2 gene fragments in wild and farmed foxes (Vulpes vulpes) was performed. Nine mutations in the ASIP gene which allowed us to distinguish seven SNP profiles, fourteen mutations and five SNP profiles in the MC1R gene, and seven SNP profiles based on four polymorphic nucleotides in the TYRP2 gene were detected. Analyses of obtained profiles indicate that ASIP did not undergo mutations in the wild, and significant variability of SNP profiles was found for TYRP2, with specific haplotypes noted for farm foxes and American and European wild foxes.

A large insertion in intron 2 of the TYRP1 gene associated with American Palomino phenotype in American mink.

A number of American mink phenotypes display a range of brownish colours. One of these phenotypes, namely American Palomino (b (P) b (P) ) (AP) has been found to be associated with the tyrosinase-related protein 1 (TYRP1) gene by genotyping microsatellite markers in one sire family. Trials for amplifying the genomic DNA and cDNA at the beginning of intron 2 of AP TYRP1 revealed the presence of a large insertion of approximately eight kb. The insertion most likely disrupts different elements necessary for the splicing of intron 2 of the TYRP1 gene. In AP RNAseq data indicate, however, the presence of the wild-type (wt) transcript at very low levels and Western blot reveals three products when using an antibody raised against middle part of the TYRP1 protein. One individual from another brown mink phenotype-commercially named Dawn-was also investigated at the molecular level by long-range PCR and the same size insertion appears to be present. By this we suggest that certain modifiers of TYRP1 would induce different brown colour degradation, which results in at least two different phases of brown.

Ultraviolet B radiation-stimulated urocortin 1 is involved in tyrosinase-related protein 1 production in human melanoma HMV-II cells

Ultraviolet B (UVB) radiation stimulates cutaneous melanin pigmentation. The melanosomal enzyme tyrosinase-related protein 1 (TRP1) is involved in the modulation of pigment production in response to this stressor. Recent molecular and biochemical analyses have revealed the presence of corticotropin-releasing factor (CRF) and urocortin 1 (Ucn1), together with their corresponding receptors, in mammalian skin. Although CRF and Ucn1 are thought to have potent effects on the skin system, their possible roles and regulations have yet to be determined fully. Our previous findings in human melanoma HMV-II cells suggest that both CRF and Ucn1 regulate TRP1 gene expression via Nurr-1/Nur77, transcription factors that constitute the nuclear receptor 4a subgroup of orphan nuclear receptors. HMV-II cells were found to express mainly Ucn1 mRNA. This study aimed to explore the effects of UVB on Ucn1 mRNA and TRP1 protein levels in HMV-II cells. UVB (30mJ/cm2) increased Nurr-1, Nur77, and Ucn1 mRNA levels. UVB also increased TRP1 protein levels. Ucn1 knockdown inhibited the UVB-induced increases in TRP1 protein levels. These data suggest that UVB-stimulated Ucn1 contributes to TRP1 production via the transcription of both Nurr-1 and Nur77. Ucn1, produced in melanoma cells, acts on melanoma cells themselves in an autocrine manner.

Tyrosinase-related protein 1 (TYRP1) gene polymorphism and skin differential expression related to coat color in Mongolian horse

The purpose of this study was to evaluate the association among the polymorphism of the tyrosinase-related protein 1 (TYRP1) gene, differential expression in the skin, and coat color in Mongolian horses. The polymorphisms of TYRP1 in five groups of Mongolian horse, Sanhe horse and thoroughbreds were genotyped using PCR-SSCP. The relative gene expression level of TYRP1 in the skin tissues among different coat color Mongolian horses was determined using quantitative real-time PCR. The association of the TYRP1 polymorphisms with coat color was analyzed. A missense mutation (C189T) in exon 2 of TYRP1 was detected in the Mongolian horse, resulting in two genotypes: CC and CT. The TT genotype was not observed in these Mongolian horses. Allele C was found to be the predominant allele in black, bay, and chestnut horses. The results showed the TYRP1 gene polymorphism to be closely associated with dark coat color (P=2.3×10−6). The expression level of the TYRP1 gene was the highest in the chestnut skin tissues and the lowest in the gray skin tissues of Mongolian horses. These results suggest that the allele and expression of the TYRP1 gene are associated with coat color and colored coat formation in Mongolian horses. This is the first report of the association of the TYRP1 gene polymorphism with coat color in the Mongolian horse.

A premature stop codon in the TYRP1 gene is associated with brown coat colour in the European rabbit (Oryctolagus cuniculus).

Classical genetic studies in European rabbits (Oryctolagus cuniculus) suggested the presence of two alleles at the brown coat colour locus: a wild-type B allele that gives dense black pigment throughout the coat and a recessive b allele that in the homozygous condition (b/b genotype) produces brown rabbits that are unable to develop black pigmentation. In several other species, this locus is determined by mutations in the tyrosinase-related protein 1 (TYRP1) gene, encoding a melanocyte enzyme needed for the production of dark eumelanin. In this study, we investigated the rabbit TYRP1 gene as a strong candidate for the rabbit brown coat colour locus. A total of 3846 bp of the TYRP1 gene were sequenced in eight rabbits of different breeds and identified 23 single nucleotide polymorphisms (SNPs; 12 in intronic regions, five in exons and six in the 3'-untranslated region) and an insertion/deletion of 13 bp, in the 3'-untranslated region, organised in a few haplotypes. A mutation in exon 2 (g.41360196G>A) leads to a premature stop codon at position 190 of the deduced amino acid sequence (p.Trp190ter). Therefore, translation predicts a truncated TYRP1 protein lacking almost completely the tyrosinase domain. Genotyping 203 rabbits of 32 different breeds identified this mutation only in brown Havana rabbits. Its potential functional relevance in disrupting the TYRP1 protein and its presence only in brown animals strongly argue for this non-sense mutation being a causative mutation for the recessive b allele at the brown locus in Oryctolagus cuniculus.

Association of Tyrosinase (TYR) and Tyrosinase-related Protein 1 (TYRP1) with Melanic Plumage Color in Korean Quails (Coturnix coturnix).

TYR (Tyrosinase) and TYRP1 (Tyrosinase-related protein 1) play crucial roles in determining the coat color of birds. In this paper, we aimed to characterize the relationship of TYR and TYRP1 genes with plumage colors in Korean quails. The SNPs were searched by cDNA sequencing and PCR-SSCP in three plumage color Korean quails (maroon, white and black plumage). Two SNPs (367T→C and 1153C→T) were found in the coding region of TYRP1 gene, but had no significant association with plumage phenotype in Korean quails. The expression of TYR was higher in black plumage quails than that in maroon plumage quails. In contrast, the expression of TYRP1 was lower in black plumage quails than that in maroon plumage quails. This study suggested that the melanic plumage color in Korean quails may be associated with either increased production of TYR or decreased production of TYRP1.

Involvement of Nurr-1/Nur77 in corticotropin-releasing factor/urocortin1-induced tyrosinase-related protein 1 gene transcription in human melanoma HMV-II cells

Recent molecular and biochemical analyses have revealed the presence of corticotropin-releasing factor (CRF) and urocortin (Ucn), together with their corresponding receptors in mammalian skin. The melanosomal enzyme tyrosinase-related protein 1 (TRP1) is involved in modulation of pigment production in response to stressors. Although CRF and Ucn are thought to have potent effects on the skin system, their possible roles and regulation have yet to be fully determined. This study aimed to explore the effects of CRF and Ucn on TRP1 gene expression using human melanoma HMV-II cells. The mRNA of CRF, Ucn1, Ucn2, and CRF receptor type 1 (CRF1 receptor) was detected in HMV-II cells. CRF and Ucn1 stimulated TRP1 gene transcription via the CRF1 receptor, and increased both Nurr-1 and Nur77 mRNA expression levels. Both CRF- and Ucn1-induced Nurr-1/Nur77 acted via a NGFI-B response element on the TRP1 promoter. The combination of Nurr-1/Nur77 and microphthalmia-associated transcription factor, a melanocyte-specific transcription factor gene induced by α-melanocyte-stimulating hormone, had additive effects on activation of TRP1 gene transcription. The findings suggest that in human melanoma HMV-II cells both CRF and Ucn1 regulate TRP1 gene expression via Nurr-1/Nur77 production, independent of pro-opiomelanocortin or α-melanocyte-stimulating hormone stimulation.

Identification of c.483C>T polymorphism in the caprine tyrosinase-related protein 1 (TYRP1) gene

Tyrosinase-related protein 1 (TYRP1) has been shown to play a fundamental role in pigmentation both in human and mouse. In this work, we aimed to characterize the variability of the caprine TYRP1 gene and investigate its segregation in a wide array of goat breeds. By partially sequencing the coding region of the TYRP1 gene in 18 individuals from eight different breeds, we were able to identify a synonymous nucleotide substitution at exon 3 (c.483C>T). An extensive survey of Iberian and Balearic (N=175), Italian (N=99), Swiss (N=54), Asian (N=14), Canarian (N=92) and North African (N=117) goats with different coat colours was carried out. We found that the C-allele has a different distribution in European vs African breeds, being almost fixed in the latter. Moreover, the C-allele showed an increased frequency in white coated breeds (Girgentana, Grigia Molisana, Blanca de Rasquera and Saanen) when compared with those displaying a dark pigmentation (Cilentana Nera, Azpi Gorri and Murciano-Granadina). This could be due to genetic drift, migration and other factors associated with the demographic history of breeds under analysis or to a genetic hitchhiking event (c.483C>T frequencies would be shaped by a neighbouring causal mutation differentially selected in white and black goats). More refined studies will be needed to distinguish between these two alternative explanations.

A 6-bp deletion in the TYRP1 gene causes the brown colouration phenotype in Chinese indigenous pigs

Brown coat colour has been described in Chinese-Tibetan, Kele, and Dahe pigs. Here, we report the identification of a causal mutation underlying the brown colouration. We performed a genome-wide association study (GWAS) on Tibetan and Kele pigs, and found that brown colours in Chinese breeds are controlled by a single locus on pig chromosome 1. By using a haplotype-sharing analysis, we refined the critical region to a 1.5-Mb interval that encompasses only one pigmentation gene: tyrosinase-related protein 1 (TYRP1). Mutation screens of sequence variants in the coding region of TYRP1 revealed a strong candidate causative mutation (c.1484_1489del). The protein-altering deletion showed complete association with the brown colouration across Chinese-Tibetan, Kele, and Dahe breeds by occurring exclusively in brown pigs (n=121) and lacking in all non-brown-coated pigs (n=745) from 27 different breeds. The findings provide the compelling evidence that brown colours in Chinese indigenous pigs are caused by the same ancestral mutation in TYRP1. To our knowledge, this study gives the first description of GWAS identifying causal mutation for a monogenic trait in the domestic pig.

Conditions for the differentiation of melanocyte- precursor cells from human cord blood-derived mesenchymal stem cells

The loss of skin pigmentation can induce compromised cutaneous immunity, which can result in conditions such as vitiligo. In this study, we evaluated various agents that are able to induce the differentiation of stem cells into melanocytes. We found that a mixture of forskolin (FK), stem cell factor (SCF) and endothelin-3 (EDN-3) induced melanocyte-like morphology in human cord blood-derived mesenchymal stem cells (CB-MSCs). In addition, significant expression of microphthalmia-associated transcription factor-M and tyrosinase-related protein-1 genes was observed. These results suggest that a mixture of FK, SCF and EDN-3 induces the differentiation of melanocyte-precursor cells (MPCs) from CB-MSCs. Keywords : mesenchymal stem cells, melanocyte-precursor cells, forskolin, microphthalmia-associated transcription factor-M, tyrosinase-related protein-1 African Journal of Biotechnology Vol. 9(36), pp. 5975-5977, 6 September, 2010

Molecular cloning, sequence characteristics, and polymorphism analyses of the tyrosinase-related protein 2 / DOPAchrome tautomerase gene of black-boned sheep (Ovis aries)

Tyrosinase-related protein 2 (TYRP2) plays a pivotal role in the biosynthesis of eumelanin. Black-boned sheep have excessive melanin and eumelanin, resulting in dark (black) muscles and organs. This study was designed to investigate the effects of variants of the TYRP2 gene on black traits and coat colour of black-boned sheep. Melanin traits were measured in three populations of sheep (Nanping black-boned, Nanping normal, and Romney Marsh) and compared in this study. From the TYRP2 cDNA, all 8 exons and their flanking regions were amplified and characterized. Fifteen single nucleotide polymorphisms (SNPs) were identified in the exons and their flanking regions. Five exonic polymorphic sites, including two synonymous (c.93T>G and c.1140C>T) and three non-synonymous mutations (c.163C>T (p.R55W), c.605G>A (p.R202H), and c.1141A>G (p.T381A)), were retrieved. PCR-RFLP analysis of c.605G>A showed that the frequencies of allele G in the Nanping black-boned, Nanping normal, and Romney Marsh sheep were 0.632, 0.603, and 0.886, respectively. Sheep with the GG genotype had significantly (P < 0.05) lower tyrosinase activity, alkali-soluble melanin content, and ratio of eumelanin : total melanin than sheep with GA and AA genotypes when measured across all investigated samples but not when samples within each population of sheep were compared. However, there was no association of TYRP2 genotype at a single SNP position with coat colour across populations. Nonetheless, the two breeds with higher overall tyrosinase activity did produce darker and more varied coat colours than the breed with lower tyrosinase activity.