Tyrosinase Gene Expression Research Articles

Anti-Melanogenic Activity of Undecylprodigiosin, a Red Pigment Isolated from a Marine Streptomyces sp. SNA-077.

Bioassay and HPLC-UV guided fractionations of the crude extract of marine-derived Streptomyces sp. SNA-077 have led to the isolation of a red pigment, undecylprodigiosin (1). The chemical structure of undecylprodigiosin (1) was revealed by the interpretation of NMR and mass spectroscopic (MS) data. Further, anti-melanogenic effects of undecylprodigiosin (1) were investigated. First, the melanin contents of undecylprodigiosin (1)-treated B16 cells were evaluated. Furthermore, undecylprodigiosin (1) significantly inhibited the key enzymes involved in melanogenesis, including tyrosinase, tyrosinase related protein-1 (TYRP-1), and dopachrome tautomerase (DCT). The mRNA and protein expression levels of Microphthalmia-associated transcriptian factor (MiTF), a critical transcription factor for tyrosinase gene expression, were also suppressed by undecylprodigiosin (1) treatment in B16 analyses. Collectively, our results suggest for the first time that undecylprodigiosin (1), a potent component isolated from an extract of marine Streptomyces sp. SNA-077, critically exerts the anti-melanogenic ability for melanin synthesis.

Inhibition of postharvest browning of white Hypsizygus marmoreus by LVEF-Vac: Evidence from phenolic metabolism and enzyme expression

A study was conducted to examine the effects of postharvest anti-browning of white Hypsizygus marmoreus and the enzymes related to it, utilizing the Low Voltage Electrostatic Field-Vacuum (LVEF-Vac, 150 V, 100 Hz, 26–36 kPa) treatment technology. The findings indicated that the application of LVEF-Vac treatment significantly extended the storage time of white Hypsizygus marmoreus to 14 d as compared to the control groups. Additionally, it successfully prevented the rise in color difference and browning degree, reduce them by 21.23 % and 36.62 %, respectively, while also inhibiting water loss and migration. Furthermore, it can impede the increase in total amino acid, tyrosine, and lysine content while maintaining a high proline and total phenols content of white Hypsizygus marmoreus during storage. At 9 d of storage, LVEF-vac treated laccase activity was reduced by 32.56 %, tyrosinase activity was reduced by 40.35 %, and gene expression of laccase and tyrosinase was reduced by 93.67 % and 48.77 %, respectively. Therefore, the discoloration of white Hypsizygus marmoreus during storage is slowed down, which improves its quality over time.

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.

The Antimelanogenic Activity of the Extract of Heukharang Lettuce (Lactuca sativa L.) Leaf

Heukharang (Lactuca sativa L.), the artificially developed lettuce cultivar for enhancement of lactucin content, exhibits antioxidant activities and sleep-promoting effects. However, potential of Heukharang as a raw material for the skin-whitening agent has not been investigated yet. This study evaluated the effects of Heukharang extract (HHE) on α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis in vitro and in vivo models. Our findings revealed that HHE (25–100 μg/mL) effectively inhibited α-MSH-induced melanin synthesis in both 2D and 3D cell culture environments without compromising the viability of the B16F10 murine melanoma cell line. Furthermore, HHE suppressed intracellular tyrosinase activity, along with both gene and protein expression of tyrosinase (TYR) and tyrosinase-related protein (TRP)-1 and TRP-2. HHE downregulated the mRNA level of microphthalmia-associated transcription factor (MITF) and the phosphorylation of cAMP response element-binding (CREB) protein. The antimelanogenic activity of HHE (50 and 100 μg/mL) was also confirmed using a zebrafish embryo model, highlighting its efficacy in inhibiting α-MSH-induced melanogenesis through the downregulating CREB/MITF/TYR signaling pathways. Moreover, our study demonstrated that a corresponding amount of lactucin (5–20 μM) to the HHE inhibited and regulated melanogenesis. These results collectively suggest that HHE, enriched with lactucin, holds promise as a potential skin-whitening agent for nutricosmetic industries.

Photobiomodulation for melasma treatment: Integrative review and state of the art.

Photobiomodulation therapy (PBM) is a versatile technique for treating skin diseases. Melasma, a chronic hyperpigmentation condition, has recently been associated with vascular features and dermal photoaging and poses significant management challenges. We review the recent literature on melasma etiology and the evidence supporting PBM as a therapeutic modality for melasma treatment. We conducted a comprehensive literature search in three different databases from May to August 2023, focusing on studies published in the past 10 years. The inclusion criteria comprised full-text studies investigating low-power lasers and/or light-emitting diodes (LEDs) in invitro or invivo models, as well as clinical trials. We excluded studies discussing alternative melasma therapies or lacking experimental data. We identified additional studies by searching the reference lists of the selected articles. We identified nine relevant studies. Clinical studies, in agreement with invitro experiments and animal models, suggest that PBM effectively reduces melasma-associated hyperpigmentation. Specific wavelengths (red: 630 nm; amber: 585 and 590 nm; infrared: 830 and 850 nm) at radiant exposures between 1 and 20 J/cm2 exert modulatory effects on tyrosinase activity, gene expression, and protein synthesis of melanocytic pathway components, and thus significantly reduce the melanin content. Additionally, PBM is effective in improving the dermal structure and reducing erythema and neovascularization, features recently identified as pathological components of melasma. PBM emerges as a promising, contemporary, and non-invasive procedure for treating melasma. Beyond its role in inhibiting melanogenesis, PBM shows potential in reducing erythema and vascularization and improving dermal conditions. However, robust and well-designed clinical trials are needed to determine optimal light parameters and to evaluate the effects of PBM on melasma thoroughly.

Effects of Water-Ethanol Extracts from Four Sphagnum Species on Gene Expression of Selected Enzymes in Normal Human Dermal Fibroblasts and Their Antioxidant Properties.

Mosses (Bryophyta), particularly species of the genus Sphagnum, which have been used for centuries for the treatment of skin diseases and damage, are still not explored enough in terms of their use in cosmetics. The purpose of this study was to determine the antioxidant properties of water-ethanol extracts from four selected species of the genus Sphagnum (S. girgenshonii Russow, S. magellanicum Brid., S. palustre L., and S. squarrosum Crome) and their impact on the expression of genes encoding key enzymes for the functioning of the skin. In this study, the effects of Sphagnum extracts on the expression of genes encoding tyrosinase, collagenase, elastase, hyaluronidase and hyaluronic acid synthase in human dermal fibroblasts were determined for the first time in vitro. The extracts inhibited tyrosinase gene expression and showed antioxidant activity. The experiment showed an increase in the expression of some genes encoding collagenase (MMP1) or hyaluronidase (HYAL2, HYAL3 and HYAL4) and a decrease in the hyaluronan synthase (HAS1, HAS2 and HAS3) genes expression by the tested extracts. The obtained results suggest that using extracts from the tested Sphagnum species in anti-aging cosmetics does not seem beneficial. Further studies are needed to clarify their impact on the skin.

Enhancement of Melanogenic Inhibitory Effects of the Leaf Skin Extracts of Aloe barbadensis Miller by the Fermentation Process

This work first showed that the skin-lightening effects of the leaf skin extracts of Aloe vera were significantly increased by the fermentation of Lactobacillus plantarum BN41. The fermented extract (BF) showed much higher antioxidant activities of DPPH scavenging effects and the reduction in intracellular ROS production than the water extract (BW), and even higher than Trolox as a positive control. High efficacy of the BF results was shown from the synergistic effects of higher elution of aloesin (2.96 ± 0.09 mg/g vs. 2.03 ± 0.02 mg/g in BF and BW, respectively) and bioactive substances from the fermentation processes. The inhibition of tyrosinase activities and melanin synthesis at 0.3% (w/v) optimal dosage of BF was much better than those of arbutin and aloesin, which are commercial skin-lightening ingredients. It was also first proved that BF effectively down-regulated all microphthalmia-associated transcription factors (MITF), tyrosinase-related protein-1 (TYRP-1) and TYRP-2, and tyrosinase (TYR) gene expression (p < 0.05), proposing melanogenesis inhibitory mechanism in the MITF/TYRP-1/TYRP-2/TYR pathway. However, aloesin and arbutin selectively suppressed the expression of TRYP-1, TRYP-2 or TYR. It was clearly demonstrated that the fermentation process reduces inherent cytotoxicity of aloe, showing much less cell cytotoxicity than BW. Conclusively, 0.3% (w/v) of the BF can be utilized as a competitive and sustainable natural skin-lightening ingredient.

Regulation of Tyrosinase Gene Expression by Retinoic Acid Pathway in the Pacific Oyster Crassostrea gigas.

Retinoic acid (RA) plays important roles in various biological processes in animals. RA signaling is mediated by two types of nuclear receptors, namely retinoic acid receptor (RAR) and retinoid x receptor (RXR), which regulate gene expression by binding to retinoic acid response elements (RAREs) in the promoters of target genes. Here, we explored the effect of all-trans retinoic acid (ATRA) on the Pacific oyster Crassostera gigas at the transcriptome level. A total of 586 differentially expressed genes (DEGs) were identified in C. gigas upon ATRA treatment, with 309 upregulated and 277 downregulated genes. Bioinformatic analysis revealed that ATRA affects the development, metabolism, reproduction, and immunity of C. gigas. Four tyrosinase genes, including Tyr-6 (LOC105331209), Tyr-9 (LOC105346503), Tyr-20 (LOC105330910), and Tyr-12 (LOC105320007), were upregulated by ATRA according to the transcriptome data and these results were verified by real-time quantitative polymerase chain reaction (RT-qPCR) analysis. In addition, increased expression of Tyr (a melanin-related TYR gene in C. gigas) and Tyr-2 were detected after ATRA treatment. The yeast one-hybrid assay revealed the DNA-binding activity of the RA receptors CgRAR and CgRXR, and the interaction of CgRAR with RARE present in the Tyr-2 promoter. These results provide evidence for the further studies on the role of ATRA and the mechanism of RA receptors in mollusks.

Expression of tyrosinase gene in gingiva: A pilot study.

Melanin is the predominant pigment responsible for the color of skin, hair, iris of eyes, and oral mucosa. Tyrosinase (TYR) is the key enzyme involved in melanin synthesis. Studies in dermatology have shown a positive correlation between TYR enzyme levels and melanin pigmentation of the skin. However, no study has been conducted to assess TYR levels in the gingiva. Hence the present study was conducted to assess TYR levels in gingival melanin hyperpigmentation. To assess the TYR gene expression in gingiva in individuals with moderate to severe gingival melanin hyperpigmentation. Subjects with a chief complaint of blackish appearance of gums with an unesthetic smile were included in the study. Informed consent was obtained. Scaling and root planning were done and subjects were recalled after 2 weeks. The gingival depigmentation procedure was performed using the conventional scalpel technique under adequate local anesthesia. The selected sites underwent conventional gingival depigmentation technique using Bard-Parker handle no: 3 and blade no: 11. The excised layer of epithelium along with a thin layer of underlying connective was sent to the laboratory to assess the TYR gene expression by real-time polymerase chain reaction technique. The levels of the TYR enzyme activity in the gingival tissues from the selected sites were assessed. Table 1 and Graph 1 show the levels of TYR enzyme gene expression in the gingival tissue. TYR gene expression and the degree of gingival melanin hyperpigmentation are positively correlated. Hence the assessment of TYR enzyme activity in gingiva could be of great value in today's cosmetologically conscious individuals.

Inhibitory activity of soybean (Glycine max L. Merr.) Cell Culture Extract on tyrosinase activity and melanin formation in alpha-melanocyte stimulating Hormone-Induced B16-F10 melanoma cells.

Hyperpigmentation, which causes excessive melanin synthesis and accumulation, is an important issue in the cosmetic industry. Since compounds developed against hyperpigmentation often come with side effects such as skin irritation and contact dermatitis, new studies focus on the use of natural agents that have no side effects. In this study, it was found that the effects of soybean cell culture extract (SCE) on alpha-melanocyte-stimulating hormone (α-MSH) induced melanogenesis in B16-F10 murine melanoma cells. The cells were incubated with SCE for 48h after treatment with α‑MSH for 24h to analysis the melanin content, cellular tyrosinase activity, and gene and protein expression. SCE at 1mg/mL decreased melanin content and tyrosinase activity by 34% and 24%, respectively, compared to the α-MSH-treated group, which did not decrease cell viability. In addition, SCE (1mg/mL) downregulated the expression of tyrosinase (TYR), tyrosinase-related protein (TRP)-1, tyrosinase-related protein (TRP)-2, and microphthalmia-associated transcription factor (MITF) genes 1.5-, 1.5-, 2-, and 2-fold, respectively. Furthermore, SCE inhibited the expression of TYR, TRP1, and TRP2 by decreasing the expression of MITF, as shown in a western blot assay. This study suggests that SCE reveals dose-dependent inhibition of melanin synthesis through the suppression of tyrosinase activity as well as molecular levels of TYR, TRP1, TRP2, and MITF in B16-F10 murine melanoma cells. Therefore, SCE has the potential to be an effective and natural skin-whitening agent for application in the cosmetic industry.

Persister state-directed transitioning and vulnerability in melanoma

Melanoma is a highly plastic tumor characterized by dynamic interconversion of different cell identities depending on the biological context. Melanoma cells with high expression of the H3K4 demethylase KDM5B (JARID1B) rest in a slow-cycling, yet reversible persister state. Over time, KDM5Bhigh cells can promote rapid tumor repopulation with equilibrated KDM5B expression heterogeneity. The cellular identity of KDM5Bhigh persister cells has not been studied so far, missing an important cell state-directed treatment opportunity in melanoma. Here, we have established a doxycycline-titratable system for genetic induction of permanent intratumor expression of KDM5B and screened for chemical agents that phenocopy this effect. Transcriptional profiling and cell functional assays confirmed that the dihydropyridine 2-phenoxyethyl 4-(2-fluorophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxylate (termed Cpd1) supports high KDM5B expression and directs melanoma cells towards differentiation along the melanocytic lineage and to cell cycle-arrest. The high KDM5B state additionally prevents cell proliferation through negative regulation of cytokinetic abscission. Moreover, treatment with Cpd1 promoted the expression of the melanocyte-specific tyrosinase gene specifically sensitizing melanoma cells for the tyrosinase-processed antifolate prodrug 3-O-(3,4,5-trimethoxybenzoyl)-(–)-epicatechin (TMECG). In summary, our study provides proof-of-concept for a dual hit strategy in melanoma, in which persister state-directed transitioning limits tumor plasticity and primes melanoma cells towards lineage-specific elimination.

Adenostemmoic acid B suppresses NO production by downregulating the expression and inhibiting the enzymatic activity of iNOS

Adenostemmoic acid B (AB) is a major compound found in Adenostemma lavenia ; it shows anti-melanogenic, anti-inflammatory, and cytotoxic activities. By modifying the 19th position (carboxy: involved in the avoidance of cytotoxicity) of AB, we succeed to separate these activities. Short-chain alkylation of the carboxy group enhanced anti-melanogenic activity, while long-chain alkylation (hydrophobic) resulted in the suppression of nitric oxide (NO) production and inducible NO synthase (iNOS) expression without anti-melanogenic activity. Re-modification of hydrophilic properties in these long-chain derivatives restored anti-melanogenic activity but did not suppress NO production. Unexpectedly, AB and derivatives with long chains linked by an anhydride bond were new iNOS inhibitors. These results suggest that AB modulates multiple physiological activities by regulating different targets, including iNOS. • Adenostemmoic acid B is a multipotential ingredient in Adenostemma lavenia. • Adenostemmoic acid B suppresses gene expression of tyrosinase (anti-melanogenesis) and iNOS (anti-inflammatory). • Adenostemmoic acid B and its derivatives with an anhydride bond inhibit iNOS enzyme activity.

Probiotic microbes: Are their anti-melanogenicity and longevity promoting activities closely linked through the major "pathogenic" kinase PAK1?

PAK1-deficient mutant of C. elegans lives 60% longer than the wild-type. Interestingly, PAK1-deficient mutant of melanocytes produces less melanin (only a half compared with the wild-type) in the presence of either serum (PDGF) or α-MSH (alpha-melanocyte stimulating hormone). These observations indicate that the major "pathogenic" kinase PAK1 is responsible for both shortening the healthy lifespan, and PDGF/α-MSH-dependent melanogenesis. For screening of PAK1-blocking probiotic bacteria or their products, their anti-melanogenic as well as longevity promoting properties were examined. Recently it was found that C. elegans fed with Lactobacillus rhamnosus in Xinjiang cheese lives 40% longer than the worm fed with the standard E. coli. Interestingly, a Chinese traditional medicine called "ChiBai" fermented with the Lactobacillus rhamnosus also inhibited the α-MSH-induced melanogenesis, and this bacteria itself produces butyric acid that blocks the oncogenic HDAC (histone deacetylase)-PAK1 signaling pathway. These findings strongly suggest, if not proven, that anti-melanogenic activity of Lactobacillus and many other probiotic bacteria might serve as a reliable indicator for their longevity promoting activity. In this context, a popular Japanese Lactobacillus-fermented milk drink called "Calpis", developed a century ago, and recently proven to inhibit the melanogenesis by suppressing the PAK1-dependent tyrosinase gene expression, may potentially prolong our healthy lifespan.

GIF-2209, an Oxindole Derivative, Accelerates Melanogenesis and Melanosome Secretion via the Modification of Lysosomes in B16F10 Mouse Melanoma Cells.

Melanogenesis and melanosome secretion are regulated by several mechanisms. In this study, we found that the oxindole derivative GIF-2209 accelerated melanogenesis associated with the discrimination in the expression and intracellular distributions of two melanogenic enzymes, tyrosinase (TYR) and tyrosinase-related protein-1 (TYRP-1). GIF-2209 upregulated the expression of TYR via a microphthalmia transcription factor (MITF)-independent mechanism, leading to high expression of protein. In contrast, GIF-2209 did not alter the mRNA levels of TYRP-1 and suppressed its protein levels. GIF-2209 induced the dissociation of TYR from TYRP-1 but did not alter the association between TYR and CD63, a melanosome and lysosome marker. The protein levels of CD63 were also upregulated by GIF-2209. GIF-2209 induced lysosome expansion and redistribution in all areas of the cytosol, accompanied by autophagy acceleration (upregulation of LC3BII protein levels and downregulation of p62 protein levels). In addition, GIF-2209 stimulated the secretion of melanosomes containing high levels of TYR, TYRP-1, and CD63 proteins. The GIF-2209 mediated melanosome secretion was sensitive to the lysosome inhibitor chloroquine. These results suggest that GIF-2209 may activate lysosomal functions with TYR gene expression, while it accelerates melanosome secretion, which finally leads to the depletion of intracellular melanogenic enzyme, especially TYRP-1 protein.

Melanogenesis Markers Expression in Premature Graying of Hair: A Cross-Sectional Study

Background: Studies on mice and aging human hair follicles provide compelling evidence that graying of hair results from premature differentiation of melanocyte stem cells in the niche/bulge. Objective: The aim of this study was to analyze whether differentiation of melanocyte stem cells is responsible for premature graying of hair (PGH). Methods: Twenty-five patients with PGH (n = 25) attending the dermatology department were recruited. Five unpigmented and 5 pigmented hairs were obtained per patient by separating individual follicles after 1 mm punch biopsies. The hairs were dissected at a distance of 2 mm from the bulb to separate the stem cells (upper segment – US) from the melanocytes (lower segment – LS). RNA was extracted from hair follicle US and LS, and expression of GP100, tyrosinase (TYR), and tyrosinase-related protein-1 (TYRP1) genes was quantified using Qiagen one-step RT-PCR kit. Results: We found melanogenesis gene expression in both temporary (US) and permanent (LS) segments of unpigmented and pigmented hair follicles. When compared between the US and LS of white hair, the expression of TYR and GP100 was much higher in US than LS, suggestive of melanogenesis in the bulge. Similarly, when compared between white and black US, the expression of all 3 genes was higher in white US than black US, although not statistically significant. Limitations: Low samples size and lack of data pertaining to the expression of genes at protein level are the limitations of current study. Conclusion: Even though this pilot study data yielded key information about the expression of GP100, TYR, and TYRP-1 at the mRNA level, further studies quantifying the expression of these genes at protein level are needed to provide additional clues to further address the results in detail.

Shell Biosynthesis and Pigmentation as Revealed by the Expression of Tyrosinase and Tyrosinase-like Protein Genes in Pacific Oyster (Crassostrea gigas) with Different Shell Colors.

The widely recognized color polymorphisms of molluscan shell have been appreciated for hundreds of years by collectors and scientists, while molecular mechanisms underlying shell pigmentation are still poorly understood. Tyrosinase is a key rate-limiting enzyme for the biosynthesis of melanin. Here, we performed an extensive multi-omics data mining and identified two tyrosinase genes, including tyrosinase and tyrosinase-like protein 2 (Tyr and Typ-2 respectively), in the Pacific oyster Crassostrea gigas, and investigated the expression patterns of tyrosinase during adults and embryogenesis in black and white shellcolor C. gigas. Tissue expression analysis showed that two tyrosinase genes were both specifically expressed in the mantle, and the expression levels of Tyr and Typ-2 in the edge mantle were significantly higher than that in the central mantle. Besides, Tyr and Typ-2 genes were black shell-specific compared with whiteshell oysters. In situ hybridization showed that strong signals for Tyr were detected in the inner surface of the outer fold, whereas positive signals for Typ-2 were mainly localized in the outer surface of the outer fold. In the embryos and larvae, the high expression of Tyr mRNA was detected in eyed-larvae, while Typ-2 mRNA was mainly expressed at the trochophore and early D-veliger. Furthermore, the tyrosinase activity in the edge mantle was significantly higher than that in the central mantle. These findings indicated that Tyr gene may be involved in shell pigmentation, and Typ-2 is more likely to play critical roles not only in the formation of shell prismatic layer but also in shell pigmentation. In particular, Typ-2 gene was likely to involve in the initial non-calcified shell of trochophores. The work provides valuable information for the molecular mechanism study of shell formation and pigmentation in C. gigas.

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.

The investigation on allelic, genotypic frequencies and gene expression study in coding region of tyrosinase gene in Deoni cattle breed of western India

An investigation was carried out on Deoni animals of western India to study the allelic and genotypic frequencies in coding region of TYR gene as well as gene expression profile. The animals were grouped according to age, gender, strain and intensity of partial albinism (low, medium and high). The present study revealed that the genotypic frequency of TYR gene across different strains, gender, age group and level of partial albinism was found to be non-significant for both exon-I and exon-II. The AB genotype in Balankya (0.70) was observed highest genotypic frequency followed by Wanera (0.55) and Shewara (0.55) strains. The genotypic frequency of AB and BB genotypes were observed highest in male and female, respectively. In exon-I, genotype frequency of AA genotype was found highest (0.55) in low level of partial albinism. The allelic frequencies in Shewara strain, male and low level of partial albinism were 0.75, 0.63 and 0.73, respectively. However, in exon-II genotype frequency of AB and BB was observed highest (0.70) in Wanera and Balankya strains followed by AA genotype in Shewara (0.50). The highest genotypic frequency of AA (0.87) and BB (0.50) were in male and female, respectively. The genotype frequency of AB genotype was found highest in all level of partial albinism. The allelic frequency was highest (0.85 for B allele) in Wanera strain, male (0.80 for A allele) and high level (0.60 for A allele) of particle albinism. The highly significant (p = 0.002) expression of tyrosinase gene was observed in young animals as compared to adult animals. The TYR gene expression was significantly (p = 0.047) higher in animals with low intensity of partial albinism followed by in the animals with medium and high intensity. Therefore, it is inferred that the TYR gene expression in young animals were high and as compared to the old animals of Deoni cattle breed.

Molecular and Biochemical Basis of Minocycline-Induced Hyperpigmentation-The Study on Normal Human Melanocytes Exposed to UVA and UVB Radiation.

Minocycline is a drug which induces skin hyperpigmentation. Its frequency reaches up to 50% of treated patients. The adverse effect diminishes the great therapeutic potential of minocycline, including antibacterial, neuroprotective, anti-inflammatory and anti-cancer actions. It is supposed that an elevated melanin level and drug accumulation in melanin-containing cells are related to skin hyperpigmentation. This study aimed to evaluate molecular and biochemical mechanism of minocycline-induced hyperpigmentation in human normal melanocytes, as well as the contribution of UV radiation to this side effect. The experiments involved the evaluation of cyto- and phototoxic potential of the drug using cell imaging with light and confocal microscopes as well as biochemical and molecular analysis of melanogenesis. We showed that minocycline induced melanin synthesis in epidermal melanocytes. The action was intensified by UV irradiation, especially with the UVB spectrum. Minocycline stimulated the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase (TYR) gene. Higher levels of melanin and increased activity of tyrosinase were also observed in treated cells. Moreover, minocycline triggered the supranuclear accumulation of tyrosinase, similar to UV radiation. The decreased level of premelanosome protein PMEL17 observed in all minocycline-treated cultures suggests disorder of the formation, maturation or distribution of melanosomes. The study revealed that minocycline itself was able to enhance melanin synthesis. The action was intensified by irradiation, especially with the UVB spectrum. Demonstrated results confirmed the potential role of melanin and UV radiation minocycline-induced skin hyperpigmentation.

Expression of histidine decarboxylase in melanocytes of the human skin

Histamine-producing cells include storage-type cells (e.g., mast cells and basophils), which store histamine intracellularly, and inducible-type cells (e.g., keratinocytes and macrophages), which induce histidine decarboxylase (HDC, a key enzyme for histamine biosynthesis) activity but do not have a storage pool of histamine. Most of the studies focused on identifying HDC-expressing cells by using cultured cells, and few on investigating the localization of HDC by using skin tissues. Hence, this study conducted immunohistochemical studies using human healthy skin samples. HDC-positive and cytokeratin 14 (a marker of basal keratinocytes)-negative cells were present around the basal layer of the epidermis. These cells did not immunohistochemically react with mast cell tryptase but expressed tyrosinase (a key enzyme for melanin biosynthesis) and microphthalmia-associated transcription factor (MITF, a transcription factor controlling the expression of tyrosinase genes). Melanin granules were clearly observed around HDC-positive and MITF-positive cells. Moreover, HDC mRNA and protein were both detected in cultured normal human epidermal melanocytes. In conclusion, HDC-positive and cytokeratin 14-negative cells around the basal layer of the epidermis are melanocytes.