Tyrosinase Gene Expression Research Articles

Enhancement of gene expression and melanin production of human tyrosinase gene loaded in elastic cationic niosomes

Disturbance in the synthesis of tyrosinase might be one of the major causes of vitiligo. The enhancement of tyrosinase gene expression and melanin production by loading the plasmid in elastic cationic niosomes was investigated in tyrosinase gene knocked out human melanoma (M5) cells and in tyrosine-producing mouse melanoma (B(16) F(10) ) cells. Niosomes composed of Tween 61/cholesterol/dimethyl dioctadecyl ammonium bromide at 1:1:0.5 molar ratio were prepared by the freeze-dried empty liposomes method. The thin lipid film was redissolved in distilled water or 25% ethanol to obtain the non-elastic or elastic cationic niosomes, respectively. The maximum loading of the plasmid in non-elastic and elastic niosomes was 130 and 100 µg per 16 mg of the niosomal contents, respectively. The plasmid-loaded elastic cationic niosomes exhibited high specific tyrosinase activity of 1.66 and 1.50 fold in M5 cells and 6.81 and 4.37 fold in B(16) F(10) cells compared with the free plasmid and the plasmid-loaded non-elastic cationic niosomes, respectively. This study has demonstrated not only the enhancement of the expression of human tyrosinase gene by loading in elastic cationic niosomes, but also the potential application of this gene delivery system for the further development of vitiligo gene therapy.

Microphthalmia-associated transcription factor modulates expression of NADPH oxidase type 4: A negative regulator of melanogenesis

How signaling via reactive oxygen species (ROS) influences skin pigmentation is unclear. We have investigated how NADPH oxidase-derived ROS modulates the expression of the key pigment “melanin” synthesizing enzymes in B16 mouse melanoma cells. A melanin inducer α-melanocyte-stimulating hormone (α-MSH) caused ROS generation that was inhibited by the NADPH oxidase inhibitor Diphenyleneiodonium (DPI) and was insensitive to antagonists of other ROS-producing enzyme systems including mitochondrial enzymes, cycloxygenase, and xanthine oxidase. NADPH oxidase 4 (Nox4) was found to be the most abundant isoform expressed in B16 cells, and its gene levels, as well as ROS generation, were enhanced by α-MSH. Interestingly, silencing Nox4 gene expression with Nox4 siRNA augmented melanin formation under basal conditions and after α-MSH stimulation, demonstrating that constitutive or stimulated Nox4-dependent ROS inhibits melanin formation. This process may be mediated by targeting the promoter region of a melanin synthesizing enzyme tyrosinase, because Nox4 siRNA enhanced tyrosinase promoter activity. Moreover, inhibition of tyrosinase mRNA expression in Nox4 siRNA-treated cells by blocking de novo mRNA and protein synthesis with actinomycin D and cycloheximide respectively indicates that Nox4 repression induces melanogenesis by increasing tyrosinase gene expression. We also found that α-MSH activated its downstream signal transducer microphthalmia-associated transcription factor (MITF) to stimulate Nox4 gene expression. We thus identified a novel mechanism by MITF signaling that in turn stimulates Nox4 to drive ROS generation, thereby repressing melanin synthesis. Such sequence of actions appears to act as an internal feedback mechanism to fine-tune melanin synthesis in response to exogenous challenges such as UV radiation.

Analysis of tyrosinase gene and tissue expression in five different strains of Koi carp (Cyprinus carpioKoi)

Black is an important body color of Koi(Cyprinus carpio Koi) which is performed through melanin synthesized by melanocyte,and tyrosinase is an important rate-limiting enzyme in melanin synthesis.It's unclear of genetic mechanism of Koi body color.The present work obtained Koi tyrosinase(Tyr) gene sequence and investigated the expression of Tyr gene in different strains and tissues using semi-quantitative PCR,trying to reveal the relationship between the pigment control genes and the body color.The results showed 1 779 bp of Tyr gene,including a 1 608 bp open reading frame encoding 535 amino acids.Sequence analysis of cDNA and protein and phylogenetic analysis indicated that conservation of Tyr is higher in teleost than between teleost and other vertebrates.Semi-quantitative analysis showed the highest Tyr expression in the eye and black skin,intermediate in brain,red and yellow skin,and the lowest in liver and heart.There was no significant difference of Tyr expression between the same tissues of eyes,liver,heart,brain from different Koi carps,but differentiated in the skins with the highest in black skin,followed by red and yellow skin and small amount in white skin.The different expression was related to tissue function.The role of tyrosinase in non-melanoma cells was unclear.There possibly exist multiple forms of tyrosinase,some of which is inhibited,or the xanthophores and erythrophores could be translated into functional melanocytes.

Mangosteen leaf extract increases melanogenesis in B16F1 melanoma cells by stimulating tyrosinase activity in vitro and by up-regulating tyrosinase gene expression

Melanin synthesis is stimulated by various effectors, including α-melanocyte stimulating hormone (α-MSH), cyclic AMP (cAMP)-elevating agents (forskolin, isobutylmethylxantine, glycyrrhizin) and ultraviolet light. Our investigation focused on the identification of the melanogenic efficacy of mangosteen (Garcinia mangostana) leaf extract with regard to its effects on melanogenesis in B16F1 melanoma cells, since it has been known to possess strong anti-oxidant activities. The mangosteen leaf extract was found to stimulate melanin synthesis and tyrosinase activity in a dose-dependent manner without any significant effects on cell proliferation. Cytotoxicity of the extract was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; the highest concentration of the extract that did not affect cell viability was 32 µg/ml. Formation of melanin from cultured B16F1 melanoma induced by extract treatment was estimated using spectrophotometry. In order to clarify the subsequent mechanism of tyrosinase activation by the extract, the levels of tyrosinase expression in B16F1 melanoma were examined using an intracellular tyrosinase assay and tyrosinase zymography. Up-regulation of intracellular tyrosinase expression seemed to correlate with an increase in microphtalmia-associated transcription factor (MITF) protein levels since MITF is the key factor for genes involved in melanogenesis. Both of the results showed that tyrosinase activity was markedly enhanced from extract-treated cells. The overall results suggest that mangosteen leaf extract may be a promising candidate for the treatment of hypopigmentation disorder and useful for self-tanning cosmetic products.

Effect of saucerneol D on melanin production in cAMP-elevated melanocytes

Intracellular cAMP stimulates microphthalmia-associated transcription factor (MITF) induction in melanocytes through cAMP-responsive element binding protein (CREB), which plays a pivotal role in the gene expression of tyrosinase for melanin biosynthesis. In the present study, saucerneol D as a lignan constituent of Saururus chinensis (Saururaceae family) efficiently inhibited melanin production with IC(50) values of 188-297 nM in B16 melanoma cells stimulated with α-melanocyte stimulating hormone (α-MSH) or other cAMP elevators. Moreover, saucerneol D down-regulated α-MSH-induced gene expression of tyrosinase at the transcription level in B16 cells, but it did not directly inhibit the catalytic activity of cell-free tyrosinase. As to the molecular basis of hypopigmenting action, saucerneol D inhibited α-MSH-induced phosphorylation of CREB in the cells, and sequentially suppressed MITF induction. Taken together, this study provides saucerneol D down-regulated the gene expression of tyrosinase, resulting in the inhibition of cAMP-induced melanin biosynthesis, and suggests pharmacological potential of the lignan structure in skin hyperpigmentation.

Dual inhibitions of lemon balm (Melissa officinalis) ethanolic extract on melanogenesis in B16-F1 murine melanocytes: Inhibition of tyrosinase activity and its gene expression

The effects of wild type and UV-irradiated lemon balm (Melissa officinalis) ethanolic extracts (MOE and UMOE) on melanogenesis in vitro were examined. UMOE showed potent antioxidant activity and significantly inhibited the mushroom and melanocyte tyrosinase activity, and lowered cellular melanin content by 49% at 200 μg/mL in B16-F1 melanocytes. The key gene and protein expression of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were reduced (−73% for TRP-1 protein at 200 μg/mL UMOE, p<0.05). MOE showed similar results to a slightly lesser degree. We found that myo-inositol, a major compound in lemon balm extracts, significantly reduced cellular melanin synthesis and its effect was greater than arbutin at 1 mM. These suggest that both MOE and UMOE have anti-melanogenic role by both direct inhibition of tyrosinase and down-regulation of gene expressions in melanogenesis. UV-irradiation slightly improved the anti-melanogenic activities. UMOE may be useful as natural anti-melanogenic biomaterials for functional foods and cosmetics.

Evaluation of in Vitro and in Vivo Depigmenting Activity of Raspberry Ketone from Rheum officinale

Melanogenesis inhibition by raspberry ketone (RK) from Rheum officinale was investigated both in vitro in cultivated murine B16 melanoma cells and in vivo in zebrafish and mice. In B16 cells, RK inhibited melanogenesis through a post-transcriptional regulation of tyrosinase gene expression, which resulted in down regulation of both cellular tyrosinase activity and the amount of tyrosinase protein, while the level of tyrosinase mRNA transcription was not affected. In zebrafish, RK also inhibited melanogenesis by reduction of tyrosinase activity. In mice, application of a 0.2% or 2% gel preparation of RK applied to mouse skin significantly increased the degree of skin whitening within one week of treatment. In contrast to the widely used flavoring properties of RK in perfumery and cosmetics, the skin-whitening potency of RK has been demonstrated in the present study. Based on our findings reported here, RK would appear to have high potential for use in the cosmetics industry.

Aromatic-turmerone inhibits α-MSH and IBMX-induced melanogenesis by inactivating CREB and MITF signaling pathways

This study investigated the anti-melanogenic effect of aromatic (ar)-turmerone on alpha-melanocyte stimulating hormone (α-MSH) and 3-isobuty-1-methxlzanthine (IBMX)-induced tyrosinase (Tyr), tyrosinase-related protein 1 (TRP-1), and tyrosinase-related protein 2 (TRP-2) expression in B16F10 melanoma cells. We demonstrated that ar-turmerone inhibits α-MSH and IBMX-induced melanin synthesis and tyrosinase activity. Data also showed that ar-turmerone inhibits the expression of tyrosinase, TRP-1, and TRP-2 in α-MSH- and IBMX-stimulated B16F10 cells. In addition, ar-turmerone exhibits stronger anti-melanogenic effects than curcumin. Furthermore, ar-turmerone strongly inhibited α-MSH- and IBMX-induced microphthalmia-associated transcription factor by suppressing the activity of cyclic adenosine monophosphate (cAMP)-responsive element binding protein in α-MSH-stimulated B16F10 cells. Our data revealed that ar-turmerone is a novel, effective, anti-melanogenic agent that functions by downregulating tyrosinase, Trp-1, and Trp-2 gene expression. Therefore, ar-turmerone may be a useful therapeutic agent for treating hyperpigmentation disorders, such as freckles and melasma, and as a beneficial additive in whitening cosmetics.

Manassantin A inhibits cAMP‐induced melanin production by down‐regulating the gene expressions of MITF and tyrosinase in melanocytes

Microphthalmia-associated transcription factor (MITF) is inducible in response to cAMP through the cAMP-responsive element-binding protein (CREB) and plays a pivotal role in the melanocyte-specific expression of tyrosinase or tyrosinase-related proteins (TRPs) for melanin biosynthesis. Manassantin A from Saururus chinensis inhibits cAMP-induced melanin production in B16 melanoma cells. Here, we focused on molecular basis of the antimelanogenic activity. Manassantin A consistently inhibited the cAMP elevator 3-isobutyl-1-methylxanthine (IBMX)- or dibutyryl cAMP-induced melanin production in B16 cells or in melan-a melanocytes by down-regulating the expression of tyrosinase or TRP1 gene. Moreover, manassantin A suppressed MITF induction through IBMX-activated CREB pathway, directly inhibiting the Ser-133 phosphorylation of CREB. However, manassantin A did not affect IBMX-increased cAMP levels in these cells but also other cAMP-dependent melanogenic pathways through post-translational modifications of MITF. This putative molecular mechanism of manassantin A in the inhibition of melanin production suggests its pharmacological potential in skin hyperpigmentation.

Nitric oxide enhances melanogenesis of alpaca skin melanocytes in vitro by activating the MITF phosphorylation

Ultraviolet (UV) B radiation can cause skin-tanning via the synthesis of melanin which is synthesized by specific tyrosinase and tyrosinase-related enzymes expressed in melanocytes. It is reported that several melanogenic factors are released from keratinocytes and other cells surrounding melanocytes in the skin following UV radiation. Some of them are reported to up-regulate tyrosinase gene expression through a different pathway, but most regulate tyrosinase via microphthalmia-associated transcription factor (MITF). It is unknown whether an NO-induced pathway regulates melanogenesis via MITF in vitro. In this study, we investigated this problem because it is important for our understanding of how to enhance the coat color of alpaca. We set up three groups for experiments using alpaca melanocytes: the control cultures were allowed a total of 5 days growth; the UV group cultures were also allowed 5 days of growth like the control group, but were then irradiated once everyday with 312 mJ/cm(2) of UVB; the UV + L-NAME group was the same as the UV group, but with the addition of 300 μM L-NAME every 6 h. To determine the NO inhibition effect, NO product was measured. To determine the effect of NO on MITF, the expression levels of the MITF gene and protein were measured by immunofluorescence, quantitative real-time PCR and western immunoblotting. To determine the influence of NO on MITF phosphorylation, phosphorylated MITF protein (p-MITF) was measured by western immunoblotting. To determine the effect of NO on melanogenesis, the melanin content was measured. The results provide exciting new evidence that NO can enhance melanogenesis in alpaca skin melanocytes by stimulating MITF phosphorylation.

The Effect of Epimedium koreanum Water Extract on the Enzymes and Factor Relevant to Melanin synthesis in Vitro Test

This study was conducted to evaluate the promoting effects of Epimedium koreanum water extract (EKWE) on the enzymes and factor relevant to melanin synthesis using enzyme activity, RT-PCR and Western blotting assays in melan-a cells. Intra-cellular tyrosinase activities of EKWE were higher as 3.9%, 9.2% (p⁄0.01), 13.0% (p⁄0.001), and 16.9% (p⁄0.001) at concentrations of 1.563, 3.125, 6.25, and 12.5 μg/mL, respectively, than the control group. Cell-extracted tyrosinase activities of EKWE were higher as 5.8%, 10.4% (p⁄0.01), 14.2% (p⁄0.01), and 24.1% (p⁄0.001) at concentrations of 1.563, 3.125, 6.25, and 12.5 μg/mL, respectively, than the control group. EKWE showed a promoting effect on tyrosinase activity. In Western blotting assay, EKWE significantly increased the protein expression of tyrosinase and TRP-2. In RT-PCR assay, EKWE significantly increased gene expression of tyrosinase, TRP-1 and MITF-M. In conclusion, EKWE has the promoting effect on the tyrosinase activity that is resulted from the up-regulation of its protein and gene expression.

Melanogenesis inhibition by a crude extract of Magnolia officinalis

In the present study, we investigated the inhibitory effect of a crude extract from Magnolia officinalis (MOE) on melanogenesis in both mouse B16 melanoma cells and zebrafish. Our results showed that MOE inhibited melanogenesis in either a-melanocyte stimulating hormone (a-MSH)- or 3-isobutyl-1-methylxanthin (IBMX)-stimulated B16 cells in a dose-dependent manner with an IC50 value of 9.3 µg/ml. In addition, MOE also inhibited cellular tyrosinase activity with an IC50 value of 13.4 µg/ml while no inhibitory activity was found by MOE against cell-free tyrosinase activity. Moreover, western blotting and real time reverse-transcription polymerase chain reaction (qRT-PCR) analyses, respectively confirmed that MOE downregulated levels of tyrosinase protein but not that of its mRNA in a-MSH-stimulated B16 cells. These results demonstrated that MOE inhibits melanogenesis of B16 cells by a pre-translational regulation on tyrosinase gene expression. On the other hand, when using zebrafish as a depigmenting assay system, MOE could inhibit both melanogenesis and tyrosinase activity in the in vivo model. From the present study, MOE was proven to be a good candidate as a skin-whitening agent for treatment of skin hyperpigmentation. Key words: Magnolia officinalis, melanogenesis, tyrosinase, melanin, inhibition.

Evaluation of RPE65, CRALBP, VEGF, CD68, and Tyrosinase Gene Expression in Human Retinal Pigment Epithelial Cells Cultured on Amniotic Membrane

The retinal pigment epithelium (RPE) plays a key role in the maintenance of the normal functions of the retina. Tissue engineering using amniotic membrane as a substrate to culture RPE cells may provide a promising new strategy to replace damaged RPE. We established a method of culturing RPE cells over the amniotic membrane as a support for their growth and transplantation. The transcription of specific genes involved in cellular function of native RPE, including RPE65, CRALBP, VEGF, CD68, and tyrosinase, were then measured using quantitative real-time PCR. Data showed a considerable increase in transcription of RPE65, CD68, and VEGF in RPE cells cultured on amniotic membrane. The amounts of CRALBP and tyrosinase transcripts were not affected. This may simply indicate that amniotic membrane restricted dedifferentiation of RPE cells in culture. The results suggest that amniotic membrane may be considered as an elective biological substrate for RPE cell culture.

Antimelanogenic effect of c-phycocyanin through modulation of tyrosinase expression by upregulation of ERK and downregulation of p38 MAPK signaling pathways

BackgroundPigmentation is one of the essential defense mechanisms against oxidative stress or UV irradiation; however, abnormal hyperpigmentation in human skin may pose a serious aesthetic problem. C-phycocyanin (Cpc) is a phycobiliprotein from spirulina and functions as an antioxidant and a light harvesting protein. Though it is known that spirulina has been used to reduce hyperpigmentation, little literature addresses the antimelanogenic mechanism of Cpc. Herein, we investigated the rationale for the Cpc-induced inhibitory mechanism on melanin synthesis in B16F10 melanoma cells.MethodsCpc-induced inhibitory effects on melanin synthesis and tyrosinase expression were evaluated. The activity of MAPK pathways-associated molecules such as MAPK/ERK and p38 MAPK, were also examined to explore Cpc-induced antimelanogenic mechanisms. Additionally, the intracellular localization of Cpc was investigated by confocal microscopic analysis to observe the migration of Cpc.ResultsCpc significantly (P < 0.05) reduced both tyrosinase activity and melanin production in a dose-dependent manner. This phycobiliprotein elevated the abundance of intracellular cAMP leading to the promotion of downstream ERK1/2 phosphorylation and the subsequent MITF (the transcription factor of tyrosinase) degradation. Further, Cpc also suppressed the activation of p38 causing the consequent disturbed activation of CREB (the transcription factor of MITF). As a result, Cpc negatively regulated tyrosinase gene expression resulting in the suppression of melanin synthesis. Moreover, the entry of Cpc into B16F10 cells was revealed by confocal immunofluorescence localization and immunoblot analysis.ConclusionsCpc exerted dual antimelanogenic mechanisms by upregulation of MAPK/ERK-dependent degradation of MITF and downregulation of p38 MAPK-regulated CREB activation to modulate melanin formation. Cpc may have potential applications in biomedicine, food, and cosmetic industries.

Tyrosinase Small Interfering RNA Effectively Suppresses Tyrosinase Gene Expression In Vitro and In Vivo

Tyrosinase is a bifunctional enzyme which oxidizes the initial step of melanin biosynthesis, that is, conversion of tyrosine to dopa and subsequently dopa to dopaquinone. It is a glycosylated protein and a major regulator of melanogenesis. To date, many approaches have been tried to regulate tyrosinase activity and melanin content. To that end, we screened small interfering RNA sequences for sequence-inhibited tyrosinase expression in B16 cells and in C57BL/6 mice. We analyzed tyrosinase mRNA levels by quantitative real-time PCR and determined tyrosinase activity and melanin content at 24, 48, and 72 hours after transfection. Results showed that siNM_011661_001 was the most efficient small interfering RNA sequence in suppressing tyrosinase mRNA expression, and cells transfected with this sequence showed lower tyrosinase activity. Moreover, intravitreous injection of siNM_011661_001 in C57BL/6 mice induced an efficient and stable gene-specific inhibition of expression at the posttranscriptional level.

Ficus deltoidea (Mas cotek) extract exerted anti-melanogenic activity by preventing tyrosinase activity in vitro and by suppressing tyrosinase gene expression in B16F1 melanoma cells

Ficus deltoidea (Mas cotek) water extract has been widely used for woman health in Malaysia. Our investigation focused to identify anti-melanogenic efficacy of F. deltoidea since it has been known to have strong anti-oxidant activities. Anti-melanogenic effect of F. deltoidea extract was analyzed using cultured B16F1 melanoma cells. Cytotoxicity of the extract was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and determined the highest concentration of the extract that did not affect cell viability as 0.1% (w/v). α-MSH-induced melanin synthesis was significantly inhibited with dose-dependent manner by treatment of F. deltoidea leave extract, which was comparable to that of kojic acid. The extract directly inhibited mushroom tyrosinase activity and intracellular tyrosinase activity of B16F1 as well. The inhibition of intracellular tyrosinase activity was found to be exerted at the protein expression level when analyzed by immunoblot and tyrosinase zymography. The expression of microphthalmia-associated transcription factor (MITF) was also reduced by the F. deltoidea extract. In conclusion, F. deltoidea extract has strong anti-melanogenic activity that is exerted by direct inhibition of tyrosinase enzyme activity and by down-regulation of the expression of genes involved in the melanogenesis pathways. Collectively, data shown in this study strongly suggest that F. deltoidea extract has potential to be used as a novel depigmenting agent for cosmetics.

Enhancement of Transdermal Absorption, Gene Expression and Stability of Tyrosinase Plasmid (pMEL34)-Loaded Elastic Cationic Niosomes: Potential Application in Vitiligo Treatment

The pMEL34 was loaded in elastic cationic niosomes (Tween61/Cholesterol/DDAB at 1:1:0.5 molar ratio) by chloroform film method with sonication and rehydrated with 25% ethanol. The amount of pMEL34 was determined by gel electrophoresis and gel documentation. The maximum loading of pMEL34 in elastic cationic niosomes was 150 microg/16 mg of the niosomal compositions. At 8 weeks, the remaining plasmid in the elastic niosomes kept at 4 +/- 2 degrees C, 27 +/- 2 degrees C were 49.75% and 38.57%, respectively, whereas at 45 +/- 2 degrees C, all plasmids were degraded. For transdermal absorption through rat skin investigated by Franz diffusion cells at 6 h, the fluxes of pMEL34 loaded in elastic and nonelastic niosomes in viable epidermis and dermis (VED) were 0.022 +/- 0.00 and 0.017 +/- 0.01 microg/cm(2)/h, respectively, whereas only pMEL34 loaded in elastic cationic noisome was observed in the receiver solution. The pMEL34 loaded in elastic cationic niosomes showed the highest tyrosinase gene expression demonstrating higher tyrosinase activity than the free and the loaded plasmid in nonelastic niosomes of about four times. This study has suggested the potential application of elastic cationic niosomes as an efficient topical delivery for tyrosinase gene in vitiligo therapy.

Melanogenesis inhibitory effect of dehydroevodiamine isolated from fruits of Evodia rutaecarpa

Dehydroevodiamine, an alkaloid, was isolated from the fruit of Evodia rutaecarpa and melanin production, and tyrosinase inhibition in B16F10 melanoma cells treated with the isolated dehydroevodiamine was investigated. The compound decreased melanin synthesis significantly without promoting cytotoxicity. The IC50 value of dehydro- evodiamine for melanogenesis and cell viability were 59.8 µM and 90.0 µM, respectively. The L-dopa oxidase activity of mushroom tyrosinase was reduced after dehydroevodiamine treatment by about 22.4% at a concentration of 33.2 µM. However, there was no effect on cellular tyrosinase activity. These results indicate that the observed decrease in melanin content after treatment with dehydroevodiamine was attributed to the direct inhibition of tyrosinase activity, rather than the suppression of tyrosinase gene expression. Dehydroevodiamine may be a promising new agent for use in cosmeceutical application.

Sulforaphane Inhibited Melanin Synthesis by Regulating Tyrosinase Gene Expression in B16 Mouse Melanoma Cells

Sulforaphane is a compound widely present in consumed vegetables, particularly broccoli. Previous studies have demonstrated that sulforaphane has many physiological effects including anti-cancer, anti-oxidation, and detoxification. In this study, we found that sulforaphane inhibited melanogenesis and tyrosinase expression. The inhibitory effect of 5 microM sulforaphane on melanogenesis was determined to be equivalent to that of 100 microM arbutin. In addition, sulforaphane induced phosphorylated extracellular signal-regulated kinase (ERK) and inhibited phosphorylated p38. It has been reported that the phosphorylated mitogen-activated protein (MAP) kinase family (ERK and p38) controls tyrosinase expression. Our data indicate that sulforaphane inhibited melanogenesis and tyrosinase expression by affecting the phosphorylated MAP kinase family. These findings indicate that sulforaphane might be an effective skin-whitening agent.

Hairpin DNA coated gold nanoparticles as intracellular mRNA probes for the detection of tyrosinase gene expression in melanoma cells

A new intracellular mRNA imaging probe has been developed that incorporates thiol-terminated hairpin oligonucleotides covalently bound to the surface of citrate-capped gold nanoparticles. The hairpin DNA-coated gold nanoparticles (hAuNPs) positively identifies tyrosinase mRNA in cultured melanoma cells.