MITF Research Articles

Pueraria protein extract inhibits melanogenesis and promotes melanoma cell apoptosis through the regulation of MITF and mitochondrial‑related pathways.

PuerariaLobata Radix (P.Lobata Radix) is an edible traditional Chinese medicine that contains various active compounds. Proteins from P.Lobata Radix have become the subject of increased interest in recent years. In evaluating the whitening effect on the skin, the present study found that the P.Lobata Radix water‑soluble total protein extract (PLP) had the strongest inhibitory effect on tyrosinase activity. In the present study, the anti‑melanogenic effect of PLP and the inhibitory effect on B16 melanoma cells were investigated. PLP significantly reduced the tyrosinase activity and melanin content in B16 melanoma cells. Mechanistically, PLP inhibited melanogenesis by decreasing the expression of tyrosinase, tyrosinase‑related protein (TRP)‑1 and TRP‑2 through downregulation of the microphthalmia‑associated transcription factor (MITF) gene, which was mediated by inhibition of p38 mitogen‑activated protein kinase signaling. In addition, PLP inhibited cell viability and triggered apoptosis of B16 cells in a dose‑dependent manner. Exposure to PLP reduced the mitochondrial membrane potential (MMP) and decreased ATP generation, leading to mitochondria‑related apoptosis of B16 melanoma cells. The expression levels of succinate dehydrogenase (SDH) and its two related subunits (SDHA and SDHB) were downregulated significantly by PLP, which may be associated with the regulation of mitochondrial energy metabolism by PLP. These results may explain why MMP collapse and reduced ATP generation were observed in B16 melanoma cells treated with PLP. Finally, the present study demonstrated that the inhibition of melanin synthesis by PLP was correlated with the regulation of antioxidant enzymes to reduce reactive oxygen species levels. These results suggested that PLP inhibits melanogenesis by downregulating the expression of MITF‑related melanogenic enzymes and triggering apoptosis through mitochondria‑related pathways.

Effects of MITF on marker protein expression of multivesicular bodies and miRNA omics of extracellular vesicles of mice melanocyte cell line

Extracellular vesicles (EVs) are heterogeneous membrane-bound complexes of cell-derived and nanosized structures originating from the endosomal system and subsequently released from the plasma membrane. EVs contribute significantly to intercellular communication and are involved in pigmentation processes that rely on tight communication between keratinocytes and melanocytes in the epidermis. Microphthalmia-associated transcription factor (MITF) induces melanogenesis and modulates the expression factors involved in melanosome biogenesis, maturation and dispersal in melanocytes. Here, we evaluated the effects of MITF on the fate of multivesicular bodies and the biogenesis of extracellular vesicles of melanocytes. It was found that MITF increased the expression of subunits of the endosomal sorting complex, required for transport (ESCRT), including VPS37, VPS36B, and tetraspanin CD81, which are key mediators of multivesicular body biogenesis. Over 110 miRNAs, including miR-211–5p, miR-335–5p, let-7g-5p and miR-28a-3p, were differentially expressed in melanocyte-derived EVs after overexpression of MITF in melanocytes. These miRNAs have been reported to be key regulators of plasma protein binding, changes in the cell membrane system and transferase activity. These results suggest that while enhancing melanogenesis, melanocytes may mediate intercellular communication with surrounding cells by serving as EV delivery vehicles.

Effects of polystyrene nanoplastics on melanin interference toxicity and transgenerational toxicity of ethylhexyl salicylate based on DNA methylation sequencing

Organic ultraviolet filters (OUVFs) are new hydrophobic organic pollutants in the aquatic environment. When ingested by aquatic organisms, OUVFs can induce a variety of toxic effects in organisms and be transferred to offspring. However, as the main active ingredient in sunscreens, OUVFs have rarely been investigated for their melanin interference toxicity or transgenerational toxic effects on aquatic organisms and their interactive toxic effects with nanoplastics (NPs). Here, we show the mechanism by which OUVFs interfere with melanogenesis in parental or offspring zebrafish and the effect of polystyrene (PS) NPs on the melanin-interference effect of OUVFs. We found that EHS induced significant enrichment of the melanogenesis pathway, inhibited the expression of the key melanin gene microphthalmia-associated transcription factor a (mitfa) and induced the mitf tyrosinase (tyr)-dopachrome tautomerase (dct)-tyrosinase related protein 1 (tyrp1) signaling cascade in parents, which ultimately induced a decrease in melanin content. After reproduction, transgenerational melanin interference effects of EHS may occur through the maternal inheritance of mitfa. Coexisting PS-NPs may inhibit the melanin interference toxicity or transgenerational toxicity of EHS by reducing ultraviolet irritation to the skin through adsorption of EHS. Our results demonstrate the ecotoxic potential of OUVFs in terms of melanin interference and the interference of PS-NP carrier effects on the toxicity of OUVFs. We anticipate that our assay will contribute to the assessment of the toxic effects of OUVFs and provide a basis for the interactive ecotoxicity assessment of PS-NPs and hydrophobic organic pollutants.

Design and Synthesis of (Z)-2-(Benzylamino)-5-benzylidenethiazol-4(5H)-one Derivatives as Tyrosinase Inhibitors and Their Anti-Melanogenic and Antioxidant Effects.

In this study, (Z)-2-(benzylamino)-5-benzylidenethiazol-4(5H)-one (BABT) derivatives were designed as tyrosinase inhibitors based on the structure of MHY2081, using a simplified approach. Of the 14 BABT derivatives synthesized, two derivatives ((Z)-2-(benzylamino)-5-(3-hydroxy-4-methoxybenzylidene)thiazol-4(5H)-one [7] and (Z)-2-(benzylamino)-5-(2,4-dihydroxybenzylidene)thiazol-4(5H)-one [8]) showed more potent mushroom tyrosinase inhibitory activities than kojic acid, regardless of the substrate used; in particular, compound 8 was 106-fold more potent than kojic acid when l-tyrosine was used as the substrate. Analysis of Lineweaver-Burk plots for 7 and 8 indicated that they were competitive inhibitors, which was confirmed via in silico docking. In experiments using B16F10 cells, 8 exerted a greater ability to inhibit melanin production than kojic acid, and it inhibited cellular tyrosinase activity in a concentration-dependent manner, indicating that the anti-melanogenic effect of 8 is attributable to its ability to inhibit tyrosinase. In addition, 8 exhibited strong antioxidant activity to scavenge 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals and peroxynitrite and inhibited the expression of melanogenesis-associated proteins (tyrosinase and microphthalmia-associated transcription factor). These results suggest that BABT derivative 8 is a promising candidate for the treatment of hyperpigmentation-related diseases, owing to its inhibition of melanogenesis-associated protein expression, direct tyrosinase inhibition, and antioxidant activity.

Protopanaxadiol-Enriched Rice Extracts Suppressed Oxidative and Melanogenic Activities in Melan-a Cells.

Concerns about hyperpigmentation and skin appearance have led to increasing research into the prevention and altering of skin pigmentation. Natural compounds may be of interest in the search for skin-lightening actives. Protopanaxadiol (PPD), a gut microbiome-induced ginseng metabolite, has been reported to have anti-melanogenic effects. This study aimed to evaluate the antioxidative and anti-melanogenic effects of PPD-enriched rice seed extracts on melan-a cells. The antioxidant and cytotoxicity activities of the extracts were investigated in melan-a cells before measuring their responses to melanogenic activities. The extracts significantly enhanced the antioxidant potency compared with normal rice seed extract. PPD-enriched rice seed extracts (i) significantly downregulated microphthalmia-associated transcription factor, which led to a reduction in tyrosinase and tyrosinase-related protein-1 and -2, (ii) decrease in the cellular tyrosinase activity and melanin content, (iii) reduction in the number of melanin-containing cells, (iv) promotion of melanogenesis downregulators, phosphorylation of extracellular signal-regulated kinase 1/2 and protein kinase B, and (v) downregulation of the phosphorylated p38 mitogen-activated protein kinase and melanin synthesis. These results indicate the feasibility of PPD-enriched rice seed extracts as a novel agent for suppressing melanogenesis and controlling hyperpigmentation.

In Silico Study of Naringenin as Melanogenesis Inducer in Vitiligo

Introduction: Vitiligo is a pigmentation disorder characterized by loss of skin color (depigmentation) due to melanocyte dysfunction and loss. Melanocytes produce melanin pigment through a melanogenesis process. Melanocyte survival and melanogenesis process are influenced by Microphthalmia Associated- Transcription Factor (MITF) and several proteins, including WNT, β-catenin, tyrosinase, Tyrosinase- Related Protein-1 (TRP1), and Tyrosinase-Related Protein-2 (TRP2). The current therapy for vitiligo is still unsatisfactory. Naringenin is one of Rhizophora mucronata compound, one type of mangrove plant often found in the eastern coastal area of Surabaya City. Objective: To investigate the naringenin’s potency in melanogenesis and to predict the pharmacokinetics or toxicity of naringenin by in silico study. Methods: This is a computational study using a molecular docking method to observe the interaction of naringenin with WNT, β-catenin, MITF, tyrosinase, TRP-1, and TRP-2 proteins. Pharmacokinetic or toxicity prediction of naringenin using the pkCSM method. Psoralen was used as a control. Results: Naringenin binds to all these proteins in the same region as psoralen, indicating that naringenin can stimulate melanogenesis. Naringenin has lower binding energy than psoralen on all proteins (except β-catenin), indicating that naringenin's interaction with these proteins is stronger than psoralen. Pharmacokinetic and toxicity predictions show that naringenin has good absorption or permeation, is not mutagenic, is not hepatotoxic, and does not cause skin sensitization. Conclusion: This computational study concludes that naringenin has melanogenesis inducer potency and good pharmacokinetics.

Melanogenesis Inhibitory Activity, Chemical Components and Molecular Docking Studies of Prunus cerasoides Buch.-Ham. D. Don. Flowers.

Safe depigmenting agents are currently increasing in the cosmetic or pharmaceutical industry because various compounds have been found to have undesirable side effects. Therefore, the present study aimed to investigate the melanogenesis inhibitory effects of Prunus cerasoides Buch. -Ham. D. Don. flower extracts and their molecular mechanism in B16F10 mouse melanoma cells. Moreover, we also examined phenolic and flavonoid contents, antioxidant activity, chemical constituents of potential extracts, and molecular docking. The highest phenolic and flavonoid contents with the greatest scavenging activity were found in the butanol extract of the P. cerasoides flower compared to other extracts. From all extracts, only crude, diethyl ether, and butanol extracts showed an inhibition of mushroom tyrosinase activity, cellular tyrosinase activity, and melanin content as well as the downregulation of the gene expression of the microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) in α-MSH-stimulated B16F10 cells. Based on the molecular docking study, n-hexadecanoic acid, heptadecanoic acid, octadecanoic acid, 9,12-octadecadienoic acid, 9,12,15-octadecanoic acid, and eicosanoic acid might show an inhibitory effect against tyrosinase and MITF. In conclusion, this finding demonstrates that both the diethyl ether and butanol extracts of the P. cerasoides flower can effectively reduce tyrosinase activity and melanin synthesis through the downregulation of the melanogenic gene expression in B16F10 cells and through the molecular docking study. Taken together, the diethyl ether and butanol extracts of the P. cerasoides flower could be an anti-melanogenic ingredient for hyperpigmentary or melasma treatment.

Resveratrol can induce differentiating phenotypes in canine oral mucosal melanoma cells.

This report described the differentiation induction of canine oral mucosal melanoma (OMM) cells by resveratrol. Exposure of canine OMM cells to resveratrol (maximum dose: 50 μM and treatment period: 72 hr) induced differentiating features like melanocytes, and enhanced chemosensitivity against cisplatin, but alone had no influence on cell viability. Additionally, resveratrol significantly enhanced mRNA expression of key melanoma differentiation markers such as microphthalmia-associated transcription factor (MITF). Of several inhibitors against mitogen-activated protein kinase subtypes, only the c-Jun N-terminal kinase (JNK) inhibitor, SP600125, induced melanocyte-like morphological change and enhanced MITF mRNA expression. Furthermore, resveratrol also suppressed JNK activation in OMM cells by approximately 33%. Overall, these findings suggest that resveratrol induces differentiation in canine OMM cells, due to the inhibition of JNK signaling.

Hibiscus Flower Extract and Niacinamide Show Enhanced Whitening Effects in Mouse Melanoma Cells (B16F10)

Melanoma, a type of cancer that most often occurs on skin exposed to UV rays, is becoming increasingly common. Recent research has focused actively on using natural products. The goal of this study was to compare the melanin-inhibitory effects of Hibiscus (Hibiscus sabdariffa L.) flower Extract (HE) and Niacinamide (NA), a functional ingredient with whitening effects, on melanoma cells. The 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the effects of HE (1, 3.5, 7, 10, and 14 μg/mL) and NA (1, 5, 10, 20, and 25 μg/mL) on cell viability. A lactate dehydrogenase cytotoxicity assay was employed to confirm the cytotoxic effect of HE and NA on mouse melanoma cells. The real-time reverse-transcription polymerase chain reaction was performed to analyze Tyrosinase (TYR), Tyrosinase-Related Protein (TRP), and Microphthalmia-associated Transcription Factor (MITF) mRNA expression levels to determine whitening effects. Vitamin C (VC, 10 µg/mL) was selected as a control. The MTT assay showed that HE and NA were non-cytotoxic at <10 μg/mL in B16F10 cells when compared to the control, VC. The cytotoxicity of HE was confirmed to be lower than the control (VC) when a concentration of 7 µg/mL or lower was applied. The cytotoxicity of NA was low even at a concentration of 10 µg/mL. HE showed greater whitening effects at lower concentrations (i.e., 1 µg/mL) than VC (10 µg/mL). HE had almost no cytotoxicity compared to NA and VC, and the expression levels of whitening inhibition genes MITF and TYR were higher than VC, indicating that it can be used as a healthy functional food or cosmetic material.

Novel role of microphthalmia-associated transcription factor in modulating the differentiation and immunosuppressive functions of myeloid-derived suppressor cells

BackgroundMicrophthalmia-associated transcription factor (MITF) is a master regulator of melanogenesis and is mainly expressed in melanoma cells. MITF has also been reported to be expressed in non-pigmented cells, such as...

Characterization and functional analysis of pax3 in body color transition of polychromatic Midas cichlids (Amphilophus citrinellus).

As the representative genetic and economic trait of ornamental fish, skin color has a strong impact on speciation and adaptation. However, the genetic basis of skin color pigmentation, differentiation and change is still not understood. The Midas cichlid fish with three typical body color transition stages of "black-gray‑gold" is an ideal model system for investigating the formation and change of fish body color. In this study, to investigate the regulatory role of the pair box 3 (pax3) gene in the early body color fading process of Midas cichlids, the complete cDNA sequence (3513bp) of pax3 was successfully isolated from Midas cichlids (Amphilophus Citrinellus), and found to encode polypeptides of 491 amino acids. Expression patterns of the pax3 gene in tissues of Midas cichlids during different periods, including embryonic development and body color fading stages were detected by quantitative real-time PCR. The qRT-PCR analysis showed that pax3 was expressed in all tissues of adult fish, with a higher expression level in muscle and skin. The highest expression level in muscle tissue was significantly higher than that in other tissues (P<0.05). During embryonic development, the expression tendency of pax3 was first increased and then decreased. In the three typical stages of early skin color fading from black to gold, pax3 expression in skin, caudal fin and scales all showed a downward trend. The expression level in the black stage was significantly higher than that in other stages (P<0.05). Positive signal of pax3 protein was detected in the three typical skin color conversion stages, and the highest positive signal intensity was detected in the black stage, which was consistent with qRT-PCR results. After pax3 RNA interference, pax3 and the downstream genes mitf and tyr all decreased, while dct mRNA expression increased in the skin of fish. Western blotting also showed a decrease in pax3 protein concentration. Those results suggest that pax3 plays an important role in skin color formation, distribution and change in Midas cichlids through the melanogenesis pathway.

Evaluation and Comparison of the Antimelanogenic Properties of Different Solvent Fractionated Cnidium japonicum Extracts in B16F10 Murine Melanoma Cells.

Cnidium japonicum is a biennial halophyte found in the salt marshes and shores of Korea and widely used in traditional Korean medicine as an ingredient. This study investigated and compared the antimelanogenic effect of solventpartitioned fractions of C. japonicum extract (CJEFs) in a B16F10 mouse melanoma cell model, focusing on tyrosinase activity and production. Melanogenesis is the process in which skin pigment melanin is produced through tyrosinase activity. Overproduction of melanin is the primary reason behind several skin disorders such as freckles, spots, and hyperpigmentation. The antimelanogenic capacity of CJEFs was initially screened by their tyrosinase inhibitory effects, prevention of dihydroxyphenylalanine (DOPA) oxidation, and suppression of melanin production. The inhibition of tyrosinase activity and DOPA oxidation by CJEFs was suggested to be related to the downregulation of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2, which was confirmed using mRNA and protein expression levels. Moreover, the glycogen synthase kinase 3 beta- and cyclic adenosine monophosphate response element-binding protein-related signaling pathways were inhibited by treatment with CJEFs, indicating their action mechanism. All the tested CJEFs exerted similar effects on tyrosinase activity and production. However, among those, 85% aq. MeOH was the most active fraction to suppress the signaling pathway that produces tyrosinase. These results suggest that especially the MeOH fraction of C. japonicum extract serves as a potential source of bioactive substances, with effective antimelanogenesis properties.

Anti-Melanogenesis Effects of a Cyclic Peptide Derived from Flaxseed via Inhibition of CREB Pathway.

Linosorbs (Los) are cyclic peptides from flaxseed oil composed of the LO mixture (LOMIX). The activity of LO has been reported as being anti-cancer and anti-inflammatory. However, the study of skin protection has still not proceeded. In particular, there are poorly understood mechanisms of melanogenesis to LO. Therefore, we investigated the anti-melanogenesis effects of LOMIX and LO, and its activity was examined in mouse melanoma cell lines. The treatment of LOMIX (50 and 100 μg/mL) and LO (6.25-50 μM) suppressed melanin secretion and synthesis, which were 3-fold increased, in a dose-dependent manner, up to 95%. In particular, [1-9-NαC]-linusorb B3 (LO1) and [1-9-NαC]-linusorb B2 (LO2) treatment (12.5 and 25 μM) highly suppressed the synthesis of melanin in B16F10 cell lines up to 90%, without toxicity. LOMIX and LOs decreased the 2- or 3-fold increased mRNA levels, including the microphthalmia-associated transcription factor (MITF), Tyrosinase, tyrosinase-related protein 1 (TYRP1), and tyrosinase-related protein 2 (TYRP2) at the highest concentration (25 μM). Moreover, the treatment of 25 μM LO1 and LO2 inhibited the expression of MITF and phosphorylation of upper regulatory proteins such as CREB and PKA. Taken together, these results suggested that LOMIX and its individual LO could inhibit melanin synthesis via downregulating the CREB-dependent signaling pathways, and it could be used for novel therapeutic materials in hyperpigmentation.

Anti-Melanogenesis Effect of Rosa rugosa on α-MSH-Induced B16F10 Cells via PKA/CREB Pathway Activation

Melanin protects the skin against UV damage, whereas excessive melanin accumulation causes abnormal pigmentation and even melanoma. It has been reported that Rosa rugosa exhibits antioxidant, anti-bacterial, anti-tumor, and anti-inflammation activities. The current study evaluated the melanogenesis-suppressing effect of R. rugosa extract and its solvent fractions (H2O, n-BuOH, 85% aq. MeOH, and n-hexane). The effect of R. rugosa on the extra/intra-cellular melanin and intracellular active tyrosinase levels, melanogenesis-related gene and protein expression, and PKA/CREB signaling pathway activation was investigated in α-MSH-induced B16F10 cells. The results showed that R. rugosa effectively suppressed melanin secretion and tyrosinase activity at non-cytotoxic concentrations. R. rugosa extract down-regulated the melanogenesis-related expression of genes and proteins of tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP)-1, and TRP-2. Furthermore, R. rugosa effectively inhibited the phosphorylation of the PKA/CREB proteins. Finally, the total polyphenol content of R. rugosa crude extract and its H2O, n-BuOH, 85% aq. MeOH, and n-hexane solvent fractions were 1383.9 ± 44.5, 2004.7 ± 43.4, 7270.3 ± 54.5, 2064.1 ± 34.8, and 1091.1 ± 26.2 mg gallic acid equivalent/100 g extract, respectively. The anti-melanogenesis effect of R. rugosa was suggested to be exhibited by downregulating the PKA/CREB signaling pathway potentially due to a high content of polyphenols. Overall, R. rugosa crude extract and its solvent fractions could be considered sources of bioactive ingredients that can be used against hyperpigmentation.

Miglitol, an Oral Antidiabetic Drug, Downregulates Melanogenesis in B16F10 Melanoma Cells through the PKA, MAPK, and GSK3β/β-Catenin Signaling Pathways

Hyperpigmentation is a common condition that causes darker spots or patches on the skin, which often look brown, black, gray, red, or pink. This results in unresolved psychological impact due to high anxiety, depression, and somatoform disorder. We aimed to repurpose an antidiabetic drug, miglitol, as an effective compound against hyperpigmentation when applied as a cosmeceutical agent. The present study investigated the antimelanogenic effects of miglitol and the trehalase inhibitor validamycin A. Miglitol in isolation exhibited no cytotoxicity and significantly reduced the melanin production and intracellular tyrosinase activity in B16F10 melanoma cells. The Western blotting results showed that miglitol reduces the expression of melanogenic regulatory factors, including tyrosinase, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF). Mechanistically, miglitol appears to suppress melanin synthesis through cAMP-dependent protein kinase (PKA)-dependent downregulation of MITF, a master transcription factor in melanogenesis. The antimelanogenic effects of miglitol was mediated by downregulation of the p38 signaling pathway and upregulation of extracellular signal-regulated kinase (ERK). Moreover, miglitol decreases P-GSK3β and β-catenin levels compared to those in the untreated group. However, miglitol activated P-β-catenin expression compared to that in the untreated group. Finally, we tested the potential of miglitol in topical application through primary human skin irritation tests on the normal skin (upper back) of 33 volunteers. In these assays, miglitol (125 and 250 μM) did not induce any adverse reactions. Taken together, these findings suggest that the regulation of melanogenesis by miglitol may be mediated by the PKA, MAPK, and GSK3β/β-Catenin signaling pathways and that miglitol might provide new insights into drug repurposing for the treatment of hyperpigmentation symptoms.

New Butyroside D from Argan Press Cake Possess Anti-Melanogenesis Effect via MITF Downregulation in B16F10 and HEM Cells.

Hyperpigmentation is a skin condition where patches of skin become darker in color due to excess melanin production upon UV exposure leading to melasma, which are lentigines or post inflammatory hyperpigmentation that psychologically affecting a great number of people. The present study investigates the anti-melanogenic effect of Butyroside D and the underling mechanism. After the confirmation of the non-cytotoxic effect of Butyroside D on B16F10 cells, we proceeded with analyzing the impact of the treatment at low and high concentration (i.e., 0.2 μM and 2 μM) using gene profiling analysis and examined the differentiation in gene expression. Our results identify cyclic adenosine monophosphate (cAMP), Wnt/β-catenin and Mitogen-Activated Protein Kinase (MAPK) signaling pathways to be downregulated upon treatment with Butyroside D. These pathways were targeted to further validate the effect of Butyroside D on membrane receptors melanocortin 1 receptor (MC1R) and receptor tyrosine kinase (c-Kit), related microphthalmia-associated transcription factor (MITF) and consequently tyrosinase (TYR), and tyrosine-related protein-1 (TYRP-1) that were all shown to be downregulated and, therefore, leading to the repression of melanin biosynthesis. Finally, the anti-melanogenic effect of Butyroside D was confirmed on human epidermal melanocytes (HEM) cells by inhibiting the activation of cAMP pathway generally mediated through α-melanocyte-stimulating hormone (α-MSH) and MC1R. Overall, this study suggests the potential applicability of this purified compound for the prevention of hyperpigmentation conditions.

SH3BP2 Silencing Increases miRNAs Targeting ETV1 and Microphthalmia-Associated Transcription Factor, Decreasing the Proliferation of Gastrointestinal Stromal Tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Gain of function in receptor tyrosine kinases type III, KIT, or PDGFRA drives the majority of GIST. Previously, our group reported that silencing of the adaptor molecule SH3 Binding Protein 2 (SH3BP2) downregulated KIT and PDGFRA and microphthalmia-associated transcription factor (MITF) levels and reduced tumor growth. This study shows that SH3BP2 silencing also decreases levels of ETV1, a required factor for GIST growth. To dissect the SH3BP2 pathway in GIST cells, we performed a miRNA array in SH3BP2-silenced GIST cell lines. Among the most up-regulated miRNAs, we found miR-1246 and miR-5100 to be predicted to target MITF and ETV1. Overexpression of these miRNAs led to a decrease in MITF and ETV1 levels. In this context, cell viability and cell cycle progression were affected, and a reduction in BCL2 and CDK2 was observed. Interestingly, overexpression of MITF enhanced cell proliferation and significantly rescued the viability of miRNA-transduced cells. Altogether, the KIT-SH3BP2-MITF/ETV1 pathway deserves to be considered in GIST cell survival and proliferation.

Atraric Acid Ameliorates Hyperpigmentation through the Downregulation of the PKA/CREB/MITF Signaling Pathway.

Atraric acid (AA) is derived from lichens and is widely used in perfumes for its desirable scent. It has been reported as having anti-inflammatory and antioxidant activity. Hyperpigmentation is the underlying cause of a variety of dermatological diseases that have a significant impact on patients' quality of life and are frequently difficult to treat. This study aimed to explore the inhibitory effects of AA on hyperpigmentation in vitro and in vivo and its potential molecular mechanisms. The cytological results revealed that at a dose of 250 μM, AA may reduce melanin content and tyrosinase levels without causing cytotoxicity. Furthermore, the expression of melanocortin-1 receptor (MC1R), phosphorylated protein kinase A (pPKA) and phosphorylated cAMP response element binding protein (pCREB) were downregulated in AA-administrated cells. In vivo, histological analysis showed that AA could inhibit melanin production and tyrosinase activity, and 3% AA had the best activity, with almost no side effects. Furthermore, the results of Western blot analysis and RT-PCR suggested that AA may suppress the mRNA transcription of microphthalmia-associated transcription factor (MITF) protein and tyrosine protease by decreasing the expression of MC1R, consequently decreasing the phosphorylation of PKA and CREB. Finally, the MC1R inhibitor MSG606 verified the hypothesis that AA suppresses melanin formation by downregulating the PKA/CREB/MITF signaling pathway. Taken together, our study offers valuable information for the development of AA as a possible ingredient in skin-lightening cosmeceuticals and hyperpigmentation inhibitors.

Knockout of microphthalmia-associated transcription factor (mitf) confers a red and yellow tilapia with few pigmented melanophores

As the most important genetic factor for melanophore differentiation and melanogenesis, mitf has been studied for over 30 years. The phenotypes of mitf mutants have also received continuous attention for nearly a century. Due to the third round of genome duplication, teleosts have two mitf genes. Mutation analysis demonstrates that mitfa plays an important role in zebrafish pigmentation. However, there have been no functional studies on body color regulation by mitfb or studies of mitfa;mitfb double mutants. In the present study, we mutated both mitf genes in tilapia using CRISPR/Cas9. Disruption of mitfa resulted in light yellow body color with weak gray vertical bars due to significantly reduced numbers of melanophores and increased sizes of xanthophores, while disruption of mitfb led to slight hypo-pigmentation. Double mutation of mitfa and mitfb resulted in dramatic hypo-pigmentation in trunk and fins due to loss of additional melanophores and increase in the number of iridophores compared to the single mutants, but had no influence on retinal pigment epithelium (RPE) pigmentation. The mitfa−/−;mitfb−/− mutants were yellow with black spots at early juvenile stage (60 dpf), yellow-reddish at late juvenile stage (120 dpf) and red and yellow (including iris) at adult stage (180 dpf), due to increased erythrophores and enlarged xanthophores. Our results demonstrated that both mitf genes are important for body color formation in tilapia, but mitfa plays a more important role than mitfb. Additionally, by comparing the phenotypes of the mitfa−/−;mitfb−/−, pmela−/−;pmelb−/− and hps4−/− mutants, we found that disruption of genes with different functions in different aspects of melanogenesis could lead to different body colors in tilapia. Mitf is the most important gene for melanophore differentiation and is probably also critical for differentiation of erythrophores, xanthophores and iridophores. To our knowledge, this is the first report showing that both mitf genes are involved in body color formation by loss of function study, and the first report showing that erythrophore numbers and xanthophore sizes were affected by mitf. Our research not only serves as a model for studying mitf function in tilapia and the closely related cichlids, but also provides new strategies for breeding red and yellow tilapia for aquaculture.

Antimelanogenesis Effect of Methyl Gallate through the Regulation of PI3K/Akt and MEK/ERK in B16F10 Melanoma Cells.

Methyl gallate is a polyphenolic compound found in many plants, and its antioxidant, antitumor, antibacterial, and anti-inflammatory effects have been extensively studied. More recently, antidepressant-like effects of methyl gallate have been demonstrated in some studies. In the present study, we examined the effects of methyl gallate on melanogenesis, including the tyrosinase inhibitory effect, the melanin content, and the molecular signaling pathways involved in this inhibition. The results showed that methyl gallate inhibited tyrosinase activity and significantly downregulated the expressions of melanin synthesis-associated proteins, including microphthalmia-associated transcription factor (MITF), tyrosinase, dopachrome tautomerase (Dct), and tyrosinase-related protein-1 (TRP1). In conclusion, our findings indicated that activation of MEK/ERK and PI3K/Akt promoted by methyl gallate caused downregulation of MITF and triggered its downstream signaling pathway, thereby inhibiting the production of melanin. In summary, methyl gallate showed significant inhibitory activity against melanin formation, implying that it may be a potential ingredient for application in skin-whitening cosmetics.