“Transcription physiology” of pigment formation in melanocytes: central role of MITF

Ammonium chloride, an environmental pollutant, disrupts melanocyte biology through the regulation of melanosome and autophagy

Ammonium chloride is an indoor environmental pollutant released due to industrial emissions, concrete, indoor bacteria, or other sources. In this study, we characterized molecular mechanisms of ammonium chloride-induced cell damage in melanocyte cells, which are a critical effector for pigmentation. Specifically, we investigated the effects of ammonium chloride on pigmentation and its underlying mechanisms, including its involvement in melanogenesis and autophagy. Based on the experiments, we elucidated that ammonium chloride induced and increased melanogenesis by upregulating MITF via AKT-mediated melanogenic signaling pathways. Moreover, ammonium chloride did not exhibit lysosomotropic activity and inhibited autophagy by activating the AKT-mTOR signaling pathway, suggesting that the pigment-regulating mechanism of ammonium chloride was associated with autophagy in pigmented cells. The findings of this study offer new perspectives on the mechanisms involved in ammonium chloride-induced pigmentation and propose a potential approach to mitigate ammonium chloride-induced side effects like hyperpigmentation and hyperammonemia by employing a combined autophagy inducer.

Physicochemical Characterization, Skin Penetration, Anti-Melanogenesis and Safety Assessment of Flavokawain C Nanofibers

Various whitening cosmetics are available in the market, usually containing active whitening ingredients. However, most of the reported active ingredients have low dermal penetration due to their lipophilic structure. Therefore, it is necessary to develop effective whitening agents and novel formulations to address this. In previous studies, natural compounds such as chalcones have shown inhibitory effects on tyrosinase. However, most chalcone compounds have the disadvantage of poor water solubility, which restricts their dermal absorption. Flavokawain C (FKC) is a natural chalcone obtained from the root of the kava tree (Piper methysticum) and can also be obtained through organic synthesis. Since FKC is a chalcone, it is also water-insoluble, showing poor dermal absorption. In this study, electrospinning technology was used to develop FKC nanofibers (FKCNFs) to improve FKC's physicochemical properties. The results showed that FKCNFs significantly improved water solubility and percutaneous absorption. Based on the results of in vitro experiments with B16F10 melanoma cells, 10 µM FKCNFs repressed the expressions of melanogenesis-related proteins MITF and TRP2. Furthermore, cosmetic safety assessment revealed that FKCNFs displayed a good margin of safety. This study suggests that FKCNFs have great potential as an effective active ingredient for whitening cosmetics.

Increased melanin induces aberrant keratinocyte - melanocyte - basal - fibroblast cell communication and fibrogenesis by inducing iron overload and ferroptosis resistance in keloids

BACKGROUND

Keloid is a typical skin fibrotic disease with unclear mechanisms and limited therapeutic options. Fibroblast-induced fibrogenesis is a crucial cause of KD. However, the types of cells involved in fibroblast fibrogenesis in KD and the specific mechanisms are unclear. This study aimed to investigate the role of melanocyte-secreted melanin in promoting fibroblast fibrogenesis and its mechanism and to evaluate the potential therapeutic effect of intervening melanin in treating keloid.

METHODS

The activity of pigmentation-related pathways in KD melanocytes was examined using single-cell RNA-sequence (scRNA-seq) analysis. Masson-Fontana staining or isolated melanin quantification detected the melanin levels and distribution in the skin and cells. Collagen deposition, wounding healing, and proliferation analysis were employed to integratively assess fibroblast fibrogenesis. After melanin treatment, bulk-seq identified fibroblasts' differentially expressed genes (DEGs). The iron levels were detected by Perl's staining or isolated iron quantification. Cell viability, LipidROS, and malondialdehyde assay accessed the ferroptosis levels. The therapeutic potential of ML329 was evaluated in keloid-bearing mice.

RESULTS

We found the enriched skin pigmentation-related pathways in the melanocytes of keloid by single-cell RNA-sequence (scRNA-seq) analysis. We further validated increased melanin levels in keloid patients. Additionally, melanin positively correlated with the Keloid Area and Severity Index in keloid. Furthermore, melanocyte-secreted melanin significantly promoted fibroblast proliferation, migration, and collagen synthesis. Mechanically, melanin increased basal cell permeability and inflammation to facilitate its transfer to the dermis, where it further activated fibroblasts by evoking iron overload and ferroptosis resistance. Consistently, iron overload and ferroptosis resistance were validated in primary fibroblasts and skin tissues of keloid patients. Inhibition of iron overload and ferroptosis resistance effectively diminish melanin-induced fibrogenesis. Interestingly, melanin induced iron overload and ferroptosis resistance in melanocytes in an autocrine manner and further stimulated keratinocytes to take up melanin to deepen skin color by upregulating the F2R-like trypsin receptor 1 (F2RL1). In vivo, the delivery of ML329, a microphthalmia-associated transcription factor (MITF) inhibitor, could suppress melanogenesis and alleviate keloid in human keloid-bearing nude mice. Meanwhile, ML329 decreased the iron content and restored the sensitivities of ferroptosis.

CONCLUSION

Collectively, melanin-lowing strategies may appear as a potential new therapeutic target for keloid.

A Novel Butyrate Derivative, Zinc Dibutyroyllysinate, Blunts Microphthalmia-Associated Transcription Factor Expression and Up-Regulates Retinol and Differentiation Pathway mRNAs in a Full-Thickness Human Skin Model

Lysine, butyric acid, and zinc play important roles in skin homeostasis, which involves aging, inflammation, and prevention of skin barrier disruption. This bioactivity spectrum is not replicated by any one topical compound currently in use. Our purpose in this study was to characterize a novel compound, zinc dibutyroyllysinate (ZDL), consisting of zinc with lysine and butyric acid moieties. We used RNA-seq to evaluate its effect on gene expression in a full-thickness skin model. We show that lysine alone has minimal effects on gene expression, whereas ZDL had greater transcriptional bioactivity. The effects of ZDL included an increased expression of genes promoting epidermal differentiation and retinol metabolism, along with a decreased expression of microphthalmia-associated transcription factor (MITF) and other melanogenesis genes. These effects were not replicated by an alternative salt compound (i.e., calcium dibutyroyllysinate). ZDL additionally led to a dose-dependent increase in skin fibroblast extracellular matrix proteins, including collagen I, collagen IV, and prolidase. Loss of melanin secretion was also seen in ZDL-treated melanocytes. These results provide an initial characterization of ZDL as a novel topical agent. Our findings support a rationale for the development of ZDL as a skincare ingredient, with potential applications for diverse conditions, involving melanocyte hyperactivity, pigmentation, inflammation, or aging.

Melanin deposition and key molecular features in Xenopus tropicalis oocytes

BACKGROUND

Melanin pigmentation in oocytes is a critical feature for both the esthetic and developmental aspects of oocytes, influencing their polarity and overall development. Despite substantial knowledge of melanogenesis in melanocytes and retinal pigment epithelium cells, the molecular mechanisms underlying oocyte melanogenesis remain largely unknown.

RESULTS

Here, we compare the oocytes of wild-type, tyr-/- and mitf-/- Xenopus tropicalis and found that mitf-/- oocytes exhibit normal melanin deposition at the animal pole, whereas tyr-/- oocytes show no melanin deposition at this site. Transmission electron microscopy confirmed that melanogenesis in mitf-/- oocytes proceeds normally, similar to wild-type oocytes. Transcriptomic analysis revealed that mitf-/- oocytes still express melanogenesis-related genes, enabling them to complete melanogenesis. Additionally, in Xenopus tropicalis oocytes, the expression of the MiT subfamily factor tfe3 is relatively high, while tfeb, mitf, and tfec levels are extremely low. The expression pattern of tfe3 is similar to that of tyr and other melanogenesis-related genes. Thus, melanogenesis in Xenopus tropicalis oocytes is independent of Mitf and may be regulated by other MiT subfamily factors such as Tfe3, which control the expression of genes like tyr, dct, and tyrp1. Furthermore, transcriptomic data revealed that changes in the expression of genes related to mitochondrial cloud formation represent the most significant molecular changes during oocyte development.

CONCLUSIONS

Overall, these findings suggest that further elucidation of Tyr-dependent and Mitf-independent mechanisms of melanin deposition at the animal pole will enhance our understanding of melanogenesis and Oogenesis.

Small-Molecule Tyrosinase Inhibitors for Treatment of Hyperpigmentation

Increasing attention is being focused on skin health currently, especially the excessive deposition of melanin in the skin. Tyrosinase, the rate-limiting enzyme in melanin biosynthesis, is a crucial enzyme in melanin synthesis. However, existing tyrosinase inhibitors pose some degree of toxicity to humans. Therefore, the development of more efficient and low-toxicity tyrosinase inhibitors is urgently needed. This review briefly depicts the melanin biosynthesis process and the crystal structure and catalytic mechanism of tyrosinase. The latest research progress regarding small-molecule tyrosinase inhibitors is also reviewed. Moreover, the structure-function relationships are analyzed and summarized. This is expected to provide new and more scientific insights to enable researchers to explore safer and more potent tyrosinase inhibitors.

Exosomal miR-365b-5p derived from keratinocyte promotes melanogenesis by directly targeting GLI2

In previous studies, we analyzed that exosomal microRNA (miRNA) secreted by keratinocytes exposed to Ultraviolet B(UVB) light regulate melanogenesis in melanocytes. Through functional experiments, it was determined that a subgroup of exosomal miRNAs had distinct impacts on melanogenesis. In the current study, we focused on hsa-miR-365b-5p which founded upregulated in UVB-irradiated keratinocyte exosomes and confirmed to exert enhancing effects on melanogenesis in human melanocyte. Hsa-miR-365b-5p is a specific, mature microRNA derived from the precursor hsa-miR-365. We demonstrated that the overexpression of hsa-miR-365b-5p in normal human epidermal melanocytes (NHEM) resulted in an approximate 50% increase in melanin content relative to the control group. Furthermore, treatment with an inhibitor of hsa-miR-365b-5p substantiated its specific regulatory role in melanogenesis, as inhibition resulted in a nearly 90% reduction in melanin production. Notably, hsa-miR-365b-5p upregulates the expression of genes associated with melanogenesis, including MITF, TYR, TRP1, and TRP2. Additionally, we established that GLI Family Zinc Finger 2 (GLI2) functions as a repressor of MITF, with its inhibition via siRNA leading to increased melanogenesis. Moreover, we constructed a luciferase reporter vector containing the 3' UTR of GLI2, confirming that hsa-miR-365b-5p specifically targets GLI2, a known repressor of MITF. These findings elucidate the regulatory pathways governing melanogenesis and underscore the significant role of hsa-miR-365b-5p in this biological process.

Drug Repurposing of Voglibose, a Diabetes Medication for Skin Health

Background/Objectives: Voglibose, an α-glucosidase inhibitor commonly prescribed to manage postprandial hyperglycemia in diabetes mellitus, demonstrates potential for repurposing as an anti-melanogenic agent. This study aims to explore the inhibitory effects of voglibose on melanogenesis and elucidate its molecular mechanisms, highlighting its possible applications in treating hyperpigmentation disorders. Methods: The anti-melanogenic effects of voglibose were investigated using B16F10 melanoma cells. Cell viability, melanin content, and tyrosinase activity were assessed following voglibose treatment. Western blot analysis was performed to examine changes in melanogenic proteins and transcription factors. The role of signaling pathways, including PKA/CREB, MAPK, PI3K/AKT, and GSK3β/β-Catenin, was analyzed. Primary human skin irritation tests were conducted to evaluate the topical safety of voglibose. Results: Voglibose significantly reduced melanin synthesis and tyrosinase activity in B16F10 cells in a dose-dependent manner. Western blot analysis revealed decreased expression of MITF, TRP-1, and TRP-2, indicating the inhibition of melanogenesis. Voglibose modulated key signaling pathways, including the suppression of PKA/CREB, MAPK, and AKT activation, while restoring GSK3β activity to inhibit β-catenin stabilization. Human skin irritation tests confirmed voglibose's safety for topical application, showing no adverse reactions at 50 and 100 μM concentrations. Conclusions: Voglibose demonstrates anti-melanogenic properties through the modulation of multiple signaling pathways and the inhibition of melanin biosynthesis. Its safety profile and efficacy suggest its potential as a repurposed drug for managing hyperpigmentation and advancing cosmeceutical applications.

Comparative in vitro and in silico evaluation of the toxic effects of metformin and/or ascorbic acid, new treatment options in the treatment of Melasma

Melasma is a chronic condition that leads to the buildup of melanin pigment in the epidermis and dermis due to active melanocytes. Even though it is considered a non-life-threatening condition, pigment disorders have a negative impact on quality of life. Since melasma treatment is not sufficient and complicated, new treatment options are sought. Research on metformin and ascorbic acid suggested that they might be used against melasma in the scope of "drug repositioning."The MNT-1 human melanoma cell line was used to assess the effects of metformin, ascorbic acid, and metformin+ascorbic acid combination on cytotoxicity and oxidative stress. Melanin, cAMP, L-3,4-dihydroxyphenylalanine (L-DOPA) and tyrosinase levels were determined by commercial ELISA kits and tyrosinase gene expression was analyzed with RT-qPCR. Cytopathological evaluations were performed by phase contrast microscopy. Tyrosinase expression was determined by immunofluorescence (IF) staining of MNT-1 cells. The online service TargetNet was used for biological target screening. The parameters were not significantly altered by ascorbic acid applied at non-cytotoxic concentrations. On the contrary, metformin dramatically raised tyrosinase and intracellular ROS levels. Moreover, intracellular ROS levels and tyrosinase levels were found to be considerably elevated with the combined treatment. Also, potential metformin and ascorbic acid interactions were determined. According to the results, it can be said that these parameters were not significantly altered by ascorbic acid. On the contrary, metformin dramatically raised tyrosinase and intracellular oxidative stress levels. Moreover, intracellular oxidative stress and tyrosinase levels were elevated with the combined treatment. In conclusion, individual treatments of ascorbic acid or metformin may only provide a limited effect when treating melasma and extensive in vitro and in vivo research are required.

A Cell-Based Evaluation of the Tyrosinase-Mediated Metabolic Activation of Leukoderma-Inducing Phenols, II: The Depletion of Nrf2 Augments the Cytotoxic Effect Evoked by Tyrosinase in Melanogenic Cells

Chemical leukoderma is a disorder induced by chemicals such as rhododendrol and monobenzone. These compounds possess a p-substituted phenol moiety and undergo oxidation into highly reactive and toxic o-quinone metabolites by tyrosinase. This metabolic activation plays a critical role in the development of leukoderma through the production of damage to melanocytes and immunological responses. This study aimed to develop a simple method for assessing the metabolic activation of leukoderma-inducing phenols without analyzing the metabolite. Although B16BL6 melanoma cells showed insufficient sensitivity to the cytotoxicity assay, the siRNA-mediated knockdown of the transcription factor NRF2 (NFE2L2) repressed the expression of cytoprotective factors, thereby augmenting the cytotoxicity of all six leukoderma-inducing phenols tested in a tyrosinase-dependent manner, indicating enhanced sensitivity to o-quinone metabolites. Additionally, the knockdown of the NRF2-target Slc7a11 elevated the cytotoxicity of three out of the six compounds, indicating the involvement of cystine transport in cellular protection. In contrast, the knockdown or inhibition of the NRF2-target Nqo1 had minimal effects. The same response was induced upon Nrf2 and Slc7a11 knockdown in B16-4A5 cells, albeit with low sensitivity owing to low tyrosinase expression. We conclude that the analysis of tyrosinase-dependent cytotoxicity in Nrf2-depleted B16BL6 cells may serve as a useful strategy for evaluating the metabolic activation of chemicals.

An Overview of the Biological Complexity of Vitiligo

Vitiligo is a skin disease that affects all ethnicities and genders and is characterized by the loss of pigment essentially due to the selective loss of melanocytes. Although it is generally considered a systemic disease associated with polymorphisms in genes involved in the immune response, vitiligo is also considered an oxidative imbalance-associated disease. It represents a multifactorial pathology in which some genetic predisposition and epigenetic factors coupled with some critical biochemical and molecular pathways could play a pivotal role. The aim of this work was thus to review some of the fine cellular mechanisms involved in the etiopathogenesis of vitiligo, mainly focusing on the nonimmunological ones, extensively highlighted elsewhere. We took into consideration, in addition to oxidative stress, both the cause and the hallmark of the pathology, some less investigated aspects such as the role of epigenetic factors, e.g., microRNAs, of receptors of catecholamines, and the more recently recognized role of the mitochondria. Sex differences associated with vitiligo have also been investigated starting from sex hormones and the receptors through which they exert their influence. From literature analysis, a picture seems to emerge in which vitiligo can be considered not just a melanocyte-affecting disease but a systemic pathology that compromises the homeostasis of a complex tissue such as the skin, in which different cell types reside playing multifaceted physiological roles for the entire organism. The exact sequence of cellular and subcellular events associated with vitiligo is still a matter of debate. However, the knowledge of the individual biological factors implicated in vitiligo could help physicians to highlight useful innovative markers of progression and provide, in the long run, new targets for more tailored treatments based on individual manifestations of the disease.

Methylsulfonylmethane promotes melanogenesis via activation of JNK in Mel-Ab cells

OBJECTIVE

Methylsulfonylmethane (MSM), which contains organic sulphur, has been used for a long time as a medicinal ingredient because of its benefits to human health. MSM is reported to be protective against certain skin disorders, but it is unknown whether it affects melanin synthesis. Therefore, in our current research, we examined the possibility of MSM controlling the production of melanin in Mel-Ab melanocytes.

METHODS

In Mel-Ab cells, melanin contents and tyrosinase activities were assessed and quantified. The expression of microphthalmia-associated transcription factor (MITF) and tyrosinase was evaluated using western blot analysis, while MSM-induced signalling pathways were investigated.

RESULTS

The MSM treatment significantly resulted in a dose-dependent increase in melanin production. Furthermore, MSM elevated melanin-related proteins, including MITF and tyrosinase. However, the rate-limiting enzyme of melanin production, tyrosinase, was not directly influenced by it. Therefore, we investigated potential melanogenesis-related signalling pathways that may have been triggered by MSM. Our findings showed that MSM did not influence the signalling pathways associated with glycogen synthase kinase 3β, cAMP response-element binding protein, extracellular signal-regulated kinase, or p38 mitogen-activated protein kinase. However, MSM phosphorylated c-Jun N-terminal kinases/stress-activated protein kinase (JNK/SAPK), which is known to induce melanogenesis. SP600125, a specific JNK inhibitor, inhibited MSM-induced melanogenesis.

CONCLUSION

Taken together, our study indicates that MSM induces melanin synthesis and may serve as a therapeutic option for hypopigmentary skin disorders such as vitiligo.

Ethanolic Extract of Bergenia purpurascens Exhibits Antimelanogenic Effects in B16F10 Cells through Multiple Mechanisms That Suppress Tyrosinase

Bergenia purpurascens, renowned for its antibacterial and antioxidant properties, remains relatively unexplored in its impact on melanogenesis. This study delves into the antimelanogenic potential of the ethanol extract derived from B. purpurascens (BPE). Our investigations reveal the robust antioxidant capabilities of the BPE, along with its effective inhibition of mushroom tyrosinase activity. Remarkably, these effects were significantly stronger than those observed with arbutin, the positive control. In vitro assays demonstrate the BPE's efficacy in reducing the melanin content and tyrosinase activity in α-MSH-stimulated B16F10 cells. Immunofluorescence and qPCR analyses further reveal the BPE's ability to inhibit MITF-mediated gene expression levels associated with melanogenesis, including Trp-1, Trp-2, and tyrosinase. These findings suggest that the extract operates through dual mechanisms, suppressing both tyrosinase activity and key transcription factor-mediated downstream signaling. Utilizing UPLC-MS/MS analysis, we identified six key compounds implicated in tyrosinase activity inhibition and melanogenesis suppression. Docking simulations confirm moderate binding affinities between these compounds and tyrosinase. This study highlights the potential of B. purpurascens as a novel natural agent for depigmentation in medicinal and cosmetic applications, elucidating its dual mechanism of action in melanogenesis inhibition.

Joint Genomic and Transcriptomic Analysis Reveals Candidate Genes Associated with Plumage Color Traits in Matahu Ducks

Plumage color is a key trait for identifying waterfowl breeds with significant economic importance. A white-feathered group has recently emerged within the native Matahu duck population, presenting an opportunity for breeding new lines. However, the genetic basis for this plumage variation is still unknown, necessitating further research. This study aims to identify the genetic mechanisms underlying the emergence of white-feathered individuals in the Matahu duck population through combined genome and transcriptome analysis, providing insights for selective breeding and the development of new white-feathered lines. In this study, a total of 1344 selected genes and 1406 significantly differentially expressed genes were identified through selection signal analysis and transcriptomic analysis, respectively. The functional enrichment of these genes revealed several key signaling pathways, including those related to cGMP-PKG, cAMP, PI3K-Akt, and MAPK. Furthermore, important candidate genes involved in melanin biosynthesis, such as MITF, MC1R, TYR, TYRP1, and ABCB6, were identified. Notably, 107 genes were detected by both methods, and, among these, DGKI, GPRC5B, HMX1, STS, ADGRA1, PRKAR2B, and HOXB9 are suggested to play a role in melanin formation and potentially influence plumage traits. Through the integrative approach combining genomic selection signals and transcriptomic analyses, we identified several candidate genes directly associated with plumage color, including MITF, TYR, TYRP1, and MC1R, along with multiple signaling pathways linked to melanin formation. We hypothesize that the expression of DGKI, GPRC5B, HMX1, STS, ADGRA1, PRKAR2B, and HOXB9, detected by both methods, may be closely related to the regulation of plumage color traits. These findings provide a foundational basis for further research aimed at elucidating the genetic mechanisms governing plumage color variation in ducks.

Hair follicle-targeted delivery for hair recoloration using scalp-curvature-conforming microneedles based on sodium alginate and polyvinylpyrrolidone

Hair-related disorders are currently widely concerned issues for not only the scientific society but also the public attentions. Microneedle-based drug delivery system has been regarded as a promise hair follicle-targeted drug delivery approach, largely because they can effectively penetrate the stratum corneum barrier and deliver drugs to hair follicles within dermis. However, the currently reported microneedles for treating hair-related disorders usually rely on rigid backings, showing poor adaptability to the curved scalp and thereby restricting their usability for hair follicles targeted drug delivery. To this end, this study utilized sodium alginate and polyvinylpyrrolidone to construct a scalp-curvature-conforming microneedle with flexible backing. Subsequently, Psoralea corylifolia extract (PE) was loaded into the microneedles to investigate its capability in delivering PE to the hair follicle site for treating leukotrichia associated with vitiligo. These PE-loaded microneedles can effectively conform to the curvature of skin, enhancing the efficiency of microneedle insertion and ensuring stable drug delivery. Moreover, animal studies demonstrate that the PE loaded microneedles can effectively penetrate the stratum corneum, benefiting the drug delivery to hair follicles located site, and consequently showing a successful inhibition of hair graying. In summary, the present study reports a design and preparation of scalp-curvature-conforming microneedle. This design may offer a potential solution for efficient drug delivery using microneedles to the curved skin.

Dynamic Transcriptome Profile Analysis of Mechanisms Related to Melanin Deposition in Chicken Muscle Development

The pectoral muscle is an important component of skeletal muscle. The blackness of pectoral muscles can directly affect the economic value of black-boned chickens. Although the genes associated with melanogenesis in mammals and birds have been thoroughly investigated, only little is known about the key genes involved in muscle hyperpigmentation during embryonic development. Here, we analyzed melanin deposition patterns in the pectoral muscle of Yugan black-boned chickens and compared differentially expressed genes (DEGs) between the muscles of Wenchang (non-black-boned chickens) and Yugan black-boned chickens on embryonic days 9, 13, 17, and 21. Melanin pigments were found to gradually accumulate in the muscle fibers over time. Using RNA-seq, there were 40, 97, 169, and 94 genes were identified as DEGs, respectively, between Yugan black-boned chicken muscles and Wenchang chickens at embryonic day 9, 13, 17, and 21 stages (fold change ≥2.0, false discovery rate (FDR) < 0.05). Thirteen DEGs, such as MSTRG.720, EDNRB2, TYRP1, and DCT, were commonly identified among the time points observed. These DEGs were mainly involved in pigmentation, melanin biosynthetic and metabolic processes, and secondary metabolite biosynthetic processes. Pathway analysis of the DEGs revealed that they were mainly associated with melanogenesis and tyrosine metabolism. Moreover, weighted gene co-expression network analysis (WGCNA) was used to detect core modules and central genes related to melanogenesis in the muscles of black-boned chickens. A total of 24 modules were identified. Correlation analysis indicated that one of them (the orange module) was positively correlated with muscle pigmentation traits (r > 0.8 and p < 0.001). Correlations between gene expression and L* values of the breast muscle were investigated in Yugan and Taihe black-boned chickens after hatching. The results confirmed that EDNRB2, GPNMB, TRPM1, TYR, and DCT expression levels were significantly associated with L* values (p < 0.01) in black-boned chickens (p < 0.05). Our results suggest that EDNRB2, GPNMB, TRPM1, TYR, and DCT are the essential genes regulating melanin deposition in the breast muscle of black-boned chickens. MSTRG.720 is a potential candidate gene involved in melanin deposition in the breast muscles of Yugan black-boned chickens.

MITF regulates IDH1, NNT, and a transcriptional program protecting melanoma from reactive oxygen species

Microphthalmia-associated transcription factor (MITF) is a master regulator of melanocyte function, development and plays a significant role in melanoma pathogenesis. MITF genomic amplification promotes melanoma development, and it can facilitate resistance to multiple therapies. Here, we show that MITF regulates a global antioxidant program that increases survival of melanoma cell lines by protecting the cells from reactive oxygen species (ROS)-induced damage. In addition, this redox program is correlated with MITF expression in human melanoma cell lines and patient-derived melanoma samples. Using a zebrafish melanoma model, we show that MITF decreases ROS-mediated DNA damage in vivo. Some of the MITF target genes involved, such as IDH1 and NNT, are regulated through direct MITF binding to canonical enhancer box (E-BOX) sequences proximal to their promoters. Utilizing functional experiments, we demonstrate the role of MITF and its target genes in reducing cytosolic and mitochondrial ROS. Collectively, our data identify MITF as a significant driver of the cellular antioxidant state.

Identification of candidate genes associated with primary feathers of tianfu nonghua ducks based on Genome-wide association studies

The primary feathers of ducks have important economic value in the poultry industry. This study quantified the primary feather phenotype of Nonghua ducks, including the primary feathers' length, area, distribution of black spots, and feather symmetry. And genome-wide association analysis was used to screen candidate genes that affect the primary feather traits. The genome-wide association study (GWAS) results identified the genetic region related to feather length (FL) on chromosome 2. Through Linkage disequilibrium (LD) analysis, candidate regions (chr2: 115,246,393-116,501,448 bp) were identified and were further annotated to 5 genes: MRS2, GPLD1, ALDH5A1, KIAA0319, and ATP9B. Secondly, candidate regions related to feather black spots were identified on chromosome 21. Through LD analysis, the candidate regions (chr21: 163,552-2,183,853 bp) were screened and further annotated to 47 genes. Among them, STK4, CCN5, and YWHAB genes were related to melanin-related pathways or pigment deposition, which may be key genes affecting the distribution of black spots on feathers. In addition, we also screened 125 genes on multiple chromosomes that may be related to feather symmetry. Among them, significant SNPs on chromosome 1 were further identified as candidate regions (chr1: 142,118,209-142,223,605 bp) through LD analysis and annotated into 2 genes, TGFBRAP1 and LOC113839965. These results reported the genetic basis of the primary feather from multiple phenotypes, and offered valuable insights into the genetic basis for the growth and development of duck feathers and feather color pattern.

Visual input regulates melanophore differentiation

Introduction

Developmental processes continue in organisms in which sensory systems have reached functional maturity, however, little research has focused on the influence of sensory input on cell and tissue development. Here, we explored the influence of visual system activity on the development of skin melanophores in Xenopus laevis.

Methods

Melanophore number was measured in X. laevis larvae after the manipulation of visual input through eye removal (enucleation) and/or incubation on a white or black substrate at the time when the visual system becomes functional (stage 40). To determine the developmental process impacted by visual input, migration, proliferation and differentiation of melanophores was assessed. Finally, the role of melatonin in driving melanophore differentiation was explored.

Results

Enucleating, or maintaining stage 40 larvae on a black background, results in a pronounced increase in melanophore number in the perioptic region within 24 h. Time lapse analysis revealed that in enucleated larvae new melanophores appear through gradual increase in pigmentation, suggesting unpigmented cells in the perioptic region differentiate into mature melanophores upon reduced visual input. In support, we observed increased expression of melanization genes tyr, tyrp1, and pmel in the perioptic region of enucleated or black background-reared larvae. Conversely, maintaining larvae in full light suppresses melanophore differentiation. Interestingly, an extra-pineal melatonin signal was found to be sufficient and necessary to promote the transition to differentiated melanophores.

Discussion

In this study, we found that at the time when the visual system becomes functional, X. laevis larvae possess a population of undifferentiated melanophores that can respond rapidly to changes in the external light environment by undergoing differentiation. Thus, we propose a novel mechanism of environmental influence where external sensory signals influence cell differentiation in a manner that would favor survival.

Potential Wound Healing and Anti-Melanogenic Activities in Skin Cells of Aralia elata (Miq.) Seem. Flower Essential Oil and Its Chemical Composition

Aralia elata (Miq.) Seem. (AES; family Araliaceae) is a medicinal plant and has been reported to have various bioactivities, including anticancer and hepatotoxicity protective activities. However, no studies have investigated the biological activities of AES or its extracts on skin. To address this, we aimed to explore the effect of AES-flower-derived absolute-type essential oil (AESFEO) on skin-related biological activities, especially skin wound healing and whitening-related responses in skin cells (human-derived keratinocytes [HaCaT cells] and melanocytes [B16BL6 cells]) and to identify the components of AESFEO. Cell biological activities were analyzed using WST and BrdU incorporation assays, ELISA, or by immunoblotting. In HaCaT cells, AESFEO promoted proliferation, type IV collagen production, and enhanced the phosphorylations of Erk1/2, p38 MAPK, JNK, and Akt. In B16BL6 cells, AESFEO reduced serum-induced proliferation, α-MSH-stimulated increases in melanin synthesis and tyrosinase activity, and α-MSH-induced increases in MITF, tyrosinase, TRP-1, and TRP-2 expressions. In addition, AESFEO inhibited the phosphorylation of Erk1/2, p38 MAPK, and JNK in α-MSH-stimulated B16BL6 cells. Eighteen compounds were identified in AESFEO by GC/MS. These results suggest that AESFEO has beneficial effects on keratinocyte activities related to skin wound healing and melanocyte activities related to inhibition of skin pigmentation. AESFEO may serve as a useful natural substance for developing agents that facilitate skin wound healing and inhibit melanogenesis.

Anti-tyrosinase and anti-melanogenic effects of piperine isolated from Piper nigrum on B16F10 mouse melanoma cells

The essential function of melanin is to protect our skin against harmful environmental factors. However, excessive melanin production can cause undesirable hyperpigmentation issues, such as freckles and melasma. Although several compounds are used to control melanin production by inhibiting tyrosinase (TYR), their efficacy is limited by skin-related adverse effects and cytotoxicity concerns. Consequently, searching for new natural compounds with an effective TYR inhibitor (TYR-I) activity but less harmful effects continues. Plant-based natural extracts are an alternative that are in great demand due to their safety and diverse biological properties. This study assessed ten isolated plant compounds for their TYR-I activities using an in vitro mushroom TYR inhibition assay. Among these compounds, piperine (400 μM) demonstrated the highest TYR-I activity, with a potency of 36.27 ± 1.96 %. Hence, this study examined the effect of piperine on melanogenesis in melanocyte stimulating hormone-treated B16F10 melanoma cells and using kojic acid as a positive reference. Cell viability was evaluated through the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Measurements of cellular TYR activity and melanin content were performed and related to changes in the transcriptional expression levels of melanogenesis-related genes, assessed via quantitative real-time reverse transcriptase (RT-q)PCR analysis. The results revealed that piperine at a concentration of 44 μM significantly reduced cellular TYR activity by 21.51 ± 2.00 % without causing cytotoxicity. Additionally, at the same concentration, piperine significantly decreased the intracellular melanin content by 37.52 ± 2.53 % through downregulating transcription levels of TYR and TYR-related protein 1 (TRP-1) but not TRP-2. Kojic acid, at a concentration of 1407 μM, induced a significant decrease in the melanin content and cellular TYR activity by suppressing all three melanogenesis-related genes. These findings suggest that piperine has potential as a potent depigmenting agent.

The relationship of MITF gene expression and promoter methylation with plumage colour in quail

1. This study focused on the relationship between MITF mRNA expression and plumage colour in quail and the effect of promoter methylation on the expression of MITF mRNA.2. The CDS region of MITF mRNA was cloned by RT-PCR, followed by DNA sequencing. The RT-qPCR method was used to analyse the expression levels of MITF mRNA in dorsal skin tissue in Korean quail and Beijing white quail. The promoter region of the MITF gene was cloned, and the CpG island was predicted by the CpGplot program. The methylation levels of the CpG island were analysed using BS-PCR technology.3. Quail MITF mRNA contains a 1,476 bp complete ORF, which encodes a 492 amino acid residue protein. The MITF protein has no signal peptide or transmembrane region. The expression of MITF mRNA in dorsal tissue of Korean quail was significantly higher than that in Beijing white quail (p < 0.01). Abundant cis-elements and a 346 bp CpG island were found in the promoter region of the MITF gene. The average methylation level of the CpG island was 22 (22%) in Korean quail, and 46 (30%) in Beijing white quail (p < 0.05).4. The hypermethylation of the MITF gene promoter region in Beijing white quail resulted in a decrease in expression level, which was related to white feather colour.

The lgi-miR-2d is Potentially Involved in Shell Melanin Synthesis by Targeting mitf in Manila Clam Ruditapes philippinarum

Shell color as an important economic trait is also the crucial target trait for breeding and production. MicroRNA (miRNA) is an endogenous small non-coding RNA that can post-transcriptionally regulate the expression of target genes, it plays important roles in many life activities and physiological processes, such as shell color, stress response, and disease traits. In this study, we investigated the function of lgi-miR-2d in shell melanin formation and the expression patterns of lgi-miR-2d and target gene Rpmitf in Manila clam Ruditapes philippinarum. We further explored and verified the relationship between Rpmitf and lgi-miR-2d and identified the expression level of shell color-related gene changes by RNAi and injecting the antagomir of lgi-miR-2d, respectively. Our results indicated that lgi-miR-2d antagomir affected the expression of its target gene Rpmitf. In addition, the dual-luciferase reporter assay was conducted to confirm the direct interaction between lgi-miR-2d and Rpmitf. The results showed that the expression levels of melanin-related genes such as Rpmitf and tyr were significantly decreased in the positive treatment group compared with the blank control group after the Rpmitf dsRNA injection, indicating Rpmitf plays a crucial role in the melanin synthesis pathway. Taken together, we speculated that lgi-miR-2d might be negatively modulating Rpmitf, which might regulate other shell color-related genes, thereby affecting melanin synthesis in R. philippinarum.

Anticancer Potential of Indole Phytoalexins and Their Analogues

Indole phytoalexins, found in economically significant Cruciferae family plants, are synthesized in response to pathogen attacks or stress, serving as crucial components of plant defense mechanisms against bacterial and fungal infections. Furthermore, recent research indicates that these compounds hold promise for improving human health, particularly in terms of potential anticancer effects that have been observed in various studies. Since our last comprehensive overview in 2016 focusing on the antiproliferative effects of these substances, brassinin and camalexin have been the most extensively studied. This review analyses the multifaceted pharmacological effects of brassinin and camalexin, highlighting their anticancer potential. In this article, we also provide an overview of the antiproliferative activity of new synthetic analogs of indole phytoalexins, which were synthesized and tested at our university with the aim of enhancing efficacy compared to the parent compound.

Anti-Melanogenic Effects of Cnidium monnieri Extract via p38 Signaling-Mediated Proteasomal Degradation of Tyrosinase

Cnidium monnieri fructus is widely used in traditional Oriental medicine for treating female genital disorders, male impotence, frigidity, and skin-related conditions in East Asia. However, the role of C. monnieri fructus extract (CMFE) in melanin synthesis is not well elucidated. This study aimed to investigate the anti-melanogenesis effect and mechanism of action of CMFE in α-MSH-stimulated B16F10 cells. Intracellular melanin content and tyrosinase activity were measured in α-MSH-stimulated B16F10 cells treated with various concentrations of CMFE (0.5-5 μg/mL). mRNA and protein levels of tyrosinase and MITF were evaluated using qRT-PCR and ting. CMFE's effect on the proteasomal degradation of tyrosinase was confirmed using a proteasomal degradation inhibitor, MG132. CMFE treatment activated p38, a protein associated with proteasomal degradation. Treatment with CMFE at up to 5 μg/mL showed no significant cytotoxicity. CMFE significantly reduced α-MSH-stimulated melanin production (43.29 ± 3.55% decrease, p < 0.05) and cellular tyrosinase activity (31.14 ± 3.15% decrease, p < 0.05). Although mRNA levels of MITF and tyrosinase increased, CMFE suppressed tyrosinase protein levels. The suppressive effect of CMFE on tyrosinase protein was blocked by MG132. CMFE inhibited melanogenesis by promoting the proteasome degradation of tyrosinase through p38 activation. These findings suggest that CMFE has the potential to be a natural whitening agent for inhibiting melanogenesis.

Hybrid protein microspheres and their responsive release behaviors and inhibitory effects on melanin synthesis

In this study, the formation of protein microspheres through lysosomal enzyme-assisted biomineralized crystallization was demonstrated. Spherical micro-sized hybrid CaCO3 constructs were synthesized and characterized using field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and particle size analysis. Additionally, parameters such as the Brunauer-Emmett-Teller surface area and single-point total pore volume, and adsorption/desorption analysis were used to investigate the mesoporous properties, which are advantageous for lysosomal enzyme (LE) loading. A LE can be used as an organic template, not only as a morphological controller but also for entrapping LE during the crystallization pathway. The hybrid protein microspheres accommodated 2.3 mg of LE with a 57% encapsulation efficiency and 5.1 wt% loading. The peroxidase activity of the microspheres was calculated and found to be approximately 0.0238 mM-1 min-1. pH-responsive release of the LE from CaCO3 was observed, suggesting potential biomedical and cosmetic applications in acidic environments. The hybrid LE microsphere treatment significantly alleviated melanin production in a dose-dependent manner and further downregulated the mRNA expression of MITF, tyrosinase, TYRP-1, and TYRP-2. These results indicate skin-whitening effects by inhibiting melanin without inducing cytotoxicity. The data provide the first evidence of the potential use of a LE for obtaining hybrid minerals and the effectiveness of biomineralization-based sustainable delivery of enzyme-based vehicles based on organelle-extract-assisted biomineralization.

Tricholoma matsutake polysaccharides suppress excessive melanogenesis via JNK-mediated pathway: Investigation in 8- methoxypsoralen induced B16-F10 melanoma cells and clinical study

Skin hyperpigmentation is a worldwide condition associated with augmented melanogenesis. However, conventional therapies often entail various adverse effects. Here, we explore the safety range and depigmentary effects of polysaccharides extract of Tricholoma matsutake (PETM) in an in vitro model and further evaluated its efficacy at the clinical level. An induced-melanogenesis model was established by treating B16-F10 melanoma cells with 8-methoxypsoralen (8-MOP). Effects of PETM on cell viability and melanin content were examined and compared to a commonly used depigmentary agent, α-arbutin. Expressions of key melanogenic factors and upstream signaling pathway were analysed by quantitative PCR and western blot. Moreover, a placebo-controlled clinical study involving Chinese females with skin hyperpigmentation was conducted to measure the efficacy of PETM on improving facial pigmented spots, melanin index, and individual typology angle (ITA°). Results demonstrated that PETM (up to 0.5 mg/mL) had little effect on the viability and motility of B16-F10 cells. Notably, it significantly suppressed the melanin content and expressions of key melanogenic factors induced by 8-MOP in B16-F10 melanoma cells. Western blotting results revealed that PETM inhibited melanogenesis by inactivating c-Jun N-terminal kinase (JNK), and this inhibitory role could be rescued by JNK agonist treatment. Clinical findings showed that PETM treatment resulted in a significant reduction of facial hyperpigmented spot, decreased melanin index, and improved ITA° value compared to the placebo-control group. In conclusion, these in vitro and clinical evidence demonstrated the safety and depigmentary efficacy of PETM, a novel polysaccharide agent. The distinct mechanism of action of PETM on melanogenic signaling pathway positions it as a promising agent for developing alternative therapies.

Inhibitory Effects of Fermented Sprouted Oat Extracts on Oxidative Stress and Melanin Overproduction

Hyperpigmentation occurs due to irregular secretion of melanin pigment in the skin. This can affect quality of life depending on its severity, so prevention and management are essential. Oats (Avena sativa L.), a grain consumed worldwide, are known to offer improved health benefits upon germination and fermentation. This study is aimed to investigate the protective effects of lactobacilli-fermented sprouted oat extracts on oxidative stress and melanin overproduction in vitro. The anti-melanogenic effect was investigated using melanin content and tyrosinase activity assays in B16F10 cells, as well as a mushroom tyrosinase-based enzyme inhibition assay. The results showed that L. casei-fermented oat extracts were the most effective for reducing melanin formation by reducing the mRNA expression of microphthalmia-associated transcription factor, tyrosinase, and tyrosinase-related protein 2. Furthermore, L. casei fermentation was effective in improving the total phenolic, flavonoid, and avenanthramide A contents of sprouted oat extracts. The results also demonstrated the antioxidant effects of L. casei-fermented sprouted oat extracts in promoting DPPH radical-scavenging activity, superoxide dismutase-like activity, and reduction in reactive oxygen species levels. Overall, the findings indicate that fermented sprouted oat extracts are promising candidates for antioxidant and anti-hyperpigmentation treatments.

Comparative Analysis of Olive-Derived Phenolic Compounds' Pro-Melanogenesis Effects on B16F10 Cells and Epidermal Human Melanocytes

Olive leaf contains plenty of phenolic compounds, among which oleuropein (OP) is the main component and belongs to the group of secoiridoids. Additionally, phenolic compounds such as oleocanthal (OL) and oleacein (OC), which share a structural similarity with OP and two aldehyde groups, are also present in olive leaves. These compounds have been studied for several health benefits, such as anti-cancer and antioxidant effects. However, their impact on the skin remains unknown. Therefore, this study aims to compare the effects of these three compounds on melanogenesis using B16F10 cells and human epidermal cells. Thousands of gene expressions were measured by global gene expression profiling with B16F10 cells. We found that glutaraldehyde compounds derived from olive leaves have a potential effect on the activation of the melanogenesis pathway and inducing differentiation in B16F10 cells. Accordingly, the pro-melanogenesis effect was investigated by means of melanin quantification, mRNA, and protein expression using human epidermal melanocytes (HEM). This study suggests that secoiridoid and its derivates have an impact on skin protection by promoting melanin production in both human and mouse cell lines.

3D Artificial Skin Platform for Investigating Pregnancy-Related Skin Pigmentation

In this study, we created a 3D Artificial Skin Platform that can be used for the treatment of pigmentation by artificially realizing the skin of pregnant women. For the stable realization of 3D artificial skin, a bilayer hydrogel composed of collagen type I and fibrin was designed and applied to the study to reduce the tension-induced contraction of collagen type I, the extracellular matrix (ECM) of artificial skin, by dynamic culture. Oxygen concentration and 17β-Estradiol (E2) concentration, which are highly related to melanin production, were selected as parameters of the pregnancy environment and applied to cell culture. Oxygen concentration, which is locally reduced in the first trimester (2.5-3%), and E2, which is upregulated in the third trimester, were applied to the cell culture process. We analyzed whether the 3D artificial skin implemented in the 3D Artificial Skin Platform could better represent the tendency of melanin expression in pregnant women than cells cultured under the same conditions in 2D. The expression levels of melanin and melanin-related genes in the 2D cell culture did not show a significant trend that was similar to the melanin expression trend in pregnant women. However, the 3D artificial skin platform showed a significant trend towards a 2-6-fold increase in melanin expression in response to low oxygen concentrations (2.5%) and E2 concentrations (17 ng/mL), which was similar to the trend in pregnant women in vivo. These results suggest that 3D artificial skin cultured on the Artificial Skin Platform has the potential to be used as a substitute for human pregnant skin in various research fields related to the treatment of pigmentation.

The potential role of ubiquitination and deubiquitination in melanogenesis

Melanogenesis is a critical biochemical process in which melanocytes produce melanin, a crucial element involved in the formation of coat colour in mammals. According to several earlier studies, melanocytes' post-translational modifications of proteins primarily control melanogenesis. Among the many post-translational changes that can affect melanin production, ubiquitination and deubiquitination can keep melanin production going by changing how proteins that are related to melanin are broken down or kept stable. Ubiquitination and deubiquitination maintain ubiquitin homeostasis, which is a highly dynamic process in balance under the action of E3 ubiquitin ligase and deubiquitinating enzymes. However, the regulatory mechanisms underlying ubiquitination and deubiquitination in melanogenesis are yet to be thoroughly investigated. As a result, there has been a growing focus on exploring the potential correlation between melanogenesis, ubiquitination and deubiquitination. This study discusses the mechanisms of ubiquitination and deubiquitination in the context of melanogenesis, a crucial process for enhancing mammalian coat coloration and addressing pigment-related diseases.

Anti-Melanogenic Effects of Lilium lancifolium Root Extract via Downregulation of PKA/CREB and MAPK/CREB Signaling Pathways in B16F10 Cells

Hyperpigmentation disorders causing emotional distress require the topical use of depigmenting agents of natural origin. In this study, the anti-melanogenic effects of the Lilium lancifolium root extract (LRE) were investigated in B16F10 cells. Consequently, a non-cytotoxic concentration of the extract reduced intracellular melanin content and tyrosinase activity in a dose-dependent manner, correlating with the diminished expression of core melanogenic enzymes within cells. LRE treatment also inhibited cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB)/microphthalmia-associated transcription factor signaling, which regulates the expression of tyrosinase-related genes. Upon examining these findings from a molecular mechanism perspective, LRE treatment suppressed the phosphorylation of protein kinase A (PKA), p38, and extracellular signal-related kinase (ERK), which are upstream regulators of CREB. In addition, L-phenylalanine and regaloside A, specifically identified within the LRE using liquid chromatography-mass spectrometry, exhibited inhibitory effects on melanin production. Collectively, these results imply that LRE potentially suppresses cAMP-mediated melanogenesis by downregulating PKA/CREB and mitogen-activated protein kinase (MAPK)/CREB signaling pathways. Therefore, it can be employed as a novel therapeutic ingredient of natural origin to ameliorate hyperpigmentation disorders.

Whole Genome Resequencing Reveals Selection Signals Related to Wool Color in Sheep

Wool color is controlled by a variety of genes. Although the gene regulation of some wool colors has been studied in relative depth, there may still be unknown genetic variants and control genes for some colors or different breeds of wool that need to be identified and recognized by whole genome resequencing. Therefore, we used whole genome resequencing data to compare and analyze sheep populations of different breeds by population differentiation index and nucleotide diversity ratios (Fst and θπ ratio) as well as extended haplotype purity between populations (XP-EHH) to reveal selection signals related to wool coloration in sheep. Screening in the non-white wool color group (G1 vs. G2) yielded 365 candidate genes, among which PDE4B, GMDS, GATA1, RCOR1, MAPK4, SLC36A1, and PPP3CA were associated with the formation of non-white wool; an enrichment analysis of the candidate genes yielded 21 significant GO terms and 49 significant KEGG pathways (p < 0.05), among which 17 GO terms and 21 KEGG pathways were associated with the formation of non-white wool. Screening in the white wool color group (G2 vs. G1) yielded 214 candidate genes, including ABCD4, VSX2, ITCH, NNT, POLA1, IGF1R, HOXA10, and DAO, which were associated with the formation of white wool; an enrichment analysis of the candidate genes revealed 9 significant GO-enriched pathways and 19 significant KEGG pathways (p < 0.05), including 5 GO terms and 12 KEGG pathways associated with the formation of white wool. In addition to furthering our understanding of wool color genetics, this research is important for breeding purposes.

Biogenic Imaging Contrast Agents

Imaging contrast agents are widely investigated in preclinical and clinical studies, among which biogenic imaging contrast agents (BICAs) are developing rapidly and playing an increasingly important role in biomedical research ranging from subcellular level to individual level. The unique properties of BICAs, including expression by cells as reporters and specific genetic modification, facilitate various in vitro and in vivo studies, such as quantification of gene expression, observation of protein interactions, visualization of cellular proliferation, monitoring of metabolism, and detection of dysfunctions. Furthermore, in human body, BICAs are remarkably helpful for disease diagnosis when the dysregulation of these agents occurs and can be detected through imaging techniques. There are various BICAs matched with a set of imaging techniques, including fluorescent proteins for fluorescence imaging, gas vesicles for ultrasound imaging, and ferritin for magnetic resonance imaging. In addition, bimodal and multimodal imaging can be realized through combining the functions of different BICAs, which helps overcome the limitations of monomodal imaging. In this review, the focus is on the properties, mechanisms, applications, and future directions of BICAs.

Atractylodes lancea rhizome derived exosome-like nanoparticles prevent alpha-melanocyte stimulating hormone-induced melanogenesis in B16-F10 melanoma cells

Aberrant melanin overproduction can significantly impact an individual's appearance and cause mental and psychological distress. Current inhibitors of melanin production exert harmful side effects due to inadequate selectivity; thus a need to develop more selective melanin synthesis inhibitors is necessary. Extracellular vesicles are important agents of intercellular signalling in prokaryotes and eukaryotes. Recently, plant-derived nanoparticles, similar to mammalian exosomes, have attracted attention for their use in health research. In this study, to investigate the potential of plant-derived exosome-like nanoparticles (ELNs) as inhibitors of melanin production, we used hot water to extract ELNs from the rhizome of Atractylodes lancea (A-ELNs). The size of A-ENLs ranged from 34 to 401 nm and carried three microRNA: ath-miR166f, ath-miR162a-5p, and ath-miR162b-5p. These A-ENLs were applied to B16-F10 melanoma cells treated with α-melanocyte-stimulating hormone (α-MSH). After A-ELNs were taken up by B16-F10 cells, their melanin levels were significantly reduced. Furthermore, A-ELNs significantly reduced tyrosinase activity in B16-F10 cells and mRNA expression of microphthalmia-associated transcription factor (Mitf), tyrosinase, tyrosinase-related protein 1, and DOPA chrome tautomerase. These results suggest that A-ELN suppresses melanogenic enzymes expression by downregulating Mitf, thereby inhibiting melanin synthesis. Hence, A-ELN can be developed into a novel topical drug after additional studies and optimization.

Effects of SLC45A2 and GPNMB on Melanin Deposition Based on Transcriptome Sequencing in Chicken Feather Follicles

As an essential genetic and economic trait, chicken feather color has long been an important research topic. To further understand the mechanism of melanin deposition associated with coloration in chicken feathers, we selected feather follicle tissues from the neck and wings of chickens with differently colored feathers (yellow, sub-Columbian, and silver) for transcriptome analysis. We focused on genes that were expressed in both the wings and neck and were expressed with the same trends in breeds with two different plumage colors, specifically, SLC45A2, GPNMB, MLPH, TYR, KIT, WNT11, and FZD1. GO and KEGG enrichment analyses showed the DEGs were enriched in melanin-related pathways, such as tyrosine metabolic pathway and melanogenesis, and PPI analysis highlighted the genes SLC45A2 and GPNMB as associated with melanin deposition. Verification experiments in chicken melanocytes demonstrated that these two genes promote melanocyte melanin deposition. These data enrich our knowledge of the mechanisms that regulate chicken feather color.

The Essential Role of microRNAs in Inflammatory and Autoimmune Skin Diseases-A Review

The etiopathogenesis of autoimmune skin diseases is complex and still not fully understood. The role of epigenetic factors is emphasized in the development of such diseases. MicroRNAs (miRNAs), a group of non-coding RNAs (ncRNAs-non-coding RNAs), are one of the important post-transcriptional epigenetic factors. miRNAs have a significant role in the regulation of the immune response by participating in the process of the differentiation and activation of B and T lymphocytes, macrophages, and dendritic cells. Recent advances in research on epigenetic factors have provided new insights into the pathogenesis and potential diagnostic and therapeutic targets of many pathologies. Numerous studies revealed a change in the expression of some microRNAs in inflammatory skin disorders, and the regulation of miRNA expression is a promising therapeutic goal. This review presents the state of the art regarding changes in the expression and role of miRNAs in inflammatory and autoimmune skin diseases, including psoriasis, atopic dermatitis, vitiligo, lichen planus, hidradenitis suppurativa, and autoimmune blistering diseases.

The Potential of Algae in the Nutricosmetic Sector

Seaweeds or algae are marine autotrophic organisms. They produce nutrients (e.g., proteins, carbohydrates, etc.) essential for the survival of living organisms as they participate in biochemical processes and non-nutritive molecules (such as dietary fibers and secondary metabolites), which can improve their physiological functions. Seaweed polysaccharides, fatty acids, peptides, terpenoids, pigments, and polyphenols have biological properties that can be used to develop food supplements and nutricosmetic products as they can act as antibacterial, antiviral, antioxidant, and anti-inflammatory compounds. This review examines the (primary and secondary) metabolites produced by algae, the most recent evidence of their effect on human health conditions, with particular attention to what concerns the skin and hair's well-being. It also evaluates the industrial potential of recovering these metabolites from biomass produced by algae used to clean wastewater. The results demonstrate that algae can be considered a natural source of bioactive molecules for well-being formulations. The primary and secondary metabolites' upcycling can be an exciting opportunity to safeguard the planet (promoting a circular economy) and, at the same time, obtain low-cost bioactive molecules for the food, cosmetic, and pharmaceutical industries from low-cost, raw, and renewable materials. Today's lack of methodologies for recovering bioactive molecules in large-scale processes limits practical realization.

Genome-Wide Association Study Reveals the Genetic Basis of Duck Plumage Colors

Plumage color is an artificially and naturally selected trait in domestic ducks. Black, white, and spotty are the main feather colors in domestic ducks. Previous studies have shown that black plumage color is caused by MC1R, and white plumage color is caused by MITF. We performed a genome-wide association study (GWAS) to identify candidate genes associated with white, black, and spotty plumage in ducks. Two non-synonymous SNPs in MC1R (c.52G>A and c.376G>A) were significantly related to duck black plumage, and three SNPs in MITF (chr13:15411658A>G, chr13:15412570T>C and chr13:15412592C>G) were associated with white plumage. Additionally, we also identified the epistatic interactions between causing loci. Some ducks with white plumage carry the c.52G>A and c.376G>A in MC1R, which also compensated for black and spotty plumage color phenotypes, suggesting that MC1R and MITF have an epistatic effect. The MITF locus was supposed to be an upstream gene to MC1R underlying the white, black, and spotty colors. Although the specific mechanism remains to be further clarified, these findings support the importance of epistasis in plumage color variation in ducks.

Coordinated microRNA/mRNA Expression Profiles Reveal Unique Skin Color Regulatory Mechanisms in Chinese Giant Salamander (Andrias davidianus)

The Chinese giant salamander (Andrias davidianus) has been increasingly popular in the aquaculture market in China in recent years. In the breeding process of Andrias davidianus, we found that some albino individuals were extremely rare and could not be inherited stably, which severely limits their commercialization in the aquaculture market. In this study, we performed transcriptome and small RNA (sRNA) sequencing analyses in the skin samples of wild-type (WT) and albino (AL) Andrias davidianus. In total, among 5517 differentially expressed genes (DEGs), 2911 DEGs were down-regulated in AL, including almost all the key genes involved in melanin formation. A total of 25 miRNAs were differentially expressed in AL compared to WT, of which 17 were up-regulated. Through the integrated analysis, no intersection was found between the target genes of the differentially expressed miRNAs and the key genes for melanin formation. Gene Ontology (GO) and KEGG pathway analyses on DEGs showed that these genes involved multiple processes relevant to melanin synthesis and the key signal pathway MAPK. Interestingly, the transcription factors SOX10 and PAX3 and the Wnt signaling pathway that play a key role in other species were not included, while the other two transcription factors in the SOX family, SOX21 and SOX7, were included. After analyzing the key genes for melanin formation, it was interesting to note an alternative splicing form of the MITF in WT and a critical mutation of the SLC24A5 gene in AL, which might be the main reason for the skin color change of Andrias davidianus. The results contributed to understanding the molecular mechanism of skin pigmentation in Andrias davidianus and accelerating the acquisition process of individuals with specific body colors by genetic means.

Methoxyflavones from Black Ginger (Kaempferia parviflora Wall. ex Baker) and their Inhibitory Effect on Melanogenesis in B16F10 Mouse Melanoma Cells

Kaempferia parviflora Wall. ex Baker (Zingiberaceae), commonly known as Thai ginseng or black ginger, is a tropical medicinal plant in many regions. It has been traditionally used to treat various ailments, including ulcers, dysentery, gout, allergies, abscesses, and osteoarthritis. As part of our ongoing phytochemical study aimed at discovering bioactive natural products, we investigated potential bioactive methoxyflavones from K. parviflora rhizomes. Phytochemical analysis aided by liquid chromatography-mass spectrometry (LC-MS) led to the isolation of six methoxyflavones (1-6) from the n-hexane fraction of the methanolic extract of K. parviflora rhizomes. The isolated compounds were structurally determined to be 3,7-dimethoxy-5-hydroxyflavone (1), 5-hydroxy-7-methoxyflavone (2), 7,4'-dimethylapigenin (3), 3,5,7-trimethoxyflavone (4), 3,7,4'-trimethylkaempferol (5), and 5-hydroxy-3,7,3',4'-tetramethoxyflavone (6), based on NMR data and LC-MS analysis. All of the isolated compounds were evaluated for their anti-melanogenic activities. In the activity assay, 7,4'-dimethylapigenin (3) and 3,5,7-trimethoxyflavone (4) significantly inhibited tyrosinase activity and melanin content in IBMX-stimulated B16F10 cells. In addition, structure-activity relationship analysis revealed that the methoxy group at C-5 in methoxyflavones is key to their anti-melanogenic activity. This study experimentally demonstrated that K. parviflora rhizomes are rich in methoxyflavones and can be a valuable natural resource for anti-melanogenic compounds.

A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics

The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.

Rapid screening of novel tyrosinase inhibitory peptides from a pearl shell meat hydrolysate by molecular docking and the anti-melanin mechanism

Pearls are an edible and medicinal resource with whitening activity and nutritional value in China. In the previous study, we found that the pearl shell meat hydrolysate showed dual activities of antioxidation and tyrosinase inhibition, which were similar to the activities of pearls. In this research, a pearl shell meat hydrolysate was isolated, identified and screened by molecular docking, and three peptides FLF, SPSSS and WLL with high tyrosinase inhibitory activities were obtained. The results indicated that FLF, SPSSS and WLL could effectively inhibit tyrosinase activities and the inhibition rates (1.0 mg mL^-1) were 54.32%, 65.26% and 57.50%, respectively. The results of a zebrafish whitening experiment showed that the tyrosinase activities of zebrafish treated with FLF, SPSSS and WLL decreased by 75.41%, 62.87% and 64.99% (p < 0.05), respectively, and the melanin content decreased by 37.34%, 38.52% and 40.39% (p < 0.05), respectively. In a B16F10 cell whitening experiment, compared with a control group, FLF, SPSSS and WLL also showed a significant whitening effect, the tyrosinase activities decreased by 84.08%, 79.08% and 77.45% (p < 0.05), respectively, and the melanin content decreased by 42.23%, 34.37% and 34.02% (p < 0.05), respectively. Moreover, the active peptides could act on three signal pathways including Wnt/β-catenin, MAPK and MC1R/α-MSH and significantly downregulated the expressions of the signaling factors WNT4, MITF, β-catenin, ERK, JNK, TRP1 and TRP2 (p < 0.05). The results demonstrated that the whitening active peptides were edible natural antioxidants, tyrosinase inhibitors and skin anti-melanin agents, which could be added to functional foods as food ingredients.

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.

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 (3513 bp) 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.

Brassinin Abundant in Brassicaceae Suppresses Melanogenesis through Dual Mechanisms of Tyrosinase Inhibition

Brassinin is a phytoalexin abundant in plants, especially in cabbage, and has been reported to act as an anti-cancer and anti-inflammatory agent. However, limited studies are available to elucidate the functionalities of brassinin. Here, we tested the effects of brassinin on melanogenesis using cell-free and cell-based biochemical analysis and docking simulation. Cell-free experiments exhibited that brassinin has antioxidant and anti-tyrosinase activities. When applied to B16F10 cells stimulated with a melanogenesis inducer α-MSH, brassinin pretreatment significantly reduced melanin accumulation and cellular tyrosinase activity. Docking simulation indicates that the docking score of brassinin to the binding pocket of tyrosinase is better than that of kojic acid or arbutin, anti-melanogenic positive controls, indicating that brassinin inhibits melanogenesis at least partially by binding to and inactivating tyrosinase. In addition, qPCR results showed that brassinin reduced tyrosinase mRNA levels. Together, these results suggest that brassinin exerts anti-melanogenesis effects by inhibiting both the activity and mRNA expression levels of tyrosinase. Therefore, our study showed that brassinin has the potential to be used in pharmaceutical or cosmetic products for depigmentation.

MITF Contributes to the Body Color Differentiation of Sea Cucumbers Apostichopus japonicus through Expression Differences and Regulation of Downstream Genes

Melanin, which is a pigment produced in melanocytes, is an important contributor to sea cucumber body color. MITF is one of the most critical genes in melanocyte development and melanin synthesis pathways. However, how MITF regulates body color and differentiation in sea cucumbers is poorly understood. In this study, we analyzed the expression level and location of MITF in white, purple, and green sea cucumbers and identified the genes regulated by MITF using chromatin immunoprecipitation followed by sequencing. The mRNA and protein expression levels of MITF were all highest in purple morphs and lowest in white morphs. In situ hybridization indicated that MITF mRNA were mainly expressed in the epidermis. We also identified 984, 732, and 1191 peaks of MITF binding in green, purple, and white sea cucumbers, which were associated with 727, 557, and 887 genes, respectively. Our findings suggested that MITF contributed to the body color differentiation of green, purple, and white sea cucumbers through expression differences and regulation of downstream genes. These results provided a basis for future studies to determine the mechanisms underlying body color formation and provided insights into gene regulation in sea cucumbers.

Comparative transcriptome and miRNA analysis of skin pigmentation during embryonic development of Chinese soft-shelled turtle (Pelodiscus sinensis)

BACKGROUND

Aquatic animals show diverse body coloration, and the formation of animal body colour is a complicated process. Increasing evidence has shown that microRNAs (miRNAs) play important regulatory roles in many life processes. The role of miRNAs in pigmentation has been investigated in some species. However, the regulatory patterns of miRNAs in reptile pigmentation remain to be elucidated. In this study, we performed an integrated analysis of miRNA and mRNA expression profiles to explore corresponding regulatory patterns in embryonic body colour formation in the soft-shelled turtle Pelodiscus sinensis.

RESULTS

We identified 8 866 novel genes and 9 061 mature miRNAs in the skin of Chinese soft-shelled turtles in three embryonic stages (initial period: IP, middle period: MP, final period: FP). A total of 16 563 target genes of the miRNAs were identified. Furthermore, we identified 2 867, 1 840 and 4 290 different expression genes (DEGs) and 227, 158 and 678 different expression miRNAs (DEMs) in IP vs. MP, MP vs. FP, and IP vs. FP, respectively. Among which 72 genes and 25 miRNAs may be related to turtle pigmentation in embryonic development. Further analysis of the novel miRNA families revealed that some novel miRNAs related to pigmentation belong to the miR-7386, miR-138, miR-19 and miR-129 families. Novel_miR_2622 and novel_miR_2173 belong to the miR-19 family and target Kit and Gpnmb, respectively. The quantification of novel_miR_2622 and Kit revealed negative regulation, indicating that novel_miR_2622 may participate in embryonic pigmentation in P. sinensis by negatively regulating the expression of Kit.

CONCLUSIONS

miRNA act as master regulators of biological processes by controlling the expression of mRNAs. Considering their importance, the identified miRNAs and their target genes in Chinese soft-shelled turtle might be useful for investigating the molecular processes involved in pigmentation. All the results of this study may aid in the improvement of P. sinensis breeding traits for aquaculture.

Study on the Mechanism of miR-125b-5p Affecting Melanocyte Biological Behavior and Melanogenesis in Vitiligo through Regulation of MITF

OBJECTIVE

The goal was to confirm the mechanism by which miR-125b-5p influences melanocyte biological behavior and melanogenesis in vitiligo by regulating MITF.

METHODS

oe-MITF, sh-MITF, miR-125b-5p mimic, NC-mimic, NC-inhibitor, and miR-125b-5p inhibitor were transfected into cells by cell transfection. Western blotting was used to detect the related protein expression, qRT-PCR was used to detect miR-125b-5p and MITF expression, immunohistochemistry was used to detect the MITF-positive cells in vitiligo patients tissues, and a dual-luciferase reporter system was used to detect the target of miR-125b-5p and MITF. PIG1 and PIG3V cell proliferation by the CCK-8 method, cell cycle progression and apoptosis by flow cytometry, apoptosis was detected by TUNEL, Tyr activity and melanin content were measured using Tyr and melanin content assay kits.

RESULTS

Compared with the healthy control group, the expression of miR-125b-5p in the tissues and serum of vitiligo patients was upregulated, and the expression of MITF was downregulated; compared with PIG1 cells, the expression of miR-125b-5p and MITF in the PIG3V group was consistent with the above. Compared with the NC-minic group, the cell proliferation activity of the miR-125b-5p mimic group decreased, apoptosis increased, and the expression levels of melanogenesis-related proteins Tyr, Tyrp1, Tyrp2, and DCT were downregulated. Compared with the NC-inhibitor group, the above indices in the miR-125b-5p inhibitor group were all opposite to those in the miR-125b-5p mimic group. Transfection of oe-MITF into the miR-125b-5p mimic group reversed the effect of the miR-125b-5p mimic, while transfection of sh-MITF enhanced the effect of the miR-125b-5p mimic.

CONCLUSION

miR-125b-5p affects vitiligo melanocyte biological behavior and melanogenesis by downregulating MITF expression.