Signaling Pathways in Melanogenesis

Gut Microbiome-Driven metabolites influence skin pigmentation in TYRP1 mutant Oujiang Color Common Carp

The gut microbiome plays a key role in regulating the gut-skin axis, and host genetics partially influence this regulation. The study investigated the role of gut microbiota and host genetics in the gut-skin axis, focusing on the unusual "coffee-like" color phenotype observed in TYRP1 mutant Oujiang Color Common Carp. We employed comparative high-throughput omics data from wild-type and mutant fish to quantify the influence of both genetics and gut microbes on skin transcriptomic expression and blood metabolites. We found 525 differential metabolites (DMs) and 45 distinct gut microbial genera in TYRP1 mutant fish compared to wild type. Interaction and causal mediation analyses revealed a complex interplay. The TYRP1 mutation likely triggers an inflammatory pathway involving Acinetobacter bacteria, Leukotrience-C4 and Spermine. This inflammatory response appears to be counterbalanced by an anti-inflammatory cardiovascular genetic network. The net effect is the upregulation of COMT, PLG, C2, C3, F10, TDO2, MHC1, and SERPINF2, leading to unusual coffee-like coloration. This study highlights the intricate interplay between gut microbiota, host genetics, and metabolic pathways in shaping complex phenotypes.

The Pigmentation of Blue Light is Mediated by Both Melanogenesis Activation and Autophagy Inhibition through OPN3-TRPV1

Blue light, a high-energy radiation in the visible light spectrum, was recently reported to induce skin pigmentation. In this study, we investigated the involvement of TRPV1-mediated signaling along with OPN3 in blue light-induced melanogenesis, as well as its signaling pathway. Operating downstream target of OPN3 in blue light-induced melanogenesis, blue light activated TRPV1 and upregulated its expression, resulting in calcium influx. [Ca2+] induced activation of CaMKII and MAPK. It also downregulated clusterin expression, leading to the nuclear translocation of PAX3, ultimately affecting melanin synthesis. In addition, blue light interfered with autophagy-mediated regulation of melanosomes by decreasing not only the interaction between CLU and LC3B but the expression of ATF family. These findings demonstrate that the pigmenting effects of blue light are mediated by CaMKII- and MAPK-mediated signaling, as well as CLU-dependent inhibition of autophagy through OPN3-TRPV1-calcium influx, suggesting a new signaling pathway by which blue light regulates melanocyte biology. Furthermore, these results suggest that TRPV1 and CLU could be potential therapeutic targets for blue light-induced pigmentation due to prolonged exposure to blue light.

Germacrone, isolated from Curcuma wenyujin, inhibits melanin synthesis through the regulation of the MAPK signaling pathway

Abnormal melanin synthesis causes hyperpigmentation disorders, such as chloasma, freckles, and melanoma, which are highly multiple and prevalent. There were few reports on the anti-melanogenic effect of Curcuma wenyujin Y.H. Chen et C. Ling, and the bioactive compound has not been elucidated as well. The study aims to investigate the anti-melanogenic effect of C. wenyujin, and identify the bioactive compound, and further explore its underlying mechanism. Our results showed that the Petroleum ether fraction extracted from C. wenyujin rhizome had a significant anti-melanogenic effect, and germacrone isolated from it was confirmed as the major bioactive compound. To our data, germacrone significantly inhibited tyrosinase (TYR) activity, reduced melanosome synthesis, reduced dendrites formation of B16F10 cells, and melanosome transport to keratinocytes. Moreover, germacrone effectively decreased the hyperpigmentation in zebrafish and the skin of guinea pigs in vivo. Western-blot analysis showed that germacrone down-regulated the expression of TYR, TRP-1, TRP-2, Rab27a, Cdc42, and MITF proteins via the activation of the MAPK signaling pathway. Taken together, germacrone is an effective bioactive compound for melanogenesis inhibition. Our studies suggest that germacrone may be considered a potential candidate for skin whitening.

Photobiomodulation Using 830 nm Lighting-Emitting Diode Inhibits Melanogenesis via FOXO3a in Human Melanocyte

Photobiomodulation (PBM) using 830 nm light-emitting diode (LED) benefits tissue regeneration, wound healing and neural stimulation. However, there is not much exploration of its effect on melanocytes and ex vivo skin model. This study aims to investigate the mechanism behind the anti-melanogenic activity of 830 nm LED and provides evidence for its activity in human ex vivo skin model. Our results showed that 830 nm LED at fluences ranging from 5 to 20 J/cm2 inhibited melanosome maturation and reduced melanin content, tyrosinase activity and melanogenesis-related proteins. 830 nm LED inhibited the phosphorylation of AKT and its downstream FOXO3a, leading to nuclear translocation of FOXO3a. Furthermore, FOXO3a knockdown and AKT activator like SC79 could reverse the melanogenesis inhibition phenotype induced by 830 nm LED. In human ex vivo skin model, Fontana-Masson staining revealed a decrease in epidermal basal pigmentation after 830 nm LED irradiation. Taken together, 830 nm LED demonstrated the anti-melanogenic activity via FOXO3a.

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.

Hydrolyzed conchiolin protein inhibits melanogenesis through PKA/CREB and MEK/ERK signalling pathways

OBJECTIVE

Hydrolyzed conchiolin protein (HCP) derived from pearl and nacre extracts exerts skin-lightening effects; however, the underlying molecular mechanisms are not fully understood. Herein, we investigated the effect of HCP on melanogenesis and the signalling pathways involved.

METHODS

B16F10 cells and PIG cells were treated with HCP to verify its ability to inhibit melanin. Western Blot, immunofluorescence, and flow cytometry methods were performed to investigate the effect of HCP on melanogenesis signalling pathway proteins. The inhibitors were used to further validate the effect of HCP on PKA/CREB and MEK/ERK signalling pathways. To further evaluate the whitening ability of HCP, changes in melanin were detected using 3D melanin skin model and zebrafish model.

RESULTS

HCP was found to significantly inhibit melanin synthesis and decrease the expression of melanogenesis-related proteins, such as microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein-2, in a dose-dependent manner. Additionally, we revealed that HCP suppresses melanogenesis via the regulation of the PKA/cAMP response element-binding (CREB) and MEK/extracellular signalling-regulated kinase (ERK) signalling pathways. Using 3D melanin skin models, we demonstrated that HCP can achieve skin-lightening effects by improving apparent chroma, increasing apparent brightness, and inhibiting melanin synthesis. Furthermore, HCP exhibits skin-whitening effects in a zebrafish model.

CONCLUSION

These results suggest that HCP suppresses the melanogenesis signalling cascade by inhibiting the PKA/CREB, MEK/ERK signalling pathway and downregulating MITF and its downstream signalling pathways, resulting in decreased melanin synthesis. In summary, HCP is a potential anti-pigmentation agent with promising applications in cosmetics and pharmaceutical products.

The role of regulatory T cells in vitiligo and therapeutic advances: a mini-review

BACKGROUND

Regulatory T cells (Tregs) play vital roles in controlling immune reactions and maintaining immune tolerance in the body. The targeted destruction of epidermal melanocytes by activated CD8+T cells is a key event in the development of vitiligo. However, Tregs may exert immunosuppressive effects on CD8+T cells, which could be beneficial in treating vitiligo.

METHODS

A comprehensive search of PubMed and Web of Science was conducted to gather information on Tregs and vitiligo.

RESULTS

In vitiligo, there is a decrease in Treg numbers and impaired Treg functions, along with potential damage to Treg-related signaling pathways. Increasing Treg numbers and enhancing Treg function could lead to immunosuppressive effects on CD8+T cells. Recent research progress on Tregs in vitiligo has been summarized, highlighting various Treg-related therapies being investigated for clinical use. The current status of Treg-related therapeutic strategies and potential future directions for vitiligo treatment are also discussed.

CONCLUSIONS

A deeper understanding of Tregs will be crucial for advancing Treg-related drug discovery and treatment development in vitiligo.

Examination of wnt signaling mediated melanin transport and shell color formation in Pacific oyster (Crassostrea gigas)

Mollusca exhibit remarkable diversity in shell coloration, attributed to the presence of melanin, a widely distributed pigment with various essential roles, such as mechanical strengthening, antioxidation and thermoregulation. However, the regulatory network governing melanogenesis and melanin transport in molluscs remains poorly understood. In this study, we conducted a systematic analysis of melanin distribution and transport in the Pacific oyster, utilizing light microscopy and high-resolution transmission electron microscopy. In addition, we characterized CgWnt1 and CgWnt2b-a in Crassostrea gigas, and analyzed Wnt signaling in melanocyte formation. Expression analysis revealed that these genes were predominantly expressed in the mantle of black-shelled individuals, particularly in the outer fold of the mantle. Furthermore, we employed RNA interference and inhibitors to specifically inhibit Wnt signaling in both in vivo and in vitro. The results revealed impaired melanogenesis and diminished tyrosinase activity upon Wnt signaling inhibition. These findings suggest the crucial role of Wnt ligands and downstream factors in melanogenesis. In summary, our study provides valuable insights into the regulatory mechanism of shell pigmentation in C. gigas. By demonstrating the promotion of melanogenesis through Wnt signaling modulation, we contribute to a better understanding of the complex processes underlying molluscan melanin production and shell coloration.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-024-00221-5.

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.

Prenylated flavonoids from Sophora flavescens inhibit mushroom tyrosinase activity and modulate melanogenesis in murine melanoma cells and zebrafish

Background: Sophora flavescens, a traditional Chinese medicine for treating conditions associated with abnormal skin pigmentation, contains flavonoids with inhibitory effects on tyrosinase. However, their mechanisms of action and their modulatory effects on melanogenesis remain unclear. Methods: Herein, a group of prenylated flavonoids was identified from S. flavescens extracts and their inhibitory activities on mushroom tyrosinase were evaluated. The anti-melanogenesis effects of these prenylated flavonoids were investigated in cellular (with murine melanoma cells) and animal (with zebrafish) models. Results: Prenylated flavonoids including isoanhydroicaritin (IAI), kurarinone (KR), and sophoraflavanone G (SG) were the major active constituents in S. flavescens extracts with anti-tyrosinase activity (IC50 = 0.7, 7.1, and 6.7 μM, respectively). Enzyme kinetic assays showed that IAI, KR, and SG had a mixed type of tyrosinase inhibition, supported by data from computational docking. Notably, KR at concentrations of 5 and 10 μM enhanced intracellular tyrosinase activity and stimulated melanin production in B16F10 cells, whereas SG and IAI did not exhibit significant activity. Further studies with the zebrafish model showed that IAI (80 and 160 μM) inhibited melanin biosynthesis by about 30.0% while KR (20 μM) stimulated melanogenesis by 36.9%. Furthermore, a zebrafish depigmentation model supported the anti-melanogenesis effect of IAI (80 and 160 μM) by 33.0% and 34.4%, respectively. Conclusion: In summary, IAI was identified as a tyrosinase inhibitor with an anti-melanogenic effect and KR was an enhancer for melanin production in B16F10 cells and zebrafish. Findings from the current study suggest that IAI and KR from S. flavescens may exert contrasting effects in the modulation of melanin production, providing important insights into the development of S. flavescens as a cosmeceutical or medicinal ingredient.

Predictive accuracy of genetic variants for eye color in a Kazakh population using the IrisPlex system

OBJECTIVE

This study assesses the accuracy of the IrisPlex system, a genetic eye color prediction tool for forensic analysis, in the Kazakh population. The study compares previously published genotypes of 515 Kazakh individuals from varied geographical and ethnohistorical contexts with phenotypic data on their eye color, introduced for the first time in this research.

RESULTS

The IrisPlex panel's effectiveness in predicting eye color in the Kazakh population was validated. It exhibited slightly lower accuracy than in Western European populations but was higher than in Siberian populations. The sensitivity was notably high for brown-eyed individuals (0.99), but further research is needed for blue and intermediate eye colors. This study establishes IrisPlex as a useful predictive tool in the Kazakh population and provides a basis for future investigations into the genetic basis of phenotypic variations in this diverse population.

Unique feather color characteristics and transcriptome analysis of hair follicles in Liancheng White ducks

Avian feather color is a fascinating trait, and the genetic mechanism of duck plumage formation is still in the preliminary stage. In this study, feather color of Liancheng White ducks was analyzed by determination of melanin content and RNA-seq analysis. In this research, 9 ducks from Mallards (n = 3), Liancheng White (n = 3) and Pekin ducks (n = 3) were used by high performance liquid chromatography (HPLC) and Masson-Fontana staining to reveal the difference of feather melanin content. RNA-seq from 11 hair follicle tissues (1- and 8-wk-old) of Liancheng White ducks (n = 5) and Pekin ducks (n = 7) was used to analyze the candidate genes for the feather melanin synthesis, and Immunofluorescence experiment was used to show the protein expression in 6 black- and white-feathered ducks. Pectorale, skin, liver, fat, brain, heart, kidney, lung, spleen of an 8-wk-old black-feathered Mallard were collected for candidate gene expression. The results showed that the contents of feathers, beak, web melanin in Liancheng White ducks were higher than in Pekin ducks (p < 0.05). Melanin within hair follicles was located in the barb ridge and hair matrix of black feather duck, also we found that TYRP1, TYR, SOX10 genes were differentially expressed between Liancheng White and Pekin ducks (p < 0.05), and these genes were mainly expressed showed in duck skin tissues. This study revealed the unique feather color phenotype of Liancheng White duck shedding light on the transcriptome that underlies it.

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.

Gingivectomy-Gingivoplasty for Oral Physiological Melanosis Depigmentation: A Case Report Involving Human Papillomavirus

Gingiva hyperpigmentation resulting from physiological melanosis causes aesthetic discomfort and is usually perceived as a disease by patients because healthy attached gingiva is typically characterized by coral pink coloring with stippling and scalloped contours. When physiological melanosis compromises the aesthetics of smiling, it may induce insecurity in patients, who usually seek out alternatives for reducing or eliminating hyperpigmentation. We present a case report of a surgical procedure combining gingivectomy with gingivoplasty for the management of physiological melanosis. The surgical procedure was performed on a 40-year-old female patient with bilateral pigmentation in both arches. The results of the histological analysis confirm the diagnoses of melanotic macula, with papillary hyperplasia and cytopathic changes being suggestive of HPV infection, which was verified using an immunohistochemistry analysis based on the detection of a major capsid protein of HPV. Acceptable functional and aesthetic results were obtained for the patient without major discomfort during the postoperative period. In cases when HPV infection is present, long-term follow-up becomes necessary.

Exosomes Derived from Hypertrophic Scar Fibroblasts Suppress Melanogenesis in Normal Human Epidermal Melanocytes

Post-burn hypertrophic scars often exhibit abnormal pigmentation. Exosomes play important roles in maintaining normal physiological homeostasis and in the pathological development of diseases. This study investigated the effects of the exosomes derived from hypertrophic scar fibroblasts (HTSFs) on melanocytes, which are pigment-producing cells. Normal fibroblasts (NFs) and HTSFs were isolated and cultured from normal skin and hypertrophic scar (HTS) tissue. Both the NF- and HTSF-exosomes were isolated from a cell culture medium and purified using a column-based technique. The normal human epidermal melanocytes were treated with both exosomes at a concentration of 100 μg/mL at different times. The cell proliferation, melanin content in the medium, apoptotic factors, transcription factors, melanin synthesis enzymes, signaling, signal transduction pathways, and activators of transcription factors (STAT) 1, 3, 5, and 6 were investigated. Compared with the Dulbecco's phosphate-buffered saline (DPBS)-treated controls and NF-exosomes, the HTSF-exosomes decreased the melanocyte proliferation and melanin secretion. The molecular patterns of apoptosis, proliferation, melanin synthesis, Smad and non-Smad signaling, and STATs were altered by the treatment with the HTSF-exosomes. No significant differences were observed between the DPBS-treated control and NF-exosome-treated cells. HTSF-derived exosomes may play a role in the pathological epidermal hypopigmentation observed in patients with HTS.

Rapid discovery of natural skin-lightening ingredients based on an integrated screening strategy based on molecular docking and zebrafish model

BACKGROUND

Natural herbs have been widely considered a reservoir for skin-lightening ingredients, but discovery of the effective ingredients from herbs remains a large challenge.

AIM

This research aimed to rapidly identify compounds with skin-lightening activity in Chinese herbs.

METHODS

The structure information of herbal compounds was collected and selected from the open-source data. High throughput virtual screening (HTVS) and Extra precision (XP) docking modes were used to screen for compounds that could bind to the mushroom tyrosinase involved in melanin synthesis. Furthermore, molecular dynamics (MD) simulations were introduced to assess the binding stability of those compounds with the key target protein. The candidate compounds found by this kind of multidimensional molecular screening were finally tested for their ability to inhibit pigmentation and potential toxicity using an in vivo zebrafish animal model.

RESULTS

A Natural Compounds Database was established with 5616 natural compounds. Fourteen compounds with favorable binding capability were screened by the XP docking mode with mushroom tyrosinase and five compounds among them were found to have superior dynamic binding performance through MD simulations. Then the Zebrafish animal experiments revealed that two components, sennoside B (SB) and sennoside C (SC), could significantly inhibit melanogenesis rather than the other three compounds. Meanwhile, there were no obvious side effects observed in SB and SC about the morphology, heart rate, or body length of zebrafish.

CONCLUSION

A strategy for rapid screening of compounds with whitening activity has been established, and two potent skin-lightening compounds, SB and SC, have been identified from a vast library of herbal compounds. This study revealed that SB and SC have potential for topical use in skin lightening for the first time. The findings of this study would provide an important theoretical basis for the application of these two compounds in the cosmetic field in the future.

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.

Selection signatures of wool color in Gangba sheep revealed by genome-wide SNP discovery

BACKGROUND

Gangba sheep as a famous breed of Tibetan sheep, its wool color is mainly white and black. Gangba wool is economically important as a high-quality raw material for Tibetan blankets and Tibetan serge. However, relatively few studies have been conducted on the wool color of Tibetan sheep.

RESULTS

To fill this research gap, this study conducted an in-depth analysis of two populations of Gangba sheep (black and white wool color) using whole genome resequencing to identify genetic variation associated with wool color. Utilizing PCA, Genetic Admixture, and N-J Tree analyses, the present study revealed a consistent genetic relationship and structure between black and white wool colored Gangba sheep populations, which is consistent with their breed history. Analysis of selection signatures using multiple methods (FST, π ratio, Tajima's D), 370 candidate genes were screened in the black wool group (GBB vs GBW); among them, MC1R, MLPH, SPIRE2, RAB17, SMARCA4, IRF4, CAV1, USP7, TP53, MYO6, MITF, MC2R, TET2, NF1, JAK1, GABRR1 genes are mainly associated with melanin synthesis, melanin delivery, and distribution. The enrichment results of the candidate genes identified 35 GO entries and 19 KEGG pathways associated with the formation of the black phenotype. 311 candidate genes were screened in the white wool group (GBW vs GBB); among them, REST, POU2F1, ADCY10, CCNB1, EP300, BRD4, GLI3, and SDHA genes were mainly associated with interfering with the differentiation of neural crest cells into melanocytes, affecting the proliferation of melanocytes, and inhibiting melanin synthesis. 31 GO entries and 22 KEGG pathways were associated with the formation of the white phenotype.

CONCLUSIONS

This study provides important information for understanding the genetic mechanism of wool color in Gangba, and provides genetic knowledge for improving and optimizing the wool color of Tibetan sheep. Genetic improvement and selective breeding to produce wool of specific colors can meet the demand for a diversity of wool products in the Tibetan wool textile market.

Virtual screening of natural products to enhance melanogenosis

Natural products have long been an important source of inspiration for medicinal chemistry and drug discovery. In the cosmetic field, they remain the major elements of the composition and serve as marketing asset. Recent research showed the implication of salt-inducible kinases on the melanin production in skin via MITF regulation. Finding new potent modulators on such target could open the way to several cosmetic applications to attenuate visible signs of photoaging and improve the tan without sun. Since virtual screening can be a powerful tool for detecting hit compounds in the early stages of a drug discovery process, we applied this method on salt-inducible kinase 2 to discover potential interesting compounds. Here, we present the different steps from the construction of a database of natural products, to the validation of a docking protocol and the results of the virtual screening. Hits from the screening were tested in vitro to confirm their efficiency and results are discussed.

Xenopus as a model system for studying pigmentation and pigmentary disorders

Human pigmentary disorders encompass a broad spectrum of phenotypic changes arising from disruptions in various stages of melanocyte formation, the melanogenesis process, or the transfer of pigment from melanocytes to keratinocytes. A large number of pigmentation genes associated with pigmentary disorders have been identified, many of them awaiting in vivo confirmation. A more comprehensive understanding of the molecular basis of pigmentary disorders requires a vertebrate animal model where changes in pigmentation are easily observable in vivo and can be combined to genomic modifications and gain/loss-of-function tools. Here we present the amphibian Xenopus with its unique features that fulfill these requirements. Changes in pigmentation are particularly easy to score in Xenopus embryos, allowing whole-organism based phenotypic screening. The development and behavior of Xenopus melanocytes closely mimic those observed in mammals. Interestingly, both Xenopus and mammalian skins exhibit comparable reactions to ultraviolet radiation. This review highlights how Xenopus constitutes an alternative and complementary model to the more commonly used mouse and zebrafish, contributing to the advancement of knowledge in melanocyte cell biology and related diseases.

Introducing the model of repeated exposure of skin to antiseptics: Randomised pilot trial

INTRODUCTION

Intensified hand hygiene measures were recommended for preventing the spread of SARS-CoV-2. However, these measures can lead to skin damage and the development of hand eczema, particularly among health professionals.

OBJECTIVES

This pilot study aimed to evaluate the effects of repeated antiseptic use on healthy skin under controlled conditions and to assess the emollient use.

METHODS

Twelve healthy volunteers (nine females, age = 22.3 ± 2.8 years (mean ± SD), Fitzpatrick phototypes II and III) with no skin diseases were recruited. Antiseptic was applied daily for 3 weeks on the volar sides of forearms. Emollient cream was also applied daily. Skin assessments were performed using non-invasive methods (transepidermal water loss-TEWL, skin hydration, erythema and melanin content).

RESULTS

Prolonged antiseptic use increased TEWL, decreased hydration and elevated erythema and melanin levels. Emollient cream significantly reduced TEWL and improved hydration on antiseptic-treated sites, and also enhanced hydration on intact skin.

CONCLUSIONS

Prolonged use of antiseptics can have adverse effects on the skin, including barrier disruption and inflammation. Emollient showed promise in improving skin hydration and reducing the damage caused by antiseptics. Further research with a larger sample is needed to confirm these findings and assess emollient efficacy during frequent antiseptic use.

Irradiation-induced hair graying in mice: an experimental model to evaluate the effectiveness of interventions targeting oxidative stress, DNA damage prevention, and cellular senescence

Hair graying, also known as canities or achromotrichia, is a natural phenomenon associated with aging and is influenced by external factors such as stress, environmental toxicants, and radiation exposure. Understanding the mechanisms underlying hair graying is an ideal approach for developing interventions to prevent or reverse age-related changes in regenerative tissues. Hair graying induced by ionizing radiation (γ-rays or X-rays) has emerged as a valuable experimental model to investigate the molecular pathways involved in this process. In this review, we examine the existing evidence on radiation-induced hair graying, with a particular focus on the potential role of radiation-induced cellular senescence. We explore the current understanding of hair graying in aging, delve into the underlying mechanisms, and highlight the unique advantages of using ionizing-irradiation-induced hair graying as a research model. By elucidating the molecular pathways involved, we aim to deepen our understanding of hair graying and potentially identify novel therapeutic targets to address this age-related phenotypic change.

Cyclic AMP-regulatory element-binding protein: a novel UV-targeted transcription factor in skin cancer

Common therapeutics in relation to melanoma and non-melanoma cancers include the use of kinase inhibitors. The long-term benefits of kinases, however, are limited by development of drug resistance. An alternative approach for treatment would be to focus on transcription factors. Cyclic AMP-regulatory element-binding protein (CREB) is a transcription factor that is commonly overactivated or overexpressed in many different cancers including skin cancer. Ultraviolet radiation (UVR), one of the main causes of skin cancer, can activate CREB in both melanocytes and keratinocytes. In addition, CREB has been found to be activated in skin cancers. Considering the prominent role that CREB plays in skin cancers, the studies reviewed herein raise the possibility of CREB as a potential prognostic and diagnostic marker of skin cancer and a novel target for therapeutic intervention.

Identification of pigmentation genes in skin, muscle and tail of a Thai-flag variety of Siamese fighting fish Betta splendens

Pigmentation genes expressed in skin, body muscle and tail of Thai-flag compared with Blue, White and Red varieties of Siamese fighting fish Betta splendens were identified. In total, 22,919 new unigenes were found. Pearson correlation and PCA analysis revealed that expression profiles of genes in muscle, skin and tail across solid color variety were similar. In contrast, those in skin and red tail part of Thai-flag were closely related but they showed different expression profiles with the white tail part. Moreover, 21,347-64,965 SNPs were identified in exonic regions of identified genes. In total, 28,899 genes were differentially expressed between paired comparisons of libraries where 13,907 genes (48.12 %) were upregulated and 14,992 genes (51.88 %) were downregulated. DEGs between paired libraries were 106-5775 genes relative to the compared libraries (56-2982 and 50-2782 for upregulated and downregulated DEGs). Interestingly, 432 pigmentation genes of B. splendens were found. Of these, 297 DEGs showed differential expression between varieties. Many DEGs in melanogenesis (Bsmcr1r, Bsmcr5r, and Bsslc2a15b), tyrosine metabolism (Bstyr, Bstyrp1b and Bsdct), stripe repressor (BsAsip1 and BsAsip2b), pteridine (Bsgch2) and carotenoid (BsBco2) biosynthesis were downregulated in the Thai-flag compared with solid color varieties. Expression of Bsbco1l, Bsfrem2b, Bskcnj13, Bszic2a and Bspah in skin, muscle and tail of Thai-flag, Blue, Red and White varieties was analyzed by qRT-PCR and revealed differential expression between fish varieties and showed anatomical tissue-preferred expression patterns in the same fish variety. The information could be applied to assist genetic-based development of new B. splendens varieties in the future.

Petanin Potentiated JNK Phosphorylation to Negatively Regulate the ERK/CREB/MITF Signaling Pathway for Anti-Melanogenesis in Zebrafish

Petanin, an acylated anthocyanin from the Solanaceae family, shows potential in tyrosinase inhibitory activity and anti-melanogenic effects; however, its mechanism remains unclear. Therefore, to investigate the underlying mechanism of petanin's anti-melanogenic effects, the enzyme activity, protein expression and mRNA transcription of melanogenic and related signaling pathways in zebrafish using network pharmacology, molecular docking and molecular dynamics simulation were combined for analysis. The results showed that petanin could inhibit tyrosinase activity and melanogenesis, change the distribution and arrangement of melanocytes and the structure of melanosomes, reduce the activities of catalase (CAT) and peroxidase (POD) and enhance the activity of glutathione reductase (GR). It also up-regulated JNK phosphorylation, inhibited ERK/RSK phosphorylation and down-regulated CREB/MITF-related protein expression and mRNA transcription. These results were consistent with the predictions provided through network pharmacology and molecular docking. Thus, petanin could inhibit the activity of tyrosinase and the expression of tyrosinase by inhibiting and negatively regulating the tyrosinase-related signaling pathway ERK/CREB/MITF through p-JNK. In conclusion, petanin is a good tyrosinase inhibitor and anti-melanin natural compound with significant market prospects in melanogenesis-related diseases and skin whitening cosmetics.

Transcriptome analysis of sexual dimorphism in dorsal down coloration in goslings

BACKGROUND

In day-old Hungarian white goose goslings, there is a noticeable difference in dorsal down coloration between males and females, with females having darker dorsal plumage and males having lighter plumage. The ability to autosex day-old goslings based on their dorsal down coloration is important for managing them efficiently and planning their nutrition in the poultry industry. The aim of this study was to determine the biological and genetic factors underlying this difference in dorsal down colorationthrough histological analysis, biochemical assays, transcriptomic profiling, and q‒PCR analysis.

RESULTS

Tissue analysis and biochemical assays revealed that compared with males, 17-day-old embryos and day-old goslings of female geese exhibited a greater density of melanin-containing feather follicles and a greater melanin concentration in these follicles during development. Both female and male goslings had lower melanin concentrations in their dorsal skin compared to 17-day-old embryos. Transcriptome analysis identified a set of differentially expressed genes (DEGs) (MC1R, TYR, TYRP1, DCT and MITF) associated with melanogenesis pathways that were downregulated or silenced specifically in the dorsal skin of day-old goslings compared to 17-day-old embryos, affecting melanin synthesis in feather follicles. Additionally, two key genes (MC1R and MITF) associated with feather coloration showed differences between males and females, with females having higher expression levels correlated with increased melanin synthesis and darker plumage.

CONCLUSION

The expression of multiple melanogenesis genes determines melanin synthesis in goose feather follicles. The dorsal down coloration of day-old Hungarian white goose goslings shows sexual dimorphism, likely due to differences in the expression of the MC1R and MITF genes between males and females. These results could help us better understand why male and female goslings exhibit different plumage patterns.

Resveratrol-Enriched Rice Callus Extract Inhibits Oxidative and Cellular Melanogenic Activities in Melan-A Cells

The excessive production of melanin can cause skin diseases and hyperpigmentation. In this study, resveratrol contained in Dongjin rice seed (DJ526) was increased through callus induction. The antioxidant capacity of resveratrol-enriched rice callus was evaluated using the ABTS radical scavenging method and was equivalent to that of vitamin C. DJ526 rice callus extract significantly increased antioxidant activities in a concentration-dependent manner. The anti-melanogenesis effects of DJ526 rice callus extract were also evaluated in melan-a cells. Resveratrol-enriched rice callus extract significantly (i) decreased the size and number of melanin-containing cells, (ii) suppressed the activity of cellular tyrosinase and melanin content, (iii) downregulated the expression of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2, (iv) increased the expression of phosphorylated extracellular signal-regulated kinase 1/2 and protein kinase B, and (v) inhibited the activation of phosphorylated p38 in melan-a cells. From the above observations, DJ526 rice callus extract showed strong antioxidant and anti-melanogenesis activity at the concentration test. These findings indicate the potential of resveratrol-enriched rice callus as a novel agent for controlling hyperpigmentation.

Exploring the Influence of Cold Plasma on Epidermal Melanogenesis In Situ and In Vitro

Epidermal melanin synthesis determines an individual's skin color. In humans, melanin is formed by melanocytes within the epidermis. The process of melanin synthesis strongly depends on a range of cellular factors, including the fine-tuned interplay with reactive oxygen species (ROS). In this context, a role of cold atmospheric plasma (CAP) on melanin synthesis was proposed due to its tunable ROS generation. Herein, the argon-driven plasma jet kINPen® MED was employed, and its impact on melanin synthesis was evaluated by comparison with known stimulants such as the phosphodiesterase inhibitor IBMX and UV radiation. Different available model systems were employed, and the melanin content of both cultured human melanocytes (in vitro) and full-thickness human skin biopsies (in situ) were analyzed. A histochemical method detected melanin in skin tissue. Cellular melanin was measured by NIR autofluorescence using flow cytometry, and a highly sensitive HPLC-MS method was applied, which enabled the differentiation of eu- and pheomelanin by their degradation products. The melanin content in full-thickness human skin biopsies increased after repeated CAP exposure, while there were only minor effects in cultured melanocytes compared to UV radiation and IBMX treatment. Based on these findings, CAP does not appear to be a useful option for treating skin pigmentation disorders. On the other hand, the risk of hyperpigmentation as an adverse effect of CAP application for wound healing or other dermatological diseases seems to be neglectable.

Multi-technology integrated network pharmacology-based study on phytochemicals, active metabolites, and molecular mechanism of Psoraleae Fructus to promote melanogenesis

ETHNOPHARMACOLOGICAL RELEVANCE

According to the Compendium of Materia Medica (Shizhen Li, Ming dynasty) and Welfare Pharmacy (Song dynasty), Psoraleae Fructus (PF), a traditional Chinese medicine (TCM) has a bitter taste and warm nature, which has the effect of treating spleen and kidney deficiency and skin disease. Although PF has been widely used since ancient times and has shown satisfactory efficacy in treating vitiligo, the active substances and the mechanism of PF in promoting melanogenesis remain unclear.

AIM OF THE STUDY

To explore the active substances and action mechanisms of PF in promoting melanogenesis.

MATERIALS AND METHODS

Firstly, UPLC-UV-Q-TOF/MS was used to characterize the components in PF extract and identify the absorption components and metabolites of PF after oral administration at usual doses in rats. Secondly, the active substances and related targets and pathways were predicted by network pharmacology and molecular docking. Finally, pharmacodynamic and molecular biology experiments were used to verify the prediction results.

RESULTS

The experimental results showed that 15 compounds were identified in PF extract, and 44 compounds, consisting of 8 prototype components and 36 metabolites (including isomers) were identified in rats' plasma. Promising action targets (MAPK1, MAPK8, MAPK14) and signaling pathways (MAPK signaling pathway) were screened and refined to elucidate the mechanism of PF against vitiligo based on network pharmacology. Bergaptol and xanthotol (the main metabolites of PF), psoralen (prototype drug), and PF extract significantly increased melanin production in zebrafish embryos. Furthermore, bergaptol could promote the pigmentation of zebrafish embryos more than psoralen and PF extract. Bergaptol significantly increased the protein expression levels of p-P38 and decreased ERK phosphorylation in B16F10 cells, which was also supported by the corresponding inhibitor/activator combination study. Moreover, bergaptol increased the mRNA expression levels of the downstream microphthalmia-associated transcription factor (MITF) and tyrosinase in B16F10 cells. Our data elucidate that bergaptol may promote melanogenesis by regulating the p-P38 and p-ERK signaling pathway.

CONCLUSIONS

This study will lay a foundation for discovering potential new drugs for treating vitiligo and provide feasible ideas for exploring the mechanism of traditional Chinese medicine.

Sustainable Utilization of Food Biowaste (Papaya Peel) Extract for Gold Nanoparticle Biosynthesis and Investigation of Its Multi-Functional Potentials

Papaya contains high amounts of vitamins A, C, riboflavin, thiamine, niacin, ascorbic acid, potassium, and carotenoids. It is confirmed by several studies that all food waste parts such as the fruit peels, seeds, and leaves of papaya are potential sources of phenolic compounds, particularly in the peel. Considering the presence of numerous bioactive compounds in papaya fruit peels, the current study reports a rapid, cheap, and environmentally friendly method for the production of gold nanoparticles (AuNPs) employing food biowaste (vegetable papaya peel extract (VPPE)) and investigated its antioxidant, antidiabetic, tyrosinase inhibition, anti-inflammatory, antibacterial, and photocatalytic degradation potentials. The phytochemical analysis gave positive results for tannins, saponins, steroids, cardiac steroidal glycoside, protein, and carbohydrates. The manufactured VPPE-AuNPs were studied by UV-Vis scan (with surface plasmon resonance of 552 nm), X-ray diffraction analysis (XRD) (with average crystallite size of 44.41 nm as per the Scherrer equation), scanning electron microscopy-energy-dispersive X-ray (SEM-EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), particle size, zeta potential, etc. The mean dimension of the manufactured VPPE-AuNPs is 112.2 d.nm (PDI-0.149) with a -26.1 mV zeta potential. The VPPE-AuNPs displayed a significant antioxidant effect (93.24% DPPH scavenging and 74.23% SOD inhibition at 100 µg/mL); moderate tyrosinase effect (with 30.76%); and substantial α-glucosidase (95.63%) and α-amylase effect (50.66%) at 100 µg/mL. Additionally, it was found to be very proficient in the removal of harmful methyl orange and methylene blue dyes with degradation of 34.70% at 3 h and 24.39% at 5 h, respectively. Taken altogether, the VPPE-AuNPs have been proven to possess multiple biopotential activities, which can be explored by the food, cosmetics, and biomedical industries.

Promising Application, Efficient Production, and Genetic Basis of Mannosylerythritol Lipids

Mannosylerythritol lipids (MELs) are a class of glycolipids that have been receiving increasing attention in recent years due to their diverse biological activities. MELs are produced by certain fungi and display a range of bioactivities, making them attractive candidates for various applications in medicine, agriculture, and biotechnology. Despite their remarkable qualities, industrial-scale production of MELs remains a challenge for fungal strains. Excellent fungal strains and fermentation processes are essential for the efficient production of MELs, so efforts have been made to improve the fermentation yield by screening high-yielding strains, optimizing fermentation conditions, and improving product purification processes. The availability of the genome sequence is pivotal for elucidating the genetic basis of fungal MEL biosynthesis. This review aims to shed light on the applications of MELs and provide insights into the genetic basis for efficient MEL production. Additionally, this review offers new perspectives on optimizing MEL production, contributing to the advancement of sustainable biosurfactant technologies.

Transcriptional and post-translational regulation of MITF mediated by bHLH domain during the melanogenesis and melanocyte proliferation in Crassostrea gigas

Melanocyte differentiation is orchestrated by the master regulator transcription factor MITF. However, its ability to discern distinct binding sites linked to effective gene regulation remains poorly understood. This study aims to assess how co-activator acetyltransferase interacts with MITF to modulate their related lysine action, thereby mediating downstream gene regulation, including DNA affinity, stability, transcriptional activity, particularly in the process of shell pigmentation. Here, we have demonstrated that the CgMITF protein can be acetylated, further enabling selective amplification of the melanocyte maturation program. Collaboration with transcriptional co-regulator p300 advances MITF dynamically interplay with downstream targeted gene promoters. We have established that MITF activation was partially dependent on the bHLH domain, which was well conserved across species. The bHLH domain contained conserved lysine residues, including K6 and K43, which interacted with the E-box motif of downstream targeted-genes. Mutations at K6 and K43 lead to a decrease in the binding affinity of the E-box motif. CgMITF protein bound to the E-box motif within the promoter regions of the tyrosinase-related genes, contributing to melanogenesis, and also interacted with the E-box motif within the TBX2 promoter regions, associated with melanocyte proliferation. We elucidated how the bHLH domain links the transcriptional regulation and acetylation modifications in the melanocyte development in C. gigas.

Fast freezing inhibits melanin synthesis of melanocytes by modulating the Wnt/β-catenin signalling pathway

Skin hyperpigmentation is mainly caused by excessive synthesis of melanin; however, there is still no safe and effective therapy for its removal. Here, we found that the dermal freezer was able to improve UVB-induced hyperpigmentation of guinea pigs without causing obvious epidermal damage. We also mimic freezing stimulation at the cellular level by rapid freezing and observed that freezing treatments <2.5 min could not decrease cell viability or induce cell apoptosis in B16F10 and Melan-A cells. Critically, melanin content and tyrosinase activity in two cells were greatly reduced after freezing treatments. The dramatic decrease in tyrosinase activity was associated with the downregulation of MITF, TYR, TRP-1 and TRP-2 protein expression in response to freezing treatments for two cells. Furthermore, our results first demonstrated that freezing treatments significantly reduced the levels of p-GSK3β and β-catenin and the nuclear accumulation of β-catenin in B16F10 and Melan-A cells. Together, these data suggest that fast freezing treatments can inhibit melanogenesis-related gene expression in melanocytes by regulating the Wnt/β-catenin signalling pathway. The inhibition of melanin production eventually contributed to the improvement in skin hyperpigmentation induced by UVB. Therefore, fast freezing treatments may be a new alternative of skin whitening in the clinic in the future.

Mucosal immune responses to Ichthyophthirius multifiliis in the ocular mucosa of rainbow trout (Oncorhynchus mykiss, Walbaum), an ancient teleost fish

The eye, as a specialized visual organ, is directly exposed to the external environment, and, therefore, it faces constant challenges from external pathogenic organisms and toxins. In the ocular mucosa (OM) of mammals, mucosal-associated lymphoid tissues (MALTs) constitute the primary line of defense. However, the immune defense role of the OM remains unknown in aquatic vertebrates. To gain insights into the immune processes within the OM of teleost fish, we developed an infection model of rainbow trout (Oncorhynchus mykiss) OM using a parasite, Ichthyophthirius multifiliis (Ich). Immunofluorescence, qPCR, and H&E staining revealed that Ich successfully infiltrates the OM of rainbow trout, leading to pathological structural changes, as evidenced by A&B staining. Importantly, the qPCR results indicate an up-regulation of immune-related genes following Ich infection in the OM. Moreover, transcriptome analyses were conducted to detect immune responses and impairments in eye function within the OM of rainbow trout with Ich infection. The results of the transcriptome analysis that Ich infection can cause an extensive immune response in the OM, ultimately affecting ocular function. To the best of our knowledge, our findings represent for the first time that the teleost OM could act as an invasion site for parasites and trigger a strong mucosal immune response to parasitic infection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-023-00199-6.

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.

Melanin Inhibitory Effect of Tuber himalayense Isolated in Incheon, Korea

There has been a growing interest in skin beauty and antimelanogenic products. Melanogenesis is the process of melanin synthesis whereby melanocytes are activated by UV light or hormone stimulation to produce melanin. Melanogenesis is mediated by several enzymes, such as tyrosinase (TYR), microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TRP-1), and TRP-2. In this study, we investigated the effect of Tuber himalayense extract on melanin synthesis in α-melanocyte-stimulating hormone (α-MSH)-treated B16F10 melanoma cells. We confirmed that T. himalayense extract was not toxic to α-MSH-treated B16F10 melanoma cells and exhibited a significant inhibitory effect on melanin synthesis at concentrations of 25, 50, and 100 μg/ml. Additionally, the T. himalayense extract inhibited melanin, TRP-1, TRP-2, tyrosinase, and MITF, which are enzymes involved in melanin synthesis, in a concentration-dependent manner. Furthermore, T. himalayense extract inhibited the mitogen-activated protein kinase (MAPK) pathways, such as extracellular signal-regulated kinase-1/2 (ERK), c-Jun N-terminal kinase (JNK), and p38. Therefore, we hypothesized that various components of T. himalayense extract affect multiple factors involved in melanogenesis in B16F10 cells. Our results indicate that T. himalayense extract could potentially be used as a new material for preparing whitening cosmetics.

Ribosomal S6 kinase 2-forkhead box protein O4 signaling pathway plays an essential role in melanogenesis

Although previous studies have examined the signaling pathway involved in melanogenesis through which ultraviolet (UV) or α-melanocyte-stimulating hormones (α-MSH) stimuli act as key inducers to produce melanin at the stratum basal layer of the epidermis, the signaling pathway regulating melanogenesis is still controversial. This study reports that α-MSH, not UVA and UVB, acted as a major stimulus of melanogenesis in B16F10 melanoma cells. Signaling pathway analysis using gene knockdown technology and chemical inhibitors, the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK)/p90 ribosomal S6 kinase 2 (RSK2) played an important role in melanogenesis. Unexpectedly, LY294002, a PI3K inhibitor, increased melanogenesis without UV or α-MSH stimulation, suggesting that the PI3K/AKT signaling pathway may not be a major signaling pathway for melanogenesis. Chemical inhibition of the MEKs/ERKs/RSK2 signaling pathway using U0126 or BI-D1870 suppressed melanogenesis by stimulation of UVA or α-MSH stimulation, or both. In particular, the genetic depletion of RSK2 or constitutive active (CA)-RSK2 overexpression showed that RSK2 plays a key role in melanogenesis. Interestingly, forkhead box protein O4 (FOXO4) was phosphorylated by RSK2, resulting in the increase of FOXO4's transactivation activity. Notably, the FOXO4 mutant harboring serine-to-alanine replacement at the phosphorylation sites totally abrogated the transactivation activity and reduced melanin production, indicating that RSK2-mediated FOXO4 activity plays a key role in melanogenesis. Furthermore, kaempferol, a flavonoid inhibiting the RSK2 activity, suppressed melanogenesis. In addition, FOXO4-wt overexpression showed that FOXO4 enhance melanin synthesis. Overall, the RSK2-FOXO4 signaling pathway plays a key role in modulating melanogenesis.

Artificial Intelligence-Assisted Optimization of Antipigmentation Tyrosinase Inhibitors: De Novo Molecular Generation Based on a Low Activity Lead Compound

Artificial intelligence (AI) de novo molecular generation is a highly promising strategy in the drug discovery, with deep reinforcement learning (RL) models emerging as powerful tools. This study introduces a fragment-by-fragment growth RL forward molecular generation and optimization strategy based on a low activity lead compound. This process integrates fragment growth-based reaction templates, while target docking and drug-likeness prediction were simultaneously performed. This comprehensive approach considers molecular similarity, internal diversity, synthesizability, and effectiveness, thereby enhancing the quality and efficiency of molecular generation. Finally, a series of tyrosinase inhibitors were generated and synthesized. Most compounds exhibited more improved activity than lead, with an optimal candidate compound surpassing the effects of kojic acid and demonstrating significant antipigmentation activity in a zebrafish model. Furthermore, metabolic stability studies indicated susceptibility to hepatic metabolism. The proposed AI structural optimization strategies will play a promising role in accelerating the drug discovery and improving traditional efficiency.

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.

Differential expression and alternative splicing analyses of multiple tissues reveal albinism-associated genes in the Wels catfish (Silurus glanis)

Albinism is a widespread departure from a typical body colouration due to altered melanin production. The Wels catfish (Silurus glanis) is among the largest freshwater fish species in the world, and albino individuals occur both in the wild and in aquaculture. Here, we performed transcriptome-wide analysis of albino and normally pigmented S. glanis using four tissues (skin, dorsal fin, whole eye and liver) to identify genes associated with albinism by exploring patterns of differential expression (DE) and differential alternative splicing (DAS). Multi-tissue analyses revealed a large number of genes in skin (n = 1355) and fin (n = 614) tissue associated with the albino phenotype in S. glanis, while the number of DE genes in eye and liver tissues was lower (n = 188, n = 189, respectively). Several DE genes across multiple tissues were detected as the most promising candidates (e.g., hsp4, hsp90b1, raph1, uqcrfs1, adcy-family and wnt-family) potentially causally linked to the albino phenotype in Wels catfish. Moreover, our findings supported earlier observations of physiological differences between albino and normally pigmented individuals, particularly in energy metabolism and immune response. In contrast, there were only a few pigmentation-related genes observed among DAS genes (4 in skin, 2 in fin), the overlap between DAS and DE genes was low (n = 25) and did not include known pigmentation-related genes. This suggests that DAS and DE in Wels catfish are, to a large extent, independent processes, and the observed alternative splicing cases are probably not causally linked with albinism in S. glanis. This work provides the first transcriptome-wide multi-tissue insights into the albinism of Wels catfish and serves as a valuable resource for further understanding the genetic mechanisms of pigmentation in fish.

Co-Treatment with Phlorotannin and Extracellular Vesicles from Ecklonia cava Inhibits UV-Induced Melanogenesis

Hyperpigmentation due to ultraviolet (UV)-induced melanogenesis causes various esthetic problems. Phlorotannin (PT) and extracellular vesicles (EVs) derived from various plants suppress melanogenesis pathways. We used UV-exposed keratinocytes and animal skin to determine if co-treatment with PT and EVs from Ecklonia cava (EVE) could inhibit melanogenesis by reducing UV-induced oxidative stress and the expression of the thioredoxin-interacting protein (TXNIP)/nucleotide-binding oligomerization domain-like receptor family pyrin domain containing the 3 (NLRP3)/interleukin-18 (IL-18) pathway, which are upstream signals of the microphthalmia-associated transcription factor. UV exposure increased oxidative stress in keratinocytes and animal skin, as evaluated by 8-OHdG expression, and this effect was reduced by co-treatment with PT and EVE. UV also increased binding between NLRP3 and TXNIP, which increased NLRP3 inflammasome activation and IL-18 secretion, and this effect was reduced by co-treatment with PT and EVE in keratinocytes and animal skin. In melanocytes, conditioned media (CM) from UV-exposed keratinocytes increased the expression of melanogenesis-related pathways; however, these effects were reduced with CM from UV-exposed keratinocytes treated with PT and EVE. Similarly, PT and EVE treatment reduced melanogenesis-related signals, melanin content, and increased basement membrane (BM) components in UV-exposed animal skin. Thus, co-treatment with PT and EVE reduced melanogenesis and restored the BM structure by reducing oxidative stress and TXNIP/NLRP3/IL-18 pathway expression.

Methylanthranilate, a Food Fragrance Attenuates Skin Pigmentation through Downregulation of Melanogenic Enzymes by cAMP Suppression

Methyl anthranilate (MA) is a botanical fragrance used in food flavoring with unexplored potential in anti-pigment cosmetics. MA dose-dependently reduced melanin content without affecting cell viability, inhibited dendrite elongation and melanosome transfer in the co-culture system of human melanoma cells (MNT-1) and human keratinocyte cell line (HaCaT), and downregulated melanogenic genes, including tyrosinase, tyrosinase-related protein 1 and 2 (TRP-1, TRP-2). Additionally, MA decreased cyclic adenosine monophosphate (cAMP) production and exhibited a significant anti-pigmentary effect in Melanoderm™. These results suggest that MA is a promising anti-pigmentary agent for replacing or complementing existing anti-pigmentary cosmetics.

Skin-whitening effects of Spergularia marina by suppressing MITF translocation

Spergularia marina is a plant that grows in salty regions along the coastline and exerts radical-scavenging and anti-inflammatory effects. In this study, we investigated the skin-whitening effects of S. marina extract (SME) in B16F10 melanoma cells. SME was found to exert radical-scavenging effects. It suppressed α-melanocyte-stimulating hormone-induced melanogenesis and tyrosinase activity. We also assessed the melanin production signaling pathway to identify the inhibitory action mechanism of SME on melanogenesis. SME decreased the protein expression levels of tyrosinase-related protein (TRP)-1, TRP-2, and tyrosinase, which play important roles in melanogenesis. Furthermore, western blotting revealed that SME inhibited the nuclear translocation of melanocyte inducing transcription factor (MITF), which is a transcription factor for TRP-1, TRP-2, and tyrosinase, suggesting that SME exerts its skin-whitening effect by inhibiting MITF nuclear translocation. Therefore, SME may potentially be used in skin-whitening medicines and cosmetics.

Putrescine Upregulates Melanogenesis Through Modulation of MITF Transcription Factor in B16F1 Mouse Melanoma Cells

Research background

Ageing is a biochemical, metabolic and genetic physiological phenomenon. The suppression of melanin biosynthesis, evident in the greying of the hair, is a hallmark of ageing resulting from translation failure, reduced enzyme activity and cellular senescence. Putrescine, the smallest member of the polyamine family and an organic chemical, is present in living mammalian cells and plays a crucial role in regulating skin melanogenesis. Therefore, the purpose of this study is to explore the effect of putrescine on the signalling pathways of melanogenesis in melanoma cells.

Experimental approach

Melanin production capacity of putrescine was analysed using a tyrosinase activity assay. To assess the cell viability of B16F1 cells exposed to putrescine, a tetrazolium dye MTT assay was performed. The effect of putrescine on melanin synthesis in the presence of H2O2 was evaluated using various in vitro assays in B16F1 cells. The effect of putrescine on melanin production in B16F1 cells was determined using a specific melanin production assay. Gene expression was analysed using real-time polymerase chain reaction (RT-PCR). Furthermore, the effect of putrescine on the expression of proteins related to melanin production in the cells treated with H2O2 was analysed by immunofluorescence and Western blot analysis.

Results and conclusions

Putrescine increased tyrosinase activity and showed no cytotoxicity in B16F1 cells. In addition, putrescine effectively scavenged H2O2, as shown by the reduction of intracellular H2O2 amounts in 2',7'-dichlorofluorescin diacetate analysis, and promoted melanin production in living cells. The stimulation of melanogenesis by putrescine was attributed to the increased expression of Mitf, Tyr, Trp-1 and Trp-2 genes. Immunofluorescence assays revealed that putrescine enhanced the expression of proteins associated with melanogenesis and upregulated TYR, TRP-1 and TRP-2 via the microphthalmia-associated transcription factor (MITF) and increased the expression of methionine sulfoxide reductases A (MSRA) and B (MSRB) in the cells treated with H2O2, effectively promoting melanogenesis. These results suggest that putrescine can be used to stimulate melanin synthesis.

Novelty and scientific contribution

This is the first study to investigate the effect of putrescine on the signalling pathways of melanogenesis in B16F1 melanoma cells. The results confirm that putrescine can promote melanogenesis through the expression of TYR, TRP-1 and TRP-2 via the MITF in cells treated with H2O2. Putrescine can be used exclusively as a cosmetic product to prevent premature greying of hair.

Carotenoids in red fruit (Pandanus conoideus Lam.) have a potential role as an anti‑pigmentation agent (Review)

Melasma is a persistent condition characterized by excessive melanin production in the skin. The management of melasma necessitates a protracted treatment duration, which is associated with diminished levels of patient satisfaction. One effective strategy for mitigating occurrence of melasma is consumption of nutricosmetics with depigmentation properties. The present review aimed to investigate the potential of red fruit as a depigmentation agent. Carotenoids serve a crucial role in human nutrition as a precursor to vitamin A. Carotenoids serve as scavengers of reactive oxygen species generated by ultraviolet radiation. Carotenoids promote skin health. Red fruit, a fruit originating from Papua (Indonesia) has anti-pigmentation properties associated with its ability to block melanogenesis through various protein pathways such as PKA, ERK, and AKT signaling pathways. The consumption of food rich in carotenoids, such as red fruit, has advantageous properties to reduce hyperpigmentation and skin brightening.

Synthesis of Benzoxazines by Heterogeneous Multicomponent Biochemo Multienzymes Cascade Reaction

This work describes the possibility to combine multicomponent chemistry and multienzymes cascade transformations in a unique reactive framework to yield highly functionalized 1,4-benzoxazines under favorable heterogeneous conditions. The synthetic scheme involved the generation in situ of electrophilic reactive quinone intermediates of tyrosol esters catalyzed by lipase M and tyrosinase followed by nucleophilic 1,6-Michael addition of selected α-amino acid methyl esters, and successive intramolecular lactonization and aromatization processes. The immobilization of the multienzymes cascade on electroactive lignin nanoparticles improved the sustainability and recyclability of the overall system.

Screening of Key Components for Melanogenesis Inhibition of Polygonum cuspidatum Extract Based on the Spectrum-Effect Relationship and Molecular Docking

Polygonum cuspidatum (PC) extract has been listed in the "Catalog of Used Cosmetic Ingredients (2021 Edition)", which can inhibit melanogenesis, thus exerting a whitening effect, and has been widely used in cosmetics. However, there are currently no quality standards for PC extract used in cosmetics, and the bioactive components associated with anti-melanogenesis remain unclear. In view of this, the present study was the first to investigate the spectrum-effect relationship between fingerprints of PC extract and melanogenesis inhibition. Ten batches of PC extract fingerprints were established by HPLC. Pearson's correlation analysis, gray correlation analysis (GRA) and orthogonal partial least squares regression analysis (OPLSR) were used to screen out resveratrol, emodin and physcion as the main whitening active ingredients using the inhibition of tyrosinase in B16F10 cells as the pharmacological index. Then, the melanogenesis inhibitory effects of the above three components were verified by tyrosinase inhibition and a melanin content assay in B16F10 cells. The interaction between small molecules and proteins was investigated by the molecular docking method, and it was confirmed by quantitative real-time PCR (qRT-PCR) that resveratrol, emodin and physcion significantly down-regulated the transcript levels of melanogenesis-related factors. In conclusion, this study established a general model combining HPLC fingerprinting and melanogenesis inhibition and also analyzed the spectrum-effect relationship of PC extract, which provided theoretical support for the quality control of PC extract in whitening cosmetics.

Optimization, Metabolomic Analysis, Antioxidant Potential andDepigmenting Activity of Polyphenolic Compounds fromUnmature Ajwa Date Seeds (Phoenix dactylifera L.) Using Ultrasonic-Assisted Extraction

This study sought to optimize the ultrasonic-assisted extraction of polyphenolic compounds from unmature Ajwa date seeds (UMS), conduct untargeted metabolite identification and assess antioxidant and depigmenting activities. Response surface methodology (RSM) utilizing the Box-Behnken design (BBD) and artificial neural network (ANN) modeling was applied to optimize extraction conditions, including the ethanol concentration, extraction temperature and time. The determined optimal conditions comprised the ethanol concentration (62.00%), extraction time (29.00 min), and extraction temperature (50 °C). Under these conditions, UMS exhibited total phenolic content (TPC) and total flavonoid content (TFC) values of 77.52 ± 1.55 mgGAE/g and 58.85 ± 1.12 mgCE/g, respectively, with low relative standard deviation (RSD%) and relative standard error (RSE%). High-resolution mass spectrometry analysis unveiled the presence of 104 secondary metabolites in UMS, encompassing phenols, flavonoids, sesquiterpenoids, lignans and fatty acids. Furthermore, UMS demonstrated robust antioxidant activities in various cell-free antioxidant assays, implicating engagement in both hydrogen atom transfer and single electron transfer mechanisms. Additionally, UMS effectively mitigated tert-butyl hydroperoxide (t-BHP)-induced cellular reactive oxygen species (ROS) generation in a concentration-dependent manner. Crucially, UMS showcased the ability to activate mitogen-activated protein kinases (MAPKs) and suppress key proteins including tyrosinase (Tyr), tyrosinase-related protein-1 and -2 (Trp-1 and -2) and microphthalmia-associated transcription factor (MITF), which associated melanin production in MNT-1 cell. In summary, this study not only optimized the extraction process for polyphenolic compounds from UMS but also elucidated its diverse secondary metabolite profile. The observed antioxidant and depigmenting activities underscore the promising applications of UMS in skincare formulations and pharmaceutical developments.

Genomic loci involved in sensing environmental cues and metabolism affect seasonal coat shedding in Bos taurus and Bos indicus cattle

Seasonal shedding of winter hair at the start of summer is well studied in wild and domesticated populations. However, the genetic influences on this trait and their interactions are poorly understood. We use data from 13,364 cattle with 36,899 repeated phenotypes to investigate the relationship between hair shedding and environmental variables, single nucleotide polymorphisms, and their interactions to understand quantitative differences in seasonal shedding. Using deregressed estimated breeding values from a repeated records model in a genome-wide association analysis (GWAA) and meta-analysis of year-specific GWAA gave remarkably similar results. These GWAA identified hundreds of variants associated with seasonal hair shedding. There were especially strong associations between chromosomes 5 and 23. Genotype-by-environment interaction GWAA identified 1,040 day length-by-genotype interaction associations and 17 apparent temperature-by-genotype interaction associations with hair shedding, highlighting the importance of day length on hair shedding. Accurate genomic predictions of hair shedding were created for the entire dataset, Angus, Hereford, Brangus, and multibreed datasets. Loci related to metabolism and light-sensing have a large influence on seasonal hair shedding. This is one of the largest genetic analyses of a phenological trait and provides insight into both agriculture production and basic science.