The effect of emodin on melanogenesis through the modulation of ERK and MITF signaling pathway

Gynostemma pentaphyllum Makino extract induces hair growth and exhibits an anti-graying effect via multiple mechanisms

BACKGROUND

In traditional Asian medicine, Gynostemma pentaphyllum Makino leaf extract (Gp) is used to treat aging, metabolic syndrome, diabetes, and neurodegenerative diseases. Hair loss and hair-graying are common phenomena that haunt everyone. However, whether Gp activities on inhibition of hair loss and getting gray have been rarely studied.

AIM

Study the Gp activity and mechanism by in vivo and in vitro experiments to explore its application on hair health.

METHODS

In the present study, we determined the effects of Gp on the expression of hair growth-related genes and proliferation of human dermal papilla cells (hDPCs). Furthermore, Gp was topically applied to the hair-shaved skin of male C57BL/6 mice, and the histological profile of the skin was studied. Because emotional stress may lead to melanocyte disappearance, norepinephrine-exposed mice B16 melanocytes were treated with Gp to elucidate the anti-hair graying capacity of Gp in response to this stress type.

RESULTS

Gp stimulated the proliferation of hDPCs and the Wnt signaling pathways associated with hair growth; furthermore, the expression of the hair loss-related gene transforming growth factor-β1 was suppressed. Gp treatment significantly increased the size of hair follicles in the treated mice and stimulated them. Moreover, Gp not only increased melanin synthesis but also tyrosinase activity in B16 cells. Quantitative real-time polymerase chain reaction revealed that Gp increased melanin synthesis by increasing the expression of tyrosine-related protein-1, tyrosine-related protein-2, tyrosinase, and microphthalmia-associated transcription factor.

CONCLUSION

Our study provides preclinical evidence regarding the potential of Gp as a promising hair growth and anti-graying agent.

Quercetin 3-O-Galactoside Isolated from Limonium tetragonum Inhibits Melanogenesis by Regulating PKA/MITF Signaling and ERK Activation

Quercetin 3-O-galactoside (Q3G) is a common dietary flavanol that has been shown to possess several bioactivities, including anti-melanogenesis. However, how Q3G exerts its anti-melanogenic effect has not been studied. The current study, therefore aimed to investigate the anti-melanogenesis potential of Q3G and elucidate the underlying action mechanism in α-melanocyte-stimulating hormone (α-MSH)-induced hyperpigmentation model of B16F10 murine melanoma cells. Results showed that α-MSH stimulation significantly increased tyrosinase (TYR) and melanin production, which were significantly downregulated by Q3G treatment. The treatment with Q3G suppressed the transcriptional and protein expressions of melanogenesis-related enzymes TYR, tyrosinase related protein-1 (TRP-1), and TRP-2, along with the melanogenic transcription factor microphthalmia-associated transcription factor (MITF) in B16F10 cells. It was shown that Q3G downregulated MITF expression and suppressed its transcriptional activity by inhibiting the cAMP-dependent protein kinase A (PKA)-mediated activation of CREB and GSK3β. In addition, MAPK-regulated MITF activation signaling was also involved in the inhibition of melanin production by Q3G. The results suggest that the anti-melanogenic properties of Q3G rationalize further studies in vivo to confirm its action mechanism and consequent utilization as a cosmetic ingredient against hyperpigmentation.

Stimulatory effects of Lycium shawii on human melanocyte proliferation, migration, and melanogenesis: In vitro and in silico studies

There is no first-line treatment for vitiligo, a skin disease characterized by a lack of melanin produced by the melanocytes, resulting in an urgent demand for new therapeutic drugs capable of stimulating melanocyte functions, including melanogenesis. In this study, traditional medicinal plant extracts were tested for cultured human melanocyte proliferation, migration, and melanogenesis using MTT, scratch wound-healing assays, transmission electron microscopy, immunofluorescence staining, and Western blot technology. Of the methanolic extracts, Lycium shawii L. (L. shawii) extract increased melanocyte proliferation at low concentrations and modulated melanocyte migration. At the lowest tested concentration (i.e., 7.8 μg/mL), the L. shawii methanolic extract promoted melanosome formation, maturation, and enhanced melanin production, which was associated with the upregulation of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2 melanogenesis-related proteins, and melanogenesis-related proteins. After the chemical analysis and L. shawii extract-derived metabolite identification, the in silico studies revealed the molecular interactions between Metabolite 5, identified as apigenin (4,5,6-trihydroxyflavone), and the copper active site of tyrosinase, predicting enhanced tyrosinase activity and subsequent melanin formation. In conclusion, L. shawii methanolic extract stimulates melanocyte functions, including melanin production, and its derivative Metabolite 5 enhances tyrosinase activity, suggesting further investigation of the L. shawii extract-derived Metabolite 5 as a potential natural drug for vitiligo treatment.

Screening and Evaluation of Dermo-Cosmetic Activities of the Invasive Plant Species Polygonum cuspidatum

Polygonum cuspidatum (P. cuspidatum) is among the world's most problematic invasive plant species with negative ecological, socio-economic and security consequences. Management operations in areas invaded systematically generate a large quantity of plant waste, most often without outlets. Using this plant material could constitute a new alternative treatment for sustainable management. P. cuspidatum is well known to have numerous biological properties, containing notably stilbenes, quinones, flavonoids and phenolic acids. The present work proposes a reliable strategy using powerful techniques for the screening and the evaluation of the dermo-cosmetic potential of its aerial parts (AP) and root parts (RP). To the best of our knowledge, only antioxidant and anti-tyrosinase activities were previously evaluated on P. cuspidatum among the targets studied (superoxide dismutase, hyaluronidase, elastase, collagenase and tyrosinase). The results revealed strong antioxidant and anti-collagenase activities, moderate anti-hyaluronidase activity, while weak anti-elastase and anti-tyrosinase activities were observed for ethanolic extracts. Different standards selected and screened on the same targets made it possible to correlate the observed residual activities of produced extracts of P. cuspidatum from Savoie Mont Blanc and their chemical compositions. A structure-activity study was thus conducted on main molecular families, widely represented in the genus Polygonum.

Imperatorin Positively Regulates Melanogenesis through Signaling Pathways Involving PKA/CREB, ERK, AKT, and GSK3β/β-Catenin

The present study investigated the melanogenic effects of imperatorin and isoimperatorin and the underlying mechanisms of imperatorin using a mouse melanoma B16F10 model. Interestingly, treatment with 25 μM of either imperatorin or isoimperatorin, despite their structural differences, did not produce differences in melanin content and intracellular tyrosinase activity. Imperatorin also activated the expression of melanogenic enzymes, such as tyrosinase (TYR) and tyrosinase-related proteins TYRP-1 and TYRP-2. Mechanistically, imperatorin increases melanin synthesis through the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA)/cAMP-responsive element-binding protein (CREB)-dependent upregulation of microphthalmia-associated transcription factor (MITF), which is a key transcription factor in melanogenesis. Furthermore, imperatorin exerted melanogenic effects by downregulating extracellular signal-regulated kinase (ERK) and upregulating phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthesis kinase-3β (GSK-3β). Moreover, imperatorin increased the content of β-catenin in the cell cytoplasm and nucleus by reducing the content of phosphorylated β-catenin (p-β-catenin). Finally, we tested the potential of imperatorin in topical application through primary human skin irritation tests. These tests were performed on the normal skin (upper back) of 31 volunteers to determine whether 25 or 50 µM of imperatorin had irritation or sensitization potential. During these tests, imperatorin did not induce any adverse reactions. Taken together, these findings suggest that the regulation of melanogenesis by imperatorin can be mediated by signaling pathways involving PKA/CREB, ERK, AKT, and GSK3β/β-catenin and that imperatorin could prevent the pathogenesis of pigmentation diseases when used as a topical agent.

Emodin alleviates aortic valvular calcification by inhibiting the AKT/FOXO1 pathway

BACKGROUND

Valvular calcification commonly occurs in elderly individuals, and is increasingly considered an important economic and health burden. However, no efficient drugs against valvular calcification are available. The present work aimed to examine emodin's suppressive effect on high-calcium-dependent valve calcification and explore the underpinning mechanisms.

METHODS

Experiments were carried out in mice receiving vitamin D (Vit D) to induce valvular calcification.

RESULTS

Cell viability and apoptosis assays demonstrated celastrol suppressed proliferation and increased apoptosis in porcine aortic valve interstitial cells (PAVICs) at concentrations higher than 10 μM. Emodin (5 μM) attenuated the upregulation of osteogenic genes as well as calcium accumulation in PAVICs under high-calcium conditions. The elevations of calcium content in serum and valve, and calcium accumulation in valve and artery were suppressed by emodin in mice with valvular calcification after joint treatment with adenine and Vit D. In addition, p-AKT and p-FOXO1 were upregulated in PAVICs under high-calcium conditions, and this effect was reversed by emodin treatment. SC79, an AKT activator, reversed emodin's suppressive effects on increased calcium content, calcium deposition and osteogenic gene expression in PAVICs induced by calcific medium.

CONCLUSIONS

These data demonstrated emodin alleviates high-calcium-associated valvular calcification via AKT/FOXO1 signaling suppression, providing new insights into therapeutic strategies for clinical valvular calcification.

Genomic Regions Associated with the Position and Number of Hair Whorls in Horses

Simple Summary

Whorls have been used to indicate the temperaments of domestic animals; however, little is known about the biological events that drive this association. The present study is the first that aims to find the main genomic regions that influence the whorl traits in livestock, with horses as a model. Genes related to hair follicle growth were found. Interestingly, some of these genes also influence psychiatric diseases and neurological disorders, thus evidencing a consistent biological explanation for the association.

Abstract

The position and number of hair whorls have been associated with the behavior, temperament, and laterality of horses. The easy observation of whorls assists in the prediction of reactivity, and thus permits the development of better measures of handling, training, mounting, and riding horses. However, little is known about the genetics involved in the formation of hair whorls. Therefore, the aim of this study was to perform a genome-wide association analysis to identify chromosome regions and candidate genes associated with hair whorl traits. Data from 342 Quarter Horses genotyped for approximately 53,000 SNPs were used in an association study using a single-step procedure. The following traits were analyzed: vertical position of hair whorl on the head, number of whorls on the head, and number of whorls on the left and right sides of the neck. The traits had between one and three genomic windows associated. Each of them explained at least 4% of the additive variance. The windows accounted for 20–80% of additive variance for each trait analyzed. Many of the prospected genes are related to hair follicle growth. Some of these genes exert a pleiotropic effect on neurological and behavioral traits. This is the first indication of biological and physiological activity that might explain the association of hair whorls and temperament.