Melanocyte Stimulating Research Articles

Infertility in POMC-deficient mice

The pro-opiomelanocortin (POMC) gene is expressed in the hypothalamus and pituitary and its product is cleaved into several peptides including the melanocyte stimulating hormones (α, β, or γ-MSH), adrenocorticotropic hormone (ACTH), and beta-endorphin. Alpha-MSH is involved in regulating appetite, sexual behavior, and melanin, while ACTH regulates secretion of glucocorticoids from the adrenal cortex. Humans who have a POMC mutation either produce an abnormally short version of POMC or are missing the protein completely and therefore lack these hormones. This has biological consequences including red hair and fair skin, early-onset obesity (due to severe hyperphagia), and potentially hypothyroidism, hypogonadism, and infertility. Many of these same effects are seen with mice containing this deficiency. We are interested in studying infertility through a mouse model of hypothalamic-specific POMC-deficiency. These mice also experience early-onset obesity and infertility. Estradiol is a key reproductive hormone that is essential for fertility. POMC deficiency may lead to hypogonadism, which can cause low levels of estrogen so we hypothesize that POMC-deficient mice have reduced estrogen levels, which may contribute to their infertility. To test this hypothesis, we will measure estrogen levels in POMC-deficient mice at different stages of the estrus cycle using an estradiol ELISA kit. We expect the POMC-deficient mice to have lower estrogen levels than control mice. We also plan to use liquid chromatography mass spectrometry (LC-MS) to measure estrogen levels. Before collecting the blood samples, vaginal cell samples are obtained and viewed under a microscope to analyze the ratio of cells and determine which stage the females were in—proestrus, estrus, metestrus, or diestrus. Blood samples are then collected into 1.5 mL microcentrifuge tubes with 10 microliters of 0.5 M EDTA to prevent blood clotting. After blood is collected, it is centrifuged at 2,000 g for 20 minutes at 4 degrees Celsius. The plasma is then stored at -80 degrees Celsius until analysis. Based on preliminary results we expect the POMC deficient mice to have reduced estrogen and/or altered levels throughout the cycle. So far, our results have indicated that POMC-deficient female mice have abnormal estrus cycles and also reduced uterine weights. The conclusions from this study will help us understand more about the causes of infertility in POMC-deficient mice, which may also lead to greater understanding on how to treat humans with infertility due to a POMC mutation. Support for this research was provided by IRACDA grant NIHK12GM111725 to Z.T. and UVU Scholarly Activities Grant to A.G. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Afamelanotide in protoporphyria and other skin diseases: a review.

Afamelanotide is a synthetic alpha melanocyte stimulating hormone presenting a higher activity than natural hormones. Its main properties are related to the enhanced production of eumelanin by agonistically binding to the melanocortin-1 receptor. Since 2016 afamelanotide has been especially applied to treat cases of erythropoietic porphyria (EPP), where painful photosensitivity has been observed since early childhood. The positive effect of afamelanotide in EPP administered subcutaneously improved tolerance to artificial white light and increased pain-free time spent in direct sunlight. In this review we summarize the possible use of afamelanotide in dermatology, with special emphasis on EPP and encourage including afamelanotide as a treatment option in patient care.

The role of aryl hydrocarbon receptor in vitiligo: a review.

Vitiligo is an acquired autoimmune dermatosis characterized by patchy skin depigmentation, causing significant psychological distress to the patients. Genetic susceptibility, environmental triggers, oxidative stress, and autoimmunity contribute to melanocyte destruction in vitiligo. Due to the diversity and complexity of pathogenesis, the combination of inhibiting melanocyte destruction and stimulating melanogenesis gives the best results in treating vitiligo. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that can regulate the expression of various downstream genes and play roles in cell differentiation, immune response, and physiological homeostasis maintenance. Recent studies suggested that AhR signaling pathway was downregulated in vitiligo. Activation of AhR pathway helps to activate antioxidant pathways, inhibit abnormal immunity response, and upregulate the melanogenesis gene, thereby protecting melanocytes from oxidative stress damage, controlling disease progression, and promoting lesion repigmentation. Here, we review the relevant literature and summarize the possible roles of the AhR signaling pathway in vitiligo pathogenesis and treatment, to further understand the links between the AhR and vitiligo, and provide new potential therapeutic strategies.

SAT027 Novel Obesity-Associated Melanocortin 4 Receptor Variants Modulate Signaling Differently

Abstract Disclosure: A.V. Rodriguez Rondon: None. M.S. Welling: None. E.L. van den Akker: None. E.F. van Rossum: None. P.J. Delhanty: None. J.A. Visser: None. Melanocortin-4 receptor (MC4R) is a G-protein-coupled receptor expressed in the hypothalamus regulating appetite and energy expenditure. Extensive evidence from genetic and biological studies show that MC4R is a key player in the homeostatic regulation of body weight. MC4R loss of function (LoF) variants are the most common cause of monogenic obesity. We have identified 1 homozygous and 16 heterozygous MC4R variants in patients with obesity at our academic Obesity Center CGG, Erasmus MC. The impact of these variants on MC4R signaling and the association with obesity are unknown. Here, we functionally characterized these variants by analyzing four different aspects of MC4R signaling. HEK293 cells were transiently transfected with expression plasmids encoding wild type (WT) or variant MC4R and stimulated with melanocyte stimulating hormone. Cyclic AMP response (cAMP) was measured using GloSensor cAMP bioluminescence assay, and β-arrestin-2 recruitment (βarr2) was measured using NanoBiT complementation luminescence assay. Furthermore, HiBiT Detection System was used to measure cell surface expression, and serum response element (SRE) reporter assay was used to measure extracellular signal-regulated kinase (ERK) activation. Variants were classified according to the percent of maximum response (Emax) relative to WT: complete LoF (cLoF): 0-20%; partial LoF (pLoF): 20-80%; WT: 80-120%; gain of function (GoF): >120%. The MC4R variants were identified by sequencing the MC4R gene of adult and pediatric patients with obesity using an obesity gene panel. Eleven of these variants have not been functionally studied previously. The median age of onset obesity for all patients is 3 years (range 0 – 6). Furthermore, the median BMI of the adult patients was 48.8 kg/m2 (range 36 - 58.8) and the median BMI-SDS of the pediatric patients was +4.2 SDS (range +3 – 7). Twelve out of 17 patients presented with hyperphagia. MC4R variants had differential effects on signaling. In 7 out of 17 variants, cLoF for cAMP was observed. This could be explained in 6 out of 7 of these variants due to lack of cell surface expression. Intriguingly, five out of 17 variants had a normal or GoF cAMP response and normal ERK activation. However, three out of these 5 variants showed cLoF or pLoF for βarr2, indicating a disrupted desensitization mechanism. In addition, the remaining five variants displayed pLoF for most studied pathways. We show that these MC4R variants identified in our patients with obesity affect signaling differently, through modulation of cAMP, βarr2, cell surface expression, and ERK pathways. This demonstrates the value of examining different aspects of MC4R signaling to understand possible biased effects of variants on these pathways. Overall, our results show the clinical importance of assessing the effect of MC4R variants on a range of molecular signaling mechanisms to determine their association with obesity. Presentation: Saturday, June 17, 2023

Functional characterization of melanocortin 2 receptor (Mc2r) from a lobe-finned fish (Protopterus annectens) and insights into the molecular evolution of melanocortin receptors

Recent studies from our group on melanocortin 2 receptors (Mc2r) from basal families of actinopterygians have served to resolve that Mrap1 dependence and ACTH selectivity are features of even the most basal ray-finned fishes. However, there have been no studies on Mc2r function of the basal sarcopterygians, the lobe-finned fishes, represented by the extant members coelacanths and lungfishes. Here, we offer the first molecular and functional characterization of an Mc2r from a lobe-finned fish, the West African lungfish (Protopterus annectens). Plasmids containing cDNA constructs of lungfish (lf) Mc2r and Mrap1 were expressed in mammalian and zebrafish cell lines. Cells were then stimulated by human ACTH(1–24) and melanocyte stimulating hormone (α-MSH), as well as alanine-substituted analogs of hACTH(1–24) targeting residues within the H6F7R8W9 and K15K16R17R18P19 motifs. Activation of lfMc2r was assessed using a cAMP-responsive luciferase reporter gene assay. In these assays, lfMc2r required co-expression with lfMrap1, was selective for ACTH over α-MSH at physiological concentrations of the ligands, and was completely inhibited by multiple-alanine substitutions of the HFRW (A6–9) and KKRRP (A15–19) motifs. Single- and partial-alanine substitutions of the HFRW and KKRRP motifs varied in their impacts on receptor-ligand affinity from having no effect to completely inhibiting lfMc2r activation. This characterization of the Mc2r of a lobe-finned fish fulfills the last major extant vertebrate group for which Mc2r function had yet to be characterized. In doing so, we resolve that all basal bony vertebrate groups exhibit Mc2r function that substantially differs from that of the cartilaginous fishes, indicating that rapid and dramatic shift in Mc2r function occurred between the radiation of cartilaginous fishes and the emergence of bony fishes. We support this interpretation with a molecular clock analysis of the melanocortin receptors, which demonstrates the uniquely high rate of sequence divergence in Mc2r. Much remains to be understood regarding the molecular evolution of Mc2r during the early radiation of vertebrates that resulted in the derived functional characteristics of Mrap1 dependence and exclusive selectivity for ACTH.

Avian opioid peptides: evolutionary considerations, functional roles and a challenge to address critical questions.

The present review considers the putative hormonal opioid peptides in birds. In birds and all other vertebrates, there are four opioid related genes encoding a series of peptides. These genes are, respectively, proenkephalin (PENK), prodynorphin (PDYN), pronociceptin (PNOC) and proopiomelanocortin (POMC). Proenkephalin (PENK) encodes Met- and Leu-enkephalin together with peptides containing met enkephalin motifs in birds, mammals and reptiles. Proopiomelanocortin (POMC) encodes β endorphin together with adrenocorticotropic hormone (ACTH), and melanocyte stimulating hormone (MSH). Prodynorphin (PDYN) encoding dynorphins A and B with α- and β-neoendorphins together intermediate polypeptides across the vertebrates. Pronociceptin (PNOC) encodes nociceptin together with possibly putative avian nocistatin and a non-opioid peptide derived from the C terminal of pronociceptin. There is a high degree of identity in the sequences of enkephalin peptides, dynorphin-A and B and nociceptin in birds and, to a less extent, across vertebrates. The opioid peptides exert effects related to pain together with other biological actions such as growth/development acting via a series of opioid receptors. What is unclear, particularly in birds, is the biological roles and interactions (additivity, antagonistic and synergistic) for the individual opioid peptides, the processing of the prohormones in different tissues and the physiological relevance of the different peptides and, particularly, of the circulating forms.

Nodakenin Inhibits Melanogenesis Via the ERK/MSK1 Signaling Pathway.

The aim of the present study was to investigate the potential inhibitory effects of nodakenin, a coumarin glucoside derivative from the root extract of Angelica gigas Nakai (AGN), on melanogenesis and its underlying mechanisms in B16F10 melanoma cells. The inhibitory effects of nodakenin on melanogenesis were evaluated by determining melanin contents and tyrosinase activity in α -melanocyte stimulating hormone (α-MSH)-treated B16F10 melanoma cells. The mechanisms associated with the anti-pigmentation effect of nodakenin were investigated by quantitative real-time PCR and immunoblotting analysis. Using the UVB-irradiated conditioned media culture system and UVB-irradiated co-cultivation system of HaCaT keratinocytes and B16F10 melanoma cells mimicking in vivo melanin biosynthesis, the effect of nodakenin on melanin production was evaluated. Melanin content analysis showed that nodakenin decreased cellular melanin biosynthesis in α-MSH-treated B16F10 cells. Immunoblotting revealed that CREB phosphorylation, MITF, a mastering transcription factor of melanogenesis and its downstream genes tyrosinase, tyrosinase-related protein 1, and tyrosinase-related protein 2 were downregulated by nodakenin in a dose-dependent manner. Interestingly, nodakenin did not affect the phosphorylation of PKA and p38 MAPK but the phosphorylation of ERK1/2 and MSK1. In addition, the inhibition of melanin accumulation by nodakenin in the UVB-irradiated conditioned media culture system and UVB-irradiated co-cultivation system of HaCaT and B16F10 cells suggests that nodakenin has potential as an anti-pigmentation activity. These data suggest that nodakenin inhibits the melanogenesis in B16F10 cells by interfering the ERK/ MSK1/CREB axis and thus preventing MITF expression.

Laser-assisted drug delivery of synthetic alpha melanocyte stimulating hormone and L-tyrosine leads to increased pigmentation area and expression of melanogenesis genes in a porcine hypertrophic scar model.

One symptom of hypertrophic scar (HTS) that can develop after burn injury is dyschromia with hyper- and hypopigmentation. There are limited treatments for these conditions. Previously, we showed there is no expression of alpha melanocyte stimulating hormone (α-MSH) in hypopigmented scars, and if these melanocytes are treated with synthetic α-MSH in vitro, they respond by repigmenting. The current study tested the same hypothesis in the in vivo environment using laser-assisted drug delivery (LADD). HTSs were created in red Duroc pigs. At Day 77 (pre), they were treated with CO2 fractional ablative laser (FLSR). Synthetic α-MSH was delivered as a topical solution dissolved in l-tyrosine (n = 6, treated). Control scars received LADD of l-tyrosine only (n = 2, control). Scars were treated and examined weekly through Week 4. Digital images and punch biopsies of hyper, hypo-, and normally pigmented scar and skin were collected. Digital pictures were analyzed with ImageJ by tracing the area of hyperpigmentation. Epidermal sheets were obtained from punch biopsies through dispase separation and RNA was isolated. qRT-PCR was run for melanogenesis-related genes: tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1), and dopachrome tautomerase (DCT). Two-way ANOVA with multiple comparisons and Dunnett's correction compared the groups. The areas of hyperpigmentation were variable before treatment. Therefore, data is represented as fold-change where each scar was normalized to its own pre value. Within the LADD of NDP α-MSH + l-tyrosine group, hyperpigmented areas gradually increased each week, reaching 1.3-fold over pre by Week 4. At each timepoint, area of hyperpigmentation was greater in the treated versus the control (1.04 ± 0.05 vs. 0.89 ± 0.08, 1.21 ± 0.07 vs. 0.98 ± 0.24, 1.21 ± 0.08 vs. 1.04 ± 0.11, 1.28 ± 0.11 vs. 0.94 ± 0.25; fold-change from pre-). Within the treatment group, pretreatment, levels of TYR were decreased -17.76 ± 4.52 below the level of normal skin in hypopigmented scars. After 1 treatment, potentially due to laser fractionation, the levels decreased to -43.49 ± 5.52. After 2, 3, and 4 treatments, there was ever increasing levels of TYR to almost the level of normally pigmented skin (-35.74 ± 15.72, -23.25 ± 6.80, -5.52 ± 2.22 [p < 0.01, Week 4]). This pattern was also observed for TYRP1 (pre = -12.94 ± 1.82, Week 1 = -48.85 ± 13.25 [p < 0.01], Weeks 2, 3, and 4 = -34.45 ± 14.64, -28.19 ± 4.98, -6.93 ± 3.05 [p < 0.01, Week 4]) and DCT (pre = -214.95 ± 89.42, Week 1 = -487.93 ± 126.32 [p < 0.05], Weeks 2, 3, and 4 = -219.06 ± 79.33, -72.91 ± 20.45 [p < 0.001], -76.00 ± 24.26 [p < 0.001]). Similar patterns were observed for scars treated with LADD of l-tyrosine alone without NDP α-MSH. For each gene, in hyperpigmented scar, levels increased at Week 4 of treatment compared to Week 1 (p < 0.01). A clinically-relevant FLSR treatment method can be combined with topical delivery of synthetic α-MSH andl-tyrosine to increase the area of pigmentation and expression of melanogenesis genes in hypopigmented HTS. LADD of l-tyrosine alone leads to increased expression of melanogenesis genes. Future studies will aim to optimize drug delivery, timing, and dosing.

CORRELATION OF SERUM ZINC LEVELS WITH SEVERITY AND DISEASE ACTIVITY IN VITILIGO PATIENTS AT SANJIWANI GIANYAR HOSPITAL

Vitiligo is autoimmune disease, characterized by well defined milky-white macule, caused by destruction of melanocyte selectively. Management of vitiligo is still challenging due to the pathogenesis is not yet fully understood, and vitiligo can caused significant psychological distress to the patients. Several studies reveal the role of zinc as an important element in the prevention and treatment of vitiligo based on zinc's function as an antiapoptotic, as a bull against free radicals, and as an important element in melanogenesis by stimulating cell mediated immunity activity, zinc and alpha melanocyte stimulating hormone. We conducted an analytical cross-sectional study that aims to determine the correlation between plasma zinc levels and the severity of vitiligo using the VASI score and vitiligo disease activity calculated based on the VIDA score. The results showed that there was a strong negative correlation between serum zinc levels and the VASI score, with a correlation coefficient or r = -0.668 and p &lt;0.05 and there was a negative correlation between serum zinc levels and the VIDA score with a correlation coefficient (r) = -0.342 and p &lt; 0.05.

Effects of agonists of melanocortin receptors MC3Rand MC4R on components of sexual behavior of male rats reared in condition of chronic social isolation

BACKGROUND: Melanocortins, including -melanocyte stimulating hormone (MSH), MSH, MSH, and adrenocorticotropic hormone, are products of the polypeptide proopiomelanocortin. These products bind to five different melanocortin receptors (MC1R, MC2R, MC3R, MC4R, MC5R) with different affinities. Because MC3R and MC4R are the major types expressed in the brain, these two receptors can mediate the behavioral effects of melanocortins.&#x0D; AIM: To clear the role of MC4R in sexual behavior of male rats after social isolation from relatives.&#x0D; MATERIALS AND METHODS: In the present study, 40 naive male Wistar rats divided into 4 groups, 3 of which were grown in complete social and partial sensory isolation, received saline, PT-141 (MC3R/MC4R agonist) in a dose 0.3 g intraperitoneally, and THIQ (MC4R agonist) in a dose 0.1 g intranasally. Behavioral effects were registered in a cage with unreachable reinforcement in which the female in the estrus phase, separated by a transparent perforated barrier, was kept for 10 minutes under red light. Blood samples were taken 30 minutes after administration from the tail vein. Testosterone concentrations were measured by ELISA.&#x0D; RESULTS: Social isolation had no significant effect on latent time before trying to reach a female but decreased the time spent near the cage with a female. Isolated animals did not show genital grooming acts during the experiment. PT-141 decreased the latent time to approach the female, increased the time spent near the female cage, and stimulated genital grooming. THIQ decreased the latent time to reach a female and stimulated genital grooming. At the same time, THIQ had no effect on the time spent near the female cage. Social isolation reduced testosterone levels more than twice compared to controls. The administration of PT-141 and THIQ had no effect on testosterone concentration.&#x0D; CONCLUSIONS: The results confirm the depressing effect of chronic social isolation stress on the sexual motivation of male rats and demonstrate different roles of melanocortin MC3R/MC4R receptors in the realization of sexual behavior.

The integrative panel of fatty acid desaturase-2 (FADS2) rs174583 gene polymorphism and dietary indices (DQI-I and HEI) affects cardiovascular risk factors among obese individuals

BackgroundRecent studies have shown that dietary intakes and gene variants have a critical role in the obesity related comorbidities. This study aimed to evaluate the effects of the interactions between Fatty acid desaturase 2 (FADS2) gene rs174583 polymorphism and two dietary indices on cardiometabolic risk factors.MethodsThis cross-sectional study was carried out on 347 obese adults aged 20-50 years old in Tabriz, Iran. Healthy eating index (HEI) and Diet quality index-international (DQI-I) were evaluated by a validated semi-quantitative 147-item Food frequency questionnaire (FFQ). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine FADS2 gene variants. Multivariate analysis of covariance (MANCOVA) was used to identify gene-diet interactions on metabolic parameters.ResultsWaist circumference (WC) and serum triglyceride (TG) levels were significantly higher among carriers of TT genotype of FADS2 gene (P < 0.05). In addition, the interactions between FADS2 gene rs174583 polymorphism and DQI-I had significant effects on weight (P interaction = 0.01), fat mass (P interaction = 0.04), fat free mass (P interaction = 0.03), and Body mass index (BMI) (P interaction = 0.02); the highest level of these parameters belonged to TT carriers. Similarly, the interactions between FADS2 gene variants and HEI had significant effects on insulin (P interaction < 0.001), Homeostasis model assessment of insulin resistance (HOMA-IR) (P interaction < 0.001), Quantitative insulin check index (QUICKI) (P interaction = 0.001), and alpha Melanocyte stimulating hormone (α-MSH) (P interaction = 0.03).ConclusionIn this study, for the first time, we reported the effects of gene-diet interactions on metabolic traits. Compliance with dietary indices (DQI-I and HEI) ameliorated the adverse effects of gene variants on metabolic risk factors, especially in heterogeneous genotypes. Further prospective cohort studies are needed to confirm these results.

Short-term effects of α-melanocyte-stimulating hormone in three distinct melanin-pigmented cell types of Anura.

Ectothermic animals present melanin-containing cells in their integument and viscera. Besides cutaneous melanophores, amphibians have melanomacrophages in the hepatic parenchyma and melanocytes in the viscera, which are also present in their testicular stroma. The native melanocyte stimulating hormone (α-MSH) is the main hormone that modulates the color change in melanophores. However, we still know too little about how the α-MSH acts in vivo on visceral melanin-containing cells. In this study, we collected 30 adult males of Physalaemus nattereri (Anura, Leptodactylidae) to evaluate the short-term effects of α-MSH on melanophores, melanocytes and melanomacrophages under light microscopy. For this, we injected 0.05 ml of a single intraperitoneal dose containing 2.5x10-7 mmol/10g of α-MSH, diluted in ringer solution, in five experimental groups with five individuals each one. The different groups were analyzed after 1, 3, 6, 12 and 24h. The control group with five other individuals received only 0.05 ml of ringer solution. The skin pigmentation increased quickly after animals received the hormone α-MSH with the consequent darkening of the body (body darkness). Melanophores, melanocytes and melanomacrophages responded similarly to the test, with an increase in the area containing melanin. However, melanophores and melanomacrophages reached their darkest pigmentation in a shorter period of time in comparison to the testicular melanocytes, probably due to specific metabolic characteristics of each organ. Thus, we verified that the three types of cells, although present in different organs, are responsive to the native hormone α-MSH, which enables us to treat them as a pigmentary system.

Decrypting the Potential of Nanotechnology-Based Approaches as Cutting-Edge for Management of Hyperpigmentation Disorder.

The abundant synthesis and accretion of melanin inside skin can be caused by activation of melanogenic enzymes or increase in number of melanocytes. Melasma is defined as hyperpigmented bright or dark brown spots which are symmetrically distributed and have serrated and irregular borders. The three general categories of pigmentation pattern include centro facial pattern, malar pattern, and mandibular pattern. Exposure to UV rays, heat, use of cosmetics and photosensitizing drugs, female sex hormonal therapies, aberrant production of melanocyte stimulating hormone, and increasing aesthetic demands are factors which cause the development of melasma disease. This review gives a brief overview regarding the Fitzpatrick skin phototype classification system, life cycle of melanin, mechanism of action of anti-hyperpigmenting drugs, and existing pharmacotherapy strategies for the treatment of melasma. The objectives of this review are focused on role of cutting-edge nanotechnology-based strategies, such as lipid-based nanocarriers, i.e., lipid nanoparticles, microemulsions, nanoemulsions, liposomes, ethosomes, niosomes, transfersomes, aspasomes, invasomes penetration-enhancing vesicles; inorganic nanocarriers, i.e., gold nanoparticles and fullerenes; and polymer-based nanocarriers i.e., polymeric nanoparticles, polymerosomes, and polymeric micelles for the management of hyperpigmentation.

The mechanisms of melanogenesis inhibition by glabridin: molecular docking, PKA/MITF and MAPK/MITF pathways

Glabridin is the main ingredient of hydrophobic fraction in licorice extract and has been shown to have anti-melanogenesis activity in skins. However, the underlying mechanism(s) remain not completely understood. The aim of this study is thus to elucidate the possible mechanisms related to the melanogenesis suppression by glabridin in cultured B16 murine melanoma cells and in UVA radiation induced hyperpigmentation model of BALB/c mice as well. Molecular docking simulations revealed that between catalytic core residues and the compound. The treatment by glabridin significantly downregulated both transcriptional and/or protein expression of melanogenesis-related factors including melanocyte stimulating hormone receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), TYR-related protein-1 (TRP-1) and TRP-2 in B16 cells. Both PKA/MITF and MAPK/MITF signaling pathways were found to be involved in the suppression of melanogenesis by glabridin in B16 cells. Also in vivo glabridin therapy significantly reduced hyperpigmentation, epidermal thickening, roughness and inflammation induced by frequent UVA exposure in mice skins, thus beneficial for skin healthcare. These data further look insights into the molecular mechanisms of melanogenesis suppression by glabridin, rationalizing the application of the natural compound for skin healthcare.

Interferon-gamma induces melanogenesis via post-translational regulation of tyrosinase.

Melanogenesis (melanin pigment production) in melanocytes is canonically stimulated by the alpha melanocyte stimulating hormone (αMSH), which activates the cyclic-AMP-mediated expression of the melanocyte inducing transcription factor (MITF) and its downstream melanogenic genes, including the principal rate-limiting melanogenic enzyme tyrosinase (TYR). Here, we report that interferon-gamma (IFNG; type II interferon), but not interferon-alpha (a type I interferon), induces a noncanonical melanogenic pathway in mouse and human melanocytic cells. Inhibition of IFNG pathway by the JAK1/2 inhibitor ruxolitinib or knocking out Stat1gene abrogated the IFNG-induced melanogenesis. Interestingly, IFNG-induced melanogenesis was independent of MITF. IFNG markedly increased the TYR protein expression but did not affect the mRNA expression, suggesting a post-translational regulatory mechanism. In contrast, IFNG had no effect on the expression of other melanogenesis-related proteins, for example, tyrosinase-related protein 1 (TYRP1) and dopachrome tautomerase (DCT). Glycosidase digestion assays revealed that IFNG treatment increased the mature glycosylated form of TYR, but not its de novo synthesis. Moreover, cycloheximide chase assay showed that degradation of TYR was decreased in IFNG-treated cells. These results suggest that the IFNG-STAT1 pathway regulates melanogenesis via regulation of the post-translational processing and protein stability of TYR.

A multicenter-retrospective study of non-small-cell lung carcinoma harboring uncommon epidermal growth factor receptor (EGFR) mutations: different subtypes of EGFR exon 19 deletion-insertions exhibit the clinical characteristics and prognosis of non-small cell lung carcinoma.

BackgroundThe aim of this study was to investigate the clinical features, immunohistochemistry (IHC), compound mutation, and prognosis of patients with non-small cell lung cancer (NSCLC) harboring exon 19 deletion-insertion mutations.MethodsThis retrospective analysis included 4,666 NSCLC patients harboring epidermal growth factor receptor (EGFR) mutations in a multi-center study from January 2017 to December 2020, and 69 patients with EGFR exon 19 deletion-insertions were taken to account. Next-generation sequencing (NGS) was used to detect the subtype of EGFR exon 19 deletion-insertions. These mutations were correlated with clinical features, immunophenotype and molecular characteristics of tumors and outcomes of patients.ResultsSixty-nine patients with EGFR exon 19 deletion-insertions were analyzed in this study, comprising 24 cases (34.8%) with L747_P753delinsS, 9 cases (13.1%) with L747_A750delinsP, both 5 cases (7.2%) in E746_A750delinsQP, E746_S752delinsV and both 4 cases (5.8%) in E746_T751delinsA and L747_T751delinsP. Twenty-nine males (42%) and 40 females (58%), with a median age of 59.7 years; 12 (21.7%) participants were smokers and 54 (78.3%) were nonsmokers. The compound mutations were tumor protein 53 (TP53) (45.83%), phosphoinositide-3-kinase (PIK3CA) (11.59%), and almost 16.67% in retinoblastoma 1 (RB1), melanocyte stimulating hormone (MSH), and myelocytomatosis (MYC). The best overall response was complete response (CR) in 47.8% of patients, partial response (PR) in 33.3% and stable disease (SD) in 13.1% of patients. Correlation between immunoreactivity of Napsin A, thyroid transcription factor (TTF), cytokeratin (CK7), surfactant proteins B (SPB), and the subtypes of EGFR exon 19 deletion-insertion was significantly statistically different (P<0.05). The disease control rate (DCR) was 29%. The median progression-free survival (mPFS) and 95% confidence interval (CI) of exon 19 deletion-insertion subtypes were 14.821 (9.917 to 19.726) months for L747_P753delinsS, 23.500 (15.877 to 31.123) months for L747_A750delinsP, 26.667 (11.731 to 41.603) months for L747_T751delinsP, and 11.713 (7.786 to 15.639) months for the others. Patients receiving treatment with 3rd generation tyrosine kinase inhibitors (TKI) had the shortest progression-free survival (PFS) (median: 7.179, 95% CI: 3.969–10.388).ConclusionsThe subtypes of exon 19 deletion-insertion exhibited different clinical characteristics compared with other common mutations. Our finding argued in favor of analyzing the correlation between immunoreactivity and the subtypes of EGFR exon 19 deletion-insertion. The EGFR exon 19 deletion-insertion mutations exhibited limited sensitivity to 3rd generation TKI. Moreover, in light of therapeutic effect for the subtype, L747_T751delinsP achieved longer PFS.

Particulate matter 2.5 induced hyperpigmentation in reconstructed human epidermis model (MelaKutis®).

Particulate matter 2.5 induced hyperpigmentation in reconstructed human epidermis model (MelaKutis®).

Characterization of Phenethyl Cinnamamide Compounds from Hemp Seed and Determination of Their Melanogenesis Inhibitory Activity.

Hyperpigmentation is induced by the overactivation of tyrosinase, which is a rate-limiting enzyme in melanogenesis. The defatted extract of hemp (Cannabis sativa L.) seed is known to have inhibitory effects on melanogenesis; however, effective compounds in the extract have not been identified yet. In this study, three phenethyl cinnamamides present in hemp seed extract were prepared by purification and chemical synthesis and were assessed for their inhibitory effect on melanogenesis in B16F10 melanoma cells. A comparison of the anti-melanogenesis and anti-tyrosinase activity of hemp seed solvent fractions revealed that the ethyl acetate fraction possessed the greatest potential for suppressing melanogenesis in melanoma cells by decreasing tyrosinase activity. We tentatively identified 26 compounds in the ethyl acetate fraction by comparing spectroscopic data with the literature. Three phenethyl cinnamamides such as N-trans-caffeoyltyramine, N-trans-coumaroyltyramine, and N-trans-feruloyltyramine present abundantly in the ethyl acetate fraction were prepared and their anti-melanogenesis and anti-tyrosinase activities in melanoma cells were evaluated. We found that N-trans-caffeoyltyramine and N-trans-feruloyltyramine inhibited alpha melanocyte stimulating hormone (α-MSH)-induced melanogenesis without cytotoxicity, while N-trans-coumaroyltyramine inhibited melanogenesis with cytotoxicity. IC50 values of N-trans-caffeoyltyramine, N-trans-feruloyltyramine, and N-trans-coumaroyltyramine for inhibition of α-MSH-mediated tyrosinase activation were 0.8, 20.2, and 6.3 μM, respectively. Overall, N-trans-caffeoyltyramine possessed the strongest anti-melanogenesis activity among the three phenethyl cinnamamides evaluated. The inhibitory effect of N-trans-caffeoyltyramine was verified by determining the melanin content and tyrosinase activity in melanoma after treating the cells with synthetic compounds. Thus, N-trans-caffeoyltyramine isolated from hemp seed extract could be useful in cosmetics as a skin-whitening agent.

302 Increased nociceptive thresholds associated with red hair are caused by reduced MC4R signaling

Humans and mice with natural red hair have elevated basal pain thresholds and an increased sensitivity to opioid analgesics. We investigated the mechanisms responsible for higher nociceptive thresholds in red-haired mice resulting from a loss of melanocortin 1 receptor (MC1R) function and found that the increased thresholds are melanocyte-dependent but melanin-independent. MC1R loss of function decreases melanocytic pro-opiomelanocortin transcription and systemic melanocyte stimulating hormone (MSH) levels in the plasma of red-haired (Mc1re/e) mice.

Hepatic melanocortin 1 receptor mediated lipid metabolism in cultured human liver (HEPG2) cells

Background and Aims: Melanocortins, consisting of melanocyte stimulating hormones (α-, β- and γ-MSH) and adrenocorticotropic hormone, mediate their functions through five different melanocortin receptors named from MC1-R to MC5-R. MC1-R is known to be an integral regulator of skin pigmentation and immune responses. Studies conducted in our research group have revealed that MC1-R deficiency in mice disturbs cholesterol and glucose homeostasis through a yet unknown mechanism. The aim of this project was to determine the role of MC1-R in hepatic lipid metabolism.