Melanocortin 1 Receptor Research Articles

Dysregulated Angiogenin and Related Pathways in the Ventral Midbrain of "Redhead" Mice with MC1R Disruption.

A relationship between the melanoma-related pigmentation gene melanocortin 1 receptor (MC1R) and Parkinson's disease (PD) has been previously suggested. The present study aims to investigate the gene expression pattern in the ventral midbrain (VMB) of MC1R extension (MC1Re/e) mice to provide insights into the underlying mechanism of dopaminergic neuron loss in these mice. RNA sequencing (RNA-seq) was conducted on VMB tissues from MC1Re/e mice and their wild-type (WT) C57BL/6J littermates. Gene expression levels and pathway activity were assessed using differential gene expression analysis, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Set Enrichment Analysis (GSEA). To validate the RNA-seq results, RT-qPCR, WB and ELISA were performed. Our analyses found significant transcriptomic differences in the VMB between MC1Re/e mice and WT controls. Several immune response-related pathways were identified to be downregulated in the MC1Re/e group. Angiogenin (ANG) was implicated in several of the enriched pathways in MC1Re/e mice. Furthermore, ANG was found to be significantly downregulated in the VMB of MC1Re/e mice, which was confirmed at both mRNA and protein levels. There was no significant difference in ANG protein levels in the serum of MC1Re/e and WT mice. Our results suggest a differential gene expression pattern in the VMB as a result of MC1R mutation. Notably, lower ANG expression may be involved in the neuronal loss observed in the VMB of the MC1Re/e mice.

Urbanization's hidden influence: Linking landscape alterations and feather coloration with pigeon's cholesterol levels.

Urbanization's hidden influence: Linking landscape alterations and feather coloration with pigeon's cholesterol levels.

Exterior characteristics and coat colour marker of MC1R gene in Bali Crossbred cattle

Crossbreeding between Bali cattle with exotic bulls (such as Simmental and Limousin) has been widely developed in several regions in Indonesia. This study aims to determine changes in exterior characteristics and differences in vital statistics of Bali cattle and their crosses in West Lombok Regen-cy. A total of 91 female cattle aged 1 to 5 years were sampled, consisting of 5 Bali cattle (100%Bali), 54 F1 (50%Bali), 21 G2 (75%Bali/25%Bali), and 11 G3 (12.5%Bali) cattle. Qualitative (color and shape) and quantitative cattle data (vital statistics) were collected through observation and measure-ment. Identification of Bali crossbred cattle genotypes that have different color patterns using molecu-lar markers of the MC1R gene with forward primer MC1R: 5'-GGTGAGTCTCGTGGAGAACG-3' and reverse primer MC1R: 5'-CGTAGAAGATGGAGATGTAGCG-3', at a target DNA sequence size of 308 bp. The dominant color results of Bali cattle showed brick red (60%) and brown (20%), and there was a dark brown and black color change of up to 100% in the crosses. DNA-pool sequencing of 14 samples indicated individual sequence differences, indicated by overlapping nucleotide arrays after the 174 sequence. Furthermore, sequencing of different color representatives from 12 individual sam-ples shows 4 SNPs, namely g.64C>T, g.147C>T, g.159C>T, dan g.235A>C in Bali crossbred cattle. The measurement of chest circumference of Bali cattle, crossbred F1, G2, and G3 aged 3 to 5 years were 151.80±9.60cm, 175.69±12.63 cm, 175.50±11.04cm, and 173.17±15.06cm, respectively.The re-sult indicate the significant differences of body measurement ((P<0.01). In conclusion, the F1 (50%Bali) crossbred produced superior performance. Single nucleotide polymorphism (SNP) can be used as a genetic marker for colour pattern the dark brown-black in crossbred Bali cattle. However, the com-prehenshive study in the future is still needed in the future for cattle crossbred Bali cattle at different generation.

Melanocortin 1 Receptor Regulates Pathological and Physiological Cardiac Remodeling.

The melanocortin 1 receptor (MC1R) is abundantly expressed in the skin and leukocytes, where it regulates skin pigmentation and inflammatory responses. Recently, MC1R was also found in the heart, but its functional role has remained unknown. We aimed to investigate whether MC1R is involved in the regulation of pathological or physiological cardiac remodeling. Recessive yellow mice, as a model of global MC1R deficiency, and cardiomyocyte-specific MC1R knockout mice were subjected to transverse aortic constriction or voluntary wheel running to induce pathological or physiological cardiac hypertrophy, respectively. Mice were phenotyped for cardiac structure and function by echocardiography, histology, and quantitative PCR analysis. H9c2 cells and neonatal mouse ventricular cardiac myocytes were used as invitro models to investigate the effects of pharmacological MC1R activation on hypertrophy-related responses. We found that the expression of MC1R progressively declines in the failing mouse heart. MC1R recessive yellow mice showed blunted hypertrophic response to transverse aortic constriction-induced pressure overload and exercise training. This phenotype was recapitulated in MC1R knockout mice, demonstrating that MC1R deficiency specifically in cardiomyocytes is responsible for the antihypertrophic effect. However, MC1R knockout mice subjected to pressure overload showed left ventricular dilatation that was associated with reduced ejection fraction and changes in left ventricular diastolic function. At the molecular level, the mRNA expression of myosin heavy chain β was upregulated in the hearts of MC1R knockout mice. In contrast, selective activation of MC1R promoted hypertrophic responses in cultured cardiomyocytes. Cardiomyocyte-specific MC1R deficiency attenuates physiological and pathological cardiac hypertrophy in mice, while pharmacological activation of MC1R promotes cardiomyocyte hypertrophy.

Assessment of Potential Drug-Drug Interactions for Novel Oral Melanocortin-1 Receptor Agonist Dersimelagon.

Dersimelagon is a novel investigational orally administered selective agonist of the melanocortin-1 receptor. The drug-drug interaction (DDI) potential of dersimelagon was investigated in both nonclinical (in vitro) and clinical studies. The invitro inhibition of CYP/UGT isoforms and efflux/uptake transporters by dersimelagon was assessed. The impact of 300-mg dersimelagon on the pharmacokinetics (PK) of substrate drugs and the effect of co-administering verapamil on 100-mg dersimelagon PK (as substrate drug) were investigated in healthy participants in a Phase 1 study. DDIs were assessed based on ratios of Cmax and AUC0-∞ of substrate drug administered alone and with dersimelagon (or verapamil). Relatively potent invitro inhibition of CYP2C9, CYP3A, UGT1A1, BCRP, P-gp, and OATPs by dersimelagon was observed. In the clinical study, exposures of atorvastatin (CYP3A, P-gp, BCRP, OATP substrate) rosuvastatin (BCRP and OATP substrate), and β-hydroxy simvastatin (metabolite of simvastatin) increased 2- to 3-fold (atorvastatin: Cmax LS mean ratio = 198.0%; AUC0-∞ ratio = 196.6%; rosuvastatin: Cmax ratio = 316.5%, AUC0-∞ ratio = 206.0%) when co-administered with dersimelagon. Midazolam (CYP3A substrate), digoxin (P-gp), pravastatin (OATP), and simvastatin (CYP3A) did not show any clinically relevant DDI effects when co-administered with dersimelagon. Dersimelagon exposure increased ~25% when co-administered with verapamil, an effect not considered clinically relevant. Dersimelagon 300 mg did not elicit major DDIs involving CYP/UGT enzymes and drug transporters; however, dersimelagon may have potential for clinically relevant DDIs with drugs that are substrates for BCRP, such as atorvastatin and rosuvastatin, and caution should be exercised when co-administering 300-mg dersimelagon with these statin drugs. Trial Registration: ClinicalTrials.gov: NCT04793295, NCT04402489, NCT04440592, NCT02834442, NCT03520036, NCT03503266.

An 211At-labeled alpha-melanocyte stimulating hormone peptide analog for targeted alpha therapy of metastatic melanoma.

Patients who develop metastatic melanoma have a very poor prognosis, and new treatments are needed to improve the response rates. Melanocortin-1 receptor (MC1R) is a promising target for radionuclide therapy of metastatic melanoma, and alpha-melanocyte stimulating hormone (α-MSH) peptide analogs show high affinities to MC1Rs. Because targeted alpha therapy (TAT) can be a desirable treatment for metastatic melanoma, this study aimed to develop an 211At-labeled α-MSH peptide analog for TAT of metastatic melanoma. We designed an α-MSH analog labeled with 211At using aneopentyl glycol scaffold via a hydrophilic linker. Preliminary studies using 125I-labeled α-MSH analogs were performed to identify suitable hydrophilic linkers. Then, [211At]NpG-GGN4c was prepared using a procedure similar to that of the 125I-labeled counterpart, [125I]NpG-GGN4b. The biodistribution profile of [211At]NpG-GGN4c in B16F10 tumor-bearing mice was compared with that of [125I]NpG-GGN4b. B16F10 tumor-bearing mice were treated with a single dose of vehicle or [211At]NpG-GGN4c (1 or 0.4 MBq). The D-Glu-D-Arg linker was identified as the optimal hydrophilic linker because of its high affinity for MC1R and good biodistribution profile, especially with low accumulation in the liver and intestine. [211At]NpG-GGN4c showed tumor accumulation comparable to that of [125I]NpG-GGN4b and maintained the tumor radioactivity retention from 1 to 3h postinjection. [211At]NpG-GGN4c exhibited a dose-dependent inhibitory effect on B16F10 xenograft growth without apparent body weight loss. [211At]NpG-GGN4c showed dose-dependent efficacy against B16F10 xenografts, suggesting that [211At]NpG-GGN4c is a promising TAT agent for treating metastatic melanoma.

Melanocortin-1 receptor expression as a predictive factor for postoperative outcomes in melanoma patients: a retrospective study.

This study aims to explore the relationship between melanocortin-1 receptor (MC1R) expression levels and clinical pathological parameters of melanoma, as well as its potential as a prognostic biomarker. This retrospective study included 99 melanoma patients in our hospital from June 2017 to July 2023. MC1R expression was assessed by immunohistochemistry assays. Histochemistry score (H-score) determined the level of MC1R immunohistochemistry expression in melanoma. The relationships among MC1R expression, clinical pathological parameters in melanoma patients were assessed using Chi-square and Fisher's precision probability tests. Kaplan-Meier assay and log-rank test were utilized to estimate survival curves. Potential independent factors among the enrolled patients were investigated using COX regression analysis. According to median value of H-score, 38 cases with low MC1R expression and 61 cases with high MC1R expression in melanoma tumor tissues were observed. Patients with high MC1R expression in melanoma tissues exhibited a worse prognosis compared to patients with low MC1R expression. The survival time difference was statistically significant [MC1R expression in melanoma tumor tissue (MC1RT): median DFS, 12.83 vs. 17.53 months, χ2 = 5.395, P=0.0202; median OS, 16.47 vs. 21.77 months, χ2 = 5.082, P=0.0243. MC1R expression in normal adjacent to melanoma tissue (MC1RN): median DFS, 12.03 vs. 14.29 months, χ2 = 6.864, P=0.0088; median OS, 16.73 vs. 21.77 months, χ2 = 5.649, P=0.0175]. Multivariate COX regression model analysis indicated that MC1RN, MC1RT, sex, ESR, tumor site, targeted therapy, and immunotherapy were potential prognostic factors for the DFS. Furthermore, MC1RN, MC1RT, sex, tumor site, TLN, PLN, and immunotherapy were potential prognostic factors for the OS. Calibration curve indicated the predicted probabilities of nomogram models were in accordance with the actual probabilities, and the prediction accuracy was relatively high at one year and three years following surgery. The decision clinical curve revealed that the nomogram models had better predictive performance for DFS and OS than the MC1RT or MC1RN thresholds. Low MC1R expression in melanoma tumor tissues and adjacent normal tissue might be beneficial for the prognosis of melanoma patients. MC1R was a predictive factor for the prognosis of melanoma patients. Nomogram models based on MC1R demonstrated good prediction ability.

Local Anesthetic Duration, Not Onset, Linked to MC1R Genotype in Redheads and Brunettes.

Evidence suggests that redheaded individuals react differently to local anesthetics, but there is no defined human genotype associated with local anesthetic response. As red hair has been associated with unique mutations of the melanocortin-1 receptor (MC1R), we tested the hypothesis that local anesthetic onset and duration of action were significantly modified in red haired individuals as related to the single nucleotide polymorphism (SNP) genotype. Ninety-two participants between the ages of 18 and 65 years were enrolled and assigned to one of four experimental groups: lidocaine-redhead, lidocaine-brunette hair, bupivacaine-redhead, and bupivacaine-brunette hair. Onset and duration of action were quantified in response to sharp sensation. Sputum samples were collected, gDNA was extracted and subjected to the Illumina CoreExome-24 SNP array (Illumina, San Diego, California). Twenty-five MC1R sequence polymorphisms were analyzed. A two-way analysis of variance (ANOVA) test was used to examine treatment and hair color effects, and their interaction on onset and duration time respectively; P ≤ .05 was considered statistically significant. Overall mean onset of action was statistically significant (P = .042) when comparing red hair to brunette responses between anesthesia (lidocaine versus bupivacaine: 2.68 ± 0.28 minutes versus 3.60 ± 0.30 minutes, and 4.46 ± 0.49 minutes versus 5.14 ± 0.46 minutes, respectively). The redhead mean duration times were statistically shorter (P = .007) than brunettes (lidocaine and bupivacaine: 72.5 ± 6.3 min versus 97.6 ± 12.1 min, and 367.7 ± 21.4 minutes versus 455.5 ± 30.2 minutes, respectively). There were no statistical interactions between treatment and hair color on either onset or duration (P = .761 and P = .120, respectively). Interestingly, bupivacaine-injected redhead participants did show a significantly shorter duration (P = .004). Of 25 SNPs from MC1R assayed from the Illumina CoreExome-24 array, two missense mutations at loci rs1805007 (R151C) and rs1805008 (R160W) significantly predicted phenotypic responses to local analgesics. A two-way ANOVA indicated that these SNPs were significantly associated with reduced onset and duration time (P = .014, P = .047, respectively). Additionally, χ2 tests demonstrated a significantly strong correlation between red hair and these SNPs: R151C (P < .001, Power = 1.000) and R160W (P = .016, Power = 0.732). To our knowledge there are no published studies that associate the effect of hair color with local anesthetic function on onset and duration of action via SNP genotyping. The SNP genotyping reaffirmed functional results, and points to the complimentary impact that precision medicine will have on clinical decision making and patient comfort with future studies to unravel the degree to which SNPs affect these responses.

Localization of Melanocortin 1 Receptor in the Substantia Nigra.

Recent findings have revealed that melanocortin 1 receptor (MC1R) deficiency leads to Parkinson's disease-like dopaminergic neurodegeneration in the substantia nigra (SN). However, its precise distribution and expressing-cell type in the SN remain unclear. Therefore, in this study, we analyzed the localization and characteristics of MC1R in the SN using histological methods, including in situ hybridization and immunohistochemistry. Our findings reveal that MC1R was slightly present in dopaminergic neurons in the ventral tier of SN pars compacta dorsal (vSNCD), a region particularly vulnerable to PD-related neurodegeneration. Notably, we discovered that MC1R is highly present in parvalbumin (PV)-positive neurons, which were also vesicular GABA transporter messenger RNA-expressing inhibitory neurons of the lateral SN pars reticulata (lSNR). Intracellular analysis demonstrated that MC1R was present not only in the plasma membrane but also in mitochondrial and endoplasmic reticulum membranes. Furthermore, MC1R co-localized with attractin (Atrn), a known MC1R modulator, in nearly all MC1R-positive neurons. Therefore, it has been suggested that MC1R and Atrn work together to regulate dopaminergic neurons in the SN through both direct expression and indirect modulation via PV-positive inhibitory neurons. These findings provide new insights into MC1R's role in the SN and its potential contribution to PD pathophysiology.

Self-assessed improved sun protection after diagnosis of melanoma is associated with improved survival.

Although ultraviolet radiation is the most important risk factor for skin cancer in general, its role in disease control after the diagnosis of melanoma remains to be elucidated. To analyse the association between survival and self-assessed sun protection behaviour after a melanoma diagnosis. This was a questionnaire-based pilot study. We used patient data from the Molecular Markers of Melanoma Study programme to select patients with a histologically verified, invasive cutaneous melanoma, diagnosed at stage I or II according to the American Joint Committee on Cancer's AJCC Cancer Staging Manual 8th edition, between 1981 and 2014. In total, 843 patients with melanoma were asked whether their diagnosis had influenced their sun protection behaviour and, if 'Yes', they were asked to describe, in their own words, how the diagnosis affected their behaviour. We excluded 33 patients who were unable to answer and included 810 patient responses for analysis. Reports on sun protection behaviour before and after melanoma diagnosis were recorded. We found a significant association of increased melanoma-specific survival (P = 0.001) with improved self-assessed sun protection behaviour. After adjusting for age, sex, AJCC stage, localization of the primary tumour and prior ultraviolet light exposure (outdoor occupation, solarium use and sun cream use), improved sun protecting behaviour after melanoma diagnosis resulted in a decreased hazard ratio (HR) for melanoma-specific survival (adjusted HR 0.491, 95% confidence interval 0.270-0.896; P = 0.020). Stratification showed that those who benefited from improved sun protection were, in particular, male patients, patients diagnosed with melanoma after 50 years of age, patients with stage II melanomas and those carrying an MC1R gene variant. Self-assessed improved sun protection after diagnosis was significantly associated with reduced mortality due to melanoma. These results highlight the importance of improved sun awareness for patients after melanoma diagnosis, not only for preventing further melanomas but also reducing mortality risk.

Exploring the role of MC1R protein in Zebrafish Danio rerio by Molecular Modeling, Dynamics and Simulation Studies

The melanocortin-1 receptor protein (MC1R) is a G-protein-coupled receptor that plays an important role in anti-inflammatory and melanogenic activities, making it a promising therapeutic agent. Considering its functional diversity, we initially focus on predicting Zebrafish MC1R protein structure using EasyModeller v.4.0 to gain structural insights. Next, we describe the structure to highlight the importance of serine-threonine (ST) and aspartic acid-arginine-tyrosine (DRY) motifs, which are crucial for receptor activation and protein stability. Then, we demonstrate the molecular dynamics (MD) simulation of protein in an aqueous environment at 300 and 350 temperatures and present the trajectory analysis of receptor proteins in the dynamic system. We identify that the receptor protein had a significant conformational change with deviations at 300 K at 35 ps and 350 K at 55 ps, respectively. Notably, stability of the receptor protein was obtained at 300 K between 2.7 and 2.8 Å (400 and 600 ps) and at 350 K from 3.1 to 3.2 Å (400 and 600 ps), while this is the first report of the thermostability of the Zebrafish MC1R protein using MD as the main impact. Finally, we discuss how the receptor can be exploited as a therapeutic target for developing new peptides and drugs to improve skin pigmentation and treat pigmentary disorders.

Discovery of MT-7117 (Dersimelagon Phosphoric Acid): A Novel, Potent, Selective, and Nonpeptidic Orally Available Melanocortin 1 Receptor Agonist.

Activation of the melanocortin 1 receptor (MC1R) mediates melanogenesis in melanocytes, anti-inflammatory effects in inflammatory cells, and antifibrotic effects in fibroblasts. Thus, MC1R agonists are expected to be beneficial for treating skin, autoimmune, inflammatory, and fibrotic diseases. Afamelanotide, an α-melanocyte-stimulating hormone (α-MSH) analogue MC1R agonist, is used clinically for treating erythropoietic protoporphyria (EPP) as a subcutaneous implant formulation. We explored nonpeptidic small-molecule MC1R agonists with the aim of identifying more convenient oral drugs. By exploring the structure of previously reported compound 5, we discovered compound 11 (MT-7117: dersimelagon phosphoric acid). This compound exhibited strong MC1R agonistic activity, good pharmacokinetic properties, and excellent safety profiles. Furthermore, compound 11 was effective in animal pigmentation evaluation and skin fibrosis model studies. Compound 11 is currently in clinical trials for the treatment of EPP, X-linked protoporphyria (XLP), and systemic sclerosis (SSc). Proof of concept was obtained in phase 2 clinical studies on EPP and XLP.

Genome-Wide Association Study of Birth Wool Length, Birth Weight, and Head Color in Chinese Tan Sheep Through Whole-Genome Re-Sequencing.

The Chinese Tan sheep is a unique breed of sheep that is typical throughout China, mainly used for fur and meat production. They are widely distributed in northwestern China and are famous for their lambskin and shiny white curly wool. In this study, the phenotypic traits of wool length, birth weight, and head coat color were evaluated in 256 Chinese Tan sheep breeds. Whole genome sequencing generated 23.67 million high-quality SNPs for genome-wide association studies (GWAS). We identified 208 significant SNPs associated with birth wool length, implicating RAD50, MACROD2, SAMD5, SASH1, and SPTLC3 as potential candidate genes for this trait. For birth weight, 1056 significant SNPs, with 76.89% of them located on chromosome 2, were identified by GWAS, and XPA, INVS, LOC121818504, GABBR2, LOC101114941, and LOC106990096 were identified as potential candidate genes for birth weight. The GWAS for head coat color identified 1424 significant SNPs across three chromosomes, with 99.65% on chromosome 14, and SPIRE2, TCF25, and MC1R as candidate genes were found to be possibly involved in the development of the black-headed coat color in sheep. Furthermore, we selected head coat color as a representative trait and performed an independent test of our GWAS findings through multiplex PCR SNP genotyping. The findings validated five mutation sites in chromosome 14 (14,251,947 T>A, 14,252,090 G>A, 14,252,158 C>T, 14,252,329 T>G, and 14,252,464 C>T) within the exon1 of the MC1R gene (517 bp), as identified by GWAS in an additional 102 Tan sheep individuals, and revealed that black-headed sheep predominantly exhibited heterozygous genotypes, possibly contributing to their color change. Our results provide a valuable foundation for further study of these three economically important traits, and enhance our understanding of genetic structure and variation in Chinese Tan sheep.

Melanocortin 1 receptor mediates melanin production by interacting with the BBSome in primary cilia.

Production of melanin pigments is a protective mechanism of the skin against ultraviolet (UV)-induced damage and carcinogenesis. However, the molecular basis for melanogenesis is still poorly understood. Herein, we demonstrate a critical interplay between the primary cilium and the melanocortin 1 receptor (MC1R) signaling. Our data show that UV and α-melanocyte-stimulating hormone (α-MSH) trigger cilium formation in human melanocytes and melanoma cells. Deficiency of MC1R or the presence of its red hair color (RHC) variations significantly attenuates the UV/α-MSH-induced ciliogenesis. Further investigation reveals that MC1R enters the cilium upon UV/α-MSH stimulation, which is facilitated by the interaction of MC1R with the BBSome and the palmitoylation of MC1R. MC1R interacts with the BBSome through the second and third intercellular loops, which contain the common RHC variant alleles (R151C and R160W). These RHC variants of MC1R exhibit attenuated ciliary localization, and enforced ciliary localization of these variants elevates melanogenesis. Ciliary MC1R triggers a sustained cAMP signaling and selectively stimulates Sox9, which appears to up-regulate melanogenesis-related genes as the transcriptional cofactor for MITF. These findings reveal a previously unrecognized nexus between MC1R and cilia and suggest an important mechanism for RHC variant-related pigmentary defects.

A Ball Python Colour Morph Implicates MC1R in Melanophore-Xanthophore Distribution and Pattern Formation.

Reptiles showcase an extensive array of skin colours and patterns, yet little is known about the genetics of reptile colouration. Here, we investigate the genetic basis of the Clown colour morph found in captive-bred ball pythons (Python regius) to study skin pigmentation and patterning in snakes. We obtained samples by crowdsourcing shed skin from commercial breeders and hobbyists. We applied a case-control design, whole-genome pool sequencing, variant annotation, histological analyses, and electron microscopy imaging. We identified a missense mutation in a transmembrane region of the melanocortin-1 receptor (MC1R) associated with the Clown phenotype. In classic avian and mammalian model species, MC1R is known for controlling the type and amount of melanin produced. In contrast, our results suggest that MC1R signalling might play a key role in pattern formation in ball pythons, affecting xanthophore-melanophore distribution. This work highlights the varied functions of MC1R across different vertebrate lineages and promotes a novel model system to study reptile colouration.

Molecular and genetic characterization of sex-linked orange coat color in the domestic cat.

The Sex-linked orange mutation in domestic cats causes variegated patches of reddish/yellow hair and is a defining signature of random X-inactivation in female tortoiseshell and calico cats. Unlike the situation for most coat color genes, there is no apparent homolog for Sex-linked orange in other mammals. We show that the Sex-linked orange is caused by a 5 kb deletion that leads to ectopic and melanocyte-specific expression of the Rho GTPase Activating Protein 36 ( Arhgap36 ) gene. Single cell RNA-seq studies from fetal cat skin reveal that red/yellow hair color is caused by reduced expression of melanogenic genes that are normally activated by the Melanocortin 1 receptor (Mc1r)-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, but the Mc1r gene and its ability to stimulate cAMP accumulation is intact. Instead, we show that increased expression of Arhgap36 in melanocytes leads to reduced levels of the PKA catalytic subunit (PKA C ); thus, Sex-linked orange is genetically and biochemically downstream of Mc1r . Our findings solve a comparative genomic conundrum, provide in vivo evidence for the ability of Arhgap36 to inhibit PKA, and reveal a molecular explanation for a charismatic color pattern with a rich genetic history.

Exposure to Radiofrequency Electromagnetic Fields Enhances Melanin Synthesis by Activating the P53 Signaling Pathway in Mel-Ab Melanocytes.

The skin is the largest body organ that can be physiologically affected by exposure to radiofrequency electromagnetic fields (RF-EMFs). We investigated the effect of RF-EMFs on melanogenesis; Mel-Ab melanocytes were exposed to 1760 MHz radiation with a specific absorption rate of 4.0 W/kg for 4 h/day over 4 days. Exposure to the RF-EMF led to skin pigmentation, with a significant increase in melanin production in Mel-Ab melanocytes. The phosphorylation level of cAMP response element binding protein (CREB) and the expression of microphthalmia-associated transcription factor (MITF), which regulate the expression of tyrosinase, were significantly increased in Mel-Ab after RF-EMF exposure. Interestingly, the expression of tyrosinase was significantly increased, but tyrosinase activity was unchanged in the RF-EMF-exposed Mel-Ab cells. Additionally, the expression of p53 and melanocortin 1 receptor (MC1R), which regulate MITF expression, was significantly increased. These results suggest that the RF-EMF induces melanogenesis by increasing phospho-CREB and MITF activity. Importantly, when Mel-Ab cells were incubated at 38 °C, the melanin production and the levels of tyrosinase significantly decreased, indicating that the increase in melanin synthesis by RF-EMF exposure is not due to a thermal effect. In conclusion, RF-EMF exposure induces melanogenesis in Mel-Ab cells through the increased expression of tyrosinase via the activation of MITF or the phosphorylation of CREB, which are initiated by the activation of p53 and MC1R.

Plumage polymorphism in the black sparrowhawk (Accipiter melanoleucus) is strongly associated with the expression level of agouti signaling protein

Abstract Melanin-based plumage polymorphisms in birds are often associated with mutations in the melanogenesis genes, notably the melanocortin-1 receptor (MC1R), but may also arise through changes in the expression of these genes. Here we investigate the molecular basis of plumage polymorphism in both adult and juvenile black sparrowhawks (Accipiter melanoleucus), an African raptor that occurs in two adult color morphs, light and dark, and also exhibits variation in juvenile plumage coloration. Our results confirmed that plumage differences in adult morphs were a result of differential deposition of eumelanin in their ventral contour feathers. No polymorphisms in the coding regions of the MC1R or the agouti signaling protein (ASIP) genes associated with adult color morph were identified. However, lack of pigmentation in the developing breast feathers of light morph birds was strongly associated with elevated ASIP expression, and concomitant downregulation of the downstream melanogenesis genes microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), and tyrosinase-related protein 1 (TYRP1). Variation in the rufous colored plumage of juveniles was found to be due to covariation in eumelanin and pheomelanin levels in dorsal and ventral contour feathers. As in adult birds, an inverse relationship between melanin pigmentation and ASIP expression was observed. This covariation between eumelanin and pheomelanin levels is not consistent with the pigment type-switching model of melanogenesis, where increased ASIP expression results in a switch from eumelanin to pheomelanin production. This highlights the need for caution when extrapolating results from model systems to other animals and the value of conducting research in wild species.

Development of a qPCR assay for the quantification of canine autosomal DNA recovered from livestock attacks

Development of a qPCR assay for the quantification of canine autosomal DNA recovered from livestock attacks

52Mn-labelled Beta-cyclodextrin for Melanoma Imaging: A Proof-of-concept Preclinical Study.

As prostaglandin E2 (PGE2) and its receptors (EP2) are over-expressed on tumor cells and microenvironment, radiolabeled cyclodextrins targeting such biomolecules are valuable vector candidates in molecular cancer diagnostics. Using experimental melanoma models, we evaluated the in vivo imaging behavior of novel Manganese-52-labeled (52Mn) randomly methylated beta-cyclodextrin ([52Mn]Mn-DOTAGA-RAMEB) and compared it with the following well-established tumor-specific probes: melanocortin-1 receptor (MC1-R)-affine [68Ga]Ga-DOTA-NAPamide and PGE2 selective [68Ga]Ga-DOTAGA-RAMEB cyclodextrin. Post-injection of [68Ga]Ga-DOTA-NAPamide, [68Ga]Ga-DOTAGA-RAMEB, and [52Mn]Mn-DOTAGA-RAMEB into MC1-R positive B16F10 melanoma-bearing mice, tumor radio-pharmaceutical uptake was quantified in vivo and ex vivo using preclinical positron emission tomography (PET) and high-performance gamma counter. Although all tracers performed well in tumor identification, the highest standardized uptake values were detected in the [68Ga]Ga-DOTA-NAPamide scans. Corresponding to the ex vivo data, meaningful [52Mn]Mn-DOTAGA-RAMEB accumulation 1 h post-injection confirmed the tumor-targeting potential of the tracer. Temporal changes in PGE2/EP2 expression of the neoplasms may explain the significant differences observed between the tumor uptake of the two cyclodextrin probes and that of the 52Mn-labelled compound measured 1 h, 4 h, and 3 days post-injection (p≤0.01, p≤0.05). Although further pharmacokinetical optimization may be required, 52Mn-labelled cyclodextrin holds potential in melanoma diagnostics and the PET-based longitudinal assessment of tumor-associated PGE2/EP2 expression.