Dentre os vários marcadores genéticos existentes, alguns SNPs (Single Nucleotide Polymorphisms) podem estar associados à determinação de uma série de características fenotípicas (cor de pele, olhos e cabelos, estatura, forma do rosto, espessura do fio de cabelo) tendo sua predição um grande valor nas investigações forenses. Dentre os principais genes conhecidos por controlarem a pigmentação humana, através da produção da melanina, o SLC24A5 (solute carrier family 24, member 5) e o MC1R (melanocortin 1-receptor) apresentam um papel fundamental na melanogênese. O advento do sequenciamento de nova geração permitiu o processamento de várias regiões genômicas e indivíduos simultaneamente, aumentando a disponibilidade e precisão de dados de genomas completos, como alcançado em estudos como o 1000 Genomes Project. Nossas análises preliminares demonstraram que os dados de Fase 3 do 1000 Genomes são muito mais confiáveis do que as versões anteriores. Com esses dados, obtidos para 26 populações globais, foram realizadas análises populacionais (diversidade haplotípica, desequilíbrio de ligação, redes de haplótipo e de variância molecular) para os genes MC1R e SLC24A5 a fim de se compreender melhor seus padrões de diversidade, correlacionando-os à prováveis eventos de seleção natural que tenham moldado sua história evolutiva, como por exemplo a intensidade da radiação UV nas diferentes regiões geográficas. Alguns padrões foram encontradas entre os grupos africano, europeu e asiático, de acordo com a história evolutiva já descrita para estes grupos. Apesar disso, foi observado um padrão claro de varredura seletiva para o SLC24A5 nos resultados obtidos, como o alto desequilíbrio de ligação e baixa diversidade haplotípica. As análises da diversidade do SLC24A5 associadas com as zonas de incidência UV, no entanto, não apresentaram uma correlação clara entre a intensidade da radiação UV e a diversidade haplotípica / Among the various existing genetic markers, some SNPs may be associated with the determination of a series of phenotypic characteristics (skin, eyes and hair color, height, face shape, hair thickness) and its prediction could have a great value in forensic investigations. Among the major genes known to control human pigmentation through melanin production, SLC24A5 (solute carrier family 24, member 5) and MC1R (melanocortin-1 receptor) have a major role in melanogenesis. The advent of next-generation sequencing has enabled processing of several individuals and genomic regions simultaneously while increasing the availability and accuracy of whole genomes data, such as 1000 Genomes Project has achieved. Our preliminary analysis showed that Phase 3 data from the 1000 Genomes are far more reliable than previous versions. Using this data, obtained for 26 global populations, several analyzes were performed (haplotype diversity, linkage disequilibrium, haplotype networks and molecular variance) for MC1R and SLC24A5 in order to better understand their diversity patterns, correlating them to natural selection events which may have shaped their evolutionary history, such as UV radiation intensity in different geographical regions. Some patterns were found between African, European and Asian groups, according to the evolutionary history already described for these groups. Nevertheless, a strong pattern of selective sweep was observed for SLC24A5 in our data, such as high linkage disequilibrium and low haplotype diversity. Analysis of SLC24A5 diversity associated to UV, however, did not show a clear correlation between the UV radiation intensity and haplotype diversity

Dentre os vários marcadores genéticos existentes, alguns SNPs (Single Nucleotide Polymorphisms) podem estar associados à determinação de uma série de características fenotípicas (cor de pele, olhos e cabelos, estatura, forma do rosto, espessura do fio de cabelo) tendo sua predição um grande valor nas investigações forenses. Dentre os principais genes conhecidos por controlarem a pigmentação humana, através da produção da melanina, o SLC24A5 (solute carrier family 24, member 5) e o MC1R (melanocortin 1-receptor) apresentam um papel fundamental na melanogênese. O advento do sequenciamento de nova geração permitiu o processamento de várias regiões genômicas e indivíduos simultaneamente, aumentando a disponibilidade e precisão de dados de genomas completos, como alcançado em estudos como o 1000 Genomes Project. Nossas análises preliminares demonstraram que os dados de Fase 3 do 1000 Genomes são muito mais confiáveis do que as versões anteriores. Com esses dados, obtidos para 26 populações globais, foram realizadas análises populacionais (diversidade haplotípica, desequilíbrio de ligação, redes de haplótipo e de variância molecular) para os genes MC1R e SLC24A5 a fim de se compreender melhor seus padrões de diversidade, correlacionando-os à prováveis eventos de seleção natural que tenham moldado sua história evolutiva, como por exemplo a intensidade da radiação UV nas diferentes regiões geográficas. Alguns padrões foram encontradas entre os grupos africano, europeu e asiático, de acordo com a história evolutiva já descrita para estes grupos. Apesar disso, foi observado um padrão claro de varredura seletiva para o SLC24A5 nos resultados obtidos, como o alto desequilíbrio de ligação e baixa diversidade haplotípica. As análises da diversidade do SLC24A5 associadas com as zonas de incidência UV, no entanto, não apresentaram uma correlação clara entre a intensidade da radiação UV e a diversidade haplotípica / Among the various existing genetic markers, some SNPs may be associated with the determination of a series of phenotypic characteristics (skin, eyes and hair color, height, face shape, hair thickness) and its prediction could have a great value in forensic investigations. Among the major genes known to control human pigmentation through melanin production, SLC24A5 (solute carrier family 24, member 5) and MC1R (melanocortin-1 receptor) have a major role in melanogenesis. The advent of next-generation sequencing has enabled processing of several individuals and genomic regions simultaneously while increasing the availability and accuracy of whole genomes data, such as 1000 Genomes Project has achieved. Our preliminary analysis showed that Phase 3 data from the 1000 Genomes are far more reliable than previous versions. Using this data, obtained for 26 global populations, several analyzes were performed (haplotype diversity, linkage disequilibrium, haplotype networks and molecular variance) for MC1R and SLC24A5 in order to better understand their diversity patterns, correlating them to natural selection events which may have shaped their evolutionary history, such as UV radiation intensity in different geographical regions. Some patterns were found between African, European and Asian groups, according to the evolutionary history already described for these groups. Nevertheless, a strong pattern of selective sweep was observed for SLC24A5 in our data, such as high linkage disequilibrium and low haplotype diversity. Analysis of SLC24A5 diversity associated to UV, however, did not show a clear correlation between the UV radiation intensity and haplotype diversity

Dentre os genes conhecidos por influenciarem a variação normal de pigmentação de olhos, pele e cabelos em humanos, o gene MC1R (receptor de melanocortina 1) é o mais bem caracterizado até o momento. A atuação do MC1R ocorre pela produção de uma proteína transmembrana nos melanócitos, responsável pela regulação da produção de melanina nos mesmos. Sabe-se que a atuação do MC1R determina a proporção entre eumelanina (coloração castanha/preta) e feomelanina (coloração amarela/vermelha) presente nos melanócitos. O presente trabalho tem como objetivo analisar os SNPs conhecidos do gene MC1R com o propósito de se avaliar a influência da diversidade deste gene em características como a presença de sardas e variação da pigmentação dos olhos, pele e cabelos em humanos. Foram analisados 29 SNPs conhecidos da região codificadora do gene MC1R em 131 indivíduos da região de Ribeirão Preto, SP. A extração do DNA foi feita pela técnica de salting-out. A região codificadora do gene MC1R (951pb) foi amplificada em uma única reação de PCR, a qual foi seqüenciada em um analisador genético ABI-PRISM 310 por eletroforese capilar, utilizando-se os mesmos primers empregados para a amplificação. Dos 29 SNPs avaliados, 22 deles mostraram variação nas amostras estudadas, sendo que metade deles demonstrou estar associados a características de pigmentação. Observou-se um conjunto de SNPs associados claramente à fenótipos relacionados à feomelanina (+1645 A, +1858 T e +2260 C), enquanto outros se relacionam à ocorrência de eumelanina (+1558 G, +2322 G, +2346 A). A reconstrução de haplótipos gerou 31 haplótipos, sendo que quatro deles estavam associados à pele escura e dois outros tinham freqüências significativamente baixas em pele clara. Um haplótipo se associou a olhos verdes, enquanto dois outros tiveram associação com olhos castanho escuros. Cores escuras de cabelo se relacionaram à seis haplótipos distintos enquanto cabelos ruivos estavam associados à dois e um outro associado à cabelos loiros. Por fim, a ocorrência de sardas foi significativamente relacionada à três haplótipos. O presente trabalho apresenta associações significativas entre SNPs individuais e pigmentação de olhos, cabelos e pele, sendo que nossos dados confirmam que tal gene também desempenha papel relevante na variação de pigmentação na população brasileira. / Among the known genes influencing eye, skin and hair normal pigmentation variation, the MC1R (melanocortin l-receptor) gene is the best characterized so far. The activity of MC1R occurs due the production of a transmembrane protein in melanocytes, responsible for regulating the production of melanin. It is known that the performance of MC1R determines the ratio of eumelanin (brown color I black) and pheomelanin (yellow I red) present in melanocytes. This study aims to analyze known SNPs of the MC1R gene in order to evaluate the influence of this gene diversity on features like freckles and pigmentation variation of eyes, skin and hair in humans. We analyzed 29 known SNPs in the coding region of MC1R gene in 296 individuals from the region of Ribeirao Preto, Brazil. DNA extraction was performed using the salting-out technique. The MC1R gene coding region (951pb) was amplified in a single PCR reaction, which was sequenced on a ABI PRISM-310 genetic analyzer by capillary electrophoresis, using the same primers used for amplification. Of the 29 SNPs evaluated, only 22 showed variation in the samples studied, half of them showing to be associated with pigmentation characteristics. We observed a set of SNPs clearly associated to pheomelanin (+1645 A, +1831 T,+1858 T e +2260 C), while others related to eumelanin occurrence (+1558 G, +2322 G, +2346 A).Haplotype reconstruction generated 31 haplotypes. Four of them were associated with dark skin and two had significantly low frequencies in fair skin. One haplotype was associated with green eyes, while two other had aSSOciation with dark brown eyes. Darker hair color was associated with six different haplotypes, whereas red hair was associated with two and blonde hair with one haplotype. Finally, the absence or presence of freckles was significantly related to three haplotypes. Our study shows significant associations between individual SNPs and eyes, hair and skin pigmentation. The results presented here confirm that this gene also plays a relevant role in the pigmentation variation in the Brazilian population.

Hårfollikeln är en struktur som hittas hos alla däggdjur. Hår skyddar kroppen från UV-ljus, medverkar i kroppens värmereglering och har flera kommunikativa funktioner. Hårets varierande färg inom och mellan arter är både en fascinerande och intresseväckande egenskap som länge har studerats som en modell för genetisk nedärvning. I denna litteraturstudie ges en genomgång av hårfollikelns struktur och funktion, genetiken bakom hårets pigmentering samt didaktiska utmaningar i genetikundervisningen. Interaktioner mellan generna MC1R, ASIP (agouti) och POMC förklaras och exemplifieras. Dessutom diskuteras hur fårfollikeln och de pigmentreglerande generna kan användas i gymnasieskolan som ett exempel för komplicerade genetiska interaktioner. / The hair follicle is a structure found in all mammals. Hair protects the body from UV-induced damage, assists the body in its thermoregulation and has several communicative functions. The great variation in hair colour, both within and between species, is a captivating and intriguing trait that has been used as a model for genetic inheritance for a long time. This literature review features the structure and function of the hair follicle, the genetics behind the pigmentation of the hair as well as didactic challenges in teaching genetics. Interactions between the genes MC1R, ASIP (agouti) and POMC is both explained and illustrated. This review also discusses how the hair follicle and the genes regulating pigmentation can be used as an example of intricate genetic interactions in the upper secondary school. / <p>På grund av Covid-19 skedde presentation, opponering och respondering skriftligt på distans.</p>

No description available.

BRAF(V600E), the most commonly mutated oncogene in melanoma, is found in about half of patients. By hyperactivating the MAPK pathway, this mutation promotes cell growth and proliferation. Melanocytic BRAF(V600E) alone, however, is insufficient to cause melanoma and rather promotes the development of benign nevi (moles). The goal of our initial studies was to better understand how genetic and environmental risk factors interact with the BRAF(V600E) oncogene to induce melanoma. The two most prominent risk factors for melanoma development are exposure to ultraviolet (UV) radiation and pale skin pigmentation; particularly in the case of individuals with the “redhead” phenotype, who carry inactivating mutations in the MC1R G-protein coupled receptor. It has commonly been thought that redheads are at highest risk for melanoma development due to poor protection from genotoxic UV radiation from the sun. Using a melanocyte-specific, inducible Braf(V600E) mouse model, we have shown that an inactivating mutation in Mc1r which causes a redhead phenotype in mice, confers a significant UV-independent elevation in melanoma risk, relative to black and albino animals. The mechanism of accelerated UV-independent oncogenesis was found to be dependent on the synthesis of the red/yellow pheomelanin pigment. While these experiments were on-going, a novel small molecule inhibitor of the BRAF(V600E) oncogene, vemurafenib, began showing promising results in clinical trials. The observation that half of patients were experiencing significant tumor regression was unprecedented, but was soon followed by vemurafenib-resistant disease progression. Based on the fact that acquired drug resistance is a major obstacle to good therapeutic outcomes, we began investigating mechanisms of BRAF inhibitor resistance. A panel of BRAF(V600E) human melanoma cell lines that were initially sensitive to PLX4720 (a pre-clinical analog of vemurafenib), were chronically treated with the oncogenic BRAF inhibitor until resistance developed. These paired resistant and sensitive cell lines were characterized in terms of drug sensitivity and activation of cell signaling pathways. Multiple different patterns of drug resistance were found. The diversity of resistance mechanisms in these studies agrees with the diversity which others have found in the literature, suggesting that melanoma cells may be uniquely adaptable to circumventing BRAF(V600E) oncogene addiction.

Colouration is an important phenotypic trait of animals and plays a substantial role in the characteristics of individual animal species. The MC1R gene has an essential role in colouration. This thesis is focused on the study of sequence variability in this gene and subsequent phylogram formation in selected species, which are: Bos Primigenius Taurus, Sus Scrofa, Equus Caballus and Canis Lupus Familiaris. There were custom primers designed in Oligo for the selected exon sequence. Based on se-quencing, known polymorphisms in Canis Lupus Familiaris and Equus Caballus were detected. In Canis Lupus Familiaris sequence, there was a 790 A>G polymorphism. All of N sequenced samples (N = 10) carried the E (790AA) allele. In Equus Caballus se-quence, there was a 901 C>T polymorphism, with representatives of all genotypes nEE(901CC) = 2, nEe(901CT) = 2, nee(901TT) = 6. The thesis also provides a comprehensive overview of the phylogenetic tree for-mation process. For phylogenetic analysis, there were added sequences from other ani-mal species, gained from freely available genomic databases. The reconstruction took place in the MEGA X program with selected distance and sign methods. Only nodes with bootstrap support ≥ 70 could be interpreted. JC69 and HKY85 models were cho-sen as substitution models. The choice of models was statistically supported by testing likelihood in the Model Generator with P < 0,0001 support. The trees obtained by par-ticular methods were compared by the Pearson correlation coefficient.

Les ultraviolets A (UVA) sont carcinogènes et produisent des espèces réactives de l'oxygène (ERO). Le récepteur à la mélanocortine de type 1 (MC1R) est un récepteur couplé aux protéines G (RCPG) qui est impliqué dans la mélanogénèse et dans l'inflammation cutanée. Certains variants du gène sont associés à un risque accru de mélanomes et de carcinomes cutanés. Le MC1R est exprimé surtout dans les mélanocytes mais son expression peut être induite par les UV in vitro dans les kératinocytes et in vivo dans la peau. Le récepteur MC1R est activé par l'α-MSH. L'objectif de ce travail de thèse a été d'étudier les effets du récepteur MC1R sur le stress oxydatif induit par les UVA dans des lignées kératinocytaires humaines HaCaT exprimant le récepteur MC1R ou son variant non fonctionnel Arg151Cys. Nous avons montré que la production d'ERO intracellulaire induite par les UVA est fortement inhibée dans les cellules HaCaT-MC1R et que cette inhibition est renforcée en présence d'α-MSH. L'inhibition du stress oxydatif induit par les UVA dans les cellules transfectées par le MC1R est en partie dépendante de la phosphorylation de la sous-unité activatrice, NoxA1 de la NADPH oxydase. Le traitement des cellules HaCaT-MC1R par un inhibiteur du récepteur au facteur de croissance épidermique (EGFR) restaure l'habilité de ces cellules à induire un stress oxydatif après irradiation UVA. Ces résultats montrent que l'activité constitutive du récepteur MC1R dans des kératinocytes pourrait inhiber le stress oxydatif induit par les UVA via des mécanismes dépendants de l'AMPc et de l'EGFR.

La Llama es el Camélido doméstico más abundante de Argentina. La cría de Llamas constituye una actividad económica de gran importancia debido a que es una especie poliproductora de carne, fibra, cuero y transporte. Actualmente existe interés creciente por mejorar el rendimiento y calidad de estos productos. El estudio de genes candidatos permite vincular las variaciones de un carácter y la manera en que éste se manifiesta en el fenotipo del individuo. En ese contexto la hormona de crecimiento (GH), producto del gen GH1 y secretada por la glándula pituitaria, estimula el crecimiento de huesos y músculos. Por otra parte, es bien conocido el interés que existe en la producción de fibras por determinados colores con mayor valor comercial. La determinación del color de capa en mamíferos se debe a la interacción de los genes MC1R (receptor 1 de melanocortina) y ASIP (péptido de señalización Agouti). Ambos controlan el tipo y localización de pigmento eumelánico (negro-marrón oscuro o sepia) o feomelánico (rojoamarillento) producido. Esta Tesis tuvo por objetivo caracterizar y analizar la diversidad genética del gen GH1 y realizar la caracterización molecular de las variantes alélicas de MC1R y ASIP en Llamas con distintos fenotipos de colores de capas. Mediante PCR se amplificaron y luego secuenciaron los tres genes. El gen GH1 mostró un alto nivel de variabilidad encontrándose 15 SNPs, mayormente situados en región no codificante. Sin embargo se identificaron dos polimorfismos en el promotor y uno en la región 5´no traducible. Dado que los polimorfismos localizados en el promotor podrían afectar los niveles de expresión del gen, se concluye que los mismos pueden ser útiles en futuros estudios de asociación. Con respecto al gen MC1R se identificaron 13 SNPs en región codificante, 10 de los cuales fueron no sinónimos. La combinación de 3 de estos polimorfismos permitieron diferenciar Llamas con capas pigmentadas (A259/A376/T383) de las blancas no albinas (BNA) que carecían de pigmento (G259/G376/C383). En ASIP el hallazgo más importante fue una deleción de 57pb en el Exón 4 con posible pérdida de función. De esta manera, el alelo delecionado en homocigosis se observó en Llamas eumelánicas y el alelo sin delecionar en estado homocigota o heterocigota, se vió en Llamas feomelánicas. La identificación de los alelos de los genes MC1R y ASIP permitió proponer un mecanismo por el cual se genera la pigmentación feomelánica y eumelánica (TO) en las Llamas.

The melanocortin-1 receptor (MC1R) is a G-protein coupled receptor (GPCR) expressed on the surface of the melanocyte. MC1R activation after UV exposure results in the production of the dark eumelanin pigment and the tanning process in humans, providing protection from UV induced DNA damage. MC1R activation has also recently been linked to DNA repair. The MC1R gene is highly polymorphic in Caucasian populations with a number of MC1R variant alleles associated with red hair, fair skin, poor tanning and increased risk of melanoma and non-melanoma skin cancer. These MC1R variant receptors were thought to be loss of function, however the type of defect and the extent of the loss of function for individual variants was relatively unknown before the commencement of this PhD project. Many GPCR mutant proteins are intracellularly retained, resulting in a loss of signalling ability. To determine if this was the case for MC1R variant receptors, the localisation of the wild type and variant MC1R protein was investigated using immunofluorescence and radio-ligand binding on transfected melanocytic cells as well as primary melanocyte strains. For the first time, several MC1R variants including V60L, R151C, I155T, R160W and R163Q, were shown to have reduced cell surface expression compared to wild type MC1R. cAMP assays were used to determine the signalling ability of activated wild type and variant MC1R, importantly, variant receptors with reduced cell surface expression showed corresponding impairment in cAMP signalling. In contrast, the R142H and D294H variants, which have normal cell surface expression but significantly impaired cAMP signalling, are thought to have a defect in G-protein coupling. Some MC1R variants were found to have dominant negative activity on the wild type receptor in co-expression studies, this result may explain the MC1R heterozygote effect on human pigmentation phenotypes. This dominant negative effect resulted in either reduced wild type cell surface expression or reduced G-protein coupling and may be mediated by receptor dimerisation. In order to validate the in vitro studies, comparison of variant receptor characteristics with skin and hair colour data of individuals both homozygous and heterozygous for MC1R variant alleles was performed. This revealed parallels between variant MC1R cell surface expression, functional ability, dominant negative activity and the strength of the effects of variant alleles on human pigmentation. From the in vitro functional studies, it was clear that most variant receptors retained some signaling ability, although the relative abilities varied. An important unanswered question in the literature was whether the phenotype of carriers of the high penetrance MC1R variant alleles was actually representative of complete loss of function for MC1R. Due to the rarity of MC1R null alleles they had only previously been found in the heterozygous state, however we described the phenotype of one individual compound heterozygous for two frameshift mutations resulting in an individual unable to produce any functional MC1R protein. Phenotypic analysis indicated that red hair and fair skin is found in the absence of MC1R. Finally, preliminary studies using low temperature, chemical or pharmacological chaperones indicated that the cell surface expression of some MC1R variants could be rescued in cell transfection experiments. This resulted in a restoration of signaling ability after stimulation with agonist. These studies into the localization and function of MC1R variants have contributed to a greater understanding of the molecular mechanism underlying the association of MC1R with skin cancer risk phenotypes, and may lead to future drug based therapies that are able to rescue the function of MC1R variants that are intracellularly retained.