Transcriptional regulation of gene expression in eukaryotes has evolved over millions of years. The regulatory pathways of nuclear receptors represent an evolutionarily ancient, but conserved mechanism with associated accessory proteins, many of them forming a functional nexus known as the Mediator complex involved in transcription. Despite the versatility of the pathway, e.g. through the adoption of new regulatory functions in phylogenetically more recent Metazoa, we hypothesise that the intrinsic potential of the NR-Mediator axis to directly translate a stimulus to a biological response is conserved across species, and additional regulation could also be achieved through secondary functions of its essential members. To support the hypothesis, we assessed the ligand-binding capability of retinoic X receptor in Trichoplax adhaerens and provided evidence to support the concept that this capability was already present at the base of metazoan evolution. With regards to the potential secondary functions, we took inspiration from previous research and identified the Mediator subunit 28 (MED28) as the only known member having documented nuclear and cytoplasmic dual roles, and thus possessing the potential to transmit signals from the cellular structural states to the nucleus. Due to the lack of...

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A obesidade é causada pelo desequilíbrio entre a ingestão alimentar e o gasto energético corporal, com o armazenamento de energia na forma de gordura, no tecido adiposo. A obesidade causa alterações metabólicas, como resistência à insulina e dislipidemia, além de aumento de adipocinas e citocinas pró-inflamatórias. Este trabalho investigou a influência de polimorfismos nos genes da perilipina 1 (PLINl), visfatina (NAMPT) , resistina (RETN) e grelina (GHRL) na adiposidade e no perfil metabólico e inflamatório, antes e após um programa de orientação nutricional. Foram selecionados indivíduos obesos (OB, n=214), sobrepeso (SOB, n=71) e não obesos (NOB, n=69), com idade de 30 a 70 anos. Foram obtidos dados clínicos, antropométricos e de composição corporal. O recordatório de 24h foi aplicado a 87 indivíduos obesos para avaliação de consumo alimentar, antes e após o programa de orientação nutricional. Foi obtido sangue para extração de DNA e para analisar parâmetros laboratoriais (perfil lipídico e glicêmico, marcadores inflamatórios e adipocinas). Polimorfismos dos genes PLINl, NAMPT, RETN e GHRL foram analisados por PCR em tempo real. O grupo OB teve perfil antropométrico alterado e risco aumentado de hipertensão, diabetes tipo 2 e dislipidemia em comparação com os grupos SOB e NOB (p<0,05). As concentrações de glicose, colesterol total, LDL colesterol, VLDL colesterol, triglicérides, apolipoproteína B (ApoB), interleucina 1&#946; (IL-l &#946;) e fator de necrose tumoral alfa (TNF&#945;) foram maiores e as concentrações de HDL colesterol e apolipoproteina AI (apoAI) foram menores, no grupo OB que nos outros grupos (p<0,05). As frequências dos polimorfismos genéticos do grupo total foram similares as de outras populações. Os polimorfismos NAMPT rs1319501 C>T e rs10763861 C>T foram associados com obesidade (p<0,05). Os polimorfismos genéticos não influenciaram o perfil antropométrico do grupo total (p>0,05), mas no grupo de obesos, o polimorfismo GHRL rs4684677 T>A foi relacionado com maior porcentagem de gordura corporal (p=0,043). Após a orientação nutricional, observou-se diminuição da ingestão de calorias e do consumo de carboidratos, gorduras totais, sódio, magnésio e betacaroteno (p<0,05). Os polimorfismos genéticos não influenciaram o perfil antropométrico e o consumo alimentar de obesos, após a orientação nutricional. Em conclusão, polimorfismos dos genes NAMPT e GHRL contribuem para a adiposidade, mas não influenciam o comportamento alimentar e o perfil antropométrico, após orientação nutricional. / Obesity is caused by the imbalance between food intake and body energy expenditure, with the storage of energy in the form of fat, in adipose tissue. Obesity causes metabolic changes, such as insulin resistance and dyslipidemia, and an increase in adipokines and pro-inflammatory cytokines. This work investigated the influence of polymorphisms in the perilipine 1 (PLINI) , visfatin (NAMPT) , resistin (RETN) and ghrelin (GHRL) genes on adiposity and metabolic and inflammatory profile, before and after a nutritional orientation programo Obese (OB, n=214), overweight (SOB, n=71) and nonobese subjects (NOB, n=69), aged 30 to 70 years, were selected. ClinicaI, anthropometric and body composition data were obtained. The 24-hour dietary recall was applied to 87 obese subjects to eva1uate food intake before and after the nutritiona1 orientation programo Blood was obtained for DNA extraction and to analyze 1aboratory parameters (lipid and glycemic profile, inflammatory markers and adipokines). Po1ymorphisms of the PLINI, NAMPT, RETN and GHRL genes were analyzed by real-time PCR. The OB group had altered anthropometric profile and increased risk for hypertension, type 2 diabetes and dyslipidemia in comparison with SOB and NOB groups (p <0.05). Concentrations of glucose, total cholesterol, LDL cholesterol, VLDL cholesterol, triglycerides, apolipoprotein B (ApoB), interleukin 1&#946; (IL-1&#946;) and tumor necrosis factor alpha (TNF&#945;) were higher and the concentrations ofHDL cholesterol and apolipoprotein AI (apoAI) were lower in the OB than in the other groups (p <0.05). The frequencies of the genetic polymorphisms of the total group were similar to those of other populations. NAMPT rs1319501 C> T and rs10763861 C> T polymorphisms were associated with obesity (p <0.05). Genetic polymorphisms did not influence the anthropometric profile ofthe total group (p> 0.05), but in the obese group, the GHRL rs4684677 T> A polymorphism was related to a higher body fat percentage (p = 0.043). After nutritional orientation, a decrease in calorie intake and in the consumption of carbohydrates, total fats, sodium, magnesium and beta-carotene CP <0.05) were observed. Genetic polymorphisms did not influence the anthropometric profile and the dietary intake of obese individuaIs after nutritional orientation. In conclusion, NAMPT and GHRL gene polymorphisms contribute to adiposity but do not influence dietary behavior and anthropometric profile after nutritional orientation.

A obesidade é causada pelo desequilíbrio entre a ingestão alimentar e o gasto energético corporal, com o armazenamento de energia na forma de gordura, no tecido adiposo. A obesidade causa alterações metabólicas, como resistência à insulina e dislipidemia, além de aumento de adipocinas e citocinas pró-inflamatórias. Este trabalho investigou a influência de polimorfismos nos genes da perilipina 1 (PLINl), visfatina (NAMPT) , resistina (RETN) e grelina (GHRL) na adiposidade e no perfil metabólico e inflamatório, antes e após um programa de orientação nutricional. Foram selecionados indivíduos obesos (OB, n=214), sobrepeso (SOB, n=71) e não obesos (NOB, n=69), com idade de 30 a 70 anos. Foram obtidos dados clínicos, antropométricos e de composição corporal. O recordatório de 24h foi aplicado a 87 indivíduos obesos para avaliação de consumo alimentar, antes e após o programa de orientação nutricional. Foi obtido sangue para extração de DNA e para analisar parâmetros laboratoriais (perfil lipídico e glicêmico, marcadores inflamatórios e adipocinas). Polimorfismos dos genes PLINl, NAMPT, RETN e GHRL foram analisados por PCR em tempo real. O grupo OB teve perfil antropométrico alterado e risco aumentado de hipertensão, diabetes tipo 2 e dislipidemia em comparação com os grupos SOB e NOB (p<0,05). As concentrações de glicose, colesterol total, LDL colesterol, VLDL colesterol, triglicérides, apolipoproteína B (ApoB), interleucina 1&#946; (IL-l &#946;) e fator de necrose tumoral alfa (TNF&#945;) foram maiores e as concentrações de HDL colesterol e apolipoproteina AI (apoAI) foram menores, no grupo OB que nos outros grupos (p<0,05). As frequências dos polimorfismos genéticos do grupo total foram similares as de outras populações. Os polimorfismos NAMPT rs1319501 C>T e rs10763861 C>T foram associados com obesidade (p<0,05). Os polimorfismos genéticos não influenciaram o perfil antropométrico do grupo total (p>0,05), mas no grupo de obesos, o polimorfismo GHRL rs4684677 T>A foi relacionado com maior porcentagem de gordura corporal (p=0,043). Após a orientação nutricional, observou-se diminuição da ingestão de calorias e do consumo de carboidratos, gorduras totais, sódio, magnésio e betacaroteno (p<0,05). Os polimorfismos genéticos não influenciaram o perfil antropométrico e o consumo alimentar de obesos, após a orientação nutricional. Em conclusão, polimorfismos dos genes NAMPT e GHRL contribuem para a adiposidade, mas não influenciam o comportamento alimentar e o perfil antropométrico, após orientação nutricional. / Obesity is caused by the imbalance between food intake and body energy expenditure, with the storage of energy in the form of fat, in adipose tissue. Obesity causes metabolic changes, such as insulin resistance and dyslipidemia, and an increase in adipokines and pro-inflammatory cytokines. This work investigated the influence of polymorphisms in the perilipine 1 (PLINI) , visfatin (NAMPT) , resistin (RETN) and ghrelin (GHRL) genes on adiposity and metabolic and inflammatory profile, before and after a nutritional orientation programo Obese (OB, n=214), overweight (SOB, n=71) and nonobese subjects (NOB, n=69), aged 30 to 70 years, were selected. ClinicaI, anthropometric and body composition data were obtained. The 24-hour dietary recall was applied to 87 obese subjects to eva1uate food intake before and after the nutritiona1 orientation programo Blood was obtained for DNA extraction and to analyze 1aboratory parameters (lipid and glycemic profile, inflammatory markers and adipokines). Po1ymorphisms of the PLINI, NAMPT, RETN and GHRL genes were analyzed by real-time PCR. The OB group had altered anthropometric profile and increased risk for hypertension, type 2 diabetes and dyslipidemia in comparison with SOB and NOB groups (p <0.05). Concentrations of glucose, total cholesterol, LDL cholesterol, VLDL cholesterol, triglycerides, apolipoprotein B (ApoB), interleukin 1&#946; (IL-1&#946;) and tumor necrosis factor alpha (TNF&#945;) were higher and the concentrations ofHDL cholesterol and apolipoprotein AI (apoAI) were lower in the OB than in the other groups (p <0.05). The frequencies of the genetic polymorphisms of the total group were similar to those of other populations. NAMPT rs1319501 C> T and rs10763861 C> T polymorphisms were associated with obesity (p <0.05). Genetic polymorphisms did not influence the anthropometric profile ofthe total group (p> 0.05), but in the obese group, the GHRL rs4684677 T> A polymorphism was related to a higher body fat percentage (p = 0.043). After nutritional orientation, a decrease in calorie intake and in the consumption of carbohydrates, total fats, sodium, magnesium and beta-carotene CP <0.05) were observed. Genetic polymorphisms did not influence the anthropometric profile and the dietary intake of obese individuaIs after nutritional orientation. In conclusion, NAMPT and GHRL gene polymorphisms contribute to adiposity but do not influence dietary behavior and anthropometric profile after nutritional orientation.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal