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Abstract(s)
A proteína Gla da matriz (MGP), uma proteína da matriz extracelular segregada por
condrócitos (osso e cartilagem) e células do tecido muscular liso vascular, é considerada
uma inibidora fisiológica da mineralização. Estudos in viíro mostram que a expressão
genética da MGP é extensivamente regulada em mamíferos, mas não existem dados
disponíveis para outros vertebrados. Neste trabalho, estudámos a regulação da MGP de
Sparus aurata por vitaminas (C, K ou D), factores de crescimento (FGF, EGF ou
VEGF), cálcio, fosfato, ácido retinóico, insulina, P-estradiol ou dexametazona usando
uma linha celular derivada de vértebra de dourada (VSal3), recentemente desenvolvida
no nosso laboratório. A expressão do gene da MGP foi reprimida em células tratadas
com 5 pM de ácido retinóico ou 100 nM de dexametazona, induzida em células tratadas
com 2 nM de insulina, 10 nM de p-estradiol, 50 mg/ml de vitamina C, 10 nM de
vitamin D, 50 mg/ml de vitamin K ou 50 ng/ml de FGF, e sem alterações em células
tratadas com EGF, VEGF, cálcio ou fosfato. O efeito indutor da vitamina C na
expressão do gene foi ligeiramente aumentado na presença de cálcio ou fosfato e
fortemente aumentado quando ambos cálcio e fosfato estiveram presentes. Alguns
destes resultados estão em contradição com os obtidos em vertebrados superiores,
podendo ser explicados por diferentes mecanismos de regulação nos vertebrados
inferiores. Construções contendo fragmentos do promotor da MGP a montante do gene
repórter Luciferase estão a ser usados para validar estes resultados e identificar regiões regulatórias.
Matrix Gla protein (MGP), an extracellular matrix protein secreted by chondrocytes from bone and cartilage and vascular smooth muscle cells, is considered to be a physiological inhibitor of tissue mineralization. In viíro studies have demonstratcd that MGP gene expression is highly regulated in mammals, but no data is available for other vertebrates. In the present work, we have studied the regulation of Sparus aura/a MGP gene expression by vitamins (C, K or D), growth factors (FGF, EGF or VEGF), extracellular calcium, inorganic phosphate, retinoic acid, insulin, P-estradiol and dexamethasone using a Sparus aurata bone-derived cell line, VSal3, recently developed in our laboratory MGP gene expression was strongly down-regulated in cells treated with 5 mM of retinoic acid or 100 nM of dexamethazone, was slightly upregulated in cells treated with 2 nM of insulin or 10 nM of P-estradiol, was more strongly up-regulated in cells treated with 50 mg/ml of vitamin C, 10 nM of vitamin D, 50 mg/ml of vitamin K or 50 ng/ml of FGF, and unchanged in cells treated with IGF, EGF, VEGF, calcium or phosphate. The stimulatory effect of vitamin C on MGP gene expression was slightly increased in presence of calcium or phosphate and strongly increased when both calcium and phosphate were present. Some of these results are in contradiction with those obtained in higher vertebrates but could be explained by different regulatory mechanisms in lower vertebrates. Constructions containing MGP promoter fragments upstream of Luciferase repórter gene are currently being used to validate these results and identify regulatory regions
Matrix Gla protein (MGP), an extracellular matrix protein secreted by chondrocytes from bone and cartilage and vascular smooth muscle cells, is considered to be a physiological inhibitor of tissue mineralization. In viíro studies have demonstratcd that MGP gene expression is highly regulated in mammals, but no data is available for other vertebrates. In the present work, we have studied the regulation of Sparus aura/a MGP gene expression by vitamins (C, K or D), growth factors (FGF, EGF or VEGF), extracellular calcium, inorganic phosphate, retinoic acid, insulin, P-estradiol and dexamethasone using a Sparus aurata bone-derived cell line, VSal3, recently developed in our laboratory MGP gene expression was strongly down-regulated in cells treated with 5 mM of retinoic acid or 100 nM of dexamethazone, was slightly upregulated in cells treated with 2 nM of insulin or 10 nM of P-estradiol, was more strongly up-regulated in cells treated with 50 mg/ml of vitamin C, 10 nM of vitamin D, 50 mg/ml of vitamin K or 50 ng/ml of FGF, and unchanged in cells treated with IGF, EGF, VEGF, calcium or phosphate. The stimulatory effect of vitamin C on MGP gene expression was slightly increased in presence of calcium or phosphate and strongly increased when both calcium and phosphate were present. Some of these results are in contradiction with those obtained in higher vertebrates but could be explained by different regulatory mechanisms in lower vertebrates. Constructions containing MGP promoter fragments upstream of Luciferase repórter gene are currently being used to validate these results and identify regulatory regions
Description
Dissertação de mest. em Biotecnologia, Faculdade de Engenharia de Recursos Naturais, Univ. do Algarve, 2004
Keywords
Biotecnologia Proteínas Proteína Gla Condrócitos Sparus aurata