RESUMEN
ABSTRACT Gyrate atrophy is a rare metabolic autosomal recessive disorder caused by ornithine aminotransferase enzyme deficiency that leads to characteristic progressive, degenerative chorioretinal findings. Patients complain mostly of low vision, night blindness, and peripheral vision loss. Posterior subcapsular cataract, myopia, choroid neovascularization, and intraretinal cysts may be accompanying factors related to vision loss. We encountered a patient with vision loss secondary to posterior subcapsular cataract and intraretinal cysts. After treatment with topical brinzolamide and nepafenac (and without any diet mo dification and/or supplementation), we observed 143- and 117-mm macular thickness resolutions with 2 and 1 Snellen lines of visual gain in his right and left eyes, respectively. Also, we detected a novel homozygous mutation in the ornithine aminotransferase gene: c.1253T>C (p.Leu418Pro). Carbonic anhydrase inhibitors and/or non-steroid anti-inflammatory drugs can control macular edema in patients with gyrate atrophy-associated intraretinal cysts. The genetic variants may also be a determinant in the responsiveness to the therapy type.
RESUMO A atrofia girata é um distúrbio autossômico recessivo metabólico raro causado pela deficiência da enzima ornitina ami notransferase, que leva a achados degenerativos coriorretinianos progressivos característicos. Os pacientes queixam-se principalmente de baixa visão, cegueira noturna e perda de vi são periférica. A catarata subcapsular posterior, a miopia, a neovascularização da coróide e os cistos intrarretinianos podem ser fatores associados à perda da visão. Encontramos um paciente com perda de visão secundária à catarata subcapsular posterior e cistos intrarretinianos. Após o tratamento com brinzolamida tópica e nepafenaco (e sem modificação e/ou suplementação da dieta), observamos resoluções de espessura macular de 143 e 117 mm e com 2 e 1 linhas de Snellen de ganho visual nos olhos direito e esquerdo, respectivamente. Além disso, detectamos uma nova mutação homozigótica no gene da ornitina aminotransfera se: c.1253T>C (p.Leu418Pro). Inibidores da anidrase carbônica e/ou drogas anti-inflamatórias não esteróides podem controlar o edema macular em pacientes com cistos intrarretinianos associados à atrofia girata. As variantes genéticas também podem ser determinantes na responsividade ao tipo de terapia.
Asunto(s)
Humanos , Masculino , Adulto , Fenilacetatos/administración & dosificación , Inhibidores de Anhidrasa Carbónica/administración & dosificación , Atrofia Girata/genética , Antiinflamatorios no Esteroideos/administración & dosificación , Edema Macular/tratamiento farmacológico , Bencenoacetamidas/administración & dosificación , Ornitina-Oxo-Ácido Transaminasa/genética , Sulfonamidas/administración & dosificación , Tiazinas/administración & dosificación , Angiografía con Fluoresceína , Edema Macular/diagnóstico por imagen , Tomografía de Coherencia Óptica , Secuenciación de Nucleótidos de Alto Rendimiento , Administración Oftálmica , MutaciónRESUMEN
Gyrate atrophy is a rare metabolic autosomal recessive disorder caused by ornithine aminotransferase enzyme deficiency that leads to characteristic progressive, degenerative chorioretinal findings. Patients complain mostly of low vision, night blindness, and peripheral vision loss. Posterior subcapsular cataract, myopia, choroid neovascularization, and intraretinal cysts may be accompanying factors related to vision loss. We encountered a patient with vision loss secondary to posterior subcapsular cataract and intraretinal cysts. After treatment with topical brinzolamide and nepafenac (and without any diet mo dification and/or supplementation), we observed 143- and 117-mm macular thickness resolutions with 2 and 1 Snellen lines of visual gain in his right and left eyes, respectively. Also, we detected a novel homozygous mutation in the ornithine aminotransferase gene: c.1253T>C (p.Leu418Pro). Carbonic anhydrase inhibitors and/or non-steroid anti-inflammatory drugs can control macular edema in patients with gyrate atrophy-associated intraretinal cysts. The genetic variants may also be a determinant in the responsiveness to the therapy type.
Asunto(s)
Antiinflamatorios no Esteroideos/administración & dosificación , Bencenoacetamidas/administración & dosificación , Inhibidores de Anhidrasa Carbónica/administración & dosificación , Atrofia Girata/genética , Edema Macular/tratamiento farmacológico , Fenilacetatos/administración & dosificación , Sulfonamidas/administración & dosificación , Tiazinas/administración & dosificación , Administración Oftálmica , Adulto , Angiografía con Fluoresceína , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Edema Macular/diagnóstico por imagen , Masculino , Mutación , Ornitina-Oxo-Ácido Transaminasa/genética , Tomografía de Coherencia ÓpticaRESUMEN
The role of the δ-ornithine amino transferase (OAT) pathway in proline synthesis is still controversial and was assessed in leaves of cashew plants subjected to salinity. The activities of enzymes and the concentrations of metabolites involved in proline synthesis were examined in parallel with the capacity of exogenous ornithine and glutamate to induce proline accumulation. Proline accumulation was best correlated with OAT activity, which increased 4-fold and was paralleled by NADH oxidation coupled to the activities of OAT and Δ(1)-pyrroline-5-carboxylate reductase (P5CR), demonstrating the potential of proline synthesis via OAT/P5C. Overall, the activities of GS, GOGAT and aminating GDH remained practically unchanged under salinity. The activity of P5CR did not respond to NaCl whereas Δ(1)-pyrroline-5-carboxylate dehydrogenase was sharply repressed by salinity. We suggest that if the export of P5C from the mitochondria to the cytosol is possible, its subsequent conversion to proline by P5CR may be important. In a time-course experiment, proline accumulation was associated with disturbances in amino acid metabolism as indicated by large increases in the concentrations of ammonia, free amino acids, glutamine, arginine and ornithine. Conversely, glutamate concentrations increased moderately and only within the first 24h. Exogenous feeding of ornithine as a precursor was very effective in inducing proline accumulation in intact plants and leaf discs, in which proline concentrations were several times higher than glutamate-fed or salt-treated plants. Our data suggest that proline accumulation might be a consequence of salt-induced increase in N recycling, resulting in increased levels of ornithine and other metabolites involved with proline synthesis and OAT activity. Under these metabolic circumstances the OAT pathway might contribute significantly to proline accumulation in salt-stressed cashew leaves.
Asunto(s)
Anacardium/metabolismo , Nitrógeno/metabolismo , Ornitina-Oxo-Ácido Transaminasa/metabolismo , Ornitina/metabolismo , Prolina/metabolismo , Tolerancia a la Sal/fisiología , Estrés Fisiológico/fisiología , Pruebas de Enzimas , Glutamato Deshidrogenasa/metabolismo , Glutamato-Sintasa (NADH)/metabolismo , Glutamato-Amoníaco Ligasa/metabolismo , Glutamatos/administración & dosificación , Glutamatos/metabolismo , NAD/metabolismo , Ornitina/administración & dosificación , Hojas de la Planta/metabolismo , Prolina/biosíntesis , Pirrolina Carboxilato Reductasas/metabolismo , Salinidad , delta-1-Pirrolina-5-Carboxilato ReductasaRESUMEN
Many plants synthesize and accumulate proline in response to osmotic stress conditions. A central enzyme in the proline biosynthesis is the bifunctional enzyme Delta(1)-pyrroline-5-carboxylate synthase (P5CS) that includes two functional catalytic domains: the gamma-glutamyl kinase and the glutamic-gamma-semialdehyde dehydrogenase. This enzyme catalyzes the first two steps of the proline biosynthetic pathway and plays a central role in the regulation of this process in plants. To determine the evolutionary events that occurred in P5CS genes, partial sequences from four Neotropical trees were cloned and compared to those of other plant taxa. Molecular phylogenetic analysis indicated that P5CS duplication events have occurred several times following the emergence of flowering plants and at different frequencies throughout the evolution of monocots and dicots. Despite the high number of conserved residues in plant P5CS sequences, positive selection was observed at different regions of P5CS paralogous genes and also when dicots and monocots were contrasted.
Asunto(s)
Ornitina-Oxo-Ácido Transaminasa/genética , Ornitina-Oxo-Ácido Transaminasa/metabolismo , Plantas/enzimología , Plantas/genética , Prolina/biosíntesis , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , ADN de Plantas/genética , Evolución Molecular , Duplicación de Gen , Genes de Plantas , Datos de Secuencia Molecular , Presión Osmótica , Filogenia , Plantas/clasificación , Homología de Secuencia de Aminoácido , Árboles/enzimología , Árboles/genética , Clima TropicalRESUMEN
Estudamos a regulação de enzimas da via de metabolização da L-arginina (óxido nítrico sintase induzível, iNOS, ornitina descarboxilase, ODC, e ornitina aminotransferase, OAT) pelo hormônio de crescimento (GH) em células mesangiais e em córtex renal de camundongos bGH. Estes animais apresentam concentração sérica elevada de GH e desenvolvem glomerulosclerose (GS) progressiva. Há várias evidências da participação do GH no desenvolvimento de GS. Demonstrou-se também uma associação entre o acúmulo de matrix extracelular (MEC) nos glomérulos e a expressão aumentada de iNOS, OAT e ODC. Nós demonstramos, pela primeira vez, uma ligação entre o GH e a iNOS em células mesangiais, além de uma expressão aumentada desta enzima em córtex renal de camundongo bGH com GS severa...
Asunto(s)
Regulación Enzimológica de la Expresión Génica , Hormona del Crecimiento , Técnicas In Vitro , Óxido Nítrico Sintasa/genética , Nitritos , Ornitina Descarboxilasa , Ornitina-Oxo-Ácido Transaminasa , Medios de Cultivo , Ratones Transgénicos , Reacción en Cadena de la Polimerasa , EsclerosisRESUMEN
Proline prototrophy was restored to an Escherichia coli proBA proline auxotroph by ornithine and a mothbean (Vigna aconitifolia) cDNA expression library. This novel strategy, "trans-complementation," allowed isolation of a cDNA encoding ornithine delta-aminotransferase (delta-OAT). This enzyme transaminates ornithine to glutamic-gamma-semialdehyde (GSA), thereby bypassing the block in GSA synthesis from glutamate in the proBA mutant. The identity of the mothbean enzyme was confirmed by its high sequence homology to mammalian and yeast delta-OATs as well as to a family of bacterial and fungal omega-aminotransferases and an absence of significant homology to various alpha-aminotransferases. The V. aconitifolia OAT cDNA encodes a polypeptide of 48.1 kDa. The native enzyme expressed in E. coli appears to be a monomer with Km of 2 mM for ornithine and 0.75 mM for alpha-ketoglutarate. Levels of mRNA in V. aconitifolia for delta 1-pyrroline-5-carboxylate synthetase (P5CS) and delta-OAT, the two key enzymes for proline synthesis, were monitored under different physiological conditions. Salt stress and nitrogen starvation induced P5CS mRNA levels and depressed OAT mRNA levels. Conversely, OAT mRNA level was elevated in plants supplied with excess nitrogen while the P5CS mRNA level was reduced. These data suggest that the glutamate pathway is the primary route for proline synthesis in plants during conditions of osmotic stress and nitrogen limitation whereas the ornithine pathway assumes prominence under high nitrogen input.
Asunto(s)
Clonación Molecular , ADN/genética , Escherichia coli/enzimología , Ornitina-Oxo-Ácido Transaminasa/genética , Plantas/enzimología , Prolina/biosíntesis , 1-Pirrolina-5-Carboxilato Deshidrogenasa , Secuencia de Aminoácidos , Secuencia de Bases , Escherichia coli/genética , Escherichia coli/crecimiento & desarrollo , Fabaceae , Glutamatos/metabolismo , Ácido Glutámico , Cinética , Datos de Secuencia Molecular , Mutación , Nitrógeno/administración & dosificación , Nitrógeno/farmacología , Ornitina-Oxo-Ácido Transaminasa/química , Ornitina-Oxo-Ácido Transaminasa/metabolismo , Presión Osmótica , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH/genética , Plantas/efectos de los fármacos , Plantas/genética , Plantas Medicinales , ARN Mensajero/metabolismo , Homología de SecuenciaRESUMEN
The growth rate of several polyamine-deficient mutants of Escherichia coli was very low in minimal medium and increased markedly upon the addition of putrescine, spermidine, arginine, citrulline, or argininosuccinic acid. The endogenous content of polyamines was not significantly altered by the supplementation of polyamine-starved cultures with arginine or its precursors. In contrast, these compounds as well as putrescine or spermidine caused a 40-fold reduction in intracellular ornithine levels when added to polyamine-depleted bacteria. In vivo experiments with radioactive glutamic acid as a precursor and in vitro assays of the related enzymes showed that the decrease in ornithine levels was due to the inhibition of its biosynthesis rather than to an increase in its conversion to citrulline or delta 1-pyrroline-5-carboxylic acid and proline. High endogenous concentrations of ornithine were toxic for the E. coli strains tested. The described results indicate that the stimulatory effect of putrescine and spermidine on the growth of certain polyamine-starved bacteria may be partially due to the control of ornithine biosynthesis by polyamines.