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1.
Biol. Res ; 44(1): 25-34, 2011. ilus
Artigo em Inglês | LILACS | ID: lil-591861

RESUMO

The Notch signaling pathway plays an important role in development and physiology. In Drosophila, Notch is activated by its Delta or Serrate ligands, depending in part on the sugar modifications present in its extracellular domain. O-fucosyltransferase-1 (OFUT1) performs the first glycosylation step in this process, O-fucosylating various EGF repeats at the Notch extracellular domain. Besides its O-fucosyltransferase activity, OFUT1 also behaves as a chaperone during Notch synthesis and is able to down regulate Notch by enhancing its endocytosis and degradation. We have reevaluated the roles that O-fucosylation and the synthesis of GDP-fucose play in the regulation of Notch protein stability. Using mutants and the UAS/Gal4 system, we modified in developing tissues the amount of GDP-mannose-deshydratase (GMD), the first enzyme in the synthesis of GDP-fucose. Our results show that GMD activity, and likely the levels of GDP-fucose and O-fucosylation, are essential to stabilize the Notch protein. Notch degradation observed under low GMD expression is absolutely dependent on OFUT1 and this is also observed in Notch Abruptex mutants, which have mutations in some potential O-fucosylated EGF domains. We propose that the GDP-fucose/OFUT1 balance determines the ability of OFUT1 to endocytose and degrade Notch in a manner that is independent of the residues affected by Abruptex mutations in Notch EGF domains.


Assuntos
Animais , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Fucosiltransferases/metabolismo , Guanosina Difosfato Fucose/metabolismo , Guanosina Difosfato Manose/metabolismo , Receptores Notch/metabolismo , Asas de Animais/metabolismo , Alelos , Proteínas de Drosophila/genética , Drosophila melanogaster/anatomia & histologia , Drosophila melanogaster/metabolismo , Endocitose/genética , Fucosiltransferases/genética , Guanosina Difosfato Fucose/genética , Guanosina Difosfato Manose/genética , Imuno-Histoquímica , Hibridização In Situ , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutação/genética , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptores Notch/genética , Transdução de Sinais , Asas de Animais/anatomia & histologia
2.
Rev. argent. transfus ; 36(4): 225-231, 2010. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-673556

RESUMO

El estado secretor de un individuo está determinado por el gen Secretor (FUT2), responsable de la presencia de antígenos ABH en las secreciones del organismo. El polimorfismo del gen FUT2 muestra una gran variabilidad dependiente del tipo de población. Alrededor del 20% de los individuos caucásicos son no­secretores y presentan la mutación G428A. El objetivo de este trabajo fue estudiar las variables alélicas del gen FUT2 en una población de Rosario. Se trabajó con muestras de sangre periférica de dadores voluntarios (n=1728). Se determinó el estado secretor en plasma y saliva y el fenotipo Lewis. El ADN genómico fue extraído por la técnica de salting-out modificada y fue analizado por ASA-PCR con cebadores específicos para el alelo G428A y para el alelo wild type del gen FUT2. Los resultados obtenidos mostraron que el 77% de los individuos investigados fueron secretores y presentaron el fenotipo Lewis Le(a-b+). El polimorfismo G428A estuvo presente en homocigosis en un 7.5%, valor menor al reportado en la bibliografía para la población caucásica. El análisis molecular del gen FUT2 confirmaría la diversidad genética de la población investigada y podría ser utilizada como un marcador poblacional.


The secretor status is determinate by the secretor gene (FUT2) responsible of the ABH antigens expression in human secretions. About 20% of Caucasian individuals are non-secretors. The aim of this study was to study the allelic varieties of the FUT2 gene by a PCR reaction. We worked with peripheral blood samples of volunteers (n= 1728). We determinated the secretor status in plasma and saliva. The genomic DNA was extracted by an enzymatic digestion method and was analyzed by ASA-PCR with specific primers for the G428A allele and for the wild type allele of the FUT2 gene. The results obtained by serologic and molecular methods showed that the 77% of the investigate individuals were secretors. The G428A polymorphism had present in a 7.5%. The allelic varieties of the other non-secretor individuals different to the G428A might to correspond to other mutations. The molecular analysis of the FUT2 gene confirms the genetic diversity of the investigated population.


Assuntos
Humanos , Alelos , Antígenos de Grupos Sanguíneos/genética , Antígenos de Grupos Sanguíneos/imunologia , Fucosiltransferases/genética , Variação Genética , Argentina , Técnicas Genéticas , Polimorfismo Genético , Testes Sorológicos/métodos , Sistema ABO de Grupos Sanguíneos/genética , Sistema ABO de Grupos Sanguíneos/imunologia
3.
Genet. mol. biol ; 27(3): 342-349, Sept. 2004. ilus, tab, graf
Artigo em Inglês | LILACS | ID: lil-366178

RESUMO

In the present study, the coding region of the H gene was sequenced and analyzed in fourteen genera of New World primates (Alouatta, Aotus, Ateles, Brachyteles, Cacajao, Callicebus, Callithrix, Cebus, Chiropotes, Lagothrix, Leontopithecus, Pithecia, Saguinus, and Saimiri), in order to investigate the evolution of the gene. The analyses revealed that this coding region contains 1,101 nucleotides, with the exception of Brachyteles, the callitrichines (Callithrix, Leontopithecus, and Saguinus) and one species of Callicebus (moloch), in which one codon was deleted. In the primates studied, the high GC content (63 percent), the nonrandom distribution of codons and the low evolution rate of the gene (0.513 substitutions/site/MA in the order Primates) suggest the action of a purifying type of selective pressure, confirmed by the Z-test. Our analyses did not identify mutations equivalent to those responsible for the H-deficient phenotypes found in humans, nor any other alteration that might explain the lack of expression of the gene in the erythrocytes of Neotropical monkeys. The phylogenetic trees obtained for the H gene and the distance matrix data suggest the occurrence of divergent evolution in the primates.


Assuntos
Evolução Molecular , Fucosiltransferases , Primatas
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