Three regulatory regions of the Aedes aegypti glutamine synthetase gene differentially regulate expression: identification of a crucial regulator in the first exon
Autor(es): Niu L L,Kiley L M,Dasgupta R,Kohler P,Christensen B M
Resumo: Aedes aegyptiglutamine synthetase (GS) is expressed constitutively at various developmental stages and its relative mRNA abundance increases in the midgut following blood feeding in support of the biosynthesis of chitin, a component of the peritrophic matrix. To understand the regulation of GS expression better, GS-luciferase reporter fusion genes were constructed and analysed in transiently transfected C6/36 cells. These studies have identified three GS regions: GS-A, -B and -C (C1, C2) that are required for efficient transcription. The crucial regulatory DNA sequence is located within 140 nucleotides of the GS-C region in the first exon. GS-B region between -209 and +4 contains a negative modulator that represses transcription of the GS-C promoter, but the 5'-GS-A region, between -476 and -282, can negate the transcription inhibition of GS-B and promote GS transcription of the GS-C promoter. Electrophoretic mobility shift assays showed that nuclear proteins for GS-A, GS-B and GS-C1 are present in the C6/36 cells, and therefore that GS-A, GS-B and GS-C1 indeed possess regulatory function. By contrast, nuclear proteins isolated from both cultured cells and midgut tissues bound to GS-C2, suggesting that GS-C2 plays an important role in GS transcription and that GS-C2 is regulated by several different and redundant transcription factors to achieve constitutive expression in a wide variety of tissues.
Palavras-Chave: Glutamine synthetase; Electrophoreticmobility shift assay (EMSA); Gene regulation; Aedesaegypti; Chitin biosynthesis
Imprenta: Insect Molecular Biology, v. 12, n. 6, p. 571-579, 2003
Identificador do objeto digital: 10.1046/j.1365-2583.2003.00442.x
Descritores: Aedes aegypti - Cell ; Aedes aegypti - DNA ; Aedes aegypti - Genome ; Aedes aegypti - Pathogenesis ; Aedes aegypti - Proteins
Data de publicação: 2003
