Immunity related genes in dipterans share common enrichment of AT-rich motifs in their 5' regulatory regions that are potentially involved in nucleosome formation.
BACKGROUND
Understanding the transcriptional regulation mechanisms in response to environmental challenges is of fundamental importance in biology. Transcription factors associated to response elements and the chromatin structure had proven to play important roles in gene expression regulation. We have analyzed promoter regions of dipteran genes induced in response to immune challenge, in search for particular sequence patterns involved in their transcriptional regulation.


RESULTS
5' upstream regions of D. melanogaster and A. gambiae immunity-induced genes and their corresponding orthologous genes in 11 non-melanogaster drosophilid species and Ae. aegypti share enrichment in AT-rich short motifs. AT-rich motifs are associated with nucleosome formation as predicted by two different algorithms. In A. gambiae and D. melanogaster, many immunity genes 5' upstream sequences also showed NFkappaB response elements, located within 500 bp from the transcription start site. In A. gambiae, the frequency of ATAA motif near the NFkappaB response elements was increased, suggesting a functional link between nucleosome formation/remodelling and NFkappaB regulation of transcription.


CONCLUSIONS
AT-rich motif enrichment in 5' upstream sequences in A. gambiae, Ae. aegypti and the Drosophila genus immunity genes suggests a particular pattern of nucleosome formation/chromatin organization. The co-occurrence of such motifs with the NFkappaB response elements suggests that these sequence signatures may be functionally involved in transcriptional activation during dipteran immune response. AT-rich motif enrichment in regulatory regions in this group of co-regulated genes could represent an evolutionary constrained signature in dipterans and perhaps other distantly species.
Hernandez-Romano
Jesus
J
Centro de Investigación sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av, Universidad 655, Col Sta Maria Ahuacatitlan, CP 62508, Cuernavaca, Morelos, México. jesushromano@hotmail.com
Carlos-Rivera
Francisco J
FJ
Salgado
Heladia
H
Lamadrid-Figueroa
Hector
H
Valverde-Garduño
Veronica
V
Rodriguez
Mario H
MH
Martinez-Barnetche
Jesus
J
D024506:5' Flanking Region / Q000235:genetics; D020856:AT Rich Sequence; D000330:Aedes / Q000235:genetics* / Q000276:immunology; D000818:Animals; D000852:Anopheles / Q000235:genetics* / Q000276:immunology; D030561:Databases, Nucleic Acid; D004331:Drosophila melanogaster / Q000235:genetics* / Q000276:immunology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D017344:Genes, Insect; D007109:Immunity / Q000235:genetics*; D016328:NF-kappa B / Q000235:genetics; D009707:Nucleosomes / Q000235:genetics* / Q000276:immunology; D020411:Oligonucleotide Array Sequence Analysis; D020218:Response Elements / Q000235:genetics; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D016328:NF-kappa B; D009707:Nucleosomes