Involvement of Rel factors in the expression of antimicrobial peptide genes in amphibia

Genes coding for antimicrobial peptides in amphibia reveal a remarkably hig h number of structural motifs for response elements, previously identified in the genes of insect antimicrobial peptides and in those of the mammalian acute phase response. This study focuses on the functional analysis of the bombinin gene promoter in a Drosophila blood cell line, and the identifica tion of kappaB-binding factors in skin secretions of the frog Bombina orien talis. Transfection experiments demonstrated that the bombinin gene promote r was activated in a lipopolysaccharide-dependent manner, and that insect R el factors target specific sequences in the amphibian gene promoter. After bathing frogs in bacteria, their skin secretions contained kappaB-specific binding complexes, indicating that Rel factors are crucial components in th e response against gram-negative bacteria in this species. These results su ggest that a common ancestral control mechanism governs the expression of t he first line host-defence from insects to vertebrates.