Gene Expression Divergence and Evolutionary Analysis of the Drosomycin Gene Family inDrosophila melanogaster

[摘要] Drosomycin(Drs) encoding an inducible 44-residue antifungal peptide is clusteredwith six additional genes,Dro1, Dro2, Dro3, Dro4, Dro5,andDro6, forming amultigene family on the 3L chromosome arm inDrosophila melanogaster. To getfurther insight into the regulation of each member of the drosomycin gene family,here we investigated gene expression patterns of this family by either microbe-freeinjury or microbial challenges using real time RT-PCR. The results indicated thatamong the sevendrosomycingenes,Drs, Dro2, Dro3, Dro4,andDro5showedconstitutive expressions. Three out of five,Dro2, Dro3,andDro5, were able to beupregulated by simple injury. Interestingly,Drsis an only gene strongly upregulatedwhenDrosophilawas infected with microbes. In contrast to these five genes,Dro1andDro6were not transcribed at all in either noninfected or infected flies. Furthermore, by5′rapid amplification of cDNA ends, two transcription start siteswere identified inDrsandDro2, and one inDro3, Dro4,andDro5. In addition, NF-κBbinding sites were found in promoter regions ofDrs, Dro2, Dro3,andDro5, indicatingthe importance of NF-κB binding sites for the inducibility ofdrosomycingenes. Basedon the analyses of flanking sequences of each gene inD. melanogasterandphylogenetic relationship ofdrosomycinsinD. melanogasterspecies-group, weconcluded that gene duplications were involved in the formation of the drosomycingene family. The possible evolutionary fates ofdrosomycingenes were discussedaccording to the combining analysis of gene expression pattern, gene structure, andfunctional divergence of these genes.

[学科分类] 基础医学