The Relationship Between The Evolutional Information Of Interleukin-12(il12) Gene And The Evolution Of Species

Interleukin-12(IL-12)is one member of the IL-12 family cytokines.As one of the multifunctional cytokines,it plays an important role in both innate and acquired immunity in vertebrate.Il-12,a heterodimer,is composed of a p35 and a p40 subunit,playing important role in microbial infection,autoimmune disease and cancer.The adaptive immune system arose in lower fish.Moreover,fish-special whole genomice duplication(WGD),3 round(3R),leads to the presence of multiple copies of il12p35 and il12p40 in fish.However,the evolutionary status of il12(il12p35 and il12p40)genes are unclear in all species,which brings obstacles for the further study on the evolutionary information and functional mechanism of IL-12.Therefore,it is vital to explore the evolution of il12 genes in vertebrates,especially in fish.In this study,nearly 20 species of vertebrate which lie in the evolutionary nodes were selected;the gene location and structure of il12p35 and il12p40 from their genome databases were analysed;phylogenetic trees according to protein sequence of IL-12p35 and IL-12p40 through the principles and methods of bioinformatics were constructed to find the universality and particularity of il12 gene profiles in the evolutionary process;the evolutionary status of il12 gene in different vertebrates were determined;the origin of il12p35 and il12p40 genes was hypothesised.In the time axis of 1R,2R,3R and 4R genome replication,the evolution models of il12p35 and il12p40 genes were proposed for the first time.In addition,six heteroisomers of IL-12 formed by different subunits of grass carp p35 and p40 were analysed via constructing three-dimensional structural models predict the binding affinity ability of p35 and p40 subunits,so that a theoretical method for further functional studies of other heterodimers in fish were supplied.This study not only explored the evolution of il12p35 and il12p40 in different species,but also identified genetic information of il12 in the genomes of selected species,which provided further elucidation of the functional status of il12 in immunology,as well as methods for the study of the evolutionary information and functional evolution of genes.