Cloning And Expression Analysis Of Three Novel CC Chemokine Genes From Japanese Flounder Paralichthys Olivaceus

Chemokines are small cytokines secreted by various cell types. They not only functionin cell activation, differentiation and trafficking, but they also have influences on manybiological processes. According to the arrangement of the first two cysteine residues in theirsequence, the chemokines are divided into four subfamilies: CXC, CC, CX3C and C.Recently, a new subfamily of chemokines which named CX was described in zebrafish. CCchemokines constitutes the largest group of chemokines in mammals with28CCchemokines have been identified. However, in teleost fish CC chemokines, most effortshave been directed at cloning and phylogenetic analysis and only few studies have dealtwith their functions in the immune response.Three novel CC chemokine genes Paol-SCYA105,106and107in Japanese flounder(Paralichthys olivaceus) were cloned and characterized. Paol-SCYA105, Paol-SCYA106and Paol-SCYA107they have between59and67%amino acid sequence identities withtheir closest matches in the databases. Amino acid sequences alignment of three novel CCchemokines with other CC chemokines shows that four cysteine residues are conserved. Aphylogenetic tree showed Paol-SCYA105, Paol-SCYA106and Paol-SCYA107aregenetically closest to CCL17/22, CCL19and CCL27/28clade, respectively. The genestructure of Paol-SCYA105and Paol-SCYA107consist of3exons and2introns.Paol-SCYA106consists of4exons and3introns. Paol-SCYA105transcripts wereexpressed mainly in gill, kidney and spleen, weakly in brain and skin but not in the liver ormuscle. Paol-SCYA106was expressed in all tissues examined. Paol-SCYA107wasexpressed in the spleen, kidney and gill. In response to VHSV, Paol-SCYA105expressionwas significantly increased at3day post infection (dpi). Paol-SCYA106expression wasup-regulated at3and6dpi. Paol-SCYA107expression peaked at6dpi. In response toinfection by E. tarda, three novel CC chemokines only Paol-SCYA106was up-regulated.In response to infection by S. iniae, Paol-SCYA106expression peaked at1dpi. In this study, I reported three novel CC chemokines Paol-SCYA105, Paol-SCYA106and Paol-SCYA107in Japanese flounder. Sequencing alignment and genomic structureanalysis suggest that the three CC chemokine represent novel members of the CCchemokine family in Japanese flounder. The expressions of two of the chemokine geneswere tissue-specific. These chemokines have a role in the immune response against viraland bacterial infection, especially VHSV infection.