title: A novel homolog of protein tyrosine kinase Fyn identified in Lampetra japonica with roles in the immune response.
abstract: The non-receptor protein tyrosine kinase (nrPTK) Fyn, a member of the avian sarcoma virus transforming gene (Src) kinase family, plays a very significant role in cell growth, survival, apoptosis, tumor formation and immune response. In this study, a homolog of nrPTK Fyn was identified for the first time in the lamprey, Lampetra japonica and was named "Lja-Fyn". The cDNA fragment of lamprey lja-fyn contains a 1611-bp open reading frame, which encodes a protein of 537 amino acids. Multiple sequence alignment analysis showed that it shares four conserved domains (Src homology (SH) 4, SH3, SH2 and protein kinases catalytic domains) and a variable unique domain with vertebrates Fyn molecules. Though Lja-Fyn has high sequence similarity with typical Fyn and Yes molecules of jawed vertebrates, the identities among Lja-Fyn and typical Fyn molecules in unique domain are relatively higher than that among Lja-Fyn and typical Yes molecules. The result indicates that Lja-Fyn is a homolog of Fyn rather than Yes. The phylogenetic analysis showed that Fyn, Yes and Src molecules are grouped into three distinct phylogenetic clusters, and Lja-Fyn is grouped as a single branch in Fyn cluster. The real-time quantitative PCR assay revealed the wide distribution of the lja-fyn mRNA in lamprey immune related tissues. After stimulation with mixed antigens, the levels of lja-fyn mRNA were obviously up-regulated in the gill and lymphocyte-like cells, and the similar results were got by western blot analysis of Lja-Fyn protein expression. These results indicated that nrPTK Lja-Fyn was likely to be involved in immune response. Furthermore, our present findings also provide the necessary information for understanding the distinction between lamprey Lja-Fyn and other members of jawed vertebrates in Src family.
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Xueying
authors.initials: X
authors.lastname: Song
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Su
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Ranran
authors.initials: R
authors.lastname: Li
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Gou
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China. Electronic address: liuxin@lnnu.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Life Science, Liaoning Normal University, Dalian 116029, China; Lamprey Research Center, Liaoning Normal University, Dalian 116029, China. Electronic address: liqw@263.net.
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Li
mesh_terms: D000818:Animals; D007113:Immunity, Innate / Q000235:genetics*; D007798:Lampreys / Q000235:genetics* / Q000276:immunology; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics* / Q000276:immunology; D017386:Sequence Homology, Amino Acid
chemical_list: D051076:Proto-Oncogene Proteins c-fyn
keywords: Expression pattern; Immune response; Lampetra japonica; Phylogenetic relationship; Tyrosine protein kinase Fyn