D-dopachrome tautomerase from Japanese sea bass(Lateolabrax japonicus) is a chemokine-like cytokine and functional homolog of macrophage migration inhibitory factor  

作　　者：Feng Xu Ming-Yun Li Jiong Chen 

机构地区：[1]State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products,Ningbo University,Ningbo,Zhejiang 315211,China [2]Laboratory of Biochemistry and Molecular Biology,School of Marine Sciences,Ningbo University,Ningbo,Zhejiang 315832,China [3]Key Laboratory of Applied Marine Biotechnology of Ministry of Education,Ningbo University,Ningbo,Zhejiang 315832,China

出　　处：《Zoological Research》2020年第1期39-50,共12页动物学研究（英文）

基　　金：supported by the National Natural Science Foundation of China(31772876);Zhejiang Provincial Natural Science Foundation of China(LZ18C190001);Scientific Innovation Team Project of Ningbo(2015C110018);K.C.Wong Magna Fund in Ningbo University

摘　　要：D-dopachrome tautomerase(DDT),a member of the macrophage migration inhibitory factor(MIF)protein superfamily,is a newly described cytokine with chemokine-like characteristics.However,research on fish DDT remains limited.In this study,we identified a DDT homolog(LjDDT)from the Japanese sea bass,Lateolabrax japonicus.Sequence analysis showed that LjDDT had typical sequence features of known DDT and MIF homologs and was most closely related to DDT of rock bream(Oplegnathus fasciatus).LjDDT transcripts were detected in all tested tissues of healthy Japanese sea bass,with the highest expression found in the liver.Upon infection with Vibrio harveyi,LjDDT transcripts were significantly down-regulated in the three tested tissues,including the liver,spleen,and head kidney.Recombinant LjDDT(rLjDDT)and the corresponding antibody(anti-rLjDDT)were subsequently prepared.The administration of 100μg/g anti-rLjDDT had a statistically significant protective effect on the survival of V.harveyi-infected fish.Moreover,rLjDDT was able to induce the migration of monocytes/macrophages(MO/MФ)and lymphocytes both in vitro and in vivo,but without significant influence on the migration of neutrophils.rLjDDT exhibited chemotactic activity for lipopolysaccharide(LPS)-stimulated M1-type MO/MΦin vitro,but not for cAMP-stimulated M2-type MO/MΦ.Furthermore,the knockdown of LjCD74,but not LjCXCR4,significantly down-regulated the rLjDDT-enhanced migration of MO/MΦand relieved the rLjMIF-inhibited migration of MO/MΦ.These results indicate that LjCD74 may be the major chemotactic receptor of LjDDT and LjMIF in Japanese sea bass MO/MΦ.Combined rLjDDT+rLjMIF treatment had no significant effect on the migration of MsiRNA,LjCD74si-,or LjCXCR4sitreated MO/MΦcompared to the control group,suggesting that the roles of LjDDT and LjMIF may be antagonistic.In conclusion,our study demonstrates for the first time that DDT may play a role in the immune responses of fish against bacterial infection through chemotactic recruitment of MO/MΦvia mediation of CD-dopachrome tautomerase(DDT), a member of the macrophage migration inhibitory factor(MIF) protein superfamily, is a newly described cytokine with chemokine-like characteristics. However, research on fish DDT remains limited. In this study, we identified a DDT homolog(Lj DDT) from the Japanese sea bass, Lateolabrax japonicus.Sequence analysis showed that Lj DDT had typical sequence features of known DDT and MIF homologs and was most closely related to DDT of rock bream(Oplegnathus fasciatus). Lj DDT transcripts were detected in all tested tissues of healthy Japanese sea bass, with the highest expression found in the liver. Upon infection with Vibrio harveyi, Lj DDT transcripts were significantly down-regulated in the three tested tissues, including the liver, spleen, and head kidney. Recombinant Lj DDT(r Lj DDT) and the corresponding antibody(anti-r Lj DDT) were subsequently prepared. The administration of 100μg/g anti-r Lj DDT had a statistically significant protective effect on the survival of V. harveyi-infected fish. Moreover, r Lj DDT was able to induce the migration of monocytes/macrophages(MO/MФ) and lymphocytes both in vitro and in vivo, but without significant influence on the migration of neutrophils.r Lj DDT exhibited chemotactic activity for lipopolysaccharide(LPS)-stimulated M1-type MO/MΦ in vitro, but not for c AMP-stimulated M2-type MO/MΦ. Furthermore, the knockdown of Lj CD74, but not Lj CXCR4, significantly down-regulated the r Lj DDT-enhanced migration of MO/MΦ and relieved the r Lj MIF-inhibited migration of MO/MΦ. These results indicate that Lj CD74 may be the major chemotactic receptor of Lj DDT and Lj MIF in Japanese sea bass MO/MΦ. Combined r Lj DDT+r Lj MIF treatment had no significant effect on the migration of Msi RNA, Lj CD74 si-, or Lj CXCR4-sitreated MO/MΦ compared to the control group,suggesting that the roles of Lj DDT and Lj MIF may be antagonistic. In conclusion, our study demonstrates for the first time that DDT may play a role in the immune responses of fish against bact

关 键 词：Cell migration D-dopachrome tautomerase Japanese sea bass Macrophage migration inhibitory factor MONOCYTE/MACROPHAGE 

分 类 号：Q952[生物学—动物学]