Identification and characterization of mkk genes and their expression profiles in rainbow trout (Oncorhynchus mykiss) symptomatically or asymptomatically infected with Vibrio anguillarum

• Published in: Fish & shellfish immunology 2022-02, Vol.121, p.1-11
• Main Authors: Yang, Xiao-Dong, Hou, Zhi-Shuai, Liu, Meng-Qun, Zeng, Chu, Zhao, Hong-Kui, Xin, Yuan-Ru, Xiang, Kai-Wen, Yang, Qian, Wen, Hai-Shen, Li, Ji-Fang
• Format: Article
• Language: English
• Subjects: Animals; Fish Proteins - genetics; Fish Proteins - metabolism; Immunity; MAPK signaling; Mitogen-Activated Protein Kinase Kinases - genetics; Mitogen-Activated Protein Kinase Kinases - metabolism; mkk; Oncorhynchus mykiss - genetics; Oncorhynchus mykiss - metabolism; Rainbow trout; Vibrio; Vibrio anguillarum; Vibrio Infections - veterinary
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2021.12.049

Mitogen-activated protein kinase kinases (MKKs) are intermediate kinases of mitogen-activated protein kinases (MAPKs) signaling pathways. MKKs are activated by mitogen-activated protein kinase kinase kinase (MKKK) and then the activated MKKs trigger the activation of downstream MAPKs. MAPK signaling pathways play an important role in regulating immune functions including apoptosis and inflammation. However, studies on identification and characterization of mkk repertoire in rainbow trout (Oncorhynchus mykiss) are still limited. Trout experienced 4 rounds (4R) of whole genome duplication (WGD), thus exhibiting increased paralogs of mkks with potentially functional diversity. In this study, we identified 17 mkk genes in trout and the following bacterial challenge (Vibrio anguillarum) studies showed functional diversity of different mkk subtypes. Vibrio anguillarum infection resulted in significantly up-regulated mkk2 subtypes in spleen and liver, and mkk4b3 in spleen, suggesting immunomodulation was regulated by activation of ERK, p38 and JNK pathways. Compared to other mkk subtypes, mkk6s were down-regulated in symptomatic group, rather than asymptomatic group. The organisms present negative feedback on MAPK activation, thus reducing extra damage to cells. We observed down-regulated mkk6s with up-regulated genes (dusp1 &dusp2) involved in negative feedback of MAPK activation. Based on these results, we might propose the distinct expression patterns of genes associated with MAPK pathways resulted in different phenotypes and symptoms of trout in response to bacterial challenge. •Due to 4 rounds of whole genome duplication, 17 mkks were identified in trout.•Symptomatic and asymptomatic group exhibited distinct expression patterns of mkks.•Up-regulated mkks might mediate inflammation and apoptosis in trout.•Negative feedback system may be the reason to down-regulated mkks.•Up-regulated dusps might be involved in negative feedback of MAPK activation.