Molecular characterization and expression analysis of claudin-4-like in rainbow trout involved in Flavobacterium psychrophilum infection

Furong Deng; Di Wang; Fuguang Chen; Tongyan Lu; Shaowu Li

doi:10.1016/j.fsi.2022.09.016

Molecular characterization and expression analysis of claudin-4-like in rainbow trout involved in Flavobacterium psychrophilum infection

Fish Shellfish Immunol. 2022 Nov:130:244-251. doi: 10.1016/j.fsi.2022.09.016. Epub 2022 Sep 16.

Authors

Furong Deng¹, Di Wang², Fuguang Chen², Tongyan Lu², Shaowu Li³

Affiliations

¹ College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China; Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 150070, China.
² Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 150070, China.
³ Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 150070, China. Electronic address: lishaowu@hrfri.ac.cn.

PMID: 36122640
DOI: 10.1016/j.fsi.2022.09.016

Abstract

The claudin family of proteins are pivotal components of tight junction (TJ) participating in the epithelial barrier function in fish. Our previous studies indicated that one of the claudins, claudin-4-like (OmCLDN4L) was differentially expressed in rainbow trout (Oncorhynchus mykiss) spleen post infection of Flavobacterium psychrophilum, which is the causative pathogen of bacterial coldwater disease (BCWD). However, little is known about the function of OmCLDN4L in rainbow trout against bacterial infection. In the present study, the OmCLDN4L was identified and functionally characterized from rainbow trout. The OmCLDN4L has an open reading frame (ORF) of 668 bp, encoding a 22.86 kDa four-transmembrane protein with function of bicellular tight junction and apical tight junction. OmCLDN4L has the highest similarity with CLDN28a, CLDN28b and CLDN30 in amino acid sequence. Phylogenetic analysis showed that all of CLDN4 and CLDN4-like from fish clustered together but diverged from their counterparts in mammals, with main differences lying in their N-terminus. RT-qPCR results indicated that OmCLDN4L was constitutively expressed in all tissues investigated under healthy conditions, primarily in mucus, liver, skin and intestine. The expression of OmCLDN4L in rainbow trout intestine was slightly down-regulated at day 1 while up-regulated at day 3 and day 7 post F. psychrophilum infection, with the similar profiling of CLDN30 and CLDN10e. The expression level of inflammatory cytokines TNF-α, IL4/13A, IL-6 and pattern recognition receptor TLR-2 showed the same trend with OmCLDN4L in the intestine at day 3 and day 7 post F. psychrophilum infection. Collectively, these findings demonstrate that OmCLDN4L participates in the immune response to bacterial infection, offering new insights into the molecular mechanism of intestinal barrier in rainbow trout against F. psychrophilum infection.

Keywords: Claudin-4-like (OmCLDN4L); Flavobacterium psychrophilum; Intestinal barrier; Oncorhynchus mykiss; Tight junction (TJ).

MeSH terms

Animals
Claudin-4
Cytokines
Fish Diseases*
Flavobacteriaceae Infections*
Flavobacterium / physiology
Interleukin-4
Interleukin-6
Oncorhynchus mykiss*
Phylogeny
Toll-Like Receptor 2
Tumor Necrosis Factor-alpha

Substances

Claudin-4
Cytokines
Interleukin-6
Toll-Like Receptor 2
Tumor Necrosis Factor-alpha
Interleukin-4

Supplementary concepts

Flavobacterium psychrophilum