Homeostatic Functions of Tecrem, a CD46-Like Regulatory Protein of Complement Activation, on Epithelial Cells in Carp Fish

Harsha Prakash,Tomonori Somamoto,Takahiro Nagasawa,Shiori Motobe,Miki Nakao

doi:10.3390/jmse9070687

Abstract

Fish mucosal surface is a significant interface for pathogens to infect from an aqueous environment. In addition to mucosal innate and adaptive immune factors, epithelial cells are considered as a significant physical barrier against microbial invasion. Previously, we identified a mammalian CD46-like complement regulatory protein (Tecrem) in teleost and detected its expression on epithelial cells derived from fin, suggesting its physiological role on the fish surface. This study examines the homeostatic roles of Tecrem in maintaining the fish epithelium, by analyzing the expression behavior of Tecrem on the fin-derived epithelial cell lines (KF-1 from the common carp and CFS from ginbuna crucian carp) using monoclonal and polyclonal anti-Tecrem antibodies. Expression of KF-1 protein was associated with the adhesion of KF-1, and the adhesion was enhanced by anti-Tecrem treatments of the cells. Stimulation of the epithelial cells with anti-Tecrem enhanced wound healing, protein expression of tight-junction proteins, and cell density of the KF-1 and CFS monolayer culture. These results suggest that Tecrem on epithelial cells play a homeostatic role in maintaining intactness of the surface epithelial barrier, implying that modification of Tecrem expression may develop a novel tool to improve the first-line defense against pathogens in aquaculture.

Highlights

Primers were separately designed for the SCR 1-2 and SCR 3-4 regions of carp Tecrem (cTecrem), and the recombinant proteins were expressed in a prokaryotic system
Both rSCR1-2 and rSCR3-4 showed a single band of 13.5 kDa, agreeing well with the theoretical molecular masses of SCR1-2 and SCR3-4 domains calculated from their amino acid sequences (Figure 1A)
The results suggest that anti-SCR1-2 recognizes both cTecrem and ginbuna Tecrem, while anti-SCR3-4 is specific for cTecrem

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Aquaculture, a rapidly developing industry for animal protein supply, has been hampered by the persistent occurrence of infectious diseases caused by pathogenic microbes. High densities of the livestock under stressed conditions in tanks, ponds, and fish cages are considered as a major risk factor to increase the susceptibility of fish to pathogen infection. Fish body surfaces, including skin, gills, and intestine, face to microbe-rich environmental water through mucosal tissues. Mucosal immunity, including humoral and cellular factors, and physical barriers, has been regarded to be important for defense [1]

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Results

Conclusion