Pentraxins CRP-I and CRP-II are post-translationally deiminated and differ in tissue specificity in cod (Gadus morhua L.) ontogeny

Abstract

Pentraxins arefluid phase pattern recognition molecules that form an important part of the innate immunedefence and are conserved betweenfish and human. In Atlantic cod (Gadus morhuaL.), two pentraxin-likeproteins have been described, CRP-I and CRP-II. Here we show for thefirst time that these two CRP forms arepost-translationally deiminated (an irreversible conversion of arginine to citrulline) and differ with respect totissue specific localisation in cod ontogeny from 3 to 84 days post hatching. While both forms are expressed inliver, albeit at temporally differing levels, CRP-I shows a strong association with nervous tissue while CRP-II isstrongly associated to mucosal tissues of gut and skin. This indicates differing roles for the two pentraxin types inimmune responses and tissue remodelling, also elucidating novel roles for CRP-I in the nervous system. Thepresence of deimination positive bands for cod CRPs varied somewhat between mucus and serum, possiblyfacilitating CRP protein moonlighting, allowing the same protein to exhibit a range of biological functions andthus meeting different functional requirements in different tissues. The presentedfindings may further currentunderstanding of the diverse roles of pentraxins in teleost immune defences and tissue remodelling, as well as invarious human pathologies, including autoimmune diseases, amyloidosis and cancer.