Post-translational protein deimination in cod (Gadus morhua L.) ontogeny novel roles in tissue remodelling and mucosal immune defences?

Abstract

Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophysiological roles conserved throughout phylogeny. PADs promote post-translational deimination of protein arginine to citrulline, altering the structure and function of target proteins. Deiminated proteins were detected in the early developmental stages of cod from 11 days post fertilisation to 70 days post hatching. Deiminated proteins were present in mucosal surfaces and in liver, pancreas, spleen, gut, muscle, brain and eye during early cod larval development. Deiminated protein targets identified in skin mucosa included nuclear histones; cytoskeletal proteins such as tubulin and beta-actin; metabolic and immune related proteins such as galectin, mannan-binding lectin, toll-like receptor, kininogen, Beta2-microglobulin, aldehyde dehydrogenase, bloodthirsty and preproapolipoprotein A-I. Deiminated histone H3, a marker for anti-pathogenic neutrophil extracellular traps, was particularly elevated in mucosal tissues in immunostimulated cod larvae. PAD-mediated protein deimination may facilitate protein moonlighting, allowing the same protein to exhibit a range of biological functions, in tissue remodelling and mucosal immune defences in teleost ontogeny.

Deiminated proteins in extracellular vesicles and serum of llama (Lama glama)—Novel insights into camelid immunity

“…A llama PAD homologue was identified at an expected 70-75 kDa size similar as for human PADs by Western blotting via cross reaction with anti-human PAD2, PAD3 and PAD4 antibodies. PAD2 is known to be the phylogenetically most conserved PAD form (Vossenaar et al, 2003;Magnadóttir et al, 2018a) and has also been seen in shark (Criscitiello et al, 2019). Deiminated histone H3, a marker of neutrophil extracellular trap formation (NETosis), was also detected in llama serum by Western blotting and is described for the first time in a camelid species but was recently described in shark (Criscitiello et al, 2019).…”

“…NETosis is driven by PADs (Li et al, 2010), is conserved throughout phylogeny and is important in innate immune defences against a range of pathogens including bacteria, viruses and helminths (Brinkmann et al, 2004;Branzk et al, 2014;Schönrich and Raftery, 2016). NETosis has also been associated with clearance of apoptotic cells and during tissue remodelling in teleosts (Magnadóttir et al, 2018a(Magnadóttir et al, , 2019a. Furthermore, NETosis is linked to a range of autoimmune diseases, due to NET activation via neo-epitopes (O'Neil and Kaplan, 2019), which can also lead to organ damage (Lee et al, 2017).…”

“…This can cause functional and structural changes in target proteins (Vossenaar, and intrinsically disordered proteins, while the position of the arginine is also important; arginines sitting next to aspartic acid residues are most prone to citrullination, arginines next to glutamic acid residues are rarely citrullinated and those flanked by proline are poorly citrullinated (Nomura, 1992;Tarcsa et al, 1996;György et al, 2006). Protein deimination can affect gene regulation, cause generation of neoepitopes (Witalison et al, 2015;Lange et al, 2017) and may also allow for protein moonlighting, an evolutionary acquired phenomenon facilitating proteins to exhibit several physiologically relevant functions within one polypeptide chain (Henderson and Martin, 2014;Jeffrey, 2018;Magnadóttir et al, 2018a). PADs have been identified throughout phylogeny from bacteria to mammals, with 5 tissue specific PAD isozymes in mammals, 3 in chicken, 1 in bony fish and arginine deiminase homologues in bacteria (Vossenaar et al, 2003;Rebl et al, 2010;Magnadóttir et al, 2018a, a;Kosgodage et al, 2019).…”

“…Protein deimination can affect gene regulation, cause generation of neoepitopes (Witalison et al, 2015;Lange et al, 2017) and may also allow for protein moonlighting, an evolutionary acquired phenomenon facilitating proteins to exhibit several physiologically relevant functions within one polypeptide chain (Henderson and Martin, 2014;Jeffrey, 2018;Magnadóttir et al, 2018a). PADs have been identified throughout phylogeny from bacteria to mammals, with 5 tissue specific PAD isozymes in mammals, 3 in chicken, 1 in bony fish and arginine deiminase homologues in bacteria (Vossenaar et al, 2003;Rebl et al, 2010;Magnadóttir et al, 2018a, a;Kosgodage et al, 2019). While studies on PADs in relation to human pathophysiology, including cancer, autoimmune and neurodegenerative diseases (Wang and Wang, 2013;Witalison et al, 2015;Lange et al, 2017;Kosgodage et al, 2017Kosgodage et al, & 2018 and CNS regeneration (Lange et al, 2011 and2014) exist, relatively little phylogenetic research has been carried out on PADs in relation to normal physiology and evolutionary acquired adaptions of the immune system.…”

“…While studies on PADs in relation to human pathophysiology, including cancer, autoimmune and neurodegenerative diseases (Wang and Wang, 2013;Witalison et al, 2015;Lange et al, 2017;Kosgodage et al, 2017Kosgodage et al, & 2018 and CNS regeneration (Lange et al, 2011 and2014) exist, relatively little phylogenetic research has been carried out on PADs in relation to normal physiology and evolutionary acquired adaptions of the immune system. Recent comparative studies focussing on roles for PADs in teleost fish have identified post-translational deimination in key proteins of innate, adaptive and mucosal immunity (Magnadóttir et al, 2018a, b;Magnadottir et al, 2019a;Magnadóttir et al, 2019b). A recent study in shark also revealed novel insights into this post-translational modification in relation to key immune factors, including shark immunoglobulins (Criscitiello et al, 2019).…”