Post-Translational Protein Deimination Signatures in Plasma and Plasma EVs of Reindeer (Rangifer tarandus).

Stefania D’Alessio,Karl Skírnisson,Igor Kraev,Sigrun Lange,Stefanía Thorgeirsdóttir

doi:10.3390/biology10030222

Stefania D’Alessio, Karl Skírnisson + Show 3 more

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https://doi.org/10.3390/biology10030222

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Abstract

Simple SummaryReindeer are an important wild and domesticated species of the Arctic, Northern Europe, Siberia and North America. As reindeer have developed various strategies to adapt to extreme environments, this makes them an interesting species for studies into diversity of immune and metabolic functions in the animal kingdom. Importantly, while reindeer carry natural infections caused by viruses (including coronaviruses), bacteria and parasites, they can also act as carriers for transmitting such diseases to other animals and humans, so called zoonosis. Reindeer are also affected by chronic wasting disease, a neuronal disease caused by prions, similar to scrapie in sheep, mad cows disease in cattle and Creutzfeldt-Jakob disease in humans. The current study assessed a specific protein modification called deimination/citrullination, which can change how proteins function and allow them to take on different roles in health and disease processes. Profiling of deiminated proteins in reindeer showed that many important pathways for immune defenses, prion diseases and metabolism are enriched in deiminated proteins, both in plasma, as well as in plasma extracellular vesicles. This study provides a platform for the development of novel biomarkers to assess wild life health status and factors relating to zoonotic disease.The reindeer (caribou) Rangifer tarandus is a Cervidae in the order Artiodactyla. Reindeer are sedentary and migratory populations with circumpolar distribution in the Arctic, Northern Europe, Siberia and North America. Reindeer are an important wild and domesticated species, and have developed various adaptive strategies to extreme environments. Importantly, deer have also been identified to be putative zoonotic carriers, including for parasites, prions and coronavirus. Therefore, novel insights into immune-related markers are of considerable interest. Peptidylarginine deiminases (PADs) are a phylogenetically conserved enzyme family which causes post-translational protein deimination by converting arginine into citrulline in target proteins. This affects protein function in health and disease. Extracellular vesicles (EVs) participate in cellular communication, in physiological and pathological processes, via transfer of cargo material, and their release is partly regulated by PADs. This study assessed deiminated protein and EV profile signatures in plasma from sixteen healthy wild female reindeer, collected in Iceland during screening for parasites and chronic wasting disease. Reindeer plasma EV profiles showed a poly-dispersed distribution from 30 to 400 nm and were positive for phylogenetically conserved EV-specific markers. Deiminated proteins were isolated from whole plasma and plasma EVs, identified by proteomic analysis and protein interaction networks assessed by KEGG and GO analysis. This revealed a large number of deimination-enriched pathways for immunity and metabolism, with some differences between whole plasma and EVs. While shared KEGG pathways for whole plasma and plasma EVs included complement and coagulation pathways, KEGG pathways specific for EVs were for protein digestion and absorption, platelet activation, amoebiasis, the AGE–RAGE signaling pathway in diabetic complications, ECM receptor interaction, the relaxin signaling pathway and the estrogen signaling pathway. KEGG pathways specific for whole plasma were pertussis, ferroptosis, SLE, thyroid hormone synthesis, phagosome, Staphylococcus aureus infection, vitamin digestion and absorption, and prion disease. Further differences were also found between molecular function and biological processes GO pathways when comparing functional STRING networks for deiminated proteins in EVs, compared with deiminated proteins in whole plasma. This study highlights deiminated proteins and EVs as candidate biomarkers for reindeer health and may provide information on regulation of immune pathways in physiological and pathological processes, including neurodegenerative (prion) disease and zoonosis.

Highlights

The reindeer (Rangifer tarandus), known as the caribou in North America, is a mammal of the order Artiodactyla, family Cervidae, and has a circumpolar distribution
Peptidylarginine deiminases (PADs) Protein Homologue and Deiminated Proteins in Reindeer Plasma and Plasma extracellular vesicles (EVs) Anti-human PAD2, PAD3- and PAD4-specific antibodies were used in Western blotting for assessment of putative PAD protein homologues in reindeer, based on crossreaction
A positive protein band at the expected approximate 70–75 kDa size was identified for all three isozymes in plasma; in plasma EVs only PAD4 was positive, while neither PAD2 nor PAD3 where detected in plasma EVs (Figure 2A,B)

Summary

Introduction

The reindeer (Rangifer tarandus), known as the caribou in North America, is a mammal of the order Artiodactyla, family Cervidae, and has a circumpolar distribution. Reindeer play an important role in economy, society, culture and ecological values among populations of Eurasia and were fundamental for the colonization of the northern part of Eurasia. They have been a source of food among indigenous culture and were sporadically used for transportation, and can be considered as a semi-domesticated species [1]. R. tarandus may play roles in various zoonotic diseases, including parasitic, bacterial and viral ones [5,6,7,8], and deer have been recently identified to be new reservoir hosts for SARS-CoV-2 [9]

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