D'Alessio Stefania, Thorgeirsdóttir Stefanía, Kraev Igor, Skírnisson Karl, Lange Sigrun
Tissue Architecture and Regeneration Research Group, School of Life Sciences, University of Westminster, London W1W 6UW, UK.
Institute for Experimental Pathology at Keldur, University of Iceland, Keldnavegur 3, 112 Reykjavik, Iceland.
Biology (Basel). 2021 Mar 13;10(3):222. doi: 10.3390/biology10030222.
The reindeer (caribou) 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, 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.
驯鹿属于偶蹄目鹿科动物。驯鹿有定居型和迁徙型种群，在北极地区、北欧、西伯利亚和北美呈环极分布。驯鹿是一种重要的野生和家养物种，已经形成了各种适应极端环境的策略。重要的是，驯鹿也被确定为可能的人畜共患病载体，包括寄生虫、朊病毒和冠状病毒的载体。因此，对免疫相关标志物的新见解具有相当大的研究价值。肽基精氨酸脱亚氨酶（PADs）是一个在系统发育上保守的酶家族，通过将靶蛋白中的精氨酸转化为瓜氨酸来引起翻译后蛋白质脱亚氨基作用。这会影响健康和疾病状态下的蛋白质功能。细胞外囊泡（EVs）通过货物材料的转移参与细胞间通讯，在生理和病理过程中发挥作用，并且它们的释放部分受PADs调节。本研究评估了在冰岛采集的16只健康野生雌性驯鹿血浆中脱亚氨基蛋白和EVs谱特征，这些驯鹿在进行寄生虫和慢性消耗病筛查时被采集血样。驯鹿血浆EVs谱显示其粒径在30到400纳米之间呈多分散分布，并且对系统发育保守的EVs特异性标志物呈阳性反应。从全血浆和血浆EVs中分离出脱亚氨基蛋白，通过蛋白质组学分析进行鉴定，并通过KEGG和GO分析评估蛋白质相互作用网络。这揭示了大量在免疫和代谢方面富含脱亚氨基作用的途径，全血浆和EVs之间存在一些差异。全血浆和血浆EVs共有的KEGG途径包括补体和凝血途径，而EVs特有的KEGG途径涉及蛋白质消化和吸收、血小板活化、阿米巴病、糖尿病并发症中的AGE-RAGE信号通路、细胞外基质受体相互作用、松弛素信号通路和雌激素信号通路。全血浆特有的KEGG途径包括百日咳、铁死亡、系统性红斑狼疮、甲状腺激素合成、吞噬体、感染、维生素消化和吸收以及朊病毒病。在比较EVs中脱亚氨基蛋白与全血浆中脱亚氨基蛋白的功能STRING网络时，还发现分子功能和生物学过程GO途径之间存在进一步差异。本研究强调脱亚氨基蛋白和EVs作为驯鹿健康的候选生物标志物，并可能提供有关生理和病理过程中免疫途径调节的信息，包括神经退行性（朊病毒）疾病和人畜共患病。
