Abstract | Naked mole-rats are long-lived animals which show unusual resistance to hypoxia, cancer and ageing. Protein deimination is an irreversible post-translational modification caused by the peptidylarginine deiminase (PADs) family of enzymes, which convert arginine into citrulline in target proteins. Protein deimination can cause structural and functional protein changes, facilitating protein moonlighting, but also leading to neo-epitope generation and effects on gene regulation. Furthermore, PADs have been found to regulate cellular release of extracellular vesicles (EVs), which are lipid-vesicles released from cells as part of cellular communication. EVs carry protein and genetic cargo and are indicative biomarkers that can be isolated from most body fluids. This study was aimed at profiling deiminated proteins in plasma and EVs of naked mole-rat. Key immune and metabolic proteins were identified to be post-translationally deiminated, with 65 proteins specific for plasma, while 42 proteins were identified to be deiminated in EVs only. Using protein-protein interaction network analysis, deiminated plasma proteins were found to belong to KEEG pathways of immunity, infection, cholesterol and drug metabolism, while deiminated proteins in EVs were in addition linked to KEEG pathways of HIF-1 signalling and glycolysis. The mole-rat EV profiles showed a poly-dispersed population of 50-300 nm, similar to observations from human plasma. Furthermore, the EVs were assessed for three key microRNAs involved in cancer, inflammation and hypoxia. The identification of post-translational deimination of critical immunological and metabolic markers may contribute to current understanding of protein moonlighting functions via post-translational changes in longevity and cancer resistance in mole-rats. |
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