Protein pathologies in oligodendroglia in neurodegenerative diseases

Neurodegenerative diseases are clinically, pathologically and genetically heterogeneous disorders characterised by progressive dysfunction and neuronal loss and the deposition of disease-specific proteinaceous aggregates in neurons and/or glia, showing a hierarchical involvement of brain regions. Research into disease mechanisms underlying neurodegenerative disorders has focused on the proteinaceous neuronal aggregates in vulnerable brain regions leading to neuronal dysfunction and degeneration and onset of clinical symptoms. However, emerging evidence highlights the importance of glia, including oligodendroglia, in the pathogenesis of neurodegenerative diseases, which have been underappreciated and frequently considered secondary to neuronal involvement. Pathologically altered proteins depositing in oligodendroglia comprise phosphorylated tau, α-synuclein, transactive response DNA-binding protein-43 (TDP-43) and occasionally FET/FUS. However, only primary oligodendroglial tau and α-synuclein deposits are considered for neuropathological diagnosis and classification of some tauopathies and synucleinopathies, respectively. Oligodendroglial tau pathology is also seen in ageing-related tau oligodendrogliopathy (ARTOG). This chapter provides an overview of neurodegenerative proteinopathies and protein pathologies affecting oligodendroglia.