Classically, the central nervous system (CNS) was considered to contain neurons and three main types of glial cells - astrocytes, oligodendrocytes, and microglia. Now, it has been clearly established that NG2-glia are a fourth glial cell type that are identified and defined by their expression of the NG2 chondroitin sulfate proteoglycan (Cspg4). NG2-glia differentiate into oligodendrocytes, the myelin-forming cells of the CNS, under the control of multiple extacellular and intrinsic factors. Due to this, NG2-glia are often referred to in the literature as oligodendrocyte progenitor cells (OPCs). The name polydendrocytes has been suggested for NG2-glia (OPCs), to emphasize their nature as a fourth distinct glial cell type. NG2-glia respond rapidly to neurotransmission via their synaptic connections with neurons and their repertoire of neurotransmitter receptors and ion channels. Bidirectional interactions between NG2-glia and neurons are also important for synaptic function and neuronal integrity. NG2-glia respond to most neuropathologies by increased proliferation and differentiation into oligodendrocytes, which is critical for replacing damaged myelin after injury and in demyelinating diseases, such as multiple sclerosis. There is also evidence NG2-glia are capable of generating astrocytes and neurons under some circumstances. The full capacity of NG2-glia is not yet clear, but their key function is the lifelong generation of oligodendrocytes, which is absolutely critical for CNS function and integrity.
Table of Contents
Identification and Lineage of NG2-Glia (Polydendrocytes)
Physiological Characteristics of NG2-Glia (Polydendrocytes)
Synaptic Signalling in NG2-Glia (Polydendrocytes)
Pathological Responses of NG2-Glia (Polydendrocytes)
Titles of Related Interest
About the Author(s)Arthur M. Butt
, University of Portsmouth
Professor Arthur M. Butt has worked on glial cells for over 30 years using multiple cell biological, molecular, anatomical, and physiological techniques. He received his PhD from King's College London in 1986, working with Joan Abbott, a leader in blood-brain barrier research. After a postdoctoral position in the lab of Ed Liebermann (North Carolina, USA) and a Grass Fellowship at Wood's Hole Marine Laboratories, Professor Butt joined the lab of Bruce Ransom (Yale University, USA). Here, he began his work on glial cells in the optic nerve and has pursued this line of research ever since. Professor Butt started his first independent laboratory in Guy's & St Thomas' Hospitals Medical and Dental Schools in 1990, where he worked closely with Martin Berry, a leader in CNS regeneration studies. After gaining a personal chair in King's College London in 2000, Professor Butt moved to the University of Portsmouth in 2005 and served as the Director of the Institute of Biomedical and Biomolecular Sciences, until standing down in 2016. Professor Butt is on the editorial board of Glia and edited the first special issues on novel polydendrocytes for the Journal of Neurocytology in 2000 and Journal of Anatomy in 2002. Professor Butt has focussed on the fundamental biology of glial cells, with a particular relevance to multiple sclerosis and neurodegeneration. In this regard, Professor Butt would like to thank especially the Multiple Sclerosis Society, the Anatomical Society, and The International Spinal Research Trust for supporting his research on polydendrocytes over the years.