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Science 330 (6005): 773-

Copyright © 2010 by the American Association for the Advancement of Science

Introduction

Glee for Glia

Peter Stern


Figure 1

CREDIT: BEN EMERY (CENTRE FOR NEUROSCIENCE AND FLOREY NEUROSCIENCE INSTITUTES, UNIVERSITY OF MELBOURNE, AUSTRALIA) AND SARA MULINYAWE (STANFORD UNIVERSITY, CALIFORNIA, USA)

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Research on glial cells has come of age. Until a few years ago, gliobiologists felt they had to justify their existence, often in a department of neuroscience or neurobiology, and they regularly stressed the abundance of glia as compared to that of neurons in the nervous system. Now, however, the outdated notion that glia are simply the glue that holds the nerve cells together but otherwise have no active role in the brain has been laid to rest for good. Years of thorough research and the steady accumulation of solid evidence have confirmed that glia are highly complex cells engaged in a plethora of functions. The role of glia in, among other examples, synapse formation, synapse maturation and plasticity, and the rapid conduction of action potentials, as well as their immunological functions in the nervous system, have by now been unequivocally established. Hence, this year's neuroscience special issue is devoted to glial cells.

Astrocytes are an important fraction of glial cells in the brain. The molecular mechanisms underlying astrocyte specification and growth and their interactions with other cell types to assemble the nervous system are still not completely understood. In his Review, Freeman (p. 774) presents and discusses exciting findings and ideas concerning the development, specification, and morphogenesis of astrocytes. Another type of glial cell, oligodendrocytes, is central to the brain's myelination, which ensures the efficiency and speed of action potentials. Emery (p. 779) reviews new approaches to investigating oligodendrocyte differentiation and myelination in the central nervous system. Microglia are another fascinating subpopulation of glial cells. They sense pathological tissue alterations and they can develop into brain macrophages and perform immunological functions. In a Perspective, Graeber (p. 783) outlines the involvement of microglia in the treatment of higher brain functional defects.

In the research section of the magazine, Lee et al. (p. 790) report that tonic inhibition in the cerebellum is due to GABA released from glial cells by permeation through the Bestrophin 1 anion channel. Ginhoux et al. (p. 841) investigate the developmental origin of microglia and show that adult microglia derive from primitive myeloid progenitor cells that arise before embryonic day 8. In a Perspective, Fields (p. 768) presents his hypothesis that white matter, which consists mostly of myelinated axons, may play a role in brain plasticity and learning.

The 9 November issue of Science Signaling complements this Science special issue on glia with research into signaling pathways involved in drug-resistant glioma, which is a type of aggressive brain cancer (www.sciencemag.org/special/glia). A Perspective by Ballanyi et al. describes how astrocytes sense changes in pH to stimulate the neurons that control breathing and, in a Podcast, Fields discusses mechanisms by which nerve and glial cells communicate outside of synapses.

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