title: Oligodendrocyte progenitors balance growth with self-repulsion to achieve homeostasis in the adult brain.
abstract: The adult CNS contains an abundant population of oligodendrocyte precursor cells (NG2(+) cells) that generate oligodendrocytes and repair myelin, but how these ubiquitous progenitors maintain their density is unknown. We generated NG2-mEGFP mice and used in vivo two-photon imaging to study their dynamics in the adult brain. Time-lapse imaging revealed that NG2(+) cells in the cortex were highly dynamic; they surveyed their local environment with motile filopodia, extended growth cones and continuously migrated. They maintained unique territories though self-avoidance, and NG2(+) cell loss though death, differentiation or ablation triggered rapid migration and proliferation of adjacent cells to restore their density. NG2(+) cells recruited to sites of focal CNS injury were similarly replaced by a proliferative burst surrounding the injury site. Thus, homeostatic control of NG2(+) cell density through a balance of active growth and self-repulsion ensures that these progenitors are available to replace oligodendrocytes and participate in tissue repair.
authors.affiliation: The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Ethan G
authors.initials: EG
authors.lastname: Hughes
authors.forename: Shin H
authors.initials: SH
authors.lastname: Kang
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukaya
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Bergles
mesh_terms: D000818:Animals; D002452:Cell Count; D016923:Cell Death / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D002540:Cerebral Cortex / Q000166:cytology* / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D058953:Neural Stem Cells / Q000502:physiology*; D009836:Oligodendroglia / Q000502:physiology*; D059008:Time-Lapse Imaging