title: Ependymal stem cells divide asymmetrically and transfer progeny into the subventricular zone when activated by injury.
abstract: Evidence is presented to show that cells of the ependymal layer surrounding the ventricles of the mammalian (rat) forebrain act as neural stem cells (NSCs), and that these cells can be activated to divide by a combination of injury and growth factor stimulation. Several markers of asymmetric cell division (ACD), a characteristic of true stem cells, are expressed asymmetrically in the ependymal layer but not in the underlying subventricular zone (SVZ), and when the brain is treated with a combination of local 6-hydroxydopamine (6-OHDA) with systemic delivery of transforming growth factor-alpha (TGFalpha), ependymal cells divide asymmetrically and transfer progeny into the SVZ. The SVZ cells then divide as transit amplifying cells (TACs) and their progeny enter a differentiation pathway. The stem cells in the ependymal layer may have been missed in many previous studies because they are usually quiescent and divide only in response to strong stimuli.
authors.affiliation: Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA. dgleason@uci.edu
authors.forename: D
authors.initials: D
authors.lastname: Gleason
authors.forename: J H
authors.initials: JH
authors.lastname: Fallon
authors.forename: M
authors.initials: M
authors.lastname: Guerra
authors.forename: J-C
authors.initials: JC
authors.lastname: Liu
authors.forename: P J
authors.initials: PJ
authors.lastname: Bryant
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001930:Brain Injuries / Q000139:chemically induced / Q000503:physiopathology; D001973:Bromodeoxyuridine; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D048749:Cytokinesis / Q000187:drug effects / Q000502:physiology; D004805:Ependyma / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D020547:Lateral Ventricles / Q000166:cytology / Q000502:physiology*; D008297:Male; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016627:Oxidopamine; D051381:Rats; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013565:Sympatholytics; D016211:Transforming Growth Factor alpha / Q000378:metabolism / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D009419:Nerve Tissue Proteins; D013565:Sympatholytics; D016211:Transforming Growth Factor alpha; D016627:Oxidopamine; D001973:Bromodeoxyuridine