Radial glial cells, ubiquitous throughout the developing CNS, guide radially migrating neurons and are the precursors of astrocytes. Recent evidence indicates that radial glial cells also generate neurons in the developing cerebral cortex. Here we investigated the role of the transcription factor Pax6 expressed in cortical radial glia. We showed that radial glial cells isolated from the cortex of Pax6 mutant mice have a reduced neurogenic potential, whereas the neurogenic potential of non-radial glial precursors is not affected. Consistent with defects in only one neurogenic lineage, the number of neurons in the Pax6 mutant cortex in vivo is reduced by half. Conversely, retrovirally mediated Pax6 expression instructs neurogenesis even in astrocytes from postnatal cortex in vitro. These results demonstrated an important role of Pax6 as intrinsic fate determinant of the neurogenic potential of glial cells.
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We are grateful to A. Stoykova and A. Messing for the Sey- and 94-4 mice, respectively; D. Anderson, F. Guillemot, C. Lagenaur, P. Leprince and J. Price for antisera; J.E. Majors for the viral backbone plasmid; H. Wekerle and W. Klinkert for access to the FACSort; M. Öcalan for expertise in tissue culture; and F. Guillemot, B. Grothe, M. Korte and R. Klein for comments on the manuscript. The monoclonal antibody against nestin was obtained from the Developmental Studies Hybridoma Bank. Our work was supported by the EU Grant QLK3-1999-00894, European Cell Therapy in the Nervous System, a Marie Curie Fellowship to P.M. and the Max-Planck Society. F.C. is an Assistant Telethon Scientist (grant 38/CP).
The authors declare no competing financial interests.
Supplementary Figure 1. Astrocytes change their morphology, but do not acquire Pax6, in chemically defined medium. Corresponding fluorescent micrographs (A, C, E and B, D, F) of astrocytes from postnatal day 11 cortex cultured in medium containing fetal calf serum (FM) and switched to chemically-defined medium (CDM) for two days. Cultures were stained with antiserum directed against GLAST (A, B), GFAP (C, D) and Pax6 (E, F) as indicated. Note that astrocytes extend long processes in the CDM, but do not change their GLAST- and GFAP-immunoreactivity (A-D). Very weak Pax6-immunoreactivity is detected in astrocytes cultures in both conditions (E, F). Scale bar: 30µm. (JPG 48 kb)
Supplementary Figure 2. Increased number of neurosphere-forming cells in the Pax6-mutant cortex. (A) Micrograph shows a neurosphere culture from E14 cortex after 3 passages. (B) Histogram depicting the number of neurospheres generated by the same number of cells from wild-type (WT) and Pax6 mutant (Sey/Sey) cortex after 1-5 passages normalized to the number of neurospheres generated from WT cells). Note that Pax6-deficient precursors generate more than double the number of neurospheres than WT cortex precursors. (JPG 26 kb)
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Heins, N., Malatesta, P., Cecconi, F. et al. Glial cells generate neurons: the role of the transcription factor Pax6. Nat Neurosci 5, 308–315 (2002). https://doi.org/10.1038/nn828
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