Forebrain ependymal cells are Notch-dependent and generate neuroblasts and astrocytes after stroke


Neurons are continuously generated from stem cells in discrete regions in the adult mammalian brain. We found that ependymal cells lining the lateral ventricles were quiescent and did not contribute to adult neurogenesis under normal conditions in mice but instead gave rise to neuroblasts and astrocytes in response to stroke. Ependymal cell quiescence was actively maintained by canonical Notch signaling. Inhibition of this pathway in uninjured animals allowed ependymal cells to enter the cell cycle and produce olfactory bulb neurons, whereas forced Notch signaling was sufficient to block the ependymal cell response to stroke. Ependymal cells were depleted by stroke and failed to self-renew sufficiently to maintain their own population. Thus, although ependymal cells act as primary cells in the neural lineage to produce neurons and glial cells after stroke, they do not fulfill defining criteria for stem cells under these conditions and instead serve as a reservoir that is recruited by injury.

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Figure 1: Ependymal cells generate neuroblasts and astrocytes in response to stroke.
Figure 2: Ependymal cell loss after stroke is inhibited by constitutive Notch signaling.
Figure 3: The Notch signaling pathway in the adult lateral ventricle wall stem cell niche.
Figure 4: Canonical Notch signaling maintains ependymal phenotype.
Figure 5: RBP-J is required for ependymal cell maintenance.
Figure 6: Proliferation of ependymal cell progeny in the absence of RBP-J.
Figure 7: Ependymal cells generate neuroblasts after RBP-J deletion.
Figure 8: Ependymal cells give rise to olfactory bulb neurons after RBP-J deletion.


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We are grateful to U. Lendahl, O. Hermanson, A. Simon and members of the Frisén laboratory for valuable discussions; L. Ostrowski for the Foxj1 promoter construct; T. Li for antibodies to Crocc; U. Lendahl for N1IC and 12× Rbpj-dsgfp cDNA; O. Bergmann for virus injections; and M-L. Spångberg and K. Hamrin for technical assistance. This study was supported by grants from the Swedish Research Council, the Swedish Cancer Society, the Foundation for Strategic Research, the Juvenile Diabetes Research Foundation, the Karolinska Institute, Tobias Stiftelsen and the European Commission Framework VI Programme, EuroStemCell and StemStroke. M.C. and E.E. are supported by postdoctoral fellowships from the Swedish Brain Foundation (Hjärnfonden), C.G. by a postdoctoral fellowship from the Wenner-Gren Foundation and F.B.-H. by postdoctoral fellowships from the Canadian Institutes of Health Research and the Christopher and Dana Reeve Foundation.

Author information

M.C. and K.M. designed the study, carried out viral injections, analyzed and documented the Rbpj ablation and stroke experiments and wrote the paper. C.G. carried out viral injections and analyzed and documented the stroke experiments. V.D. conducted the stroke experiments. E.E. performed ultrastructural analyses. K.T. helped with the initial Rbpj ablation experiments. M.A. produced lentivirus. F.B.-H. carried out electroporation. M.S.Y.Y. contributed to the documentation of neuronal maturation in the olfactory bulb. L.N. supervised the lentivirus production. T.H. provided conditional Rbjp mice. Z.K. designed and analyzed the stroke experiments. O.S. designed and performed the ultrastructural analyses. R.M.C. initiated the study, carried out viral injections, analyzed and documented the Rbpj ablation experiments and the expression of components of the Notch pathway. O.L. designed and supervised the stroke experiments and wrote the paper. J.F. designed and supervised the study and wrote the paper.

Correspondence to Jonas Frisén.

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Carlén, M., Meletis, K., Göritz, C. et al. Forebrain ependymal cells are Notch-dependent and generate neuroblasts and astrocytes after stroke. Nat Neurosci 12, 259–267 (2009).

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