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Expression and function of orphan nuclear receptor TLX in adult neural stem cells

Abstract

The finding of neurogenesis in the adult brain led to the discovery of adult neural stem cells1. TLX was initially identified as an orphan nuclear receptor expressed in vertebrate forebrains2 and is highly expressed in the adult brain3. The brains of TLX-null mice have been reported to have no obvious defects during embryogenesis4; however, mature mice suffer from retinopathies5, severe limbic defects, aggressiveness, reduced copulation and progressively violent behaviour4,6. Here we show that TLX maintains adult neural stem cells in an undifferentiated, proliferative state. We show that TLX-expressing cells isolated by fluorescence-activated cell sorting (FACS) from adult brains can proliferate, self-renew and differentiate into all neural cell types in vitro. By contrast, TLX-null cells isolated from adult mutant brains fail to proliferate. Reintroducing TLX into FACS-sorted TLX-null cells rescues their ability to proliferate and to self-renew. In vivo, TLX mutant mice show a loss of cell proliferation and reduced labelling of nestin in neurogenic areas in the adult brain. TLX can silence glia-specific expression of the astrocyte marker GFAP in neural stem cells, suggesting that transcriptional repression may be crucial in maintaining the undifferentiated state of these cells.

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Acknowledgements

We thank G. Cabrera, S. Tiep, M. Nelson, H. Juguilon, J. Havstad, B. Miller, R. Summers, A. Consiglio, A. Huynh, L. Moore, A. Dearie and H. Lansford for technical help; M. L. Gage for editing; E. Stevens and E. Ong for administrative assistance; C. Zhang for comments on the manuscript; R. Marr and I. Verma for the lentiviral vector; and T. Kitamura for the pMY vector and PlatE cells. Y.S. is a fellow of the Susan G. Komen Breast Cancer Foundation. D.C.L. was supported by the Deutsche Forschungsgemeinschaft. P.T. was supported by the Pasarow Foundation. K.N. was supported by a Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowship for Research Abroad. R.M.E. is an Investigator of the Howard Hughes Medical Institute at the Salk Institute and March of Dimes Chair in Molecular and Developmental Biology. F.H.G. is the Adler Professor of Age-Related Neurodegenerative Diseases. This work was supported by the Howard Hughes Medical Institute, the NIH, the Christopher Reeve Paralysis Foundation, the National Institutes of Aging, the Michael J. Fox Foundation, Project ALS and the Lookout Fund.

Author information

Correspondence to Fred H. Gage or Ronald M. Evans.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Figure 1: TLX-/- cells cultured in growth media at day 1 and 10. (JPG 30 kb)

Supplementary Figure 2: Quantitation of nestin+ (a) and GFAP+ cells (b) from TLX+/- and TLX-/- culture in growth media. (JPG 41 kb)

Supplementary Figure 3: GFP fluorescence and nestin-staining of TLX-/- cells expressing TLX-GFP. (JPG 43 kb)

Supplementary Figure 4: Quantitation of Ki67+ (a) and GFAP+ cells (b) in TLX-/- cells infected with control or TLX-GFP lentivirus. (JPG 42 kb)

Supplementary Figure Legends (DOC 23 kb)

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Further reading

Figure 1: Expression of TLX in adult NSCs.
Figure 2: TLX-positive cells are self-renewable and multipotent.
Figure 3: TLX is a transcriptional repressor.
Figure 4: Loss of nestin and BrdU staining in TLX mutant mouse brain.

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