Initiation of neuronal differentiation requires PI3-kinase/TOR signalling in the vertebrate neural tube

Katherine J. Fishwick, Roman A. Li, Pamela Halley, Peiyi Deng, Kate G. Storey

    Research output: Contribution to journalArticle

    36 Citations (Scopus)

    Abstract

    Regulated neuron production within the vertebrate nervous system relies on input from multiple signalling pathways. Work in the Drosophila retina has demonstrated that PI3-kinase and downstream TOR signalling regulate the timing of photoreceptor differentiation: however, the function of such signals during vertebrate neurogenesis is not well understood. Here we show that mutant mice lacking PKB activity downstream of PDK1, the master kinase of the PI3-kinase pathway, exhibit deficient neuron production. We further demonstrate expression of PI3-kinase signalling components and active PKB and TOR signalling in the chick spinal cord, an early site of neurogenesis. Neuron production was also attenuated in the chick neural tube following exposure to small molecule inhibitors of PI3-kinase (LY294002) or TOR (Rapamycin) activity. Furthermore, Rapamycin repressed expression of early neuronal differentiation genes, such as Ngn2, but did not inhibit expression of Sox1B genes characteristic of proliferating neural progenitors. In addition, some cells expressing an early neuronal marker were mis-localised at the ventricular surface in the presence of Rapamycin and remained aberrantly within the cell cycle. These findings suggest that TOR signalling is necessary to initiate neuronal differentiation and that it may facilitare coordination of cell cycle and differentiation programmes. In contrast, stimulating PI3-kinase signalling did not increase neuron production, suggesting that such activity is simply permissive for vertebrate neurogenesis. (C) 2009 Elsevier Inc. All rights reserved.

    Original languageEnglish
    Pages (from-to)215-225
    Number of pages11
    JournalDevelopmental Biology
    Volume338
    Issue number2
    DOIs
    Publication statusPublished - 15 Feb 2010

    Keywords

    • Vertebrate neurogenesis
    • Chick
    • Mouse
    • PI3-kinase
    • TOR
    • Rapamycin
    • Neuronal differentiation
    • Cell cycle
    • Tuberous sclerosis
    • Central nervous system
    • Growth factor actions
    • Kinase-B-gamma
    • Spinal cord
    • Mammalian target
    • Messenger RNA
    • Stem cells
    • Factor-I
    • Insulin
    • Pathway

    Cite this

    Fishwick, Katherine J. ; Li, Roman A. ; Halley, Pamela ; Deng, Peiyi ; Storey, Kate G. / Initiation of neuronal differentiation requires PI3-kinase/TOR signalling in the vertebrate neural tube. In: Developmental Biology. 2010 ; Vol. 338, No. 2. pp. 215-225.
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    Initiation of neuronal differentiation requires PI3-kinase/TOR signalling in the vertebrate neural tube. / Fishwick, Katherine J.; Li, Roman A.; Halley, Pamela; Deng, Peiyi; Storey, Kate G.

    In: Developmental Biology, Vol. 338, No. 2, 15.02.2010, p. 215-225.

    Research output: Contribution to journalArticle

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    AU - Li, Roman A.

    AU - Halley, Pamela

    AU - Deng, Peiyi

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    AB - Regulated neuron production within the vertebrate nervous system relies on input from multiple signalling pathways. Work in the Drosophila retina has demonstrated that PI3-kinase and downstream TOR signalling regulate the timing of photoreceptor differentiation: however, the function of such signals during vertebrate neurogenesis is not well understood. Here we show that mutant mice lacking PKB activity downstream of PDK1, the master kinase of the PI3-kinase pathway, exhibit deficient neuron production. We further demonstrate expression of PI3-kinase signalling components and active PKB and TOR signalling in the chick spinal cord, an early site of neurogenesis. Neuron production was also attenuated in the chick neural tube following exposure to small molecule inhibitors of PI3-kinase (LY294002) or TOR (Rapamycin) activity. Furthermore, Rapamycin repressed expression of early neuronal differentiation genes, such as Ngn2, but did not inhibit expression of Sox1B genes characteristic of proliferating neural progenitors. In addition, some cells expressing an early neuronal marker were mis-localised at the ventricular surface in the presence of Rapamycin and remained aberrantly within the cell cycle. These findings suggest that TOR signalling is necessary to initiate neuronal differentiation and that it may facilitare coordination of cell cycle and differentiation programmes. In contrast, stimulating PI3-kinase signalling did not increase neuron production, suggesting that such activity is simply permissive for vertebrate neurogenesis. (C) 2009 Elsevier Inc. All rights reserved.

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    KW - Kinase-B-gamma

    KW - Spinal cord

    KW - Mammalian target

    KW - Messenger RNA

    KW - Stem cells

    KW - Factor-I

    KW - Insulin

    KW - Pathway

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