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Osteonectin is a Schwann cell-secreted factor that promotes retinal ganglion cell survival and process outgrowth

Authors

  • Edward T. W. Bampton,

    1. Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
    2. Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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      Present address: Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.

  • Chi Him Ma,

    1. Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
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  • Aviva M. Tolkovsky,

    1. Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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  • Jeremy S. H. Taylor

    1. Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
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Dr J. S. H. Taylor, as above.
E-mail: Jeremy.taylor@anat.ox.ac.uk

Abstract

We have investigated the factors made by Schwann cells (SCs) that stimulate survival and neurite outgrowth from postnatal rat retinal ganglion cells (RGCs). These effects are preserved under K252a blockade of the Trk family of neurotrophin receptors and are not fully mimicked by the action of a number of known trophic factors. To identify novel factors responsible for this regenerative activity, we have used a radiolabelling assay. Proteins made by SCs were labelled radioactively and then fed to purified RGCs. The proteins taken up by the RGCs were then isolated and further characterized. Using this assay we have identified a major 40 kDa factor taken up by RGCs, which was microsequenced and shown to be the matricellular protein osteonectin (ON). Using an in vitro assay of purified RGCs we show that ON promotes both survival and neurite outgrowth. We conclude that ON has a potential new role in promoting CNS repair.

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