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HSP70 interacting protein prevents the accumulation of inclusions in polyglutamine disease1

Authors

  • Joanna L. Howarth,

    1. Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, Dorothy Hodgkin Building, University of Bristol, Bristol, UK
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  • Colin P. J. Glover,

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    • 2

      The present address of Colin P. J. Glover is the Molecular & Cellular Neurobiology Psychiatry DTG, GlaxoSmithKline, Essex, CM19 5AW, UK.

  • James B. Uney

    1. Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, Dorothy Hodgkin Building, University of Bristol, Bristol, UK
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  • 1

    Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.

Address correspondence and reprint requests to James Uney, Henry Wellcome Laboratories for Integrative Neuroscience & Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK. E-mail: james.uney@bristol.ac.uk

Abstract

Heat shock proteins (HSPs) are associated with the proteinaceous inclusions that characterise many neurodegenerative diseases. This suggests they may be associated with disease aetiology and/or represents an attempt to remove abnormal protein aggregates. In this study the adenoviral mediated over-expression of HSP70 interacting protein (HIP) alone was shown to significantly reduce inclusion formation in both an in vitro model of Spinal Bulbar Muscular Atrophy and a primary neuronal model of polyglutamine disease. Experiments to determine the mechanism of action showed that: denatured luciferase activity (a measure of protein refolding) was not increased in the presence of HIP alone but was increased when HIP was co-expressed with HSP70 or Heat Shock cognate protein 70 (HSC70); the expression of polyglutamine inclusions in cortical neurons mediated an increase in the levels of HSC70 but not HSP70. Our data suggest that HIP may prevent inclusion formation by facilitating the constitutive HSC70 refolding cycle and possibly by preventing aggregation. HIP expression is not increased following stress and its over-expression may therefore reduce toxic polyglutamine aggregation events and contribute to an effective therapeutic strategy.

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