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    Interactions between N-linked glycosylation and polymerisation of neuroserpin within the endoplasmic reticulum

    Moriconi, C. and Ordoñez, A. and Lupo, G. and Gooptu, Bibek and Irving, J.A. and Noto, R. and Martorana, V. and Manno, M. and Timpano, V. and Guadagno, N.A. and Dalton, L. and Marciniak, S.J. and Lomas, D.A. and Miranda, E. (2015) Interactions between N-linked glycosylation and polymerisation of neuroserpin within the endoplasmic reticulum. FEBS Journal 282 (23), pp. 4565-4579. ISSN 1742-464X.

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    Abstract

    The neuronal serpin neuroserpin undergoes polymerisation as a consequence of point mutations that alter its conformational stability, leading to a neurodegenerative dementia called familial encephalopathy with neuroserpin inclusion bodies (FENIB). Neuroserpin is a glycoprotein with predicted glycosylation sites at asparagines 157, 321 and 401. We used site-directed mutagenesis, transient transfection, western blot, metabolic labelling and ELISA to probe the relationship between glycosylation, folding, polymerisation and degradation of neuroserpin in validated cell models of health and disease. Our data show that glycosylation at N157 and N321 plays an important role in maintaining the monomeric state of neuroserpin, and we propose this is the result of steric hindrance or effects on local conformational dynamics that can contribute to polymerisation. Asparagine residue 401 is not glycosylated in wild type neuroserpin and in several polymerogenic variants that cause FENIB, but partial glycosylation was observed in the G392E mutant of neuroserpin that causes severe, early-onset dementia. Our findings indicate that N401 glycosylation reports lability of the C-terminal end of neuroserpin in its native state. This C-terminal lability is not required for neuroserpin polymerisation in the endoplasmic reticulum, but the additional glycan facilitates degradation of the mutant protein during proteasomal impairment. In summary, our results indicate how normal and variant-specific N-linked glycosylation events relate to intracellular folding, misfolding, degradation and polymerisation of neuroserpin.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): conformational disease, neurodegeneration, protein aggregation, serpin, serpinopathies
    School: Birkbeck Schools and Departments > School of Science > Biological Sciences
    Research Centre: Structural Molecular Biology, Institute of (ISMB)
    Depositing User: Administrator
    Date Deposited: 15 Jan 2016 09:12
    Last Modified: 06 Dec 2016 10:42
    URI: http://eprints.bbk.ac.uk/id/eprint/14006

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