dc.contributor.advisor | Gillingwater, Tom | |
dc.contributor.advisor | Wishart, Tom | |
dc.contributor.author | Mutsaers, Chantal | |
dc.date.accessioned | 2014-12-04T14:09:22Z | |
dc.date.available | 2014-12-04T14:09:22Z | |
dc.date.issued | 2014-06-28 | |
dc.identifier.uri | http://hdl.handle.net/1842/9774 | |
dc.description.abstract | Low levels of survival motor neuron (SMN) protein cause the autosomal recessive
neurodegenerative disease spinal muscular atrophy (SMA), through mechanisms that
are poorly defined. SMN protein is ubiquitously expressed, however the major
pathological hallmarks of SMA are focused on the neuromuscular system, including
a loss of lower motor neurons in the ventral horn of the spinal cord and atrophy of
skeletal muscle. At present there is no cure for SMA. Most research to date has
focused on examining how low levels of SMN lead to pathological changes in motor
neurons, therefore the contribution of other tissues, for example muscle, remains
unclear. In this thesis I have used proteomic techniques to identify intrinsic
molecular changes in muscle of SMA mice that contribute to neuromuscular
pathology in SMA. I demonstrate significant disruption to the molecular composition
of skeletal muscle in pre-symptomatic SMA mice, in the absence of any detectable
degenerative changes in lower motor neurons and with a molecular profile distinct
from that of denervated muscle. Functional cluster analysis of proteomics data and
phospho-histone H2AX labelling of DNA damage revealed increased activity of cell
death pathways in SMA muscle. In addition robust up-regulation of VDAC2 and
down-regulation of parvalbumin was confirmed in two mouse models of SMA as
well as in patient muscle biopsies. Thus intrinsic pathology of skeletal muscle is an
important event in SMA. I then used proteomics to identify individual proteins in
skeletal muscle of SMA that report directly on disease status. Two proteins, GRP75
and calreticulin, showed increased expression levels over time in different muscles as
well as in skin samples, a more accessible tissue for biopsies in patients. Preliminary
results suggest that GRP75 and calreticulin can be detected and measured in SMA
patient muscle biopsies. These results show that proteomics provides a powerful
platform for biomarker identification in SMA, revealing GRP75 and calreticulin as
peripherally accessible potential protein biomarkers capable of reporting on disease
progression in muscle as well as in skin samples. Finally I identified a role for
ubiquitin-dependent pathways in regulating neuromuscular pathology in SMA.
Levels of ubiquitin-like modifier activating enzyme 1 (UBA1) were reduced in
spinal cord and skeletal muscle tissue of SMA mice. Dysregulation of UBA1 and
subsequently the ubiquitination pathways led to the accumulation of β-catenin. I
show here that pharmacological inhibition of β-catenin robustly ameliorates
neuromuscular pathology in animal models of SMA. Interestingly, downstream
disruption of β-catenin was restricted to the neuromuscular system in SMA mice.
Pharmacological inhibition of β-catenin failed to prevent systemic pathology in
organs. Thus disruption of ubiquitin homeostasis, with downstream consequences for
β-catenin signalling, contributes to the pathogenesis of SMA, thereby highlighting
novel therapeutic targets for this disease. | en_US |
dc.contributor.sponsor | Medical Research Council (MRC) | en_US |
dc.contributor.sponsor | SMA trust | en_US |
dc.language.iso | en | en_US |
dc.publisher | The University of Edinburgh | en_US |
dc.relation.hasversion | Mutsaers CA, Lamont DJ, Hunter G, Wishart TM, Gillingwater TH. Label-free proteomics identifies Calreticulin and GRP75/Mortalin as peripherally accessible protein biomarkers for spinal muscular atrophy. Genome Med. 2013 Oct 18;5(10):95. | en_US |
dc.relation.hasversion | Thomson SR, Nahon JE, Mutsaers CA, Thomson D, Hamilton G, Parson SH, Gillingwater TH. Morphological characteristics of motor neurons do not determine their relative susceptibility to degeneration in a mouse model of severe spinal muscular atrophy. Plos One. 2012 Dec 7(12). | en_US |
dc.relation.hasversion | Mutsaers CA, Wishart TM, Lamont DJ, Riessland M, Schreml J, Comley LH, Murray LM, Parson SH, Lochmüller H, Wirth B, Talbot K, Gillingwater TH. Reversible molecular pathology of skeletal muscle in spinal muscular atrophy. Hum Mol Genet. 2011 Nov 15;20(22):4334-44. | en_US |
dc.relation.hasversion | Comley LH, Fuller HR, Wishart TM, Mutsaers CA, Thomson D, Wright AK, Ribchester RR, Morris GE, Parson SH, Horsburgh K, Gillingwater TH. ApoE isoform-specific regulation of regeneration in the peripheral nervous system. Hum Mol Genet. 2011 Jun 15;20(12):2406-21. | en_US |
dc.relation.hasversion | Wishart TM, Huang JP, Murray LM, Lamont DJ, Mutsaers CA, Ross J, Geldsetzer P, Ansorge O, Talbot K, Parson SH, Gillingwater TH. SMN deficiency disrupts brain development in a mouse model of severe spinal muscular atrophy. Hum Mol Genet. 2010 Nov 1;19(21):4216-28. | en_US |
dc.relation.hasversion | Xu W, Berger SP, Trouw LA, de Boer HC, Schlagwein N, Mutsaers C, Daha MR, van Kooten C. Properdin binds to late apoptotic and necrotic cells independently of C3b and regulates alternative pathway complement activation. J Immunol. 2008 Jun 1;180(11):7613-21. | en_US |
dc.subject | SMA | en_US |
dc.subject | spinal muscular atrophy | en_US |
dc.subject | proteomics | en_US |
dc.subject | disease mechanism | en_US |
dc.subject | biomarkers | en_US |
dc.title | Mechanisms of disease pathogenesis in Spinal Muscular Atrophy | en_US |
dc.type | Thesis or Dissertation | en_US |
dc.type.qualificationlevel | Doctoral | en_US |
dc.type.qualificationname | PhD Doctor of Philosophy | en_US |