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Investigations of Myelin Basic Protein, SH3 Proteins and the Oligodendrocyte Cytoskeleton during Maturation and Development

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dc.contributor.advisor Harauz, George
dc.contributor.author Smith, Graham
dc.date.accessioned 2012-08-29T15:52:52Z
dc.date.available 2012-08-29T15:52:52Z
dc.date.copyright 2012-08
dc.date.created 2012-07-20
dc.date.issued 2012-08-29
dc.identifier.uri http://hdl.handle.net/10214/3884
dc.description.abstract The myelin basic protein (MBP) family arises from different transcription start sites of the Golli (gene of oligodendrocyte lineage) gene, with further variety generated by differential splicing. The “classic” MBP isoforms are peripheral membrane proteins that facilitate compaction of the mature myelin sheath, but also have multiple protein interactions. As an intrinsically disordered protein, MBP has proven to have complex structural and functional relationships with proteins in vitro including actin, tubulin, Ca2+-calmodulin, and multiple protein kinases. The investigations reported in this thesis were to further examine the multifunctionality, and protein:protein interactions of MBP with cytoskeletal and SRC homology 3 domain (SH3) proteins in cells using an oligodendrocyte (OLG) model system to better understand MBP’s contributions to membrane structure, formation, and elaboration in the developing OLG. A new function of MBP has been described showing that classic MBPs can modulate voltage operated calcium channels (VOCCs) by direct or indirect protein-protein interactions at the OLG cytoplasmic leaflet. These interactions contribute to global calcium homeostasis, and may play a complex developmental and spatiotemporal role in the regulation of oligodendrocyte precursor cell (OPC) migration and OLG differentiation. The importance of MBPs SH3 ligand binding domain within its central amino acid region was investigated with the protein-tyrosine kinase Fyn. Co-expression of MBP with a constitutively-active form of Fyn in OLGs resulted in membrane process elaboration, a phenomenon that was abolished by amino acid substitutions within MBP’s SH3-ligand domain. These results suggest that MBP’s SH3-ligand domain plays a key role, and may be required for proper membrane elaboration of developing OLGs. Lastly, interactions of MBP with the OLG cytoskeleton were investigated in OLGs transfected with fluorescently-tagged MBP, actin, tubulin, and zonula occludens 1 (ZO-1). MBP redistributes to distinct ‘membrane-ruffled’ regions of the plasma membrane where it had increased co-localization with actin and tubulin, and with the SH3-domain-containing proteins cortactin and ZO-1, when stimulated with PMA, a potent activator of the protein kinase C pathway. The results presented here advance our understanding regarding protein:protein interactions of MBP, and its multifunctionality in OLGs with regards to membrane formation and elaboration. en_US
dc.description.sponsorship This work was supported by the Canadian Institutes of Health Research (MOP #86483, J.M.B. and G.H.), and Discovery Grants from the Natural Sciences and Engineering Research Council of Canada (NSERC, G.H., RG121541). G.S.T.S. was a recipient of a Doctoral Studentship from the Multiple Sclerosis Society of Canada en_US
dc.language.iso en en_US
dc.subject Oligodendrocyte en_US
dc.subject myelin en_US
dc.subject myelin basic protein en_US
dc.subject calcium imaging en_US
dc.subject golli en_US
dc.subject SH3 domain en_US
dc.subject live-cell imaging en_US
dc.subject intrinsically disordered protein en_US
dc.title Investigations of Myelin Basic Protein, SH3 Proteins and the Oligodendrocyte Cytoskeleton during Maturation and Development en_US
dc.type Thesis en_US
dc.degree.programme Biophysics en_US
dc.degree.name Doctor of Philosophy en_US
dc.degree.department Department of Molecular and Cellular Biology en_US
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