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dc.contributor.authorChong Goh, Yawen
dc.date.accessioned2018-05-14T10:11:30Z
dc.date.available2018-05-14T10:11:30Z
dc.date.issued2005en
dc.identifier.urihttp://hdl.handle.net/1842/29663
dc.description.abstracten
dc.description.abstractThe studies undertaken in this research project characterised as fully as possible the antigen identified by the monoclonal antibody BOB78. Earlier studies (Hart, Ross et al. 2000) have linked BOB78 to the identification of apoptotic cells. The present project extended this finding by further studies utilising various antibody -based techniques on cancer -derived cell lines in different stages of apoptosis.en
dc.description.abstractThe BOB78 antigen was confirmed to be present in normal cells and to be multi -lineage. BOB78 antigen is normally expressed within the cytosol of nucleated cells, but absent in anucleated red blood cells which do not undergo apoptosis. Following depolarisation of mitochondrial transmembrane potential, a key event in the initiation of apoptosis, BOB78 antigen is detected on the surface of the outer cell membrane. This surfacing of the BOB78 antigen parallels that of phosphatidylserine residues, presently the most well characterised marker for apoptosis in analysis with flow cytometry. Immunocytochemistry corroborated this finding by showing the translocation of the BOB78 antigen to membrane blebs of apoptotic cells. Observations using agents which disrupt the endomembrane synthetic pathways suggest that BOB78 is probably not trafficked through the Golgi apparatus or processed for secretion. Although BOB78 is an IgM antibody, it does not identify a carbohydrate epitope and is therefore likely to be specific for a multi -lineage protein.en
dc.description.abstractMembrane blebbing in apoptotic cells appears to share certain characteristics with the budding of platelets from megakaryocytes. For example, the production of platelets during the terminal differentiation of megakaryocytes involves activation of caspases. Interestingly, BOB78 was found by flow cytometric analysis to be present in platelets as they develop from the membranes of the MEG -01 megakaryocytes. BOB78 was also expressed on the surface of senescent platelets. These MEG -01 platelets were therefore used for purification of BOB78 through immunoprecipitation. The captured BOB78 antigen was sequenced using MALDI -TOF, which identified it as chaperonin, also known as heat shock protein 60 (hsp60).en
dc.description.abstractHeat shock protein 60 is a highly conserved stress protein which has chaperone functions in prokaryotes as well mammalian cells. Expression of hsp60 on the surface of apoptotic cells may serve novel functions or purposes akin to molecular chaperoning. Mechanisms underlying the translocation of hsp60 to the cell membrane have been characterised in various prokaryotes. Homologous pathways of movement for this highly conserved entity are likely to exist in mammalian cells. The observation that hsp60 is expressed on the surface of senescent platelets suggests a possible role as a recognition signal in phagocytosis. Platelets are equipped with caspases and when senescent display membrane changes typical of apoptotic cells. Like apoptotic cells, platelets are normally cleared from tissues by macrophages. Surface expression of hsp60 is probably an essential change marking cellular entities for uptake by phagocytes. It remains to be studied if engulfment of bodies displaying an endogenous moiety like hsp60 might play a key role in mediating a non -inflammatory response observed in apoptosis. It may also be speculated that hsp60 serves the function of molecular mimicry as many intracellular bacteria display surface hsp60, the expression of which has been linked to pathogenic invasiveness. The ability of these microbes to evade immune clearance may be linked to the non -inflammatory apoptotic disguise which surface hsp60 confers on them.en
dc.publisherThe University of Edinburghen
dc.relation.isreferencedbyen
dc.subjectAnnexe Thesis Digitisation Project 2018 Block 18en
dc.titleCharacterisation of a cell-surface marker of apoptosisen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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