Subcellular trafficking of proteolipid protein (PLP/DM20) and novel mechanisms of ER retention in Pelizaeus-Merzbacher disease

Dhaunchak, Ajit Singh

dc.contributor.advisor	Nave, Klaus-Armin Prof. Dr.	de
dc.contributor.author	Dhaunchak, Ajit Singh	de
dc.date.accessioned	2006-11-22T06:48:36Z	de
dc.date.accessioned	2013-01-18T14:24:08Z	de
dc.date.available	2013-01-30T23:51:08Z	de
dc.date.issued	2006-11-22	de
dc.identifier.uri	http://hdl.handle.net/11858/00-1735-0000-0006-B365-C	de
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-3205
dc.format.mimetype	application/pdf	de
dc.language.iso	eng	de
dc.rights.uri	http://webdoc.sub.gwdg.de/diss/copyr_diss.html	de
dc.title	Subcellular trafficking of proteolipid protein (PLP/DM20) and novel mechanisms of ER retention in Pelizaeus-Merzbacher disease	de
dc.type	doctoralThesis	de
dc.title.translated	Subcellular trafficking of proteolipid protein (PLP/DM20) and novel mechanisms of ER retention in Pelizaeus-Merzbacher disease	de
dc.contributor.referee	Nave, Klaus-Armin Prof. Dr.	de
dc.date.examination	2006-06-26	de
dc.subject.dnb	570 Biowissenschaften	de
dc.subject.dnb	Biologie	de
dc.description.abstracteng	Missense mutations that predict the misfolding of membrane proteins have been associated with a number of neurogenetic diseases. However, it is not known how apparently minor changes in the amino acid sequence of an extracellular loop or a transmembrane domain lead to complete ER retention with complex loss- and gain-of-function effects. I have chosen PLP/DM20, a highly conserved and abundant tetraspan myelin protein, associated with Pelizaeus-Merzbacher disease (PMD), as a model system. By expressing wildtype and mutant PLP isoforms in glial cells, surprising molecular properties became apparent, including the ability to self-assemble from two truncated PLP polypeptides, and to form conformation sensitive epitope that become masked as the protein matures in the ER. With respect to human disease, it was possible to identify a novel molecular mechanism by which missense mutations cause ER retention of misfolded PLP. Unexpectedly, pairs of cysteines within an extracellular loop of PLP/DM20 play a critical role. Multiple disease-causing mutations require the presence of cysteines such that misfolded PLP/DM20 is efficiently retained in the ER. Replacing cysteines by serine completely prevents ER retention and restores normal trafficking of mutant PLP/DM20. This demonstrates a novel pathological mechanism by which missense mutations greatly reduce the efficiency of intramolecular disulfide bridging. When exposed by misfolding to the ER lumen, unpaired cysteines engage in alternative oxidations that lead to abnormal intermolecular crosslinks. Since extracellular cysteines are a feature of many membrane proteins, this novel pathomechanism is likely to contribute to a diverse group of genetic diseases. To monitor the expression and subcellular trafficking of PLP in vivo, a transgenic knock-in mouse in being generated that will express a PLP-EGFP fusion protein under control of the endogenous promoter. In an attempt to develop a cure for Pelizaeus-Merzbacher disease (PMD), we treated a genuine animal model (rumpshaker mice) with Turmeric. The active constituent of this herbal drug (Curcumin) is a non-toxic Ca2+ adenosine triphosphatase pump inhibitor, and known to release membrane proteins from ER retention. In a pilot experiment, we extended the lifespan of rumpshaker mice from 20 to 60 days. These promising data suggest that a therapeutic strategy should be developed for PMD, using turmeric and our in vitro and in vivo models.	de
dc.contributor.coReferee	Jahn, Reinhard Prof. Dr.	de
dc.contributor.thirdReferee	Neumann, Harald Prof. Dr.	de
dc.subject.topic	Molecular Biology & Neurosciences Program	de
dc.subject.ger	N.A	de
dc.subject.eng	Myelin	de
dc.subject.eng	proteolipid protein	de
dc.subject.eng	PLP	de
dc.subject.eng	PLP/DM20	de
dc.subject.eng	ER retention	de
dc.subject.eng	chaperons	de
dc.subject.eng	protein folding	de
dc.subject.eng	myelin diseases	de
dc.subject.eng	Pelizaeus-Merzbacher disease	de
dc.subject.eng	conformation disease	de
dc.subject.eng	protein traffiking	de
dc.subject.eng	exosomes	de
dc.subject.eng	live cell imaging	de
dc.subject.eng	cell biology	de
dc.subject.eng	oli-neu	de
dc.subject.eng	oligodendrocyte precursor	de
dc.subject.eng	disulfide bond	de
dc.subject.bk	42.15	de
dc.subject.bk	42.13	de
dc.identifier.urn	urn:nbn:de:gbv:7-webdoc-1341-2	de
dc.identifier.purl	webdoc-1341	de
dc.affiliation.institute	Göttinger Graduiertenschule für Neurowissenschaften und molekulare Biowissenschaften (GGNB)	de
dc.subject.gokfull	WHC 000: Zellbestandteile und ihre Funktion {Cytologie}	de
dc.subject.gokfull	WHF 000: Zell- und Gewebephysiologie	de
dc.subject.gokfull	Zellphysiologie {Cytologie}	de
dc.subject.gokfull	WHM 000: Cytohistochemie	de
dc.subject.gokfull	Zyto-und Histochemie {Cytologie}	de
dc.subject.gokfull	WF 200: Molekularbiologie	de
dc.identifier.ppn	614145635	de