dc.contributor.author
Bauer, Johannes H.
dc.date.accessioned
2018-06-07T23:05:26Z
dc.date.available
2001-12-03T00:00:00.649Z
dc.identifier.uri
https://refubium.fu-berlin.de/handle/fub188/10037
dc.identifier.uri
http://dx.doi.org/10.17169/refubium-14235
dc.description
Title page and contents
Chapter I - Introduction
1 A Matter of Death 1
1.1 Necrosis 1
1.1.1 Morphological Features of Necrosis 2
1.2 Apoptosis 2
1.2.1 Morphological Features of Apoptosis 3
1.3 Apoptosis and Necrosis: A Continuum? 4
2 The Molecular Components of Apoptosis
2.1 Death Receptors 5
2.2 Bcl-2 Family 6
2.3 Apaf-1 Family 7
2.4 Caspases 7
2.5 DNases 8
2.6 Cytochrome c 9
2.7 Inhibitors of Apoptosis 9
2.8 Other molecules 10
3 Apoptotic Signaling Pathways
3.1 Mitochondria-dependent Death 12
3.2 Death Receptor Pathway 15
3.3 The C. elegans death machinery 17
4 Huntingtons Disease
4.1 Disease Phenotype 19
4.2 Molecular Basis of HD 19
4.3 The Function of wtHtt 23
4.4 Other triplet expansion diseases 24
5 The goals of this study 26
6 Figures and Legends 28
7 References 44
Chapter II - The Function
1 Introduction 57
2 Preliminary Results
2.1 Effects of Htt on viability at the non-permissive temperature 59
2.2 WtHtt prevents the appearance of apoptotic markers 60
3 Results
3.1 The anti-apoptotic function of wtHtt 61
3.2 WtHtt acts downstream of Cytochrome c-release 63
3.3 WtHtt inhibits Cytochrome c-dependent Caspase-9 activity 65
3.4 WtHtt prevents Cytochrome c-dependent cleavage of pro-Caspase-9 66
4 Discussion 68
5 Materials and Methods 73
6 Figures and Legends 76
7 References 96
Chapter III - The Mechanism
1 Introduction 97/p>
2 Results
2.1 No upregulation of heat shock proteins by Htt 99
2.2 Htt is part of a large protein complex 99
2.3 Caspase-9 interacts with both wtHtt and muHtt 103
2.4 WtHtt does not interact with Apaf-1 104
2.5 WtHtt does not interact with Bcl-2 family members 104
2.6 WtHtt preferentially interacts with the zymogen form of Caspase-9 105
2.7 WtHtt interacts with long pro-domain caspases 105
2.8 Htt binds the catalytic domain of Caspase-9 106
2.9 Interaction between endogenous proteins 106
2.10 Htt is upregulated in some cancer cell lines 107
3 Discussion 108
4 Materials and Methods 114
5 Figures and Legends 116
6 References 137
Chapter IV - The Recombinant Trap
1 Introduction 138
2 Results
2.1 Production of recombinant wtHtt and recombinant Caspase-9 139
2.2 Binding experiments 140
2.3 Htt phosphorylation by Akt 140
2.4 The final straw 141
3 Discussion 143
4 Materials and Methods 145
5 Figures and Legends 147
6 References 151
Chapter V - WORMS!
1 Introduction 152
2 Results
2.1 Htt interacts with components of the C. elegans death machinery 157
2.2 Introduction of Htt constructs into wildtype C. elegans 157
2.3 Breeding of the Htt extrachromosomal arrays into different genetic
backgrounds 159
2.4 Phenotypes 161
3 Discussion 164
4 Materials and Methods 268
5 Figures and Legends 271
6 References 187
Chapter VI - Conclusion
1 Discussion 189
2 References 198
Appendix
Acknowledgements 200
Thanks 201
Special Thanks 202
Abbreviations 203
Curriculum Vitae of the Author 205
dc.description.abstract
Huntington's Disease is a neurodegenerative disease that leads to progressive
cell death of a select set of neurons. It is caused by the expansion of a
stretch of glutamines in the N-terminus of the Huntingtin (Htt) protein. This
gain-of-function event results in increased apoptosis of striatal neurons.
Wild-type (wt) Htt is an ubiquitously expressed protein whose function remains
largely unknown. Mice with a targeted disruption of the Htt gene die early in
utero. In this work, the question of the function of wtHtt and the apoptotic
pathways engaged by the poly-Q expanded mutant (mu) Htt is addressed. Results
show that wtHtt is an anti-apoptotic protein that protects striatal cell lines
from various apoptotic stimuli. Htt acts downstream of mitochondrial
Cytochrome c release and interacts with the catalytic domain of Caspase-9.
This interaction leads to decreased Cytochrome c-dependent cleavage of pro-
Caspase-9 and decreased catalytic activity, probably through inhibition of
proper apoptosome formation. The results also show that muHtt does retain some
of the function of the wt protein, most markedly interaction with Caspase-9.
In addition, muHtt induces apoptosis in striatal cell lines by a mechanism
that involves Caspase-3 activation. Most importantly, pro-apoptotic activity
of muHtt is also observed in C. elegans.
de
dc.description.abstract
Chorea Huntington (HD) ist eine autosomal-dominante, neurodegenerative
Krankheit, die zu selektivem, progressivem neuronalen Zellverlust führt.
Ursache ist eine Mutation im Gen IT15, das das Huntingtin (Htt) Protein
kodiert. Die Folge ist eine pathogene Expansion einer Reihe von Glutaminen im
N-terminus von Huntingtin, was in Apoptose von Neuronen im Striatum
resultiert. Wildtyp Htt ist ein ubiquitär exprimiertes Protein unbekannter
Funktion. Mäuse, in denen Htt Expression durch homologe Rekombination
ausgeschaltet wurde, sterben früh während der Schwangerschaft in utero. Die
Funktion wtHtts und die pro-apoptotischen Signalwege poly-Q mutierten (mu)
Htts werden in dieser Arbeit untersucht. Die Ergebnisse zeigen, daß wtHtt
anti-apoptotisch in einem neuronalem Zellkulturmodel wirkt. Diese anti-
apoptotische Funktion entfaltet sich nach Cytochrom c-Efflux aus den
Mitochondrien durch Interaktion mit der katalytischen Domäne von Caspase-9.
Dies führt zu reduzierter katalytischer Aktivität von Caspase-9. MuHtt zeigt
einige Funktionalitäten wtHtts, einschließlich Interaktion mit Caspase-9.
Darüberhinaus aktiviert muHtt pro-apoptotische Signalwege. Diese pro-
apototische Wirkung ist reproduzierbar in C. elegans.
de
dc.rights.uri
http://www.fu-berlin.de/sites/refubium/rechtliches/Nutzungsbedingungen
dc.subject
Huntington's Disease
dc.subject
neurodegenerative diseases
dc.subject.ddc
500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften
dc.title
Apoptotic Regulation by the Huntingtin Protein
dc.contributor.firstReferee
Peter A. Ward, MD
dc.contributor.furtherReferee
Prof. Dr. Ferdinand Hucho
dc.date.accepted
2001-12-17
dc.date.embargoEnd
2001-12-19
dc.identifier.urn
urn:nbn:de:kobv:188-2001002481
dc.title.translated
Apoptotische Regulation durch das Huntingtin Protein
de
refubium.affiliation
Biologie, Chemie, Pharmazie
de
refubium.mycore.fudocsId
FUDISS_thesis_000000000481
refubium.mycore.transfer
http://www.diss.fu-berlin.de/2001/248/
refubium.mycore.derivateId
FUDISS_derivate_000000000481
dcterms.accessRights.dnb
free
dcterms.accessRights.openaire
open access
