Cellular mechanisms in prion-mediated neurodegeneration

Prion diseases are fatal neurodegenerative disorders of both humans and other animals. The cause of prion-mediated neurodegeneration by conversion of the normal cellular prion protein (PrPC) to the disease-related isoform (PrPSc) remains unknown. Increasing evidence suggests a role for the ubiquitin proteasome system (UPS) in prion disease. PrPC and PrPSc isoforms have been shown to accumulate in cells after proteasome inhibition, leading to increased cell death. The aim of this thesis was to investigate the role of cellular degradation systems, such as the UPS and autophagy, in prion-mediated cell death. In UPS-mediated degradation poly-ubiquitinated substrates get degraded by the 26S proteasome, which comprises a 20S hydrolytic core and a 19S regulatory particle. Using a variety of biochemical methods, I report that abnormal beta-sheet-rich PrP isoforms inhibit the catalytic activity of the 26S proteasome, by specifically inhibiting its beta1 and beta5 proteolytic subunits. Pre-incubating these PrP isoforms with an antibody raised against aggregation intermediates abrogates the inhibitory effect seen, consistent with an ‘oligomeric’ inhibitory species. Using open-gated yeast 20S proteasome mutants and conserved 19S ATPase C-terminal peptides containing an essential motif for gate-opening, this thesis describes findings supporting an inhibitory effect on proteasomal gating rather than a direct inhibitory effect on the active sites of the 20S proteasome. These C-terminal peptides open the gate in a ‘key in a lock’ fashion by docking into inter-subunit pockets in the alpha-ring of the 20S proteasome. In this system, the inhibitory effect of the beta-sheet-rich PrP isoforms may be due to abnormal PrP competing with the C-terminal peptides for the inter-subunit pockets, thereby preventing gate-opening. Proteins are also degraded by autophagy, a degradation pathway that has not been adequately characterised in prion disease. This thesis investigates potential roles autophagy may play in prion disease. Data presented here suggest that a) prions are cleared by autophagy, b) prion-infected cells have higher numbers of autophagosomes compared to uninfected controls, c) induction of autophagy ameliorates cell death after proteasome inhibition, indicating cross-talk between the two protein-degradation pathways, and d) it is up-regulated in vivo at end-stage prion disease

Shaman, Sage, Priest, Prophet and Magician: Exploring the Architecture of the Religious Wise Man

Little attention has been given to the archetype of the wise old man, both by Carl G. Jung and by contemporary scholars indebted to his methodology. This is especially relevant when compared to other common Jungian archetypes such as the ‘hero’, the ‘mother’ and the ‘trickster.’ As such, the wise man can be viewed as a neglected or overlooked figure whose image is so familiar and recognisable that his purpose and representations have not currently received the depth of analysis and explanation that has been given to other archetypal images. This thesis identifies the religious wise man as an important figure within the contexts of culture and religion. Its aim is to not only to explore the ‘archetype’ of the wise man, but to go beyond that rather superficial – and indeed, academically problematic – notion, and determine what I term the ‘architecture’ of the wise man. This architecture consists of the structural elements (social, institutional, historical) and identifiers (costume, calling, education), that separate the wise man, and in particular the religious wise man, from other male ‘archetypal’ figures. In using the term ‘architecture’ I aim to identify the arrangement of concrete elements and characteristics - rather than psychological or inner ‘essences’ - which are significant in the construction and maintenance of the religious wise man figure in specific cultural contexts. The dissertation presents five possible categories of the religious wise man - the shaman, sage, priest, prophet and magician – identifying common elements and distinguishing features that may then be redesigned and adapted in different and unique forms appropriate to each manifestation of the religious wise man. Once these key characteristics are identified, they create a schema that can be employed to classify a range of religious wise man figures into the appropriate category

Proteomic analysis of FOXP proteins reveals interactions between cortical transcription factors associated with neurodevelopmental disorders

FOXP transcription factors play important roles in neurodevelopment, but little is known about how their transcriptional activity is regulated. FOXP proteins cooperatively regulate gene expression by forming homo- and hetero-dimers with each other. Physical as

The structure of blocks with a Klein four defect group

We prove Erdmann’s conjecture [16] stating that every block with a Klein four defect group has a simple module with trivial source, and deduce from this that Puig’s finiteness conjecture holds for source algebras of blocks with a Klein four defect group. The proof uses the classification of finite simple groups

Additive Polynomials for Finite Groups of Lie Type

This paper provides a realization of all classical and most exceptional finite groups of Lie type as Galois groups over function fields over F_q and derives explicit additive polynomials for the extensions. Our unified approach is based on results of Matzat which give bounds for Galois groups of Frobenius modules and uses the structure and representation theory of the corresponding connected linear algebraic groups.Comment: 59 pages; v2: added reference, slightly restructured section 6.1, few small rewordings; v3: completed realization of Steinberg's triality groups (thanks to P. Mueller for solving the remaining open question); clarified argument how to use Thm. 3.

Overlapping SETBP1 gain-of-function mutations in Schinzel-Giedion syndrome and hematologic malignancies

Schinzel-Giedion syndrome (SGS) is a rare developmental disorder characterized by multiple malformations, severe neurological alterations and increased risk of malignancy. SGS is caused by de novo germline mutations clustering to a 12bp hotspot in exon 4 of SETBP1. Mutations in this hotspot disrupt a degron, a signal for the regulation of protein degradation, and lead to the accumulation of SETBP1 protein. Overlapping SETBP1 hotspot mutations have been observed recurrently as somatic events in leukemia. We collected clinical information of 47 SGS patients (including 26 novel cases) with germline SETBP1 mutations and of four individuals with a milder phenotype caused by de novo germline mutations adjacent to the SETBP1 hotspot. Different mutations within and around the SETBP1 hotspot have varying effects on SETBP1 stability and protein levels in vitro and in in silico modeling. Substitutions in SETBP1 residue I871 result in a weak increase in protein levels and mutations affecting this residue are significantly more frequent in SGS than in leukemia. On the other hand, substitutions in residue D868 lead to the largest increase in protein levels. Individuals with germline mutations affecting D868 have enhanced cell proliferation in vitro and higher incidence of cancer compared to patients with other germline SETBP1 mutations. Our findings substantiate that, despite their overlap, somatic SETBP1 mutations driving malignancy are more disruptive to the degron than germline SETBP1 mutations causing SGS. Additionally, this suggests that the functional threshold for the development of cancer driven by the disruption of the SETBP1 degron is higher than for the alteration in prenatal development in SGS. Drawing on previous studies of somatic SETBP1 mutations in leukemia, our results reveal a genotype-phenotype correlation in germline SETBP1 mutations spanning a molecular, cellular and clinical phenotype