published_or_final_version / abstract / toc / Biochemistry / Master / Master of Philosophy

The human androgen receptor (hAR) is a ligand-activated, DNA-binding nuclear transcription factor. Mutations in the hAR result in varying degrees of androgen insensitivity (AI); they may play a predisposing or pathogenetic role in both prostate and breast cancer. Expansion of the hAR's N-terminal polymorphic Glutamine (Gln) repeat causes a late-onset progressive motoneuronopathy which is associated with mild androgen insensitivity: spinal and bulbar muscular atrophy (SBMA). SBMA belongs to a group of translated CAG trinucleotide repeat expansion neuronopathies that includes Huntington disease, dentatorubral-pallidoluysian atrophy and five distinct spinocerebellar ataxias. The fact that this group of disorders is caused by polyGln expansions in totally unrelated proteins, is one of the main reasons for postulating that a common gain-of-function mechanism must underlie their communal pathogenesis. This common pathogenetic mechanism is postulated to occur via aberrant protein interactions. / I undertook a search for hAR-interacting proteins using a yeast two-hybrid system. A human testes cDNA library was screened several times with two forms of an N-terminal fragment of the hAR: a normal (20 Gin) hAR and an expanded (50 Gin) hAR. A few candidate hAR-interacting proteins were isolated during the library screenings and I tested them for physiological relevance. / A second aspect of my project included the analysis of an aberrant 75-kD protein fragment generated in COS-1 cells transfected with a polyCAG-expanded (n = 44) hAR cDNA. Recent work in Huntington disease and spinocerebellar ataxia type 3 shows the accumulation of insoluble protein aggregates primarily in the nucleus of certain brain cells (Davies et al., 1997; Scherzinger et al., 1997; Paulson et al., 1997). I confirmed the presence of the aberrant hAR-fragment in the nucleus through western analysis of protein samples extracted from the nucleus.

Temperature is a critical environmental signal, which exerts powerful control over the development and virulence of diverse microbial pathogens. Fungi, along with other microbial species, exploit a diversity of mechanisms to sense and respond to temperature fluctuations that may be encountered in the host or under other conditions of temperature stress. For Candida albicans, the leading fungal pathogen of humans, temperature influences mating, phenotypic switching, resistance to antifungal drugs, and the morphogenetic transition from yeast to filamentous growth. C. albicans morphogenesis is strongly influenced by temperature, and most filament inducing cues depend on a concurrent increase of temperature to 37˚C before morphogenesis can occur. Further elevated temperature of 39˚C to 42˚C can serve as an independent filament-inducing cue, although the molecular mechanisms underpinning this temperature-dependent morphogenetic transition remain largely uncharacterized. Here, I provide the first comprehensive investigation of the molecular mechanisms mediating temperature-dependent morphogenesis in C. albicans. I establish that the thermally responsive molecular chaperone Hsp90 orchestrates temperature-dependent morphogenesis, and that Hsp90 functions as a key temperature sensor, such that elevated temperature is required to relieve Hsp90-mediated repression of the morphogenetic program. Further, I demonstrate that Hsp90 controls morphogenesis via at least two distinct cellular signaling cascades. First, Hsp90 and its co-chaperone Sgt1 physically interact, and together regulate protein kinase A (PKA) signaling via an interaction with the adenylyl cyclase of the PKA cascade, Cyr1, such that genetic depletion of either Hsp90 or Sgt1 activates PKA signaling and induces filamentation. Second, Hsp90 controls temperature-dependent morphogenesis via previously uncharacterized cellular circuitry comprised of the cyclin-dependent kinase Pho85, the cyclin Pcl1, and the transcriptional regulator Hms1. Together, this research illuminates the central role of Hsp90 in coupling temperature sensing and morphogenesis in the human fungal pathogen C. albicans.

No description available.

Yes / A 3500‐year‐old papyrus from ancient Egypt provides a list of treatments for many diseases including “bite hair loss,” most likely alopecia areata (AA). The treatment of AA remained largely unchanged for over 1500 years. In 30 CE, Celsus described AA presenting as scalp alopecia in spots or the “windings of a snake” and suggested treatment with caustic compounds and scarification. The first “modern” description of AA came in 1813, though treatment still largely employed caustic agents. From the mid‐19th century onwards, various hypotheses of AA development were put forward including infectious microbes (1843), nerve defects (1858), physical trauma and psychological stress (1881), focal inflammation (1891), diseased teeth (1902), toxins (1912) and endocrine disorders (1913). The 1950s brought new treatment developments with the first use of corticosteroid compounds (1952), and the first suggestion that AA was an autoimmune disease (1958). Research progressively shifted towards identifying hair follicle‐specific autoantibodies (1995). The potential role of lymphocytes in AA was made implicit with immunohistological studies (1980s). However, studies confirming their functional role were not published until the development of rodent models (1990s). Genetic studies, particularly genome‐wide association studies, have now come to the forefront and open up a new era of AA investigation (2000s). Today, AA research is actively focused on genetics, the microbiome, dietary modulators, the role of atopy, immune cell types in AA pathogenesis, primary antigenic targets, mechanisms by which immune cells influence hair growth, and of course the development of new treatments based on these discoveries. / Alopecia UK.

No description available.

Torque teno virus (TTV) is a single stranded circular DNA virus and, despite its widespread nature in the human population, its pathogenesis is still unknown. Factors complicating TTV research include its huge genetic diversity, difficulties identifying an uninfected control population, the lack of a small animal model and lack of a good cell culture system for viral propagation. Recently we have identified a TTV homologue (RoTTV) in wild rodents. RoTTV was frequently observed in wood mice and field voles. RoTTV infections were also found in bank voles but not in Mus musculus populations. Analysis of complete genome sequencing shows that several genetic variants are found in wild rodent population with two distinct species containing several diverse genotypes. Furthermore, multiple variants were present in single individuals, consistent with infection patterns seen in humans. RoTTV transcripts in infected wild wood mice have also been detected and fully sequenced. Predicted protein coding regions from these transcripts have been expressed in cell culture and show the different expression patterns. Using cloned genomic DNA it has also been possible to observe the transcription from the virus in vitro and it was shown RoTTV viral titer in the supernatant of culture fluid increased. In addition, RoTTV propagation was observed by using the supernatant of culture fluid. Using cloned genomic DNA and the culture supernatant, an in vivo model system in naïve laboratory wood mice was developed.

published_or_final_version / abstract / Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Medicine / Master / Doctor of Medicine

published_or_final_version / abstract / Microbiology / Master / Master of Philosophy