This thesis describes investigations into the genetic basis and pathophysiology of three distinct inherited diseases in humans, two of which are strongly associated to the function of the ectodomain sheddase enzyme ADAM17. The first of these is a novel inherited syndrome of neonatal onset inflammatory skin and bowel disease, which is associated in a consanguineous family with homozygous loss-offunction mutations in ADAM17. This thesis describes investigations of the expression and function of ADAM17 – and downstream proteins it regulates – in an individual affected by this disease. This is accompanied by genetic investigations into other individuals suspected of suffering from the same syndrome. The second investigated disease is Tylosis with Oesophageal Cancer (TOC), an inherited cutaneous disease which represents the only known syndrome of familial oesophageal cancer susceptibility. This disease was associated to dominantly inherited mutations in the Rhomboid protein iRHOM2. This work describes investigations of immortalised keratinocyte cell lines and tissues derived from TOC-affected individuals, and illustrates that the pathogenesis of TOC is characterised by increased iRHOM2-dependent activation and activity of ADAM17, and upregulation of the shedding of ADAM17 substrates, particularly in the EGFR ligand family, accompanied by increased desmosome turnover and transglutaminase 1 activity. This pattern of upregulation results in attendant increases in growth factor signalling, proliferation and motility in TOC keratinocytes, dependent on ADAM17. The third focus of this thesis is a life-threatening inherited gastrointestinal disease (accompanied by severe extraintestinal complications) whose symptoms correspond to Cryptogenic Multifocal Ulcerative Stenosing Enteritis. This work describes the identification of mutations in cytosolic phospholipase A2-α (cPLA2α) – an enzyme responsible for arachidonic acid production, the first step in the eicosanoid synthesis pathway – as associated with this condition in a single affected family. The expression and function of cPLA2α in this disease was investigated, using platelet aggregation stimulated by a downstream product of cPLA2α (Thromboxane A2) as a model.

多聚谷氨酰胺疾病 (Polyglutamine diseases) 是一類在各自的致病基因編碼區的CAG重複編碼擴張造成的顯性遺傳神經退退化疾病。已擴大的CAG訊息核醣核酸 (Expanded CAG transcripts) 在多聚谷氨酰胺蛋白疾病作出細胞毒性作用。從基因減弱篩查中，我發現U2AF50能修飾已擴大的CAG訊息核醣核酸的毒性。並發現U2AF50能與已擴大的CAG訊息核醣核酸作實體互動，能參與已擴大的CAG訊息核醣核酸的核出口 (Nuclear export)。U2AF50的基因減弱增強已擴大CAG訊息核醣核酸在細胞核的累積和毒性。這突出核醣核酸的核出口在多聚谷氨酰胺疾病的重要性，並暗示細胞核是已擴大的CAG訊息核醣核酸毒性的起源地。此外，我鑑定已擴大的CAG訊息核醣核酸在亞細胞的分佈，並發現它們特別累積在核仁 (Nucleolus) 內。核仁是核糖體核醣核酸（rRNA）的轉錄場所。我發現已擴大的CAG訊息核醣核酸減弱rRNA基因啟動子 (rRNA promoter) 的活性並且抑制核糖體核醣核酸的轉錄。 核糖體核醣核酸基因轉錄的抑制，促進核糖體蛋白RpL23和E3連接酶MDM2蛋白作實體互動，從而增強p53的穩定性導。穩定的p53能夠轉移至線粒體 (Mitochondria)。我還發現，線粒體內的p53能打亂Bcl-xL與 Bak的實體互動，導致細胞色素C釋放到細胞質，這導致凋亡蛋白酶 (Caspases) 的活化和細胞凋亡。我的研究，首次證明核仁參與在多聚谷氨酰胺疾病的發病機制中，揭示了在多聚谷氨酰胺疾病中的新致病機制。 / Polyglutamine (polyQ) diseases are a class of dominantly inherited neurodegenerative disorders caused by the expansion of CAG-repeat encoding glutamine within the coding region of the respective disease genes. Expanded CAG transcripts have been reported to contribute to cytotoxicity in polyQ diseases. From a candidate gene knockdown screen, I identified U2AF50 as a modifier of RNA toxicity. U2AF50 has been reported to be involved in RNA nuclear export, and I showed that it interacted specifically with expanded CAG transcripts. Knockdown of U2AF50 expression enhanced nuclear accumulation of expanded CAG transcripts and neurotoxicity. This part of my work highlights the role of RNA nuclear export in polyQ degeneration and implies that the nucleus is a major site for RNA toxicity. In addition, I determined the subcellular distribution of expanded CAG transcripts and found that they particularly localized in the nucleolus. The nucleolus is a critical sub-nuclear compartment for ribosomal RNA (rRNA) transcription. I discovered that expanded CAG transcripts in nucleolus inhibited rRNA transcription by inactivating the rRNA gene promoter activity. Inhibition of rRNA transcription promoted the interaction between ribosomal protein L23 and the ubiquitin E3 ligase MDM2, which led to the stabilization of p53 and its accumulation in mitochondria. I also found that mitochondrial p53 disrupted the interaction between the anti-apoptotic protein, Bcl-xL, and pro-apoptotic protein, Bak, subsequently causing Cytochrome c release, caspase activation, and apoptosis. In summary, my study first describes the involvement of nucleolar function in polyQ pathogenesis and uncovers a new pathogenic mechanism in polyQ diseases. / Detailed summary in vernacular field only. / Tsoi, Ho. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 220-228). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Thesis Committee --- p.ii / Declaration --- p.iii / Acknowledgement --- p.iv / Abstract --- p.v / Abstract in Chinese --- p.vii / List of Abbreviations --- p.viii / List of Figures --- p.x / List of Tables --- p.xvi / Table of Contents --- p.xvi / Chapter 1 --- Introduction / Chapter 1.1 --- Introduction to Polyglutamine Diseases --- p.1 / Chapter 1.1.1 --- Etiology of Polyglutamine Diseases --- p.1 / Chapter 1.1.2 --- Common Features of Different Types of Polyglutamine Disease --- p.1 / Chapter 1.2 --- Pathogenic Mechanisms of Expanded Polyglutamine Proteins --- p.4 / Chapter 1.2.1 --- Pathogenesis of Polyglutamine Diseases --- p.4 / Chapter 1.2.1.1 --- Loss-of-function toxicity --- p.4 / Chapter 1.2.1.2 --- Gain-of-function toxicity --- p.4 / Chapter 1.3 --- Expanded CAG Transcript-mediated Pathogenic Mechanism --- p.6 / Chapter 1.3.1 --- Identification of the Toxic Role of Expanded CAG Transcripts --- p.6 / Chapter 1.3.2 --- Nuclear Foci Formation of Expanded CAG Transcripts and Polyglutamine Pathogenesis --- p.8 / Chapter 1.4 --- Receptor-mediated RNA nuclear export Transport --- p.9 / Chapter 1.4.1 --- Introduction to RNA Nuclear Export --- p.9 / Chapter 1.4.2 --- Regulation of RNA Nucleocytoplasmic Transport and Human Diseases --- p.11 / Chapter 1.5 --- Function of Nucleolus --- p.12 / Chapter 1.5.1 --- Ribosomal RNA Transcription --- p.12 / Chapter 1.5.2 --- Nucleolar Stress and Apoptosis --- p.15 / Chapter 1.6 --- Research Plan --- p.17 / Chapter 1.6.1 --- Project Objective --- p.17 / Chapter 1.6.2 --- Experimental Model --- p.17 / Chapter 1.6.2.1 --- In vivo Drosophila Model --- p.17 / Chapter 1.6.2.2 --- In vitro Cell Culture Model --- p.19 / Chapter 1.6.2.3 --- Transgenic Mouse Model --- p.20 / Chapter 1.6.3 --- Significance of the Present Study --- p.21 / Chapter 2 --- Materials and Methods / Chapter 2.1 --- Molecular Cloning --- p.22 / Chapter 2.1.1 --- Polymerase Chain Reaction (PCR) --- p.22 / Chapter 2.1.2 --- Primers Used for PCR --- p.29 / Chapter 2.1.3 --- Restriction Digestion --- p.31 / Chapter 2.1.4 --- Agarose Gel Electrophoresis --- p.32 / Chapter 2.1.5 --- Preparation of genomic DNA from A Single Adult Fly --- p.34 / Chapter 2.1.6 --- Removal of 5' Phosphate Groups on Linearized Plasmids --- p.35 / Chapter 2.1.7 --- Addition of 5' Phosphate Group to Linker Oligonucleotides --- p.35 / Chapter 2.1.8 --- Ligation Reaction --- p.37 / Chapter 2.1.9 --- Bacterial Transformation --- p.37 / Chapter 2.2 --- Mammalian Cell Culture --- p.40 / Chapter 2.3 --- Drosophila Culture --- p.44 / Chapter 2.4 --- Semi-quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR) --- p.48 / Chapter 2.5 --- Microscopy --- p.51 / Chapter 2.6 --- Protein Sample Preparation and Concentration Measurement --- p.53 / Chapter 2.7 --- Co-immunoprecipitation --- p.57 / Chapter 2.8 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and Immunoblotting --- p.62 / Chapter 2.9 --- Bacterial Protein Purification --- p.65 / Chapter 2.1 --- DNA Methylation Assay --- p.68 / Chapter 2.11 --- Mitochondrial Fraction Isolation --- p.79 / Chapter 3 --- U2 Small Nuclear Riboprotein Auxiliary Factor 50 Modulates Polyglutamine Diseases Toxicity by Altering the Subcellular Localization of Expanded CAG Transcripts in vivo / Chapter 3.1 --- The Nuclear Accumulation of Expanded CAG Transcripts Correlates with the Neurodegeneration in vivo --- p.72 / Chapter 3.1.1 --- Expanded CAG Transcripts Predominantly Localize in the Nucleus in Drosophila Model of Machado-Joseph Disease --- p.72 / Chapter 3.1.2 --- Nuclear Accumulation of Expanded CAG Transcripts Correlates with the Neurodegeneration in an Inducible Model of Machado-Joseph Disease --- p.73 / Chapter 3.1.3 --- Nuclear Accumulation of Expanded CAG Transcripts Correlates with the Neurodegeneration in Inducible DsRed[subscript CAG100] Model. --- p.76 / Chapter 3.1.3.1 --- Expanded CAG Transcripts Induce the Expression of Pro-apoptotic Genes --- p.77 / Chapter 3.1.3.2 --- Co-expression of p35 Suppresses the Toxicity Induced by the Expanded CAG Transcripts --- p.80 / Chapter 3.2 --- A Candidate-gene RNA Interference Approach was Employed to Identify Genetic Factors Involved in Nuclear Export of Expanded CAG Transcripts --- p.80 / Chapter 3.3 --- Confirmation of the Modulatory Effect of U2 Small Nuclear Riboprotein Auxiliary Factor 50 on Machado-Joseph Disease in vivo --- p.84 / Chapter 3.4 --- The Modulatory Effect of U2 Small Nuclear Riboprotein Auxiliary Factor 50 on Different Drosophila Models of Polygultamine Diseases --- p.84 / Chapter 3.5 --- U2 Small Nuclear Riboprotein Auxiliary Factor 50 Specifically Modulates Expanded CAG Transcript-induced Toxicity in vivo --- p.87 / Chapter 3.5.1 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Enhances Expanded CAG Transcript-induced Toxicity --- p.87 / Chapter 3.5.2 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Does Not Modulate Expanded PolyQ Protein-induced Toxicity --- p.89 / Chapter 3.5.3 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Does Not Alter the Expression Level of Expanded CAG Transcripts in vivo --- p.89 / Chapter 3.5.4 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Does Not Modulate the Toxicity in Fragile X syndrome in vivo --- p.91 / Chapter 3.6 --- Over-expression of Human U2 Small Nuclear Riboprotein Auxiliary Factor 65 Does Not Modulate Expanded CAG Transcript-induced Toxicity in Drosophila --- p.91 / Chapter 3.7 --- Expanded CAG Transcripts Does Not Compromise Endogenous Function of U2 Small Nuclear Riboprotein Auxiliary Factor 50 --- p.94 / Chapter 3.8 --- A Correlation between Nucleocytoplasmic Localization of Expanded CAG Transcripts and Its Induced Toxicity --- p.97 / Chapter 3.8.1 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Enriched DsRedCAG100 Transcripts in the Nucleus in vivo --- p.99 / Chapter 3.8.2 --- Knockdown of U2 Small Nuclear Riboprotein Auxiliary Factor 50 Enriched MJDCAG78 Transcripts in the Nucleus in vivo --- p.99 / Chapter 3.9 --- Expanded CAG-repeat on the Transcripts Interact with U2 Small Nuclear Riboprotein Auxiliary Factor 50/65 in vivo and in vitro --- p.102 / Chapter 3.9.1 --- Expanded CAG Transcripts Interact with U2 Small Nuclear Riboprotein Auxiliary Factor 50 in vivo --- p.102 / Chapter 3.9.2 --- Expanded CAG Transcripts Interact with U2 Small Nuclear Riboprotein Auxiliary Factor 65 in vitro --- p.103 / Chapter 3.9.3 --- Expanded CAG Transcripts Directly Interact with U2 Small Nuclear Riboprotein Auxiliary Factor 65 in vitro --- p.103 / Chapter 3.10 --- Identification of Expanded CAG Transcripts Interacting Domain on U2 Small Nuclear Riboprotein Auxiliary Factor 65 --- p.107 / Chapter 3.10.1 --- Generation of Different Myc-tagged U2 Small Nuclear Riboprotein Auxiliary Factor 65 Expression Constructs --- p.107 / Chapter 3.10.2 --- RNA Recognition Motif 3 on U2 Small Nuclear Riboprotein Auxiliary Factor 65 Is Essential for the Interaction with Expanded CAG Transcripts --- p.109 / Chapter 3.11 --- Nuclear RNA Export Factor 1 is Involved in U2 Small Nuclear Riboprotein Auxiliary Factor 65-mediated Nuclear Export of Expanded CAG Transcripts --- p.113 / Chapter 3.11.1 --- The Effect of Full Length U2 Small Nuclear Riboprotein Auxiliary Factor 65 and its Corresponding Deletion Mutants on Nuclear Export of Expanded CAG Transcripts --- p.113 / Chapter 3.11.2 --- Formation of Complexes Composed of Nuclear RNA Export Factor 1/U2 Small Nuclear Riboprotein Auxiliary Factor 65/Expanded CAG Transcripts in HEK293 Cells --- p.115 / Chapter 3.12 --- The Nuclear Export of Expanded CAG Transcripts is Mediated by U2 Small Nuclear Riboprotein Auxiliary Factor 65 and Nuclear RNA Export Factor 1 --- p.120 / Chapter 3.13 --- Aging Compromises the Nuclear Export of Expanded CAG Transcripts in Polyglutamine Disease Mouse Model --- p.123 / Chapter 3.13.1 --- Expanded CAG Transcripts Accumulate in the Nucleus of Polyglutamine Disease Mouse Model --- p.123 / Chapter 3.13.2 --- Expression Level of U2 Small Nuclear Riboprotein Auxiliary Factor 65 Declines with Age in Mice --- p.124 / Chapter 3.14 --- Discussion --- p.127 / Chapter 3.14.1 --- Expanded CAG Transcripts Induce Nuclear Toxicity through a Mechanism Independent on Pathogenic Mechanism Mediated by Other Trinucleotide Repeats Expansion --- p.127 / Chapter 3.14.2 --- Nuclear Accumulation of Expanded CAG Transcripts Leads to Neurodegeneration --- p.128 / Chapter 3.14.3 --- U2 Small Nuclear Riboprotein Auxiliary Factor 50 Modulates Expanded CAG Transcript-induced Toxicity by Mediating the Subcellular Localization of Expanded CAG Transcripts --- p.129 / Chapter 3.14.4 --- U2 Small Nuclear Riboprotein Auxiliary Factor 65 and Nuclear RNA Export Factor 1 Regulate the Nuclear Export of Expanded CAG Transcripts --- p.130 / Chapter 3.14.4.1 --- U2 Small Nuclear Riboprotein Auxiliary Factor 50/65 Interacts with Expanded CAG Transcripts and Mediates the Subcellular localization of Expanded CAG Transcripts --- p.130 / Chapter 3.14.4.2 --- U2 Small Nuclear Riboprotein Auxiliary Factor 65 Requires Nuclear RNA Export Factor 1 to Mediate the Nuclear Export of Expanded CAG Transcripts --- p.131 / Chapter 3.14.4.3 --- Developmental Decline of U2 Small Nuclear Riboprotein Auxiliary Factor 65 Protein Level is a Factor That Leads to Progressive Neurodegeneration in Polyglutamine Diseases --- p.134 / Chapter 4 --- Expanded CAG Transcripts Induce Nucleolar Stress / Chapter 4.1 --- Expanded CAG-repeat Sequence Mediates the Nucleolar Localization of RNA Transcripts in vitro --- p.135 / Chapter 4.1.1 --- Machado-Joseph Disease Cell Model --- p.135 / Chapter 4.1.2 --- EGFPCAG Cell Model --- p.137 / Chapter 4.2 --- Expanded CAG Transcripts Suppress Nucleolar Function in vitro and in vivo --- p.140 / Chapter 4.2.1 --- Expanded CAG Transcripts Suppress Ribosomal RNA Transcription in vivo --- p.140 / Chapter 4.2.1.1 --- Drosophila Model of Machado-Joseph Disease --- p.140 / Chapter 4.2.1.2 --- Drosophila Model of DsRedCAG --- p.142 / Chapter 4.2.1.3 --- Transgenic Mouse Model of PolyQ Disease --- p.142 / Chapter 4.2.2 --- Expanded CAG Transcripts Suppress rRNA Transcription in vitro --- p.145 / Chapter 4.2.2.1 --- Machado-Joseph Disease Patient-derived Fibroblast Cell Lines --- p.145 / Chapter 4.2.2.2 --- Expanded CAG Transcript-expressing HEK293 Cells --- p.145 / Chapter 4.3 --- Expanded CAG Transcripts Disrupt the Interaction between RNA Polymerase I and rRNA Promoter in vitro --- p.148 / Chapter 4.4 --- Expanded CAG Transcripts Disrupt the Interaction between Upstream Binding Factor and Upstream Control Element in vitro and in vivo --- p.149 / Chapter 4.4.1 --- Expanded CAG Transcripts Compromise the Interaction between Upstream Binding Factor and Upstream Control Element in vitro --- p.149 / Chapter 4.4.2 --- Expanded CAG Transcripts Compromise the Interaction between Upstream Binding Factor and Upstream Control Element in vivo --- p.151 / Chapter 4.5 --- Expanded CAG Transcripts Induce DNA Hyper-methylation on Upstream Control Element in vitro and in vivo --- p.151 / Chapter 4.5.1 --- The HpaII-PCR Assay for DNA Methylation --- p.154 / Chapter 4.5.2 --- Expanded CAG Transcripts Lead to DNA Hyper-methylation of Upstream Control Element in vitro --- p.154 / Chapter 4.5.2.1 --- Expanded CAG Transcript-expressing HEK293 Cells --- p.154 / Chapter 4.5.2.2 --- Machado-Joseph Disease Patient-derived Fibroblast Cell Lines --- p.156 / Chapter 4.5.3 --- Expanded CAG Transcripts Lead to DNA Hyper-methylation of Upstream Control Element in vivo --- p.156 / Chapter 4.5.4 --- Expanded CAG Transcripts Disrupt the Regulatory Mechanism of Upstream Control Element Methylation in vitro --- p.159 / Chapter 4.6 --- Expanded CAG Transcripts Induce Nucleolar Stress and Apoptosis --- p.161 / Chapter 4.6.1 --- Expanded CAG Transcripts Induce Nucleolar Stress in vitro and in vivo --- p.162 / Chapter 4.6.1.1 --- Expanded CAG Transcript-expressing HEK293 Cells --- p.162 / Chapter 4.6.1.2 --- Transgenic Mouse Model of PolyQ Disease --- p.162 / Chapter 4.6.2 --- Expanded CAG Transcripts Lead to Stabilization of p53 in vitro and in vivo --- p.165 / Chapter 4.6.2.1 --- Expanded CAG Transcripts Lead to Stabilization of p53 in vitro --- p.165 / Chapter 4.6.2.2 --- Expanded CAG Transcripts Lead to Stabilization of p53 in vivo --- p.167 / Chapter 4.6.3 --- Expanded CAG Transcripts Enrich p53 in Mitochondria in vitro --- p.167 / Chapter 4.6.4 --- Expanded CAG Transcripts Lead to Disruption of interaction between Bcl-xL and Bak by p53 in mitochondria in vitro --- p.169 / Chapter 4.6.5 --- Expanded CAG Transcripts Lead to Release of Cytochrome c in vitro --- p.171 / Chapter 4.6.6 --- Expanded CAG Transcripts Lead to Activation of Caspase 3 in vitro --- p.173 / Chapter 4.7 --- Discussion --- p.176 / Chapter 4.7.1 --- Expanded CAG Transcripts Compromise Nucleolar Function --- p.176 / Chapter 4.7.2 --- Expanded CAG Transcripts Induce Apoptosis via Nucleolar Stress --- p.176 / Chapter 4.7.3 --- The Origin of Nucleolar Stress Induced by Expanded CAG Transcripts --- p.178 / Chapter 5 --- Expanded CAG Transcripts Interact with Nucleolin and Deplete It from Upstream Control Element to Suppress Ribosomal RNA Transcription / Chapter 5.1 --- Nucleolin is an Interacting Partner of Expanded CAG Transcripts --- p.180 / Chapter 5.1.1 --- Nucleolin is Pulled down by S1-tagged Expanded CAG Transcripts in vitro --- p.180 / Chapter 5.1.2 --- Expanded CAG Transcripts Interact with Endogenous Nucleolin in vitro --- p.181 / Chapter 5.1.3 --- Expanded CAG Transcripts Directly Interact with Nucleolin in vitro --- p.184 / Chapter 5.2 --- RNA Recognition Motifs 2 and 3 on Nucleolin Interact with Expanded CAG Transcripts --- p.184 / Chapter 5.2.1 --- Generation of Expression Constructs Carrying Full Length Nucleolin and its Deletion Mutants --- p.184 / Chapter 5.2.2 --- Mapping of Domains on Nucleolin Required for Interacting with Expanded CAG Transcripts --- p.187 / Chapter 5.3 --- Nucleolin Regulates Ribosomal RNA Transcription by Mediating the DNA Methylation of Upstream Control Element in HEK293 Cells --- p.187 / Chapter 5.3.1 --- Nucleolin is involved in Regulating the Interaction between Upstream Binding Factor and Upstream Control Element in vitro --- p.191 / Chapter 5.3.2 --- Nucleolin is Involved in Regulating DNA Methylation Level of Upstream Control Element in vitro --- p.191 / Chapter 5.3.3 --- Nucleolin Associates with Upstream Control Element in vitro --- p.194 / Chapter 5.4 --- Expanded CAG Transcripts Deplete Nucleolin from Upstream Control Element in vitro and in vivo --- p.194 / Chapter 5.4.1 --- Expanded CAG Transcripts Compete Nucleolin with Upstream Control Element in vitro --- p.197 / Chapter 5.4.2 --- Expanded CAG Transcripts Compete Nucleolin with Upstream Control Element in vivo --- p.197 / Chapter 5.4.3 --- Expanded Polyglutamine Proteins does not Interact with Nucleolin in vitro --- p.200 / Chapter 5.5 --- Over-expression of Nucleolin Counteracts the Effect of Expanded CAG Transcripts on Ribosomal RNA Transcription in vitro --- p.200 / Chapter 5.5.1 --- Over-expression of Nucleolin Restores the Methylation Level of Upstream Control Element in Dose-dependent Manner in vitro --- p.200 / Chapter 5.5.1.1 --- The Dosage Effect of Nucleolin on DNA Hyper-methylation of Upstream Control Element Induced by Expanded CAG Transcripts in vitro --- p.202 / Chapter 5.5.1.2 --- Does-dependent Expression of Nucleolin in vitro --- p.202 / Chapter 5.5.1.3 --- The Effect of Nucleolin Over-expression on DNA Hyper-methylation of Upstream Control Element Induced by Expanded CAG Transcripts is Dose-dependent in HEK293 cells --- p.205 / Chapter 5.5.2 --- Over-expression of Nucleolin Does Not Alter the Expression Level of Expanded CAG Transcripts in vitro --- p.205 / Chapter 5.5.3 --- Over-expression of Nucleolin Relieves the Nucleolar Stress induced by Expanded CAG Transcripts in vitro --- p.208 / Chapter 5.6 --- Discussion --- p.212 / Chapter 5.6.1 --- The Physical Interaction between Expanded CAG Transcripts and Nucleolin Leads to Suppression of Ribosomal RNA Transcription --- p.212 / Chapter 5.6.2 --- Expanded CAG Transcripts Deprive Upstream Control Element of Nucleolin to Induce Toxicity --- p.212 / Chapter 5.6.3 --- Nucleolin Suppresses Expanded CAG Transcript-induced Cell Death --- p.213 / Chapter 5.6.4 --- Expanded CAG Transcripts Employ both p53-dependent and p53-independent pathways to Induce Cell Death --- p.214 / Chapter 6 --- Concluding Remarks --- p.216 / References --- p.220

A anemia falciforme (AF) é a doença hereditária monogênica mais prevalente no Brasil, caracterizada pelo alto índice de morbimortalidade. Uma mutação de ponto no gene da globina beta da hemoglobina é a causa da doença. Características genéticas dos indivíduos além da possível heterogeneidade das moléculas associadas à hemólise e vasculopatia são responsáveis por uma variedade de manifestações e complicações clínicas. Os tratamentos disponíveis atualmente consistem no objetivo de amenizar as manifestações clínicas e reduzir o número de crises para uma melhor qualidade de vida destes pacientes. Considerando a importância dos MicroRNAs na regulação da expressão gênica e na fisiopatologia de diversas doenças, este estudo tem por objetivo a elucidação do mecanismo de ação destes potenciais reguladores na fisiopatologia da AF. Caracteriza-se por um estudo prospectivo comparativo, do tipo de pesquisa clínica transversal. Foram incluídos neste estudo 50 indivíduos, dos quais, 25 indivíduos normais sem a patologia, doadores do banco de sangue do Hospital de Clinicas de Porto Alegre (HCPA), e 25 pacientes homozigóticos SS, em acompanhamento médico no Centro de Referência em Doença Falciforme do HCPA A obtenção dos dados se deu pela reação da polimerase em cadeia em tempo real, com a seleção de quatro microRNAs candidatos selecionados de acordo com a predição de suas funções alvo já disponíveis na literatura (hsa-mir-15a, hsa-mir-210, hsa-mir-144 e hsa-mir-223). Foram comparadas as diferenças dos perfis de expressão de cada microRNA com a média do grupo controle, além das correlações entre as variáveis hematológicas, bioquímicas e manifestações clínicas, com a finalidade de avaliar a influência entre as variáveis positivamente ou negativamente. Resultados: Três dos quatro microRNAs tiveram seus níveis de expressão estatisticamente significativos em relação ao grupo controle (mir- 15a, mir-210 e mir-223). As correlações positivas identificadas foram do microRNA 15a com o microRNA 144, do microRNA 210 com o microRNA 223, além do microRNA 223 com as manifestações de úlceras. As correlações negativas identificadas foram do microRNA 15a em relação às plaquetas e síndrome torácica aguda, e do microRNA 144 em relação aos reticulócitos. Conclusão: Tal conhecimento poderá possibilitar estabelecer novos tratamentos e possíveis abordagens terapêuticas através do controle da expressão de genes específicos e sua interação direta com RNAs alvo. / Sickle cell anemia (FA) is the most prevalent monogenic hereditary disease in Brazil; it is characterized by variable and sometimes severe symptoms and high morbi-mortality. A point mutation of the beta globin gene is a cause of the disease. Genetic characteristics of individuals and the heterogeneous possibility of molecules associated with hemolysis and vasculopathy are responsible for the variability of clinical manifestations. The available treatments are aimed at mitigating the clinical manifestations and reducing the number of crisis for a better quality of life of these patients. This study aims to elucidate the mechanism of action of regulatory molecules in the pathophysiology of FA. It is characterized by a prospective comparative study, type of cross-sectional clinical research. Fifty individuals, 25 normal subjects, from the blood bank of the Hospital de Clínicas de Porto Alegre (HCPA), and 25 homozygous SS patients, from the Reference Center on Sickle Disease of HCPA. Real-time polymerase chain reaction measuring four microRNAs selected according to the predictions of their target functions in the literature (hsa-mir-15a, hsa-mir-210, Hsa-mir -144 and hsa-mir-223) Differences in the expression profiles of each microRNA with a mean of the control group were compared, as well as the correlations between hematological, biochemical and clinical manifestations, with the purpose of evaluating positive or negative influence between variables. Results: Three of the four microRNAs had their expression levels statistically significant in relation to the control group (mir- 15a, mir-210 and mir-223). A positive correlation was identified between microRNA 15a with the microRNA 144, the microRNA 210 with the microRNA 223, and microRNA 223 with positively correlated with leg ulcers. As for negative correlation we identified for microRNA 15a in relation to platelets and acute thoracic syndrome, and for microRNA 144 in relation to reticulocytes. Conclusion: Such knowledge may enable new treatments and possible therapeutic approaches by controlling the expression of specific genes and their direct interaction with target RNAs.

Relatively new technology called optical coherence tomography allows direct and non invasive in vivo imaging of retinal anatomy in human subjects. There are several interesting applications of this technique, including testing models relating retinal anatomy (structural measures) to behavioral thresholds of light sensitivity (functional measures). In addition to potentially improving our understanding of this relationship and how it changes during the course of neurodegenerative diseases of the eye such as glaucoma, analyses of these data may allow for early identification of glaucomatous neural damage in the retina, which has considerable clinical relevance. Here, the underlying assumptions and generalization of a previously developed model of the structure function relationship in glaucoma was tested by applying this model to a novel dataset. This model has been influential in the literature because it purports to accurately estimate the number of retinal ganglion cells; however, it was found to have several questionable assumptions and did not generalize well. Next, a new method of estimating the number of retinal ganglion cells from optical coherence tomography was developed. This method uses fewer and more defensible assumptions and demonstrated good agreement with independent histological estimates. Finally, a new method, using computer simulations, was developed for analyzing data from optical coherence tomography in order to distinguish early signs of glaucomatous changes in retinal anatomy from variability in structure among healthy retinas, and this method performed better than previously published techniques.

Cardiovascular diseases are major causes of morbidity and mortality in Western-style populations. Atherosclerosis and Abdominal Aortic Aneurysms (AAAs) are two prevalent vascular diseases that may progress without symptoms and contribute to acute cardiovascular events such as stroke and AAA rupture, which are consistently among the leading causes of death worldwide. The imaging methods used in the diagnosis of these diseases, have been reported to present several limitations. Given that both are associated with mechanical changes in the arterial wall, imaging of the arterial mechanical properties may improve early disease detection and patient care. Pulse wave velocity (PWV) refers to the velocity at which arterial waves generated by ventricular ejection travel along the arterial tree. PWV is a surrogate marker of arterial stiffness linked to cardiovascular mortality. The foot-to-foot method that is typically used to calculate PWV suffers from errors of distance measurements and time-delay measurements. Additionally, a single PWV estimate is provided over a relatively long distance, thus inherently lacking the capability to provide regional arterial stiffness measurements. Pulse Wave Imaging (PWI) is a noninvasive, ultrasound-based technique for imaging the propagation of pulse waves along the wall of major arteries and providing a regional PWV value for the imaged artery. The aim of this work was to enable PWI to provide more localized PWV and stiffness measurements within the imaged arterial segment and to further extend it into a 2-D and 3-D technique for the detection and monitoring of focal vascular disease at high temporal and spatial resolution. The improved modality was integrated with blood flow imaging modalities aiming to render PWI a comprehensive methodology for the study of arterial biomechanics in vivo. Spatial information was increased with the introduction of piecewise PWI. This novel technique was used to measure PWV within small sub-regions of the imaged vessel in murine aneurysmal (n = 8) and atherosclerotic aortas (n = 11) in vivo. It provided PWV and stiffness maps while capturing the progressive arterial stiffening caused by atherosclerosis. PWI was further augmented with a sophisticated adaptive algorithm, enabling it to optimally partition the imaged artery into relatively homogeneous segments, automatically isolating arterial stiffness inhomogeneities. Adaptive PWI was validated in silicone phantoms consisting of segments of varying stiffness and then tested in murine aortas in vivo. Subsequently, the conventional tradeoff between spatial and temporal resolution was addressed with a plane wave compounding implementation of PWI, allowing the acquisition of full field of view frames at over 2000 Hz. A GPU-accelerated PWI post-processing framework was developed for the processing of the big bulk of generated data. The parameters of coherent compounding were optimized in vivo. The optimized sequences were then used in the clinic to assess the mechanical properties of atherosclerotic carotids (n=10) and carotids of patients after endarterectomy (n=7), a procedure to remove the plaque and restore blood flow to the brain. In the case of atherosclerotic patients undergoing carotid endarterectomy, the results were compared against the histology of the excised plaques. Investigation of the mechanical properties of plaques was also conducted for the first time with a high-frequency transducer (18.5 MHz). Additionally, 4-D PWI was introduced, utilizing high frame rate 3-D plane wave acquisitions with a 2-D matrix array transducer (16x16 elements, 2.5 MHz). A novel methodology for PWV estimation along the direction of pulse wave propagation was implemented and validated in silicone phantoms. 4-D PWI provided comprehensive views of the pulse wave propagation in a plaque phantom and the results were compared against conventional PWI. Finally, its feasibility was tested in the carotid arteries of healthy human subjects (n=6). PWVs derived in 3-D were within the physiological range and showed good agreement with the results of conventional PWI. Finally, PWI was integrated with flow imaging modalities (Color and Vector Doppler). Thus, full field-of-view, high frame-rate, simultaneous and co-localized imaging of the arterial wall dynamics and color flow as well as 2-D vector flow was implemented. The feasibility of both techniques was tested in healthy subjects (n=6) in vivo. The relationship between the timings of the flow and wall velocities was investigated at multiple locations of the imaged artery. Vector flow velocities were found to be aligned with the vessel’s centerline during peak systole in the common carotid artery and interesting flow patterns were revealed in the case of the carotid bifurcation Consequently, with the aforementioned improvements and the inclusion of 3-D imaging, PWI is expected to provide comprehensive information on the mechanical properties of pathological arteries, providing clinicians with a powerful tool for the early detection of vascular abnormalities undetectable on the B-mode, while also enabling the monitoring of fully developed vascular pathology and of the recovery of post-operated vessels.

Polyglutamine (polyQ) diseases describe a group of late-onset progressive neurodegenerative disorders which are caused by the CAG triplet repeat expansion in the coding region of disease genes. Such expansions result in expanded polyQ tracts in the disease proteins which confer neurotoxicity. To date, nine such diseases are reported including Huntington's disease and several types of spinocerebellar ataxias. Misfolding of polyQ proteins and formation of intracellular SDS-insoluble protein aggregates are closely associated with the toxicity of these diseases. In particular, impairment of the ubiquitin-proteasome system (UPS) which is responsible for protein degradation has been observed in polyQ diseases. Recently, ubiquitin ligases, which govern substrate specificity of the UPS, have gained huge attention in polyQ disease pathogenesis studies. In humans, cullin (Cul) proteins, including Cul1, 2, 3, 4 & 5, are integral components of a group of ubiquitin ligases called cullin- RING ubiquitin ligases (CRLs). Each CRL displays distinct substrate specificity through specific substrate receptors. Cullin proteins are evolutionarily conserved and Cul orthologues are found in the Drosophila genome. In the present study, it was found that individual Culs displayed distinct effects on polyQ pathogenesis in Drosophila polyQ models. Particularly, it was found that Cul1 modulated polyQ-induced toxic phenotype. This modification was accompanied with an alteration in the ubiquitination level and SDS-solubility properties of expanded polyQ protein. Through genetic interaction studies and biochemical analyses, it is suggested that Cul1-based CRL specifically targets SDS-insoluble species of expanded polyQ protein for ubiquitination via selective recognition by CG2010 substrate receptor. On the other hand, it was found that expanded polyQ protein induced accumulation of CRL substrates in cells. Current data support a hypothesis that polyQ protein would impair the ubiquitin ligase activity of CRLs upon expansion of the polyQ domain, through interfering with neddylation of cullin and other uncharacterized mechanisms. Taken together, the present study identifies Cul1-CRL as a novel E3 ligase that modifies polyQ toxicity through modulating ubiquitination of expanded polyQ protein, and demonstrates a pathological mechanism by expanded polyQ protein through impairing CRL activity. These findings would lead to a better understanding of polyQ pathogenesis and give insights on developing treatments against polyQ diseases. / Wong, Kam Yan. / Adviser: Ho-Yin Edwin Chan. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 260-273). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Background: Asthma is characterized by chronic airway inflammation in which leukocytes are attracted into the inflamed airway under the influence of chemokines. Molecular studies and allergen bronchoprovocation suggested that chemokines such as thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), eotaxin and regulated upon activation normal T-cell expressed and secreted (RANTES) were involved in the airway responses to allergen exposure. / Conclusions: Chemokines are important mediators in the pathophysiology of asthma and atopy. TARC in plasma and MDC in EBC appear to be useful biomarkers for assessing childhood asthma. Besides, MDC concentrations in UCB may predict the susceptibility to develop wheezing during infancy. / Methods: Asthmatic patients, non-allergic controls and healthy singleton newborns were recruited from attendants of a university teaching hospital. Atopy-related chemokines in peripheral blood and EBC were measured by enzyme-linked immunosorbent assays. Genomic DNA from asthmatics and controls was genotyped by restriction fragment length polymorphism to characterize single nucleotide polymorphisms (SNPs) in the genes encoding TARC, RANTES, interleukin-13 and CD14. / Objectives: This thesis investigated the relation between chemokines and asthma and atopy by: (a) measuring their concentrations in peripheral blood and exhaled breath condensate (EBC); (b) performing case-control association studies for genes encoding atopy-related chemokines and related molecules; and (c) analyzing chemokines in umbilical cord blood (UCB) in relation to wheezing phenotypes during infancy. / Results: Plasma TARC concentrations were higher in children with chronic asthma than controls, and also correlated with plasma total IgE. Among children with asthmatic exacerbation, plasma TARC concentrations showed inverse correlation with peak expiratory flow rates at presentation. When measured in EBC, MDC but not TARC or eotaxin was higher in asthmatics than controls. In our genetic association studies, SNPs in IL13, RANTES and TARC were associated with serum total and/or allergen-specific IgE. TARC C-431T was also linked to peripheral eosinophilia. However, none of these polymorphisms was associated with physician-diagnosed asthma. Interestingly, C-159T in CD14 was also associated with serum total IgE, but only among atopic asthmatic children. In the last part involving 124 singleton healthy newborns, MDC concentrations in UCB were significantly increased in newborns who wheezed during infancy. / Leung Ting-fan. / Adviser: Gary W.K. Wong. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 196-231). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

Mast cells are pivotal effector cells in the pathogenesis of allergic and inflammatory diseases. Activation of FcepsilonRI in mast cells by antigen initiates a complex series of biochemical events leading to the release and synthesis of myriads of chemical mediators and cytokines. Adenosine is an endogenous nucleoside formed from cleavage of AMP by the enzyme 5'-nucleotidase. It exerts modulating effects in a large number of cellular systems by acting through four distinct subtypes of adenosine receptors (A1, A 2A, A2B and A3) which belong to the G-protein-coupled receptor (GPCR) family. Increasing evidence have been provided to show that adenosine plays a role in the pathophysiology of asthma through a mast cell dependent mechanism. / Pharmacological studies using specific adenosine agonists and antagonists revealed that A1 receptor was responsible for the potentiating effect of adenosine with the involvement of the pertussis toxin-sensitive Galphai-protein. Conversely, inhibition of HCMC activation was mediated by A2B receptor and was accompanied by the elevation of cAMP level suggesting the participation of Galphas-protein. / Taken together, the current studies explored the dual effect of adenosine on human mast cells activation which enhanced our understanding of adenosine receptor biology. The effectiveness of adenosine in modulating the important mast cell activation pathways definitely facilitates the rational exploitation of these receptors as therapeutic targets that could be converted into clinical benefits for asthmatic patients. / To better characterize the effect of adenosine on human mast cell under asthmatic environment, we incubated HCMC under different inflammatory condition found in asthmatic, including toll-like receptor (TLR) ligands and inflammatory cytokines. Functional studies on mediator release from HCMC indicated that out of all tested substances, Peptidoglycan (PGN) pre-incubation enhanced the IL-8 synthesis from HCMC in response to low concentration of adenosine (10-9--10-7 M). / We also investigated the action of adenosine on key signal transduction pathways involved in mast cells activation. Study on intracellular calcium concentration ([Ca2+]i) revealed that low concentration of adenosine (10-8 M) through activation of PI3Kgamma significantly enhanced Ca2+ influx. In contrast, high concentration of adenosine at 10-4 M substantially inhibited [Ca2+] i in response to anti-IgE. Furthermore, investigation on intracellular signaling molecules provided evidence that adenosine at concentrations over 10-6 M does-dependently inhibited the immunoglobulin (IgE)-dependent activation of ERK, JNK or NF-kappaB pathways, whereas enhancement of IkappaBalpha was found on low concentration of adenosine. The above observation help to justify the dual action of adenosine on anti-IgE-induced mediators release from HCMC. Our investigation further suggested that adenosine may inhibit HCMC activation through a novel cAMP-dependent, but PKA- and EPAC-independent, signaling pathway. / We generated human cultured mast cells (HCMC) from human buffy coat and confirmed the expression of all adenosine receptor subtypes in them. We showed that adenosine alone did not induce HCMC degranulation and cytokine release. However, adenosine and the non-selective agonist, 5'-N-Ethylcarbox-amidoadenosine (NECA), produced a biphasic response on anti-IgE induced mast cell activation. An enhancement of HCMC activation was observed with low concentrations of adenosine and NECA (10-9--10-7 M), whereas a predominant inhibitory action was observed at concentrations higher than 10-6 M. / Yip, Kwok Ho. / Adviser: Alaster H.Y. Lau. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 237-263). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

As CFTR plays an important role in HCO3- transport, and HCO3- sensitive soluble adenylyl cyclase (sAC) has been shown to be largely responsible for the cAMP production in spermatogenetic cells, we hypothesized that CFTR-mediated HCO3- transport was important to spermatogenesis via sAC pathway in spermatogenetic and Sertoli cells. Using intracellular pH measurement, we demonstrated that CFTR is involved in HCO3- transport in Sertoli cells. RT-PCR results showed that increased HCO3- concentrations in the culture medium resulted in upregulation of CFTR expression. The results also showed that the intracellular cAMP level in Sertoli cells increased as the extracellular HCO3- concentration increased. HCO3- also caused phosphorylation of the cAMP response element binding (pCREB) proteins transcription factor on serine 133, a modification known to be required by Sertoli cells to support spermatogenesis. This phosphorylation could be inhibited by CFTR inhibitor, further lending support to the notion that CFTR is important for HCO3- transport in Sertoli cells, leading to HCO3- dependent events that are important for spermatogenesis. / CFTR is known to be widely expressed in epithelial cells of male reproductive tracts, but its expression in spermatogenic cells is less well known. We first confirmed the expression of CFTR in spermatogenic cells and mature sperm in rodents. Our study thus focused on the important role of CFTR in the processes related to male fertility including spermatogenesis and sperm capacitation. / Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel, mutations of which cause cystic fibrosis, a disease characterized by defective Cl- and HCO3- transport. While over 95% of CF male patients are infertile because of congenital bilateral absence of the vas deferens (CBAVD), the question whether CFTR mutations are involved in other forms of male infertility is under intense debates. / In conclusion, our study has demonstrated the role of CFTR in male reproductive system. We have further elucidated its possible physiological role and the underlying molecular mechanisms. These studies may pave the way for the development of method strategies for diagnosis and treatment of CFTR related infertility in male. / Our study also detected CFTR in both human and mouse sperm. CFTR inhibitor or antibody significantly reduced sperm capacitation, and the associated HCO 3--dependent events including increases in intracellular pH, cAMP production and membrane hyperpolarization. The fertilizing capacity of the sperm obtained from heterozygous CFTR mutant mice is also significantly lower as compared to that of the wild type. These results suggest that CFTR in sperm may be involved in the transport of HCO3- important for sperm capacitation and that CFTR mutations with impaired CFTR function may lead to reduced sperm fertilizing capacity and male infertility other than CBAVD. / We further demonstrated the physiological role of CFTR in spermatogenesis using CFTR knockout mice as an in vivo model. Although TUNNEL staining showed normal percentage of apoptotic cells in seminiferous tubules, Cftr -/- mice had spermatogenetic defects in histology section and fewer number of mature sperm compared with wild type (WT) mice. Consistent with the proposed role of CFTR in spermatogenesis, RT-PCR and Western blot results showed reduced expression of spennatids specific gene, Protamine 1, Protamine 2, and CREM, which have been known to be involved in the process of spermatogenesis, in Cftr-/- mice. / Xu, Wenming. / "January 2008." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4506. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 121-138). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Polyglutamine disease is a class of neurodegenerative diseases, which is manifested by the atrophy of nervous system that results in dementia and/or motor dysfunction. The major pathological characteristics include progressive loss of neuronal cells as well as the appearance of insoluble nuclear inclusions in degenerating neuronal cells. Polyglutamine disease is caused by CAG triplet expansion in the genome. When translated, such expansion leads to the formation of expanded polyglutamine domain within the respective disease proteins and promotes abnormal protein conformational changes. Owing to their misfolded nature, the expanded polyglutamine proteins form insoluble nuclear inclusions. These insoluble nuclear inclusions are heterogeneous in nature, in which polyglutamine protein and molecular chaperones are the recruited components. All eukaryotic cells express molecular chaperones which function to mediate the proper folding of proteins. The recruitment of molecular chaperones into nuclear inclusions that contain misfolded triplet-expanded proteins strongly suggests the involvement of molecular chaperones in polyglutamine disease progression. It has been shown that over-expression of molecular chaperones in polyglutamine disease models can lead to a suppression of polyglutamine toxicity and a concomitant increase in the solubility of disease proteins, i.e. the solubility of polyglutamine disease protein is related to its toxicity. Intrigued by these observations, I aimed at elucidating the mechanism of polyglutamine disease pathogenesis by first studying the cellular regulation of endogenous chaperone expression in neurodegeneration in a transgenic Drosophila model of polyglutamine disease. A biphasic regulation of Hsp70 expression was observed, which the regulation was at the transcription level. Moreover, over-expression of Hsp70 could alter the endogenous Hsp70 protein and mRNA level of polyglutamine disease fly model. The study may help the understanding of how the chaperone expression is regulated under the effects of polyglutamine expression and thus to find out the mechanism of pathogenesis. In addition, cellular proteins that change in solubility other than disease protein will also be identified. Small heat shock proteins, glutathione S transferase and alpha 4 proteasome subunit, etc., showed change in solubility or expression by 2D gel electrophoresis analysis. Identifying the proteins that change in solubility or expression may help the finding of the interplay of proteins and thus the pathways involve in the mechanism of polyglutamine disease pathogenesis. Understanding pathogenic pathways can give ideas on how polyglutamine lead to the disease, up- or down-regulation of those protein interplays may provide direction and therapeutic candidates to suppress polyglutamine disease. / Huen Ngar Yee. / "September 2006." / Advisers: Ho Yin Chan; Siu Kai Kong. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1465. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 134-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.