Tsoi Lo Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 99-109). / Abstracts in English and Chinese. / Acknowledgements --- p.I / Abstract --- p.II / Abstract in Chinese --- p.III / List of Abbreviations --- p.IV / List of Figures --- p.V / List of Tables --- p.VI / Table of Contents --- p.VII / Chapter Chapter 1 : --- Introduction / Chapter 1.1. --- Apolipoprotein and Lipoprotein Metabolism --- p.1 / Chapter 1.2. --- Molecular Information of ApoE --- p.2 / Chapter 1.3. --- Tissue Distribution of ApoE --- p.2 / Chapter 1.4. --- Functions of ApoE --- p.4 / Chapter 1.5. --- Genetic Polymorphism of ApoE --- p.7 / Chapter 1.6. --- Protein Structure and Characteristics of ApoE Isoforms --- p.9 / Chapter 1.7. --- Plasma and Cellular Expression Level of ApoE Isoforms --- p.12 / Chapter 1.8. --- Association between ApoE Isoforms and Plasma Lipid Profiles --- p.13 / Chapter 1.9. --- ApoE Polymorphisms and Pathophysiological Conditions / Chapter 1.9.1. --- Type III Hyperlipoproteinemia (Type III HLP) --- p.14 / Chapter 1.9.2. --- Alzheimer's Disease --- p.15 / Chapter 1.9.3. --- Atherosclerosis / Chapter 1.9.3.1. --- Atherosclerosis - An Inflammatory Process --- p.15 / Chapter 1.9.3.2. --- Role of ApoE in Atherosclerosis --- p.18 / Chapter (a) --- Functions Associated to Lipid Metabolism --- p.19 / Chapter (b) --- Functions Independent to Lipid Metabolism --- p.20 / Chapter 1.9.3.3. --- TNF-α and IL-6 in Atherosclerosis --- p.25 / Chapter 1.10. --- Macrophage Cytokine Expression and MAPKs / Chapter 1.10.1. --- Organization of MAPKs Signaling Pathway --- p.26 / Chapter 1.10.2. --- Lipopolysaccharide and MAPKs in Macrophage Cytokine Expression --- p.28 / Chapter 1.10.3. --- Regulation of Macrophage Cytokine Expression / Chapter 1.10.3.1. --- ERK1/2 and p38 MAPK Pathway --- p.30 / Chapter 1.10.3.2. --- Arachidonic Acid Metabolism --- p.30 / Chapter 1.11. --- Aim and Hypothesis --- p.31 / Chapter Chapter 2 : --- Materials and Methods / Materials / Chapter 2.1 --- Culture of ApoE-isoform-expressing J774A.1 Macrophage Cell Line --- p.32 / Chapter 2.2 --- RNA Extraction and Reverse Transcription-Polymerase Chain Reaction (RT-PCR) --- p.33 / Chapter 2.3 --- Protein Extraction and Quantification --- p.37 / Chapter 2.4 --- Enzyme-linked Immunosorbent Assay (ELISA) --- p.38 / Chapter 2.5 --- Western Blotting --- p.39 / Chapter 2.6 --- LPS Treatment --- p.42 / Chapter 2.7 --- MAPK Inhibitor Experiment --- p.43 / Methods / Chapter 2.8 --- Study on the Effect of Endogenously Expressed ApoE Isoforms on Macrophage Cytokine Secretion / Chapter 2.8.1. --- Establishment of ApoE-isoform-expressing Macrophages --- p.44 / Chapter 2.8.2. --- Semi-quantification of ApoE mRNA Level by RT-PCR / Chapter 1) --- Isolation of Total RNA --- p.45 / Chapter 2) --- RT-PCR --- p.46 / Chapter 2.8.3. --- Determination of ApoE Protein Expression Level by ELISA and Western Blot --- p.47 / Chapter 1) --- Quantification of Total Proteins --- p.48 / Chapter 2) --- ELISA --- p.48 / Chapter 3) --- Western Blot --- p.49 / Chapter 2.8.4. --- LPS Treatment --- p.51 / Chapter 2.8.5. --- MEK1/2 Inhibitor Experiment --- p.53 / Chapter 2.8.6. --- p38 Inhibitor Experiment --- p.54 / Chapter 2.9 --- Study on the Effect of Exogenous ApoE Isoform on Macrophage Cytokine Secretion --- p.55 / Chapter 2.10 --- Statistical Analysis --- p.55 / Chapter Chapter 3: --- Results / Changes of Inflammatory Properties Associated with Endogenous ApoE Isoform Expression in Macrophages / Chapter 3.1 --- Characterization of ApoE-isoform-expressing Macrophages --- p.56 / Chapter 3.1.1. --- Cell Lines with Stable Expression of ApoE Isoforms --- p.56 / Chapter 3.2 --- Cell Morphology Study --- p.58 / Chapter 3.3 --- Changes of IL-6 and TNF-α Secretion Associated with Endogenous ApoE Isoforms Expression / Chapter 3.3.1. --- In the Presence of Lipoproteins --- p.60 / Chapter 3.3.2. --- Serum/Lipoprotein-independent Effects of ApoE Isoforms --- p.63 / Chapter 3.4 --- The Effects of Endogenous ApoE Isoform Expression on the Activities of MAPK Signaling Pathways / Chapter 3.4.1. --- Study on the Activation Status and Expression of MAPKs --- p.66 / Chapter 1) --- ERK1/2 MAPK Pathway --- p.66 / Chapter 2) --- p38 MAPK Pathway --- p.69 / Chapter 3.4.2. --- IL-6 and TNF-a Secretion Among ApoE Isoforms in the Presence of MEK1/2 mhibitor --- p.72 / Chapter 3.4.3. --- IL-6 and TNF-α Secretion Among ApoE Isoforms in the Presence of p38 Inhibitor --- p.75 / Chapter Chapter 4 : --- Discussions / Chapter 4.1. --- Mouse Peritoneal Macrophage Cell Line J774A.1 as Cell Model --- p.79 / Chapter 4.2. --- Inflammatory Properties Associated with Endogenous ApoE Isoform Expression in Macrophages / Chapter 4.2.1. --- Expression Level of ApoE Isoform Transgenes in Mouse Peritoneal Macrophages --- p.80 / Chapter 4.2.2. --- Macrophage Activation by LPS --- p.81 / Chapter 4.2.3. --- Effect of Endogenous ApoE Isoform Expression on Cytokine Secretion and Signal Transduction in Macrophages --- p.82 / Chapter 4.3. --- Conclusions and Future Prospects / Chapter 4.3.1. --- Conclusions --- p.90 / Chapter 4.3.2. --- Future Prospects --- p.91 / Chapter Chapter 5 : --- Appendices / Chapter 5.1 --- Changes of Inflammatory Properties of Macrophages Supplemented with Exogenous ApoE Isoforms / Chapter 5.1.1. --- Changes of IL-6 and TNF-a Secretion in Macrophages Supplemented with Exogenous ApoE Isoforms --- p.92 / Chapter 5.1.2. --- Changes of Signal Transduction in Macrophages Supplemented with Exogenous ApoE Isoforms / Chapter 5.1.2.1. --- Study on the Activation Status and Expression of MAPKs / Chapter 1) --- ERK1/2 MAPK Pathway --- p.95 / Chapter 2) --- p38 MAPK Pathway --- p.97 / Chapter Chapter 6: --- Bibliography --- p.99

A corticoterapia tem sido utilizada frequentemente nas éguas suscetíveis. O uso de isuflupredona melhora a taxa de prenhez e altera o perfil proteico do líquido endometrial em relação a éguas não tratadas. A utilização de dexametasona diminui o acúmulo de líquido pós-cobertura, reduz o edema do útero, porém, desconhecem-se seus efeitos no perfil proteico do líquido endometrial. O objetivo do presente estudo foi analisar o efeito da dexametasona em éguas suscetíveis à endometrite persistente póscobertura sobre perfil proteico do líquido endometrial na presença ou ausência de infecção. Nove éguas suscetíveis foram utilizados, com idade entre 7 a 30 anos. Após a verificação dos sinais de estro as éguas foram submetidas a quatro tratamentos: (C) éguas não receberam nenhum tipo de tratamento e serviram como controle; (D) éguas receberam 40mg de dexametasona (IV), no momento da cobertura, com coleta da amostras após 6 horas, (I-6 e I-24) infusão intra-uterina de 1 x 109 de S. zooepidemicus/mL, com coleta da amostra após 6 e 24 horas; (I/D-6 e I/D-24) infusão intra-uterina de 1 x 109 S. zooepidemicus/mL e administração de 40mg de dexametasona (IV), com coleta da amostra após 6 e 24 horas. Todas as éguas foram submetidas a todos os tratamentos. As amostras foram coletadas e submetidas à eletroforese bidimensional para separação proteica e espectrometria de massa para a identificação das bandas proteicas relevantes. A corticoterapia provocou alteração na proteômica do líquido endometrial de éguas suscetíveis, caracterizada pelo aumento (TTR) e/ou diminuição (ApoA1) na densidade óptica de proteínas da fase aguda da inflamação. Conclui-se que a utilização da dexametasona em éguas com e sem presença de infecção altera a proteômica do fluido endometrial de éguas suscetíveis. Sugere-se que a dosagem ou a frequência de aplicação da dexametasona deva ser aumentada. / Corticotherapy has often been used in susceptible mares. The use of isuflupredona improves pregnancy rate and alters the protein profile of the endometrial fluid in relation to untreated mares. The use of dexamethasone decreases the post breeding fluid accumulation, reduces the uterine edema, however is unaware of its effects on the protein profile of endometrial fluid. The aim of the present study was analyze the effect of dexamethasone in mares susceptible to post-breeding persistent endometritis on the protein profile of endometrial fluid in the presence or absence of infection. Nine susceptible mares were used, aged 7-30 years old. After checking the signs of estrus, mares were subjected to four treatments: (C) mares received no treatment and served as controls; (D) mares received 40 mg of dexamethasone at breeding time, with collection of samples after 6 hours; (I-6 and I-24) intrauterine infusion of 1 x 109 S. zooepidemicus/ml and the sample was collected after 6 and 24 hours; (I/D-6 and I/D-24) intrauterine infusion of 1 x 109 S. zooepidemicus/ml and 40 mg of dexamethasone administration, collecting the sample after 6 and 24 hours. All of the mares were subjected to all treatments. Samples were collected and subjected to two-dimensional electrophoresis for protein separation and mass spectrometry for the identification of relevant protein bands. Corticotherapy resulted in alteration of the protein profile of the endometrial fluid of susceptible mares, characterized by an increase (TTR) and/or decrease (ApoA1) in optical density of the acute phase of proteins of inflammation. We conclude that the use of dexamethasone in mares with and without the presence of infection alters the protein profile of endometrial fluid of susceptible mares. It is suggested that the dosage or frequency of application of dexamethasone should be increased.

Despite the tremendous advances of the last century, the cause of Alzheimer disease (AD) remains unclear. Genetic analysis of families with Alzheimer disease has revealed a disease-associated variant of the APOE gene, which encodes apolipoprotein E, a transporter of lipids in the blood and central nervous system. The effect of the AD-associated isotype, termed ApoE-E4, on disease risk has been validated, though it is unclear by what mechanism apoE-E4 confers AD risk. Mitochondria have long been implicated in AD pathogenesis, as the canonical histopathological findings of amyloid plaques and tau tangles occur in the setting of mitochondrial dysfunction. The disrupted processes include calcium homeostasis, cholesterol metabolism, phospholipid synthesis, and mitochondrial dynamics, and are all regulated by a subcompartment of the ER that is in physical contact with mitochondria. This compartment, called the mitochondria-associated ER membrane, or MAM, has been found to be overactive in AD patient cell lines and cell models of AD. Given that MAM is dysfunctional in AD and that ApoE-ε4 is the most important risk factor for AD, this dissertation examines if ApoE4 contributes to the MAM dysfunction seen in AD. The MAM dysfunction seen in AD patients and in cell models of AD has been best characterized in the context of familial AD, and it is the purpose of this study to extend those findings to the more common, sporadic, form of the disease. Familial AD is the result of autosomal dominant mutations in one of three genes, amyloid precursor protein (APP), presenilin 1 (PSEN1), or presenilin 2 (PSEN2). APP is the protein from which amyloid-beta, the component of amyloid plaques, is cleaved. The presenilins constitute the enzymatic core of the γ-secretase complex, which cleaves amyloid-beta from a precursor APP molecule. Both PSEN1 (PS1) and PSEN2 (PS2) localize at the MAM, and their action is speculated to influence MAM activity. Fibroblasts from familial AD patients, which contained mutations in APP, PSEN1 or PSEN2, showed a marked increase in MAM activity when compared to that of age-matched controls. In mouse embryonic fibroblasts, one can recapitulate this increased MAM activity by knocking out presenilins 1 and 2. In these Psen1/2 double knockout (DKO) cells, the typical measures of MAM function, i.e. increased cholesteryl ester and phosphatidylethanolamine synthesis, calcium transport from ER to mitochondria, and co-localization of ER and mitochondria by confocal and electron microscopy, mimicked the same phenotype found in fibroblasts obtained from familial AD patients, which suggests that the presenilins are negative regulators of ER-mitochondrial apposition. The precise mechanism by which they regulate the ER-mitochondria interface, whether directly as part of a tethering complex, or indirectly though the metabolism of APP-derived substrates, is unclear. While the effect of familial AD mutations on MAM has been characterized, the mechanism of mitochondrial dysfunction seen in the more common sporadic form of the disease remains obscure. Sporadic AD patients harbor no mutations in APP, PSEN1, or PSEN2, but rather inherit mutations in other genes which do not guarantee the development of the disease, but are instead considered risk factors. The most important of these risk factors, in terms of both amount of AD risk conferred and prevalence in the population, is ApoE. Embedded in the phospholipid monolayer of lipoproteins, ApoE is involved in the transport of phospholipids, cholesterol, and cholesteryl esters in plasma and the central nervous system (CNS). In the CNS, it is the most abundant apolipoprotein, and is secreted primarily by astrocytes and taken up by neurons. Once endocytosed, ApoE can follow three different pathways: degradation by the lysosome, intracellular retention in early endosomes, or re-lipidation and re-secretion out of the cell. Our approach takes advantage of the physiological role of ApoE as part of a high densitylike lipoprotein particle (HDL). Using astrocytes from ApoE targeted gene replacement mice in which murine APOE has been replaced by either human APOE-E3 or human APOE-E4, cultured media containing ApoE3 and ApoE4-lipoproteins can be produced and applied to target cells that do not express ApoE, such as neurons or fibroblasts. These target cells can then be analyzed for MAM activity. To examine the contribution of ApoE towards MAM dysfunction, target cells, either neurons or fibroblasts, were grown in the presence of astrocyte conditioned media (ACM) from ApoE targeted gene replacement mice. Several measures of phospholipid and cholesteryl ester synthesis were performed to analyzed MAM function. To confirm that the alterations in phospholipid synthesis were the result of altered MAM activity, the same assay was performed in cells in which a protein tethers that bind mitochondria and ER were genetically ablated. Finally, to confirm that the effects seen were the result of the HDL particles and not the result of other components of the ACM, lipoproteins were extracted from ACM by density ultracentrifugation and applied to fibroblasts. In all of the assays performed, ApoE4 conditioned media or ApoE4 isolated lipoproteins were able to induce a significant increase in MAM activity, whereas ApoE4 from recombinant sources did not. These data suggest a contribution of ApoE4 towards MAM dysfunction seen in AD. The mechanism of these ApoE4 induced MAM alterations remains to be deduced. One may speculate that given the role of ApoE in cholesterol transport outside of the cell, its intracellular retention may impact the distribution of cholesterol within the cell. MAM is a cholesterol rich subdomain with lipid raft-like properties, and any change in the cholesterol content or lipid nature of this membrane may alter its activity. To test this hypothesis, MAM was biochemically extracted from ApoE3 and ApoE4 treated cells and analyzed for cholesterol and lipidomic content. The results described in this thesis demonstrate an AD-like effect in wildtype cells when treated with ApoE-E4, and that the mechanism for these alterations may be due to disturbances in cholesterol distribution in the MAM.

Introdução: A doença de Parkinson (DP) é uma doença neurodegenerativa cujo quadro clínico é essencialmente motor, no entanto as manifestações não motoras frequentemente estão presentes e muitas vezes são negligenciadas. Dentre as manifestações não motoras o declínio cognitivo tem ganhado destaque sendo causa de maior morbidade e mortalidade. A prevalência da demência na doença de Parkinson (DDP) varia de acordo com a população estudada e no momento do diagnóstico até 20% dos pacientes já apresentam algum grau de declínio cognitivo e com a evolução da doença até 80% dos pacientes apresentaram um quadro demencial associado a DP. Como A DP apresenta características clinico e patológicas sobrepostas à Doença de Alzheimer (DA) e a Apolipoproteína (ApoE) é o principal preditor de risco para desenvolvimento de demência na DA aventou-se a hipótese de que o alelo ?4 da ApoE pudesse ter relação com o risco de o paciente com DP desenvolver quadro demencial. Objetivo: analisar a relação entre o polimorfismo do gene ApoE com o desempenho cognitivo, avaliado pela MoCA, de pacientes com doença de Parkinson e descrever prevalência de cada alelo do gene em uma amostra de pacientes com DP da população brasileira. Método: estudo transversal onde foram analisados 186 pacientes em seguimento nos ambulatórios especializados em Distúrbios do Movimento do Hospital das Clínicas de Ribeirão Preto - HCFMRP e do Hospital São Paulo da Universidade Federal de São Paulo - UNIFESP, no período entre os anos de 2007 e 2014. Foi realizada a genotipagem dos alelos da ApoE e a avaliação cognitiva foi realiza através do MoCA. Para análise da amostra os pacientes foram classificados em portadores ou não do alelo ?4. Os grupos foram comparados utilizando o teste do Qui-quadrado para a variável sexo e o teste nãoparamétrico de Mann-Whitney para idade, tempo de doença e anos de estudo. Resultados: A análise dos escores da MoCA nos grupos com e sem o alelo ?4 não revelou diferença estatisticamente significativa entre os grupos (p=0,20). A frequência genotípica foi semelhante à descrita nos demais estudos sobre o assunto. Conclusão: a presença do alelo ?4 não está associada, em nossa amostra, a um pior desempenho cognitivo, quando este é avaliado pela escala cognitiva global MoCA. / Introduction: The Parkinson\'s disease (DP) is a neurodegenerative disorder where clinical findings are primarily motor however non-motor manifestations are often present and are frequently neglected. Among the non-motor events cognitive decline has gained prominence because it is cause of increased morbidity and mortality. The prevalence of Parkinson\'s disease dementia (PDD) varies depending on the population studied but at the time of diagnosis about 20% of patients already have some degree of cognitive decline and the progression of the disease up to 80% of patients demonstrated PDD. As DP has overlapping clinical and pathological features with Alzheimer\'s disease (DA) and apolipoprotein (ApoE) is the main predictor of risk for developing dementia in AD the hypothesis has suggested that the allele ?4 of ApoE could be related to the risk of the patient with PD develop dementia. Objective: analyze the relationship between ApoE gene polymorphism with the cognitive performance of patients with Parkinson\'s disease and describe prevalence of each allele of the gene in a sample of with PD in a Brazilian population. Method: cross-sectional study which analyzed 186 patients in follow-up in specialized of Hospital das Clínicas de Ribeirão Preto - HCFMRP and Hospital São Paulo of Universidade Federal de São Paulo - UNIFESP, between the years 2007 and 2014. Was made the genotyping for assessing the ApoE allele and cognitive assessment was carried out through the MoCA. For sample analysis, patients were classified as carriers or not allele ?4. The groups were compared using the chi-square test for gender and non-parametric Mann-Whitney test for age, disease duration and years of study. Results: The analysis of MoCA scores in the groups with and without the ?4 allele revealed no statistically significant difference between groups (p = 0.20). The genotypic frequency was similar to that described in other studies

Die verbesserte medizinische Versorgung führt zu einer zunehmenden Lebenserwartung unserer Gesellschaft. Damit steigt auch die sozioökonomische Relevanz neurodegenerativer Erkrankungen kontinuierlich. Für die Alzheimer Demenz (AD), die dabei die häufigste Ursache darstellt, stehen bisher keine krankheitsmodifizierenden Behandlungsoptionen zur Verfügung. Die lange präklinische Phase der Erkrankung birgt jedoch großes Potential für die Entwicklung neuer Behandlungsoptionen. Das Untersuchen von Risikogruppen ist für die Identifikation von Prädiktoren einer späteren AD Manifestation von besonderem Interesse. In diesem Zusammenhang werden insbesondere das Vorliegen genetischer Risikokonstellationen, wie dem Apolipoprotein E (APOE) Ɛ4-Allel, sowie kognitiver Risikofaktoren, wie der „leichten kognitiven Beeinträchtigung“ (MCI), diskutiert. Die Identifikation präklinischer Aktivierungsunterschiede in relevanten Gehirnregionen von Risikogruppen kann als Basis für die Entwicklung neurofunktioneller Früherkennungs-Marker dienen. Der präfrontale Kortex (PFC), welcher mit der Steuerung von Exekutivfunktionen assoziiert wird, hat sich in diesem Zusammenhang in bisherigen Studien als eine relevante Schlüsselregion manifestiert. Aufgrund der aufwendigen und kostenintensiven bildgebenden Untersuchungsmethoden, sind die genauen Prozesse jedoch noch unklar. Ziel der vorliegenden Arbeit war es daher, Unterschiede in der PFC Oxygenierung in zweierlei Risikogruppen der AD mit einer kostengünstigeren Bildgebungsmethode, der funktionellen Nahinfrarot Spektroskopie (fNIRS), zu untersuchen. Dafür wurde in einem ersten Schritt, der Trailmaking Test (TMT), ein weitverbreiteter neuropsychologischer Test zur Erfassung exekutiver Funktionen, für fNIRS implementiert. Als Grundlage für die Untersuchung frühpathologischer Prozesse, wurden zunächst gesunde Alterungsprozesse betrachtet. Der Vergleich von jungen und älteren Probanden (n = 20 pro Gruppe) wies neben der Eignung der Testimplementierung für fNIRS auf eine spezifische bilaterale PFC Oxygenierung hin, welche bei jungen Probanden rechtshemisphärisch lateralisiert war. Ältere Probanden hingegen zeigten bei vergleichbaren Verhaltensdaten insgesamt mehr signifikante Kanäle sowie eine Abnahme der Lateralisierung. Dies kann als zusätzlicher Bedarf an Ressourcen in gesunden Alterungsprozessen interpretiert werden. Im Rahmen der Hauptstudie wurden anschließend insgesamt 604 ältere Probanden im Alter von 70 bis 76 Jahren untersucht. Zunächst wurde die genetische Risikogruppe der Ɛ4-Allel-Träger (n = 78) mit den neutralen Ɛ3-Allel-Trägern (n = 216) und den Trägern des als protektiv geltenden Ɛ2-Allels (n = 50) verglichen. Hierbei zeigte sich eine geringere Oxygenierung der Risikogruppe bei geringer Aufgabenschwierigkeit, während sich ein erhöhter Oxygenierungsanstieg im medialen PFC mit steigender Aufgabenschwierigkeit zeigte. Dies deutet auf einen erhöhten Bedarf an neuronalen Kontrollmechanismen der Risikogruppe zur Bewältigung der steigenden Aufgabenschwierigkeit hin. Die protektive Gruppe zeigte hingegen eine erhöhte Oxygenierung im ventralen PFC mit steigender Aufgabenschwierigkeit, was möglicherweise auf einen präventiven Effekt hindeuten könnte. Weiterführend wurden MCI-Patienten mit gesunden Probanden (n = 57 pro Gruppe) hinsichtlich des kognitiven Risikofaktors verglichen. Hierbei zeigte sich ein punktuell reduzierter Oxygenierunganstieg der MCI Patienten mit steigender Aufgabenschwierigkeit vor allem im ventralen PFC bei ebenfalls stabiler Verhaltensleistung. Die gefundene Reduktion könnte ein Zeichen für eine aufgebrauchte kognitive Reserve sein, welche Einbußen auf Verhaltensebene voranzugehen scheint. Diese charakteristischen Unterschiede in den frontalen Oxygenierungsmustern von Risikogruppen (APOE, MCI) könnten als Biomarker zur Früherkennung von AD noch vor dem Auftreten kognitiver Einbußen dienen. Die fNIRS-Untersuchung während der Durchführung des TMT hat sich in diesem Zusammenhang als potentielles Instrument zur Frühdiagnose der präklinischen Phase der AD als geeignet erwiesen. Die Ergebnisse werden unter Einbezug des wissenschaftlichen Kontexts interpretiert und Implikationen für weitere notwendige Studien sowie die klinische Anwendbarkeit diskutiert. / Due to the improved medical care, the life expectancy of the society steadily rises. Consequently, the socioeconomic relevance of neurodegenerative disorders increases. In order to treat the Alzheimer’s Disease (AD), as the most frequent cause, disease-modulating treatment options are desperately awaited. The extensive preclinical phase of the disease has the potential for gaining new insights for the development of effective treatment strategies. The investigation of risk groups for AD is of great importance for the identification of preclinical prediction markers for the manifestation of a subsequent AD. Especially the presence of genetic risk factors like the Apolipoprotein E (APOE) Ɛ4-allele and cognitive risk factors such as the “mild cognitive impairment” (MCI) are being discussed in this context. Differences in brain activation patterns of risk groups based on functional brain imaging methods have been shown to be beneficial as potential biomarkers for early AD detection. As such, the prefrontal cortex (PFC) which is important for executive control mechanisms has been identified as a key structure of interest. However, many of the involved processes are still not sufficiently understood since most imaging methods are time-consuming and rather expensive. The aim of the present dissertation was to identify differences in PFC oxygenation in two different risk groups for AD by applying a cost-effective and easy-conductible imaging method, the functional Nearinfrared Spectroscopy (fNIRS). In a first step, the Trailmaking Test (TMT), which is a commonly used neuropsychological test for the investigation of executive functioning, was implemented for fNIRS. The neural subtracts were investigated as a basis for the subsequent examination of pre-pathological processes. Besides the usability of the suggested TMT implementation for fNIRS, the comparison of young and elderly subjects (n = 20 per group) showed a specific bilateral PFC oxygenation pattern which was right lateralized for the young group. Elderly adults on the other hand showed a decreased lateralization and more significant channels, pointing towards a need for additional resources in healthy aging. Subsequently the main study examined 604 elderly subjects aged between 70 and 76 years divided in two risk groups (APOE, MCI). In the first step, the genetic risk group of the Ɛ4-allele carriers (n = 78) was compared with the neutral Ɛ3-allele carriers (n = 216) and the carriers of the possibly protective Ɛ2-allele (n = 50). Thereby a reduced oxygenation of the risk group at low task difficulty has been shown, while a raised level of oxygenation increase in the medial PFC was found with growing task difficulty. This points towards a higher demand for neuronal control mechanisms in the genetic risk group in order to keep the performance level stable while task difficulty is increased. The protective group however showed a higher oxygenation in the ventral PFC with increasing task difficulty, which could indicate a higher cognitive reserve. In the second step, the MCI patients were compared with matched healthy control subjects (n = 57 per group). The result showed a reduced increase of oxygenation with increasing task difficulty limited to specific channels mostly within the central PFC while the performance was stable. This reduction could be a sign for the limit of the cognitive reserve, which becomes apparent before the decline of the cognitive performance. The characteristic differences of frontal oxygenation patterns in risk groups (APOE, MCI) could possibly serve as biomarkers for the early AD detection even before task performance declines. The investigation of neural oxygenation with fNIRS during the completion of the TMT has been shown to be suitable as a potential early diagnosis method in the preclinical phase of AD. The results are embedded in the scientific context and implications for future research as well as the clinical applicability are being discussed.

<p>Over 20 different plasma proteins have been shown to have the capacity to undergo conformational changes and self-assemble into highly stable and insoluble amyloid fibrils. </p><p>One, transthyretin (TTR), consists of 127 amino acid residues arranged in eight β-strands (named A to H) and is involved in two different clinical forms of amyloidosis. In familial amyloidotic polyneuropathy (FAP), mutated TTR is found in the amyloid deposits while in senile systemic amyloidosis (SSA) only wild type TTR is present in the amyloid deposits.</p><p>In this study, we have identified a novel form of amyloidosis that is caused by the deposition of an N-terminal fragment of apolipoprotein A-IV (apoA-IV). Interestingly, apoA-IV amyloid was found deposited in a patient that also suffered from SSA. Thus, this patient had two biochemically distinct and concurrent forms of amyloidosis that were derived from apoA-IV and TTR. </p><p>We have also discovered that two different morphological deposition patterns (identified as patterns A and B) exist in TTR-derived amyloidosis. Pattern A, observed in all SSA patients studied and in half of the FAP patients examined contained large homogenous deposits that were composed of short randomly oriented fibrils. In contrast, pattern B was observed in the remaining FAP patients and was represented by smaller-sized deposits that consisted of longer fibrils that were arranged in parallel bundles. The predominant TTR component deposited also differed between the two amyloid patterns. Amyloid pattern A contained mainly C-terminal TTR fragments while pattern B amyloid consisted of full-length TTR. Our findings suggest that two different mechanisms of fibril formation may exist in TTR-derived amyloidosis. </p><p>We have found two epitopes, corresponding to strand C and H that are surface-exposed in TTR-derived amyloid fibrils but hidden and part of the hydrophobic core in the native molecular structure. This indicates that TTR undergoes partial unfolding during fibril formation. </p>

<p>Nerve injury induces up-regulation of the chaperone protein clusterin in affected neurons and adjacent astrocytes but the functional significance of this response is unclear. We find that motor neuron survival is significantly greater in clusterin(+/+) compared to (-/-) mice. These results suggest that endogenous expression of clusterin is neuroprotective after nerve injury. However, motor neuron survival in clusterin overexpressing mice was not different from that in wildtype mice. In contrast, treatment of neuronal cultures with clusterin-TAT recombinant protein is neuroprotective, including a positive effect on neuronal network complexity.</p><p>Since extracellular clusterin complexes are endocytosed after binding to various receptors, we examined the expression of known clusterin binding receptors in the spinal cord. We find that megalin is expressed in the nuclei of two cell populations in the mouse spinal cord: i) oligodendrocytes in late postnatal and adult spinal cord white matter, and ii) transiently (E11-15) in a population of immature astrocytes in the dorsal spinal cord. We find no correlation between clusterin and megalin in the intact or injured spinal cord. However, intranuclear localization of megalin, suggesting signalling properties, is supported by the co-localization with γ-secretase, the enzyme responsible for endodomain cleavage of megalin. Megalin deficient mice display a pronounced deformation of the dorsal part of spinal cord, an almost complete absence of oligodendroglial progenitor cells, and a marked reduction in the population of mature astrocytes at later prenatal developmental stages.</p><p>Taken together, our findings indicate that megalin is a novel signalling molecule for distinct populations of glial cells in the pre- and postnatal spinal cord. The functional role(s) of megalin is unknown. However, its expression patterns and cellular localization suggest that megalin regulates differentiation of oligodendrocytes and astrocytes in the prenatal spinal cord, as well as the function of myelinating oligodendrocytes in the postnatal spinal cord.</p>

Over 20 different plasma proteins have been shown to have the capacity to undergo conformational changes and self-assemble into highly stable and insoluble amyloid fibrils. One, transthyretin (TTR), consists of 127 amino acid residues arranged in eight β-strands (named A to H) and is involved in two different clinical forms of amyloidosis. In familial amyloidotic polyneuropathy (FAP), mutated TTR is found in the amyloid deposits while in senile systemic amyloidosis (SSA) only wild type TTR is present in the amyloid deposits. In this study, we have identified a novel form of amyloidosis that is caused by the deposition of an N-terminal fragment of apolipoprotein A-IV (apoA-IV). Interestingly, apoA-IV amyloid was found deposited in a patient that also suffered from SSA. Thus, this patient had two biochemically distinct and concurrent forms of amyloidosis that were derived from apoA-IV and TTR. We have also discovered that two different morphological deposition patterns (identified as patterns A and B) exist in TTR-derived amyloidosis. Pattern A, observed in all SSA patients studied and in half of the FAP patients examined contained large homogenous deposits that were composed of short randomly oriented fibrils. In contrast, pattern B was observed in the remaining FAP patients and was represented by smaller-sized deposits that consisted of longer fibrils that were arranged in parallel bundles. The predominant TTR component deposited also differed between the two amyloid patterns. Amyloid pattern A contained mainly C-terminal TTR fragments while pattern B amyloid consisted of full-length TTR. Our findings suggest that two different mechanisms of fibril formation may exist in TTR-derived amyloidosis. We have found two epitopes, corresponding to strand C and H that are surface-exposed in TTR-derived amyloid fibrils but hidden and part of the hydrophobic core in the native molecular structure. This indicates that TTR undergoes partial unfolding during fibril formation.

Nerve injury induces up-regulation of the chaperone protein clusterin in affected neurons and adjacent astrocytes but the functional significance of this response is unclear. We find that motor neuron survival is significantly greater in clusterin(+/+) compared to (-/-) mice. These results suggest that endogenous expression of clusterin is neuroprotective after nerve injury. However, motor neuron survival in clusterin overexpressing mice was not different from that in wildtype mice. In contrast, treatment of neuronal cultures with clusterin-TAT recombinant protein is neuroprotective, including a positive effect on neuronal network complexity. Since extracellular clusterin complexes are endocytosed after binding to various receptors, we examined the expression of known clusterin binding receptors in the spinal cord. We find that megalin is expressed in the nuclei of two cell populations in the mouse spinal cord: i) oligodendrocytes in late postnatal and adult spinal cord white matter, and ii) transiently (E11-15) in a population of immature astrocytes in the dorsal spinal cord. We find no correlation between clusterin and megalin in the intact or injured spinal cord. However, intranuclear localization of megalin, suggesting signalling properties, is supported by the co-localization with γ-secretase, the enzyme responsible for endodomain cleavage of megalin. Megalin deficient mice display a pronounced deformation of the dorsal part of spinal cord, an almost complete absence of oligodendroglial progenitor cells, and a marked reduction in the population of mature astrocytes at later prenatal developmental stages. Taken together, our findings indicate that megalin is a novel signalling molecule for distinct populations of glial cells in the pre- and postnatal spinal cord. The functional role(s) of megalin is unknown. However, its expression patterns and cellular localization suggest that megalin regulates differentiation of oligodendrocytes and astrocytes in the prenatal spinal cord, as well as the function of myelinating oligodendrocytes in the postnatal spinal cord.

The field of proteomics studies the structure and function of proteins in a large scale and high throughput manner. My work in the field of proteomics focuses on identifying interactions between proteins and discovering novel interactions. The identification of these interactions provides new information on metabolic and disease pathways and the working proteome of a cell. Cells are lysed and purified using antibody based affinity purification followed by digestion and identification using an HPLC coupled to a mass spectrometer. In my studies, I looked at the interaction networks of several AD related genes (Apolipoprotein E, Clusterin variant 1 and 2, Low-density lipoprotein receptor, Phosphatidylinositol binding clathrin assembly protein, Alpha-synuclein and Platelet-activating factor receptor) and an endosomal recycling pathway involved in cholesterol metabolism (Eps15 homology domain 1,2 and 4, Proprotein convertase subtilisin/kexin type 9 and Low-density lipoprotein receptor). Several novel and existing interactors were identified and these interactions were validated using co-immunopurification, which could be the basis for future research.