Regulation of Aß-scavengers in the choroid plexus of Alzheimer´s disease patients.

• Autor(a) principal: Oliveira, André Pedro
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/6383
• topic: Alzheimer´S Disease; Amyloid ß; Angiotensin-Converting Enzyme; Aß-Scavengers; Choroid Plexus; Circadian Rhythm; Clock Genes; Gelsolin; Insulin-Degrading Enzyme; Metallothionein-2a; Neprilysin; Transthyretin; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Alzheimer’s disease (AD) is a neurodegenerative disorder described as a progressive cognitive impairment and represents the most frequent cause of dementia in the elderly. AD is considered to be a multifactorial disease, which is characterized by accumulation of extracellular amyloid-ß peptide (Aß) into soluble plaques in the brain, associated with the aggregation of tau protein into intracellular neurofibrillary tangles leading to neuronal loss. Recently, it has been demonstrated that the choroid plexus (CP) has a role counteracting in the disease progression, specifically, by producing Aß-scavengers and performing Aß clearance. Insulin-degrading enzyme (IDE), angiotensin-converting enzyme (ACE), gelsolin (GLS), neprilysin (NEP), transthyretin (TTR) and metallothionein-2A (MT2A), are categorized Aß-scavengers and perform the Aß clearance. Memory formation and cognitive functions are deeply influenced by sleep which is controlled by the circadian clock. The circadian rhythm comprises the human internal clock system, characterized by the suprachiasmatic nucleus (SCN). SCN represents the core of the circadian system, responsible for oscillations with a periodicity of approximately 24h in sleep-wake cycle, body temperature, feeding, rest-activity behavior, hormonal levels, among others. The regulation of the circadian rhythms depends on a set of clock genes, including circadian locomoter output cycles kaput (CLOCK), brain and muscle Arnt-like protein-1 (BMAL1) or aryl hydrocarbon receptor nuclear translocator-like (ARNTL), three PERIOD genes (PER1, PER2, and PER3) and two plant CRYPTOCHROME gene homologues (CRY1 and CRY2). During sleep there is an increase of Aß clearance in brain and also in CSF of healthy individuals, which contrasts with the diminished Aß clearance in AD brains. The hypothesis of this work study is that the circadian rhythm regulates the expression of Aß-scavengers in the CP of AD patients. Firstly, primers were designed for IDE, NEP, ACE, GLS, TTR, MT2A, CLOCK, BMAL1, PER2, PER3 and CRY2 genes, and respectively optimizations of their RT-qPCR reactions were also carried out with success. Finally, an analysis of mRNA expression levels of TTR, GLS and NEP genes was performed on the CP of AD patients along the stages of the disease by real-time quantitative PCR (RT-qPCR). TTR and GLS mRNA levels were significantly upregulated in Braak stage II, when compared to age-matched controls. In the following Braak stages, the levels returned normal levels as observed in age-matched controls. NEP mRNA levels displayed the same tendency but it did not reach statistical significance.