Decreased mitochondrial function is associated with aging and is an early step in Alzheimer's disease (AD). Autophagy also declines with age and is required for degradation of dysfunctional mitochondria but it is not known whether autophagosomal formation is overactive and/or degradation of autophagosomes is inhibited in AD. Although two-thirds of the 5 million Americans diagnosed with AD are women, without a clear mechanism. Since the role of gender and autophagy in AD is unclear, we wanted to know whether: A) decreased mitochondrial biogenesis precedes brain plaque formation, neuronal death and memory deficits B) autophagosomal formation is overactive and/or degradation of autophagosomes is inhibited in AD and C) deficits in mitochondrial biogenesis and autophagy occur earlier in life in the hippocampus/cortex of female AD-Tg, than male AD-Tg mice. To answer these questions, mitochondrial DNA (mtDNA), TFAM (transcription factor A mitochondrial) and two stages in autophagy, autophagosomal formation and degradation were measured in the hippocampus/cortex of non-transgenic (non-Tg) and the APP(Swe, DI)/NOS2-/- AD mouse model (AD-Tg) from 2 mo. through 12 mo. of age, when memory deficits develop. Male and female mice were evaluated for gender differences. By measuring mitochondrial gene copy number relative to nuclear gene copy number by qPCR, we found female specific decreases in mtDNA and TFAM protein levels in AD-Tg hippocampus/cortex, before 12 mo., when memory deficits develop. The male AD-Tg mice did not show any decline in the levels of mtDNA or TFAM protein through 12 mo. of age, indicating a decline in mitochondrial biogenesis earlier in life in female AD-Tg mice, than males. To determine whether autophagosomal formation is overactive and/or autophagosomal degradation is inhibited in AD, non-Tg and AD-Tg mouse neurons from 2-12 mo. of age were cultured and transfected with an adenovirus expressing the dual fusion protein, mCherry-GFP-LC3B. This system enables the distinction of early (autophagosomal formation) from late (autophagosomal degradation) stages of autophagy. Autophagosomal formation increased in female AD-Tg mice, while male AD-Tg neurons have decreased formation of autophagosomes, compared to non-Tg. Neurons from AD-Tg mice show deficits in degradation of autophagosomes by 2 mo. Our results show increased autophagosomal formation in female neurons with age and in our AD-like model without corresponding increases in degradation of autophagosomes. All together, our data indicates that the presence of familial APP mutations and knockout of NOS2 increases deficits in both mitochondrial biogenesis and autophagy in female mice, compared to males. These deficits occur before amyloid plaque formation and memory deficits, suggesting that mitochondrial and autophagic deficits may play a role in the higher incidence of AD in females.

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The indirect influence of prior experience on a subsequent task is termed Implicit memory (IM). This study examined the status of pictorial and verbal IM in four groups of 20 subjects each: normal young (M age = 27.2), young-old (M age = 66.7), old-old (M age = 76.6), and Alzheimer's disease (AD) patients (M age = 75.4, M Mini-Mental State Examination score = 17.3). Study conditions involved reading words, naming pictures, and generating best-fit endings for high-cloze sentence frames (e.g., Ron swept the floor with a ____ .). Implicit memory was subsequently assessed by word-stem completion (WSC), in which subjects were instructed to complete three-letter stems with the first word that came to mind (e.g., bro____), and picture-fragment identification (PFI), in which subjects attempted to identify perceptually degraded pictures. Among the control groups, WSC priming was greatest following word study, and PFI priming was greatest following picture study, thereby establishing that crossover priming effects recently found among young subjects are fully retained in healthy aging, In contrast to previous studies suggesting that WSC priming may be preserved for deeply encoded material in AD patients, the present results showed that WSC priming was impaired in the AD group regardless of study condition, Nevertheless, AD patients demonstrated normal perceptual priming on the PFI task following picture study, These findings support a dissociation between perceptual and conceptual priming in AD. Explicit yes/no recognition testing revealed standard picture superiority and generation effects among controls. AD patients, in contrast, were impaired on all recognition items. Results are discussed in terms of transfer-appropriate processing theory, which states that level of retention Is a function of the degree to which processes invoked at study are recapitulated at test. Essentially, the similarity between word reading and WSC and between picture naming and PFI is a crucial determinant of priming effects In healthy young and elderly subjects. AD patients' WSC impairment may be due to a lexical-semantic processing deficit, whereas their preserved PFI priming may be supported by intact perceptual processes. Similarly, their uniformly depressed recognition memory may be explained by impaired conceptual processing. / Graduate

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Alzheimer’s disease (AD) is the most common form of dementia, with more than 25 million people worldwide suffering this progressive intellectual failure. The disease was first described by the German psychiatrist, Alois Alzheimer in 1907, and is characterised by the appearance of proteinaceous depositions (first isolated in 1984), which are comprised of insoluble amyloid-ß (Aß)-aggregates. Aβ is derived from the β-amyloid precursor protein from which it is generated by the action of two proteases. Initially it was assumed that the insoluble amyloid fibrils, which were easily detectable, mediated the observed toxicity although it was recognised that amyloid plaque number did not correlate well with the severity of dementia. However, further studies with synthetic and human-derived Aß provided strong evidence that soluble prefibrillar aggregates of Aß mediated the synaptic failure and loss of cognitive performance. In 2008 genetic evidence showed that the presence of soluble Aß-oligomers is sufficient to cause an AD-like dementia, which centres the oligomeric Aβ as the probable effector of synapse loss. Although a variety of assemblies have been described their meta-stability and technical limitations caused a controversial debate about aggregate related pathogenesis. Thus, this study aimed to establish a structure-activity relationship comparing different synthetic Aß-aggregates using biophysical methods to follow aggregation and to assess morphology, absolute MW and meta-stability of monomeric, oligomeric, protofibrillar and fibrillar Aß. However, interference with the aggregate equilibrium, by changing the ionic environment, can cause structural conversion of Aß-aggregates. Therefore, different Aß-aggregates were only compared in short-termed physiological settings i.e. neuronal binding and hippocampal neurotransmission. Herein, only prefibrillar aggregates bound to neurons and differentially impaired hippocampal neurotransmission either by inhibition of basal neurotransmission or NMDA-dependent long-term potentiation. In addition, changing the ionic environment provoked a structural conversion, which also changed the pathogenic mode of action. This study provides experimental evidence that different soluble Aß-aggregates are highly potent synaptotoxins, impairing neurotransmission by different mechanisms. Furthermore, solution-based biophysical characterisation and acute biological paradigms are crucial for differential characterisation of Aß-aggregates revealing that virtually similar aggregates can have opponent pathogenic effects; thus, morphology only does not explain observed pathogenicity.

Direct to consumer (DTC) personal genetic testing (PGT) is a popular choice for individuals in the United States who are interested in learning more about their genetic health risks without formally seeing a medical professional. The company 23andMe offers FDA-approved genetic risk tests for conditions including late-onset Alzheimer’s Disease (AD), Parkinson Disease, Celiac Disease, and the BRCA1/2 mutations. Although this company’s genetic risk testing results are accompanied by a generic information sheet regarding what each individual’s result means for each condition, formal genetic counseling is not included in the service. However, when a condition such as late-onset AD has both known genetic and behavioral risk factors, counseling becomes essential in preventing or delaying disease onset. Following a Mediterranean-style diet, regularly exercising, and regularly participating in cognitive activities (e.g. reading the newspaper or playing a musical instrument) are each thought to be protective against developing late-onset AD. Previous studies have shown that customers do not usually make significant lifestyle modifications after completing DTC PGT, though the majority of this literature may not be relevant to late-onset AD as it included customers of DTC PGT companies that no longer exist today and the genetic risk test for late-onset AD at that time was not yet approved by the Food and Drug Administration. The proposed study is an interventional study that will compare DTC PGT customer exercise, diet, and cognitive activity habits before and after a personalized genetics counseling session. Exercise will be measured using the Godin-Leisure Time Exercise Questionnaire. Diet will be evaluated by a validated food frequency questionnaire evaluating daily servings of fruits, vegetables, and unprocessed nuts. Cognitive activity at the time of survey will be evaluated by a questionnaire asking for the frequency of various cognitive activities, such as reading newspapers, reading books, artistic activities, and social activities.

The generation of amyloid-β (Aβ) peptides through proteolytic processing of the amyloid precursor protein (APP) is a key pathogenic event in Alzheimer’s disease (AD). Aβ generation begins with APP endocytosis, which is mediated by the endocytic YENPTY sequence located in the cytoplasmic tail of APP. Mints, a family of cytosolic adaptor proteins, directly bind to the YENPTY motif of APP and facilitate APP endocytosis and amyloidogenic processing. In addition, loss of any one of the three Mint proteins decreases Aβ production in aging mouse models of AD, supporting the hypothesis that the APP-Mint interaction may provide a novel therapeutic target to selectively reduce Aβ production in AD. Characterizing the biochemical and cellular dynamics of the APP-Mint interaction is critical for understanding Aβ generation. Thus, we generated Mint1 mutants that bind with high affinity (Mint1Y633A) or low affinity (Mint1Y549A/F610A) to APP. These Mint1 mutants exhibited profound alterations in cellular localization, APP endocytosis, and Aβ production. Therapeutically, we generated a novel cell-permeable APP mimetic peptide (APPMP) that interferes with the APP-Mint interaction. This APPMP was designed to outcompete endogenous APP binding, with a 46-fold improved affinity to Mint. Treatment of primary neurons from an AD mouse model with several cell permeable APPMP variants reduced Aβ production with minimal cellular toxicity, supporting Mints as a promising novel therapeutic target for AD. The PTB domain of Mint1 that mediates APP binding is autoinhibited by an adjacent C-terminal α-helix. However, the molecular mechanisms underlying the relief of Mint1 autoinhibition are unclear. Since post-translational modification is one mechanism for alleviating protein autoinhibition, and Mint1 is highly regulated by phosphorylation, we performed mass spectrometry and identified several Mint1 phosphosites. In addition, we found constitutively-active Src kinase, a kinase implicated in Mint phosphorylation, enhanced APP-Mint1 binding. These results suggest that Src kinase-mediated phosphorylation of Mint1 may relieve Mint1 autoinhibition and promote APP-Mint1 interaction. Overall, this work biochemically characterized the Mint-APP interaction and how it affects amyloidogenic processing, provided a proof of concept for targeting the APP-Mint1 interaction as an AD therapeutic target, and suggested a novel mechanism for the relief of Mint1 autoinhibition.

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