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Description
Alzheimer’s Disease (AD) affects over 5 million individuals in the U.S. and has a direct cost estimated in excess of $200 billion per year. Broadly speaking, there are two forms of AD—early-onset, familial AD (FAD) and late-onset-sporadic AD (SAD). Animal models of AD, which rely on the overexpression of FAD-related

Alzheimer’s Disease (AD) affects over 5 million individuals in the U.S. and has a direct cost estimated in excess of $200 billion per year. Broadly speaking, there are two forms of AD—early-onset, familial AD (FAD) and late-onset-sporadic AD (SAD). Animal models of AD, which rely on the overexpression of FAD-related mutations, have provided important insights into the disease. However, these models do not display important disease-related pathologies and have been limited in their ability to model the complex genetics associated with SAD.

Advances in cellular reprogramming, have enabled the generation of in vitro disease models that can be used to dissect disease mechanisms and evaluate potential therapeutics. To that end, efforts by many groups, including the Brafman laboratory, to generated patient-specific hiPSCs have demonstrated the promise of studying AD in a simplified and accessible system. However, neurons generated from these hiPSCs have shown some, but not all, of the early molecular and cellular hallmarks associated with the disease. Additionally, phenotypes and pathological hallmarks associated with later stages of the human disease have not been observed with current hiPSC-based systems. Further, disease relevant phenotypes in neurons generated from SAD hiPSCs have been highly variable or largely absent. Finally, the reprogramming process erases phenotypes associated with cellular aging and, as a result, iPSC-derived neurons more closely resemble fetal brain rather than adult brain.

It is well-established that in vivo cells reside within a complex 3-D microenvironment that plays a significant role in regulating cell behavior. Signaling and other cellular functions, such as gene expression and differentiation potential, differ in 3-D cultures compared with 2-D substrates. Nonetheless, previous studies using AD hiPSCs have relied on 2-D neuronal culture models that do not reflect the 3-D complexity of native brain tissue, and therefore, are unable to replicate all aspects of AD pathogenesis. Further, the reprogramming process erases cellular aging phenotypes. To address these limitations, this project aimed to develop bioengineering methods for the generation of 3-D organoid-based cultures that mimic in vivo cortical tissue, and to generate an inducible gene repression system to recapitulate cellular aging hallmarks.
ContributorsBounds, Lexi Rose (Author) / Brafman, David (Thesis director) / Wang, Xiao (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Description
The aims of this project are: (i) to identify structural and molecular changes in the brains of 3xTg-AD mice and (ii) to determine whether decreasing S6K1 protects the brain from these changes. To achieve our goals, we decided to remove one copy of the S6K1 gene in 3xTg-AD mice by

The aims of this project are: (i) to identify structural and molecular changes in the brains of 3xTg-AD mice and (ii) to determine whether decreasing S6K1 protects the brain from these changes. To achieve our goals, we decided to remove one copy of the S6K1 gene in 3xTg-AD mice by breeding them with S6K1 knockout mice (S6K1+/-). In previous studies, we have seen that reducing S6K1 levels in 3xTg-AD mice improved spatial memory and synaptic plasticity which was associated with reduced A and tau pathology. Here, we used a multiparametric MRI to assess volumetric and blood flow changes in the brain of 20-month-old 3xTg-AD mice. We found that 3xTg-AD/S6K1+/- mice had higher blood flow and cortical volume compared to 3xTg-AD mice. However, we saw no significant differences between 3xTg-AD mice and NonTg mice. We further found A levels and plaque numbers were significantly lower in 3xTg-AD/S6K1+/- mice compared to 3xTg-AD mice. This reduction in plaques could account for the improvement in blood flow in 3xTg-AD/S6K1+/- mice. To try to understand the reason behind the increase in cortical volume in the 3xTg-AD/S6K1+/- when compared to the 3xTg-AD, we measured markers of synaptic density, PSD95, and synaptophysin. We found that PSD95 levels were not different between the four groups. However, synaptophysin levels were significantly lower in 3xTg-AD mice compared to NonTg levels and returned to baseline levels in 3xTg-AD mice lacking one copy of the S6K1 gene. This difference in synaptophysin could explain, at least in part, the difference in volume between the four groups analyzed. Overall, this represents the first evidence showing that reducing mTOR signaling improves blood flow and cortical volume in a mouse model of AD.
ContributorsShukla, Prakriti (Author) / Oddo, Salvatore (Thesis director) / Caccamo, Antonella (Committee member) / Jankowsky, Joanna (Committee member) / School of Molecular Sciences (Contributor) / School of Public Affairs (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
To date, it has been difficult to elucidate the role of tau in learning and memory during adulthood due to developmental compensation of other microtubule associated proteins in Tau knockout (KO) mice. Here, we generated an adeno-associated virus (AAV) expressing a doxycycline (doxy)-inducible short-hairpin (sh) RNA targeted to tau, and

To date, it has been difficult to elucidate the role of tau in learning and memory during adulthood due to developmental compensation of other microtubule associated proteins in Tau knockout (KO) mice. Here, we generated an adeno-associated virus (AAV) expressing a doxycycline (doxy)-inducible short-hairpin (sh) RNA targeted to tau, and stereotaxically and bilaterally injected 7-month-old C57BL/6 mice with either the AAV-shRNAtau or an AAV expressing a scramble shRNA sequence. Seven days after the injections, all animals were administered doxy for thirty-five days to induce expression of shRNAs, after which they were tested in the open field, rotarod and Morris water maze (MWM) to assess anxiety like behavior, motor coordination and spatial reference memory, respectively. Our results show that reducing tau in the adult hippocampus produces significant impairments in motor coordination, endurance and spatial memory. Tissue analyses shows that tau knockdown reduces hippocampal dendritic spine density and the levels of BDNF and synaptophysin, two proteins involved in memory formation and plasticity. Our approach circumvents the developmental compensation issues observed in Tau KO models and shows that reducing tau levels during adulthood impairs cognition.
ContributorsTran, An Le (Author) / Oddo, Salvatore (Thesis director) / Velazquez, Ramon (Committee member) / Roberson, Erik (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Description
Alzheimer’s disease (AD) is characterized by the aberrant accumulation and aggregation of proteins that in turn contribute to learning and memory deficits. The mammalian target of rapamycin (mTOR) plays an essential role in regulating the synthesis and degradation of proteins that contribute to cell growth and learning and memory. Hyperactivity

Alzheimer’s disease (AD) is characterized by the aberrant accumulation and aggregation of proteins that in turn contribute to learning and memory deficits. The mammalian target of rapamycin (mTOR) plays an essential role in regulating the synthesis and degradation of proteins that contribute to cell growth and learning and memory. Hyperactivity of mTOR can cause detrimental effects to protein homeostasis and has been linked to AD. The proline-rich Akt-substrate 40 kDa (PRAS40) is a negative regulator of mTOR, as it binds to mTOR directly, reducing its activity. Upon phosphorylation, PRAS40 detaches from mTOR thereby releasing its inhibitory effects. Increased phosphorylation of PRAS40, and a subsequent increase in mTOR activity has been linked to diabetes, cancer, and other conditions; however, PRAS40’s direct role in the pathogenesis of AD is still unclear. To investigate the role of PRAS40 in AD pathology, we generated a PRAS40 conditional knockout mouse model and, using a neuronal-specific Cre recombinase, selectively removed PRAS40 from APP/PS1 mice. Removing neuronal PRAS40 exacerbated Abeta levels and plaque load but paradoxically had no significant effects on mTOR signaling. Mechanistically, the increase in Abeta pathology was linked to a decrease in autophagy function. Our data highlight a primary role of PRAS40 in the pathogenesis of AD.
ContributorsSurendra, Likith (Author) / Oddo, Salvatore (Thesis director) / Velazquez, Ramon (Committee member) / Pratico, Domenico (Committee member) / School of Life Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
With no known cure, Alzheimer's disease (AD) is the most common dementia, affecting more than 5.5 million Americans. Research has shown that women who undergo surgical menopause (i.e. removal of the ovaries) before the onset of natural menopause are at a greater risk for AD. It is hypothesized that this

With no known cure, Alzheimer's disease (AD) is the most common dementia, affecting more than 5.5 million Americans. Research has shown that women who undergo surgical menopause (i.e. removal of the ovaries) before the onset of natural menopause are at a greater risk for AD. It is hypothesized that this greater relative risk of developing AD is linked to ovarian hormone deprivation associated with surgical menopause. The purpose of these studies was to evaluate the behavioral changes that occur after a short-term (ST) and a long-term (LT) ovarian hormone deprivation in a mouse model of AD. Wildtype (Wt) or APP/PS1 (Tg) mutation mice underwent either a sham surgery or an ovariectomy (Ovx) surgery at three months of age. Study 1 consisted of a short-term cohort that was behaviorally tested one month following surgery on a battery of spatial memory tasks including, the Morris water maze, delayed matched-to-sample water maze, and visible platform task. Study 2 consisted of a long-term cohort that was behaviorally tested on the same cognitive battery three months following surgery. Results of Study 1 revealed that genotype interacted with surgical menopause status, such that after a short-term ovarian hormone deprivation, Ovx induced a genotype effect while Sham surgery did not. Results of Study 2 showed a similar pattern of effects, with a comparable interaction between genotypes and surgical menopause status. These findings indicate that the cognitive impact of ovarian hormone deprivation depends on AD-related genotype. Neuropathology evaluations in these mice will be done in the near future and will allow us to test relations between surgical menopause status, cognition, and AD-like neuropathology.
ContributorsPalmer, Justin M. (Author) / Bimonte-Nelson, Heather (Thesis director) / Oddo, Salvatore (Committee member) / Davis, Mary (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
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Description

As life expectancy increases worldwide, age related diseases are becoming greater health concerns. One of the most prevalent age-related diseases in the United States is dementia, with Alzheimer’s disease (AD) being the most common form, accounting for 60-80% of cases. Genetics plays a large role in a person’s risk of

As life expectancy increases worldwide, age related diseases are becoming greater health concerns. One of the most prevalent age-related diseases in the United States is dementia, with Alzheimer’s disease (AD) being the most common form, accounting for 60-80% of cases. Genetics plays a large role in a person’s risk of developing AD. Familial AD, which makes up less than 1% of all AD cases, is caused by autosomal dominant gene mutations and has almost 100% penetrance. Genetic risk factors are believed to make up about 49%-79% of the risk in sporadic cases. Many different genetic risk factors for both familial and sporadic AD have been identified, but there is still much work to be done in the field of AD, especially in non-Caucasian populations. This review summarizes the three major genes responsible for familial AD, namely APP, PSEN1 and PSEN2. Also discussed are seven identified genetic risk factors for sporadic AD, single nucleotide polymorphisms in the APOE, ABCA7, NEDD9, CASS4, PTK2B, CLU, and PICALM genes. An overview of the main function of the proteins associated with the genes is given, along with the supposed connection to AD pathology.

ContributorsRichey, Alexandra Emmeline (Author) / Brafman, David (Thesis director) / Raman, Sreedevi (Committee member) / School of International Letters and Cultures (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description
This thesis aimed to develop a consistent protocol used to effectively image the apolipoprotein E (ApoE) ε4 allele, which is a known genetic risk factor for Alzheimer’s Disease (AD). The research team used methods to extract DNA from saliva samples, amplify the DNA using polymerase chain reaction (PCR), and image

This thesis aimed to develop a consistent protocol used to effectively image the apolipoprotein E (ApoE) ε4 allele, which is a known genetic risk factor for Alzheimer’s Disease (AD). The research team used methods to extract DNA from saliva samples, amplify the DNA using polymerase chain reaction (PCR), and image the results using gel electrophoresis and a transilluminator. Extensive literature review was used to optimize these techniques. Future studies will use these methods of characterizing the ApoE ε4 allele as preliminary work towards the goal of integrating this protocol into ongoing research in aging within the Motor Rehabilitation and Learning (MRL) Lab on Arizona State University’s campus.
ContributorsWorman, Drew (Author) / Schaefer, Sydney (Thesis director) / Lewis, Candace (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05