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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
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

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
Description

Alzheimer’s disease (AD) is a devastating disorder that affects the lives of both patients and their loved ones. While it is believed that AD is due to a buildup of amyloid plaques in the brain that eventually lead to the formation of neurofibrillary tangles (NFTs) and result in neurodegeneration, there

Alzheimer’s disease (AD) is a devastating disorder that affects the lives of both patients and their loved ones. While it is believed that AD is due to a buildup of amyloid plaques in the brain that eventually lead to the formation of neurofibrillary tangles (NFTs) and result in neurodegeneration, there are many theories that attempt to define the causes of AD. This paper investigates the amyloid and tau theories in more detail, including how these proteins can spread in the brain. It will also take a look into other potential theories that could contribute to AD symptoms such as vascular issues or neuroinflammation. Frontotemporal dementia (FTD) is another form of dementia, albeit much rarer than AD, that is typically characterized by symptoms that follow the opposite progression of AD: behavior and judgement are affected before memory. In addition, FTD is closely related to amyotrophic lateral sclerosis (ALS), a movement disorder that is caused by a loss of motor neurons that results in loss of muscle control. This paper will also examine how FTD and ALS are related, as well as theories behind the potential causes of these disorders. Finally, this paper will examine a patient who exhibits signs and symptoms of both disorders to attempt to determine the potential diagnosis.

ContributorsYeturu, Sree Neha (Author) / Velazquez, Ramon (Thesis director) / Duane, Drake (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor)
Created2023-05
Description

Alzheimer’s Disease (AD) is the most prevalent form of dementia and is the sixth leading cause of death in the elderly. Evidence suggests that forms of stress, including prenatal maternal stress (PMS), could exacerbate AD development. To better understand the mechanism linking PMS and AD, we investigated behavior and specific

Alzheimer’s Disease (AD) is the most prevalent form of dementia and is the sixth leading cause of death in the elderly. Evidence suggests that forms of stress, including prenatal maternal stress (PMS), could exacerbate AD development. To better understand the mechanism linking PMS and AD, we investigated behavior and specific epigenetic markers of the 3xTg-AD mouse model compared to aged-controls in offspring of stressed mothers and non-stressed mothers.

ContributorsBrookhouser, Leia (Author) / Coleman, Paul (Thesis director) / Velazquez, Ramon (Committee member) / Conrad, Cheryl (Committee member) / Judd, Jessica (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2022-12
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Description
Dementia is a collective term used to describe symptoms of cognitive impairment in learning and memory. The most prevalent form of dementia is Alzheimer’s disease (AD). In order to understand the pathological mechanisms associated with AD, animal models have been created. These various mouse models replicate the pathology found in

Dementia is a collective term used to describe symptoms of cognitive impairment in learning and memory. The most prevalent form of dementia is Alzheimer’s disease (AD). In order to understand the pathological mechanisms associated with AD, animal models have been created. These various mouse models replicate the pathology found in humans with AD. As a consequence of the fact that this disease impairs cognitive abilities in humans, testing apparatuses have been developed to measure impaired cognition in animal models. One of the most common behavioral apparatuses that has been in use for nearly 40 years is the Morris water maze (MWM). In the MWM, animals are tasked to find a hidden platform in a pool of water and thereby are subjected to stress that can unpredictably influence cognitive performance. In an attempt to circumvent such issues, the IntelliCage was designed to remove the external stress of the human experimenter and provide a social environment during task assessment which is fully automated and programable. Additionally, the motivation is water consumption, which is less stressful than escaping a pool. This study examined the difference in performance of male and female cohorts of APP/PS1 and non-transgenic (NonTg) mice in both the MWM and the IntelliCage. Initially, 12-month-old male and female APP/PS1 and NonTg mice were tested in the hippocampal-dependent MWM maze for five days. Next, animals were moved to the IntelliCage and underwent 39 days of testing to assess prefrontal cortical and hippocampal function. The results of this experiment showed significant sex differences in task performance, but inconsistency between the two testing paradigms. Notably, males performed significantly better in the MWM, which is consistent with prior research. Interestingly however, APP/PS1 females showed higher Amyloid-β plaque load and performed significantly better in the more complex tasks of the IntelliCage. This suggests that Aβ plaque load may not directly contribute to cognitive deficits, which is consistent with recent reports in humans with AD. Collectively, these results should inform scientists about the caveats of behavioral paradigms and will aid in determining translation to the human condition.
ContributorsMifflin, Marc Anthony (Author) / Velazquez, Ramon (Thesis director) / Mastroeni, Diego (Committee member) / School of Geographical Sciences and Urban Planning (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
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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
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Description

Receptor-interacting serine/threonine protein kinase 1 (RIPK1) is an enzyme whose interaction with tumor necrosis factor receptor 1 (TNFR1) has been found to regulate cell death pathways, such as apoptosis and necroptosis, and neuroinflammation. Accumulating evidence in the past two decades has pointed to increased RIPK1 activity in various degenerative disorders,

Receptor-interacting serine/threonine protein kinase 1 (RIPK1) is an enzyme whose interaction with tumor necrosis factor receptor 1 (TNFR1) has been found to regulate cell death pathways, such as apoptosis and necroptosis, and neuroinflammation. Accumulating evidence in the past two decades has pointed to increased RIPK1 activity in various degenerative disorders, including Amyotrophic Lateral Sclerosis (ALS), stroke, traumatic brain injury (TBI) and Alzheimer’s Disease (AD). Given the work showing elevated RIPK1 in neurodegenerative disorders, to further understand the role of RIPK1 in disease pathogenesis, we created a conditional mouse overexpressing neuronal RIPK1 on a C57BL/6 background. These conditional transgenic mice overexpress murine RIPK1 under the CAMK2a neuronal promoter and the transgene is under the control of doxycycline. The removal of doxycycline turns on the RIPK1 transgene. Two cohorts of transgenic mice overexpressing neuronal RIPK1 (RIPK1 OE) were produced, and both had doxycycline removed at post-natal day 21. One cohort was behaviorally tested at 3-months-of-age and the second cohort was tested at 9-months-of-age. Behavioral testing included use of the RotaRod and the Morris water maze to assess motor coordination and spatial cognition, respectively. We found that the RIPK1 OE mice showed no deficits in motor coordination at either age but displayed spatial reference learning and memory deficits at 3- and 9-months-of-age. A subset of mice from two independent cohorts were utilized to assess RIPK1 levels and neuronal number. In these two cohorts of mice used for postmortem analysis, we found that at 3 months of age, ~2 months after transgene activation, RIPK1 levels are not higher in the hippocampus or cortex of the RIPK1 OE mice, however at 9 months, ~8 months after transgene activation, RIPK1 levels are significantly higher in the hippocampus and cortex of RIPK1 OE mice compared to the NonTg counterparts. A subset of tissue was stained against the neuronal marker NeuN. Using unbiased stereology to quantify hippocampal CA1 pyramidal neurons, we found no neuronal loss in the 3-month-old RIPK1 OE mice, but a 34.01% reduction in NeuN+ neuron count in 9-month-old RIPK1 OE mice. Collectively our data shows that RIPK1 overexpression impairs spatial reference learning and memory and reduces neuron number in the CA1 of the hippocampus, underlining the potential of RIPK1 as a target for ameliorating CNS pathology.

ContributorsBoiangiu, Mara-Clarisa (Author) / Velazquez, Ramon (Thesis director) / Newbern, Jason (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution & Social Change (Contributor) / Department of Psychology (Contributor)
Created2022-05