Abdulbaki Agbas, PhD
Department of Pharmacology and Toxicology, University of Kansas
The major obstacle to progress in the field of human neurodegenerative diseases (NDD) is molecular assessment of the longitudinal progress of proteinopathy in living AD patients before the clinical manifestations. The status of platelet surrogate markers is a new way of looking at the proteinopathy in the AD brain, and may help in a better understanding of the etiology of NDDs. Aberrant protein accumulation will often lead to proteasome dysfunction, subsequently initiating neuronal cell death. A recently re-discovered TDP-43 protein modification is common in many neurodegenerative diseases. Aberrant TDP-43 protein's involvement in proteasome malfunction is particularly important, because post-translationally modified protein aggregation is pivotal in the biology of neurodegenerative disease. We are committed to address this issue since our preliminary data may suggest that aberrant TDP-43 protein aggregation concurrently occurs in the AD brain and in the patients' platelets. The overall strategy of this proposal is (i) to document that hyper-phosphorylation of TDP-43 protein is happening in AD brain; (ii) the same hyper-phosphorylation occurs in AD patients' platelets; (iii) the ubiquitinated TDP-43 species appears in AD platelets, and (iv) the proteasome activity is reduced, if not halted completely, in the AD platelets. If successful, this approach can be used to help early diagnosis of AD by analyzing specific pTDP-43 protein in AD patients' platelets, and longitudinally monitoring the disease progress. This approach also may be used for testing new pharmaceuticals designed for either interfering with the formation of the protein aggregation or dissociation of the aggregated proteins in AD brain.
Koteswara Rao Valasani, PhD, ShiDu Yan, MD (mentor)
Department of Pharmacology and Toxicology, University of Kansas
Neurodegenerative diseases are characterized by the progressive loss of neuron populations. These disorders afflict all age groups. The mPTP play vital role in neuronal cell death. Interaction of amyloid-Î² with ABAD triggers or enhances the formation of mPTP, consequently exacerbating mitochondrial and neuronal dysfunction, as shown by decreased mitochondrial membrane potential, impaired mitochondrial respiration function, and increased oxidative stress and cytochrome c release, ultimately leading to neuronal cell death. Blockade of AÎ²-ABAD interaction by genetic abrogation or pharmacologic inhibition protects neurons from amyloid-Î² induced toxicity, suggesting that ABAD dependent mitochondrial transition pore is a potential target for drug development for the prevention and treatment of AD.
Here, we identified novel benzthiazole derivatives showing good quality drug like properties. These inhibitors are predicted the best inhibitory activity against ABAD by in silico. We used MOE software tools for the novel small molecules designing and their quantitative structure activity relationship. QSAR descriptors were studied followed by Lipinski rule filtration. The preliminary structure-activity relationship study indicated that the phoshonate moiety was required for inhibitory activity. Inhibitory activity of benzthiazole phosphonate derivatives was further evaluated in vitro by surface plasma resonance binding assay, and mitochondrial swelling assays to validate the effect on mitochondrial function. These studies will provide new information of exploring and synthesizing novel antagonists for ABAD inhibitors, which holds a potential for the AD therapeutics and beyond in particular mitochondrial and synaptic medicine.
Amber Watts, PhD
Department of Psychology, University of Kansas
Older adults are a highly sedentary group, spending about 60% of waking time in sedentary activities. Our recent paper suggests this rate is even higher in people with AD (Watts et al., in press). Walking is a safe and inexpensive physical activity that can improve health and function for many older adults, including those with physical or cognitive impairments. Though recent research points to the importance of neighborhood walkability on sedentary behavior, little of this work has focused on older adults, with or without AD. The goal of the proposed research is to evaluate the role of neighborhood walkability in walking and sedentary behavior among older adults with AD. Our recent CTSA award funded preliminary collection of accelerometry data in AD patients. Accelerometry offers a vast improvement over self-report especially for the measure of sitting time, walking, and other low intensity physical activities. This work has established feasibility of this technology in patients with AD. We propose to 1) conduct secondary analysis of existing KU-ADC data (participant addresses, self-reported physical activity, cognitive performance, and health outcomes (BMI, physical performance, lipid and glucose biomarkers). We will evaluate neighborhood walkability using a cutting edge technique (space syntax). This approach uses geographical (GIS) data to understand the physical characteristics of the neighborhoods of individual AD patients, thus allowing determination of their relationship with walking. 2) We will add collection of objective accelerometry and space syntax to the ongoing registry to test our hypothesis that neighborhood walkability is related to walking and sedentary behavior.
Hao Zhu, PhD
Department of Clinical Laboratory Sciences, University of Kansas Medical Center
Mitochondrial dysfunction and oxidative stress play a pivotal role in brain aging and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. In this pilot grant application, we will utilize brain-specific and intra-mitochondrial delivery of exogenous transcripts to AD cybrid cells (SH-SY5Y cells that contain mitochondria of AD patients) and mouse brains to modulate levels of mitochondrial-encoded ETC subunits for functional studies. Our long-term goal is to the study effects of non-conserved non-synonymous SNP's on mitochondrial function and brain aging. Our central hypothesis is that the delivery of exogenous mitochondrial transcripts, coding or interfering, can significantly alter mitochondrial function and ROS generation in a manner that is controllable and precise. In Aim 1, we will rescue mitochondrial functional defects in neuronal AD cybrid cells by intra-mitochondrial delivery of exogenous transcripts. In Aim 2, we will intra-mitochondrial delivery with brain-specific DNA delivery for functional studies. Our experiments combine biochemical, molecular and cellular approaches. They collectively should address how deficiency of mitochondrial genome-coded electron transport chain subunits accelerates brain aging.
Nancy Berman, PhD
Department of Anatomy and Cell Biology, University of Kansas Medical Center
Alzheimer's Disease (AD) is a major public health concern with severe consequences that include long-term loss of function, profound disability, and death. Few treatments are available to prevent, reverse, or slow the course of the disease, and there is an urgent need to identify new treatment targets. Recent studies have shown that exercise can benefit Alzheimer's patients and can slow the loss of brain tissue that accompanies the disease. Our long-term goal is to determine the molecular mechanism that underlies these neuroprotective effects of exercise. Our hypothesis is that exercise upregulates the neuroprotective protein erythropoietin (EPO) in the hippocampus, resulting in reduced amyloid plaque formation and tau deposition in the hippocampus and improved memory function. The objectives of this pilot application are to determine whether voluntary exercise in triple transgenic AD mice increases EPO mRNA and protein in the hippocampus, reduces plaque and tangle burden, and improves memory function. AD mice will be provided access to voluntary exercise or housed conventionally for six weeks at the time of disease onset. Two specific aims are proposed. In the first specific aim, we will determine whether voluntary exercise improves cognitive function in AD mice and whether exercise reduces plaque and tangle formation. Cognitive function will be assessed using the radial arm water maze task, while plaque and tangle formation will be assessed using histological methods. In the second aim, we will determine whether voluntary exercise increases expression of EPO in the hippocampus in Alzheimer's mice. EPO mRNA levels will be determined using quantitative RT-PCR, and cell types expressing EPO will be determined by immunohistochemistry.
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center
Brain glucose utilization changes with age/Alzheimer's (AD). Many factors may play into this, some of which have probably not been elucidated. Similarly, there are few insights into the molecular mechanism that cause AD neurons to re-enter the cell cycle, a suicidal change. Both outcomes could result from or reflect age- dependent changes in the regulation of glycolysis. Pyruvate kinase (PYK) is a glycolysis enzyme that, through a sophisticated series of post-translational modifications, helps regulate glycolysis flux. PYK also plays a key role in defining Warburg metabolism, and through this PYK helps influence cell cycling. The state of PYK post- translational modifications and PYK expression to-date have not been studied in neither aging nor AD. Addressing this knowledge gap is necessary since data from such studies could yield mechanistic insight into age and AD-associated glycolysis flux changes, as well as aberrant neuron cell cycle re-entry in the AD brain. This project will address this knowledge gap by comparing healthy vs. aged/Alzheimer's brain samples to determine if PTMs of PYK and/or expression of PYK isozyme type change as the brain ages. Understanding the status of PYK as the brain ages could identify and validate PYK as a pharmacological target that may benefit the aging or Alzheimer's brain.
Jill Morris, PhD, Jeff Burns MD, MS (mentor)
Department of Neurology, University of Kansas Medical Center
Glucose metabolism plays a complex role in cognitive decline and memory in AD. Type 2 Diabetes, characterized by insulin resistance, is linked to AD risk and markers of insulin resistance are observed in post-mortem AD brain. It has been shown that high insulin is associated with less cognitive decline in AD and that intranasal insulin administration improves memory. However, the effects of intranasal insulin are not consistent between studies. Greater than 20% of older adults exhibit impaired glucose tolerance or diabetes, and insulin sensitivity is likely an important mediator of insulin's cognitive effects. We will use the "gold standard" for measuring insulin sensitivity, the hyperinsulinemic-euglycemic clamp, to assess the relationship between insulin sensitivity and cognitive measures in AD subjects. Subjects will be recruited from the ADC registry. Longitudinal cognitive decline will be determined by comparing baseline cognitive testing to a 12 month follow-up visit (Aim 1). Because endogenous insulin levels increase significantly to compensate for mild insulin resistance, we hypothesize that subjects with mild insulin resistance and high insulin will exhibit the slowest longitudinal cognitive decline. Memory testing will be performed prior to the clamp (fasting) and during hyperinsulinemia to determine the effect of insulin on memory (Aim 2). We expect that insulin sensitivity will mediate the beneficial effect of insulin on cognition, and that the most insulin-sensitive subjects will exhibit the greatest memory effect in response to exogenous insulin. This study will provide important mechanistic insight into the role of insulin sensitivity in cognition and memory in AD.
Department of Molecular and Integrative Physiology, University of Kansas Medical Center
Although aging is the primary risk factor for developing Alzheimer's disease (AD), Type 2 diabetes (T2D) significantly increases the risk for developing AD. Due to demographic projections of increases in T2D and an aging population, determining mechanisms through which these metabolic disturbances impair brain health should greatly improve the quality of life of a rapidly aging population. The facilitating effects of normal aging and a high fat diet on peripheral insulin resistance are well known. Much less is known about how neuronal glucose regulation and metabolism are affected under these conditions. The goal of the study proposed here is delineate age-related changes in glucose regulation in the hippocampus using young adult versus aged F344 rats. We will combine non-invasive magnetic resonance spectroscopy (MRS) and in vivo electrochemical recordings to validate a glucose tolerance test for the brain. We will determine whether glucose tolerance is impaired in the hippocampus under conditions of normal aging by testing one specific aim: Do aged rats exhibit impaired hippocampal glucose regulation following a bolus injection of glucose? The results of this study will be novel and will provide essential pilot data to lay the groundwork for a larger grant application to address the effects of insulin resistance and potential therapeutic agents on this process. Testing these and related hypotheses in a well-controlled preclinical model will yield valuable information regarding a looming public health issue.
Hoglund Brain Imaging Center, University of Kansas Medical Center
Considerable evidence demonstrates that recovery and outcomes after a traumatic brain injury (TBI) are worse in elderly than in younger patients. Moreover, results from our laboratory and others suggest that specific injury mechanisms are altered with age. We believe that mechanism-specific biomarkers visible on proton magnetic resonance spectroscopy (1H-MRS) represent a promising novel approach for elucidating mechanisms of TBI and for translating treatments from pre-clinical to clinical trials. Our current goal is 1) to determine the magnitude and time course of the metabolic and behavioral effects of TBI in an aged animal model, and 2) determine whether TBI in aged animals is sensitive to neuroprotective treatment with cyclosporine A (CsA).
Department of Neurology, University of Kansas Medical Center
Complex genetic and environmental mechanisms contribute to late-onset Alzheimer’s disease and the most consistently identified risk factor for AD is family history of dementia. Moreover, maternal transmission of AD is significantly more frequent than paternal transmission. We and others have recently linked maternal transmission of risk for AD to several brain imaging phenotypes. However, the patterns of transmission and biological mechanisms through which a family history of late-onset AD (LOAD) confers risk to offspring are not fully known. There is growing evidence that the mechanism for this maternal inheritance pattern may be related to transmission through mitochondrial DNA (mtDNA) alterations. Our overall goal is to test whether there is a relationship between mitochondrial sequence polymorphisms and imaging markers of risk AD. To do this, we will test for associations between brain imaging endophenotypes and mitochondrial haplogroups derived from138 mitochondrial polymorphisms in two large datasets with imaging, genetic, and behavioral data which, to our knowledge, has never been done.
KU Higuchi Bioscience Center
In this study, we will identify the role of amyloid binding alcohol dehydrogenate (ABAD) and amyloid in changing lipid and fatty acid metabolism in Alzheimer’s disease and show for the first time that there is a link between mechanisms that influence the function of mitochondria (i.e. increases in ABAD and Aβ) and changes in lipid metabolism. We will identify how they are linked and identified, a new phenomenon that occurs within mitochondria and is potentially controlled by the binding of Aβ to ABAD. Specifically, we will identify the role of ABAD in Aβ-mediated changes in lipid metabolism relevant to the pathogenesis of AD using novel transgenic mice to determine the effect of ABAD on Aβ-induced lipid metabolism. The outcomes of this project will have a significant impact on the AD research field, in particular synaptic mitochondria and lipid metabolism.
The objective of this study is to understand function of the O-GlcNAc cycling enzymes during mitochondrial impairment and Alzheimer’s progression. This research is driven by the hypothesis that the O-GlcNAc cycling enzymes protect against mitochondrial impairment and that alterations in O-GlcNAc signaling promote Alzheimer’s development. Support for this hypothesis comes from past work. A splice variant of O-GlcNAc transferase (OGT) localizes to mitochondria, increased mitochondrial O- GlcNAcylation impairs function and promotes apoptosis. The rationale behind this research is that once we understand the interplay between O-GlcNAcylation and mitochondrial regulation, then we can better understand the biology behind the etiology of Alzheimer’s disease. The regulation of biological processes by O-GlcNAcylation is a novel approach in understanding disease progress. We believe the research proposed in this application is innovative because it will address the involvement of O-GlcNAc signaling in the regulation of Alzheimer’s mitochondria.