Paula Desplats - US grants

DESCRIPTION (provided by applicant): Currently over 30 million people live with HIV worldwide. In the US, the aging population represents one of the fastest growing groups with HIV. The Center for Disease Control estimates that by the year 2015, half of all Americans living with HIV will be over the age of 50. The mechanisms of neurodegeneration in aged individuals are not completely understood, however HIV activates apoptotic pathways, dysregulates calcium homeostasis and promotes oxidative stress. Moreover, recent studies have shown that HIV proteins might interfere with clearance pathways such as autophagy, a pathway necessary for protein quality control and elimination of defective older intracellular organelles. Deficits i autophagy have been described in Alzheimer's Disease (AD), Parkinson's Disease (PD) and other aging-related disorders, similarly, neurodegeneration has been linked to defects in autophagy in patients with HIV. We have recently shown that abnormal functioning of the autophagy pathway is associated with progressive accumulation of Amyloid-beta (A¿), ¿-synuclein (¿-syn) and Tau in the CNS of aged HIV human cases and in transgenic (tg) mice expressing HIV-gp120 protein (GFAP-gp120 tg). In this context our hypothesis is that HIV proteins such as Nef might interfere with autophagy by interacting with components of the autophagocytic pathway such as Beclin1. In aged patients with chronic HIV infection, this might result in reduced clearance of neurotoxic proteins and neurodegeneration. The main objectives of this proposal will be to a) better understand the mechanisms through which HIV proteins interfere with autophagy leading to protein accumulation and neurotoxicity, and b) to determine whether activation of the autophagy pathway is neuroprotective in preclinical models of HIV neurotoxicity and aging. For this purpose we propose the following Aims: Aim 1: To analyze interactions between HIV proteins and components of the autophagy pathway in brains of aged patients with chronic HIV infection. Aim 2: To investigate the role of HIV proteins in the cellular mechanisms of autophagy dysfunction and neurotoxicity. Aim 3. To determine whether autophagy activation in vivo ameliorates neurodegenerative and behavioral deficits in aged transgenic rodent models of HIV neurotoxicity. This project has the potential to further elucidate the role of autophagy as key downstream mediator of HIV-protein neurotoxicity during aging, which could lead to the development of new therapies and models of HIV-associated neurodegeneration and neuroprotection. Since alterations in autophagy are also present in AD and PD, this project may have broader applications for therapeutic advancements in other age-related neurodegenerative disorders.

SUMMARY Lewy body diseases, characterized by the accumulation of ?-synuclein in Lewy body structures, encompass a group of disorders with wide clinico-pathological variation, including Parkinson's disease dementia (PDD) and Dementia with Lewy Bodies (DLB). Most patients with a dominant dementia have cortical amyloid deposition, and several retrospective studies suggest that distribution and severity of Lewy body pathology impacts on clinical phenotype. Differentiation between the main synucleinopathies is based on the type and timing of clinical manifestations, with predominance of extrapyramidal motor features in PD patients and dementia in DLB cases; however, in some patients, appearance of dementia and motor impairments temporally overlap, confounding diagnosis. The lack of specific biomarkers and the co-occurrence of multiple concurring neurodegenerative syndromes in elder patients hamper determination of clinical subtypes. Epigenetic alterations, including DNA methylation and histone post-translational modifications are emerging as important contributors to neurodegenerative pathology as they have a major impact on modulating brain transcriptomes. We have previously reported alterations in DNA methylation associated with PD pathology, however, the precise epigenetic changes associated with Lewy body pathology and progression are not yet defined. Importantly, despite the impact that these alterations could potentially have on disease trajectory, they have been overlooked in the design of biomarkers and as potential outcome measures. We propose to conduct an exploratory study of DNA methylation patterns associated with DLB and PDD that will provide crucial preliminary data supporting larger studies. Importantly, we will investigate specific methylation changes in blood, searching for unique signatures that may discriminate closely related Lewy Body diseases. Development of a biomarker that aids in diagnosis of patients at early stages of neurodegeneration and that differentially diagnose cases presenting overlapping symptoms could ultimately improve disease management and therapeutic outcomes.

? DESCRIPTION (provided by applicant): Synucleonopathies are a group of neurodegenerative disorders that affect over 1.5 million people in the US. Multiple system atrophy (MSA) is a fatal, rapidly progressive synucleonopathy characterized by parkinsonism and oligodendroglial accumulation of ?-synuclein (?-syn). While considerable effort has been devoted at understanding the pathogenesis of Parkinson's Disease, less is known about MSA and the mechanisms through which ?-syn accumulates in oligodendroglial cells, resulting in neurodegenerative pathology, is not completely clear. One possibility is that autophagy failure could lead to ?-syn propagation from neurons to oligodendroglial cells. We recently found that in MSA microRNA (miR-101, miR-30a, miR183, miR-96) that regulate autophagy are affected. The HYPOTHESIS is that miRNA dysregulation in MSA might down-regulate autophagy, which in turn results in defective ?-syn clearance with the consequent propagation from neurons to glia. The OBJECTIVES will be to better understand the mechanisms through which alterations in autophagy- related miRNAs are involved in the pathogenesis of MSA and to evaluate the potential value of modulating miRNA's as a novel therapeutical approach for MSA. For this purpose we will utilize a combined strategy including studies in unique mixed cell cultures in chambers, transgenic mouse models of MSA and brain tissues from MSA patients from multiple sites. The AIMS are: ONE. To investigate in mixed neuron- oligodendroglial cell cultures the mechanisms through which alterations in miRNAs might lead to ?-syn propagation into glial cells. TWO. To determine in transgenic models of MSA if modulating miRNAs that regulate autophagy ameliorate the ?-syn pathology and spreading. THREE. To analyze the regional relationship between alterations in specific miRNAs and autophagy targets in MSA. These goals are in agreement with the NINDS 2014 PD Basic Research recommendations. Finding a link between miRNA dysregulation, autophagy deficits, and ?-syn spreading will shed light on pathogenesis of MSA, and will open the door for the study of these interactions in other neurodegenerative disorders. These studies could also lead to the development of novel therapeutical strategies for MSA.

Summary Alzheimer?s disease (AD) is a devastating neurodegenerative disorder affecting the lives of more than 5 million Americans and their families, and is the biggest forthcoming health challenge. AD is a multifactorial disorder manifested clinically by progressive memory loss, decline in cognitive functions and ultimately leading to dementia. Despite being the subject of intense research, there is no cure for AD, therefore, identifying therapies that can reduce disease progression at early stages is critical. Circadian impairment is a major feature of Alzheimer?s disease. Behavioral circadian alterations, known as sundowning, are experienced by more than 80% of patients and represent the leading factor for hospitalization and nursing home placement in AD. New research suggest that circadian disruption occurs early during disease progression and contributes to neurodegeneration, but the pathways that mediate the effects of clock dysfunction on AD pathophysiology are not well characterized yet. The proposed work will investigate the epigenome as the target of circadian deregulation. Circadian rhythms are generated by oscillation of clock genes, including BMAL1, in transcription/translation feedback loops and epigenetic mechanisms are deeply involved in their regulation. We previously reported alterations in rhythmic DNA methylation of clock genes in AD brains and identified BMAL1 as a regulator of methylation. While ample evidence demonstrates the disruption of DNA methylation in AD, the potential cross- talk between circadian dysfunction and epigenetic alterations in mediating AD pathology is yet unknown. We now propose to apply a step-wise approach starting by the identification of alterations in chromatin dynamics dictated by the circadian clock; and narrowing down to the expression of specific genes whose deregulation may trigger neurodegeneration. This work will apply cutting-edge technology to generate temporal maps of genome-wide chromatin accessibility, DNA methylation and transcription in the mouse brain in the context of circadian disruption and AD pathology. In addition, we will evaluate the mechanisms that mediate the beneficial effects of the small molecule Nobiletin (NOB) in AD mouse models, focusing on NOB activity as circadian-enhancer. These studies will define NOB targets of action in the brain and will re-evaluate their potential as disease modifying therapy. Understanding these molecular pathways may unravel novel targets and timing for improved interventions. As treatments curing or even postponing AD remain yet elusive, prolonging patient independence and daily functioning might represent a major option in clinical care.