Paul Kotzbauer - US grants

DESCRIPTION (provided by applicant): The candidate is an M.D./Ph.D neurologist who is currently a trainee in the Center for Neurodegenerative Disease Research. His goal is to develop additional research skills and experience needed to become an independent clinician scientist working to understand the pathogenesis of neurodegenerative diseases. The proposed research project focuses on neurodegeneration with brain iron accumulation (NBIA), which causes progressive impairment of speech, movement and cognition. At the neuropathological level, NBIA is characterized by iron accumulation, inclusion formation, signs of oxidative stress, and death of multiple neuronal populations. These features are also seen to varying degrees in other neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. Mutations in the gene for pantothenate kinase 2 (PanK2) were recently identified in a subset of NBIA cases. The PanK2 gene encodes an enzyme involved in coenzyme A (CoA) synthesis, a critical pathway linked to a number of cellular processes, including fatty acid synthesis, energy production, and possibly, synthesis of anti-oxidant molecules. The long term objectives of this project are to understand how PanK2 mutations lead to iron accumulation, oxidative stress, inclusion formation, and neuronal death. The proteolytic processing, mitochondrial localization and in vitro catalytic properties will by characterized for mutant Pank2 proteins and compared to the wild type human PanK2 protein. Cell culture systems will be established in which PanK2 expression is eliminated and in which wild type or mutant PanK2 proteins are over-expressed. Mice that lack PanK2 expression will also be generated. Cell lines and mice lacking PanK2 expression will be examined for changes in levels of biochemical intermediates hypothesized to be dependent on PanK2 function. Finally, neuronal and non-neuronal cells lacking PanK2 will be examined for signs of increased oxidative stress, susceptibility to oxidative injury, cellular and mitochondrial import of radio labeled iron, and inclusion formation.

DESCRIPTION (provided by applicant): Mutations in the PLA2G6 gene cause young onset neurodegenerative disorders classified as either infantile neuroaxonal dystrophy (INAD) or neurodegeneration with brain iron accumulation (NBIA). These two disorders with overlapping features involve progressive impairment of movement, speech and cognition. The PLA2G6 gene encodes group VIA calcium-independent phospholipase A2 (Pla2g6). Our previous studies indicate that human Pla2g6 hydrolyzes both phospholipids and lysophospholipids to produce free fatty acids, and that disease-associated mutations dramatically impair the catalytic activity of the protein. This predicts two potential pathological pathways in INAD/NBIA: accumulation of Pla2g6 substrates (phospholipids) and deficiency of Pla2g6 products (free fatty acids). Previous studies in cell lines also support a role for Pla2g6 in phospholipid and fatty acid homeostasis. Accumulation of Pla2g6 substrates explains a characteristic feature of the human disease - accumulation of membranes in pathological structures termed neuroaxonal spheroids. Our previously reported Pla2g6-KO mouse model recapitulates neuroaxonal spheroid formation as well as progressive neurological impairment of the human disorder. We will use Pla2g6-KO mice to test a therapeutic approach to increase the rate of fatty acid synthesis and uptake in order to compensate for impaired release of fatty acids caused by Pla2g6 mutations. This approach will utilize a small molecule liver X receptor (LXR) agonist. LXR's are nuclear receptor transcriptional activators of sterol regulatory element binding protein 1c (SREBP-1c) expression and also directly activate the expression of proteins involved in fatty acid synthesis and uptake. The LXR agonist will be administered to Pla2g6-KO and wildtype mice. The effect of the LXR agonist on lipogenic gene expression, fatty acid synthesis, and fatty acid uptake in brain tissue will be evaluated. The effect of the LXR agonist on progressive neurological impairment will be evaluated using the rotarod test and other behavioral tests of sensorimotor function, and by histopathological analysis of brain tissue. Positive results in these studies could be translated into new therapeutic approaches in humans by utilizing LXR agonists which are currently being developed for potential therapeutic effects in regulating lipid metabolism in other disorders.

Abstract People with Parkinson disease (PD) frequently develop dementia, which is associated with neocortical deposition of alpha-synuclein (?-syn) in Lewy bodies and Lewy neurites. In addition, neuronal loss and deposition of aggregated ?-syn also occurs in multiple subcortical nuclei including substantia nigra (dopaminergic), nucleus basalis of Meynert (cholinergic), locus coeruleus (noradrenergic) and dorsal raphe nuclei (serotonergic). Accumulation of ?-syn likely contributes to impaired function of cortical neurons, which may also be affected by widespread A? accumulation that occurs in approximately 60% of PD with dementia cases and widespread tau accumulation in fewer cases. However, the affected subcortical nuclei project rostrally to thalamic, striatal, limbic and neocortical regions, and the loss of innervation from these nuclei also may contribute to cognitive impairment in PD. We developed postmortem tissue analysis methods to quantify accumulation of fibrillar ?-syn, A? and tau, as well as the loss of innervating projections from dopaminergic, serotonergic, noradrenergic and cholinergic subcortical neurons. In this project we will collect autopsies from a longitudinal study of PD participants that measures cognitive, behavior, and gait function. We will sample thalamic, cerebellar, basal ganglia, limbic and neocortical regions from frozen brain tissue for each autopsy case and analyze the tissue with the following goals: 1) Determine the relationship between ?-syn, A? and tau deposition and the loss of dopaminergic, serotonergic, noradrenergic and cholinergic innervation. 2) Determine whether fibrillar protein deposition and loss of projections from subcortical nuclei relate to gait, global cognition and specific cognitive phenotypes, including: impaired attention, memory, visuospatial and executive function, fluctuations in attention, hallucinations and delusions. Defining the pathologic substrates for cognitive, behavior and gait impairment in PD will provide further guidance for therapeutic targets and outcome measures for therapeutic trials in PD.

Abstract Parkinson's Disease (PD) is defined by the accumulation of alpha-synuclein (Asyn) fibrils in neuronal cytoplasmic and neuritic inclusions known as Lewy bodies and Lewy neurites. The role of Asyn in pathogenesis is supported by the identification of dominant mutations in the gene encoding Asyn (SNCA) in rare familial versions of PD. PD progression, particularly the development of dementia in PD, is associated with more widespread deposition of Asyn throughout the brain, including neocortex. Multiple therapeutic approaches targeting Asyn accumulation are being pursued. A leading priority is to develop a PET imaging agent that can quantify the deposition of Asyn in living individuals, as a biomarker for target engagement in clinical studies. An Asyn PET imaging agent would also improve the accuracy of diagnosis for PD, and provide a biomarker for disease progression. We developed a new screening approach to identify novel compounds that can be pursued as leads for the development of an Asyn imaging agent. This new approach uses fluorescence measurements to identify a subset of natively fluorescent compounds in a commercial library. We then use fluorescence measurements to screen natively fluorescent compounds for binding Asyn fibrils in vitro followed by assessment of whether compounds bind to Asyn-containing Lewy bodies in postmortem PD brain tissue sections. A final step is to determine whether compounds selectively bind to Lewy bodies but do not bind to amyloid plaques or neurofibrillary tangles in postmortem brain tissue sections. The project will use this approach to screen 5000 fluorescent compounds. Compounds found to have the desired properties will be radiolabeled with tritium in order to further characterize their binding properties using radioligand binding assays and autoradiography. The compounds identified in the project can be used as leads in further studies to develop an Asyn imaging agent. Results from the project will also enable further optimization of this new screening approach to identify compounds with the binding properties needed for an imaging agent.

Parkinson?s disease (PD) is defined pathologically by the accumulation of alpha-synuclein (Asyn) fibrils in neuronal cytoplasmic and neuritic inclusions known as Lewy bodies and Lewy neurites. The role of Asyn in the pathogenesis of PD is supported by the identification of dominant mutations in the gene encoding Asyn (SNCA) in rare familial versions of PD. Dementia occurs frequently in PD. It sometimes begins at approximately the same time as motor symptoms (often referred to as dementia with Lewy bodies or DLB), or up to 20 years after motor symptoms begin (PD with dementia or PDD). The term Lewy body dementia (LBD) encompasses this spectrum of clinical presentations and is associated with widespread deposition of Asyn fibrils throughout the brain, particularly neocortex. Multiple therapeutic approaches targeting Asyn accumulation are being pursued. A further priority is to develop a PET imaging agent to quantify the deposition of Asyn in living individuals, as a biomarker for target engagement and disease progression. Understanding Asyn fibril structure in LBD can guide the development of Asyn-targeted therapies and imaging agents. In this project, we will use cryo-electron microscopy (cryo-EM) to determine atomic resolution structures of Asyn fibrils in LBD, in conjunction with solid-state NMR (SSNMR) for refinement of structures. We will analyze and compare structures of Asyn fibrils isolated from multiple subgroups of LBD autopsy cases defined by early versus late onset of dementia, as well as the presence or absence of co-occurring amyloid ? accumulation. We will also utilize cryo-electron tomography, SSNMR spectral analysis and new monoclonal antibodies to extend the analysis of Asyn fibril structure to additional autopsy cases. To promote the translation of these structural studies we will utilize cryo-EM to determine binding sites of leading candidates for PET imaging ligand and use fibril growth assays to identify specific amino acid residues in the Asyn protein that are important for fibril growth and stability.

ABSTRACT: NAPS2 BIOFLUID CORE REM sleep behavior disorder (RBD) is commonly a prodromal manifestation of diseases defined by pathologic alpha-synuclein (aSyn) protein accumulation (synucleinopathies). A large percentage of RBD patients are eventually diagnosed with Parkinson?s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), with varying rates of disease progression. Development and validation of biomarkers for RBD can improve the efficiency of future clinical trials by providing quantitative metrics for target engagement and drug efficacy. In the North American Prodromal Synucleinopathy Consortium on RBD, Stage 2 (NAPS2), the aims of the Biofluid Core will be 1) to oversee and coordinate [along with the National Centralized Repository for Alzheimer?s Disease and Related Dementias (NCRAD)] the collection, processing, and storage of serially collected plasma and cerebrospinal fluid (CSF) samples at the NAPS2 consortium Sites; 2) to perform assays of established neurodegenerative markers; and 3) to develop and test promising novel markers. The key biofluid markers include assays that correlate with neurodegeneration such as neurofilament light chain (NfL) in plasma and CSF and total tau in CSF, as well as measures that correlate with pathologic protein accumulation in CSF including total ?Syn, oligomeric ?Syn [including new protein misfolding cyclic amplification (PMCA) technology], A?42, A?40, and phosphorylated tau (p-tau181). Efforts on developing and testing promising novel markers will include exploration of catechols in the CSF, exploration of exosomal markers in plasma, and measurement of ?Syn oligomers in CSF by real-time quaking-induced conversion (RT- QuIC). The Biofluid Core will ensure scientific rigor through standardization of biofluid collection and use of innovative, state-of-the-art biofluid assays performed at laboratories with extensive prior experience. The Core will be directed by leaders in biofluid discovery and validation in synucleinopathies and other neurodegenerative diseases. The Core leads have collaborated with NAPS investigators on prior research studies in RBD and other synucleinopathies, and their prior experience and guidance will ensure consistency and standardization of planned biofluid assays as part of this consortium. All proposed fluid biomarker assays are backed by preliminary data and sound scientific evidence supporting their value in synucleinopathies. The Core will work closely with the Administrative, Clinical, and Database Management and Statistics (DMS) Cores, and along with the Genetics, PSG and Neuroimaging Cores, supply processed cross-sectional and longitudinal data of selected markers for the Project focused on predicting phenoconversion. The Core will also provide anonymized cross-sectional and longitudinal data for sharing with outside investigators.