Parkinson's disease (PD) is a major cause of morbidity and mortality in the United States. The etiology is largely unknown and therapies that slow or halt the relentless progression of disease do not yet exist. Dominant missense mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common known specific cause of PD, and LRRK2 mutations associate with disease phenotypes that mimic typical late-onset disease. LRRK2 encodes an unusually large protein kinase, and the most common mutations that cause PD may up-regulate LRRK2 kinase activity. Since small molecule protein kinase inhibitors have made an impact on the treatment of multiple types of cancer, LRRK2 represents a potential therapeutic target for the treatment of PD should kinase activity correlate with neurodegeneration in model systems. Through the design of novel high capacity viral vectors encoding the LRRK2 open-reading frame modified with either PD-causing mutations that up-regulate kinase activity or mutations that inactivate kinase activity, the importance of LRRK2 kinase activity in directing dopaminergic neurodegeneration in vivo will be determined. The specific effects of pathogenic mutations on LRRK2 function and activity are not fully understood, but may allow for a straightforward route to decipher disease-related LRRK2 functions. LRRK2 encodes an active kinase and GTPase protein, a near unique arrangement in the human proteome, and pathogenic mutations can occur in both enzymatic domains. Oligomerization and dimerization are intrinsic mechanisms of regulation for many protein kinases and GTPase proteins. We will biochemically characterize oligomeric and dimeric LRRK2 protein and determine the effect of pathogenic LRRK2 mutations on the composition of LRRK2 conformations and associated activities. Further, we develop technology that may allow direct visualization of LRRK2 enzyme activity in living cells and explore both inhibition and activation of kinase activity. Through the resolution of LRRK2 autophosphorylation sites, we have uncovered an unexpected complexity in the probable reciprocal regulation of kinase and GTPase activities, where kinase activity may play a dual role in mediating GTPase-dependent LRRK2 dimerization and kinase-mediated phosphorylation of substrates. We will characterize the role of LRRK2 autophosphorylation on enzymatic regulation and how PD-associated mutations perturb normal activities.

Public Health Relevance

The biochemical mechanisms underlying disease-causing mutations in the LRRK2 gene, currently the most common known cause of Parkinson's disease, are explored in order to determine potential targets for therapeutics development. Identification of cellular pathways linked with LRRK2-mediated neurodegeneration will further enhance our understanding of Parkinson's disease and spur the development of rationally designed drugs that slow or halt the disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS064934-04
Application #
8521400
Study Section
Cell Death in Neurodegeneration Study Section (CDIN)
Program Officer
Sieber, Beth-Anne
Project Start
2010-09-01
Project End
2015-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
4
Fiscal Year
2013
Total Cost
$303,067
Indirect Cost
$96,195
Name
University of Alabama Birmingham
Department
Neurology
Type
Schools of Medicine
DUNS #
063690705
City
Birmingham
State
AL
Country
United States
Zip Code
35294
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West, Andrew B; Cowell, Rita M; Daher, João P L et al. (2014) Differential LRRK2 expression in the cortex, striatum, and substantia nigra in transgenic and nontransgenic rodents. J Comp Neurol 522:2465-80
Liu, Zhiyong; Galemmo Jr, Robert A; Fraser, Kyle B et al. (2014) Unique functional and structural properties of the LRRK2 protein ATP-binding pocket. J Biol Chem 289:32937-51
Volpicelli-Daley, Laura A; Gamble, Karen L; Schultheiss, Christine E et al. (2014) Formation of ?-synuclein Lewy neurite-like aggregates in axons impedes the transport of distinct endosomes. Mol Biol Cell 25:4010-23
Davies, Paul; Hinkle, Kelly M; Sukar, Nour N et al. (2013) Comprehensive characterization and optimization of anti-LRRK2 (leucine-rich repeat kinase 2) monoclonal antibodies. Biochem J 453:101-13
Fraser, Kyle B; Moehle, Mark S; Daher, Joao P L et al. (2013) LRRK2 secretion in exosomes is regulated by 14-3-3. Hum Mol Genet 22:4988-5000
Stafa, Klodjan; Trancikova, Alzbeta; Webber, Philip J et al. (2012) GTPase activity and neuronal toxicity of Parkinson's disease-associated LRRK2 is regulated by ArfGAP1. PLoS Genet 8:e1002526
Moehle, Mark S; Webber, Philip J; Tse, Tonia et al. (2012) LRRK2 inhibition attenuates microglial inflammatory responses. J Neurosci 32:1602-11

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