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Background: Mutations in LRRK2 encoding leucine-rich repeat kinase 2 are thus far the most frequent genetic cause associated with autosomal dominant and idiopathic Parkinson's disease (PD). To examine whether LRRK2 is directly associated with neuropathology of PD and other related disorders, we analyzed LRRK2 in brains of patients affected by PD and dementia with Lewy bodies (DLB) using highly specific antibodies to LRRK2. Results: We demonstrated that anti-LRRK2 antibodies strongly labelled brainstem and cortical Lewy bodies, the pathological hallmarks of PD and DLB, respectively. In addition, anti-LRRK2 also labelled brain vasculature, axons, and neuronal cell bodies. Interestingly, the immunocytochemical profile of LRRK2 varied with different antibodies depending upon specific antigenic sites along the LRRK2 protein. All anti-LRRK2 antibodies tested that were raised against various regions of LRRK2, were found to be immunoreactive to recombinant LRRK2 on Western blots. However, only the antibodies raised against the N-terminal and C-terminal regions of LRRK2, but not the regions containing folded protein domains, were positive in immunolabeling of Lewy bodies, suggesting a differential exposure of specific antigenic sites of LRRK2 on tissue sections. Conclusion: We conclude that LRRK2 is a component of Lewy bodies in both PD and DLB, and therefore plays an important role in the Lewy body formation and disease pathogenesis. Information on the cellular localization of LRRK2 under normal and pathological conditions will deepen our understanding of its functions and molecular pathways relevant to the progression of PD and related disorders. [ABSTRACT FROM AUTHOR]

Background: Mutations in leucine-rich repeat kinase 2 (LRRK2) are thus far the most frequent genetic cause associated with autosomal dominant and idiopathic Parkinson’s disease. Objective:To examine whether LRRK2 is directly associated with the pathological structures of Parkinson’s disease, dementia with Lewy bodies, and other related disorders using highly specific antibodies to LRRK2. Results:LRRK2 antibodies strongly labeled brainstem and cortical Lewy bodies, the pathological hallmarks of Parkinson’s disease and dementia with Lewy bodies, respectively. We found that 20–100% (mean 60%) of α-synuclein-positive Lewy bodies contained LRRK2. While antibodies raised against various regions of LRRK2 were previously shown to label recombinant LRRK2 on Western blots, only antibodies raised against the N- and C-termini, but not the regions containing folded protein domains of LRRK2, immunolabeled Lewy bodies. In Alzheimer’s disease, Hirano bodies were found to contain LRRK2 and the neurofibrillary tangles in progressive supranuclear palsy remained unlabeled. Conclusions: Information on the cellular localization of LRRK2 under normal and pathological conditions will deepen our understanding of its functions and molecular pathways relevant to the progression of Parkinson’s disease and related disorders. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Introduction LRRK2 G2019S mutation carriers with Parkinson's disease (PD) have been generally indistinguishable from those with idiopathic PD, with the exception of variable differences in some motor and non-motor domains, including cognition, gait, and balance. LRRK2 G2019S is amongst the most common genetic etiologies for PD, particularly in Ashkenazi Jewish (AJ) populations. Methods This cross-sectional data collection study sought to clarify the phenotype of LRRK2 G2019S mutation carriers with PD. Primary endpoints were the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS) and Montreal Cognitive Assessment (MoCA). Other motor and non-motor data were also assessed. The Mann-Whitney U Test was utilized to compare LRRK2 G2019S carriers with PD (LRRK2+) with non-carrier PD controls who were matched for age, gender, education, and PD duration. Survival analyses and log rank tests were utilized to compare interval from onset of PD to development of motor and non-motor complications. Results We screened 251 subjects and 231 completed the study, of whom 9 were LRRK2+, including 7 AJ subjects. 22.73% of AJ subjects with a family history of PD (FH) and 12.96% of AJ subjects without a FH were LRRK2+. There were no significant differences between the 9 LRRK2+ subjects and 19 matched PD controls in MDS-UPDRS, MoCA, or other motor and non-motor endpoints. Conclusion Prevalence of the LRRK2 G2019S mutation in AJ and non-AJ subjects in our study population in Cleveland, Ohio was comparable to other clinical studies. There were no significant motor or non-motor differences between LRRK2+ PD and matched PD controls. [ABSTRACT FROM AUTHOR]

Abstract: Human leucine-rich repeat kinase 2 (LRRK2) is a novel kinase belonging to the ROCO protein superfamily (Ras of complex proteins (Roc) with a C-terminal of Roc domain). This large complex protein of 280kDa contains several functional domains including leucine-rich repeats, Ras-related GTPase, mitogen-activated protein kinase kinase kinase (MAPKKK), and WD40 repeats. While definitive functions of LRRK2 have yet to be described, the domain structure of LRRK2 suggests that it plays an important role in the regulation of signal transduction cascades through its dual enzymatic activities of GTPase and MAPKKK. Moreover, mutations in LRRK2 have been found to be thus far the most frequent cause of late-onset familial and idiopathic Parkinson''s disease. Further investigations should allow for the elucidation of how pathogenic mutations trigger changes in the structure and function of LRRK2 that lead to aberrant signal transduction and neurodegeneration in Parkinson''s disease. [Copyright &y& Elsevier]

Abstract: Mutations in LRRK2 are thus far the most frequent known cause of autosomal dominant and idiopathic Parkinson''s disease (PD) with prevalent mutations being found within the GTPase (R1441C/G) and kinase (G2019S) domains. Previous in vitro studies have revealed that R1441C and G2019S mutations are associated with increased kinase activity. To better understand LRRK2-linked PD pathogenesis in vivo, we have generated transgenic C. elegans overexpressing human LRRK2 wild type, R1441C and G2019S in dopaminergic (DA) neurons. Overexpression of these LRRK2 proteins causes age-dependent DA neurodegeneration, behavioral deficits, and locomotor dysfunction that are accompanied by a reduction of dopamine levels in vivo. In comparison, R1441C and G2019S mutants cause more severe phenotypes than the wild type protein. Interestingly, treatment with exogenous dopamine rescues the LRRK2-induced behavioral and locomotor phenotypes. In contrast, expression of the GTP binding defective mutant, K1347A, or knockout of the C. elegans LRRK2 homolog, LRK-1, prevents the LRRK2-induced neurodegeneration and behavioral abnormalities. Hence, our transgenic LRRK2 C. elegans models recapitulate key features of PD including progressive neurodegeneration, impairment of dopamine-dependent behavior and locomotor function, and reduction in dopamine levels. Furthermore, our findings provide strong support for the critical role of GTPase/kinase activity in LRRK2-linked pathologies. These invertebrate models will be useful for studying pathogenesis of PD and for development of potential therapeutics for the disease. [Copyright &y& Elsevier]

Abstract: Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the leading cause of autosomal dominant Parkinson’s disease (PD). LRRK2, a member of the ROCO protein family, contains both Ras GTPase-like (Roc) and kinase (MAPKKK) domains, as well as other functional motifs. Here, we have identified LRRK2 as the first mammalian ROCO protein that is an authentic and functional GTPase, defined by the ability to bind GTP and undergo intrinsic GTP hydrolysis. Furthermore, the Roc domain is sufficient for this native GTPase activity and binds and hydrolyzes GTP indistinguishably from the Ras-related small GTPase, Rac1. The PD-associated mutation, R1441C, located within the Roc domain, leads to an increase in LRRK2 kinase activity and a decrease in the rate of GTP hydrolysis, compared to the wild-type protein, in an in vitro assay. This finding suggests that the R1441C mutation may help stabilize an activated state of LRRK2. Additionally, LRRK2-mediated phosphorylation is stimulated upon binding of non-hydrolyzable GTP analogs, suggesting that LRRK2 is an MAPKKK-activated intramolecularly by its own GTPase. Since GTPases and MAPKKKs are upstream regulators of multiple signal transduction cascades, LRRK2 may play a central role in integrating pathways involved in neuronal cell signaling and the pathogenesis of PD. [Copyright &y& Elsevier]