The role of SCARB2 as susceptibility factor in Parkinson's disease
MOVEMENT DISORDERS
Authors: Hopfner, Franziska; Schulte, Eva C.; Mollenhauer, Brit; Bereznai, Benjamin; Knauf, Franziska; Lichtner, Peter; Zimprich, Alexander; Haubenberger, Dietrich; Pirker, Walter; Bruecke, Thomas; Peters, Annette; Gieger, Christian; Kuhlenbaeumer, Gregor; Trenkwalder, Claudia; Winkelmann, Juliane
Abstract
Background Genetic variation in the glucocerebrosidase (GBA) gene is strongly associated with Parkinson's disease (PD). Transport of glucocerebrosidase to the lysosome involves the protein encoded by the SCARB2 gene. An association between the common SNP rs6812193, upstream of SCARB2, and PD has been reported previously. The role of exonic variants in the SCARB2 gene in PD has not been examined. Methods We studied the role of exonic variants in SCARB2 and tried to replicate the association between the SNP rs6812193 and PD in a German and Austrian sample. Screening of all SCARB2 exons by high-resolution melting curve analysis was performed in 376 German PD patients. The SNP rs6812193 was analyzed in 984 PD patients and 1014 general population controls. Results We identified no novel exonic variants in SCARB2 but confirmed the association between SNP rs6812193 and PD (OR, 0.86; P=.02). (c) 2013 Movement Disorder Society
Dysregulated Lipid Metabolism and Its Role in alpha-Synucleinopathy in Parkinson's Disease
FRONTIERS IN NEUROSCIENCE
Authors: Alecu, Irina; Bennett, Steffany A. L.
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease, the main pathological hallmark of which is the accumulation of alpha-synuclein (alpha-syn) and the formation of filamentous aggregates called Lewy bodies in the brainstem, limbic system, and cortical areas. Lipidomics is a newly emerging field which can provide fresh insights and new answers that will enhance our capacity for early diagnosis, tracking disease progression, predicting critical endpoints, and identifying risk in pre-symptomatic persons. In recent years, lipids have been implicated in many aspects of PD pathology. Biophysical and lipidomic studies have demonstrated that alpha-syn binds preferentially not only to specific lipid families but also to specific molecular species and that these lipid-protein complexes enhance its interaction with synaptic membranes, influence its oligomerization and aggregation, and interfere with the catalytic activity of cytoplasmic lipid enzymes and lysosomal lipases, thereby affecting lipid metabolism. The genetic link between aberrant lipid metabolism and PD is even more direct, with mutations in GBA and SMPD1 enhancing PD risk in humans and loss of GALC function increasing alpha-syn aggregation and accumulation in experimental murine models. Moreover, a number of lipidomic studies have reported PD-specific lipid alterations in both patient brains and plasma, including alterations in the lipid composition of lipid rafts in the frontal cortex. A further aspect of lipid dysregulation promoting PD pathogenesis is oxidative stress and inflammation, with proinflammatory lipid mediators such as platelet activating factors (PAFs) playing key roles in arbitrating the progressive neurodegeneration seen in PD linked to alpha-syn intracellular trafficking. Lastly, there are a number of genetic risk factors of PD which are involved in normal lipid metabolism and function. Genes such as PLA2G6 and SCARB2, which are involved in glycerophospholipid and sphingolipid metabolism either directly or indirectly are associated with risk of PD. This review seeks to describe these facets of metabolic lipid dysregulation as they relate to PD pathology and potential pathomechanisms involved in disease progression, while highlighting incongruous findings and gaps in knowledge that necessitate further research.