Background: Parkinson's disease (PD) is a movement neurodegenerative disorder characterized by death of dopaminergic neurons in the substantia nigra pars compacta of the brain that leads to movement impairments including bradykinesia, resting tremor, postural instability and rigidity. Mutations in several genes have been associated with familial PD, such as parkin, pink, DJ-1, LRKK2 and synuclein. Lately, mutations in the GBA gene were recognized as a major cause for the development of PD.Mutations in the GBA gene, which encodes for lysosomal β-glucocerebrosidase (GCase), lead to Gaucher disease (GD), an autosomal recessive sphingolipidosis characterized by accumulation of glucosylceramide, mainly in monocyte-derived cells. It is a heterogeneous disease, with Type 1 patients that do not present any primary neurological signs, and Type 2 or Type 3 patients who suffer from a neurological disease. The propensity of type 1 GD patients and carriers of GD mutations to develop PD is significantly higher than that of the non-GD population.We have shown in the past that parkin and mutant GCase, expressed in heterologous systems, interact with each other, and that normal but not mutant parkin mediates K48-dependent proteasomal degradation of mutant GCase variants. Methods. We tested possible competition between mutant GCase and PARIS or ARTS on the E3 ubiquitin ligase parkin, using coimmunoprecipitation assays and quantitative real-time PCR. Results: We show that endogenous mutant GCase variants associate with parkin and undergo parkin-dependent degradation. Mutant GCase competes with the known parkin substrates PARIS and ARTS, whose accumulation leads to apoptosis. Dopaminergic cells expressing mutant GCase are more susceptible to apoptotic stimuli than dopaminergic cells expressing normal GCase, present increased cleavage of caspase 3 and caspase 9 levels and undergo cell death. Conclusions: Our results imply that presence of mutant GCase leads to accumulation of parkin substrates like PARIS and ARTS, which may cause apoptotic death of cells.
Bibliographical noteFunding Information:
We thank Dr. Mirella Filocamo (Centro di Diagnostica Genetica e Biochimica delle Malattie Metaboliche, IRCCS G. Gaslini, Genova, Italy) and Dr. Roscoe Brady (NIH, Bethesda, MD, USA) for GD derived skin fibroblasts and Dr. Eli Sprecher (Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel) for normal fibroblasts. We thank Dr. Ted M. Dawson (Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA) for a kind gift of the PARIS expressing plasmid. We would like to express our appreciation to Dr. Doron Calo, Research Authority, Tel Aviv University, for critical reading of the manuscript. This work was supported by a grant from The Israeli Ministry of Health (MH). Inna Bendikov-Bar was the recipient of Gertner and SAIA fellowships, administered by Tel Aviv University.
- Gaucher disease
- Parkinson disease
ASJC Scopus subject areas
- Pharmacology (medical)