LRRK2 as a target for the treatment of Parkinson’s disease

• Applicants: Professor Dr. Thomas Gasser; Professor Dr. Jared Sterneckert
• Subject Area: Molecular and Cellular Neurology and Neuropathology ; Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414868630

• Final Report Year: 2024

Final Report Abstract

Parkinson's disease (PD) is characterized by the degeneration of distal axonal termi-nals prior to soma, and disruption of protein quality control, including altered lysosomes. One of the most common causative mutations in PD is the gain-of-kinase-function mutation LRRK2 G2019S, and LRRK2-specific small molecule inhibitors have been developed as potential therapeutics. To facilitate clinical translation of these inhibitors, a better understanding of the role of LRRK2 in axon degeneration as well as non-invasive biomarkers for target engagement are needed. First, we developed a novel assay of lysosomal trafficking in human axons, which revealed that LRRK2 G2019S was associated with a subtle reduction in lysosomal transport speed, which was only partially rescued by LRRK2 kinase inhibitors. Phosphorylated Rab10 on distal axonal lysosomes was increased with mutant LRRK2, and over-expression of Rab10 mildly affected lysosomal trafficking. Interestingly, the severity of axonal trafficking phenotypes appeared to correlate with the severity of the clinical symptoms of the donors, but additional work would be needed to reinforce that link. Next, we characterized exosome-derived and cell-free microRNAs (miRNAs) as possible biomarkers for LRRK2-PD. Extracellular vesicles were isolated from induced pluripotent stem cell-derived human dopaminergic neurons. We detected over 2000 different micro-RNAs of which 56 were differentially expressed. We discovered a high correlation between changes in the cell-free and cellular miRNAomes and confirmed the dysregulation of let-7g-5p, miR-21-5p and miR-135a-5p in patient-derived cerebro-spinal fluid. Finally, we discovered that the influence of LRRK2 protein expression levels on the miRNAome could be greater than the mutation status. Following up on this work, we quantified the expression levels of 91 miRNAs via RT-qPCR in ten individuals with sporadic Parkinson’s disease, ten patients carrying a LRRK2 mutation and eleven healthy controls using both plasma and cerebrospinal fluid2. miR-29c-3p was differentially expressed between LRRK2 mutation carriers and sporadic cases, with miR-425-5p trending towards significance. Individuals clustered in principal component analysis along mutation status. Group affiliation was predicted with high accuracy. This approach could enable identification of patients that are likely to benefit from drugs targeting LRRK2. In light of small sample size, this approach needs to be validated in larger cohorts.

Publications

• Axonal Lysosomal Assays for Characterizing the Effects of LRRK2 G2019S. Biology, 13(1), 58.
  Bhatia, Priyanka; Bickle, Marc; Agrawal, Amay A.; Truss, Buster; Nikolaidi, Aikaterina; Brockmann, Kathrin; Reinhardt, Lydia; Vogel, Stefanie; Szegoe, Eva M.; Pal, Arun; Hermann, Andreas; Mikicic, Ivan; Yun, Maximina; Falkenburger, Björn & Sterneckert, Jared
  
• The Cellular and Extra-Cellular Proteomic Signature of Human Dopaminergic Neurons Carrying the LRRK2 G2019S Mutation. openRxiv.
  Knab, Felix; Guaitoli, Giambattista; Jarboui, Mohamed Ali; von Zweydorf, Felix; Isik, Fatma Busra; Klose, Franziska; Rajkumar, Anto Praveen; Gasser, Thomas & Gloeckner, Christian Johannes
  
• Using Extracellular miRNA Signatures to Identify Patients with LRRK2-Related Parkinson’s Disease. Journal of Parkinson’s Disease, 14(5), 977-991.
  Braunger, Luca Jannik; Knab, Felix & Gasser, Thomas