It should be noted that collection of the urine samples from the NHPs was performed by emptying the bladder using a catheter at the start of the experiment and collecting again at the given time point. We used western blot with antibodies directed against total and phosphorylated LRRK2, Rab8, and Rab10 to measure these LRRK2 and Rab epitopes in uEVs. We confirm the presence of LRRK2 and Rab8/10 in human and NHP uEVs, including total LRRK2 as well as phospho-LRRK2, phospho-Rab8 and phospho-Rab10. We also confirm LRRK2 and Rab expression in rodent uEVs. We quantified LRRK2 and Rab epitopes in human cohorts and found in a first CGK 733 cohort that pS1292-LRRK2 levels were elevated in individuals carrying the LRRK2 G2019S mutation, without significant differences between healthy and PD groups, whether for LRRK2 G2019S carriers or not. In a CGK 733 second cohort, we found that PD was associated to increased Rab8 levels and decreased pS910-LRRK2 and pS935-LRRK2. In animals, acute treatment with LRRK2 kinase inhibitors led to decreased pT73-Rab10. The identification of changes CGK 733 in Rab8 and LRRK2 phosphorylation at S910 and S935 heterologous phosphosites in uEVs of PD patients and pT73-Rab10 in inhibitor-dosed animals further reinforces the potential of the LRRK2-Rab pathway as a source of PD and pharmacodynamic biomarkers in uEVs. Subject terms: Diagnostic markers, Parkinson’s disease, Parkinson’s disease Introduction One of the key challenges in Parkinsons disease research today is usually to identify biomarkers for the early diagnosis of Parkinsons disease (PD), for the monitoring of the progression of PD pathology and for the assessment of therapeutic interventions. Indeed, biological biomarkers for PD are currently unavailable in routine clinical practice. Much hope in developing PD biomarkers is usually vested in exploiting findings from biological studies of genetic determinants of PD. These same genetic determinants are also the basis for a growing number of novel therapeutic strategies with disease-modifying potential. Some examples of therapies based on PD genetic determinants that have been developed in preclinical models and are currently in clinical trials include strategies to counter the aggregation of alpha-synuclein, encoded by the gene1, or to inhibit the kinase activity of leucine-rich repeat kinase 2 (LRRK2)2. These approaches are expected to block the further development of disease, and it is therefore beneficial to detect the disease in the earliest stage possible. Unfortunately, current diagnostic approaches are only capable of detecting relatively late stages of PD, encodes a large protein of 2527 amino acids, harboring multiple domains including a GTPase domain name, a kinase domain name and other domains with a role in protein-protein interactions. Linkage studies have identified several mutations in the coding sequence that segregate with autosomal dominant PD, while genome-wide association studies (GWAS) have revealed that genomic variation at the LRRK2 locus is usually associated with CGK 733 sporadic PD, demonstrating that LRRK2 is usually implicated in a large proportion of PD cases. Research efforts of recent years have elucidated several aspects of LRRK2 function and signaling that can be measured as a marker of LRRK2 activity or status. For instance, LRRK2 is usually a kinase Rabbit Polyclonal to FGFR1 that autophosphorylates itself at multiple serines and threonines in or near its ROC domain name, including at Ser1292 whose phosphorylation is considered a marker for LRRK2 autophosphorylation. LRRK2 also displays other phosphorylation sites resulting from heterologous phosphorylation, specifically at sites S910-S935-S955-S973 in the ANK-LRR interdomain region. CGK 733 These sites mediate conversation with 14-3-3 proteins and may constitute an activation or inactivation step in LRRK2 cellular activity. Downstream of LRRK2, several of the Rab family small GTPases involved in membrane trafficking are robust substrates of LRRK2, including Rab8A and Rab10. Several pieces of evidence point to the potential of measuring LRRK2 pathway activity to monitor disease or target engagement, including total or phosphorylated levels of LRRK2 and total or phosphorylated levels of LRRK2s Rab substrates (reviewed in Rideout et al.3). LRRK2 is usually expressed.
