Leucine-rich repeat kinase 2 (LRRK2) is a multifunctional protein necessary for maintaining cellular homeostasis. Mutations in the LRRK2 gene have been implicated in several diseases, including Parkinson’s disease (PD), Alzheimer´s disease (AD), and amyotrophic lateral sclerosis (ALS) among others. LRRK2 mutations are causative for monogenetic late-onset PD with autosomal dominant inheritance. The G2019S gain of function mutation within the kinase domain is the most common LRRK2 mutation, and accounts for up to 2% of sporadic PD and up to 6% of familial PD.
LRRK2 G2019S rats overexpress mutant human LRRK2. The model is valuable for testing the efficacy of LRRK2 inhibitors. Ten weeks old LRRK2 G2019S rats exhibit significantly increased total LRRK2 levels (Figure 1A), as well as increased pS935 LRRK2 levels (Figure 1B), while pS1292 LRRK2 levels remain unchanged (Figure 1C).
Selective LRRK2 inhibitors such as MLi-2 have been proposed as promising compounds for the treatment of PD and monitoring dephosphorylation of LRRK2 pS935 has become the principal marker to assess the in vivo efficacy of LRRK2 inhibitors. We have shown that while total LRRK2 levels are not affected by MLi-2 treatment (Figure 2A), LRRK2 pS935 and pS1292 levels are significantly reduced for at least 8 and 2 hours, respectively (Figure 2B and C).
The most important characteristics of LRRK2 G2019S rats are:
- Unchanged pS1292 LRRK2 levels
- Increased total and pS935 LRRK2 levels
- Phosphorylation status modifiable by LRRK2 inhibitor MLi-2
- Unchanged basal motor function and cognitive abilities
Figure 1. Total and phospho-LRRK2 levels in LRRK2 G2019S rats. Ten weeks old LRRK2 G2019S rats were evaluated for total LRRK2 (A), LRRK2 pS935 (B), and LRRK2 pS1292 (C) levels using a Mesoscale Discovery (MSD) immunosorbent assay. Mean + SEM; n = 3-4 per group, unpaired t-test. ***p<0.001, ns, not significant.
Figure 2: Time-dependent inhibition of LRRK2 kinase activity upon single oral MLi-2 treatment. LRRK2 G2019S rats received a single dose of MLi-2 or vehicle and were sacrificed 2, 8, or 24 hours later. Brain levels of total LRRK2 (A), LRRK2 pS935 (B), and LRRK2 pS1292 (C) were quantified by MSD immunosorbent assay. Mean + SEM; n = 3-4 per group. Two-way ANOVA with Bonferroni‘s post hoc test; **p<0.01, ***p<0.001; ns, not significant.
Scantox offers a custom-tailored study design for the LRRK2 G2019S rat model, and we are flexible to accommodate your special interests. We are also available to provide advice and propose study designs. The LRRK2 G2019S rats exhibit a relevant PD phenotype at 10 weeks of age, allowing for a remarkably fast processing time for your study. Additionally, non-transgenic littermates are available as control animals, which are necessary for proper study design.
We are happy to evaluate the efficacy of your compound in the LRRK2 G2019S rat model!