Expression of FLAG-tagged full-length human mutant (G2019S or G2019S/D1994N) LRRK2 gene under the control of a synapsin-1 promoter using recombinant human serotype 5 adenoviral vector (rAd5).
Endogenous rat LRRK2: yes
Corresponding human genotype: The G2019S substitution in the LRRK2 gene is believed to be the most common mutation associated with Parkinson’s disease. It is located in the kinase domain of the protein.
Mutated gene: LRRK2
Injection coordinates: Intrastriatal – two deposition sites along three needle tracts: AP 0.48/ ML −2.4/ DV −4.8 and −6.0; AP 0.48/ ML −3.2/ DV −4.8 and −6.0; AP 0.48/ ML −4.0/ DV −4.8 and −6.0.
Volume of injection and viral titer: Two microliters of virus per site at a concentration of 2.3 × 109 vp/μl
Differences in transgene expression is observed depending on the study. The transgene is always expressed in the striatum but retrograde transport to the SN is reported in one study (Dusonchet 2011) but not the other (Tsika 2015). The level of human LRRK2 protein is about 2 fold higher than the endogenous mouse LRRK2.
Up to 1.5 months post-injection: Contradictory results are reported, from no cell loss observed in the nigra to around 20% TH and VMAT positive cell loss. When present a significant degeneration of the SN can be seen as early as 10 days after injections. A decrease in TH density can be seen in the striatum after 21 days.
10 days post-injection: Hyper-phosphorylation of tau and increase in ubiquitin levels can be seen in the striatum. Tau hyper-phosphorylation disappears after 21 days.
Up to 1.5 months post-injection: No alpha-synuclein inclusions are observed, however, ubiquitin positive inclusions are present in the striatum.
3 weeks – 1.5 months post-injection: No significant impairment in the cylinder test.
Response to dopaminergic treatment
Non-applicable in the absence of motor impairment.
10 days post-injection: Inflammation is present at the injection sites (increase of microglia in the striatum) but is similar to the reaction observed in animals injected with control vectors (GFP or wild type LRRK2).
1.5 months post-injection: Normalization of the glial response (astrocytes appear normal and microglial response decreases).