Genetic background influences LRRK2-mediated Rab phosphorylation in the rat brain

Pathogenic missense mutations in the leucine-rich repeat kinase 2 gene, encoding LRRK2, results in the upregulation of Rab10 and Rab12 phosphorylation in different cells and tissues. Here, we evaluate levels of the LRRK2 kinase substrates pT73-Rab10 and pS106-Rab12 proteins in rat brain tissues from different genetic backgrounds. Whereas lines of Sprague Dawley rats have equivalent levels of pT73-Rab10 and pS106-Rab12 similar to Lrrk2 knockout rats, Long-Evans rats have levels of pT73-Rab10 and pS106-Rab12 comparable to G2019S-LRRK2 BAC transgenic rats. Strong LRRK2 kinase inhibitors are ineffective at reducing pT73-Rab10 and pS106-Rab12 levels in the Sprague Dawley rats, but potently reduce pT73-Rab10 and pS106-Rab12 levels in Long-Evans rats. Oral administration of the PFE-360 LRRK2 kinase inhibitor fails to provide neuroprotection from dopaminergic neurodegeneration caused by rAAV2/1-mediated overexpression of A53T-αsynuclein in Sprague Dawley rats. These results highlight substantial differences in LRRK2-mediated Rab10 and Rab12 phosphorylation in commonly utilized rat genetic backgrounds and suggest LRRK2 may not play a central role in Rab phosphorylation or mutant αsynuclein toxicity in Sprague Dawley rats.