LRRK2 and Parkinson disease: In animal PD models, let-7f was observed to be upregulated in the striatal tissues of LRRK2-KO mice as compared to control mice [28] while let-7 was reported to be downregulated in an A53T α-synuclein-overexpressed model of Caenorhabditis elegans (C. elegans) [40].