Parkinson's disease-related gene variants influence pre-mRNA splicing processes

We have analyzed the impact of Parkinson's disease (PD)-related genetic variants on splicing using dedicated minigene assays. Out of 14 putative splicing variants in 5 genes (PINK1, [PTEN induced kinase 1]; LRPPRC, [leucine-rich pentatricopeptide repeat containing protein]; TFAM, [mitochondrial transcription factor A]; PARK2, [parkin RBR E3 ubiquitin protein ligase]; and HSPA9, [heat shock protein family A (Hsp70) member 9]), 4 LRPPRC variants, (IVS32-3C>T, IVS35+14C>T, IVS35+15C>T, and IVS9+30A>G) influenced, pre-messenger RNA splicing by modulating the inclusion of the respective exons. In addition, 1-Methyl-4-phenylpyridinium ion-induced splicing changes of endogenous LRPPRC messenger RNA, reproduced the effect of the LRPPRC IVS35+14C>T mutation. Using silencing and overexpression methods, we show that LRPPRC exon 33 splicing is negatively regulated by heterogeneous nuclear ribonucleoprotein A1 both in a minigene and endogenous context. Furthermore, exon 33 exclusion due to PD-associated mutation IVS32-3C>T or heterogeneous nuclear ribonucleoprotein A1 overexpression and exon 35 exclusion due to IVS35+14C>T can be rescued by co-expression of modified U1 small nuclear RNAs, providing a potentially useful therapeutic strategy. Our results indicate for the first time that LRPPRC intronic variants can affect normal splicing of this gene and may influence disease risk in PD and related disorders.