Abstract
Paraquat (PQ) is a neurotoxic herbicide that induces superoxide formation. Although it is known that its toxic properties are linked to ROS production, the cellular response to PQ is still poorly understood. We reported previously that treatment with PQ induced genome-wide changes in pre-mRNA splicing. Here, we investigated the molecular mechanism underlying PQ-induced pre-mRNA splicing alterations. We show that PQ treatment leads to the phosphorylation and nuclear accumulation of SRPK2, a member of the family of serine/arginine (SR) protein-specific kinases. Concomitantly, we observed increased phosphorylation of SR proteins. Site-specific mutagenesis identified a single serine residue that is necessary and sufficient for nuclear localization of SRPK2. Transfection of a phosphomimetic mutant modified splice site selection of the E1A minigene splicing reporter similar to PQ-treatment. Finally, we found that PQ induces DNA damage and vice versa that genotoxic treatments are also able to promote SRPK2 phosphorylation and nuclear localization. Consistent with these observations, treatment with PQ, cisplatin or γ-radiation promote changes in the splicing pattern of genes involved in DNA repair, cell cycle control, and apoptosis. Altogether, our findings reveal a novel regulatory mechanism that connects PQ to the DNA damage response and to the modulation of alternative splicing via SRPK2 phosphorylation.
Highlights
Parkinson’s Disease (PD) is the second most common progressive neurodegenerative disorder of the central nervous system
We examined by immunofluorescence microscopy the intracellular distribution of several splicing regulatory proteins in cells incubated with 0.75 mM PQ for 18 hours
In this report we investigated the molecular mechanism underlying the changes in alternative splicing that are induced by PQ treatment of SH-SY5Y neuroblastoma cells
Summary
Parkinson’s Disease (PD) is the second most common progressive neurodegenerative disorder of the central nervous system. Epidemiological studies suggest that PD is a multifactorial disorder probably arising from polygenic inheritance and gene–environmental interactions. Exposure to pesticides and to the herbicide paraquat (PQ, 1,19-dimethyl-4,49-bipyridinium) is known to increase the risk of developing PD. PQ uncouples the mitochondrial electron transport chain, which induces superoxide formation [1]. Its toxic properties support the hypothesis that neuronal damage in PD may arise from a mechanism of oxidative stress. Since in recent years PQ has become an increasingly popular model for studying the etiology of PD (15, 16), it is important to understand the molecular mechanism underlying PQ-induced toxicity to neural cells
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