title: Paraquat modulates alternative pre-mRNA splicing by modifying the intracellular distribution of SRPK2.
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.
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano - Bicocca, Milano, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Vivarelli
authors.forename: Silvia C
authors.initials: SC
authors.lastname: Lenzken
authors.forename: Marc-David
authors.initials: MD
authors.lastname: Ruepp
authors.forename: Francesco
authors.initials: F
authors.lastname: Ranzini
authors.forename: Andrea
authors.initials: A
authors.lastname: Maffioletti
authors.forename: Reinaldo
authors.initials: R
authors.lastname: Alvarez
authors.forename: Oliver
authors.initials: O
authors.lastname: Mühlemann
authors.forename: Silvia M L
authors.initials: SM
authors.lastname: Barabino
mesh_terms: D006801:Humans; D016297:Mutagenesis, Site-Directed; D010269:Paraquat / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing / Q000187:drug effects / Q000235:genetics
chemical_list: D012322:RNA Precursors; D017346:Protein Serine-Threonine Kinases; C110522:SRPK2 protein, human; D010269:Paraquat