Altered serine/arginine-rich protein phosphorylation and exonic enhancer-dependent splicing in Mammalian cells lacking topoisomerase I

Johann Soret , Mathieu Gabut , Cecile Dupon , Glenda Kohlhagen , James Stevenin (1, 1) , Yves Pommier , Jamal Tazi

1 IGBMC - Institut de Génétique et de Biologie Moléculaire et Cellulaire

DNA topoisomerase I (Topo I) specifically phosphorylates arginine-serine-rich (SR proteins) splicing factors and is potentially involved in pre-mRNA-splicing regulation. Using a Topo I-deficient murine B lymphoma-derived subclone (P388-45/C) selected for its resistance to high dosage of the antitumor drug camptothecin, we show that Topo I depletion results in the hypophosphorylation of SR proteins and impairs exonic splicing enhancer (ESE)-dependent but not constitutive splicing. The Affymetrix GeneChip system analysis revealed that several alternatively spliced genes, characterized by small exons and large introns, are down-regulated in Topo I-deficient cells. Given that ectopic expression of green fluorescent protein-Topo I fusion in Topo I-deficient cells restores both wild-type phosphorylation of SR proteins and ESE-dependent splicing, we conclude that Topo I-mediated phosphorylation plays a specific role in ESE-regulated splicing.

Domaines: Biochimie, Biologie Moléculaire

Johann Soret, Mathieu Gabut, Cecile Dupon, Glenda Kohlhagen, James Stevenin, et al.. Altered serine/arginine-rich protein phosphorylation and exonic enhancer-dependent splicing in Mammalian cells lacking topoisomerase I. Cancer Research, 2003, 63 (23), pp.8203-8211. ⟨hal-04143719⟩