title: Combined inhibition of PI3K and activation of MAPK p38 signaling pathways trigger erythroid alternative splicing switch of 4.1R pre-mRNA in DMSO-induced erythroleukemia cells.
abstract: There is increasing evidence showing that many extracellular cues modulate pre-mRNA alternative splicing, through different signaling pathways. We here show that 4.1R exon 16 splicing is altered in response to specific signals. The switch from erythroblastic isoform lacking exon 16 to mature erythrocytic isoform containing this exon is tightly regulated during late erythroid differentiation, and blocage of this splicing switch in erythroleukemia cells is seen as a consequence of the deregulation of important regulatory pathways. We support that combined inhibition of PI3K and activation of p38 signaling pathways impinge on erythroid 4.1R pre-mRNA alternative splicing switch, and on cell differentiation as witnessed by hemoglobin production. By contrast, MEK/ERK signaling appeared not to affect neither cell hemoglobin production nor erythroid 4.1R pre-mRNA splicing. We also found that the signal-induced alternative splicing is not typically distinctive of EPO-non-responsive cells, but operates in EPO-responsive cells as well. Pre-mRNA splicing is a major regulatory mechanism at the crossroad between transcription and translation. We here provide evidence that inhibition of PI3K activates the splicing switch in a promoter-dependent manner, whereas p38 activation induces this event in a promoter-independent fashion. Our data further support that constitutive activation of EPO-R by the viral protein gp55 and the short form of the tyrosine kinase receptor Stk, transduces PI3K proliferation signal, but not MAPK p38 differentiation signal. Concurrently, this work lend credence to the concept that DMSO triggers transient activation of p38 signaling and irreversible inhibition of PI3K/AKT signaling pathway, hence uncovering an old conundrum regarding the mechanism by which DMSO induces erythroleukemia cell differentiation.
authors.affiliation: mRNA Metabolism in Normal and Pathological Cells, CNRS UMR 5534, Université Lyon 1, 69622 Villeurbanne Cedex, France.
authors.forename: Osman
authors.initials: O
authors.lastname: Breig
authors.forename: Orianne
authors.initials: O
authors.lastname: Théoleyre-Schaal
authors.forename: Faouzi
authors.initials: F
authors.lastname: Baklouti
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D045744:Cell Line, Tumor; D004121:Dimethyl Sulfoxide; D041905:Erythroid Cells / Q000378:metabolism / Q000473:pathology; D004920:Erythropoiesis; D005091:Exons; D004915:Leukemia, Erythroblastic, Acute / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012322:RNA Precursors / Q000235:genetics*; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004121:Dimethyl Sulfoxide; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012322:RNA Precursors; D048051:p38 Mitogen-Activated Protein Kinases
keywords: BFU-E; DMSO; EPO; EPO-R; ERK; Erythroid differentiation; Erythroleukemia; JAK2; Janus kinase-2; MAPK; MAPK p38; MEK; MEL; MTT; PI3K; SFFV; SR protein; STAT5; Signaling; burst forming unit-erythroid; dimethylsulfoxide; erythropoietin; erythropoietin receptor; extracellular signal-regulated kinase; mRNA splicing; methotrexate; mitogen-activated protein kinase; mitogen-activated protein kinase/extracellular signal-regulated kinase kinase; mouse erythroleukemia; phosphatidylinositol 3-kinase; serine-arginine-rich protein; signal transducers and activators of transcription factor-5; spleen focus forming virus