title: Signal- and development-dependent alternative splicing of LEF1 in T cells is controlled by CELF2.
abstract: The HMG-box transcription factor LEF1 controls many developmentally regulated genes, including genes that activate expression of the T-cell antigen receptor alpha chain (TCR-alpha) in developing thymocytes. At least two distinct isoforms of LEF1 are expressed, resulting from variable inclusion of LEF1 exon 6; however, the expression pattern of these isoforms and mechanism of splicing regulation have not been explored. Here we demonstrate that inclusion of LEF1 exon 6 is increased during thymic development and in response to signaling in a cultured T-cell line in a manner which temporally correlates with increased expression of TCR-alpha. We further find that inclusion of exon 6 is dependent on the signal-induced increase in expression and binding of the splicing factor CELF2 to two intronic sequences flanking the regulated exon. Importantly, loss of exon 6 inclusion, through knockdown of CELF2 or direct block of the exon 6 splice site, results in reduced expression of TCR-alpha mRNA. Together, these data establish the mechanistic basis of LEF1 splicing regulation and demonstrate that LEF1 alternative splicing is a contributing determinant in the optimal expression of the TCR-alpha chain.
authors: Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA.
authors: Michael J
authors: MJ
authors: Mallory
authors: Jason
authors: J
authors: Jackson
authors: Brittany
authors: B
authors: Weber
authors: Anthony
authors: A
authors: Chi
authors: Florian
authors: F
authors: Heyd
authors: Kristen W
authors: KW
authors: Lynch
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D000067878:CELF Proteins; D002460:Cell Line; D005091:Exons; D055785:Gene Knockdown Techniques; D006801:Humans; D008213:Lymphocyte Activation; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms; D016601:RNA-Binding Proteins / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013950:Thymus Gland / Q000196:embryology
chemical_list: D000067878:CELF Proteins; C117363:CELF2 protein, human; C497573:LEF1 protein, human; D051821:Lymphoid Enhancer-Binding Factor 1; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D013755:Tetradecanoylphorbol Acetate