Combinatorial control of signal-induced exon repression by hnRNP L and PSF.
Cells can regulate their protein repertoire in response to extracellular stimuli via alternative splicing; however, the mechanisms controlling this process are poorly understood. The CD45 gene undergoes alternative splicing in response to T-cell activation to regulate T-cell function. The ESS1 splicing silencer in CD45 exon 4 confers basal exon skipping in resting T cells through the activity of hnRNP L and confers activation-induced exon skipping in T cells via previously unknown mechanisms. Here we have developed an in vitro splicing assay that recapitulates the signal-induced alternative splicing of CD45 and demonstrate that cellular stimulation leads to two changes to the ESS1-bound splicing regulatory complex. Activation-induced posttranslational modification of hnRNP L correlates with a modest increase in the protein's repressive activity. More importantly, the splicing factor PSF is recruited to the ESS1 complex in an activation-dependent manner and accounts for the majority of the signal-regulated ESS1 activity. The associations of hnRNP L and PSF with the ESS1 complex are largely independent of each other, but together these proteins account for the total signal-regulated change in CD45 splicing observed in vitro and in vivo. Such a combinatorial effect on splicing allows for precise regulation of signal-induced alternative splicing.
Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390-9038, USA.
Alexis A
AA
Melton
Jason
J
Jackson
Jiarong
J
Wang
Kristen W
KW
Lynch
D017398:Alternative Splicing; D000818:Animals; D002460:Cell Line; D005091:Exons; D005786:Gene Expression Regulation; D034664:Heterogeneous-Nuclear Ribonucleoprotein L / Q000235:genetics / Q000378:metabolism*; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000378:metabolism; D000072670:PTB-Associated Splicing Factor; D011499:Protein Processing, Post-Translational; D012322:RNA Precursors / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D034664:Heterogeneous-Nuclear Ribonucleoprotein L; D000072670:PTB-Associated Splicing Factor; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D017493:Leukocyte Common Antigens