We report a role for the 3'-untranslated region in control of mRNA splicing and show that human TNF-α 3' UTR harbors a cis- acting element that renders splicing of precursor transcripts dependent on activation of PKR, the RNA-activated protein kinase that phosphorylates eukaryotic initiation factor 2 (eIF2). When this element, designated 2-APRE, is present, splicing becomes sensitive to inhibition by the PKR inhibitor, 2-aminopurine, or by coexpression of transdominant-negative mutant PKR. Our results reveal that activation of PKR is required for splicing of mRNA when precursor transcripts contain the 2-APRE and that increased expression of wild-type PKR enhances their splicing efficiency. Thus, PKR responds as trans-acting factor to the 2-APRE. 2-APRE RNA forms a stable, 17-bp stem-loop structure and strongly activates PKR in vitro, inducing eIF2α phosphorylation. Despite its ability to activate PKR during splicing, the 2-APRE within the 3' UTR does not affect translation efficiency of the resulting TNF-α mRNA in transfected cells. PKR and the 3' UTR thus interact during mRNA splicing to confer a novel type of regulation on expression of the TNF-α gene.
Bibliographical noteFunding Information:
We would like to thank Craig Foltz for establishing the connection among us. A. G. M. would like to thank E. Dwek for useful discussions. J. A. M. is supported by a postdoctoral fellowship from Ministerio de Educación y Cultura, Spain. We also thank the anonymous referee for correcting an error in the first version of our manuscript.
- 3'- untranslated region
- Cis-acting RNA element
- Protein kinase PKR
- Tumor necrosis factor