Mammalian UPF3A and UPF3B can activate nonsense‐mediated mRNA decay independently of their exon junction complex binding |
| |
| Authors: | Zhongxia Yi Ren M Arvola Sean Myers Corinne N Dilsavor Rabab Abu Alhasan Bayley N Carter Robert D Patton Ralf Bundschuh Guramrit Singh |
| |
| Institution: | 1. Center for RNA Biology, The Ohio State University, Columbus OH, USA ; 2. Department of Molecular Genetics, The Ohio State University, Columbus OH, USA ; 3. Department of Physics, The Ohio State University, Columbus OH, USA ; 4. Department of Chemistry and Biochemistry, The Ohio State University, Columbus OH, USA ; 5. Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus OH, USA |
| |
| Abstract: | Nonsense‐mediated mRNA decay (NMD) is governed by the three conserved factors—UPF1, UPF2, and UPF3. While all three are required for NMD in yeast, UPF3B is dispensable for NMD in mammals, and its paralog UPF3A is suggested to only weakly activate or even repress NMD due to its weaker binding to the exon junction complex (EJC). Here, we characterize the UPF3A/B‐dependence of NMD in human cell lines deleted of one or both UPF3 paralogs. We show that in human colorectal cancer HCT116 cells, NMD can operate in a UPF3B‐dependent and ‐independent manner. While UPF3A is almost dispensable for NMD in wild‐type cells, it strongly activates NMD in cells lacking UPF3B. Notably, NMD remains partially active in cells lacking both UPF3 paralogs. Complementation studies in these cells show that EJC‐binding domain of UPF3 paralogs is dispensable for NMD. Instead, the conserved “mid” domain of UPF3 paralogs is consequential for their NMD activity. Altogether, our results demonstrate that the mammalian UPF3 proteins play a more active role in NMD than simply bridging the EJC and the UPF complex. |
| |
| Keywords: | exon junction complex mRNA degradation nonsense mutations nonsense‐ mediated mRNA decay translation termination |
|
|
