mRNA for N-Bak, a neuron-specific BH3-only splice isoform of Bak, escapes nonsense-mediated decay and is translationally repressed in the neurons
Open Access
- 2 February 2012
- journal article
- research article
- Published by Springer Science and Business Media LLC in Cell Death & Disease
- Vol. 3 (2), e269
- https://doi.org/10.1038/cddis.2012.4
Abstract
MRNA for neuronal Bak (N-Bak), a splice variant of pro-apoptotic Bcl-2 family member Bak is expressed in the neurons. Surprisingly the endogeneous N-Bak protein cannot be demonstrated in the neurons, although the antibodies recognize N-Bak protein from in vitro translation or transiently transfected cells. As N-Bak mRNA contains premature termination codon (PTC) at 89 nucleotides upstream from the last exon–exon junction, it could be degraded by nonsense-mediated decay (NMD) during the pioneer round of translation thus explaining the absence of the protein. We show here that the endogeneous neuronal N-Bak mRNA is not the NMD substrate, as it is not accumulating by cycloheximide treatment, it has a long lifetime, and even prevention of PTC by interfering with the alternative splicing did not lead to translation of the Bak mRNA. N-Bak protein is also not revealed by proteasome inhibitors. Our data suggest strong translational arrest of N-Bak mRNA in the neurons. We show that this arrest is partially mediated by 5′-untranslated region of Bak mRNA and it is not released during mitochondrial apoptosis.Keywords
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