"Upstream ORF affects MYCN translation depending on exon 1b alternative splicing".
Roger Besançon 1, 2, @, Sandrine Valsesia-Wittmann 3 , Clara Locher 1, Céline Delloye-Bourgeois 1, Lydie Furhman 1, Giovani Tutrone 1, Christophe Bertrand 1, Anne-Catherine Jallas 3, Elisabeth Garin 3, and Alain Puisieux 1, 2, 3.
1 INSERM UMR590, 28 rue Laënnec, Lyon, France
2 Université de Lyon, université Lyon 1,
Institut des Sciences Pharmaceutiques et Biologiques, 8
avenue Rockefeller, Lyon, 69008, France
3 Centre Léon Bérard, Laboratoire de Recherche
Translationnelle, 28 rue Laënnec, Lyon, France
@ Corresponding author: ROGER.BESANCON@recherche.univ-lyon1.fr
The MYCN gene is transcribed into two major mRNAs: one full-length (MYCN) and one exon 1b-spliced (MYCNdelta1b) mRNA. But nothing is known about their respective ability to translate the MYCN protein.
Methods
Plasmids were prepared to enable translation from the upstream (uORF) and major ORF of the two MYCN transcripts. Translation was studied after transfection in neuroblastoma SH-EP cell line. Impact of the upstream AUG on translation was evaluated after directed mutagenesis. Functional study with the two MYCN mRNAs was conducted by a cell viability assay. Existence of a new protein encoded by the MYCNdelta1b uORF was explored by designing a rabbit polyclonal antibody against a specific epitope of this protein.
Results
Both are translated, but higher levels of protein were seen with MYCNdelta1b mRNA. An upstream ORF was shown to have positive cis-regulatory activity on translation from MYCN but not from MYCNdelta1b mRNA. In transfected SH-EP neuroblastoma cells, high MYCN dosage obtained with MYCNdelta1b mRNA translation induces an antiapoptotic effect after serum deprivation that was not observed with low MYCN expression obtained with MYCN mRNA. Here, we showed that MYCNOT: MYCN Overlap Transcript, a new protein of unknown function is translated from the upstream AUG of MYCNdelta1b mRNA.
Conclusions
Existence of upstream ORF in MYCN transcripts leads to a new level of MYCN regulation. The resulting MYCN dosage has a weak but significant anti-apoptotic activity after intrinsic apoptosis induction.
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1. Each cell retains all of its embryonic genes for a lifetime.
2. Controls for embryonic genes are often absent in adults.
3. Uncontrolled embryonic genes can replicate wildly.
4. Replicating genes participate in intra-cellular competition.
5. The basis for gene competition is selective transcription.
6. MicroRNAs can reprogram embryomic transcription.
7. Gene reprogramming can produce normal phenotypes.
8. Normal phenotypes can by-pass chromosomal lesions.
9. MicroRNA therapy may need to be permanent.
10. Transplantation of microRNAs could be preferred.
1. Pathways within cell genomes involve a flow of information.
2. Information can flow by direct contact or by third parties.
3. Direct contact within whole genomes is difficult to regulate.
4. DNA-DNA direct contects are influenced by agents.
5. Nuclear agents include hydrophilic ionic and hydrophobic conforming ligands.
6. Third parties within genomes involve RNAs and proteins.
7. RNAs and proteins are easy to regulate or reverse.
8. Information can be shared, lost, or transformed.
9. Local information can be permanently lost during system entropy.
10. System information can be hidden during isolation.
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