title: Multiple mechanisms repress N-Bak mRNA translation in the healthy and apoptotic neurons.
abstract: N-Bak is a neuron-specific BH3-only splice variant of pro-apoptotic Bcl-2 family member Bak. We have shown that its mRNA is stable in the neurons, whereas the protein cannot be detected by antibodies, suggesting a strong translational arrest of the mRNA. Here we identify two regulatory elements in the N-Bak mRNA that significantly repress translation in the luciferase reporter assay: an upstream open reading frame in the 5'-untranslated region (UTR) and naturally spliced exon-exon junction downstream of the premature translation termination codon in the 3'UTR. We also show that N-Bak mRNA is stored in granular structures in the sympathetic neurons and stays in these granules during intrinsic apoptosis. Finally, we confirm the absence of N-Bak protein by quantitative mass spectrometry analysis in the healthy, apoptotic or stressed sympathetic and cortical neurons. We conclude that N-Bak mRNA is translationally repressed by multiple mechanisms, and the protein does not participate in the classical apoptosis or cellular stress response.
authors: Institute of Biotechnology, University of Helsinki, FIN-00014, Helsinki, Finland.
authors: M
authors: M
authors: Jakobson
authors: M
authors: M
authors: Jakobson
authors: O
authors: O
authors: Llano
authors: J
authors: J
authors: Palgi
authors: U
authors: U
authors: Arumäe
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D045744:Cell Line, Tumor; D003594:Cytoplasmic Granules / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D049409:Luciferases, Firefly / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D014176:Protein Biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D013312:Stress, Physiological; D017783:Superior Cervical Ganglion / Q000166:cytology; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D012333:RNA, Messenger; D050998:bcl-2 Homologous Antagonist-Killer Protein; D049409:Luciferases, Firefly
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