Phylogenetically Conserved Sequences Around Myelin P0 Stop Codon are Essential for Translational Readthrough to Produce
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ORIGINAL PAPER
Phylogenetically Conserved Sequences Around Myelin P0 Stop Codon are Essential for Translational Readthrough to Produce L-MPZ Yoshihide Yamaguchi1 · Hiroko Baba1
Received: 14 July 2017 / Revised: 14 September 2017 / Accepted: 19 October 2017 © Springer Science+Business Media, LLC 2017
Abstract Myelin protein zero (P0, MPZ) is the main cell adhesion molecule in peripheral myelin, the sequence of which is evolutionarily highly conserved. Large myelin protein zero (L-MPZ) is a novel translational readthrough molecule in mammals in a physiological status and is encoded by the P0 mRNA with an extra domain. The sequence similarities in the L-MPZ-specific region are found in humans and frogs but not in fish P0 cDNA. Actual synthesis of L-MPZ has been detected in rat and mouse sciatic nerve but not yet evaluated in frogs and humans. The production mechanism and physiological functions of L-MPZ remain unknown. Additionally, the sequence context around the canonical stop codon is significant for readthrough in viruses and yeast, but the correlation between the sequence around P0 stop codon and L-MPZ synthesis is unclear. Here, we focused on the phylogenetic pathways in L-MPZ synthesis. We have shown that L-MPZ is widely produced from frogs to humans using western blotting against L-MPZ. Mutation analysis of the sequence around the stop codon for L-MPZ synthesis using a mammalian in vitro transcription/translation system revealed that the evolutionarily conserved sequence around P0 stop codon is susceptible to readthrough and is similar to the consensus motif in viruses and yeast UAG stop codon type molecules. Our results demonstrate that the phylogenetically conserved sequence around the canonical P0 stop codon is essential for L-MPZ synthesis, suggesting that phylogenetic emergence of L-MPZ in amphibians may be related to particular distribution and/or function in the PNS myelin. * Yoshihide Yamaguchi [email protected] 1
Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, 1432‑1 Horinouchi, Hachioji, Tokyo 192‑0392, Japan
Keywords Translational readthrough · Myelin · Myelin protein zero (P0, MPZ) · Large myelin protein zero (L-MPZ) Abbreviations Aa Amino acid AQP4 Aquaporin-4 CBB Coomassie brilliant blue CNS Central nervous system Ig Immunoglobulin L-MPZ Large myelin protein MPZ, P0 Myelin protein zero PKC Protein kinase C PNS Peripheral nervous system PTC Premature termination codon SC Spinal cord ScN Sciatic nerve SDS-PAGE Sodium dodecyl sulfate polyacrylamide gel electrophoresis VEGF-A Vascular endothelial growth factor A
Introduction Peripheral myelin protein zero (P0 or MPZ) is a type I transmembrane adhesion molecule with an extracellular immunoglobulin (Ig) domain and a major peripheral myelin protein in a tetrapod [1]. N-glycosylated mature P0 protein [219 amino acids (aa)] has an molecular weight of approximately 30 kDa. Homophilic interactions between Ig domains lead to tight adhesion of the peripheral nervous system (PNS) myelin membra
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