title: Axons provide the secretory machinery for trafficking of voltage-gated sodium channels in peripheral nerve.
abstract: The regulation of the axonal proteome is key to generate and maintain neural function. Fast and slow axoplasmic waves have been known for decades, but alternative mechanisms to control the abundance of axonal proteins based on local synthesis have also been identified. The presence of the endoplasmic reticulum has been documented in peripheral axons, but it is still unknown whether this localized organelle participates in the delivery of axonal membrane proteins. Voltage-gated sodium channels are responsible for action potentials and are mostly concentrated in the axon initial segment and nodes of Ranvier. Despite their fundamental role, little is known about the intracellular trafficking mechanisms that govern their availability in mature axons. Here we describe the secretory machinery in axons and its contribution to plasma membrane delivery of sodium channels. The distribution of axonal secretory components was evaluated in axons of the sciatic nerve and in spinal nerve axons after in vivo electroporation. Intracellular protein trafficking was pharmacologically blocked in vivo and in vitro. Axonal voltage-gated sodium channel mRNA and local trafficking were examined by RT-PCR and a retention-release methodology. We demonstrate that mature axons contain components of the endoplasmic reticulum and other biosynthetic organelles. Axonal organelles and sodium channel localization are sensitive to local blockade of the endoplasmic reticulum to Golgi transport. More importantly, secretory organelles are capable of delivering sodium channels to the plasma membrane in isolated axons, demonstrating an intrinsic capacity of the axonal biosynthetic route in regulating the axonal proteome in mammalian axons.
authors.affiliation: Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile;
authors.forename: Carolina
authors.initials: C
authors.lastname: González
authors.affiliation: Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile;
authors.forename: José
authors.initials: J
authors.lastname: Cánovas
authors.affiliation: Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile;
authors.forename: Javiera
authors.initials: J
authors.lastname: Fresno
authors.affiliation: Instituto de Biología, Laboratorio de Microscopía Electrónica, Facultad de Ciencias, Universidad de Valparaíso, 2360102 Valparaíso, Chile;
authors.forename: Eduardo
authors.initials: E
authors.lastname: Couve
authors.affiliation: Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Court
authors.affiliation: Program of Physiology and Biophysics, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, 8380453 Santiago, Chile; andres@neuro.med.uchile.cl.
authors.forename: Andrés
authors.initials: A
authors.lastname: Couve
mesh_terms: D000818:Animals; D001369:Axons; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D015640:Ion Channel Gating; D008297:Male; D010525:Peripheral Nerves / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000378:metabolism*
chemical_list: D015222:Sodium Channels
keywords: axon; endoplasmic reticulum; trafficking
references.citation: Dev Biol. 2001 Aug 1;236(1):5-16
references.pmid: 11456440
references.citation: Traffic. 2011 Jan;12(1):28-41
references.pmid: 20955502
references.citation: Neuron. 2001 Dec 20;32(6):1013-26
references.pmid: 11754834
references.citation: Mol Cell Neurosci. 2001 Nov;18(5):570-80
references.pmid: 11922146
references.citation: Cell. 2002 Jul 26;110(2):223-35
references.pmid: 12150930
references.citation: Nature. 2002 Sep 19;419(6904):271-7
references.pmid: 12239560
references.citation: J Neurosci. 2003 Aug 6;23(18):7001-11
references.pmid: 12904461
references.citation: Nat Neurosci. 2006 Oct;9(10):1247-56
references.pmid: 16980963
references.citation: Neuron. 2005 Dec 8;48(5):737-42
references.pmid: 16337912
references.citation: RNA. 2011 Jan;17(1):85-98
references.pmid: 21098654
references.citation: Nat Commun. 2011;2:543
references.pmid: 22109517
references.citation: Neuron. 2012 Jan 12;73(1):92-107
references.pmid: 22243749
references.citation: Biol Res. 2011;44(4):311-21
references.pmid: 22446593
references.citation: J Neurosci. 2012 May 23;32(21):7232-43
references.pmid: 22623668
references.citation: Cell Rep. 2012 Jul 26;2(1):89-100
references.pmid: 22840400
references.citation: Neurosci Bull. 2013 Aug;29(4):493-500
references.pmid: 23839054
references.citation: Z Zellforsch Mikrosk Anat. 1972;124(2):217-29
references.pmid: 5012671
references.citation: J Electron Microsc (Tokyo). 1976;25(3):141-9
references.pmid: 1025229
references.citation: J Neurochem. 1982 Aug;39(2):386-400
references.pmid: 7086424
references.citation: J Comp Neurol. 1984 Dec 1;230(2):231-48
references.pmid: 6210310
references.citation: Cell. 1986 Aug 1;46(3):437-44
references.pmid: 2425982
references.citation: J Biol Chem. 1988 Dec 5;263(34):18545-52
references.pmid: 3192548
references.citation: J Submicrosc Cytol Pathol. 1991 Jan;23(1):33-8
references.pmid: 2036627
references.citation: J Neurosci. 1995 Jan;15(1 Pt 2):492-503
references.pmid: 7823157
references.citation: Neuroscience. 1997 Sep;80(1):1-7
references.pmid: 9252215
references.citation: J Neurosci. 2005 Jan 26;25(4):778-91
references.pmid: 15673657
references.citation: Nat Rev Neurosci. 2005 Mar;6(3):201-14
references.pmid: 15711600
references.citation: J Neurosci. 2013 Nov 6;33(45):17884-96
references.pmid: 24198377
references.citation: Semin Cell Dev Biol. 2014 Mar;27:23-31
references.pmid: 24361785
references.citation: J Comp Neurol. 2014 Dec 15;522(18):4057-73
references.pmid: 25048219
references.citation: J Neurobiol. 2000 Jul;44(1):72-81
references.pmid: 10880133
references.citation: Neurobiol Dis. 2000 Aug;7(4):416-28
references.pmid: 10964612
references.citation: Neuron. 2001 Apr;30(1):91-104
references.pmid: 11343647
references.citation: Neuron. 2001 May;30(2):335-44
references.pmid: 11394997
references.citation: Brain Res. 1970 Dec 1;24(2):359-63
references.pmid: 5490299
references.citation: Nat Neurosci. 2006 Oct;9(10):1265-73
references.pmid: 16980965
references.citation: J Cell Biol. 2007 Sep 10;178(6):965-80
references.pmid: 17785519
references.citation: J Neurosci. 2008 Oct 22;28(43):11024-9
references.pmid: 18945910
references.citation: Int J Dev Biol. 2009;53(1):19-27
references.pmid: 19123123
references.citation: Mol Cell Neurosci. 2009 Feb;40(2):128-42
references.pmid: 19022387
references.citation: Nat Chem Biol. 2009 Mar;5(3):157-65
references.pmid: 19182783
references.citation: J Biol Chem. 2009 May 8;284(19):13077-85
references.pmid: 19276079
references.citation: Results Probl Cell Differ. 2009;48:269-88
references.pmid: 19343311
references.citation: Results Probl Cell Differ. 2009;48:193-224
references.pmid: 19582411
references.citation: Traffic. 2009 Nov;10(11):1669-84
references.pmid: 19761544
references.citation: Traffic. 2010 Dec;11(12):1498-505
references.pmid: 21040295
references.citation: J Neurosci. 2001 Dec 1;21(23):9291-303
references.pmid: 11717363