title: Schwann Cell and Axon: An Interlaced Unit-From Action Potential to Phenotype Expression.
abstract: Here we propose a model of a peripheral axon with a great deal of autonomy from its cell body-the autonomous axon-but with a substantial dependence on its ensheathing Schwann cell (SC), the axon-SC unit. We review evidence in several fields and show that (i) axons can extend sprouts and grow without the concurrence of the cell body, but regulated by SCs; (ii) axons synthesize their proteins assisted by SCs that supply them with ribosomes and, probably, with mRNAs by way of exosomes; (iii) the molecular organization of the axoplasm, i.e., its phenotype, is regulated by the SC, as illustrated by the axonal microtubular content, which is down-regulated by the SC; and (iv) the axon has a program for self-destruction that is boosted by the SC. The main novelty of this model axon-SC unit is that it breaks with the notion that all proteins of the nerve cell are specified by its own nucleus. The notion of a collaborative specification of the axoplasm by more than one nucleus, which we present here, opens a new dimension in the understanding of the nervous system in health and disease and is also a frame of reference to understand other tissues or cell associations.
authors.affiliation: Center for Integrative Biology, Universidad Mayor, Santiago, Chile. fcourt@bio.puc.cl.|FONDAP Center for Geroscience, Brain Health and Metabolism, Santiago, Chile. fcourt@bio.puc.cl.|Millenium Nucleus for Regenerative Biology, Pontificia Universidad Católica de Chile, Santiago, 8331150, Chile. fcourt@bio.puc.cl.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Court
authors.affiliation: Millenium Nucleus for Regenerative Biology, Pontificia Universidad Católica de Chile, Santiago, 8331150, Chile.
authors.forename: Jaime
authors.initials: J
authors.lastname: Alvarez
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D001692:Biological Transport; D002450:Cell Communication; D055354:Exosomes / Q000378:metabolism; D006801:Humans; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009416:Nerve Regeneration / Q000502:physiology*; D016571:Neural Networks, Computer; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012270:Ribosomes / Q000378:metabolism*; D012583:Schwann Cells / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction; D013497:Sural Nerve / Q000293:injuries / Q000378:metabolism
chemical_list: D012333:RNA, Messenger
keywords: Axoplasm; Exosomes; Microtubular density; Wallerian degeneration; mRNA