title: How Schwann Cells Sort Axons: New Concepts.
abstract: Peripheral nerves contain large myelinated and small unmyelinated (Remak) fibers that perform different functions. The choice to myelinate or not is dictated to Schwann cells by the axon itself, based on the amount of neuregulin I-type III exposed on its membrane. Peripheral axons are more important in determining the final myelination fate than central axons, and the implications for this difference in Schwann cells and oligodendrocytes are discussed. Interestingly, this choice is reversible during pathology, accounting for the remarkable plasticity of Schwann cells, and contributing to the regenerative potential of the peripheral nervous system. Radial sorting is the process by which Schwann cells choose larger axons to myelinate during development. This crucial morphogenetic step is a prerequisite for myelination and for differentiation of Remak fibers, and is arrested in human diseases due to mutations in genes coding for extracellular matrix and linkage molecules. In this review we will summarize progresses made in the last years by a flurry of reverse genetic experiments in mice and fish. This work revealed novel molecules that control radial sorting, and contributed unexpected ideas to our understanding of the cellular and molecular mechanisms that control radial sorting of axons.
authors: Hunter James Kelly Research Institute, Departments of Biochemistry & Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA mlfeltri@buffalo.edu.
authors: M Laura
authors: ML
authors: Feltri
authors: Hunter James Kelly Research Institute, Departments of Biochemistry & Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
authors: Yannick
authors: Y
authors: Poitelon
authors: Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Stefano Carlo
authors: SC
authors: Previtali
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D002453:Cell Cycle; D002454:Cell Differentiation; D049109:Cell Proliferation; D006801:Humans; D051379:Mice; D009186:Myelin Sheath / Q000378:metabolism / Q000502:physiology*; D010525:Peripheral Nerves / Q000378:metabolism / Q000502:physiology; D017933:Peripheral Nervous System / Q000378:metabolism / Q000502:physiology*; D010523:Peripheral Nervous System Diseases / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D012583:Schwann Cells / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D012584:Sciatic Nerve / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure
keywords: Schwann cells; development; human peripheral neuropathies; myelin; peripheral nervous system