title: Heterophilic binding of L1 on unmyelinated sensory axons mediates Schwann cell adhesion and is required for axonal survival.
abstract: This study investigated the function of the adhesion molecule L1 in unmyelinated fibers of the peripheral nervous system (PNS) by analysis of L1- deficient mice. We demonstrate that L1 is present on axons and Schwann cells of sensory unmyelinated fibers, but only on Schwann cells of sympathetic unmyelinated fibers. In L1-deficient sensory nerves, Schwann cells formed but failed to retain normal axonal ensheathment. L1-deficient mice had reduced sensory function and loss of unmyelinated axons, while sympathetic unmyelinated axons appeared normal. In nerve transplant studies, loss of axonal-L1, but not Schwann cell-L1, reproduced the L1-deficient phenotype. These data establish that heterophilic axonal-L1 interactions mediate adhesion between unmyelinated sensory axons and Schwann cells, stabilize the polarization of Schwann cell surface membranes, and mediate a trophic effect that assures axonal survival.
authors.affiliation: Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Haney
authors.forename: Z
authors.initials: Z
authors.lastname: Sahenk
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: V P
authors.initials: VP
authors.lastname: Lemmon
authors.forename: J
authors.initials: J
authors.lastname: Roder
authors.forename: B D
authors.initials: BD
authors.lastname: Trapp
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002448:Cell Adhesion; D016764:Cell Polarity; D002470:Cell Survival; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D039841:Leukocyte L1 Antigen Complex; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009186:Myelin Sheath / Q000378:metabolism* / Q000648:ultrastructure; D018992:Myelin-Associated Glycoprotein / Q000235:genetics / Q000378:metabolism; D009410:Nerve Degeneration; D009412:Nerve Fibers / Q000378:metabolism / Q000648:ultrastructure; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D009475:Neurons, Afferent / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D017933:Peripheral Nervous System / Q000166:cytology; D011312:Pressure; D012583:Schwann Cells / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D012584:Sciatic Nerve / Q000637:transplantation / Q000648:ultrastructure
chemical_list: D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins; D018992:Myelin-Associated Glycoprotein; D019006:Neural Cell Adhesion Molecules