title: Ankyrin-B structurally defines terminal microdomains of peripheral somatosensory axons.
abstract: Axons are subdivided into functionally organized microdomains, which are required for generation and propagation of action potentials (APs). In the central nervous system (CNS), APs are generated near the soma in the axon initial segment (AIS) and propagated by nodes of Ranvier (noR). The crucial role of the membrane adapter proteins ankyrin-B and ankyrin-G as organizers of AIS and noR is now well established. By comparison, little is known on the localization and function of these proteins in sensory axon terminals of the peripheral nervous systems (PNS). Here, we tested the hypothesis that somatosensory PNS terminals are organized by distinct members of the ankyrin protein family. We discovered a specific distribution of ankyrin-B in somatosensory axon terminals of skin and muscle. Specifically, ankyrin-B was localized along the membrane of axons innervating Meissner corpuscles, Pacinian corpuscles and hair follicle receptors. Likewise, proprioceptive terminals of muscle spindles exhibited prominent ankyrin-B expression. Furthermore, ankyrin-B expression extended into nociceptive and thermoceptive intraepidermal nerve fibers. Interestingly, all studied somatosensory terminals were largely devoid of ankyrin-G, indicating that this scaffolding protein does not contribute to organization of mechanoelectric transduction zones in peripheral somatosensory neurons. Instead, we propose that ankyrin-B serves as a major membrane organizer in mechanoreceptive and nociceptive terminals of the PNS.
authors.affiliation: Center for Biomedicine and Medical Technology Mannheim, Research Division Neuroanatomy, Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str 13-17, 68167 Mannheim, Germany. maren.engelhardt@medma.uni-heidelberg.de
authors.forename: Maren
authors.initials: M
authors.lastname: Engelhardt
authors.forename: Silke
authors.initials: S
authors.lastname: Vorwald
authors.forename: Jürgen-Markus
authors.initials: JM
authors.lastname: Sobotzik
authors.forename: Vann
authors.initials: V
authors.lastname: Bennett
authors.forename: Christian
authors.initials: C
authors.lastname: Schultz
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D017487:Ankyrins / Q000378:metabolism*; D001369:Axons / Q000502:physiology*; D005260:Female; D005455:Fluorescent Antibody Technique; D008252:Macaca fascicularis; D008465:Mechanoreceptors / Q000378:metabolism; D018613:Microscopy, Confocal; D009132:Muscles / Q000294:innervation; D017933:Peripheral Nervous System / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000166:cytology*; D012867:Skin / Q000294:innervation; D034421:Sus scrofa
chemical_list: C432674:Ank2 protein, rat; D017487:Ankyrins