Oligodendrocyte myelin glycoprotein (OMgp) is expressed by both neurons and oligodendrocytes
May 23, 2017
Oligodendrocyte myelin glycoprotein (OMgp) is expressed by both neurons and oligodendrocytes in the central anxious system (CNS). and paranodal architecture. However we show here that the anti-OMgp antiserum used in previous studies to define the functions of OMgp at nodes is not specific. Among all reported nodal ECM components the antiserum exhibited strong cross-reactivity against versican V2 LRP2 isoform a chondroitin sulfate proteoglycan. Furthermore the OMgp antiserum labeled OMgp-null nodes but not nodes from versican V2-deficient mice and pre-adsorption of the OMgp antiserum with recombinant versican GDC-0349 V2 blocked nodal labeling. Analysis of CNS nodes in OMgp-null mice failed to reveal any nodal or paranodal defects or increased nodal collateral sprouting indicating that OMgp does not participate in CNS node of Ranvier assembly or maintenance. We successfully identified a highly specific anti-OMgp antibody and observed OMgp staining in white matter only after initiation of myelination. OMgp immunoreactivity decorated the surface of mature myelinated axons but was excluded from compact myelin and nodes. Together our results strongly argue against the nodal localization of OMgp and its proposed functions at nodes and reveal OMgp’s authentic localization relative to nodes and myelin. test and errors indicated are ± SEM. Dot blotting and Western blotting Brain membrane homogenates were prepared as described previously (Schafer et al. 2004 The brain cytosolic fractions were the supernatants collected after the second centrifugation step. Nerve extracts were prepared by collecting supernatants from nerves sonicated in homogenizing buffer on ice and centrifued at 600× g for 10 min. Immunoblotting was performed as described previously (Schafer et al. 2004 Before electrophoresis chondroitin sulfate digestion of versican V2-Fc brain membrane homogenates and cytosolic fractions were carried out by incubating samples in 50 mM Tris-HCl pH 8.3 60 mM sodium acetate pH 8 10 mM EDTA 0.02% BSA (w/v) and 0.4-0.67 unit/ml chondroitinase ABC (Sigma) at 37°C for 1 hr (versican V2-Fc) or 16 hr (membrane homogenates and cytosolic fractions). Immunoadsorption Fc fusion proteins GDC-0349 in the collected media were applied to nitrocellulose membranes by dot blot. The regions of the membrane with Fc fusion proteins were cut put in 1.5-ml microcentrifuge tubes and washed with PBTGS. The primary antibodies diluted in PBTGS were incubated with the membrane in the tubes at 4°C overnight and then applied to tissue sections for immunostaining. GDC-0349 Rotarod Mice were conditioned on the rotating rod (Ugo Basile) at 4 revolutions per minute GDC-0349 (RPM) for 5 minutes. Mice then received a 1 hour break. Mice were then tested for latency to fall in 3 trials by placing them on the rotating rod which accelerated from 4 to 40 RPM in 5 minutes. Each trial was separated by a 30 minute break and latencies to fall were averaged across all trials. Electron microscopy 100 old WT (n=3) and OMgp KO (n=3) mice were anesthetized with Ketamine (80 mg/kg) and Xylazine (16 mg/kg) by intraperitoneal injection. The animals were perfused with 2 Then.5% glutaraldehyde and 2.0% paraformaldehyde in 0.1 M cacodylate buffer (pH 7.4). Optic nerves had been dissected out and postfixed in the same fixative for yet another 3 hours. Then your nerves had been postfixed in 1% osmium tetroxide option in 0.1M cacodylate buffer (pH 7.4) for 2 hours. After cleaning nerves had been dehydrated through a graded ethanol series and inlayed GDC-0349 in Low viscosity resin (Electron Microscopy Sciences Hatfield PA). Cells had been stained for one hour in saturated uranyl acetate plus 50% ethanol during dehydration. The sectioning and electron microscopy was performed in the Baylor University of Medication Integrated Microscopy Primary (Movie director: Dr. Michael A. Mancini). Longitudinal and transverse slim sections of around 70nm had been acquired using an RMC MT6000-XL ultramicrotome and a Diatome Ultra45 diamond knife and collected on 150 hex-mesh copper grids. The dried sections were counter-stained with Reynold’s lead citrate for 4 minutes after microtomy. Sections were observed using a transmission electron microscope (H7500 Hitachi Tokyo Japan). Pictures had been attained and measurements had been performed.