title: Tricellulin is expressed in autotypic tight junctions of peripheral myelinating Schwann cells.
abstract: Autotypic tight junctions are formed by tight junction-like structures in three regions of myelinating Schwann cells, the paranodal loops, Schmidt-Lanterman incisures, and outer/inner mesaxons, and various tight junction molecules, including claudin-19 and junctional adhesion molecule (JAM)-C. Our findings demonstrate the identification and subcellular distribution of a novel tricellular tight junction protein, tricellulin (TRIC), in the autotypic tight junctions of mouse myelinating Schwann cells, compared with the autotypic adherens junction protein E-cadherin and the autotypic tight junction protein JAM-C, which are expressed in the paranodal loops, Schmidt-Lanterman incisures, and mesaxons. In real-time RT-PCR, the expression level of TRIC mRNA was about 10-fold higher in the sciatic nerve than in the spinal cord or cerebrum. In immunostaining, TRIC signals were completely restricted to the peripheral nervous system (PNS) and strongly concentrated at the paranodal loops, Schmidt-Lanterman incisures, and mesaxons of myelinating Schwann cells. In addition, TRIC was expressed in the thin region of the paranode and there was a gap between TRIC and the Na+ channel. Furthermore, TRIC was more distally located from the node than E-cadherin and was colocalized with JAM-C. It is possible that TRIC may be a component to maintain the integrity for PNS myelin function and morphology. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
authors.affiliation: Department of Anatomy, Sapporo Medical University School of Medicine, West 17, South 1, Chuo-ku, Sapporo 060-8556, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ninomiya
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Tatsumi
authors.forename: Norimasa
authors.initials: N
authors.lastname: Sawada
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
mesh_terms: D000818:Animals; D062794:MARVEL Domain Containing 2 Protein; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009413:Nerve Fibers, Myelinated / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012583:Schwann Cells / Q000166:cytology* / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism*
chemical_list: D062794:MARVEL Domain Containing 2 Protein; C508309:Marveld2 protein, mouse; D008565:Membrane Proteins; D012333:RNA, Messenger