Tight junction proteins in human Schwann cell autotypic junctions.
Tight junctions (TJs) form physical barriers in various tissues and regulate paracellular transport of ions, water, and molecules. Myelinating Schwann cells form highly organized structures, including compact myelin, nodes of Ranvier, paranodal regions, Schmidt-Lanterman incisures, periaxonal cytoplasmic collars, and mesaxons. Autotypic TJs are formed in non-compacted myelin compartments between adjacent membrane lamellae of the same Schwann cell. Using indirect immunofluorescence and RT-PCR, we analyzed the expression of adherens junction (E-cadherin) and TJ [claudins, zonula occludens (ZO)-1, occludin] components in human peripheral nerve endoneurium, showing clear differences with published rodent profiles. Adult nerve paranodal regions contained E-cadherin, claudin-1, claudin-2, and ZO-1. Schmidt-Lanterman incisures contained E-cadherin, claudin-1, claudin-2, claudin-3, claudin-5, ZO-1, and occludin. Mesaxons contained E-cadherin, claudin-1, claudin-2, claudin-3, ZO-1, and occludin. None of the proteins studied were associated with nodal inter-Schwann cell junctions. Fetal nerve expression of claudin-1, claudin-3, ZO-1, and occludin was predominantly punctate, with a mesaxonal labeling pattern, but paranodal (ZO-1, claudin-3) and Schmidt-Lanterman incisure (claudins-1 and -3) expression profiles typical of compact myelin were visible by gestational week 37. The clear differences observed between human and published rodent nerve profiles emphasize the importance of human studies when translating the results of animal models to human diseases.
Alanne
Maria H
MH
Department of Anatomy, Institute of Biomedicine, University of Turku, Turku, Finland.
Pummi
Kati
K
Heape
Anthony M
AM
Grènman
Reidar
R
Peltonen
Juha
J
Peltonen
Sirkku
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D015820:Cadherins / Q000378:metabolism; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005865:Gestational Age; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D009186:Myelin Sheath / Q000378:metabolism; D062793:Occludin; D010525:Peripheral Nerves / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D010750:Phosphoproteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012583:Schwann Cells / Q000378:metabolism* / Q000648:ultrastructure; D019108:Tight Junctions / Q000378:metabolism*; D055815:Young Adult; D062826:Zonula Occludens-1 Protein
D015820:Cadherins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein