title: The tight junction component protein, claudin-4, is expressed by enteric neurons in the rat distal colon.
abstract: The expression of a tight junction (TJ) component protein, claudin-4, in the enteric neurons was investigated in the rat distal colon by immunohistochemistry and RT-PCR. Claudin-4 immunoreactivity was detected in almost all neurofilament-positive enteric neurons both of the submucosal and the myenteric plexuses, and both of the cell bodies and the neurofibers. The immunoreactivity of enteric neurons for claudin-4 was divided into two types: strongly and weakly positive neurons. Especially in the myenteric plexus, the stained neurons were classified by Dogiel's morphological classification of enteric neurons. The strongly stained claudin-4 positive neurons show Dogiel type II morphology, while the weakly stained claudin-4 positive neurons show Dogiel type I morphology. These immunohistochemical data were supported by mRNA expression in the muscle plus submucosa preparation containing the submucosal and myenteric plexuses, as well as mucosa preparation. The physiological function of claudin-4 expressed on enteric neurons is unclear up to now. It is however suggested that claudin-4 expressed on enteric neurons might play roles for the neural activity, for example as insulation between neurofibers. In conclusion, the present study clearly shows that claudin-4 is expressed by enteric neurons. This is the first evidence that the neuron itself expresses the TJ component protein, claudin-4, in the nervous system.
authors.affiliation: Laboratory of Physiology, Institute for Environmental Sciences, and Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Karaki
authors.forename: Izumi
authors.initials: I
authors.lastname: Kaji
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Otomo
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tazoe
authors.forename: Atsukazu
authors.initials: A
authors.lastname: Kuwahara
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D062506:Claudin-4; D003106:Colon / Q000294:innervation* / Q000502:physiology; D017615:Enteric Nervous System / Q000166:cytology / Q000378:metabolism*; D005725:Ganglia, Autonomic / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013368:Submucous Plexus / Q000166:cytology / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D062506:Claudin-4; D008565:Membrane Proteins; D012333:RNA, Messenger