NaCl flux between apical and basolateral side recruits claudin-1 to tight junction strands and regulates paracellular transport.
In multicellular organisms, epithelia separate and divide the internal environment maintaining appropriate conditions in each compartment. To maintain homeostasis in these compartments, claudins, major cell adhesion molecules in tight junctions (TJs), regulate movements of several substances through the paracellular pathway (barrier function). In this study, we investigated effects of the flux of several substances between apical and basolateral side on paracellular transport and TJ protein localization. NaCl flux from apical to basolateral side increased paracellular conductance (Gp) and recruited claudin-1 from lateral cell membrane to the apical end with the colocalization with occludin, one of the TJ proteins concentrated at TJ strands. Oppositely-directed flux of sucrose against NaCl flux inhibited these reactions and same directional flux of sucrose with NaCl enhanced the increase of Gp, whereas 10-kDa dextran inhibited these reactions regardless of the side of administration. Our present findings indicated that TJ protein localization and barrier function are regulated depending on the environmental differences between apical and basolateral side.
Tokuda
Shinsaku
S
Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan. s_tokku@yahoo.co.jp
Miyazaki
Hiroaki
H
Nakajima
Ken-Ichi
K
Yamada
Toshiki
T
Marunaka
Yoshinori
Y
D000818:Animals; D002460:Cell Line; D062445:Claudin-1; D003911:Dextrans / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D021381:Protein Transport / Q000187:drug effects; D012965:Sodium Chloride / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism*; D014981:Xenopus
D062445:Claudin-1; D003911:Dextrans; D008565:Membrane Proteins; D012965:Sodium Chloride