The tight junction protein complex undergoes rapid and continuous molecular remodeling at steady state.
The tight junction defines epithelial organization. Structurally, the tight junction is comprised of transmembrane and membrane-associated proteins that are thought to assemble into stable complexes to determine function. In this study, we measure tight junction protein dynamics in live confluent Madin-Darby canine kidney monolayers using fluorescence recovery after photobleaching and related methods. Mathematical modeling shows that the majority of claudin-1 (76 +/- 5%) is stably localized at the tight junction. In contrast, the majority of occludin (71 +/- 3%) diffuses rapidly within the tight junction with a diffusion constant of 0.011 microm(2)s(-1). Zonula occludens-1 molecules are also highly dynamic in this region, but, rather than diffusing within the plane of the membrane, 69 +/- 5% exchange between membrane and intracellular pools in an energy-dependent manner. These data demonstrate that the tight junction undergoes constant remodeling and suggest that this dynamic behavior may contribute to tight junction assembly and regulation.
Shen
Le
L
Department of Pathology, The University of Chicago, Chicago, IL 60637, USA.
Weber
Christopher R
CR
Turner
Jerrold R
JR
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D062445:Claudin-1; D019295:Computational Biology; D003198:Computer Simulation; D004058:Diffusion; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology; D036681:Fluorescence Recovery After Photobleaching; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D019108:Tight Junctions / Q000737:chemistry* / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein