Y. Ando-akatsuka et al., Differential behavior of E-cadherin and occludin in their colocalization with ZO-1 during the establishment of epithelial cell polarity, J CELL PHYS, 179(2), 1999, pp. 115-125
At the initial stage of cell-cell contact of epithelial cells, primordial s
pot-like junctions are formed at the tips of thin cellular protrusions radi
ating from adjacent cells, where E-cadherin and ZO-1 are precisely coconcen
trated (Yonemura et al., 1995, J. Cell Sci. 108:127-142). In fully polarize
d epithelial cells, E-cadherin and ZO-1 are completely sorted into belt-lik
e adherens junctions (AJ) and tight junctions (TJ), respectively. Here we e
xamined the behavior of occludin, an integral membrane protein consisting o
f TJ, during the establishment of epithelial cell polarity. Using confocal
immunofluorescence microscopy, we quantitatively compared the spatial relat
ionship of occludin/ZO-1 with that of E-cadherin/ZO-1 during epithelial cel
lular polarization by replating or wounding cultured mouse epithelial cells
(MTD1-A). At the initial stage of cell-cell contact, E-cadherin and ZO-1 a
ppeared to be simultaneously recruited to the primordial form of spot-like
junctions at the tips of cellular processes which showed no concentration o
f occludin. Then, as cellular polarization proceeded, occludin was graduall
y accumulated at the ZO-1-positive spot-like junctions to form belt-like TJ
, and in a complementary manner E-cadherin was sorted out From the ZO-1-pos
itive spot-like junctions to form belt-like AJ. The molecular mechanism of
TJ/AJ formation during epithelial cellular polarization is discussed with s
pecial reference to the roles of ZO-1. (C) 1999 Wiley-Liss, Inc.