M. Koppen et al., Cooperative regulation of AJM-1 controls junctional integrity in Caenorhabditis elegans epithelia, NAT CELL BI, 3(11), 2001, pp. 983-991
The function of epithelial cell sheets depends on the integrity of speciali
zed cell-cell junctions that connect neighbouring cells. We have characteri
zed the novel coiled-coil protein AJM-1, which localizes to an apical junct
ional domain of Caenorhabditis elegans epithelia basal to the HMR-HMP (cadh
erin-catenin) complex. In the absence of AJM-1, the integrity of this domai
n is compromised. Proper AJM-1 localization requires LET-413 and DLG-1, hom
ologues of the Drosophila tumour suppressors Scribble and Discs large, resp
ectively. DLG-1 physically interacts with AJM-1 and is required for its nor
mal apical distribution, and LET-413 mediates the rapid accumulation of bot
h DLG-1 and AJM-1 in the apical domain. In the absence of both dlg-1 and le
t-413 function AJM-1 is almost completely lost from apical junctions in emb
ryos, whereas HMP-1 (alpha -catenin) localization is only mildly affected.
We conclude that LET-413 and DLG-1 cooperatively control AJM-1 localization
and that AJM-1 controls the integrity of a distinct apical junctional doma
in in C. elegans.