AJM-1
Supplemental material for the following paper:
Köppen, M., Simske, J.S., Sims, P.A., Firestein, B.L., Hall, D.H., Radice, A.D., Rongo, C., and Hardin, J.D. (2001). Cooperative regulation of AJM-1 controls junctional integrity in Caenorhabditis elegans epithelia. Nat Cell Biol3, 983-991. PubMed
Summary
The function of epithelial cell sheets depends on the integrity of specialized cell-cell junctions that connect neighboring cells. We have characterized the novel coiled-coil protein AJM-1, which localizes to an apical junctional domain of Caenorhabditis elegans epithelia basal to the HMR/HMP (cadherin/catenin) complex. In the absence of AJM-1, the integrity of this domain is compromised. Proper AJM-1 localization requires LET-413 and DLG-1, homologues of the Drosophila tumour suppressors Scribble and Discs large, respectively. DLG-1 physically interacts with AJM-1 and is required for its normal apical distribution, while LET-413 mediates rapid accumulation of both DLG-1 and AJM-1 to the apical domain. Loss of both dlg-1 and let-413 function results in almost complete loss of AJM-1 from apical junctions in embryos, while HMP-1/a-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 subdomain of epithelial junctions in C. elegans.
Movie #1: – Dynamic analysis of AJM-1::GFP in a let-413(RNAi) and wild-type embryo
Description: A let-413(RNAi) embryo (on the left) and a similarly staged wild-type embryo (on the right) expressing ajm-1::gfp were analyzed simultaneously. Frames were acquired at 5 min intervals; ventral views, anterior is to the left. At the onset of ventral enclosure, the let-413 embryo shows a reduced and punctate junctional AJM-1::GFP pattern, while the pattern in the wild-type embryo is even and continuous. After enclosure, during the process of elongation, additional AJM-1::GFP accumulates in the junctions of the let-413 embryo, resulting in a significantly more continuous pattern. In the wild-type embryo, the AJM-1::GFP pattern remains even and continuous throughout development. This indicates a delay in junctional accumulation of AJM-1::GFP in the absence of let-413 function. The let-413 embryo arrests after the 1.5-fold stage, while the wild-type embryo elongates past the 3-fold stage.
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Movie #2: – Dynamic analysis of DLG-1::GFP in a wild-type embryo
Description: A wild-type embryo expressing dlg-1::gfp is shown during ventral enclosure and subsequent elongation past the 1.5-fold stage. Frames were acquired at 5 min intervals; ventral view, anterior is to the left. DLG-1::GFP forms an even, continuous pattern at all stages.
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Movie #3:- Dynamic analysis of DLG-1::GFP in a let-413(RNAi) embryo
Description: A let-413(RNAi) embryo expressing dlg-1::gfp was analyzed during ventral enclosure and subsequent elongation past the 1.5-fold stage. Frames were acquired at 5 min intervals; ventral view, anterior is to the left. At the onset of ventral enclosure, the let-413 embryo shows a reduced and punctate junctional DLG-1::GFP pattern. After enclosure, during the process of elongation, additional DLG-1-GFP accumulates in the junctions of the let-413 embryo resulting in a significantly more continuous pattern. This indicates a delay in junctional accumulation of DLG-1::GFP in the junctions in the absence of let-413 function.
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