Worm Breeder's Gazette 13(2): 88 (February 1, 1994)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Intracellular tight junctions, such as zonula occludentes are known to form regulated barrier zones between both endothelial and the cells of epithelium, and provide a means to separate tissue compartments in higher animals. Recently a number of genes encoding "tight junction" proteins have been characterized from different species, such as the discs large tumor suppressor dlg gene of Drosophila (Woods & Bryant, 1991); human erythrocyte membrane protein p55 (Cho et al., 1992), PSD-95 from the rat brain synapses (Sadler et al, 1992), ZO-1 from human cells (Willot et al., 1993), and 220 kDa protein from mouse (Itoh et al., 1993). Although extremely different in the length of the primary sequence, a hallmark of these proteins is the presence of the SH3 and guanylate kinase domain that may not have the proper catalytic function.
Using the monoclonal antibody T4192 raised against the mouse 220 KDa protein, we have screened a C. elegans cDNA expression library and cloned a cDNA that encodes a novel protein with no strong homology to the tight junction proteins, but shows the presence of the conserved amino acid residues in the SH3 and GK domains. The cDNA probe recognizes only one clone on the polytene filter, the Y50C3 ,that places the ( cej-1 , cell junction -1)gene in the cluster on chromosome III near the mab-21 locus, in a region covered by three cosmid clones ( F35G12 , T23C9 ,and F1 OG11).Screening a genomic library, we have identified a positive clone corresponding to the cej-1 cDNA probe, and have subcloned a 9 kb genomic fragment that includes the gene. Southern blot analysis suggests that the cej-1 is a single copy gene, and the Northern blot data indicates that it encodes a mRNA of 1.5 kb. Immunocytochemical staining of the nematode on wholemount squash preparations using T4192 antibody which recognizes a 34 kDa protein on immunoblots, reveals that the antigen is present during embryogenesis at cell junctions both during the early and late embryonic development. In the larvae and adults, staining of the neural tissue and the excretory canal (H - Cell) is observed.
We thank A. Coulson and other members of the Sanger Centre for their assistance in providing the YAC clones.