Neighboring cells of most invertebrate and vertebrate tissues can communicate with each other through intercellular channels called gap junctions. Gap junctions play important roles in development and cellular functions. Mutations of gap junction proteins may cause a variety of diseases, including demyelination, deafness, female infertility, cataracts, cardiac arrhythmias or malformation, embryonic lethality, and possibly cancer. Gap junctions may be formed by connexins, innexins, and pannexins. Although the three families of proteins are distinct in primary sequence, gap junctions formed by them share major structural and functional properties. Gap junction proteins of the same family may self-assemble or co-assemble to form gap junctions, and get localized to specific subcellular domains. Subunit-specific assembly and appropriate subcellular localization are critical to the function of gap junctions. However, their mechanisms are poorly understood. The aims of this proposal are to use the nematode Caenorhabditis elegans body-wall muscle as a model system to (1) identify gap junction proteins expressed, and evaluate their roles in electrical coupling and locomotion; (2) determine if the identified gap junction proteins self-assemble or co-assemble into gap junctions by coimmunostaining, labeling with distinct fluorescent proteins, and co-expression in Xenopus oocytes; and (3) isolate mutants showing subcellular mislocalization of a green fluorescent protein-tagged gap junction protein so that proteins mediating gap junction subcellular localization may be identified through analyses of the mutants in subsequent studies. The long-term goal is to understand functions, subunit-specific assembly, and mechanisms of subcellular localization of gap junctions.
