The Caenorhabditis elegans hemidesmosome or fibrous organelle (FO) is a trans-epidermal attachment structure that spans the hypodermis, linking the basal hypodermal membrane to the cuticle, thereby transducing the force of muscle contraction to the exoskeleton and propagating movement. The hemidesmosome has a similar structure and the same localisation and function as the vertebrate hemidesmosome, but there is little direct homology between the components except for the intermediate filaments (IFs), and the plectin VAB-10A (Boscher, 2003; Hahn, 2001). .
gei-16 was isolated in a RNA interference (RNAi) screen for potential anthelminthic drug targets because it fulfilled the selection criteria of being nematode specific, and when knocked down results in lethality at many stages of development, sterility and paralysis. Specifically, RNAi of
gei-16 in C.elegans results in slow development, and muscle weakness before paralysis, arrest and death in the later larval and adult stages. It appears that
gei-16 is necessary for maintaining adhesion of the muscles and cuticle to the hypodermis as depletion of
gei-16 message causes 100% penetrance of a muscle detachment phenotype, and a 47% penetrance of a cuticular detachment phenotype. Epithelial morphogenesis is also affected with larvae and adults showing uneven excretory channels and abnormal vulval morphogenesis. RNAi affected worms often arrest or die before the maturation of the reproductive system. Worms that survive to adulthood produce few eggs, which are retained within the uterus and often fail to hatch. This appears to be due to the combined failure of vulval morphogenesis, detachment of the vulval muscles and a failure of the embryo to elongate. Localisation of
gei-16 mRNA to all muscle-apposed epithelia is consistent with a role in epithelial tissue stability and morphogenesisan expression pattern which mirrors that of hemidesmosome components. Furthermore, RNAi in GFP reporter strains of C. elegans shows that components of the hemidesmosome are disorganised in
gei-16 RNAi worms. Results from the interactome data set show that
gei-16 binds to
mua-6, an IF in the hemidesmosome (Li et al, 2000). . References:. BOSHER, et al. (2003) The Caenorhabditis elegans
vab-10 spectraplakin isoforms protect the epidermis against internal and external forces. J Cell Biol, 161, 757-68.. HAHN, B. S. & LABOUESSE, M. (2001) Tissue integrity: hemidesmosomes and resistance to stress. Curr Biol, 11, R858-61.. LI, S, et al. (2004) A map of the interactome network of the metazoan C. elegans. Science, 303, 540-3.