[
International Worm Meeting,
2003]
In all metazoa the regulation of cell-cell-signaling is essential for development and behaviour. Neprilysins (NEP, neutral endopeptidases), transmembrane proteins belonging to the big family of zinc-metalloproteases, play a central regulatory role in these processes. In mammals, their main function is the hydrolysis of small neuropeptides at the cell surface leading to a termination of signals between neurons. In C. elegans more than 20 putative neprilysin genes are known but until now the physiological function of their corresponding proteins is unclear. Five of these neprilysins (F18A12.8, F26G1.6, T05A8.4, T16A9.4 and ZK20.6) show more than 30 % amino acid sequence identity to the mammalian neprilysin EC3.4.24.11. NEP-knockout mice show a decreased -opioid receptor density in the brain, increased aggression behaviour and altered locomotion activity. We are interested in effects on C. elegans behaviour and development caused by knockout of neprilysins. RNAi experiments were performed without detecting a change of the wild type phenotype. In parallel, a NEP deletion mutant was isolated by screening EMS-mutagenesis libraries. The knockout strain shows decreased, uncoordinated locomotion when compared to wild type. A temperature shift (from 20 to 26C) leads to a high embryonal lethality in these NEP deletion animals. We are continuing the characterisation of the deletion mutant strain and screen for additional NEP deletion mutants.
[
International C. elegans Meeting,
1999]
Cell-surface peptidases participate in the postsecretory processing and metabolism of neuropeptides and peptide hormones. Neutral endopeptidase-24.11 (NEP) is the prototype of a mammalian subfamily of zinc metallopeptidases that also includes endothelin-converting enzyme (ECE), the product of the PEX gene and KELL, an erythrocyte cell-surface antigen. These enzymes have central roles in a variety of physiological and disease processes, including cardiovascular function, cartilage and bone metabolism, inflammation and embryogenesis. Human zinc metalloproteinases belonging to this subfamily are important targets for therapeutic drugs. C. elegans has in the region of 90 genes with the zinc-binding consensus motif HEXXH of the superfamily of zinc metalloproteinases. Cluster analysis of predicted amino acid sequences reveals a group of 8 genes with closer similarity to mammalian NEPs/ECEs than the others. Hydrophobicity plots of the predicted protein sequences for these 8 genes revealed 5 that gave the expected domain structure seen in mammalian homologues; a short NH 2 -terminus intracellular region, a single transmembrane domain and a large extracellular region with a COOH-terminus active site. Expression patterns of beta-galactosidase and GFP have been obtained for 4 of these genes. T16A9.4 has a largely neuronal expression pattern with a pharyngeal and vulva muscle component; ZK970.1 and T05A8.4 are expressed in body wall muscle cells; ZK20.6 is pharynx specific. RNA interference experiments are being conducted with these genes to determine any null phenotypes.