[
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.
[
Life Sci Space Res (Amst),
2014]
Recent advances in the field of molecular biology have demonstrated that small non-coding microRNAs (miRNAs) have a broad effect on gene expression networks and play a key role in biological responses to environmental stressors. However, little is known about how space radiation exposure and altered gravity affect miRNA expression. The "International Space Biological Experiments" project was carried out in November 2011 by an international collaboration between China and Germany during the Shenzhou-8 (SZ-8) mission. To study the effects of spaceflight on Caenorhabditis elegans (C. elegans), we explored the expression profile miRNA changes in space-flown C. elegans. Dauer C. elegans larvae were taken by SZ-8 spacecraft and experienced the 16.5-day shuttle spaceflight. We performed miRNA microarray analysis, and the results showed that 23 miRNAs were altered in a complex space environment and different expression patterns were observed in the space synthetic and radiation environments. Most putative target genes of the altered miRNAs in the space synthetic environment were predicted to be involved in developmental processes instead of in the regulation of transcription, and the enrichment of these genes was due to space radiation. Furthermore, integration analysis of the miRNA and mRNA expression profiles confirmed that twelve genes were differently regulated by seven miRNAs. These genes may be involved in embryonic development, reproduction, transcription factor activity, oviposition in a space synthetic environment, positive regulation of growth and body morphogenesis in a space radiation environment. Specifically, we found that cel-miR-52, -55, and -56 of the miR-51 family were sensitive to space environmental stressors and could regulate biological behavioural responses and neprilysin activity through the different isoforms of T01C4.1 and F18A12.8. These findings suggest that C. elegans responded to spaceflight by altering the expression of miRNAs and some target genes that function in diverse regulatory pathways.