Mutations in genes of the
daf-2 insulin/insulin-like growth factor signaling (IIS) pathway have been found to extend adult lifespan in C. elegans1. This increase in lifespan resulting from decreased IIS is supressed by a loss of function of the
daf-16 gene which encodes a forkhead transcription factor2,3. A microarray analysis was carried out at the Sanger Institute on two temperature sensitive (ts) long-lived strains of C. elegans:
daf-2(
sa193) and
daf-2 (
m41), and compared their transcription profiles to those of wild type N2 and
daf-7 (
e1372) ts adult worms. From this study, 1,700 genes were identified as being 2-fold up- or down-regulated in the long-lived nematodes. These 1,700 genes were compared to the gene expression profiles obtained from other microarray ageing studies4,5,6. Based on these comparisons we selected 20 up- and 20 down-regulated genes for gene knockout analysis by RNAi. An RNAi feeding protocol was designed using the ts sterile C. elegans mutant
glp-4 (
bn2 ts).
glp-4 nematodes were fed on the E. coli dsRNA feeding strains and lifespan was measured by counting the number of live nematodes every second day. A long-lived control consisting of a C. elegans
glp-4 fed on
daf-2 dsRNA expressing E. coli (
daf-2 knockout) and a normal lifespan control consisting of C. elegans
glp-4 fed on E. coli transformed with the empty vector (no gene knockout) were also used. These experiments are ongoing. Our results to date show that RNAi of 4 down-regulated genes increases lifespan and RNAi of 3 up-regulated genes decreases lifespan. We will report on our progress on these RNAi experiments. We are grateful to Dr. Patricia Kuwabara in whose laboratory the microarry experiment was carried out, to Dr. David Gems and Dr. Joshua McElwee for helpful discussions and to Enterprise Ireland for financial support. 1. Kenyon, C. et al. (1993). Nature 366, 461-464. 2. Lin K. et al. (1997). Science 278, 1319-1322. 3. Ogg. S. et al. (1997). Nature 389, 994-999. 4. Murphy, C.T. et al. (2003). Nature, 424, 277-284. 5. Kimura, K.D. et al. (1997). Nature, 277, 942-946. 6. McElwee J.J. et al. (2004). J. Biol. Chem. 279, 44533-44543.