Program of the 2001 International Worm Meeting - Sternberg Lab ...

612
612. Insulin/IGF-like peptides of C.
elegans
Tsuyosi Kawano 1 , Youhei Ito 1 ,
Yuka Kobayashi 1 , Yasuo Kimura 1 ,
Kyoko Takuwa 2 , Masaji Ishiguro 2 ,
Terumi Nakajima 2
1 Dept. of BIological and Environmental
Chemistry, Tottori University, Koyama,
Tottori, Tottori 680-8553, Japanyama
2 Suntory Institute for Bioorganic Research,
Simamoto, Mishina, Osaka 618-8503, Japan
Insulin/IGF-like peptides of C. elegans
Tsuyoshi Kawano1, Youhei Ito1, Yuka
Kobayashi1, Takeshi Tada1, Kyoko Takuwa2,
Masaji Ishiguro2, Terumi Nakajima2, and
Yasuo Kimura1 1Department of Biological and
environmental Chemistry, Tottori University,
Tottori 680-8553, Japan and 2Suntory Institute
for Bioorganic Research, Osaka 618-8503,
Japan
An insulin/IGF-I receptor homolog of C.
elegans, DAF-2, is involved in the diapause,
aging, and fat metabolism of the organism. We
have searched candidates of the DAF-2 ligands
and identified three insulin/IGF-like peptides
designated Ceinsulin-1, -2, and -3. These
peptides possess six cystein residues conserved
among insulin/IGF peptide family. Ceinsulin-1
and -2 do not have a definite D domain
characteristic of IGFs and show some degrees of
sequence identify. On the other hand,
Ceinsulin-3 has a definite D domain and shows
little sequence similarity to Ceinsulin-1 and -2.
Predicted tertiary structures of Ceinsulin-1 and
-2 by computer modeling are quite similar to
each other, suggesting that these peptide should
recognize a same receptor. The developmental
expression patterns of these peptides were
examined by RT-PCR and Western blotting.
The expression pattern of Ceinsulin-3 is
somewhat different from those of Ceinsulin-1
and -2. The RNAi experiments revealed that the
Ceinsulin-1 and -3 are involved in aging and fat
metabolism, respectively. The physiological
function of Ceinsulin-2 remains unknown. We
hypothesize that each of the peptides has its own
physiological function in the diapause, aging, or
fat metabolism via the DAF-2.
613. daf-2 signalling into the cell:
looking for the second pathway
Manoj Nanji, David Gems
613
Department of Biology, University College
London, 4 Stephenson Way, London NW1 2HE,
UK
The daf-2/age-1/daf-16 pathway regulates
numerous aspects of life history including early
development, the dauer/non-dauer decision,
fertility and life span (1). Mutations in daf-2, a
homologue of vertebrate insulin and IGF-I
receptors, or in age-1, a subunit of
phosphoinositide 3-kinase (PI3K), cause dauer
larva arrest, and can double adult life (2-4).
Other components of the pathway include
daf-18 (PTEN phosphatase), pdk-1
(phosphoinositide-dependent kinase), and akt-1
and akt-2 (protein kinase Bs). The latter
inactivate DAF-16, a forkhead transcription
factor, probably by phosphorylation.
Although this signal transduction pathway
between daf-2 and daf-16 has been well defined,
several findings suggest the existence of a
second daf-2-daf-16 pathway. For example,
phenotypic analysis of 15 daf-2 mutants, which
fall into two distinct classes, suggested that the
gene has two functional components, daf-2A
and daf-2B (4). These potentially correspond to
different signalling pathways emanating from
daf-2 into the cell; daf-2B is likely to correspond
to the PI3K pathway (4). In addition, a
gain-of-function allele of akt-1(5), and the
hypomorphic allele daf-18(e1375), fully
suppress the dauer constitutive (Daf-c)
phenotype of several severe age-1 alleles yet
only weakly suppress the relatively weak allele,
daf-2(e1370).
To investigate and characterise the putative
second daf-2 pathway, we are carrying out
interaction studies between several class 1 and
class 2 daf-2 alleles and various components of
the PI3K and other signalling pathways.
Preliminary results suggest a possible identity
for the daf-2A pathway. We will present the
results of these interactions studies.
(1) Guarente, L., Kenyon, C. Nature 408: 255
(2000). (2) Kimura, K.D. et al. Science 277: 942
(1997). (3) Morris, J.Z. et al. Nature 382: 536
(1996). (4) Gems, D. et al., Genetics 150: 129
(1998). (5) Paradis, S. & Ruvkun, G. Genes