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

579
579. Nuclear Receptors Required for
Molting in C. elegans
Chris R. Gissendanner 1,2 , Ann E.
Sluder 1
1 Cambria Biosciences, Bedford, MA 01730
2 Dept. of Cellular Biology, University of
Georgia, Athens, GA 30602
C. elegans, like other nematodes, undergoes a
molting process that marks the transition
between developmental stages. During the molt,
cuticle of the next developmental stage is
synthesized while cuticle from the previous
stage is shed (ecdysed). The regulation of
molting in nematodes has been an important
focus in nematode parasitology research for
many years, but has not been extensively
investigated in C. elegans.
Using a functional genomics approach, we have
identified two putative transcriptional regulators
of the molting process. NHR-25 and NHR-41
are conserved members of the nuclear receptor
(NR) superfamily of transcription factors. The
insect orthologs of NHR-25 and NHR-41,
FTZ-F1 and HR78 respectively, function in the
ecdysone cascade during insect metamorphosis
and molting. Strikingly, the C. elegans genes
also appear to be required for the molting
process, suggesting the existence of a conserved
transcriptional pathway that regulates the
molting process in invertebrates.
nhr-25 and nhr-41 are expressed in different cell
types. nhr-25 is expressed in the epidermis
while nhr-41 is expressed in specific anterior
and posterior neurons as well as the gut. Loss of
gene function for nhr-25 and nhr-41 generate
similar molting defects; however, their
distinctive expression patterns suggest the
regulation of different molting processes.
Although nhr-25 also has other epidermal
development functions, we have demonstrated
that nhr-25 and nhr-41 have a molting-specific
function and that their expression levels cycle
with the molt. A discussion of the possible roles
of these genes during the molting process will
be presented.
580. A systematical gene expression
screen of the Caenorhabditis elegans
cytochrome P450 genes.
Ralph Menzel 1 , Thierry Bogaert 2 ,
Rudolf Achazi 1
1 Department of Biology, Institute of
Ecotoxicology & Biochemistry, Free
University Berlin, Ehrenbergstr. 26-28, 14195
Berlin, Germany
2 DEVGEN N.V., Technologiepark 9, 9052
Gent-Zwijnaarde, Belgium
580
Cytochromes P450 (CYP) are a super family of
heme containing NADPH dependent
monooxygenases which catalyze the oxidative
metabolism of many exogenous and endogenous
compounds. These proteins have been
particularly implicated in the biotransformation
of many drugs and other xenobiotics. Moreover,
P450 gene expression can be induced by the
presence of these compounds in the medium.
The soil nematode Caenorhabditis elegans is
probably the simplest animal having the status
of a laboratory model. Its genome contains the
remarkable number of 80 cytochrome P450
genes.
In order to study CYP gene expression worms
were exposed to 18 different cytochrome P450
inducers. Using subfamily-specific primers we
could amplify a pooled set of exon-rich CYP
fragments to create a P450 subfamily specific
gene filter. In that way we were able to check
systematically the influence of the different
inducers to CYP expression at the same time.
Interestingly, the well known CYP1A inducers
β-naphtoflavone, PCB52 and Lansoprazol were
the most active ones, especially in case of
family CYP35. Taking advantage of the C.
elegans whole genome DNA microarray created
in Stuart Kim’s lab (Stanford University, USA)
we could confirm and extend our results
significantly. Differentially expressed CYP
genes were further analyzed by a
semi-quantitative RT-PCR. The strongest
expression were observed for the genes
CYP35A1-4 and 35C1. In addition, a transgenic
C. elegans line expressing GFP under control of
the CYP35A2 promoter showed a strong
induction of the fusion by β-naphthoflavone in
the intestine. Altogether, xenobiotic inducible
gene expression of C. elegans could be a useful
tool to develop a biomonitoring screening