Worm Breeder's Gazette 15(4): 31 (October 1, 1998)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Characterization of C.elegans ASK-1 MAP kinase kinase kinase

Junko Hyodo, Naoki Hisamoto, Kunihiro Matsumoto

Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602 JAPAN

  Mitogen-activated protein kinase (MAPK) cascades are activated in
response to various extracelluler stimuli, including growth factors and
environmental stresses. Mammalian ASK1 belongs to MAP kinase kinase
kinase superfamily. ASK1 activates two different subgroups of MAP kinase
kinase, SEK1 (MKK4) and MKK3/MKK6, which in turn activate SAPK/JNK
(stress-activated protein kinase/ c-Jun amino-terminal kinase) and p38
subgroups of MAPK family, respectively. ASK1 is proposed to play an
essential role in the mechanism of stress- and cytokine-induced
apoptosis in mammals. 
  We have identified a C.elegans homolog of ASK1, named ask-1, from the
C.elegans genome database. We have isolated the ask-1 cDNA clone by PCR.
Sequence analysis revealed that it encodes a 1397 amino acid protein
with 63% identity in the kinase domain and 40% identity in the full
length to the ASK1 protein. In total RNA isolated from mixed stage
population of wild-type, ask-1 cDNA probes recognized a single band of
approximately 5 kb on northern blots. 
  To determine the ask-1 expression pattern, we have generated
transgenic lines carrying GFP driven by the ask-1 promoter (ASK-1 ::GFP)
in N2. ASK-1::GFP was strongly expressed in intestine, epidermis,
excretory canal and some neurons. These expressions could be detected
from 1.5-fold stages to adulthood.
  To predict the phenotype resulting from loss-of-function of ask-1, we
used RNA-mediated interference with gene function (RNAi). We injected
sense RNA to a strain expressing GFP in neurons (obtained from T.
Ishihara and S. Takagi). In most of F1 hermaphrodites from injected
worms, migration of posterior lateral ganglions was disrupted.
Furthermore, an excess cell body-like structure was observed around the
posterior lateral ganglions in 30% of the progeny of the animals. These
results suggest that ask-1 may participate in the proper cell migration.