Worm Breeder's Gazette 14(1): 52 (October 1, 1995)

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.

mig-5 is a C. elegans Member of the dsh Family

Chaobo Guo, Edward Hedgecock

Department of Biology , Johns Hopkins University, Baltimore, MD 21218

Cell fate determination and cell migration are two essential
events in the development of animals.  mig-5 controls various cell
fates and migrations in C. elegans.  In mutants of mig-5, the
descendants of the QL neuroblast fail to migrate posteriorly but
instead migrate anteriorly.  Distal tip cells (DTCs) leading the
gonad arms make precocious dorsal turns or migrate along abnormal
tracks.  Also, the DTCs are often absent and occasionally an extra
DTC is present.  Two anchor cells are sometimes present in the
hermaphrodite gonad and two linker cells are usually present in the
male gonad.  In the vulval equivalence group, secondary vulval
precursor cells are often missing, while in the preanal equivalence
group, the P12 cell often adopts a P11 cell fate.  Between the two
alleles of mig-5, rh147 is stronger than rh94 with respect to the
DTC lost phenotype.  Either maternal or zygotic expression of normal
mig-5 is sufficient for wild type phenotype.

mig-5 has been cloned by Southern analysis of chromosomal
deletions and transgenic rescue experiments.  mig-5 is located on
cosmid T05C12 in the center of chromosome II.  mig-5 is predicted to
encode an intracellular protein with 666 amino acids.  The protein
has three conserved domains that have a high degree of homology to
the Drosophila dsh gene product, in addition, the sub-domain B2 has
homology with seven other proteins, such as the Drosophila discs
large tumor suppresser protein.  The homologues of dsh have also
been found in several other species, including human.  In
Drosophila, DSH is a common component in both the wingless and
frizzled signal transduction cascades and probably is also involved
in the notch signaling pathway.  In C. elegans, mig-5 mutants share
partial phenotypes with the mutants of the C. elegans homologues of
wingless (lin-44), frizzled (lin-17) and notch. (lin-12).

Cloning mig-5  makes it possible to study the role of dsh  in
three important signaling pathways in C. elegans and will lead to a
better understanding of the mechanisms of signal transduction in
cell fate determination and cell migration.