Worm Breeder's Gazette 13(3): 95 (June 1, 1994)

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.

wnt homologs in Caenorhabditis elegans

Supriya Shivakumar, Gregg Jongeward, Cynthia Kenyon, Harold Varmus

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University of California, San Francisco, CA 94143

The wnt gene family encodes cysteine-rich secreted proteins which have been shown to act as important regulators of early development in the frog, fly and mouse. wnt genes have a crucial role in intercellular signaling in the mouse CNS development and in pattern formation in the fly. We chose to study the normal role of Ce- wnt-1 in signaling in C. elegans development.

Two members of the wnt gene family have been identified in C. elegans, Ce- wnt-1 (1) and Ce- wnt-2 (2). The Ce- wnt-1 gene encodes a 372 amino acid protein and shares 22 of the 24 cysteines found among other members of the wnt family. A 1.4 kb transcript (including an SL1 transpliced leader sequence) is detected at high levels in embryos and at lower levels at all other stages. The 15 kb Ce- wnt-2 cDNA is also expressed in a similar temporal pattern to Ce- wnt-1 .The Ce- wnt-2 cDNA encodes a protein of 362 amino acids with 22 of the cysteines shared among other Wnt proteins. Neither Ce- wnt-1 and Ce- wnt-2 are direct homologs of any specific wnt genes in other organisms.

To elucidate the functions of the Ce- wnt-1 gene product, we have isolated mutations in the gene. The Ce- wnt-1 locus maps to the left arm of chromosome II, but does not appear to correspond to any existing mutations. We made the assumption that the Ce- wnt-1 gene is required for viability based on wnt mutant phenotypes in other species. We screened for psoralen induced lethal mutations balanced by an extrachromosomal array comprising a 15 kb lambda clone containing the Ce- wnt-1 gene and a marker ( rol-6 (D))in a F2 clonal screen (see diagram below). 1500 F2 animals were screened and 2 embryonic lethal alleles were isolated. Both contain deletions in the Ce- wnt-1 coding region. These mutations are rescued by the lambda clone, but not by rol-6 .A 5.5 kb subclone also rescues the lethality. We are now trying to demonstrate conclusively that this early embryonic lethality is due to the disruption of the Ce- wnt-1 gene.

We have also screened for psoralen induced mutations (in an identical screen) that require a cosmid clone containing Ce- wnt-2 .We have identified a number of mutations in the screen which we are now analyzing in more detail.

Literature Cited:

(1) Shackleford et al., Oncogene 8:1857 (1993)

(2) Waterston et al. Nature genetics 1:114 (1992)

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