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Published October 1994 | Published
Journal Article Open

The lin-3/let-23 pathway mediates inductive signalling during male spicule development in Caenorhabditis elegans


During Caenorhabditis elegans male spicule development, four pairs of precursor cells respond to multiple positional cues and establish a pattern of fates that correlates with relative anterior-posterior cell position. One of the extracellular cues is provided by the F and U cells, which promote anterior fates. We show that the genes in the lin-3/let-23 signalling pathway required for hermaphrodite vulval induction also mediate this F/U signal. Reduction-of-function mutations in lin-3, let-23, sem-5, let-60 or lin-45 disrupt the fate of anterior cells. Likewise, activation of the pathway with ubiquitously produced signal results in posterior cells inappropriately adopting the anterior fates even in the absence of F and U. We have further used this genetic pathway to begin to understand how multiple positional cues are integrated to specify cell fate. We demonstrate that lin-15 acts in spicule development as it does in vulval induction, as a negative regulator of let-23 receptor activity. A second extracellular cue, from Y.p, also acts antagonistically to the lin-3/let-23 pathway. However, this signal is apparently integrated into the lin-3/let-23 pathway at some step after lin-45 raf and is thus functionally distinct from lin-15. We have also investigated the role of lin-12 in forming the anterior/posterior pattern of fates. A lin-12 gain-of-function defect is masked by redundant positional information from F and U.

Additional Information

© 1994 The Company of Biologists Limited. Accepted 29 June 1994. We thank T. R. Clandinin, A. Golden, R. J. Hill, L. S. Huang, G. D. Jongeward, W. Katz, P. Kayne, H. D. Lipshitz, J. Liu, A. Newman, R. Palmer and R. Sommer for comments on the manuscript, and G. Medina and Y. Hajdu-Cronin for technical assistance. We also thank R. J. Hill for providing syEx21 and syEx23 and S. Clark for providing let-23(n2020) prior to publication. Some of the strains used in this study were provided by the Caenorhabditis Genetics Center, which is funded by the NIH National Center for Research Resources (NCRR). This research was supported by the Howard Hughes Medical Institute and an NSF Presidential Young Investigator Award to P. W. S.; H. M. C. was an NSF predoctoral fellow; P. W. S. is an investigator of the HHMI.

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August 20, 2023
August 20, 2023