A hierarchy of regulatory genes controls a larva-to-adult developmental switch in C. elegans.
The heterochronic genes lin-4, lin-14, lin-28, and lin-29 control the timing of specific postembryonic developmental events in C. elegans. The experiments described here examine how these four genes interact to control a particular stage-specific event of the lateral hypodermal cell lineages. This event, termed the "larva-to-adult switch" (L/A switch), involves several coordinate changes in the behavior of hypodermal cells at the fourth molt: cessation of cell division, formation of adult (instead of larval) cuticle, cell fusion, and cessation of the molting cycle. The phenotypes of multiply mutant strains suggest a model wherein the L/A switch is controlled by the stage-specific activity of a regulatory hierarchy: At early stages of wild-type development, lin-14 and lin-28 inhibit lin-29 and thus prevent switching. Later, lin-4 inhibits lin-14 and lin-28, allowing activation of lin-29, which in turn triggers the switch in the L4 stage. lin-29 may activate the L/A switch by regulating genes that control cell division, differentiation, and stage-specific gene expression in hypodermal cells.
Ambros
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Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D008675:Metamorphosis, Biological / Q000187:drug effects; D014157:Transcription Factors / Q000494:pharmacology
D014157:Transcription Factors