Novel heterochronic functions of the Caenorhabditis elegans period-related protein LIN-42

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.09.044 Byline: Jason M. Tennessen, Heather F. Gardner, Mandy L. Volk, Ann E. Rougvie Keywords: lin-42; Period; Heterochronic; Gonad morphogenesis; Circadian rhythm; Developmental timing Abstract: LIN-42, the Caenorhabditis elegans homolog of the Period (Per) family of circadian rhythm proteins, functions as a member of the heterochronic pathway, regulating temporal cell identities. We demonstrate that lin-42 acts broadly, timing developmental events in the gonad, vulva, and sex myoblasts, in addition to its well-established role in timing terminal differentiation of the hypodermis. In the vulva, sex myoblasts, and hypodermis, lin-42 activity prevents stage-specific cell division patterns from occurring too early. This general function of timing stage-appropriate cell division patterns is shared by the majority of heterochronic genes; their mutation temporally alters stage-specific division patterns. In contrast, lin-42 function in timing gonad morphogenesis is unique among the known heterochronic genes: inactivation of lin-42 causes the elongating gonad arms to reflex too early, a phenotype which implicates lin-42 in temporal regulation of cell migration. Three additional isoforms of lin-42 are identified that expand our view of the lin-42 locus and significantly extend the homology between LIN-42 and other PER family members. We show that, similar to PER proteins, LIN-42 has a dynamic expression pattern; its levels oscillate relative to the molts during postembryonic development. Transformation rescue studies indicate lin-42 is bipartite with respect to function. Intriguingly, the hallmark PAS domain is dispensable for LIN-42 function in transgenic animals. Author Affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, 6-160 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA Article History: Received 11 August 2005; Accepted 27 September 2005