C. elegans homologs of insect clock proteins: A tale of many stories

Research Group of Functional Genomics and Proteomics, K.U. Leuven, Leuven, Belgium.
Annals of the New York Academy of Sciences (Impact Factor: 4.38). 03/2011; 1220(1):137-48. DOI: 10.1111/j.1749-6632.2010.05927.x
Source: PubMed


As a consequence of the Earth's axial rotation, organisms display daily recurring rhythms in behavior and biochemical properties, such as hormone titers. The neuronal system controlling such changes is best studied in the fruit fly Drosophila melanogaster. In the nematode worm Caenorhabditis elegans, most homologs of these genes function in the heterochronic pathway controlling the (timing of) developmental events. Recent data indicate that in the worm at least one of the genes involved in developmental timing is also active in circadian rhythm control, thereby opening up new perspectives on a central (neuronal) timer interfering with many processes. Also, new neuropeptidergic clock homologs have been identified in nematodes, supporting the idea of a broad range of clock-regulated targets. We will describe the current knowledge on homologous clock genes in C. elegans with a focus on the recently discovered pigment dispersing factor gene homologs. Similarities between developmental and daily timing are discussed.

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    • "The PDF-like neuropeptide pathway is highly conserved in nematodes, and PDF neuropeptides are also found in insects and crustaceans. In the latter, they were initially discovered and named pigment dispersing hormones (PDHs; Rao and Riehm, 1993; Janssen et al., 2009; Meelkop et al., 2011; Temmerman et al., 2011). Furthermore, all three C. elegans PDF receptors are closely related to insect orthologs, such as the D. melanogaster PDF receptor, and are distantly related to the vertebrate calcitonin GPCRs and vasoactive intestinal peptide (VIP) receptors (Janssen et al., 2008a). "
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    • "In addition, several clock genes were shown to play a role in development and most of the C. elegans clock homologs perform development-related activities (reviewed in [52]). It is quite surprising not to observe an obvious developmental or growth defect in pdf-1 mutants; moreover because the rise of pdf-1 levels before the L2 stage somehow supports a functional need at about that period during development. "
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