The Caenorhabditis elegans gene hlh-6 is expressed specifically in pharyngeal glands, one of five distinct pharyngeal cell types. Expression of hlh-6 is controlled by a discrete set of cis-regulatory elements, including a negative element called HRL1. Here we demonstrate that HRL1 is a functional binding site for LAG-1, the CSL transcriptional effector of Notch in C. elegans, and that regulation of hlh-6 by LAG-1 is direct. Regulation of hlh-6 by LAG-1 is strictly negative: removal of HRL1 or LAG-1 regulation results in ectopic expression of hlh-6, but does not affect expression in pharyngeal glands. Furthermore, direct regulation of hlh-6 expression does not appear to involve Notch signaling, contrary to the canonical mechanism by which CSL factors regulate target genes. We also identify an additional cis-regulatory element in the hlh-6 promoter that, together with previously identified elements, is sufficient to overcome repression by LAG-1 and activate hlh-6 expression in pharyngeal glands.
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http://dx.doi.org/10.1016/j.ydbio.2008.07.018 | DOI Listing |
MicroPubl Biol
June 2022
Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada.
Unsupervised Uniform Manifold Approximation and Projection (UMAP) plots of single cell sequencing data from synchronized larvae yield tissue-specific data clusters, some of which are plotted as elongated archipelagos. These archipelagos likely represent a single cell type. I show that the pharyngeal archipelagos express a myriad of asynchronous temporally regulated genes, which likely accounts for their elongated topology.
View Article and Find Full Text PDFMech Dev
June 2013
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
The Caenorhabditis elegans pharyngeal glands represent one of five cell types in the pharynx. We have previously shown that the bHLH transcription factor, HLH-6, is required for gland development and for expression of many, but not all, gland genes (Smit et al., 2008).
View Article and Find Full Text PDFGenetics
November 2011
Genes and Development Research Group, Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
The acquisition and maintenance of shape is critical for the normal function of most cells. Here we investigate the morphology of the pharyngeal glands of Caenorhabditis elegans. These unicellular glands have long cellular processes that extend discrete lengths through the pharyngeal musculature and terminate at ducts connected to the pharyngeal lumen.
View Article and Find Full Text PDFNucleic Acids Res
June 2009
Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Snail-type transcription factors (TFs) are found in numerous metazoan organisms and function in a plethora of cellular and developmental processes including mesoderm and neuronal development, apoptosis and cancer. So far, Snail-type TFs are exclusively known as transcriptional repressors. They repress gene expression by recruiting transcriptional co-repressors and/or by preventing DNA binding of activators from the basic helix-loop-helix (bHLH) family of TFs to CAGGTG E-box sequences.
View Article and Find Full Text PDFPLoS Genet
October 2008
Genes and Development Research Group, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
The Caenorhabditis elegans pharynx (or foregut) functions as a pump that draws in food (bacteria) from the environment. While the "organ identity factor" PHA-4 is critical for formation of the C. elegans pharynx as a whole, little is known about the specification of distinct cell types within the pharynx.
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