Gland-specific expression of C. elegans hlh-6 requires the combinatorial action of three distinct promoter elements.
The pharyngeal glands of Caenorhabditis elegans are one of five cell types in the pharynx. The transcription factor HLH-6 is required for gland development and function, and is specifically expressed in pharyngeal glands. As a first step to understanding specification of pharyngeal glands, we analyzed the promoter of hlh-6 to identify the elements required for gland-specific expression. Our experiments identified three distinct regulatory elements required for hlh-6 expression: a PHA-4-binding site and two new elements, HRL1 and HRL2 (for hlh-6 regulatory elements 1 and 2). The three elements employ a simple logic for producing cell-type-specific expression: the PHA-4 site restricts expression to the pharynx, HRL2 restricts expression in both a position and lineage-dependent manner, and HRL1 restricts expression to a subset of cell types. In isolation, these three elements have little or no enhancer activity but in combination they produce robust, gland-specific expression. These findings describe a combinatorial code for gland-specific expression and suggest that similar codes may be employed for specification of other pharyngeal cell types.
Raharjo
Indra
I
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada.
Gaudet
Jeb
J
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002107:Caenorhabditis / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D009928:Organ Specificity; D010614:Pharynx / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D029742:Caenorhabditis elegans Proteins; D015534:Trans-Activators; C517649:HLH-6 protein, C elegans; C113277:Pha-4 protein, C elegans