Gland-specific expression of C. elegans hlh-6 requires the combinatorial action of three distinct promoter elements

Dev Biol. 2007 Feb 1;302(1):295-308. doi: 10.1016/j.ydbio.2006.09.036. Epub 2006 Sep 26.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Caenorhabditis / genetics
  • Caenorhabditis elegans / genetics*
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / genetics*
  • Caenorhabditis elegans Proteins / metabolism
  • Gene Expression Regulation*
  • Organ Specificity
  • Pharynx / anatomy & histology
  • Pharynx / cytology
  • Pharynx / metabolism
  • Promoter Regions, Genetic*
  • Trans-Activators / metabolism


  • Basic Helix-Loop-Helix Transcription Factors
  • Caenorhabditis elegans Proteins
  • HLH-6 protein, C elegans
  • Pha-4 protein, C elegans
  • Trans-Activators