Regulation of the mec-3 gene by the C.elegans homeoproteins UNC-86 and MEC-3.
The mec-3 gene encodes a homeodomain protein with LIM repeats that is required for the specification of touch cell fate in Caenorhabditis elegans. Previous experiments suggested that mec-3 expression requires the product of the unc-86 gene, a POU-type homeoprotein, and mec-3 itself. We have analyzed the control of mec-3 expression by identifying potential cis regulatory elements in the mec-3 gene (by conservation in a related nematode and by DNase I footprinting using unc-86 and mec-3 proteins) and testing their importance by transforming C.elegans with mec-3lacZ fusions in which these sites have been mutagenized in vitro. Both unc-86 and mec-3 proteins bind specifically to the promoter of the mec-3 gene, suggesting that both proteins may be directly involved in the regulation of the mec-3 gene. In addition, the footprint pattern with mec-3 protein is altered in the presence of unc-86 protein. In vivo transformation experiments reveal that some of the binding regions of the two proteins are needed for general positive control and maintenance of mec-3 expression while others have no detectable, unique function. Interestingly, the unc-86 gene appears to be required not only to initiate mec-3 expression but also to maintain it.
Xue
D
D
Department of Biological Sciences, Columbia University, New York, NY 10027.
Finney
M
M
Ruvkun
G
G
Chalfie
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D003001:Cloning, Molecular; D004247:DNA; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D060850:LIM-Homeodomain Proteins; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D001616:beta-Galactosidase / Q000235:genetics
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C072005:mec-3 protein, C elegans; D004247:DNA; D001616:beta-Galactosidase