The pharyngeal muscles of Caenorhabditis elegans are single sarcomere muscles used for feeding. Like vertebrate cardiac and smooth muscles, C. elegans pharyngeal muscle does not express any of the known members of the MyoD family of myogenic factors. Assaying enhancer function in transgenic animals, we identified three subelements, designated A, B and C, that contribute to myo-2 enhancer activity. The B and C subelements have distinct cell type specificities. A duplication of C activates transcription in all pharyngeal cells, muscle and non-muscle.
Expression continues throughout embryonic and larval development.
Sequence requirements for myosin gene expression and regulation in Caenorhabditis elegans. We have used transformation-rescue and lacZ fusion assays to determine sequence requirements for regulated myosin gene expression during development. Multiple tissue-specific activation elements are present for all four genes. Each gene contains at least one additional tissue-specific regulatory element, as defined by the ability to enhance expression of a heterologous promoter in the appropriate muscle type. The general intron stimulation is apparently independent of intron sequence, indicating a mechanistic effect of splicing.