In vertebrate, skeletal muscle development is regulated by basic helix-loop-helix transcription factors called MyoD family. In C. elegans, expression of body-wall muscle genes is mainly enhanced by MyoD homolog, CeMyoD encoded by
hlh-1. Null mutant animal of
hlh-1 is embryonic lethal, but slightly forms body-wall muscle. This means the presence of other factors that regulate body-wall muscle genes expression. The first intron of
hlh-1 has three enhancers, 1024, 1275 and 1330 sequences. These elements are highly conserved in the C. brigssae genome. The 1330 sequence is essential for the expression of the body-wall troponin C gene,
pat-10. These enhancers also exist in the upstream region of many body-wall muscle genes. The
hlh-1 enhancer binding proteins could regulate the body-wall muscle genes expression. To identify these enhancer-binding proteins, we performed a yeast one-hybrid screen using
hlh-1 enhancer sequences, 1024-1275-1330, as bait. As a result of screening from approximately 3x105 transformants, one positive clone was isolated. This was a homolog of mammalian TIS11 and was designated CeTIS11that included two CCCH-type Zn-finger domains on the central region. In yeast one-hybrid binding assay CeTIS11 bound to the 1275 sequence of
hlh-1. The 1024 sequence containing many E-boxes interacted with CeMyoD. In two-hybrid system we observed interaction between CeTIS11 and LIM-8, a CeMyoD binding protein (Ohuchi et al., in this meeting). Several fusion constructs of CeTIS11 gene with RFP or GFP were injected into worms and expression patterns were observed in these transgenic animals. CeTIS11 was expressed in body wall, pharyngeal and anal depressor muscles, intestine and some neurons of head and tail. CeTIS11 was detected in muscle filaments of body wall and pharyngeal muscles with immuno-staining by using anti-CeTIS11 antibody. CeTIS11 RNAi worms decreased motility at the rate of 87% and showed a weak Egl phenotype. These results suggest that CeTIS11 can involve in the control of body-wall muscle genes expression. We present the regulatory model of body-wall muscle genes expression by CeTIS11, CeMyoD and LIM-8.