TGF-b signaling pathways are conserved in diverse animal species from the nematode to vertebrates. These pathways are known to regulate many aspects of cellular functions. The Sma pathway, one of the TGF-b signaling pathways in C.elegans, regulates body length and male tail pattern formation. In our previous work, we have reported that DBL-1 is the ligand of the Sma pathway. We are currently interested in the mechanism of body length regulation by DBL-1 and, in particular, in the regional specificity of DBL-1 signaling. A
dbl-1:: gfp reporter gene is expressed in neurons in the amphids and the ventral nerve cord (VNC). In an upstream sequence analysis of
dbl-1, it is suggested that a 5' upstream region required for the rescue of a
dbl-1 mutant is also required for the expression of
dbl-1 in the VNC neurons, but not in other nerons. While
dbl-1:: gfp is expressed in neurons, it has been reported that SMA-6, the type I receptor in the Sma pathway, is expressed in the pharyngeal muscle and the intestine. To determine which tissue the target of DBL-1 is in regulating body length, we are attempting to rescue a
sma-6 mutant using
sma-6 driven by various tissue-specific promoters. We will also analyze the
sma-6 5' sequence to uncover elements required for the expression of
sma-6 in the identified target tissue.