Identification of an astacin matrix metalloprotease as target gene for Hydra foot activator peptides.

Peptides serve as important signaling molecules in development and differentiation in Hydra. Two peptides, Hym-346 and pedibin, have recently been identified to act as morphogenetic signals for foot differentiation. In screening for target genes for Hym-346 we have isolated an astacin matrix metalloprotease, termed foot activator responsive matrix metalloprotease (Farm1). Farm1 is normally expressed in epithelial cells of the gastric region and absent in apical and basal tissue. Incubation of polyps in peptides Hym-346/pedibin causes immediate downregulation of Farm1 expression. A structurally unrelated peptide, Hym-323, which also enhances foot formation in Hydra, also downregulates Farm1 expression. Treatment of polyps with the ectopic feet-inducing agent LiCl also resulted in decreased level of Farm1 transcripts. Thus metalloproteinase Farm1 is a transcriptional target of positional signals specifying foot differentiation and appears to play a potent role in basal patterning processes.