Functional analysis using RNAi was performed on eleven genes for metalloproteases of the M12A family in Caenorhabditis elegans and the interference of the C17G1.6 gene (
nas-37) was found to cause incomplete molting. The RNAi of the C26C6.3 gene (
nas-36) also caused a similar molting defect but not so severely as that of the
nas-37 gene. Both the genes encode an astacin-like metalloprotease with an epidermal growth factor (EGF)-like domain, a CUB domain, and a thrombospondin-1 domain, in this order. The promoter-driven green fluorescent protein (GFP) expression analysis suggested that they are expressed in hypodermal cells throughout the larval stages and in the vulva of adult animals. In the genetic background of
rde-1(
ne219), where RNAi does not work, the molting defect caused by the
nas-37 interference was observed when the transgenic wild-type
rde-1 gene was expressed under the control of the
dpy-7 promoter, known to be active in the hypodermal cells, but not under the control of the
myo-3 promoter, active in the muscular cells. Therefore these proteases are thought to be secreted by the hypodermal cells and to participate in shedding of old cuticles.