C.elegans gene
epn-1 encodes a homolog of epsin, an endocytosis-related protein. Epsin homolog in D. melanogaster, Liquid facets (Lqf), has an important role in compound eye formation, suggesting an involvement of epsin in organogenesis. To investigate biological function of
epn-1, tissue-targeted RNAi of
epn-1 was performed, which demonstrated that the expression of
epn-1 in vulva is important for vulval development.Lqf is identified as a substrate of Fat facets (Faf), a de-ubiquitinating enzyme of D. melanogaster. The most homologous gene to Faf in the C.elegans genome is T24B8.7. Deletion mutants T24B8.7
(tm1245) and T248.7
(tm1052) exhibit protruding vulva.Expression of
epn-1 was inhibited by RNAi in the T24B8.7
(tm1245) genetic background to examine functional relation between
epn-1 and T24B8.7. As a result, protruding vulva was observed, although the phenotype was not observed on N2 applied
epn-1 RNAi. Transfection with a fosmid including whole T24B8.7 gene suppressed the phenotype of T24B8.7
(tm1245). This suggests that T24B8.7 and
epn-1 are functionally related in vulval development.Lqf and Faf promote Notch signaling in the eye formation of D. melanogaster. In vulval development of C.elegans, a vulval precursor cell (VPC) P6.p that adopts the 1deg fate presents a Notch ligand to P5.p and P7.p and introduces them into the 2deg fate. If T24B8.7 and
epn-1 promote Notch signaling in vulval development, downregulation of them are thought to reduce Notch signaling activation and to inhibit P5.p and P7.p to differentiate into the 2deg lineage. To test this hypothesis, expression of Pegl-17::GFP was compared in 4 genetic backgrounds; N2,
epn-1 (RNAi), T24B8.7
(tm1245), and T24B8.7
(tm1245)
epn-1 (RNAi). In all of them, Pegl-17::GFP was observed in the 2deg lineage vulval cells at the L4 stage, suggesting that P5.p and P7.p cells differentiated into the 2deg lineage. The expression after molting to adult, however, was observed in them except for T24B8.7
(tm1245)
epn-1 (RNAi) exhibiting proturuding vulva, which displayed either no or ectopic fluorescence. Thus, T24B8.7 and
epn-1 are thought to be involved in cell fusion or cell migration.