Suppressor genetics in C. elegans has identified key components of the LIN-12/Notch signaling pathway. Here, we describe a genetic and molecular characterization of the suppressor gene
sel-7. We show that reducing or eliminating
sel-7 activity suppresses the effects of constitutive
lin-12 activity, enhances the effects of partially reduced
lin-12 activity, and causes a synthetic Lin-12(0) phenotype when combined with a null mutation in the
sel-12 presenilin gene. These observations suggest that
sel-7 is a positive regulator of
lin-12 activity. We also show that SEL-7 encodes a novel nuclear protein. Through yeast two-hybrid screening, we identified an apparent interaction partner, K08E3.8, that also interacts with SEL-8, a known component of the nuclear complex that forms upon LIN-12 activation. Our data suggest potential roles for SEL-7 in the assembly or function of this nuclear complex.