Ying Liu et al. (2004) East Coast Worm Meeting "The molecular analysis of ego-2."

Deborah Swenton, Ying Liu, Eleanor Maine, Dave Hansen

[East Coast Worm Meeting, 2004]

In the C. elegans germ line, the GLP-1/Notch signaling pathway regulates the switch from proliferation to meiosis. GLP-1 is activated in the distal germ line by a signal from the somatic distal tip cell, and distal germ cells are thereby induced to proliferate. In the absence of GLP-1 signaling, germ cells exit mitosis, enter meiosis, and differentiate. The ego screen was designed to identify components, regulators, and targets of the GLP-1-mediated signaling pathway in the germ line (Qiao et al., 1995). An ego-2 mutation, om33, was recovered as an enhancer of a weak glp-1 loss-of-function mutation in the germ line (Qiao et al. 1995). It also enhances a weak glp-1(lf) in the embryo (A. Smardon and E. Maine, unpublished data). ego-2(om33) was originally isolated on a chromosome with several other mutations; we have now recombined those mutations away, allowing us to examine the ego-2 phenotype in more detail. In a glp-1 (+) background, ego-2(om33) has a temperature-sensitive Spe (spermatogenesis defective) phenotype. Preliminary data suggest that ego-2(om33) does not suppress the glp-1(gf) phenotype in the germ line, suggesting that ego-2 may act upstream of or in parallel with glp-1. We are now doing genetic analysis to elucidate the relationship between ego-2 and other genes that promote germ line proliferation (e.g., the GLP-1 signaling pathway and atx-2 ) and meiotic entry (e.g., gld-1 and gld-2 ). Previously, ego-2 was mapped between dpy-24 and unc-101 on the right arm of chromosome I (Qiao et al. 1995). To clone the gene, we have now mapped it relative to other cloned marker genes and single nucleotide polymorphisms (SNPs). We have localized ego-2 to an ~137 kb region between SNPs in M04D5 (11334980 bp) and ZK1025 (11471740 bp), which includes 21 predicted genes. We are continuing the SNP mapping and using RNAi to deplete the gene products and test for enhancement of a weak glp-1(lf). Qiao et al. (1995) Genetics141, 551-569

Ying Liu et al. (2003) International Worm Meeting "An update on ego-1, ego-2, and ego-3"

Ying Liu, Deborah Swenton, Eleanor Maine, Tim Schedl, Valarie Vought, David Hansen, Elyse Connors, Xiang Yu

[International Worm Meeting, 2003]

GLP-1 is a Notch-type receptor that mediates a proliferative signal from the somatic distal tip cells to the germ line. In the absence of GLP-1 signaling, germ cells exit mitosis, enter meiosis, and differentiate. egomutations were recovered as recessive enhancers of a mild glp-1defect in the germ line (Qiao et al. 1995). These screens were designed to identify components, regulators, and targets of the GLP-1-mediated signaling pathway. We have previously characterized the mutant phenotype of these genes (Qiao et al. 1995; Smardon et al. 2000) and are now pursuing molecular studies.ego-1gene functions in germline development and RNA interference (RNAi) (Smardon et al. 2000). EGO-1 protein is a member of the RNA-dependent RNA polymerase (RdRP) family whose members are widely implicated in post-translational gene silencing phenomena. We are using several approaches to characterize the role of EGO-1 in germline development. Some of our results implicate EGO-1 in RNA metabolism, consistent with its classification as a RdRP family member. To better understand EGO-1 function, we are describing its expression pattern, screening for and analyzing molecular interactors, and testing candidate genetic interactors. ego-3gene function is required germline development and may be important for the onset of meiosis. Based on mapping with visible genetic markers and single nucleotide polymorphisms (SNPs), we have localized ego-3to a small region of chromosome V that is predicted to encode ten genes. However, we have not been able to determine which gene is ego-3based on existing mutations and RNAi. Therefore, ego-3may have unusual features that prevent it from being identified by the standard annotation programs, e.g., it may encode a regulatory RNA rather than a protein. We are now refining the SNP map position and testing for the presence of another gene in the region that might correspond to ego-3.Mutations in ego-2enhance glp-1(ts)in the embryo as well as the germ line. We have localized it to an ~130 kb region using SNP mapping. Once we better define the region, we will test candidate genes using RNAi.