ELLI-1, a novel germline protein, modulates RNAi activity and P-granule accumulation in Caenorhabditis elegans

• Published in: PLoS genetics Vol. 13; no. 2; p. e1006611
• Main Authors: Andralojc, Karolina M, Campbell, Anne C, Kelly, Ashley L, Terrey, Markus, Tanner, Paige C, Gans, Ian M, Senter-Zapata, Michael J, Khokhar, Eraj S, Updike, Dustin L
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.02.2017; Public Library of Science (PLoS)
• Subjects: Alleles; Analysis; Animals; Animals, Genetically Modified; Base Sequence; Biology and life sciences; Caenorhabditis elegans; Caenorhabditis elegans - embryology; Caenorhabditis elegans - genetics; Caenorhabditis elegans - growth & development; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Cytoplasm; Cytoplasmic Granules - metabolism; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; Funding; Gene expression; Gene Expression Profiling - methods; Gene Expression Regulation, Developmental; Genetic aspects; Genomes; Germ Cells - metabolism; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Immunohistochemistry; In Situ Hybridization, Fluorescence; Laboratories; Microscopy, Fluorescence; Mutation; Nematodes; Protein binding; Proteins; Research and Analysis Methods; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; RNA polymerase; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; RNA-Dependent RNA Polymerase - genetics; RNA-Dependent RNA Polymerase - metabolism; Sperm; Transcription Factors, General - genetics; Transcription Factors, General - metabolism; Young adults; United States; Maine
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1006611

Germ cells contain non-membrane bound cytoplasmic organelles that help maintain germline integrity. In C. elegans they are called P granules; without them, the germline undergoes partial masculinization and aberrant differentiation. One key P-granule component is the Argonaute CSR-1, a small-RNA binding protein that antagonizes accumulation of sperm-specific transcripts in developing oocytes and fine-tunes expression of proteins critical to early embryogenesis. Loss of CSR-1 complex components results in a very specific, enlarged P-granule phenotype. In a forward screen to identify mutants with abnormal P granules, ten alleles were recovered with a csr-1 P-granule phenotype, eight of which contain mutations in known components of the CSR-1 complex (csr-1, ego-1, ekl-1, and drh-3). The remaining two alleles are in a novel gene now called elli-1 (enlarged germline granules). ELLI-1 is first expressed in primordial germ cells during mid-embryogenesis, and continues to be expressed in the adult germline. While ELLI-1 forms cytoplasmic aggregates, they occasionally dock, but do not co-localize with P granules. Instead, the majority of ELLI-1 aggregates accumulate in the shared germline cytoplasm. In elli-1 mutants, several genes that promote RNAi and P-granule accumulation are upregulated, and embryonic lethality, sterility, and RNAi resistance in a hypomorphic drh-3 allele is enhanced, suggesting that ELLI-1 functions with CSR-1 to modulate RNAi activity, P-granule accumulation, and post-transcriptional expression in the germline.