title: The C. elegans TIA-1/TIAR homolog TIAR-1 is required to induce germ cell apoptosis.
abstract: In Caenorhabditis elegans, physiological germ cell apoptosis eliminates more than half of the cells in the hermaphrodite gonad to support gamete quality and germline homeostasis by a still unidentified mechanism. External factors can also affect germ cell apoptosis. The BH3-only protein EGL-1 induces germ cell apoptosis when animals are exposed to pathogens or agents that produce DNA damage. DNA damage-induced apoptosis also requires the nematode p53 homolog CEP-1. Previously, we found that heat shock, oxidative, and osmotic stresses induce germ cell apoptosis through an EGL-1 and CEP-1 independent mechanism that requires the MAPKK pathway. However, we observed that starvation increases germ cell apoptosis by an unknown pathway. Searching for proteins that participate in stress-induced apoptosis, we found the RNA-binding protein TIAR-1 (a homolog of the mammalian TIA-1/TIAR family of proteins). Here, we show that TIAR-1 in C. elegans is required to induce apoptosis in the germline under several conditions. We also show that TIAR-1 acts downstream of CED-9 (a BCL2 homolog) to induce apoptosis under stress conditions, and apparently does not seem to regulate ced-4 or ced-3 mRNAs accumulation directly. TIAR-1 is expressed ubiquitously in the cytoplasm of the soma as well as the germline, where it sometimes associates with P granules. We show that animals lacking TIAR-1 expression are temperature sensitive sterile due to oogenesis and spermatogenesis defects. Our work shows that TIAR-1 is required for proper germline function and demonstrates that this protein is important to induce germ cell apoptosis under several conditions.
authors.affiliation: Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México.
authors.forename: Carlos Giovanni
authors.initials: CG
authors.lastname: Silva-García
authors.forename: Rosa
authors.initials: R
authors.lastname: Estela Navarro
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian; D005260:Female; D005298:Fertility; D005854:Germ Cells / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D017385:Sequence Homology
chemical_list: D029742:Caenorhabditis elegans Proteins; C087233:Ced-9 protein, C elegans; D019253:Proto-Oncogene Proteins c-bcl-2; D016601:RNA-Binding Proteins; C588003:TIAR-1 protein, C elegans
keywords: C. elegans; TIA-1; TIAR; TIAR-1; apoptosis; germ cells; germline; stress