Translational control of maternal glp-1 mRNA establishes an asymmetry in the C. elegans embryo

235

211

Two components of the germ-line-specific P granules of the nematode Caenorhabditis elegans have been identified using polyclonal antibodies specific for each. Both components are putative germ-line RNA helicases (GLHs) that contain CCHC zinc fingers of the type found in the RNA-binding nucleocapsid proteins of retroviruses. The predicted GLH-1 protein has four CCHC fingers; GLH-2 has six. Both GLH proteins localize in the P granules at all stages of germ-line development. However, the two glh genes display different patterns of RNA and protein accumulation in the germ lines of hermaphrodites and males. Injection of antisense glh-1 or glh-2 RNA into wild-type worms causes some offspring to develop into sterile adults, suggesting that either or both genes are required for normal germ-line development. As these very similar glh genes physically map within several hundred kilobases of one another, it seems likely that they represent a fairly recent gene duplication event.Embryos of the free-living soil nematode Caenorhabditis elegans generate distinct founder cells via a series of asymmetric cell divisions. At each division, the germ-line daughter cell inherits distinctive non-membrane-bound particles, called P granules (1-3). P granules are partitioned to the primordial germ cell P 4 of the 16-to 24-cell embryo and become perinuclear. P granules persist around the nuclei of all germ cells, until gametogenesis, at which point they are excluded from mature sperm and become dispersed within the cytoplasm of mature oocytes in preparation for cytoplasmic localization in the embryo. Although the distribution pattern of nematode P granules has been well-studied, the identity and function of P-granule components have yet to be determined.Germ granules are found in many species (4, 5). The germ-line-specific polar granules of Drosophila melanogaster have been well-studied, with a number of different genes identified that are required for polar granule assembly and germ-cell formation, including vasa, staufen, valois, oskar, tudor, mago nashi, and germ-cell-less (6-15). With the exception of vasa, these genes encode novel proteins. Vasa, however, is a member of a family of proteins with recognizable motifs and predictable function. Vasa is an RNA helicase of the DEAD-box family (8, 9) whose ATP-dependent RNA helicase activity has been demonstrated in vitro (16). As polar granules contain RNA as well as protein (11,12,15,17), a germ-linespecific RNA helicase may function to bind and unwind RNAs necessary for germ-line development. Several potential vasa homologues have been cloned, including glh-1 (germ-line helicase 1) from Caenorhabditis, Xvh (Xenopus vasa homologue), mvh (mouse vasa homologue), and rvh (rat vasa homologue) (18)(19)(20)(21). glh-1 in C. elegans is unique among RNA helicase genes reported, including vasa, in that its predicted product contains four retroviral-like zinc fingers (18). We have identified a second C. elegans germ-line RNA helicase gene, glh-2, that also encodes zinc fingers. Immunolocali...

Section: Resultsmentioning

confidence: 99%

Multiple potential germ-line helicases are components of the germ-line-specific P granules of Caenorhabditis elegans

Gruidl

Smith

Kuznicki

et al. 1996

235

211

“…During Drosophila development 3Ј UTRs are important in the spatial and temporal regulation of nanos, bicoid, and hunchback mRNA (41-43). They also define localization sites of tra-2, fem-3, and glp-1 mRNAs of Caenorhabditis elegans for translational regulation (44). In macrophages, LPS induces the production of tumor necrosis factor ␣ (TNF␣); it also induces the production of tristetratprolin (TTP), a CCCH (Cys-Cys-Cys-His) class of zinc finger protein, which negatively regulates TNF␣ (45,46).…”

Section: Discussionmentioning

confidence: 99%

Lps^d/Ran of endotoxin-resistant C3H/HeJ mice is defective in mediating lipopolysaccharide endotoxin responses

Wong

Kang

Chen

et al. 1999

C3H͞HeJ inbred mice are defective in that they are highly resistant to endotoxic shock as compared with normal responder mice. Their B cells and macrophages do not respond significantly when exposed to lipopolysaccharide (LPS), whereas cells from the responder mice do. Using a functional assay, we previously isolated a cDNA, which encodes for Ran͞TC4 GTPase. We now show that this gene is mutated in

“…The following antisera͞markers were used: pharyngeal cells, mAb 3NB12 (9), hypodermal cell boundaries, jam-1::GFP fusion construct, jcIs1 (16), anti-APX-1 polyclonal serum (17), anti-GLP-1 affinity-purified polyclonal serum (kindly provided by S. Crittenden and J. Kimble; ref. 18), anti-APH-2 affinity-purified polyclonal serum (6). For quantification of embryo survival, individual homozygous mothers were allowed to lay 30-100 eggs, and the number of unhatched eggs was scored 15-25 h later.…”

Section: Analysis Of Embryosmentioning

confidence: 99%

APH-1 is a multipass membrane protein essential for the Notch signaling pathway in Caenorhabditis elegans embryos

Goutte

Tsunozaki

Hale

et al. 2002

381

297

Early embryonic cells in Caenorhabditis elegans embryos interact through a signaling pathway closely related to the Notch signaling pathway in Drosophila and vertebrates.Components of this pathway include a ligand, receptor, the presenilin proteins, and a novel protein, APH-2, that is related to the Nicastrin protein in humans. Here we identify the aph-1 gene as a new component of the Notch pathway in Caenorhabditis elegans. aph-1 is predicted to encode a novel, highly conserved multipass membrane protein. We show that aph-1 and the presenilin genes share a similar function in that they are both required for proper cell-surface localization of APH-2͞Nicastrin.