Characterization of STIP, a multi-domain nuclear protein, highly conserved in metazoans, and essential for embryogenesis in Caenorhabditis elegans.
We report here the identification and characterization of STIP, a multi-domain nuclear protein that contains a G-patch, a coiled-coil, and several short tryptophan-tryptophan repeats highly conserved in metazoan species. To analyze their functional role in vivo, we cloned nematode stip-1 genes and determined the spatiotemporal pattern of Caenorhabditis elegans STIP-1 protein. RNA analyses and Western blots revealed that stip-1 mRNA was produced via trans-splicing and translated as a 95-kDa protein. Using reporter constructs, we found STIP-1 to be expressed at all developmental stages and in many tissue/cell types including worm oocyte nuclei. We found that STIP-1 is targeted to the nucleus and forms large polymers with a rod-like shape when expressed in mammalian cells. Using deletion mutants, we mapped the regions of STIP-1 involved in nuclear import and polymer assembly. We further showed that knockdown of C. elegans stip-1 by RNA interference arrested development and resulted in morphologic abnormalities around the 16-cell stage followed by 100% lethality, suggesting its essential role in worm embryogenesis. Importantly, the embryonic lethal phenotype could be faithfully rescued with Drosophila and human genes via transgenic expression. Our data provide the first direct evidence that STIP have a conserved essential nuclear function across metazoans from worms to humans.
Ji
Qiongmei
Q
Laboratory of Biochemistry and Molecular Genetics, Lindsley F. Kimball Research Institute, New York Blood Center, 310 E 67th Street, New York, NY 10021, USA.
Huang
Cheng-Han
CH
Peng
Jianbin
J
Hashmi
Sarwar
S
Ye
Tianzhang
T
Chen
Ying
Y
D020816:Amino Acid Motifs; D000818:Animals; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D004331:Drosophila melanogaster; D019143:Evolution, Molecular; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D010802:Phylogeny; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012326:RNA Splicing; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D029742:Caenorhabditis elegans Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; C520029:stip-1 protein, C elegans