title: C. elegans nucleostemin is required for larval growth and germline stem cell division.
abstract: The nucleolus has shown to be integral for many processes related to cell growth and proliferation. Stem cells in particular are likely to depend upon nucleolus-based processes to remain in a proliferative state. A highly conserved nucleolar factor named nucleostemin is proposed to be a critical link between nucleolar function and stem-cell-specific processes. Currently, it is unclear whether nucleostemin modulates proliferation by affecting ribosome biogenesis or by another nucleolus-based activity that is specific to stem cells and/or highly proliferating cells. Here, we investigate nucleostemin (nst-1) in the nematode C. elegans, which enables us to examine nst-1 function during both proliferation and differentiation in vivo. Like mammalian nucleostemin, the NST-1 protein is localized to the nucleolus and the nucleoplasm; however, its expression is found in both differentiated and proliferating cells. Global loss of C. elegans nucleostemin (nst-1) leads to a larval arrest phenotype due to a growth defect in the soma, while loss of nst-1 specifically in the germ line causes germline stem cells to undergo a cell cycle arrest. nst-1 mutants exhibit reduced levels of rRNAs, suggesting defects in ribosome biogenesis. However, NST-1 is generally not present in regions of the nucleolus where rRNA transcription and processing occurs, so this reduction is likely secondary to a different defect in ribosome biogenesis. Transgenic studies indicate that NST-1 requires its N-terminal domain for stable expression and both its G1 GTPase and intermediate domains for proper germ line function. Our data support a role for C. elegans nucleostemin in cell growth and proliferation by promoting ribosome biogenesis.
authors: Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States of America.
authors: Michelle M
authors: MM
authors: Kudron
authors: Valerie
authors: V
authors: Reinke
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D003598:Cytoskeletal Proteins; D005260:Female; D007814:Larva / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D051379:Mice; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C438244:CEP-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D003598:Cytoskeletal Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; C531563:nst-1 protein, C elegans