title: A Lissencephaly-1 homologue is essential for mitotic progression in the planarian Schmidtea mediterranea.
abstract: BACKGROUND
  Planarians are renowned for their capacity to replace lost tissues from adult pluripotent stem cells (neoblasts). Here we report that Lissencephaly-1 (lis1), which has roles in cellular processes such as mitotic spindle apparatus orientation and in signal regulation required for stem cell self-renewal, is required for stem cell maintenance in the planarian Schmidtea mediterranea.
  
  
  RESULTS
  In planarians, lis1 is expressed in differentiated tissues and stem cells. lis1 RNAi leads to head regression, ventral curling, and death by lysis. By labeling the neoblasts and proliferating cells, we found lis1 knockdown animals show a dramatic increase in the number of mitotic cells, followed by depletion of the stem cell pool. Analysis of the mitotic spindles in dividing neoblasts revealed that defective spindle positioning is correlated with cells arrested at metaphase. In addition, we show that inhibiting a planarian homologue of nudE, predicted to encode a LIS-1 interacting protein, also leads to cell cycle progression defects.
  
  
  CONCLUSIONS
  Our results provide evidence for a conserved role of LIS1 and NUDE in regulating the function of the mitotic spindle apparatus in a representative Lophotrochozoan and that planarians will be useful organisms in which to investigate LIS1 regulation of signaling events underlying stem cell self-renewal.
authors.affiliation: Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA.
authors.forename: Martis W
authors.initials: MW
authors.lastname: Cowles
authors.forename: Amy
authors.initials: A
authors.lastname: Hubert
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Zayas
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000235:genetics*; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D008938:Mitosis / Q000235:genetics*; D058953:Neural Stem Cells / Q000166:cytology; D010932:Planarians / Q000166:cytology / Q000235:genetics*; D034622:RNA Interference; D008941:Spindle Apparatus / Q000235:genetics; D013234:Stem Cells / Q000166:cytology
chemical_list: D008869:Microtubule-Associated Proteins; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase