The scaffolding protein anillin plays a crucial role during cytokinesis – the physical separation of daughter cells following chromosome segregation. Anillin binds filamentous F-actin, non-muscle myosin II and septins, and in cell culture models has been shown to restrict actomyosin contractility to the cleavage furrow. Whether anillin also serves this function during the incomplete cytokinesis that occurs in developing germ cells has remained unclear. Localization of anillin to several actin-rich structures in developing male germ cells also suggests potential roles for anillin outside of cytokinesis. In this study, I demonstrate that anillin is required for cytokinesis in dividing Drosophila spermatocytes. In addition, spermatid individualization is defective in anillin-depleted cells, although similarities to another cytokinesis mutant, four wheel drive, suggest this may be a secondary effect of failed cytokinesis. Anillin, septins and myosin II stably associate with the cleavage furrow in wild-type dividing spermatocytes. Anillin is necessary for recruitment of septins to the cleavage furrow, and for maintenance of Rho, F-actin and myosin II at the equator in late stages of cytokinesis. Membrane trafficking appears unaffected in anillin-depleted cells, although, unexpectedly, ectopic expression of one membrane trafficking marker, DE-cadherin-GFP, suppresses the cytokinesis defect. DE-cadherin-GFP recruits β-catenin (armadillo) and α-catenin to the cleavage furrow and stabilizes F-actin at the equator. Taken together, my results suggest that the anillin-septin and cadherin-catenin complexes can serve as alternative means to promote tight physical coupling of F-actin and myosin II to the cleavage furrow and successful completion of cytokinesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/27580 |
| Date | 09 June 2011 |
| Creators | Goldbach, Philip Daniel |
| Contributors | Brill, Julie |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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