Mistakes in chromosome segregation during meiosis or mitosis can lead to spontaneous abortion or to abnormalities such as Down syndrome. They have also been implicated in the processes leading to cancer and aging. Our laboratory has undertaken large-scale genetic screens using the organism Drosophila melanogaster to identify genes encoding proteins critical for ensuring proper chromosome segregation. In the first specific aim, we will investigate several novel components of the chromosomal kinetochores that were first found in our screens and that have been conserved among metazoans including humans. One area of focus in this aim is a multisubunit complex including the proteins ZW10, Rod, and Zwilch. This complex targets the molecular motor dynein to the kinetochore, and it is required in a currently unknown fashion for the operation of the spindle assembly checkpoint that regulates anaphase onset. We propose experiments to dissect the structure of this complex and to investigate its interactions with NudE, a dynein-associated protein whose role is currently not well understood. A second area of focus in this aim will explore the possibility that two new proteins identified in our genetic screens may together constitute a new subassembly at the kinetochore also needed for proper chromosome segregation. The second specific aim describes a new area of research for our laboratory. Mutations in greatwall, one of the Drosophila genes found in our screens, cause chromosome undercondensation because of delayed transit through prophase. The greatwall gene encodes a novel protein kinase with an unusual structure that is conserved in insects and vertebrates. We made antibody against the Xenopus Greatwall protein and used it to. deplete this kinase from oocyte extracts. To our surprise, Greatwall depletion prevented the extracts from entering or maintaining M phase. In the second specific aim, we will follow up these intriguing observations in order to understand Greatwall's role in mitotic progression. We propose experiments to define Greatwall's substrates as well as the upstream kinases involved in Greatwall activation during mitosis. Additional experiments will investigate Greatwall's possible developmental role in oocyte maturation and will search for other proteins with which this kinase associates. The proposed studies on Greatwall have the potential to offer unique mechanistic insights concerning mitotic entry in vertebrate cells.
| Filter, Joshua J; Williams, Byron C; Eto, Masumi et al. (2017) Unfair competition governs the interaction of pCPI-17 with myosin phosphatase (PP1-MYPT1). Elife 6: |
| Défachelles, Lénaïg; Raich, Natacha; Terracol, Régine et al. (2015) RZZ and Mad1 dynamics in Drosophila mitosis. Chromosome Res 23:333-42 |
| Williams, Byron C; Filter, Joshua J; Blake-Hodek, Kristina A et al. (2014) Greatwall-phosphorylated Endosulfine is both an inhibitor and a substrate of PP2A-B55 heterotrimers. Elife 3:e01695 |
| Wainman, Alan; Giansanti, Maria Grazia; Goldberg, Michael L et al. (2012) The Drosophila RZZ complex - roles in membrane trafficking and cytokinesis. J Cell Sci 125:4014-25 |
| Blake-Hodek, Kristina A; Williams, Byron C; Zhao, Yong et al. (2012) Determinants for activation of the atypical AGC kinase Greatwall during M phase entry. Mol Cell Biol 32:1337-53 |
| Kim, Min-Young; Bucciarelli, Elisabetta; Morton, Diane G et al. (2012) Bypassing the Greatwall-Endosulfine pathway: plasticity of a pivotal cell-cycle regulatory module in Drosophila melanogaster and Caenorhabditis elegans. Genetics 191:1181-97 |
| Yamamoto, Tomomi M; Blake-Hodek, Kristina; Williams, Byron C et al. (2011) Regulation of Greatwall kinase during Xenopus oocyte maturation. Mol Biol Cell 22:2157-64 |
| Goldberg, Michael L (2010) Greatwall kinase protects mitotic phosphosites from barbarian phosphatases. Proc Natl Acad Sci U S A 107:12409-10 |
| Peng, Aimin; Yamamoto, Tomomi M; Goldberg, Michael L et al. (2010) A novel role for greatwall kinase in recovery from DNA damage. Cell Cycle 9:4364-9 |
| Wainman, Alan; Creque, Jacklyn; Williams, Byron et al. (2009) Roles of the Drosophila NudE protein in kinetochore function and centrosome migration. J Cell Sci 122:1747-58 |
Showing the most recent 10 out of 22 publications
