Understanding cell division ultimately requires a comprehensive view of the essential events that occur and the regulatory pathways that control them. While chromosome segregation is a defining feature of division, other compartments of the cell must also be carefully divided into daughter cells, and coordinated with progress through the division process. Membrane trafficking is shut down during metaphase, and resumes during late anaphase. The cell cycle signals regulating this transition are incompletely understood. Separase is a key protease that cleaves the glue holding sister chromatids together to allow chromosome separation at the onset of anaphase. Separase also has additional functions during late anaphase to promote the final events in cell division including the regulation of vesicle trafficking. This proposal describes research aimed at understanding how separase mediates vesicle trafficking events in collaboration with other closely related cell cycle regulators that have well characterized roles in chromosome segregation. Separase localizes to vesicles and is required for exocytosis. We will define the domain of separase required for vesicle localization and how vesicle localization is regulated. We will also investigate the mechanism by which separase promotes exocytosis, whether the protease activity is required, and seek new effectors that separase acts upon to trigger exocytosis. These studies will be performed using the genetically tractable C. elegans embryo supplemented by biochemical approaches with Xenopus laevis egg extracts. This work will provide new insight into how cells coordinate the essential process of chromosome segregation with other events that must occur for accurate division, which is relevant to understanding normal development and diseases such as infertility and cancer.

Public Health Relevance

Cells must coordinate multiple processes during division to ensure that each daughter cell inherits all the necessary constituents to maintain viability. This proposal aims to study a novel role we have uncovered for the central chromosome segregation regulatory pathway in membrane trafficking. The control of disparate processes by core cell cycle regulators enables cells to synchronize mitotic events to maintain the fidelity of cell division.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
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Melillo, Amanda A
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University of Tennessee Knoxville
Schools of Arts and Sciences
United States
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Melesse, Michael; Sloan, Dillon E; Benthal, Joseph T et al. (2018) Genetic Identification of Separase Regulators in Caenorhabditis elegans. G3 (Bethesda) 8:695-705
Melesse, Michael; Bembenek, Joshua N; Zhulin, Igor B (2018) Conservation of the separase regulatory domain. Biol Direct 13:7
Bai, Xiaofei; Bembenek, Joshua N (2018) Orchestrating early embryonic divisions. Mol Reprod Dev 85:86
Bai, Xiaofei; Bembenek, Joshua N (2017) Protease dead separase inhibits chromosome segregation and RAB-11 vesicle trafficking. Cell Cycle 16:1902-1917
Bembenek, Joshua N; Meshik, Xenia; Tsarouhas, Vasilios (2017) Meeting report - Cellular dynamics: membrane-cytoskeleton interface. J Cell Sci 130:2775-2779