Cytokinesis, the physical division of one cell into two, is accomplished by a transient organelle called the contractile ring. The PI is focused on the molecular and biophysical mechanisms of contractile ring function. Ongoing work in the PI's laboratory has yielded an explanation of asymmetric (non-concentric) ring closure, which is seen throughout metazoa. To explain this asymmetry, a biomechanical feedback loop was proposed, among cytoskeletal filament alignment, filament sliding, and membrane curvature. An in silico model based on this feedback can recapitulate ring closure asymmetry, as well as the kinetics of closure initiation and duration in the C. elegans zygote, the primary animal model for this work. To expand and strengthen this model, the proposed work aims to define the molecular and physical mechanisms of each component of the feedback loop. Specifically, the conserved proteins that contribute to alignment of cytoskeletal filaments with each other and with the membrane will be defined. The existence of myosin in the form of bipolar minifilaments in the contractile ring will be defined. Last, the shape of the cell throughout cytokinesis will be described and correlated with local protein enrichment and organization. The proposal centers on the use of three dimensional live-cell (time-lapse) microscopy and quantitative image analysis. Several novel quantitative assays for contractile ring assembly, organization and function will be used. These include ways to measure F-actin alignment, kinetics and position of ring closure throughout cytokinesis, the number of molecules in macromolecular cortical complexes, and the three-dimensional shape of the cell during the course of division. The C. elegans zygote serves as an ideal model system for these studies due to its reproducible size, shape, and the kinetics of cell division events, the ease of thorough depletion of essential proteins, the ability to examine the first cell division attempted following protein depletion, and the availability of strains stably expressing fluorescent fusion proteins that serve as markers for various subcellular components and compartments. Importantly, cell cycle regulatory and structural proteins are conserved among C. elegans and mammals. The long-term goal of this work is to aid the development of anti-cancer chemotherapeutics that block cytokinesis. Targeting proteins that act specifically in the contractile ring should avoid the side effects on non-dividing cells of many popular drugs. In addition, because currently used anti-mitotics also have limited success against some tumor types, development of cytokinesis drugs will be a welcome expansion and diversification of our arsenal against cancers.

Public Health Relevance

For a fertilized egg to become a person, or for tissues like the skin and digestive tract to be replenished due to wear and tear, cells must multiply. We are working to understand how one cell physically splits into two copies of itself. Knowing how cells normally multiply is key to treating cancer cells that grow abnormally, so our work will inform the development of anti-cancer drugs that target the tumor and not other tissues.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM102390-05S1
Application #
9027120
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Gindhart, Joseph G
Project Start
2012-09-21
Project End
2017-08-31
Budget Start
2015-09-01
Budget End
2016-08-31
Support Year
5
Fiscal Year
2015
Total Cost
$73,104
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Descovich, Carlos Patino; Cortes, Daniel B; Ryan, Sean et al. (2018) Cross-linkers both drive and brake cytoskeletal remodeling and furrowing in cytokinesis. Mol Biol Cell 29:622-631
Fadero, Tanner C; Gerbich, Therese M; Rana, Kishan et al. (2018) LITE microscopy: Tilted light-sheet excitation of model organisms offers high resolution and low photobleaching. J Cell Biol 217:1869-1882
Lacroix, Benjamin; Letort, Gaëlle; Pitayu, Laras et al. (2018) Microtubule Dynamics Scale with Cell Size to Set Spindle Length and Assembly Timing. Dev Cell 45:496-511.e6
Rehain-Bell, Kathryn; Love, Andrew; Werner, Michael E et al. (2017) A Sterile 20 Family Kinase and Its Co-factor CCM-3 Regulate Contractile Ring Proteins on Germline Intercellular Bridges. Curr Biol 27:860-867
Ladouceur, A-M; Ranjan, Rajesh; Smith, Lydia et al. (2017) CENP-A and topoisomerase-II antagonistically affect chromosome length. J Cell Biol 216:2645-2655
Rehain, K; Green, R A; Bourdages, K G et al. (2017) Variations on a theme: Imaging cytokinetic and stable rings in situ using Caenorhabditis elegans. Methods Cell Biol 137:267-281
Dorn, Jonas F; Zhang, Li; Phi, Tan-Trao et al. (2016) A theoretical model of cytokinesis implicates feedback between membrane curvature and cytoskeletal organization in asymmetric cytokinetic furrowing. Mol Biol Cell 27:1286-99
Lacroix, Benjamin; Ryan, Joël; Dumont, Julien et al. (2016) Identification of microtubule growth deceleration and its regulation by conserved and novel proteins. Mol Biol Cell 27:1479-87
Rehain, Kathryn; Maddox, Amy Shaub (2015) Neuron migration: anillin protects leading edge actin. Curr Biol 25:R423-5
Sharif, Bedra; Fadero, Tanner; Maddox, Amy Shaub (2015) Anillin localization suggests distinct mechanisms of division plane specification in mouse oogenic meiosis I and II. Gene Expr Patterns 17:98-106

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