Cytokinesis is essential for development and survival of all organisms. Defects in cytokinesis cause aneuploidy and genomic instability, and thereby contribute to serious diseases such as cancer, neuronal disorders, and anemia. Thus, mechanistic study of cytokinesis is important not only for understanding the basic principles of a fundamental process but also for designing new strategies to treat human diseases. Cytokinesis in animal and fungal cells requires concerted functions of a contractile actomyosin ring (AMR), targeted vesicle fusion, and localized extracellular matrix (ECM) remodeling. Despite extensive studies of cytokinesis over a century, the basic architecture of the AMR remains unknown in any system. It is also unclear how myosin-II localization and filament assembly are regulated during cytokinesis. Increasing evidence suggests that ECM remodeling is critical for cytokinesis not only for yeast cells but also for animal cells. However, the underlying mechanisms remain poorly understood. We propose to address these key questions in cytokinesis using both budding yeast and mammalian cells as our experimental models.
In Aim 1, we will determine the AMR structure in budding yeast and then develop a quantitative model for it. This model will open new avenues to address broad questions in cytokinesis, e.g. those regarding the mechanism of ring constriction as well as those concerning the assembly, regulation, and function of the ring. We will also examine the AMR in mammalian cells to establish the degree of conservation in this core cytokinetic structure.
In Aim 2, we will test our hypothesis that IQGAP functions as a dual regulator of myosin localization and filament assembly during cytokinesis in both budding yeast and mammalian cells.
In Aim 3, we will test our hypothesis that the AMR-associated protein Inn1 interacts with SNAREs via its C2 domain to facilitate vesicle fusion at the division site, thereby increasing the local concentration of the cargo enzyme Chs2 (chitin synthase-II), which is subsequently activated by Cyk3 via its transglutaminase-like domain to promote septum formation (equivalent of ECM remodeling in animal cells) during cytokinesis. The proposed research is innovative, as diverse and cutting-edge technologies will be applied to generate new information and concepts regarding the core mechanisms of cytokinesis.

Public Health Relevance

Cytokinesis is a fundamental process essential for development and survival of all organisms. Failures in cytokinesis can cause genomic instability, and thereby contribute to serious diseases such as cancer, neuronal disorders, and anemia. Thus, mechanistic study of cytokinesis is important not only for understanding basic biology but also for designing new strategies to treat human diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM115420-02
Application #
9119026
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Gindhart, Joseph G
Project Start
2015-08-01
Project End
2019-07-31
Budget Start
2016-08-01
Budget End
2017-07-31
Support Year
2
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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Okada, Satoshi; Lee, Mid Eum; Bi, Erfei et al. (2017) Probing Cdc42 Polarization Dynamics in Budding Yeast Using a Biosensor. Methods Enzymol 589:171-190
Okada, S; Wloka, C; Bi, E (2017) Analysis of protein dynamics during cytokinesis in budding yeast. Methods Cell Biol 137:25-45
Yang, Li; Wang, Wei-Hua; Qiu, Wei-Lin et al. (2017) A single-cell transcriptomic analysis reveals precise pathways and regulatory mechanisms underlying hepatoblast differentiation. Hepatology 66:1387-1401
Bhavsar-Jog, Yogini P; Bi, Erfei (2017) Mechanics and regulation of cytokinesis in budding yeast. Semin Cell Dev Biol 66:107-118
Ong, K; Svitkina, T; Bi, E (2016) Visualization of in vivo septin ultrastructures by platinum replica electron microscopy. Methods Cell Biol 136:73-97