The goal of this research is to determine how the assembly dynamics and architecture of the actin cytoskeleton are controlled by formins and the mechanisms regulating their activities in vivo. We are studying this question in budding yeast, where the formins Bni1 and Bnr1 assemble actin 'cables'that play an essential role in polarized cell growth. Our lab recently discovered four novel modes of formin regulation mediated by the polarity factors Bud6, Bud14, Smy1, and Hof1. Remarkably, each of these proteins binds to the formin-homology FH2 domain of Bnr1, but has distinct effects on Bnr1 activity in vitro and distinct Bnr1-dependent mutant actin cable phenotypes in vivo. Further, we have identified novel in vivo ligands of Bud6 and Bud14 that function with them in regulating Bnr1-mediated actin cable assembly. The proposed research will define the cellular functions and mechanisms of these proteins, and how their combined effects coordinate the proper assembly of actin cables with a characteristic length, architecture, and dynamics that is tailored to their function. This work will provide a deeper understanding of the molecular activities and interactions that underlie cell polarity and morphogenesis. The project uses a multi-disciplinary approach, combining genetics, live-cell imaging, biochemistry, and novel multi-wavelength single molecule TIRF in vitro microscopy.
The Aims are to: (1) Elucidate the specific roles and mechanisms of Bud6 in regulating Bnr1- mediated actin cable assembly;(2) Test the hypothesis that Bud14 and Smy1 provide distinct modes of formin temporal regulation required for maintaining actin cable length, dynamics, and architecture;and (3) Determine how the functions of multiple FH2-binding regulators are coordinated in vitro and in vivo.

Public Health Relevance

The proper function of human tissues and organs depends on cells within those tissues maintaining their sense of direction (or polarity), dividing properly, ad maintaining their characteristic shapes and functions. Our work addresses a family of proteins (formins) that play vital roles in controlling cell shape, polarity, and division. By determining hw formins are regulated on a molecular and cellular level, we anticipate that this research will provide new insights into the underlying mechanisms of tumorigenesis, neurodegeneration, and developmental disorders such as limb deformities and hearing loss, which result from misregulated cell shape and division.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM083137-06
Application #
8449132
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Gindhart, Joseph G
Project Start
2008-03-01
Project End
2016-01-31
Budget Start
2013-02-01
Budget End
2014-01-31
Support Year
6
Fiscal Year
2013
Total Cost
$294,016
Indirect Cost
$110,666
Name
Brandeis University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
616845814
City
Waltham
State
MA
Country
United States
Zip Code
02454
Alioto, Salvatore L; Garabedian, Mikael V; Bellavance, Danielle R et al. (2016) Tropomyosin and Profilin Cooperate to Promote Formin-Mediated Actin Nucleation and Drive Yeast Actin Cable Assembly. Curr Biol 26:3230-3237
Eskin, Julian A; Rankova, Aneliya; Johnston, Adam B et al. (2016) Common formin-regulating sequences in Smy1 and Bud14 are required for the control of actin cable assembly in vivo. Mol Biol Cell 27:828-37
Henty-Ridilla, Jessica L; Rankova, Aneliya; Eskin, Julian A et al. (2016) Accelerated actin filament polymerization from microtubule plus ends. Science 352:1004-9
Mohapatra, Lishibanya; Goode, Bruce L; Jelenkovic, Predrag et al. (2016) Design Principles of Length Control of Cytoskeletal Structures. Annu Rev Biophys 45:85-116
Henty-Ridilla, Jessica L; Goode, Bruce L (2015) Global resource distribution: allocation of actin building blocks by profilin. Dev Cell 32:5-6
Mohapatra, Lishibanya; Goode, Bruce L; Kondev, Jane (2015) Antenna Mechanism of Length Control of Actin Cables. PLoS Comput Biol 11:e1004160
Bombardier, Jeffrey P; Eskin, Julian A; Jaiswal, Richa et al. (2015) Single-molecule visualization of a formin-capping protein 'decision complex' at the actin filament barbed end. Nat Commun 6:8707
Park, Eunyoung; Graziano, Brian R; Zheng, Wei et al. (2015) Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin Monomer Recruitment Motif. Structure 23:1492-9
Daou, Pascale; Hasan, Salma; Breitsprecher, Dennis et al. (2014) Essential and nonredundant roles for Diaphanous formins in cortical microtubule capture and directed cell migration. Mol Biol Cell 25:658-68
Graziano, Brian R; Yu, Hoi-Ying E; Alioto, Salvatore L et al. (2014) The F-BAR protein Hof1 tunes formin activity to sculpt actin cables during polarized growth. Mol Biol Cell 25:1730-43

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