The assembly dynamics of the actin cytoskeleton is crucial for most morphogenetic processes that occur at both cellular and organism levels in eukaryotes. As a consequence, defects in actin dynamics and organization have been implicated in a variety of human diseases. However, our understanding of how actin is regulated in different physiological processes remains limited due to the extraordinary complexity and dynamic nature of the actin cytoskeletal system. The Arp2/3 complex is thought to be a major key element of actin filament nucleation and the formation of branched dendritic networks at the leading edge of motile cells. The role of Arp2/3 complex in these processes can only be understood through studies of the key molecular steps in the Arp2/3-mediated actin nucleation and branch formation. In this Program Project we aim at understanding the detailed structural mechanisms by which the Arp2/3 complex mediates the formation of actin branch junctions and the role of the Arp2/3 complex in vertebrate cell motility. We have assembled a highly synergistic team of Pis with complimentary expertise to achieve these goals through collaborative efforts. This sub-project (Volkmann lab) will contribute the development and application of a diverse set of computational tools for the reconstruction, analysis, and modeling of structural states and distribution patterns. Using these tools we will combine information from various data sources generated by all members of the Program Project to obtain (i) high-resolution models of the intermediates of the branch formation process and of the fully assembled branch itself;(ii) a dynamic, energetically self-consistent, structural model of the transition pathway from the inactive state of the Arp2/3 complex to the fully assembled branch in the dendritic network, and (iii) structural differences between different cell types and between wild-type cells and defective mutants by multi-dimensional and dynamical characterization of Arp2/3-complex and actin-filament distribution patterns in living eukaryotic cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
5P01GM066311-10
Application #
8464144
Study Section
Special Emphasis Panel (ZRG1-CB-D)
Project Start
Project End
Budget Start
2013-05-01
Budget End
2014-04-30
Support Year
10
Fiscal Year
2013
Total Cost
$425,382
Indirect Cost
$2,482
Name
Yale University
Department
Type
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Wang, Pei-Shan; Chou, Fu-Sheng; Ramachandran, Sreekumar et al. (2016) Crucial roles of the Arp2/3 complex during mammalian corticogenesis. Development 143:2741-52
Page, Christopher; Hanein, Dorit; Volkmann, Niels (2015) Accurate membrane tracing in three-dimensional reconstructions from electron cryotomography data. Ultramicroscopy 155:20-6
Jurgenson, Christopher T; Pollard, Thomas D (2015) Crystals of the Arp2/3 complex in two new space groups with structural information about actin-related protein 2 and potential WASP binding sites. Acta Crystallogr F Struct Biol Commun 71:1161-8
Li, Yongchao; Wang, Pei-Shan; Lucas, George et al. (2015) ARP2/3 complex is required for directional migration of neural stem cell-derived oligodendrocyte precursors in electric fields. Stem Cell Res Ther 6:41
Suraneni, Praveen; Fogelson, Ben; Rubinstein, Boris et al. (2015) A mechanism of leading-edge protrusion in the absence of Arp2/3 complex. Mol Biol Cell 26:901-12
Tee, Yee Han; Shemesh, Tom; Thiagarajan, Visalatchi et al. (2015) Cellular chirality arising from the self-organization of the actin cytoskeleton. Nat Cell Biol 17:445-57
Volkmann, Niels; Page, Christopher; Li, Rong et al. (2014) Three-dimensional reconstructions of actin filaments capped by Arp2/3 complex. Eur J Cell Biol 93:179-83
Volkmann, Niels (2014) The joys and perils of flexible fitting. Adv Exp Med Biol 805:137-55
Yi, Kexi; Rubinstein, Boris; Li, Rong (2013) Symmetry breaking and polarity establishment during mouse oocyte maturation. Philos Trans R Soc Lond B Biol Sci 368:20130002
Pollard, Thomas D (2013) No question about exciting questions in cell biology. PLoS Biol 11:e1001734

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