Anna Marie Sokac, Ph.D.
Department of Biochemistry and Molecular Biology
Education and Awards
- B.S., Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, 1994
- Ph.D., Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin, 2001
- Postdoctoral, Princeton University, Princeton, New Jersey, 2008
- NIH, Ruth L. Kirschstein NRSA Postdoctoral Fellowship, 2007
Shaping cells, shaping embryos: Coordinated actin and membrane dynamics in flies and frogs
Cells take on specific shapes in order to perform specific jobs, and cells have the ability to rapidly change shape when normal physiology demands it. Cell shape relies on tight coupling between the plasma membrane and underlying actin cytoskeleton, and during cell shape change this coupling must be maintained even as membrane and actin are simultaneously remodeled.
The goal of my work is to understand how actin and membrane dynamics are coordinated during cell shape change: What molecular tethers link actin to membrane as each is remodeled? How do proteins and lipids of the plasma membrane influence actin dynamics? Conversely, how do actin dynamics influence membrane events, like exocytosis and endocytosis, as cells change shape?
We use early embryonic development as a model to study cell shape change. Specifically, we combine genetics, biochemistry and quantitative live imaging to ask how actin and membrane dynamics are coordinated during cycles of plasma membrane furrowing that accompany the first few hours of Drosophila morphogenesis. Our recent results suggest that actin differentially regulates endocytosis to achieve distinct cell shape changes, (i.e. furrow ingression versus regression). Ongoing projects are now aimed at 1) understanding the role of actin in regulating endocytosis, particularly at the step of vesicle scission; 2) defining the function of endocytosis at ingressing furrows, where new cell surface must be assembled; and 3) characterizing the activities of proteins poised to coordinate actin and endocytic dynamics at furrows, including Dynamin, the novel fly proteins Nullo, Serendipity-α and Spitting Image, and the BAR family protein Amphiphysin. To compliment our fly work, we are also extending these studies to cytokinesis furrows in cleavage-stage Xenopus embryos. These combined fly and frog efforts will then highlight general molecular mechanisms used to coordinate actin and membrane dynamics over a range of phyla, cell shape changes and morphogenetic events.
To view a movie of the furrow ingression/regression cycle, visit cellpressvideo: [video]
- Figard L, Sokac AM. Imaging cell shape change in living Drosophila embryos. J Vis Exp. 2011 Mar 30;(49). pii: 2503. [PubMed]
- LeBlanc-Straceski JM, Sokac A, Bement W, Sobrado P, Lemoine L. Developmental expression of Xenopus myosin 1d and identification of a myo1d tail homology that overlaps TH1. Dev Growth Differ. 2009 May;51(4):443-51. [PubMed]
- Sokac AM, Wieschaus E. Local actin-dependent endocytosis is zygotically controlled to initiate Drosophila cellularization. Dev Cell. 2008 May;14(5):775-86. [PubMed]
- Sokac AM, Wieschaus E. Zygotically controlled F-actin establishes cortical compartments to stabilize furrows during Drosophila cellularization. J Cell Sci. 2008 Jun 1;121(Pt 11):1815-24. [PubMed]
- Sokac AM, Bement WM. Kiss-and-coat and compartment mixing: coupling exocytosis to signal generation and local actin assembly. Mol Biol Cell. 2006 Apr;17(4):1495-502. [PubMed]
- Sokac AM, Schietroma C, Gundersen CB, Bement WM. Myosin-1c couples assembling actin to membranes to drive compensatory endocytosis. Dev Cell. 2006 Nov;11(5):629-40. [PubMed]
- Weber KL, Sokac AM, Berg JS, Cheney RE, Bement WM. A microtubule-binding myosin required for nuclear anchoring and spindle assembly. Nature. 2004 Sep 16;431(7006):325-9. [PubMed]
- Bement WM, Sokac AM, Mandato CA. Four-dimensional imaging of cytoskeletal dynamics in Xenopus oocytes and eggs. Differentiation. 2003 Dec;71(9-10):518-27. [PubMed]
- Sokac AM, Co C, Taunton J, Bement W. Cdc42-dependent actin polymerization during compensatory endocytosis in Xenopus eggs. Nat Cell Biol. 2003 Aug;5(8):727-32. [PubMed]
- Sokac AM, Bement WM. Regulation and expression of metazoan unconventional myosins. Int Rev Cytol. 2000;200:197-304. [PubMed]