The second edition of the Pollard and Earnshaw textbook "Cell Biology" award winning illustrations by Graham Johnson and new chapters by contributing author Jennifer Lippincott-Schwartz was published by Saunders in 2007.
Our laboratory uses a combination of
biochemistry, biophysics, microscopy and fission yeast genetics to
investigate the molecular basis of cellular motility and cytokinesis.
Actin-based cellular movements are essential for shaping organs during
embryonic development, defense against microorganisms and wiring the
nervous system. Movement of cells out of primary tumors is the chief
cause of mortality in cancer. Cytokinesis is essential for the
replication of all cells and is still one of the least understood
aspects of cell division.
Recent accomplishments include the discovery and
characterization of Arp2/3 complex, an assembly of two actin-related
proteins and seven novel subunits. We determined the crystal structure
of Arp2/3 complex and developed a method to visualize the growth
actin filaments in real time by fluorescence microscopy. These
breakthroughs have opened the way to understand how Arp2/3 complex
forms branches on the sides of actin filaments. We have also pioneered
the analysis of myosin-II function in fission yeast cytokinesis.
Thomas D. Pollard
Sterling Professor of MCDB
how cells control
the assembly and disassembly of actin filaments during cellular
have projects on the structure and function of actin, Arp2/3 complex,
of Arp2/3 complex (such as the Wiskott-Aldrich syndrome protein, WASp),
ADF/cofilin and capping protein.
include the discovery and characterization of Arp2/3 complex, an
assembly of two actin-related proteins and seven novel subunits. We
determined the crystal structure of Arp2/3 complex and developed a
method to visualize the growth of actin filaments in real time by
fluorescence microscopy. These breakthroughs opened the way to
understand how Arp2/3 complex forms branches on the sides of actin
filaments at the leading edge of motile cells and actin patches used by
fungi for endocytosis. We have also helped to establish the molecular
pathway of cytokinesis in fission yeast.
diagram of the 2.0 A crystal structure of the bovine Arp2/3 complex.
Ref: Robinson*, R.C., Turbedsky*, K., Kaiser, D.A., Higgs, H.N.,
Marchand, J.-B., Choe, S. and Pollard, T.D. (2001) Crystal structure of
Arp2/3 complex. Science 294:1679-1684. * co-first authors.
mechanism of cytokinesis:
Over the past
decade our lab adopted fission yeast
as our model system for studying cytokinesis. We used quantitative
fluorescence microscopy of fluorescent fusion
proteins to establish the temporal and spatial pathway of contractile
ring assembly and constriction and to measure the global and local
concentrations of 30 proteins
that participate in the process. We characterized the biochemical
several of the
cytokinesis proteins, including myosin-II, formins, profilin, capping
and cofilin. We combined this information in mathematical models that
allow us to
test our hypotheses about the cytokinesis pathway and to suggest
for new research.
pair of fluorescence micrographs showing the localization of
GFP-myosin-I in S. pombe. Ref: Lee, W.-L., Bezanilla, M. and Pollard,
T.D. (2000) Fission yeast myosin-I, Myo1p, stimulates actin assembly by
Arp2/3 complex and shares functions with WASp. J. Cell Biol.
See the paper in Cell where Tom Pollard explains why scientists should advocate for governmental support of basic research. [pdf]
Qian Chen, Ph.D., publishes: Actin filament severing by cofilin dismantles actin patches and produces mother filaments for new patches. [pdf]
Naomi Courtemanche, Ph.D., publishes: Tension modulates actin filament polymerization mediated by formin and profilin. [pdf]
Last Updated: August 29, 2013