Mechanisms of Cell Coordination in Epithelial Morphogenesis
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Date: 03-07-2011
Start Time:
11:00am
End Time: 12:00pm
Speaker: Rodrigo Fernandez-Gonzalez
From:
Memorial Sloan-Kettering Institute
Location: Interschool Lab, Room 750 CEPSR
ABSTRACT
Epithelial morphogenesis is driven by contractile actin-myosin networks that generate
mechanical force. Elongation of the body axis is a conserved morphogenetic process that occurs through
coordinated movements of cell intercalation in the Drosophila embryo. Actin and myosin II localize to
two distinct pools in intercalating cells, one associated with the contraction of cell-cell junctions that
drives intercalation, and another located at the medial-apical region. Using biophysical methods and
quantitative imaging we showed that mechanical tension is necessary and sufficient for myosin cortical
localization. Fluorescence recovery after photobleaching revealed that myosin is selectively stabilized
at cell junctions under increased tension. These results demonstrate that myosin both generates and is
regulated by tension, in a positive feedback loop that is predicted to increase the number of cells engaged
in contractile behavior. Simultaneously, we found that intercalating cells undergo anisotropic cell shape
fluctuations, with rapid cycles of apical contraction and expansion associated with the assembly and
disassembly of highly dynamic, medial actin-myosin structures. We have identified a novel role for
medial actin-myosin structures in wound healing during axis elongation. Upon wounding, actin and
myosin assemble dense medial meshworks associated with dramatic contraction and closure of the
wound. We found that the assembly of medial contractile structures in wound healing is specific to early
Drosophila embryos. We are currently investigating the cellular, molecular and mechanical elements that
regulate wound healing in early and late embryos to identify the mechanisms of efficient wound closure.
BIO
Dr. Rodrigo Fernandez-Gonzalez received his B. Sc. In Computer Engineering at Universidad
Autonoma de Madrid, Spain, and his Ph.D. in Bioengineering jointly from the University of California,
Berkeley and San Francisco in 2006. He is currently a postdoctoral researcher at the Memorial Sloan-
Kettering Institute. His research is focused on using his engineering skills to develop advanced
microscopy and image analysis tools to track cellular and molecular dynamics, and biophysical methods
to manipulate the mechanical forces experienced by cells in living Drosophila embryos. Using these tools
he has shown that mechanical forces can modulate the dynamics of cytoskeletal proteins in vivo, thus
regulating cell behavior. He is currently developing new methods to investigate the cellular, molecular
and mechanical aspects of wound closure in Drosophila embryos, which display an outstanding capacity
to heal wounds. He is the recipient of a 2010 Memorial Sloan-Kettering Cancer Center Postdoctoral
Research Award.