March 7, 2011
Interschool Lab, Room 750 CEPSR
Speaker: Rodrigo Fernandez-Gonzalez, Memorial Sloan-Kettering Institute
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.
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.