TAKAGI Laboratory
<Major Research Areas>Biophysics, Cell physiology, Developmental biology

Dynamics in membrane
structure, cellular response and
embryogenic development

Research activity

【Molecular level】[Dynamics of structure and function of model membranes]

　　A cell enclosed by a cytomembrane is a common unit structure shared by all living organisms. In the µm-scaled vesicular space enclosed by the cytomembrane, there exist DNA molecules with genetic information and an enormous quantity of ongoing biochemical reactions to maintain living systems. This suggests that compartmentalization with the membrane boundary between the inner space and the outer environment is indispensable for life on the earth. We are studying cell-sized lipid vesicles as model membranes, focusing on time-dependent changes of membrane morphologies, lateral phase separations (raft domains) and biochemical reactions in an encapsulated volume.

【Cellular and body levels】[Dynamics of biological responses to external stress]

　　We are also interested in signal transduction at cellular level and whole organism. Cells are always exposed to various external stresses such as heat, ultraviolet, heavy metals etc. Stress signal transduction systems including ligand-receptor interactions and signal cascades such as MAP kinases (mitogen-activated protein kinase) play very important roles in responding to various stresses and maintaining cellular homeostasis. Therefore, problems in signal transduction are associated with cancer and developmental disorders. Malfunctions of these signaling cascades and responding mechanisms are reported causes of various diseases. We have been studying effects of ultraviolet and heavy metal ions on cell proliferation, differentiation and death. Moreover, as research at body level, we are now studying influence of external stress on embryogenic morphogenesis using zebrafish as a model organism.

Equipment

Atomic Force Microscopy, Confocal Laser Microscopy, Circular Dichroism, Flow Cytometry

The main research achievements in the past five years

1. T. Hamada, R. Sugimoto, T. Nagasaki, M. Takagi. Photochemical control of membrane raft organization. Soft Matter, 7, 220-224 (2011).
2. T. Hamada, R. Sugimoto, M. Vestergaard, T. Nagasaki, M. Takagi, Membrane disk and sphere: controllable mesoscopic structures for the capture and release of a targeted object.J. Am. Chem. Soc., 132, 10528-10532 (2010).
3. T. Hamada, M. Morita, Y. Kishimoto, Y. Komatsu, M. Vestergaard, and M. Takagi, Biomimetic microdroplet membrane interface: detection of the lateral localization of amyloid beta peptides, J. Phys. Chem. Lett., 1, 170-173 (2010).
4. M. Morita, M. Vestergaard, T. Hamada, M. Takagi Real-time observation of model-membrane dynamics induced by Alzheimer's amyloid beta" Biophys. Chem., 147, 81-86 (2010).
5. M. Vestergaard, T. Hamada, M. Morita, M. Takagi Cholesterol, lipids, amyloid beta, and Alzheimer's.Curr. Alzheimer Res., 7, 262-270 (2010).