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New Biological Frontiers Illuminated by Molecular Sensors and Actuators
Monday Speaker Abstracts
FRET Imaging in Organoids and Mice
Etsuko Kiyokawa
.
Kanazawa Medical University, Kahoku-gun, Japan.
Based on the principal of fluorescence resonance energy transfer (FRET), we are now able to
observe the protein activities in the living cells. Using MDCK organoid and the FRET biosensor
for small GTPase Rac1, we found Rac1activity is higher at the lateral than the apical plasma
membrane in the mature cyst. Elevating the Rac1 activity at the apical membrane induced the
luminal cell filling, indicating that the suppression of the Rac1 is required for maintenance of the
epithelial structures. The transgenic mice expressing the FRET biosensors were established and
recent development of two photon microscopy enables us to observe individual cells in the living
mice. We time-lapse-imaged the activities of extracellular signal-regulated kinase (ERK) and
protein kinase A (PKA) in neutrophils in inflamed intestinal tissue. ERK activity in neutrophils
rapidly increased during spreading on the endothelial cells and showed positive correlation with
the migration velocity on endothelial cells or in interstitial tissue. We are currently trying to
observe cancer cell migration in the liver. References1. Mizuno R., KamiokaY., Kabashima K.,
Imajo M., Sumiyama K., Nakasho E., Ito T., Hamazaki Y., Okuchi Y., Sakai Y., Kiyokawa E.,
Matsuda M.: In vivo imaging reveals PKA regulation of ERK activity during neutrophil
recruitment to inflamed intestines. J Exp Med: 211(6):1123-36, 2014.2. Yagi S., Matsuda M.,
Kiyokawa E.: Suppression of Rac1 activity at the apical membrane of MDCK cells is essential
for cyst structure maintenance. EMBO Rep: 13(3), 237-243, 2012