In vivo imaging probes with tunable chemical switches for monitoring cellular function and localization

 

In vivo imaging probes with tunable chemical switches for monitoring cellular function and localization

 

Date: 26^th May, 2026 (Tuesday)

Time: 5 - 6 pm (HKT)

 

Venue: Lecture Theatre P3, Chong Yuet Ming Physics Building

 

 

Immunology Frontier Research Center

Osaka University

 

Professor Kazuya Kikuchi received his Ph.D from University of Tokyo in 1994, and did his postdoctoral research with Prof. Roger Y. Tsien at UCSD and Prof. Donald Hilvert at the Scripps Research Institute. He returned Japan as a research associate at the university of Tokyo in 1997, and promoted to an associate professor in 2000. He took up a professorship at Osaka University in 2005. He was appointed as Professor at the Immunology Frontier Research Center, Osaka University (2009). Currently he is a distinguished professor at Osaka University. He is well known on his work in molecular imaging, chemical biology, and the development of fluorescent/MRI probes for visualizing biological processes. Recently he is focused both in in vivo imaging and single molecule cellular imaging.

 

In vivo fluorescence imaging is a powerful modality to monitor cell dynamics in biomedical studies. We developed a red-fluorescent small molecular probe to reversibly detect the acidic environments and to analyze the function of osteoclast proton pumps. Multicolor two-photon imaging using Red-pHocas in fluorescent reporter mice revealed that bone acidification synchronously occurred occasionally with proton pump accumulation onto the bone surfaces. Our imaging system will provide a useful approach for studying protein function involved in cell activity under intravital condition. Furthermore, a designed pH-activatable fluorescent probe has been used to measure localised pH levels in osteocytic lacunae in bone tissue. Conjugation of the moderate bone-binding drug risedronate to a pH-activatable fluorophore enables the probe to penetrate osteocytic lacunae cavities that are embedded deep within the bone matrix, enabling visualization of the bone mineralizing activities of acid producing osteocytes in real time.

 

Autophagy is a lysosomal protein degradation system for intracellular proteins. We developed a protein tag based on b-lactamase with its inhibitors (BLIs) as a new covalent ligand. The probe efficiently and selectively reacts with wild type b-lactamase that can be used as protein tag for fluorescence cell imaging. Lysosomal translocation of intracellular proteins upon autophagy induction was visualized by using our labeling system with a pH-activatable fluorophore.

 

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