[Novel Technology for Studying Insulin Secretion: Imaging and Quantitative Analysis by a Bioluminescence Method]

Area of Science:

• Cell Biology
• Biochemistry
• Imaging Technology

Background:

• Visualizing protein secretion from living cells is crucial for understanding cellular function and disease.
• Existing methods often lack the temporal resolution to capture dynamic secretion events.

Purpose of the Study:

• To develop a video-rate bioluminescence imaging method for visualizing protein secretion.
• To establish and characterize a cell line for studying synchronized insulin secretion.
• To investigate the role of cell-cell interactions in glucose-stimulated insulin secretion.

Main Methods:

• Fusion of target proteins (e.g., insulin) with Gaussia luciferase (GLase).
• Video-rate imaging (30-500 ms/frame) using an EM-CCD camera to detect luminescence signals.
• Development of a rat INS-1E cell line (iGL cells) stably expressing Insulin-GLase for 2D and 3D cultures.

Main Results:

• Synchronized, oscillatory insulin secretion observed in 3D-cultured iGL cells, mimicking pancreatic islets.
• Luminescence imaging revealed localized, synchronized insulin secretion in intercellular spaces in 2D cultures.
• Demonstrated that beta cell-cell interaction is essential for synchronized, glucose-stimulated insulin secretion.

Conclusions:

• The developed bioluminescence imaging method enables real-time visualization of protein secretion.
• iGL cells are valuable tools for studying oscillatory insulin secretion and evaluating anti-diabetic drugs.
• Cell-cell interactions and synchronization play a fundamental role in glucose-stimulated insulin secretion.