Critical transitions in pancreatic islets.

Area of Science:

• Cellular biology
• Biophysics
• Physiology

Background:

• Pancreatic beta cells regulate insulin secretion through collective calcium (Ca2+) signaling.
• The transition of Ca2+ signaling from uncorrelated to correlated states resembles a phase transition but its order is not well understood.

Purpose of the Study:

• To investigate the nature and order of the phase transition in collective calcium signaling within pancreatic beta cells.
• To understand the role of islets as tipping elements in pancreatic function and insulin release.

Main Methods:

• Utilized confocal microscopy to record collective Ca2+ activation in intact pancreatic islets.
• Applied varying glucose concentrations in both increasing and decreasing patterns.
• Developed a network model of beta cells incorporating link selection and coordination.

Main Results:

• Observed a sharp transition in Ca2+ signaling from uncorrelated to correlated states as glucose concentration changed.
• Demonstrated hysteresis in the coordinated Ca2+ response, indicating a first-order phase transition.
• The network model successfully replicated the observed hysteresis loop and critical transition dynamics.

Conclusions:

• Collective calcium signaling in pancreatic beta cells undergoes a critical, first-order phase transition.
• Islets function as tipping elements, with their interconnectedness driving abrupt insulin release dynamics.
• Understanding these transitions is key to comprehending pancreatic islet function in glucose homeostasis.