TRPM2-mediated intracellular Zn2+ release triggers pancreatic β-cell death

Area of Science:

• Cell Biology
• Ion Channel Physiology
• Diabetes Research

Background:

• Reactive oxygen species (ROS) induce pancreatic beta-cell death, primarily through Transient Receptor Potential Melastatin 2 (TRPM2) channels.
• While TRPM2's role in calcium (Ca2+) influx is known, its ability to conduct zinc (Zn2+) and its physiological significance in cell death remain unclear.

Purpose of the Study:

• To investigate whether TRPM2-mediated Zn2+ permeability contributes to ROS-induced pancreatic beta-cell death.
• To elucidate the role of Zn2+ versus Ca2+ in TRPM2-associated apoptosis.

Main Methods:

• Utilized insulin-secreting INS1 cells, TRPM2-transfected HEK-293 cells, and pancreatic islets.
• Measured intracellular Ca2+ and Zn2+ levels following H2O2 exposure and TRPM2 activation.
• Assessed cell viability using Zn2+ chelation and evaluated apoptosis in TRPM2 knockout mice.

Main Results:

• H2O2 activation of TRPM2 channels increased cytosolic Ca2+ and Zn2+, leading to apoptotic cell death.
• Chelation of Zn2+ alone effectively prevented beta-cell death, indicating its critical role.
• TRPM2 channels in lysosomes facilitate intracellular Zn2+ release, potentiated by extracellular Ca2+.
• TRPM2 knockout mice were protected from streptozotocin-induced beta-cell death and hyperglycemia.

Conclusions:

• TRPM2-mediated Zn2+ release, potentiated by Ca2+, is a key mechanism in ROS-induced pancreatic beta-cell apoptosis.
• Zn2+ plays a more significant role than Ca2+ in TRPM2-associated beta-cell death.
• Targeting TRPM2-mediated Zn2+ release may offer a therapeutic strategy for diabetes.