Atad3 is Essential for Mitochondrial Permeability Transition Pore Opening and Cardiac Ischemia Reperfusion Injury

Area of Science:

• Mitochondrial biology
• Cellular physiology
• Molecular mechanisms of cell death

Background:

• The mitochondrial permeability transition pore (mPTP) plays a critical role in cell death, but its molecular identity remains unknown.
• Numerous candidate proteins have been proposed, but none have been confirmed as essential components.

Purpose of the Study:

• To identify the essential molecular component(s) of the mitochondrial permeability transition pore (mPTP).
• To investigate the role of ATAD3 in mPTP function and associated cell death pathways.

Main Methods:

• Genetic deletion of Atad3 in cardiomyocytes and hepatocytes.
• Mitochondrial swelling and calcium retention capacity assays.
• Patch-clamp recordings of recombinant ATAD3a in liposomes.
• Ischemia/reperfusion (I/R) injury model in cardiac-specific Atad3 knockout mice.

Main Results:

• Genetic deletion of Atad3 in heart and liver cells abolished Ca2+-induced mPTP-dependent swelling.
• Mitochondria lacking ATAD3 exhibited unprecedented Ca2+ retention capacity.
• Recombinant ATAD3a displayed intrinsic channel activity in liposomes.
• Cardiac-specific Atad3 deletion significantly reduced infarct size in an I/R injury model.

Conclusions:

• ATAD3 is established as the first essential, pore-forming component of the mPTP.
• ATAD3 is critical for mPTP opening and mPTP-dependent necrosis.
• Targeting ATAD3 may offer a therapeutic strategy for ischemia/reperfusion injury.