The voltage-dependent anion channel-1 modulates apoptotic cell death

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• The voltage-dependent anion channel (VDAC) is crucial in mitochondrial function and cell death.
• Hexokinase I (HK-I) binding to mitochondria, regulated by VDAC, influences cellular metabolism and survival.
• Inhibitors like dicyclohexylcarbodiimide (DCCD) and ruthenium red (RuR) affect VDAC function and cell death pathways.

Purpose of the Study:

• To investigate the role of VDAC, specifically VDAC1, in regulating apoptosis.
• To determine if VDAC directly controls the mitochondria-mediated apoptotic pathway.
• To elucidate the mechanism by which HK-I and RuR protect against apoptosis via VDAC.

Main Methods:

• Expression of native and mutated murine VDAC1 (E72Q-mVDAC1) in U-937 cells.
• Assessment of HK-I binding to mitochondria using mutated VDAC1.
• Measurement of VDAC1 conductance with HK-I and RuR.
• Induction and prevention of apoptosis in U-937 cells with native and mutated VDAC1.

Main Results:

• Mutation of Glutamate 72 to Glutamine (E72Q-mVDAC1) decreased HK-I binding to mitochondria by ~70% and abolished DCCD sensitivity.
• HK-I and RuR reduced native VDAC1 conductance but not E72Q-mVDAC1 conductance.
• Overexpression of native or E72Q-mVDAC1 induced significant apoptotic cell death.
• RuR or HK-I overexpression protected against apoptosis in cells with native VDAC1 but not E72Q-mVDAC1.

Conclusions:

• A single amino acid mutation in VDAC1 disrupts HK-I and RuR binding, preventing their anti-apoptotic effects.
• This suggests VDAC directly regulates the mitochondria-mediated apoptotic pathway.
• The protective mechanisms of RuR and HK-I are dependent on their interaction with VDAC.