Mitochondrial membrane potential acts as a retrograde signal to regulate cell cycle progression

Area of Science:

• Cell Biology
• Mitochondrial Biology
• Biochemistry

Background:

• Mitochondria are vital for cellular metabolism, and their dysfunction is linked to various diseases.
• Adaptive cellular responses to mitochondrial dysfunction involve inter-organelle communication.
• Mito-cellular signaling influences cell cycle progression, particularly in cells lacking mitochondrial DNA (ρ⁰ cells).

Purpose of the Study:

• To identify the initial trigger of the cell cycle delay in response to mitochondrial stress.
• To investigate the role of mitochondrial membrane potential (ΔΨm) in regulating cell cycle progression.
• To understand the relationship between oxidative stress and cell cycle delays in mitochondrial dysfunction.

Main Methods:

• Utilized mitochondrial DNA-deficient (ρ⁰) and control *Saccharomyces cerevisiae* cells.
• Experimentally manipulated mitochondrial membrane potential (ΔΨm).
• Assessed cell cycle progression and G1-to-S phase transition timing.
• Measured cellular oxidative stress levels.

Main Results:

• Decreased ΔΨm was identified as the primary signal initiating G1-to-S phase delay in response to mitochondrial stress.
• Experimental restoration of ΔΨm rescued timely cell cycle progression in ρ⁰ cells.
• Cellular oxidative stress levels did not correlate with the observed G1-to-S delay.

Conclusions:

• Mitochondrial membrane potential (ΔΨm) is a critical regulator of cell cycle progression, acting as an early signal of mitochondrial stress.
• Restored ΔΨm can normalize cell cycle timing, though G1/S transcription timing may remain affected.
• Findings suggest ΔΨm's role in cell cycle control has implications for diseases associated with mitochondrial dysfunction.