Stable bioreactor control reveals acidic pH-driven metabolic reprogramming and mitochondrial dysfunction in human...

Area of Science:

• Cell Biology
• Metabolic Research
• Mitochondrial Biology

Background:

• Cellular pH regulation is crucial for physiological function.
• The molecular effects of acidic environments on cells are not fully understood.

Purpose of the Study:

• To investigate the molecular consequences of acidic pH on human cells.
• To explore the role of NAD+ metabolism in mediating the effects of acidic environments.

Main Methods:

• Utilized a gas-only bioreactor for precise control of pH, oxygen, and temperature.
• Performed integrated multi-omics analyses to assess cellular responses.
• Investigated the impact of NAD+ restoration via NMN supplementation and PARP1 inhibition.

Main Results:

• Acidic pH induced a glycolytic shift, suppressed proliferation, and caused mitochondrial dysfunction.
• Acidic conditions increased reactive oxygen species (ROS), activated inflammatory pathways, and led to mitochondrial DNA mutation enrichment.
• Acidic pH depleted intracellular NAD+, partly due to PARP1 activation.
• NMN supplementation and PARP1 inhibition partially rescued proliferation and reversed mitochondrial DNA heteroplasmy.

Conclusions:

• pH homeostasis is critical for coordinating cellular metabolism, redox balance, and immune signaling.
• NAD+ metabolism acts as a mechanistic link between acidic microenvironments, mitochondrial instability, and immune-metabolic changes.