PAC proton-activated chloride channel contributes to acid-induced cell death in primary rat cortical neurons

Severe local acidosis causes tissue damage and pain, and is associated with many diseases, including cerebral and cardiac ischemia, cancer, infection, and inflammation. However, the molecular mechanisms of the cellular response to extracellular acidic environment are not fully understood. We recently identified a novel and evolutionarily conserved membrane protein, PAC (also known as PACC1 or TMEM206), encoding the proton-activated chloride (Cl⁻) channel, whose activity is widely observed in human cell lines. We demonstrated that genetic deletion of Pac abolished the proton-activated Cl⁻ currents in mouse neurons and also attenuated the acid-induced neuronal cell death and brain damage after ischemic stroke. Here, we show that the proton-activated Cl⁻ currents are also conserved in primary rat cortical neurons, with characteristics similar to those observed in human and mouse cells. Pac gene knockdown nearly abolished the proton-activated Cl⁻ currents in rat neurons and reduced the neuronal cell death triggered by acid treatment. These data further support the notion that activation of the PAC channel and subsequent Cl⁻ entry into neurons during acidosis play a pathogenic role in acidotoxicity and brain injury.