Intracellular acidification, which refers to a decrease in the pH levels within a cell, can have severe consequences on cellular processes and ultimately lead to cell death. Maintaining cellular homeostasis, including the appropriate pH balance, is crucial for normal cell functioning.
Let's explore how intracellular acidification can disrupt cellular processes and contribute to cell death:
Enzyme Dysfunction: Enzymes are essential proteins that catalyze biochemical reactions within cells. They have specific optimal pH ranges at which they function optimally. When intracellular acidification occurs, the pH deviates from the optimum, leading to enzyme dysfunction. Altered pH can denature enzymes, affecting their shape and reducing their catalytic activity. Consequently, important cellular reactions dependent on these enzymes, such as metabolism and DNA replication, can be impaired or halted, affecting overall cell function.
Protein Denaturation: Proteins, including structural and functional proteins, have specific three-dimensional structures that are critical for their proper functioning. Acidic conditions can disrupt the hydrogen bonding and electrostatic interactions that maintain protein structure, leading to protein denaturation. Denatured proteins lose their functionality and may aggregate, forming toxic protein aggregates that can disrupt cellular processes.
Ion Imbalance: Intracellular pH plays a crucial role in maintaining the balance of ions, including hydrogen ions (H⁺), potassium ions (K⁺), and calcium ions (Ca²⁺). Acidification can disrupt this balance, affecting the function of ion channels and transporters. For instance, increased intracellular acidity can cause the release of excess H⁺ ions into the cytoplasm, leading to acidosis. This disrupts the normal functioning of ion pumps and can result in abnormal cell signaling, impaired membrane potential, and altered ion gradients, ultimately affecting cellular processes such as neurotransmission and muscle contraction.
DNA Damage and Genomic Instability: Acidification can directly damage DNA molecules. The altered pH environment can cause chemical modifications to DNA bases, leading to mutations and genomic instability. DNA repair mechanisms may also be compromised due to disrupted enzyme activity, leading to the accumulation of DNA damage. Unrepaired or improperly repaired DNA can trigger cell cycle arrest or apoptosis (programmed cell death) as a protective response to prevent the propagation of damaged genetic material.
Oxidative Stress: Intracellular acidification can disrupt redox balance and contribute to oxidative stress. Acidic conditions can increase the production of reactive oxygen species (ROS) within cells. ROS are highly reactive molecules that can damage cellular components, including lipids, proteins, and DNA. Accumulated oxidative damage can impair cellular processes, compromise mitochondrial function, and trigger cell death pathways.
Disrupted Cellular Communication: Acidification can affect intercellular communication processes, such as the function of gap junctions, which are channels between neighboring cells. Altered pH can modify the electrical and chemical gradients across these channels, affecting the exchange of ions, metabolites, and signaling molecules between cells. Disrupted communication between cells can impair coordinated cellular responses and contribute to cellular dysfunction and death.
These disruption caused by intracellular acidification can induce cellular dysfunction, trigger apoptosis or necrosis pathways, and ultimately result in cell death. The importance of understanding the dangers of intracellular acidification and of monitoring it with reliable tools such as the SPAchip® is evident nowadays.