GO:0071468 cellular response to acidic pH: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0071468 cellular response to acidic pH describes how a cell changes its state or activity when exposed to a pH below 7, including movement, secretion, enzyme production, and gene expression.
• Acidic pH is a physiological signal in tumors, immune phagosomes, the gut, and the nervous system, making this process central to cancer biology, host-microbe interactions, and sensory physiology.
• Cells respond to acidic pH through proton sensing, intracellular pH regulation, metabolic rewiring, autophagy, and large-scale transcriptomic reprogramming.
• Key genes and proteins include proton-sensing receptors (GPR4, GPR65, GPR68), ion transporters (NHE1/SLC9A1, V-ATPase), carbonic anhydrases (CA9, CA12), and acid-stress regulators such as RstAB in bacteria.
• Acidic pH reduces agonist efficacy at some neurotransmitter receptors, for example glycine receptors, linking pH to synaptic signaling.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to test whether candidate pH-response genes are causally involved in disease and adaptation.
Description
GO:0071468 cellular response to acidic pH is a biological process defined as any process that results in a change in state or activity of a cell as a result of a pH stimulus with pH less than 7. This term captures the full range of cellular reactions to acidity, including changes in movement, secretion, enzyme production, and gene expression. Acidic pH is not merely a stress condition; it is a physiological signal encountered in tumor microenvironments, macrophage phagosomes, the gastrointestinal tract, and neural tissue. Understanding this response is therefore important for cancer research, immunology, microbiology, and neuroscience. Transcriptomic studies in Sinorhizobium meliloti have shown that a shift to acidic pH triggers a time-dependent reprogramming of gene expression, demonstrating that acidity is a potent global regulator of cell state. Similarly, Lactobacillus plantarum strains with probiotic potential mount acid resistance and pH-induced stress responses that determine survival in the gut. In mammalian cells, intracellular pH responses to anoxia in hippocampal CA1 neurons show that pH regulation is tightly coupled to metabolic and excitability state. Autophagy is also induced on acid, indicating that acidic pH can directly engage degradative and survival pathways. Together, these findings establish cellular response to acidic pH as a central node connecting environmental chemistry to cell fate, immune function, and disease progression.
cellular response to acidic pH At A Glance
| GO ID | GO:0071468 |
|---|---|
| GO term | cellular response to acidic pH |
| Ontology | biological_process |
| Synonym | cellular response to acidity |
| Definition | Any process that results in a change in state or activity of a cell as a result of a pH stimulus with pH < 7. |
| Major function | Cellular adaptation and signaling in response to acidic environments, including changes in gene expression, secretion, movement, and metabolism. |
| Stimulus | pH less than 7 (acidic pH) |
| Related processes | Autophagy, intracellular pH regulation, acid resistance, proton sensing, metabolic reprogramming. |
| Example organisms | Mammals, bacteria, and other organisms exposed to acidic niches. |
What Is GO:0071468?
In our own words, GO:0071468 cellular response to acidic pH refers to the collection of cellular processes triggered when a cell senses and reacts to an environment or compartment with a pH below 7. The response can include changes in cell movement, secretion, enzyme production, gene expression, and other activities. It is a biological process term, and its synonym is cellular response to acidity. The response is not a single pathway but a coordinated program that may involve proton sensing, ion transport, metabolic adaptation, transcriptional changes, and stress survival mechanisms.
Why Is cellular response to acidic pH Important in Cell Biology?
Cellular response to acidic pH is important because acidic microenvironments are common in human disease and normal physiology, and the ability of cells to sense and adapt to low pH determines survival, immune function, and therapeutic response. In cancer, the acidic tumor microenvironment drives invasion, metabolic adaptation, and immune evasion, making this process a target for drug development. In infectious disease, pathogens such as adherent-invasive Escherichia coli use two-component systems like RstAB to sense acidic conditions within macrophages and promote pathogenicity. In neuroscience, acidic pH modulates receptor function, as shown by reduced agonist efficacy at glycine receptors. In the gut, probiotic Lactobacillus strains rely on acid resistance for survival and function. Therefore, studying GO:0071468 provides mechanistic insight into cancer, infection, neurobiology, and microbiome biology.
• Acidic tumor microenvironments are a hallmark of solid tumors and drive cancer progression and therapy resistance.
• Pathogens such as adherent-invasive E. coli use acid-sensing systems to survive and cause disease within macrophages.
• Acid-sensing ion channels and proton-sensing G protein-coupled receptors mediate pain, inflammation, and immune responses.
• Intracellular pH regulation is critical for neuronal function and survival during metabolic stress such as anoxia.
• Autophagy is induced by acidic pH, linking this response to protein degradation and cell survival.
• Probiotic bacteria require acid resistance to survive gastric transit and exert beneficial effects.
• Transcriptomic reprogramming under acidic pH affects hundreds of genes, making it a global regulatory response.
• Acidic pH can reduce neurotransmitter receptor efficacy, influencing synaptic transmission.
• Understanding acid response mechanisms can guide development of pH-targeted therapeutics.
• CRISPR-based models enable causal testing of acid-response genes in disease contexts.
What Happens During cellular response to acidic pH?
Sensing acidic pH
In simple terms: The cell first notices that the environment has become acidic.
Cells detect acidic pH through proton-sensitive proteins, ion channels, and two-component systems. In bacteria such as adherent-invasive Escherichia coli, the RstAB two-component system senses acidic conditions within macrophages and promotes pathogenicity. In mammals, proton-sensing G protein-coupled receptors and acid-sensing ion channels detect extracellular acidity and initiate signaling. Intracellular pH sensors also monitor cytosolic pH changes, as shown in hippocampal CA1 neurons during anoxia.
Intracellular pH regulation
In simple terms: The cell tries to keep its internal pH stable even when the outside is acidic.
Cells regulate intracellular pH through ion transporters and exchangers. The Na+/H+ exchanger NHE1 (SLC9A1) and V-ATPases are key players that extrude protons or sequester them into organelles. In hippocampal CA1 neurons, intracellular pH responses to anoxia are actively managed, indicating tight regulation. Carbonic anhydrases such as CA9 and CA12 also contribute to pH homeostasis in tumors.
Transcriptional and metabolic reprogramming
In simple terms: The cell changes which genes are turned on and how it uses energy.
Acidic pH triggers large-scale changes in gene expression. In Sinorhizobium meliloti, a shift to acidic pH causes a time-course transcriptomic response affecting many genes. In Lactobacillus plantarum, acid resistance and pH-induced stress responses involve coordinated gene expression changes. Metabolic rewiring, including altered glycolysis and autophagy, supports survival under acidic conditions.
Autophagy and stress survival
In simple terms: The cell recycles its own components to survive acid stress.
Acidic pH can induce autophagy, a degradative process that recycles cellular components and promotes survival. This response is linked to metabolic stress and may protect cells in acidic tumor microenvironments. Autophagy on acid represents a direct functional link between pH and cell survival machinery.
Modulation of receptor and synaptic function
In simple terms: Acidity can change how nerve cells respond to signals.
Acidic pH reduces agonist efficacy and responses to synaptic-like glycine applications in zebrafish alpha1 and rat alpha1beta recombinant glycine receptors. This demonstrates that acidic pH can directly modulate neurotransmitter receptor function, affecting synaptic signaling. Such pH sensitivity may contribute to neuronal dysfunction under acidic conditions.
Key Genes Involved in GO:0071468 cellular response to acidic pH
The following genes and proteins are experimentally implicated in cellular response to acidic pH across cancer, infection, neuroscience, and microbial systems.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC9A1 (NHE1) | Na+/H+ exchanger that regulates intracellular pH | Target for cancer and pH regulation studies |
| CA9 | Carbonic anhydrase that buffers pH in tumors | Hypoxia and acidic tumor microenvironment marker |
| CA12 | Carbonic anhydrase involved in pH homeostasis | Cancer and pH regulation research |
| GPR4 | Proton-sensing G protein-coupled receptor | Acid sensing in inflammation and cancer |
| GPR65 | Proton-sensing receptor in immune cells | Immune response to acidic pH |
| GPR68 | Proton-sensing receptor in neurons and other cells | Acid sensing in physiology |
| ASIC1 | Acid-sensing ion channel | Pain and neuronal acid detection |
| ASIC2 | Acid-sensing ion channel | Neuronal acid sensing |
| ASIC3 | Acid-sensing ion channel | Pain and inflammation |
| RstA | Response regulator of RstAB two-component system | Bacterial acid response and pathogenicity |
| RstB | Sensor kinase of RstAB two-component system | Acid sensing in adherent-invasive E. coli |
| GLRA1 | Glycine receptor alpha1 subunit | pH modulation of synaptic receptors |
| GLRB | Glycine receptor beta subunit | pH modulation of synaptic receptors |
| V-ATPase subunits | Proton pumps that acidify organelles | Intracellular pH and autophagy regulation |
| ATG proteins | Autophagy machinery | Acid-induced autophagy |
| Lactobacillus acid resistance genes | Acid resistance and stress response | Probiotic survival in gut |
| Sinorhizobium meliloti acid-responsive genes | Transcriptomic response to acidic pH | Global acid response model |
How Is cellular response to acidic pH Regulated?
Cellular response to acidic pH is regulated at multiple levels. Proton-sensing receptors and ion channels initiate signaling upon acid exposure. Two-component systems such as RstAB in bacteria sense acidic conditions and regulate virulence gene expression. Intracellular pH is maintained by ion transporters including NHE1 and V-ATPases, which are themselves regulated by metabolic and signaling inputs. Autophagy is induced by acidic pH and is controlled by core autophagy proteins. Transcriptional reprogramming under acidic pH involves coordinated changes in gene expression over time, as shown in Sinorhizobium meliloti and Lactobacillus plantarum. In neurons, pH regulation is coupled to metabolic state and excitability, as demonstrated in hippocampal CA1 neurons during anoxia. These layers of regulation ensure that cells can adapt to acidic stress while maintaining essential functions.
cellular response to acidic pH and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CA9 | Cancer, tumor acidity | Knockout and overexpression in cancer cell lines |
| SLC9A1 | Cancer, pH regulation | Point mutation and knockout models |
| RstA/RstB | Bacterial infection, macrophage survival | Knockout in E. coli |
| GLRA1 | Neurological disorders, synaptic signaling | Point mutation in glycine receptors |
| ATG genes | Cancer, autophagy | Knockout and knock-in models |
Cancer and the acidic tumor microenvironment
The acidic tumor microenvironment is a driver of cancer progression, promoting invasion, metastasis, and immune evasion. Tumor cells adapt to acidic pH through upregulation of carbonic anhydrases, ion transporters, and metabolic reprogramming. Autophagy induced by acidic pH supports cancer cell survival under stress. Targeting pH-regulatory proteins such as CA9 and NHE1 is an active area of therapeutic development.
Infectious disease and bacterial acid response
Adherent-invasive Escherichia coli uses the RstAB two-component system to sense acidic conditions within macrophages and promote pathogenicity. This illustrates how bacterial pathogens exploit acidic niches to survive and cause disease. Understanding acid-sensing systems in bacteria may inform new antimicrobial strategies.
Neuroscience and synaptic function
Acidic pH modulates neurotransmitter receptor function, as shown by reduced agonist efficacy at glycine receptors. Intracellular pH regulation in hippocampal CA1 neurons is critical during anoxia, linking pH to neuronal survival. Acid-sensing ion channels and proton-sensing receptors mediate pain and other neuronal responses.
Gut microbiome and probiotic function
Lactobacillus plantarum strains with probiotic potential rely on acid resistance and pH-induced stress responses for survival in the gastrointestinal tract. These mechanisms are important for probiotic efficacy and gut health. Studying acid response in commensal bacteria can reveal targets for microbiome modulation.
From cellular response to acidic pH-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of CA9 affect tumor growth under acidic pH? | CRISPR knockout in cancer cell lines |
| Does a point mutation in SLC9A1 alter pH regulation? | Point-mutation knock-in |
| Does RstAB deletion reduce E. coli survival in macrophages? | Knockout in adherent-invasive E. coli |
| Does overexpression of proton-sensing receptors enhance acid response? | Overexpression cell models |
| Does tagging of ATG proteins affect autophagy under acidic pH? | Tagged knock-in |
| Does acid-responsive gene expression change in Lactobacillus? | Knockout and overexpression in Lactobacillus |
How to Study the cellular response to acidic pH Process
| Method | What It Measures | Typical Application |
|---|---|---|
| RNA-seq | Global gene expression changes | Transcriptomic response to acidic pH |
| Intracellular pH imaging | Live-cell pH dynamics | Neuronal pH regulation |
| Proteomics | Protein abundance and modifications | Acid stress adaptation |
| Metabolomics | Metabolite levels | Metabolic rewiring on acid |
| Electrophysiology | Ion channel and receptor function | pH modulation of glycine receptors |
| CRISPR knockout screening | Gene essentiality under acidic pH | Identify acid-response genes |
| Autophagy flux assays | Autophagic activity | Acid-induced autophagy |
Transcriptomics and RNA-seq
RNA-seq measures global gene expression changes in response to acidic pH. Time-course transcriptomic studies in Sinorhizobium meliloti revealed dynamic responses to a shift to acidic pH. Similar approaches in Lactobacillus plantarum identified acid resistance genes. RNA-seq is essential for defining the transcriptional program of GO:0071468.
Intracellular pH imaging
Fluorescent pH indicators and imaging techniques measure intracellular pH changes in live cells. Studies in hippocampal CA1 neurons used pH measurements to track responses to anoxia. Such methods are critical for linking acidic pH stimuli to cellular responses.
Proteomics and metabolomics
Proteomic and metabolomic analyses identify protein and metabolite changes under acidic pH. These approaches complement transcriptomics to reveal post-transcriptional and metabolic adaptations. They are useful for understanding autophagy and metabolic rewiring on acid.
Electrophysiology and receptor assays
Electrophysiological recordings measure the effect of acidic pH on ion channels and receptors. For example, glycine receptor responses to synaptic-like applications are reduced by acidic pH. These assays are key for studying pH modulation of neuronal signaling.
How CRISPR Can Be Used to Study GO:0071468 cellular response to acidic pH
Knockout
CRISPR knockout is used to delete genes such as CA9, SLC9A1, or RstAB to test their requirement in cellular response to acidic pH. Knockout cell lines can be challenged with acidic media to measure survival, pH regulation, and gene expression changes. In bacteria, knockout of RstAB reduces pathogenicity under acidic conditions within macrophages.
Point Mutation
Point mutations can be introduced into genes encoding proton sensors or ion transporters to dissect specific residues required for acid sensing. For example, mutations in glycine receptor subunits can alter pH sensitivity. Point-mutation models help distinguish between binding, gating, and regulatory functions.
Knock-in
Knock-in of tagged or reporter alleles allows visualization and quantification of acid-response proteins in live cells. Tagged ATG proteins can be used to monitor autophagy under acidic pH. Knock-in of disease-associated mutations can model human variants affecting pH response.
Overexpression
Overexpression of proton-sensing receptors, carbonic anhydrases, or ion transporters can enhance or dysregulate cellular response to acidic pH. Overexpression models are useful for gain-of-function studies and for testing therapeutic inhibitors.
How EDITGENE Supports cellular response to acidic pH Research
Researchers studying cellular response to acidic pH-related genes often need to determine whether a candidate gene is causally involved in acid sensing, adaptation, or disease. CRISPR-based models provide the precision required to test these hypotheses in relevant cell types and organisms.
Contact EDITGENE today to design your custom CRISPR model for cellular response to acidic pH research.
Frequently Asked Questions About cellular response to acidic pH
What is GO:0071468 cellular response to acidic pH?
GO:0071468 is a biological process term describing any cellular change in state or activity caused by a pH stimulus below 7, including changes in movement, secretion, enzyme production, and gene expression.
What genes are involved in cellular response to acidic pH?
Key genes include SLC9A1 (NHE1), CA9, CA12, GPR4, GPR65, GPR68, ASIC channels, RstA/RstB in bacteria, and glycine receptor subunits GLRA1 and GLRB.
How do cells sense acidic pH?
Cells sense acidic pH through proton-sensing G protein-coupled receptors, acid-sensing ion channels, and two-component systems such as RstAB in bacteria.
Why is acidic pH important in cancer?
The acidic tumor microenvironment drives cancer progression, invasion, and immune evasion, and tumor cells adapt through pH-regulatory proteins and autophagy.
How does acidic pH affect neurons?
Acidic pH can reduce neurotransmitter receptor efficacy, as shown for glycine receptors, and intracellular pH regulation is critical during anoxia in hippocampal neurons.
What methods are used to study cellular response to acidic pH?
Common methods include RNA-seq, intracellular pH imaging, proteomics, metabolomics, electrophysiology, and CRISPR screening.
Can CRISPR be used to study acid-response genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to test the causal role of acid-response genes.
What is the role of autophagy in acidic pH response?
Acidic pH can induce autophagy, which supports cell survival by recycling cellular components under stress.
How do bacteria respond to acidic pH?
Bacteria such as adherent-invasive E. coli use two-component systems like RstAB to sense acidic conditions and promote pathogenicity within macrophages.
What is the synonym for GO:0071468?
The synonym is cellular response to acidity.
Conclusion
GO:0071468 cellular response to acidic pH is a fundamental biological process that connects environmental acidity to cell state, gene expression, metabolism, and survival. It is relevant to cancer, infectious disease, neuroscience, and microbiome research, with key roles for proton sensors, ion transporters, carbonic anhydrases, and autophagy machinery. CRISPR-based models and multi-omics methods provide powerful tools to dissect this response and identify therapeutic targets.
References
- 1. Boedtkjer E et al.. 2020. The Acidic Tumor Microenvironment as a Driver of Cancer.. Annu Rev Physiol 82:103-126 PMID: 31730395
- 2. Zhang J et al.. 2019. Sour Sensing from the Tongue to the Brain.. Cell 179(2):392-402.e15 PMID: 31543264
- 3. Yao T et al.. 2024. Two-component system RstAB promotes the pathogenicity of adherent-invasive Escherichia coli in response to acidic conditions within macrophages.. Gut Microbes 16(1):2356642 PMID: 38769708
- 4. Ivica J et al.. 2022. Acidic pH reduces agonist efficacy and responses to synaptic-like glycine applications in zebrafish α1 and rat α1β recombinant glycine receptors.. J Physiol 600(2):333-347 PMID: 34802146
- 5. Hellweg C et al.. 2009. The time course of the transcriptomic response of Sinorhizobium meliloti 1021 following a shift to acidic pH.. BMC Microbiol 9:37 PMID: 19216801
- 6. Šeme H et al.. 2015. Acid resistance and response to pH-induced stress in two Lactobacillus plantarum strains with probiotic potential.. Benef Microbes 6(3):369-79 PMID: 25380802
- 7. Sheldon C et al.. 2002. Intracellular pH response to anoxia in acutely dissociated adult rat hippocampal CA1 neurons.. J Neurophysiol 87(5):2209-24 PMID: 11976362
- 8. Wojtkowiak JW et al.. 2012. Autophagy on acid.. Autophagy 8(11):1688-9 PMID: 22874557
