GO:0015054 gastrin receptor activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015054 (gastrin receptor activity) is a molecular function defined as the binding of gastrin to a receptor that transmits signals across the membrane by activating an associated G-protein.
• The receptor is also known as the cholecystokinin-B receptor (CCKBR or CCK2R) and is a class A G-protein-coupled receptor.
• Gastrin receptor activity is central to the regulation of gastric acid secretion, the gastrin-ECL cell-parietal cell axis, and epithelial cell proliferation [1,5,7].
• Dysregulated gastrin receptor signaling is implicated in gastric cancer, colorectal adenoma-carcinoma progression, and salt-sensitive hypertension [2,3,8].
• CCKBR expression marks a subset of gastric cancer cells that contribute to intratumor heterogeneity and can be targeted with FOXO inhibition.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable precise dissection of gastrin receptor function in health and disease.
Description
Gastrin receptor activity (GO:0015054) is a molecular function that mediates the cellular response to the peptide hormone gastrin. According to the Gene Ontology, this activity involves combining with gastrin and transmitting the signal across the membrane by activating an associated G-protein to initiate a change in cell activity. The receptor responsible for this activity is the cholecystokinin-B receptor (CCKBR), also known as CCK2R, a class A G-protein-coupled receptor that binds both gastrin and cholecystokinin. This receptor is a key regulator of gastric acid secretion and mucosal growth, and its pharmacology has been extensively reviewed [1,5]. Researchers study gastrin receptor activity because it sits at the intersection of normal gastrointestinal physiology and multiple disease processes. The gastrin-ECL cell-parietal cell axis is a classic neuroendocrine circuit in which gastrin released from G cells stimulates enterochromaffin-like (ECL) cells to release histamine, which in turn drives acid secretion from parietal cells. Beyond acid secretion, gastrin receptor activation is an early event in the adenoma-carcinoma sequence of the stomach and colon, linking chronic hypergastrinemia to epithelial proliferation and neoplasia. More recently, CCKBR has been identified as a marker of a distinct cancer cell subpopulation in gastric cancer that contributes to intratumor heterogeneity and may confer sensitivity to FOXO inhibition. In addition, intestinal gastrin/CCKBR signaling has been shown to ameliorate salt-sensitive hypertension by inhibiting the intestinal Na+/H+ exchanger 3 through a PKC-mediated pathway involving NHERF1 and NHERF2. These diverse roles make gastrin receptor activity a compelling target for both basic and translational research.
gastrin receptor activity At A Glance
| GO ID | GO:0015054 |
|---|---|
| GO term | gastrin receptor activity |
| Ontology | molecular_function |
| Synonym | cholecystokinin-B receptor activity |
| Definition | Combining with gastrin and transmitting the signal across the membrane by activating an associated G-protein to initiate a change in cell activity. |
| Major function | Gastrin binding and G-protein-coupled signal transduction |
| Receptor protein | CCKBR (also known as CCK2R) |
| Primary ligands | Gastrin, cholecystokinin |
| Tissue distribution | Stomach (ECL cells, parietal cells), intestine, kidney, trophoblast, and other tissues [1,4] |
What Is GO:0015054?
Gastrin receptor activity (GO:0015054) is the molecular function of a receptor that binds the hormone gastrin and, upon binding, activates an associated G-protein to transmit a signal across the cell membrane, thereby initiating changes in cell behavior. This activity is synonymous with cholecystokinin-B receptor activity and is mediated by the CCKBR (CCK2R) protein.
Why Is gastrin receptor activity Important in Cell Biology?
Gastrin receptor activity is essential for normal gastrointestinal physiology, particularly the regulation of gastric acid secretion and mucosal homeostasis, and its dysregulation is implicated in major human diseases including gastric and colorectal cancer, hypertension, and developmental disorders [1,2,3,5,8]. Understanding this activity at the molecular level provides a foundation for therapeutic targeting of CCKBR in oncology and beyond.
• Controls gastric acid secretion via the gastrin-ECL cell-parietal cell axis [1,7].
• Regulates epithelial cell proliferation in the stomach and colon [5,8].
• Its activation is an early event in the adenoma-carcinoma sequence.
• CCKBR+ cancer cells contribute to intratumor heterogeneity in gastric cancer and may be targeted by FOXO inhibition.
• Intestinal gastrin/CCKBR signaling ameliorates salt-sensitive hypertension through PKC-mediated inhibition of NHE3.
• Expressed in trophoblasts and involved in placental signaling.
• Renal gastrin receptor regulation involves GRK4 and is linked to hypertension.
• CCK2 receptor antagonists are valuable pharmacological tools to study the gastrin-ECL cell-parietal cell axis.
• Provides a paradigm for understanding G-protein-coupled receptor signaling in neuroendocrine cells.
• Represents a potential therapeutic target in gastric and colorectal cancers [2,8].
What Happens During gastrin receptor activity?
Ligand binding and receptor activation
In simple terms: Gastrin binds to the CCKBR receptor on the cell surface, switching it on.
Gastrin, a peptide hormone produced by G cells in the stomach, binds to the extracellular domain of the CCKBR (CCK2R) receptor, a class A G-protein-coupled receptor. This binding induces a conformational change in the receptor that enables it to act as a guanine nucleotide exchange factor for an associated heterotrimeric G-protein. The gastrin receptor pharmacology has been extensively characterized, showing that both gastrin and cholecystokinin can activate the receptor with different affinities.
G-protein activation and downstream signaling
In simple terms: The activated receptor turns on a G-protein, which then triggers signaling inside the cell.
Upon gastrin binding, the receptor activates an associated G-protein, leading to the exchange of GDP for GTP on the G-alpha subunit and dissociation of the G-beta-gamma dimer. This initiates a cascade of intracellular signaling events, including activation of phospholipase C, generation of inositol trisphosphate and diacylglycerol, and mobilization of intracellular calcium. In intestinal epithelial cells, gastrin/CCKBR signaling activates protein kinase C (PKC), which then phosphorylates and regulates the Na+/H+ exchanger 3 (NHE3) through NHERF1 and NHERF2 scaffolding proteins.
Cellular responses: acid secretion and proliferation
In simple terms: The signal leads to acid release and cell growth.
In the stomach, gastrin receptor activation on enterochromaffin-like (ECL) cells stimulates histamine release, which subsequently acts on parietal cells to increase gastric acid secretion. This gastrin-ECL cell-parietal cell axis is a key neuroendocrine circuit. In addition, gastrin receptor activation promotes epithelial cell proliferation and is an early event in the adenoma-carcinoma sequence of the stomach and colon. In gastric cancer, CCKBR+ cancer cells represent a distinct subpopulation that contributes to intratumor heterogeneity and may respond to FOXO inhibition.
Receptor desensitization and regulation
In simple terms: After signaling, the receptor is turned off or recycled to prevent overactivity.
Like many G-protein-coupled receptors, the gastrin receptor undergoes desensitization and internalization following prolonged agonist exposure. G-protein-coupled receptor kinase 4 (GRK4) has been shown to regulate renal gastrin receptor activity, and its dysfunction is linked to hypertension. This regulatory mechanism involves phosphorylation of the receptor by GRK4, leading to beta-arrestin recruitment and reduced signaling. Such feedback regulation is critical for maintaining appropriate gastric acid secretion and preventing hypergastrinemia-driven pathologies.
Key Genes Involved in GO:0015054 gastrin receptor activity
The following genes and proteins are directly involved in gastrin receptor activity and its downstream signaling pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CCKBR (CCK2R) | Gastrin receptor; binds gastrin and activates G-proteins | Primary receptor for GO:0015054; target in gastric cancer and hypertension [1,2,3] |
| GAST | Produces gastrin, the ligand for CCKBR | Ligand availability regulates receptor activity; hypergastrinemia drives proliferation [5,8] |
| CCK | Produces cholecystokinin, an alternative ligand for CCKBR | Cross-reactivity with CCKBR influences signaling in trophoblasts and other tissues |
| GRK4 | G-protein-coupled receptor kinase 4; phosphorylates and desensitizes CCKBR | Regulates renal gastrin receptor activity; linked to hypertension |
| NHERF1 (SLC9A3R1) | Scaffolding protein that interacts with NHE3 and PKC | Mediates intestinal gastrin/CCKBR signaling to NHE3 in salt-sensitive hypertension |
| NHERF2 (SLC9A3R2) | Scaffolding protein that interacts with NHE3 and PKC | Mediates intestinal gastrin/CCKBR signaling to NHE3 in salt-sensitive hypertension |
| NHE3 (SLC9A3) | Na+/H+ exchanger 3; regulated by PKC downstream of CCKBR | Effector of intestinal gastrin/CCKBR signaling in hypertension |
| PRKCA (PKC-alpha) | Protein kinase C alpha; phosphorylates NHE3 and other targets | Mediates downstream signaling from gastrin/CCKBR in intestine |
| FOXO | Forkhead box O transcription factors; regulated by CCKBR signaling | CCKBR+ gastric cancer cells are sensitive to FOXO inhibition |
| TAS2R14 | Bitter taste receptor; co-expressed with CCKBR in trophoblasts | Potential cross-talk in placental signaling |
| ECL cell markers (e.g., HDC) | Histidine decarboxylase; produces histamine in ECL cells | Part of the gastrin-ECL cell-parietal cell axis |
| Parietal cell markers (e.g., ATP4A/ATP4B) | Gastric H+/K+-ATPase; responsible for acid secretion | Effector of gastrin-stimulated acid secretion |
| Somatostatin (SST) | Inhibits gastrin release from G cells | Negative regulator of gastrin receptor activity |
| Gastrin-releasing peptide (GRP) | Stimulates gastrin release from G cells | Upstream regulator of gastrin receptor activity |
| Beta-arrestin 1/2 (ARRB1/2) | Mediate receptor desensitization and internalization | Regulate CCKBR signaling duration |
| G-alpha subunits (e.g., GNAQ, GNA11) | Couple CCKBR to downstream effectors | Mediate G-protein activation by gastrin receptor |
| Phospholipase C (PLCB1) | Generates IP3 and DAG downstream of G-alpha | Key effector of gastrin receptor signaling |
| Intracellular calcium channels (e.g., ITPR1) | Release calcium from intracellular stores | Mediate calcium signaling downstream of CCKBR |
How Is gastrin receptor activity Regulated?
Gastrin receptor activity is regulated at multiple levels. Ligand availability is controlled by gastrin release from G cells, which is stimulated by gastrin-releasing peptide and inhibited by somatostatin. Receptor desensitization is mediated by G-protein-coupled receptor kinases, notably GRK4, which phosphorylates the receptor and promotes beta-arrestin recruitment, leading to reduced signaling. In the intestine, downstream signaling to NHE3 is modulated by PKC-mediated phosphorylation of NHERF1 and NHERF2. Additionally, chronic hypergastrinemia can upregulate receptor expression and signaling, contributing to proliferative responses.
gastrin receptor activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CCKBR | Gastric cancer, intratumor heterogeneity | CCKBR knockout or overexpression in gastric cancer cell lines; xenograft models |
| CCKBR | Salt-sensitive hypertension | Intestinal-specific CCKBR knockout mice; salt-sensitive hypertension models |
| GRK4 | Hypertension, renal gastrin receptor regulation | GRK4 knockout or point-mutation models in renal cells |
| GAST | Hypergastrinemia, adenoma-carcinoma sequence | Gastrin overexpression or knockout mice; colon cancer models |
| CCKBR | Trophoblast signaling, pregnancy | Trophoblast cell lines with CCKBR knockout or knockdown |
Gastric cancer and intratumor heterogeneity
CCKBR+ cancer cells constitute a distinct subpopulation in gastric cancer that contributes to intratumor heterogeneity. These cells are sensitive to FOXO inhibition, suggesting that targeting CCKBR+ cells or their downstream FOXO pathway may be a therapeutic strategy. Gastrin receptor activation is also an early event in the adenoma-carcinoma sequence, linking chronic hypergastrinemia to gastric and colorectal neoplasia.
Salt-sensitive hypertension
Intestinal gastrin/CCKBR signaling ameliorates salt-sensitive hypertension by inhibiting the intestinal Na+/H+ exchanger 3 (NHE3) through a PKC-mediated pathway involving NHERF1 and NHERF2. This identifies the gastrin receptor as a potential target for modulating intestinal sodium handling in hypertension.
Renal regulation and hypertension
GRK4 regulates renal gastrin receptor activity, and dysfunctional GRK4 is associated with hypertension. This suggests that renal gastrin receptor signaling may contribute to blood pressure regulation and that GRK4 variants could influence receptor desensitization in hypertensive patients.
Trophoblast biology and pregnancy
Cholecystokinin, gastrin, and their receptors, including CCKBR, are expressed in trophoblasts, where they may play a role in placental signaling alongside bitter taste receptor TAS2R14. This highlights a potential role for gastrin receptor activity beyond the gastrointestinal tract.
From gastrin receptor activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CCKBR loss affect gastric acid secretion? | CCKBR knockout mouse or gastric organoids |
| Does a specific CCKBR point mutation alter ligand binding? | Point-mutation knock-in via CRISPR in cell lines |
| Can CCKBR+ cancer cells be targeted? | CCKBR knockout or FOXO inhibitor treatment in gastric cancer organoids |
| Does intestinal CCKBR signaling regulate blood pressure? | Intestinal-specific CCKBR knockout mice on high-salt diet |
| How does GRK4 regulate CCKBR desensitization? | GRK4 knockout or overexpression in renal epithelial cells |
| Does gastrin promote proliferation in vivo? | Gastrin overexpression or knockout in mouse models of colon cancer |
How to Study the gastrin receptor activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radioligand binding | Receptor affinity and density | Characterizing CCK2 receptor antagonists [1,7] |
| GTPgammaS binding | G-protein activation | Measuring agonist efficacy at CCKBR |
| Calcium imaging | Intracellular calcium mobilization | Assessing downstream signaling in live cells |
| RNA-seq | Transcriptomic changes | Identifying CCKBR+ cancer cell subpopulations |
| CRISPR knockout | Gene function loss | Studying CCKBR role in acid secretion and hypertension [3,6] |
| Western blot | Protein expression and phosphorylation | Measuring NHE3 phosphorylation by PKC |
| Blood pressure telemetry | Blood pressure in vivo | Evaluating intestinal CCKBR in salt-sensitive hypertension |
Ligand binding assays
Radioligand binding assays using iodinated gastrin or CCK analogs are used to measure receptor affinity, density, and specificity. These assays are foundational for characterizing gastrin receptor pharmacology and have been used to define CCK2 receptor antagonists [1,7].
Signal transduction assays
Downstream signaling can be measured by assessing G-protein activation (GTPgammaS binding), intracellular calcium mobilization, inositol phosphate production, and PKC activity. These methods have been applied to study gastrin/CCKBR signaling in intestinal cells and trophoblasts [3,4].
Gene expression and knockout models
CRISPR-Cas9 knockout of CCKBR or its downstream effectors, combined with RNA-seq and proteomics, allows comprehensive analysis of gastrin receptor function. Such models have been used to study CCKBR+ cancer cell heterogeneity and intestinal NHE3 regulation [2,3].
In vivo physiological measurements
Gastric acid secretion can be measured in vivo using pylorus ligation or intragastric titration in animal models. Blood pressure telemetry in salt-sensitive hypertension models has been used to assess the role of intestinal gastrin/CCKBR signaling [3,7].
How CRISPR Can Be Used to Study GO:0015054 gastrin receptor activity
Knockout
CRISPR-Cas9 knockout of CCKBR in cell lines or animal models abolishes gastrin receptor activity, enabling researchers to study its role in acid secretion, proliferation, and hypertension. For example, intestinal-specific CCKBR knockout mice have been used to demonstrate the receptor's role in salt-sensitive hypertension.
Point Mutation
Point mutations in CCKBR can be introduced to dissect ligand binding specificity, G-protein coupling, or desensitization motifs. Such models are valuable for understanding how naturally occurring variants affect receptor function and disease risk.
Knock-in
Knock-in of tagged CCKBR (e.g., HA or GFP) allows visualization and biochemical isolation of the receptor in native tissues. This approach can reveal receptor trafficking, internalization, and interaction partners in vivo.
Overexpression
Overexpression of CCKBR in cell lines or transgenic mice can model hypergastrinemia-driven proliferation and cancer. For instance, CCKBR overexpression in gastric cancer cells has been used to study intratumor heterogeneity and FOXO sensitivity.
How EDITGENE Supports gastrin receptor activity Research
Researchers studying gastrin receptor activity-related genes often need to determine whether a candidate gene is causally involved in receptor signaling, disease progression, or therapeutic response. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for gastrin receptor activity research.
Frequently Asked Questions About gastrin receptor activity
What is gastrin receptor activity?
Gastrin receptor activity (GO:0015054) is the molecular function of binding gastrin and transmitting a signal across the membrane by activating an associated G-protein, thereby initiating changes in cell activity.
What genes are involved in gastrin receptor activity?
The primary gene is CCKBR (also known as CCK2R), which encodes the gastrin receptor. Other involved genes include GAST (gastrin), CCK (cholecystokinin), GRK4, and downstream effectors like NHE3 and PKC [1,3,6].
What is the synonym for gastrin receptor activity?
The official synonym is cholecystokinin-B receptor activity.
Which GO term describes gastrin receptor activity?
The Gene Ontology term is GO:0015054, gastrin receptor activity, under the molecular_function ontology.
How is gastrin receptor activity linked to cancer?
Gastrin receptor activation is an early event in the adenoma-carcinoma sequence, and CCKBR+ cancer cells contribute to intratumor heterogeneity in gastric cancer, with sensitivity to FOXO inhibition [2,8].
Does gastrin receptor activity affect blood pressure?
Yes, intestinal gastrin/CCKBR signaling ameliorates salt-sensitive hypertension by inhibiting NHE3 through a PKC-mediated pathway, and renal GRK4 regulates gastrin receptor activity in hypertension [3,6].
What is the gastrin-ECL cell-parietal cell axis?
It is a neuroendocrine circuit in which gastrin stimulates ECL cells to release histamine, which then drives acid secretion from parietal cells.
How can I study gastrin receptor activity in the lab?
Common methods include radioligand binding assays, GTPgammaS binding, calcium imaging, CRISPR knockout models, and in vivo acid secretion measurements [1,3,7].
What are CCK2 receptor antagonists?
They are pharmacological tools that block the gastrin receptor and are used to study the gastrin-ECL cell-parietal cell axis and acid secretion.
Is gastrin receptor activity involved in trophoblast biology?
Yes, cholecystokinin, gastrin, and their receptors, including CCKBR, are expressed in trophoblasts and may play a role in placental signaling.
Conclusion
Gastrin receptor activity (GO:0015054) is a fundamental molecular function that mediates the diverse physiological and pathological effects of gastrin. From regulating gastric acid secretion to influencing cancer heterogeneity and blood pressure, CCKBR signaling is a critical node in gastrointestinal and systemic biology. Continued research using advanced CRISPR models and multi-omics approaches will further illuminate its mechanisms and therapeutic potential.
References
- 1. Dockray GJ et al.. 2012. Gastrin receptor pharmacology.. Curr Gastroenterol Rep 14(6):453-9 PMID: 22983899
- 2. Tan Z et al.. 2024. CCKBR+ cancer cells contribute to the intratumor heterogeneity of gastric cancer and confer sensitivity to FOXO inhibition.. Cell Death Differ 31(10):1302-1317 PMID: 39164456
- 3. Jiang X et al.. 2022. Intestinal Gastrin/CCKBR (Cholecystokinin B Receptor) Ameliorates Salt-Sensitive Hypertension by Inhibiting Intestinal Na(+)/H(+) Exchanger 3 Activity Through a PKC (Protein Kinase C)-Mediated NHERF1 and NHERF2 Pathway.. Hypertension 79(8):1668-1679 PMID: 35674015
- 4. Taher S et al.. 2019. Cholecystokinin, gastrin, cholecystokinin/gastrin receptors, and bitter taste receptor TAS2R14: trophoblast expression and signaling.. Am J Physiol Regul Integr Comp Physiol 316(5):R628-R639 PMID: 30892908
- 5. Dimaline R et al.. 2014. Novel roles of gastrin.. J Physiol 592(14):2951-8 PMID: 24665102
- 6. Xia X et al.. 2023. Effect of GRK4 on renal gastrin receptor regulation in hypertension.. Clin Exp Hypertens 45(1):2245580 PMID: 37641972
- 7. Håkanson R et al.. 1999. CCK2 receptor antagonists: pharmacological tools to study the gastrin-ECL cell-parietal cell axis.. Regul Pept 80(1-2):1-12 PMID: 10235629
- 8. Smith AM et al.. 2000. Gastrin and gastrin receptor activation: an early event in the adenoma-carcinoma sequence.. Gut 47(6):820-4 PMID: 11076881
