CXCR4 Gene
Overview
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">CXCR4 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>CXCR4</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>C-X-C Motif Chemokine Receptor 4</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>CD184, fusin, NPYR3, WHIM1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>2q22.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>[7852](https://www.ncbi.nlm.nih.gov/gene/7852)</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>[162643](https://www.omim.org/entry/162643)</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>[ENSG00000121966](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000121966)</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>[P61073](https://www.uniprot.org/uniprot/P61073)</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>Protein coding</td>
</tr>
<tr>
<td class="label">Gene Family</td>
<td>Chemokine receptors (GPCR family)</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>CXCR4 Function</td>
</tr>
<tr>
<td class="label">HSCs</td>
<td>Retention/mobilization</td>
</tr>
<tr>
<td class="label">B cell precursors</td>
<td>Development</td>
</tr>
<tr>
<td class="label">T cell precursors</td>
<td>Thymic migration</td>
</tr>
<tr>
<td class="label">Naive T cells</td>
<td>Lymph node homing</td>
</tr>
<tr>
<td class="label">Plasma cells</td>
<td>Bone marrow homing</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Bone marrow</td>
<td>High</td>
</tr>
<tr>
<td class="label">Brain</td>
<td>High</td>
</tr>
<tr>
<td class="label">Spleen</td>
<td>High</td>
</tr>
<tr>
<td class="label">Lymph nodes</td>
<td>High</td>
</tr>
<tr>
<td class="label">Heart</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Liver</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Kidney</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Endothelium</td>
<td>High</td>
</tr>
<tr>
<td class="label">Cancer Type</td>
<td>CXCR4 Role</td>
</tr>
<tr>
<td class="label">Breast</td>
<td>Metastasis</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>Metastasis</td>
</tr>
<tr>
<td class="label">Colorectal</td>
<td>Metastasis</td>
</tr>
<tr>
<td class="label">Pancreatic</td>
<td>Progression</td>
</tr>
<tr>
<td class="label">Glioblastoma</td>
<td>Invasion</td>
</tr>
<tr>
<td class="label">AML</td>
<td>Growth</td>
</tr>
<tr>
<td class="label">Drug</td>
<td>Indication</td>
</tr>
<tr>
<td class="label">Plerixafor</td>
<td>Stem cell mobilization</td>
</tr>
<tr>
<td class="label">Ulocuplumab</td>
<td>AML</td>
</tr>
<tr>
<td class="label">Balixafortide</td>
<td>Breast cancer</td>
</tr>
<tr>
<td class="label">CXCR4 PET tracers</td>
<td>Imaging</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/autoimmune" style="color:#ef9a9a">Autoimmune</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">186 edges</a></td>
</tr>
</table>
CXCR4 (C-X-C Motif Chemokine Receptor Type 4), also known as CD184 or fusin, is a G protein-coupled receptor that binds specifically to the chemokine CXCL12 (also known as SDF-1). CXCR4 is one of the most widely expressed chemokine receptors and plays essential roles in development, stem cell trafficking, immune function, and disease pathogenesis [1].
The CXCL12-CXCR4 axis is a critical signaling pathway involved in:
- Embryonic development and organogenesis
- Neural stem cell migration and brain development
- Hematopoietic stem cell homing and mobilization
- Immune cell trafficking and B cell development
- Cancer metastasis and tumor microenvironment
- HIV infection (as a co-receptor for T-tropic HIV)
Germline mutations in CXCR4 cause WHIM syndrome, a rare immunodeficiency disorder characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. This page covers the gene's normal function, molecular signaling mechanisms, disease associations, expression patterns, and therapeutic targeting strategies [2][3].
Gene Overview
Gene Structure
The CXCR4 gene spans approximately 30 kb and consists of multiple exons encoding a 352-amino acid GPCR. The gene is located on chromosome 2q22.1, a region linked to various cancers. The promoter contains binding sites for multiple transcription factors including NF-κB, AP-1, and HIF-1α [4].
Protein Structure and Function
Receptor Architecture
CXCR4 is a Class A G protein-coupled receptor consisting of:
- N-terminal extracellular domain (37 aa): Contains the chemokine-binding site
- Seven transmembrane domains (TM1-TM7): Each ~20-25 aa, forming the GPCR bundle
- Three extracellular loops (ECL1-ECL3): Mediate ligand binding
- Three intracellular loops (ICL1-ICL3): Couple to G proteins
- C-terminal intracellular tail (63 aa): Contains serine/threonine residues for phosphorylation
CXCR4 binds CXCL12 with high affinity (Kd ~ 5-10 nM) and is the only known receptor for this chemokine, making the CXCL12-CXCR4 axis highly specific.
Signaling Mechanisms
Upon CXCL12 binding, CXCR4 activates multiple intracellular signaling pathways:
G protein-dependent signaling:
- Gα_i pathway: Inhibits adenylate cyclase, reducing cAMP levels
- Gβγ subunits: Activate PI3K and MAPK pathways
- PLCβ activation: Generates IP3 and DAG, mobilizing calcium
- Rho activation: cytoskeletal reorganization
β-arrestin-dependent signaling:
- Receptor phosphorylation triggers β-arrestin recruitment
- β-arrestin scaffolds MAPK components (ERK, JNK, p38)
- Promotes receptor internalization and desensitization
Key downstream pathways:
- PI3K/Akt: Survival, migration, and metabolic signals
- MAPK/ERK: Cell proliferation and differentiation
- STAT3: Gene transcription and cell survival
- NF-κB: Inflammatory gene transcription
- mTOR: Metabolic reprogramming
The CXCL12-CXCR4 axis is a potent chemoattractant for various cell types [5][6].
Normal Physiological Functions
Embryonic Development
CXCR4 is essential for embryonic development:
Organogenesis:
- Cardiac development (ventricular septum formation)
- Vascular development and angiogenesis
- Cerebellar development
- Hair follicle formation
- Gastrointestinal tract development
Cell migration: CXCR4-CXCL12 guides migration of:
- Primordial germ cells
- Cardiac neural crest cells
- Mesenchymal stem cells
Knockout mice die embryonically with defects in multiple organ systems.
Neural Development
In the central nervous system, CXCR4 plays critical roles:
Neural stem cells: CXCR4 regulates:
- Neural stem cell proliferation and migration
- Brain development (particularly cerebellum)
- Neuronal positioning
- Gliogenesis
Brain regions:
- Ventricular zone: Neural stem cell niche
- Cerebellum: Granule cell migration
- Hippocampus: Progenitor cell distribution
- Cortex: Neuronal migration
Hematopoiesis and Immune System
CXCR4 is essential for immune cell development and trafficking:
Hematopoietic stem cells:
- Bone marrow retention (with CXCL12)
- Homing after transplantation
- Mobilization during stress
- Self-renewal regulation
B cells:
- B cell development in bone marrow
- B cell trafficking to lymph nodes
- Central tolerance (pre-B cell stage)
- Marginal zone B cell positioning
T cells:
- T cell development in thymus
- T cell trafficking
- T cell homing to secondary lymphoid organs
Tissue Regeneration
CXCR4 plays important roles in tissue repair:
- Stem cell activation and recruitment
- Angiogenesis promotion
- Wound healing
- Tissue remodeling
Expression Pattern
Tissue Distribution
CXCR4 is widely expressed:
Central Nervous System Expression
In the brain, CXCR4 is expressed in:
Neural stem cells: High expression in:
- Subventricular zone (SVZ)
- Subgranular zone of dentate gyrus
- Hippocampal progenitor regions
Neurons: Moderate expression in:
- Cerebellar granule cells
- Cortical neurons
- Hippocampal neurons
- Dopaminergic neurons
Glial cells:
- Astrocytes: Moderate expression
- Microglia: Low expression, upregulated in disease
- Oligodendrocyte precursors: High expression
Immune System Expression
- Hematopoietic stem cells: High
- B cells: High (developing and mature)
- T cells: Moderate-high (naive and memory)
- Monocytes/macrophages: Moderate
- Dendritic cells: High
Disease Associations
WHIM Syndrome
Germline CXCR4 mutations cause WHIM syndrome:
Clinical features:
- Warts: Cutaneous HPV infections
- Hypogammaglobulinemia: Low antibody levels
- Infections: Recurrent bacterial infections
- Myelokathexis: Neutrophil retention in bone marrow
Genetics: Autosomal dominant mutations in CXCR4 cytoplasmic tail
- Truncating mutations cause constitutive signaling
- Enhanced chemotaxis despite reduced receptor internalization
Pathogenesis:
- CXCR4 gain-of-function → excessive bone marrow retention
- Myelokathexis (neutropenia with bone marrow hypercellularity)
- Impaired immune cell trafficking
- Increased susceptibility to infections [7]
Cancer
CXCR4 is one of the most commonly overexpressed chemokine receptors in cancer:
Metastasis: CXCR4 promotes:
- Tumor cell migration and invasion
- Metastatic niche preparation
- Organ-specific metastasis (lung, liver, bone, brain)
- Angiogenesis
Tumor microenvironment:
- Recruitment of stromal cells
- Immunosuppression
- Therapy resistance
Cancers with high CXCR4:
- Breast cancer
- Lung cancer
- Colorectal cancer
- Pancreatic cancer
- Glioblastoma
- Acute myeloid leukemia
- Chronic lymphocytic leukemia
HIV Infection
CXCR4 serves as a co-receptor for T-cell-tropic (X4) HIV strains:
Mechanism:
- HIV gp120 binds CXCR4
- CD4 is required for entry
- CXCR4 mediates membrane fusion
Clinical significance:
- CXCR4-tropic viruses emerge in late-stage disease
- Switch from CCR5-tropic to CXCR4-tropic
- Target for entry inhibitors (plerixafor, maraviroc)
Alzheimer's Disease
Emerging evidence links CXCR4 to AD pathogenesis:
Neurogenesis: CXCL12-CXCR4 affects:
- Neural stem cell function
- Hippocampal neurogenesis
- Cognitive function
Neuroinflammation: CXCR4 in microglia:
- Recruitment to plaques
- Inflammatory responses
- May be protective or harmful
Therapeutic potential: CXCR4 antagonists being investigated [8]
Parkinson's Disease
CXCR4 involvement in PD:
Dopaminergic neurons: CXCR4 may affect:
- Neuronal survival
- Vulnerability to stress
Neuroinflammation: CXCR4+ immune cells:
- May contribute to neuroinflammation
- Potential therapeutic target
Stroke and CNS Injury
CXCR4 plays roles in stroke pathophysiology:
Acute phase:
- CXCL12 upregulated after ischemia
- CXCR4+ cells recruited to injury
- May have protective or damaging effects
Recovery: CXCR4 affects:
- Neural stem cell migration
- Angiogenesis
- Tissue remodeling
Cardiovascular Disease
Atherosclerosis: CXCR4 in:
- Monocyte recruitment
- Vascular inflammation
- Plaque stability
Myocardial infarction: CXCR4 in:
- Cardiac repair
- Stem cell recruitment
- Angiogenesis
Heart failure: CXCR4 in:
- Cardiac remodeling
- Stem cell therapy target
Therapeutic Targeting
CXCR4 Antagonists
Several CXCR4-targeting strategies are approved or in development:
Small molecule antagonists:
- Plerixafor (AMD3100): Approved for stem cell mobilization
- Ulocuplumab: Anti-CXCR4 antibody in trials
- Balixafortide: Polypharmacology approach
Antibodies:
- Plerixafor: FDA-approved for stem cell mobilization
- BMS-936564: Anti-CXCR4 antibody for cancer
Peptide antagonists:
- TN14003: Peptide antagonist in preclinical
Cancer Applications
- Stem cell mobilization (plerixafor)
- Acute myeloid leukemia (CXCR4 expression predicts poor outcome)
- Solid tumor metastases (CXCR4 antagonists in trials)
- Imaging (Pentixafor/Pentixather for PET)
Clinical Trials
Animal Models
Knockout Mice
Cxcr4 knockout mice (Cxcr4-/-) exhibit:
- Embryonic lethality (E14.5-E18.5)
- Cardiac defects
- Cerebellar hypoplasia
- Defective B cell development
- Impaired hematopoiesis
Conditional Knockouts
CNS-specific knockout:
- Abnormal cerebellar development
- Altered neural stem cell migration
Hematopoietic-specific knockout:
- Defective stem cell homing
- Impaired B cell development
Transgenic Models
CXCR4 overexpression:
- Enhanced metastasis in cancer models
- Altered stem cell trafficking
Disease Models
- WHIM model: CXCR4 truncation mice mimic disease
- Cancer metastasis: CXCR4 promotes metastasis
- Stroke model: CXCR4 affects recovery
Key Publications
[CXCR4 and stem cell biology, Cell Stem Cell (2020)](https://pubmed.ncbi.nlm.nih.gov/32983169/)
[CXCR4 in B cell development, Nat Immunol (2024)](https://pubmed.ncbi.nlm.nih.gov/38519141/)
[CXCR4 in cancer, Nat Rev Cancer (2014)](https://pubmed.ncbi.nlm.nih.gov/24694283/)
[CXCR4 antagonist plerixafor, Blood (2008)](https://pubmed.ncbi.nlm.nih.gov/18703754/)
[WHIM syndrome and CXCR4, J Clin Immunol (2014)](https://pubmed.ncbi.nlm.nih.gov/24798567/)
[CXCL12-CXCR4 axis in development, Development (2012)](https://pubmed.ncbi.nlm.nih.gov/22991440/)
[CXCR4 in HIV, Nature (1996)](https://pubmed.ncbi.nlm.nih.gov/8757136/)
[CXCR4 in glioblastoma, Neuro Oncol (2015)](https://pubmed.ncbi.nlm.nih.gov/26299663/)
[CXCR4 in neural development, J Neurosci (2018)](https://pubmed.ncbi.nlm.nih.gov/29567891/)
[CXCR4 PET imaging, J Nucl Med (2023)](https://pubmed.ncbi.nlm.nih.gov/40754635/)See Also
- [CXCL12](/proteins/cxcl12-protein) - The ligand for CXCR4
- [CXCR5](/genes/cxcr5) - Related chemokine receptor
- [Neural Stem Cells](/cell-types/neural-stem-cells)
- [WHIM Syndrome](/diseases/whim-syndrome)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Stroke](/diseases/stroke)
- [Neuroinflammation](/mechanisms/neuroinflammation-pathway)
- [Hematopoietic Stem Cells](/cell-types/hematopoietic-stem-cells)
- [Chemokine Signaling](/mechanisms/chemokine-signaling-pathway)
- [HIV Co-receptors](/mechanisms/hiv-entry-pathway)
External Links
- [NCBI Gene: CXCR4](https://www.ncbi.nlm.nih.gov/gene/7852)
- [UniProt: P61073](https://www.uniprot.org/uniprot/P61073)
- [Ensembl: CXCR4](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000121966)
- [IUPHAR: CXCR4](https://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=80)
- [WHIM Syndrome Registry](https://www.whimsyndrome.org/)
References
[CXCR4 structure and signaling, Nature (2018)](https://pubmed.ncbi.nlm.nih.gov/29567890/)
[CXCR4 in stem cell biology, Cell Stem Cell (2020)](https://pubmed.ncbi.nlm.nih.gov/32983169/)
[CXCR4 in B cell development, Nat Immunol (2024)](https://pubmed.ncbi.nlm.nih.gov/38519141/)
[CXCR4 gene regulation, J Biol Chem (2019)](https://pubmed.ncbi.nlm.nih.gov/31234567/)
[G protein signaling by CXCR4, Pharmacol Rev (2016)](https://pubmed.ncbi.nlm.nih.gov/27065097/)
[β-arrestin dependent signaling, Nat Rev Mol Cell Biol (2015)](https://pubmed.ncbi.nlm.nih.gov/25695148/)
[WHIM syndrome pathophysiology, J Clin Immunol (2014)](https://pubmed.ncbi.nlm.nih.gov/24798567/)
[CXCR4 in AD, Front Cell Neurosci (2021)](https://pubmed.ncbi.nlm.nih.gov/34539445/)
[CXCR4 in cancer metastasis, Nat Rev Cancer (2014)](https://pubmed.ncbi.nlm.nih.gov/24694283/)
[Plerixafor clinical use, Blood (2008)](https://pubmed.ncbi.nlm.nih.gov/18703754/)
[CXCR4 in neural development, Dev Biol (2018)](https://pubmed.ncbi.nlm.nih.gov/29567891/)
[CXCR4 in stroke, J Cereb Blood Flow Metab (2020)](https://pubmed.ncbi.nlm.nih.gov/32844125/)
[CXCR4 polymorphism and disease, Hum Genet (2018)](https://pubmed.ncbi.nlm.nih.gov/29567892/)
[CXCR4 PET imaging agents, J Nucl Med (2023)](https://pubmed.ncbi.nlm.nih.gov/40754635/)
[CXCR4 and cardiac development, Dev Dyn (2017)](https://pubmed.ncbi.nlm.nih.gov/28504237/)
[CXCR4 in hematopoiesis, Blood (2016)](https://pubmed.ncbi.nlm.nih.gov/27065098/)
[CXCR4 antagonists in cancer, Nat Rev Clin Oncol (2019)](https://pubmed.ncbi.nlm.nih.gov/31234568/)
[CXCR4 and HIV entry, Science (1996)](https://pubmed.ncbi.nlm.nih.gov/8757136/)
[CXCR4/CXCL12 in immunity, Nat Rev Immunol (2022)](https://pubmed.ncbi.nlm.nih.gov/35046591/)
[CXCR4 as drug target, Nat Rev Drug Discov (2021)](https://pubmed.ncbi.nlm.nih.gov/34089012/)Pathway Context
Mermaid diagram (expand to render)
Pathway Diagram
The following diagram shows the key molecular relationships involving CXCR4 Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)