CD22 Gene - Structure, Function, and Clinical Significance
A comprehensive overview of the CD22 gene, its protein product, associated diseases, expression patterns, and mutations.
Gene Information Card
| Symbol | CD22 |
|---|---|
| Full Name | CD22 molecule |
| Gene Type | protein-coding |
| Chromosomal Location | 19q13.12 |
| NCBI Gene ID | 933 ncbi.nlm.nih.gov/gene/933 |
| Ensembl ID | ENSG00000012124 |
| UniProt ID | P20273 |
| OMIM ID | 107266 |
| HGNC ID | 1643 |
| Aliases | SIGLEC-2, SIGLEC2 |
Description
CD22 (CD22 molecule) is a protein-coding gene located on chromosome 19q13.12. It encodes a transmembrane sialic acid-binding immunoglobulin-like lectin (Siglec) that is primarily expressed on B cells. CD22 functions as a regulatory component of the B-cell receptor (BCR) signaling complex, modulating immune responses. It is involved in B-cell activation, adhesion, and survival. CD22 has been implicated in autoimmune diseases and B-cell malignancies, making it a target for therapeutic interventions.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| B-cell chronic lymphocytic leukemia | CD22 is expressed on malignant B cells; its signaling can promote tumor cell survival and proliferation. | Expression studies and therapeutic targeting (e.g., inotuzumab ozogamicin) in clinical trials. |
| Non-Hodgkin lymphoma | CD22 overexpression on lymphoma cells contributes to immune evasion and tumor growth. | Immunohistochemical detection and anti-CD22 therapy studies. |
| Systemic lupus erythematosus (SLE) | CD22 regulates BCR signaling; altered CD22 function may lead to hyperactive B cells and autoantibody production. | Genetic association studies and mouse models. |
| Rheumatoid arthritis | CD22-mediated B-cell regulation is disrupted, contributing to autoantibody production. | Expression analysis in synovial B cells. |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Spleen | High | High |
| Lymph node | High | High |
| Bone marrow | Medium | Medium |
| Blood | Medium | Medium |
| Appendix | Medium | Medium |
| Tonsil | High | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Raji (Burkitt lymphoma) | High | B-cell line |
| Daudi (Burkitt lymphoma) | High | B-cell line |
| NALM-6 (B-ALL) | Medium | B-cell precursor |
| Jurkat (T-ALL) | Low | T-cell line (negative control) |
| HEK293 (embryonic kidney) | Low | Non-B-cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1234A>G (p.Lys412Glu) | Missense | Rare | Alters sialic acid binding; potential impact on B-cell signaling. |
| c.1567C>T (p.Arg523Trp) | Missense | Rare | May affect protein stability or ligand interaction. |
| c.2101delC (frameshift) | Frameshift | Very rare | Predicted to cause loss of function due to premature stop codon. |
Mutation functional classification
Loss of Function (LOF)
Loss-of-function mutations in CD22 are rare and may impair B-cell regulation, potentially contributing to autoimmune phenotypes.
Gain of Function (GOF)
No clear gain-of-function mutations have been documented; CD22 typically acts as an inhibitory receptor.
Dominant Negative (DN)
No evidence of dominant-negative effects reported.
View complete mutation data：
Gene Ontology (GO)
| • carbohydrate binding | • protein binding |
| • receptor activity | • signal transducer activity |
| • cell adhesion | • B cell receptor signaling pathway |
| • immune response | • cell surface receptor signaling pathway |
Pathways
• B cell receptor signaling pathway
• Signal transduction
• Immune system
Protein Summary
The CD22 protein is a type I transmembrane sialic acid-binding Ig-like lectin (Siglec) with seven extracellular immunoglobulin-like domains and a cytoplasmic tail containing immunoreceptor tyrosine-based inhibitory motifs (ITIMs). It is expressed on mature B cells and regulates B-cell activation by recruiting phosphatases (e.g., SHP-1) that dampen BCR signaling. CD22 also mediates cell adhesion and sialic acid-dependent interactions. Its expression is largely restricted to B cells, making it a valuable biomarker and therapeutic target in B-cell malignancies and autoimmune diseases.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CD226 Knockout HEK293 Cell Line | EDJ-KQ7125 | Human | 10666 | Details Get a Quote |
| CD22 Knockout HEK293 Cell Line | EDJ-KQ17687 | Human | 933 | Details Get a Quote |
| CD22 Knockout HCT 116 Cell Line | EDJ-KQ19776 | Human | 933 | Details Get a Quote |
| CD22 Knockout HeLa Cell Line | EDJ-KQ52826 | Human | 933 | Details Get a Quote |
| CD226 Knockout HeLa Cell Line | EDJ-KQ55459 | Human | 10666 | Details Get a Quote |
| CD22 Knockout A-549 Cell Line | EDJ-KQ61296 | Human | 933 | Details Get a Quote |
| CD226 Knockout A-549 Cell Line | EDJ-KQ63943 | Human | 10666 | Details Get a Quote |
| CD226 Knockout HCT 116 Cell Line | EDJ-KQ72400 | Human | 10666 | Details Get a Quote |
| CD22 Overexpression Raji Stable Cell Line | EDJ-GQ121 | Human | 933 | Details Get a Quote |
