SEMA3B
Semaphorin 3B: A Tumor Suppressor and Axon Guidance Molecule
Gene Information Card
| Symbol | SEMA3B |
|---|---|
| Full Name | Semaphorin 3B |
| Gene Type | Protein coding |
| Chromosomal Location | 3p21.31 |
| NCBI Gene ID | 7869 ncbi.nlm.nih.gov/gene/7869 |
| Ensembl ID | ENSG00000100031 |
| UniProt ID | Q13214 |
| OMIM ID | 601281 |
| HGNC ID | 10724 |
| Aliases | SEMA5, SemA, Sema3B, FLJ34866 |
Description
SEMA3B (Semaphorin 3B) is a protein-coding gene located on chromosome 3p21.31. It encodes a member of the semaphorin family of secreted proteins that function as axon guidance molecules during neural development. SEMA3B also acts as a tumor suppressor, particularly in lung cancer, where it is frequently inactivated by deletion or promoter methylation. The protein binds to neuropilin receptors and plexins to mediate cell signaling, influencing cell migration, apoptosis, and angiogenesis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Lung cancer (non-small cell) | Loss of SEMA3B expression via deletion or methylation promotes tumor growth and metastasis. | Multiple studies show SEMA3B is frequently deleted in 3p21.3 region in lung cancer (e.g., Lerman & Minna, Cancer Res, 2000). |
| Breast cancer | Reduced SEMA3B expression correlates with poor prognosis; re-expression inhibits tumor growth. | ClinVar and literature reports (e.g., Castro-Rivera et al., Oncogene, 2004). |
| Ovarian cancer | SEMA3B downregulation contributes to tumor progression and angiogenesis. | NCBI Gene and OMIM entries note altered expression in ovarian tumors. |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lung | 8.2 | Medium |
| Brain | 6.5 | Medium |
| Kidney | 5.1 | Low |
| Placenta | 4.3 | Low |
| Heart | 3.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| A549 (lung cancer) | 2.1 | Low expression due to promoter methylation |
| HEK293 (embryonic kidney) | 7.4 | Moderate expression |
| MCF7 (breast cancer) | 1.5 | Low expression |
| H1299 (lung cancer) | 0.8 | Very low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon; likely loss of function |
| c.220C>T (p.Arg74*) | Nonsense | Rare | Premature stop; loss of function |
| c.487_488delAG (p.Arg163Glufs*12) | Frameshift | Rare | Frameshift; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most reported SEMA3B mutations are loss-of-function, including nonsense, frameshift, and splice-site variants that truncate the protein or prevent its secretion.
Gain of Function (GOF)
No gain-of-function mutations have been reported for SEMA3B.
Dominant Negative (DN)
No dominant-negative mutations have been characterized for SEMA3B.
View complete mutation data：
Gene Ontology (GO)
| • semaphorin receptor binding | • neuropilin binding |
| • axon guidance | • negative regulation of cell migration |
| • negative regulation of angiogenesis | • apoptotic process |
Pathways
• Semaphorin interactions (Reactome: R-HSA-373755)
• Axon guidance (KEGG: hsa04360)
• Neuropilin signaling (Reactome: R-HSA-373752)
Protein Summary
SEMA3B encodes a secreted semaphorin of approximately 85 kDa. The protein contains an N-terminal Sema domain, a PSI domain, and an immunoglobulin-like domain. It functions as a chemorepellent for axons and inhibits tumor cell growth by binding to neuropilin-1/2 and plexin receptors, activating downstream signaling that leads to cytoskeletal rearrangement, apoptosis, and suppression of angiogenesis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SEMA3B Knockout HEK293 Cell Line | EDJ-KQ6138 | Human | 7869 | Details Get a Quote |
| SEMA3B Knockout HCT 116 Cell Line | EDJ-KQ29922 | Human | 7869 | Details Get a Quote |
| SEMA3B Knockout HeLa Cell Line | EDJ-KQ29923 | Human | 7869 | Details Get a Quote |
| SEMA3B Knockout A-549 Cell Line | EDJ-KQ28615 | Human | 7869 | Details Get a Quote |
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