CD40 - Cluster of Differentiation 40

CD40 Gene

Pathway Diagram

```mermaid
flowchart TD
CD4["CD4<br/>T-helper cell receptor"]

CD4 -->|"regulates"| Neurodegeneration["Neurodegeneration<br/>Process"]
CD4 -->|"activates"| MS["Multiple Sclerosis<br/>Autoimmune demyelination"]
CD4 -->|"inhibits"| ALS["Amyotrophic Lateral Sclerosis<br/>Motor neuron disease"]
CD4 -->|"regulates"| PD["Parkinson's Disease<br/>Dopaminergic degeneration"]
CD4 -->|"regulates"| Dementia["Dementia<br/>Cognitive decline"]

CD4 -->|"regulates"| Inflammation["Neuroinflammation<br/>Immune activation"]
CD4 -->|"regulates"| Autoimmune["Autoimmune Response<br/>Self-reactive immunity"]

Inflammation -->|"promotes"| Neurodegeneration
Inflammation -->|"contributes_to"| MS
Inflammation -->|"damages"| PD

Autoimmune -->|"drives"| MS
Autoimmune -->|"influences"| Neurodegeneration

CD4 -->|"activates"| Aging["Cellular Aging<br/>Senescence processes"]
Aging -->|"accelerates"| Neurodegeneration
Aging -->|"increases_risk"| Dementia

CD4 -->|"therapeutic_target"| MS_Treatment["MS Therapeutics<br/>Immunomodulation"]
CD4 -->|"therapeutic_target"| Neuro_Treatment["Neurodegeneration<br/>Therapeutics"]
CD4 -->|"biomarker_for"| ALS_Diagnosis["ALS Biomarker<br/>Disease monitoring"]

style CD4 fill:#006494
style MS_Treatment fill:#1b5e20
style Neuro_Treatment fill:#1b5e20
style ALS_Diagnosis fill:#1b5e20
style MS fill:#ef5350
style ALS fill:#ef5350
style Neurodegeneration fill:#ef5350
style Inflammation fill:#ef5350
style

CD40 Gene

Pathway Diagram

Introduction

Cd40 Cluster Of Differentiation 40 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-gene"> [@laman1996]
<table> [@tan2020]
<tr><th colspan="2" style="background:#f0f0f0;">Gene Overview</th></tr> [@caldi2021]
<tr><td><strong>Gene Symbol</strong></td><td>CD40</td></tr> [@gerritse1999]
<tr><td><strong>Full Name</strong></td><td>Cluster of Differentiation 40</td></tr> [@baker2006]
<tr><td><strong>Chromosomal Location</strong></td><td>20q12-q13</td></tr> [@ferrara2022]
<tr><td><strong>Protein Product</strong></td><td>CD40/TNFRSF5</td></tr> [@zhu2021]
<tr><td><strong>Molecular Weight</strong></td><td>~48 kDa (glycosylated)</td></tr>
<tr><td><strong>Gene Family</strong></td><td>TNF receptor superfamily</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/ali" style="color:#ef9a9a">ALI</a>, <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></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">84 edges</a></td>
</tr>
</table>
</div>

Overview

The CD40 gene encodes CD40, a member of the tumor necrosis factor receptor superfamily (TNFRSF5). CD40 is a costimulatory molecule critical for adaptive immune responses. It is expressed on antigen-presenting cells (B cells, dendritic cells, macrophages) and interacts with its ligand CD40L (CD154) on T cells. This interaction provides essential signals for T cell activation, B cell proliferation, immunoglobulin class switching, and dendritic cell maturation.

Gene Structure

The CD40 gene is located on chromosome 20q12-q13 and consists of 9 exons encoding a 277-amino acid type I membrane protein. The promoter contains binding sites for various transcription factors including [NF-κB](/entities/nf-kb), AP-1, and STAT elements, allowing regulation by inflammatory cytokines.

Protein Structure

CD40 is a type I transmembrane glycoprotein:

• Extracellular domain: 4 TNF receptor-associated factor (TRAF) binding sites
• Transmembrane domain: Single pass through membrane
• Cytoplasmic domain: ~62 amino acids with signaling motifs
• Glycosylation: Multiple N-linked glycosylation sites

Normal Function

CD40-CD40L signaling is central to immune function:

Expression Pattern

CD40 is expressed on:

• B cells: All B cell subsets
• Dendritic cells: Conventional and plasmacytoid
• Macrophages: M1 and M2 phenotypes
• Endothelial cells: Inflammatory activation
• Platelets: Upon activation
• Certain [neurons](/entities/neurons): Under pathological conditions
• [Astrocytes](/entities/astrocytes) and [microglia](/entities/microglia): In CNS inflammation

Role in Disease

Alzheimer's Disease

• CD40 expressed in AD brain by [microglia](/cell-types/microglia-neuroinflammation) and astrocytes
• CD40-CD40L interaction promotes:
• Microglial activation
• Pro-inflammatory cytokine production
• [Aβ](/proteins/amyloid-beta) production and aggregation
• Neurofibrillary tangle formation
• CD40L elevated in AD plasma and CSF
• CD40 polymorphisms affect AD risk
• Therapeutic targeting: CD40-CD40L blockade in development

Parkinson's Disease

• CD40 upregulated in substantia nigra of PD patients
• Expressed by activated microglia
• Contributes to dopaminergic neuron death
• CD40-CD40L in neuroinflammation
• Therapeutic potential of modulation

Amyotrophic Lateral Sclerosis

• CD40 expressed in ALS spinal cord
• Contributes to neuroinflammation
• Microglial activation through CD40
• Potential therapeutic target

Multiple Sclerosis

• CD40-CD40L critical for disease pathogenesis
• Blocking CD40L protects in EAE model
• Demyelination and inflammation
• Therapeutic antibodies in trials

Autoimmune Diseases

• Systemic lupus erythematosus: CD40L overexpression
• Rheumatoid arthritis: Synovial CD40 expression
• Multiple sclerosis: CD40 in lesion formation

Therapeutic Implications

| Approach | Status | Notes |
|----------|--------|-------|
| CD40L antibodies | Clinical (SLE) | BG9588, IDECABTAGEN |
| CD40 antagonists | Preclinical | Blocking signaling |
| Small molecule inhibitors | Research | TRAF domain inhibitors |
| Combination therapy | Research | With immunomodulators |

Key Research Directions

Background

The study of Cd40 Cluster Of Differentiation 40 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

See Also

• [Innate Immune Signaling Pathways in Alzheimer's Disease](/mechanisms/innate-immune-signaling-ad)
• [Update with 2025-2026 microglia research findings](/mechanisms/microglia-neuroinflammation)
• [Autoimmune Encephalitis](/diseases/autoimmune-encephalitis)
• [Peripheral Immune Infiltration in Neurodegeneration](/mechanisms/peripheral-immune-infiltration)
• [Neuroinflammation in Neurodegenerative Diseases](/mechanisms/neuroinflammation)
• [Autoimmune Encephalitis Mechanisms](/mechanisms/autoimmune-encephalitis)
• [Neuroinflammation Pathway](/mechanisms/neuroinflammation-pathway)
• [Cerebellar Basket Cells](/cell-types/cerebellar-basket-cells)

External Links

• [NCBI Gene - CD40](https://www.ncbi.nlm.nih.gov/gene)
• [UniProt - CD40](https://www.uniprot.org)
• [PubMed](https://pubmed.ncbi.nlm.nih.gov)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving CD40 - Cluster of Differentiation 40 discovered through SciDEX knowledge graph analysis: