CCL5 (C-C Motif Chemokine Ligand 5), also known as RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted), is a pro-inflammatory chemokine that plays a critical role in immune cell recruitment and neuroinflammation. Originally identified as a T-cell attractant, CCL5 has emerged as a significant mediator in the pathogenesis of Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions[@appay2001].
The CCL5 gene is located on chromosome 17q12 and consists of three exons spanning approximately 8.5 kb. The gene encodes a 91-amino acid secreted protein that is produced as a precursor with a 23-amino acid signal peptide.
Protein Structure
CCL5 belongs to the CC chemokine family characterized by two conserved cysteine residues adjacent to the N-terminus:
N-terminal region — Contains the signal peptide (aa 1-23)
CC motif — Two conserved cysteines (aa 35-36)
Core domain — Receptor binding and specificity determining regions
C-terminal region — Heparin-binding domain for proteoglycan interaction
The mature, secreted CCL5 is a 68-amino acid polypeptide that forms homomers and can also form heteromers with other chemokines.
Function
Chemokine Signaling
CCL5 signals through three G protein-coupled receptors[@appay2001]:
CCR1 — Expressed on monocytes, neutrophils, T cells
CCR3 — Expressed on eosinophils, Th2 cells
CCR5 — Expressed on T cells, monocytes, macrophages; major HIV co-receptor
Signal Transduction:
Gαi-mediated inhibition of adenylate cyclase
PLCβ activation and IP3/DAG production
Calcium mobilization
PI3K/Akt and MAPK pathway activation
Actin polymerization and chemotaxis
Biological Activities
T cell recruitment — Potent attractant for CD4+ and CD8+ T lymphocytes
Monocyte recruitment — Facilitates monocyte migration into tissues
Basophil activation — Induces histamine release
Eosinophil recruitment — Critical for allergic inflammation
Memory T cell homing — Guides tissue-specific trafficking
HIV restriction — Natural CCR5 ligand can block HIV entry
Expression and Regulation
Cellular Expression
CCL5 is produced by multiple cell types:
T cells — Especially CD8+ cytotoxic and CD4+ memory T cells
Macrophages — Pro-inflammatory M1 phenotype
Platelets — Stored in α-granules
Fibroblasts — In response to inflammatory signals
Endothelial cells — Under inflammatory conditions
Neurons — Particularly in pathological states
Regulation
CCL5 expression is dynamically regulated:
Transcriptional — NF-κB, AP-1, STAT1 response elements
Post-transcriptional — AU-rich elements in 3' UTR affect mRNA stability
[Human Protein Atlas - CCL5](https://www.proteinatlas.org/ENSG00000161570-CCL5)
References
[Appay V, Rowland-Jones SL, RANTES: a chemokine with multiple roles (2001)](https://pubmed.ncbi.nlm.nih.gov/11748864/)
[Galimberti D et al, CCL5 in Alzheimer's disease: a novel biomarker and therapeutic target (2020)](https://doi.org/10.3233/JAD-191234)
[McGeer PL, McGeer EG, The inflammatory response system of brain: implications for therapy of Alzheimer and Parkinson disease (1999)](https://doi.org/10.1016/S0531-5565(99)00038-6)
[Kho DS et al, Chemokines and their receptors in Parkinson's disease (2011)](https://pubmed.ncbi.nlm.nih.gov/21833331/)
Pathway Diagram
The following diagram shows the key molecular relationships involving CCL5 — C-C Motif Chemokine Ligand 5 discovered through SciDEX knowledge graph analysis: