| CLDN5 — Claudin-5 | |
|---|---|
| Symbol | CLDN5 |
| Full Name | Claudin-5 |
| Chromosome | 22q11.21 |
| NCBI Gene | 9079 |
| Ensembl | ENSG00000184113 |
| OMIM | 602507 |
| UniProt | O00511 |
| Diseases | Alzheimer's Disease, Parkinson's Disease, Multiple Sclerosis, Stroke, Vascular Dementia |
| Expression | Brain endothelial cells, Tight junctions of blood-brain barrier |
CLDN5 (Claudin-5) is a critical tight junction protein that maintains blood-brain barrier (BBB) integrity. It is essential for the paracellular barrier that prevents harmful substances from entering the brain while allowing necessary nutrients to pass.
Claudin-5 is encoded by the CLDN5 gene located on chromosome 22q11.21. It is a member of the claudin family of proteins that are the primary structural components of tight junctions. Tight junctions form a seal between adjacent endothelial cells in the blood-brain barrier, creating a physical barrier that controls the passage of ions, molecules, and cells between the blood and the brain [1].
The discovery that claudin-5 deficiency leads to increased BBB permeability to small molecules (<800 Da) demonstrated the critical role of this protein in maintaining BBB selectivity [2].
The CLDN5 gene consists of 4 exons and encodes a protein of 218 amino acids. The gene is expressed predominantly in endothelial cells of the brain and lung vasculature.
Claudin-5 is a transmembrane protein with:
Nitta et al., Size-selective loosening of the blood-brain barrier in claudin-5-deficient mice (2003). Journal of Cell Biology.
Wolburg et al., Tight junctions of the blood-brain barrier (2009). Neuroscience.
Sweeney et al., Blood-brain barrier breakdown in Alzheimer's disease (2019). Nature Reviews Neurology.
The study of Cldn5 — Claudin 5 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.
Nitta T, Hata M, Gotoh S, Seo Y, Sasaki H, Hashimoto N, Furuse M, Tsukita S. "Size-selective loosening of the blood-brain barrier in claudin-5-deficient mice." Journal of Cell Biology. 2003;161(3):653-660. DOI:10.1083/jcb.200207055
Wolburg H, Lippoldt A, Ebner B. "Tight junctions of the blood-brain barrier." Progress in Brain Research. 2009;176:39-47. DOI:10.1016/j.neuroscience.2009.02.008
Sweeney MD, Sagare AP, Zlokovic BV. "Blood-brain barrier breakdown in Alzheimer's disease and other neurodegenerative disorders." Nature Reviews Neurology. 2019;15(3):139-151. DOI:10.1038/s41582-019-0167-3