Claudin-5 Protein
Protein Name	Claudin-5 Protein
Gene	[CLDN5](/genes/cldn5)
UniProt ID	O00511
Molecular Weight	21.8 kDa
Subcellular Localization	Tight junctions of brain endothelial cells
Protein Family	Claudin family
Associated Diseases	ALS, Als, Brain Arteriovenous Malformations, Depression, Inflammation
KG Connections	174 edges

Claudin-5 Protein

Introduction

Claudin 5 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

Claudin-5 is a tight junction protein that forms the paracellular barrier of the blood-brain barrier. It is essential for maintaining BBB integrity and preventing leakage of harmful substances into the brain [1].

Structure

Claudin-5 is a 218 amino acid protein with:

• Four transmembrane domains

• Two extracellular loops: The first extracellular loop determines charge selectivity

• Cytoplasmic N- and C-termini: The C-terminus interacts with PDZ domain proteins including ZO-1, ZO-2, and ZO-3

Domain Architecture

    N-terminus
    |
TM1-EC1-TM2-EC2-TM3-TM4
                                        |
                                        C-terminus (PDZ-binding motif)

Normal Function

Blood-Brain Barrier

Claudin-5 is essential for blood-brain barrier function:

1. Barrier Formation: Polymerizes into tight junction strands

2. Paracellular Transport: Controls passage of ions and small molecules

3. Selectivity: Provides size and charge selectivity

Tight Junction Assembly

• Forms homotypic and heterotypic interactions with other claudins

• Interacts with scaffolding proteins (ZO-1, ZO-2)

• Links to actin cytoskeleton

Role in Neurodegeneration

Alzheimer’s Disease

• Claudin-5 expression is altered in AD brains

• BBB breakdown correlates with cognitive decline

• Amyloid-beta can disrupt tight junctions [2]

• Therapeutic targeting may improve drug delivery

Parkinson’s Disease

• Contributes to neuroinflammation by allowing peripheral immune cell entry

• May affect alpha-synuclein clearance

• Relevant for understanding treatment resistance

Stroke

• Critical in acute BBB breakdown post-stroke

• Target for stroke treatment strategies

• Post-stroke repair involves claudin-5 restoration

Multiple Sclerosis

• Claudin-5 is downregulated in active MS lesions

• Contributes to immune cell infiltration

• Potential therapeutic target

Therapeutic Implications

Drug Delivery

• Targeting claudin-5 can enhance drug delivery to the brain

• Transient opening of BBB for drug delivery

• Focused ultrasound can modulate tight junctions

Biomarkers

• Claudin-5 levels in blood may serve as BBB integrity markers

• CSF/serum ratio indicates BBB damage

Gene Therapy

• Potential for restoring BBB function

• Viral vector delivery to endothelial cells

Key Publications

1. Nitta et al., Claudin-5 and BBB integrity (2003). Journal of Cell Biology.

2. Wolburg et al., Tight junctions of the blood-brain barrier (2009). Neuroscience.

3. Sweeney et al., Blood-brain barrier breakdown in Alzheimer’s disease (2019). Nature Reviews Neurology.

Background

The study of Claudin 5 Protein 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.

External Links

• UniProt: https://www.uniprot.org/uniprot/O00511

• AlphaFold: https://alphafold.ebi.ac.uk/entry/O00511

• Human Protein Atlas: https://www.proteinatlas.org/ENSG00000184113-CLDN5

See Also

• Blood-Brain Barrier

• Neurovascular Unit CLDN5 Gene

• Occludin Protein

• Alzheimer’s Disease

• Parkinson’s Disease

• Proteins Index

• Genes Index