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Neurons and ECM regulate occludin localization in brain endothelial cells
G Savettieri1, I Di Liegro, C Catania
1Istituto di Neuropsichiatria, Policlinico Universitario Paolo Giaccone, Palermo, Italy.
Neuroreport
|May 3, 2000
Summary
Extracellular matrix and neurons influence occludin expression in brain endothelial cells. Collagen IV and neurons are crucial for occludin accumulation and localization in tight junctions.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Occludin is a key component of endothelial tight junctions, crucial for the blood-brain barrier.
- The regulation of occludin expression by extracellular matrix (ECM) and neuronal interactions is not fully understood.
Purpose of the Study:
- To investigate how ECM proteins and cortical neurons modulate occludin expression in rat brain endothelial cells (RBE4.B).
- To determine the specific roles of collagen IV and laminin in occludin regulation.
Main Methods:
- RBE4.B cells were cultured on different ECM proteins (collagen I, collagen IV, laminin) and in co-culture systems with cortical neurons.
- Occludin mRNA and protein levels were analyzed using molecular biology techniques.
- Immunofluorescence microscopy was used to assess occludin localization.
Main Results:
- Collagen IV significantly stimulated occludin mRNA expression in RBE4.B cells.
- Occludin protein accumulation required co-culture with cortical neurons on laminin-coated inserts alongside collagen IV.
- Occludin localized to the cell periphery only after co-culture with neurons for at least one week.
Conclusions:
- Both ECM composition and neuronal signaling are critical for regulating occludin expression and localization in brain endothelial cells.
- The combined presence of collagen IV and neurons is necessary for functional tight junction formation involving occludin.
- This study provides insights into the intricate mechanisms maintaining blood-brain barrier integrity.