The ectodomain of the Notch3 receptor accumulates within the cerebrovasculature of CADASIL patients

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Cerebral autosomal dominant adult onset arteriopathy (CADASIL) is a human genetic disorder causing stroke and dementia.
• CADASIL is linked to mutations in the Notch3 receptor, affecting vascular smooth muscle cells and causing granular deposits.
• Notch3 mutations often involve an odd number of cysteine residues in the extracellular domain, potentially impacting receptor processing, trafficking, or oligomerization.

Purpose of the Study:

• To investigate Notch3 expression patterns in normal tissues.
• To determine the consequences of Notch3 mutations on Notch3 expression in both transfected cells and CADASIL patient brains.

Main Methods:

• Examined Notch3 expression in normal tissues.
• Analyzed Notch3 expression in transfected cells and CADASIL brains.
• Investigated Notch3 proteolytic cleavage products.

Main Results:

• Notch3 is normally restricted to vascular smooth muscle cells.
• Notch3 undergoes proteolytic cleavage into extracellular (210-kDa) and intracellular (97-kDa) fragments.
• CADASIL brains exhibit significant accumulation of the 210-kDa Notch3 extracellular fragment at the cell membrane.

Conclusions:

• CADASIL mutations specifically hinder the clearance of the Notch3 extracellular domain from the cell surface.
• The intracellular domain's clearance is not affected.
• This impaired ectodomain clearance is a key mechanism in CADASIL pathogenesis.