Cell-cell junctions · USMLE Step 1

If a toxin disrupts claudin and occludin interactions in the epithelium, which consequence is most likely?

  1. Loss of direct cytoplasmic communication between cells
  2. Failure of cell-to-matrix anchoring at the basement membrane
  3. Increased paracellular permeability and barrier failure
  4. Loss of intermediate filament network integrity
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Correct answer: Increased paracellular permeability and barrier failure

Claudin and occludin are core components of tight junctions; disruption leads to failure of the occluding seal, increasing paracellular permeability and compromising the barrier function of the epithelium.

Difficulty: Medium Question 9 of 20

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