Alterations in cell cholesterol content modulate Ca(2+)-induced tight junction assembly by MDCK cells

Area of Science:

• Cell Biology
• Biochemistry
• Epithelial Physiology

Background:

• Transepithelial electrical resistance (TER) measures tight junction (TJ) barrier function.
• Lovastatin (lova) accelerates TER development by reducing cholesterol (CH).
• The precise mechanism of lova's effect on TER, considering prenyl group precursors, requires further investigation.

Purpose of the Study:

• To investigate the role of cholesterol in epithelial barrier function.
• To examine the effects of agents that lower CH and alter CH biosynthesis on TER.
• To elucidate the relationship between cholesterol levels and TJ development.

Main Methods:

• Utilized MDCK cells to study TER development.
• Employed Lovastatin (lova), Zaragozic acid, and methyl beta-cyclodextrin (MBCD) to manipulate cellular cholesterol levels and CH biosynthesis.
• Measured TER, cellular CH content, and [3H]acetate incorporation into CH.

Main Results:

• Zaragozic acid and MBCD mimicked lova's effect by accelerating TER development, despite different impacts on CH biosynthesis and efflux.
• Reducing cellular CH with MBCD enhanced TER, while increasing CH content diminished TER development.
• Supplementation with CH reversed the effect of lova on TER, indicating CH's direct role.

Conclusions:

• Cholesterol levels directly modulate the development of the epithelial tight junction barrier.
• Lowering cellular cholesterol accelerates the formation of a functional epithelial barrier.
• These findings highlight cholesterol as a critical regulator of TJ barrier function.