Changes in the function of angiotensin II type 1 receptor due to cholesterol depletion from cell membrane

Blockers of G-protein coupled receptors (GPCRs), angiotensin II (Ang II) type 1 (AT₁) receptor and β₁-adrenergic (Ad) receptor, have been shown to improve the prognosis of cardiovascular disease. Cholesterol molecules in the cell membrane are needed to stabilize GPCRs as well as the cell membrane itself. We determined whether the functions of AT₁ and β₁-Ad receptors were changed by cholesterol depletion from cardiovascular cell membranes. Ang II-induced inositol phosphate production through AT₁ receptor was suppressed by cholesterol depletion from cell membranes using rosuvastatin or methyl-β-cyclodextrin (MβCD), whereas isoproterenol-induced cyclic AMP production through β₁-Ad receptor did not change after cholesterol depletion. In addition, the binding affinities of Ang II and AT₁ receptor blocker after cholesterol depletion were significantly lower than those before depletion. Although AT₁ receptor expression levels did not change after cholesterol depletion, the expression levels of AT₁ receptor that could bind to Ang II significantly decreased after depletion. The changes in the structure of AT₁ receptor due to depletion were confirmed by substituted-cysteine accessibility mapping. In conclusion, Ang II-induced activation of AT₁ receptor is reduced without affecting the function of β₁-Ad receptor after cholesterol depletion from cardiovascular cell membranes.