ApoA-I inhibits endothelial exocytosis via SR-BI.
(A) Reaction of albumin (lane 1) with maleic acid (lane 2) leads to maleylated albumin with enhanced electrophoretic mobility, shown by Coomassie staining. (B) Maleylated albumin relieves the inhibition of endothelial exocytosis by ApoA-I. (C) SR-BI Expression: HAEC lysate, lane 1; Human Embryonic Kidney (HEK) 293 cell lysate, lane 2; wild-type mouse liver lysate, lane 3 were analyzed by immunoblotting with an SR-BI antibody. The signal at 82 kDa is consistent with the molecular weight of SR-BI; the band at 60 kDa is consistent with the molecular weight of unglycosylated SR-BI (asterisk). (D) SR-BI blocking antibody. Endothelial cells were pre-treated with an SR-BI blocking antibody, followed by the addition of 10−4 mg/mL apoA-I for 2 h. Cells were washed, stimulated with thrombin 1 U/ml, and the amount of VWF released over 1 h was measured by an ELISA (n = 3 ± S.D. *P < 0.05, vs. 0 apoA-I and 0 SR-BI receptor antibody).
