Abstract 546: SR-BI Functions on Plasma HDL Homeostasis -low Plasma preβHDL Level in SR-BI Null Mice by 2D PAGE Analysis
ApoA-I-ABCA1 mediated HDL synthesis is major source of plasma preβHDL generation. Lipid free apoA-I is mainly provided from newly synthesized from liver, small intestinal cells and the other hand, apoA-I is also provided from deflated HDL result of transferring cholesterylester into target cells via SR-BI. To evaluate the contribution of SR-BI on reverse cholesterol transport at plasma preβHDL synthesis, first, plasma from SR-BI null mice and wild type mice were analyzed by 2D-gel and compared. The anti-mouse apoA-I peptide (134-140AA, N-Asp-Val-Glu-Leu-Tyr-Arg-Gln-C) polyclonal antibody were further purified by mouse apoA-I-Sepharose then used for detection of HDL subclasses developed by 2D-gel, combination of agarose gel and native gradient PAGE. Ten μL of tail blood from each mouse were collected into microtubes containing NEM, EDTA and ascorbic acid. Plasma was kept in ice then the first electrophoresis by PALAGON LIPO gel was performed within 3 hours of harvest of blood. PreβHDL in SR-BI null mice was significantly reduced (13.78±3.58 μg protein/mL plasma, P=0.00153). The other hand, preβHDL of ABCG1 null mice (37.46±13.803, P=0.423) was the same as in wild type mice plasma (38.48±13.58). To detect the origin of apoA-I on this preβHDL, 125I labeled apoA-I HDL injection of apoA-I on plasma preβHDL, 2D gel analyses were performed followed by 125I-apoA-I-HDL injection. 125I-preβHDL spot was detected early as 2 hours to 6 hours in wild type mice plasma, indicating apoA-I recycling to the new preβHDL particle. The other hand in SR-BI null mice plasma, the 125I-preβHDL spot was only detected between 6 hours to 24 hours. The loss of SR-BI protein delayed reproduction of preβHDL in plasma in mice. This result indicates SR-BI functions as provider of preβHDL possibly both free apoA-I for ABCA1 mediated preβHDL synthesis and also directly supply preβHDL particles in mice plasma.
Author Disclosures: M. Tsujita: None. T. Yokota: None. N. Akita: None. Y. Maekawa: None. J. Yamamoto: None. A.T. Remaley: None. S. Yokoyama: None.
- © 2015 by American Heart Association, Inc.