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Mechanism of Cellular Cholesterol Release

细胞胆固醇释放机制

基本信息

批准号：
12671120
负责人：
ABE Sumiko
金额：
$ 2.18万
依托单位：
Nagoya City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12671120/
关键词：
HDL cholesterol ABCA1 apolipoprotein apolipoprotein cholesterol ABCAl

项目摘要

Various kinds of cell line cells were investigated for their response to lipid-free apolipoproteins to analyze the mechanism of apolipoprotein-mediated HDL generation.After preincubation of RAW 264, a murine monocytic leukemia cell line, with dBcAMP induced specific binding of apolipoprotein AI (apo A-I) to the cells and apoA-I-mediated HDL formation with cellular lipids, neither of which was detected in the absence of dBcAMP. Abca1 mRNA and protein were both detected in the dBcAMP-untreated cells, and the dBcAMP treatment enhanced their expression about 10 fold. The pharmacological inhibitory profile for lipid efflux by the compounds reported as inhibitors of anion transport mediated by ABCA1 protein was different from that for anion transport.HDL was formed by interaction with apoA-I and THP・1, a human monocytic leukemia cell line. However, cholesterol incorporation into HDL was only observed after differentiation of the cells by PMA. ABCA1 mRNA and protein were almost undetectable in undifferentiated cells but induced by PMA treatment.Neither ABCA1 expression nor apoA-I-mediated lipid release was detected in 293 cells derived from human embryonic kidney. Specific binding of apo A-I was detected in stable transformants of 293 with ABCA1 cDNA. ApoA-I-mediated phospholipid release was observed in the cells with low and high level ABCA1 expression. Cholesterol release was only detected in the cells with high level ABCA1.These data indicated that ABCA1 protein may be essential, but not sufficient for cholesterol assembly to HDL generated by apolipoproteins.

用dBcAMP预孵育小鼠单核细胞白血病细胞系RAW 264，观察不同细胞系对无脂载脂蛋白的反应，分析载脂蛋白介导的HDL生成机制，发现载脂蛋白AI（apoA-I）与细胞特异性结合，apoA-I介导的HDL与细胞脂质的生成，而在无dBcAMP的情况下均未检测到。在未处理的细胞中检测到Abca 1 mRNA和蛋白，并且dBcAMP处理使其表达增强约10倍。已报道的ABCA 1蛋白介导的阴离子转运抑制剂对脂质流出的药理学抑制作用不同于对阴离子转运的抑制作用。HDL是通过与apoA-I和人单核细胞白血病细胞系THP·1相互作用而形成的。然而，胆固醇掺入HDL后，才观察到分化的细胞PMA。未分化细胞中几乎检测不到ABCA 1 mRNA和蛋白的表达，但PMA可诱导ABCA 1的表达，而293人胚肾细胞中既未检测到ABCA 1的表达，也未检测到apoA-I介导的脂质释放。在293个稳定的ABCA 1 cDNA转化子中检测到apo A-I的特异性结合。在ABCA 1低表达和高表达的细胞中观察到ApoA-I介导的磷脂释放。这些结果表明，ABCA 1蛋白可能是胆固醇组装成HDL所必需的，但不足以使胆固醇组装成HDL。