Calmodulin Interacts With ATP Binding Cassette Transporter A1 to Protect From Calpain-Mediated Degradation and Upregulates High-Density Lipoprotein Generation
Calmodulin Interacts With ATP Binding Cassette Transporter A1 to Protect From Calpain-Mediated Degradation and Upregulates High-Density Lipoprotein Generation
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DOI：
10.1161/atvbaha.110.203927
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发表时间：
2010-07-01
影响因子：
8.7
通讯作者：
Yokoyama, Shinji
中科院分区：
文献类型：
--
作者：
Iwamoto, Noriyuki;Lu, Rui;Yokoyama, Shinji
研究ATP结合盒转运子A1（ABCA 1）与钙调素的相互作用及其与钙蛋白酶介导的钙蛋白酶降解的关系，因为许多钙蛋白酶底物结合钙调素来调节细胞功能.免疫沉淀和谷胱甘肽S-转移酶下拉试验表明，ABCA 1直接结合钙调素在钙离子依赖的方式。ABCA 1的胞质环包含1-5-8-14个基序（1245至1257个氨基酸）的典型钙调素结合序列。该区域的肽显示与钙调蛋白结合，并且1-5-8-14基序的缺失消除了这种相互作用。该基序位于ABCA 1 Pro-Glu-Ser-Thr序列附近，并且钙调蛋白/Ca 2+的存在保护肽免受钙蛋白酶的蛋白水解。通过特定的小干扰RNA敲低钙调素增加了ABCA 1的降解，并减少了ABCA 1蛋白和载脂蛋白A-I介导的脂质释放。令人惊讶的是，钙调蛋白抑制剂W7增加钙调蛋白结合ABCA 1和保护它从钙蛋白酶介导的降解，与我们以前的发现，这种化合物增加载脂蛋白A-I介导的细胞cholesterol release. Conclusion钙调蛋白直接结合和稳定ABCA 1中存在的Ca 2+和增加高密度脂蛋白的产生。（Arterioscler Thromb Vasc Biol.2010; 30：1446-1452.）
Objective-To investigate the interaction of ATP-binding cassette transporter A1 (ABCA1) with calmodulin in relation to its calpain-mediated degradation because many calpain substrates bind calmodulin to regulate cellular functions.Methods and Results-The activity of ABCA1 is regulated through proteolysis by calpain. An immunoprecipitation and glutathione S-transferase pull-down assay revealed that ABCA1 directly binds calmodulin in a Ca2+-dependent manner. The cytoplasmic loop of ABCA1 contains a typical calmodulin binding sequence of 1-5-8-14 motifs (1245 to 1257 amino acids). The peptide of this region showed binding to calmodulin, and deletion of the 1-5-8-14 motif abolished this interaction. This motif is located near the ABCA1 Pro-Glu-Ser-Thr sequence, and the presence of calmodulin/Ca2+ protected the peptides from proteolysis by calpain. The knockdown of calmodulin by a specific small and interfering RNA increased the degradation of ABCA1 and decreased ABCA1 protein and apolipoprotein A-I-mediated lipid release. Surprisingly, calmodulin inhibitor W7 increased calmodulin binding to ABCA1 and protected it from calpain-mediated degradation, consistent with our previous finding that this compound increased apolipoprotein A-I-mediated cell cholesterol release.Conclusion-Calmodulin directly binds and stabilizes ABCA1 in the presence of Ca2+ and increases the generation of high-density lipoprotein. (Arterioscler Thromb Vasc Biol. 2010; 30: 1446-1452.)