Tangier disease is caused by mutations in ATP binding cassette transporter A1( ABCA1). ABCA1 interacts with lipid-free apolip oproteins, promoting phospholipid and cholesterol efflux from cells and giving r ise to HDL...Tangier disease is caused by mutations in ATP binding cassette transporter A1( ABCA1). ABCA1 interacts with lipid-free apolip oproteins, promoting phospholipid and cholesterol efflux from cells and giving r ise to HDL particles. ABCA1 may act as a phospholipid translocase facilitating p hospholipid binding to apoA-I. ABCA1 gene expression is upregulated in cholester ol-loaded cells as a result of activation of LXR/RXR-mediated gene transcription . LXR and RXR coordinately induce a battery of genes mediating cellular choleste rol efflux, centripetal cholesterol transport, and cholesterol excretion in bile . Small-molecule activators of LXR/RXR or other stimulators of macrophage or int estinal cholesterol efflux hold great promise as future treatments for atheroscl erosis.展开更多
目的检测三磷酸腺苷结合盒转运体A1(ABCA1)蛋白第2跨膜结构域(the second transmembrane domain,TMD2)中关键的抗砷结构域。方法采用重叠区扩增基因拼接法构建三磷酸腺苷结合盒转运体A1基因TMD2的一系列缺失突变体,分别转染至HeLa细胞,...目的检测三磷酸腺苷结合盒转运体A1(ABCA1)蛋白第2跨膜结构域(the second transmembrane domain,TMD2)中关键的抗砷结构域。方法采用重叠区扩增基因拼接法构建三磷酸腺苷结合盒转运体A1基因TMD2的一系列缺失突变体,分别转染至HeLa细胞,激光共聚焦观察其定位,Cell Counting Kit-8检测48 h急性砷中毒后生存率的变化,原子荧光吸收光谱法检测细胞内的总砷含量。结果激光共聚焦证实各突变体的编码蛋白均定位在HeLa细胞的细胞膜上。CCK-8结果显示,转染胞外第4、5环,胞内第4、5环缺失突变体的HeLa细胞IC50分别为33.18、32.84、33.45、34.29μmol.L-1,与转染野生型三磷酸腺苷结合盒转运体A1质粒的HeLa细胞(IC50为33.96μmol.L-1)无显著差异,均高于空载体转染对照组(IC50为19.01μmol.L-1)。转染胞外第6环缺失突变体HeLa细胞的IC50为19.95μmol.L-1,与空载体对照组无显著差异,显著低于野生型三磷酸腺苷结合盒转运体A1质粒转染组。原子荧光分光光度法结果显示,转染胞外第6环缺失三磷酸腺苷结合盒转运体A1的HeLa细胞内砷含量与转染空载体接近,而转染其他突变体的结果与转染野生型三磷酸腺苷结合盒转运体A1的结果基本一致。结论成功构建了5个三磷酸腺苷结合盒转运体A1蛋白第2跨膜结构域的缺失突变体,且其表达的蛋白仍然正确定位于HeLa细胞的细胞膜上。突变体(除胞外第6环外)仍然具有一定的抗砷性,提示三磷酸腺苷结合盒转运体A1胞外第6环可能是关键抗砷结构域。展开更多
文摘Tangier disease is caused by mutations in ATP binding cassette transporter A1( ABCA1). ABCA1 interacts with lipid-free apolip oproteins, promoting phospholipid and cholesterol efflux from cells and giving r ise to HDL particles. ABCA1 may act as a phospholipid translocase facilitating p hospholipid binding to apoA-I. ABCA1 gene expression is upregulated in cholester ol-loaded cells as a result of activation of LXR/RXR-mediated gene transcription . LXR and RXR coordinately induce a battery of genes mediating cellular choleste rol efflux, centripetal cholesterol transport, and cholesterol excretion in bile . Small-molecule activators of LXR/RXR or other stimulators of macrophage or int estinal cholesterol efflux hold great promise as future treatments for atheroscl erosis.