The multidrug transporter, P-glycoprotein, actively mediates cholesterol redistribution in the cell membrane
The multidrug transporter, P-glycoprotein, actively mediates cholesterol redistribution in the cell membrane
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DOI：
10.1073/pnas.162366399
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发表时间：
2002-08-06
影响因子：
11.1
通讯作者：
Orlowski, S
中科院分区：
文献类型：
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作者：
Garrigues, A;Escargueil, AE;Orlowski, S
P-糖蛋白(P-gp)是一种质膜三磷酸腺苷结合盒转运体，与肿瘤细胞的多药耐药有关。P-gp催化依赖于IS的ATP水解物流出大量化学结构无关的两亲性化合物。在没有任何已知底物的情况下，P-gp表现出明显无效的基础ATPase活性。通过使用含有大量P-gp的天然膜小泡，我们发现：(I)这种基础的ATPase活性与膜中胆固醇的存在密切相关；(Ii)P-gp转运的药物在没有胆固醇的情况下对P-gp ATPase活性的刺激高于在有胆固醇存在的情况下，相反，胆固醇对P-gp ATPase活性的刺激在没有P-gp底物的情况下比在有已知P-gp底物的情况下更高；(Iii)P-gp介导了胆固醇从细胞质小叶到质膜外质小叶的依赖于ATP的迁移；(4)已知的P-gp底物对胆固醇依赖的P-gp ATPase活性的降低与膜内依赖于ATP的胆固醇再分布的抑制有关。这些数据高度暗示了P-gp的基础ATPase活性与其膜内胆固醇重分配功能之间的偶联，并与P-gp可能主动地在膜上转运胆固醇的可能性完全一致。最后，这种P-gp介导的胆固醇在细胞膜上的重新分布使得P-gp可能有助于稳定富含胆固醇的微区、筏子和小窝，并参与细胞内胆固醇运输的调节。
P-glycoprotein (P-gp) is a plasma membrane ATP-binding cassette transporter, responsible for multidrug resistance in tumor cells. P-gp catalyzes the ATP hydrolys is-dependent efflux of numerous amphiphilic compounds of unrelated chemical structures. In the absence of any identified substrate, P-gp exhibits an apparently futile, basal ATPase activity. By using native membrane vesicles containing high amounts of P-gp, we show here that (i) this basal ATPase activity is tightly dependent on the presence of cholesterol in the membrane; (ii) the stimulation of P-gp ATPase activity by drugs transported by P-gp is higher in the absence than in the presence of cholesterol and, conversely, the stimulation of P-gp ATPase activity by cholesterol is higher in the absence than in the presence of known P-gp substrates; (iii) P-gp mediates the ATP-dependent relocation of cholesterol from the cytosolic leaflet to the exoplasmic leaflet of the plasma membrane; and (iv) the decrease of the cholesterol dependence of P-gp ATPase activity induced by known P-gp substrates is correlated with the inhibition of the ATP-dependent cholesterol redistribution within the membrane. These data are highly evocative of a coupling between the basal ATPase activity of P-gp and its intramembrane cholesterol-redistribution function, and they are fully consistent with the possibility that P-gp may actively translocate cholesterol in the membrane. Finally, this P-gp-mediated cholesterol redistribution in the cell membrane makes it likely that P-gp contributes in stabilizing the cholesterol-rich microdomains, rafts and caveolae, and that it is involved in the regulation of cholesterol trafficking in cells.