Ishii Hidenari, Mori Tomoe, Shiratsuchi Akiko, Nakai Yuji, Shimada Yukiko, Ohno-Iwashita Yoshiko, Nakanishi Yoshinobu
Graduate School of Medical Science, Kanazawa University, Shizenken, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.
Biochem Biophys Res Commun. 2005 Feb 4;327(1):94-9. doi: 10.1016/j.bbrc.2004.11.135.
Externalization of phosphatidylserine (PS) takes place in apoptotic cells as well as in viable cells under certain circumstances. Recent studies showed that externalized PS is localized at the lipid raft in viable activated immune cells. We found that lipid rafts and PS existed in a mutually exclusive manner in apoptotic cells. The number of PS-exposing apoptotic cells decreased when lipid rafts were disrupted. BCtheta;, which binds selectively to cholesterol in a cholesterol-rich region, did not effectively recognize lipid rafts of apoptotic cells. Lipid rafts rich in GM1 were successfully prepared from apoptotic cells, but the lipid raft protein LAT was not enriched in the preparation. Furthermore, the amount of PS and phosphatidylethanolamine but not of cholesterol in lipid rafts appeared to change after induction of apoptosis. These results suggest that lipid rafts are structurally modified during apoptosis and, despite being localized differently from PS, are involved in the externalization of PS.
磷脂酰丝氨酸（PS）外化不仅发生在凋亡细胞中，在某些情况下也会发生在活细胞中。最近的研究表明，外化的PS定位于存活的活化免疫细胞的脂筏中。我们发现，脂筏和PS在凋亡细胞中以互斥的方式存在。当脂筏被破坏时，暴露PS的凋亡细胞数量减少。BCtheta;，它在富含胆固醇的区域选择性地结合胆固醇，不能有效地识别凋亡细胞的脂筏。从凋亡细胞中成功制备了富含GM1的脂筏，但脂筏蛋白LAT在制备物中未富集。此外，凋亡诱导后，脂筏中PS和磷脂酰乙醇胺的量似乎发生了变化，但胆固醇的量没有变化。这些结果表明，脂筏在凋亡过程中发生了结构修饰，尽管其定位与PS不同，但参与了PS的外化过程。
