Shiratsuchi A, Osada S, Kanazawa S, Nakanishi Y
Graduate School of Natural Science and Technology, Kanazawa University, Ishikawa, Japan.
Biochem Biophys Res Commun. 1998 May 19;246(2):549-55. doi: 10.1006/bbrc.1998.8663.
In many apoptotic cells, phosphatidylserine (PS), that is normally restricted to the inner membrane layer, is externalized and subsequently recognized by phagocytes. However, it has been unclear whether PS externalization is sufficient for phagocytosis induction. In a cultured cell line undergoing Fas-mediated apoptosis, PS externalization preceded other apoptotic events. When transbilayer movement of membrane phospholipids was analyzed, a decrease of the uptake of PS and phosphatidylethanolamine and an increase of phosphatidylcholine incorporation were observed upon apoptosis induction. Apoptotic cultured cells were phagocytosed by macrophages in a manner dependent on externalized PS before plasma membrane permeability increased. Moreover, a N-ethylmaleimide treatment caused PS externalization independent of apoptosis, and such cells underwent PS-mediated phagocytosis. These results suggested that PS is externalized as a result of membrane phospholipid redistribution and externalized PS by itself induces apoptosing cell phagocytosis.
在许多凋亡细胞中，通常局限于内膜层的磷脂酰丝氨酸（PS）会外化，随后被吞噬细胞识别。然而，PS外化是否足以诱导吞噬作用尚不清楚。在经历Fas介导凋亡的培养细胞系中，PS外化先于其他凋亡事件。当分析膜磷脂的跨膜运动时，在诱导凋亡后观察到PS和磷脂酰乙醇胺摄取减少，磷脂酰胆碱掺入增加。凋亡的培养细胞在质膜通透性增加之前，以依赖于外化PS的方式被巨噬细胞吞噬。此外，N-乙基马来酰亚胺处理导致与凋亡无关的PS外化，并且此类细胞经历PS介导的吞噬作用。这些结果表明，PS外化是膜磷脂重新分布的结果，外化的PS自身可诱导凋亡细胞的吞噬作用。
