A possible role of lysophospholipids produced by calcium-independent phospholipase A₂ in membrane-raft budding and fission

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• 作者：Takanari Nakano ; Ikuo Inoue ; Rina Shinozaki ; Masanori Matsui ; Toshitaka Akatsuka ; Seiichiro Takahashi ; Kayoko Tanaka ; Masumi Akita ; Makoto Seo ; Shigeru Hokari ; Shigehiro Katayama ; Tsugikazu Komoda
• 关键词：Alkaline phosphatase ; Brush border ; Caco-2 ; Influenza virus ; MDCK ; Lysophosphatidylcholine
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2009
• 出版时间：October 2009
• 年：2009
• 卷：1788
• 期：10
• 页码：2222-2228
• 全文大小：671 K

文摘

Phospholipase A₂ (PLA₂) not only plays a role in the membrane vesiculation system but also mediates membrane-raft budding and fission in artificial giant liposomes. This study aimed to demonstrate the same effects in living cells. Differentiated Caco-2 cells were cultured on filter membranes. MDCK cells were challenged with Influenza virus. The MDCK cultures were harvested for virus titration with a plaque assay. Alkaline phosphatase (ALP), a membrane-raft associated glycosylphosphatidylinositol (GPI)-anchored protein, was 70 % released by adding 0.2 mmol/l lysophosphatidylcholine, which was abolished by treatment with a membrane-raft disrupter, methyl-β-cyclodextrin. Activation of calcium-independent PLA₂ (iPLA₂) by brefeldin A increased the apical release of ALP by approximately 1.5-fold (p < 0.01), which was blocked by PLA₂ inhibitor bromoenol lactone (BEL). BEL also reduced Influenza virus production into the media (< 10 % ) in the MDCK culture. These results suggest that cells utilize inverted corn-shaped lysophospholipids generated by PLA₂ to modulate plasma membrane structure and assist the budding of raft-associated plasma membrane particles, which virus utilizes for its budding. Brush borders are enriched with membrane-rafts and undergo rapid turnover; thus, PLA₂ may be involved in the regulatory mechanism in membrane dynamism. Further, iPLA₂ may provide a therapeutic target for viral infections.