A possible role of lysophospholipids produced by calcium-independent phospholipase A(2) in membrane-raft budding and fission.
Phospholipase A(2) (PLA(2)) 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-beta-cyclodextrin. Activation of calcium-independent PLA(2) (iPLA(2)) by brefeldin A increased the apical release of ALP by approximately 1.5-fold (p<0.01), which was blocked by PLA(2) 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 PLA(2) 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, PLA(2) may be involved in the regulatory mechanism in membrane dynamism. Further, iPLA(2) may provide a therapeutic target for viral infections.
Nakano
Takanari
T
Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama 350-0455, Japan. nk.takanari@gmail.com
Inoue
Ikuo
I
Shinozaki
Rina
R
Matsui
Masanori
M
Akatsuka
Toshitaka
T
Takahashi
Seiichiro
S
Tanaka
Kayoko
K
Akita
Masumi
M
Seo
Makoto
M
Hokari
Shigeru
S
Katayama
Shigehiro
S
Komoda
Tsugikazu
T
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane; D002478:Cells, Cultured / Q000821:virology; D004285:Dogs; D006801:Humans; D008246:Lysophospholipids / Q000737:chemistry* / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D009975:Orthomyxoviridae / Q000502:physiology; D054467:Phospholipases A2 / Q000737:chemistry* / Q000378:metabolism; D019065:Virus Assembly; D014779:Virus Replication / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000494:pharmacology
D008246:Lysophospholipids; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D054467:Phospholipases A2; D000469:Alkaline Phosphatase; D002118:Calcium