Systematic evaluation of transcellular activities of secretory phospholipases A2. High activity of group V phospholipases A2 to induce eicosanoid biosynthesis in neighboring inflammatory cells.
The mechanisms by which secretory phospholipase A2 (PLA2) exerts cellular effects are not fully understood. To elucidate these mechanisms, we systematically and quantitatively assessed the activities of human group IIA, V, and X PLA2s on originating and neighboring cells using orthogonal fluorogenic substrates in various mixed cell systems. When HEK293 cells stably expressing each of these PLA2s were mixed with non-transfected HEK293 cells, group V and X PLA2s showed strong transcellular lipolytic activity, whereas group IIA PLA2 exhibited much lower transcellular activity. The transcellular activity of group V PLA2 was highly dependent on the presence of cell surface heparan sulfate proteoglycans of acceptor cells. Activation of RBL-2H3 and DLD-1 cells that express endogenous group V PLA2 led to the secretion of group V PLA2 and its transcellular action on neighboring human neutrophils and eosinophils, respectively. Similarly, activation of human bronchial epithelial cells, BEAS-2B, caused large increases in arachidonic acid and leukotriene C4 release from neighboring human eosinophils. Collectively, these studies show that group V and X PLA2s can act transcellularly on mammalian cells and suggest that group V PLA2 released from neighboring cells may function in triggering the activation of inflammatory cells under physiological conditions.
Department of Chemistry, University of Illinois, Chicago, Illinois 60607, USA.
Gihani T
GT
Wijewickrama
Jin-Hahn
JH
Kim
Young Jun
YJ
Kim
Alexandra
A
Abraham
YounSang
Y
Oh
Bharath
B
Ananthanarayanan
Mark
M
Kwatia
Steven J
SJ
Ackerman
Wonhwa
W
Cho
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D015777:Eicosanoids / Q000378:metabolism*; D004804:Eosinophils / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D054501:Group II Phospholipases A2; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D019763:Heparin Lyase / Q000378:metabolism; D006801:Humans; D007249:Inflammation; D017997:Leukotriene C4 / Q000378:metabolism; D018613:Microscopy, Confocal; D008956:Models, Chemical; D009504:Neutrophils / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism* / Q000502:physiology*; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism; D020033:Protein Isoforms; D051381:Rats; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014162:Transfection
D018076:DNA, Complementary; D015777:Eicosanoids; D019812:Heparan Sulfate Proteoglycans; D010743:Phospholipids; D020033:Protein Isoforms; D016718:Arachidonic Acid; D017997:Leukotriene C4; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; D019763:Heparin Lyase