TY - JOUR
T1 - Class A scavenger receptor-mediated macrophage adhesion requires coupling of calcium-independent phospholipase A2 and 12/15-lipoxygenase to Rac and Cdc42 activation
AU - Nikolic, Dejan M.
AU - Gong, Ming C.
AU - Turk, John
AU - Post, Steven R.
PY - 2007/11/16
Y1 - 2007/11/16
N2 - Class A scavenger receptors (SR-A) participate in multiple macrophage functions including adhesion to modified extracellular matrix proteins present in various inflammatory disorders such as atherosclerosis and diabetes. By mediating macrophage adhesion to modified proteins and increasing macrophage retention, SR-A may contribute to the inflammatory process. Eicosanoids produced after phospholipase A2 (PLA2)-catalyzed release of arachidonic acid (AA) are important regulators of macrophage function and inflammatory responses. The potential roles of AA release and metabolism in SR-A-mediated macrophage adhesion were determined using macrophages adherent to modified protein. SR-A-dependent macrophage adhesion was abolished by selectively inhibiting calcium-independent PLA2 (iPLA2) activity and absent in macrophages isolated from iPLA2β -/- mice. Our results further demonstrate that 12/15-lipoxygenase (12/15-LOX)-derived, but not cyclooxygenase- or cytochrome P450-dependent epoxygenase-derived AA metabolites, are specifically required for SR-A-dependent adhesion. Because of their role in regulating actin polymerization and cell adhesion, Rac and Cdc42 activation were also examined and shown to be increased via an iPLA2- and LOX-dependent pathway. Together, our results identify a novel role for iPLA2-catalyzed AA release and its metabolism by 12/15-LOX in coupling SR-A-mediated macrophage adhesion to Rac and Cdc42 activation.
AB - Class A scavenger receptors (SR-A) participate in multiple macrophage functions including adhesion to modified extracellular matrix proteins present in various inflammatory disorders such as atherosclerosis and diabetes. By mediating macrophage adhesion to modified proteins and increasing macrophage retention, SR-A may contribute to the inflammatory process. Eicosanoids produced after phospholipase A2 (PLA2)-catalyzed release of arachidonic acid (AA) are important regulators of macrophage function and inflammatory responses. The potential roles of AA release and metabolism in SR-A-mediated macrophage adhesion were determined using macrophages adherent to modified protein. SR-A-dependent macrophage adhesion was abolished by selectively inhibiting calcium-independent PLA2 (iPLA2) activity and absent in macrophages isolated from iPLA2β -/- mice. Our results further demonstrate that 12/15-lipoxygenase (12/15-LOX)-derived, but not cyclooxygenase- or cytochrome P450-dependent epoxygenase-derived AA metabolites, are specifically required for SR-A-dependent adhesion. Because of their role in regulating actin polymerization and cell adhesion, Rac and Cdc42 activation were also examined and shown to be increased via an iPLA2- and LOX-dependent pathway. Together, our results identify a novel role for iPLA2-catalyzed AA release and its metabolism by 12/15-LOX in coupling SR-A-mediated macrophage adhesion to Rac and Cdc42 activation.
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U2 - 10.1074/jbc.M704133200
DO - 10.1074/jbc.M704133200
M3 - Article
C2 - 17873277
AN - SCOPUS:36348990292
SN - 0021-9258
VL - 282
SP - 33405
EP - 33411
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 46
ER -