Localization and function of cytosolic phospholipase A2α at the Golgi

Cytosolic phospholipase A2α (cPLA2α, Group IVA phospholipase A2) is a central mediator of arachidonate release from cellular phospholipids for the biosynthesis of eicosanoids. cPLA2α translocates to intracellular membranes including the Golgi in response to a rise in intracellular calcium level. The enzyme’s calcium-dependent phospholipid-binding C2 domain provides the targeting specificity for cPLA2α translocation to the Golgi. However, other features of cPLA2α regulation are incompletely understood such as the role of phosphorylation of serine residues in the catalytic domain and the function of basic residues in the cPLA2α C2 and catalytic domains that are proposed to interact with anionic phospholipids in the membrane to which cPLA2α is targeted. Increasing evidence strongly suggests that cPLA2α plays a role in regulating Golgi structure, tubule formation and intra-Golgi transport. For example, recent data suggests that cPLA2α regulates the transport of tight junction and adherens junction proteins through the Golgi to cell–cell contacts in confluent endothelial cells. However, there are now examples where data based on knockdown using siRNA or pharmacological inhibition of enzymatic activity of cPLA2α affects fundamental cellular processes yet these phenotypes are not observed in cells from cPLA2α deficient mice. These results suggest that in some cases there may be compensation for the lack of cPLA2α. Thus, there is continued need for studies employing highly specific cPLA2α antagonists in addition to genetic deletion of cPLA2α in mice.