Group IV Phospholipase A2α Controls the Formation of Inter-Cisternal Continuities Involved in Intra-Golgi Transport

Abstract

The enzyme phospholipase A2 (cPLA2α) is involved in the formation of intercisternal tubules that mediate transport of proteins within the Golgi complex.

Phospholipase A2IVα Regulates Phagocytosis Independent of Its Enzymatic Activity

“…In addition, in the IMLF Ϫ/Ϫ cells from the PLA 2 IV␣ knock-out mice, the PLA 2 IV␣ N-terminal C2 domain was identified as the portion of PLA 2 IV␣ that is sufficient to induce a rescue of impaired FcR-mediated phagocytosis. This is in agreement with previous studies, also from our laboratory, that have indicated the C2 domain as the minimal PLA 2 IV␣ portion that can still translocate to cell membranes following increases in intracellular Ca 2ϩ (18). Based on the data presented here, we speculate on a new mechanism of action of PLA 2 IV␣, whereby membrane insertion of the PLA 2 IV␣ C2 domain induces perturbation of the membrane phospholipid packing, potentially also generating the membrane bending that is necessary for phagosome formation (57).…”

“…Here, both phagocytosis-induced release of arachidonic acid and FcR-mediated phagocytosis were monitored. The PLA 2 IV␣ enzymatic activity was completely inhibited by this treatment (Table 1), whereas FcR-mediated phago- (1-525), and the point mutant GFP-PLA 2 IV␣-S228C have no catalytic activity, but they translocate to membranes under agonist stimulation (18,36,55). The point mutant GFP-PLA 2 IV␣-D43N cannot translocate to membranes under cell stimulation (12).…”

New Members of the Mammalian Glycerophosphodiester Phosphodiesterase Family

“…The intracellular localization of GDE4 was further examined by comparing the staining patterns in COS-7 cells with PLA 2 IV␣, which under these conditions showed a diffuse localization (cytosolic) as well as a perinuclear staining compatible with a Golgi localization (Fig. 3B), in agreement with the reported localization of this enzyme (25). The results showed that heterologous GDE4 partially co-localized with overexpressed PLA 2 IV␣, suggesting its prevalent Golgi localization (Fig.…”

How the Golgi works: A cisternal progenitor model

“…It is important to note that two stacks are not needed to accomplish such transport: because even ministack cisternae are discontinuous, such a fusion event could occur between cisternae within a ministack. In addition, this class of fusion may explain the tubules that have been detected in some laboratories to connect Golgi cisternae (4,5,30).…”