Interaction of the Type Ialpha PIPkinase with phospholipase D: a role for the local generation of phosphatidylinositol 4,5-bisphosphate in the regulation of PLD2 activity

Abstract

Phosphoinositides are localized in various intracellular compartments and can regulate a number of intracellular functions, such as cytoskeletal dynamics and membrane traf®cking. Phospholipase Ds (PLDs) are regulated enzymes that hydrolyse phosphatidylcholine (PtdCho) to generate the putative second messenger phosphatidic acid (PtdOH). In vitro, PLDs have an absolute requirement for higher phosphorylated inositides, such as phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P 2 ]. Whether this lipid is able to regulate the activity of PLD in vivo is contentious. To examine this hypothesis we studied the relationship between PLD and an enzyme critical for the intracellular synthesis of PtdIns(4,5)P 2 : phosphatidylinositol 4-phosphate 5-kinase a (Type Ia PIPkinase). We ®nd that both PLD1 and PLD2 interact with the Type Ia PIPkinase and that PLD2 activity in vivo can be regulated solely by the expression of this lipid kinase. Moreover, PLD2 is able to recruit the Type Ia PIPkinase to its intracellular location. We show that the physiological requirement of PLD enzymes for PtdIns(4,5)P 2 is critical and that PLD2 activity can be regulated solely by the levels of this key intracellular lipid.

Phosphatidic acid regulates the affinity of the murine phosphatidylinositol 4‐phosphate 5‐kinase‐Iβ for phosphatidylinositol‐4‐phosphate

“…This conclusion is supported by evidence of an interdependent relationship between PA production by phospholipase D isoforms and PI(4,5)P2 production by the type I PIP5Ks in the regulation of endocytosis and in response to the small G-protein ARF6 [Arneson et al, 1999;Divecha et al, 2000]. Since, type I PIP5K activity is stimulated by PA and PI(4,5)P2 activates phospholipase D, a positive feedback loop is potentially formed between these enzyme families.…”

“…The observation that ARF GTPases regulate both phospholipase D enzymes and PIP5Ks together with evidence that PA and PI(4,5)P2 regulate overlapping cellular functions suggests that an intimate connection exists between these enzyme families [Honda et al, 1999;Brown et al, 2001;Skippen et al, 2002]. Consistent with this notion, PIP5K-Ia directly associates with both phospholipase D1 and phospholipase D2 and recruits phospholipase D2 to intracellular vesicles [Divecha et al, 2000]. Additionally, ARF1 mutants that fail to bind phospholipase D do not enhance PI(4,5)P2 production in vivo as effectively as wildtype ARF1 [Skippen et al, 2002].…”

“…While PA stimulation of the type I PIP5Ks has been shown in vitro and in vivo [Moritz et al, 1992;Jenkins et al, 1994;Divecha et al, 2000], the mechanism by which PA stimulates the type I PIP5Ks has not been studied. In vitro stimulation of type I PIP5K kinase activity together with the evidence presented above support the hypothesis that mPIP5K-Ib is activated by the direct binding of PA to the enzyme.…”

Effects of Active and Inactive Phospholipase D2 on Signal Transduction, Adhesion, Migration, Invasion, and Metastasis in EL4 Lymphoma Cells

“…For example, PA can reportedly promote the membrane association and activation of Raf-1, member of the Erk mitogen-activated protein kinase cascade (Ghosh et al, 1996). Other reported protein targets of PA are phosphatidylinositol 5-kinase (Divecha et al, 2000), NADPH oxidase (Palicz et al, 2001), mTOR (Fang et al, 2001), Pak1 (Symons, 2000), and sphingosine kinase 1 (Delon et al, 2004). In addition, PA is rapidly metabolized to other lipids with biological activity.…”

PLD2 (phospholipase D2)

“…Most studies have found PLD2 is mainly localized in the plasma membrane (Du et al, 2004) and that PLD1 is primarily localized in specialized vesicles, such as, endoplasmic reticulum (ER), Golgi apparatus, secretory vesicles, endosomes, and lysosomes (Brown et al, 1998;Freyberg et al, 2001), and several reports indicate that PLD2 is also localized in cytoplasmic vesicles (Divecha et al, 2000). In addition, PLD2 can be translocated into the submembranous vesicles by serum and ruffling membranes by epidermal growth factor (EGF) (Colley et al, 1997;Honda et al, 1999).…”