Disease relevance of PLD2

• In our present study we investigated how PLD2 activity is regulated in mouse lymphocytic leukemia L1210 cells, which mainly contain PLD2, and in PLD2 -transfected COS-7 cells [1].
• We conclude that oleic acid is a selective activator of PLD2 and can be used for localization studies, but its use as an activator of PLD2 in intact cells to study function is limited due to toxicity [2].
• These results suggest that EWS-Fli1 may play a role in the regulation of tumor proliferation-signaling enzymes via PLD2 expression in Ewing sarcoma cells [3].
• Thus, this study was conducted to determine the activity and the expression of PLD2 in human colorectal cancer [4].
• As determined by reverse transcription polymerase chain reaction, both splicing variants of PLD1, PLD1a and PLD1b, and the isoenzyme PLD2, are expressed in melanoma cells and melanocytes [5].

High impact information on PLD2

• Previously, we reported that phospholipase D2 (PLD2) interacts with dynamin in a GTP-dependent manner [6].
• Disruption of the PH domain of mammalian PLD2 results in relocalization of the protein from the PI(4,5)P2-containing plasma membrane to endosomes [7].
• Binding of PLD2 to model membranes is enhanced by acidic phospholipids [7].
• We find that both PLD1 and PLD2 interact with the Type Ialpha PIPkinase and that PLD2 activity in vivo can be regulated solely by the expression of this lipid kinase [8].
• Gene expression silencing of the other mammalian isoform, PLD2, also led to cell migration arrest, whereas ENA-78 selectively increased endogenous PLD2 activity and chemotaxis of HL-60 cells overexpressing a myc-pcDNA-PLD2 construct [9].

Chemical compound and disease context of PLD2

• Since the expression of PLD2 significantly enhanced phorbol 12-myristate 13-acetate (PMA)- or bradykinin-induced PLD activity in rat pheochromocytoma PC12 cells, we investigated the regulatory mechanism of PLD2 in PC12 cells [10].

Biological context of PLD2

• Moreover, epidermal growth factor induced tyrosine phosphorylation of PLD2 and its interaction with c-Src in A431 cells [11].
• Together, these data suggest that PLD2 play a key role in the regulation of agonist-induced endocytosis of the mu-opioid receptor [12].
• These results show for the first time that transactivation of PDGF-R beta by LPA in HBEpCs is regulated by PLD2 [13].
• The deduced amino acid sequence shows 53 and 90% identity to hPLD1 and rodent PLD2, respectively [14].
• Taken together, the results suggest that PLD2 activity is specifically up-regulated by H(2)O(2) in PC12 cells and that it plays a suppressive role in H(2)O(2)-induced apoptosis [15].

Anatomical context of PLD2

• In contrast, overexpressed mouse PLD2 was observed to localize primarily to the plasma membrane, although internalization on membrane vesicles was observed subsequent to serum stimulation [16].
• Finally, alpha-actinin co-localizes with actin and with PLD2 in the detergent-insoluble fraction from sarcolemmal membranes [17].
• Intriguingly, A23187, a calcium ionophore that induces calcium influx, potently stimulates PLD activity in these two cell lines, suggesting that Ca2+ might be implicated in the regulation of the PLD2 activity [1].
• Examination of membranes prepared from COS-7, Jurkat and HL60 cells indicated a relationship between oleate-stimulated PLD2 activity and PLD2 immunoreactivity [2].
• Here we show that caveolin-rich fractions, prepared from HaCaT human keratinocytes by either detergent-based or detergent-free methods, contain PLD2 [18].

Associations of PLD2 with chemical compounds

• Conversely the inhibition of PLD2-mediated phosphatidic acid formation by 1-butanol or overexpression of a negative mutant of PLD2 prevented agonist-mediated endocytosis of MOR1 [12].
• The inhibitory effect of arachidonyl trifluoromethyl ketone on the A23187-induced PLD2 activity could be recovered by addition of exogenous lysophosphatidylcholine [1].
• Furthermore, heterologous stimulation of PLD2 by phorbol ester led to an accelerated internalization of the mu-opioid receptor after both DAMGO and morphine exposure [12].
• Mutation of this residue to phenylalanine enhanced basal activity almost 2-fold, but did not alter the magnitude of the EGF-mediated increase in PLD2 activity [19].
• Finally, studies conducted using overexpression of wild-type active or dominant-negative isoforms of PLD2 and RNA interference-mediated targeting of PLD2 suggest that PLD2 functions at the plasma membrane to facilitate endocytosis of the angiotensin II type 1 receptor [16].

Physical interactions of PLD2

• In this study, we have examined the properties of the PX domains of PLD1 and PLD2 in terms of phosphoinositide binding and PLD activity regulation [20].
• We also determined that the region between amino acids 613 and 723 of PLD2 is required for the direct binding of beta-actin, using bacterially expressed glutathione S-transferase fusion proteins of PLD2 fragments [21].
• PLD2 forms a functional complex with mTOR/raptor to transduce mitogenic signals [22].
• PLD2 co-immunoprecipitated with ERK1/2 and became phosphorylated on MAP kinase consensus sites in fMLP-stimulated cells [23].

Enzymatic interactions of PLD2

• In cell-free systems, ERK2 gave rise to strong ATP-dependent PLD activity and directly phosphorylated PLD2 that generated two phosphopeptides only after tryptic digestion [23].

Regulatory relationships of PLD2

• Cloning and initial characterization of a human phospholipase D2 (hPLD2). ADP-ribosylation factor regulates hPLD2 [14].
• Purified alpha-actinin potently inhibits PLD2 activity (IC(50) = 80 nm) in an interaction-dependent and ADP-ribosylation factor-reversible manner [17].
• In this report, we demonstrated that both PLD1 and PLD2 repressed expression of cyclin-dependent kinase inhibitor p21 gene in an additive manner [24].
• Intriguingly, purified beta-actin potently inhibited both phosphatidylinositol-4,5-bisphosphate- and oleate-dependent PLD2 activities in a concentration-dependent manner (IC50 = 5 nm) [21].
• Phospholipase D2-derived phosphatidic acid binds to and activates ribosomal p70 S6 kinase independently of mTOR [25].

Other interactions of PLD2

• Examples of other G protein-coupled receptors assessed in comparison display alternative pathways of protein kinase C- or ARF6-dependent activation of PLD2 [26].
• Finally, we provide evidence that PKC alpha is constitutively associated with PLD2 [27].
• Insulin-induced phospholipase D1 and phospholipase D2 activity in human embryonic kidney-293 cells mediated by the phospholipase C gamma and protein kinase C alpha signalling cascade [27].
• The direct association between PLD2 and alpha-actinin was confirmed using an in vitro binding assay and localized to PLD2's N-terminal 185 amino acids [17].
• We conclude that MDR is accompanied by an increase in PLD2 activity in DIGs and caveolar membranes [28].

Analytical, diagnostic and therapeutic context of PLD2

• Using subcellular fractionation and Western blot analysis, we found that PLD2 is the major myocardial PLD and that it localizes primarily to sarcolemmal membranes [17].
• Co-immunoprecipitation studies indicated an association between PLD2 and PKCalpha under basal conditions that was further enhanced by PMA [29].
• By in situ immunofluorescence or cell fractionation followed by immunoblotting, PLD1 was concentrated primarily in nuclei, whereas the membrane fraction contained PLD2 and PLD1 [30].
• RT-PCR analysis showed that both PLD1 and PLD2 isoforms are expressed in human neutrophils, with PLD1 expressed at a higher level [31].
• Antigen stimulation resulted in increased association and colocalization of Syk with PLD2 on the plasma membrane as indicated by coimmunoprecipitation and confocal microscopy [32].

References