Munc-18-1 Inhibits Phospholipase D Activity by Direct Interaction in an Epidermal Growth Factor-reversible Manner

Lee, Hye Young; Park, Jong Bae; Jang, Il Ho; Chae, Young Chan; Kim, Jong Hyun; Kim, Il Shin; Suh, Pann‐Ghill; Ryu, Sung Ho

doi:10.1074/jbc.m310976200

Cited by 35 publications

(35 citation statements)

References 68 publications

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“…However, the roles of these inhibitors in signal-dependent PLD activity has not been demonstrated. Recently our group reported that Munc-18-1 directly inhibits PLD activity (53). In this report, epidermal growth factor treatment was found to trigger the dissociation of Munc-18-1 from PLD, and the inhibitory role of Munc-18-1 upon basal PLD activity, in a signaldependent manner, was suggested.…”

Section: Figmentioning

confidence: 69%

Inhibition of Muscarinic Receptor-linked Phospholipase D Activation by Association with Tubulin

Chae

Lee

et al. 2005

Journal of Biological Chemistry

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Mammalian phospholipase D (PLD) is considered a key enzyme in the transmission signals from various receptors including muscarinic receptors. PLD activation is a rapid and transient process, but a negative regulator has not been found that inhibits signal-dependent PLD activation. Here, for the first time, we report that tubulin binding to PLD 2 is an inhibition mechanism for muscarinic receptor-linked PLD 2 activation. Tubulin was identified in an immunoprecipitated PLD 2 complex from COS-7 cells by peptide mass fingerprinting. The direct interaction between PLD 2 and tubulin was found to be mediated by a specific region of PLD 2 (amino acids 476 -612). PLD 2 was potently inhibited (IC 50 <10 nM) by tubulin binding in vitro. In cells, the interaction between PLD 2 and tubulin was increased by the microtubule disrupting agent nocodazole and reduced by the microtubule stabilizing agent Taxol. Moreover, PLD 2 activity was found to be inversely correlated with the level of monomeric tubulin. In addition, we found that interaction with and the inhibition of PLD 2 by monomeric tubulin is important for the muscarinic receptor-linked PLD signaling pathway. Interaction between PLD 2 and tubulin was increased only after 1-2 min of carbachol stimulation when carbachol-stimulated PLD 2 activity was decreased. The expression of the tubulin binding region of PLD 2 blocked the later decrease in carbachol-induced PLD activity by masking tubulin binding. Taken together, these results indicate that an increase in local membrane monomeric tubulin concentration inhibits PLD 2 activity, and provides a novel mechanism for the inhibition of muscarinic receptor-induced PLD 2 activation by interaction with tubulin. Mammalian phospholipase D (PLD)1 hydrolyzes membrane phosphatidylcholine to generate phosphatidic acid and choline. PLD activity is dramatically activated in response to a variety of signals, including hormones, neurotransmitters, and growth factors (1). PLD products, phosphatidic acid itself or the hydrolyzed product diacylglycerol, have been known to act as intracellular lipid second messengers and to be involved in multiple physiological events, such as, the promotion of mitogenesis, stimulation of respiratory bursts, secretory processes, and actin cytoskeletal reorganization (2-7). Therefore, signal-dependent PLD activity must be tightly controlled in cells.Many reports have been issued about the mechanisms of receptor-mediated PLD activation. Although the mammalian PLD isozymes, PLD 1 and PLD 2 , have some different regulatory properties, in general, agonist-induced PLD is activated by various protein kinases, including protein kinase C, proteintyrosine kinase, and the MAP kinase family, in addition to small G proteins of the ARF, Rho, and Ras families (8 -13). The signal-dependent activation of PLD is rapid and transient. Although, the activation kinetics depend on the stimulus and cell type, the PLD signal is usually diminished within 10 min (14). However, the mechanisms involved in PLD signal inhibition remain unknow...

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Section: Figmentioning

confidence: 69%

Inhibition of Muscarinic Receptor-linked Phospholipase D Activation by Association with Tubulin

Chae

Lee

et al. 2005

Journal of Biological Chemistry

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“…PLD has a large role in the activity of lipid hydrolysis, and until now there have been many reports that its activity is elaborately controlled by many cellular regulators in diverse cell systems (20,22,26,31,33,34,35,37,50). In contrast, little is known about the details of mechanisms in the regulation of other proteins by PLD through direct binding.…”

Section: Discussionmentioning

confidence: 98%

Novel Functions of the Phospholipase D2-Phox Homology Domain in Protein Kinase Cζ Activation

Kim

Ohba

et al. 2005

Molecular and Cellular Biology

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It has been established that protein kinase C (PKC) participates in diverse signaling pathways and cellular functions in a wide variety of cells, exhibiting properties relevant to cellular survival and proliferation. Currently, however, the regulation mechanism of PKC remains elusive. Here, for the first time, we determine that phospholipase D2 (PLD2) enhances PKC activity through direct interaction in a lipase activity-independent manner. This interaction of the PLD2-Phox homology (PX) domain with the PKC-kinase domain also induces the activation loop phosphorylation of PKC and downstream signal stimulation, as measured by p70 S6 kinase phosphorylation. Furthermore, only the PLD2-PX domain directly stimulates PKC activity in vitro, and it is necessary for the formation of the ternary complex with phosphoinositide-dependent kinase 1 and PKC. The mutant that substitutes the triple lysine residues (Lys 101 , Lys 102, and Lys 103) within the PLD2-PX domain with alanine abolishes interaction with the PKC-kinase domain and activation of PKC. Moreover, breast cancer cell viability is significantly affected by PLD2 silencing. Taken together, these results suggest that the PLD2-mediated PKC activation is induced by its PX domain performing both direct activation of PKC and assistance of activation loop phosphorylation. Furthermore, we find it is an important factor in the survival of breast cancer cells.Protein kinase C (PKC) has been implicated in many cellular key functions, such as cell proliferation, survival, and migration (2, 40, 44). The PKC family is subclassified into three groupsclassical, novel, and atypical PKC-according to differences in the lipid activation profile (42). It has been established that the phosphorylation and activation of atypical PKC, especially, is an important factor in the survival of cancer cells (21, 41). The phosphorylation of PKC is one of the main mechanisms for regulating its activity. Recently, it has been reported that moderate activation of PKC is mediated through activation loop phosphorylation by phosphoinositide-dependent kinase 1 (PDK-1), followed by a subsequent autophosphorylation (8,38,59). PKC is also stimulated by the interaction of acidic lipids, including phosphatidic acid (PA) and phosphoinositides. Due to its structural uniqueness, PKC is insensitive to second messengers, such as Ca 2ϩ or diacylglycerol (DAG), known to be potent activators of the other families (46). Therefore, the activation of PKC may be expected to rely on a peculiar mechanism, which is perhaps regulated by many cellular proteins. However, the exact protein-protein interactions intrinsic to the regulation mechanism of PKC remain largely unclear.Phospholipase D (PLD) exists as a membrane-bound protein and is widely distributed in a variety of cells. It hydrolyzes phosphatidylcholine to generate choline and PA as a response to diverse stimuli. In many cancer cells, the abnormal overexpression of PLD is associated with the promotion of mitogenesis, oncogenic transformation, and cell proliferation an...

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“…23,32,33,[44][45][46][47][48] However, less is known about the interactions of PLD with downstream signaling proteins that would account for its presumed roles in regulating cell function. Here we present evidence that PLD2 complexes with Syk and in doing so facilitates activation of mast cells in the manner depicted in Figure 7D.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, the PLD PX and PH domains have been implicated in the direct interaction of PLD, particularly PLD2, with other proteins in a lipase-independent manner. These proteins include PLC␥, 32 Munc-18-1, 33 and PKC. 34 It has also been reported that PLD and c-Src interact similarly but in a lipase-dependent manner to enable phosphorylation of PLD2 and activation of Src.…”

Section: Introductionmentioning

confidence: 99%

Phospholipase D2 acts as an essential adaptor protein in the activation of Syk in antigen-stimulated mast cells

Lee

Kim

et al. 2006

Blood

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Munc-18-1 Inhibits Phospholipase D Activity by Direct Interaction in an Epidermal Growth Factor-reversible Manner

Cited by 35 publications

References 68 publications

Inhibition of Muscarinic Receptor-linked Phospholipase D Activation by Association with Tubulin

Inhibition of Muscarinic Receptor-linked Phospholipase D Activation by Association with Tubulin

Novel Functions of the Phospholipase D2-Phox Homology Domain in Protein Kinase Cζ Activation

Phospholipase D2 acts as an essential adaptor protein in the activation of Syk in antigen-stimulated mast cells

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