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

Chae, Young Chan; Lee, Sukmook; Lee, Hye Young; Heo, Kyun; Kim, Junghwan; Kim, Jong Hyun; Suh, Pann‐Ghill; Ryu, Sung Ho

doi:10.1074/jbc.m406987200

Cited by 46 publications

(35 citation statements)

References 63 publications

(58 reference statements)

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“…Previous studies have shown that PLD activity can be regulated by various protein kinases such as PKC, protein-tyrosine kinases, and the MAP kinase family as well as the small G proteins from the ARF, Rho, and Ras families (38,39). Furthermore, the activity of PLD has been shown to be regulated through interactions with various cytoskeletal proteins such as tubulin, actin, and ␣-actinin (40)(41)(42). For example, Park et al (41) demonstrated that PLD can bind to ␣-actinin and that this interaction inhibits the activity of PLD.…”

Section: Discussionmentioning

confidence: 99%

The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle

Hornberger

Chen

Mak

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

264

263

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Signaling by the mammalian target of rapamycin (mTOR) has been reported to be necessary for mechanical load-induced growth of skeletal muscle. The mechanisms involved in the mechanical activation of mTOR signaling are not known, but several studies indicate that a unique [phosphotidylinositol-3-kinase (PI3K)-and nutrient-independent] mechanism is involved. In this study, we have demonstrated that a regulatory pathway for mTOR signaling that involves phospholipase D (PLD) and the lipid second messenger phosphatidic acid (PA) plays a critical role in the mechanical activation of mTOR signaling. First, an elevation in PA concentration was sufficient for the activation of mTOR signaling. Second, the isozymes of PLD (PLD1 and PLD2) are localized to the z-band in skeletal muscle (a critical site of mechanical force transmission). Third, mechanical stimulation of skeletal muscle with intermittent passive stretch ex vivo induced PLD activation, PA accumulation, and mTOR signaling. Finally, pharmacological inhibition of PLD blocked the mechanically induced increase in PA and the activation of mTOR signaling. Combined, these results indicate that mechanical stimuli activate mTOR signaling through a PLD-dependent increase in PA. Furthermore, we showed that mTOR signaling was partially resistant to rapamycin in muscles subjected to mechanical stimulation. Because rapamycin and PA compete for binding to the FRB domain on mTOR, these results suggest that mechanical stimuli activate mTOR signaling through an enhanced binding of PA to the FRB domain on mTOR.mechanical load ͉ skeletal muscle growth ͉ exercise ͉ stretch ͉ atrophy M echanical loads play a central role in the regulation of skeletal muscle mass; however, the mechanisms involved in converting mechanical signals into the molecular events that control this process have not been defined (1, 2). Recent studies on this topic have focused on a signaling network that is regulated by a protein kinase called the mammalian target of rapamycin (mTOR) (3-5). Interest in mTOR signaling was initially motivated by studies that suggested that this protein was the master regulator of a signaling network that controls cell growth (6, 7). One of the most intensely studied proteins in the mTOR signaling network is the ribosomal S6 kinase (p70 S6k ), and measurements of p70 S6k phosphorylation on the threonine 389 residue [p70 S6k (389)] are commonly used as a readout of mTOR signaling (6,8,9).Mechanical loading of skeletal muscle has been shown to induce p70 S6k (389) phosphorylation through a rapamycinsensitive mechanism, implicating a role for mTOR in this pathway (5, 10). Furthermore, the mechanical activation of p70 S6k phosphorylation correlates with the extent of the concomitant growth response, and inhibiting mTOR with rapamycin prevents the mechanical-load-induced growth (3-5, 11) Taken together, these observations indicate that the activation of mTOR signaling is an essential step for converting mechanical signals into a growth response.To date, the mechanisms involved in the m...

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Section: Discussionmentioning

confidence: 99%

The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle

Hornberger

Chen

Mak

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

264

263

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“…COS-7 cells were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% (vol/vol) fetal bovine serum at 37°C in a humidified, CO 2 -controlled (5%) incubator. For transfection and the transient expression of proteins, cells were transfected using Lipofectamine, as described previously (4). The following plasmids were used to induce overexpression: pcDNA3.1-HA-PKC␣, pcDNA3.1-HA-PKC␦, pcDNA3.1-HA-PKCε, pcDNA3.1-HA-DN-PKC␣, pcDNA3.1-HA-DN-PKC␦, pcDNA3.1-HA-DN-PKCε, pEGFP-C1-PLD2, and pcDNA3.1-FLAG-V12-Rac1.…”

Section: Methodsmentioning

confidence: 99%

Protein Kinase Cδ-Mediated Phosphorylation of Phospholipase D Controls Integrin-Mediated Cell Spreading

Chae¹,

Kim²,

Ha³

et al. 2010

Molecular and Cellular Biology

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Integrin signaling plays critical roles in cell adhesion, spreading, and migration, and it is generally accepted that to regulate these integrin functions accurately, localized actin remodeling is required. However, the molecular mechanisms that control the targeting of actin regulation molecules to the proper sites are unknown. We previously demonstrated that integrin-mediated cell spreading and migration on fibronectin are dependent on the localized activation of phospholipase D (PLD). However, the mechanism underlying PLD activation by integrin is largely unknown. Here we demonstrate that protein kinase C␦ (PKC␦) is required for integrinmediated PLD signaling. After integrin stimulation, PKC␦ is activated and translocated to the edges of lamellipodia, where it colocalizes with PLD2. The abrogation of PKC␦ activity inhibited integrin-induced PLD activation and cell spreading. Finally, we show that Thr566 of PLD2 is directly phosphorylated by PKC␦ and that PLD2 mutation in this region prevents PLD2 activation, PLD2 translocation to the edge of lamellipodia, Rac translocation, and cell spreading after integrin activation. Together, these results suggest that PKC␦ is a primary regulator of integrin-mediated PLD activation via the direct phosphorylation of PLD, which is essential for directing integrin-induced cell spreading.

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“…By contrast, little is known about the regulation of PLD2 although its activity is dependent upon PtdIns(4,5)P 2 and it has been hypothesised that availability of this lipid may be a major factor in its regulation (Divecha et al, 2000). Furthermore, in contrast to PLD1 which also requires PtdIns(4,5)P 2 for activation, PLD2 has been shown to have high basal activity in the presence of PtdIns(4,5)P 2 and may therefore be subject to negative regulation through direct protein interaction as has been demonstrated through interaction with proteins such as actin, α-actinin, α-synuclein and tubulin (Lee et al, 2001;Park et al, 2000;Payton et al, 2004;Chae et al, 2005).…”

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confidence: 99%

Phospholipase D2 stimulates integrin-mediated adhesion via phosphatidylinositol 4-phosphate 5-kinase Iγb

Powner

Payne

Pettitt

et al. 2005

Journal of Cell Science

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Cellular adhesion can be regulated by, as yet, poorly defined intracellular signalling events. Phospholipase D enzymes generate the messenger lipid phosphatidate and here we demonstrate that suppression of this reaction inhibits cellular adhesion. This effect was reversed by the addition of cell-permeable analogues of either phosphatidate or phosphatidylinositol 4,5-bisphosphate. By contrast, neither diacylglycerol nor lysophosphatidic acid were able to reverse this effect suggesting that phosphatidate itself acts directly on a target protein(s) to regulate adhesion rather than as the result of its conversion to either of these metabolite lipids. Antibodies that block β1 and β2 integrin-substrate interactions inhibited adhesion stimulated by both phosphatidate and phosphatidylinositol 4,5-bisphosphate indicating that these lipids regulate β1 and β2 integrin-mediated adhesion. In vivo, these lipids can be generated by phospholipase D2 and phosphatidylinositol 4-phosphate 5-kinase Iγb, respectively, and over-expression of catalytically-functional forms of these enzymes dose-dependently stimulated adhesion while siRNA depletion of PLD2 levels inhibited adhesion. Furthermore the ability of over-expressed phospholipase D2 to stimulate adhesion was inhibited by a dominant-negative version of phosphatidylinositol 4-phosphate 5-kinase Iγb. Consistent with this, phosphatidylinositol 4-phosphate 5-kinase Iγb-mediated adhesion was dependent upon phospholipase D2's product, phosphatidate indicating that phosphatidylinositol 4-phosphate 5-kinase Iγb is downstream of, and necessary for, phospholipase D2's regulation of adhesion. It is likely that this phospholipase D2-generated phosphatidate directly stimulates phosphatidylinositol 4-phosphate 5-kinase Iγb to generate phosphatidylinositol 4,5-bisphosphate as this mechanism has previously been demonstrated in vitro. Thus, our data indicates that during the initial stages of adhesion, phospholipase D2-derived phosphatidate stimulates phosphatidylinositol 4-phosphate 5-kinase Iγb to generate phosphatidylinositol 4,5-bisphosphate and that consequently this inositol phospholipid promotes adhesion through its regulation of cell-surface integrins.

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

Cited by 46 publications

References 63 publications

The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle

The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle

Protein Kinase Cδ-Mediated Phosphorylation of Phospholipase D Controls Integrin-Mediated Cell Spreading

Phospholipase D2 stimulates integrin-mediated adhesion via phosphatidylinositol 4-phosphate 5-kinase Iγb

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