Differences in Gα12- and Gα13-mediated plasma membrane recruitment of p115-RhoGEF

Bhattacharyya, Raja; Banerjee, Jayashree; Khalili, Kamel; Wedegaertner, Philip

doi:10.1016/j.cellsig.2009.02.010

Cited by 18 publications

(26 citation statements)

References 34 publications

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“…In agreement with this, it has been demonstrated that membrane localization of Ga 13 is necessary to recruit p115-RhoGEF to the membrane for subsequent RhoA activation (53,54). Ga I was observed to disappear from membrane rafts/caveolae in lysates from both wt and Swap-70 2/2 BMDCs after stimulation with LPS and S1P.…”

Section: /2supporting

confidence: 59%

Sphingosine 1-Phosphate–Induced Motility and Endocytosis of Dendritic Cells Is Regulated by SWAP-70 through RhoA

Ocaña-Morgner

Reichardt

Chopin

et al. 2011

The Journal of Immunology

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The phospholipid mediator sphingosine 1-phosphate (S1P) enhances motility and endocytosis of mature dendritic cells (DCs). We show that in vitro migration of Swap-70−/− bone marrow-derived DCs (BMDCs) in response to S1P and S1P-induced upregulation of endocytosis are significantly reduced. S1P-stimulated movement of Swap-70−/− BMDCs, specifically retraction of their trailing edge, in a collagen three-dimensional environment is impaired. These in vitro observations correlate with delayed entry into lymphatic vessels and migration to lymph nodes of skin DCs in Swap-70−/− mice. Expression of S1P receptors (S1P1–3) by wild-type and Swap-70−/− BMDCs is similar, but Swap-70−/− BMDCs fail to activate RhoA and to localize Rac1 and RhoA into areas of actin polymerization after S1P stimulus. The Rho-activating G protein Gαi interacts with SWAP-70, which also supports the localization of Gα13 to membrane rafts in BMDCs. LPS-matured Swap-70−/− BMDCs contain significantly more active RhoA than wild-type DCs. Preinhibition of Rho activation restored migration to S1P, S1P-induced upregulation of endocytosis in mature Swap-70−/− BMDCs, and localization of Gα13 to membrane rafts. These data demonstrate SWAP-70 as a novel regulator of S1P signaling necessary for DC motility and endocytosis.

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Section: /2supporting

confidence: 59%

Sphingosine 1-Phosphate–Induced Motility and Endocytosis of Dendritic Cells Is Regulated by SWAP-70 through RhoA

Ocaña-Morgner

Reichardt

Chopin

et al. 2011

The Journal of Immunology

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“…It may also simply reflect the fact that p63RhoGEF has a relatively simple regulatory mechanism compared with other GPCR-regulated RhoGEFs, including its homologs Trio and Duet, which are more complex proteins and can potentially be recruited to the PM via multiple mechanisms. For example, PDZ-RhoGEF and LARG have N-terminal PDZ domains that are recruited to plexin receptors (47)(48)(49), and the PH domains of RH-RhoGEFs bind to activated RhoA in a feed-forward mechanism of activation (21,50). It will be interesting to identify the palmitoyltransferase(s) responsible for carrying out posttranslational modification of p63RhoGEF and determine whether this occurs in a signal-or locale-dependent manner.…”

Section: Discussionmentioning

confidence: 99%

Plasma Membrane Association of p63 Rho Guanine Nucleotide Exchange Factor (p63RhoGEF) Is Mediated by Palmitoylation and Is Required for Basal Activity in Cells

Aittaleb

Nishimura

Linder

et al. 2011

Journal of Biological Chemistry

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Activation of G protein-coupled receptors at the cell surface leads to the activation or inhibition of intracellular effector enzymes, which include various Rho guanine nucleotide exchange factors (RhoGEFs). RhoGEFs activate small molecular weight GTPases at the plasma membrane (PM). Many of the known G protein-coupled receptor-regulated RhoGEFs are found in the cytoplasm of unstimulated cells, and PM recruitment is a critical aspect of their regulation. In contrast, p63RhoGEF, a G␣ q -regulated RhoGEF, appears to be constitutively localized to the PM. The objective of this study was to determine the molecular basis for the localization of p63RhoGEF and the impact of its subcellular localization on its regulation by G␣ q . Herein, we show that the pleckstrin homology domain of p63RhoGEF is not involved in its PM targeting. Instead, a conserved string of cysteines (Cys-23/25/26) at the N terminus of the enzyme is palmitoylated and required for membrane localization and full basal activity in cells. Conversion of these residues to serine relocates p63RhoGEF from the PM to the cytoplasm, diminishes its basal activity, and eliminates palmitoylation. The activity of palmitoylation-deficient p63RhoGEF can be rescued by targeting to the PM by fusion with tandem phospholipase C-␦1 pleckstrin homology domains or by co-expression with wild-type G␣ q but not with palmitoylation-deficient G␣ q . Our data suggest that p63RhoGEF is regulated chiefly through allosteric control by G␣ q , as opposed to other known G␣-regulated RhoGEFs, which are instead sequestered in the cytoplasm, perhaps because of their high basal activity.Rho GTPases act as molecular switches that mediate a wide variety of cellular processes, such as actin cytoskeletal organization, cell migration, cell cycle progression, and transcriptional control (1-3). They are activated by Rho guanine nucleotide exchange factors (RhoGEFs), 3 which catalyze the exchange of GDP for GTP on the G protein (4, 5). The largest family of RhoGEFs is characterized by a Dbl homology (DH) domain that is almost always found immediately N-terminal to a pleckstrin homology (PH) domain. The DH domain forms the primary binding site for the GTPase, whereas the PH domain either modulates nucleotide exchange by the DH domain or has other functions. Heterotrimeric G-protein ␣ subunits are known to directly interact with and activate at least two classes of Dbl family RhoGEFs (6 -8). G␣ 12/13 subunits bind to the regulator of G protein signaling (RGS) homology (RH) domain of RH domaincontaining RhoGEFs (RH-RhoGEFs) such as leukemia-associated RhoGEF (LARG), PDZ-RhoGEF, and p115-RhoGEF (9 -12). G␣ q/11 subunits bind to the DH/PH core of another subfamily of RhoGEFs that includes p63RhoGEF and the C-terminal DH/PH domains of Trio and Duet (13,14). Because small GTPases are tethered to the plasma membrane (PM) via posttranslational prenylation of their C-terminal CAAX motifs (15), RhoGEFs must also be targeted to the PM in order to efficiently activate their substrates in living cells. Because...

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“…Plexin B1 signaling to RhoA does not seem to require G␣ 13 (Perrot et al, 2002). Although membrane recruitment is one aspect of signal transduction to RH-RhoGEFs, additional interactions at the cell membrane involving the various structural domains and sequence motifs of the RH-RhoGEF are probably required for full activation (Bhattacharyya and Wedegaertner, 2003;Bhattacharyya et al, 2009). Indeed, there is evidence that G␣ 13 interacts with other regions in addition to the RH domain (indicated by red arrows) to stabilize a high-affinity complex and stimulate GEF activity (Suzuki et al, 2009b).…”

Section: Heterotrimeric G Protein-regulated Rhogefs 115mentioning

confidence: 99%

“…There is considerable evidence that the mechanism of activation is also complex, involving not only recruitment to specific sites at the membrane surface, but also multiple intra-and intermolecular interactions that mediate inhibition of basal activity as well as allosteric activation (Bhattacharyya and Wedegaertner, 2003;Bhattacharyya et al, 2009;Suzuki et al, 2009b;Zheng et al, 2009). The specific details vary among subfamily members (e.g., p115RhoGEF lacks a PDZ domain) and context .…”

Section: The Rh-rhogefsmentioning

confidence: 99%

Structure and Function of Heterotrimeric G Protein-Regulated Rho Guanine Nucleotide Exchange Factors

Aittaleb

Boguth

Tesmer³

2010

Molecular Pharmacology

137

145

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Activation of certain classes of G protein-coupled receptors (GPCRs) can lead to alterations in the actin cytoskeleton, gene transcription, cell transformation, and other processes that are known to be regulated by Rho family small-molecular-weight GTPases. Although these responses can occur indirectly via cross-talk from canonical heterotrimeric G protein cascades, it has recently been demonstrated that Dbl family Rho guanine nucleotide exchange factors (RhoGEFs) can serve as the direct downstream effectors of heterotrimeric G proteins. Heterotrimeric G␣ 12/13 , G␣ q , and G␤␥ subunits are each now known to directly bind and regulate RhoGEFs. Atomic structures have recently been determined for several of these RhoGEFs and their G protein complexes, providing fresh insight into the molecular mechanisms of signal transduction between GPCRs and small molecular weight G proteins. This review covers what is currently known about the structure, function, and regulation of these recently recognized effectors of heterotrimeric G proteins.Heterotrimeric G proteins are master regulators of cell homeostasis. By coordinating signaling between the ϳ800 G protein-coupled receptors (GPCRs) in the human genome and a relatively small handful of effector enzymes and channels in the cell, they control processes such as muscle contractility, glycogen metabolism, neurotransmission, and the concentration of intracellular ions. Their profound impact on nearly all cellular processes and their therapeutic potential have rendered them one of the most intensely studied signal transduction paradigms at the biochemical and molecular level (Sprang et al., 2007).When heterotrimeric G proteins are in their inactive, GDPbound state, they exist as an inert complex composed of ␣, ␤, and ␥ subunits (G␣␤␥). In this state, they are substrates for activated GPCRs, which catalyze nucleotide exchange on the ␣ subunit (G␣). When bound to GTP, G␣ releases the effector binding surface of the ␤ and ␥ heterodimer (G␤␥) so that both G␣ and G␤␥ can interact with and modulate the activity of specific downstream enzymes and channels. The G␣ subunit has weak guanine nucleotide triphosphatase (GTPase) activity that slowly returns the G protein to its GDP-bound state. G␣⅐GDP then becomes resequestered by G␤␥. Beyond serving as conduits for extracellular signals, heterotrimeric G proteins contribute to the fidelity, duration, and amplitude of GPCR signaling. A given class of heterotrimeric G protein can typically recognize only a subset of GPCRs, and can only interact with one or a few downstream effector targets, ensuring the specificity of signaling from receptor to effector. The rate of GTP hydrolysis on G␣ dictates the length of time that its signal is in play, and this rate -bound conformation. The Ras-like domain is colored cyan, and the ␣-helical domain is gray. The three nucleotide-dependent switch regions (switch I-III) are red. The canonical effector docking site, a shallow canyon formed between switch II and the ␣3 helix, is indicated by the tr...

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Differences in Gα12- and Gα13-mediated plasma membrane recruitment of p115-RhoGEF

Cited by 18 publications

References 34 publications

Sphingosine 1-Phosphate–Induced Motility and Endocytosis of Dendritic Cells Is Regulated by SWAP-70 through RhoA

Sphingosine 1-Phosphate–Induced Motility and Endocytosis of Dendritic Cells Is Regulated by SWAP-70 through RhoA

Plasma Membrane Association of p63 Rho Guanine Nucleotide Exchange Factor (p63RhoGEF) Is Mediated by Palmitoylation and Is Required for Basal Activity in Cells

Structure and Function of Heterotrimeric G Protein-Regulated Rho Guanine Nucleotide Exchange Factors

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