The human orthologue of CdGAP is a phosphoprotein and a GTPase‐activating protein for Cdc42 and Rac1 but not RhoA

Tcherkezian, Joseph; Triki, Ibtissem; Stenne, Raphaëlle; Danek, Eric I.; Lamarche-Vane, Nathalie

doi:10.1042/bc20050101

Cited by 28 publications

(39 citation statements)

References 47 publications

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“…Mouse and hCdGAP constructs were as described previously (Southgate et al, submitted;Tcherkezian et al, 2005Tcherkezian et al, , 2006.…”

Section: Methodsmentioning

confidence: 99%

“…CdGAP contains a N-terminal GAP domain, a basic central region and a proline-rich domain (PRD) with an extended C-terminal domain (Lamarche-Vane and Hall, 1998;Jenna et al, 2002;Tcherkezian et al, 2006). We have previously shown that CdGAP is a substrate of ERK/GSK-3 and mediates cross talk between the Ras/MAP kinase pathway and regulation of Rac1 activity (Tcherkezian et al, 2005;Danek et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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CdGAP is required for transforming growth factor β- and Neu/ErbB-2-induced breast cancer cell motility and invasion

Northey

Primeau

et al. 2010

Oncogene

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RhoA, Rac1 and Cdc42, the best-characterized members of the Rho family of small GTPases, are critical regulators of many cellular activities. Cdc42 GTPaseactivating protein (CdGAP) is a serine-and proline-rich RhoGAP protein showing GAP activity against both Cdc42 and Rac1 but not RhoA. CdGAP is phosphorylated downstream of the MEK-ERK (extracellular signalregulated kinase) pathway in response to serum and is required for normal cell spreading and polarized lamellipodia formation. In this study, we found that CdGAP protein and mRNA levels are highly increased in mammary tumor explants expressing an activated Neu/ ErbB-2 (Neu-NT) receptor. In response to transforming growth factor-b (TGFb) stimulation, Neu-NT-expressing mammary tumor explants demonstrate a clear induction in cell motility and invasion. We show that downregulation of CdGAP expression by small interfering RNA abrogates the ability of TGFb to induce cell motility and invasion of Neu-NT-expressing mammary tumor explants. However, it has no effect on TGFb-mediated cell adhesion on type 1 collagen and fibronectin. Interestingly, protein expression of E-Cadherin is highly increased in Neu-NT-expressing mammary tumor explants depleted of CdGAP. In addition, complete loss of E-Cadherin expression is not observed in CdGAP-depleted cells during TGFb-mediated epithelial to mesenchymal transition. Downregulation of the CdGAP expression also decreases cell proliferation of Neu-NT-expressing mammary tumor explants independently of TGFb. Rescue analysis using re-expression of various CdGAP deletion-mutant proteins revealed that the proline-rich domain (PRD) but not the GAP domain of CdGAP is essential to mediate TGFbinduced cell motility and invasion. Finally, we found that TGFb induces the expression and phosphorylation of CdGAP in mammary epithelial NMuMG cells. Taken together, these studies identify CdGAP as a novel molecular target in TGFb signaling and implicate CdGAP as an essential component in the synergistic interaction between TGFb and Neu/ErbB-2 signaling pathways in breast cancer cells.

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“…Mouse and hCdGAP constructs were as described previously (Southgate et al, submitted;Tcherkezian et al, 2005Tcherkezian et al, , 2006.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CdGAP is required for transforming growth factor β- and Neu/ErbB-2-induced breast cancer cell motility and invasion

Northey

Primeau

et al. 2010

Oncogene

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“…It is required for cell spreading, polarized lamellipodia formation and cell migration. 14,15 The Rho GTPases control many aspects of cell behavior, such as the organization of the cytoskeleton, cell migration, cell-cell and cell-matrix adhesion, cell-cycle progression, gene expression and cell polarity. [16][17][18] DLG1-disks, large homolog 1…”

Section: Hpa036380mentioning

confidence: 99%

Novel signatures of cancer‐associated fibroblasts

Bozóky

Savchenko

Csermely

et al. 2013

Intl Journal of Cancer

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Increasing evidence indicates the importance of the tumor microenvironment, in particular cancer-associated fibroblasts, in cancer development and progression. In our study, we developed a novel, visually based method to identify new immunohistochemical signatures of these fibroblasts. The method employed a protein list based on 759 protein products of genes identified by RNA profiling from our previous study, comparing fibroblasts with differential growth-modulating effect on human cancers cells, and their first neighbors in the human protein interactome. These 2,654 proteins were analyzed in the Human Protein Atlas online database by comparing their immunohistochemical expression patterns in normal versus tumor-associated fibroblasts. Twelve new proteins differentially expressed in cancer-associated fibroblasts were identified (DLG1, BHLHE40, ROCK2, RAB31, AZI2, PKM2, ARHGAP31, ARHGAP26, ITCH, EGLN1, RNF19A and PLOD2), four of them can be connected to the Rho kinase signaling pathway. They were further analyzed in several additional tumor stromata and revealed that the majority showed congruence among the different tumors. Many of them were also positive in normal myofibroblast-like cells. The new signatures can be useful in immunohistochemical analysis of different tumor stromata and may also give us an insight into the pathways activated in them in their true in vivo context. The method itself could be used for other similar analysis to identify proteins expressed in other cell types in tumors and their surrounding microenvironment.

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“…DNA Constructs-CdGAP constructs were as described previously (6,8,11). GSK-3␣ was obtained as a full clone in the pACTII vector (see "Yeast Two-hybrid Screen").…”

Section: Methodsmentioning

confidence: 99%

“…Recombinant GSK-3␣ and -␤ and phospho-glycogen synthase peptide were purchased from Upstate Biotechnology. Polyclonal anti-CdGAP antibodies were produced and purified as described previously (8,11). Polyclonal antibodies against phospho-Thr-776 of CdGAP were produced by immunizing rabbits with a peptide CXPPPPT*PLEEEPE (T* represents phosphorylated threonine, and X represents hexanoic acid spacer).…”

Section: Methodsmentioning

confidence: 99%

Glycogen Synthase Kinase-3 Phosphorylates CdGAP at a Consensus ERK 1 Regulatory Site

Danek¹,

Tcherkezian²,

Triki

et al. 2007

Journal of Biological Chemistry

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Rho GTPases regulate a multitude of cellular processes from cytoskeletal reorganization to gene transcription and are negatively regulated by GTPase-activating proteins (GAPs). Cdc42 GTPase-activating protein (CdGAP) is a ubiquitously expressed GAP for Rac1 and Cdc42. In this study, we set out to identify CdGAP-binding partners and, using a yeast two-hybrid approach, glycogen synthase kinase 3␣ (GSK-3␣) was identified as a partner for CdGAP. GSK-3 exists in two isoforms, ␣ and ␤, and is involved in regulating many cellular functions from insulin response to tumorigenesis. We show that GSK-3␣ and -␤ interact with CdGAP in mammalian cells. We also demonstrate that GSK-3 phosphorylates CdGAP both in vitro and in vivo on Thr-776, which we have previously shown to be an ERK 1/2 phosphorylation site involved in CdGAP regulation. We report that the mRNA and protein levels of CdGAP are increased upon serum stimulation and that GSK-3 activity is necessary for the up-regulation of the protein levels of CdGAP but not for the increase in mRNA. We conclude that GSK-3 is an important regulator of CdGAP and that regulation of CdGAP protein levels by serum presents a novel mechanism for cells to control Cdc42/Rac1 GTPase signaling pathways.The Rho subfamily of small GTPases controls a wide variety of cellular functions. RhoA, Rac1, and Cdc42 are the best known members of this family, and they are most often associated with their roles as regulators of cytoskeleton remodeling and as key mediators of the activation of transcription of genes downstream of growth factor receptors (1). Much evidence exists linking Rho GTPases to transformation of cells; however, contrary to the Ras gene, activating mutations in Rho genes are rarely found in human cancers (2, 3). It seems instead that the expression of Rho GTPases and expression and function of regulators of the Rho subfamily of GTPases are altered during cellular transformation (2, 3).Rho GTPases act in a cycle as molecular switches with an active GTP-bound form and an inactive GDP-bound form (1). The GTPase-activating proteins (GAPs) 5 negatively regulate the GTPases by enhancing the hydrolysis of GTP to GDP (1). To date, ϳ70 human genes are predicted to encode for potential RhoGAP proteins (4), which is roughly triple the number of Rho GTPases (1). This lends weight to the notion that regulators like the RhoGAPs tightly control Rho GTPases and lend context-dependent specificity to their processes. Thus, the activity of RhoGAPs must be highly regulated in both spatial and temporal fashions. RhoGAPs are regulated at the protein level by a variety of mechanisms ranging from protein-protein interactions to phosphorylation, lipid interactions, and proteolytic degradation (5).Cdc42 GTPase-activating protein (CdGAP) has been shown to regulate both Cdc42 and Rac1 in vitro and in vivo and exists in two main isoforms: a short form of 820 amino acids containing an N-terminal RhoGAP domain, a central region, and a C-terminal proline-rich region (PRD) (6, 7) and a long isoform comprising the...

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The human orthologue of CdGAP is a phosphoprotein and a GTPase‐activating protein for Cdc42 and Rac1 but not RhoA

Cited by 28 publications

References 47 publications

CdGAP is required for transforming growth factor β- and Neu/ErbB-2-induced breast cancer cell motility and invasion

CdGAP is required for transforming growth factor β- and Neu/ErbB-2-induced breast cancer cell motility and invasion

Novel signatures of cancer‐associated fibroblasts

Glycogen Synthase Kinase-3 Phosphorylates CdGAP at a Consensus ERK 1 Regulatory Site

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