Rac2‐deficient mice display perturbed T‐cell distribution and chemotaxis, but only minor abnormalities in T<sub>H</sub>1 responses

Croker, Ben A.; Handman, Emanuela; Hayball, John D.; Baldwin, Tracey M.; Voigt, Valentina; Cluse, Leonie A.; Yang, Feng Chun; Williams, David A.; Roberts, Andrew W.

doi:10.1046/j.1440-1711.2002.01077.x

Cited by 54 publications

(61 citation statements)

References 48 publications

(75 reference statements)

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“…specificity in their effects on the actin cytoskeleton and cellular morphology. This signaling specificity has been largely ascribed to differences in the effector loop (amino acids [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and the insert region (amino acids 124 -136), domains that are divergent among the different family members. However, the most variable region within the closely related Rho-like GTPases is the C terminus.…”

Section: Discussionmentioning

confidence: 99%

“…The differential effects of the Rac1 and Rac2 peptides, both on actin polymerization and chemotaxis, are remarkable, considering there is more Rac2 than Rac1 in leukocytes (31) and that Rac2 has been implicated in migration of neutrophils, B-cells, and T-cells (32)(33)(34). Yet introduction of the C terminus of Rac1 is sufficient to block chemotaxis, further underscoring the role of the C terminus in determining signaling specificity between Rac1 and Rac2.…”

Section: Discussionmentioning

confidence: 99%

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The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

Hennik

Klooster

Halstead

et al. 2003

Journal of Biological Chemistry

119

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Rho-like GTPases control a wide range of cellular functions such as integrin-and cadherin-mediated adhesion, cell motility, and gene expression. The hypervariable C-terminal domain of these GTPases has been implicated in membrane association and effector binding. We found that cell-permeable peptides, encoding the C termini of Rac1, Rac2, RhoA, and Cdc42, interfere with GTPase signaling in a specific fashion in a variety of cellular models. Pull-down assays showed that the C terminus of Rac1 does not associate to either RhoGDI or to Pak. In contrast, the C terminus of Rac1 (but not Rac2 or Cdc42) binds to phosphatidylinositol 4,5-phosphate kinase (PIP5K) via amino acids 185-187 (RKR). Moreover, Rac1 associates to the adapter protein Crk via the N-terminal Src homology 3 (SH3) domain of Crk and the proline-rich stretch in the Rac1 C terminus. These differential interactions mediate Rac1 localization, as well as Rac1 signaling, toward membrane ruffling, cell-cell adhesion, and migration. These data show that the Cterminal, hypervariable domain of Rac1 encodes two distinct binding motifs for signaling proteins and regulates intracellular targeting and differential signaling in a unique and non-redundant fashion.Rho-like GTPases drive temporally and spatially coordinated actin polymerization to control cell motility, cadherin-based cell-cell adhesion, and cytokinesis (1-4). To relay their signals, Rho-like GTPases interact with a wide range of effector proteins. These interactions are generally thought to occur at the plasma membrane to which GTPases are translocated prior to activation by guanine nucleotide exchange factors. This membrane association is dependent on lipid modifications of specific cysteine residues in the extreme C terminus (i.e. prenylation), as well as on the C-terminal polybasic region (5).Rho-like GTPases share a high level of homology, despite the fact that their effects on cellular morphology or function can be very distinct. This has been attributed to sequence diversity in the effector domain (residues 26 -45) and the so-called insert region (amino acids 124 -135). However, the most divergent region between otherwise very homologous GTPases (e.g. Rac 1066 CX, and Rac2) is the C-terminal polybasic region. This domain was shown to be required for activation of the neutrophil NADPH oxidase (6) and was claimed for Rac1 to drive activation of PAK 1 by some (7) but not by others (6). Most of the studies that have addressed the role of this domain relied on deletion or mutation strategies, testing the role of this region in the context of, for instance, a constitutively active variant of the GTPase.Tao et al. (5) showed recently that deleting the C-terminal polybasic region affects the efficiency of prenylation of Rac2. Moreover, del Pozo et al. (8) have shown that mutation of the crucial cysteine residue to prevent Rac prenylation blocked activation of PAK. This means that mutating or deleting the C-terminal domain may affect downstream signaling in an indirect manner, complicating the interpret...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

Hennik

Klooster

Halstead

et al. 2003

Journal of Biological Chemistry

119

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“…In addition, Rac1 is also required for BCR/ABL-mediated leukemogenesis (Skorski et al 1998). In contrast to Rac1, Rac2 is specifically expressed in cells of hematopoietic origin (Didsbury et al 1989, Wennerberg & Der 2004) and mice genetically deficient in Rac2 are characterized by defects in cellular functions of diverse hematopoietic cells (Croker et al 2002a,b, Gu et al 2002, Carstanjen et al 2005. Rac3 is most highly expressed in brain, but has also been found in other organs including placenta, kidney, pancreas, and heart (Haataja et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Prognostic relevance of increased Rac GTPase expression in prostate carcinomas

Engers¹,

Ziegler²,

Mueller³

et al. 2007

Endocr Relat Cancer

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Rac proteins of the Rho-like GTPase family, including the ubiquitous Rac1, the hematopoiesisspecific Rac2, and the least-characterized Rac3 play a major role in oncogenic transformation, tumor invasion and metastasis. However, the prognostic relevance of Rac expression in human tumors has not been investigated yet. In the present study, Rac protein expression was analyzed in benign secretory epithelium, high-grade prostatic intraepithelium neoplasia (HG-PIN), and prostate carcinomas of 60 R0-resected radical prostatectomy specimens by semiquantitative immunohistochemistry. Thus, Rac proteins were significantly strongly expressed in HG-PIN (P!0.001) and prostate carcinomas (P!0.001) when compared with benign secretory epithelium. Accordingly, all tumor tissues analyzed by isoform-specific real-time PCR (nZ7) exhibited significantly higher RNA expression levels of Rac (i.e. sum of Rac1 and Rac3 expression levels) than the respective benign counterparts (PZ0.018) and this appeared to result mainly from increased expression of the Rac3 isoform as verified by immunoblotting. Univariate analyses showed statistically significant associations of increased Rac protein expression in prostate cancer (PZ0.045), preoperative prostate-specific antigen levels (PZ0.044), pT stage (PZ0.002), and Gleason score (PZ0.001) with decreased disease-free survival (DFS). This prognostic effect of increased protein expression of Rac remained significant even in a multivariate analysis including all these four factors (relative riskZ3.22, 95% confidence intervalZ1.04-10.00; PZ0.043). In conclusion, our data suggest that increased Rac protein expression in prostate cancer relative to the corresponding benign secretory epithelium is an independent predictor of decreased DFS and appears to result mainly from increased expression of the Rac3 isoform.

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“…Both effects are mediated by the putative amino-terminal pleckstrin homology domain of PLC␤ 2 (12)(13)(14). Rac2 is specifically expressed in cells of hematopoietic origin (27,28), and mice genetically deficient in Rac2 are characterized by defects in cellular functions of hematopoietic stem cells (29,30), neutrophils (31), mast cells (32), T cells (33), and B lymphocytes (34,35). In the latter cells, the absence of Rac2 caused a reduction in the B cell antigen receptor (BCR)-mediated increase in cytosolic Ca 2ϩ (34,35).…”

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confidence: 99%

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

Piechulek

Rehlen

Walliser

et al. 2005

Journal of Biological Chemistry

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The regulation of the two isoforms of phospholipase C-␥, PLC␥ 1 and PLC␥ 2 , by cell surface receptors involves protein tyrosine phosphorylation as well as interaction with adapter proteins and phosphatidylinositol 3,4,5-trisphosphate (PtdInsP 3 ) generated by inositol phospholipid 3-kinases (PI3Ks). All three processes may lead to recruitment of the PLC␥ isozymes to the plasma membrane and/or stimulation of their catalytic activity. Recent evidence suggests that PLC␥ may also be regulated by Rho GTPases. In this study, PLC␥ 1 and PLC␥ 2 were reconstituted in intact cells and in a cell-free system with Rho GTPases to examine their influence on PLC␥ activity. PLC␥ 2 , but not PLC␥ 1 , was markedly activated in intact cells by constitutively active Rac1 G12V , Rac2 G12V , and Rac3 G12V but not by Cdc42 G12V and RhoA G14V . The mechanism of PLC␥ 2 activation was apparently independent of phosphorylation of tyrosine residues known to be modified by PLC␥ 2 -activating protein-tyrosine kinases. Activation of PLC␥ 2 by Rac2 G12V in intact cells coincided with a translocation of PLC␥ 2 from the soluble to the particulate fraction. PLC␥ isozyme-specific activation of PLC␥ 2 by Rac GTPases (Rac1 ≈ Rac2 > Rac3), but not by Cdc42 or RhoA, was also observed in a cell-free system. Herein, activation of wild-type Rac GTPases with guanosine 5-(3-O-thio)triphosphate caused a marked stimulation of PLC␥ 2 but had no effect on the activity of PLC␥ 1 . PLC␥ 1 and PLC␥ 2 have previously been shown to be indiscriminately activated by PtdInsP 3 in vitro. Thus, the results suggest a novel mechanism of PLC␥ 2 activation by Rac GTPases involving neither protein tyrosine phosphorylation nor PI3K-mediated generation of PtdInsP 3 .Inositol phospholipid-specific phospholipases C (PLCs) 3 catalyze the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP 2 ) to produce inositol 1,4,5-trisphosphate and diacylglycerol. While the products of this reaction have long been known to act as intracellular second messengers (reviewed in Refs. 1-4), it has only recently become clear that the phospholipid substrate itself may also be considered an intracellular signaling molecule in that its local concentration in the plasma membrane and possibly in other cellular membranes regulates the activities and/or subcellular distribution of a number of regulatory or structural proteins. These include enzymes, ion channels and transporters, transcription factors, scaffolding proteins, cytoskeletal proteins, as well as proteins involved in the regulation of exocytosis, endocytosis, and membrane trafficking (reviewed in Refs. 5-8).The mammalian PLCs are divided into six subfamilies, designated ␤, ␥, ␦, ⑀, , and (reviewed in Refs. 9 and 10). The four members of the PLC␤ subfamily are activated by ␤␥ dimers of heterotrimeric G proteins and/or members of the ␣ q subfamily of G protein ␣ subunits and by certain Rho GTPases (11-14). The two members of the PLC␥ family are activated by receptor and nonreceptor protein-tyrosine kinases (reviewed in Refs. 9, 10, 15, ...

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Rac2‐deficient mice display perturbed T‐cell distribution and chemotaxis, but only minor abnormalities in T_H1 responses

Cited by 54 publications

References 48 publications

The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

Prognostic relevance of increased Rac GTPase expression in prostate carcinomas

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

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Rac2‐deficient mice display perturbed T‐cell distribution and chemotaxis, but only minor abnormalities in TH1 responses

Cited by 54 publications

References 48 publications

The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

The C-terminal Domain of Rac1 Contains Two Motifs That Control Targeting and Signaling Specificity

Prognostic relevance of increased Rac GTPase expression in prostate carcinomas

Isozyme-specific Stimulation of Phospholipase C-γ2 by Rac GTPases

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Product

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Rac2‐deficient mice display perturbed T‐cell distribution and chemotaxis, but only minor abnormalities in T_H1 responses