3BP-1, an SH3 domain binding protein, has GAP activity for Rac and inhibits growth factor-induced membrane ruffling in fibroblasts.

Cicchetti, Piera; Ridley, Anne J.; Zheng, Yi; Cerione, Richard A.; Baltimore, David

doi:10.1002/j.1460-2075.1995.tb07315.x

Cited by 68 publications

(67 citation statements)

References 44 publications

(19 reference statements)

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“…Bcr contains a domain with strong GAP activity towards Cdc42 and Rac1, but not RhoA (Diekmann et al, 1991;Ridley et al, 1993). 3BP-1, a GAP protein that binds the SH3 domain of Abl, has the same speci®city as Bcr except that the GAP activity is relatively less potent (Cicchetti et al, 1995). RhoGAP has GAP activity toward Cdc42 and Rho, but not Rac1 (Lancaster et al, 1994;Ridley et al, 1993).…”

Section: Resultsmentioning

confidence: 99%

Mechanism of activation of Pak1 kinase by membrane localization

Mayer

1999

Oncogene

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Pak kinases are a family of serine/threonine protein kinases homologous to Ste20p of yeast. Paks can be activated in vivo and in vitro by binding to GTP-bound Cdc42 and Rac1, members of the Rho family of small GTPases implicated in regulating the organization of the actin cytoskeleton. We have previously reported that the SH2/SH3-containing adaptor protein Nck binds Pak kinase through its second SH3 domain. Pak1 can be targeted to the membrane by Nck in response to tyrosine phosphorylation, and membrane association of Pak1 is su cient to increase its speci®c activity. The mechanism whereby Pak is activated by membrane localization, however, is unknown. We show here that expression of three proteins that inhibit Rho-family GTPases by di erent mechanisms (RhoGDI, Bcr and D57Y Cdc42) all block the activation of Pak by a membrane-targeted Nck SH3 domain, demonstrating that the in vivo activation of Pak1 induced by membrane localization is dependent on Rho-family GTPases. This implies that Pak activity can be regulated in cells both by the level of GTP loading of various Rho-family GTPases and the local concentration of Pak relative to these GTPases. Our data also suggest the existence of Rho-family GTPases in addition to Cdc42 and Rac1 that can activate Pak on membranes.

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Section: Resultsmentioning

confidence: 99%

Mechanism of activation of Pak1 kinase by membrane localization

Mayer

1999

Oncogene

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“…Many RhoGAP domains, however, appear to represent a constitutively active structural module and display limited specificity toward the Rho GTPase substrates. Under overexpression or microinjection conditions, RhoGAP domain alone could cause Rho GTPase down-regulation and disruption of certain Rho-mediated cellular functions (45,52,53). This likely is because of partial saturation of intracellular compartments by the introduced RhoGAP domain and may not be desirable in studies to extract more specific function of individual members of Rho GTPases.…”

Section: Discussionmentioning

confidence: 99%

A Novel Strategy for Specifically Down-regulating Individual Rho GTPase Activity in Tumor Cells

Wang

Yang

Luo

et al. 2003

Journal of Biological Chemistry

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The Rho family GTPases RhoA, RhoB, and RhoC regulate the actin cytoskeleton, cell movement, and cell growth. Unlike Ras, up-regulation or overexpression of these GDP/GTP binding molecular switches, but not activating point mutations, has been associated with human cancer. Although they share over 85% sequence identity, RhoA, RhoB, and RhoC appear to play distinct roles in cell transformation and metastasis. In NIH 3T3 cells, RhoA or RhoB overexpression causes transformation whereas RhoC increases the cell migration rate. To specifically target RhoA, RhoB, or RhoC function, we have generated a set of chimeric molecules by fusing the RhoGAP domain of p190, a GTPase-activating protein that accelerates the intrinsic GTPase activity of all three Rho GTPases, with the C-terminal hypervariable sequences of RhoA, RhoB, or RhoC. The p190-Rho chimeras were active as GTPase-activating proteins toward RhoA in vitro, co-localized with the respective active Rho proteins, and specifically down-regulated Rho protein activities in cells depending on which Rho GTPase sequences were included in the chimeras. In particular, the p190-RhoA-C chimera specifically inhibited RhoA-induced transformation whereas p190-RhoC-C specifically reversed the migration phenotype induced by the active RhoC. In human mammary epithelial-RhoC breast cancer cells, p190-RhoC-C, but not p190-RhoA-C or p190-RhoB-C, reversed the anchorageindependent growth and invasion phenotypes caused by RhoC overexpression. In the highly metastatic A375-M human melanoma cells, p190-RhoC-C specifically reversed migration, and invasion phenotypes attributed to RhoC up-regulation. Thus, we have developed a novel strategy utilizing RhoGAP-Rho chimeras to specifically down-regulate individual Rho activity and demonstrate that this approach may be applied to multiple human tumor cells to reverse the growth and/or invasion phenotypes associated with disregulation of a distinct subtype of Rho GTPase.

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“…Proteins containing these consensi are predicted to bind SH3-containing proteins and have proven to be regulatory for localization or activity (Bar-Sagi et al, 1993). Other proteins which contain this motif include the GTPase dynamin (Gout et al, 1993), the Rho-GAP 3BP-1 (Cicchetti et al, 1992(Cicchetti et al, , 1995Ren et al, 1993), and the guanine nucleotide exchange factor Sos1 . One other proline-rich kinase (not related to STE20), MAPKAP kinase 2, has been shown to bind the SH3 domain of c-Abl in a ®lter binding assay, but the relevance of this binding is unclear (Plath et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

A novel human SPS1/STE20 homologue, KHS, activates Jun N-terminal kinase

Tung

Blenis

1997

Oncogene

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STE20-homologous proteins have been implicated in mammalian MAP kinase pathways as important transducers of signals from p21 family GTPases. We have cloned a novel STE20 family member, which we call KHS for kinase homologous to SPS1/STE20, that encodes a kinase of 95 kD which is expressed in a variety of tissues. Transiently expressed fusion protein GST-KHS exhibits phosphotransferase activity toward a panel of test substrates, including myelin basic protein (MBP), which is phosphorylated by all known STE20 homologues. KHS is most closely related to another human STE20, GC kinase (74% similar in the catalytic domain), which has recently been placed upstream of the stress-activated MAP kinases (SAPKs/JNKs. KHS also activates JNK in transient coexpression experiments, suggesting a role for KHS in the stress response of ®broblasts. Characterization and comparison of the regulation of these two kinases will be important in elucidating MAP kinase signalling cascades.

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3BP-1, an SH3 domain binding protein, has GAP activity for Rac and inhibits growth factor-induced membrane ruffling in fibroblasts.

Cited by 68 publications

References 44 publications

Mechanism of activation of Pak1 kinase by membrane localization

Mechanism of activation of Pak1 kinase by membrane localization

A Novel Strategy for Specifically Down-regulating Individual Rho GTPase Activity in Tumor Cells

A novel human SPS1/STE20 homologue, KHS, activates Jun N-terminal kinase

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