scholarly journals A mammalian Rho-specific guanine-nucleotide exchange factor (p164-RhoGEF) without a pleckstrin homology domain

2002 ◽  
Vol 366 (3) ◽  
pp. 721-728 ◽  
Author(s):  
Ulrich RÜMENAPP ◽  
Andrea FREICHEL-BLOMQUIST ◽  
Burkhard WITTINGHOFER ◽  
Karl H. JAKOBS ◽  
Thomas WIELAND
Keyword(s):  
Gene Transcription ◽  
Rho Gtpases ◽  
Serum Response Factor ◽  
Full Length ◽  
Pleckstrin Homology Domain ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Pleckstrin Homology ◽  
Guanine Nucleotide Exchange ◽  
Dh Domain

Rho GTPases, which are activated by specific guanine-nucleotide exchange factors (GEFs), play pivotal roles in several cellular functions. We identified a recently cloned human cDNA, namely KIAA0337, encoding a protein containing 1510 amino acids (p164). It contains a RhoGEF-specific Dbl homology (DH) domain but lacks their typical pleckstrin homology domain. The expression of the mRNA encoding p164 was found to be at least 4-fold higher in the heart than in other tissues. Recombinant p164 interacted with and induced GDP/GTP exchange at RhoA but not at Rac1 or Cdc42. p164-ΔC and p164-ΔN are p164 mutants that are truncated at the C- and N-termini respectively but contain the DH domain. In contrast with the full-length p164, expression of p164-ΔC and p164-ΔN strongly induced actin stress fibre formation and activated serum response factor-mediated and Rho-dependent gene transcription. Interestingly, p164-ΔN2, a mutant containing the C-terminus but having a defective DH domain, bound to p164-ΔC and suppressed the p164-ΔC-induced gene transcription. Overexpression of the full-length p164 inhibited M3 muscarinic receptor-induced gene transcription, whereas co-expression with Gβ1γ2 dimers induced transcriptional activity. It is concluded that p164-RhoGEF is a Rho-specific GEF with novel structural and regulatory properties and predominant expression in the heart. Apparently, its N- and C-termini interact with each other, thereby inhibiting its GEF activity.

scholarly journals Selectivity of Guanine Nucleotide Exchange Factor-mediated Cdc42 activation in primary human endothelial cells

2019 ◽  
Author(s):  
Nathalie R. Reinhard ◽  
Sanne van der Niet ◽  
Anna Chertkova ◽  
Marten Postma ◽  
Peter L. Hordijk ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Single Cell ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Actin Dynamics ◽  
Pleckstrin Homology Domain ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Dh Domain

AbstractThe Rho GTPase family is involved in actin dynamics and regulates the barrier function of the endothelium. One of the main barrier-promoting Rho GTPases is Cdc42, also known as cell division control protein 42 homolog. Currently, regulation of Cdc42-based signaling networks in endothelial cells (ECs) lack molecular details. To examine these, we focused on a subset of 15 Rho guanine nucleotide exchange factors (GEFs), which are expressed in the endothelium. By performing single cell FRET measurements with Rho GTPase biosensors in primary human ECs, we monitored GEF efficiency towards Cdc42 and Rac1. A new, single cell-based analysis was developed and used to enable the quantitative comparison of cellular activities of the full-length GEFs. Our data reveal a specific GEF dependent activation profile, with most efficient Cdc42 activation induced by PLEKHG2, FGD1, PLEKHG1 and pRex1 and the highest selectivity for FGD1. Additionally, we generated truncated GEF constructs that comprise only the catalytic dbl homology (DH) domain or together with the adjacent pleckstrin homology domain (DHPH). The DH domain by itself did not activate Cdc42, whereas the DHPH domain of ITSN1, ITSN2 and PLEKHG1 showed activity towards Cdc42. Together, our study characterized endothelial GEFs that may activate Cdc42, which will be of great value for the field of vascular biology.Abstract FigureGraphical Abstract

scholarly journals The Dbs PH domain contributes independently to membrane targeting and regulation of guanine nucleotide-exchange activity

2006 ◽  
Vol 400 (3) ◽  
pp. 563-572 ◽  
Author(s):  
Mark A. Baumeister ◽  
Kent L. Rossman ◽  
John Sondek ◽  
Mark A. Lemmon
Keyword(s):  
Rho Gtpases ◽  
Regulatory Role ◽  
Pleckstrin Homology Domain ◽  
Membrane Targeting ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Ph Domain ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Dh Domain

Dbl family GEFs (guanine nucleotide-exchange factors) for the Rho GTPases almost invariably contain a PH (pleckstrin homology) domain adjacent to their DH (Dbl homology) domain. The DH domain is responsible for GEF activity, and the PH domain plays a regulatory role that remains poorly understood. We demonstrated previously that Dbl family PH domains bind phosphoinositides with low affinity and cannot function as independent membrane targeting modules. In the present study, we show that dimerization of a Dbs (Dbl's big sister) DH/PH domain fragment is sufficient to drive it to the plasma membrane through a mechanism involving PH domain–phosphoinositide interactions. Thus, the Dbs PH domain could play a significant role in membrane targeting if it co-operates with other domains in the protein. We also show that mutations that prevent phosphoinositide binding by the Dbs PH domain significantly impair cellular GEF activity even in chimaeric proteins that are robustly membrane targeted by farnesylation or by the PH domain of phospholipase C-δ1. This finding argues that the Dbs PH domain plays a regulatory role that is independent of its ability to aid membrane targeting. Thus, we suggest that the PH domain plays dual roles, contributing independently to membrane localization of Dbs (as part of a multi-domain interaction) and allosteric regulation of the DH domain.

scholarly journals Critical but Distinct Roles for the Pleckstrin Homology and Cysteine-Rich Domains as Positive Modulators of Vav2 Signaling and Transformation

2002 ◽  
Vol 22 (8) ◽  
pp. 2487-2497 ◽  
Author(s):  
Michelle A. Booden ◽  
Sharon L. Campbell ◽  
Channing J. Der
Keyword(s):  
Membrane Association ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Ph Domain ◽  
Pleckstrin Homology ◽  
Guanine Nucleotide Exchange ◽  
Ph Domains ◽  
Transforming Activity ◽  
Dh Domain ◽  
Exchange Activity

ABSTRACT Vav2, like all Dbl family proteins, possesses tandem Dbl homology (DH) and pleckstrin homology (PH) domains and functions as a guanine nucleotide exchange factor for Rho family GTPases. Whereas the PH domain is a critical positive regulator of DH domain function for a majority of Dbl family proteins, the PH domains of the related Vav and Vav3 proteins are dispensable for DH domain activity. Instead, Vav proteins contain a cysteine-rich domain (CRD) critical for DH domain function. We evaluated the contribution of the PH domain and the CRD to Vav2 guanine nucleotide exchange, signaling, and transforming activity. Unexpectedly, we found that mutations of the PH domain impaired Vav2 signaling, transforming activity, and membrane association. However, these mutations do not influence exchange activity on Rac and only slightly affect exchange on RhoA and Cdc42. We also found that the CRD was critical for the exchange activity in vitro and contributed to Vav2 membrane localization. Finally, we found that phosphoinositol 3-kinase activation synergistically enhanced Vav2 transforming and signaling activity by stimulating exchange activity but not membrane association. In conclusion, the PH domain and CRD are mechanistically distinct, positive modulators of Vav2 DH domain function in vivo.

scholarly journals RalGEF2, a Pleckstrin Homology Domain Containing Guanine Nucleotide Exchange Factor for Ral

2000 ◽  
Vol 275 (38) ◽  
pp. 29761-29766 ◽  
Author(s):  
Kim M. T. de Bruyn ◽  
Johan de Rooij ◽  
Rob M. F. Wolthuis ◽  
Holger Rehmann ◽  
Joep Wesenbeek ◽  
...  
Keyword(s):  
Guanine Nucleotide Exchange Factor ◽  
Pleckstrin Homology Domain ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Pleckstrin Homology ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

scholarly journals Inositol phospholipids regulate the guanine-nucleotide-exchange factor Tiam1 by facilitating its binding to the plasma membrane and regulating GDP/GTP exchange on Rac1

2004 ◽  
Vol 382 (3) ◽  
pp. 857-865 ◽  
Author(s):  
Ian N. FLEMING ◽  
Ian H. BATTY ◽  
Alan R. PRESCOTT ◽  
Alex GRAY ◽  
Gursant S. KULAR ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Inositol Phosphates ◽  
Pleckstrin Homology Domain ◽  
Membrane Association ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Pleckstrin Homology ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

Binding of the Rac1-specific guanine-nucleotide-exchange factor, Tiam1, to the plasma membrane requires the N-terminal pleckstrin homology domain. In the present study, we show that membrane-association is mediated by binding of PtdIns(4,5)P2 to the pleckstrin homology domain. Moreover, in 1321N1 astrocytoma cells, translocation of Tiam1 to the cytosol, following receptor-mediated stimulation of PtdIns(4,5)P2 breakdown, correlates with decreased Rac1-GTP levels, indicating that membrane-association is required for GDP/GTP exchange on Rac1. In addition, we show that platelet-derived growth factor activates Rac1 in vivo by increasing PtdIns(3,4,5)P3 concentrations, rather than the closely related lipid, PtdIns(3,4)P2. Finally, the data demonstrate that PtdIns(4,5)P2 and PtdIns(3,4,5)P3 bind to the same pleckstrin homology domain in Tiam1 and that soluble inositol phosphates appear to compete with lipids for this binding. Together, these novel observations provide strong evidence that distinct phosphoinositides regulate different functions of this enzyme, indicating that local concentrations of signalling lipids and the levels of cytosolic inositol phosphates will play crucial roles in determining its activity in vivo.

scholarly journals Identification and characterization of a novel Rho-specific guanine nucleotide exchange factor

2000 ◽  
Vol 352 (2) ◽  
pp. 319-325 ◽  
Author(s):  
Andrea BLOMQUIST ◽  
Guntram SCHWÖRER ◽  
Helge SCHABLOWSKI ◽  
Amalia PSOMA ◽  
Michaela LEHNEN ◽  
...  
Keyword(s):  
Gene Transcription ◽  
Transcriptional Activation ◽  
Bound States ◽  
Membrane Receptors ◽  
Pleckstrin Homology Domain ◽  
Dependent Manner ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Rho Gef

Rho GTPases are implicated in a multitude of cellular processes regulated by membrane receptors, such as cytoskeletal rearrangements, gene transcription and cell growth and motility. Activation of these GTPases is under the direct control of guanine nucleotide exchange factors (GEFs), the Dbl family proteins. By searching protein databases we have identified a novel Rho-GEF, termed p114-Rho-GEF, which similarly to other Rho-GEFs contains a Dbl homology domain followed by a pleckstrin homology domain. p114-Rho-GEF interacted specifically with RhoA, in its nucleotide-free and guanosine 5′-[γ-thio]triphosphate-bound states, but not with Rac1 and Cdc42, and efficiently catalysed guanine nucleotide exchange of RhoA. Consistent with these results in vitro was our finding that the overexpression of p114-Rho-GEF in J82 and HEK-293 cells induced the formation of actin stress fibres and stimulated serum-response-factor-mediated gene transcription in a Rho-dependent manner. Rho-mediated transcriptional activation induced by M3 muscarinic acetylcholine and lysophosphatidic acid receptors was enhanced by p114-Rho-GEF, suggesting that the activity of this novel Rho-GEF, which is widely expressed in human tissues, can be controlled by G-protein-coupled receptors.

scholarly journals Bacterial Guanine Nucleotide Exchange Factors SopE-Like and WxxxE Effectors

2010 ◽  
Vol 78 (4) ◽  
pp. 1417-1425 ◽  
Author(s):  
Richard Bulgin ◽  
Benoit Raymond ◽  
James A. Garnett ◽  
Gad Frankel ◽  
Valerie F. Crepin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rho Gtpases ◽  
Shigella Flexneri ◽  
Small Gtpases ◽  
Effector Proteins ◽  
Actin Dynamics ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
T3ss Effector

ABSTRACT Subversion of Rho family small GTPases, which control actin dynamics, is a common infection strategy used by bacterial pathogens. In particular, Salmonella enterica serovar Typhimurium, Shigella flexneri, enteropathogenic Escherichia coli (EPEC), and enterohemorrhagic Escherichia coli (EHEC) translocate type III secretion system (T3SS) effector proteins to modulate the Rho GTPases RhoA, Cdc42, and Rac1, which trigger formation of stress fibers, filopodia, and lamellipodia/ruffles, respectively. The Salmonella effector SopE is a guanine nucleotide exchange factor (GEF) that activates Rac1 and Cdc42, which induce “the trigger mechanism of cell entry.” Based on a conserved Trp-xxx-Glu motif, the T3SS effector proteins IpgB1 and IpgB2 of Shigella, SifA and SifB of Salmonella, and Map of EPEC and EHEC were grouped together into a WxxxE family; recent studies identified the T3SS EPEC and EHEC effectors EspM and EspT as new family members. Recent structural and functional studies have shown that representatives of the WxxxE effectors share with SopE a 3-D fold and GEF activity. In this minireview, we summarize contemporary findings related to the SopE and WxxxE GEFs in the context of their role in subverting general host cell signaling pathways and infection.

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