scholarly journals Autophosphorylation-dependent degradation of Pak1, triggered by the Rho-family GTPase, Chp

2007 ◽  
Vol 404 (3) ◽  
pp. 487-497 ◽  
Author(s):  
Monika Weisz Hubsman ◽  
Natalia Volinsky ◽  
Edward Manser ◽  
Deborah Yablonski ◽  
Ami Aronheim
Keyword(s):  
Rho Gtpases ◽  
Cellular Functions ◽  
Kinase Activation ◽  
Homologous Protein ◽  
T Cell Migration ◽  
Rho Family Gtpases ◽  
Small Rho Gtpases ◽  
Rho Family ◽  
First Time ◽  
Pak1 Activation

The Paks (p21-activated kinases) Pak1, Pak2 and Pak3 are among the most studied effectors of the Rho-family GTPases, Rac, Cdc42 (cell division cycle 42) and Chp (Cdc42 homologous protein). Pak kinases influence a variety of cellular functions, but the process of Pak down-regulation, following activation, is poorly understood. In the present study, we describe for the first time a negative-inhibitory loop generated by the small Rho-GTPases Cdc42 and Chp, resulting in Pak1 inhibition. Upon overexpression of Chp, we unexpectedly observed a T-cell migration phenotype consistent with Paks inhibition. In line with this observation, overexpression of either Chp or Cdc42 caused a marked reduction in the level of Pak1 protein in a number of different cell lines. Chp-induced degradation was accompanied by ubiquitination of Pak1, and was dependent on the proteasome. The susceptibility of Pak1 to Chp-induced degradation depended on its p21-binding domain, kinase activity and a number of Pak1 autophosphorylation sites, whereas the PIX- (Pak-interacting exchange factor) and Nck-binding sites were not required. Together, these results implicate Chp-induced kinase autophosphorylation in the degradation of Pak1. The N-terminal domain of Chp was found to be required for Chp-induced degradation, although not for Pak1 activation, suggesting that Chp provides a second function, distinct from kinase activation, to trigger Pak degradation. Collectively, our results demonstrate a novel mechanism of signal termination mediated by the Rho-family GTPases Chp and Cdc42, which results in ubiquitin-mediated degradation of one of their direct effectors, Pak1.

Rho family GTPases

2012 ◽  
Vol 40 (6) ◽  
pp. 1378-1382 ◽  
Author(s):  
Alan Hall
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Cellular Response ◽  
Molecular Switches ◽  
Effector Proteins ◽  
Eukaryotic Cells ◽  
Cell Behaviour ◽  
Wide Range ◽  
Rho Family Gtpases ◽  
Rho Family

Rho GTPases comprise a family of molecular switches that control signal transduction pathways in eukaryotic cells. A conformational change induced upon binding GTP promotes an interaction with target (effector) proteins to generate a cellular response. A highly conserved function of Rho GTPases from yeast to humans is to control the actin cytoskeleton, although, in addition, they promote a wide range of other cellular activities. Changes in the actin cytoskeleton drive many dynamic aspects of cell behaviour, including morphogenesis, migration, phagocytosis and cytokinesis, and the dysregulation of Rho GTPases is associated with numerous human diseases and disorders.

scholarly journals Differential activation and function of Rho GTPases during Salmonella–host cell interactions

2006 ◽  
Vol 175 (3) ◽  
pp. 453-463 ◽  
Author(s):  
Jayesh C. Patel ◽  
Jorge E. Galán
Keyword(s):  
Rho Gtpases ◽  
Food Poisoning ◽  
Bacterial Pathogen ◽  
Cellular Responses ◽  
Host Cells ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
And Function

Salmonella enterica, the cause of food poisoning and typhoid fever, has evolved sophisticated mechanisms to modulate Rho family guanosine triphosphatases (GTPases) to mediate specific cellular responses such as actin remodeling, macropinocytosis, and nuclear responses. These responses are largely the result of the activity of a set of bacterial proteins (SopE, SopE2, and SopB) that, upon delivery into host cells via a type III secretion system, activate specific Rho family GTPases either directly (SopE and SopE2) or indirectly (SopB) through the stimulation of an endogenous exchange factor. We show that different Rho family GTPases play a distinct role in Salmonella-induced cellular responses. In addition, we report that SopB stimulates cellular responses by activating SH3-containing guanine nucleotide exchange factor (SGEF), an exchange factor for RhoG, which we found plays a central role in the actin cytoskeleton remodeling stimulated by Salmonella. These results reveal a remarkable level of complexity in the manipulation of Rho family GTPases by a bacterial pathogen.

scholarly journals Rho-family GTPases modulate Ca2+-dependent ATP release from astrocytes

2008 ◽  
Vol 295 (1) ◽  
pp. C231-C241 ◽  
Author(s):  
Andrew E. Blum ◽  
Sheldon M. Joseph ◽  
Ronald J. Przybylski ◽  
George R. Dubyak
Keyword(s):  
Rho Gtpases ◽  
Atp Release ◽  
Rho Kinase ◽  
Astrocytoma Cells ◽  
Gap Junction Channel ◽  
Rho Family Gtpases ◽  
Clostridium Difficile Toxin ◽  
Protease Activated Receptor 1 ◽  
Rho Family ◽  
Clostridium Difficile Toxin B

Previously, we reported that activation of G protein-coupled receptors (GPCR) in 1321N1 human astrocytoma cells elicits a rapid release of ATP that is partially dependent on a Gq/phophospholipase C (PLC)/Ca2+ mobilization signaling cascade. In this study we assessed the role of Rho-family GTPase signaling as an additional pathway for the regulation of ATP release in response to activation of protease-activated receptor-1 (PAR1), lysophosphatidic acid receptor (LPAR), and M3-muscarinic (M3R) GPCRs. Thrombin (or other PAR1 peptide agonists), LPA, and carbachol triggered quantitatively similar Ca2+ mobilization responses, but only thrombin and LPA caused rapid accumulation of active GTP-bound Rho. The ability to elicit Rho activation correlated with the markedly higher efficacy of thrombin and LPA, relative to carbachol, as ATP secretagogues. Clostridium difficile toxin B and Clostridium botulinum C3 exoenzyme, which inhibit Rho-GTPases, attenuated the thrombin- and LPA-stimulated ATP release but did not decrease carbachol-stimulated release. Thus the ability of certain Gq-coupled receptors to additionally stimulate Rho-GTPases acts to strongly potentiate a Ca2+-activated ATP release pathway. However, pharmacological inhibition of Rho kinase I/II or myosin light chain kinase did not attenuate ATP release. PAR1-induced ATP release was also reduced twofold by brefeldin treatment suggesting the possible mobilization of Golgi-derived, ATP-containing secretory vesicles. ATP release was also markedly repressed by the gap junction channel inhibitor carbenoxolone in the absence of any obvious thrombin-induced change in membrane permeability indicative of hemichannel gating.

scholarly journals The integrin cytoplasmic domain-associated protein ICAP-1 binds and regulates Rho family GTPases during cell spreading

2002 ◽  
Vol 156 (2) ◽  
pp. 377-388 ◽  
Author(s):  
Simona Degani ◽  
Fiorella Balzac ◽  
Mara Brancaccio ◽  
Simona Guazzone ◽  
Saverio Francesco Retta ◽  
...  
Keyword(s):  
Cell Spreading ◽  
Cytoplasmic Domain ◽  
Nih3t3 Cells ◽  
Cell Matrix ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
First Time ◽  
Cell Matrix Adhesion

Using two-hybrid screening, we isolated the integrin cytoplasmic domain-associated protein (ICAP-1), an interactor for the COOH terminal region of the β1A integrin cytoplasmic domain. To investigate the role of ICAP-1 in integrin-mediated adhesive function, we expressed the full-length molecule in NIH3T3 cells. ICAP-1 expression strongly prevents NIH3T3 cell spreading on extracellular matrix. This inhibition is transient and can be counteracted by coexpression of a constitutively activated mutant of Cdc42, suggesting that ICAP-1 acts upstream of this GTPase. In addition, we found that ICAP-1 binds both to Cdc42 and Rac1 in vitro, and its expression markedly inhibits activation of these GTPases during integrin-mediated cell adhesion to fibronectin as detected by PAK binding assay. In the attempt to define the molecular mechanism of this inhibition, we show that ICAP-1 reduces both the intrinsic and the exchange factor–induced dissociation of GDP from Cdc42; moreover, purified ICAP-1 displaces this GTPase from cellular membranes. Together, these data show for the first time that ICAP-1 regulates Rho family GTPases during integrin-mediated cell matrix adhesion, acting as guanine dissociation inhibitor.

scholarly journals The Large GTPase, GBP-2, Regulates Rho Family GTPases to Inhibit Migration and Invadosome Formation in Breast Cancer Cells

Cancers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 5632
Author(s):  
Geoffrey O. Nyabuto ◽  
John P. Wilson ◽  
Samantha A. Heilman ◽  
Ryan C. Kalb ◽  
Jonathan P. Kopacz ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Rho Gtpases ◽  
Breast Cancer Cells ◽  
Primary Site ◽  
Common Cancer ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
4T1 Cells ◽  
Guanylate Binding Protein

Breast cancer is the most common cancer in women. Despite advances in early detection and treatment, it is predicted that over 43,000 women will die of breast cancer in 2021. To lower this number, more information about the molecular players in breast cancer are needed. Guanylate-Binding Protein-2 has been correlated with better prognosis in breast cancer. In this study, we asked if the expression of GBP-2 in breast cancer merely provided a biomarker for improved prognosis or whether it actually contributed to improving outcome. To answer this, the 4T1 model of murine breast cancer was used. 4T1 cells themselves are highly aggressive and highly metastatic, while 67NR cells, isolated from the same tumor, do not leave the primary site. The expression of GBP-2 was examined in the two cell lines and found to be inversely correlated with aggressiveness/metastasis. Proliferation, migration, and invadosome formation were analyzed after altering the expression levels of GBP-2. Our experiments show that GBP-2 does not alter the proliferation of these cells but inhibits migration and invadosome formation downstream of regulation of Rho GTPases. Together these data demonstrate that GBP-2 is responsible for cell autonomous activities that make breast cancer cells less aggressive.

scholarly journals Proximity-dependent proteomics reveals extensive interactions of Protocadherin-19 with regulators of Rho GTPases and the microtubule cytoskeleton

2020 ◽  
Author(s):  
Michelle R. Emond ◽  
Sayantanee Biswas ◽  
Matthew L. Morrow ◽  
James D. Jontes
Keyword(s):  
Nervous System ◽  
Behavioral Problems ◽  
Rho Gtpases ◽  
Protein Complexes ◽  
Epileptic Seizures ◽  
Centrosomal Protein ◽  
Surface Receptors ◽  
Rho Family Gtpases ◽  
Rho Family

AbstractProtocadherin-19 belongs to the cadherin family of cell surface receptors and has been shown to play essential roles in the development of the vertebrate nervous system. Mutations in human Protocadherin-19 (PCDH19) lead to PCDH19 Female-limited epilepsy (PCDH19 FLE) in humans, characterized by the early onset of epileptic seizures in children and a range of cognitive and behavioral problems in adults. Despite being considered the second most prevalent gene in epilepsy, very little is known about the intercellular pathways in which it participates. In order to characterize the protein complexes within which Pcdh19 functions, we generated Pcdh19-BioID fusion proteins and utilized proximity-dependent biotinylation to identify neighboring proteins. Proteomic identification and analysis revealed that the Pcdh19 interactome is enriched in proteins that regulate Rho family GTPases, microtubule binding proteins and proteins that regulate cell divisions. We cloned the centrosomal protein Nedd1 and the RacGEF Dock7 and verified their interactions with Pcdh19 in vitro. Our findings provide the first comprehensive insights into the interactome of Pcdh19, and provide a platform for future investigations into the cellular and molecular biology of this protein critical to the proper development of the nervous system.

The emerging importance of group II PAKs

2010 ◽  
Vol 425 (3) ◽  
pp. 465-473 ◽  
Author(s):  
Claire M. Wells ◽  
Gareth E. Jones
Keyword(s):  
Functional Results ◽  
Effector Proteins ◽  
Cellular Functions ◽  
Downstream Effector ◽  
Group I ◽  
Rho Family Gtpases ◽  
Cytoskeletal Dynamics ◽  
Rho Family ◽  
Group Ii ◽  
Actin Cytoskeletal Dynamics

The Rho-family GTPases Rho Rac and Cdc42 regulate many intracellular processes through their interaction with downstream effector proteins. The PAKs (p21-activated kinases) are a family of effector proteins for Rac and Cdc42. PAKs are important regulators of actin cytoskeletal dynamics, neurite outgrowth, cell survival, hormone signalling and gene transcription. There are six mammalian PAKs that can be divided into two groups: group I PAKs (PAK1–3) and group II PAKs (PAK4–6). Although the two PAK groups are architecturally similar, there are differences in their mode of regulation, suggesting that their cellular functions are likely to be different. Whereas much is known about group I PAKs, less is known about the more recently discovered PAK4, PAK5 and PAK6. This review will focus on the latest structural and functional results relating to the group II PAKs and discuss the emerging importance of group II PAKs in disease progression.

scholarly journals Syndecan Regulates Cellular Morphogenesis in Cooperation with the Netrin Guidance Pathway and Rho-family GTPases

2022 ◽  
Author(s):  
Raphael Dima ◽  
Marianne Bah Tahe ◽  
Yann A Chabi ◽  
Lise Rivollet ◽  
Anthony F Arena ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Cell Types ◽  
Cellular Functions ◽  
C Elegans ◽  
Rho Family Gtpases ◽  
Canal Cell ◽  
Guidance Receptors ◽  
Cell Shapes ◽  
Rho Family ◽  
Excretory Canal

The establishment of complex cell shapes is essential for specific cellular functions, and thus critical in animal development and physiology. Heparan sulfate proteoglycans (HSPGs) are conserved glycoproteins that regulate interactions between extracellular signals and their receptors, to orchestrate morphogenetic events and elicit cellular responses. Although HSPG-regulated pathways have been implicated in regulating the guidance of neuronal migrations, whether HSPGs regulate earlier aspects of cellular development that dictate cell shape remains unknown. HSPGs consist of a protein core (e.g., Syndecan, Perlecan, Glypican, etc.) with attached heparan sulfate (HS) glycosaminoglycan chains, which are synthesized by glycosyltransferases of the exostosin family. Using mutations in the two C. elegans HS glycosyltransferases genes, rib-1 and rib-2, we reveal that HSPGs control the number of cellular projections in the epithelial excretory canal cell, which can form more than its normal four canals in these mutants. We identify SDN-1/Syndecan as the key HSPG that regulates the number of excretory canal cell projections in a cell-autonomous manner. We also find that Syndecan and guidance receptors for Netrin function in the same pathway to restrict the number of cellular projections. Furthermore, we show that the formation of extra projections in the absence of Syndecan requires the conserved Rho-family GTPases CED-10/Rac and MIG-2/RhoG. Our findings not only contribute to understanding the roles of conserved HSPGs in cellular morphogenetic events, but also reveal the existence of an HSPG-regulated system operating to guarantee that a precise number of cellular projections is established during cell development. Given the evolutionary conservation of developmental mechanisms and the molecules implicated, this work provides information relevant to understanding the cellular and molecular bases of the development of precise cellular morphologies in varied cell types across animals.

scholarly journals Inhibition of Rac GTPase signaling and downstream prosurvival Bcl-2 proteins as combination targeted therapy in MLL-AF9 leukemia

Blood ◽  
2011 ◽  
Vol 118 (19) ◽  
pp. 5235-5245 ◽  
Author(s):  
Benjamin Mizukawa ◽  
Junping Wei ◽  
Mahesh Shrestha ◽  
Mark Wunderlich ◽  
Fu-Sheng Chou ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Cellular Functions ◽  
Rac Gtpase ◽  
Molecule Inhibitor ◽  
Survival Pathway ◽  
Apoptotic Effect ◽  
Small Rho Gtpases ◽  
Expression Model ◽  
Cytoskeleton Rearrangements

Abstract The Rac family of small Rho GTPases coordinates diverse cellular functions in hematopoietic cells including adhesion, migration, cytoskeleton rearrangements, gene transcription, proliferation, and survival. The integrity of Rac signaling has also been found to critically regulate cellular functions in the initiation and maintenance of hematopoietic malignancies. Using an in vivo gene targeting approach, we demonstrate that Rac2, but not Rac1, is critical to the initiation of acute myeloid leukemia in a retroviral expression model of MLL-AF9 leukemogenesis. However, loss of either Rac1 or Rac2 is sufficient to impair survival and growth of the transformed MLL-AF9 leukemia. Rac2 is known to positively regulate expression of Bcl-2 family proteins toward a prosurvival balance. We demonstrate that disruption of downstream survival signaling through antiapoptotic Bcl-2 proteins is implicated in mediating the effects of Rac2 deficiency in MLL-AF9 leukemia. Indeed, overexpression of Bcl-xL is able to rescue the effects of Rac2 deficiency and MLL-AF9 cells are exquisitely sensitive to direct inhibition of Bcl-2 family proteins by the BH3-mimetic, ABT-737. Furthermore, concurrent exposure to NSC23766, a small-molecule inhibitor of Rac activation, increases the apoptotic effect of ABT-737, indicating the Rac/Bcl-2 survival pathway may be targeted synergistically.

scholarly journals RHO Family GTPases in the Biology of Lymphoma

Cells ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 646 ◽  
Author(s):  
Voena ◽  
Chiarle
Keyword(s):  
Rho Gtpases ◽  
Intracellular Signaling ◽  
Human Cancer ◽  
Loss Of Function ◽  
Cellular Processes ◽  
Ras Gtpase ◽  
Rho Family Gtpases ◽  
Ras Family ◽  
Human Lymphoma ◽  
Rho Family

RHO GTPases are a class of small molecules involved in the regulation of several cellular processes that belong to the RAS GTPase superfamily. The RHO family of GTPases includes several members that are further divided into two different groups: typical and atypical. Both typical and atypical RHO GTPases are critical transducers of intracellular signaling and have been linked to human cancer. Significantly, both gain-of-function and loss-of-function mutations have been described in human tumors with contradicting roles depending on the cell context. The RAS family of GTPases that also belong to the RAS GTPase superfamily like the RHO GTPases, includes arguably the most frequently mutated genes in human cancers (K-RAS, N-RAS, and H-RAS) but has been extensively described elsewhere. This review focuses on the role of RHO family GTPases in human lymphoma initiation and progression.

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