scholarly journals Rac1 Protein Rescues Neurite Retraction Caused by G2019S Leucine-rich Repeat Kinase 2 (LRRK2)

2011 ◽  
Vol 286 (18) ◽  
pp. 16140-16149 ◽  
Author(s):  
Diane Chan ◽  
Allison Citro ◽  
Joanna M. Cordy ◽  
Grace C. Shen ◽  
Benjamin Wolozin
Keyword(s):  
Parkinson Disease ◽  
Rho Gtpases ◽  
Cellular Localization ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Late Onset ◽  
Critical Role ◽  
Leucine Rich Repeat ◽  
Neurite Retraction ◽  
P21 Activated Kinase

Mutations in leucine-rich repeat kinase 2 (LRRK2) are currently the most common genetic cause of familial late-onset Parkinson disease, which is clinically indistinguishable from idiopathic disease. The most common pathological mutation in LRRK2, G2019S LRRK2, is known to cause neurite retraction. However, molecular mechanisms underlying regulation of neurite length by LRRK2 are unknown. Here, we demonstrate a novel interaction between LRRK2 and the Rho GTPase, Rac1, which plays a critical role in actin cytoskeleton remodeling necessary for the maintenance of neurite morphology. LRRK2 binds strongly to endogenous or expressed Rac1, while showing weak binding to Cdc42 and no binding to RhoA. Co-expression with LRRK2 increases Rac1 activity, as shown by increased binding to the p21-activated kinase, which modulates actin cytoskeletal dynamics. LRRK2 constructs carrying mutations that inactivate the kinase or GTPase activities do not activate Rac1. Interestingly, LRRK2 does not increase levels of membrane-bound Rac1 but dramatically changes the cellular localization of Rac1, causing polarization, which is augmented further when LRRK2 is co-expressed with constitutively active Rac1. Four different disease-related mutations in LRRK2 altered binding to Rac1, with the G2019S and R1441C LRRK2 mutations attenuating Rac1 binding and the Y1699C and I2020T LRRK2 mutations increasing binding. Co-expressing Rac1 in SH-SY5Y cells rescues the G2019S mutant phenotype of neurite retraction. We hypothesize that pathological mutations in LRRK2 attenuates activation of Rac1, causing disassembly of actin filaments, leading to neurite retraction. The interactions between LRRK2 and Rho GTPases provide a novel pathway through which LRRK2 might modulate cellular dynamics and contribute to the pathophysiology of Parkinson disease.

scholarly journals Targeting and activation of Rac1 are mediated by the exchange factor β-Pix

2006 ◽  
Vol 172 (5) ◽  
pp. 759-769 ◽  
Author(s):  
Jean Paul ten Klooster ◽  
Zahara M. Jaffer ◽  
Jonathan Chernoff ◽  
Peter L. Hordijk
Keyword(s):  
Rho Gtpases ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Exchange Factor ◽  
Downstream Signaling ◽  
Intracellular Targeting ◽  
Dynamics And Control ◽  
P21 Activated Kinase ◽  
Gtpase Activation

Rho guanosine triphosphatases (GTPases) are critical regulators of cytoskeletal dynamics and control complex functions such as cell adhesion, spreading, migration, and cell division. It is generally accepted that localized GTPase activation is required for the proper initiation of downstream signaling events, although the molecular mechanisms that control targeting of Rho GTPases are unknown. In this study, we show that the Rho GTPase Rac1, via a proline stretch in its COOH terminus, binds directly to the SH3 domain of the Cdc42/Rac activator β-Pix (p21-activated kinase [Pak]–interacting exchange factor). The interaction with β-Pix is nucleotide independent and is necessary and sufficient for Rac1 recruitment to membrane ruffles and to focal adhesions. In addition, the Rac1–β-Pix interaction is required for Rac1 activation by β-Pix as well as for Rac1-mediated spreading. Finally, using cells deficient for the β-Pix–binding kinase Pak1, we show that Pak1 regulates the Rac1–β-Pix interaction and controls cell spreading and adhesion-induced Rac1 activation. These data provide a model for the intracellular targeting and localized activation of Rac1 through its exchange factor β-Pix.

scholarly journals PAK and other Rho-associated kinases – effectors with surprisingly diverse mechanisms of regulation

2005 ◽  
Vol 386 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Zhou-shen ZHAO ◽  
Ed MANSER
Keyword(s):  
Rho Gtpases ◽  
Cell Biology ◽  
Rho Gtpase ◽  
Rho Kinase ◽  
Molecular Switches ◽  
Eukaryotic Cell ◽  
Effector Proteins ◽  
Downstream Effector ◽  
P21 Activated Kinase ◽  
Do So

The Rho GTPases are a family of molecular switches that are critical regulators of signal transduction pathways in eukaryotic cells. They are known principally for their role in regulating the cytoskeleton, and do so by recruiting a variety of downstream effector proteins. Kinases form an important class of Rho effector, and part of the biological complexity brought about by switching on a single GTPase results from downstream phosphorylation cascades. Here we focus on our current understanding of the way in which different Rho-associated serine/threonine kinases, denoted PAK (p21-activated kinase), MLK (mixed-lineage kinase), ROK (Rho-kinase), MRCK (myotonin-related Cdc42-binding kinase), CRIK (citron kinase) and PKN (protein kinase novel), interact with and are regulated by their partner GTPases. All of these kinases have in common an ability to dimerize, and in most cases interact with a variety of other proteins that are important for their function. A diversity of known structures underpin the Rho GTPase–kinase interaction, but only in the case of PAK do we have a good molecular understanding of kinase regulation. The ability of Rho GTPases to co-ordinate spatial and temporal phosphorylation events explains in part their prominent role in eukaryotic cell biology.

scholarly journals Analysis of the LRRK2 p.G2019S mutation in Colombian Parkinson’s Disease Patients

2015 ◽  
pp. 117-121 ◽  
Author(s):  
Andres Felipe Duque ◽  
Juan Carlos Lopez ◽  
Helena Hernandez ◽  
Bruno Benitez ◽  
Juan Jose Yunis ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson Disease ◽  
Latin American ◽  
Autosomal Dominant ◽  
Late Onset ◽  
Causal Factor ◽  
Leucine Rich Repeat ◽  
Common Cause ◽  
Asymptomatic Control ◽  
Normal Controls

Introduction: Mutations in the leucine-rich repeat kinase 2 gene (LRRK2 or Dardarin) are considered to be a common cause of autosomal dominant and sporadic Parkinson´s disease, but the prevalence of these mutations varies among populations. Objective: to analysed the frequency of the LRRK2 p.G2019S mutation (c.6055G>A transition) in a sample of Colombian patients. Materials and Methods: In the present study we have analysed the frequency of the LRRK2 p.G2019S mutation in 154 patients with familial or sporadic Parkinson Disease, including early and late onset patients, and 162 normal controls. Results: Our results show occurrence of this mutation in two cases (2/154, 1.3%) with classical Parkinson´s signs, and one completely asymptomatic control (1/162, 0.6%). Conclusion: The p.G2019S mutation is not an important causal factor of Parkinson Disease in Colombia having similar frequencies to those reported in other Latin American populations.

scholarly journals MicroRNA Regulation of the Small Rho GTPase Regulators—Complexities and Opportunities in Targeting Cancer Metastasis

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1092 ◽  
Author(s):  
Brock A. Humphries ◽  
Zhishan Wang ◽  
Chengfeng Yang
Keyword(s):  
Transcriptional Activation ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Large Family ◽  
Actin Dynamics ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange

The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.

scholarly journals Mechanochemical coupling and junctional forces during collective cell migration

2019 ◽  
Author(s):  
J. Bui ◽  
D. E. Conway ◽  
R. L. Heise ◽  
S.H. Weinberg
Keyword(s):  
Cell Migration ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Leading Edge ◽  
Collective Cell Migration ◽  
Gtpase Activity ◽  
Modeling Framework ◽  
Cell Cell

ABSTRACTCell migration, a fundamental physiological process in which cells sense and move through their surrounding physical environment, plays a critical role in development and tissue formation, as well as pathological processes, such as cancer metastasis and wound healing. During cell migration, dynamics are governed by the bidirectional interplay between cell-generated mechanical forces and the activity of Rho GTPases, a family of small GTP-binding proteins that regulate actin cytoskeleton assembly and cellular contractility. These interactions are inherently more complex during the collective migration of mechanically coupled cells, due to the additional regulation of cell-cell junctional forces. In this study, we present a minimal modeling framework to simulate the interactions between mechanochemical signaling in individual cells and interactions with cell-cell junctional forces during collective cell migration. We find that migration of individual cells depends on the feedback between mechanical tension and Rho GTPase activity in a biphasic manner. During collective cell migration, waves of Rho GTPase activity mediate mechanical contraction/extension and thus synchronization throughout the tissue. Further, cell-cell junctional forces exhibit distinct spatial patterns during collective cell migration, with larger forces near the leading edge. Larger junctional force magnitudes are associated with faster collective cell migration and larger tissue size. Simulations of heterogeneous tissue migration exhibit a complex dependence on the properties of both leading and trailing cells. Computational predictions demonstrate that collective cell migration depends on both the emergent dynamics and interactions between cellular-level Rho GTPase activity and contractility, and multicellular-level junctional forces.

Cell motility: can Rho GTPases and microtubules point the way?

2001 ◽  
Vol 114 (21) ◽  
pp. 3795-3803 ◽  
Author(s):  
Torsten Wittmann ◽  
Clare M. Waterman-Storer
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Motility ◽  
Rho Gtpases ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Cell Types ◽  
Small Gtpases ◽  
Cell Polarization ◽  
Microtubule Cytoskeleton ◽  
Filament Bundles

Migrating cells display a characteristic polarization of the actin cytoskeleton. Actin filaments polymerise in the protruding front of the cell whereas actin filament bundles contract in the cell body, which results in retraction of the cell’s rear. The dynamic organization of the actin cytoskeleton provides the force for cell motility and is regulated by small GTPases of the Rho family, in particular Rac1, RhoA and Cdc42. Although the microtubule cytoskeleton is also polarized in a migrating cell, and microtubules are essential for the directed migration of many cell types, their role in cell motility is not well understood at a molecular level. Here, we discuss the potential molecular mechanisms for interplay of microtubules, actin and Rho GTPase signalling in cell polarization and motility. Recent evidence suggests that microtubules locally modulate the activity of Rho GTPases and, conversely, Rho GTPases might be responsible for the initial polarization of the microtubule cytoskeleton. Thus, microtubules might be part of a positive feedback mechanism that maintains the stable polarization of a directionally migrating cell.

scholarly journals Rho GTPase–independent regulation of mitotic progression by the RhoGEF Net1

2013 ◽  
Vol 24 (17) ◽  
pp. 2655-2667 ◽  
Author(s):  
Sarita Menon ◽  
Wonkyung Oh ◽  
Heather S. Carr ◽  
Jeffrey A. Frost
Keyword(s):  
Molecular Mechanisms ◽  
Spindle Assembly Checkpoint ◽  
Rho Gtpase ◽  
Spindle Assembly ◽  
Nucleotide Exchange ◽  
Altered Expression ◽  
Human Cancers ◽  
Nucleotide Exchange Factor ◽  
Chromosome Congression ◽  
P21 Activated Kinase

Neuroepithelial transforming gene 1 (Net1) is a RhoA-subfamily–specific guanine nucleotide exchange factor that is overexpressed in multiple human cancers and is required for proliferation. Molecular mechanisms underlying its role in cell proliferation are unknown. Here we show that overexpression or knockdown of Net1 causes mitotic defects. Net1 is required for chromosome congression during metaphase and generation of stable kinetochore microtubule attachments. Accordingly, inhibition of Net1 expression results in spindle assembly checkpoint activation. The ability of Net1 to control mitosis is independent of RhoA or RhoB activation, as knockdown of either GTPase does not phenocopy effects of Net1 knockdown on nuclear morphology, and effects of Net1 knockdown are effectively rescued by expression of catalytically inactive Net1. We also observe that Net1 expression is required for centrosomal activation of p21-activated kinase and its downstream kinase Aurora A, which are critical regulators of centrosome maturation and spindle assembly. These results identify Net1 as a novel regulator of mitosis and indicate that altered expression of Net1, as occurs in human cancers, may adversely affect genomic stability.

scholarly journals PakB binds to the SH3 domain of Dictyostelium Abp1 and regulates its effects on cell polarity and early development

2013 ◽  
Vol 24 (14) ◽  
pp. 2216-2227 ◽  
Author(s):  
Yidai Yang ◽  
Marc de la Roche ◽  
Scott W. Crawley ◽  
Zhihao Li ◽  
Emilia Furmaniak-Kazmierczak ◽  
...  
Keyword(s):  
Early Development ◽  
Actin Filaments ◽  
Cellular Localization ◽  
Critical Role ◽  
Leading Edge ◽  
Sh3 Domain ◽  
Cell Polarization ◽  
Actin Binding ◽  
Filamentous Actin ◽  
P21 Activated Kinase

Dictyostelium p21-activated kinase B (PakB) phosphorylates and activates class I myosins. PakB colocalizes with myosin I to actin-rich regions of the cell, including macropinocytic and phagocytic cups and the leading edge of migrating cells. Here we show that residues 1–180 mediate the cellular localization of PakB. Yeast two-hybrid and pull-down experiments identify two proline-rich motifs in PakB-1-180 that directly interact with the SH3 domain of Dictyostelium actin-binding protein 1 (dAbp1). dAbp1 colocalizes with PakB to actin-rich regions in the cell. The loss of dAbp1 does not affect the cellular distribution of PakB, whereas the loss of PakB causes dAbp1 to adopt a diffuse cytosolic distribution. Cosedimentation studies show that the N-terminal region of PakB (residues 1–70) binds directly to actin filaments, whereas dAbp1 exhibits only a low affinity for filamentous actin. PakB-1-180 significantly enhances the binding of dAbp1 to actin filaments. When overexpressed in PakB-null cells, dAbp1 completely blocks early development at the aggregation stage, prevents cell polarization, and significantly reduces chemotaxis rates. The inhibitory effects are abrogated by the introduction of a function-blocking mutation into the dAbp1 SH3 domain. We conclude that PakB plays a critical role in regulating the cellular functions of dAbp1, which are mediated largely by its SH3 domain.

scholarly journals Spatial Organization of Rho GTPase signaling by RhoGEF/RhoGAP proteins

2018 ◽  
Author(s):  
Paul M. Müller ◽  
Juliane Rademacher ◽  
Richard D. Bagshaw ◽  
Keziban M. Alp ◽  
Girolamo Giudice ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Spatial Organization ◽  
Rho Gtpase ◽  
Critical Role ◽  
Control Cell ◽  
Positional Information ◽  
Small Gtpases ◽  
G Protein Coupled Receptors ◽  
Signaling Networks ◽  
G Protein Coupled

AbstractRho GTPases control cell morphogenesis and thus fundamental processes in all eukaryotes. They are regulated by 145 RhoGEF and RhoGAP multi-domain proteins in humans. How the Rho signaling system is organized to generate localized responses in cells and prevent their spreading is not understood. Here, we systematically characterized the substrate specificities, localization and interactome of the RhoGEFs/RhoGAPs and revealed their critical role in contextualizing and spatially delimiting Rho signaling. They localize to multiple compartments providing positional information, are extensively interconnected to jointly coordinate their signaling networks and are widely autoinhibited to remain sensitive to local activation. RhoGAPs exhibit lower substrate specificity than RhoGEFs and may contribute to preserving Rho activity gradients. Our approach led us to uncover a multi-RhoGEF complex downstream of G-protein-coupled receptors controlling a Cdc42/RhoA crosstalk. The spatial organization of Rho signaling thus differs from other small GTPases and expands the repertoire of mechanisms governing localized signaling activity.

scholarly journals Loss of CREST leads to neuroinflammatory responses and ALS-like motor defects in mice

2018 ◽  
Author(s):  
Cheng Cheng ◽  
Kan Yang ◽  
Xinwei Wu ◽  
Yuefang Zhang ◽  
Shifang Shan ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Microglial Activation ◽  
Molecular Mechanisms ◽  
Motor Coordination ◽  
Inflammatory Responses ◽  
Late Onset ◽  
Critical Role ◽  
Histone Deacetylation ◽  
Loss Of Function ◽  
Sporadic Als

SUMMARYAmyotrophic lateral sclerosis (ALS) is a late onset neurodegenerative disease with fast progression. Mutations of the CREST gene (also known as SS18L1) are identified in sporadic ALS patients. Whether CREST mutations may lead to ALS remained largely unclear. In this study, we showed that the ALS-related CREST-Q388X mutation exhibited loss-of-function effects. Importantly, we found that microglial activation were prevalent in CREST haploinsufficieny mice and the Q394X mice mimicking the human CREST Q388X mutation. Furthermore, we showed that both CREST haploinsufficieny and the Q394X mice displayed deficits in motor coordination. Finally, we identified the critical role of CREST-BRG1 complex in repressing the expression of immune-related cytokines including Ccl2 and Cxcl10 in neurons, via histone deacetylation, providing the molecular mechanisms underlying inflammatory responses lack of CREST. These findings indicate that elevated inflammatory responses in a subset of ALS may be caused by neuron-derived factors, suggesting potential therapeutic methods through inflammation pathways.In BriefCheng et al. discovered that neuronal loss of CREST reduces the protein level of FUS, de-represses the transcriptional inhibition of chemokine genes which in turn causes microglial activation and proinflammation, and ultimately leads to axonal degeneration of motor neurons and impairment of locomotion.

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