scholarly journals Spatiotemporal Control of Intracellular Membrane Trafficking by Rho GTPases

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1478 ◽  
Author(s):  
Monilola A. Olayioye ◽  
Bettina Noll ◽  
Angelika Hausser
Keyword(s):  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Regulatory Proteins ◽  
Biological Processes ◽  
Intracellular Membrane ◽  
Master Regulators ◽  
Cytoskeletal Remodeling ◽  
Wide Range ◽  
Spatiotemporal Control

As membrane-associated master regulators of cytoskeletal remodeling, Rho GTPases coordinate a wide range of biological processes such as cell adhesion, motility, and polarity. In the last years, Rho GTPases have also been recognized to control intracellular membrane sorting and trafficking steps directly; however, how Rho GTPase signaling is regulated at endomembranes is still poorly understood. In this review, we will specifically address the local Rho GTPase pools coordinating intracellular membrane trafficking with a focus on the endo- and exocytic pathways. We will further highlight the spatiotemporal molecular regulation of Rho signaling at endomembrane sites through Rho regulatory proteins, the GEFs and GAPs. Finally, we will discuss the contribution of dysregulated Rho signaling emanating from endomembranes to the development and progression of cancer.

scholarly journals Identifying Cancer-Relevant Mutations in the DLC START Domain Using Evolutionary and Structure-Function Analyses

2020 ◽  
Vol 21 (21) ◽  
pp. 8175
Author(s):  
Ashton S. Holub ◽  
Renee A. Bouley ◽  
Ruben C. Petreaca ◽  
Aman Y. Husbands
Keyword(s):  
Structure Function ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Structural Level ◽  
Lipid Transfer ◽  
Gtp Hydrolysis ◽  
Conserved Residues ◽  
Wide Range ◽  
Bona Fide ◽  
Start Domain

Rho GTPase signaling promotes proliferation, invasion, and metastasis in a broad spectrum of cancers. Rho GTPase activity is regulated by the deleted in liver cancer (DLC) family of bona fide tumor suppressors which directly inactivate Rho GTPases by stimulating GTP hydrolysis. In addition to a RhoGAP domain, DLC proteins contain a StAR-related lipid transfer (START) domain. START domains in other organisms bind hydrophobic small molecules and can regulate interacting partners or co-occurring domains through a variety of mechanisms. In the case of DLC proteins, their START domain appears to contribute to tumor suppressive activity. However, the nature of this START-directed mechanism, as well as the identities of relevant functional residues, remain virtually unknown. Using the Catalogue of Somatic Mutations in Cancer (COSMIC) dataset and evolutionary and structure-function analyses, we identify several conserved residues likely to be required for START-directed regulation of DLC-1 and DLC-2 tumor-suppressive capabilities. This pan-cancer analysis shows that conserved residues of both START domains are highly overrepresented in cancer cells from a wide range tissues. Interestingly, in DLC-1 and DLC-2, three of these residues form multiple interactions at the tertiary structural level. Furthermore, mutation of any of these residues is predicted to disrupt interactions and thus destabilize the START domain. As such, these mutations would not have emerged from traditional hotspot scans of COSMIC. We propose that evolutionary and structure-function analyses are an underutilized strategy which could be used to unmask cancer-relevant mutations within COSMIC. Our data also suggest DLC-1 and DLC-2 as high-priority candidates for development of novel therapeutics that target their START domain.

scholarly journals Driving Rho GTPase activity in endothelial cells regulates barrier integrity

2010 ◽  
Vol 103 (01) ◽  
pp. 40-55 ◽  
Author(s):  
Cora Beckers ◽  
Victor van Hinsbergh ◽  
Geerten van Nieuw Amerongen
Keyword(s):  
Barrier Function ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Three Dimensional ◽  
Regulatory Proteins ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Barrier Dysfunction ◽  
Gtpase Activation ◽  
The Individual

SummaryIn the past decade understanding of the role of the Rho GTPases RhoA, Rac1 and Cdc42 has been developed from regulatory proteins that regulate specific actin cytoskeletal structures – stress fibers, lamellipodia and filopodia – to complex integrators of cytoskeletal structures that can exert multiple functions depending on the cellular context. Fundamental to these functions are three-dimensional complexes between the individual Rho GTPases, their specific activators (GEFs) and inhibitors (GDIs and GAPs), which greatly outnumber the Rho GTPases themselves, and additional regulatory proteins. By this complexity of regulation different vasoactive mediators can induce various cytoskeletal structures that enable the endothelial cell (EC) to respond adequately. In this review we have focused on this complexity and the consequences of Rho GTPase regulation for endothelial barrier function. The permeability inducers thrombin and VEGF are presented as examples of G-protein coupled receptor- and tyrosine kinase receptormediated Rho GTPase activation, respectively. These mediators induce complex but markedly different networks of activators, inhibitors and effectors of Rho GTPases, which alter the endothelial barrier function. An interesting feature in this regulation is that Rho GTPases often have both barrier-protecting and barrier-disturbing functions. While Rac1 enforces the endothelial junctions, it becomes part of a barrier-disturbing mechanism as activator of reactive oxygen species generating NADPH oxidase. Similarly RhoA is protective under basal conditions, but becomes involved in barrier dysfunction after activation of ECs by thrombin. The challenge and promise lies in unfolding this complex regulation, as this will provide leads for new therapeutic opportunities.

Atypical Rho GTPases RhoD and Rif integrate cytoskeletal dynamics and membrane trafficking

2014 ◽  
Vol 395 (5) ◽  
pp. 477-484 ◽  
Author(s):  
Pontus Aspenström
Keyword(s):  
Cell Migration ◽  
Cell Division ◽  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Intracellular Transport ◽  
Cell Contraction ◽  
Cell Behaviour ◽  
Master Regulators ◽  
Cellular Processes ◽  
Cytoskeletal Dynamics

Abstract The Rho GTPases are essential regulators of basic cellular processes, including cell migration, cell contraction and cell division. Most studies still involve just the three canonical members, RhoA, Rac1 and Cdc42, although the Rho GTPases comprise at least 20 members. The aim of this review is to highlight some of the recent advances in our knowledge regarding the less-studied Rho members, with the focus on RhoD and Rif. The phenotypic alterations to cell behaviour that are triggered by RhoD and Rif suggest that they have unique impacts on cytoskeletal dynamics that distinguish them from the well-studied members of the Rho GTPases. In addition, RhoD has a role in the regulation of intracellular transport of vesicles. Taken together, the available data indicate that RhoD and Rif have functions as master regulators in the integration of cytoskeletal reorganisation and membrane trafficking.

scholarly journals Visualizing endogenous RhoA activity with an improved localization-based, genetically encoded biosensor

2021 ◽  
Author(s):  
Eike K. Mahlandt ◽  
Janine J. G. Arts ◽  
Werner J. van der Meer ◽  
Franka H. van der Linden ◽  
Simon Tol ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Fluorescent Protein ◽  
Rho Gtpase ◽  
Regulatory Proteins ◽  
Fluorescent Biosensors ◽  
Rhoa Activity ◽  
Cellular Processes ◽  
Binding Peptides ◽  
Subcellular Resolution ◽  
G Protein Coupled

AbstractRho GTPases are regulatory proteins, which orchestrate cell features such as morphology, polarity and movement. Therefore, probing Rho GTPase activity is key to understanding processes such as development, cell migration and wound healing. Localization-based reporters for active Rho GTPases are attractive probes to study Rho GTPase-mediated processes, in real time with subcellular resolution in living cells and tissue. Until now, relocation RhoA biosensors seem to only be useful in certain organisms and have not been characterized well. In this paper, we systematically examined the contribution of the fluorescent protein and RhoA binding peptides, on the performance of localization-based sensors. To test the performance, we compared relocation efficiency and specificity in cell-based assays. We identified several improved localization-based, genetically encoded, fluorescent biosensors for detecting endogenous RhoA activity. This enables a broader application of RhoA relocation biosensors, which was demonstrated by using the improved biosensor to visualize RhoA activity, during cell division, during random migration, at the Golgi membrane and induced by G protein-coupled receptor signaling. Due to the improved avidity of the new biosensors for RhoA activity, cellular processes regulated by RhoA can be better understood.Abstract Figure

scholarly journals Rab GTPases: Switching to Human Diseases

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 909 ◽  
Author(s):  
Noemi Antonella Guadagno ◽  
Cinzia Progida
Keyword(s):  
Membrane Trafficking ◽  
Intracellular Transport ◽  
Small Gtpases ◽  
Regulatory Proteins ◽  
Human Diseases ◽  
Rab Proteins ◽  
Rab Gtpases ◽  
Intracellular Membrane ◽  
And Migration ◽  
And Control

Rab proteins compose the largest family of small GTPases and control the different steps of intracellular membrane traffic. More recently, they have been shown to also regulate cell signaling, division, survival, and migration. The regulation of these processes generally occurs through recruitment of effectors and regulatory proteins, which control the association of Rab proteins to membranes and their activation state. Alterations in Rab proteins and their effectors are associated with multiple human diseases, including neurodegeneration, cancer, and infections. This review provides an overview of how the dysregulation of Rab-mediated functions and membrane trafficking contributes to these disorders. Understanding the altered dynamics of Rabs and intracellular transport defects might thus shed new light on potential therapeutic strategies.

scholarly journals The atypical Rho GTPase RhoU interacts with intersectin-2 to regulate endosomal recycling pathways

2020 ◽  
Vol 133 (16) ◽  
pp. jcs234104
Author(s):  
Olga Gubar ◽  
Pauline Croisé ◽  
Sergii Kropyvko ◽  
Tetyana Gryaznova ◽  
Petra Tóth ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Vesicular Trafficking ◽  
Recycling Endosomes ◽  
Vesicle Recycling ◽  
Binding Partners ◽  
Endosomal Recycling ◽  
Early Endosomes ◽  
And Migration

ABSTRACTRho GTPases play a key role in various membrane trafficking processes. RhoU is an atypical small Rho GTPase related to Rac/Cdc42, which possesses unique N- and C-terminal domains that regulate its function and its subcellular localization. RhoU localizes at the plasma membrane, on endosomes and in cell adhesion structures where it governs cell signaling, differentiation and migration. However, despite its endomembrane localization, RhoU function in vesicular trafficking has been unexplored. Here, we identified intersectins (ITSNs) as new binding partners for RhoU and showed that the second PxxP motif at the N terminus of RhoU mediated interactions with the SH3 domains of ITSNs. To evaluate the function of RhoU and ITSNs in vesicular trafficking, we used fluorescent transferrin as a cargo for uptake experiments. We showed that silencing of either RhoU or ITSN2, but not ITSN1, increased transferrin accumulation in early endosomes, resulting from a defect in fast vesicle recycling. Concomitantly, RhoU and ITSN2 colocalized to a subset of Rab4-positive vesicles, suggesting that a RhoU–ITSN2 interaction may occur on fast recycling endosomes to regulate the fate of vesicular cargos.

scholarly journals Plasma membrane nano-organization specifies phosphoinositide effects on Rho-GTPases and actin dynamics in tobacco pollen tubes

2020 ◽  
Author(s):  
Marta Fratini ◽  
Praveen Krishnamoorthy ◽  
Irene Stenzel ◽  
Mara Riechmann ◽  
Kirsten Bacia ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Pollen Tubes ◽  
Actin Dynamics ◽  
Tobacco Pollen ◽  
Dual Distribution ◽  
Cytoskeletal Dynamics

AbstractPollen tube growth requires coordination of cytoskeletal dynamics and apical secretion. The regulatory phospholipid, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is enriched in the subapical plasma membrane of pollen tubes and can influence both actin dynamics and secretion. How alternative PtdIns(4,5)P2-effects are specified is unclear. Spinning disc microscopy (SD) reveals dual distribution of a fluorescent PtdIns(4,5)P2-reporter in dynamic plasma membrane nanodomains vs. apparent diffuse membrane labelling, consistent with spatially distinct coexisting pools of PtdIns(4,5)P2. Several PI4P 5-kinases (PIP5Ks) can generate PtdIns(4,5)P2 in pollen tubes. Despite localizing to one membrane region, AtPIP5K2 and NtPIP5K6 display distinctive overexpression effects on cell morphologies, respectively related to altered actin dynamics or membrane trafficking. When analyzed by SD, AtPIP5K2-EYFP associated with nanodomains, whereas NtPIP5K6-EYFP localized diffusely. Chimeric AtPIP5K2 and NtPIP5K6 variants with reciprocally swapped membrane-associating domains evoked reciprocally shifted effects on cell morphology upon overexpression. Overall, PI4P 5-kinase variants targeted to nanodomains stabilized actin, suggesting a specific function of PtdIns(4,5)P2-nanodomains. A distinct role of nanodomain-associated AtPIP5K2 in actin regulation is further supported by proximity to and interaction with the Rho-GTPase NtRac5, and by functional interplay with elements of ROP-signalling. Plasma membrane nano-organization may thus aid the specification of PtdIns(4,5)P2-functions to coordinate cytoskeletal dynamics and secretion in pollen tubes.

scholarly journals The Proteasomal Deubiquitinating Enzyme PSMD14 Regulates Macroautophagy by Controlling Golgi-to-ER Retrograde Transport

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 777 ◽  
Author(s):  
Hianara A Bustamante ◽  
Karina Cereceda ◽  
Alexis E González ◽  
Guillermo E Valenzuela ◽  
Yorka Cheuquemilla ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Membrane Trafficking ◽  
Retrograde Transport ◽  
Deubiquitinating Enzyme ◽  
Biological Processes ◽  
Intracellular Membrane ◽  
Pharmacological Inhibition ◽  
Protein Membrane ◽  
A Subunit

Ubiquitination regulates several biological processes, however the role of specific members of the ubiquitinome on intracellular membrane trafficking is not yet fully understood. Here, we search for ubiquitin-related genes implicated in protein membrane trafficking performing a High-Content siRNA Screening including 1187 genes of the human “ubiquitinome” using amyloid precursor protein (APP) as a reporter. We identified the deubiquitinating enzyme PSMD14, a subunit of the 19S regulatory particle of the proteasome, specific for K63-Ub chains in cells, as a novel regulator of Golgi-to-endoplasmic reticulum (ER) retrograde transport. Silencing or pharmacological inhibition of PSMD14 with Capzimin (CZM) caused a robust increase in APP levels at the Golgi apparatus and the swelling of this organelle. We showed that this phenotype is the result of rapid inhibition of Golgi-to-ER retrograde transport, a pathway implicated in the early steps of the autophagosomal formation. Indeed, we observed that inhibition of PSMD14 with CZM acts as a potent blocker of macroautophagy by a mechanism related to the retention of Atg9A and Rab1A at the Golgi apparatus. As pharmacological inhibition of the proteolytic core of the 20S proteasome did not recapitulate these effects, we concluded that PSMD14, and the K63-Ub chains, act as a crucial regulatory factor for macroautophagy by controlling Golgi-to-ER retrograde transport.

scholarly journals The atypical Rho GTPase RhoU interacts with Intersectin-2 to regulate endosomal recycling pathways

2019 ◽  
Author(s):  
Olga Gubar ◽  
Pauline Croisé ◽  
Sergii Kropyvko ◽  
Tetyana Gryaznova ◽  
Petra Toth ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Cell Signalling ◽  
Vesicular Trafficking ◽  
Recycling Endosomes ◽  
Vesicle Recycling ◽  
Endosomal Recycling ◽  
Early Endosomes ◽  
And Migration

AbstractRho GTPases play a key role in various membrane trafficking processes. RhoU is an atypical small Rho GTPase related to Rac/Cdc42 which possesses unique N- and C-terminal domains that regulate its function and its subcellular localization. RhoU localized at the plasma membrane, on endosomes and in cell adhesion structures where it governs cell signalling, differentiation and migration. However, despite its endomembrane localization, RhoU function in vesicular trafficking has been unexplored. Here, we identified intersectins (ITSNs) as new binding partners for RhoU and showed that the second PxxP motif at the N-terminus of RhoU mediated interactions with SH3 domains of ITSNs. To evaluate the function of RhoU and ITSNs in vesicular trafficking, we used fluorescent transferrin as a cargo for uptake experiments. We showed that silencing of either RhoU or ITSN2, but not ITSN1 increased transferrin accumulation in early endosomes resulting from defect in fast vesicle recycling. Concomitantly, RhoU and ITSN2 colocalized to a subset of Rab4-positive vesicles suggesting that RhoU-ITSN2 interaction may occur on fast recycling endosomes to regulate the fate of vesicular cargos.

scholarly journals Rab GTPases in Parkinson’s disease: a primer

2021 ◽  
Author(s):  
Antonio Jesús Lara Ordóñez ◽  
Rachel Fasiczka ◽  
Yahaira Naaldijk ◽  
Sabine Hilfiker
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Membrane Trafficking ◽  
Protein Function ◽  
Current Knowledge ◽  
Rab Gtpases ◽  
Intracellular Membrane ◽  
Master Regulators ◽  
Rab Protein ◽  
Physiological Properties

Abstract Parkinson’s disease is a prominent and debilitating movement disorder characterized by the death of vulnerable neurons which share a set of structural and physiological properties. Over the recent years, increasing evidence indicates that Rab GTPases can directly as well as indirectly contribute to the cellular alterations leading to PD. Rab GTPases are master regulators of intracellular membrane trafficking events, and alterations in certain membrane trafficking steps can be particularly disruptive to vulnerable neurons. Here, we describe current knowledge on the direct links between altered Rab protein function and PD pathomechanisms.

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