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

2014 ◽  
Vol 395 (5) ◽  
pp. 477-484 ◽  
Author(s):  
Pontus Aspenström

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.

2012 ◽  
Vol 23 (24) ◽  
pp. 4807-4819 ◽  
Author(s):  
Annica K. B. Gad ◽  
Vishal Nehru ◽  
Aino Ruusala ◽  
Pontus Aspenström

The Rho GTPases have mainly been studied in association with their roles in the regulation of actin filament organization. These studies have shown that the Rho GTPases are essential for basic cellular processes, such as cell migration, contraction, and division. In this paper, we report that RhoD has a role in the organization of actin dynamics that is distinct from the roles of the better-studied Rho members Cdc42, RhoA, and Rac1. We found that RhoD binds the actin nucleation–promoting factor WASp homologue associated with actin Golgi membranes and microtubules (WHAMM), as well as the related filamin A–binding protein FILIP1. Of these two RhoD-binding proteins, WHAMM was found to bind to the Arp2/3 complex, while FILIP1 bound filamin A. WHAMM was found to act downstream of RhoD in regulating cytoskeletal dynamics. In addition, cells treated with small interfering RNAs for RhoD and WHAMM showed increased cell attachment and decreased cell migration. These major effects on cytoskeletal dynamics indicate that RhoD and its effectors control vital cytoskeleton-driven cellular processes. In agreement with this notion, our data suggest that RhoD coordinates Arp2/3-dependent and FLNa-dependent mechanisms to control the actin filament system, cell adhesion, and cell migration.


Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1037 ◽  
Author(s):  
Cho ◽  
Kim ◽  
Baek ◽  
Kim ◽  
Lee

Rho GDP dissociation inhibitors (RhoGDIs) play important roles in various cellular processes, including cell migration, adhesion, and proliferation, by regulating the functions of the Rho GTPase family. Dissociation of Rho GTPases from RhoGDIs is necessary for their spatiotemporal activation and is dynamically regulated by several mechanisms, such as phosphorylation, sumoylation, and protein interaction. The expression of RhoGDIs has changed in many human cancers and become associated with the malignant phenotype, including migration, invasion, metastasis, and resistance to anticancer agents. Here, we review how RhoGDIs control the function of Rho GTPases by regulating their spatiotemporal activity and describe the regulatory mechanisms of the dissociation of Rho GTPases from RhoGDIs. We also discuss the role of RhoGDIs in cancer progression and their potential uses for therapeutic intervention.


Author(s):  
Fabienne Podieh ◽  
Peter L. Hordijk

Cullin3-based ubiquitin E3 ligases induce ubiquitination of substrates leading to their proteasomal or lysosomal degradation. BTB proteins serve as adaptors by binding to Cullin3 and recruiting substrate proteins, which enables specific recognition of a broad spectrum of targets. Hence, Cullin3 and its adaptors are involved in myriad cellular processes and organ functions. Cullin3-based ubiquitin E3 ligase complexes target small GTPases of the Rho subfamily, which are key regulators of cytoskeletal dynamics and cell adhesion. In this mini review, we discuss recent insights in Cullin3-mediated regulation of Rho GTPases and their impact on cellular function and disease. Intriguingly, upstream regulators of Rho GTPases are targeted by Cullin3 complexes as well. Thus, Rho GTPase signaling is regulated by Cullin3 on multiple levels. In addition, we address current knowledge of Cullin3 in regulating vascular function, focusing on its prominent role in endothelial barrier function, angiogenesis and the regulation of blood pressure.


Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1478 ◽  
Author(s):  
Monilola A. Olayioye ◽  
Bettina Noll ◽  
Angelika Hausser

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.


2019 ◽  
Vol 294 (28) ◽  
pp. 10954-10968 ◽  
Author(s):  
Tao Tao ◽  
Jie Sun ◽  
Yajing Peng ◽  
Yeqiong Li ◽  
Pei Wang ◽  
...  

Neurite outgrowth requires coordinated cytoskeletal rearrangements in the growth cone and directional membrane delivery from the neuronal soma. As an essential Rho guanine nucleotide exchange factor (GEF), TRIO is necessary for cytoskeletal dynamics during neurite outgrowth, but its participation in the membrane delivery is unclear. Using co-localization studies, live-cell imaging, and fluorescence recovery after photobleaching analysis, along with neurite outgrowth assay and various biochemical approaches, we here report that in mouse cerebellar granule neurons, TRIO protein pools at the Golgi and regulates membrane trafficking by controlling the directional maintenance of both RAB8 (member RAS oncogene family 8)– and RAB10-positive membrane vesicles. We found that the spectrin repeats in Golgi-resident TRIO confer RAB8 and RAB10 activation by interacting with and activating the RAB GEF RABIN8. Constitutively active RAB8 or RAB10 could partially restore the neurite outgrowth of TRIO-deficient cerebellar granule neurons, suggesting that TRIO-regulated membrane trafficking has an important functional role in neurite outgrowth. Our results also suggest cross-talk between Rho GEF and Rab GEF in controlling both cytoskeletal dynamics and membrane trafficking during neuronal development. They further highlight how protein pools localized to specific organelles regulate crucial cellular activities and functions. In conclusion, our findings indicate that TRIO regulates membrane trafficking during neurite outgrowth in coordination with its GEF-dependent function in controlling cytoskeletal dynamics via Rho GTPases.


2019 ◽  
Author(s):  
Jona Mijalkovic ◽  
Erwin J.G. Peterman

AbstractCytoplasmic dyneins play a role in a myriad of cellular processes, such as retrograde intracellular transport and cell division. Small-molecule cytoplasmic dynein antagonists, ciliobrevins, have recently been developed as tools to acutely probe cytoplasmic dynein function. Although widely used to investigate cytoplasmic dynein 1, far fewer studies explore the effect of ciliobrevin on cytoplasmic dynein 2 or IFT dynein. Here, we use ciliobrevin A to partially disrupt IFT dynein in the chemosensory cilia of living C. elegans. Acute, low-concentration ciliobrevin treatment results in shortening of cilia and reduction of transport velocity in both directions. After longer exposure to ciliobrevin, we find concentration-dependent motor accumulations and axonemal deformations. We propose that maintenance of ciliary length requires a high fraction of active IFT-dynein motors, while structural integrity can be preserved by only a few active motors.


2013 ◽  
Vol 368 (1629) ◽  
pp. 20130013 ◽  
Author(s):  
Elvira Infante ◽  
Anne J. Ridley

Leucocytes migrate into and out of blood vessels at multiple points during their development and maturation, and during immune surveillance. In response to tissue damage and infection, they are rapidly recruited through the endothelium lining blood vessels into the tissues. Leukaemia cells also move in and out of the bloodstream during leukaemia progression. Rho GTPases are intracellular signalling proteins that regulate cytoskeletal dynamics and are key coordinators of cell migration. Here, we describe how different members of the Rho GTPase family act in leucocytes and leukaemia cells to regulate steps of transendothelial migration. We discuss how inhibitors of Rho signalling could be used to reduce leucocyte or leukaemia cell entry into tissues.


2008 ◽  
Vol 180 (4) ◽  
pp. 729-737 ◽  
Author(s):  
Katharina A. Dragestein ◽  
Wiggert A. van Cappellen ◽  
Jeffrey van Haren ◽  
George D. Tsibidis ◽  
Anna Akhmanova ◽  
...  

Microtubule (MT) plus end–tracking proteins (+TIPs) specifically recognize the ends of growing MTs. +TIPs are involved in diverse cellular processes such as cell division, cell migration, and cell polarity. Although +TIP tracking is important for these processes, the mechanisms underlying plus end specificity of mammalian +TIPs are not completely understood. Cytoplasmic linker protein 170 (CLIP-170), the prototype +TIP, was proposed to bind to MT ends with high affinity, possibly by copolymerization with tubulin, and to dissociate seconds later. However, using fluorescence-based approaches, we show that two +TIPs, CLIP-170 and end-binding protein 3 (EB3), turn over rapidly on MT ends. Diffusion of CLIP-170 and EB3 appears to be rate limiting for their binding to MT plus ends. We also report that the ends of growing MTs contain a surplus of sites to which CLIP-170 binds with relatively low affinity. We propose that the observed loss of fluorescent +TIPs at plus ends does not reflect the behavior of single molecules but is a result of overall structural changes of the MT end.


2012 ◽  
Vol 23 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Heidi Hehnly ◽  
Stephen Doxsey

Cell polarity is important for a number of processes, from chemotaxis to embryogenesis. Recent studies suggest a new role for polarity in the orchestration of events during the final cell separation step of cell division called abscission. Abscission shares several features with cell polarization, including rearrangement of phosphatidylinositols, reorganization of microtubules, and trafficking of exocyst-associated membranes. Here we focus on how the canonical pathways for cell polarization and cell migration may play a role in spatiotemporal membrane trafficking events required for the final stages of cytokinesis.


Author(s):  
Marta Fratini ◽  
Praveen Krishnamoorthy ◽  
Irene Stenzel ◽  
Mara Riechmann ◽  
Kirsten Bacia ◽  
...  

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.


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