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Bajar BT, Guan X, Lam A, Lin MZ, Yasuda R, Laviv T, Chu J. FRET Imaging of Rho GTPase Activity with Red Fluorescent Protein-Based FRET Pairs. Methods Mol Biol 2022; 2438:31-43. [PMID: 35147933 PMCID: PMC9976416 DOI: 10.1007/978-1-0716-2035-9_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
With the development of fluorescent proteins (FPs) and advanced optical microscopy techniques, Förster or fluorescence resonance energy transfer (FRET) has become a powerful tool for real-time noninvasive visualization of a variety of biological processes, including kinase activities, with high spatiotemporal resolution in living cells and organisms. FRET can be detected in appropriately configured microscopes as changes in fluorescence intensity, lifetime, and anisotropy. Here, we describe the preparation of samples expressing FP-based FRET sensors for RhoA kinase, intensity- and lifetime-based FRET imaging, and postimaging data analysis.
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Affiliation(s)
- Bryce T Bajar
- Department of Biological Chemistry, Medical Scientist Training Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Xinmeng Guan
- Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology & Center for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Amy Lam
- Departments of Neurobiology and Bioengineering, Stanford University, Stanford, CA, USA
| | - Michael Z Lin
- Departments of Neurobiology and Bioengineering, Stanford University, Stanford, CA, USA
| | - Ryohei Yasuda
- Neuronal Signal Transduction Group, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA
| | - Tal Laviv
- Neuronal Signal Transduction Group, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA.
- Department of Physiology and Pharmacology, Sackler School of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Jun Chu
- Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology & Center for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
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2
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Wu YW. Spatiotemporal Imaging of Small GTPase Activity Using Conformational Sensors for GTPase Activity (COSGA). METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2262:259-267. [PMID: 33977482 DOI: 10.1007/978-1-0716-1190-6_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Small GTPases cycle between active GTP bound and inactive GDP bound forms in live cells. They act as molecular switches and regulate diverse cellular processes at different times and locations in the cell. Spatiotemporal visualization of their activity provides important insights into dynamics of cellular signaling. Conformational sensors for GTPase activity (COSGAs) are based on the conserved GTPase fold and have been used as a versatile approach for imaging small GTPase activity in the cell. Conformational changes upon GDP/GTP binding can be visualized directly in solution, on beads, or in live cells using COSGA by fluorescence lifetime imaging microscopy (FLIM) technique. Herein, we describe the construction of COSGA for imaging K-Ras GTPase activity in live cells.
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Affiliation(s)
- Yao-Wen Wu
- Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.
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3
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Tuba Activates Cdc42 during Neuronal Polarization Downstream of the Small GTPase Rab8a. J Neurosci 2021; 41:1636-1649. [PMID: 33478991 DOI: 10.1523/jneurosci.0633-20.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 11/21/2022] Open
Abstract
The acquisition of neuronal polarity is a complex molecular process that depends on changes in cytoskeletal dynamics and directed membrane traffic, regulated by the Rho and Rab families of small GTPases, respectively. However, during axon specification, a molecular link that couples these protein families has yet to be identified. In this paper, we describe a new positive feedback loop between Rab8a and Cdc42, coupled by Tuba, a Cdc42-specific guanine nucleotide-exchange factor (GEF), that ensures a single axon generation in rodent hippocampal neurons from embryos of either sex. Accordingly, Rab8a or Tuba gain-of-function generates neurons with supernumerary axons whereas Rab8a or Tuba loss-of-function abrogated axon specification, phenocopying the well-established effect of Cdc42 on neuronal polarity. Although Rab8 and Tuba do not interact physically, the activity of Rab8 is essential to generate a proximal to distal axonal gradient of Tuba in cultured neurons. Tuba-associated and Rab8a-associated polarity defects are also evidenced in vivo, since dominant negative (DN) Rab8a or Tuba knock-down impairs cortical neuronal migration in mice. Our results suggest that Tuba coordinates directed vesicular traffic and cytoskeleton dynamics during neuronal polarization.SIGNIFICANCE STATEMENT The morphologic, biochemical, and functional differences observed between axon and dendrites, require dramatic structural changes. The extension of an axon that is 1 µm in diameter and grows at rates of up to 500 µm/d, demands the confluence of two cellular processes: directed membrane traffic and fine-tuned cytoskeletal dynamics. In this study, we show that both processes are integrated in a positive feedback loop, mediated by the guanine nucleotide-exchange factor (GEF) Tuba. Tuba connects the activities of the Rab GTPase Rab8a and the Rho GTPase Cdc42, ensuring the generation of a single axon in cultured hippocampal neurons and controlling the migration of cortical neurons in the developing brain. Finally, we provide compelling evidence that Tuba is the GEF that mediates Cdc42 activation during the development of neuronal polarity.
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4
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Hatanaka Y, Hirata T. How Do Cortical Excitatory Neurons Terminate Their Migration at the Right Place? Critical Roles of Environmental Elements. Front Cell Dev Biol 2020; 8:596708. [PMID: 33195277 PMCID: PMC7644909 DOI: 10.3389/fcell.2020.596708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/05/2020] [Indexed: 11/13/2022] Open
Abstract
Interactions between neurons and their environment are crucial for proper termination of neuronal migration during brain development. In this review, we first introduce the migration behavior of cortical excitatory neurons from neurogenesis to migration termination, focusing on morphological and behavioral changes. We then describe possible requirements for environmental elements, including extracellular matrix proteins and Cajal–Retzius cells in the marginal zone, radial glial cells, and neighboring neurons, to ensure proper migration termination of these neurons at their final destinations. The requirements appear to be highly linked to sequential and/or concurrent changes in adhesiveness of migrating neurons and their surroundings, which allow the neurons to reach their final positions, detach from substrates, and establish stable laminar structures.
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Affiliation(s)
- Yumiko Hatanaka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Tatsumi Hirata
- Brain Function Laboratory, National Institute of Genetics, Mishima, Japan.,Department of Genetics, Graduate School of Life Sciences, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
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5
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Aβ modulates actin cytoskeleton via SHIP2-mediated phosphoinositide metabolism. Sci Rep 2019; 9:15557. [PMID: 31664099 PMCID: PMC6820556 DOI: 10.1038/s41598-019-51914-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/02/2019] [Indexed: 12/22/2022] Open
Abstract
Emerging evidences suggest that phospholipid metabolism is altered in Alzheimer’s disease (AD), but molecular mechanisms on how this affects neurodegeneration in AD is poorly understood. SHIP2 is a phosphoinositide-metabolizing enzyme, which dephosphorylates PI(3,4,5)P3 resulting to PI(3,4)P2, and it has been recently shown that Aβ directly increases the activity of SHIP2. Here we monitored, utilizing fluorescent SHIP2 biosensor, real-time increase of PI(3,4)P2-containing vesicles in HT22 cells treated with Aβ. Interestingly, PI(3,4)P2 is accumulated at late endosomes and lysosomal vesicles. We further discovered that ARAP3 can be attracted to PI(3,4)P2-positive mature endosomes via its PH domain and this facilitates the degradation of ARAP3. The reduced level of ARAP3 then causes RhoA hyperactivation and filamentous actin, which are critical for neurodegeneration in AD. These results provide a novel molecular link between Aβ and actin disruption through dysregulated phosphoinositide metabolism, and the SHIP2-PI(3,4)P2-ARAP3-RhoA signaling pathway can be considered as new therapeutic targets for synaptic dysfunctions in Alzheimer’s disease.
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6
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Duman JG, Mulherkar S, Tu YK, Erikson KC, Tzeng CP, Mavratsas VC, Ho TSY, Tolias KF. The adhesion-GPCR BAI1 shapes dendritic arbors via Bcr-mediated RhoA activation causing late growth arrest. eLife 2019; 8:47566. [PMID: 31461398 PMCID: PMC6713510 DOI: 10.7554/elife.47566] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/03/2019] [Indexed: 12/17/2022] Open
Abstract
Dendritic arbor architecture profoundly impacts neuronal connectivity and function, and aberrant dendritic morphology characterizes neuropsychiatric disorders. Here, we identify the adhesion-GPCR BAI1 as an important regulator of dendritic arborization. BAI1 loss from mouse or rat hippocampal neurons causes dendritic hypertrophy, whereas BAI1 overexpression precipitates dendrite retraction. These defects specifically manifest as dendrites transition from growth to stability. BAI1-mediated growth arrest is independent of its Rac1-dependent synaptogenic function. Instead, BAI1 couples to the small GTPase RhoA, driving late RhoA activation in dendrites coincident with growth arrest. BAI1 loss lowers RhoA activation and uncouples it from dendrite dynamics, causing overgrowth. None of BAI1's known downstream effectors mediates BAI1-dependent growth arrest. Rather, BAI1 associates with the Rho-GTPase regulatory protein Bcr late in development and stimulates its cryptic RhoA-GEF activity, which functions together with its Rac1-GAP activity to terminate arborization. Our results reveal a late-acting signaling pathway mediating a key transition in dendrite development.
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Affiliation(s)
- Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Yen-Kuei Tu
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, United States
| | - Kelly C Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Christopher P Tzeng
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Vasilis C Mavratsas
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Rice University, Houston, United States
| | - Tammy Szu-Yu Ho
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, United States.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
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7
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Bajanca F, Gouignard N, Colle C, Parsons M, Mayor R, Theveneau E. In vivo topology converts competition for cell-matrix adhesion into directional migration. Nat Commun 2019; 10:1518. [PMID: 30944331 PMCID: PMC6447549 DOI: 10.1038/s41467-019-09548-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 03/11/2019] [Indexed: 12/14/2022] Open
Abstract
When migrating in vivo, cells are exposed to numerous conflicting signals: chemokines, repellents, extracellular matrix, growth factors. The roles of several of these molecules have been studied individually in vitro or in vivo, but we have yet to understand how cells integrate them. To start addressing this question, we used the cephalic neural crest as a model system and looked at the roles of its best examples of positive and negative signals: stromal-cell derived factor 1 (Sdf1/Cxcl12) and class3-Semaphorins. Here we show that Sdf1 and Sema3A antagonistically control cell-matrix adhesion via opposite effects on Rac1 activity at the single cell level. Directional migration at the population level emerges as a result of global Semaphorin-dependent confinement and broad activation of adhesion by Sdf1 in the context of a biased Fibronectin distribution. These results indicate that uneven in vivo topology renders the need for precise distribution of secreted signals mostly dispensable.
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Affiliation(s)
- Fernanda Bajanca
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Nadège Gouignard
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Charlotte Colle
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Maddy Parsons
- Kings College London, Randall Centre for Cell and Molecular Biophysics Room 3.22B, New Hunts House, Guys Campus, London, SE1 1UL, UK
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Eric Theveneau
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse, Cedex 09, France.
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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8
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 PMCID: PMC7462118 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 302] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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9
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Morishita S, Wada N, Fukuda M, Nakamura T. Rab5 activation on macropinosomes requires ALS2, and subsequent Rab5 inactivation through ALS2 detachment requires active Rab7. FEBS Lett 2018; 593:230-241. [PMID: 30485418 DOI: 10.1002/1873-3468.13306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 11/09/2018] [Accepted: 11/21/2018] [Indexed: 11/08/2022]
Abstract
Macropinocytosis is a nonspecific bulk uptake of extracellular fluid. During endosome maturation, the Rab5-to-Rab7 switch machinery executes the conversion from early to late endosomes. However, how the Rab switch works during macropinosome maturation remains unclear. Here, we elucidate the Rab switch machinery in macropinosome maturation using Förster resonance energy transfer imaging. Rab5 is activated and concurrently recruited to macropinosomes during ruffle closure. ALS2 depletion abolishes transient Rab5 activation on macropinosomes, while ALS2 is recruited to macropinosomes simultaneously with Rab5 activation. Thus, we conclude ALS2 activates Rab5 on macropinosomes. The absence of active Rab7 prolongs ALS2 presence and Rab5 activation on macropinosomes, indicating that active Rab7 is necessary for Rab5 inactivation through ALS2 dissociation and plays key roles in the Rab switch on macropinosomes.
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Affiliation(s)
- So Morishita
- Division of Biosignaling, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Japan
| | - Naoyuki Wada
- Department of Applied Biological Science, Tokyo University of Science, Noda, Japan
| | - Mitsunori Fukuda
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Takeshi Nakamura
- Division of Biosignaling, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Japan
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10
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Ulc A, Zeug A, Bauch J, van Leeuwen S, Kuhlmann T, ffrench-Constant C, Ponimaskin E, Faissner A. The guanine nucleotide exchange factor Vav3 modulates oligodendrocyte precursor differentiation and supports remyelination in white matter lesions. Glia 2018; 67:376-392. [DOI: 10.1002/glia.23548] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Annika Ulc
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Andre Zeug
- Cellular Neurophysiology, Centre for Physiology; Hannover Medical School; Hannover Germany
| | - Juliane Bauch
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Simon van Leeuwen
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Tanja Kuhlmann
- Institute of Neuropathology; University Hospital Münster; Germany
| | | | - Evgeni Ponimaskin
- Cellular Neurophysiology, Centre for Physiology; Hannover Medical School; Hannover Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
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11
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Fort L, Batista JM, Thomason PA, Spence HJ, Whitelaw JA, Tweedy L, Greaves J, Martin KJ, Anderson KI, Brown P, Lilla S, Neilson MP, Tafelmeyer P, Zanivan S, Ismail S, Bryant DM, Tomkinson NCO, Chamberlain LH, Mastick GS, Insall RH, Machesky LM. Fam49/CYRI interacts with Rac1 and locally suppresses protrusions. Nat Cell Biol 2018; 20:1159-1171. [PMID: 30250061 PMCID: PMC6863750 DOI: 10.1038/s41556-018-0198-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/20/2018] [Indexed: 11/09/2022]
Abstract
Actin-based protrusions are reinforced through positive feedback, but it is unclear what restricts their size, or limits positive signals when they retract or split. We identify an evolutionarily conserved regulator of actin-based protrusion: CYRI (CYFIP-related Rac interactor) also known as Fam49 (family of unknown function 49). CYRI binds activated Rac1 via a domain of unknown function (DUF1394) shared with CYFIP, defining DUF1394 as a Rac1-binding module. CYRI-depleted cells have broad lamellipodia enriched in Scar/WAVE, but reduced protrusion-retraction dynamics. Pseudopods induced by optogenetic Rac1 activation in CYRI-depleted cells are larger and longer lived. Conversely, CYRI overexpression suppresses recruitment of active Scar/WAVE to the cell edge, resulting in short-lived, unproductive protrusions. CYRI thus focuses protrusion signals and regulates pseudopod complexity by inhibiting Scar/WAVE-induced actin polymerization. It thus behaves like a 'local inhibitor' as predicted in widely accepted mathematical models, but not previously identified in cells. CYRI therefore regulates chemotaxis, cell migration and epithelial polarization by controlling the polarity and plasticity of protrusions.
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Affiliation(s)
- Loic Fort
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - José Miguel Batista
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | | | | | | | | | - Jennifer Greaves
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Kurt I Anderson
- CRUK Beatson Institute, Glasgow, UK
- Francis Crick Institute, London, UK
| | | | | | | | | | | | - Shehab Ismail
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - David M Bryant
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Nicholas C O Tomkinson
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK
| | - Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Robert H Insall
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
| | - Laura M Machesky
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
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12
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Broussard JA, Green KJ. Research Techniques Made Simple: Methodology and Applications of Förster Resonance Energy Transfer (FRET) Microscopy. J Invest Dermatol 2017; 137:e185-e191. [PMID: 29055415 DOI: 10.1016/j.jid.2017.09.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/23/2017] [Accepted: 09/05/2017] [Indexed: 01/11/2023]
Abstract
Classical biochemical techniques have contributed a great deal to our understanding of the mechanisms regulating fundamental biological processes. However, these approaches are typically end-point, population-based assays and are often insufficient in examining transient molecular events. Förster resonance energy transfer (FRET) microscopy is a powerful technique capable of investigating dynamic interactions between proteins and a plethora of biochemical signaling events based on the development of specific biosensors. This technique exploits the principle that when FRET occurs, energy from a donor fluorophore is transferred to an acceptor fluorophore only when certain conditions are met. These include dependence on both distance and fluorophore orientation. In this article, applications of FRET microscopy to protein interactions and modifications are discussed, and examples are given of the types of biosensors that can be developed. There are a number of methods to measure FRET. The most common modalities and specific advantages and shortcomings for each are reviewed. Finally, general considerations and guidelines for choosing a method are discussed.
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Affiliation(s)
- Joshua A Broussard
- Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA; Department of Dermatology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Kathleen J Green
- Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA; Department of Dermatology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA.
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13
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Koinuma S, Takeuchi K, Wada N, Nakamura T. cAMP-induced activation of protein kinase A and p190B RhoGAP mediates down-regulation of TC10 activity at the plasma membrane and neurite outgrowth. Genes Cells 2017; 22:953-967. [PMID: 29072354 DOI: 10.1111/gtc.12538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/08/2017] [Indexed: 12/14/2022]
Abstract
Cyclic AMP plays a pivotal role in neurite growth. During outgrowth, a trafficking system supplies membrane at growth cones. However, the cAMP-induced signaling leading to the regulation of membrane trafficking remains unknown. TC10 is a Rho family GTPase that is essential for specific types of vesicular trafficking. Recent studies have shown a role of TC10 in neurite growth in NGF-treated PC12 cells. Here, we investigated a mechanical linkage between cAMP and TC10 in neuritogenesis. Plasmalemmal TC10 activity decreased abruptly after cAMP addition in neuronal cells. TC10 was locally inactivated at extending neurite tips in cAMP-treated PC12 cells. TC10 depletion led to a decrease in cAMP-induced neurite outgrowth. Constitutively active TC10 could not rescue this growth reduction, supporting our model for a role of GTP hydrolysis of TC10 in neuritogenesis by accelerating vesicle fusion. The cAMP-induced TC10 inactivation was mediated by PKA. Considering cAMP-induced RhoA inactivation, we found that p190B, but not p190A, mediated inactivation of TC10 and RhoA. Upon cAMP treatment, p190B was recruited to the plasma membrane. STEF depletion and Rac1-N17 expression reduced cAMP-induced TC10 inactivation. Together, the PKA-STEF-Rac1-p190B pathway leading to inactivation of TC10 and RhoA at the plasma membrane plays an important role in cAMP-induced neurite outgrowth.
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Affiliation(s)
- Shingo Koinuma
- Division of Biosignaling, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | - Kohei Takeuchi
- Division of Biosignaling, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | - Naoyuki Wada
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba, Japan
| | - Takeshi Nakamura
- Division of Biosignaling, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda, Chiba, Japan
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14
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Bhattacharyya S, Jean-Alphonse FG, Raghavan V, McGarvey JC, Rbaibi Y, Vilardaga JP, Carattino MD, Weisz OA. Cdc42 activation couples fluid shear stress to apical endocytosis in proximal tubule cells. Physiol Rep 2017; 5:5/19/e13460. [PMID: 29038362 PMCID: PMC5641940 DOI: 10.14814/phy2.13460] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 08/30/2017] [Accepted: 09/04/2017] [Indexed: 11/24/2022] Open
Abstract
Cells lining the kidney proximal tubule (PT) respond to acute changes in glomerular filtration rate and the accompanying fluid shear stress (FSS) to regulate reabsorption of ions, glucose, and other filtered molecules and maintain glomerulotubular balance. Recently, we discovered that exposure of PT cells to FSS also stimulates an increase in apical endocytic capacity (Raghavan et al. PNAS, 111:8506–8511, 2014). We found that FSS triggered an increase in intracellular Ca2+ concentration ([Ca2+]i) that required release of extracellular ATP and the presence of primary cilia. In this study, we elucidate steps downstream of the increase in [Ca2+]i that link FSS‐induced calcium increase to increased apical endocytic capacity. Using an intramolecular FRET probe, we show that activation of Cdc42 is a necessary step in the FSS‐stimulated apical endocytosis cascade. Cdc42 activation requires the primary cilia and the FSS‐mediated increase in [Ca2+]i. Moreover, Cdc42 activity and FSS‐stimulated endocytosis are coordinately modulated by activators and inhibitors of calmodulin. Together, these data suggest a mechanism by which PT cell exposure to FSS is translated into enhanced endocytic uptake of filtered molecules.
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Affiliation(s)
- Sohinee Bhattacharyya
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Frédéric G Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Venkatesan Raghavan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jennifer C McGarvey
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Marcelo D Carattino
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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15
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Morris DC, Popp JL, Tang LK, Gibbs HC, Schmitt E, Chaki SP, Bywaters BC, Yeh AT, Porter WW, Burghardt RC, Barhoumi R, Rivera GM. Nck deficiency is associated with delayed breast carcinoma progression and reduced metastasis. Mol Biol Cell 2017; 28:3500-3516. [PMID: 28954862 PMCID: PMC5683761 DOI: 10.1091/mbc.e17-02-0106] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 09/15/2017] [Accepted: 09/20/2017] [Indexed: 12/16/2022] Open
Abstract
Nck promotes breast carcinoma progression and metastasis by directing the polarized interaction of carcinoma cells with collagen fibrils, decreasing actin turnover, and enhancing the localization and activity of MMP14 at the cell surface through modulation of the spatiotemporal activation of Cdc42 and RhoA. Although it is known that noncatalytic region of tyrosine kinase (Nck) regulates cell adhesion and migration by bridging tyrosine phosphorylation with cytoskeletal remodeling, the role of Nck in tumorigenesis and metastasis has remained undetermined. Here we report that Nck is required for the growth and vascularization of primary tumors and lung metastases in a breast cancer xenograft model as well as extravasation following injection of carcinoma cells into the tail vein. We provide evidence that Nck directs the polarization of cell–matrix interactions for efficient migration in three-dimensional microenvironments. We show that Nck advances breast carcinoma cell invasion by regulating actin dynamics at invadopodia and enhancing focalized extracellular matrix proteolysis by directing the delivery and accumulation of MMP14 at the cell surface. We find that Nck-dependent cytoskeletal changes are mechanistically linked to enhanced RhoA but restricted spatiotemporal activation of Cdc42. Using a combination of protein silencing and forced expression of wild-type/constitutively active variants, we provide evidence that Nck is an upstream regulator of RhoA-dependent, MMP14-mediated breast carcinoma cell invasion. By identifying Nck as an important driver of breast carcinoma progression and metastasis, these results lay the groundwork for future studies assessing the therapeutic potential of targeting Nck in aggressive cancers.
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Affiliation(s)
- David C Morris
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
| | - Julia L Popp
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
| | - Leung K Tang
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
| | - Holly C Gibbs
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843-4467
| | - Emily Schmitt
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4467
| | - Sankar P Chaki
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
| | - Briana C Bywaters
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
| | - Alvin T Yeh
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843-4467
| | - Weston W Porter
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4467
| | - Robert C Burghardt
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4467
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4467
| | - Gonzalo M Rivera
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467
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16
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MiR-199a Inhibits Secondary Envelopment of Herpes Simplex Virus-1 Through the Downregulation of Cdc42-specific GTPase Activating Protein Localized in Golgi Apparatus. Sci Rep 2017; 7:6650. [PMID: 28751779 PMCID: PMC5532371 DOI: 10.1038/s41598-017-06754-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/16/2017] [Indexed: 02/06/2023] Open
Abstract
Because several studies have shown that exogenous miR-199a has antiviral effects against various viruses, including herpesviruses, we examined how miR-199a exerts its antiviral effects using epithelial tumour cell lines infected with herpes simplex virus-1 (HSV-1). We found that both miR-199a-5p and -3p impair the secondary envelopment of HSV-1 by suppressing their common target, ARHGAP21, a Golgi-localized GTPase-activating protein for Cdc42. We further found that the trans-cisternae of the Golgi apparatus are a potential membrane compartment for secondary envelopment. Exogenous expression of either pre-miR-199a or sh-ARHGAP21 exhibited shared phenotypes i.e. alteration of Golgi function in uninfected cells, inhibition of HSV-1 secondary envelopment, and reduction of trans-Golgi proteins upon HSV-1 infection. A constitutively active form of Cdc42 also inhibited HSV-1 secondary envelopment. Endogenous levels of miR-199a in epithelial tumour cell lines were negatively correlated with the efficiency of HSV-1 secondary envelopment within these cells. These results suggest that miR-199a is a crucial regulator of Cdc42 activity on Golgi membranes, which is important for the maintenance of Golgi function and for the secondary envelopment of HSV-1 upon its infection.
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17
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A Feed-Forward Mechanism Involving the NOX Complex and RyR-Mediated Ca2+ Release During Axonal Specification. J Neurosci 2017; 36:11107-11119. [PMID: 27798190 DOI: 10.1523/jneurosci.1455-16.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/06/2016] [Indexed: 01/16/2023] Open
Abstract
Physiological levels of ROS support neurite outgrowth and axonal specification, but the mechanisms by which ROS are able to shape neurons remain unknown. Ca2+, a broad intracellular second messenger, promotes both Rac1 activation and neurite extension. Ca2+ release from the endoplasmic reticulum, mediated by both the IP3R1 and ryanodine receptor (RyR) channels, requires physiological ROS levels that are mainly sustained by the NADPH oxidase (NOX) complex. In this work, we explore the contribution of the link between NOX and RyR-mediated Ca2+ release toward axonal specification of rat hippocampal neurons. Using genetic approaches, we find that NOX activation promotes both axonal development and Rac1 activation through a RyR-mediated mechanism, which in turn activates NOX through Rac1, one of the NOX subunits. Collectively, these data suggest a feedforward mechanism that integrates both NOX activity and RyR-mediated Ca2+ release to support cellular mechanisms involved in axon development. SIGNIFICANCE STATEMENT High levels of ROS are frequently associated with oxidative stress and disease. In contrast, physiological levels of ROS, mainly sustained by the NADPH oxidase (NOX) complex, promote neuronal development and axonal growth. However, the mechanisms by which ROS shape neurons have not been described. Our work suggests that NOX-derived ROS promote axonal growth by regulating Rac1 activity, a molecular determinant of axonal growth, through a ryanodine receptor (RyR)-mediated Ca2+ release mechanism. In addition, Rac1, one of the NOX subunits, was activated after RyR-mediated Ca2+ release, suggesting a feedforward mechanism between NOX and RyR. Collectively, our data suggest a novel mechanism that is instrumental in sustaining physiological levels of ROS required for axonal growth of hippocampal neurons.
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18
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Azzarelli R, Oleari R, Lettieri A, Andre' V, Cariboni A. In Vitro, Ex Vivo and In Vivo Techniques to Study Neuronal Migration in the Developing Cerebral Cortex. Brain Sci 2017; 7:brainsci7050048. [PMID: 28448448 PMCID: PMC5447930 DOI: 10.3390/brainsci7050048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/21/2017] [Accepted: 04/24/2017] [Indexed: 11/16/2022] Open
Abstract
Neuronal migration is a fundamental biological process that underlies proper brain development and neuronal circuit formation. In the developing cerebral cortex, distinct neuronal populations, producing excitatory, inhibitory and modulatory neurotransmitters, are generated in different germinative areas and migrate along various routes to reach their final positions within the cortex. Different technical approaches and experimental models have been adopted to study the mechanisms regulating neuronal migration in the cortex. In this review, we will discuss the most common in vitro, ex vivo and in vivo techniques to visualize and study cortical neuronal migration.
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Affiliation(s)
- Roberta Azzarelli
- Department of Oncology, University of Cambridge, Hutchison-MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK.
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, UK.
| | - Roberto Oleari
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, Milan 20133, Italy.
| | - Antonella Lettieri
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, Milan 20133, Italy.
| | - Valentina Andre'
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, Milan 20133, Italy.
| | - Anna Cariboni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, Milan 20133, Italy.
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
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19
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Bywalez WG, Ona-Jodar T, Lukas M, Ninkovic J, Egger V. Dendritic Arborization Patterns of Small Juxtaglomerular Cell Subtypes within the Rodent Olfactory Bulb. Front Neuroanat 2017; 10:127. [PMID: 28163674 PMCID: PMC5247448 DOI: 10.3389/fnana.2016.00127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/19/2016] [Indexed: 01/27/2023] Open
Abstract
Within the glomerular layer of the rodent olfactory bulb, numerous subtypes of local interneurons contribute to early processing of incoming sensory information. Here we have investigated dopaminergic and other small local juxtaglomerular cells in rats and mice and characterized their dendritic arborization pattern with respect to individual glomeruli by fluorescent labeling via patching and reconstruction of dendrites and glomerular contours from two-photon imaging data. Dopaminergic neurons were identified in a transgenic mouse line where the expression of dopamine transporter (DAT) was labeled with GFP. Among the DAT+ cells we found a small short-axon cell (SAC) subtype featuring hitherto undescribed dendritic specializations. These densely ramifying structures clasped mostly around somata of other juxtaglomerular neurons, which were also small, non-dopaminergic and to a large extent non-GABAergic. Clasping SACs were observed also in wild-type mice and juvenile rats. In DAT+ SAC dendrites, single backpropagating action potentials evoked robust calcium entry throughout both clasping and non-clasping compartments. Besides clasping SACs, most other small neurons either corresponded to the classical periglomerular cell type (PGCs), which was never DAT+, or were undersized cells with a small dendritic tree and low excitability. Aside from the presence of clasps in SAC dendrites, many descriptors of dendritic morphology such as the number of dendrites and the extent of branching were not significantly different between clasping SACs and PGCs. However, a detailed morphometric analysis in relation to glomerular contours revealed that the dendrites of clasping SACs arborized mostly in the juxtaglomerular space and never entered more than one glomerulus (if at all), whereas most PGC dendrites were restricted to their parent glomerulus, similar to the apical tufts of mitral cells. These complementary arborization patterns might underlie a highly complementary functional connectivity. The morphometric approach may serve to differentiate also other subtypes of juxtaglomerular neurons, help to identify putative synaptic partners and thus to establish a more refined picture of glomerular network interactions during odor sensing.
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Affiliation(s)
- Wolfgang G Bywalez
- Systems Neurobiology, Department II of Biology, Ludwig-Maximilians-Universität MünchenMunich, Germany; Neurophysiology, Institute of Zoology, Universität RegensburgRegensburg, Germany
| | - Tiffany Ona-Jodar
- Neurophysiology, Institute of Zoology, Universität Regensburg Regensburg, Germany
| | - Michael Lukas
- Neurophysiology, Institute of Zoology, Universität Regensburg Regensburg, Germany
| | - Jovica Ninkovic
- Institute for Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH)Munich, Germany; Institute of Physiological Genomics, Ludwig-Maximilians-Universität MünchenMunich, Germany; Cluster for Systems Neurology and BioMedical Center, Ludwig-Maximilians-Universität MünchenMunich, Germany
| | - Veronica Egger
- Systems Neurobiology, Department II of Biology, Ludwig-Maximilians-Universität MünchenMunich, Germany; Neurophysiology, Institute of Zoology, Universität RegensburgRegensburg, Germany; Regensburg Center of Neuroscience, Universität RegensburgRegensburg, Germany
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20
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Spatiotemporal imaging of small GTPases activity in live cells. Proc Natl Acad Sci U S A 2016; 113:14348-14353. [PMID: 27911813 DOI: 10.1073/pnas.1613999113] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Ras-like small GTPases function as molecular switches and regulate diverse cellular events. To examine the dynamics of signaling requires spatiotemporal visualization of their activity in the cell. Current small GTPase sensors rely on specific effector domains that are available for only a small number of GTPases and compete for endogenous regulator/effector binding. Here, we describe versatile conformational sensors for GTPase activity (COSGAs) based on the conserved GTPase fold. Conformational changes upon GDP/GTP exchange were directly observed in solution, on beads, and in live cells by Förster resonance energy transfer (FRET). The COSGAs allow for monitoring of Rab1 and K-Ras activity in live cells using fluorescence lifetime imaging microscopy. We found that Rab1 is largely active in the cytoplasm and inactive at the Golgi, suggesting that the Golgi serves as the terminal of the Rab1 functional cycle. K-Ras displays polarized activity at the plasma membrane, with less activity at the edge of the cell and membrane ruffles.
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21
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Lobo MJ, Amaral MD, Zaccolo M, Farinha CM. EPAC1 activation by cAMP stabilizes CFTR at the membrane by promoting its interaction with NHERF1. J Cell Sci 2016; 129:2599-612. [PMID: 27206858 DOI: 10.1242/jcs.185629] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/17/2016] [Indexed: 01/14/2023] Open
Abstract
Cyclic AMP (cAMP) activates protein kinase A (PKA) but also the guanine nucleotide exchange factor 'exchange protein directly activated by cAMP' (EPAC1; also known as RAPGEF3). Although phosphorylation by PKA is known to regulate CFTR channel gating - the protein defective in cystic fibrosis - the contribution of EPAC1 to CFTR regulation remains largely undefined. Here, we demonstrate that in human airway epithelial cells, cAMP signaling through EPAC1 promotes CFTR stabilization at the plasma membrane by attenuating its endocytosis, independently of PKA activation. EPAC1 and CFTR colocalize and interact through protein adaptor NHERF1 (also known as SLC9A3R1). This interaction is promoted by EPAC1 activation, triggering its translocation to the plasma membrane and binding to NHERF1. Our findings identify a new CFTR-interacting protein and demonstrate that cAMP activates CFTR through two different but complementary pathways - the well-known PKA-dependent channel gating pathway and a new mechanism regulating endocytosis that involves EPAC1. The latter might constitute a novel therapeutic target for treatment of cystic fibrosis.
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Affiliation(s)
- Miguel J Lobo
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal
| | - Manuela Zaccolo
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Carlos M Farinha
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal
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22
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Ramos GDO, Bernardi L, Lauxen I, Sant’Ana Filho M, Horwitz AR, Lamers ML. Fibronectin Modulates Cell Adhesion and Signaling to Promote Single Cell Migration of Highly Invasive Oral Squamous Cell Carcinoma. PLoS One 2016; 11:e0151338. [PMID: 26978651 PMCID: PMC4792484 DOI: 10.1371/journal.pone.0151338] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 02/27/2016] [Indexed: 12/02/2022] Open
Abstract
Cell migration is regulated by adhesion to the extracellular matrix (ECM) through integrins and activation of small RhoGTPases, such as RhoA and Rac1, resulting in changes to actomyosin organization. During invasion, epithelial-derived tumor cells switch from laminin-enriched basal membrane to collagen and fibronectin-enriched connective tissue. How this switch affects the tumor migration is still unclear. We tested the hypothesis that ECM dictates the invasiveness of Oral Squamous Cell Carcinoma (OSCC). We analyzed the migratory properties of two OSCC lines, a low invasive cell line with high e-cadherin levels (Linv/HE-cad) or a highly invasive cell line with low e-cadherin levels (Hinv/LE-cad), plated on different ECM components. Compared to laminin, fibronectin induced non-directional collective migration and decreased RhoA activity in Linv/HE-cad OSCC. For Hinv/LE-cad OSCC, fibronectin increased Rac1 activity and induced smaller adhesions, resulting in a fast single cell migration in both 2D and 3D environments. Consistent with these observations, human OSCC biopsies exhibited similar changes in cell-ECM adhesion distribution at the invasive front of the tumor, where cells encounter fibronectin. Our results indicate that ECM composition might induce a switch from collective to single cell migration according to tumor invasiveness due to changes in cell-ECM adhesion and the resulting signaling pathways that alter actomyosin organization.
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Affiliation(s)
- Grasieli de Oliveira Ramos
- Basic Research Center, Dentistry School, Federal University of Rio Grande of Sul, Porto Alegre, Rio Grande do Sul, Brazil
- Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
| | - Lisiane Bernardi
- Basic Research Center, Dentistry School, Federal University of Rio Grande of Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Isabel Lauxen
- Basic Research Center, Dentistry School, Federal University of Rio Grande of Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Manoel Sant’Ana Filho
- Basic Research Center, Dentistry School, Federal University of Rio Grande of Sul, Porto Alegre, Rio Grande do Sul, Brazil
- Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
| | - Alan Rick Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Marcelo Lazzaron Lamers
- Basic Research Center, Dentistry School, Federal University of Rio Grande of Sul, Porto Alegre, Rio Grande do Sul, Brazil
- Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
- Department of Morphological Sciences, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
- * E-mail:
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23
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Abstract
Since their discovery, G protein-coupled receptors (GPCRs) constitute one of the most studied proteins leading to important discoveries and perspectives in terms of their biology and implication in physiology and pathophysiology. This is mostly linked to the remarkable advances in the development and application of the biophysical resonance energy transfer (RET)-based approaches, including bioluminescence and fluorescence resonance energy transfer (BRET and FRET, respectively). Indeed, BRET and FRET have been extensively applied to study different aspects of GPCR functioning such as their activation and regulation either statically or dynamically, in real-time and intact cells. Consequently, our view on GPCRs has considerably changed opening new challenges for the study of GPCRs in their native tissues in the aim to get more knowledge on how these receptors control the biological responses. Moreover, the technological aspect of this field of research promises further developments for robust and reliable new RET-based assays that may be compatible with high-throughput screening as well as drug discovery programs.
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Affiliation(s)
- Mohammed Akli Ayoub
- Biologie et Bioinformatique des Systèmes de Signalisation, Institut National de la Recherche Agronomique, UMR85, Unité Physiologie de la Reproduction et des Comportements; CNRS, UMR7247, Nouzilly, France; LE STUDIUM(®) Loire Valley Institute for Advanced Studies, Orléans, France.
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24
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Kumar G, Ho CC, Co CC. Cell-Substrate Interactions Feedback to Direct Cell Migration along or against Morphological Polarization. PLoS One 2015; 10:e0133117. [PMID: 26186588 PMCID: PMC4506050 DOI: 10.1371/journal.pone.0133117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/24/2015] [Indexed: 12/19/2022] Open
Abstract
In response to external stimuli, cells polarize morphologically into teardrop shapes prior to moving in the direction of their blunt leading edge through lamellipodia extension and retraction of the rear tip. This textbook description of cell migration implies that the initial polarization sets the direction of cell migration. Using microfabrication techniques to control cell morphologies and the direction of migration without gradients, we demonstrate that after polarization, lamelipodia extension and attachment can feedback to change and even reverse the initial morphological polarization. Cells do indeed migrate faster in the direction of their morphologically polarization. However, feedback from subsequent lamellipodia extension and attachment can be so powerful as to induce cells to reverse and migrate against their initial polarization, albeit at a slower speed. Constitutively active mutants of RhoA show that RhoA stimulates cell motility when cells are guided either along or against their initial polarization. Cdc42 activation and inhibition, which results in loss of directional motility during chemotaxis, only reduces the speed of migration without altering the directionality of migration on the micropatterns. These results reveal significant differences between substrate directed cell migration and that induced by chemotactic gradients.
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Affiliation(s)
- Girish Kumar
- Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, 45221–0012, United States of America
| | - Chia-Chi Ho
- Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, 45221–0012, United States of America
| | - Carlos C. Co
- Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, 45221–0012, United States of America
- * E-mail:
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25
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De Los Santos C, Chang CW, Mycek MA, Cardullo RA. FRAP, FLIM, and FRET: Detection and analysis of cellular dynamics on a molecular scale using fluorescence microscopy. Mol Reprod Dev 2015; 82:587-604. [PMID: 26010322 PMCID: PMC4515154 DOI: 10.1002/mrd.22501] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 05/01/2015] [Indexed: 01/01/2023]
Abstract
The combination of fluorescent-probe technology plus modern optical microscopes allows investigators to monitor dynamic events in living cells with exquisite temporal and spatial resolution. Fluorescence recovery after photobleaching (FRAP), for example, has long been used to monitor molecular dynamics both within cells and on cellular surfaces. Although bound by the diffraction limit imposed on all optical microscopes, the combination of digital cameras and the application of fluorescence intensity information on large-pixel arrays have allowed such dynamic information to be monitored and quantified. Fluorescence lifetime imaging microscopy (FLIM), on the other hand, utilizes the information from an ensemble of fluorophores to probe changes in the local environment. Using either fluorescence-intensity or lifetime approaches, fluorescence resonance energy transfer (FRET) microscopy provides information about molecular interactions, with Ångstrom resolution. In this review, we summarize the theoretical framework underlying these methods and illustrate their utility in addressing important problems in reproductive and developmental systems.
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Affiliation(s)
- Carla De Los Santos
- Departments of Biology and Bioengineering, University of California, Riverside, Riverside, CA 92501
| | - Ching-Wei Chang
- Department of Bioengineering, University of California, Berkeley 94720
| | - Mary-Ann Mycek
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109
| | - Richard A. Cardullo
- Departments of Biology and Bioengineering, University of California, Riverside, Riverside, CA 92501
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26
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Wilson C, Núñez MT, González-Billault C. Contribution of NADPH-oxidase to the establishment of hippocampal neuronal polarity in culture. J Cell Sci 2015; 128:2989-95. [DOI: 10.1242/jcs.168567] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/05/2015] [Indexed: 01/09/2023] Open
Abstract
Reactive oxygen species (ROS) produced by the NADPH oxidase (NOX) complex play important physiological and pathological roles in neurotransmission and neurodegeneration, respectively. However, the contribution of ROS to molecular mechanisms involved in neuronal polarity and axon elongation is not well understood. In this work, we found that loss of function of the NOX complex altered neuronal polarization and decreased axonal length by a mechanism that involves actin cytoskeleton dynamics. Together, these results indicate that physiological levels of ROS produced by the NOX complex modulate hippocampal neuronal polarity and axonal growth in vitro.
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Affiliation(s)
- Carlos Wilson
- Department of Biology, Faculty of Sciences, Universidad de Chile, Las Palmeras 3425, 7800024, Santiago, Chile
| | - M. Tulio Núñez
- Department of Biology, Faculty of Sciences, Universidad de Chile, Las Palmeras 3425, 7800024, Santiago, Chile
| | - Christian González-Billault
- Department of Biology, Faculty of Sciences, Universidad de Chile, Las Palmeras 3425, 7800024, Santiago, Chile
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27
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Cdk5 induces constitutive activation of 5-HT6 receptors to promote neurite growth. Nat Chem Biol 2014; 10:590-7. [DOI: 10.1038/nchembio.1547] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 04/30/2014] [Indexed: 02/07/2023]
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28
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A Trio-Rac1-Pak1 signalling axis drives invadopodia disassembly. Nat Cell Biol 2014; 16:574-86. [PMID: 24859002 PMCID: PMC4083618 DOI: 10.1038/ncb2972] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/17/2014] [Indexed: 12/11/2022]
Abstract
Rho family GTPases control cell migration and participate in the regulation of cancer metastasis. Invadopodia, associated with invasive tumor cells, are crucial for cellular invasion and metastasis. To study Rac1 GTPase in invadopodia dynamics, we developed a genetically-encoded, single-chain Rac1 Fluorescence Resonance Energy Transfer (FRET) biosensor. The biosensor shows Rac1 activity exclusion from the core of invadopodia, and higher activity when invadopodia disappear, suggesting that reduced Rac1 activity is necessary for their stability, and Rac1 activation is involved in disassembly. Photoactivating Rac1 at invadopodia confirmed this previously-unknown Rac1 function. We built an invadopodia disassembly model, where a signaling axis involving TrioGEF, Rac1, PAK1, and phosphorylation of cortactin, causing invadopodia dissolution. This mechanism is critical for the proper turnover of invasive structures during tumor cell invasion, where a balance of proteolytic activity and locomotory protrusions must be carefully coordinated to achieve a maximally invasive phenotype.
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29
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Azzarelli R, Pacary E, Garg R, Garcez P, van den Berg D, Riou P, Ridley AJ, Friedel RH, Parsons M, Guillemot F. An antagonistic interaction between PlexinB2 and Rnd3 controls RhoA activity and cortical neuron migration. Nat Commun 2014; 5:3405. [PMID: 24572910 PMCID: PMC3939360 DOI: 10.1038/ncomms4405] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 02/06/2014] [Indexed: 02/06/2023] Open
Abstract
A transcriptional programme initiated by the proneural factors Neurog2 and Ascl1 controls successive steps of neurogenesis in the embryonic cerebral cortex. Previous work has shown that proneural factors also confer a migratory behaviour to cortical neurons by inducing the expression of the small GTP-binding proteins such as Rnd2 and Rnd3. However, the directionality of radial migration suggests that migrating neurons also respond to extracellular signal-regulated pathways. Here we show that the Plexin B2 receptor interacts physically and functionally with Rnd3 and stimulates RhoA activity in migrating cortical neurons. Plexin B2 competes with p190RhoGAP for binding to Rnd3, thus blocking the Rnd3-mediated inhibition of RhoA and also recruits RhoGEFs to directly stimulate RhoA activity. Thus, an interaction between the cell-extrinsic Plexin signalling pathway and the cell-intrinsic Ascl1-Rnd3 pathway determines the level of RhoA activity appropriate for cortical neuron migration.
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Affiliation(s)
- Roberta Azzarelli
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
- Present address: Hutchison/MRC Research Centre, University of Cambridge, Box 197, Biomedical Campus, Cambridge CB2 0XZ, UK
| | - Emilie Pacary
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
- Present address: INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France or University Bordeaux, Neurocentre Magendie, Physiopathologie de la plasticité neuronale, U862, Bordeaux F-33000, France
| | - Ritu Garg
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Patricia Garcez
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Debbie van den Berg
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Philippe Riou
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
- Present address: Protein Phosphorylation Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, UK
| | - Anne J. Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Roland H. Friedel
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, New York 10029, USA
| | - Maddy Parsons
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - François Guillemot
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Leptin activates RhoA/ROCK pathway to induce cytoskeleton remodeling in nucleus pulposus cells. Int J Mol Sci 2014; 15:1176-88. [PMID: 24441571 PMCID: PMC3907862 DOI: 10.3390/ijms15011176] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Revised: 01/03/2014] [Accepted: 01/08/2014] [Indexed: 01/01/2023] Open
Abstract
Hyperleptinemia is implicated in obesity-associated lumbar disc degeneration. Nevertheless, the effect of leptin on the intracellular signaling of nucleus pulposus cells is not clear. The current study sought to delineate the possible involvement of the RhoA/ROCK pathway in leptin-mediated cytoskeleton reorganization in nucleus pulposus cells. Nucleus pulposus cells isolated from scoliosis patients were treated with 10 ng/mL of leptin. Fluorescent resonance energy transfer analysis was used to determine the activation of RhoA signaling in nucleus pulposus cells. The protein expression of LIMK1 and cofilin-2 were analyzed by western blot analysis. F-actin cytoskeletal reorganization was assessed by rhodamine-conjugated phalloidin immunoprecipitation. Leptin induced F-actin reorganization and stress fiber formation in nucleus pulposus cells, accompanied by localized RhoA activation and phosphorylation of LIMK1 and cofilin. The RhoA inhibitor C3 exoenzyme or the ROCK inhibitor Y-27632 potently attenuated the effects of leptin on F-actin reorganization and stress fiber formation. Both inhibitors also prevented leptin-induced phosphorylation of LIMK1 and cofilin-2. Our study demonstrated that leptin activated the RhoA/ROCK/LIMK/cofilin-2 cascade to induce cytoskeleton reorganization in nucleus pulposus cells. These findings may provide novel insights into the pathogenic mechanism of obesity-associated lumbar disc degeneration.
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Mouawad F, Aoudjit L, Jiang R, Szaszi K, Takano T. Role of guanine nucleotide exchange factor-H1 in complement-mediated RhoA activation in glomerular epithelial cells. J Biol Chem 2013; 289:4206-18. [PMID: 24356971 DOI: 10.1074/jbc.m113.506816] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Visceral glomerular epithelial cells (GEC), also known as podocytes, are vital for the structural and functional integrity of the glomerulus. The actin cytoskeleton plays a central role in maintaining GEC morphology. In a rat model of experimental membranous nephropathy (passive Heymann nephritis (PHN)), complement C5b-9-induced proteinuria was associated with the activation of the actin regulator small GTPase, RhoA. The mechanisms of RhoA activation, however, remained unknown. In this study, we explored the role of the epithelial guanine nucleotide exchange factor, GEF-H1, in complement-induced RhoA activation. Using affinity precipitation to monitor GEF activity, we found that GEF-H1 was activated in glomeruli isolated from rats with PHN. Complement C5b-9 also induced parallel activation of GEF-H1 and RhoA in cultured GEC. In GEC in which GEF-H1 was knocked down, both basal and complement-induced RhoA activity was reduced. On the other hand, GEF-H1 knockdown augmented complement-mediated cytolysis, suggesting a role for GEF-H1 and RhoA in protecting GEC from cell death. The MEK1/2 inhibitor, U0126, and mutation of the ERK-dependent phosphorylation site (T678A) prevented complement-induced GEF-H1 activation, indicating a role for the ERK pathway. Further, complement induced GEF-H1 and microtubule accumulation in the perinuclear region. However, both the perinuclear accumulation and the activation of GEF-H1 were independent of microtubules and myosin-mediated contractility, as shown using drugs that interfere with microtubule dynamics and myosin II activity. In summary, we have identified complement-induced ERK-dependent GEF-H1 activation as the upstream mechanism of RhoA stimulation, and this pathway has a protective role against cell death.
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Affiliation(s)
- Flaviana Mouawad
- From the Department of Medicine, McGill University Health Centre, Montreal, Quebec H3A 2B4, Canada and
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Raynaud F, Moutin E, Schmidt S, Dahl J, Bertaso F, Boeckers TM, Homburger V, Fagni L. Rho-GTPase-activating protein interacting with Cdc-42-interacting protein 4 homolog 2 (Rich2): a new Ras-related C3 botulinum toxin substrate 1 (Rac1) GTPase-activating protein that controls dendritic spine morphogenesis. J Biol Chem 2013; 289:2600-9. [PMID: 24352656 DOI: 10.1074/jbc.m113.534636] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Development of dendritic spines is important for synaptic function, and alteration in spine morphogenesis is often associated with mental disorders. Rich2 was an uncharacterized Rho-GAP protein. Here we searched for a role of this protein in spine morphogenesis. We found that it is enriched in dendritic spines of cultured hippocampal pyramidal neurons during early stages of development. Rich2 specifically stimulated the Rac1 GTPase in these neurons. Inhibition of Rac1 by EHT 1864 increased the size and decreased the density of dendritic spines. Similarly, Rich2 overexpression increased the size and decreased the density of dendritic spines, whereas knock-down of the protein by specific si-RNA decreased both size and density of spines. The morphological changes were reflected by the increased amplitude and decreased frequency of miniature EPSCs induced by Rich2 overexpression, while si-RNA treatment decreased both amplitude and frequency of these events. Finally, treatment of neurons with EHT 1864 rescued the phenotype induced by Rich2 knock-down. These results suggested that Rich2 controls dendritic spine morphogenesis and function via inhibition of Rac1.
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Affiliation(s)
- Fabrice Raynaud
- From CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
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Nakamura T, Yasuda S, Nagai H, Koinuma S, Morishita S, Goto A, Kinashi T, Wada N. Longest neurite-specific activation of Rap1B in hippocampal neurons contributes to polarity formation through RalA and Nore1A in addition to PI3-kinase. Genes Cells 2013; 18:1020-31. [DOI: 10.1111/gtc.12097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Accepted: 08/13/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Takeshi Nakamura
- Division of Biosignaling, Research Institute for Biomedical Sciences; Tokyo University of Science; Noda Chiba 278-0022 Japan
| | - Sayaka Yasuda
- Division of Biosignaling, Research Institute for Biomedical Sciences; Tokyo University of Science; Noda Chiba 278-0022 Japan
| | - Hiroyuki Nagai
- Division of Biosignaling, Research Institute for Biomedical Sciences; Tokyo University of Science; Noda Chiba 278-0022 Japan
| | - Shingo Koinuma
- Division of Biosignaling, Research Institute for Biomedical Sciences; Tokyo University of Science; Noda Chiba 278-0022 Japan
| | - So Morishita
- Division of Biosignaling, Research Institute for Biomedical Sciences; Tokyo University of Science; Noda Chiba 278-0022 Japan
- Department of Applied Biological Science; Tokyo University of Science; Noda Chiba 278-8510 Japan
| | - Akihiro Goto
- Laboratory of Bioimaging and Cell Signaling; Graduate School of Biostudies; Kyoto University; Kyoto 606-8501 Japan
| | - Tatsuo Kinashi
- Department of Molecular Genetics; Kansai Medical University; Osaka 573-1010 Japan
| | - Naoyuki Wada
- Department of Applied Biological Science; Tokyo University of Science; Noda Chiba 278-8510 Japan
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Spiering D, Bravo-Cordero JJ, Moshfegh Y, Miskolci V, Hodgson L. Quantitative ratiometric imaging of FRET-biosensors in living cells. Methods Cell Biol 2013; 114:593-609. [PMID: 23931524 DOI: 10.1016/b978-0-12-407761-4.00025-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Biosensors based on FRET have been useful in deciphering the dynamics of protein activation events in living cells at subcellular resolutions and in time scales of seconds. These new systems allow observations of dynamic processes which were not possible previously using more traditional biochemical and cell biological approaches. The image data sets obtained from these sensors require careful processing in order to represent the actual protein activation events. Here, we will cover the basic approaches useful for processing the raw image data sets into relativistic ratiometric measurements, capable of depicting relative differences in the protein activation states within a single cell. We will discuss in detail the approaches for genetically encoded, single-chain biosensor systems based on FRET, as well as those that are based on intermolecular, dual-chain design. Additionally, the same analysis can be utilized for biosensor systems using solvatochromic dyes (Nalbant, Hodgson, Kraynov, Toutchkine, & Hahn, 2004), useful for detection of endogenous protein activation states.
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Affiliation(s)
- Désirée Spiering
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA
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35
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Abstract
The Rho GTPases are members of the Ras superfamily of GTPases that are pivotal regulators of the actin cytoskeleton. They also contribute to other cellular processes such as gene transcription, cell polarity, microtubule dynamics, cell cycle progression and vesicle trafficking. Most Rho GTPases act as molecular switches cycling between an "active" GTP-bound form and an "inactive" GDP-bound form. Hence, to elucidate the mechanisms by which Rho GTPases regulate cellular responses, an important parameter to determine is the GTP-loading of each Rho family member in cells under different conditions. Here we describe a biochemical technique to assess this based on affinity-precipitation of the GTP-bound form from whole cell lysates.
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Affiliation(s)
- Narendra Suryavanshi
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
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36
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Tomida T, Oda S, Takekawa M, Iino Y, Saito H. The Temporal Pattern of Stimulation Determines the Extent and Duration of MAPK Activation in a Caenorhabditis elegans Sensory Neuron. Sci Signal 2012; 5:ra76. [DOI: 10.1126/scisignal.2002983] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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37
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Yuen DA, Stead BE, Zhang Y, White KE, Kabir MG, Thai K, Advani SL, Connelly KA, Takano T, Zhu L, Cox AJ, Kelly DJ, Gibson IW, Takahashi T, Harris RC, Advani A. eNOS deficiency predisposes podocytes to injury in diabetes. J Am Soc Nephrol 2012; 23:1810-23. [PMID: 22997257 DOI: 10.1681/asn.2011121170] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Endothelial nitric oxide synthase (eNOS) deficiency may contribute to the pathogenesis of diabetic nephropathy in both experimental models and humans, but the underlying mechanism is not fully understood. Here, we studied two common sequelae of endothelial dysfunction in diabetes: glomerular capillary growth and effects on neighboring podocytes. Streptozotocin-induced diabetes increased glomerular capillary volume in both C57BL/6 and eNOS(-/-) mice. Inhibiting the vascular endothelial growth factor receptor attenuated albuminuria in diabetic C57BL/6 mice but not in diabetic eNOS(-/-) mice, even though it inhibited glomerular capillary enlargement in both. In eNOS(-/-) mice, an acute podocytopathy and heavy albuminuria occurred as early as 2 weeks after inducing diabetes, but treatment with either captopril or losartan prevented these effects. In vitro, serum derived from diabetic eNOS(-/-) mice augmented actin filament rearrangement in cultured podocytes. Furthermore, conditioned medium derived from eNOS(-/-) glomerular endothelial cells exposed to both high glucose and angiotensin II activated podocyte RhoA. Taken together, these results suggest that the combined effects of eNOS deficiency and hyperglycemia contribute to podocyte injury, highlighting the importance of communication between endothelial cells and podocytes in diabetes. Identifying mediators of this communication may lead to the future development of therapies targeting endothelial dysfunction in albuminuric individuals with diabetes.
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Affiliation(s)
- Darren A Yuen
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
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38
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α3β1 integrins regulate CD151 complex assembly and membrane dynamics in carcinoma cells within 3D environments. Oncogene 2012; 32:3965-79. [PMID: 22986527 DOI: 10.1038/onc.2012.415] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 07/23/2012] [Accepted: 07/31/2012] [Indexed: 11/09/2022]
Abstract
Integrins are extracellular matrix (ECM) receptors that are key players in the regulation of tumour cell invasion. The laminin-binding integrin α3β1 has previously been shown to regulate adhesion and migration of carcinoma cells in part through co-operative signalling with the tetraspanin family of transmembrane proteins. However, the spatial and temporal regulation of crosstalk between these families of transmembrane proteins in intact cells remains poorly understood. Here we have used fluorescence resonance energy transfer (FRET) to demonstrate for the first time that α3β1 and the tetraspanin CD151 directly associate at the front and retracting rear of polarised migrating breast carcinoma cells in both two-dimentional (2D) and three-dimentional (3D)matrices. Furthermore, localised α3β1-CD151 binding correlates with lower CD151 homodimerisation in cells migrating on laminin or within matrigel. Loss of α3β1 integrin leads to increased CD151 homodimer formation, increased activation of Rho GTPase, loss of cell polarity and decreased invasion in 3D ECM. As a result, α3-silenced cells show decreased actin-based membrane protrusion and retraction in both 2D and 3D environments. These data demonstrate that associations between α3β1 and CD151 occur dynamically within discrete subcellular compartments and act to establish local GTPase signalling to promote tumour cell invasion. These novel findings shed light on the complex crosstalk and switching between receptor complexes in response to different extracellular cues during cell invasion in 3D environments.
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39
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Matthews DR, Fruhwirth GO, Weitsman G, Carlin LM, Ofo E, Keppler M, Barber PR, Tullis IDC, Vojnovic B, Ng T, Ameer-Beg SM. A multi-functional imaging approach to high-content protein interaction screening. PLoS One 2012; 7:e33231. [PMID: 22506000 PMCID: PMC3323588 DOI: 10.1371/journal.pone.0033231] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 02/06/2012] [Indexed: 12/20/2022] Open
Abstract
Functional imaging can provide a level of quantification that is not possible in what might be termed traditional high-content screening. This is due to the fact that the current state-of-the-art high-content screening systems take the approach of scaling-up single cell assays, and are therefore based on essentially pictorial measures as assay indicators. Such phenotypic analyses have become extremely sophisticated, advancing screening enormously, but this approach can still be somewhat subjective. We describe the development, and validation, of a prototype high-content screening platform that combines steady-state fluorescence anisotropy imaging with fluorescence lifetime imaging (FLIM). This functional approach allows objective, quantitative screening of small molecule libraries in protein-protein interaction assays. We discuss the development of the instrumentation, the process by which information on fluorescence resonance energy transfer (FRET) can be extracted from wide-field, acceptor fluorescence anisotropy imaging and cross-checking of this modality using lifetime imaging by time-correlated single-photon counting. Imaging of cells expressing protein constructs where eGFP and mRFP1 are linked with amino-acid chains of various lengths (7, 19 and 32 amino acids) shows the two methodologies to be highly correlated. We validate our approach using a small-scale inhibitor screen of a Cdc42 FRET biosensor probe expressed in epidermoid cancer cells (A431) in a 96 microwell-plate format. We also show that acceptor fluorescence anisotropy can be used to measure variations in hetero-FRET in protein-protein interactions. We demonstrate this using a screen of inhibitors of internalization of the transmembrane receptor, CXCR4. These assays enable us to demonstrate all the capabilities of the instrument, image processing and analytical techniques that have been developed. Direct correlation between acceptor anisotropy and donor FLIM is observed for FRET assays, providing an opportunity to rapidly screen proteins, interacting on the nano-meter scale, using wide-field imaging.
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Affiliation(s)
- Daniel R. Matthews
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Gilbert O. Fruhwirth
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Gregory Weitsman
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Leo M. Carlin
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Enyinnaya Ofo
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Melanie Keppler
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Paul R. Barber
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
- Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Iain D. C. Tullis
- Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Borivoj Vojnovic
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
- Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Tony Ng
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Simon M. Ameer-Beg
- Division of Cancer Studies, Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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40
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Padilla-Parra S, Tramier M. FRET microscopy in the living cell: Different approaches, strengths and weaknesses. Bioessays 2012; 34:369-76. [DOI: 10.1002/bies.201100086] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 09/15/2011] [Accepted: 09/28/2011] [Indexed: 02/02/2023]
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Abstract
A neuron is able to seamlessly respond to a number of signals, in a timely and specific manner. This process, of integrating multiple inputs, relays on the orchestration of intracellular events by signaling networks. The inherent complexity of signaling networks has made computational modeling a useful approach to understand their underlying regulatory principles. Recent advances in imaging techniques have highlighted the nonhomogeneous nature of intracellular signaling and its significant contribution to the maintenance of signal specificity. Computational modeling can provide mechanistic insight into the origins of these inhomogeneous distributions of signaling components and their role in the integrative capabilities of the neuron.
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Affiliation(s)
- Wendy C Wenderski
- Department of Pharmacology and System Therapeutics, Friedman Brain Institute, Systems Biology Center of New York, Mount Sinai School of Medicine, New York, New York, USA
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42
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Rougerie P, Delon J. Rho GTPases: masters of T lymphocyte migration and activation. Immunol Lett 2011; 142:1-13. [PMID: 22207038 DOI: 10.1016/j.imlet.2011.12.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 11/24/2011] [Accepted: 12/07/2011] [Indexed: 12/15/2022]
Abstract
Rho GTPases are key signal transducer elements activated in T cells by both chemokine and antigen receptors. These two signalling pathways control the two main functions of T lymphocytes: motility and activation. Rho GTPases are thus crucial for the development of an adequate immune response. In this review, we mostly focus on the roles of RhoA, Rac1 and Cdc42 in T cells. We show their importance in phenomena such as adhesion, morphological polarization, migration and antigen recognition.
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Affiliation(s)
- Pablo Rougerie
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, CNRS (UMR 8104), Paris, France; Inserm, U1016, Paris, France
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43
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Abstract
Cell migration is required for many physiological processes, including wound repair and embryogenesis, and relies on precisely orchestrated events that are regulated in a spatially and temporally controlled manner. Most traditional approaches for studying migration, such as genetic methods or the use of chemical inhibitors, do not offer insight into these important components of protein function. However, chemical tools, which respond on a more rapid time scale and in localized regions of the cell, are capable of providing more detailed, real-time information. This Review describes these recent approaches to investigate cell migration and focuses on proteins that are activated by light or small molecules, as well as fluorescent sensors of protein activity.
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Affiliation(s)
- Brenda N. Goguen
- Departments of Biology and Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Barbara Imperiali
- Departments of Biology and Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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44
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Parrini MC, Sadou-Dubourgnoux A, Aoki K, Kunida K, Biondini M, Hatzoglou A, Poullet P, Formstecher E, Yeaman C, Matsuda M, Rossé C, Camonis J. SH3BP1, an exocyst-associated RhoGAP, inactivates Rac1 at the front to drive cell motility. Mol Cell 2011; 42:650-61. [PMID: 21658605 DOI: 10.1016/j.molcel.2011.03.032] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 02/10/2011] [Accepted: 03/30/2011] [Indexed: 11/18/2022]
Abstract
The coordination of the several pathways involved in cell motility is poorly understood. Here, we identify SH3BP1, belonging to the RhoGAP family, as a partner of the exocyst complex and establish a physical and functional link between two motility-driving pathways, the Ral/exocyst and Rac signaling pathways. We show that SH3BP1 localizes together with the exocyst to the leading edge of motile cells and that SH3BP1 regulates cell migration via its GAP activity upon Rac1. SH3BP1 loss of function induces abnormally high Rac1 activity at the front, as visualized by in vivo biosensors, and disorganized and instable protrusions, as revealed by cell morphodynamics analysis. Consistently, constitutively active Rac1 mimics the phenotype of SH3BP1 depletion: slow migration and aberrant cell morphodynamics. Our finding that SH3BP1 downregulates Rac1 at the motile-cell front indicates that Rac1 inactivation in this location, as well as its activation by GEF proteins, is a fundamental requirement for cell motility.
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45
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Tkachenko E, Sabouri-Ghomi M, Pertz O, Kim C, Gutierrez E, Machacek M, Groisman A, Danuser G, Ginsberg MH. Protein kinase A governs a RhoA-RhoGDI protrusion-retraction pacemaker in migrating cells. Nat Cell Biol 2011; 13:660-7. [PMID: 21572420 PMCID: PMC3746034 DOI: 10.1038/ncb2231] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 03/04/2011] [Indexed: 01/15/2023]
Abstract
The cyclical protrusion and retraction of the leading edge is a hallmark of many migrating cells involved in processes such as development, inflammation, and tumorigenesis. The molecular identity of signaling mechanisms that control these cycles has remained unknown. Here, we used live cell imaging of biosensors to monitor spontaneous morphodynamic and signaling activities, and employed correlative image analysis to examine the role of cAMP-activated Protein Kinase A (PKA) in protrusion regulation. PKA activity at the leading edge is closely synchronized with rapid protrusion and with the activity of RhoA. Ensuing PKA phosphorylation of RhoA and the resulting increased interaction between RhoA and RhoGDI establishes a negative feedback that controls the cycling of RhoA activity at the leading edge. Thus, cooperation between PKA, RhoA, and a RhoGDI forms a pacemaker that governs the morphodynamic behavior of migrating cells.
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Affiliation(s)
- Eugene Tkachenko
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, Mail Code 0726, La Jolla, California 92093, USA
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46
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Beckervordersandforth R, Tripathi P, Ninkovic J, Bayam E, Lepier A, Stempfhuber B, Kirchhoff F, Hirrlinger J, Haslinger A, Lie DC, Beckers J, Yoder B, Irmler M, Götz M. In vivo fate mapping and expression analysis reveals molecular hallmarks of prospectively isolated adult neural stem cells. Cell Stem Cell 2011; 7:744-58. [PMID: 21112568 DOI: 10.1016/j.stem.2010.11.017] [Citation(s) in RCA: 326] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 07/08/2010] [Accepted: 11/01/2010] [Indexed: 11/29/2022]
Abstract
Until now, limitations in the ability to enrich adult NSCs (aNSCs) have hampered meaningful analysis of these cells at the transcriptome level. Here we show via a split-Cre technology that coincident activity of the hGFAP and prominin1 promoters is a hallmark of aNSCs in vivo. Sorting of cells from the adult mouse subependymal zone (SEZ) based on their expression of GFAP and prominin1 isolates all self-renewing, multipotent stem cells at high purity. Comparison of the transcriptome of these purified aNSCs to parenchymal nonneurogenic astrocytes and other SEZ cells reveals aNSC hallmarks, including neuronal lineage priming and the importance of cilia- and Ca-dependent signaling pathways. Inducible deletion of the ciliary protein IFT88 in aNSCs validates the role of ciliary function in aNSCs. Our work reveals candidate molecular regulators for unique features of aNSCs and facilitates future selective analysis of aNSCs in other functional contexts, such as aging and injury.
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Affiliation(s)
- Ruth Beckervordersandforth
- Institute for Stem Cell Research, Helmholtz Centre Munich German Research Centre for Environmental Health, Neuherberg/Munich, Germany
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Liang J, Feng J, Wu WKK, Xiao J, Wu Z, Han D, Zhu Y, Qiu G. Leptin-mediated cytoskeletal remodeling in chondrocytes occurs via the RhoA/ROCK pathway. J Orthop Res 2011; 29:369-74. [PMID: 20886658 DOI: 10.1002/jor.21257] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Accepted: 08/16/2010] [Indexed: 02/04/2023]
Abstract
Leptin affects a number of cell signaling pathways, at present, the mechanism(s) by which leptin affects the cartilage cells in OA patient is not well understood. The current study seeks to elucidate whether leptin induces cytoskeletal remodeling in chondrocytes and the possible involvement of the RhoA/ROCK pathway and its downstream mediators in this process. Fluorescent resonance energy transfer (FRET) and western analysis were used to determine the activations of the key proteins in the RhoA/LIMK1/Cofilin pathway. Accompanying cytoskeletal remodeling was elucidated. Upon leptin stimulation, a substantial increase of RhoA activity localized at one end of the cell was observed from 2 to 30 min post-stimulation. The results of Western blot showed leptin significantly increased LIMK1 and cofilin-2 phosphorylation in a time-dependent manner with maximal stimulation attained 60 min and 24 h post-stimulation, respectively. Chondrocytes stimulated with leptin exhibited an epithelioid morphology with increased cellular spreading. F-actin in leptin-stimulated chondrocytes also showed more intense cytoplasmic staining with occasional localization along filamentous structures. The results indicate that leptin activates the RhoA/ROCK/LIMK/cofilin pathway, which results in cytoskeletal reorganization in chondrocytes. These findings provide novel evidence supporting the possible involvement of leptin and the RhoA pathway in the pathogenesis of OA.
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Affiliation(s)
- Jinqian Liang
- Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Beijing, China
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Reelin signals through apolipoprotein E receptor 2 and Cdc42 to increase growth cone motility and filopodia formation. J Neurosci 2010; 30:14759-72. [PMID: 21048135 DOI: 10.1523/jneurosci.4036-10.2010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lipoprotein receptor signaling regulates the positioning and differentiation of postmitotic neurons during development and modulates neuronal plasticity in the mature brain. Depending on the contextual situation, the lipoprotein receptor ligand Reelin can have opposing effects on cortical neurons. We show that Reelin increases growth cone motility and filopodia formation, and identify the underlying signaling cascade. Reelin activates the Rho GTPase Cdc42, known for its role in neuronal morphogenesis and directed migration, in an apolipoprotein E receptor 2-, Disabled-1-, and phosphatidylinositol 3-kinase-dependent manner. We demonstrate that neuronal vesicle trafficking, a Cdc42-controlled process, is increased after Reelin treatment and further provide evidence that the peptidergic VIP/PACAP38 system and Reelin can functionally interact to promote axonal branching. In conclusion, Reelin-induced activation of Cdc42 contributes to the regulation of the cytoskeleton of individual responsive neurons and converges with other signaling cascades to orchestrate Rho GTPase activity and promote neuronal development. Our data link the observation that defects in Rho GTPases and Reelin signaling are responsible for developmental defects leading to neurological and psychiatric disorders.
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Balla A, Erdélyi LS, Soltész-Katona E, Balla T, Várnai P, Hunyady L. Demonstration of angiotensin II-induced Ras activation in the trans-Golgi network and endoplasmic reticulum using bioluminescence resonance energy transfer-based biosensors. J Biol Chem 2010; 286:5319-27. [PMID: 21062747 DOI: 10.1074/jbc.m110.176933] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous studies have demonstrated that molecules of the Ras signaling pathway are present in intracellular compartments, including early endosomes, the endoplasmic reticulum (ER), and the Golgi, and suggested that mitogens can regulate Ras activity in these endomembranes. In this study, we investigated the effect of angiotensin II (AngII) on intracellular Ras activity in living HEK293 cells expressing angiotensin type 1 receptors (AT(1)-Rs) using newly developed bioluminescence resonance energy transfer biosensors. To investigate the subcellular localization of AngII-induced Ras activation, we targeted our probes to various intracellular compartments, such as the trans-Golgi network (TGN), the ER, and early endosomes. Using these biosensors, we detected AngII-induced Ras activation in the TGN and ER, but not in early endosomes. In cells expressing a cytoplasmic tail deletion AT(1)-R mutant, the AngII-induced response was enhanced, suggesting that receptor internalization and β-arrestin binding are not required for AngII-induced Ras activation in endomembranes. Although we were able to demonstrate EGF-induced Ras activation in the plasma membrane and TGN, but not in other endomembranes, AG1478, an EGF receptor inhibitor, did not affect the AngII-induced response, suggesting that the latter is independent of EGF receptor transactivation. AngII was unable to stimulate Ras activity in the studied compartments in cells expressing a G protein coupling-deficient AT(1)-R mutant ((125)DRY(127) to (125)AAY(127)). These data suggest that AngII can stimulate Ras activity in the TGN and ER with a G protein-dependent mechanism, which does not require β-arrestin-mediated signaling, receptor internalization, and EGF receptor transactivation.
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Affiliation(s)
- András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, H-1444 Budapest, Hungary
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Dityatev A, Schachner M, Sonderegger P. The dual role of the extracellular matrix in synaptic plasticity and homeostasis. Nat Rev Neurosci 2010; 11:735-46. [DOI: 10.1038/nrn2898] [Citation(s) in RCA: 350] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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