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Schneider F, Metz I, Rust MB. Regulation of actin filament assembly and disassembly in growth cone motility and axon guidance. Brain Res Bull 2023; 192:21-35. [PMID: 36336143 DOI: 10.1016/j.brainresbull.2022.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
Directed outgrowth of axons is fundamental for the establishment of neuronal networks. Axon outgrowth is guided by growth cones, highly motile structures enriched in filamentous actin (F-actin) located at the axons' distal tips. Growth cones exploit F-actin-based protrusions to scan the environment for guidance cues, and they contain the sensory apparatus to translate guidance cue information into intracellular signaling cascades. These cascades act upstream of actin-binding proteins (ABP) and thereby control assembly and disassembly of F-actin. Spatiotemporally controlled F-actin dis-/assembly in growth cones steers the axon towards attractants and away from repellents, and it thereby navigates the axon through the developing nervous system. Hence, ABP that control F-actin dynamics emerged as critical regulators of neuronal network formation. In the present review article, we will summarize and discuss current knowledge of the mechanisms that control remodeling of the actin cytoskeleton in growth cones, focusing on recent progress in the field. Further, we will introduce tools and techniques that allow to study actin regulatory mechanism in growth cones.
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Affiliation(s)
- Felix Schneider
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Molecular Urooncology, Department of Urology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Isabell Metz
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University Giessen, 35032 Marburg, Germany.
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2
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Tonazzini I, Pellegrini M, Pellegrino M, Cecchini M. Interaction of leech neurons with topographical gratings: comparison with rodent and human neuronal lines and primary cells. Interface Focus 2014; 4:20130047. [PMID: 24501675 DOI: 10.1098/rsfs.2013.0047] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Controlling and improving neuronal cell migration and neurite outgrowth are critical elements of tissue engineering applications and development of artificial neuronal interfaces. To this end, a promising approach exploits nano/microstructured surfaces, which have been demonstrated to be capable of tuning neuronal differentiation, polarity, migration and neurite orientation. Here, we investigate the neurite contact guidance of leech neurons on plastic gratings (GRs; anisotropic topographies composed of alternating lines of grooves and ridges). By high-resolution microscopy, we quantitatively evaluate the changes in tubulin cytoskeleton organization and cell morphology and in the neurite and growth cone development. The topography-reading process of leech neurons on GRs is mediated by filopodia and is more responsive to 4-µm-period GRs than to smaller period GRs. Leech neuron behaviour on GRs is finally compared and validated with several other neuronal cells, from murine differentiated embryonic stem cells and primary hippocampal neurons to differentiated human neuroblastoma cells.
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Affiliation(s)
- Ilaria Tonazzini
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR , Piazza San Silvestro 12, Pisa 56127 , Italy
| | - Monica Pellegrini
- Scuola Normale Superiore , Piazza dei Cavalieri 7, Pisa 56126 , Italy
| | - Mario Pellegrino
- Dipartimento di Ricerca Traslazionale e Delle Nuove Tecnologie in Medicina e Chirurgia , Università di Pisa , Via S. Zeno 31, 56127 Pisa , Italy
| | - Marco Cecchini
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR , Piazza San Silvestro 12, Pisa 56127 , Italy
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Lorente G, Syriani E, Morales M. Actin filaments at the leading edge of cancer cells are characterized by a high mobile fraction and turnover regulation by profilin I. PLoS One 2014; 9:e85817. [PMID: 24465723 PMCID: PMC3895011 DOI: 10.1371/journal.pone.0085817] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 12/03/2013] [Indexed: 11/18/2022] Open
Abstract
Cellular motility is the basis for cancer cell invasion and metastasis. In the case of breast cancer, the most common type of cancer among women, metastasis represents the most devastating stage of the disease. The central role of cellular motility in cancer development emphasizes the importance of understanding the specific mechanisms involved in this process. In this context, tumor development and metastasis would be the consequence of a loss or defect of the mechanisms that control cytoskeletal remodeling. Profilin I belongs to a family of small actin binding proteins that are thought to assist in actin filament elongation at the leading edge of migrating cells. Traditionally, Profilin I has been considered to be an essential control element for actin polymerization and cell migration. Expression of Profilin I is down-regulated in breast and various other cancer cells. In MDA-MB-231 cells, a breast cancer cell line, further inhibition of Profilin I expression promotes hypermotility and metastatic spread, a finding that contrasts with the proposed role of Profilin in enhancing polymerization. In this report, we have taken advantage of the fluorescence recovery after photobleaching (FRAP) of GFP-actin to quantify and compare actin dynamics at the leading edge level in both cancer and non-cancer cell models. Our results suggest that (i) a high level of actin dynamics (i.e., a large mobile fraction of actin filaments and a fast turnover) is a common characteristic of some cancer cells; (ii) actin polymerization shows a high degree of independence from the presence of extracellular growth factors; and (iii) our results also corroborate the role of Profilin I in regulating actin polymerization, as raising the intracellular levels of Profilin I decreased the mobile fraction ratio of actin filaments and slowed their polymerization rate; furthermore, increased Profilin levels also led to reduced individual cell velocity and directionality.
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Affiliation(s)
- Gisela Lorente
- Neurophysiology Laboratory, Deptartment of Physiological Sciences I, School of Medicine, University of Barcelona, Barcelona, Spain
| | - Emilio Syriani
- Structural Synaptic Plasticity Lab, Department of Neurodegenerative Diseases, CIBIR Piqueras 98, Logroño, La Rioja, Spain
| | - Miguel Morales
- Structural Synaptic Plasticity Lab, Department of Neurodegenerative Diseases, CIBIR Piqueras 98, Logroño, La Rioja, Spain
- * E-mail:
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Pontrello CG, Ethell IM. Accelerators, Brakes, and Gears of Actin Dynamics in Dendritic Spines. ACTA ACUST UNITED AC 2009; 3:67-86. [PMID: 20463852 DOI: 10.2174/1874082000903020067] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dendritic spines are actin-rich structures that accommodate the postsynaptic sites of most excitatory synapses in the brain. Although dendritic spines form and mature as synaptic connections develop, they remain plastic even in the adult brain, where they can rapidly grow, change, or collapse in response to normal physiological changes in synaptic activity that underlie learning and memory. Pathological stimuli can adversely affect dendritic spine shape and number, and this is seen in neurodegenerative disorders and some forms of mental retardation and autism as well. Many of the molecular signals that control these changes in dendritic spines act through the regulation of filamentous actin (F-actin), some through direct interaction with actin, and others via downstream effectors. For example, cortactin, cofilin, and gelsolin are actin-binding proteins that directly regulate actin dynamics in dendritic spines. Activities of these proteins are precisely regulated by intracellular signaling events that control their phosphorylation state and localization. In this review, we discuss how actin-regulating proteins maintain the balance between F-actin assembly and disassembly that is needed to stabilize mature dendritic spines, and how changes in their activities may lead to rapid remodeling of dendritic spines.
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Affiliation(s)
- Crystal G Pontrello
- Biomedical Sciences Division and Neuroscience program, University of California Riverside, USA
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Ding Z, Lambrechts A, Parepally M, Roy P. Silencing profilin-1 inhibits endothelial cell proliferation, migration and cord morphogenesis. J Cell Sci 2006; 119:4127-37. [PMID: 16968742 DOI: 10.1242/jcs.03178] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Expression of several actin-binding proteins including profilin-1 is up-regulated during capillary morphogenesis of endothelial cells, the biological significance of which remains unknown. Specifically, we hypothesized that profilin-1 is important for endothelial migration and proliferation. In this study, we suppressed profilin-1 expression in human umbilical vein endothelial cells by RNA-interference. Gene silencing of profilin-1 led to significant reduction in the formation of actin filaments and focal adhesions. Loss of profilin-1 expression was also associated with reduced dynamics of cell-cell adhesion. Data from both wound-healing experiments and time-lapse imaging of individual cells showed inhibition of cell migration when profilin-1 expression was suppressed. Cells lacking profilin-1 exhibited defects in membrane protrusion, both in terms of its magnitude and directional persistence. Furthermore, loss of profilin-1 expression inhibited cell growth without compromising cell survival, at least in the short-term, thus suggesting that profilin-1 also plays an important role in endothelial proliferation as hypothesized. Finally, silencing profilin-1 expression suppressed matrigel-induced early cord morphogenesis of endothelial cells. Taken together, our data suggest that profilin-1 may play important role in biological events that involve endothelial proliferation, migration and morphogenesis.
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Affiliation(s)
- Zhijie Ding
- Department of Bioengineering, University of Pittsburgh, 749 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, USA
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Roy P, Jacobson K. Overexpression of profilin reduces the migration of invasive breast cancer cells. ACTA ACUST UNITED AC 2004; 57:84-95. [PMID: 14691948 DOI: 10.1002/cm.10160] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The exact role profilin plays in cell migration is not clear. In this study, we have evaluated the effect of overexpression of profilin on the migration of breast cancer cells. Overexpression was carried out by stably expressing GFP-profilin in BT474 cells. It was observed that even a moderate level of overexpression of profilin significantly impaired the ability of BT474 cells to spread on fibronectin-coated substrate and migrate in response to EGF. GFP-profilin expressing cells also showed increased resistance to detachment in response to trypsin and increased tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin compared to the parental and GFP-expressing (control) cell lines. These results suggest that perturbation of profilin levels may offer a good strategy for controlling the metastatic potential of breast cancer cells.
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Affiliation(s)
- Partha Roy
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC, USA.
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de-Miguel FF, Vargas J. Steps in the formation of a bipolar outgrowth pattern by cultured neurons, and their substrate dependence. JOURNAL OF NEUROBIOLOGY 2002; 50:106-17. [PMID: 11793358 DOI: 10.1002/neu.10017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We studied the steps in the formation of the bipolar outgrowth pattern of cultured adult Anterior Pagoda (AP) neurons of the leech growing on a central nervous system (CNS) homogenate as substrate. This pattern, which consists of two primary neurites directed in opposite directions plus some bifurcations, resembles their embryonic pattern but is different from the patterns they develop in culture on leech laminin or Concanavalin A as substrates. In eight neurons that were studied, one primary neurite formed and branched several hours before the second one. Time-lapse video analysis showed that between 12 and 36 h of growth, the more proximal branch of the early neurite migrated retrogradely, rotated, and formed the second primary branch. Both neurites elongated until the total neurite length reached 130-160 microm, when the elongation of primary neurites became synchronous with the retraction of secondary processes, suggesting competition. The substrate dependence of these events was tested by plating AP neurons on leech laminin. On this substrate AP neurons produced multiple independent primary neurites with branches. Retraction of some large branches was followed by their regrowth, and did not correlate with the changes in other neurites. We propose that the dynamics in the formation of the bipolar outgrowth pattern of AP neurons arise from inhibitory extracellular matrix molecules, which reduce the synthesis of precursors for neurite formation.
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Affiliation(s)
- Francisco F de-Miguel
- Departamento de Biofísica, Instituto de Fisiología Celular, U.N.A.M., Apartado Postal 70-253, 04510, D.F., México.
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Hwang SJ, Pagliardini S, Boukhelifa M, Parast MM, Otey CA, Rustioni A, Valtschanoff JG. Palladin is expressed preferentially in excitatory terminals in the rat central nervous system. J Comp Neurol 2001. [DOI: 10.1002/cne.1062] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Geese M, Schlüter K, Rothkegel M, Jockusch BM, Wehland J, Sechi AS. Accumulation of profilin II at the surface of Listeria is concomitant with the onset of motility and correlates with bacterial speed. J Cell Sci 2000; 113 ( Pt 8):1415-26. [PMID: 10725224 DOI: 10.1242/jcs.113.8.1415] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The spatial and temporal activity of the actin cytoskeleton is precisely regulated during cell motility by several microfilament-associated proteins of which profilin plays an essential role. We have analysed the distribution of green fluorescent protein (GFP)-tagged profilins in cultured and in Listeria-infected cells. Among the different GFP-profilin fusion proteins studied, only the construct in which the GFP moiety was fused to the carboxy terminus of profilin II (profilin II-GFP) was recruited by intracellular Listeria. The in vitro ligand-binding properties of this construct, e.g. the binding to monomeric actin, poly-L-proline and phosphatidylinositol 4,5-bisphosphate (PIP2), were unaffected by GFP. Profilin II-GFP co-localised with vinculin and Mena to the focal adhesions in REF-52 fibroblasts and was distributed as a thin line at the front of protruding lamellipodia in B16-F1 mouse melanoma cells. In Listeria-infected cells, profilin II-GFP was recruited, in an asymmetric fashion, to the surface of Listeria at the onset of motility whereas it was not detectable on non-motile bacteria. In contrast to the vasodilator-stimulated phosphoprotein (VASP), profilin II-GFP localised at the bacterial surface only on motile Listeria. Moreover, the fluorescence intensity of profilin II-GFP directly correlated with the speed of the bacteria. Thus, the use of GFP-tagged profilin II provides new insights into the role of profilins in cellular motility.
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Affiliation(s)
- M Geese
- Department of Cell Biology, Gesellschaft für Biotechnologische Forschung (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
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Abstract
The ability of calcium (Ca(2+)) to effect changes in growth cone motility requires remodeling of the actin cytoskeleton. To understand the mechanisms involved, we evaluated the effect of elevated intracellular calcium ([Ca(2+)](i)) on actin bundle dynamics, organization, and retrograde flow in the large growth cones of identified Helisoma neurons. Depolarization with 15 mM KCl (high K(+)) for 30 min caused a rapid and sustained increase in [Ca(2+)](i) and resulted in longer filopodia, shorter actin ribs, and a decrease in lamellipodia width. Time-lapse microscopy revealed that increasing [Ca(2+)](i) affected actin bundle dynamics differently at the proximal and distal ends. Filopodial lengthening resulted from assembly-driven elongation of actin bundles whereas actin rib shortening resulted from a distal shift in the location of breakage. Buckling of ribs occurred before breakage, suggesting nonuniform forces were applied to ribs before shortening. Calcium (Ca(2+)) influx also resulted in a decrease in density of F-actin in bundles, as determined by contrast changes in ribs imaged by differential interference contrast microscopy and fluorescent intensity changes in rhodamine-labeled ribs. The velocity of retrograde flow decreased by 50% after elevation of [Ca(2+)](i). However, no significant change in retrograde flow occurred when the majority of changes in actin bundles were blocked by phalloidin. This suggests that inhibition of retrograde flow resulted from Ca(2+)-induced changes in the actin cytoskeleton. These results implicate Ca(2+) as a regulator of actin dynamics and, as such, provide a mechanism by which Ca(2+) can influence growth cone motility and behavior.
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11
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Roth LW, Bormann P, Wiederkehr C, Reinhard E. Beta-thymosin, a modulator of the actin cytoskeleton is increased in regenerating retinal ganglion cells. Eur J Neurosci 1999; 11:3488-98. [PMID: 10564357 DOI: 10.1046/j.1460-9568.1999.00715.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Beta-thymosins are actin monomer-binding polypeptides that are expressed in a neuronal growth-specific manner during embryonic development. Here, we show that regenerating retinal ganglion cells and non-neuronal cells of the optic nerve transiently activate beta-thymosin transcription after optic nerve lesion in the zebrafish. In retinal cell cultures, beta-thymosin is found at highest concentration in growth cones, branching points and varicosities of neurite-extending retinal ganglion cells. These places often exhibit reduced phalloidin staining, indicating that beta-thymosin promotes the disassembly of actin filaments. Beta-thymosin distribution within neurons in culture is distinct from actin, tubulin and the actin-severing protein gelsolin. Ectopic expression of beta-thymosin in a central nervous system (CNS) catecholaminergic cell line leads to alterations in the shape of the cell bodies and neurites. Beta-thymosin-positive cells spread more fully and exhibit an excessive degree of branching. We partially cloned two other actin-binding proteins, profilin and gelsolin, and analysed their expression patterns. Profilin is constitutively expressed in virtually all cells. Gelsolin, like beta-thymosin, is selectively increased in regenerating retinal ganglion cells. During development, however, gelsolin mRNA is not detected in the nervous system. These findings indicate that distinct mechanisms control the actin cytoskeleton in embryonic and regenerating neurons, and that beta-thymosin may be a major regulator of actin dynamics in the zebrafish CNS.
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Affiliation(s)
- L W Roth
- Department of Pharmacology, Biozentrum, University of Basel, Switzerland
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Welnhofer EA, Zhao L, Cohan CS. Calcium influx alters actin bundle dynamics and retrograde flow in Helisoma growth cones. J Neurosci 1999; 19:7971-82. [PMID: 10479697 PMCID: PMC6782479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
The ability of calcium (Ca(2+)) to effect changes in growth cone motility requires remodeling of the actin cytoskeleton. To understand the mechanisms involved, we evaluated the effect of elevated intracellular calcium ([Ca(2+)](i)) on actin bundle dynamics, organization, and retrograde flow in the large growth cones of identified Helisoma neurons. Depolarization with 15 mM KCl (high K(+)) for 30 min caused a rapid and sustained increase in [Ca(2+)](i) and resulted in longer filopodia, shorter actin ribs, and a decrease in lamellipodia width. Time-lapse microscopy revealed that increasing [Ca(2+)](i) affected actin bundle dynamics differently at the proximal and distal ends. Filopodial lengthening resulted from assembly-driven elongation of actin bundles whereas actin rib shortening resulted from a distal shift in the location of breakage. Buckling of ribs occurred before breakage, suggesting nonuniform forces were applied to ribs before shortening. Calcium (Ca(2+)) influx also resulted in a decrease in density of F-actin in bundles, as determined by contrast changes in ribs imaged by differential interference contrast microscopy and fluorescent intensity changes in rhodamine-labeled ribs. The velocity of retrograde flow decreased by 50% after elevation of [Ca(2+)](i). However, no significant change in retrograde flow occurred when the majority of changes in actin bundles were blocked by phalloidin. This suggests that inhibition of retrograde flow resulted from Ca(2+)-induced changes in the actin cytoskeleton. These results implicate Ca(2+) as a regulator of actin dynamics and, as such, provide a mechanism by which Ca(2+) can influence growth cone motility and behavior.
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Affiliation(s)
- E A Welnhofer
- Department of Anatomy and Cell Biology, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
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Wills Z, Marr L, Zinn K, Goodman CS, Van Vactor D. Profilin and the Abl tyrosine kinase are required for motor axon outgrowth in the Drosophila embryo. Neuron 1999; 22:291-9. [PMID: 10069335 DOI: 10.1016/s0896-6273(00)81090-9] [Citation(s) in RCA: 172] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The ability of neuronal growth cones to be guided by extracellular cues requires intimate communication between signal transduction systems and the dynamic actin-based cytoskeleton at the leading edge. Profilin, a small, actin-binding protein, has been proposed to be a regulator of the cell motility machinery at leading edge membranes. However, its requirement in the developing nervous system has been unknown. Profilin associates with members of the Enabled family of proteins, suggesting that Profilin might link Abl function to the cytoskeleton. Here, genetic analysis in Drosophila is used to demonstrate that mutations in Profilin (chickadee) and Abl (abl) display an identical growth cone arrest phenotype for axons of intersegmental nerve b (ISNb). Moreover, the phenotype of a double mutant suggests that these components function together to control axonal outgrowth.
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Affiliation(s)
- Z Wills
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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