scholarly journals Shootin1 interacts with actin retrograde flow and L1-CAM to promote axon outgrowth

2008 ◽  
Vol 181 (5) ◽  
pp. 817-829 ◽  
Author(s):  
Tadayuki Shimada ◽  
Michinori Toriyama ◽  
Kaori Uemura ◽  
Hiroyuki Kamiguchi ◽  
Tadao Sugiura ◽  
...  
Keyword(s):  
Actin Filament ◽  
Cell Adhesion Molecules ◽  
Molecular Basis ◽  
Hippocampal Neurons ◽  
Leading Edge ◽  
Growth Cones ◽  
Axon Outgrowth ◽  
Retrograde Flow ◽  
Nerve Growth Cones ◽  
Linkage Model

Actin polymerizes near the leading edge of nerve growth cones, and actin filaments show retrograde movement in filopodia and lamellipodia. Linkage between actin filament retrograde flow and cell adhesion molecules (CAMs) in growth cones is thought to be one of the mechanisms for axon outgrowth and guidance. However, the molecular basis for this linkage remains elusive. Here, we show that shootin1 interacts with both actin filament retrograde flow and L1-CAM in axonal growth cones of cultured rat hippocampal neurons, thereby mediating the linkage between them. Impairing this linkage, either by shootin1 RNA interference or disturbing the interaction between shootin1 and actin filament flow, inhibited L1-dependent axon outgrowth, whereas enhancing the linkage by shootin1 overexpression promoted neurite outgrowth. These results strengthen the actin flow–CAM linkage model (“clutch” model) for axon outgrowth and suggest that shootin1 is a key molecule involved in this mechanism.

scholarly journals Shootin1–cortactin interaction mediates signal–force transduction for axon outgrowth

2015 ◽  
Vol 210 (4) ◽  
pp. 663-676 ◽  
Author(s):  
Yusuke Kubo ◽  
Kentarou Baba ◽  
Michinori Toriyama ◽  
Takunori Minegishi ◽  
Tadao Sugiura ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Leading Edge ◽  
Growth Cones ◽  
Axon Outgrowth ◽  
Actin Binding ◽  
Retrograde Flow ◽  
Environmental Chemical ◽  
Mechanical Coupling ◽  
Cell Adhesions ◽  
Force Transduction

Motile cells transduce environmental chemical signals into mechanical forces to achieve properly controlled migration. This signal–force transduction is thought to require regulated mechanical coupling between actin filaments (F-actins), which undergo retrograde flow at the cellular leading edge, and cell adhesions via linker “clutch” molecules. However, the molecular machinery mediating this regulatory coupling remains unclear. Here we show that the F-actin binding molecule cortactin directly interacts with a clutch molecule, shootin1, in axonal growth cones, thereby mediating the linkage between F-actin retrograde flow and cell adhesions through L1-CAM. Shootin1–cortactin interaction was enhanced by shootin1 phosphorylation by Pak1, which is activated by the axonal chemoattractant netrin-1. We provide evidence that shootin1–cortactin interaction participates in netrin-1–induced F-actin adhesion coupling and in the promotion of traction forces for axon outgrowth. Under cell signaling, this regulatory F-actin adhesion coupling in growth cones cooperates with actin polymerization for efficient cellular motility.

Distribution and possible interactions of actin-associated proteins and cell adhesion molecules of nerve growth cones

Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 505-519 ◽  
Author(s):  
P.C. Letourneau ◽  
T.A. Shattuck
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Cell Adhesion Molecules ◽  
Growth Cones ◽  
Tissue Cell ◽  
Axonal Pathfinding ◽  
Cell Behaviour ◽  
Nerve Growth ◽  
Associated Proteins ◽  
Nerve Growth Cones

Actin filaments and their interactions with cell surface molecules have key roles in tissue cell behaviour. Axonal pathfinding during embryogenesis, an especially complex cell behaviour, is based on the migration of nerve growth cones. We have used fluorescence immunocytochemistry to examine the distribution in growth cones, their filopodia and lamellipodia of several actin-associated proteins and nerve cell adhesion molecules. The leading margins of chick dorsal root ganglion nerve growth cones and their protrusions stain strongly for f-actin, filamin, alpha-actinin, myosin, tropomyosin, talin and vinculin. MAP2 is absent from DRG growth cones, and staining for spectrin fodrin extends into growth cones, but not along filopodia. Thus, organization of the leading margins of growth cones may strongly resemble the leading lamella of migrating fibroblasts. The adhesion-mediating molecules integrin, L1, N-CAM and A-CAM are all found on DRG neurites and growth cones. However, filopodia stain relatively more strongly for integrin and L1 than for A-CAM or N-CAM. In fact, the 180 X 10(3) Mr form of N-CAM may be absent from most of the length of filopodia. DRG neurones cultured in cytochalasin B display differences in immunofluorescence staining which further emphasize that these adhesion molecules interact differentially with the actin filament system of migrating growth cones. Several models for neuronal morphogenesis emphasize the importance of regulation of the expression of adhesion molecules. Our results support hypotheses that cellular distribution and transmembrane interactions are key elements in the functions of these adhesion molecules during axonal pathfinding.

scholarly journals CRMP-2 Is Involved in Kinesin-1-Dependent Transport of the Sra-1/WAVE1 Complex and Axon Formation

2005 ◽  
Vol 25 (22) ◽  
pp. 9920-9935 ◽  
Author(s):  
Yoji Kawano ◽  
Takeshi Yoshimura ◽  
Daisuke Tsuboi ◽  
Saeko Kawabata ◽  
Takako Kaneko-Kawano ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Hippocampal Neurons ◽  
Binding Proteins ◽  
Neuronal Development ◽  
Critical Role ◽  
Growth Cones ◽  
Axon Outgrowth ◽  
Actin Binding ◽  
Dependent Manner ◽  
Actin Binding Proteins

ABSTRACT A neuron has two types of highly polarized cell processes, the single axon and multiple dendrites. One of the fundamental questions of neurobiology is how neurons acquire such specific and polarized morphologies. During neuronal development, various actin-binding proteins regulate dynamics of actin cytoskeleton in the growth cones of developing axons. The regulation of actin cytoskeleton in the growth cones is thought to be involved in axon outgrowth and axon-dendrite specification. However, it is largely unknown which actin-binding proteins are involved in axon-dendrite specification and how they are transported into the developing axons. We have previously reported that collapsin response mediator protein 2 (CRMP-2) plays a critical role in axon outgrowth and axon-dendrite specification (N. Inagaki, K. Chihara, N. Arimura, C. Menager, Y. Kawano, N. Matsuo, T. Nishimura, M. Amano, and K. Kaibuchi, Nat. Neurosci. 4:781-782, 2001). Here, we found that CRMP-2 interacted with the specifically Rac1-associated protein 1 (Sra-1)/WASP family verprolin-homologous protein 1 (WAVE1) complex, which is a regulator of actin cytoskeleton. The knockdown of Sra-1 and WAVE1 by RNA interference canceled CRMP-2-induced axon outgrowth and multiple-axon formation in cultured hippocampal neurons. We also found that CRMP-2 interacted with the light chain of kinesin-1 and linked kinesin-1 to the Sra-1/WAVE1 complex. The knockdown of CRMP-2 and kinesin-1 delocalized Sra-1 and WAVE1 from the growth cones of axons. These results suggest that CRMP-2 transports the Sra-1/WAVE1 complex to axons in a kinesin-1-dependent manner and thereby regulates axon outgrowth and formation.

scholarly journals Nerve growth cone lamellipodia contain two populations of actin filaments that differ in organization and polarity.

1992 ◽  
Vol 119 (5) ◽  
pp. 1219-1243 ◽  
Author(s):  
A K Lewis ◽  
P C Bridgman
Keyword(s):  
Actin Filament ◽  
Growth Cone ◽  
Actin Filaments ◽  
Membrane Surface ◽  
Leading Edge ◽  
Growth Cones ◽  
Differential Interference Contrast Microscopy ◽  
Nerve Growth ◽  
Filament Bundles ◽  
Two Populations

The organization and polarity of actin filaments in neuronal growth cones was studied with negative stain and freeze-etch EM using a permeabilization protocol that caused little detectable change in morphology when cultured nerve growth cones were observed by video-enhanced differential interference contrast microscopy. The lamellipodial actin cytoskeleton was composed of two distinct subpopulations: a population of 40-100-nm-wide filament bundles radiated from the leading edge, and a second population of branching short filaments filled the volume between the dorsal and ventral membrane surfaces. Together, the two populations formed the three-dimensional structural network seen within expanding lamellipodia. Interaction of the actin filaments with the ventral membrane surface occurred along the length of the filaments via membrane associated proteins. The long bundled filament population was primarily involved in these interactions. The filament tips of either population appeared to interact with the membrane only at the leading edge; this interaction was mediated by a globular Triton-insoluble material. Actin filament polarity was determined by decoration with myosin S1 or heavy meromyosin. Previous reports have suggested that the polarity of the actin filaments in motile cells is uniform, with the barbed ends toward the leading edge. We observed that the actin filament polarity within growth cone lamellipodia is not uniform; although the predominant orientation was with the barbed end toward the leading edge (47-56%), 22-25% of the filaments had the opposite orientation with their pointed ends toward the leading edge, and 19-31% ran parallel to the leading edge. The two actin filament populations display distinct polarity profiles: the longer filaments appear to be oriented predominantly with their barbed ends toward the leading edge, whereas the short filaments appear to be randomly oriented. The different length, organization and polarity of the two filament populations suggest that they differ in stability and function. The population of bundled long filaments, which appeared to be more ventrally located and in contact with membrane proteins, may be more stable than the population of short branched filaments. The location, organization, and polarity of the long bundled filaments suggest that they may be necessary for the expansion of lamellipodia and for the production of tension mediated by receptors to substrate adhesion molecules.

scholarly journals Xenopus cytoplasmic linker–associated protein 1 (XCLASP1) promotes axon elongation and advance of pioneer microtubules

2013 ◽  
Vol 24 (10) ◽  
pp. 1544-1558 ◽  
Author(s):  
Astrid Marx ◽  
William J. Godinez ◽  
Vasil Tsimashchuk ◽  
Peter Bankhead ◽  
Karl Rohr ◽  
...  
Keyword(s):  
Growth Cone ◽  
Binding Protein ◽  
Leading Edge ◽  
Growth Cones ◽  
Retrograde Flow ◽  
Spinal Cord Neurons ◽  
Actin Organization ◽  
Axon Elongation ◽  
Axon Extension ◽  
Potential Link

Dynamic microtubules (MTs) are required for neuronal guidance, in which axons extend directionally toward their target tissues. We found that depletion of the MT-binding protein Xenopus cytoplasmic linker–associated protein 1 (XCLASP1) or treatment with the MT drug Taxol reduced axon outgrowth in spinal cord neurons. To quantify the dynamic distribution of MTs in axons, we developed an automated algorithm to detect and track MT plus ends that have been fluorescently labeled by end-binding protein 3 (EB3). XCLASP1 depletion reduced MT advance rates in neuronal growth cones, very much like treatment with Taxol, demonstrating a potential link between MT dynamics in the growth cone and axon extension. Automatic tracking of EB3 comets in different compartments revealed that MTs increasingly slowed as they passed from the axon shaft into the growth cone and filopodia. We used speckle microscopy to demonstrate that MTs experience retrograde flow at the leading edge. Microtubule advance in growth cone and filopodia was strongly reduced in XCLASP1-depleted axons as compared with control axons, but actin retrograde flow remained unchanged. Instead, we found that XCLASP1-depleted growth cones lacked lamellipodial actin organization characteristic of protrusion. Lamellipodial architecture depended on XCLASP1 and its capacity to associate with MTs, highlighting the importance of XCLASP1 in actin–microtubule interactions.

Nerve growth factor stimulates coupling of beta1 integrin to distinct transport mechanisms in the filopodia of growth cones

2000 ◽  
Vol 113 (17) ◽  
pp. 3003-3012 ◽  
Author(s):  
P.W. Grabham ◽  
M. Foley ◽  
A. Umeojiako ◽  
D.J. Goldberg
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Actin Cytoskeleton ◽  
Leading Edge ◽  
Growth Cones ◽  
Myosin Atpase ◽  
Retrograde Flow ◽  
Transport Mechanisms ◽  
Nerve Growth ◽  
Beta1 Integrin

The cycling of membrane receptors for substrate-bound proteins via their interaction with the actin cytoskeleton at the leading edge of growth cones and other motile cells is important for neurite outgrowth and cell migration. Receptor delivered to the leading edge binds to its ligand, which induces coupling of the receptor to a rearward flowing network of actin filaments. This coupling is thought to facilitate advance. We show here that a soluble growth factor stimulates this cycling. We have used single particle tracking to monitor the effects of nerve growth factor (NGF) on the movements of beta1 integrin in the plane of the plasma membrane of the filopodia of growth cones. Beta1 integrin was visualized by its binding of 0.2 microm beads coated with a monoclonal Ab directed against an extracellular epitope distant from the binding site for extracellular matrix ligands. The beads were observed by video microscopy. Beads coated with a low concentration of antibody, and therefore bound to unliganded receptor with little cross-linking, showed an increase in both diffusion and directed forward transport in response to NGF. Transport had a net velocity of 37 microm/minute and was characterized by brief periods of sustained forward excursions with a velocity of 75–150 microm/minute. There was a 2-fold increase in the number of beads accumulated at the tips of filopodia after 10 minutes, indicating that NGF enhanced the delivery of beta1 integrin to the periphery. Forward transport was dependent on an intact actin cytoskeleton and myosin ATPase, since treatment with cytochalasin D or the myosin ATPase inhibitor butanedione monoxime inhibited the transport but not the diffusion of receptors. NGF also greatly increased the steady rearward migration of beads coated with a high density of (β)1 integrin antibody, indicating that coupling of cross-linked receptor to the retrograde flow of actin is also enhanced. The rate of the retrograde flow of actin was unaffected by NGF. These studies show that a soluble factor can stimulate the coupling of a receptor for substrate-bound factor to two actomyosin-based transport mechanisms and thus facilitate the response of the growth cone to the substrate-bound factor by increasing cycling of the receptor at the periphery.

scholarly journals Branched actin networks are assembled on microtubules by adenomatous polyposis coli for targeted membrane protrusion

2020 ◽  
Vol 219 (9) ◽  
Author(s):  
Nadia Efimova ◽  
Changsong Yang ◽  
Jonathan X. Chia ◽  
Ning Li ◽  
Christopher J. Lengner ◽  
...  
Keyword(s):  
Adenomatous Polyposis Coli ◽  
Hippocampal Neurons ◽  
Leading Edge ◽  
Growth Cones ◽  
Network Interface ◽  
Adenomatous Polyposis ◽  
Polyposis Coli ◽  
Actin Networks ◽  
Underlying Mechanisms ◽  
Filament Networks

Cell migration is driven by pushing and pulling activities of the actin cytoskeleton, but migration directionality is largely controlled by microtubules. This function of microtubules is especially critical for neuron navigation. However, the underlying mechanisms are poorly understood. Here we show that branched actin filament networks, the main pushing machinery in cells, grow directly from microtubule tips toward the leading edge in growth cones of hippocampal neurons. Adenomatous polyposis coli (APC), a protein with both tumor suppressor and cytoskeletal functions, concentrates at the microtubule-branched network interface, whereas APC knockdown nearly eliminates branched actin in growth cones and prevents growth cone recovery after repellent-induced collapse. Conversely, encounters of dynamic APC-positive microtubule tips with the cell edge induce local actin-rich protrusions. Together, we reveal a novel mechanism of cell navigation involving APC-dependent assembly of branched actin networks on microtubule tips.

Sign in / Sign up

Export Citation Format

Share Document