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Results for “Cell Movement”

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At least 145 records · Page 8Linked to original sources

PubMed2000

Role of p120 Ras-GAP in directed cell movement.

We have used cell lines deficient in p120 Ras GTPase activating protein (Ras-GAP) to investigate the roles of Ras-GAP and the associated p190 Rho-GAP (p190) in cell polarity and cell migration. Cell wounding assays showed that Ras-GAP-deficient cells were incapable of establishing complete cell polarity and migration into the wound. Stimulation of mutant cells with growth factor rescued defects in cell spreading, Golgi apparatus fragmentation, and polarized vesicular transport and partially rescued migration in a Ras-dependent manner. However, for directional movement, the turnover of stress fibers and focal adhesions to produce an elongate morphology was dependent on the constitutive association between Ras-GAP and p190, independent of Ras regulation. Disruption of the phosphotyrosine-mediated Ras-GAP/p190 complex by microinjecting synthetic peptides derived from p190 sequences in wild-type cells caused a suppression of actin filament reorientation and migration. From these observations we suggest that although Ras-GAP is not directly required for motility per se, it is important for cell polarization by regulating actin stress fiber and focal adhesion reorientation when complexed with 190. This observation suggests a specific function for Ras-GAP separate from Ras regulation in cell motility.

Animals↗

PubMed2000

Dictyostelium: a model for regulated cell movement during morphogenesis.

Dictyostelium has played an important role in unraveling the pathways that control cell movement and chemotaxis. Recent studies have started to elucidate the pathways that control cell sorting, morphogenesis, and the establishment of spatial patterning in this system. In doing so, they provide new insights into how cell movements within a multicellular organism are regulated and the importance of pathways that are similar to those that regulate chemotaxis of cells on two-dimensional surfaces during aggregation.

Animals↗

PubMed2006

Visualizing signaling and cell movement during the multicellular stages of dictyostelium development.

Time-lapse microscopy provides a powerful tool with which to study cell behavior during Dictyostelium development. On a macroscopic level, the overall cell movement patterns that give rise to the complex multicellular structures such as slugs and fruiting bodies can be studied together with the signal waves that coordinate cell movement. Using green fluorescent protein fusion proteins, it is also possible to visualize the cytoskeleton or signal transduction processes at high resolution in single cells in their multicellular environment.

Animals↗

PubMed2001

WASP and WAVE family proteins: key molecules for rapid rearrangement of cortical actin filaments and cell movement.

Reorganization of cortical actin filaments plays critical roles in cell movement and pattern formation. Recently, the WASP and WAVE family proteins WASP and N-WASP, and WAVE1, WAVE2 and WAVE3 have been shown to regulate cortical actin filament reorganization in response to extracellular stimuli. These proteins each have a verprolin-homology (V) domain, cofilin-homology (C) domain and an acidic (A) region at the C-terminus, through which they activate the Arp2/3 complex, leading to rapid actin polymerization. N-WASP is usually present as an inactive form in which the VCA region is masked. Cooperative binding of Cdc42 and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) exposes the VCA region, activating N-WASP. In addition to this activation mechanism, WISH also activates N-WASP independently of Cdc42 and PtdIns(4,5)P(2), by binding to the proline-rich region of N-WASP. N-WASP activation induces formation of filopodia in vivo. In contrast, the ubiquitously expressed form of WAVE2 is activated downstream of Rac, leading to formation of lamellipodia. In this case, IRSp53 transmits a signal from Rac to WAVE2 through formation of a ternary Rac-IRSp53-WAVE2 complex. Thus, N-WASP, which is activated downstream of Cdc42 or independently by WISH, induces formation of filopodia and WAVE2, which is activated via IRSp53 downstream of Rac, induces formation of lamellipodia.

Actin Cytoskeleton↗

PubMed1978

Cell movement and the mechanism of invasiveness: a survey of the behaviour of some normal and malignant cells implanted into the developing chick wing bud.

A survey of the behaviour of a variety of normal and malignant tumours and cells has been carried out to gain insights into the mechanisms of tumour invasiveness. The tumours and cells were implanted into the developing chick wing bud, which is a loose mesenchyme bounded by ectoderm. The distribution of the grafted cells was examined histologically after one or two days. The special feature of this assay is that the behaviour of cells is tested in a 3-dimensional tissue. Cells from 3 different carcinomas, mouse lung tumour, rat bladder tumour and human breast tumour did not invade the mesenchyme, whereas trophoblast, sarcoma 180, cultured hamster fibroblasts (BHK, PyBHK, Nil 8, HSV Nil 8) and neuroblastoma cells did. Cells from embryonic pigmented retina and heart ventricle were non-invasive. These results suggest that cell movement may not be a common feature of all invasive tumours. The cells that did move into the mesenchyme appeared to do so by various mechanisms. Lack of contact inhibition of movement, although probably involved in the invasiveness of sarcoma 180 cells, does not appear to be necessary for invasion: cells that have been shown to exhibit contact inhibition of movement (BHK and PyBHK) also invade. Both normal and transformed cells (BHK and PyBHK; Nil 8 and HSV Nil 8) moved into the mesenchyme. Other invading cells, such as trophoblast, neuroblastoma and to a small extent, HSV Nil 8 cells, destroy the adjacent host tissue and this may be important in the invasiveness of these cells. The patterns of invasion and interactions with the host tissue were varied. Trophoblast and the fibroblasts were often elongated along the basement membrane at the ectoderm/mesenchyme border and also closely apposed to the endothelial linings of blood vessels. Sarcoma 180 and neuroblastoma cells clustered around nerves. The embryonic tissues and neuroblastoma cells were often associated with blood vessels. These results are discussed in relation to tumour invasion. A striking finding was that the carcinoma cells were frequently found positioned within the wing ectoderm on the basement membrane. This affinity of carcinoma cells for the epithelium rather than the mesenchyme leads to a reappraisal of the mechanisms involved in the invasiveness of carcinomas.

Animals↗

PubMed1976

[Quantitative evaluation of periodicity of cell movement in the process of aggregation].

A method of quantitative estimation of quasiperiodic cell movements is considered which allows to approximate the process under study by the sum of trigonometric functions. The possibilities of the method are deomonstrated in the analysis of cell and aggregate movement during the development of a sponge Ephydatia fluviatilis from dissociated cells, taken as an example. The spectral composition of the movement of cell aggregates was found to change with time; the high frequencies disappear gradualy and the lower ones appear.

Animals↗

PubMed1985

Cessation of epithelial cell movement at native type I collagen-epithelial interface in vitro.

Two foci of gingival epithelial cells from the dog were grown in culture in dishes which were coated with gingival epithelial extracellular matrix (GEEM). A streak of native, reconstituted type I collagen fibers had been placed at the midline of the dish between the two foci. The epithelial cells spread and proliferated in all directions, but their motility ceased at the collagen-epithelial interface, where they piled up and formed several layers. It is concluded that type I collagen may serve as a biological barrier to stop undesirable epithelial cell movement in vivo.

Animals↗

PubMed2003

TIP, a novel host factor linking callose degradation with the cell-to-cell movement of Potato virus X.

The cell-to-cell movement of Potato virus X (PVX) requires four virus-encoded proteins, the triple gene block (TGB) proteins (TGB25K, TGB12K, and TGB8K) and the coat protein. TGB12K increases the plasmodesmal size exclusion limit (SEL) and may, therefore, interact directly with components of the cell wall or with plant proteins associated with bringing about this change. A yeast two-hybrid screen using TGB12K as bait identified three TGB12K-interacting proteins (TIP1, TIP2, and TIP3). All three TIPs interacted specifically with TGB12K but not with TGB25K or TGB8K. Similarly, all three TIPs interacted with beta-1,3-glucanase, the enzyme that may regulate plasmodesmal SEL through callose degradation. Sequence analyses revealed that the TIPs encode very similar proteins and that TIP1 corresponds to the tobacco ankyrin repeat-containing protein HBP1. A TIP1::GFP fusion protein localized to the cytoplasm. Coexpression of this fusion protein with TGB12K induced cellular changes manifested as deposits of additional cytoplasm at the cell periphery. This work reports a direct link between a viral movement protein required to increase plasmodesmal SEL and a host factor that has been implicated as a key regulator of plasmodesmal SEL. We propose that the TIPs are susceptibility factors that modulate the plasmodesmal SEL.

Amino Acid Sequence↗

PubMed2005

A movement protein and three capsid proteins are all necessary for the cell-to-cell movement of apple latent spherical cheravirus.

Immunoblot analysis of apple latent spherical cheravirus (ALSV)-infected leaves using a polyclonal antibody against the 21 C-terminal amino acids of a 53 K/42 K movement protein (MP) showed that a protein with an Mr of 42 kDa (42KP) is the dominant form found in vivo, which could indicate that the second AUG is used as an initiation codon of a ORF in RNA2. Co-expression of GFP with 42KP in tobacco epidermal cells showed that 42KP is able to facilitate cell-to-cell trafficking of GFP that is expressed in the same cells. The analysis of deletion mutants on each of MP, Vp24, Vp20, or Vp25 using an ALSV vector that stably expresses GFP indicated that an MP and three capsid proteins are all indispensable for the cell-to-cell movement of the virus. In ultrathin sections of infected leaves, a file of virus-like particles passing through the plasmodesmata connecting neighboring cells and tubular structures containing virus-like particles extending into the cytoplasm were observed. These results show that ALSV moves from cell to cell as virus particles.

Blotting, Western↗

PubMed2004

Cell movements controlled by the Notch signalling cascade during foregut development in Drosophila.

Notch signalling is an evolutionarily conserved cell interaction mechanism, the role of which in controlling cell fate choices has been studied extensively. Recent studies in both vertebrates and invertebrates revealed additional functions of Notch in proliferation and apoptotic events. We provide evidence for an essential role of the Notch signalling pathway during morphogenetic cell movements required for the formation of the foregut-associated proventriculus organ in the Drosophila embryo. We demonstrate that the activation of the Notch receptor occurs in two rows of boundary cells in the proventriculus primordium. The boundary cells delimit a population of foregut epithelial cells that invaginate into the endodermal midgut layer during proventriculus morphogenesis. Notch receptor activation requires the expression of its ligand Delta in the invaginating cells and apical Notch receptor localisation in the boundary cells. We further show that the movement of the proventricular cells is dependent on the short stop gene that encodes the Drosophila plectin homolog of vertebrates and is a cytoskeletal linker protein of the spectraplakin superfamily. short stop is transcriptionally activated in response to the Notch signalling pathway in boundary cells and we demonstrate that the localisation of the Notch receptor and Notch signalling activity depend on short stop activity. Our results provide a novel link between the Notch signalling pathway and cytoskeletal reorganisation controlling cell movement during the development of foregut-associated organs.

Actins↗

PubMed2000

Light affects cAMP signaling and cell movement activity in Dictyostelium discoideum.

The multicellular, slug stage of the slime mould Dictyostelium discoideum lacks specific sensory cells and organs but can nevertheless respond in a very sensitive manner to external stimuli such as temperature and light. Within the migrating slug, the behavior of up to 100,000 individual amoebae is coordinated by cAMP mediated cell-cell signaling and chemotaxis. We report here the striking result that light directly modulates the cAMP cell-cell signaling system. Light-induced secretion of cAMP from the slug tips decreased the period length of optical density waves and speeded up cell movement. A local effect of light on cAMP release within the slug tip could modulate cell movement within the slug and thus control its phototactic turning and orientation toward a light source.

Animals↗

PubMed1984

A new microtechnique for quantitating cell movement in vitro using polystyrene bead monolayers.

In this paper we describe a new and simple technique for studying cell movement in vitro. This method is based upon the migration of endothelial cells on polystyrene bead monolayers. It permits the rapid preparation and screening of multiple 96-well plates for effects on migration, requires fewer samples per test and has the potential for precise quantitation by digital image analysis. The locomotive response of endothelial cells in response to different protein matrices (fibrin, collagen, albumin, gelatin), as used by this technique, is also described. Experiments in progress have shown that this technique can be used to study the effect of different factors (monoclonal antibodies, lymphokines, etc.) on cell migration, and that it may be used with other cell types which exhibit cell migration on substrates in vitro.

Animals↗

PubMed2005

An integrated approach to the characterization of cell movement.

BACKGROUND: Most phenomena in developmental biology involve or depend upon cell migration. This article describes a comprehensive framework for the characterization and analysis of trajectories defined by cell movement. The following two perspectives are considered: (a) the behavior of each individual cell and (b) interactions between neighboring pairs of cells. METHODS: The measurements considered for individual trajectories include the velocity magnitude and orientation, maximum spatial dispersion, displacement effectiveness, and displacement entropies. Interactions between two trajectories are characterized by comparing the respective velocities. RESULTS: The potential of the overall framework is illustrated using data of moving cells in different biological environments. The work shows that it is possible to use the new algorithm presented here to characterize cell motility. CONCLUSIONS: The features of the algorithm were successful in determining the motility changes under different experimental conditions.

Algorithms↗

PubMed1999

Mound-cell movement and morphogenesis in Dictyostelium.

To examine the mechanisms of cell locomotion within a three-dimensional (3-D) cell mass, we have undertaken a systematic 3-D analysis of individual cell movements in the Dictyostelium mound, the first 3-D structure to form during development of the fruiting body. We used time-lapse deconvolution microscopy to examine two strains whose motion represents endpoints on the spectrum of motile behaviors that we have observed in mounds. In AX-2 mounds, cell motion is slow and trajectories are a combination of random and radial, compared to KAX-3, in which motion is fivefold faster and most trajectories are rotational. Although radial or rotational motion was correlated with the optical-density wave patterns present in each strain, we also found small but significant subpopulations of cells that moved differently from the majority, demonstrating that optical-density waves are at best insufficient to explain all motile behavior in mounds. In examining morphogenesis in these strains, we noted that AX-2 mounds tended to culminate directly to a fruiting body, whereas KAX-3 mounds first formed a migratory slug. By altering buffering conditions we could interchange these behaviors and then found that mound-cell motions also changed accordingly. This demonstrates a correlation between mound-cell motion and subsequent development, but it is not obligatory. Chimeric mounds composed of only 10% KAX-3 cells and 90% AX-2 cells exhibited rotational motion, suggesting that a diffusible molecule induces rotation, but many of these mounds still culminated directly, demonstrating that rotational motion does not always lead to slug migration. Our observations provide a detailed analysis of cell motion for two distinct modes of mound and slug formation in Dictyostelium.

Algorithms↗

PubMed2001

The Alzheimer amyloid precursor protein (APP) and FE65, an APP-binding protein, regulate cell movement.

FE65 binds to the Alzheimer amyloid precursor protein (APP), but the function of this interaction has not been identified. Here, we report that APP and FE65 are involved in regulation of cell movement. APP and FE65 colocalize with actin and Mena, an Abl-associated signaling protein thought to regulate actin dynamics, in lamellipodia. APP and FE65 specifically concentrate with beta 1-integrin in dynamic adhesion sites known as focal complexes, but not in more static adhesion sites known as focal adhesions. Overexpression of APP accelerates cell migration in an MDCK cell wound--healing assay. Coexpression of APP and FE65 dramatically enhances the effect of APP on cell movement, probably by regulating the amount of APP at the cell surface. These data are consistent with a role for FE65 and APP, possibly in a Mena-containing macromolecular complex, in regulation of actin-based motility.

Actins↗

PubMed1992

Roles for the extracellular matrix in plant development and pollination: a special case of cell movement in plants.

Pattern formation in plants is now thought to be primarily dependent on positional information during development. We discuss the prevalent theories on how position is deciphered by cells in an organism and highlight the recent advances implicating molecules of the cell wall or extracellular matrix (ECM) in this process. We compare the functions of the ECM in plants and animals and describe the various cell and substrate adhesion molecules of the animal ECM which play a role in morphogenesis and cell movement. We propose that analogous molecules may occur in plants and provide evidence for the presence of a substrate adhesion molecule like vitronectin in plants and algae. We provide a model for how substrate adhesion molecules may be involved in a special case of cell movement in plants, pollination.

Animals↗

PubMed2003

A role for cytoplasmic dynein and LIS1 in directed cell movement.

Cytoplasmic dynein has been implicated in numerous aspects of intracellular movement. We recently found dynein inhibitors to interfere with the reorientation of the microtubule cytoskeleton during healing of wounded NIH3T3 cell monolayers. We now find that dynein and its regulators dynactin and LIS1 localize to the leading cell cortex during this process. In the presence of serum, bright diffuse staining was observed in regions of active ruffling. This pattern was abolished by cytochalasin D, and was not observed in cells treated with lysophosphatidic acid, conditions which allow microtubule reorientation but not forward cell movement. Under the same conditions, using total internal reflection fluorescence microscopy, clear punctate dynein/dynactin containing structures were observed along the sides and at the tips of microtubules at the leading edge. Overexpression of dominant negative dynactin and LIS1 cDNAs or injection of antidynein antibody interfered with the rate of cell migration. Together, these results implicate a leading edge cortical pool of dynein in both early and persistent steps in directed cell movement.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2006

Capsid protein gene and the type of host plant differentially modulate cell-to-cell movement of cowpea chlorotic mottle virus.

A study was undertaken to measure the rate of coat protein (CP) independent cell-to-cell movement of cowpea chlorotic mottle bromovirus (CCMV) in three different host plants. A CCMV RNA3 variant in which the CP gene was substituted with enhanced green fluorescent protein (C3/DeltaCP-EGFP) was coinoculated to three different host plants with transcripts of wild type RNAs 1 and 2. Comparative analysis of cell-to-cell movement monitored by the EGFP expression at various days post inoculation revealed that the rate of spread varied with the type of host species inoculated: fastest movement was observed in Nicotiana benthamiana while the rate spread was significantly slower in the natural host cowpea. When CP was expressed as EGFP fusion (C3/CP:EGFP) the rate of spread in N. benthamiana and C. quinoa was slower than that was observed in the absence of CP and remained subliminal in cowpea. Analysis of infection foci by confocal laser scanning microscope revealed that localization of CP:EGFP fusion was distinct in N. benthamiana and C.quinoa and accumulated as fluorescent inclusions at the cell periphery. Additional experiments involving coinoculation of either C3/DeltaCP-EGFP or C3/CP:EGFP with heterologous brome mosaic bromovirus (BMV) genomic RNAs 1 and 2 revealed that, in addition to movement protein and CP, viral replicase also influences cell-to-cell spread. The significance of these results in relation to the mechanism of bromovirus movement is discussed.

Bromovirus↗