Magnetic super-hydrophilic carbon nanotubes/graphene oxide composite as nanocarriers of mesenchymal stem cells: Insights into the time and dose dependences.

PubMed

Granato, Alessandro E C; Rodrigues, Bruno V M; Rodrigues-Junior, Dorival M; Marciano, Fernanda R; Lobo, Anderson O; Porcionatto, Marimelia A

2016-10-01

Among nanostructured materials, multi-walled carbon nanotubes (MWCNT) have demonstrated great potential for biomedical applications in recent years. After oxygen plasma etching, we can obtain super-hydrophilic MWCNT that contain graphene oxide (GO) at their tips. This material exhibits good dispersion in biological systems due to the presence of polar groups and its excellent magnetic properties due to metal particle residues from the catalyst that often remain trapped in its walls and tips. Here, we show for the first time a careful biological investigation using magnetic superhydrophilic MWCNT/GO (GCN composites). The objective of this study was to investigate the application of GCN for the in vitro immobilization of mesenchymal stem cells. Our ultimate goal was to develop a system to deliver mesenchymal stem cells to different tissues and organs. We show here that mesenchymal stem cells were able to internalize GCN with a consequent migration when subjected to a magnetic field. The cytotoxicity of GCN was time- and dose-dependent. We also observed that GCN internalization caused changes in the gene expression of the proteins involved in cell adhesion and migration, such as integrins, laminins, and the chemokine CXCL12, as well as its receptor CXCR4. These results suggest that GCN represents a potential new platform for mesenchymal stem cell immobilization at injury sites. Copyright © 2016 Elsevier B.V. All rights reserved.

The Long Non-coding RNA HOTTIP Enhances Pancreatic Cancer Cell Proliferation, Survival and Migration

EPA Science Inventory

ABSTRACTHOTTIP is a long non-coding RNA (lncRNA) transcribed from the 5' tip of the HOXA locus and is associated with the polycomb repressor complex 2 (PRC2) and WD repeat containing protein 5 (WDR5)/mixed lineage leukemia 1 (MLL1) chromatin modifying complexes. HOTTIP is expres...

Melatonin enhances the recovery of cryopreserved shoot tips of American elm (Ulmus Americana L.)

USDA-ARS?s Scientific Manuscript database

Climate change and the global migrations of people and goods have exposed trees to new diseases and abiotic challenges that threaten the survival of species. In vitro germplasm storage via cryopreservation is an effective tool to ensure conservation of tree species, but plant cells and tissues are e...

MIF Promotes Classical Activation and Conversion of Inflammatory Ly6Chigh Monocytes into TipDCs during Murine Toxoplasmosis

PubMed Central

Ruiz-Rosado, Juan de Dios; Olguín, Jonadab E.; Juárez-Avelar, Imelda; Saavedra, Rafael; Terrazas, Luis I.; Robledo-Avila, Frank H.; Vazquez-Mendoza, Alicia; Fernández, Jacquelina; Satoskar, Abhay R.; Partida-Sánchez, Santiago; Rodriguez-Sosa, Miriam

2016-01-01

Macrophage migration inhibitory factor (MIF) mediates immunity against Toxoplasma gondii infection by inducing inflammatory cytokines required to control the parasite replication. However, the role of this inflammatory mediator in the cell-mediated immune response against this infection is still poorly understood. Here, we used T. gondii-infected WT and Mif −/− mice to analyze the role of MIF in the maturation of CD11b+ and CD8α + dendritic cells (DCs). We found that MIF promotes maturation of CD11b+ but not CD8α + DCs, by inducing IL-12p70 production and CD86 expression. Infected Mif −/− mice showed significantly lower numbers of TNF and inducible nitric oxide synthase- (iNOS-) producing DCs (TipDCs) compared to infected WT mice. The adoptive transfer of Ly6Chigh monocytes into infected WT or Mif −/− mice demonstrated that MIF participates in the differentiation of Ly6Chigh monocytes into TipDCs. In addition, infected Mif −/− mice display a lower percentage of IFN-γ-producing natural killer (NK) cells compared to WT mice, which is associated with reducing numbers of TipDCs in Mif −/− mice. Furthermore, administration of recombinant MIF (rMIF) into T. gondii-infected Mif −/− mice restored the numbers of TipDCs and reversed the susceptible phenotype of Mif −/− mice. Collectively, these results demonstrate an important role for MIF inducing cell-mediated immunity to T. gondii infection. PMID:27057101

The glycan-binding protein galectin-1 controls survival of epithelial cells along the crypt-villus axis of small intestine.

PubMed

Muglia, C; Mercer, N; Toscano, M A; Schattner, M; Pozner, R; Cerliani, J P; Gobbi, R Papa; Rabinovich, G A; Docena, G H

2011-05-26

Intestinal epithelial cells serve as mechanical barriers and active components of the mucosal immune system. These cells migrate from the crypt to the tip of the villus, where different stimuli can differentially affect their survival. Here we investigated, using in vitro and in vivo strategies, the role of galectin-1 (Gal-1), an evolutionarily conserved glycan-binding protein, in modulating the survival of human and mouse enterocytes. Both Gal-1 and its specific glyco-receptors were broadly expressed in small bowel enterocytes. Exogenous Gal-1 reduced the viability of enterocytes through apoptotic mechanisms involving activation of both caspase and mitochondrial pathways. Consistent with these findings, apoptotic cells were mainly detected at the tip of the villi, following administration of Gal-1. Moreover, Gal-1-deficient (Lgals1(-/-)) mice showed longer villi compared with their wild-type counterparts in vivo. In an experimental model of starvation, fasted wild-type mice displayed reduced villi and lower intestinal weight compared with Lgals1(-/-) mutant mice, an effect reflected by changes in the frequency of enterocyte apoptosis. Of note, human small bowel enterocytes were also prone to this pro-apoptotic effect. Thus, Gal-1 is broadly expressed in mucosal tissue and influences the viability of human and mouse enterocytes, an effect which might influence the migration of these cells from the crypt, the integrity of the villus and the epithelial barrier function.

Podosomes, But Not the Maturation Status, Determine the Protease-Dependent 3D Migration in Human Dendritic Cells.

PubMed

Cougoule, Céline; Lastrucci, Claire; Guiet, Romain; Mascarau, Rémi; Meunier, Etienne; Lugo-Villarino, Geanncarlo; Neyrolles, Olivier; Poincloux, Renaud; Maridonneau-Parini, Isabelle

2018-01-01

Dendritic cells (DC) are professional Antigen-Presenting Cells scattered throughout antigen-exposed tissues and draining lymph nodes, and survey the body for pathogens. Their ability to migrate through tissues, a 3D environment, is essential for an effective immune response. Upon infection, recognition of Pathogen-Associated Molecular Patterns (PAMP) by Toll-like receptors (TLR) triggers DC maturation. Mature DC (mDC) essentially use the protease-independent, ROCK-dependent amoeboid mode in vivo , or in collagen matrices in vitro . However, the mechanisms of 3D migration used by human immature DC (iDC) are still poorly characterized. Here, we reveal that human monocyte-derived DC are able to use two migration modes in 3D. In porous matrices of fibrillar collagen I, iDC adopted the amoeboid migration mode. In dense matrices of gelled collagen I or Matrigel, iDC used the protease-dependent, ROCK-independent mesenchymal migration mode. Upon TLR4 activation by LPS, mDC-LPS lose the capacity to form podosomes and degrade the matrix along with impaired mesenchymal migration. TLR2 activation by Pam 3 CSK 4 resulted in DC maturation, podosome maintenance, and efficient mesenchymal migration. Under all these conditions, when DC used the mesenchymal mode in dense matrices, they formed 3D podosomes at the tip of cell protrusions. Using PGE 2 , known to disrupt podosomes in DC, we observed that the cells remained in an immature status and the mesenchymal migration mode was abolished. We also observed that, while CCL5 (attractant of iDC) enhanced both amoeboid and mesenchymal migration of iDC, CCL19 and CCL21 (attractants of mDC) only enhanced mDC-LPS amoeboid migration without triggering mesenchymal migration. Finally, we examined the migration of iDC in tumor cell spheroids, a tissue-like 3D environment. We observed that iDC infiltrated spheroids of tumor cells using both migration modes. Altogether, these results demonstrate that human DC adopt the mesenchymal mode to migrate in 3D dense environments, which relies on their capacity to form podosomes independent of their maturation status, paving the way of further investigations on in vivo DC migration in dense tissues and its regulation during infections.

PCP Signaling between Migrating Neurons and their Planar-Polarized Neuroepithelial Environment Controls Filopodial Dynamics and Directional Migration

PubMed Central

Moens, Cecilia B.

2016-01-01

The planar cell polarity (PCP) pathway is a cell-contact mediated mechanism for transmitting polarity information between neighboring cells. PCP “core components” (Vangl, Fz, Pk, Dsh, and Celsr) are essential for a number of cell migratory events including the posterior migration of facial branchiomotor neurons (FBMNs) in the plane of the hindbrain neuroepithelium in zebrafish and mice. While the mechanism by which PCP signaling polarizes static epithelial cells is well understood, how PCP signaling controls highly dynamic processes like neuronal migration remains an important outstanding question given that PCP components have been implicated in a range of directed cell movements, particularly during vertebrate development. Here, by systematically disrupting PCP signaling in a rhombomere-restricted manner we show that PCP signaling is required both within FBMNs and the hindbrain rhombomere 4 environment at the time when they initiate their migration. Correspondingly, we demonstrate planar polarized localization of PCP core components Vangl2 and Fzd3a in the hindbrain neuroepithelium, and transient localization of Vangl2 at the tips of retracting FBMN filopodia. Using high-resolution timelapse imaging of FBMNs in genetic chimeras we uncover opposing cell-autonomous and non-cell-autonomous functions for Fzd3a and Vangl2 in regulating FBMN protrusive activity. Within FBMNs, Fzd3a is required to stabilize filopodia while Vangl2 has an antagonistic, destabilizing role. However, in the migratory environment Fzd3a acts to destabilize FBMN filopodia while Vangl2 has a stabilizing role. Together, our findings suggest a model in which PCP signaling between the planar polarized neuroepithelial environment and FBMNs directs migration by the selective stabilization of FBMN filopodia. PMID:26990447

The glycan-binding protein galectin-1 controls survival of epithelial cells along the crypt-villus axis of small intestine

PubMed Central

Muglia, C; Mercer, N; Toscano, M A; Schattner, M; Pozner, R; Cerliani, J P; Gobbi, R Papa; Rabinovich, G A; Docena, G H

2011-01-01

Intestinal epithelial cells serve as mechanical barriers and active components of the mucosal immune system. These cells migrate from the crypt to the tip of the villus, where different stimuli can differentially affect their survival. Here we investigated, using in vitro and in vivo strategies, the role of galectin-1 (Gal-1), an evolutionarily conserved glycan-binding protein, in modulating the survival of human and mouse enterocytes. Both Gal-1 and its specific glyco-receptors were broadly expressed in small bowel enterocytes. Exogenous Gal-1 reduced the viability of enterocytes through apoptotic mechanisms involving activation of both caspase and mitochondrial pathways. Consistent with these findings, apoptotic cells were mainly detected at the tip of the villi, following administration of Gal-1. Moreover, Gal-1-deficient (Lgals1−/−) mice showed longer villi compared with their wild-type counterparts in vivo. In an experimental model of starvation, fasted wild-type mice displayed reduced villi and lower intestinal weight compared with Lgals1−/− mutant mice, an effect reflected by changes in the frequency of enterocyte apoptosis. Of note, human small bowel enterocytes were also prone to this pro-apoptotic effect. Thus, Gal-1 is broadly expressed in mucosal tissue and influences the viability of human and mouse enterocytes, an effect which might influence the migration of these cells from the crypt, the integrity of the villus and the epithelial barrier function. PMID:21614093

Evolutionary modification of mesenchyme cells in sand dollars in the transition from indirect to direct development.

PubMed

Yajima, Mamiko

2007-01-01

Peronella japonica, an intermediate type of direct-developing sand dollar, forms an abbreviated pluteus, followed by metamorphosis within 3 days without feeding. In this species, ingression of mesenchyme cells starts before hatching and continues until gastrulation, but no typical secondary mesenchyme cells (SMCs) migrate from the tip of the archenteron. Here, I investigated the cell lineage of mesenchyme cells through metamorphosis in P. japonica and found that mesenchyme cells migrating before hatching (early mesenchyme cells [EMCs]) were exclusively derived from micromeres and became larval skeletogenic cells, whereas cells migrating after hatching (late mesenchyme cells [LMCs]) appeared to contain several nonskeletogenic cells. Thus, it is likely that EMCs are homologous to primary mesenchyme cells (PMCs) and LMCs are similar to the SMCs of typical indirect developers, suggesting that heterochrony in the timing of mesenchyme cell ingression may have occurred in this species. EMCs disappeared after metamorphosis and LMCs were involved in adult skeletogenesis. Embryos from which micromeres were removed at the 16-cell stage formed armless plutei that went on to form adult skeletons and resulted in juveniles with normal morphology. These results suggest that in P. japonica, LMCs form adult skeletal elements, whereas EMCs are specialized for larval spicule formation. The occurrence of evolutionary modifications in mesenchyme cells in the transition from indirect to direct development of sand dollars is discussed.

Long non-coding RNA HOTTIP promotes prostate cancer cells proliferation and migration by sponging miR-216a-5p.

PubMed

Yang, Bin; Gao, Ge; Wang, Zhixin; Sun, Daju; Wei, Xin; Ma, Yanan; Ding, Youpeng

2018-06-08

Long non-coding RNAs (lncRNAs) are a class of ncRNAs with > 200 nucleotides in length that regulate gene expression. The HOXA transcript at the distal tip (HOTTIP) lncRNA plays an important role in carcinogenesis, however, the underlying role of HOTTIP in prostate cancer (PCa) remain unknown. The aim of the present study was to evaluate the expression and function of HOTTIP in PCa. In the present study, we analyzed HOTTIP expression levels of 86 PCa patients in tumor and adjacent normal tissue by real-time quantitative PCR. Knockdown or overexpression of HOTTIP was performed to explore its roles in cell proliferation, migration, invasion, and cell cycle. Furthermore, bioinformatics online programs predicted and luciferase reporter assay were used to validate the association of HOTTIP and miR-216a-5p in PCa cells. Our results found that HOTTIP was up-regulated in human primary PCa tissues with lymph node metastasis. Knockdown of HOTTIP inhibited PCa cell proliferation, migration and invasion. Overexpression of HOTTIP promoted cell proliferation, migration and invasion of PCa cells. Bioinformatics online programs predicted that HOTTIP sponge miR-216a-5p at 3'-UTR with complementary binding sites, which was validated using luciferase reporter assay. HOTTIP could negatively regulate the expression of miR-216a-5p in PCa cells. Above all, knockdown of HOTTIP could represent a rational therapeutic strategy for PCa. ©2018 The Author(s).

Microcoil embolization during abdominal vascular interventions through microcatheters with a tip of 2 French or less.

PubMed

Miyayama, Shiro; Yamashiro, Masashi; Hattori, Yuki; Orito, Nobuaki; Matsui, Ken; Tsuji, Kazunobu; Yoshida, Miki; Matsui, Osamu

2011-05-01

The aim of this study was to evaluate the technical aspects of embolization using microcoils through a microcatheter with a tip of 2F or smaller during abdominal vascular interventions. Coil embolization through a microcatheter with a tip of 2F or smaller was attempted in 73 procedures. Two types of microcoil-Liquid Coil (Boston Scientific, Watertown, MA, USA) and Tornado Coil (Cook, Bloomington, IN, USA)-were deployed through four types of thinner microcatheter [2F tip (n = 49) and 1.8F tip (n = 24)]. Coil jams in the microcatheter and coil migration were evaluated. In total, 286 microcoils were placed (mean ± SD, 3.9 ± 4.3 coils per procedure, range 1-32 coils). In 19 procedures (26.9%), Liquid Coils were used alone. In 44 (60.3%), Tornado Coils were used alone. In 10 (13.7%), Liquid Coils and Tornado Coils were combined. There were no coil jams in the microcatheter in this series. One Tornado Coil (0.3%) delivered into the gastroduodenal artery migrated to the right hepatic artery. Liquid Coils and Tornado Coils can be placed through a thinner microcatheter without difficulty. However, there is a risk of coil migration in large vessels or at the proximal site because the catheter tip is not stabilized.

Cyclic AMP Response Element Binding Protein Mediates Pathological Retinal Neovascularization via Modulating DLL4-NOTCH1 Signaling

PubMed Central

Singh, Nikhlesh K.; Kotla, Sivareddy; Kumar, Raj; Rao, Gadiparthi N.

2015-01-01

Retinal neovascularization is the most common cause of moderate to severe vision loss in all age groups. Despite the use of anti-VEGFA therapies, this complication continues to cause blindness, suggesting a role for additional molecules in retinal neovascularization. Besides VEGFA and VEGFB, hypoxia induced VEGFC expression robustly. Based on this finding, we tested the role of VEGFC in pathological retinal angiogenesis. VEGFC induced proliferation, migration, sprouting and tube formation of human retinal microvascular endothelial cells (HRMVECs) and these responses require CREB-mediated DLL4 expression and NOTCH1 activation. Furthermore, down regulation of VEGFC levels substantially reduced tip cell formation and retinal neovascularization in vivo. In addition, we observed that CREB via modulating the DLL4-NOTCH1 signaling mediates VEGFC-induced tip cell formation and retinal neovascularization. In regard to upstream mechanism, we found that down regulation of p38β levels inhibited hypoxia-induced CREB-DLL4-NOTCH1 activation, tip cell formation, sprouting and retinal neovascularization. Based on these findings, it may be suggested that VEGFC besides its role in the regulation of lymphangiogenesis also plays a role in pathological retinal angiogenesis and this effect depends on p38β and CREB-mediated activation of DLL4-NOTCH1 signaling. PMID:26870802

Computational modeling of three-dimensional ECM-rigidity sensing to guide directed cell migration.

PubMed

Kim, Min-Cheol; Silberberg, Yaron R; Abeyaratne, Rohan; Kamm, Roger D; Asada, H Harry

2018-01-16

Filopodia have a key role in sensing both chemical and mechanical cues in surrounding extracellular matrix (ECM). However, quantitative understanding is still missing in the filopodial mechanosensing of local ECM stiffness, resulting from dynamic interactions between filopodia and the surrounding 3D ECM fibers. Here we present a method for characterizing the stiffness of ECM that is sensed by filopodia based on the theory of elasticity and discrete ECM fiber. We have applied this method to a filopodial mechanosensing model for predicting directed cell migration toward stiffer ECM. This model provides us with a distribution of force and displacement as well as their time rate of changes near the tip of a filopodium when it is bound to the surrounding ECM fibers. Aggregating these effects in each local region of 3D ECM, we express the local ECM stiffness sensed by the cell and explain polarity in the cellular durotaxis mechanism.

Symmetric rearrangement of groundwater-fed streams.

PubMed

Yi, Robert; Cohen, Yossi; Devauchelle, Olivier; Gibbins, Goodwin; Seybold, Hansjörg; Rothman, Daniel H

2017-11-01

Streams shape landscapes through headward growth and lateral migration. When these streams are primarily fed by groundwater, recent work suggests that their tips advance to maximize the symmetry of the local Laplacian field associated with groundwater flow. We explore the extent to which such forcing is responsible for the lateral migration of streams by studying two features of groundwater-fed streams in Bristol, Florida: their confluence angle near junctions and their curvature. First, we find that, while streams asymptotically form a 72° angle near their tips, they simultaneously exhibit a wide 120° confluence angle within approximately 10 m of their junctions. We show that this wide angle maximizes the symmetry of the groundwater field near the junction. Second, we argue that streams migrate laterally within valleys and present a new spectral analysis method to relate planform curvature to the surrounding groundwater field. Our results suggest that streams migrate laterally in response to fluxes from the surrounding groundwater table, providing evidence of a new mechanism that complements Laplacian growth at their tips.

Endothelial Ca2+ oscillations reflect VEGFR signaling-regulated angiogenic capacity in vivo

PubMed Central

Yokota, Yasuhiro; Nakajima, Hiroyuki; Wakayama, Yuki; Muto, Akira; Kawakami, Koichi; Fukuhara, Shigetomo; Mochizuki, Naoki

2015-01-01

Sprouting angiogenesis is a well-coordinated process controlled by multiple extracellular inputs, including vascular endothelial growth factor (VEGF). However, little is known about when and how individual endothelial cell (EC) responds to angiogenic inputs in vivo. Here, we visualized endothelial Ca2+ dynamics in zebrafish and found that intracellular Ca2+ oscillations occurred in ECs exhibiting angiogenic behavior. Ca2+ oscillations depended upon VEGF receptor-2 (Vegfr2) and Vegfr3 in ECs budding from the dorsal aorta (DA) and posterior cardinal vein, respectively. Thus, visualizing Ca2+ oscillations allowed us to monitor EC responses to angiogenic cues. Vegfr-dependent Ca2+ oscillations occurred in migrating tip cells as well as stalk cells budding from the DA. We investigated how Dll4/Notch signaling regulates endothelial Ca2+ oscillations and found that it was required for the selection of single stalk cell as well as tip cell. Thus, we captured spatio-temporal Ca2+ dynamics during sprouting angiogenesis, as a result of cellular responses to angiogenic inputs. DOI: http://dx.doi.org/10.7554/eLife.08817.001 PMID:26588168

SU-F-T-675: Down-Regulating the Expression of Cdc42 and Inhibition of Migration of A549 with Combined Treatment of Ionizing Radiation and Sevoflurane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Y; Feng, J; Huang, Z

Purpose: Cdc42 is involved in cell transformation, proliferation, invasion and metastasis of human cancer cells. Cdc42 overexpression has been reported in several types of cancers. This study investigated the combined treatment effects of ionizing radiation and sevoflurane on down-regulating Cdc42 expression and suppressing migration of human adenocarcinoma cell line A549. Methods: Samples of A549 cells with Cdc42 overexpression were created and Cdc42 expression was determined by Western blotting. Increase of migration speed by Cdc42-HA overexpression was confirmed with an initial in-vitro scratch assay. The cells grown in culture media were separated into 2 groups of 6 samples: one for themore » control and the other was treated with 4% sevoflurane for 5hrs prior to a single-fraction radiation of 4Gy using a 6MV beam. Cell migration speeds of the 2 groups were measured with an initial in-vitro scratch assay. The scratch was created with a pipette tip immediately after treatment and images at 4 post-treatment time points (0h, 3h, 6h, 12h) were acquired. The distance between the two separated sides at 0h was used as reference and subsequent changes of the distance over time was defined as the cell migration speed. Image processing and measurement were performed with an in-house software. The experiment was repeated three times independently to evaluate the repeatability and reliability. Statistical analysis was performed with SPSS 19.0. Results: Western blotting showed the treatment down-regulated Cdc42 overexpression. Quantitative analysis and two-tailed t-test showed that cell migration speed of the treated group was higher than the control group at all time points after treatment (p < 0.02). Conclusion: Combined treatment of 6MV photon and sevoflurane can cause the effects of down-regulating Cdc42 overexpression and decrease of migration speed of A549 cells which provides potential of clinical benefit for the cancer therapy. More investigation is needed to further quantify the benefits of the combined therapy.« less

FGF coordinates air sac development by activation of the EGF ligand Vein through the transcription factor PntP2.

PubMed

Cruz, Josefa; Bota-Rabassedas, Neus; Franch-Marro, Xavier

2015-12-03

How several signaling pathways are coordinated to generate complex organs through regulation of tissue growth and patterning is a fundamental question in developmental biology. The larval trachea of Drosophila is composed of differentiated functional cells and groups of imaginal tracheoblasts that build the adult trachea during metamorphosis. Air sac primordium cells (ASP) are tracheal imaginal cells that form the dorsal air sacs that supply oxygen to the flight muscles of the Drosophila adult. The ASP emerges from the tracheal branch that connects to the wing disc by the activation of both Bnl-FGF/Btl and EGFR signaling pathways. Together, these pathways promote cell migration and proliferation. In this study we demonstrate that Vein (vn) is the EGF ligand responsible for the activation of the EGFR pathway in the ASP. We also find that the Bnl-FGF/Btl pathway regulates the expression of vn through the transcription factor PointedP2 (PntP2). Furthermore, we show that the FGF target gene escargot (esg) attenuates EGFR signaling at the tip cells of the developing ASP, reducing their mitotic rate to allow proper migration. Altogether, our results reveal a link between Bnl-FGF/Btl and EGFR signaling and provide novel insight into how the crosstalk of these pathways regulates migration and growth.

FGF coordinates air sac development by activation of the EGF ligand Vein through the transcription factor PntP2

PubMed Central

Cruz, Josefa; Bota-Rabassedas, Neus; Franch-Marro, Xavier

2015-01-01

How several signaling pathways are coordinated to generate complex organs through regulation of tissue growth and patterning is a fundamental question in developmental biology. The larval trachea of Drosophila is composed of differentiated functional cells and groups of imaginal tracheoblasts that build the adult trachea during metamorphosis. Air sac primordium cells (ASP) are tracheal imaginal cells that form the dorsal air sacs that supply oxygen to the flight muscles of the Drosophila adult. The ASP emerges from the tracheal branch that connects to the wing disc by the activation of both Bnl-FGF/Btl and EGFR signaling pathways. Together, these pathways promote cell migration and proliferation. In this study we demonstrate that Vein (vn) is the EGF ligand responsible for the activation of the EGFR pathway in the ASP. We also find that the Bnl-FGF/Btl pathway regulates the expression of vn through the transcription factor PointedP2 (PntP2). Furthermore, we show that the FGF target gene escargot (esg) attenuates EGFR signaling at the tip cells of the developing ASP, reducing their mitotic rate to allow proper migration. Altogether, our results reveal a link between Bnl-FGF/Btl and EGFR signaling and provide novel insight into how the crosstalk of these pathways regulates migration and growth. PMID:26632449

EGF domain of coagulation factor IX is conducive to exposure of phosphatidylserine.

PubMed

Hidai, Chiaki; Fujiwara, Yusuke; Kokubun, Shinichiro; Kitano, Hisataka

2017-04-01

Lipid rafts are an initiation site for many different signals. Recently, we reported that an EGF domain in activated coagulation factor IX (EGF-F9) increases lipid raft formation and accelerates cell migration. However, the detailed mechanism is not well understood. This study aimed to evaluate the effects of EGF-F9 on the cell membrane. A431 cells (derived from human squamous cell carcinoma) were treated with recombinant EGF-F9. Cells were immunocytochemically stained with probes for lipid rafts or phosphatidylserine (PS). After 3 min of treatment with EGF-F9, cholera toxin subunit B (CTxB) binding domains emerged at the adhesive tips of filopodia. Subsequently, CTxB staining was observed on the filopodial shaft. Finally, large clusters of CTxB domains were observed at the edge of cell bodies. Markers for lipid rafts, such as caveolin-1 and a GPI anchored protein, co-localized with CTxB. Staining with annexin V and XII revealed that PS was exposed at the tips of filopodia, translocated on filopodial shafts, and co-localized with CTxB at the rafts. Immunocytochemistry showed that scramblase-1 protein was present at the filopodial tips. Our data indicates that EGF-F9 accelerates PS exposure around the filopodial adhesion complex and induces clustering of lipid rafts in the cell body. PS exposure is thought to occur on cells undergoing apoptosis. Further study of the function of the EGF-F9 motif in mediating signal transduction is necessary because it is shared by a number of proteins. © 2017 International Federation for Cell Biology.

Transjugular Intrahepatic Portosystemic Shunt Flow Reduction with Adjustable Polytetrafluoroethylene-Covered Balloon-Expandable Stents Using the “Sheath Control” Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blue, Robert C., E-mail: Robert.c.blue@gmail.com; Lo, Grace C.; Kim, Edward

PurposeA complication of transjugular intrahepatic portosystemic shunts (TIPS) placement is refractory portosystemic encephalopathy (PSE) often requiring TIPS reduction. We report the results of a “sheath control technique” utilizing constraining sheaths during deployment of polytetrafluoroethylene (PTFE)-covered balloon-expandable stents, minimizing stent migration, and providing additional procedural control.MethodsTIPS reduction was performed in 10 consecutive patients for PSE using Atrium iCast covered stents (Atrium Maquet Getinge Group, Germany). Within the indwelling TIPS stent, a 9 mm × 59 mm iCast stent was deployed with 2 cm exposed from the sheath’s distal end and the majority of the stent within the sheath to create the distal hourglass shape. During balloonmore » retraction, the stent was buttressed by the sheath. The proximal portion of the stent was angioplastied to complete the hourglass configuration, and the central portion of the stent was dilated to 5 mm. Demographics, pre- and post-procedure laboratory values, and outcomes were recorded.ResultsTen patients underwent TIPS reduction with 100 % technical success. There was no stent migration during stent deployment. All patients experienced initial improvement of encephalopathy. One patient ultimately required complete TIPS occlusion for refractory PSE, and another developed TIPS occlusion 36 days post-procedure. There was no significant trend toward change in patients’ MELD scores immediately post-procedure or at 30 days (p = 0.46, p = 0.47, respectively).ConclusionTIPS reduction using Atrium iCast PTFE balloon-expandable stents using the “sheath control technique” is safe and effective, and minimizes the risk of stent migration.« less

Mesenchymally-derived insulin-like growth factor 1 provides a paracrine stimulus for trophoblast migration.

PubMed

Lacey, Helen; Haigh, Teresa; Westwood, Melissa; Aplin, John D

2002-04-24

Trophoblast migration into maternal decidua is essential for normal pregnancy. It occurs in a defined time window, is spatially highly restricted, and is aberrant in some pathological pregnancies, but the control mechanisms are as yet ill-defined. At the periphery of the placenta, chorionic villi make contact with decidua to form specialised anchoring sites that feed interstitially migrating cytotrophoblast into the placental bed. Explants of first trimester mesenchymal villi on collagen type I developed cytotrophoblast outgrowths from the villous tips. However, in medium changed daily, cells did not progress to a migratory phenotype, remaining instead as a contiguous multi-layered sheet. This suggested the need for another migration stimulus. To test the possibility that this might arise from mesenchymal cells, serum-free conditioned medium from first trimester placental fibroblasts was added to explant cultures. Cytotrophoblasts were stimulated to migrate in streams across the gel. Affinity depletion of Insulin-like growth factor from fibroblast medium reduced streaming activity, while the addition of exogenous IGF-I (10 ng/ml) to serum-free medium produced a streaming phenotype. IGF receptor type 1 (IGFR1) was present on cells in the columns, and streaming could be inhibited by antibody to this receptor. IGF-II and activin, known stimulators of cytotrophoblast migration, were also active in this model. These data suggest a paracrine interaction between villous mesenchyme and the cytotrophoblast in anchoring sites that stimulates trophoblast infiltration of decidua. Such a signal would be self-limiting since it diminishes with distance from the placenta. This is a novel mechanism in placental development.

Role of the nuclear migration protein Lis1 in cell morphogenesis in Ustilago maydis

PubMed Central

Valinluck, Michael; Ahlgren, Sara; Sawada, Mizuho; Locken, Kristopher; Banuett, Flora

2010-01-01

Ustilago maydis is a basidiomycete fungus that exhibits a yeast-like and a filamentous form. Growth of the fungus in the host leads to additional morphological transitions. The different morphologies are characterized by distinct nuclear movements. Dynein and α-tubulin are required for nuclear movements and for cell morphogenesis of the yeast-like form. Lis1 is a microtubule plus-end tracking protein (+TIPs) conserved in eukaryotes and required for nuclear migration and spindle positioning. Defects in nuclear migration result in altered cell fate and aberrant development in metazoans, slow growth in fungi and disease in humans (e.g. lissencephaly). Here we investigate the role of the human LIS1 homolog in U. maydis and demonstrate that it is essential for cell viability, not previously seen in other fungi. With a conditional null mutation we show that lis1 is necessary for nuclear migration in the yeast-like cell and during the dimorphic transition. Studies of asynchronous exponentially growing cells and time-lapse microscopy uncovered novel functions of lis1: It is necessary for cell morphogenesis, positioning of the septum and cell wall integrity. lis1-depleted cells exhibit altered axes of growth and loss of cell polarity leading to grossly aberrant cells with clusters of nuclei and morphologically altered buds devoid of nuclei. Altered septum positioning and cell wall deposition contribute to the aberrant morphology. lis1-depleted cells lyse, indicative of altered cell wall properties or composition. We also demonstrate, with indirect immunofluorescence to visualize tubulin, that lis1 is necessary for the normal organization of the microtubule cytoskeleton: lis1-depleted cells contain more and longer microtubules that can form coils perpendicular to the long axis of the cell. We propose that lis1 controls microtubule dynamics and thus the regulated delivery of vesicles to growth sites and other cell domains that govern nuclear movements. PMID:20524583

A pilot study to assess adductor canal catheter tip migration in a cadaver model.

PubMed

Leng, Jody C; Harrison, T Kyle; Miller, Brett; Howard, Steven K; Conroy, Myles; Udani, Ankeet; Shum, Cynthia; Mariano, Edward R

2015-04-01

An adductor canal catheter may facilitate early ambulation after total knee arthroplasty, but there is concern over preoperative placement since intraoperative migration of catheters may occur from surgical manipulation and result in ineffective analgesia. We hypothesized that catheter type and subcutaneous tunneling may influence tip migration for preoperatively inserted adductor canal catheters. In a male unembalmed human cadaver, 20 catheter insertion trials were divided randomly into one of four groups: flexible epidural catheter either tunneled or not tunneled; or rigid stimulating catheter either tunneled or not tunneled. Intraoperative patient manipulation was simulated by five range-of-motion exercises of the knee. Distance and length measurements were performed by a blinded regional anesthesiologist. Changes in catheter tip to nerve distance (p = 0.225) and length of catheter within the adductor canal (p = 0.467) were not different between the four groups. Two of five non-tunneled stimulating catheters (40 %) were dislodged compared to 0/5 in all other groups (p = 0.187). A cadaver model may be useful for assessing migration of regional anesthesia catheters; catheter type and subcutaneous tunneling may not affect migration of adductor canal catheters based on this preliminary study. However, future studies involving a larger sample size, actual patients, and other catheter types are warranted.

The long non-coding RNA HOTTIP enhances pancreatic cancer cell proliferation, survival and migration.

PubMed

Cheng, Yating; Jutooru, Indira; Chadalapaka, Gayathri; Corton, J Christopher; Safe, Stephen

2015-05-10

HOTTIP is a long non-coding RNA (lncRNA) transcribed from the 5' tip of the HOXA locus and is associated with the polycomb repressor complex 2 (PRC2) and WD repeat containing protein 5 (WDR5)/mixed lineage leukemia 1 (MLL1) chromatin modifying complexes. HOTTIP is expressed in pancreatic cancer cell lines and knockdown of HOTTIP by RNA interference (siHOTTIP) in Panc1 pancreatic cancer cells decreased proliferation, induced apoptosis and decreased migration. In Panc1 cells transfected with siHOTTIP, there was a decrease in expression of 757 genes and increased expression of 514 genes, and a limited gene analysis indicated that HOTTIP regulation of genes is complex. For example, Aurora kinase A, an important regulator of cell growth, is coregulated by MLL and not WDR5 and, in contrast to previous studies in liver cancer cells, HOTTIP does not regulate HOXA13 but plays a role in regulation of several other HOX genes including HOXA10, HOXB2, HOXA11, HOXA9 and HOXA1. Although HOTTIP and the HOX-associated lncRNA HOTAIR have similar pro-oncogenic functions, they regulate strikingly different sets of genes in Panc1 cells and in pancreatic tumors.

A translating stage system for µ-PIV measurements surrounding the tip of a migrating semi-infinite bubble.

PubMed

Smith, B J; Yamaguchi, E; Gaver, D P

2010-01-01

We have designed, fabricated and evaluated a novel translating stage system (TSS) that augments a conventional micro particle image velocimetry (µ-PIV) system. The TSS has been used to enhance the ability to measure flow fields surrounding the tip of a migrating semi-infinite bubble in a glass capillary tube under both steady and pulsatile reopening conditions. With conventional µ-PIV systems, observations near the bubble tip are challenging because the forward progress of the bubble rapidly sweeps the air-liquid interface across the microscopic field of view. The translating stage mechanically cancels the mean bubble tip velocity, keeping the interface within the microscope field of view and providing a tenfold increase in data collection efficiency compared to fixed-stage techniques. This dramatic improvement allows nearly continuous observation of the flow field over long propagation distances. A large (136-frame) ensemble-averaged velocity field recorded with the TSS near the tip of a steadily migrating bubble is shown to compare well with fixed-stage results under identical flow conditions. Use of the TSS allows the ensemble-averaged measurement of pulsatile bubble propagation flow fields, which would be practically impossible using conventional fixed-stage techniques. We demonstrate our ability to analyze these time-dependent two-phase flows using the ensemble-averaged flow field at four points in the oscillatory cycle.

Teamcenter community : administration tips and tricks

NASA Technical Reports Server (NTRS)

Rangel, Gabriel

2005-01-01

This presentation covers what areas of prerequisites are important to understand and how one can improve performance and maintenance of an existing implementation. It will also cover tips and tricks for site migration and how to plan for upgrades.

Effectiveness of breast fixation to reduce migration of the tip of a totally implantable venous access port in women.

PubMed

Song, Myung Gyu; Seo, Tae-Seok; Kim, Yun Hwan; Cho, Sung Bum; Jung, Euichul; Chung, Hwan Hoon; Lee, Seung Hwa

2016-07-12

To evaluate effectiveness of breast fixation to reduce migration of the catheter tip of a totally implantable venous access port (TIVP) in women. TIVPs were placed in 129 women via the right axillary vein from July 2012 to December 2014, with a final study population of 118 patients (mean age, 55.3 ± 13.8 years; range, 21-91 years). The patients were divided into two groups according to breast fixation during TIVP placement. A total of 56 patients received TIVP placement without breast fixation (Group 1); the remaining 62 received TIVP placement in the supine position after fixation of the ipsilateral breast on the abdominal wall in the sitting position (Group 2). Medical records were retrospectively reviewed for age, weight, height, body mass index, and underlying malignancy. We evaluated the difference in distance ratios between the port chamber and the catheter tip on supine chest and erect chest radiographs, respectively. Statistical analysis was performed using Student's t test. Differences in all parameters between Group 1 and Group 2 were not statistically significant. Mean distance ratio between the port chamber and the catheter tip was 1.95 ± 0.97 in Group 1 and 1.33 ± 0.59 in Group 2. Differences in distance ratios between the port chamber and the catheter tip were statistically significant between Group 1 and Group 2 (p = 0.001). Breast fixation seems to be effective in reducing migration of the port chamber and catheter tip with position changes in female patients during TIVP placement.

The directed migration of gonadal distal tip cells in Caenorhabditis elegans requires NGAT-1, a ß1,4-N-acetylgalactosaminyltransferase enzyme

PubMed Central

Veyhl, Joseph; Dunn, Robert J.; Johnston, Wendy L.; Bennett, Alexa; Zhang, Lijia W.; Dennis, James W.; Schachter, Harry

2017-01-01

Glycoproteins such as growth factor receptors and extracellular matrix have well-known functions in development and cancer progression, however, the glycans at sites of modification are often heterogeneous molecular populations which makes their functional characterization challenging. Here we provide evidence for a specific, discrete, well-defined glycan modification and regulation of a stage-specific cell migration in Caenorhabditis elegans. We show that a chain-terminating, putative null mutation in the gene encoding a predicted β1,4-N-acetylgalactosaminyltransferase, named ngat-1, causes a maternally rescued temperature sensitive (ts) defect in the second phase of the three phase migration pattern of the posterior, but not the anterior, hermaphrodite Distal Tip Cell (DTC). An amino-terminal partial deletion of ngat-1 causes a similar but lower penetrance ts phenotype. The existence of multiple ts alleles with distinctly different molecular DNA lesions, neither of which is likely to encode a ts protein, indicates that NGAT-1 normally prevents innate temperature sensitivity for phase 2 DTC pathfinding. Temperature shift analyses indicate that the ts period for the ngat-1 mutant defect ends by the beginning of post-embryonic development–nearly 3 full larval stages prior to the defective phase 2 migration affected by ngat-1 mutations. NGAT-1 homologs generate glycan-terminal GalNAc-β1-4GlcNAc, referred to as LacdiNAc modifications, on glycoproteins and glycolipids. We also found that the absence of the GnT1/Mgat1 activity [UDP-N-acetyl-D-glucosamine:α-3-D-mannoside β-1,2-N-acetylglucosaminyltransferase 1 (encoded by C. elegans gly-12, gly-13, and gly-14 and homologous to vertebrate GnT1/Mgat1)], causes a similar spectrum of DTC phenotypes as ngat-1 mutations–primarily affecting posterior DTC phase 2 migration and preventing manifestation of the same innate ts period as ngat-1. GnT1/Mgat1 is a medial Golgi enzyme known to modify mannose residues and initiate N-glycan branching, an essential step in the biosynthesis of hybrid, paucimannose and complex-type N-glycans. Quadruple mutant animals bearing putative null mutations in ngat-1 and the three GnT genes (gly-12, gly-13, gly-14) were not enhanced for DTC migration defects, suggesting NGAT-1 and GnT1 act in the same pathway. These findings suggest that GnTI generates an N-glycan substrate for NGAT-1 modification, which is required at restrictive temperature (25°C) to prevent, stabilize, reverse or compensate a perinatal thermo-labile process (or structure) causing late larval stage DTC phase 2 migration errors. PMID:28817611

Similarity is not enough: Tipping points of Ebola Zaire mortalities

NASA Astrophysics Data System (ADS)

Phillips, J. C.

2015-06-01

In early 2014 an outbreak of a slightly mutated Zaire Ebola subtype appeared in West Africa which is less virulent than 1976 and 1994 strains. The numbers of cases per year appear to be ∼1000 times larger than the earlier strains, suggesting a greatly enhanced transmissibility. Although the fraction of the 2014 spike glycoprotein mutations is very small (∼3%), the mortality is significantly reduced, while the transmission appears to have increased strongly. Bioinformatic scaling had previously shown similar inversely correlated trends in virulence and transmission in N1 (H1N1) and N2 (H3N2) influenza spike glycoprotein mutations. These trends appear to be related to various external factors (migration, availability of pure water, and vaccination programs). The molecular mechanisms for Ebola's mutational response involve mainly changes in the disordered mucin-like domain (MLD) of its spike glycoprotein amino acids. The MLD has been observed to form the tip of an oligomeric amphiphilic wedge that selectively pries apart cell-cell interfaces via an oxidative mechanism.

Paxillin associates with poly(A)-binding protein 1 at the dense endoplasmic reticulum and the leading edge of migrating cells.

PubMed

Woods, Alison J; Roberts, Marnie S; Choudhary, Jyoti; Barry, Simon T; Mazaki, Yuichi; Sabe, Hisataka; Morley, Simon J; Critchley, David R; Norman, Jim C

2002-02-22

Using mass spectrometry we have identified proteins which co-immunoprecipitate with paxillin, an adaptor protein implicated in the integrin-mediated signaling pathways of cell motility. A major component of paxillin immunoprecipitates was poly(A)-binding protein 1, a 70-kDa mRNA-binding protein. Poly(A)-binding protein 1 associated with both the alpha and beta isoforms of paxillin, and this was unaffected by RNase treatment consistent with a protein-protein interaction. The NH(2)-terminal region of paxillin (residues 54-313) associated directly with poly(A)-binding protein 1 in cell lysates, and with His-poly(A)-binding protein 1 immobilized in microtiter wells. Binding was specific, saturable and of high affinity (K(d) of approximately 10 nm). Cell fractionation studies showed that at steady state, the bulk of paxillin and poly(A)-binding protein 1 was present in the "dense" polyribosome-associated endoplasmic reticulum. However, inhibition of nuclear export with leptomycin B caused paxillin and poly(A)-binding protein 1 to accumulate in the nucleus, indicating that they shuttle between the nuclear and cytoplasmic compartments. When cells migrate, poly(A)-binding protein 1 colocalized with paxillin-beta at the tips of lamellipodia. Our results suggest a new mechanism whereby a paxillin x poly(A)-binding protein 1 complex facilitates transport of mRNA from the nucleus to sites of protein synthesis at the endoplasmic reticulum and the leading lamella during cell migration.

Tensile stress stimulates microtubule outgrowth in living cells

NASA Technical Reports Server (NTRS)

Kaverina, Irina; Krylyshkina, Olga; Beningo, Karen; Anderson, Kurt; Wang, Yu-Li; Small, J. Victor

2002-01-01

Cell motility is driven by the sum of asymmetric traction forces exerted on the substrate through adhesion foci that interface with the actin cytoskeleton. Establishment of this asymmetry involves microtubules, which exert a destabilising effect on adhesion foci via targeting events. Here, we demonstrate the existence of a mechano-sensing mechanism that signals microtubule polymerisation and guidance of the microtubules towards adhesion sites under increased stress. Stress was applied either by manipulating the body of cells moving on glass with a microneedle or by stretching a flexible substrate that cells were migrating on. We propose a model for this mechano-sensing phenomenon whereby microtubule polymerisation is stimulated and guided through the interaction of a microtubule tip complex with actin filaments under tension.

The migration and growth of nuclei in an ideal vortex flow

NASA Astrophysics Data System (ADS)

Zhang, Lingxin; Chen, Linya; Shao, Xueming

2016-12-01

Tip vortex cavitation occurs on ship propellers which can cause significant noise compared to the wet flow. In order to predict the inception of tip vortex cavitation, numerous researches have been investigated about the detailed flow field around the tip. According to informed studies, the inception of tip vortex cavitation is affected by many factors. To understand the effect of water quality on cavitation inception, the motion of nuclei in an ideal vortex flow, i.e., the Rankine vortex flow, was investigated. The one-way coupling point-particle tracking model was employed to simulate the trajectory of nuclei. Meanwhile, Rayleigh-Plesset equation was introduced to describe the growth of nuclei. The results show that the nucleus size has a significant effect on nucleus' trajectory. The capture time of a nucleus is approximately inversely proportional to its radius. The growth of nucleus accelerates its migration in the vortex flow and shortens its capture time, especially for the case of explosive growth.

Characterization of Intracellular Streaming and Traction Forces in Migrating Physarum Plasmodia

NASA Astrophysics Data System (ADS)

Zhang, Shun; Del Alamo, Juan C.; Guy, Robert D.; Lasheras, Juan C.

2012-11-01

Physarum plasmodium is a model organism for cell migration that exhibits fast intracellular streaming. Motile amoeboid physarum plasmodia were obtained from dish cultures of Physarum Polycephalum, a slime mold that inhabits shady cool moist areas in the wild, such as decaying vegetable material. The migrating amoebae were obtained by cutting successively smaller pieces from the growing tips of the cultured parent mold, and their size ranged 0.2 to 0.5 mm. Single amoebae were seeded and let adhere on flexible polyacrilamide gels that were functionalized with collagen, contained 0.2-micron fluorescent beads, and were embedded in an aqueous medium. Soon after adhering to the gel, the amoeabe began crawling at about 1mm/hr. Joint time-lapse sequences of intracellular streaming and gel deformation were acquired respectively in the bright and fluorescent fields of a confocal microscope at 20X magnification. These images were analyzed using particle-tracking algorithms, and the traction stresses applied by the amoebae on the surface were computed by solving the elastostatic equation for the gel using the measured bead displacements as boundary conditions. These measurements provide, for the first time, a joint characterization of intracellular mass transport and the forces driving this transport in motile amoeboid cells.

The long non-coding RNA HOTTIP enhances pancreatic cancer cell proliferation, survival and migration

PubMed Central

Cheng, Yating; Jutooru, Indira; Chadalapaka, Gayathri; Corton, J. Christopher; Safe, Stephen

2015-01-01

HOTTIP is a long non-coding RNA (lncRNA) transcribed from the 5′ tip of the HOXA locus and is associated with the polycomb repressor complex 2 (PRC2) and WD repeat containing protein 5 (WDR5)/mixed lineage leukemia 1 (MLL1) chromatin modifying complexes. HOTTIP is expressed in pancreatic cancer cell lines and knockdown of HOTTIP by RNA interference (siHOTTIP) in Panc1 pancreatic cancer cells decreased proliferation, induced apoptosis and decreased migration. In Panc1 cells transfected with siHOTTIP, there was a decrease in expression of 757 genes and increased expression of 514 genes, and a limited gene analysis indicated that HOTTIP regulation of genes is complex. For example, Aurora kinase A, an important regulator of cell growth, is coregulated by MLL and not WDR5 and, in contrast to previous studies in liver cancer cells, HOTTIP does not regulate HOXA13 but plays a role in regulation of several other HOX genes including HOXA10, HOXB2, HOXA11, HOXA9 and HOXA1. Although HOTTIP and the HOX-associated lncRNA HOTAIR have similar pro-oncogenic functions, they regulate strikingly different sets of genes in Panc1 cells and in pancreatic tumors. PMID:25912306

Genetic damage induced by a food coloring dye (sunset yellow) on meristematic cells of Brassica campestris L.

PubMed

Dwivedi, Kshama; Kumar, Girjesh

2015-01-01

We have performed the present piece of work to evaluate the effect of synthetic food coloring azo dye (sunset yellow) on actively dividing root tip cells of Brassica campestris L. Three doses of azo dye were administered for the treatment of actively dividing root tip cells, namely, 1%, 3%, and 5%, for 6-hour duration along with control. Mitotic analysis clearly revealed the azo dye induced endpoint deviation like reduction in the frequency of normal divisions in a dose dependent manner. Mitotic divisions in the control sets were found to be perfectly normal while dose based reduction in MI was registered in the treated sets. Azo dye has induced several chromosomal aberrations (genotoxic effect) at various stages of cell cycle such as stickiness of chromosomes, micronuclei formation, precocious migration of chromosome, unorientation, forward movement of chromosome, laggards, and chromatin bridge. Among all, stickiness of chromosomes was present in the highest frequency followed by partial genome elimination as micronuclei. The present study suggests that extensive use of synthetic dye should be forbidden due to genotoxic and cytotoxic impacts on living cells. Thus, there is an urgent need to assess potential hazardous effects of these dyes on other test systems like human and nonhuman biota for better scrutiny.

Genetic Damage Induced by a Food Coloring Dye (Sunset Yellow) on Meristematic Cells of Brassica campestris L.

PubMed Central

Dwivedi, Kshama; Kumar, Girjesh

2015-01-01

We have performed the present piece of work to evaluate the effect of synthetic food coloring azo dye (sunset yellow) on actively dividing root tip cells of Brassica campestris L. Three doses of azo dye were administered for the treatment of actively dividing root tip cells, namely, 1%, 3%, and 5%, for 6-hour duration along with control. Mitotic analysis clearly revealed the azo dye induced endpoint deviation like reduction in the frequency of normal divisions in a dose dependent manner. Mitotic divisions in the control sets were found to be perfectly normal while dose based reduction in MI was registered in the treated sets. Azo dye has induced several chromosomal aberrations (genotoxic effect) at various stages of cell cycle such as stickiness of chromosomes, micronuclei formation, precocious migration of chromosome, unorientation, forward movement of chromosome, laggards, and chromatin bridge. Among all, stickiness of chromosomes was present in the highest frequency followed by partial genome elimination as micronuclei. The present study suggests that extensive use of synthetic dye should be forbidden due to genotoxic and cytotoxic impacts on living cells. Thus, there is an urgent need to assess potential hazardous effects of these dyes on other test systems like human and nonhuman biota for better scrutiny. PMID:25954313

Wnt4 coordinates directional cell migration and extension of the Müllerian duct essential for ontogenesis of the female reproductive tract

PubMed Central

Prunskaite-Hyyryläinen, Renata; Skovorodkin, Ilya; Xu, Qi; Miinalainen, Ilkka; Shan, Jingdong; Vainio, Seppo J.

2016-01-01

The Müllerian duct (MD) is the anlage of the oviduct, uterus and upper part of the vagina, the main parts of the female reproductive tract. Several wingless-type mouse mammary tumor virus (MMTV) integration site family member (Wnt) genes, including Wnt4, Wnt5a and Wnt7a, are involved in the development of MD and its derivatives, with Wnt4 particularly critical, since the MD fails to develop in its absence. We use, here, Wnt4EGFPCre-based fate mapping to demonstrate that the MD tip cells and the subsequent MD cells are derived from Wnt4+ lineage cells. Moreover, Wnt4 is required for the initiation of MD-forming cell migration. Application of anti-Wnt4 function-blocking antibodies after the initiation of MD elongation indicated that Wnt4 is necessary for the elongation as well, and consistent with this, cell culture wound-healing assays with NIH3T3 cells overexpressing Wnt4 promoted cell migration by comparison with controls. In contrast to the Wnt4 null embryos, some Wnt4monomeric cherry/monomeric cherry (Wnt4mCh/mCh) hypomorphic mice survived to adulthood and formed MD in ∼45% of cases. Nevertheless, the MD of the Wnt4mCh/mCh females had altered cell polarization and basement membrane deposition relative to the controls. Examination of the reproductive tract of the Wnt4mCh/mCh females indicated a poorly coiled oviduct, absence of the endometrial glands and an undifferentiated myometrium, and these mice were prone to develop a hydro-uterus. In conclusion, the results suggest that the Wnt4 gene encodes signals that are important for various aspects of female reproductive tract development. PMID:26721931

TIPS stent migration into the heart with 6-year follow-up.

PubMed

Fehervari, Imre; Szonyi, Laszlo; Fazakas, Janos; Gerlei, Zsuzsa; Lazar, Istvan

2011-01-01

The transjugular intrahepatic portosystemic shunt (TIPS) is widely used for the treatment of portal hypertension in adults, but no studies have defined the best approach to treat portal hypertension in pediatric patients. Pediatric use of TIPS is rare even in large centers of adult practice. The migration of stents has also been reported as a complication in adults. There is no standard way to treat this type of complication, and it is not always clear whether immediate removal or watchful waiting is safer for the patient. We report the case of an 11-year-old patient who underwent urgent TIPS implantation due to variceal bleeding, after unsuccessful sclerotherapy. During the procedure, due to the deep impact of the stent, a second, telescopic, stent was inserted. The portal pressure decreased, no further bleeding occurred, and the patient was listed for transplantation. Three weeks later a routine chest X-ray discovered the migration of the second stent into the right ventricle. No interventional radiological removal or open heart surgery was available for the transplant waiting list patient. The patient underwent uneventful combined liver-kidney transplantation. During the 6-year follow-up period the child had no signs of hemodynamic instability, and his somatic and mental development were appropriate. To our knowledge this case is the first publication on a heart-impacted TIPS stent in a child. The watchful waiting was justified by uneventful combined liver-kidney transplantation and long-term follow-up. This case also underlines the need for best practice guidelines in pediatric portal hypertension.

Defective eyelid leading edge cell migration in C57BL/6-corneal opacity mice with an "eye open at birth" phenotype.

PubMed

Wu, L C; Liu, C; Jiang, M R; Jiang, Y M; Wang, Q H; Lu, Z Y; Wang, S J; Yang, W L; Shao, Y X

2016-08-26

Development of the eyelid requires coordination of the cellular processes involved in proliferation, cell size alteration, migration, and cell death. C57BL/6J-corneal opacity (B6-Co) mice are mutant mice generated by the administration of N-ethyl-N-nitrosourea (100 mg/kg). They exhibit the eyelids open at birth phenotype, abnormal round cell shape from tightened F-actin bundles in leading edge keratinocytes at E16.5, and gradual corneal opacity with neovessels. The tip of the leading edge in B6-Co mice did not move forward, and demonstrated a sharp peak shape without obvious directionality. Analysis of the biological characteristics of B6-Co mice demonstrated that abnormal migration of keratinocytes could affect eyelid development, but proliferation and apoptosis in B6-Co mice had no effect. Mutant gene mapping and sequence analysis demonstrated that in B6-Co mice, adenosine was inserted into the untranslated regions, between 3030 and 3031, in the mRNA 3'-terminal of Fgf10. In addition, guanine 7112 was substituted by adenine in the Mtap1B mRNA, and an A2333T mutation was identified in Mtap1B. Quantitative real-time polymerase chain reaction analysis showed that expression of the Hbegf gene was significantly down-regulated in the eyelids of B6- Co mice at E16.5, compared to B6 mice. However, the expression of Rock1, Map3k1, and Jnk1 genes did not show any significant changes. Abnormal keratinocyte migration and down-regulated expression of the Hbegf gene might be associated with impaired eyelid development in B6-Co mice.

Inducible nuclear translocation of a STAT protein in Dictyostelium prespore cells: implications for morphogenesis and cell-type regulation.

PubMed

Dormann, D; Abe, T; Weijer, C J; Williams, J

2001-04-01

Dd-STATa, the Dictyostelium STAT (signal transducer and activator of transcription) protein, is selectively localised in the nuclei of a small subset of prestalk cells located in the slug tip. Injection of cAMP into the extracellular spaces in the rear of the slug induces rapid nuclear translocation of a Dd-GFP:STATa fusion protein in prespore cells surrounding the site of injection. This suggests that cAMP signals that emanate from the tip direct the localised nuclear accumulation of Dd-STATa. It also shows that prespore cells are competent to respond to cAMP, by Dd-STATa activation, and it implies that cAMP signalling is in some way limiting in the rear of the slug. Co-injection of a specific inhibitor of the cAR1 serpentine cAMP receptor almost completely prevents the cAMP-induced nuclear translocation, showing that most or all of the cAMP signal is transduced by cAR1. Dd-GFP:STATa also rapidly translocates into the nuclei of cells adjoining the front and back cut edges when a slug is bisected. Less severe mechanical disturbances, such as pricking the rear of a slug with an unfilled micropipette, also cause a more limited nuclear translocation of Dd-GFP:STATa. We propose that these signalling events form part of a repair mechanism that is activated when the migrating slug suffers mechanical damage.

Ten tips for successful electronic health records deployment.

PubMed

Gasch, Art

2012-01-01

As healthcare providers are increasingly compelled to adopt electronic health records (EHRs) and paper records migrate to electronic files provided to dozens of healthcare intermediaries, breeches of protected health information are skyrocketing, and so are dissatisfaction rates with EHR solutions. This article provides 10 practical tips to ensure a successful EHR system deployment an circumvent EHR land mines.

Identification and functional analysis of endothelial tip cell-enriched genes.

PubMed

del Toro, Raquel; Prahst, Claudia; Mathivet, Thomas; Siegfried, Geraldine; Kaminker, Joshua S; Larrivee, Bruno; Breant, Christiane; Duarte, Antonio; Takakura, Nobuyuki; Fukamizu, Akiyoshi; Penninger, Josef; Eichmann, Anne

2010-11-11

Sprouting of developing blood vessels is mediated by specialized motile endothelial cells localized at the tips of growing capillaries. Following behind the tip cells, endothelial stalk cells form the capillary lumen and proliferate. Expression of the Notch ligand Delta-like-4 (Dll4) in tip cells suppresses tip cell fate in neighboring stalk cells via Notch signaling. In DLL4(+/-) mouse mutants, most retinal endothelial cells display morphologic features of tip cells. We hypothesized that these mouse mutants could be used to isolate tip cells and so to determine their genetic repertoire. Using transcriptome analysis of retinal endothelial cells isolated from DLL4(+/-) and wild-type mice, we identified 3 clusters of tip cell-enriched genes, encoding extracellular matrix degrading enzymes, basement membrane components, and secreted molecules. Secreted molecules endothelial-specific molecule 1, angiopoietin 2, and apelin bind to cognate receptors on endothelial stalk cells. Knockout mice and zebrafish morpholino knockdown of apelin showed delayed angiogenesis and reduced proliferation of stalk cells expressing the apelin receptor APJ. Thus, tip cells may regulate angiogenesis via matrix remodeling, production of basement membrane, and release of secreted molecules, some of which regulate stalk cell behavior.

Differing strategies of patterning of follicular cells in higher and lower brachycerans (Diptera: Brachycera).

PubMed

Tworzydlo, Waclaw; Jablonska, Anna; Kisiel, Elzbieta; Bilinski, Szczepan M

2005-10-01

In all higher dipterans (Brachycera), including the fruitfly, Drosophila melanogaster, each egg chamber (ovarian follicle) consists of a group (clone) of germ cells (one oocyte and 15 accompanying nurse cells) that is surrounded by a layer of somatic mesodermal follicular cells (FCs). As oogenesis progresses the initially uniform FCs diversify into several morphologically and functionally distinct subpopulations. In D. melanogaster some of these subpopulations, e.g., border, centripetal, and dorsolateral cells, undertake coordinated migration or rearrangement over the surface of the germ cells. During the final stages of oogenesis these subpopulations participate in the formation of a complex, regionally specialized eggshell. In representatives of lower brachycerans (Orthorrhapha), only FCs that undertake active, directed migration are the border cells. These cells originate at the anterior pole of the ovarian follicle and migrate between the nurse cells to the anterior pole of the oocyte. Reduced motility of FCs in lower brachycerans results in the absence of certain FC subpopulations in their egg chambers and subsequent simplicity of their eggshells. We found that the lack of some FC subpopulations coincided with the appearance of lamellipodium-like protrusions of the oocyte. These protrusions penetrated between the apposing membranes of nurse and FCs and partially enveloped the nurse cell compartment. Analysis of whole-mount preparations stained with rhodamine-conjugated phalloidin revealed that the protrusions contained microfilaments and that their tips were equipped with actin-rich filopodium-like processes. We also found that in some lower brachycerans (representatives of the family Rhagionidae), the FCs located at the posterior pole of the oocyte, became enlarged and morphologically similar to the anterior border cells. These findings indicate that in higher dipterans the processes leading to the formation of a functional egg are variable and often markedly different from those in the model organism, D. melanogaster. genesis 43:49-58, 2005. (c) 2005 Wiley-Liss, Inc.

Automated tracking and quantification of angiogenic vessel formation in 3D microfluidic devices.

PubMed

Wang, Mengmeng; Ong, Lee-Ling Sharon; Dauwels, Justin; Asada, H Harry

2017-01-01

Angiogenesis, the growth of new blood vessels from pre-existing vessels, is a critical step in cancer invasion. Better understanding of the angiogenic mechanisms is required to develop effective antiangiogenic therapies for cancer treatment. We culture angiogenic vessels in 3D microfluidic devices under different Sphingosin-1-phosphate (S1P) conditions and develop an automated vessel formation tracking system (AVFTS) to track the angiogenic vessel formation and extract quantitative vessel information from the experimental time-lapse phase contrast images. The proposed AVFTS first preprocesses the experimental images, then applies a distance transform and an augmented fast marching method in skeletonization, and finally implements the Hungarian method in branch tracking. When applying the AVFTS to our experimental data, we achieve 97.3% precision and 93.9% recall by comparing with the ground truth obtained from manual tracking by visual inspection. This system enables biologists to quantitatively compare the influence of different growth factors. Specifically, we conclude that the positive S1P gradient increases cell migration and vessel elongation, leading to a higher probability for branching to occur. The AVFTS is also applicable to distinguish tip and stalk cells by considering the relative cell locations in a branch. Moreover, we generate a novel type of cell lineage plot, which not only provides cell migration and proliferation histories but also demonstrates cell phenotypic changes and branch information.

Mechanical Removal of Migrated Onyx Due to Microcatheter Rupture During AVM Embolization: A Technical Case Report.

PubMed

Senturk, Cagin

2015-12-01

We report a case where migrated Onyx could be removed safely with a mechanical thrombectomy device after withdrawal of the damaged microcatheter. A microcatheter was retained in the superior cerebellar artery with attached Onyx fragments on its tip during embolization of a bled cerebellar AVM. During retrieval maneuvers microcatheter shaft was ruptured and Onyx fragments were released into the vertebrobasilar system causing occlusion. Finally, Onyx fragment on tip of the microcatheter could be detached with dimethyl sulfoxide injection and the microcatheter could be withdrawn. A Merci retriever device (Concentric Medical, Mountain View, CA, USA) was successfully used to retrieve most of the dislodged Onyx material and recanalize the vertebrobasilar circulation.

Humidifier disinfectants, unfinished stories

PubMed Central

Choi, Yeyong

2016-01-01

Once released into the air, humidifier disinfectants became tiny nano-size particles, and resulted in chemical bronchoalveolitis. Families had lost their most beloved members, and even some of them became broken. Based on an estimate of two million potential victims who had experienced adverse effects from the use of humidifier disinfectants, we can say that what we have observed was only the tip of the iceberg. Problems of entire airways, as well as other systemic effects, should be examined, as we know these nano-size particles can irritate cell membranes and migrate into systemic circulation. The story of humidifier disinfectant is not finished yet. PMID:26987713

μ-PIV measurements of the ensemble flow fields surrounding a migrating semi-infinite bubble.

PubMed

Yamaguchi, Eiichiro; Smith, Bradford J; Gaver, Donald P

2009-08-01

Microscale particle image velocimetry (μ-PIV) measurements of ensemble flow fields surrounding a steadily-migrating semi-infinite bubble through the novel adaptation of a computer controlled linear motor flow control system. The system was programmed to generate a square wave velocity input in order to produce accurate constant bubble propagation repeatedly and effectively through a fused glass capillary tube. We present a novel technique for re-positioning of the coordinate axis to the bubble tip frame of reference in each instantaneous field through the analysis of the sudden change of standard deviation of centerline velocity profiles across the bubble interface. Ensemble averages were then computed in this bubble tip frame of reference. Combined fluid systems of water/air, glycerol/air, and glycerol/Si-oil were used to investigate flows comparable to computational simulations described in Smith and Gaver (2008) and to past experimental observations of interfacial shape. Fluorescent particle images were also analyzed to measure the residual film thickness trailing behind the bubble. The flow fields and film thickness agree very well with the computational simulations as well as existing experimental and analytical results. Particle accumulation and migration associated with the flow patterns near the bubble tip after long experimental durations are discussed as potential sources of error in the experimental method.

Eleven quick tips for architecting biomedical informatics workflows with cloud computing.

PubMed

Cole, Brian S; Moore, Jason H

2018-03-01

Cloud computing has revolutionized the development and operations of hardware and software across diverse technological arenas, yet academic biomedical research has lagged behind despite the numerous and weighty advantages that cloud computing offers. Biomedical researchers who embrace cloud computing can reap rewards in cost reduction, decreased development and maintenance workload, increased reproducibility, ease of sharing data and software, enhanced security, horizontal and vertical scalability, high availability, a thriving technology partner ecosystem, and much more. Despite these advantages that cloud-based workflows offer, the majority of scientific software developed in academia does not utilize cloud computing and must be migrated to the cloud by the user. In this article, we present 11 quick tips for architecting biomedical informatics workflows on compute clouds, distilling knowledge gained from experience developing, operating, maintaining, and distributing software and virtualized appliances on the world's largest cloud. Researchers who follow these tips stand to benefit immediately by migrating their workflows to cloud computing and embracing the paradigm of abstraction.

Eleven quick tips for architecting biomedical informatics workflows with cloud computing

PubMed Central

Moore, Jason H.

2018-01-01

Cloud computing has revolutionized the development and operations of hardware and software across diverse technological arenas, yet academic biomedical research has lagged behind despite the numerous and weighty advantages that cloud computing offers. Biomedical researchers who embrace cloud computing can reap rewards in cost reduction, decreased development and maintenance workload, increased reproducibility, ease of sharing data and software, enhanced security, horizontal and vertical scalability, high availability, a thriving technology partner ecosystem, and much more. Despite these advantages that cloud-based workflows offer, the majority of scientific software developed in academia does not utilize cloud computing and must be migrated to the cloud by the user. In this article, we present 11 quick tips for architecting biomedical informatics workflows on compute clouds, distilling knowledge gained from experience developing, operating, maintaining, and distributing software and virtualized appliances on the world’s largest cloud. Researchers who follow these tips stand to benefit immediately by migrating their workflows to cloud computing and embracing the paradigm of abstraction. PMID:29596416

Emergent behavior of cells on microfabricated soft polymeric substrates

NASA Astrophysics Data System (ADS)

Anand, Sandeep Venkit

In recent years, cell based bio-actuators like cardiomyocytes and skeletal muscle cells have emerged as popular choices for powering biological machines consisting of soft polymeric scaffolds at the micro and macro scales. This is owing to their unique ability to generate spontaneous, synchronous contractions either autonomously or under externally applied fields. Most of the biological machine designs reported in literature use single cells or cell clusters conjugated with biocompatible soft polymers like polydimethylsiloxane (PDMS) and hydrogels to produce some form of locomotion by converting chemical energy of the cells to mechanical energy. The mode of locomotion may vary, but the fundamental mechanism that these biological machines exploit to achieve locomotion stems from cell substrate interactions leading to large deformations of the substrates (relative to the cell size). However, the effect of such large scale, dynamic deformation of the substrates on the cellular and cluster level organization of the cells remains elusive. This dissertation tries to explore the emergent behavior of cells on different types of micro-scale deformable, soft polymeric substrates. In the first part of the dissertation, contractile dynamics of primary cardiomyocyte clusters is studied by culturing them on deformable thin polymeric films. The cell clusters beat and generate sufficient forces to deform the substrates out of plane. Over time, the clusters reorient their force dipoles along the direction of maximum compliance. This suggests that the cells are capable of sensing substrate deformations through a mechanosensitive feedback mechanism and dynamically reorganizing themselves. Results are further validated through finite element analysis. The development, characterization and quantification of a novel 1D/2D like polymeric platform for cell culture is presented in the second part. The platform consists of a 2D surface anchoring a long (few millimeters) narrow filament (1D) with a single cell scale (micro scale) cross section. We plate C2C12 cells on the platform and characterize their migration, proliferation, and differentiation patterns in contrast to 2D culture. We find that the cells land on the 2D surface, and then migrate to the filament only when the 2D surface has become nearly confluent. Individual and isolated cells randomly approaching the filament always retract away towards the 2D surface. Once on the filament, their differentiation to myotubes is expedited compared to that on 2D substrate. The myotubes generate periodic twitching forces that deform the filament producing more than 17 um displacement at the tip. Such flagellar motion can be used to develop autonomous micro scale bio-bots. Finally, the design and fabrication of a polymeric micro-pillar based force sensor capable of measuring cellular focal-adhesion forces under externally applied stretch is discussed. The force sensor consists of arrays of uniformly spaced PDMS micro-pillars of 1-2 um diameter and 2-3 um spacing on a macroscale PDMS substrate. The tips of the micro-pillars are selectively patterned with fluorescently labeled ECM proteins using micro-contact printing to promote cell adhesion while simultaneously acting as markers for strain measurements. Cells adhere and spread on top of the pillars causing them to deform. When stretched, the cells reorganize their internal structure and modulate their traction forces in response to the applied stretch. The dynamically varying cellular forces in response to the stretch are computed by measuring the cell induced displacements estimated by isolating the displacements caused by the applied stretch from the net displacements of the tips.

Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip from Herpesvirus saimiri

PubMed Central

Vernot, Jean-Paul; Perdomo-Arciniegas, Ana María; Pérez-Quintero, Luis Alberto; Martínez, Diego Fernando

2015-01-01

The Lck interacting protein Tip of Herpesvirus saimiri is responsible for T-cell transformation both in vitro and in vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human and Aotus sp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts. PMID:26539553

Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip from Herpesvirus saimiri.

PubMed

Vernot, Jean-Paul; Perdomo-Arciniegas, Ana María; Pérez-Quintero, Luis Alberto; Martínez, Diego Fernando

2015-01-01

The Lck interacting protein Tip of Herpesvirus saimiri is responsible for T-cell transformation both in vitro and in vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human and Aotus sp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts.

IL-5-stimulated eosinophils adherent to periostin undergo stereotypic morphological changes and ADAM8-dependent migration.

PubMed

Johansson, M W; Khanna, M; Bortnov, V; Annis, D S; Nguyen, C L; Mosher, D F

2017-10-01

IL-5 causes suspended eosinophils to polarize with filamentous (F)-actin and granules at one pole and the nucleus in a specialized uropod, the "nucleopod," which is capped with P-selectin glycoprotein ligand-1 (PSGL-1). IL-5 enhances eosinophil adhesion and migration on periostin, an extracellular matrix protein upregulated in asthma by type 2 immunity mediators. Determine how the polarized morphology evolves to foster migration of IL-5-stimulated eosinophils on a surface coated with periostin. Blood eosinophils adhering to adsorbed periostin were imaged at different time points by fluorescent microscopy, and migration of eosinophils on periostin was assayed. After 10 minutes in the presence of IL-5, adherent eosinophils were polarized with PSGL-1 at the nucleopod tip and F-actin distributed diffusely at the opposite end. After 30-60 minutes, the nucleopod had dissipated such that PSGL-1 was localized in a crescent or ring away from the cell periphery, and F-actin was found in podosome-like structures. The periostin layer, detected with monoclonal antibody Stiny-1, shown here to recognize the FAS1 4 module, was cleared in wide areas around adherent eosinophils. Clearance was attenuated by metalloproteinase inhibitors or antibodies to disintegrin metalloproteinase 8 (ADAM8), a major eosinophil metalloproteinase previously implicated in asthma pathogenesis. ADAM8 was not found in podosome-like structures, which are associated with proteolytic activity in other cell types. Instead, immunoblotting demonstrated proteoforms of ADAM8 that lack the cytoplasmic tail in the supernatant. Anti-ADAM8 inhibited migration of IL-5-stimulated eosinophils on periostin. Migrating IL-5-activated eosinophils on periostin exhibit loss of nucleopodal features and appearance of prominent podosomes along with clearance of the Stiny-1 periostin epitope. Migration and epitope clearance are both attenuated by inhibitors of ADAM8. We propose, therefore, that eosinophils remodel and migrate on periostin-rich extracellular matrix in the asthmatic airway in an ADAM8-dependent manner, making ADAM8 a possible therapeutic target. © 2017 John Wiley & Sons Ltd.

Cotton fiber tips have diverse morphologies and show evidence of apical cell wall synthesis

PubMed Central

Stiff , Michael R.; Haigler, Candace H.

2016-01-01

Cotton fibers arise through highly anisotropic expansion of a single seed epidermal cell. We obtained evidence that apical cell wall synthesis occurs through examining the tips of young elongating Gossypium hirsutum (Gh) and G. barbadense (Gb) fibers. We characterized two tip types in Gh fiber (hemisphere and tapered), each with distinct apical diameter, central vacuole location, and distribution of cell wall components. The apex of Gh hemisphere tips was enriched in homogalacturonan epitopes, including a relatively high methyl-esterified form associated with cell wall pliability. Other wall components increased behind the apex including cellulose and the α-Fuc-(1,2)-β-Gal epitope predominantly found in xyloglucan. Gb fibers had only one narrow tip type featuring characters found in each Gh tip type. Pulse-labeling of cell wall glucans indicated wall synthesis at the apex of both Gh tip types and in distal zones. Living Gh hemisphere and Gb tips ruptured preferentially at the apex upon treatment with wall degrading enzymes, consistent with newly synthesized wall at the apex. Gh tapered tips ruptured either at the apex or distantly. Overall, the results reveal diverse cotton fiber tip morphologies and support primary wall synthesis occurring at the apex and discrete distal regions of the tip. PMID:27301434

Long-term C. elegans immobilization enables high resolution developmental studies in vivo.

PubMed

Berger, Simon; Lattmann, Evelyn; Aegerter-Wilmsen, Tinri; Hengartner, Michael; Hajnal, Alex; deMello, Andrew; Casadevall I Solvas, Xavier

2018-05-01

Live-imaging of C. elegans is essential for the study of conserved cellular pathways (e.g. EGFR/Wnt signaling) and morphogenesis in vivo. However, the usefulness of live imaging as a research tool has been severely limited by the need to immobilize worms prior to and during imaging. Conventionally, immobilization is achieved by employing both physical and chemical interventions. These are known to significantly affect many physiological processes, and thus limit our understanding of dynamic developmental processes. Herein we present a novel, easy-to-use microfluidic platform for the long-term immobilization of viable, normally developing C. elegans, compatible with image acquisition at high resolution, thereby overcoming the limitations associated with conventional worm immobilization. The capabilities of the platform are demonstrated through the continuous assessment of anchor cell (AC) invasion and distal tip cell (DTC) migration in larval C. elegans and germ cell apoptosis in adult C. elegans in vivo for the first time.

Endothelial cells dynamically compete for the tip cell position during angiogenic sprouting.

PubMed

Jakobsson, Lars; Franco, Claudio A; Bentley, Katie; Collins, Russell T; Ponsioen, Bas; Aspalter, Irene M; Rosewell, Ian; Busse, Marta; Thurston, Gavin; Medvinsky, Alexander; Schulte-Merker, Stefan; Gerhardt, Holger

2010-10-01

Sprouting angiogenesis requires the coordinated behaviour of endothelial cells, regulated by Notch and vascular endothelial growth factor receptor (VEGFR) signalling. Here, we use computational modelling and genetic mosaic sprouting assays in vitro and in vivo to investigate the regulation and dynamics of endothelial cells during tip cell selection. We find that endothelial cells compete for the tip cell position through relative levels of Vegfr1 and Vegfr2, demonstrating a biological role for differential Vegfr regulation in individual endothelial cells. Differential Vegfr levels affect tip selection only in the presence of a functional Notch system by modulating the expression of the ligand Dll4. Time-lapse microscopy imaging of mosaic sprouts identifies dynamic position shuffling of tip and stalk cells in vitro and in vivo, indicating that the VEGFR-Dll4-Notch signalling circuit is constantly re-evaluated as cells meet new neighbours. The regular exchange of the leading tip cell raises novel implications for the concept of guided angiogenic sprouting.

The effect of the serum corona on interactions between a single nano-object and a living cell

NASA Astrophysics Data System (ADS)

Dror, Yael; Sorkin, Raya; Brand, Guy; Boubriak, Olga; Urban, Jill; Klein, Jacob

2017-04-01

Nanoparticles (NPs) which enter physiological fluids are rapidly coated by proteins, forming a so-called corona which may strongly modify their interaction with tissues and cells relative to the bare NPs. In this work the interactions between a living cell and a nano-object, and in particular the effect on this of the adsorption of serum proteins, are directly examined by measuring the forces arising as an Atomic Force Microscope tip (diameter 20 nm) - simulating a nano-object - approaches and contacts a cell. We find that the presence of a serum protein corona on the tip strongly modifies the interaction as indicated by pronounced increase in the indentation, hysteresis and work of adhesion compared to a bare tip. Classically one expects an AFM tip interacting with a cell surface to be repelled due to cell elastic distortion, offset by tip-cell adhesion, and indeed such a model fits the bare-tip/cell interaction, in agreement with earlier work. However, the force plots obtained with serum-modified tips are very different, indicating that the cell is much more compliant to the approaching tip. The insights obtained in this work may promote better design of NPs for drug delivery and other nano-medical applications.

The effect of the serum corona on interactions between a single nano-object and a living cell

PubMed Central

Dror, Yael; Sorkin, Raya; Brand, Guy; Boubriak, Olga; Urban, Jill; Klein, Jacob

2017-01-01

Nanoparticles (NPs) which enter physiological fluids are rapidly coated by proteins, forming a so-called corona which may strongly modify their interaction with tissues and cells relative to the bare NPs. In this work the interactions between a living cell and a nano-object, and in particular the effect on this of the adsorption of serum proteins, are directly examined by measuring the forces arising as an Atomic Force Microscope tip (diameter 20 nm) - simulating a nano-object - approaches and contacts a cell. We find that the presence of a serum protein corona on the tip strongly modifies the interaction as indicated by pronounced increase in the indentation, hysteresis and work of adhesion compared to a bare tip. Classically one expects an AFM tip interacting with a cell surface to be repelled due to cell elastic distortion, offset by tip-cell adhesion, and indeed such a model fits the bare-tip/cell interaction, in agreement with earlier work. However, the force plots obtained with serum-modified tips are very different, indicating that the cell is much more compliant to the approaching tip. The insights obtained in this work may promote better design of NPs for drug delivery and other nano-medical applications. PMID:28383528

Vegetative and sperm cell-specific aquaporins of Arabidopsis highlight the vacuolar equipment of pollen and contribute to plant reproduction.

PubMed

Wudick, Michael M; Luu, Doan-Trung; Tournaire-Roux, Colette; Sakamoto, Wataru; Maurel, Christophe

2014-04-01

The water and nutrient status of pollen is crucial to plant reproduction. Pollen grains of Arabidopsis (Arabidopsis thaliana) contain a large vegetative cell and two smaller sperm cells. Pollen grains express AtTIP1;3 and AtTIP5;1, two members of the Tonoplast Intrinsic Protein subfamily of aquaporins. To address the spatial and temporal expression pattern of the two homologs, C-terminal fusions of AtTIP1;3 and AtTIP5;1 with green fluorescent protein and mCherry, respectively, were expressed in transgenic Arabidopsis under the control of their native promoter. Confocal laser scanning microscopy revealed that AtTIP1;3 and AtTIP5;1 are specific for the vacuoles of the vegetative and sperm cells, respectively. The tonoplast localization of AtTIP5;1 was established by reference to fluorescent protein markers for the mitochondria and vacuoles of sperm and vegetative cells and is at variance with the claim that AtTIP5;1 is localized in vegetative cell mitochondria. AtTIP1;3-green fluorescent protein and AtTIP5;1-mCherry showed concomitant expression, from first pollen mitosis up to pollen tube penetration in the ovule, thereby revealing the dynamics of vacuole morphology in maturating and germinating pollen. Transfer DNA insertion mutants for either AtTIP1;3 or AtTIP5;1 showed no apparent growth phenotype and had no significant defect in male transmission of the mutated alleles. By contrast, a double knockout displayed an abnormal rate of barren siliques, this phenotype being more pronounced under limited water or nutrient supply. The overall data indicate that vacuoles of vegetative and sperm cells functionally interact and contribute to male fertility in adverse environmental conditions.

21 CFR 870.5150 - Embolectomy catheter.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... (a) Identification. An embolectomy catheter is a balloon-tipped catheter that is used to remove thromboemboli, i.e., blood clots which have migrated in blood vessels from one site in the vascular tree to...

Indecisive Behavior of Amoeba Crossing AN Environmental Barrier

NASA Astrophysics Data System (ADS)

Takagi, S.; Nishiura, Y.; Nakagaki, T.; Ueda, T.; Ueda, K.-I.

2007-07-01

We report here a new kind of behavior that seems to be 'indecisive' in an amoeboid organism, the Physarum plasmodium of true slime mold. The plasmodium migrating in a narrow lane stops moving for a period of time (several hours but the duration differs for each plasmodium) when it encounters the presence of a chemical repellent, quinine. After stopping period, the organism suddenly begins to move again in one of three different ways as the concentration of repellent increases: going through the repulsive place (penetration), splitting into two fronts of going throught it and turning (splitting) and turning back (rebound). In relation to the physiological mechanism for tip migration in the plasmodium, we found that the frontal tip is capable of moving further although the tip is divided from a main body of organism. This means that a motive force of front locomotion is produced by a local process at the tip. Based on this finding, a mathematical model for front locomotion is considered in order to understand the dynamics for both the long period of stopping and three kinds of behavior. A model based on reaction-diffusion equations succeeds to reproduce the experimental observation. The origin of long-time stopping and three different outputs may be reduced to the hidden instabilities of internal dynamics of the pulse, which may be a skeleton structure extracted from much more complex dynamics imbedded in the Physarum plasmodium.

Jagged gives endothelial tip cells an edge.

PubMed

Suchting, Steven; Eichmann, Anne

2009-06-12

Sprouting blood vessels have tip cells that lead and stalk cells that follow. Benedito et al. (2009) now show that competition between endothelial cells for the tip position is regulated by glycosylation of Notch receptors and by the opposing actions of the Notch ligands Jagged1 and Delta-like 4.

[Intrathoracic migration of a ventriculoperitoneal shunt catheter: a case report].

PubMed

Sánchez-Medina, Yanire; Domínguez-Báez, Jaime; Lazo-Fernández, Eglis; Pérez Del Rosario, Pedro Antonio; Zanabria-Ortiz, Robert

2015-01-01

The intrathoracic complications from ventriculoperitoneal shunt placement are very rare. However, they are potentially serious if not treated. We report the case of thoracic migration of a peritoneal catheter after ventriculoperitoneal shunt and we also review the literature references with discussion of the different mechanisms of shunt-tip migration described. No case of previous sternotomy as in our patient has been found published. All reports recommend early catheter repositioning into the peritoneal cavity after diagnosing the migration described, to prevent worse complications. Moreover, it is important to keep in mind that intrathoracic migration can happen and it is necessary to palpate the catheter continuously during passage through subcutaneous tunnelling to prevent it. Copyright © 2014 Sociedad Española de Neurocirugía. Published by Elsevier España. All rights reserved.

Relocalization of human chromatin remodeling cofactor TIP48 in mitosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sigala, Barbara; Edwards, Mina; Puri, Teena

2005-11-01

TIP48 is a highly conserved eukaryotic AAA{sup +} protein which is an essential cofactor for several complexes involved in chromatin acetylation and remodeling, transcriptional and developmental regulation and nucleolar organization and trafficking. We show that TIP48 abundance in HeLa cells did not change during the cell cycle, nor did its distribution in various biochemical fractions. However, we observed distinct changes in the subcellular localization of TIP48 during M phase using immunofluorescence microscopy. Our studies demonstrate that in interphase cells TIP48 was found mainly in the nucleus and exhibited a distinct localization in the nuclear periphery. As the cells entered mitosis,more » TIP48 was excluded from the condensing chromosomes but showed association with the mitotic apparatus. During anaphase, some TIP48 was detected in the centrosome colocalizing with tubulin but the strongest staining appeared in the mitotic equator associated with the midzone central spindle. Accumulation of TIP48 in the midzone and the midbody was observed in late telophase and cytokinesis. This redeployment of TIP48 during anaphase and cytokinesis was independent of microtubule assembly. The relocation of endogenous TIP48 to the midzone/midbody under physiological conditions suggests a novel and distinct function for TIP48 in mitosis and possible involvement in the exit of mitosis.« less

Role of Tat-interacting protein of 110 kDa and microRNAs in the regulation of hematopoiesis.

PubMed

Liu, Ying; He, Johnny J

2016-07-01

Hematopoiesis is regulated by cellular factors including transcription factors, microRNAs, and epigenetic modifiers. Understanding how these factors regulate hematopoiesis is pivotal for manipulating them to achieve their desired potential. In this review, we will focus on HIV-1 Tat-interacting protein of 110 kDa (Tip110) and its regulation of hematopoiesis. There are several pathways in hematopoiesis that involve Tip110 regulation. Tip110 is expressed in human cord blood CD34 cells; its expression decreases when CD34 cells begin to differentiate. Tip110 is also expressed in mouse marrow hematopoietic stem cells (HSC) and hematopoietic progenitor cells (HPC). Tip110 expression increases the number, survival, and cell cycling of HPC. Tip110-mediated regulation of hematopoiesis has been linked to its reciprocal control of proto-oncogene expression. Small noncoding microRNAs (miRs) have been shown to play important roles in regulation of hematopoiesis. miR-124 specifically targets 3'-untranslated region of Tip110 and subsequently regulates Tip110 expression in HSC. Our recent findings for manipulating expression levels of Tip110 in HSC and HPC could be useful for expanding HSC and HPC and for improving engraftment of cord blood HSC/HPC.

Modulation of TIP60 by Human Papilloma Virus in Breast Cancer

DTIC Science & Technology

2012-09-01

can also be a etiological agent or can augment the breast epithelial cells transformation and cancer. Body: Testing HPVE6 can degrade Tip60 in...sera, the spleen cells were collected from immunized mice and co- cultured with myeloma cells. These cells were cultured in selective HAT medium to... select for fused cells called Hybridoma cells. These hybridoma cells were cultured and tested for monoclonal antibody generation against Tip60 by ELISA

Direct mechanical stimulation of tip links in hair cells through DNA tethers

PubMed Central

Basu, Aakash; Lagier, Samuel; Vologodskaia, Maria; Fabella, Brian A; Hudspeth, AJ

2016-01-01

Mechanoelectrical transduction by hair cells commences with hair-bundle deflection, which is postulated to tense filamentous tip links connected to transduction channels. Because direct mechanical stimulation of tip links has not been experimentally possible, this hypothesis has not been tested. We have engineered DNA tethers that link superparamagnetic beads to tip links and exert mechanical forces on the links when exposed to a magnetic-field gradient. By pulling directly on tip links of the bullfrog's sacculus we have evoked transduction currents from hair cells, confirming the hypothesis that tension in the tip links opens transduction channels. This demonstration of direct mechanical access to tip links additionally lays a foundation for experiments probing the mechanics of individual channels. DOI: http://dx.doi.org/10.7554/eLife.16041.001 PMID:27331611

The mandibular ridge oral mucosa model of stromal influences on the endothelial tip cells: an immunohistochemical and TEM study.

PubMed

Rusu, Mugurel Constantin; Didilescu, Andreea Cristiana; Stănescu, Ruxandra; Pop, Florinel; Mănoiu, Valentina Mariana; Jianu, Adelina Maria; Vâlcu, Marek

2013-02-01

This study aimed to evaluate by immunohistochemistry and transmission electron microscopy (TEM) the morphological features of the oral mucosa endothelial tip cells (ETCs) and to determine the immune and ultrastructural patterns of the stromal nonimmune cells which could influence healing processes. Immune labeling was performed on bioptic samples obtained from six edentulous patients undergoing surgery for dental implants placement; three normal samples were collected from patients prior to the extraction of the third mandibular molar. The antibodies were tested for CD34, CD117(c-kit), platelet derived growth factor receptor-alpha (PDGFR-α), Mast Cell Tryptase, CD44, vimentin, CD45, CD105, alpha-smooth muscle actin, FGF2, Ki67. In light microscopy, while stromal cells (StrCs) of the reparatory and normal oral mucosa, with a fibroblastic appearance, were found positive for a CD34/CD44/CD45/CD105/PDGFR-α/vimentin immune phenotype, the CD117/c-kit labeling led to a positive stromal reaction only in the reparatory mucosa. In TEM, non-immune StrCs presenting particular ultrastructural features were identified as circulating fibrocytes (CFCs). Within the lamina propria CFCs were in close contact with ETCs. Long processes of the ETCs were moniliform, and hook-like collaterals were arising from the dilated segments, suggestive for a different stage migration. Maintenance and healing of oral mucosa are so supported by extensive processes of angiogenesis, guided by ETCs that, in turn, are influenced by the CFCs that populate the stromal compartment both in normal and reparatory states. Therefore, CFCs could be targeted by specific therapies, with pro- or anti-angiogenic purposes. Copyright © 2012 Wiley Periodicals, Inc.

Dll4-containing exosomes induce capillary sprout retraction in a 3D microenvironment

PubMed Central

Sharghi-Namini, Soheila; Tan, Evan; Ong, Lee-Ling Sharon; Ge, Ruowen; Asada, H. Harry

2014-01-01

Delta-like 4 (Dll4), a membrane-bound Notch ligand, plays a fundamental role in vascular development and angiogenesis. Dll4 is highly expressed in capillary endothelial tip cells and is involved in suppressing neighboring stalk cells to become tip cells during angiogenesis. Dll4-Notch signaling is mediated either by direct cell-cell contact or by Dll4-containing exosomes from a distance. However, whether Dll4-containing exosomes influence tip cells of existing capillaries is unknown. Using a 3D microfluidic device and time-lapse confocal microscopy, we show here for the first time that Dll4-containing exosomes causes tip cells to lose their filopodia and trigger capillary sprout retraction in collagen matrix. We demonstrate that Dll4 exosomes can freely travel through 3D collagen matrix and transfer Dll4 protein to distant tip cells. Upon reaching endothelial sprout, it causes filopodia and tip cell retraction. Continuous application of Dll4 exosomes from a distance lead to significant reduction of sprout formation. This effect correlates with Notch signaling activation upon Dll4-containing exosome interaction with recipient endothelial cells. Furthermore, we show that Dll4-containing exosomes increase endothelial cell motility while suppressing their proliferation. These data revealed novel functions of Dll4 in angiogenesis through exosomes. PMID:24504253

Bidirectional Fusion of the Heart-forming Fields in the Developing Chick Embryo

PubMed Central

Moreno-Rodriguez, R.A.; Krug, E.L.; Reyes, L.; Villavicencio, L.; Mjaatvedt, C.H.; Markwald, R.R.

2007-01-01

It is generally thought that the early pre-tubular chick heart is formed by fusion of the anterior or cephalic limits of the paired cardiogenic fields. However, this study shows that the heart fields initially fuse at their midpoint to form a transitory “butterfly”-shaped, cardiogenic structure. Fusion then progresses bi-directionally along the longitudinal axis in both cranial and caudal directions. Using in vivo labeling, we demonstrate that cells along the ventral fusion line are highly motile, crossing future primitive segments. We found that mesoderm cells migrated cephalically from the unfused tips of the anterior/cephalic wings into the head mesenchyme in the region that has been called the secondary heart field. Perturbing the anterior/cranial fusion results in formation of a biconal heart. A theoretical role of the ventral fusion line acting as a “heart organizer” and its role in cardia bifida is discussed. PMID:16252277

Macrophages and fibroblasts during inflammation and tissue repair in models of organ regeneration

PubMed Central

2017-01-01

Abstract This review provides a concise summary of the changing phenotypes of macrophages and fibroblastic cells during the local inflammatory response, the onset of tissue repair, and the resolution of inflammation which follow injury to an organ. Both cell populations respond directly to damage and present coordinated sequences of activation states which determine the reparative outcome, ranging from true regeneration of the organ to fibrosis and variable functional deficits. Recent work with mammalian models of organ regeneration, including regeneration of full‐thickness skin, hair follicles, ear punch tissues, and digit tips, is summarized and the roles of local immune cells in these systems are discussed. New investigations of the early phase of amphibian limb and tail regeneration, including the effects of pro‐inflammatory and anti‐inflammatory agents, are then briefly discussed, focusing on the transition from the normally covert inflammatory response to the initiation of the regeneration blastema by migrating fibroblasts and the expression of genes for limb patterning. PMID:28616244

A role for CSLD3 during cell-wall synthesis in apical plasma membranes of tip-growing root-hair cells.

PubMed

Park, Sungjin; Szumlanski, Amy L; Gu, Fangwei; Guo, Feng; Nielsen, Erik

2011-07-17

In plants, cell shape is defined by the cell wall, and changes in cell shape and size are dictated by modification of existing cell walls and deposition of newly synthesized cell-wall material. In root hairs, expansion occurs by a process called tip growth, which is shared by root hairs, pollen tubes and fungal hyphae. We show that cellulose-like polysaccharides are present in root-hair tips, and de novo synthesis of these polysaccharides is required for tip growth. We also find that eYFP-CSLD3 proteins, but not CESA cellulose synthases, localize to a polarized plasma-membrane domain in root hairs. Using biochemical methods and genetic complementation of a csld3 mutant with a chimaeric CSLD3 protein containing a CESA6 catalytic domain, we provide evidence that CSLD3 represents a distinct (1→4)-β-glucan synthase activity in apical plasma membranes during tip growth in root-hair cells.

Angiogenesis in the reparatory mucosa of the mandibular edentulous ridge is driven by endothelial tip cells.

PubMed

Stănescu, Ruxandra; Didilescu, Andreea Cristiana; Jianu, Adelina Maria; Rusu, M C

2012-01-01

Sprouting angiogenesis is led by specialized cell--the endothelial tip cells (ETCs) which can be targeted by pro- or anti-angiogenic therapies. We aimed to perform a qualitative study in order to assess the guidance by tip cells of the endothelial sprouts in the repairing mucosa of the edentulous mandibular crest. Mucosa of the mandibular edentulous ridge was collected from six adult patients, prior to healing abutment placement (second surgery). Slides were prepared and immunostained with antibodies for CD34 and Ki67. The abundant vasculature of the lamina propria was observed on slides and the CD34 antibodies labeled endothelial tip cells in various stages of the endothelial sprouts. Ki67 identified positive endothelial cells, confirming the proliferative status of the microvascular bed. According to the results, the in situ sprouting angiogenesis is driven by tip cells in the oral mucosa of the edentulous ridge and these cells can be targeted by various therapies, as required by the local pathologic or therapeutic conditions.

[Study on teratogenic effect of potassium dichromate on Vicia faba root tip cells].

PubMed

Qian, Xiao-Wei

2004-05-01

We studied the aberrant effects of different concentrations of potassium dichromate on Vicia faba root tip cells. The micronucleus and chromosome aberration assay was conducted to determine the micronucleus rate and chromosome aberration rate of Vicia faba root tip cells induced by potassium dichromate. The result indicated that potassium dichromate could increase the micronucleus rate of Vicia faba root tip cells. Within certain range of concentration the rate of micronucleus was found to be increased with the increase of potassium dichromate concentration,but beyond this range the rate of micronucleus decreased with further increase of potassium dichromate concentration. The potassium dichromate at different concentrations could increase the cell mitosis index. Besides,it also caused various types of chromosome aberration,and the rates of chromosome aberration were always higher than that of the control group. The conclusion of this study was that potassium dichromate has obvious teratogenic effect on Vicia faba root tip cells.

A fall land bird migration across the South China Sea from Indo-China to the Greater Sunda Islands

USGS Publications Warehouse

Ellis, D.H.; Kepler, A.K.; Kepler, C.B.

1994-01-01

We encountered 150 land birds representing 14 families along the cruise track of the Soviet Oceanographic Research Vessel AKADEMlK KOROLEV in the South China Sea. We saw most of these birds during a 3 -day period in a small area c. 350 km southeast of the southern tip of the Indo-China peninsula. These observations suggest that a significant land bird migration corridor crosses the South China Sea from Viet Nam to Borneo.

Ultrastructural analysis of cell component distribution in the apical cell of Ceratodon protonemata

NASA Technical Reports Server (NTRS)

Walker, L. M.; Sack, F. D.

1995-01-01

A distinctive feature of tip-growing plant cells is that cell components are distributed differentially along the length of the cell, although most ultrastructural analyses have been qualitative. The longtitudinal distribution of cell components was studied both qualitatively and quantitatively in the apical cell of dark-grown protonemata of the moss Ceratodon. The first 35 micrometers of the apical cell was analyzed stereologically using transmission electron microscopy. There were four types of distributions along the cell's axis, three of them differential: (1) tubular endoplasmic reticulum was evenly distributed, (2) cisternal endoplasmic reticulum and Golgi vesicles were distributed in a tip-to-base gradient, (3) plastids, vacuoles, and Golgi stacks were enriched in specific areas, although the locations of the enrichments varied, and (4) mitochondria were excluded in the tip-most 5 micrometers and evenly distributed throughout the remaining 30 micrometers. This study provides one of the most comprehensive quantitative, ultrastructural analyses of the distribution of cell components in the apex of any tip-growing plant cell. The finding that almost every component had its own spatial arrangement demonstrates the complexity of the organization and regulation of the distribution of components in tip-growing cells.

Tip60 degradation by adenovirus relieves transcriptional repression of viral transcriptional activator EIA.

PubMed

Gupta, A; Jha, S; Engel, D A; Ornelles, D A; Dutta, A

2013-10-17

Adenoviruses are linear double-stranded DNA viruses that infect human and rodent cell lines, occasionally transform them and cause tumors in animal models. The host cell challenges the virus in multifaceted ways to restrain viral gene expression and DNA replication, and sometimes even eliminates the infected cells by programmed cell death. To combat these challenges, adenoviruses abrogate the cellular DNA damage response pathway. Tip60 is a lysine acetyltransferase that acetylates histones and other proteins to regulate gene expression, DNA damage response, apoptosis and cell cycle regulation. Tip60 is a bona fide tumor suppressor as mice that are haploid for Tip60 are predisposed to tumors. We have discovered that Tip60 is degraded by adenovirus oncoproteins EIB55K and E4orf6 by a proteasome-mediated pathway. Tip60 binds to the immediate early adenovirus promoter and suppresses adenovirus EIA gene expression, which is a master regulator of adenovirus transcription, at least partly through retention of the virally encoded repressor pVII on this promoter. Thus, degradation of Tip60 by the adenoviral early proteins is important for efficient viral early gene transcription and for changes in expression of cellular genes.

HIV-1 Tat targets Tip60 to impair the apoptotic cell response to genotoxic stresses

PubMed Central

Col, Edwige; Caron, Cécile; Chable-Bessia, Christine; Legube, Gaelle; Gazzeri, Sylvie; Komatsu, Yasuhiko; Yoshida, Minoru; Benkirane, Monsef; Trouche, Didier; Khochbin, Saadi

2005-01-01

HIV-1 transactivator Tat uses cellular acetylation signalling by targeting several cellular histone acetyltransferases (HAT) to optimize its various functions. Although Tip60 was the first HAT identified to interact with Tat, the biological significance of this interaction has remained obscure. We had previously shown that Tat represses Tip60 HAT activity. Here, a new mechanism of Tip60 neutralization by Tat is described, where Tip60 is identified as a substrate for the newly reported p300/CBP-associated E4-type ubiquitin-ligase activity, and Tat uses this mechanism to induce the polyubiquitination and degradation of Tip60. Tip60 targeting by Tat results in a dramatic impairment of the Tip60-dependent apoptotic cell response to DNA damage. These data reveal yet unknown strategies developed by HIV-1 to increase cell resistance to genotoxic stresses and show a role of Tat as a modulator of cellular protein ubiquitination. PMID:16001085

[Effects of chlorobenzene stress on seedling growth and cell division of Vicia faba].

PubMed

Liu, Wan; Zhou, Qixing; Li, Peijun; Sun, Tieheng; Tai, Peidong; Xu, Huaxia; Zhang, Chungui; Zhang, Hairong

2003-04-01

Effects of 1, 2, 4-trichlorobenzene (TCB) stress on seedling growth, cell division and chromosomal aberration frequency of root-tip cells of Vicia faba were studied. The results indicated that the growth of the root length and mitotic index of root tip cells were successively decreased and even stopped with the increase of TCB concentrations and treatment duration. Numerical and structural chromosomal aberrations at metaphase and anaphase of root-tip cells in Vicia faba seedlings were produced by 50-300 micrograms.g-1 TCB treatment for 12-96 h. The percentage of c-mitosis, chromosomal bridge and chromosomal asymmetry array in root tip cells exposed to 50-100 micrograms.g-1 TCB for 12-24 h was up to 1.0-10.3%. The percentage of chromosomal stickness (S), chromosomal stickiness + chromosomal breakage (S + B), chromosomal stickness + chromosomal ring (S + R), chromosomal stickiness + chromosomal asymmetry array (S + A) and chromosomal stickness + chromosomal bridge (S + Be) in root tip cells reached 47.9-88.9%, and 18.1-29.6% for different kinds of chromosomal breakage at 300 micrograms.g-1 TCB for 12-96 h. Thus, the chromosomal aberration of root tip cells in Vicia faba seedlings could be used as a sensitive biomarker of monitoring soil contaminated with TCB.

Adhesion between peptides/antibodies and breast cancer cells

NASA Astrophysics Data System (ADS)

Meng, J.; Paetzell, E.; Bogorad, A.; Soboyejo, W. O.

2010-06-01

Atomic force microscopy (AFM) techniques were used to measure the adhesion forces between the receptors on breast cancer cells specific to human luteinizing hormone-releasing hormone (LHRH) peptides and antibodies specific to the EphA2 receptor. The adhesion forces between LHRH-coated AFM tips and human MDA-MB-231 cells (breast cancer cells) were shown to be about five times greater than those between LHRH-coated AFM tips and normal Hs578Bst breast cells. Similarly, those between EphA2 antibody-coated AFM tips and breast cancer cells were over five times greater than those between EphA2 antibody-coated AFM tips and normal breast cells. The results suggest that AFM can be used for the detection of breast cancer cells in biopsies. The implications of the results are also discussed for the early detection and localized treatment of cancer.

Characterization of the initial level and migration of silicone oil lubricant in empty prefilled syringes for biologics using infrared spectroscopy.

PubMed

Bee, Jared S; Frey, Vadim V; Javed, Urooj; Chung, Jonathan; Corcoran, Marta L; Roussel, Paul S; Krause, Stephan O; Cash, Patricia W; Bishop, Steven M; Dimitrova, Mariana N

2014-01-01

Glass prefillable syringes are lubricated with silicone oil to ensure functionality and a consistent injection for the end user. If excessive silicone is applied, droplets could potentially result in aggregation of sensitive biopharmaceuticals or clouding of the solution. Therefore, monitoring and optimization of the applied silicone layer is critical for prefilled syringe development. The hydrophobic properties of silicone oil, the potential for assay interference, and the very small quantities applied to prefilled syringes present a challenge for the development of a suitable assay. In this work we present a rapid and simple Fourier transform infrared (FTIR) spectroscopy method for quantitation of total silicone levels applied to prefilled syringes. Level-dependent silicone oil migration occurred over time for empty prefilled syringes stored tip-up. However, migration from all prefilled syringes with between 0.25 and 0.8 mg of initial silicone oil resulted in a stable limiting minimum level of between 0.15 and 0.26 mg of silicone in the syringe reached after 1 to 4 years of empty tip-up storage. The results of the FTIR assay correlated well with non-destructive reflectometry characterization of the syringes. This assay can provide valuable data for selection of a robust initial silicone oil target and quality control of prefilled syringes intended for biopharmaceuticals. Glass prefillable syringes are lubricated with silicone oil to ensure functionality and a consistent injection for the end user. If excessive silicone is applied, droplets could potentially result in aggregation of sensitive biopharmaceuticals or clouding of the solution. Therefore, monitoring and optimization of the applied silicone layer is critical for prefilled syringe development. The hydrophobic properties of silicone oil, the potential for assay interference, and the very small quantities applied to prefilled syringes present a challenge for the development of a suitable assay. In this work we present a rapid and simple Fourier transform infrared (FTIR) spectroscopy method for quantitation of total silicone levels applied to prefilled syringes. Level-dependent silicone oil migration occurred over time for empty prefilled syringes stored tip-up. However, migration from all prefilled syringes with between 0.25 and 0.8 mg of initial silicone oil resulted in a stable limiting minimum level of between 0.15 and 0.26 mg of silicone in the syringe reached after 1 to 4 years of empty tip-up storage. The results of the FTIR assay correlated well with non-destructive reflectometry characterization of the syringes. This assay can provide valuable data for selection of a robust initial silicone oil target and quality control of prefilled syringes intended for biopharmaceuticals. © PDA, Inc. 2014.

DNA-binding activity of TNF-{alpha} inducing protein from Helicobacter pylori

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzuhara, T.; Suganuma, M.; Oka, K.

2007-11-03

Tumor necrosis factor-{alpha} (TNF-{alpha}) inducing protein (Tip{alpha}) is a carcinogenic factor secreted from Helicobacter pylori (H. pylori), mediated through both enhanced expression of TNF-{alpha} and chemokine genes and activation of nuclear factor-{kappa}B. Since Tip{alpha} enters gastric cancer cells, the Tip{alpha} binding molecules in the cells should be investigated. The direct DNA-binding activity of Tip{alpha} was observed by pull down assay using single- and double-stranded genomic DNA cellulose. The surface plasmon resonance assay, indicating an association between Tip{alpha} and DNA, revealed that the affinity of Tip{alpha} for (dGdC)10 is 2400 times stronger than that of del-Tip{alpha}, an inactive Tip{alpha}. This suggestsmore » a strong correlation between DNA-binding activity and carcinogenic activity of Tip{alpha}. And the DNA-binding activity of Tip{alpha} was first demonstrated with a molecule secreted from H. pylori.« less

Early establishment of epithelial apoptosis in the developing human small intestine.

PubMed

Vachon, P H; Cardin, E; Harnois, C; Reed, J C; Vézina, A

2000-12-01

In the adult small intestine, the dynamic renewal of the epithelium is characterized by a sequence of cell production in the crypts, cell maturation and cell migration to the tip of villi, where apoptosis is undertaken. Little is known about enterocytic apoptosis during development. In man, intestinal architectural features and functions are acquired largely by mid-gestation (18-20 wks); the question whether the establishment of enterocytic apoptotic processes parallels or not the acquisition of other intestinal functional features remains open. In the present study, we approached this question by examining enterocytic apoptosis during development of the human jejunum (9-20 wks gestation), using the ISEL (in situ terminal uridine deoxynucleotidyl nick-end labelling) method. Between 9 and 17 wks, apoptotic enterocytes were not evidenced. However, beginning at the 18 wks stage, ISEL-positive enterocytes were regularly observed at the tip of villi. Since the Bcl-2 family of proteins constitutes a critical checkpoint in apoptosis, acting upstream of the apoptotic machinery, we investigated the expression of six Bcl-2 homologs (Bcl-2, Bcl-X(L), Mcl-1, Bax, Bak, Bad) and one non-homologous associated molecule (Bag-1). By immunofluorescence, we found that all homologs analyzed were expressed by enterocytes between 9 and 20 wks. However, Bcl-2 homologs underwent a gradual compartmentalization of epithelial expression along the maturing crypt-villus axis, to establish gradients of expression by 18-20 wks. Western blot analyses indicated that the expression levels of Bcl-2 homologs were modulated during morphogenesis of the crypt-villus axis, in parallel to their gradual compartmentalization of expression. Altogether, these data suggest that regulatory mechanisms of human enterocytic apoptosis become established by mid-gestation (18-20 wks) and coincide with the maturation of the crypt-villus axis of cell proliferation, differentiation and renewal.

Use of Anti-phospho-girdin Antibodies to Visualize Intestinal Tuft Cells in Free-Floating Mouse Jejunum Cryosections

PubMed Central

Mizutani, Yuka; Kuga, Daisuke; Iida, Machiko; Ushida, Kaori; Takagi, Tsuyoshi; Tokita, Yoshihito; Takahashi, Masahide; Asai, Masato

2018-01-01

The actin binding protein girdin is a cytosolic protein that is required for actin remodeling to trigger cell migration in various tissues. Girdin is phosphorylated by both receptor and non-receptor tyrosine kinases at tyrosine 1798. Omori et al. developed site- and phosphorylation status-specific antibodies against human girdin at tyrosine-1798 (pY1798), which specifically bind to phosphorylated tyrosine-1798, but not to unphosphorylated tyrosine-1798. pY1798 antibodies have been used to specifically label tuft cells (TCs) that are present in mammalian gastrointestinal tissues, but the function of these cells is unclear. This protocol allows the robust visualization of TCs in the jejunum using pY1798 antibodies and immunofluorescence. To ensure successful and simple TC visualization, this protocol includes two histological techniques: production of free-floating cryosections from gelatin-filled jejunum tissue, and low-temperature antigen retrieval at 50 °C for 3 h. Filling the jejunum with gelatin maintains the shape of free-floating sections throughout the staining procedure, whereas low-temperature antigen retrieval ensures robust signals from TCs. Successful use of this protocol results in pY1798 staining of TCs distributed from villus tip to crypt. Stained TCs have a spool-shaped soma and fluorescent signals condense at the lumenal tip, which corresponds to the protruding 'tuft.' Phalloidin staining colocalized with pY1798-positive TCs at the thickened brush border, and corresponds to a rootlet mass extending from the TC tuft. This protocol could be used to examine TCs in human biopsy samples collected with gastrointestinal endoscopes. Furthermore, TCs were recently reported to accumulate following parasite infection in mice, suggesting that this protocol could have applications for diagnosis of parasite infections in the human gut. PMID:29630055

Use of Anti-phospho-girdin Antibodies to Visualize Intestinal Tuft Cells in Free-Floating Mouse Jejunum Cryosections.

PubMed

Mizutani, Yuka; Kuga, Daisuke; Iida, Machiko; Ushida, Kaori; Takagi, Tsuyoshi; Tokita, Yoshihito; Takahashi, Masahide; Asai, Masato

2018-03-21

The actin binding protein girdin is a cytosolic protein that is required for actin remodeling to trigger cell migration in various tissues. Girdin is phosphorylated by both receptor and non-receptor tyrosine kinases at tyrosine 1798. Omori et al. developed site- and phosphorylation status-specific antibodies against human girdin at tyrosine-1798 (pY1798), which specifically bind to phosphorylated tyrosine-1798, but not to unphosphorylated tyrosine-1798. pY1798 antibodies have been used to specifically label tuft cells (TCs) that are present in mammalian gastrointestinal tissues, but the function of these cells is unclear. This protocol allows the robust visualization of TCs in the jejunum using pY1798 antibodies and immunofluorescence. To ensure successful and simple TC visualization, this protocol includes two histological techniques: production of free-floating cryosections from gelatin-filled jejunum tissue, and low-temperature antigen retrieval at 50 °C for 3 h. Filling the jejunum with gelatin maintains the shape of free-floating sections throughout the staining procedure, whereas low-temperature antigen retrieval ensures robust signals from TCs. Successful use of this protocol results in pY1798 staining of TCs distributed from villus tip to crypt. Stained TCs have a spool-shaped soma and fluorescent signals condense at the lumenal tip, which corresponds to the protruding 'tuft.' Phalloidin staining colocalized with pY1798-positive TCs at the thickened brush border, and corresponds to a rootlet mass extending from the TC tuft. This protocol could be used to examine TCs in human biopsy samples collected with gastrointestinal endoscopes. Furthermore, TCs were recently reported to accumulate following parasite infection in mice, suggesting that this protocol could have applications for diagnosis of parasite infections in the human gut.

Reduction of TIP30 in esophageal squamous cell carcinoma cells involves promoter methylation and microRNA-10b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Wenjie, E-mail: dongwenjie200581@126.com; Shen, Ruizhe; Cheng, Shidan

2014-10-31

Highlights: • TIP30 expression is frequently suppressed in ESCC. • TIP30 was hypermethylated in ESCC. • Reduction of TIP30 was significantly correlated with LN metastasis. • miR-10b is a direct regulator of TIP30. - Abstract: TIP30 is a putative tumor suppressor that can promote apoptosis and inhibit angiogenesis. However, the role of TIP30 in esophageal squamous cell carcinoma (ESCC) biology has not been investigated. Immunohistochemistry was used to investigate the expression of TIP30 in 70 ESCC. Hypermethylation of TIP30 was evaluated by the methylation specific PCR (MSP) method in ESCC (tumor and paired adjacent non-tumor tissues). Lost expression of TIP30more » was observed in 50 of 70 (71.4%) ESCC. 61.4% (43 of 70) of primary tumors analyzed displayed TIP30 hypermethylation, indicating that this aberrant characteristic is common in ESCC. Moreover, a statistically significant inverse association was found between TIP30 methylation status and expression of the TIP30 protein in tumor tissues (p = 0.001). We also found that microRNA-10b (miR-10b) targets a homologous DNA region in the 3′untranslated region of the TIP30 gene and represses its expression at the transcriptional level. Reporter assay with 3′UTR of TIP30 cloned downstream of the luciferase gene showed reduced luciferase activity in the presence of miR-10b, providing strong evidence that miR-10b is a direct regulator of TIP30. These results suggest that TIP30 expression is regulated by promoter methylation and miR-10b in ESCC.« less

Low-dimensional manifold of actin polymerization dynamics

NASA Astrophysics Data System (ADS)

Floyd, Carlos; Jarzynski, Christopher; Papoian, Garegin

2017-12-01

Actin filaments are critical components of the eukaryotic cytoskeleton, playing important roles in a number of cellular functions, such as cell migration, organelle transport, and mechanosensation. They are helical polymers with a well-defined polarity, composed of globular subunits that bind nucleotides in one of three hydrolysis states (ATP, ADP-Pi, or ADP). Mean-field models of the dynamics of actin polymerization have succeeded in, among other things, determining the nucleotide profile of an average filament and resolving the mechanisms of accessory proteins. However, these models require numerical solution of a high-dimensional system of nonlinear ordinary differential equations. By truncating a set of recursion equations, the Brooks-Carlsson (BC) model reduces dimensionality to 11, but it still remains nonlinear and does not admit an analytical solution, hence, significantly hindering understanding of its resulting dynamics. In this work, by taking advantage of the fast timescales of the hydrolysis states of the filament tips, we propose two model reduction schemes: the quasi steady-state approximation model is five-dimensional and nonlinear, whereas the constant tip (CT) model is five-dimensional and linear, resulting from the approximation that the tip states are not dynamic variables. We provide an exact solution of the CT model and use it to shed light on the dynamical behaviors of the full BC model, highlighting the relative ordering of the timescales of various collective processes, and explaining some unusual dependence of the steady-state behavior on initial conditions.

Larval behavioral, morphological changes, and nematocyte dynamics during settlement of actinulae of Tubularia mesembryanthemum, Allman 1871 (Hydrozoa: Tubulariidae).

PubMed

Yamashita, Keiji; Kawaii, Satoru; Nakai, Mitsuyo; Fusetani, Nobuhiro

2003-06-01

The marine colonial hydroid Tubularia mesembryanthemum produces a morphologically unique dispersive stage, the actinula larva. Detailed observations were made on the behaviors and nematocyte dynamics of actinula larvae during attachment and morphogenesis by employing microscopic and time lapse video techniques. These observations produced four primary results. (1) Actinula larvae demonstrated two forms of attachment: temporary attachment by atrichous isorhiza (AI)-nematocysts discharged from the aboral tentacle (AT) tips-and permanent settlement by cement secretion from the columnar gland cells of the basal protrusion. (2) During larval settlement, numerous AIs were discharged from the AT tips with sinuous movement and rubbing of the tentacles onto the substrata, leading to "nematocyte-printing" around the settlement site. (3) Simultaneous with the discharge of the AIs, migration of stenoteles, desmonemes, and microbasic mastigophores occurred, resulting in a dramatic change of nematocyte composition in the ATs after larval settlement. This was in parallel with changes in larval behavior and the tentacle function. (4) Nematocyte-printing behavior during settlement could be recognized as metamorphic behavior responsible for irreversible changes in AT function, from attachment to feeding and defense.

Imaging of soft material with carbon nanotube tip using near-field scanning microwave microscopy.

PubMed

Wu, Zhe; Sun, Wei-Qiang; Feng, Tao; Tang, Shawn Wenjie; Li, Gang; Jiang, Kai-Li; Xu, Sheng-Yong; Ong, Chong Kim

2015-01-01

In this manuscript, a near-field scanning microwave microscope (NSMM) of our own design is introduced while using a multi-walled carbon nanotube (MWCNT) bundle as the tip (referred to as 'CNT tip'). Clear images of gold-patterned numbers, photoresist stripes and corneal endothelial cells (cell line B4G12) were obtained by mapping the resonant frequency fr and S11 amplitude of a given area while the NSMM is operating in tapping mode. The CNT tip helps to improve image quality and reveals more information about the sample as compared to a traditional metallic tip. The CNT tip is flexible and does not scratch the surface of the sample during the scan, which is useful for imaging soft material in biological science. In the imaging of the B4G12 endothelial cells, the nuclei and cytoplasm can be clearly distinguished from the rest of the cell and its surrounding medium. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of dynamic matrix remodelling on en masse migration of fibroblasts on collagen matrices.

PubMed

Ozcelikkale, Altug; Dutton, J Craig; Grinnell, Frederick; Han, Bumsoo

2017-10-01

Fibroblast migration plays a key role during various physiological and pathological processes. Although migration of individual fibroblasts has been well studied, migration in vivo often involves simultaneous locomotion of fibroblasts sited in close proximity, so-called ' en masse migration', during which intensive cell-cell interactions occur. This study aims to understand the effects of matrix mechanical environments on the cell-matrix and cell-cell interactions during en masse migration of fibroblasts on collagen matrices. Specifically, we hypothesized that a group of migrating cells can significantly deform the matrix, whose mechanical microenvironment dramatically changes compared with the undeformed state, and the alteration of the matrix microenvironment reciprocally affects cell migration. This hypothesis was tested by time-resolved measurements of cell and extracellular matrix movement during en masse migration on collagen hydrogels with varying concentrations. The results illustrated that a group of cells generates significant spatio-temporal deformation of the matrix before and during the migration. Cells on soft collagen hydrogels migrate along tortuous paths, but, as the matrix stiffness increases, cell migration patterns become aligned with each other and show coordinated migration paths. As cells migrate, the matrix is locally compressed, resulting in a locally stiffened and dense matrix across the collagen concentration range studied. © 2017 The Author(s).

Embryonic cell-cell adhesion: a key player in collective neural crest migration.

PubMed

Barriga, Elias H; Mayor, Roberto

2015-01-01

Cell migration is essential for morphogenesis, adult tissue remodeling, wound healing, and cancer cell migration. Cells can migrate as individuals or groups. When cells migrate in groups, cell-cell interactions are crucial in order to promote the coordinated behavior, essential for collective migration. Interestingly, recent evidence has shown that cell-cell interactions are also important for establishing and maintaining the directionality of these migratory events. We focus on neural crest cells, as they possess extraordinary migratory capabilities that allow them to migrate and colonize tissues all over the embryo. Neural crest cells undergo an epithelial-to-mesenchymal transition at the same time than perform directional collective migration. Cell-cell adhesion has been shown to be an important source of planar cell polarity and cell coordination during collective movement. We also review molecular mechanisms underlying cadherin turnover, showing how the modulation and dynamics of cell-cell adhesions are crucial in order to maintain tissue integrity and collective migration in vivo. We conclude that cell-cell adhesion during embryo development cannot be considered as simple passive resistance to force, but rather participates in signaling events that determine important cell behaviors required for cell migration. © 2015 Elsevier Inc. All rights reserved.

Means and methods for cytometric therapies

DOEpatents

Gillies, George T.; Fillmore, Helen; Broaddus, William C.; Evans, III, Boyd M.; Allison, Stephen W.

2013-03-26

A functionalized tip is incorporated into catheters for the cytometric delivery of cells into the brain and other body parts. For use in the brain, the tip forms part of a neurosurgical probe having a proximal end and a distal end. In addition to the functionalized tip, the probe has at least one cell slurry delivery lumen and a plurality of optical fibers configured along the probe, terminating in the tip to provide the photo-optical capability needed to monitor the viability and physiological behavior of the grafted cells as well as certain characteristics of the cellular environment. Details are also presented of the use of a neurocatheter having a cytometric tip of the type disclosed in the invention, as employed within the context of a feedback and control system for regulating the number of cells delivered to the brain of a patient.

The type III secretion system needle tip complex mediates host cell sensing and translocon insertion.

PubMed

Veenendaal, Andreas K J; Hodgkinson, Julie L; Schwarzer, Lynn; Stabat, David; Zenk, Sebastian F; Blocker, Ariel J

2007-03-01

Type III secretion systems (T3SSs) are essential virulence determinants of many Gram-negative bacterial pathogens. The Shigella T3SS consists of a cytoplasmic bulb, a transmembrane region and a hollow 'needle' protruding from the bacterial surface. Physical contact with host cells initiates secretion and leads to assembly of a pore, formed by IpaB and IpaC, in the host cell membrane, through which proteins that facilitate host cell invasion are translocated. As the needle is implicated in host cell sensing and secretion regulation, its tip should contain components that initiate host cell contact. Through biochemical and immunological studies of wild-type and mutant Shigella T3SS needles, we reveal tip complexes of differing compositions and functional states, which appear to represent the molecular events surrounding host cell sensing and pore formation. Our studies indicate that the interaction between IpaB and IpaD at needle tips is key to host cell sensing, orchestration of IpaC secretion and its subsequent assembly at needle tips. This allows insertion into the host cell membrane of a translocation pore that is continuous with the needle.

Micro injector sample delivery system for charged molecules

DOEpatents

Davidson, James C.; Balch, Joseph W.

1999-11-09

A micro injector sample delivery system for charged molecules. The injector is used for collecting and delivering controlled amounts of charged molecule samples for subsequent analysis. The injector delivery system can be scaled to large numbers (>96) for sample delivery to massively parallel high throughput analysis systems. The essence of the injector system is an electric field controllable loading tip including a section of porous material. By applying the appropriate polarity bias potential to the injector tip, charged molecules will migrate into porous material, and by reversing the polarity bias potential the molecules are ejected or forced away from the tip. The invention has application for uptake of charged biological molecules (e.g. proteins, nucleic acids, polymers, etc.) for delivery to analytical systems, and can be used in automated sample delivery systems.

Tip cells: master regulators of tubulogenesis?

PubMed

Weavers, Helen; Skaer, Helen

2014-07-01

The normal development of an organ depends on the coordinated regulation of multiple cell activities. Focusing on tubulogenesis, we review the role of specialised cells or groups of cells that are selected from within tissue primordia and differentiate at the outgrowing tips or leading edge of developing tubules. Tip or leading cells develop distinctive patterns of gene expression that enable them to act both as sensors and transmitters of intercellular signalling. This enables them to explore the environment, respond to both tissue intrinsic signals and extrinsic cues from surrounding tissues and to regulate the behaviour of their neighbours, including the setting of cell fate, patterning cell division, inducing polarity and promoting cell movement and cell rearrangements by neighbour exchange. Tip cells are also able to transmit mechanical tension to promote tissue remodelling and, by interacting with the extracellular matrix, they can dictate migratory pathways and organ shape. Where separate tubular structures fuse to form networks, as in the airways of insects or the vascular system of vertebrates, specialised fusion tip cells act to interconnect disparate elements of the developing network. Finally, we consider their importance in the maturation of mature physiological function and in the development of disease. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Tropomodulin 1 Constrains Fiber Cell Geometry during Elongation and Maturation in the Lens Cortex

PubMed Central

Nowak, Roberta B.

2012-01-01

Lens fiber cells exhibit a high degree of hexagonal packing geometry, determined partly by tropomodulin 1 (Tmod1), which stabilizes the spectrin-actin network on lens fiber cell membranes. To ascertain whether Tmod1 is required during epithelial cell differentiation to fiber cells or during fiber cell elongation and maturation, the authors quantified the extent of fiber cell disorder in the Tmod1-null lens and determined locations of disorder by confocal microscopy and computational image analysis. First, nearest neighbor analysis of fiber cell geometry in Tmod1-null lenses showed that disorder is confined to focal patches. Second, differentiating epithelial cells at the equator aligned into ordered meridional rows in Tmod1-null lenses, with disordered patches first observed in elongating fiber cells. Third, as fiber cells were displaced inward in Tmod1-null lenses, total disordered area increased due to increased sizes (but not numbers) of individual disordered patches. The authors conclude that Tmod1 is required first to coordinate fiber cell shapes and interactions during tip migration and elongation and second to stabilize ordered fiber cell geometry during maturation in the lens cortex. An unstable spectrin-actin network without Tmod1 may result in imbalanced forces along membranes, leading to fiber cell rearrangements during elongation, followed by propagation of disorder as fiber cells mature. PMID:22473940

Quantitative analysis of random migration of cells using time-lapse video microscopy.

PubMed

Jain, Prachi; Worthylake, Rebecca A; Alahari, Suresh K

2012-05-13

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion (1, 2). During directional migration, cells move rapidly in response to an extracellular chemotactic signal, or in response to intrinsic cues (3) provided by the basic motility machinery. Random migration occurs when a cell possesses low intrinsic directionality, allowing the cells to explore their local environment. Cell migration is a complex process, in the initial response cell undergoes polarization and extends protrusions in the direction of migration (2). Traditional methods to measure migration such as the Boyden chamber migration assay is an easy method to measure chemotaxis in vitro, which allows measuring migration as an end point result. However, this approach neither allows measurement of individual migration parameters, nor does it allow to visualization of morphological changes that cell undergoes during migration. Here, we present a method that allows us to monitor migrating cells in real time using video - time lapse microscopy. Since cell migration and invasion are hallmarks of cancer, this method will be applicable in studying cancer cell migration and invasion in vitro. Random migration of platelets has been considered as one of the parameters of platelet function (4), hence this method could also be helpful in studying platelet functions. This assay has the advantage of being rapid, reliable, reproducible, and does not require optimization of cell numbers. In order to maintain physiologically suitable conditions for cells, the microscope is equipped with CO(2) supply and temperature thermostat. Cell movement is monitored by taking pictures using a camera fitted to the microscope at regular intervals. Cell migration can be calculated by measuring average speed and average displacement, which is calculated by Slidebook software.

Modular control of endothelial sheet migration

PubMed Central

Vitorino, Philip; Meyer, Tobias

2008-01-01

Growth factor-induced migration of endothelial cell monolayers enables embryonic development, wound healing, and angiogenesis. Although collective migration is widespread and therapeutically relevant, the underlying mechanism by which cell monolayers respond to growth factor, sense directional signals, induce motility, and coordinate individual cell movements is only partially understood. Here we used RNAi to identify 100 regulatory proteins that enhance or suppress endothelial sheet migration into cell-free space. We measured multiple live-cell migration parameters for all siRNA perturbations and found that each targeted protein primarily regulates one of four functional outputs: cell motility, directed migration, cell–cell coordination, or cell density. We demonstrate that cell motility regulators drive random, growth factor-independent motility in the presence or absence of open space. In contrast, directed migration regulators selectively transduce growth factor signals to direct cells along the monolayer boundary toward open space. Lastly, we found that regulators of cell–cell coordination are growth factor-independent and reorient randomly migrating cells inside the sheet when boundary cells begin to migrate. Thus, cells transition from random to collective migration through a modular control system, whereby growth factor signals convert boundary cells into pioneers, while cells inside the monolayer reorient and follow pioneers through growth factor-independent migration and cell–cell coordination. PMID:19056882

Adenylyl cyclase A expression is tip-specific in Dictyostelium slugs and directs StatA nuclear translocation and CudA gene expression.

PubMed

Verkerke-van Wijk, I; Fukuzawa, M; Devreotes, P N; Schaap, P

2001-06-01

cAMP oscillations, generated by adenylyl cyclase A (ACA), coordinate cell aggregation in Dictyostelium and have also been implicated in organizer function during multicellular development. We used a gene fusion of the ACA promoter with a labile lacZ derivative to study the expression pattern of ACA. During aggregation, most cells expressed ACA, but thereafter expression was lost in all cells except those of the anterior tip. Before aggregation, ACA transcription was strongly upregulated by nanomolar cAMP pulses. Postaggregative transcription was sustained by nanomolar cAMP pulses, but downregulated by a continuous micromolar cAMP stimulus and by the stalk-cell-inducing factor DIF. Earlier work showed that the transcription factor StatA displays tip-specific nuclear translocation and directs tip-specific expression of the nuclear protein CudA, which is essential for culmination. Both StatA and CudA were present in nuclei throughout the entire slug in an aca null mutant that expresses ACA from the constitutive actin15 promoter. This suggests that the tip-specific expression of ACA directs tip-specific nuclear translocation of StatA and tip-specific expression of CudA. Copyright 2001 Academic Press.

Preparative electrophoresis of cultured human cells: Effect of cell cycle phase

NASA Technical Reports Server (NTRS)

Kunze, M. E.; Todd, P. W.; Goolsby, C. L.; Walker, J. T.

1985-01-01

Human epithelioid T-1E cells were cultured in suspension and subjected to density gradient electrophoresis upward in a vertical column. It is indicated that the most rapidly migrating cells were at the beginning of the cell cycle and the most slowly migrating cells were at the end of the cell cycle. The fastest migrating cells divided 24 hr later than the slowest migrating cells. Colonies developing from slowly migrating cells had twice as many cells during exponential growth as did the most rapidly migrating cells, and the numbers of cells per colony at any time was inversely related to the electrophoretic migration rate. The DNA measurements by fluorescence flow cytometry indicates that the slowest migrating cell populations are enriched in cells that have twice as much DNA as the fastest migrating cells. It is concluded that electrophoretic mobility of these cultured human cells declines steadily through the cell cycle and that the mobility is lowest at the end of G sub 2 phase and highest at the beginning of G sub 1 phase.

Mechanotransduction current is essential for stability of the transducing stereocilia in mammalian auditory hair cells

PubMed Central

Vélez-Ortega, A Catalina; Freeman, Mary J; Indzhykulian, Artur A; Grossheim, Jonathan M; Frolenkov, Gregory I

2017-01-01

Mechanotransducer channels at the tips of sensory stereocilia of inner ear hair cells are gated by the tension of 'tip links' interconnecting stereocilia. To ensure maximal sensitivity, tip links are tensioned at rest, resulting in a continuous influx of Ca2+ into the cell. Here, we show that this constitutive Ca2+ influx, usually considered as potentially deleterious for hair cells, is in fact essential for stereocilia stability. In the auditory hair cells of young postnatal mice and rats, a reduction in mechanotransducer current, via pharmacological channel blockers or disruption of tip links, leads to stereocilia shape changes and shortening. These effects occur only in stereocilia that harbor mechanotransducer channels, recover upon blocker washout or tip link regeneration and can be replicated by manipulations of extracellular Ca2+ or intracellular Ca2+ buffering. Thus, our data provide the first experimental evidence for the dynamic control of stereocilia morphology by the mechanotransduction current. DOI: http://dx.doi.org/10.7554/eLife.24661.001 PMID:28350294

Physcomitrella patens: a model for tip cell growth and differentiation.

PubMed

Vidali, Luis; Bezanilla, Magdalena

2012-12-01

The moss Physcomitrella patens has emerged as an excellent model system owing to its amenability to reverse genetics. The moss gametophyte has three filamentous tissues that grow by tip growth: chloronemata, caulonemata, and rhizoids. Because establishment of the moss plant relies on this form of growth, it is particularly suited for dissecting the molecular basis of tip growth. Recent studies demonstrate that a core set of actin cytoskeletal proteins is essential for tip growth. Additional actin cytoskeletal components are required for modulating growth to produce caulonemata and rhizoids. Differentiation into these cell types has previously been linked to auxin, light and nutrients. Recent studies have identified that core auxin signaling components as well as transcription factors that respond to auxin or nutrient levels are required for tip-growing cell differentiation. Future studies may establish a connection between the actin cytoskeleton and auxin or nutrient-induced cell differentiation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Joint effects of microwave and chromium trioxide on root tip cells of Vicia faba *

PubMed Central

Qian, Xiao-Wei; Luo, Wei-Hua; Zheng, Ou-Xiang

2006-01-01

The mutagenic effects of microwave and chromium trioxide (CrO3) on Vicia faba root tip were studied. Micronucleus assay and chromosomal aberration assay were used to determine the mitotic index, the micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells induced by microwave and CrO3. The results showed that the micronucleus frequency decreased, and that the mitotic index and chromosomal aberration frequency showed linear dose responses to CrO3, in treatment of microwave for 5 s. In microwave of 25 s, the mitotic index decreased, the micronucleus frequency and chromosomal aberration frequency increased with increase of CrO3 concentration. We concluded that microwave and CrO3 had antagonistic effect on the mitotic index of Vicia faba root tip cells, but had synergetic effect on micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells. PMID:16502510

Joint effects of microwave and chromium trioxide on root tip cells of Vicia faba.

PubMed

Qian, Xiao-wei; Luo, Wei-hua; Zheng, Ou-xiang

2006-03-01

The mutagenic effects of microwave and chromium trioxide (CrO(3)) on Vicia faba root tip were studied. Micronucleus assay and chromosomal aberration assay were used to determine the mitotic index, the micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells induced by microwave and CrO(3). The results showed that the micronucleus frequency decreased, and that the mitotic index and chromosomal aberration frequency showed linear dose responses to CrO(3), in treatment of microwave for 5 s. In microwave of 25 s, the mitotic index decreased, the micronucleus frequency and chromosomal aberration frequency increased with increase of CrO(3) concentration. We concluded that microwave and CrO(3) had antagonistic effect on the mitotic index of Vicia faba root tip cells, but had synergetic effect on micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells.

The Development of a Novel High Throughput Computational Tool for Studying Individual and Collective Cellular Migration

PubMed Central

Chapnick, Douglas A.; Jacobsen, Jeremy; Liu, Xuedong

2013-01-01

Understanding how cells migrate individually and collectively during development and cancer metastasis can be significantly aided by a computation tool to accurately measure not only cellular migration speed, but also migration direction and changes in migration direction in a temporal and spatial manner. We have developed such a tool for cell migration researchers, named Pathfinder, which is capable of simultaneously measuring the migration speed, migration direction, and changes in migration directions of thousands of cells both instantaneously and over long periods of time from fluorescence microscopy data. Additionally, we demonstrate how the Pathfinder software can be used to quantify collective cell migration. The novel capability of the Pathfinder software to measure the changes in migration direction of large populations of cells in a spatiotemporal manner will aid cellular migration research by providing a robust method for determining the mechanisms of cellular guidance during individual and collective cell migration. PMID:24386097

Can mesenchymal cells undergo collective cell migration?

PubMed Central

Theveneau, Eric

2011-01-01

Cell migration is critical for proper development of the embryo and is also used by many cell types to perform their physiological function. For instance, cell migration is essential for immune cells to monitor the body and for epithelial cells to heal a wound whereas, in cancer cells, acquisition of migratory capabilities is a critical step toward malignancy. Migratory cells are often categorized into two groups: (1) mesenchymal cells, produced by an epithelium-to-mesenchyme transition, that undergo solitary migration and (2) epithelial-like cells which migrate collectively. However, on some occasions, mesenchymal cells may travel in large, dense groups and exhibit key features of collectively migrating cells such as coordination and cooperation. Here, using data published on neural crest cells, a highly invasive mesenchymal cell population that extensively migrate throughout the embryo, we explore the idea that mesenchymal cells, including cancer cells, might be able to undergo collective cell migration under certain conditions and discuss how they could do so. PMID:22274714

Regulation of Cell Migration in Breast Cancer

DTIC Science & Technology

2011-04-01

the wound healing, assay by scarring and Oris plate migration assay, transwell migration assay and live - cell imaging studies. Cell migration capacity...evaluated by the use of techniques that include the wound healing assay by scarring and Oris plate migration assay, transwell migration assay and live - cell imaging studies

The Rice Basic Helix-Loop-Helix Transcription Factor TDR INTERACTING PROTEIN2 Is a Central Switch in Early Anther Development[C][W

PubMed Central

Fu, Zhenzhen; Yu, Jing; Cheng, Xiaowei; Zong, Xu; Xu, Jie; Chen, Mingjiao; Li, Zongyun; Zhang, Dabing; Liang, Wanqi

2014-01-01

In male reproductive development in plants, meristemoid precursor cells possessing transient, stem cell–like features undergo cell divisions and differentiation to produce the anther, the male reproductive organ. The anther contains centrally positioned microsporocytes surrounded by four distinct layers of wall: the epidermis, endothecium, middle layer, and tapetum. Here, we report that the rice (Oryza sativa) basic helix-loop-helix (bHLH) protein TDR INTERACTING PROTEIN2 (TIP2) functions as a crucial switch in the meristemoid transition and differentiation during early anther development. The tip2 mutants display undifferentiated inner three anther wall layers and abort tapetal programmed cell death, causing complete male sterility. TIP2 has two paralogs in rice, TDR and EAT1, which are key regulators of tapetal programmed cell death. We revealed that TIP2 acts upstream of TDR and EAT1 and directly regulates the expression of TDR and EAT1. In addition, TIP2 can interact with TDR, indicating a role of TIP2 in later anther development. Our findings suggest that the bHLH proteins TIP2, TDR, and EAT1 play a central role in regulating differentiation, morphogenesis, and degradation of anther somatic cell layers, highlighting the role of paralogous bHLH proteins in regulating distinct steps of plant cell–type determination. PMID:24755456

Mutations in cadherin 23 affect tip links in zebrafish sensory hair cells.

PubMed

Söllner, Christian; Rauch, Gerd-Jörg; Siemens, Jan; Geisler, Robert; Schuster, Stephan C; Müller, Ulrich; Nicolson, Teresa

2004-04-29

Hair cells have highly organized bundles of apical projections, or stereocilia, that are deflected by sound and movement. Displacement of stereocilia stretches linkages at the tips of stereocilia that are thought to gate mechanosensory channels. To identify the molecular machinery that mediates mechanotransduction in hair cells, zebrafish mutants were identified with defects in balance and hearing. In sputnik mutants, stereociliary bundles are splayed to various degrees, with individuals displaying reduced or absent mechanotransduction. Here we show that the defects in sputnik mutants are caused by mutations in cadherin 23 (cdh23). Mutations in Cdh23 also cause deafness and vestibular defects in mice and humans, and the protein is present in hair bundles. We show that zebrafish Cdh23 protein is concentrated near the tips of hair bundles, and that tip links are absent in homozygous sputnik(tc317e) larvae. Moreover, tip links are absent in larvae carrying weak alleles of cdh23 that affect mechanotransduction but not hair bundle integrity. We conclude that Cdh23 is an essential tip link component required for hair-cell mechanotransduction.

Guide wire entrapment by inferior vena cava filters: an experimental study.

PubMed

Rosen, Michael J; Burns, Justin M; Cobb, William S; Jacobs, David G; Heniford, B Todd; Sing, Ronald F

2005-09-01

In situ vena cava filters are at risk for complications with the use of J-tipped guide wires. The purpose of this study was to evaluate the impact of two commonly used J-tipped guide wires on the stability of the four most recently released vena cava filters in an in vitro flow model. Four filters (OptEase [F1], Günther Tulip [F2], Vena Tech LP [F3], and Recovery [F4]) were inserted into an in vitro flow model. Two J-tipped guide wires (0.032-inch [GW-1], 0.035-inch [GW-2]) were passed through each filter (n = 50 passes per wire) for a distance of 10 cm. The inserter was blind as to the effects of the wire. The filters were monitored by an independent observer for adverse events occurring between the filters and the guide wires. These were defined as: migrations (>1 cm), change of position (tilt>10 degrees), and entrapment of the wire (unable to remove wire). Descriptive statistics, chi-square, and Fisher's exact test were used (p < 0.05 considered significant). GW-1 resulted in a lower incidence of entrapment, migration, and tilt for all filters compared with GW-2 (F1, p = 0.003; F2, p < 0.0001; F3, p < 0.0001; F4, p = 0.0004). GW-1 resulted in entrapment in 0%, migration in 7.5%, and tilt in 10.5% of insertions. GW-2 resulted in entrapment in 1%, migration in 26.5%, and tilt in 5.5% of insertions. The incidence of adverse events for GW-1 was significantly different compared with all filters (F1, 0%; F2, 46%; F3, 4%; and F4, 22%; p < 0.0001). Similarly, the incidence of adverse events for GW-2 was significantly different when evaluating all filters (F1, 12%; F2, 48%; F3, 22%; F4 60%; p < 0.0001). The smaller-diameter guide wire resulted in a decreased incidence of adverse events for all filters, but there is still risk for complications. Knowledge of potential complications associated with vena cava filters and the postinsertion use of guide wires are essential to avoid potential mishaps.

Co-Regulation of Cell Polarization and Migration by Caveolar Proteins PTRF/Cavin-1 and Caveolin-1

PubMed Central

Hill, Michelle M.; Daud, Noor Huda; Aung, Cho Sanda; Loo, Dorothy; Martin, Sally; Murphy, Samantha; Black, Debra M.; Barry, Rachael; Simpson, Fiona; Liu, Libin; Pilch, Paul F.; Hancock, John F.; Parat, Marie-Odile; Parton, Robert G.

2012-01-01

Caveolin-1 and caveolae are differentially polarized in migrating cells in various models, and caveolin-1 expression has been shown to quantitatively modulate cell migration. PTRF/cavin-1 is a cytoplasmic protein now established to be also necessary for caveola formation. Here we tested the effect of PTRF expression on cell migration. Using fluorescence imaging, quantitative proteomics, and cell migration assays we show that PTRF/cavin-1 modulates cellular polarization, and the subcellular localization of Rac1 and caveolin-1 in migrating cells as well as PKCα caveola recruitment. PTRF/cavin-1 quantitatively reduced cell migration, and induced mesenchymal epithelial reversion. Similar to caveolin-1, the polarization of PTRF/cavin-1 was dependent on the migration mode. By selectively manipulating PTRF/cavin-1 and caveolin-1 expression (and therefore caveola formation) in multiple cell systems, we unveil caveola-independent functions for both proteins in cell migration. PMID:22912783

Epithelial-mesenchymal transition transcription factors control pluripotent adult stem cell migration in vivo in planarians

PubMed Central

Abnave, Prasad; Aboukhatwa, Ellen; Kosaka, Nobuyoshi; Thompson, James; Hill, Mark A.

2017-01-01

Migration of stem cells underpins the physiology of metazoan animals. For tissues to be maintained, stem cells and their progeny must migrate and differentiate in the correct positions. This need is even more acute after tissue damage by wounding or pathogenic infection. Inappropriate migration also underpins metastasis. Despite this, few mechanistic studies address stem cell migration during repair or homeostasis in adult tissues. Here, we present a shielded X-ray irradiation assay that allows us to follow stem cell migration in planarians. We demonstrate the use of this system to study the molecular control of stem cell migration and show that snail-1, snail-2 and zeb-1 EMT transcription factor homologs are necessary for cell migration to wound sites and for the establishment of migratory cell morphology. We also observed that stem cells undergo homeostatic migration to anterior regions that lack local stem cells, in the absence of injury, maintaining tissue homeostasis. This requires the polarity determinant notum. Our work establishes planarians as a suitable model for further in-depth study of the processes controlling stem cell migration in vivo. PMID:28893948

Root Border Cells and Their Role in Plant Defense.

PubMed

Hawes, Martha; Allen, Caitilyn; Turgeon, B Gillian; Curlango-Rivera, Gilberto; Minh Tran, Tuan; Huskey, David A; Xiong, Zhongguo

2016-08-04

Root border cells separate from plant root tips and disperse into the soil environment. In most species, each root tip can produce thousands of metabolically active cells daily, with specialized patterns of gene expression. Their function has been an enduring mystery. Recent studies suggest that border cells operate in a manner similar to mammalian neutrophils: Both cell types export a complex of extracellular DNA (exDNA) and antimicrobial proteins that neutralize threats by trapping pathogens and thereby preventing invasion of host tissues. Extracellular DNases (exDNases) of pathogens promote virulence and systemic spread of the microbes. In plants, adding DNase I to root tips eliminates border cell extracellular traps and abolishes root tip resistance to infection. Mutation of genes encoding exDNase activity in plant-pathogenic bacteria (Ralstonia solanacearum) and fungi (Cochliobolus heterostrophus) results in reduced virulence. The study of exDNase activities in plant pathogens may yield new targets for disease control.

Intracellular chloride ion concentration in differentiating neuronal cell and its role in growing neurite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Ken-ichi; Marunaka, Yoshinori; Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto 602-8566

Chloride ion (Cl{sup −}) is one of the most abundant anions in our body. Increasing evidence suggests that Cl{sup −} plays fundamental roles in various cellular functions. We have previously reported that electroneutral cation-chloride cotransporters, such as Na{sup +}-K{sup +}-2Cl{sup −} cotransporter 1 (NKCC1) and K{sup +}-Cl{sup −} cotransporter 1 (KCC1), are involved in neurite outgrowth during neuronal differentiation. In the present study, we studied if there is correlation between intracellular Cl{sup −} concentrations ([Cl{sup −}]{sub i}) and the length of growing neurites. We measured [Cl{sup −}]{sub i} in the cell body and growing neurite tips using halide-sensitive fluorescent dyemore » N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), revealing that [Cl{sup −}]{sub i} in the tip of growing neurite was higher than that in cell body in a single cell. Importantly, there was a significant positive correlation between the length of growing neurite and [Cl{sup −}]{sub i} in neurite tip. Bumtanide (BMT), an inhibitor of NKCC1, significantly inhibited neurite outgrowth and decreased [Cl{sup −}]{sub i} in neurite tip. The results obtained in the present study and our previous studies together strongly suggest that high [Cl{sup −}]{sub i} in neurite tip region is crucial for efficient neurite outgrowth. - Highlights: • Intracellular Cl{sup −} concentrations ([Cl{sup −}]{sub i}) in the tip of growing neurite is higher than that in cell body in a single cell. • There is a significant positive correlation between the length of growing neurite and [Cl{sup −}]{sub i} in neurite tip. • Bumetanide significantly inhibits neurite outgrowth and decreased [Cl{sup −}]{sub i} in neurite tip. • High [Cl{sup −}]{sub i} in neurite tip region is crucial for efficient neurite outgrowth.« less

Selectable-Tip Corrosion-Testing Electrochemical Cell

NASA Technical Reports Server (NTRS)

Lomness, Janice; Hintze, Paul

2008-01-01

The figure depicts aspects of an electrochemical cell for pitting- corrosion tests of material specimens. The cell is designed to generate a region of corrosion having a pit diameter determined by the diameter of a selectable tip. The average depth of corrosion is controlled by controlling the total electric charge passing through the cell in a test. The cell is also designed to produce minimal artifacts associated with crevice corrosion. There are three selectable tips, having diameters of 0.1 in. (0.254 cm), 0.3 in. (0.762 cm), and 0.6 in. (1.524 cm), respectively.

Mib1 contributes to persistent directional cell migration by regulating the Ctnnd1-Rac1 pathway.

PubMed

Mizoguchi, Takamasa; Ikeda, Shoko; Watanabe, Saori; Sugawara, Michiko; Itoh, Motoyuki

2017-10-31

Persistent directional cell migration is involved in animal development and diseases. The small GTPase Rac1 is involved in F-actin and focal adhesion dynamics. Local Rac1 activity is required for persistent directional migration, whereas global, hyperactivated Rac1 enhances random cell migration. Therefore, precise control of Rac1 activity is important for proper directional cell migration. However, the molecular mechanism underlying the regulation of Rac1 activity in persistent directional cell migration is not fully understood. Here, we show that the ubiquitin ligase mind bomb 1 (Mib1) is involved in persistent directional cell migration. We found that knockdown of MIB1 led to an increase in random cell migration in HeLa cells in a wound-closure assay. Furthermore, we explored novel Mib1 substrates for cell migration and found that Mib1 ubiquitinates Ctnnd1. Mib1-mediated ubiquitination of Ctnnd1 K547 attenuated Rac1 activation in cultured cells. In addition, we found that posterior lateral line primordium cells in the zebrafish mib1 ta52b mutant showed increased random migration and loss of directional F-actin-based protrusion formation. Knockdown of Ctnnd1 partially rescued posterior lateral line primordium cell migration defects in the mib1 ta52b mutant. Taken together, our data suggest that Mib1 plays an important role in cell migration and that persistent directional cell migration is regulated, at least in part, by the Mib1-Ctnnd1-Rac1 pathway. Published under the PNAS license.

Electron Transfer from Triplet State of TIPS-Pentacene Generated by Singlet Fission Processes to CH3NH3PbI3 Perovskite.

PubMed

Lee, Sangsu; Hwang, Daesub; Jung, Seok Il; Kim, Dongho

2017-02-16

To reveal the applicability of singlet fission processes in perovskite solar cell, we investigated electron transfer from TIPS-pentacene to CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite in film phase. Through the observation of the shorter fluorescence lifetime in TIPS-pentacene/MAPbI 3 perovskite bilayer film (5 ns) compared with pristine MAPbI 3 perovskite film (20 ns), we verified electron-transfer processes between TIPS-pentacene and MAPbI 3 perovskite. Furthermore, the observation of singlet fission processes, a faster decay rate, TIPS-pentacene cations, and the analysis of kinetic profiles of the intensity ratio between 500 and 525 nm in the TA spectra of the TIPS-pentacene/MAPbI 3 perovskite bilayer film indicate that electron transfer occurs from triplet state of TIPS-pentacene generated by singlet fission processes to MAPbI 3 perovskite conduction band. We believe that our results can provide useful information on the design of solar cells sensitized by singlet fission processes and pave the way for new types of perovskite solar cells.

The Mechanics of Single Cell and Collective Migration of Tumor Cells

PubMed Central

Lintz, Marianne; Muñoz, Adam; Reinhart-King, Cynthia A.

2017-01-01

Metastasis is a dynamic process in which cancer cells navigate the tumor microenvironment, largely guided by external chemical and mechanical cues. Our current understanding of metastatic cell migration has relied primarily on studies of single cell migration, most of which have been performed using two-dimensional (2D) cell culture techniques and, more recently, using three-dimensional (3D) scaffolds. However, the current paradigm focused on single cell movements is shifting toward the idea that collective migration is likely one of the primary modes of migration during metastasis of many solid tumors. Not surprisingly, the mechanics of collective migration differ significantly from single cell movements. As such, techniques must be developed that enable in-depth analysis of collective migration, and those for examining single cell migration should be adopted and modified to study collective migration to allow for accurate comparison of the two. In this review, we will describe engineering approaches for studying metastatic migration, both single cell and collective, and how these approaches have yielded significant insight into the mechanics governing each process. PMID:27814431

Cell Migration

PubMed Central

Trepat, Xavier; Chen, Zaozao; Jacobson, Ken

2015-01-01

Cell migration is fundamental to establishing and maintaining the proper organization of multicellular organisms. Morphogenesis can be viewed as a consequence, in part, of cell locomotion, from large-scale migrations of epithelial sheets during gastrulation, to the movement of individual cells during development of the nervous system. In an adult organism, cell migration is essential for proper immune response, wound repair, and tissue homeostasis, while aberrant cell migration is found in various pathologies. Indeed, as our knowledge of migration increases, we can look forward to, for example, abating the spread of highly malignant cancer cells, retarding the invasion of white cells in the inflammatory process, or enhancing the healing of wounds. This article is organized in two main sections. The first section is devoted to the single-cell migrating in isolation such as occurs when leukocytes migrate during the immune response or when fibroblasts squeeze through connective tissue. The second section is devoted to cells collectively migrating as part of multicellular clusters or sheets. This second type of migration is prevalent in development, wound healing, and in some forms of cancer metastasis. PMID:23720251

Impact of Tumor Cell Cytoskeleton Organization on Invasiveness and Migration: A Microchannel-Based Approach

PubMed Central

Rolli, Claudio G.; Seufferlein, Thomas; Kemkemer, Ralf; Spatz, Joachim P.

2010-01-01

Cell migration is a fundamental feature of the interaction of cells with their surrounding. The cell's stiffness and ability to deform itself are two major characteristics that rule migration behavior especially in three-dimensional tissue. We simulate this situation making use of a micro-fabricated migration chip to test the active invasive behavior of pancreatic cancer cells (Panc-1) into narrow channels. At a channel width of 7 µm cell migration through the channels was significantly impeded due to size exclusion. A striking increase in cell invasiveness was observed once the cells were treated with the bioactive lipid sphingosylphosphorylcholine (SPC) that leads to a reorganization of the cell's keratin network, an enhancement of the cell's deformability, and also an increase in the cell's migration speed on flat surfaces. The migration speed of the highly deformed cells inside the channels was three times higher than of cells on flat substrates but was not affected upon SPC treatment. Cells inside the channels migrated predominantly by smooth sliding while maintaining constant cell length. In contrast, cells on adhesion mediating narrow lines moved in a stepwise way, characterized by fluctuations in cell length. Taken together, with our migration chip we demonstrate that the dimensionality of the environment strongly affects the migration phenotype and we suggest that the spatial cytoskeletal keratin organization correlates with the tumor cell's invasive potential. PMID:20090950

Evidence for tension-based regulation of Drosophila MAL and SRF during invasive cell migration.

PubMed

Somogyi, Kálmán; Rørth, Pernille

2004-07-01

Cells migrating through a tissue exert force via their cytoskeleton and are themselves subject to tension, but the effects of physical forces on cell behavior in vivo are poorly understood. Border cell migration during Drosophila oogenesis is a useful model for invasive cell movement. We report that this migration requires the activity of the transcriptional factor serum response factor (SRF) and its cofactor MAL-D and present evidence that nuclear accumulation of MAL-D is induced by cell stretching. Border cells that cannot migrate lack nuclear MAL-D but can accumulate it if they are pulled by other migrating cells. Like mammalian MAL, MAL-D also responds to activated Diaphanous, which affects actin dynamics. MAL-D/SRF activity is required to build a robust actin cytoskeleton in the migrating cells; mutant cells break apart when initiating migration. Thus, tension-induced MAL-D activity may provide a feedback mechanism for enhancing cytoskeletal strength during invasive migration.

Cytoglobin inhibits migration through PI3K/AKT/mTOR pathway in fibroblast cells.

PubMed

Demirci, Selami; Doğan, Ayşegül; Apdik, Hüseyin; Tuysuz, Emre Can; Gulluoglu, Sukru; Bayrak, Omer Faruk; Şahin, Fikrettin

2018-01-01

Cell proliferation and migration are crucial in many physiological processes including development, cancer, tissue repair, and wound healing. Cell migration is regulated by several signaling molecules. Identification of genes related to cell migration is required to understand molecular mechanism of non-healing chronic wounds which is a major concern in clinics. In the current study, the role of cytoglobin (CYGB) gene in fıbroblast cell migration and proliferation was described. L929 mouse fibroblast cells were transduced with lentiviral particles for CYGB and GFP, and analyzed for cell proliferation and migration ability. Fibroblast cells overexpressing CYGB displayed decreased cell proliferation, colony formation capacity, and cell migration. Phosphorylation levels of mTOR and two downstream effectors S6 and 4E-BP1 which take part in PI3K/AKT/mTOR signaling declined in CYGB-overexpressing cells. Microarray analysis indicated that CYGB overexpression leads to downregulation of cell proliferation, migration, and tumor growth associated genes in L929 cell line. This study demonstrated the role of CYGB in fibroblast cell motility and proliferation. CYGB could be a promising candidate for further studies as a potential target for diseases related to cell migration such as cancer and chronic wound treatment.

Customized atomic force microscopy probe by focused-ion-beam-assisted tip transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Andrew; Butte, Manish J., E-mail: manish.butte@stanford.edu

2014-08-04

We present a technique for transferring separately fabricated tips onto tipless atomic force microscopy (AFM) cantilevers, performed using focused ion beam-assisted nanomanipulation. This method addresses the need in scanning probe microscopy for certain tip geometries that cannot be achieved by conventional lithography. For example, in probing complex layered materials or tall biological cells using AFM, a tall tip with a high-aspect-ratio is required to avoid artifacts caused by collisions of the tip's sides with the material being probed. We show experimentally that tall (18 μm) cantilever tips fabricated by this approach reduce squeeze-film damping, which fits predictions from hydrodynamic theory, andmore » results in an increased quality factor (Q) of the fundamental flexural mode. We demonstrate that a customized tip's well-defined geometry, tall tip height, and aspect ratio enable improved measurement of elastic moduli by allowing access to low-laying portions of tall cells (T lymphocytes). This technique can be generally used to attach tips to any micromechanical device when conventional lithography of tips cannot be accomplished.« less

Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes*

PubMed Central

Park, Dayoung; Brune, Kristin A.; Mitra, Anupam; Marusina, Alina I.; Maverakis, Emanual; Lebrilla, Carlito B.

2015-01-01

Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract. PMID:26355101

Regulation of Histone Acetyltransferase TIP60 Function by Histone Deacetylase 3

PubMed Central

Yi, Jingjie; Huang, Xiangyang; Yang, Yuxia; Zhu, Wei-Guo; Gu, Wei; Luo, Jianyuan

2014-01-01

The key member of the MOZ (monocyticleukaemia zinc finger protein), Ybf2/Sas3, Sas2, and TIP60 acetyltransferases family, Tat-interactive protein, 60 kD (TIP60), tightly modulates a wide array of cellular processes, including chromatin remodeling, gene transcription, apoptosis, DNA repair, and cell cycle arrest. The function of TIP60 can be regulated by SIRT1 through deacetylation. Here we found that TIP60 can also be functionally regulated by HDAC3. We identified six lysine residues as its autoacetylation sites. Mutagenesis of these lysines to arginines completely abolishes the autoacetylation of TIP60. Overexpression of HDAC3 increases TIP60 ubiquitination levels. However, unlike SIRT1, HDAC3 increased the half-life of TIP60. Further study found that HDAC3 colocalized with TIP60 both in the nucleus and the cytoplasm, which could be the reason why HDAC3 can stabilize TIP60. The deacetylation of TIP60 by both SIRT1 and HDAC3 reduces apoptosis induced by DNA damage. Knockdown of HDAC3 in cells increased TIP60 acetylation levels and increased apoptosis after DNA damage. Together, our findings provide a better understanding of TIP60 regulation mechanisms, which is a significant basis for further studies of its cellular functions. PMID:25301942

CNS angiogenesis and barriergenesis occur simultaneously.

PubMed

Umans, Robyn A; Henson, Hannah E; Mu, Fangzhou; Parupalli, Chaithanyarani; Ju, Bensheng; Peters, Jennifer L; Lanham, Kevin A; Plavicki, Jessica S; Taylor, Michael R

2017-05-15

The blood-brain barrier (BBB) plays a vital role in the central nervous system (CNS). A comprehensive understanding of BBB development has been hampered by difficulties in observing the differentiation of brain endothelial cells (BECs) in real-time. Here, we generated two transgenic zebrafish line, Tg(glut1b:mCherry) and Tg(plvap:EGFP), to serve as in vivo reporters of BBB development. We showed that barriergenesis (i.e. the induction of BEC differentiation) occurs immediately as endothelial tips cells migrate into the brain parenchyma. Using the Tg(glut1b:mCherry) transgenic line, we performed a genetic screen and identified a zebrafish mutant with a nonsense mutation in gpr124, a gene known to play a role in CNS angiogenesis and BBB development. We also showed that our transgenic plvap:EGFP line, a reporter of immature brain endothelium, is initially expressed in newly formed brain endothelial cells, but subsides during BBB maturation. Our results demonstrate the ability to visualize the in vivo differentiation of brain endothelial cells into the BBB phenotype and establish that CNS angiogenesis and barriergenesis occur simultaneously. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Epithelial-mesenchymal transition transcription factors control pluripotent adult stem cell migration in vivo in planarians.

PubMed

Abnave, Prasad; Aboukhatwa, Ellen; Kosaka, Nobuyoshi; Thompson, James; Hill, Mark A; Aboobaker, A Aziz

2017-10-01

Migration of stem cells underpins the physiology of metazoan animals. For tissues to be maintained, stem cells and their progeny must migrate and differentiate in the correct positions. This need is even more acute after tissue damage by wounding or pathogenic infection. Inappropriate migration also underpins metastasis. Despite this, few mechanistic studies address stem cell migration during repair or homeostasis in adult tissues. Here, we present a shielded X-ray irradiation assay that allows us to follow stem cell migration in planarians. We demonstrate the use of this system to study the molecular control of stem cell migration and show that snail-1 , snail-2 and zeb-1 EMT transcription factor homologs are necessary for cell migration to wound sites and for the establishment of migratory cell morphology. We also observed that stem cells undergo homeostatic migration to anterior regions that lack local stem cells, in the absence of injury, maintaining tissue homeostasis. This requires the polarity determinant notum Our work establishes planarians as a suitable model for further in-depth study of the processes controlling stem cell migration in vivo . © 2017. Published by The Company of Biologists Ltd.

Modeling keratinocyte wound healing dynamics: Cell-cell adhesion promotes sustained collective migration.

PubMed

Nardini, John T; Chapnick, Douglas A; Liu, Xuedong; Bortz, David M

2016-07-07

The in vitro migration of keratinocyte cell sheets displays behavioral and biochemical similarities to the in vivo wound healing response of keratinocytes in animal model systems. In both cases, ligand-dependent Epidermal Growth Factor Receptor (EGFR) activation is sufficient to elicit collective cell migration into the wound. Previous mathematical modeling studies of in vitro wound healing assays assume that physical connections between cells have a hindering effect on cell migration, but biological literature suggests a more complicated story. By combining mathematical modeling and experimental observations of collectively migrating sheets of keratinocytes, we investigate the role of cell-cell adhesion during in vitro keratinocyte wound healing assays. We develop and compare two nonlinear diffusion models of the wound healing process in which cell-cell adhesion either hinders or promotes migration. Both models can accurately fit the leading edge propagation of cell sheets during wound healing when using a time-dependent rate of cell-cell adhesion strength. The model that assumes a positive role of cell-cell adhesion on migration, however, is robust to changes in the leading edge definition and yields a qualitatively accurate density profile. Using RNAi for the critical adherens junction protein, α-catenin, we demonstrate that cell sheets with wild type cell-cell adhesion expression maintain migration into the wound longer than cell sheets with decreased cell-cell adhesion expression, which fails to exhibit collective migration. Our modeling and experimental data thus suggest that cell-cell adhesion promotes sustained migration as cells pull neighboring cells into the wound during wound healing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Public Health and Mental Health Implications of Environmentally Induced Forced Migration.

PubMed

Shultz, James M; Rechkemmer, Andreas; Rai, Abha; McManus, Katherine T

2018-03-28

ABSTRACTClimate change is increasingly forcing population displacement, better described by the phrase environmentally induced forced migration. Rising global temperatures, rising sea levels, increasing frequency and severity of natural disasters, and progressive depletion of life-sustaining resources are among the drivers that stimulate population mobility. Projections forecast that current trends will rapidly accelerate. This will lead to an estimated 200 million climate migrants by the year 2050 and create dangerous tipping points for public health and security.Among the public health consequences of climate change, environmentally induced forced migration is one of the harshest and most harmful outcomes, always involving a multiplicity of profound resource and social losses and frequently exposing migrants to trauma and violence. Therefore, one particular aspect of forced migration, the effects of population displacement on mental health and psychosocial functioning, deserves dedicated focus. Multiple case examples are provided to elucidate this theme. (Disaster Med Public Health Preparedness. 2018;page 1 of 7).

Probing the compressibility of tumor cell nuclei by combined atomic force-confocal microscopy

NASA Astrophysics Data System (ADS)

Krause, Marina; te Riet, Joost; Wolf, Katarina

2013-12-01

The cell nucleus is the largest and stiffest organelle rendering it the limiting compartment during migration of invasive tumor cells through dense connective tissue. We here describe a combined atomic force microscopy (AFM)-confocal microscopy approach for measurement of bulk nuclear stiffness together with simultaneous visualization of the cantilever-nucleus contact and the fate of the cell. Using cantilevers functionalized with either tips or beads and spring constants ranging from 0.06-10 N m-1, force-deformation curves were generated from nuclear positions of adherent HT1080 fibrosarcoma cell populations at unchallenged integrity, and a nuclear stiffness range of 0.2 to 2.5 kPa was identified depending on cantilever type and the use of extended fitting models. Chromatin-decondensating agent trichostatin A (TSA) induced nuclear softening of up to 50%, demonstrating the feasibility of our approach. Finally, using a stiff bead-functionalized cantilever pushing at maximal system-intrinsic force, the nucleus was deformed to 20% of its original height which after TSA treatment reduced further to 5% remaining height confirming chromatin organization as an important determinant of nuclear stiffness. Thus, combined AFM-confocal microscopy is a feasible approach to study nuclear compressibility to complement concepts of limiting nuclear deformation in cancer cell invasion and other biological processes.

Leader cells regulate collective cell migration via Rac activation in the downstream signaling of integrin β1 and PI3K

PubMed Central

Yamaguchi, Naoya; Mizutani, Takeomi; Kawabata, Kazushige; Haga, Hisashi

2015-01-01

Collective cell migration plays a crucial role in several biological processes, such as embryonic development, wound healing, and cancer metastasis. Here, we focused on collectively migrating Madin-Darby Canine Kidney (MDCK) epithelial cells that follow a leader cell on a collagen gel to clarify the mechanism of collective cell migration. First, we removed a leader cell from the migrating collective with a micromanipulator. This then caused disruption of the cohesive migration of cells that followed in movement, called “follower” cells, which showed the importance of leader cells. Next, we observed localization of active Rac, integrin β1, and PI3K. These molecules were clearly localized in the leading edge of leader cells, but not in follower cells. Live cell imaging using active Rac and active PI3K indicators was performed to elucidate the relationship between Rac, integrin β1, and PI3K. Finally, we demonstrated that the inhibition of these molecules resulted in the disruption of collective migration. Our findings not only demonstrated the significance of a leader cell in collective cell migration, but also showed that Rac, integrin β1, and PI3K are upregulated in leader cells and drive collective cell migration. PMID:25563751

Leader cells regulate collective cell migration via Rac activation in the downstream signaling of integrin β1 and PI3K.

PubMed

Yamaguchi, Naoya; Mizutani, Takeomi; Kawabata, Kazushige; Haga, Hisashi

2015-01-07

Collective cell migration plays a crucial role in several biological processes, such as embryonic development, wound healing, and cancer metastasis. Here, we focused on collectively migrating Madin-Darby Canine Kidney (MDCK) epithelial cells that follow a leader cell on a collagen gel to clarify the mechanism of collective cell migration. First, we removed a leader cell from the migrating collective with a micromanipulator. This then caused disruption of the cohesive migration of cells that followed in movement, called "follower" cells, which showed the importance of leader cells. Next, we observed localization of active Rac, integrin β1, and PI3K. These molecules were clearly localized in the leading edge of leader cells, but not in follower cells. Live cell imaging using active Rac and active PI3K indicators was performed to elucidate the relationship between Rac, integrin β1, and PI3K. Finally, we demonstrated that the inhibition of these molecules resulted in the disruption of collective migration. Our findings not only demonstrated the significance of a leader cell in collective cell migration, but also showed that Rac, integrin β1, and PI3K are upregulated in leader cells and drive collective cell migration.

Technical Advance: New in vitro method for assaying the migration of primary B cells using an endothelial monolayer as substrate.

PubMed

Stewart-Hutchinson, Phillip J; Szasz, Taylor P; Jaeger, Emily R; Onken, Michael D; Cooper, John A; Morley, Sharon Celeste

2017-09-01

Migration of B cells supports their development and recruitment into functional niches. Therefore, defining factors that control B cell migration will lead to a better understanding of adaptive immunity. In vitro cell migration assays with B cells have been limited by poor adhesion of cells to glass coated with adhesion molecules. We have developed a technique using monolayers of endothelial cells as the substrate for B cell migration and used this technique to establish a robust in vitro assay for B cell migration. We use TNF-α to up-regulate surface expression of the adhesion molecule VCAM-1 on endothelial cells. The ligand VLA-4 is expressed on B cells, allowing them to interact with the endothelial monolayer and migrate on its surface. We tested our new method by examining the role of L-plastin (LPL), an F-actin-bundling protein, in B cell migration. LPL-deficient (LPL -/- ) B cells displayed decreased speed and increased arrest coefficient compared with wild-type (WT) B cells, following chemokine stimulation. However, the confinement ratios for WT and LPL -/- B cells were similar. Thus, we demonstrate how the use of endothelial monolayers as a substrate will support future interrogation of molecular pathways essential to B cell migration. © Society for Leukocyte Biology.

Collective cell migration in development

PubMed Central

Scarpa, Elena

2016-01-01

During embryonic development, tissues undergo major rearrangements that lead to germ layer positioning, patterning, and organ morphogenesis. Often these morphogenetic movements are accomplished by the coordinated and cooperative migration of the constituent cells, referred to as collective cell migration. The molecular and biomechanical mechanisms underlying collective migration of developing tissues have been investigated in a variety of models, including border cell migration, tracheal branching, blood vessel sprouting, and the migration of the lateral line primordium, neural crest cells, or head mesendoderm. Here we review recent advances in understanding collective migration in these developmental models, focusing on the interaction between cells and guidance cues presented by the microenvironment and on the role of cell–cell adhesion in mechanical and behavioral coupling of cells within the collective. PMID:26783298

Cell-cell interactions mediate cytoskeleton organization and collective endothelial cell chemotaxis.

PubMed

Shamloo, Amir

2014-09-01

This study investigates the role of cell-cell and cell-ligand interactions in cytoskeleton organization of endothelial cells (ECs) and their directional migration within a microfluidic device. The migration of ECs in response to a biochemical factor was studied. Mathematical analysis of the cell migration pathways and cellular cytoskeleton revealed that directional migration, migration persistence length, migration speed, and cytoskeletal stress fiber alignment can be mediated by the level of cell contacts as well as the presence or absence of a biochemical polarizing factor. It was shown that in the presence of a biochemical polarizing factor, higher cell density and more frequent cell contacts has a reinforcing effect on collective cell chemotaxis. In contrast, in the absence of a polarizing factor, high cell density can decrease or suppress the ability of the cells to migrate. Also, the correlation of actin stress fiber organization and alignment with directional migration of ECs was investigated. It was shown that in the presence of a biochemical polarizing factor, stress fibers within the cytoskeleton of ECs can be significantly aligned parallel to the gradient direction when the cells have higher level of contacts. The results also show that the organization and alignment of actin stress fibers is mediated by cell adhesion junctions during collective cell migration and introduce cell-cell interactions as a key factor during collective cell chemotaxis. © 2014 Wiley Periodicals, Inc.

Toddler signaling regulates mesodermal cell migration downstream of Nodal signaling

PubMed Central

Norris, Megan L; Pauli, Andrea; Gagnon, James A; Lord, Nathan D; Rogers, Katherine W; Mosimann, Christian; Zon, Leonard I

2017-01-01

Toddler/Apela/Elabela is a conserved secreted peptide that regulates mesendoderm development during zebrafish gastrulation. Two non-exclusive models have been proposed to explain Toddler function. The ‘specification model’ postulates that Toddler signaling enhances Nodal signaling to properly specify endoderm, whereas the ‘migration model’ posits that Toddler signaling regulates mesendodermal cell migration downstream of Nodal signaling. Here, we test key predictions of both models. We find that in toddler mutants Nodal signaling is initially normal and increasing endoderm specification does not rescue mesendodermal cell migration. Mesodermal cell migration defects in toddler mutants result from a decrease in animal pole-directed migration and are independent of endoderm. Conversely, endodermal cell migration defects are dependent on a Cxcr4a-regulated tether of the endoderm to mesoderm. These results suggest that Toddler signaling regulates mesodermal cell migration downstream of Nodal signaling and indirectly affects endodermal cell migration via Cxcr4a-signaling. PMID:29117894

Alleviation effect of alginate-derived oligosaccharides on Vicia faba root tip cells damaged by cadmium.

PubMed

Ma, L J; Zhang, Y; Bu, N; Wang, S H

2010-02-01

Cadmium has been shown to prevent Vicia faba growth by inhibiting cell mitosis. In this study we investigated the role of Alginate-derived Oligosaccharides (ADO) in alleviating Vicia faba root tip cells damaged by 6 and 8 mg L(-1) CdCl2. Micronucleus assay and chromosomal aberration assay were used to determine mitotic index, micronucleus frequency and chromosomal aberration frequency. The results showed that micronucleus frequency of Vicia faba root tip cells was inhibited under all the ADO concentrations. Especially, the inhibition ratio of 0.125% ADO highly reached 66.11 and 67.17% in 6 and 8 mg L(-1) CdCl2, respectively. Furthermore, the mitotic index increased (p < 0.05) and chromosomal aberration frequency decreased (p < 0.05) under all the ADO concentrations. This indicated that ADO had a significant alleviation effect on Vicia faba root tip cells damaged by cadmium.

Cell proliferation within small intestinal crypts is the principal driving force for cell migration on villi

PubMed Central

Parker, Aimee; Maclaren, Oliver J.; Fletcher, Alexander G.; Muraro, Daniele; Kreuzaler, Peter A.; Byrne, Helen M.; Maini, Philip K.; Watson, Alastair J. M.; Pin, Carmen

2017-01-01

The functional integrity of the intestinal epithelial barrier relies on tight coordination of cell proliferation and migration, with failure to regulate these processes resulting in disease. It is not known whether cell proliferation is sufficient to drive epithelial cell migration during homoeostatic turnover of the epithelium. Nor is it known precisely how villus cell migration is affected when proliferation is perturbed. Some reports suggest that proliferation and migration may not be related while other studies support a direct relationship. We used established cell-tracking methods based on thymine analog cell labeling and developed tailored mathematical models to quantify cell proliferation and migration under normal conditions and when proliferation is reduced and when it is temporarily halted. We found that epithelial cell migration velocities along the villi are coupled to cell proliferation rates within the crypts in all conditions. Furthermore, halting and resuming proliferation results in the synchronized response of cell migration on the villi. We conclude that cell proliferation within the crypt is the primary force that drives cell migration along the villus. This methodology can be applied to interrogate intestinal epithelial dynamics and characterize situations in which processes involved in cell turnover become uncoupled, including pharmacological treatments and disease models.—Parker, A., Maclaren, O. J., Fletcher, A. G., Muraro, D., Kreuzaler, P. A., Byrne, H. M., Maini, P. K., Watson, A. J. M., Pin, C. Cell proliferation within small intestinal crypts is the principal driving force for cell migration on villi. PMID:27811059

Balancing Cell Migration with Matrix Degradation Enhances Gene Delivery to Cells Cultured Three-Dimensionally Within Hydrogels

PubMed Central

Shepard, Jaclyn A.; Huang, Alyssa; Shikanova, Ariella; Shea, Lonnie D.

2010-01-01

In regenerative medicine, hydrogels are employed to fill defects and support the infiltration of cells that can ultimately regenerate tissue. Gene delivery within hydrogels targeting infiltrating cells has the potential to promote tissue formation, but the delivery efficiency of nonviral vectors within hydrogels is low hindering their applicability in tissue regeneration. To improve their functionality, we have conducted a mechanistic study to investigate the contribution of cell migration and matrix degradation on gene delivery. In this report, lipoplexes were entrapped within hydrogels based on poly(ethylene glycol) (PEG) crosslinked with peptides containing matrix metalloproteinase degradable sequences. The mesh size of these hydrogels is substantially less than the size of the entrapped lipoplexes, which can function to retain vectors. Cell migration and transfection were simultaneously measured within hydrogels with varying density of cell adhesion sites (Arg-Gly-Asp peptides) and solids content. Increasing RGD density increased expression levels up to 100-fold, while greater solids content sustained expression levels for 16 days. Increasing RGD density and decreasing solids content increased cell migration, which indicates expression levels increase with increased cell migration. Initially exposing cells to vector resulted in transient expression that declined after 2 days, verifying the requirement of migration to sustain expression. Transfected cells were predominantly located within the population of migrating cells for hydrogels that supported cell migration. Although the small mesh size retained at least 70% of the lipoplexes in the absence of cells after 32 days, the presence of cells decreased retention to 10% after 16 days. These results indicate that vectors retained within hydrogels contact migrating cells, and that persistent cell migration can maintain elevated expression levels. Thus matrix degradation and cell migration are fundamental design parameters for maximizing gene delivery from hydrogels. PMID:20450944

Living cell manipulation, manageable sampling, and shotgun picoliter electrospray mass spectrometry for profiling metabolites.

PubMed

Gholipour, Yousef; Erra-Balsells, Rosa; Hiraoka, Kenzo; Nonami, Hiroshi

2013-02-01

A modified cell pressure probe and an online Orbitrap mass spectrometer were used to sample in situ plant single cells without any additional manipulation. The cell pressure probe, a quartz capillary tip filled with an oil mixture, was penetrated to various depths into parenchyma cells of tulip bulb scale, followed by a hydraulic continuity test to determine the exact location of the tip inside target cells. The operation was conducted under a digital microscope, and the capillary tip was photographed to calculate the volume of the cell sap sucked. The cell sap sample was then directly nebulized/ionized under high-voltage conditions at the entrance of the mass spectrometer. Several sugars, amino acids, organic acids, vitamins, fatty acids, and secondary metabolites were detected. Because picoliter solutions can be accurately handled and measured, known volumes of standard solutions can be added to cell sap samples inside the capillary tip to be used as references for metabolite characterization and relative quantitation. The high precision and sensitivity of the cell pressure probe and Orbitrap mass spectrometer allow for the manipulation and analysis of both femtoliter cell sap samples and standard solutions. Copyright © 2012 Elsevier Inc. All rights reserved.

Morphogenetic changes occurring in the regenerating newt tail under changed gravity conditions

NASA Astrophysics Data System (ADS)

Radugina, Elena A.; Grigoryan, Eleonora N.; Dvorochkin, Natasha; Almeida, Eduardo

2012-07-01

It is widely accepted that gravity greatly affects animal physiology, development, and alters gene expression. Recently it became apparent that it can also affect tissue morphogenesis. In our work, we developed special laboratory conditions that allow us to produce the gravity-dependent alterations in tail regenerates of the newt Pleurodeles waltl. We examined the dynamic morphogenetic changes during 50-day tail regeneration using computer morphometric analysis. Changes that we observed under these conditions were comparable with those found earlier in our spaceflight experiments. The newts kept in aquarium deep water (low g) after 1/3 tail amputation developed normal lanceolate regenerates. In contrast, the animals that stayed on the moist mat (1g) developed tail regenerates curved ventrally, with tips almost touching the mat. The similar results were obtained with a 12-day centrifugation at 2g. The study of the regenerate morphology in low g, 1g, and 2g animal groups allowed us to determine the stage at which the morphological changes in regenerates become apparent, and to detect the main morphological events associated with the development of tail curve, such as bending of ependymal tube and reorientation of the forming cartilage. We describe cellular processes foregoing observed tissue morphogenetic changes, such as cell migration, condensation in cell population, and unequal proliferation in different areas of epidermis and blastema. Cell proliferation in epidermis and blastema of tails regenerated under the conditions of different gravitational load was evaluated by BrdU assay. In 1g newts, cell proliferation increased within the dorso-apical region of the regenerates compared with that in low g group. These results provide us with a valuable insight into the regenerative tissue homostasis that involves cell division, cell death, and migration in the newt regenerating tail. In addition, these findings could provide us with better understanding of the mechanisms mediating morphogenetic response of regenerating tissues to the modified gravity vector.

Towards force spectroscopy of single tip-link bonds

NASA Astrophysics Data System (ADS)

Koussa, Mounir A.; Sotomayor, Marcos; Wong, Wesley P.; Corey, David P.

2015-12-01

Inner-ear mechanotransduction relies on tip links, fine protein filaments made of cadherin-23 and protocadherin-15 that convey tension to mechanosensitive channels at the tips of hair-cell stereocilia. The tip-link cadherins are thought to form a heterotetrameric complex, with two cadherin-23 molecules forming the upper part of the filament and two protocadherin-15 molecules forming the lower end. The interaction between cadherin-23 and protocadherin-15 is mediated by their N-terminal tips. Missense mutations that modify the interaction interface impair binding and lead to deafness. Molecular dynamics simulations predict that the tip-link bond is mechanically strong enough to withstand forces in hair cells, but its experimentally determined strength is unknown. We have developed molecular tools to facilitate single-molecule force spectroscopy on the tip link bond. Self-assembling DNA nanoswitches are functionalized with the interacting tips of cadherin-23 and protocadherin-15 using the enzyme sortase under conditions that preserve protein function. These tip link nanoswitches are designed to provide a signature force-extension profile. This molecular signature should allow us to identify single-molecule rupture events in pulling experiments.

Calcium in Gravitropism of the Moss Pohlia nutans (Hedw.) Lindb. protonemata

NASA Astrophysics Data System (ADS)

Khorkavtsiv, O. Ya; Demkiv, O. T.; Khorkavtsiv, Ya. D.

Protonemata of mosses of Pohlia nutans grow both by extension and division of single apical cells which are negatively gravitropic in darkness. The fluorescence of Ca2+ increased in the tip of apical cells from the first hours of gravitropism stimulation. Cytochemical investigations confirmed the existence of a well pronounced tip-to-base Ca2+-gradient, its formation being favoured by localization of calcium influx in the tip of the apical cell. Measurement of the cytochemical reaction intensity showed that the level of Ca2+-ATFase activity is low in apex and increases towards the base of the apical cell. The gravitropic protonemata and filaments which grew on the clinostat showed similar distributions of the Ca2+ and Ca2+-ATFase activity along the apical cell axis. Thus, these data demonstrate that growing apical cells of gravitropic protonemata have a high tip-to-base Ca2+ gradient, the Ca2+ transport being afforded by Ca2+-ATFase.

Cell migration or cytokinesis and proliferation? – Revisiting the “go or grow” hypothesis in cancer cells in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garay, Tamás; Juhász, Éva; Molnár, Eszter

The mortality of patients with solid tumors is mostly due to metastasis that relies on the interplay between migration and proliferation. The “go or grow” hypothesis postulates that migration and proliferation spatiotemporally excludes each other. We evaluated this hypothesis on 35 cell lines (12 mesothelioma, 13 melanoma and 10 lung cancer) on both the individual cell and population levels. Following three-day-long videomicroscopy, migration, proliferation and cytokinesis-length were quantified. We found a significantly higher migration in mesothelioma cells compared to melanoma and lung cancer while tumor types did not differ in mean proliferation or duration of cytokinesis. Strikingly, we found inmore » melanoma and lung cancer a significant positive correlation between mean proliferation and migration. Furthermore, non-dividing melanoma and lung cancer cells displayed slower migration. In contrast, in mesothelioma there were no such correlations. Interestingly, negative correlation was found between cytokinesis-length and migration in melanoma. FAK activation was higher in melanoma cells with high motility. We demonstrate that the cancer cells studied do not defer proliferation for migration. Of note, tumor cells from various organ systems may differently regulate migration and proliferation. Furthermore, our data is in line with the observation of pathologists that highly proliferative tumors are often highly invasive. - Highlights: • We investigated the “go or grow” hypothesis in human cancer cells in vitro. • Proliferation and migration positively correlate in melanoma and lung cancer cells. • Duration of cytokinesis and migration shows inverse correlation. • Increased FAK activation is present in highly motile melanoma cells.« less

Fine Tuning Cell Migration by a Disintegrin and Metalloproteinases

PubMed Central

Theodorou, K.

2017-01-01

Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity. PMID:28260841

A simple non-perturbing cell migration assay insensitive to proliferation effects.

PubMed

Glenn, Honor L; Messner, Jacob; Meldrum, Deirdre R

2016-08-18

Migration is a fundamental cellular behavior that plays an indispensable role in development and homeostasis, but can also contribute to pathology such as cancer metastasis. Due to its relevance to many aspects of human health, the ability to accurately measure cell migration is of broad interest, and numerous approaches have been developed. One of the most commonly employed approaches, because of its simplicity and throughput, is the exclusion zone assay in which cells are allowed to migrate into an initially cell-free region. A major drawback of this assay is that it relies on simply counting cells in the exclusion zone and therefore cannot distinguish the effects of proliferation from migration. We report here a simple modification to the exclusion zone migration assay that exclusively measures cell migration and is not affected by proliferation. This approach makes use of a lineage-tracing vital stain that is retained through cell generations and effectively reads out migration relative to the original, parental cell population. This modification is simple, robust, non-perturbing, and inexpensive. We validate the method in a panel of cell lines under conditions that inhibit or promote migration and demonstrate its use in normal and cancer cell lines as well as primary cells.

Human Papillomavirus Type 18 E6 Protein Binds the Cellular PDZ Protein TIP-2/GIPC, Which Is Involved in Transforming Growth Factor β Signaling and Triggers Its Degradation by the Proteasome

PubMed Central

Favre-Bonvin, Arnaud; Reynaud, Caroline; Kretz-Remy, Carole; Jalinot, Pierre

2005-01-01

Several viral proteins expressed by DNA or RNA transforming viruses have the particular property of binding via their C-terminal end to various cellular proteins with PDZ domains. This study is focused on the PDZ protein TIP-2/GIPC, which was originally identified in two-hybrid screens performed with two different baits: the human T-cell leukemia virus type 1 Tax oncoprotein and the regulator of G signaling RGS-GAIP. Further studies have shown that TIP-2/GIPC is also able to associate with the cytoplasmic domains of various transmembrane proteins. In this report we show that TIP-2/GIPC interacts with the E6 protein of human papillomavirus type 18 (HPV-18). This event triggers polyubiquitination and proteasome-mediated degradation of the cellular protein. In agreement with this observation, silencing of E6 by RNA interference in HeLa cells causes an increase in the intracellular TIP-2/GIPC level. This PDZ protein has been previously found to be involved in transforming growth factor β (TGF-β) signaling by favoring expression of the TGF-β type III receptor at the cell membrane. In line with this activity of TIP-2/GIPC, we observed that depletion of this protein in HeLa cells hampers induction of the Id3 gene by TGF-β treatment and also diminishes the antiproliferative effect of this cytokine. Conversely, silencing of E6 increases the expression of Id3 and blocks proliferation of HeLa cells. These results support the notion that HPV-18 E6 renders cells less sensitive to the cytostatic effect of TGF-β by lowering the intracellular amount of TIP-2/GIPC. PMID:15767424

Single-cell isolation by a modular single-cell pipette for RNA-sequencing.

PubMed

Zhang, Kai; Gao, Min; Chong, Zechen; Li, Ying; Han, Xin; Chen, Rui; Qin, Lidong

2016-11-29

Single-cell transcriptome sequencing highly requires a convenient and reliable method to rapidly isolate a live cell into a specific container such as a PCR tube. Here, we report a modular single-cell pipette (mSCP) consisting of three modular components, a SCP-Tip, an air-displacement pipette (ADP), and ADP-Tips, that can be easily assembled, disassembled, and reassembled. By assembling the SCP-Tip containing a hydrodynamic trap, the mSCP can isolate single cells from 5-10 cells per μL of cell suspension. The mSCP is compatible with microscopic identification of captured single cells to finally achieve 100% single-cell isolation efficiency. The isolated live single cells are in submicroliter volumes and well suitable for single-cell PCR analysis and RNA-sequencing. The mSCP possesses merits of convenience, rapidness, and high efficiency, making it a powerful tool to isolate single cells for transcriptome analysis.

A tip-localized RhoGAP controls cell polarity by globally inhibiting Rho GTPase at the cell apex.

PubMed

Hwang, Jae-Ung; Vernoud, Vanessa; Szumlanski, Amy; Nielsen, Erik; Yang, Zhenbiao

2008-12-23

Highly elongated eukaryotic cells (e.g., neuronal axons, fungal hyphae, and pollen tubes) are generated through continuous apically restricted growth (tip growth), which universally requires tip-localized Rho GTPases. We used the oscillating pollen tube as a model system to determine the function and regulation of Rho GTPases in tip growth. Our previous work showed that the spatiotemporal dynamics of the apical cap of the activated Rho-like GTPase from Plant 1 (ROP1) are critical for tip growth in pollen tubes. However, the underlying mechanism for the generation and maintenance of this dynamic apical cap is poorly understood. A screen for mutations that enhance ROP1-overexpression-induced depolarization of pollen-tube growth identified REN1 (ROP1 enhancer 1) in Arabidopsis, whose null mutations turn elongated pollen tubes into bulbous cells. REN1 encodes a novel Rho GTPase-activating protein (RhoGAP) required for restricting the ROP1 activity to the pollen-tube tip. REN1 was localized to exocytic vesicles accumulated in the pollen-tube apex, as well as to the apical plasma membrane at the site of ROP1 activation. The apical localization of REN1 and its function in controlling growth polarity was compromised by disruption of ROP1-dependent F-actin and vesicular trafficking, which indicates that REN1 targeting and function is regulated by ROP1 downstream signaling. Our findings suggest that the REN1 RhoGAP controls a negative-feedback-based global inhibition of ROP1. This function provides a critical self-organizing mechanism, by which ROP signaling is spatially limited to the growth site and temporally oscillates during continuous tip growth. Similar spatiotemporal control of Rho GTPase signaling may also play an important role in cell-polarity control in other systems, including tip growth in fungi and cell movement in animals.

A novel honeycomb cell assay kit designed for evaluating horizontal cell migration in response to functionalized self-assembling peptide hydrogels

NASA Astrophysics Data System (ADS)

Guan, Fengyi; Lu, Jiaju; Wang, Xiumei

2017-03-01

A clear understanding on cell migration behaviors contributes to designing novel biomaterials in tissue engineering and elucidating related tissue regeneration processes. Many traditional evaluation methods on cell migration including scratch assay and transwell migration assay possess all kinds of limitations. In this study, a novel honeycomb cell assay kit was designed and made of photosensitive resin by 3D printing. This kit has seven hexagonal culture chambers so that it can evaluate the horizontal cell migration behavior in response to six surrounding environments simultaneously, eliminating the effect of gravity on cells. Here this cell assay kit was successfully applied to evaluate endothelial cell migration cultured on self-assembling peptide (SAP) RADA (AcN-RADARADARADARADA-CONH2) nanofiber hydrogel toward different functionalized SAP hydrogels. Our results indicated that the functionalized RADA hydrogels with different concentration of bioactive motifs of KLT or PRG could induce cell migration in a dose-dependent manner. The total number and migration distance of endothelial cells on functionalized SAP hydrogels significantly increased with increasing concentration of bioactive motif PRG or KLT. Therefore, the honeycomb cell assay kit provides a simple, efficient and convenient tool to investigate cell migration behavior in response to multi-environments simultaneously.

Negative regulators of vessel patterning.

PubMed

Suchting, Steven; Freitas, Catarina; le Noble, Ferdinand; Benedito, Rui; Bréant, Christiane; Duarte, Antonio; Eichmann, Anne

2007-01-01

Blood vessels and nerves are structurally similar, complex branched networks that require guidance to ensure their proper positioning in the body. Recent studies have demonstrated that specialized endothelial cells, resembling axonal growth cones, are located at the tips of growing capillaries. These endothelial tip cells guide outgrowing capillaries in response to gradients of extracellular matrix-bound vascular endothelial growth factor (VEGF). Here we show that endothelial tip cell formation and vessel branching are negatively regulated by the Notch ligand Delta-like 4 (Dll4). Heterozygous deletion of Dll4 or pharmacological inhibition of Notch signalling using gamma-secretase inhibitor revealed a striking vascular phenotype, with greatly increased numbers of filopodia-extending endothelial tip cells and increased expression of tip cell marker genes compared to controls. Filopodia extension in Dll4+/- retinal vessels required VEGF and was inhibited when VEGF signalling was blocked. While VEGF expression was not significantly altered in Dll4+- retinas, Dll4+/- vessels showed increased expression of VEGF Receptor 2 and decreased expression of VEGF Receptor 1 compared to wildtype, suggesting that they could be more responsive to VEGF stimulation. In addition, expression of Dll4 in wildtype tip cells was itself decreased when VEGF signalling was blocked, indicating that Dll4 may act downstream of VEGF as a 'brake' on VEGF-mediated angiogenic sprouting. Taken together, these data reveal Dll4 as a novel negative regulator of vascular sprouting and vessel branching that is required for normal vascular network formation during development.

Experiment K-6-17. Structural changes and cell turnover in the rats small intestine induced by spaceflight

NASA Technical Reports Server (NTRS)

Phillips, R. W.; Sawyer, H. R.; Smirnov, K. V.

1990-01-01

The purpose of this project was to test the hypothesis that the generalized, whole body decrease in synthetic activity associated with microgravity conditions of space flight as evidenced by negative nitrogen balance and muscle atrophy (Nicogossian and Parker, 1982; Oganov, 1981), as well as inhibited lymphocyte proliferation (Bechler and Cogoli, 1986), would be evident in cells characterized by a rapid rate of turnover. As a model, researchers chose to study the turnover of mucosal cells lining the jejunum of the small intestine, since these cells are among the most rapidly proliferating in the body. Under normal conditions, epithelial cells that line the small intestine are continually produced in the crypts of Lieberkuhn. These cells migrate out of the crypts onto intestinal villi, are progressively pushed up the villus as new crypt cells are formed, and ultimately reach the tip of villi where they are then descquamated. In rats, the entire process, from initial proliferation in crypts to desquamation, takes approximately 2 days (Cairnie et al., 1965; Lipkin, 1973). In this study, researchers determined the mitotic index for mucosal cells lining the proximal, middle, and distal regions of the jejunum in rats from three treatment groups (synchronous control, vivarium control and flight), and measured the depth of the crypts of Lieberkuhn and the length of villi present in each of the three jejunal regions sampled.

Assays for in vitro monitoring of human airway smooth muscle (ASM) and human pulmonary arterial vascular smooth muscle (VSM) cell migration.

PubMed

Goncharova, Elena A; Goncharov, Dmitry A; Krymskaya, Vera P

2006-01-01

Migration of human pulmonary vascular smooth muscle (VSM) cells contributes to vascular remodeling in pulmonary arterial hypertension and atherosclerosis. Evidence also indicates that, in part, migration of airway smooth muscle (ASM) cells may contribute to airway remodeling associated with asthma. Here we describe migration of VSM and ASM cells in vitro using Transwell or Boyden chamber assays. Because dissecting signaling mechanisms regulating cell migration requires molecular approaches, our protocol also describes how to assess migration of transfected VSM and ASM cells. Transwell or Boyden chamber assays can be completed in approximately 8 h and include plating of serum-deprived VSM or ASM cell suspension on membrane precoated with collagen, migration of cells toward chemotactic gradient and visual (Transwell) or digital (Boyden chamber) analysis of membrane. Although the Transwell assay is easy, the Boyden chamber assay requires hands-on experience; however, both assays are reliable cell-based approaches providing valuable information on how chemotactic and inflammatory factors modulate VSM and ASM migration.

Plectin deficiency in liver cancer cells promotes cell migration and sensitivity to sorafenib treatment.

PubMed

Cheng, Chiung-Chi; Chao, Wei-Ting; Liao, Chen-Chun; Tseng, Yu-Hui; Lai, Yen-Chang Clark; Lai, Yih-Shyong; Hsu, Yung-Hsiang; Liu, Yi-Hsiang

2018-01-02

Plectin involved in activation of kinases in cell signaling pathway and plays important role in cell morphology and migration. Plectin knockdown promotes cell migration by activating focal adhesion kinase and Rac1-GTPase activity in liver cells. Sorafenib is a multi-targeting tyrosine kinase inhibitor that improves patient survival on hepatocellular carcinoma. The aim of this study is to investigate the correlation between the expression of plectin and cell migration as well as the sensitivity of hepatoma cell lines exposing to sorafenib. Hepatoma cell lines PLC/PRF/5 and HepG2 were used to examine the level of plectin expression and cell migration in comparison with Chang liver cell line. In addition, sensitivity of the 3 cell lines to sorafenib treatment was also measured. Expression of plectin was lower in PLC/PRF/5 and HepG2 hepatoma cells than that of Chang liver cells whereas HepG2 and PLC/PRF/5 cells exhibit higher rate of cell migration in trans-well migration assay. Immunohistofluorecent staining on E-cadherin revealed the highest rate of collective cell migration in HepG2 cells and the lowest was found in Chang liver cells. Likewise, HepG2 cell line was most sensitive to sorafenib treatment and Chang liver cells exhibited the least sensitivity. The drug sensitivity to sorafenib treatment showed inverse correlation with the expression of plectin. We suggest that plectin deficiency and increased E-cadherin in hepatoma cells were associated with higher rates of cell motility, collective cell migration as well as higher drug sensitivity to sorafenib treatment.

Aerodynamics and Heat Transfer Studies of Parameters Specific to the IGCC-Requirements: Endwall Contouring, Leading Edge and Blade Tip Ejection under Rotating Turbine Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schobeiri, Meinhard; Han, Je-Chin

2014-09-30

This report deals with the specific aerodynamics and heat transfer problematic inherent to high pressure (HP) turbine sections of IGCC-gas turbines. Issues of primary relevance to a turbine stage operating in an IGCC-environment are: (1) decreasing the strength of the secondary flow vortices at the hub and tip regions to reduce (a), the secondary flow losses and (b), the potential for end wall deposition, erosion and corrosion due to secondary flow driven migration of gas flow particles to the hub and tip regions, (2) providing a robust film cooling technology at the hub and that sustains high cooling effectiveness lessmore » sensitive to deposition, (3) investigating the impact of blade tip geometry on film cooling effectiveness. The document includes numerical and experimental investigations of above issues. The experimental investigations were performed in the three-stage multi-purpose turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University. For the numerical investigations a commercial Navier-Stokes solver was utilized.« less

MicroRNA-3178 ameliorates inflammation and gastric carcinogenesis promoted by Helicobacter pylori new toxin, Tip-α, by targeting TRAF3.

PubMed

Zou, Meijuan; Wang, Fang; Jiang, Aiqin; Xia, Anliang; Kong, Siya; Gong, Chun; Zhu, Mingxia; Zhou, Xin; Zhu, Jun; Zhu, Wei; Cheng, Wenfang

2017-04-01

Helicobacter pylori infection is the main cause of chronic gastritis, peptic ulcer, and gastric cancer. Tip-α is a newly identified carcinogenic factor present in H. pylori. TRAF3 can activate NF-κB by both canonical and noncanonical signaling pathways. In this study, we found that the expression of TRAF3 and NF-κB was upregulated, while microRNA-3178 (miR-3178) was decreased in H. pylori-positive gastric tissues but not in H. pylori-negative tissues. GES-1 cells were incubated with 12.5 μg/mL recombinant Tip-α (rTip-α) in RPMI1640 for 2 hours. After another 24 hours, the supernatant medium was designed as inflammatory-conditioned medium (ICM) and that from the untreated control cells was designed as untreated control medium. The release of proinflammatory cytokines from GES-1 cells and proliferation of gastric cancer cells was determined by ELISA and CCK-8 kits. Cells were transfected with the mimic, inhibitor, negative control of miR-3178, or TRAF3 siRNA control siRNA. The medium was then replaced with RPMI1640, 12.5 μg/mL rTip-α, and collected, and the total cellular RNA and protein were extracted for the following detection. MiR-3178 mimic prevented the increasement of TRAF3 and hence decreased activation of NF-κB signals, whereas miR-3178 inhibitor could not, in GES-1 cells with Tip-α treatment. The condition medium from miR-3178 mimic transfected GES-1 cells could inhibit proliferation and induce apoptosis of inflammation-related gastric cancer cells SGC7901 and MGC803 by decreasing the production of inflammatory cytokines TNF-α and IL-6, which were secreted by GES-1 cells. Taken all together, Tip-α might activate NF-κB to promote inflammation and carcinogenesis by inhibiting miR-3178 expression, which directly targeting TRAF3, during H. pylori infection in gastric mucosal epithelial cells. © 2016 John Wiley & Sons Ltd.

DE-Cadherin Is Required for Intercellular Motility during Drosophila Oogenesis

PubMed Central

Niewiadomska, Paulina; Godt, Dorothea; Tepass, Ulrich

1999-01-01

Cadherins are involved in a variety of morphogenetic movements during animal development. However, it has been difficult to pinpoint the precise function of cadherins in morphogenetic processes due to the multifunctional nature of cadherin requirement. The data presented here indicate that homophilic adhesion promoted by Drosophila E-cadherin (DE-cadherin) mediates two cell migration events during Drosophila oogenesis. In Drosophila follicles, two groups of follicle cells, the border cells and the centripetal cells migrate on the surface of germline cells. We show that the border cells migrate as an epithelial patch in which two centrally located cells retain epithelial polarity and peripheral cells are partially depolarized. Both follicle cells and germline cells express DE-cadherin, and border cells and centripetal cells strongly upregulate the expression of DE-cadherin shortly before and during their migration. Removing DE-cadherin from either the follicle cells or the germline cells blocks migration of border cells and centripetal cells on the surface of germline cells. The function of DE-cadherin in border cells appears to be specific for migration as the formation of the border cell cluster and the adhesion between border cells are not disrupted in the absence of DE-cadherin. The speed of migration depends on the level of DE-cadherin expression, as border cells migrate more slowly when DE-cadherin activity is reduced. Finally, we show that the upregulation of DE-cadherin expression in border cells depends on the activity of the Drosophila C/EBP transcription factor that is essential for border cell migration. PMID:9971747

Follow-the-leader cell migration requires biased cell-cell contact and local microenvironmental signals

NASA Astrophysics Data System (ADS)

Wynn, Michelle L.; Rupp, Paul; Trainor, Paul A.; Schnell, Santiago; Kulesa, Paul M.

2013-06-01

Directed cell migration often involves at least two types of cell motility that include multicellular streaming and chain migration. However, what is unclear is how cell contact dynamics and the distinct microenvironments through which cells travel influence the selection of one migratory mode or the other. The embryonic and highly invasive neural crest (NC) are an excellent model system to study this question since NC cells have been observed in vivo to display both of these types of cell motility. Here, we present data from tissue transplantation experiments in chick and in silico modeling that test our hypothesis that cell contact dynamics with each other and the microenvironment promote and sustain either multicellular stream or chain migration. We show that when premigratory cranial NC cells (at the pre-otic level) are transplanted into a more caudal region in the head (at the post-otic level), cells alter their characteristic stream behavior and migrate in chains. Similarly, post-otic NC cells migrate in streams after transplantation into the pre-otic hindbrain, suggesting that local microenvironmental signals dictate the mode of NC cell migration. Simulations of an agent-based model (ABM) that integrates the NC cell behavioral data predict that chain migration critically depends on the interplay of biased cell-cell contact and local microenvironment signals. Together, this integrated modeling and experimental approach suggests new experiments and offers a powerful tool to examine mechanisms that underlie complex cell migration patterns.

Dancing Styles of Collective Cell Migration: Image-Based Computational Analysis of JRAB/MICAL-L2.

PubMed

Sakane, Ayuko; Yoshizawa, Shin; Yokota, Hideo; Sasaki, Takuya

2018-01-01

Collective cell migration is observed during morphogenesis, angiogenesis, and wound healing, and this type of cell migration also contributes to efficient metastasis in some kinds of cancers. Because collectively migrating cells are much better organized than a random assemblage of individual cells, there seems to be a kind of order in migrating clusters. Extensive research has identified a large number of molecules involved in collective cell migration, and these factors have been analyzed using dramatic advances in imaging technology. To date, however, it remains unclear how myriad cells are integrated as a single unit. Recently, we observed unbalanced collective cell migrations that can be likened to either precision dancing or awa-odori , Japanese traditional dancing similar to the style at Rio Carnival, caused by the impairment of the conformational change of JRAB/MICAL-L2. This review begins with a brief history of image-based computational analyses on cell migration, explains why quantitative analysis of the stylization of collective cell behavior is difficult, and finally introduces our recent work on JRAB/MICAL-L2 as a successful example of the multidisciplinary approach combining cell biology, live imaging, and computational biology. In combination, these methods have enabled quantitative evaluations of the "dancing style" of collective cell migration.

Nonlinear optical microscopy reveals invading endothelial cells anisotropically alter three-dimensional collagen matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, P.-F.; Yeh, Alvin T.; Bayless, Kayla J.

The interactions between endothelial cells (ECs) and the extracellular matrix (ECM) are fundamental in mediating various steps of angiogenesis, including cell adhesion, migration and sprout formation. Here, we used a noninvasive and non-destructive nonlinear optical microscopy (NLOM) technique to optically image endothelial sprouting morphogenesis in three-dimensional (3D) collagen matrices. We simultaneously captured signals from collagen fibers and endothelial cells using second harmonic generation (SHG) and two-photon excited fluorescence (TPF), respectively. Dynamic 3D imaging revealed EC interactions with collagen fibers along with quantifiable alterations in collagen matrix density elicited by EC movement through and morphogenesis within the matrix. Specifically, we observedmore » increased collagen density in the area between bifurcation points of sprouting structures and anisotropic increases in collagen density around the perimeter of lumenal structures, but not advancing sprout tips. Proteinase inhibition studies revealed membrane-associated matrix metalloproteinase were utilized for sprout advancement and lumen expansion. Rho-associated kinase (p160ROCK) inhibition demonstrated that the generation of cell tension increased collagen matrix alterations. This study followed sprouting ECs within a 3D matrix and revealed that the advancing structures recognize and significantly alter their extracellular environment at the periphery of lumens as they progress.« less

The Golgi in Cell Migration: Regulation by Signal Transduction and Its Implications for Cancer Cell Metastasis

PubMed Central

Millarte, Valentina; Farhan, Hesso

2012-01-01

Migration and invasion are fundamental features of metastatic cancer cells. The Golgi apparatus, an organelle involved in posttranslational modification and sorting of proteins, is widely accepted to regulate directional cell migration. In addition, mounting evidence suggests that the Golgi is a hub for different signaling pathways. In this paper we will give an overview on how polarized secretion and microtubule nucleation at the Golgi regulate directional cell migration. We will review different signaling pathways that signal to and from the Golgi. Finally, we will discuss how these signaling pathways regulate the role of the Golgi in cell migration and invasion. We propose that by identifying regulators of the Golgi, we might be able to uncover unappreciated modulators of cell migration. Uncovering the regulatory network that orchestrates cell migration is of fundamental importance for the development of new therapeutic strategies against cancer cell metastasis. PMID:22623902

Focal Adhesion-Independent Cell Migration.

PubMed

Paluch, Ewa K; Aspalter, Irene M; Sixt, Michael

2016-10-06

Cell migration is central to a multitude of physiological processes, including embryonic development, immune surveillance, and wound healing, and deregulated migration is key to cancer dissemination. Decades of investigations have uncovered many of the molecular and physical mechanisms underlying cell migration. Together with protrusion extension and cell body retraction, adhesion to the substrate via specific focal adhesion points has long been considered an essential step in cell migration. Although this is true for cells moving on two-dimensional substrates, recent studies have demonstrated that focal adhesions are not required for cells moving in three dimensions, in which confinement is sufficient to maintain a cell in contact with its substrate. Here, we review the investigations that have led to challenging the requirement of specific adhesions for migration, discuss the physical mechanisms proposed for cell body translocation during focal adhesion-independent migration, and highlight the remaining open questions for the future.

C-C motif ligand 5 promotes migration of prostate cancer cells in the prostate cancer bone metastasis microenvironment.

PubMed

Urata, Satoko; Izumi, Kouji; Hiratsuka, Kaoru; Maolake, Aerken; Natsagdorj, Ariunbold; Shigehara, Kazuyoshi; Iwamoto, Hiroaki; Kadomoto, Suguru; Makino, Tomoyuki; Naito, Renato; Kadono, Yoshifumi; Lin, Wen-Jye; Wufuer, Guzailinuer; Narimoto, Kazutaka; Mizokami, Atsushi

2018-03-01

Chemokines and their receptors have key roles in cancer progression. The present study investigated chemokine activity in the prostate cancer bone metastasis microenvironment. Growth and migration of human prostate cancer cells were assayed in cocultures with bone stromal cells. The migration of LNCaP cells significantly increased when co-cultured with bone stromal cells isolated from prostate cancer bone metastases. Cytokine array analysis of conditioned medium from bone stromal cell cultures identified CCL5 as a concentration-dependent promoter of LNCaP cell migration. The migration of LNCaP cells was suppressed when C-C motif ligand 5 (CCL5) neutralizing antibody was added to cocultures with bone stromal cells. Knockdown of androgen receptor with small interfering RNA increased the migration of LNCaP cells compared with control cells, and CCL5 did not promote the migration of androgen receptor knockdown LNCaP. Elevated CCL5 secretion in bone stromal cells from metastatic lesions induced prostate cancer cell migration by a mechanism consistent with CCL5 activity upstream of androgen receptor signaling. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Epitaxially grown collagen fibrils reveal diversity in contact guidance behavior among cancer cells.

PubMed

Wang, Juan; Petefish, Joseph W; Hillier, Andrew C; Schneider, Ian C

2015-01-01

Invasion of cancer cells into the surrounding tissue is an important step during cancer progression and is driven by cell migration. Cell migration can be random, but often it is directed by various cues such as aligned fibers composed of extracellular matrix (ECM), a process called contact guidance. During contact guidance, aligned fibers bias migration along the long axis of the fibers. These aligned fibers of ECM are commonly composed of type I collagen, an abundant structural protein around tumors. In this paper, we epitaxially grew several different patterns of organized type I collagen on mica and compared the morphology and contact guidance behavior of two invasive breast cancer cell lines (MDA-MB-231 and MTLn3 cells). Others have shown that these cells randomly migrate in qualitatively different ways. MDA-MB-231 cells exert large traction forces, tightly adhere to the ECM, and migrate with spindle-shaped morphology and thus adopt a mesenchymal mode of migration. MTLn3 cells exert small traction forces, loosely adhere to the ECM, and migrate with a more rounded morphology and thus adopt an amoeboid mode of migration. As the degree of alignment of type I collagen fibrils increases, cells become more elongated and engage in more directed contact guidance. MDA-MB-231 cells perceive the directional signal of highly aligned type I collagen fibrils with high fidelity, elongating to large extents and migrating directionally. Interestingly, behavior in MTLn3 cells differs. While highly aligned type I collagen fibril patterns facilitate spreading and random migration of MTLn3 cells, they do not support elongation or directed migration. Thus, different contact guidance cues bias cell migration differently and the fidelity of contact guidance is cell type dependent, suggesting that ECM alignment is a permissive cue for contact guidance, but requires a cell to have certain properties to interpret that cue.

Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus. I. Cell types without spherules.

PubMed

Heatfield, B M; Travis, D F

1975-01-01

The fine structure of regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus was investigated. Each conical tip consisted of an inner dermis, which deposits and contains the calcite skeleton, and an external layer of epidermis. Although cell types termed spherulecytes containing large, intracellular membrane bound spherules were also present in spine tissues, only epidermal and dermal cell types lacking such spherules are described in this paper. The epidermis was composed largely of free cells representing several functional types. Over the apical portion of the tip these cells occurred in groups, while proximally they were distributed within longitudinal grooves present along the periphery of the spine from the base to the tip. The terminal portions of apical processes extending from some of the epidermal cells formed a thin, contiguous outer layer consisting of small individual islands of cytoplasm bearing microvilli. Adjacent islands were connected around the periphery by a junctional complex extending roughly 200 A in depth in which the opposing plasma membranes were separated by a narrow gap about 145 A in width bridged by amorphous material. Other epidermal cells were closely associated with the basal lamina, which was 900 A in thickness and delineated the dermoepidermal junction; some of these cells appeared to synthesize the lamina, while others may be sensory nerve cells. The dermis at the spine tip also consisted of several functional types of free cells; the most interesting of these was the calcoblast, which deposits the skeleton. Calcoblasts extended a thin, cytoplasmic skeletal sheath which surrounded the tips and adjacent proximal portions of each of the longitudinally oriented microspines comprising the regenerating skeleton, and distally, formed a conical extracellular channel ahead of the mineralizing tip. The intimate relationship between calcoblasts and the growing mineral surface strongly suggests that these cells directly control both the kinetics of mineral deposition and morphogenesis of the skeleton. Other cell types in the dermis were precalcoblasts and phagocytes. Precalcoblasts may function as fibroblasts and are possible precursors of calcoblasts. Closely associated with the basal lamina at the dermoepidermal junction were extracellular unbanded anchoring fi0rils 150 A to 200 A51 in diameter. Scattered proximally among dermal cells were other extracellular fibrils, presumably collagenous, about 300 A in diameter wit

Cadherin-2 Is Required Cell Autonomously for Collective Migration of Facial Branchiomotor Neurons.

PubMed

Rebman, Jane K; Kirchoff, Kathryn E; Walsh, Gregory S

2016-01-01

Collective migration depends on cell-cell interactions between neighbors that contribute to their overall directionality, yet the mechanisms that control the coordinated migration of neurons remains to be elucidated. During hindbrain development, facial branchiomotor neurons (FBMNs) undergo a stereotypic tangential caudal migration from their place of birth in rhombomere (r)4 to their final location in r6/7. FBMNs engage in collective cell migration that depends on neuron-to-neuron interactions to facilitate caudal directionality. Here, we demonstrate that Cadherin-2-mediated neuron-to-neuron adhesion is necessary for directional and collective migration of FBMNs. We generated stable transgenic zebrafish expressing dominant-negative Cadherin-2 (Cdh2ΔEC) driven by the islet1 promoter. Cell-autonomous inactivation of Cadherin-2 function led to non-directional migration of FBMNs and a defect in caudal tangential migration. Additionally, mosaic analysis revealed that Cdh2ΔEC-expressing FBMNs are not influenced to migrate caudally by neighboring wild-type FBMNs due to a defect in collective cell migration. Taken together, our data suggest that Cadherin-2 plays an essential cell-autonomous role in mediating the collective migration of FBMNs.

Fast-crawling cell types migrate to avoid the direction of periodic substratum stretching

PubMed Central

Okimura, Chika; Ueda, Kazuki; Sakumura, Yuichi; Iwadate, Yoshiaki

2016-01-01

ABSTRACT To investigate the relationship between mechanical stimuli from substrata and related cell functions, one of the most useful techniques is the application of mechanical stimuli via periodic stretching of elastic substrata. In response to this stimulus, Dictyostelium discoideum cells migrate in a direction perpendicular to the stretching direction. The origins of directional migration, higher migration velocity in the direction perpendicular to the stretching direction or the higher probability of a switch of migration direction to perpendicular to the stretching direction, however, remain unknown. In this study, we applied periodic stretching stimuli to neutrophil-like differentiated HL-60 cells, which migrate perpendicular to the direction of stretch. Detailed analysis of the trajectories of HL-60 cells and Dictyostelium cells obtained in a previous study revealed that the higher probability of a switch of migration direction to that perpendicular to the direction of stretching was the main cause of such directional migration. This directional migration appears to be a strategy adopted by fast-crawling cells in which they do not migrate faster in the direction they want to go, but migrate to avoid a direction they do not want to go. PMID:26980079

The Notch ligand Delta-like 4 negatively regulates endothelial tip cell formation and vessel branching

PubMed Central

Suchting, Steven; Freitas, Catarina; le Noble, Ferdinand; Benedito, Rui; Bréant, Christiane; Duarte, Antonio; Eichmann, Anne

2007-01-01

Delta-like 4 (Dll4) is a transmembrane ligand for Notch receptors that is expressed in arterial blood vessels and sprouting endothelial cells. Here we show that Dll4 regulates vessel branching during development by inhibiting endothelial tip cell formation. Heterozygous deletion of dll4 or pharmacological inhibition of Notch signaling using γ-secretase inhibitor revealed a striking vascular phenotype, with greatly increased numbers of filopodia-extending endothelial tip cells and increased expression of tip cell marker genes compared with controls. Filopodia extension in dll4+/− retinal vessels required the vascular growth factor VEGF and was inhibited when VEGF signaling was blocked. Although VEGF expression was not significantly altered in dll4+/− retinas, dll4+/− vessels showed increased expression of VEGF receptor 2 and decreased expression of VEGF receptor 1 compared with wild-type, suggesting they could be more responsive to VEGF stimulation. In addition, expression of dll4 in wild-type tip cells was itself decreased when VEGF signaling was blocked, indicating that dll4 may act downstream of VEGF as a “brake” on VEGF-mediated angiogenic sprouting. Taken together, these data reveal Dll4 as a negative regulator of vascular sprouting and vessel branching that is required for normal vascular network formation during development. PMID:17296941

The Notch ligand Delta-like 4 negatively regulates endothelial tip cell formation and vessel branching.

PubMed

Suchting, Steven; Freitas, Catarina; le Noble, Ferdinand; Benedito, Rui; Bréant, Christiane; Duarte, Antonio; Eichmann, Anne

2007-02-27

Delta-like 4 (Dll4) is a transmembrane ligand for Notch receptors that is expressed in arterial blood vessels and sprouting endothelial cells. Here we show that Dll4 regulates vessel branching during development by inhibiting endothelial tip cell formation. Heterozygous deletion of dll4 or pharmacological inhibition of Notch signaling using gamma-secretase inhibitor revealed a striking vascular phenotype, with greatly increased numbers of filopodia-extending endothelial tip cells and increased expression of tip cell marker genes compared with controls. Filopodia extension in dll4(+/-) retinal vessels required the vascular growth factor VEGF and was inhibited when VEGF signaling was blocked. Although VEGF expression was not significantly altered in dll4(+/-) retinas, dll4(+/-) vessels showed increased expression of VEGF receptor 2 and decreased expression of VEGF receptor 1 compared with wild-type, suggesting they could be more responsive to VEGF stimulation. In addition, expression of dll4 in wild-type tip cells was itself decreased when VEGF signaling was blocked, indicating that dll4 may act downstream of VEGF as a "brake" on VEGF-mediated angiogenic sprouting. Taken together, these data reveal Dll4 as a negative regulator of vascular sprouting and vessel branching that is required for normal vascular network formation during development.

Desiccation and osmotic stress increase the abundance of mRNA of the tonoplast aquaporin BobTIP26-1 in cauliflower cells.

PubMed

Barrieu, F; Marty-Mazars, D; Thomas, D; Chaumont, F; Charbonnier, M; Marty, F

1999-07-01

Changes in vacuolar structure and the expression at the RNA level of a tonoplast aquaporin (BobTIP26-1) were examined in cauliflower (Brassicaoleracea L. var. botrytis) under water-stress conditions. Gradual drying out of slices of cauliflower floret tissue caused its collapse, with a shrinkage in tissue and cell volumes and an apparent vesiculation of the central vacuole, whereas osmotic stress resulted in plasmolysis with a collapse of the cytoplasm and the central vacuole within. Osmotic stress caused a rapid and substantial increase in BobTIP26 mRNA in slices of floret tissue. Exposure of tissue slices to a regime of desiccation showed a slower but equally large rise in BobTIP26 mRNA followed by a rapid decline upon rehydration. In situ hybridization showed that BobTIP26-2 mRNA is expressed most highly in meristematic and expanding cells of the cauliflower florets and that desiccation strongly increased the expression in those cells and in differentiated cells near the xylem vessels. These data indicate that under water-deficit conditions, expression of the tonoplast aquaporin gene in cauliflower is subject to a precise regulation that can be correlated with important cytological changes in the cells.

Nanotopography guides and directs cell migration in amoeboid and epithelial cells

NASA Astrophysics Data System (ADS)

Lee, Rachel; Das, Satarupa; Hourwitz, Matthew; Sun, Xiaoyu; Parent, Carole; Fourkas, John; Losert, Wolfgang

Cell migration plays a critical role in development, angiogenesis, immune response, wound healing, and cancer metastasis. In many cases, cells also move in the context of a matrix of collagen fibers, and the alignment of these fibers can both affect the migration phenotype and guide cells. Here we show that both fast and slow migrating cells - amoeboid HL-60 and epithelial MCF10A - are affected in similar ways by micro/nanostructures with dimensions similar to those of collagen fibers. Cell alignment enhances the efficiency of migration by increasing directional persistence.

A PDMS Device Coupled with Culture Dish for In Vitro Cell Migration Assay.

PubMed

Lv, Xiaoqing; Geng, Zhaoxin; Fan, Zhiyuan; Wang, Shicai; Pei, WeiHua; Chen, Hongda

2018-04-30

Cell migration and invasion are important factors during tumor progression and metastasis. Wound-healing assay and the Boyden chamber assay are efficient tools to investigate tumor development because both of them could be applied to measure cell migration rate. Therefore, a simple and integrated polydimethylsiloxane (PDMS) device was developed for cell migration assay, which could perform quantitative evaluation of cell migration behaviors, especially for the wound-healing assay. The integrated device was composed of three units, which included cell culture dish, PDMS chamber, and wound generation mold. The PDMS chamber was integrated with cell culture chamber and could perform six experiments under different conditions of stimuli simultaneously. To verify the function of this device, it was utilized to explore the tumor cell migration behaviors under different concentrations of fetal bovine serum (FBS) and transforming growth factor (TGF-β) at different time points. This device has the unique capability to create the "wound" area in parallel during cell migration assay and provides a simple and efficient platform for investigating cell migration assay in biomedical application.

Lamellipodin and the Scar/WAVE complex cooperate to promote cell migration in vivo

PubMed Central

Law, Ah-Lai; Vehlow, Anne; Kotini, Maria; Dodgson, Lauren; Soong, Daniel; Theveneau, Eric; Bodo, Cristian; Taylor, Eleanor; Navarro, Christel; Perera, Upamali; Michael, Magdalene; Dunn, Graham A.; Bennett, Daimark; Mayor, Roberto

2013-01-01

Cell migration is essential for development, but its deregulation causes metastasis. The Scar/WAVE complex is absolutely required for lamellipodia and is a key effector in cell migration, but its regulation in vivo is enigmatic. Lamellipodin (Lpd) controls lamellipodium formation through an unknown mechanism. Here, we report that Lpd directly binds active Rac, which regulates a direct interaction between Lpd and the Scar/WAVE complex via Abi. Consequently, Lpd controls lamellipodium size, cell migration speed, and persistence via Scar/WAVE in vitro. Moreover, Lpd knockout mice display defective pigmentation because fewer migrating neural crest-derived melanoblasts reach their target during development. Consistently, Lpd regulates mesenchymal neural crest cell migration cell autonomously in Xenopus laevis via the Scar/WAVE complex. Further, Lpd’s Drosophila melanogaster orthologue Pico binds Scar, and both regulate collective epithelial border cell migration. Pico also controls directed cell protrusions of border cell clusters in a Scar-dependent manner. Taken together, Lpd is an essential, evolutionary conserved regulator of the Scar/WAVE complex during cell migration in vivo. PMID:24247431

Myosin-II-Mediated Directional Migration of Dictyostelium Cells in Response to Cyclic Stretching of Substratum

PubMed Central

Iwadate, Yoshiaki; Okimura, Chika; Sato, Katsuya; Nakashima, Yuta; Tsujioka, Masatsune; Minami, Kazuyuki

2013-01-01

Living cells are constantly subjected to various mechanical stimulations, such as shear flow, osmotic pressure, and hardness of substratum. They must sense the mechanical aspects of their environment and respond appropriately for proper cell function. Cells adhering to substrata must receive and respond to mechanical stimuli from the substrata to decide their shape and/or migrating direction. In response to cyclic stretching of the elastic substratum, intracellular stress fibers in fibroblasts and endothelial, osteosarcoma, and smooth muscle cells are rearranged perpendicular to the stretching direction, and the shape of those cells becomes extended in this new direction. In the case of migrating Dictyostelium cells, cyclic stretching regulates the direction of migration, and not the shape, of the cell. The cells migrate in a direction perpendicular to that of the stretching. However, the molecular mechanisms that induce the directional migration remain unknown. Here, using a microstretching device, we recorded green fluorescent protein (GFP)-myosin-II dynamics in Dictyostelium cells on an elastic substratum under cyclic stretching. Repeated stretching induced myosin II localization equally on both stretching sides in the cells. Although myosin-II-null cells migrated randomly, myosin-II-null cells expressing a variant of myosin II that cannot hydrolyze ATP migrated perpendicular to the stretching. These results indicate that Dictyostelium cells accumulate myosin II at the portion of the cell where a large strain is received and migrate in a direction other than that of the portion where myosin II accumulated. This polarity generation for migration does not require the contraction of actomyosin. PMID:23442953

Neutral endopeptidase inhibits prostate cancer cell migration by blocking focal adhesion kinase signaling.

PubMed

Sumitomo, M; Shen, R; Walburg, M; Dai, J; Geng, Y; Navarro, D; Boileau, G; Papandreou, C N; Giancotti, F G; Knudsen, B; Nanus, D M

2000-12-01

Neutral endopeptidase 24.11 (NEP, CD10) is a cell-surface enzyme expressed by prostatic epithelial cells that cleaves and inactivates neuropeptides implicated in the growth of androgen-independent prostate cancer (PC). NEP substrates such as bombesin and endothelin-1 induce cell migration. We investigated the mechanisms of NEP regulation of cell migration in PC cells, including regulation of phosphorylation on tyrosine of focal adhesion kinase (FAK). Western analyses and cell migration assays revealed an inverse correlation between NEP expression and the levels of FAK phosphorylation and cell migration in PC cell lines. Constitutively expressed NEP, recombinant NEP, and induced NEP expression using a tetracycline-repressive expression system inhibited bombesin- and endothelin-1-stimulated FAK phosphorylation and cell migration. This results from NEP-induced inhibition of neuropeptide-stimulated association of FAK with cSrc protein. Expression of a mutated catalytically inactive NEP protein also resulted in partial inhibition of FAK phosphorylation and cell migration. Coimmunoprecipitation experiments show that NEP associates with tyrosine-phosphorylated Lyn kinase, which then binds the p85 subunit of phosphatidylinositol 3-kinase (PI3-K) resulting in an NEP-Lyn-PI3-K protein complex. This complex competitively blocks FAK-PI3-K interaction, suggesting that NEP protein inhibits cell migration via a protein-protein interaction independent of its catalytic function. These experiments demonstrate that NEP can inhibit FAK phosphorylation on tyrosine and PC cell migration through multiple pathways and suggest that cell migration which contributes to invasion and metastases in PC cells can be regulated by NEP.

Neutral endopeptidase inhibits prostate cancer cell migration by blocking focal adhesion kinase signaling

PubMed Central

Sumitomo, Makoto; Shen, Ruoqian; Walburg, Marc; Dai, Jie; Geng, Yiping; Navarro, Daniel; Boileau, Guy; Papandreou, Christos N.; Giancotti, Filippo G.; Knudsen, Beatrice; Nanus, David M.

2000-01-01

Neutral endopeptidase 24.11 (NEP, CD10) is a cell-surface enzyme expressed by prostatic epithelial cells that cleaves and inactivates neuropeptides implicated in the growth of androgen-independent prostate cancer (PC). NEP substrates such as bombesin and endothelin-1 induce cell migration. We investigated the mechanisms of NEP regulation of cell migration in PC cells, including regulation of phosphorylation on tyrosine of focal adhesion kinase (FAK). Western analyses and cell migration assays revealed an inverse correlation between NEP expression and the levels of FAK phosphorylation and cell migration in PC cell lines. Constitutively expressed NEP, recombinant NEP, and induced NEP expression using a tetracycline-repressive expression system inhibited bombesin- and endothelin-1–stimulated FAK phosphorylation and cell migration. This results from NEP-induced inhibition of neuropeptide-stimulated association of FAK with cSrc protein. Expression of a mutated catalytically inactive NEP protein also resulted in partial inhibition of FAK phosphorylation and cell migration. Coimmunoprecipitation experiments show that NEP associates with tyrosine-phosphorylated Lyn kinase, which then binds the p85 subunit of phosphatidylinositol 3-kinase (PI3-K) resulting in an NEP-Lyn-PI3-K protein complex. This complex competitively blocks FAK-PI3-K interaction, suggesting that NEP protein inhibits cell migration via a protein-protein interaction independent of its catalytic function. These experiments demonstrate that NEP can inhibit FAK phosphorylation on tyrosine and PC cell migration through multiple pathways and suggest that cell migration which contributes to invasion and metastases in PC cells can be regulated by NEP. PMID:11104793

Deformation of Forearcs during Aseismic Ridge Subduction

NASA Astrophysics Data System (ADS)

Zeumann, S.; Hampel, A.

2014-12-01

Subduction of aseismic oceanic ridges causes considerable deformation of the forearc region. To identify the crucial parameters for forearc deformation we created 3D finite-element models representing both erosive and accretive forearcs as well as migrating and non-migrating ridges. As natural examples we choose the Cocos ridge subducting stationary beneath the erosive margin of Costa Rica and the Nazca and Gagua Ridges that migrate along the erosive Peruvian margin and the accretive accretive Ryukyu margin, respectively. A series of models show that the deformation of the forearc depends on the ridge shape (height, width), on the frictional coupling along the plate interface and the mechanical strength of the forearc. The forearc is uplifted and moved sideward during ridge subduction. Strain components show domains of both, shortening and extension. Along the ridge axis, extension occurs except at the ridge tip, where shortening prevails. The strain component normal to the ridge axis reveals extension at the ridge tip and contraction above the ridge flanks. Shortening and extension increase with increasing ridge height. Higher friction coefficients lead to less extension and more shortening. Accretive wedges show larger indentation at the model trench. For stationary ridges (Cocos Ridge) the deformation pattern of the forearc is symmetric with respect to the ridge axis whereas for migrating ridges (Nazca Ridge, Gagua Ridge) the oblique convergence direction leads to asymmetric deformation of the forearc. In case of ridge migration, uplift occurs at the leading flank of the ridge and subsidence at the trailing flank, in agreement with field observations and analogue models. For a model with a 200-km-wide and 1500-m-high ridge (i.e. similar to the dimensions of the Nazca Ridge), the modelled uplift rate at the southern ridge flank of the ridge is ~1 mm/a, which agrees well with uplift rates of ~0.7 mm/a derived from the elevation of marine terraces in southern Peru.

[Effectivity and Safety of a Modified Tip Design in Torsional Phacoemulsification].

PubMed

Schmidt, Sabine; Hubich, Sophie; Vetter, Jan Markus; Wirbelauer, Christopher

2018-02-16

Torsional mode phacoemulsification results in more effective fragmentation of the nucleus due to a different movement of the phacotip. In this clinical study, we investigated the influence of a modified tip design and active fluidics on the efficacy of phacoemulsification and safety for the corneal endothelium. We conducted a prospective randomized 2 : 1 study in which 40 patients were operated on with the mini-flared Kelman Tip using the Infiniti ® System (group 1), and 20 patients were operated on with the Intrepid ® Balanced Tip and the Centurion ® System. We analyzed the intraoperative cumulative dissipated energy and also the density of the corneal endothelium measured with an endothelial microscope (CEM 530, Nidek) pre- and postoperatively. Both groups did not differ preoperatively in age, sex, axial length of the globe or corneal endothelium cell density nor cataract density (LOCS3). All surgeries were uneventful. The cumulative dissipated energy in group 1 (mini-flared Kelman tip, Infiniti System) was 38% higher than in group 2 (balanced tip, Centurion System; p < 0.05). The endothelial cell loss was 8% in group 1 and 10.3% in group 2 (p > 0.05). The cell size (polymegathism) increased in both groups significantly with + 37 µm in group 1 (p < 0.05) und + 54 µm in group 2 (p < 0.05). There was no statistically significant difference between both groups (p > 0.05). The number of hexagonal cells (pleomorphism) and corneal thickness did not differ in both groups either pre- nor postoperatively. Compared to torsional phacoemulsification with a mini-flared Kelman Tip and gravity fluidics, torsional phacoemulsification with a modified tip design and active fluidics is 38% more effective regarding the cumulative dissipated energy. Endothelial cell loss occurs to a similar extend using both systems. The postoperative changes in cell size (polymegathism), number of hexagonal cells (pleomorphism) and corneal thickness (pachymetry) were similar among both systems. We conclude, that the intraoperative stress on the endothelium is equivalent with both systems used. Georg Thieme Verlag KG Stuttgart · New York.

Pinoresinol-4,4'-di-O-beta-D-glucoside from Valeriana officinalis root stimulates calcium mobilization and chemotactic migration of mouse embryo fibroblasts.

PubMed

Do, Kee Hun; Choi, Young Whan; Kim, Eun Kyoung; Yun, Sung Ji; Kim, Min Sung; Lee, Sun Young; Ha, Jung Min; Kim, Jae Ho; Kim, Chi Dae; Son, Beung Gu; Kang, Jum Soon; Khan, Ikhlas A; Bae, Sun Sik

2009-06-01

Lignans are major constituents of plant extracts and have important pharmacological effects on mammalian cells. Here we showed that pinoresinol-4,4'-di-O-beta-D-glucoside (PDG) from Valeriana officinalis induced calcium mobilization and cell migration through the activation of lysophosphatidic acid (LPA) receptor subtypes. Stimulation of mouse embryo fibroblast (MEF) cells with 10 microM PDG resulted in strong stimulation of MEF cell migration and the EC(50) was about 2 microM. Pretreatment with pertussis toxin (PTX), an inhibitor of G(i) protein, completely blocked PDG-induced cell migration demonstrating that PDG evokes MEF cell migration through the activation of the G(i)-coupled receptor. Furthermore, pretreatment of MEF cells with Ki16425 (10 microM), which is a selective antagonist for LPA(1) and LPA(3) receptors, completely blocked PDG-induced cell migration. Likewise, PDG strongly induced calcium mobilization, which was also blocked by Ki16425 in a dose-dependent manner. Prior occupation of the LPA receptor with LPA itself completely blocked PDG-induced calcium mobilization. Finally, PDG-induced MEF cell migration was attenuated by pretreatment with a phosphatidylinositol 3-kinase (PI3K) inhibitor such as LY294002. Cells lacking downstream mediator of PI3K such as Akt1 and Akt2 (DKO cells) showed loss of PDG-induced migration. Re-expression of Akt1 (but not Akt2) completely restored PDG-induced DKO cell migration. Given these results, we conclude that PDG is a strong inducer of cell migration. We suggest that the pharmacological action of PDG may occur through the activation of an LPA receptor whereby activation of PI3K/Akt signaling pathway mediates PDG-induced MEF cell migration.

Multi-Cellular Logistics of Collective Cell Migration

PubMed Central

Yamao, Masataka; Naoki, Honda; Ishii, Shin

2011-01-01

During development, the formation of biological networks (such as organs and neuronal networks) is controlled by multicellular transportation phenomena based on cell migration. In multi-cellular systems, cellular locomotion is restricted by physical interactions with other cells in a crowded space, similar to passengers pushing others out of their way on a packed train. The motion of individual cells is intrinsically stochastic and may be viewed as a type of random walk. However, this walk takes place in a noisy environment because the cell interacts with its randomly moving neighbors. Despite this randomness and complexity, development is highly orchestrated and precisely regulated, following genetic (and even epigenetic) blueprints. Although individual cell migration has long been studied, the manner in which stochasticity affects multi-cellular transportation within the precisely controlled process of development remains largely unknown. To explore the general principles underlying multicellular migration, we focus on the migration of neural crest cells, which migrate collectively and form streams. We introduce a mechanical model of multi-cellular migration. Simulations based on the model show that the migration mode depends on the relative strengths of the noise from migratory and non-migratory cells. Strong noise from migratory cells and weak noise from surrounding cells causes “collective migration,” whereas strong noise from non-migratory cells causes “dispersive migration.” Moreover, our theoretical analyses reveal that migratory cells attract each other over long distances, even without direct mechanical contacts. This effective interaction depends on the stochasticity of the migratory and non-migratory cells. On the basis of these findings, we propose that stochastic behavior at the single-cell level works effectively and precisely to achieve collective migration in multi-cellular systems. PMID:22205934

Autoradiography and the Cell Cycle.

ERIC Educational Resources Information Center

Jones, C. Weldon

1992-01-01

Outlines the stages of a cell biology "pulse-chase" experiment in which the students apply autoradiography techniques to learn about the concept of the cell cycle. Includes (1) seed germination and plant growth; (2) radioactive labeling and fixation of root tips; (3) feulgen staining of root tips; (4) preparation of autoradiograms; and…

Nanofiber Nerve Guide for Peripheral Nerve Repair and Regeneration

DTIC Science & Technology

2014-01-01

observing cell migration using live - cell imaging microscopy, and analyzing cell migration with our MATLAB-based programs. Our studies...are then pipetted into the chamber and their path of migration is observed using a live - cell imaging microscope (Fig. 6d). Utilizing this migration

N-WASP and WAVE2 acting downstream of phosphatidylinositol 3-kinase are required for myogenic cell migration induced by hepatocyte growth factor.

PubMed

Kawamura, Kazuhiro; Takano, Kazunori; Suetsugu, Shiro; Kurisu, Shusaku; Yamazaki, Daisuke; Miki, Hiroaki; Takenawa, Tadaomi; Endo, Takeshi

2004-12-24

During skeletal muscle regeneration caused by injury, muscle satellite cells proliferate and migrate toward the site of muscle injury. This migration is mainly induced by hepatocyte growth factor (HGF) secreted by intact myofibers and also released from injured muscle. However, the intracellular machinery for the satellite cell migration has not been elucidated. To examine the mechanisms of satellite cell migration, we utilized satellite cell-derived mouse C2C12 skeletal muscle cells. HGF induced reorganization of actin cytoskeleton to form lamellipodia in C2C12 myoblasts. HGF treatment facilitated both nondirectional migration of the myoblasts in phagokinetic track assay and directional chemotactic migration toward HGF in a three-dimensional migration chamber assay. Endogenous N-WASP and WAVE2 were concentrated in the lamellipodia at the leading edge of the migrating cells. Moreover, exogenous expression of wild-type N-WASP or WAVE2 promoted lamellipodial formation and migration. By contrast, expression of the dominant-negative mutant of N-WASP or WAVE2 and knockdown of N-WASP or WAVE2 expression by the RNA interference prevented the HGF-induced lamellipodial formation and migration. When the cells were treated with LY294002, an inhibitor of phosphatidylinositol 3-kinase, the HGF-induced lamellipodial formation and migration were abrogated. These results imply that both N-WASP and WAVE2, which are activated downstream of phosphati-dylinositol 3-kinase, are required for the migration through the lamellipodial formation of C2C12 cells induced by HGF.

A simple non-perturbing cell migration assay insensitive to proliferation effects

PubMed Central

Glenn, Honor L.; Messner, Jacob; Meldrum, Deirdre R.

2016-01-01

Migration is a fundamental cellular behavior that plays an indispensable role in development and homeostasis, but can also contribute to pathology such as cancer metastasis. Due to its relevance to many aspects of human health, the ability to accurately measure cell migration is of broad interest, and numerous approaches have been developed. One of the most commonly employed approaches, because of its simplicity and throughput, is the exclusion zone assay in which cells are allowed to migrate into an initially cell-free region. A major drawback of this assay is that it relies on simply counting cells in the exclusion zone and therefore cannot distinguish the effects of proliferation from migration. We report here a simple modification to the exclusion zone migration assay that exclusively measures cell migration and is not affected by proliferation. This approach makes use of a lineage-tracing vital stain that is retained through cell generations and effectively reads out migration relative to the original, parental cell population. This modification is simple, robust, non-perturbing, and inexpensive. We validate the method in a panel of cell lines under conditions that inhibit or promote migration and demonstrate its use in normal and cancer cell lines as well as primary cells. PMID:27535324

Control of the Water Transport Activity of Barley HvTIP3;1 Specifically Expressed in Seeds.

PubMed

Utsugi, Shigeko; Shibasaka, Mineo; Maekawa, Masahiko; Katsuhara, Maki

2015-09-01

Tonoplast intrinsic proteins (TIPs) are involved in the transport and storage of water, and control intracellular osmotic pressure by transporting material related to the water potential of cells. In the present study, we focused on HvTIP3;1 during the periods of seed development and desiccation in barley. HvTIP3;1 was specifically expressed in seeds. An immunochemical analysis showed that HvTIP3;1 strongly accumulated in the aleurone layers and outer layers of barley seeds. The water transport activities of HvTIP3;1 and HvTIP1;2, which also accumulated in seeds, were measured in the heterologous expression system of Xenopus oocytes. When they were expressed individually, HvTIP1;2 transported water, whereas HvTIP3;1 did not. However, HvTIP3;1 exhibited water transport activity when co-expressed with HvTIP1;2 in oocytes, and this activity was higher than when HvTIP1;2 was expressed alone. This is the first report to demonstrate that the water permeability of a TIP aquaporin was activated when co-expressed with another TIP. The split-yellow fluorescent protein (YFP) system in onion cells revealed that HvTIP3;1 interacted with HvTIP1;2 to form a heterotetramer in plants. These results suggest that HvTIP3;1 functions as an active water channel to regulate water movement through tissues during the periods of seed development and desiccation. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The FGF8-related signals Pyramus and Thisbe promote pathfinding, substrate adhesion, and survival of migrating longitudinal gut muscle founder cells

PubMed Central

Reim, Ingolf; Hollfelder, Dominik; Ismat, Afshan; Frasch, Manfred

2013-01-01

Fibroblast growth factors (FGFs) frequently fulfill prominent roles in the regulation of cell migration in various contexts. In Drosophila, the FGF8-like ligands Pyramus (Pyr) and Thisbe (Ths), which signal through their receptor Heartless (Htl), are known to regulate early mesodermal cell migration after gastrulation as well as glial cell migration during eye development. Herein, we show that Pyr and Ths also exert key roles during the long-distance migration of a specific sub-population of mesodermal cells that migrate from the caudal visceral mesoderm within stereotypic bilateral paths along the trunk visceral mesoderm toward the anterior. These cells constitute the founder myoblasts of the longitudinal midgut muscles. In a forward genetic screen for regulators of this morphogenetic process we identified loss of function alleles for pyr. We show that pyr and ths are expressed along the paths of migration in the trunk visceral mesoderm and endoderm and act largely redundantly to help guide the founder myoblasts reliably onto and along their substrate of migration. Ectopically-provided Pyr and Ths signals can efficiently re-rout the migrating cells, both in the presence and absence of endogenous signals. Our data indicate that the guidance functions of these FGFs must act in concert with other important attractive or adhesive activities of the trunk visceral mesoderm. Apart from their guidance functions, the Pyr and Ths signals play an obligatory role for the survival of the migrating cells. Without these signals, essentially all of these cells enter cell death and detach from the migration substrate during early migration. We present experiments that allowed us to dissect the roles of these FGFs as guidance cues versus trophic activities during the migration of the longitudinal visceral muscle founders. PMID:22609944

Kinesins have a dual function in organizing microtubules during both tip growth and cytokinesis in Physcomitrella patens.

PubMed

Hiwatashi, Yuji; Sato, Yoshikatsu; Doonan, John H

2014-03-01

Microtubules (MTs) play a crucial role in the anisotropic deposition of cell wall material, thereby affecting the direction of growth. A wide range of tip-growing cells display highly polarized cell growth, and MTs have been implicated in regulating directionality and expansion. However, the molecular machinery underlying MT dynamics in tip-growing plant cells remains unclear. Here, we show that highly dynamic MT bundles form cyclically in the polarized expansion zone of the moss Physcomitrella patens caulonemal cells through the coalescence of growing MT plus ends. Furthermore, the plant-specific kinesins (KINID1) that are is essential for the proper MT organization at cytokinesis also regulate the turnover of the tip MT bundles as well as the directionality and rate of cell growth. The plus ends of MTs grow toward the expansion zone, and KINID1 is necessary for the stability of a single coherent focus of MTs in the center of the zone, whose formation coincides with the accumulation of KINID1. We propose that KINID-dependent MT bundling is essential for the correct directionality of growth as well as for promoting growth per se. Our findings indicate that two localized cell wall deposition processes, tip growth and cytokinesis, previously believed to be functionally and evolutionarily distinct, share common and plant-specific MT regulatory components.

Chemokine-Dependent pH Elevation at the Cell Front Sustains Polarity in Directionally Migrating Zebrafish Germ Cells.

PubMed

Tarbashevich, Katsiaryna; Reichman-Fried, Michal; Grimaldi, Cecilia; Raz, Erez

2015-04-20

Directional cell migration requires cell polarization with respect to the distribution of the guidance cue. Cell polarization often includes asymmetric distribution of response components as well as elements of the motility machinery. Importantly, the function and regulation of most of these molecules are known to be pH dependent. Intracellular pH gradients were shown to occur in certain cells migrating in vitro, but the functional relevance of such gradients for cell migration and for the response to directional cues, particularly in the intact organism, is currently unknown. In this study, we find that primordial germ cells migrating in the context of the developing embryo respond to the graded distribution of the chemokine Cxcl12 by establishing elevated intracellular pH at the cell front. We provide insight into the mechanisms by which a polar pH distribution contributes to efficient cell migration. Specifically, we show that Carbonic Anhydrase 15b, an enzyme controlling the pH in many cell types, including metastatic cancer cells, is expressed in migrating germ cells and is crucial for establishing and maintaining an asymmetric pH distribution within them. Reducing the level of the protein and thereby erasing the pH elevation at the cell front resulted in abnormal cell migration and impaired arrival at the target. The basis for the disrupted migration is found in the stringent requirement for pH conditions in the cell for regulating contractility, for the polarization of Rac1 activity, and hence for the formation of actin-rich structures at the leading edge of the migrating cells. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of the proliferation and acceleration of migration of vascular endothelial cells by increased cysteine-rich motor neuron 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakashima, Yukiko; Morimoto, Mayuka; Toda, Ken-ichi

2015-07-03

Cysteine-rich motor neuron 1 (CRIM1) is upregulated only in extracellular matrix gels by angiogenic factors such as vascular endothelial growth factor (VEGF). It then plays a critical role in the tube formation of endothelial cells. In the present study, we investigated the effects of increased CRIM1 on other endothelial functions such as proliferation and migration. Knock down of CRIM1 had no effect on VEGF-induced proliferation or migration of human umbilical vein endothelial cells (HUVECs), indicating that basal CRIM1 is not involved in the proliferation or migration of endothelial cells. Stable CRIM1-overexpressing endothelial F-2 cells, termed CR1 and CR2, were constructed,more » because it was difficult to prepare monolayer HUVECs that expressed high levels of CRIM1. Proliferation was reduced and migration was accelerated in both CR1 and CR2 cells, compared with normal F-2 cells. Furthermore, the transient overexpression of CRIM1 resulted in decreased proliferation and increased migration of bovine aortic endothelial cells. In contrast, neither proliferation nor migration of COS-7 cells were changed by the overexpression of CRIM1. These results demonstrate that increased CRIM1 reduces the proliferation and accelerates the migration of endothelial cells. These CRIM1 effects might contribute to tube formation of endothelial cells. CRIM1 induced by angiogenic factors may serve as a regulator in endothelial cells to switch from proliferating cells to morphological differentiation. - Highlights: • CRIM1 was upregulated only in tubular endothelial cells, but not in monolayers. • Increased CRIM1 reduced the proliferation of endothelial cells. • Increased CRIM1 accelerated the migration of endothelial cells. • Increased CRIM1 had no effect on the proliferation or migration of COS-7 cells.« less

[Overexpression of inhibitor of β-catenin and T cell factor (ICAT) promotes proliferation and migration of cervical cancer Caski cells].

PubMed

Jiang, Yayun; Wang, Ting; Wang, Jinshu; Xia, Jing; Gou, Liyao; Liu, Mengyao; Zhang, Yan

2016-11-01

Objective To investigate the effect of overexpressed inhibitor of β-catenin and T cell factor (ICAT) on the proliferation and migration of human cervical cancer Caski cells. Methods Caski cells were transfected with ICAT recombinant adenovirus (AdICAT). The levels of ICAT mRNA and protein were detected by quantitative real-time PCR (qRT-PCR) and Western blotting, respectively. Effect of ICAT overexpression on proliferation, cell cycle and migration in Caski cells was respectively evaluated by MTT assay, flow cytometry and Transwell TM migration assays. Results The expression of ICAT remarkably increased in Caski cells after AdICAT infection. Overexpression of ICAT promoted Caski cells' proliferation, arrested the cell cycle in the S phase and enhanced cell migration. Conclusion Overexpression of ICAT can promote the proliferation and migration of Caski cervical cancer cells.

Lipid phosphate phosphatase activity regulates dispersal and bilateral sorting of embryonic germ cells in Drosophila

PubMed Central

Renault, Andrew D.; Kunwar, Prabhat S.; Lehmann, Ruth

2010-01-01

In Drosophila, germ cell survival and directionality of migration are controlled by two lipid phosphate phosphatases (LPP), wunen (wun) and wunen-2 (wun2). wun wun2 double mutant analysis reveals that the two genes, hereafter collectively called wunens, act redundantly in primordial germ cells. We find that wunens mediate germ cell-germ cell repulsion and that this repulsion is necessary for germ cell dispersal and proper transepithelial migration at the onset of migration and for the equal sorting of the germ cells between the two embryonic gonads during their migration. We propose that this dispersal function optimizes adult fecundity by assuring maximal germ cell occupancy of both gonads. Furthermore, we find that the requirement for wunens in germ cell survival can be eliminated by blocking germ cell migration. We suggest that this essential function of Wunen is needed to maintain cell integrity in actively migrating germ cells. PMID:20431117

Sphingosine 1-phosphate and human ether-a'-go-go-related gene potassium channels modulate migration in human anaplastic thyroid cancer cells.

PubMed

Asghar, Muhammad Yasir; Viitanen, Tero; Kemppainen, Kati; Törnquist, Kid

2012-10-01

Anaplastic thyroid cancer (ATC) is the most aggressive form of human thyroid cancer, lacking any effective treatment. Sphingosine 1-phosphate (S1P) receptors and human ether-a'-go-go-related gene (HERG (KCNH2)) potassium channels are important modulators of cell migration. In this study, we have shown that the S1P(1-3) receptors are expressed in C643 and THJ-16T human ATC cell lines, both at mRNA and protein level. S1P inhibited migration of these cells and of follicular FTC-133 thyroid cancer cells. Using the S1P(1,3) inhibitor VPC-23019, the S1P(2) inhibitor JTE-013, and the S1P(2) receptor siRNA, we showed that the effect was mediated through S1P(2). Treatment of the cells with the Rho inhibitor C3 transferase abolished the effect of S1P on migration. S1P attenuated Rac activity, and inhibiting Rac decreased migration. Sphingosine kinase inhibitor enhanced basal migration of cells, and addition of exogenous S1P inhibited migration. C643 cells expressed a nonconducting HERG protein, and S1P decreased HERG protein expression. The HERG blocker E-4031 decreased migration. Interestingly, downregulating HERG protein with siRNA decreased the basal migration. In experiments using HEK cells overexpressing HERG, we showed that S1P decreased channel protein expression and current and that S1P attenuated migration of the cells. We conclude that S1P attenuates migration of C643 ATC cells by activating S1P(2) and the Rho pathway. The attenuated migration is also, in part, dependent on a S1P-induced decrease of HERG protein.

Probing Leader Cells in Endothelial Collective Migration by Plasma Lithography Geometric Confinement

PubMed Central

Yang, Yongliang; Jamilpour, Nima; Yao, Baoyin; Dean, Zachary S.; Riahi, Reza; Wong, Pak Kin

2016-01-01

When blood vessels are injured, leader cells emerge in the endothelium to heal the wound and restore the vasculature integrity. The characteristics of leader cells during endothelial collective migration under diverse physiological conditions, however, are poorly understood. Here we investigate the regulation and function of endothelial leader cells by plasma lithography geometric confinement generated. Endothelial leader cells display an aggressive phenotype, connect to follower cells via peripheral actin cables and discontinuous adherens junctions, and lead migrating clusters near the leading edge. Time-lapse microscopy, immunostaining, and particle image velocimetry reveal that the density of leader cells and the speed of migrating clusters are tightly regulated in a wide range of geometric patterns. By challenging the cells with converging, diverging and competing patterns, we show that the density of leader cells correlates with the size and coherence of the migrating clusters. Collectively, our data provide evidence that leader cells control endothelial collective migration by regualting the migrating clusters. PMID:26936382

Probing Leader Cells in Endothelial Collective Migration by Plasma Lithography Geometric Confinement.

PubMed

Yang, Yongliang; Jamilpour, Nima; Yao, Baoyin; Dean, Zachary S; Riahi, Reza; Wong, Pak Kin

2016-03-03

When blood vessels are injured, leader cells emerge in the endothelium to heal the wound and restore the vasculature integrity. The characteristics of leader cells during endothelial collective migration under diverse physiological conditions, however, are poorly understood. Here we investigate the regulation and function of endothelial leader cells by plasma lithography geometric confinement generated. Endothelial leader cells display an aggressive phenotype, connect to follower cells via peripheral actin cables and discontinuous adherens junctions, and lead migrating clusters near the leading edge. Time-lapse microscopy, immunostaining, and particle image velocimetry reveal that the density of leader cells and the speed of migrating clusters are tightly regulated in a wide range of geometric patterns. By challenging the cells with converging, diverging and competing patterns, we show that the density of leader cells correlates with the size and coherence of the migrating clusters. Collectively, our data provide evidence that leader cells control endothelial collective migration by regualting the migrating clusters.

Proximal Corporal Perforation During Penile Prosthesis Surgery: Prevention, Recognition, and Review of Historical and Novel Management Strategies.

PubMed

Pearlman, Amy M; Terlecki, Ryan P

2018-05-02

Proximal corporal perforation at time of dilation, although rare, may occur due to factors related to patient anatomy, presence of intra-cavernosal fibrosis, and/or surgical technique. To describe tools and techniques designed to prevent and identify proximal corporal perforation, and maneuvers to minimize the risk of subsequent cylinder migration once proximal perforation has been recognized, such that the operation may proceed and result in an acceptable outcome. We discuss tips for prevention, recognition, and management of proximal corporal perforation by presenting a review of the literature as well as our preferences based on a high-volume experience with penile prosthesis surgery. Described techniques aim to minimize risk of cylinder migration in the absence of true proximal repair. Although proximal perforation may be obvious at times, particularly with a sudden loss of resistance during dilation, discrepant corporal measurements and/or dissimilar proximal deflection of the dilator should also increase the index of suspicion. Numerous techniques have been employed to theoretically reduce the risk of cylinder migration in the setting of proximal corporal perforation. These include formal corporal repair (historical), windsock repairs with non-absorbable grafts, absorbable plugs, and suture fixation of the rear tip extender or shod material covering implant tubing. Intra-operative recognition of proximal corporal perforation, coupled with understanding of surgical strategies to minimize the risk of future device migration, may allow completion of an operation that still results in an optimal outcome. Techniques described to prevent proximal migration are not strongly evidence-based, but rooted in logic and supported by high-volume implanters. Intra-operative perforation of the proximal corpora, although rare, can threaten the success of penile implant surgery, though the techniques described herein have been developed to mitigate the potential for subsequent device migration, allowing surgery to proceed and to achieve the desired clinical result. Pearlman AM, Terlecki RP. Proximal Corporal Perforation During Penile Prosthesis Surgery: Prevention, Recognition, and Review of Historical and Novel Management Strategies. J Sex Med 2018;XX:XXX-XXX. Copyright © 2018 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

Directional cell migration in an extracellular pH gradient: a model study with an engineered cell line and primary microvascular endothelial cells.

PubMed

Paradise, Ranjani K; Whitfield, Matthew J; Lauffenburger, Douglas A; Van Vliet, Krystyn J

2013-02-15

Extracellular pH (pH(e)) gradients are characteristic of tumor and wound environments. Cell migration in these environments is critical to tumor progression and wound healing. While it has been shown previously that cell migration can be modulated in conditions of spatially invariant acidic pH(e) due to acid-induced activation of cell surface integrin receptors, the effects of pH(e) gradients on cell migration remain unknown. Here, we investigate cell migration in an extracellular pH(e) gradient, using both model α(v)β(3) CHO-B2 cells and primary microvascular endothelial cells. For both cell types, we find that the mean cell position shifts toward the acidic end of the gradient over time, and that cells preferentially polarize toward the acidic end of the gradient during migration. We further demonstrate that cell membrane protrusion stability and actin-integrin adhesion complex formation are increased in acidic pH(e), which could contribute to the preferential polarization toward acidic pH(e) that we observed for cells in pH(e) gradients. These results provide the first demonstration of preferential cell migration toward acid in a pH(e) gradient, with intriguing implications for directed cell migration in the tumor and wound healing environments. Copyright © 2012 Elsevier Inc. All rights reserved.

A three-dimensional gravity study of the 95.5°W propagating rift in the Galapagos spreading center

NASA Astrophysics Data System (ADS)

Phipps Morgan, Jason; Parmentier, E. M.

1987-01-01

Seafloor at the Galapagos 95.5°W propagating rift (PR) has a varied morphological expression that can be spatially correlated with the predicted kinematic history of the PR. A median valley-like depression occurs near the tip of the growing ridge axis. To test if this bathymetry is a dynamic feature supported by mantle or lithosphere strength or if it is due to isostatically compensated crustal thickness variations, we use three-dimensional gravity modelling to constrain the crustal structure in this region, from data collected by Hey in 1979 and 1982. The gravity anomaly at the PR tip depression suggests that the tip depression is not caused by crustal thinning. The data are consistent with a stress-supported PR tip depression caused by asthenospheric along-axis flow into the growing ridge axis (Phipps Morgan and Parmentier [1]). In contrast to the tip depression, seafloor in the sheared zone of material transferred through transform migration from the Cocos to Nazca plate is anomalously shallow and has a pronounced regional 300-400 m tilt towards the growing ridge axis over the 20 km width of the sheared zone. The gravity data also suggest that the sheared zone is not compensated by crustal thickening.

ERP44 inhibits human lung cancer cell migration mainly via IP3R2.

PubMed

Huang, Xue; Jin, Meng; Chen, Ying-Xiao; Wang, Jun; Zhai, Kui; Chang, Yan; Yuan, Qi; Yao, Kai-Tai; Ji, Guangju

2016-06-01

Cancer cell migration is involved in tumour metastasis. However, the relationship between calcium signalling and cancer migration is not well elucidated. In this study, we used the human lung adenocarcinoma A549 cell line to examine the role of endoplasmic reticulum protein 44 (ERP44), which has been reported to regulate calcium release inside of the endoplasmic reticulum (ER), in cell migration. We found that the inositol 1,4,5-trisphosphate receptors (IP3Rs/ITPRs) inhibitor 2-APB significantly inhibited A549 cell migration by inhibiting cell polarization and pseudopodium protrusion, which suggests that Ca2+ is necessary for A549 cell migration. Similarly, the overexpression of ERP44 reduced intracellular Ca2+ release via IP3Rs, altered cell morphology and significantly inhibited the migration of A549 cells. These phenomena were primarily dependent on IP3R2 because wound healing in A549 cells with IP3R2 rather than IP3R1 or IP3R3 siRNA was markedly inhibited. Moreover, the overexpression of ERP44 did not affect the migration of the human neuroblastoma cell line SH-SY5Y, which mainly expresses IP3R1. Based on the above observations, we conclude that ERP44 regulates A549 cell migration mainly via an IP3R2-dependent pathway.

ERP44 inhibits human lung cancer cell migration mainly via IP3R2

PubMed Central

Zhai, Kui; Chang, Yan; Yuan, Qi; Yao, Kai-Tai; Ji, Guangju

2016-01-01

Cancer cell migration is involved in tumour metastasis. However, the relationship between calcium signalling and cancer migration is not well elucidated. In this study, we used the human lung adenocarcinoma A549 cell line to examine the role of endoplasmic reticulum protein 44 (ERP44), which has been reported to regulate calcium release inside of the endoplasmic reticulum (ER), in cell migration. We found that the inositol 1,4,5-trisphosphate receptors (IP3Rs/ITPRs) inhibitor 2-APB significantly inhibited A549 cell migration by inhibiting cell polarization and pseudopodium protrusion, which suggests that Ca2+ is necessary for A549 cell migration. Similarly, the overexpression of ERP44 reduced intracellular Ca2+ release via IP3Rs, altered cell morphology and significantly inhibited the migration of A549 cells. These phenomena were primarily dependent on IP3R2 because wound healing in A549 cells with IP3R2 rather than IP3R1 or IP3R3 siRNA was markedly inhibited. Moreover, the overexpression of ERP44 did not affect the migration of the human neuroblastoma cell line SH-SY5Y, which mainly expresses IP3R1. Based on the above observations, we conclude that ERP44 regulates A549 cell migration mainly via an IP3R2-dependent pathway. PMID:27347718

Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour

PubMed Central

Wynn, Michelle L.; Kulesa, Paul M.; Schnell, Santiago

2012-01-01

Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell–cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell–cell contact. PMID:22219399

The mechanisms of substance P-mediated migration of bone marrow-derived mesenchymal stem cell-like ST2 cells.

PubMed

Dubon, Maria Jose; Park, Ki-Sook

2016-04-01

Substance P (SP) is known to induce the mobilization of bone marrow-derived mesenchymal stem cells (BM-MSCs) and thus participates in wound repair. However, the cellular and molecular mechanisms responsible for the SP-mediated migration of BM-MSCs were not fully understood. In the present study, we studied the molecular mechanisms that mediate the migration of the BM-derived MSC-like cell line ST2 in response to SP. Using a migration assay and western blot analysis, we noted that SP induced the chemotactic migration of ST2 cells through the intrinsic activation of extracellular signal-regulated kinases (ERKs) and protein kinase B (Akt), the phosphorylated expression levels of which were increased. We noted that Src is involved in the SP-mediated migration of ST2 cells and that focal adhesion kinase (FAK) was activated in the ST2 cells following SP treatment. Membrane ruffling increased in the ST2 cells after SP treatment, as was clearly demonstrated by immunocytochemical analysis. Importantly, using a blocking antibody against N-cadherin (GC-4), we studied cell migration and noted that SP mediated the migration of the ST2 cells through N-cadherin. The present study thus advanced our understanding of the mechanisms through which SP induces BM-MSC migration.

Light Activated Cell Migration in Synthetic Extracellular Matrices

PubMed Central

Guo, Qiongyu; Wang, Xiaobo; Tibbitt, Mark W.; Anseth, Kristi S.; Montell, Denise J.; Elisseeff, Jennifer H.

2012-01-01

Synthetic extracellular matrices provide a framework in which cells can be exposed to defined physical and biological cues. However no method exists to manipulate single cells within these matrices. It is desirable to develop such methods in order to understand fundamental principles of cell migration and define conditions that support or inhibit cell movement within these matrices. Here, we present a strategy for manipulating individual mammalian stem cells in defined synthetic hydrogels through selective optical activation of Rac, which is an intracellular signaling protein that plays a key role in cell migration. Photoactivated cell migration in synthetic hydrogels depended on mechanical and biological cues in the biomaterial. Real-time hydrogel photodegradation was employed to create geometrically defined channels and spaces in which cells could be photoactivated to migrate. Cell migration speed was significantly higher in the photo-etched channels and cells could easily change direction of movement compared to the bulk hydrogels. PMID:22889487

Phosphorylation of WAVE2 by MAP kinases regulates persistent cell migration and polarity

PubMed Central

Danson, Christopher M.; Pocha, Shirin M.; Bloomberg, Graham B.; Cory, Giles O.

2009-01-01

Summary The WAVE family of proteins has long been implicated in the stimulus-dependent generation of lamellipodia at the leading edge of migrating cells, with WAVE2 in particular implicated in the formation of peripheral ruffles and chemotactic migration. However, the lack of direct visualisation of cell migration in WAVE2 mutants or knockdowns has made defining the mechanisms of WAVE2 regulation during cell migration difficult. We have characterised three MAP kinase phosphorylation sites within WAVE2 and analysed fibroblast behaviour in a scratch-wound model following introduction of transgenes encoding phospho-defective WAVE2. The cells exhibited an increase in migration speed, a decrease in the persistence of migration, and disruption of polarisation of the Golgi apparatus. All these effects could be mimicked by acute knockdown of endogenous WAVE2 expression with RNAi, indicating that phosphorylation of WAVE2 by MAP kinases regulates cell polarity during migration. PMID:18032787

Phosphorylation of WAVE2 by MAP kinases regulates persistent cell migration and polarity.

PubMed

Danson, Christopher M; Pocha, Shirin M; Bloomberg, Graham B; Cory, Giles O

2007-12-01

The WAVE family of proteins has long been implicated in the stimulus-dependent generation of lamellipodia at the leading edge of migrating cells, with WAVE2 in particular implicated in the formation of peripheral ruffles and chemotactic migration. However, the lack of direct visualisation of cell migration in WAVE2 mutants or knockdowns has made defining the mechanisms of WAVE2 regulation during cell migration difficult. We have characterised three MAP kinase phosphorylation sites within WAVE2 and analysed fibroblast behaviour in a scratch-wound model following introduction of transgenes encoding phospho-defective WAVE2. The cells exhibited an increase in migration speed, a decrease in the persistence of migration, and disruption of polarisation of the Golgi apparatus. All these effects could be mimicked by acute knockdown of endogenous WAVE2 expression with RNAi, indicating that phosphorylation of WAVE2 by MAP kinases regulates cell polarity during migration.

Golgi polarization plays a role in the directional migration of neonatal dermal fibroblasts induced by the direct current electric fields.

PubMed

Kim, Min Sung; Lee, Mi Hee; Kwon, Byeong-Ju; Koo, Min-Ah; Seon, Gyeung Mi; Park, Jong-Chul

2015-05-01

Directional cell migration requires cell polarization. The reorganization of the Golgi apparatus is an important phenomenon in the polarization and migration of many types of cells. Direct current electric fields (dc (EF) induced directional cell migration in a wide variety of cells. Here nHDFs migrated toward cathode under 1 V/cm dc EF, however 1 μM of brefeldin A (BFA) inhibited the dc EF induced directional migration. BFA (1 μM) did not cause the complete Golgi dispersal for 2 h. When the Golgi polarization maintained their direction of polarity, the direction of cell migration also kept toward the same direction of the Golgi polarization even though the dc EF was reversed. In this study, the importance of the Golgi polarization in the directional migration of nHDf under dc EF was identified. Copyright © 2015 Elsevier Inc. All rights reserved.

Systemic control of cell division and endoreduplication by NAA and BAP by modulating CDKs in root tip cells of Allium cepa.

PubMed

Tank, Jigna G; Thaker, Vrinda S

2014-01-01

Molecular mechanism regulated by auxin and cytokinin during endoreduplication, cell division, and elongation process is studied by using Allium cepa roots as a model system. The activity of CDK genes modulated by auxin and cytokinin during cell division, elongation, and endoreduplication process is explained in this research work. To study the significance of auxin and cytokinin in the management of cell division and endoreduplication process in plant meristematic cells at molecular level endoreduplication was developed in root tips of Allium cepa by giving colchicine treatment. There were inhibition of vegetative growth, formation of c-tumor at root tip, and development of endoreduplicated cells after colchicine treatment. This c-tumor was further treated with NAA and BAP to reinitiate vegetative growth in roots. BAP gave positive response in reinitiation of vegetative growth of roots from center of c-tumor. However, NAA gave negative response in reinitiation of vegetative growth of roots from c-tumor. Further, CDKs gene expression analysis from normal, endoreduplicated, and phytohormone (NAA or BAP) treated root tip was done and remarkable changes in transcription level of CDK genes in normal, endoreduplicated, and phytohormones treated cells were observed.

Systemic Control of Cell Division and Endoreduplication by NAA and BAP by Modulating CDKs in Root Tip Cells of Allium cepa

PubMed Central

Tank, Jigna G.; Thaker, Vrinda S.

2014-01-01

Molecular mechanism regulated by auxin and cytokinin during endoreduplication, cell division, and elongation process is studied by using Allium cepa roots as a model system. The activity of CDK genes modulated by auxin and cytokinin during cell division, elongation, and endoreduplication process is explained in this research work. To study the significance of auxin and cytokinin in the management of cell division and endoreduplication process in plant meristematic cells at molecular level endoreduplication was developed in root tips of Allium cepa by giving colchicine treatment. There were inhibition of vegetative growth, formation of c-tumor at root tip, and development of endoreduplicated cells after colchicine treatment. This c-tumor was further treated with NAA and BAP to reinitiate vegetative growth in roots. BAP gave positive response in reinitiation of vegetative growth of roots from center of c-tumor. However, NAA gave negative response in reinitiation of vegetative growth of roots from c-tumor. Further, CDKs gene expression analysis from normal, endoreduplicated, and phytohormone (NAA or BAP) treated root tip was done and remarkable changes in transcription level of CDK genes in normal, endoreduplicated, and phytohormones treated cells were observed. PMID:24955358

Long-term in vivo single-cell tracking reveals the switch of migration patterns in adult-born juxtaglomerular cells of the mouse olfactory bulb

PubMed Central

Liang, Yajie; Li, Kaizhen; Riecken, Kristoffer; Maslyukov, Anatoliy; Gomez-Nicola, Diego; Kovalchuk, Yury; Fehse, Boris; Garaschuk, Olga

2016-01-01

The behavior of adult-born cells can be easily monitored in cell culture or in lower model organisms, but longitudinal observation of individual mammalian adult-born cells in their native microenvironment still proves to be a challenge. Here we have established an approach named optical cell positioning system for long-term in vivo single-cell tracking, which integrates red-green-blue cell labeling with repeated angiography. By combining this approach with in vivo two-photon imaging technique, we characterized the in vivo migration patterns of adult-born neurons in the olfactory bulb. In contrast to the traditional view of mere radial migration of adult-born cells within the bulb, we found that juxtaglomerular cells switch from radial migration to long distance lateral migration upon arrival in their destination layer. This unique long-distance lateral migration has characteristic temporal (stop-and-go) and spatial (migratory, unidirectional or multidirectional) patterns, with a clear cell age-dependent decrease in the migration speed. The active migration of adult-born cells coincides with the time period of initial fate determination and is likely to impact on the integration sites of adult-born cells, their odor responsiveness, as well as their survival rate. PMID:27174051

Chlorambucil (nitrogen mustard) induced impairment of early vascular endothelial cell migration - effects of α-linolenic acid and N-acetylcysteine.

PubMed

Steinritz, Dirk; Schmidt, Annette; Simons, Thilo; Ibrahim, Marwa; Morguet, Christian; Balszuweit, Frank; Thiermann, Horst; Kehe, Kai; Bloch, Wilhelm; Bölck, Birgit

2014-08-05

Alkylating agents (e.g. sulfur and nitrogen mustards) cause a variety of cell and tissue damage including wound healing disorder. Migration of endothelial cells is of utmost importance for effective wound healing. In this study we investigated the effects of chlorambucil (a nitrogen mustard) on early endothelial cells (EEC) with special focus on cell migration. Chlorambucil significantly inhibited migration of EEC in Boyden chamber and wound healing experiments. Cell migration is linked to cytoskeletal organization. We therefore investigated the distribution pattern of the Golgi apparatus as a marker of cell polarity. Cells are polarized under control conditions, whereas chlorambucil caused an encircling perinuclear position of the Golgi apparatus, indicating non-polarized cells. ROS are discussed to be involved in the pathophysiology of alkylating substances and are linked to cell migration and cell polarity. Therefore we investigated the influence of ROS-scavengers (α-linolenic acid (ALA) and N-acetylcysteine (NAC)) on the impaired EEC migration. Both substances, in particular ALA, improved EEC migration. Notably ALA restored cell polarity. Remarkably, investigations of ROS and RNS biomarkers (8-isoprostane and nitrotyrosine) did not reveal a significant increase after chlorambucil exposure when assessed 24h post exposure. A distinct breakdown of mitochondrial membrane potential (measured by TMRM) that recovered under ALA treatment was observed. In conclusion our results provide compelling evidence that the alkylating agent chlorambucil dramatically impairs directed cellular migration, which is accompanied by perturbations of cell polarity and mitochondrial membrane potential. ALA treatment was able to reconstitute cell polarity and to stabilize mitochondrial potential resulting in improved cell migration. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

3D cancer cell migration in a confined matrix

NASA Astrophysics Data System (ADS)

Alobaidi, Amani; Sun, Bo

Cancer cell migration is widely studied in 2D motion, which does not mimic the invasion processes in vivo. More recently, 3D cell migration studies have been performed. The ability of cancer cells to migrate within the extracellular matrix depends on the physical and biochemical features of the extracellular matrix. We present a model of cell motility in confined matrix geometry. The aim of the study is to study cancer migration in collagen matrix, as a soft tissue, to investigate their motility within the confined and surrounding collagen environment. Different collagen concentrations have been used to show the ability of these cancer cells to move through such a complex structure by measuring Cancer cell migration velocity as well as the displacement. Graduate student physics department.

Polyamine-dependent migration of retinal pigment epithelial cells.

PubMed

Johnson, Dianna A; Fields, Carolyn; Fallon, Amy; Fitzgerald, Malinda E C; Viar, Mary Jane; Johnson, Leonard R

2002-04-01

Migration of retinal pigment epithelial (RPE) cells can be triggered by disruption of the RPE monolayer or injury to the neural retina. Migrating cells may re-establish a confluent monolayer, or they may invade the neural retina and disrupt visual function. The purpose of this study was to examine the role of endogenous polyamines in mechanisms of RPE migration. Endogenous polyamine levels were determined in an immortalized RPE cell line, D407, using HPLC. Activities of the two rate-limiting enzymes for polyamine synthesis, ornithine decarboxylase (ODC), and S-adenosylmethionine decarboxylase (SAMdc), were measured by liberation of ((14)CO(2))(.) Migration was assessed in confluent cultures by determining the number of cells migrating into a mechanically denuded area. All measurements were obtained both in control cultures and in cultures treated with synthesis inhibitors that deplete endogenous polyamines. Subcellular localization of endogenous polyamines was determined using a polyamine antibody. The polyamines, spermidine and spermine, as well as their precursor, putrescine, were normal constituents of RPE cells. The two rate-limiting synthetic enzymes were also present, and their activities were stimulated dramatically by addition of serum to the culture medium. Cell migration was similarly stimulated by serum exposure. When endogenous polyamines were depleted, migration was blocked. When polyamines were replenished through uptake, migration was restored. Polyamine immunoreactivity was limited to membrane patches in quiescent cells. In actively migrating and dividing cells, immunoreactivity was enhanced throughout the cytoplasm. Polyamines are essential for RPE migration. Pharmacologic manipulation of the polyamine pathway could provide a therapeutic strategy for regulating anomalous migration.

The Caenorhabditis elegans Q neuroblasts: A powerful system to study cell migration at single-cell resolution in vivo.

PubMed

Rella, Lorenzo; Fernandes Póvoa, Euclides E; Korswagen, Hendrik C

2016-04-01

During development, cell migration plays a central role in the formation of tissues and organs. Understanding the molecular mechanisms that drive and control these migrations is a key challenge in developmental biology that will provide important insights into disease processes, including cancer cell metastasis. In this article, we discuss the Caenorhabditis elegans Q neuroblasts and their descendants as a tool to study cell migration at single-cell resolution in vivo. The highly stereotypical migration of these cells provides a powerful system to study the dynamic cytoskeletal processes that drive migration as well as the evolutionarily conserved signaling pathways (including different Wnt signaling cascades) that guide the cells along their specific trajectories. Here, we provide an overview of what is currently known about Q neuroblast migration and highlight the live-cell imaging, genome editing, and quantitative gene expression techniques that have been developed to study this process. © 2016 Wiley Periodicals, Inc.

Loss of Sip1 leads to migration defects and retention of ectodermal markers during lens development.

PubMed

Manthey, Abby L; Lachke, Salil A; FitzGerald, Paul G; Mason, Robert W; Scheiblin, David A; McDonald, John H; Duncan, Melinda K

2014-02-01

SIP1 encodes a DNA-binding transcription factor that regulates multiple developmental processes, as highlighted by the pleiotropic defects observed in Mowat-Wilson syndrome, which results from mutations in this gene. Further, in adults, dysregulated SIP1 expression has been implicated in both cancer and fibrotic diseases, where it functionally links TGFβ signaling to the loss of epithelial cell characteristics and gene expression. In the ocular lens, an epithelial tissue important for vision, Sip1 is co-expressed with epithelial markers, such as E-cadherin, and is required for the complete separation of the lens vesicle from the head ectoderm during early ocular morphogenesis. However, the function of Sip1 after early lens morphogenesis is still unknown. Here, we conditionally deleted Sip1 from the developing mouse lens shortly after lens vesicle closure, leading to defects in coordinated fiber cell tip migration, defective suture formation, and cataract. Interestingly, RNA-Sequencing analysis on Sip1 knockout lenses identified 190 differentially expressed genes, all of which are distinct from previously described Sip1 target genes. Furthermore, 34% of the genes with increased expression in the Sip1 knockout lenses are normally downregulated as the lens transitions from the lens vesicle to early lens, while 49% of the genes with decreased expression in the Sip1 knockout lenses are normally upregulated during early lens development. Overall, these data imply that Sip1 plays a major role in reprogramming the lens vesicle away from a surface ectoderm cell fate towards that necessary for the development of a transparent lens and demonstrate that Sip1 regulates distinctly different sets of genes in different cellular contexts. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Loss of Sip1 leads to migration defects and retention of ectodermal markers during lens development

PubMed Central

Manthey, Abby L.; Lachke, Salil A.; FitzGerald, Paul G.; Mason, Robert W.; Scheiblin, David A.; McDonald, John H.; Duncan, Melinda K.

2014-01-01

SIP1 encodes a DNA-binding transcription factor that regulates multiple developmental processes, as highlighted by the pleiotropic defects observed in Mowat-Wilson Syndrome, which results from mutations in this gene. Further, in adults, dysregulated SIP1 expression has been implicated in both cancer and fibrotic diseases, where it functionally links TGFβ signaling to the loss of epithelial cell characteristics and gene expression. In the ocular lens, an epithelial tissue important for vision, Sip1 is co-expressed with epithelial markers, such as E-cadherin, and is required for the complete separation of the lens vesicle from the head ectoderm during early ocular morphogenesis. However, the function of Sip1 after early lens morphogenesis is still unknown. Here, we conditionally deleted Sip1 from the developing mouse lens shortly after lens vesicle closure, leading to defects in coordinated fiber cell tip migration, defective suture formation, and cataract. Interestingly, RNA-Sequencing analysis on Sip1 knockout lenses identified 190 differentially expressed genes, all of which are distinct from previously described Sip1 target genes. Furthermore, 34% of the genes with increased expression in the Sip1 knockout lenses are normally downregulated as the lens transitions from the lens vesicle to early lens, while 49% of the genes with decreased expression in the Sip1 knockout lenses are normally upregulated during early lens development. Overall, these data imply that Sip1 plays a major role in reprogramming the lens vesicle away from a surface ectoderm cell fate towards that necessary for the development of a transparent lens and demonstrate that Sip1 regulates distinctly different sets of genes in different cellular contexts. PMID:24161570

Cadherin-11 Mediates Contact Inhibition of Locomotion during Xenopus Neural Crest Cell Migration

PubMed Central

Becker, Sarah F. S.; Mayor, Roberto; Kashef, Jubin

2013-01-01

Collective cell migration is an essential feature both in embryonic development and cancer progression. The molecular mechanisms of these coordinated directional cell movements still need to be elucidated. The migration of cranial neural crest (CNC) cells during embryogenesis is an excellent model for collective cell migration in vivo. These highly motile and multipotent cells migrate directionally on defined routes throughout the embryo. Interestingly, local cell-cell interactions seem to be the key force for directionality. CNC cells can change their migration direction by a repulsive cell response called contact inhibition of locomotion (CIL). Cell protrusions collapse upon homotypic cell-cell contact and internal repolarization leads to formation of new protrusions toward cell-free regions. Wnt/PCP signaling was shown to mediate activation of small RhoGTPase RhoA and inhibition of cell protrusions at the contact side. However, the mechanism how a cell recognizes the contact is poorly understood. Here, we demonstrate that Xenopus cadherin-11 (Xcad-11) mediated cell-cell adhesion is necessary in CIL for directional and collective migration of CNC cells. Reduction of Xcad-11 adhesive function resulted in higher invasiveness of CNC due to loss of CIL. Additionally, transplantation analyses revealed that CNC migratory behaviour in vivo is non-directional and incomplete when Xcad-11 adhesive function is impaired. Blocking Wnt/PCP signaling led to similar results underlining the importance of Xcad-11 in the mechanism of CIL and directional migration of CNC. PMID:24392028

Constrained Adherable Area of Nanotopographic Surfaces Promotes Cell Migration through the Regulation of Focal Adhesion via Focal Adhesion Kinase/Rac1 Activation.

PubMed

Lim, Jiwon; Choi, Andrew; Kim, Hyung Woo; Yoon, Hyungjun; Park, Sang Min; Tsai, Chia-Hung Dylan; Kaneko, Makoto; Kim, Dong Sung

2018-05-02

Cell migration is crucial in physiological and pathological processes such as embryonic development and wound healing; such migration is strongly guided by the surrounding nanostructured extracellular matrix. Previous studies have extensively studied the cell migration on anisotropic nanotopographic surfaces; however, only a few studies have reported cell migration on isotropic nanotopographic surfaces. We herein, for the first time, propose a novel concept of adherable area on cell migration using isotropic nanopore surfaces with sufficient nanopore depth by adopting a high aspect ratio. As the pore size of the nanopore surface was controlled to 200, 300, and 400 nm in a fixed center-to-center distance of 480 nm, it produced 86, 68, and 36% of adherable area, respectively, on the fabricated surface. A meticulous investigation of the cell migration in response to changes in the constrained adherable area of the nanotopographic surface showed 1.4-, 1.5-, and 1.6-fold increase in migration speeds and a 1.4-, 2-, and 2.5-fold decrease in the number of focal adhesions as the adherable area was decreased to 86, 68, and 36%, respectively. Furthermore, a strong activation of FAK/Rac1 signaling was observed to be involved in the promoted cell migration. These results suggest that the reduced adherable area promotes cell migration through decreasing the FA formation, which in turn upregulates FAK/Rac1 activation. The findings in this study can be utilized to control the cell migration behaviors, which is a powerful tool in the research fields involving cell migration such as promoting wound healing and tissue repair.

A PML/Slit Axis Controls Physiological Cell Migration and Cancer Invasion in the CNS.

PubMed

Amodeo, Valeria; A, Deli; Betts, Joanne; Bartesaghi, Stefano; Zhang, Ying; Richard-Londt, Angela; Ellis, Matthew; Roshani, Rozita; Vouri, Mikaella; Galavotti, Sara; Oberndorfer, Sarah; Leite, Ana Paula; Mackay, Alan; Lampada, Aikaterini; Stratford, Eva Wessel; Li, Ningning; Dinsdale, David; Grimwade, David; Jones, Chris; Nicotera, Pierluigi; Michod, David; Brandner, Sebastian; Salomoni, Paolo

2017-07-11

Cell migration through the brain parenchyma underpins neurogenesis and glioblastoma (GBM) development. Since GBM cells and neuroblasts use the same migratory routes, mechanisms underlying migration during neurogenesis and brain cancer pathogenesis may be similar. Here, we identify a common pathway controlling cell migration in normal and neoplastic cells in the CNS. The nuclear scaffold protein promyelocytic leukemia (PML), a regulator of forebrain development, promotes neural progenitor/stem cell (NPC) and neuroblast migration in the adult mouse brain. The PML pro-migratory role is active also in transformed mouse NPCs and in human primary GBM cells. In both normal and neoplastic settings, PML controls cell migration via Polycomb repressive complex 2 (PRC2)-mediated repression of Slits, key regulators of axon guidance. Finally, a PML/SLIT1 axis regulates sensitivity to the PML-targeting drug arsenic trioxide in primary GBM cells. Taken together, these findings uncover a drug-targetable molecular axis controlling cell migration in both normal and neoplastic cells. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Quantitative Analysis of Cell Migration Using Optical Flow

PubMed Central

Boric, Katica; Orio, Patricio; Viéville, Thierry; Whitlock, Kathleen

2013-01-01

Neural crest cells exhibit dramatic migration behaviors as they populate their distant targets. Using a line of zebrafish expressing green fluorescent protein (sox10:EGFP) in neural crest cells we developed an assay to analyze and quantify cell migration as a population, and use it here to characterize in detail the subtle defects in cell migration caused by ethanol exposure during early development. The challenge was to quantify changes in the in vivo migration of all Sox10:EGFP expressing cells in the visual field of time-lapse movies. To perform this analysis we used an Optical Flow algorithm for motion detection and combined the analysis with a fit to an affine transformation. Through this analysis we detected and quantified significant differences in the cell migrations of Sox10:EGFP positive cranial neural crest populations in ethanol treated versus untreated embryos. Specifically, treatment affected migration by increasing the left-right asymmetry of the migrating cells and by altering the direction of cell movements. Thus, by applying this novel computational analysis, we were able to quantify the movements of populations of cells, allowing us to detect subtle changes in cell behaviors. Because cranial neural crest cells contribute to the formation of the frontal mass these subtle differences may underlie commonly observed facial asymmetries in normal human populations. PMID:23936049

Stimulation of Cortical Myosin Phosphorylation by p114RhoGEF Drives Cell Migration and Tumor Cell Invasion

PubMed Central

Zihni, Ceniz; Harris, Andrew R.; Bailly, Maryse; Charras, Guillaume T.; Balda, Maria S.; Matter, Karl

2012-01-01

Actinomyosin activity is an important driver of cell locomotion and has been shown to promote collective cell migration of epithelial sheets as well as single cell migration and tumor cell invasion. However, the molecular mechanisms underlying activation of cortical myosin to stimulate single cell movement, and the relationship between the mechanisms that drive single cell locomotion and those that mediate collective cell migration of epithelial sheets are incompletely understood. Here, we demonstrate that p114RhoGEF, an activator of RhoA that associates with non-muscle myosin IIA, regulates collective cell migration of epithelial sheets and tumor cell invasion. Depletion of p114RhoGEF resulted in specific spatial inhibition of myosin activation at cell-cell contacts in migrating epithelial sheets and the cortex of migrating single cells, but only affected double and not single phosphorylation of myosin light chain. In agreement, overall elasticity and contractility of the cells, processes that rely on persistent and more constant forces, were not affected, suggesting that p114RhoGEF mediates process-specific myosin activation. Locomotion was p114RhoGEF-dependent on Matrigel, which favors more roundish cells and amoeboid-like actinomyosin-driven movement, but not on fibronectin, which stimulates flatter cells and lamellipodia-driven, mesenchymal-like migration. Accordingly, depletion of p114RhoGEF led to reduced RhoA, but increased Rac activity. Invasion of 3D matrices was p114RhoGEF-dependent under conditions that do not require metalloproteinase activity, supporting a role of p114RhoGEF in myosin-dependent, amoeboid-like locomotion. Our data demonstrate that p114RhoGEF drives cortical myosin activation by stimulating myosin light chain double phosphorylation and, thereby, collective cell migration of epithelial sheets and amoeboid-like motility of tumor cells. PMID:23185572

Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes.

PubMed

Park, Dayoung; Brune, Kristin A; Mitra, Anupam; Marusina, Alina I; Maverakis, Emanual; Lebrilla, Carlito B

2015-11-01

Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Cancer cell migration within 3D layer-by-layer microfabricated photocrosslinked PEG scaffolds with tunable stiffness.

PubMed

Soman, Pranav; Kelber, Jonathan A; Lee, Jin Woo; Wright, Tracy N; Vecchio, Kenneth S; Klemke, Richard L; Chen, Shaochen

2012-10-01

Our current understanding of 3-dimensional (3D) cell migration is primarily based on results from fibrous scaffolds with randomly organized internal architecture. Manipulations that change the stiffness of these 3D scaffolds often alter other matrix parameters that can modulate cell motility independently or synergistically, making observations less predictive of how cells behave when migrating in 3D. In order to decouple microstructural influences and stiffness effects, we have designed and fabricated 3D polyethylene glycol (PEG) scaffolds that permit orthogonal tuning of both elastic moduli and microstructure. Scaffolds with log-pile architectures were used to compare the 3D migration properties of normal breast epithelial cells (HMLE) and Twist-transformed cells (HMLET). Our results indicate that the nature of cell migration is significantly impacted by the ability of cells to migrate in the third dimension. 2D ECM-coated PEG substrates revealed no statistically significant difference in cell migration between HMLE and HMLET cells among substrates of different stiffness. However, when cells were allowed to move along the third dimension, substantial differences were observed for cell displacement, velocity and path straightness parameters. Furthermore, these differences were sensitive to both substrate stiffness and the presence of the Twist oncogene. Importantly, these 3D modes of migration provide insight into the potential for oncogene-transformed cells to migrate within and colonize tissues of varying stiffness. Copyright © 2012 Elsevier Ltd. All rights reserved.

Modelling collective cell migration of neural crest

PubMed Central

Szabó, András; Mayor, Roberto

2016-01-01

Collective cell migration has emerged in the recent decade as an important phenomenon in cell and developmental biology and can be defined as the coordinated and cooperative movement of groups of cells. Most studies concentrate on tightly connected epithelial tissues, even though collective migration does not require a constant physical contact. Movement of mesenchymal cells is more independent, making their emergent collective behaviour less intuitive and therefore lending importance to computational modelling. Here we focus on such modelling efforts that aim to understand the collective migration of neural crest cells, a mesenchymal embryonic population that migrates large distances as a group during early vertebrate development. By comparing different models of neural crest migration, we emphasize the similarity and complementary nature of these approaches and suggest a future direction for the field. The principles derived from neural crest modelling could aid understanding the collective migration of other mesenchymal cell types. PMID:27085004

Modelling collective cell migration of neural crest.

PubMed

Szabó, András; Mayor, Roberto

2016-10-01

Collective cell migration has emerged in the recent decade as an important phenomenon in cell and developmental biology and can be defined as the coordinated and cooperative movement of groups of cells. Most studies concentrate on tightly connected epithelial tissues, even though collective migration does not require a constant physical contact. Movement of mesenchymal cells is more independent, making their emergent collective behaviour less intuitive and therefore lending importance to computational modelling. Here we focus on such modelling efforts that aim to understand the collective migration of neural crest cells, a mesenchymal embryonic population that migrates large distances as a group during early vertebrate development. By comparing different models of neural crest migration, we emphasize the similarity and complementary nature of these approaches and suggest a future direction for the field. The principles derived from neural crest modelling could aid understanding the collective migration of other mesenchymal cell types. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cellular and dendritic growth in a binary melt - A marginal stability approach

NASA Technical Reports Server (NTRS)

Laxmanan, V.

1986-01-01

A simple model for the constrained growth of an array of cells or dendrites in a binary alloy in the presence of an imposed positive temperature gradient in the liquid is proposed, with the dendritic or cell tip radius calculated using the marginal stability criterion of Langer and Muller-Krumbhaar (1977). This approach, an approach adopting the ad hoc assumption of minimum undercooling at the cell or dendrite tip, and an approach based on the stability criterion of Trivedi (1980) all predict tip radii to within 30 percent of each other, and yield a simple relationship between the tip radius and the growth conditions. Good agreement is found between predictions and data obtained in a succinonitrile-acetone system, and under the present experimental conditions, the dendritic tip stability parameter value is found to be twice that obtained previously, possibly due to a transition in morphology from a cellular structure with just a few side branches, to a more fully developed dendritic structure.

Microfluidic gradient device for studying mesothelial cell migration and the effect of chronic carbon nanotube exposure

NASA Astrophysics Data System (ADS)

Zhang, Hanyuan; Lohcharoenkal, Warangkana; Sun, Jianbo; Li, Xiang; Wang, Liying; Wu, Nianqiang; Rojanasakul, Yon; Liu, Yuxin

2015-07-01

Cell migration is one of the crucial steps in many physiological and pathological processes, including cancer development. Our recent studies have shown that carbon nanotubes (CNTs), similarly to asbestos, can induce accelerated cell growth and invasiveness that contribute to their mesothelioma pathogenicity. Malignant mesothelioma is a very aggressive tumor that develops from cells of the mesothelium, and is most commonly caused by exposure to asbestos. CNTs have a similar structure and mode of exposure to asbestos. This has raised a concern regarding the potential carcinogenicity of CNTs, especially in the pleural area which is a key target for asbestos-related diseases. In this paper, a static microfluidic gradient device was applied to study the migration of human pleural mesothelial cells which had been through a long-term exposure (4 months) to subcytotoxic concentration (0.02 µg cm-2) of single-walled CNTs (SWCNTs). Multiple migration signatures of these cells were investigated using the microfluidic gradient device for the first time. During the migration study, we observed that cell morphologies changed from flattened shapes to spindle shapes prior to their migration after their sensing of the chemical gradient. The migration of chronically SWCNT-exposed mesothelial cells was evaluated under different fetal bovine serum (FBS) concentration gradients, and the migration speeds and number of migrating cells were extracted and compared. The results showed that chronically SWCNT-exposed mesothelial cells are more sensitive to the gradient compared to non-SWCNT-exposed cells. The method described here allows simultaneous detection of cell morphology and migration under chemical gradient conditions, and also allows for real-time monitoring of cell motility that resembles in vivo cell migration. This platform would be much needed for supporting the development of more physiologically relevant cell models for better assessment and characterization of the mesothelioma hazard posed by nanomaterials.

RhoA and RhoC are involved in stromal cell-derived factor-1-induced cell migration by regulating F-actin redistribution and assembly.

PubMed

Luo, Jixian; Li, Dingyun; Wei, Dan; Wang, Xiaoguang; Wang, Lan; Zeng, Xianlu

2017-12-01

Stromal cell-derived factor-1 (SDF-1) signaling is important to the maintenance and progression of T-cell acute lymphoblastic leukemia by inducing chemotaxis migration. To identify the mechanism of SDF-1 signaling in the migration of T-ALL, Jurkat acute lymphoblastic leukemia cells were used. Results showed that SDF-1 induces Jurkat cell migration by F-actin redistribution and assembly, which is dependent on Rho activity. SDF-1 induced RhoA and RhoC activation, as well as reactive oxygen species (ROS) production, which was inhibited by Rho inhibitor. The Rho-dependent ROS production led to subsequent cytoskeleton redistribution and assembly in the process of migration. Additionally, RhoA and RhoC were involved in SDF-1-induced Jurkat cell migration. Taken together, we found a SDF-1/CXCR4-RhoA and RhoC-ROS-cytoskeleton pathway that regulates Jurkat cell migration in response to SDF-1. This work will contribute to a clearer insight into the migration mechanism of acute lymphoblastic leukemia.

Membrane-type matrix metalloproteinases mediate curcumin-induced cell migration in non-tumorigenic colon epithelial cells differing in Apc genotype.

PubMed

Fenton, Jenifer I; Wolff, Margaret S; Orth, Michael W; Hord, Norman G

2002-06-01

Colonic epithelial cell migration is required for normal differentiated cell function. This migratory phenotype is dependent upon wild-type adenomatous polyposis coli (Apc) expression. Non-tumorigenic murine colon epithelial cell lines with distinct Apc genotypes, i.e. young adult mouse colon (YAMC; Apc(+/+)) and immortomouse/Min colon epithelial (IMCE; Apc(Min/+) cells) were used to assess the association between the Apc genotype, cell motility and matrix metalloproteinase (MMP) activity. Cells were treated with epidermal growth factor (EGF; 1, 10 and 25 ng/ml), hepatocyte growth factor (HGF; 1, 10 and 25 ng/ml) and/or curcumin (0.1-100 microM). EGF (25 ng/ml) and HGF (25 ng/ml) induced a greater migratory response in YAMC compared with IMCE cells after 24 h (P < 0.05). Treatment with curcumin induced a greater or equivalent migratory response in IMCE than YAMC cells. When migrating cells were treated with Ilomastat (MMP inhibitor), migration was inhibited in both cell types. High concentrations of Ilomastat (25 and 50 microM) inhibited migration in both cell types, while low concentrations (10 microM) inhibited HGF-induced IMCE migration. Curcumin-induced migration was inhibited in both cell types at the highest concentration of Ilomastat (50 microM). Immuno-localization analysis of membrane type-1 (MT1)-MMP indicated that migration is associated with the redistribution of this protein from the endoplasmic reticulum to the plasma membrane. Addition of neutralizing polyclonal antibodies against MT1-MMP or a mixture of MT1, 2- and 3-MMPs demonstrated partial or complete inhibition of cell migration in both cell types, respectively. The data provide the first evidence that migration in non-tumorigenic murine colon epithelial cells is: (i) inducible by EGF and HGF in an Apc genotype-dependent manner, (ii) dependent on MT-MMP activity and (iii) inducible by curcumin in an Apc genotype-independent manner. The data suggest a potential mechanism by which curcumin may induce cells heterozygous for Apc to overcome defective cell migration, a phenotype associated with cell differentiation and apoptosis.

Quantitative impedimetric monitoring of cell migration under the stimulation of cytokine or anti-cancer drug in a microfluidic chip

PubMed Central

Xiao, Xia; Lei, Kin Fong; Huang, Chia-Hao

2015-01-01

Cell migration is a cellular response and results in various biological processes such as cancer metastasis, that is, the primary cause of death for cancer patients. Quantitative investigation of the correlation between cell migration and extracellular stimulation is essential for developing effective therapeutic strategies for controlling invasive cancer cells. The conventional method to determine cell migration rate based on comparison of successive images may not be an objective approach. In this work, a microfluidic chip embedded with measurement electrodes has been developed to quantitatively monitor the cell migration activity based on the impedimetric measurement technique. A no-damage wound was constructed by microfluidic phenomenon and cell migration activity under the stimulation of cytokine and an anti-cancer drug, i.e., interleukin-6 and doxorubicin, were, respectively, investigated. Impedance measurement was concurrently performed during the cell migration process. The impedance change was directly correlated to the cell migration activity; therefore, the migration rate could be calculated. In addition, a good match was found between impedance measurement and conventional imaging analysis. But the impedimetric measurement technique provides an objective and quantitative measurement. Based on our technique, cell migration rates were calculated to be 8.5, 19.1, and 34.9 μm/h under the stimulation of cytokine at concentrations of 0 (control), 5, and 10 ng/ml. This technique has high potential to be developed into a powerful analytical platform for cancer research. PMID:26180566

Downregulation of CD9 in Keratinocyte Contributes to Cell Migration via Upregulation of Matrix Metalloproteinase-9

PubMed Central

Jiang, Xu-pin; Zhang, Dong-xia; Teng, Miao; Zhang, Qiong; Zhang, Jia-ping; Huang, Yue-sheng

2013-01-01

Tetraspanin CD9 has been implicated in various cellular and physiological processes, including cell migration. In our previous study, we found that wound repair is delayed in CD9-null mice, suggesting that CD9 is critical for cutaneous wound healing. However, many cell types, including immune cells, endothelial cells, keratinocytes and fibroblasts undergo marked changes in gene expression and phenotype, leading to cell proliferation, migration and differentiation during wound repair, whether CD9 regulates kerationcytes migration directly remains unclear. In this study, we showed that the expression of CD9 was downregulated in migrating keratinocytes during wound repair in vivo and in vitro. Recombinant adenovirus vector for CD9 silencing or overexpressing was constructed and used to infect HaCaT cells. Using cell scratch wound assay and cell migration assay, we have also demonstrated that downregulation of CD9 promoted keratinocyte migration in vitro, whereas CD9 overexpression inhibited cell migration. Moreover, CD9 inversely regulated the activity and expression of MMP-9 in keratinocytes, which was involved in CD9-regulated keratinocyte migration. Importantly, CD9 silencing-activated JNK signaling was accompanied by the upregulation of MMP-9 activity and expression. Coincidentally, we found that SP600125, a JNK pathway inhibitor, decreased the activity and expression of MMP-9 of CD9-silenced HaCaT cells. Thus, our results suggest that CD9 is downregulated in migrating keratinocytes in vivo and in vitro, and a low level of CD9 promotes keratinocyte migration in vitro, in which the regulation of MMP-9 through the JNK pathway plays an important role. PMID:24147081

Cancer: fundamentals behind pH targeting and the double-edged approach

PubMed Central

Koltai, Tomas

2016-01-01

The highly regulated pH of cells and the less-regulated pH of the surrounding extracellular matrix (ECM) is the result of a delicate balance between metabolic processes and proton production, proton transportation, chemical buffering, and vascular removal of waste products. Malignant cells show a pronounced increase in metabolic processes where the 10- to 15-fold rise in glucose consumption is only the tip of the iceberg. Aerobic glycolysis (Warburg effect) is one of the hallmarks of cancer metabolism that implies excessive production of protons, which if stayed inside the cells would result in fatal intracellular acidosis (maintaining a strict acid–base balance is essential for the survival of eukaryotic cells). Malignant cells solve this problem by increasing mechanisms of proton transportation which expel the excess acidity. This allows cancer cells to keep a normal intracellular pH, or even overshooting this mechanism permits a slightly alkaline intracellular tendency. The proton excess expelled from malignant cells accumulates in the ECM, where chronic hypoxia and relative lack of enough blood vessels impede adequate proton clearance, thus creating an acidic microenvironment. This microenvironment is quite heterogeneous due to the tumor’s metabolic heterogeneity and variable degrees of hypoxia inside the tumor mass. The acidic environment (plus other necessary cellular modifications) stimulates migration and invasion and finally intravasation of malignant cells which eventually may result in metastasis. Targeting tumor pH may go in two directions: 1) increasing extracellular pH which should result in less migration, invasion, and metastasis; and 2) decreasing intracellular pH which may result in acidic stress and apoptosis. Both objectives seem achievable at the present state of the art with repurposed drugs. This hypothesis analyzes the altered pH of tumors and its implications for progression and metastasis and also possible repurposed drug combinations targeting this vulnerable side of cancer development. It also analyzes the double-edged approach, which consists in pharmacologically increasing intracellular proton production and simultaneously decreasing proton extrusion creating intracellular acidity, acid stress, and eventual apoptosis. PMID:27799782

Nonmuscle myosin IIA and IIB differentially contribute to intrinsic and directed migration of human embryonic lung fibroblasts.

PubMed

Kuragano, Masahiro; Murakami, Yota; Takahashi, Masayuki

2018-03-25

Nonmuscle myosin II (NMII) plays an essential role in directional cell migration. In this study, we investigated the roles of NMII isoforms (NMIIA and NMIIB) in the migration of human embryonic lung fibroblasts, which exhibit directionally persistent migration in an intrinsic manner. NMIIA-knockdown (KD) cells migrated unsteadily, but their direction of migration was approximately maintained. By contrast, NMIIB-KD cells occasionally reversed their direction of migration. Lamellipodium-like protrusions formed in the posterior region of NMIIB-KD cells prior to reversal of the migration direction. Moreover, NMIIB KD led to elongation of the posterior region in migrating cells, probably due to the lack of load-bearing stress fibers in this area. These results suggest that NMIIA plays a role in steering migration by maintaining stable protrusions in the anterior region, whereas NMIIB plays a role in maintenance of front-rear polarity by preventing aberrant protrusion formation in the posterior region. These distinct functions of NMIIA and NMIIB might promote intrinsic and directed migration of normal human fibroblasts. Copyright © 2018 Elsevier Inc. All rights reserved.

Cell migration in microengineered tumor environments.

PubMed

Um, Eujin; Oh, Jung Min; Granick, Steve; Cho, Yoon-Kyoung

2017-12-05

Recent advances in microengineered cell migration platforms are discussed critically with a focus on how cell migration is influenced by engineered tumor microenvironments, the medical relevance being to understand how tumor microenvironments may promote or suppress the progression of cancer. We first introduce key findings in cancer cell migration under the influence of the physical environment, which is systematically controlled by microengineering technology, followed by multi-cues of physico-chemical factors, which represent the complexity of the tumor environment. Recognizing that cancer cells constantly communicate not only with each other but also with tumor-associated cells such as vascular, fibroblast, and immune cells, and also with non-cellular components, it follows that cell motility in tumor microenvironments, especially metastasis via the invasion of cancer cells into the extracellular matrix and other tissues, is closely related to the malignancy of cancer-related mortality. Medical relevance of forefront research realized in microfabricated devices, such as single cell sorting based on the analysis of cell migration behavior, may assist personalized theragnostics based on the cell migration phenotype. Furthermore, we urge development of theory and numerical understanding of single or collective cell migration in microengineered platforms to gain new insights in cancer metastasis and in therapeutic strategies.

Actin polymerization drives polar growth in Arabidopsis root hair cells.

PubMed

Vazquez, Luis Alfredo Bañuelos; Sanchez, Rosana; Hernandez-Barrera, Alejandra; Zepeda-Jazo, Isaac; Sánchez, Federico; Quinto, Carmen; Torres, Luis Cárdenas

2014-01-01

In plants, the actin cytoskeleton is a prime regulator of cell polarity, growth, and cytoplasmic streaming. Tip growth, as observed in root hairs, caulonema, and pollen tubes, is governed by many factors, including calcium gradients, exocytosis and endocytosis, reactive oxygen species, and the cytoskeleton. Several studies indicate that the polymerization of G-actin into F-actin also contributes to tip growth. The structure and function of F-actin within the apical dome is variable, ranging from a dense meshwork to sparse single filaments. The presence of multiple F-actin structures in the elongating apices of tip-growing cells suggests that this cytoskeletal array is tightly regulated. We recently reported that sublethal concentrations of fluorescently labeled cytochalasin could be used to visualize the distribution of microfilament plus ends using fluorescence microscopy, and found that the tip region of the growing root hair cells of a legume plant exhibits a clear response to the nodulation factors secreted by Rhizobium. (1) In this current work, we expanded our analysis using confocal microscopy and demonstrated the existence of highly dynamic fluorescent foci along Arabidopsis root hair cells. Furthermore, we show that the strongest fluorescence signal accumulates in the tip dome of the growing root hair and seems to be in close proximity to the apical plasma membrane. Based on these findings, we propose that actin polymerization within the dome of growing root hair cells regulates polar growth.

Directional Cell Migration in Response to Repeated Substratum Stretching

NASA Astrophysics Data System (ADS)

Okimura, Chika; Iwadate, Yoshiaki

2017-10-01

Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

Collective behavior of brain tumor cells: The role of hypoxia

NASA Astrophysics Data System (ADS)

Khain, Evgeniy; Katakowski, Mark; Hopkins, Scott; Szalad, Alexandra; Zheng, Xuguang; Jiang, Feng; Chopp, Michael

2011-03-01

We consider emergent collective behavior of a multicellular biological system. Specifically, we investigate the role of hypoxia (lack of oxygen) in migration of brain tumor cells. We performed two series of cell migration experiments. In the first set of experiments, cell migration away from a tumor spheroid was investigated. The second set of experiments was performed in a typical wound-healing geometry: Cells were placed on a substrate, a scratch was made, and cell migration into the gap was investigated. Experiments show a surprising result: Cells under normal and hypoxic conditions have migrated the same distance in the “spheroid” experiment, while in the “scratch” experiment cells under normal conditions migrated much faster than under hypoxic conditions. To explain this paradox, we formulate a discrete stochastic model for cell dynamics. The theoretical model explains our experimental observations and suggests that hypoxia decreases both the motility of cells and the strength of cell-cell adhesion. The theoretical predictions were further verified in independent experiments.

N-Cadherin and Fibroblast Growth Factor Receptors crosstalk in the control of developmental and cancer cell migrations.

PubMed

Nguyen, Thao; Mège, René Marc

2016-11-01

Cell migrations are diverse. They constitutemajor morphogenetic driving forces during embryogenesis, but they contribute also to the loss of tissue homeostasis and cancer growth. Capabilities of cells to migrate as single cells or as collectives are controlled by internal and external signalling, leading to the reorganisation of their cytoskeleton as well as by the rebalancing of cell-matrix and cell-cell adhesions. Among the genes altered in numerous cancers, cadherins and growth factor receptors are of particular interest for cell migration regulation. In particular, cadherins such as N-cadherin and a class of growth factor receptors, namely FGFRs cooperate to regulate embryonic and cancer cell behaviours. In this review, we discuss on reciprocal crosstalk between N-cadherin and FGFRs during cell migration. Finally, we aim at clarifying the synergy between N-cadherin and FGFR signalling that ensure cellular reorganization during cell movements, mainly during cancer cell migration and metastasis but also during developmental processes. Copyright © 2016 Elsevier GmbH. All rights reserved.

Slits Affect the Timely Migration of Neural Crest Cells via Robo Receptor

PubMed Central

Giovannone, Dion; Reyes, Michelle; Reyes, Rachel; Correa, Lisa; Martinez, Darwin; Ra, Hannah; Gomez, Gustavo; Kaiser, Josh; Ma, Le; Stein, Mary-Pat; de Bellard, Maria Elena

2013-01-01

SUMMARY Background Neural crest cells emerge by delamination from the dorsal neural tube and give rise to various components of the peripheral nervous system in vertebrate embryos. These cells change from non-motile into highly motile cells migrating to distant areas before further differentiation. Mechanisms controlling delamination and subsequent migration of neural crest cells are not fully understood. Slit2, a chemorepellant for axonal guidance that repels and stimulates motility of trunk neural crest cells away from the gut has recently been suggested to be a tumor suppressor molecule. The goal of this study was to further investigate the role of Slit2 in trunk neural crest cell migration by constitutive expression in neural crest cells. Results We found that Slit gain-of-function significantly impaired neural crest cell migration while Slit loss-of-function favored migration. In addition, we observed that the distribution of key cytoskeletal markers was disrupted in both gain and loss of function instances. Conclusions These findings suggest that Slit molecules might be involved in the processes that allow neural crest cells to begin migration and transitioning to a mesenchymal type. PMID:22689303

Optimization of interneuron function by direct coupling of cell migration and axonal targeting.

PubMed

Lim, Lynette; Pakan, Janelle M P; Selten, Martijn M; Marques-Smith, André; Llorca, Alfredo; Bae, Sung Eun; Rochefort, Nathalie L; Marín, Oscar

2018-06-18

Neural circuit assembly relies on the precise synchronization of developmental processes, such as cell migration and axon targeting, but the cell-autonomous mechanisms coordinating these events remain largely unknown. Here we found that different classes of interneurons use distinct routes of migration to reach the embryonic cerebral cortex. Somatostatin-expressing interneurons that migrate through the marginal zone develop into Martinotti cells, one of the most distinctive classes of cortical interneurons. For these cells, migration through the marginal zone is linked to the development of their characteristic layer 1 axonal arborization. Altering the normal migratory route of Martinotti cells by conditional deletion of Mafb-a gene that is preferentially expressed by these cells-cell-autonomously disrupts axonal development and impairs the function of these cells in vivo. Our results suggest that migration and axon targeting programs are coupled to optimize the assembly of inhibitory circuits in the cerebral cortex.

Collective cell migration during inflammatory response

NASA Astrophysics Data System (ADS)

Wu, Di; Stroka, Kimberly; Aranda-Espinoza, Helim

2012-02-01

Wound scratch healing assays of endothelial cell monolayers is a simple model to study collective cell migration as a function of biological signals. A signal of particular interest is the immune response, which after initial wounding in vivo causes the release of various inflammatory factors such as tumor necrosis alpha (TNF-α). TNF-α is an innate inflammatory cytokine that can induce cell growth, cell necrosis, and change cell morphology. We studied the effects of TNF-α on collective cell migration using the wound healing assays and measured several migration metrics, such as rate of scratch closure, velocities of leading edge and bulk cells, closure index, and velocity correlation functions between migrating cells. We observed that TNF-α alters all migratory metrics as a function of the size of the scratch and TNF-α content. The changes observed in migration correlate with actin reorganization upon TNF-α exposure.

Untangling cell tracks: Quantifying cell migration by time lapse image data analysis.

PubMed

Svensson, Carl-Magnus; Medyukhina, Anna; Belyaev, Ivan; Al-Zaben, Naim; Figge, Marc Thilo

2018-03-01

Automated microscopy has given researchers access to great amounts of live cell imaging data from in vitro and in vivo experiments. Much focus has been put on extracting cell tracks from such data using a plethora of segmentation and tracking algorithms, but further analysis is normally required to draw biologically relevant conclusions. Such relevant conclusions may be whether the migration is directed or not, whether the population has homogeneous or heterogeneous migration patterns. This review focuses on the analysis of cell migration data that are extracted from time lapse images. We discuss a range of measures and models used to analyze cell tracks independent of the biological system or the way the tracks were obtained. For single-cell migration, we focus on measures and models giving examples of biological systems where they have been applied, for example, migration of bacteria, fibroblasts, and immune cells. For collective migration, we describe the model systems wound healing, neural crest migration, and Drosophila gastrulation and discuss methods for cell migration within these systems. We also discuss the role of the extracellular matrix and subsequent differences between track analysis in vitro and in vivo. Besides methods and measures, we are putting special focus on the need for openly available data and code, as well as a lack of common vocabulary in cell track analysis. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

The Sal-like 4 - integrin α6β1 network promotes cell migration for metastasis via activation of focal adhesion dynamics in basal-like breast cancer cells.

PubMed

Itou, Junji; Tanaka, Sunao; Li, Wenzhao; Iida, Atsuo; Sehara-Fujisawa, Atsuko; Sato, Fumiaki; Toi, Masakazu

2017-01-01

During metastasis, cancer cell migration is enhanced. However, the mechanisms underlying this process remain elusive. Here, we addressed this issue by functionally analyzing the transcription factor Sal-like 4 (SALL4) in basal-like breast cancer cells. Loss-of-function studies of SALL4 showed that this transcription factor is required for the spindle-shaped morphology and the enhanced migration of cancer cells. SALL4 also up-regulated integrin gene expression. The impaired cell migration observed in SALL4 knockdown cells was restored by overexpression of integrin α6 and β1. In addition, we clarified that integrin α6 and β1 formed a heterodimer. At the molecular level, loss of the SALL4 - integrin α6β1 network lost focal adhesion dynamics, which impairs cell migration. Over-activation of Rho is known to inhibit focal adhesion dynamics. We observed that SALL4 knockdown cells exhibited over-activation of Rho. Aberrant Rho activation was suppressed by integrin α6β1 expression, and pharmacological inhibition of Rho activity restored cell migration in SALL4 knockdown cells. These results indicated that the SALL4 - integrin α6β1 network promotes cell migration via modulation of Rho activity. Moreover, our zebrafish metastasis assays demonstrated that this gene network enhances cell migration in vivo. Our findings identify a potential new therapeutic target for the prevention of metastasis, and provide an improved understanding of cancer cell migration. Copyright © 2016 Elsevier B.V. All rights reserved.

Vinculin is required for cell polarization, migration, and extracellular matrix remodeling in 3D collagen.

PubMed

Thievessen, Ingo; Fakhri, Nikta; Steinwachs, Julian; Kraus, Viola; McIsaac, R Scott; Gao, Liang; Chen, Bi-Chang; Baird, Michelle A; Davidson, Michael W; Betzig, Eric; Oldenbourg, Rudolf; Waterman, Clare M; Fabry, Ben

2015-11-01

Vinculin is filamentous (F)-actin-binding protein enriched in integrin-based adhesions to the extracellular matrix (ECM). Whereas studies in 2-dimensional (2D) tissue culture models have suggested that vinculin negatively regulates cell migration by promoting cytoskeleton-ECM coupling to strengthen and stabilize adhesions, its role in regulating cell migration in more physiologic, 3-dimensional (3D) environments is unclear. To address the role of vinculin in 3D cell migration, we analyzed the morphodynamics, migration, and ECM remodeling of primary murine embryonic fibroblasts (MEFs) with cre/loxP-mediated vinculin gene disruption in 3D collagen I cultures. We found that vinculin promoted 3D cell migration by increasing directional persistence. Vinculin was necessary for persistent cell protrusion, cell elongation, and stable cell orientation in 3D collagen, but was dispensable for lamellipodia formation, suggesting that vinculin-mediated cell adhesion to the ECM is needed to convert actin-based cell protrusion into persistent cell shape change and migration. Consistent with this finding, vinculin was necessary for efficient traction force generation in 3D collagen without affecting myosin II activity and promoted 3D collagen fiber alignment and macroscopical gel contraction. Our results suggest that vinculin promotes directionally persistent cell migration and tension-dependent ECM remodeling in complex 3D environments by increasing cell-ECM adhesion and traction force generation. © FASEB.

ProBDNF inhibits collective migration and chemotaxis of rat Schwann cells.

PubMed

Ding, You-Quan; Li, Xuan-Yang; Xia, Guan-Nan; Ren, Hong-Yi; Zhou, Xin-Fu; Su, Bing-Yin; Qi, Jian-Guo

2016-10-01

Schwann cell migration, including collective migration and chemotaxis, is essential for the formation of coordinate interactions between Schwann cells and axons during peripheral nerve development and regeneration. Moreover, limited migration of Schwann cells imposed a serious obstacle on Schwann cell-astrocytes intermingling and spinal cord repair after Schwann cell transplantation into injured spinal cords. Recent studies have shown that mature brain-derived neurotrophic factor, a member of the neurotrophin family, inhibits Schwann cell migration. The precursor form of brain-derived neurotrophic factor, proBDNF, was expressed in the developing or degenerating peripheral nerves and the injured spinal cords. Since "the yin and yang of neurotrophin action" has been established as a common sense, proBDNF would be expected to promote Schwann cell migration. However, we found, in the present study, that exogenous proBDNF also inhibited in vitro collective migration and chemotaxis of RSC 96 cells, a spontaneously immortalized rat Schwann cell line. Moreover, proBDNF suppressed adhesion and spreading of those cells. At molecular level, proBDNF inhibits F-actin polymerization and focal adhesion dynamics in cultured RSC 96 cells. Therefore, our results suggested a special case against the classical opinion of "the yin and yang of neurotrophin action" and implied that proBDNF might modulate peripheral nerve development or regeneration and spinal cord repair through perturbing native or transplanted Schwann cell migration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cellular Migration and Invasion Uncoupled: Increased Migration Is Not an Inexorable Consequence of Epithelial-to-Mesenchymal Transition

PubMed Central

Schaeffer, Daneen; Somarelli, Jason A.; Hanna, Gabi; Palmer, Gregory M.

2014-01-01

Metastatic dissemination requires carcinoma cells to detach from the primary tumor and invade through the basement membrane. To acquire these characteristics, epithelial tumor cells undergo epithelial-to-mesenchymal transitions (EMT), whereby cells lose polarity and E-cadherin-mediated cell-cell adhesion. Post-EMT cells have also been shown, or assumed, to be more migratory; however, there have been contradictory reports on an immortalized human mammary epithelial cell line (HMLE) that underwent EMT. In the context of carcinoma-associated EMT, it is not yet clear whether the change in migration and invasion must be positively correlated during EMT or whether enhanced migration is a necessary consequence of having undergone EMT. Here, we report that pre-EMT rat prostate cancer (PC) and HMLE cells are more migratory than their post-EMT counterparts. To determine a mechanism for increased epithelial cell migration, gene expression analysis was performed and revealed an increase in epidermal growth factor receptor (EGFR) expression in pre-EMT cells. Indeed, inhibition of EGFR in PC epithelial cells slowed migration. Importantly, while post-EMT PC and HMLE cell lines are less migratory, both remain invasive in vitro and, for PC cells, in vivo. Our study demonstrates that enhanced migration is not a phenotypic requirement of EMT, and migration and invasion can be uncoupled during carcinoma-associated EMT. PMID:25002532

A photon-driven micromotor can direct nerve fibre growth

NASA Astrophysics Data System (ADS)

Wu, Tao; Nieminen, Timo A.; Mohanty, Samarendra; Miotke, Jill; Meyer, Ronald L.; Rubinsztein-Dunlop, Halina; Berns, Michael W.

2012-01-01

Axonal path-finding is important in the development of the nervous system, nerve repair and nerve regeneration. The behaviour of the growth cone at the tip of the growing axon determines the direction of axonal growth and migration. We have developed an optical-based system to control the direction of growth of individual axons (nerve fibres) using laser-driven spinning birefringent spheres. One or two optical traps position birefringent beads adjacent to growth cones of cultured goldfish retinal ganglion cell axons. Circularly polarized light with angular momentum causes the trapped bead to spin. This creates a localized microfluidic flow generating an estimated 0.17 pN shear force against the growth cone that turns in response to the shear. The direction of axonal growth can be precisely manipulated by changing the rotation direction and position of this optically driven micromotor. A physical model estimating the shear force density on the axon is described.

Cell-Biological Studies of Osmotic Shock Response in Streptomyces spp.

PubMed

Fuchino, Katsuya; Flärdh, Klas; Dyson, Paul; Ausmees, Nora

2017-01-01

Most bacteria are likely to face osmotic challenges, but there is yet much to learn about how such environmental changes affect the architecture of bacterial cells. Here, we report a cell-biological study in model organisms of the genus Streptomyces, which are actinobacteria that grow in a highly polarized fashion to form branching hyphae. The characteristic apical growth of Streptomyces hyphae is orchestrated by protein assemblies, called polarisomes, which contain coiled-coil proteins DivIVA and Scy, and recruit cell wall synthesis complexes and the stress-bearing cytoskeleton of FilP to the tip regions of the hyphae. We monitored cell growth and cell-architectural changes by time-lapse microscopy in osmotic upshift experiments. Hyperosmotic shock caused arrest of growth, loss of turgor, and hypercondensation of chromosomes. The recovery period was protracted, presumably due to the dehydrated state of the cytoplasm, before hyphae could restore their turgor and start to grow again. In most hyphae, this regrowth did not take place at the original hyphal tips. Instead, cell polarity was reprogrammed, and polarisomes were redistributed to new sites, leading to the emergence of multiple lateral branches from which growth occurred. Factors known to regulate the branching pattern of Streptomyces hyphae, such as the serine/threonine kinase AfsK and Scy, were not involved in reprogramming of cell polarity, indicating that different mechanisms may act under different environmental conditions to control hyphal branching. Our observations of hyphal morphology during the stress response indicate that turgor and sufficient hydration of cytoplasm are required for Streptomyces tip growth. Polar growth is an intricate manner of growth for accomplishing a complicated morphology, employed by a wide range of organisms across the kingdoms of life. The tip extension of Streptomyces hyphae is one of the most pronounced examples of polar growth among bacteria. The expansion of the cell wall by tip extension is thought to be facilitated by the turgor pressure, but it was unknown how external osmotic change influences Streptomyces tip growth. We report here that severe hyperosmotic stress causes cessation of growth, followed by reprogramming of cell polarity and rearrangement of growth zones to promote lateral hyphal branching. This phenomenon may represent a strategy of hyphal organisms to avoid osmotic stress encountered by the growing hyphal tip. Copyright © 2016 American Society for Microbiology.

CoCl2 , a mimic of hypoxia, enhances bone marrow mesenchymal stem cells migration and osteogenic differentiation via STAT3 signaling pathway.

PubMed

Yu, Xin; Wan, Qilong; Cheng, Gu; Cheng, Xin; Zhang, Jing; Pathak, Janak L; Li, Zubing

2018-06-16

Mesenchymal stem cells homing and migration is a crucial step during bone fracture healing. Hypoxic environment in fracture site induces bone marrow mesenchymal stem cells (BMSCs) migration, but its mechanism remains unclear. Our previous study and studies by other groups have reported the involvement of signal transducer and activator of transcription 3 (STAT3) pathway in cell migration. However, the role of STAT3 pathway in hypoxia-induced cell migration is still unknown. In this study, we investigated the role of STAT3 signaling in hypoxia-induced BMSCs migration and osteogenic differentiation. BMSCs isolated from C57BL/6 male mice were cultured in the presence of cobalt chloride (CoCl 2 ) to simulate intracellular hypoxia. Hypoxia enhanced BMSCs migration, and upregulated cell migration related gene expression i.e., metal-loproteinase (MMP) 7, MMP9 and C-X-C motif chemokine receptor 4. Hypoxia enhanced the phosphorylation of STAT3, and cell migration related proteins: c-jun n-terminal kinase (JNK), focal of adhesion kinase (FAK), extracellular regulated protein kinases and protein kinase B 1/2 (ERK1/2). Moreover, hypoxia enhanced expression of osteogenic differentiation marker. Inhibition of STAT3 suppressed the hy-poxia-induced BMSCs migration, cell migration related signaling molecules phos-phorylation, and osteogenic differentiation related gene expression. In conclusion, our result indicates that hypoxia-induced BMSCs migration and osteogenic differentiation is via STAT3 phosphorylation and involves the cooperative activity of the JNK, FAK and MMP9 signaling pathways. This article is protected by copyright. All rights reserved.

Identification of tissues and patterning events required for distinct steps in early migration of zebrafish primordial germ cells.

PubMed

Weidinger, G; Wolke, U; Köprunner, M; Klinger, M; Raz, E

1999-12-01

In many organisms, the primordial germ cells have to migrate from the position where they are specified towards the developing gonad where they generate gametes. Extensive studies of the migration of primordial germ cells in Drosophila, mouse, chick and Xenopus have identified somatic tissues important for this process and demonstrated a role for specific molecules in directing the cells towards their target. In zebrafish, a unique situation is found in that the primordial germ cells, as marked by expression of vasa mRNA, are specified in random positions relative to the future embryonic axis. Hence, the migrating cells have to navigate towards their destination from various starting positions that differ among individual embryos. Here, we present a detailed description of the migration of the primordial germ cells during the first 24 hours of wild-type zebrafish embryonic development. We define six distinct steps of migration bringing the primordial germ cells from their random positions before gastrulation to form two cell clusters on either side of the midline by the end of the first day of development. To obtain information on the origin of the positional cues provided to the germ cells by somatic tissues during their migration, we analyzed the migration pattern in mutants, including spadetail, swirl, chordino, floating head, cloche, knypek and no isthmus. In mutants with defects in axial structures, paraxial mesoderm or dorsoventral patterning, we find that certain steps of the migration process are specifically affected. We show that the paraxial mesoderm is important for providing proper anteroposterior information to the migrating primordial germ cells and that these cells can respond to changes in the global dorsoventral coordinates. In certain mutants, we observe accumulation of ectopic cells in different regions of the embryo. These ectopic cells can retain both morphological and molecular characteristics of primordial germ cells, suggesting that, in zebrafish at the early stages tested, the vasa-expressing cells are committed to the germ cell lineage.

Robotic Patterning a Superhydrophobic Surface for Collective Cell Migration Screening.

PubMed

Pang, Yonggang; Yang, Jing; Hui, Zhixin; Grottkau, Brian E

2018-04-01

Collective cell migration, in which cells migrate as a group, is fundamental in many biological and pathological processes. There is increasing interest in studying the collective cell migration in high throughput. Cell scratching, insertion blocker, and gel-dissolving techniques are some methodologies used previously. However, these methods have the drawbacks of cell damage, substrate surface alteration, limitation in medium exchange, and solvent interference. The superhydrophobic surface, on which the water contact angle is greater than 150 degrees, has been recently utilized to generate patterned arrays. Independent cell culture areas can be generated on a substrate that functions the same as a conventional multiple well plate. However, so far there has been no report on superhydrophobic patterning for the study of cell migration. In this study, we report on the successful development of a robotically patterned superhydrophobic array for studying collective cell migration in high throughput. The array was developed on a rectangular single-well cell culture plate consisting of hydrophilic flat microwells separated by the superhydrophobic surface. The manufacturing process is robotic and includes patterning discrete protective masks to the substrate using 3D printing, robotic spray coating of silica nanoparticles, robotic mask removal, robotic mini silicone blocker patterning, automatic cell seeding, and liquid handling. Compared with a standard 96-well plate, our system increases the throughput by 2.25-fold and generates a cell-free area in each well non-destructively. Our system also demonstrates higher efficiency than conventional way of liquid handling using microwell plates, and shorter processing time than manual operating in migration assays. The superhydrophobic surface had no negative impact on cell viability. Using our system, we studied the collective migration of human umbilical vein endothelial cells and cancer cells using assays of endpoint quantification, dynamic cell tracking, and migration quantification following varied drug treatments. This system provides a versatile platform to study collective cell migration in high throughput for a broad range of applications.

The Stress-responsive Gene ATF3 Mediates Dichotomous UV Responses by Regulating the Tip60 and p53 Proteins*

PubMed Central

Cui, Hongmei; Li, Xingyao; Han, Chunhua; Wang, Qi-En; Wang, Hongbo; Ding, Han-Fei; Zhang, Junran; Yan, Chunhong

2016-01-01

The response to UV irradiation is important for a cell to maintain its genetic integrity when challenged by environmental genotoxins. An immediate early response to UV irradiation is the rapid induction of activating transcription factor 3 (ATF3) expression. Although emerging evidence has linked ATF3 to stress pathways regulated by the tumor suppressor p53 and the histone acetyltransferase Tip60, the role of ATF3 in the UV response remains largely unclear. Here, we report that ATF3 mediated dichotomous UV responses. Although UV irradiation enhanced the binding of ATF3 to Tip60, knockdown of ATF3 expression decreased Tip60 stability, thereby impairing Tip60 induction by UV irradiation. In line with the role of Tip60 in mediating UV-induced apoptosis, ATF3 promoted the death of p53-defective cells in response to UV irradiation. However, ATF3 could also activate p53 and promote p53-mediated DNA repair, mainly through altering histone modifications that could facilitate recruitment of DNA repair proteins (such as DDB2) to damaged DNA sites. As a result, ATF3 rather protected the p53 wild-type cells from UV-induced apoptosis. Our results thus indicate that ATF3 regulates cell fates upon UV irradiation in a p53-dependent manner. PMID:26994140

A transport and retention mechanism for the sustained distal localization of Spn-F-IKKε during Drosophila bristle elongation.

PubMed

Otani, Tetsuhisa; Oshima, Kenzi; Kimpara, Akiyo; Takeda, Michiko; Abdu, Uri; Hayashi, Shigeo

2015-07-01

Stable localization of the signaling complex is essential for the robust morphogenesis of polarized cells. Cell elongation involves molecular signaling centers that coordinately regulate intracellular transport and cytoskeletal structures. In Drosophila bristle elongation, the protein kinase IKKε is activated at the distal tip of the growing bristle and regulates the shuttling movement of recycling endosomes and cytoskeletal organization. However, how the distal tip localization of IKKε is established and maintained during bristle elongation is unknown. Here, we demonstrate that IKKε distal tip localization is regulated by Spindle-F (Spn-F), which is stably retained at the distal tip and functions as an adaptor linking IKKε to cytoplasmic dynein. We found that Javelin-like (Jvl) is a key regulator of Spn-F retention. In jvl mutant bristles, IKKε and Spn-F initially localize to the distal tip but fail to be retained there. In S2 cells, particles that stain positively for Jvl or Spn-F move in a microtubule-dependent manner, whereas Jvl and Spn-F double-positive particles are immobile, indicating that Jvl and Spn-F are transported separately and, upon forming a complex, immobilize each other. These results suggest that polarized transport and selective retention regulate the distal tip localization of the Spn-F-IKKε complex during bristle cell elongation. © 2015. Published by The Company of Biologists Ltd.

Aluminium-induced reduction of plant growth in alfalfa (Medicago sativa) is mediated by interrupting auxin transport and accumulation in roots.

PubMed

Wang, Shengyin; Ren, Xiaoyan; Huang, Bingru; Wang, Ge; Zhou, Peng; An, Yuan

2016-07-20

The objective of this study was to investigate Al(3+)-induced IAA transport, distribution, and the relation of these two processes to Al(3+)-inhibition of root growth in alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or 100 μM AlCl3 and were foliar sprayed with water or 6 mg L(-1) IAA. Aluminium stress resulted in disordered arrangement of cells, deformed cell shapes, altered cell structure, and a shorter length of the meristematic zone in root tips. Aluminium stress significantly decreased the IAA concentration in apical buds and root tips. The distribution of IAA fluorescence signals in root tips was disturbed, and the IAA transportation from shoot base to root tip was inhibited. The highest intensity of fluorescence signals was detected in the apical meristematic zone. Exogenous application of IAA markedly alleviated the Al(3+)-induced inhibition of root growth by increasing IAA accumulation and recovering the damaged cell structure in root tips. In addition, Al(3+) stress up-regulated expression of AUX1 and PIN2 genes. These results indicate that Al(3+)-induced reduction of root growth could be associated with the inhibitions of IAA synthesis in apical buds and IAA transportation in roots, as well as the imbalance of IAA distribution in root tips.

Aluminium-induced reduction of plant growth in alfalfa (Medicago sativa) is mediated by interrupting auxin transport and accumulation in roots

PubMed Central

Wang, Shengyin; Ren, Xiaoyan; Huang, Bingru; Wang, Ge; Zhou, Peng; An, Yuan

2016-01-01

The objective of this study was to investigate Al3+-induced IAA transport, distribution, and the relation of these two processes to Al3+-inhibition of root growth in alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or 100 μM AlCl3 and were foliar sprayed with water or 6 mg L−1 IAA. Aluminium stress resulted in disordered arrangement of cells, deformed cell shapes, altered cell structure, and a shorter length of the meristematic zone in root tips. Aluminium stress significantly decreased the IAA concentration in apical buds and root tips. The distribution of IAA fluorescence signals in root tips was disturbed, and the IAA transportation from shoot base to root tip was inhibited. The highest intensity of fluorescence signals was detected in the apical meristematic zone. Exogenous application of IAA markedly alleviated the Al3+-induced inhibition of root growth by increasing IAA accumulation and recovering the damaged cell structure in root tips. In addition, Al3+ stress up-regulated expression of AUX1 and PIN2 genes. These results indicate that Al3+-induced reduction of root growth could be associated with the inhibitions of IAA synthesis in apical buds and IAA transportation in roots, as well as the imbalance of IAA distribution in root tips. PMID:27435109

Measurement of Tip Apex Distance and Migration of Lag Screws and Novel Blade Screw Used for the Fixation of Intertrochanteric Fractures.

PubMed

Yang, Jesse Chieh-Szu; Chen, Hsin-Chang; Lai, Yu-Shu; Cheng, Cheng-Kung

2017-01-01

Fixation with a dynamic hip screw (DHS) is one of the most common methods for stabilizing intertrochanteric fractures, except for unstable and reverse oblique fracture types. However, failure is often observed in osteoporotic patients whereby the lag screw effectively 'cuts out' through the weak bone. Novel anti-migration blades have been developed to be used in combination with a lag screw ('Blade Screw') to improve the fixation strength in osteoporotic intertrochanteric fractures. An in-vitro biomechanical study and a retrospective clinical study were performed to evaluate lag screw migration when using the novel Blade Screw and a traditional threaded DHS. The biomechanical study showed both the Blade Screw and DHS displayed excessive migration (≥10 mm) before reaching 20,000 loading cycles in mild osteoporotic bone, but overall migration of the Blade Screw was significantly less (p ≤ 0.03). Among the patients implanted with a Blade Screw in the clinical study, there was no significant variation in screw migration at 3-months follow-up (P = 0.12). However, the patient's implanted with a DHS did display significantly greater migration (P<0.001) than those implanted with the Blade Screw. In conclusion, the Blade Screw stabilizes the bone fragments during dynamic loading so as to provide significantly greater resistance to screw migration in patients with mild osteoporosis.

Ordered progression of nematogenesis from stem cells through differentiation stages in the tentacle bulb of Clytia hemisphaerica (Hydrozoa, Cnidaria).

PubMed

Denker, Elsa; Manuel, Michaël; Leclère, Lucas; Le Guyader, Hervé; Rabet, Nicolas

2008-03-01

Nematogenesis, the production of stinging cells (nematocytes) in Cnidaria, can be considered as a model neurogenic process. Most molecular data concern the freshwater polyp Hydra, in which nematocyte production is scattered throughout the body column ectoderm, the mature cells then migrating to the tentacles. We have characterized tentacular nematogenesis in the Clytia hemisphaerica hydromedusa and found it to be confined to the ectoderm of the tentacle bulb, a specialized swelling at the tentacle base. Analysis by a variety of light and electron microscope techniques revealed that while cellular aspects of nematogenesis are similar to Hydra, the spatio-temporal characteristics are markedly more ordered. The tentacle bulb nematogenic ectoderm (TBE) was found to be polarized, with a clear progression of successive nematoblast stages from a proximal zone (comprising a majority of undifferentiated cells) to the distal end where the tentacle starts. Pulse-chase labelling experiments demonstrated a continuous displacement of differentiating nematoblasts towards the tentacle tip, and that nematogenesis proceeds more rapidly in Clytia than in Hydra. Compact expression domains of orthologues of known nematogenesis-associated genes (Piwi, dickkopf-3, minicollagens and NOWA) were correspondingly staggered along the TBE. These distinct characteristics make the Clytia TBE a promising experimental system for understanding the mechanisms regulating nematogenesis.

Motile membrane protrusions regulate cell-cell adhesion and migration of olfactory ensheathing glia.

PubMed

Windus, Louisa C E; Claxton, Christina; Allen, Chelsea L; Key, Brian; St John, James A

2007-12-01

Olfactory ensheathing cells (OECs) are candidates for therapeutic approaches for neural regeneration due to their ability to assist axon regrowth in central nervous system lesion models. However, little is understood about the processes and mechanisms underlying migration of these cells. We report here that novel lamellipodial protrusions, termed lamellipodial waves, are integral to OEC migration. Time-lapse imaging of migrating OECs revealed that these highly dynamic waves progress along the shaft of the cells and are crucial for mediating cell-cell adhesion. Without these waves, cell-cell adhesion does not occur and migrational rates decline. The activity of waves is modulated by both glial cell line-derived neurotrophic factor and inhibitors of the JNK and SRC kinases. Furthermore, the activity of lamellipodial waves can be modulated by Mek1, independently of leading edge activity. The ability to selectively regulate cell migration via lamellipodial waves has implications for manipulating the migratory behavior of OECs during neural repair. (c) 2007 Wiley-Liss, Inc.

Long-term effects of short-term retinal bleb detachments in rabbits.

PubMed

Ivert, Lena; Kjeldbye, Hild; Gouras, Peter

2002-03-01

To examine the effects of saline-induced bleb detachments in rabbit retina. Retinal bleb detachments were produced by the injection of 50 microl of balanced salt solution (BSS) into the subretinal space of one eye of each of six rabbits using a glass pipette with a flat tip, 50 microm in diameter. The retina was examined by biomicroscopy, scanning laser ophthalmoscopy (SLO), auto-fluorescence and simultaneous fluorescein and indocyanine green (ICG) angiography. Histological examination was carried out at 1, 2, 3 and 4 months after surgery. All rabbits showed leakage of fluorescein for at least a day after detachment, but within 1 month the leakage ceased. ICG staining developed gradually at the level of the RPE or Bruch's membrane near sites of previous staining. Lipofuscin fluorescence also developed gradually around areas of staining. Histology revealed the source of the excessive lipofuscin to be in the RPE layer, especially in cells migrating away from Bruch's membrane. Short-term bleb detachments cause a transient breakdown in the blood-retinal barrier, long-term ICG staining at or deep to the RPE layer, hyperlipofuscinosis and migration of the RPE. The abnormal lipofuscin accumulation is apparent on fluorescence ophthalmoscopy and can be confused with markers such as green fluorescent protein.

RhoA regulates Activin B-induced stress fiber formation and migration of bone marrow-derived mesenchymal stromal cell through distinct signaling.

PubMed

Wang, Xueer; Tang, Pei; Guo, Fukun; Zhang, Min; Chen, Yinghua; Yan, Yuan; Tian, Zhihui; Xu, Pengcheng; Zhang, Lei; Zhang, Lu; Zhang, Lin

2017-01-01

In our previous study, Activin B induced actin stress fiber formation and cell migration in Bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. However, the underlying molecular mechanisms are not well studied. RhoA is recognized to play a critical role in the regulation of actomyosin cytoskeletal organization and cell migration. Pull-down assay was performed to investigate the activity of RhoA. The dominant-negative mutants of RhoA (RhoA(N19)) was used to determine whether RhoA has a role in Activin B-induced cytoskeleton organization and cell migration in BMSCs. Cytoskeleton organization was examined by fluorescence Rhodamine-phalloidin staining, and cell migration by transwell and cell scratching assay. Western blot was carried out to investigate downstream signaling cascade of RhoA. Inhibitor and siRNAs were used to detect the role of downstream signaling in stress fiber formation and/or cell migration. RhoA was activated by Activin B in BMSCs. RhoA(N19) blocked Activin B-induced stress fiber formation and cell migration. ROCK inhibitor blocked Activin B-induced stress fiber formation but enhanced BMSCs migration. Activin B induced phosphorylation of LIMK2 and Cofilin, which was abolished by ROCK inhibition. Both of siRNA LIMK2 and siRNA Cofilin inhibited Activin B-induced stress fiber formation. RhoA regulates Activin B-induced stress fiber formation and migration of BMSCs. A RhoA-ROCK-LIMK2-Cofilin signaling node exists and regulates actin stress fiber formation. RhoA regulates Activin B-induced cell migration independent of ROCK. Better understanding of the molecular mechanisms of BMSCs migration will help optimize therapeutic strategy to target BMSCs at injured tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Brain-derived Neurotrophic Factor Promotes the Migration of Olfactory Ensheathing Cells Through TRPC Channels.

PubMed

Wang, Ying; Teng, Hong-Lin; Gao, Yuan; Zhang, Fan; Ding, Yu-Qiang; Huang, Zhi-Hui

2016-12-01

Olfactory ensheathing cells (OECs) are a unique type of glial cells with axonal growth-promoting properties in the olfactory system. Organized migration of OECs is essential for neural regeneration and olfactory development. However, the molecular mechanism of OEC migration remains unclear. In the present study, we examined the effects of brain-derived neurotrophic factor (BDNF) on OEC migration. Initially, the "scratch" migration assay, the inverted coverslip and Boyden chamber migration assays showed that BDNF could promote the migration of primary cultured OECs. Furthermore, BDNF gradient attracted the migration of OECs in single-cell migration assays. Mechanistically, TrkB receptor expressed in OECs mediated BDNF-induced OEC migration, and BDNF triggered calcium signals in OECs. Finally, transient receptor potential cation channels (TRPCs) highly expressed in OECs were responsible for BDNF-induced calcium signals, and required for BDNF-induced OEC migration. Taken together, these results demonstrate that BDNF promotes the migration of cultured OECs and an unexpected finding is that TRPCs are required for BDNF-induced OEC migration. GLIA 2016;64:2154-2165. © 2016 Wiley Periodicals, Inc.

Crucial role of vinexin for keratinocyte migration in vitro and epidermal wound healing in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kioka, Noriyuki, E-mail: nkioka@kais.kyoto-u.ac.jp; Ito, Takuya; Yamashita, Hiroshi

2010-06-10

In the process of tissue injury and repair, epithelial cells rapidly migrate and form epithelial sheets. Vinexin is a cytoplasmic molecule of the integrin-containing cell adhesion complex localized at focal contacts in vitro. Here, we investigated the roles of vinexin in keratinocyte migration in vitro and wound healing in vivo. Vinexin knockdown using siRNA delayed migration of both HaCaT human keratinocytes and A431 epidermoid carcinoma cells in scratch assay but did not affect cell proliferation. Induction of cell migration by scratching the confluent monolayer culture of these cells activated both EGFR and ERK, and their inhibitors AG1478 and U0126 substantiallymore » suppressed scratch-induced keratinocyte migration. Vinexin knockdown in these cells inhibited the scratch-induced activation of EGFR, but not that of ERK, suggesting that vinexin promotes cell migration via activation of EGFR. We further generated vinexin (-/-) mice and isolated their keratinocytes. They similarly showed slow migration in scratch assay. Furthermore, vinexin (-/-) mice exhibited a delay in cutaneous wound healing in both the back skin and tail without affecting the proliferation of keratinocytes. Together, these results strongly suggest a crucial role of vinexin in keratinocyte migration in vitro and cutaneous wound healing in vivo.« less

Lamellipodia-based migrations of larval epithelial cells are required for normal closure of the adult epidermis of Drosophila

PubMed Central

Bischoff, Marcus

2012-01-01

Cell migrations are an important feature of animal development. They are, furthermore, essential to wound healing and tumour progression. Despite recent progress, it is still mysterious how cell migration is spatially and temporally regulated during morphogenesis and how cell migration is coordinated with other cellular behaviours to shape tissues and organs. The formation of the abdominal epithelium of Drosophila during metamorphosis provides an attractive system to study morphogenesis. Here, the diploid adult histoblasts replace the polyploid larval epithelial cells (LECs). Using in vivo 4D microscopy, I show that, besides apical constriction and apoptosis, the LECs undergo extensive coordinated migrations. The migrations follow a transition from a stationary (epithelial) to a migratory mode. The migratory behaviour is stimulated by autocrine Dpp signalling. Directed apical lamellipodia-like protrusions propel the cells. Initially, planar cell polarity determines the orientation of LEC migration. While LECs are migrating they also constrict apically, and changes in activity of the small GTPase Rho1 can favour one behaviour over the other. This study shows that the LECs play a more active role in morphogenesis than previously thought, with their migrations contributing to abdominal closure. It furthermore provides insights into how the migratory behaviour of cells is regulated during morphogenesis. PMID:22230614

Gaussian Curvature Directs Stress Fiber Orientation and Cell Migration.

PubMed

Bade, Nathan D; Xu, Tina; Kamien, Randall D; Assoian, Richard K; Stebe, Kathleen J

2018-03-27

We show that substrates with nonzero Gaussian curvature influence the organization of stress fibers and direct the migration of cells. To study the role of Gaussian curvature, we developed a sphere-with-skirt surface in which a positive Gaussian curvature spherical cap is seamlessly surrounded by a negative Gaussian curvature draping skirt, both with principal radii similar to cell-length scales. We find significant reconfiguration of two subpopulations of stress fibers when fibroblasts are exposed to these curvatures. Apical stress fibers in cells on skirts align in the radial direction and avoid bending by forming chords across the concave gap, whereas basal stress fibers bend along the convex direction. Cell migration is also strongly influenced by the Gaussian curvature. Real-time imaging shows that cells migrating on skirts repolarize to establish a leading edge in the azimuthal direction. Thereafter, they migrate in that direction. This behavior is notably different from migration on planar surfaces, in which cells typically migrate in the same direction as the apical stress fiber orientation. Thus, this platform reveals that nonzero Gaussian curvature not only affects the positioning of cells and alignment of stress fiber subpopulations but also directs migration in a manner fundamentally distinct from that of migration on planar surfaces. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Root tips moving through soil

PubMed Central

Curlango-Rivera, Gilberto

2011-01-01

Root elongation occurs by the generation of new cells from meristematic tissue within the apical 1–2 mm region of root tips. Therefore penetration of the soil environment is carried out by newly synthesized plant tissue, whose cells are inherently vulnerable to invasion by pathogens. This conundrum, on its face, would seem to reflect an intolerable risk to the successful establishment of root systems needed for plant life. Yet root tip regions housing the meristematic tissues repeatedly have been found to be free of microbial infection and colonization. Even when spore germination, chemotaxis, and/or growth of pathogens are stimulated by signals from the root tip, the underlying root tissue can escape invasion. Recent insights into the functions of root border cells, and the regulation of their production by transient exposure to external signals, may shed light on long-standing observations. PMID:21455030

Endogenous cannabinoid receptor ligand induces the migration of human natural killer cells.

PubMed

Kishimoto, Seishi; Muramatsu, Mayumi; Gokoh, Maiko; Oka, Saori; Waku, Keizo; Sugiura, Takayuki

2005-02-01

2-Arachidonoylglycerol is an endogenous ligand for the cannabinoid receptors (CB1 and CB2). Evidence is gradually accumulating which shows that 2-arachidonoylglycerol plays important physiological roles in several mammalian tissues and cells, yet the details remain ambiguous. In this study, we first examined the effects of 2-arachidonoylglycerol on the motility of human natural killer cells. We found that 2-arachidonoylglycerol induces the migration of KHYG-1 cells (a natural killer leukemia cell line) and human peripheral blood natural killer cells. The migration of natural killer cells induced by 2-arachidonoylglycerol was abolished by treating the cells with SR144528, a CB2 receptor antagonist, suggesting that the CB2 receptor is involved in the 2-arachidonoylglycerol-induced migration. In contrast to 2-arachidonoylglycerol, anandamide, another endogenous cannabinoid receptor ligand, did not induce the migration. Delta9-tetrahydrocannabinol, a major psychoactive constituent of marijuana, also failed to induce the migration; instead, the addition of delta9-tetrahydrocannabinol together with 2-arachidonoylglycerol abolished the migration induced by 2-arachidonoylglycerol. It is conceivable that the endogenous ligand for the cannabinoid receptor, that is, 2-arachidonoylglycerol, affects natural killer cell functions such as migration, thereby contributing to the host-defense mechanism against infectious viruses and tumor cells.

The lutheran/basal cell adhesion molecule promotes tumor cell migration by modulating integrin-mediated cell attachment to laminin-511 protein.

PubMed

Kikkawa, Yamato; Ogawa, Takaho; Sudo, Ryo; Yamada, Yuji; Katagiri, Fumihiko; Hozumi, Kentaro; Nomizu, Motoyoshi; Miner, Jeffrey H

2013-10-25

Cell-matrix interactions are critical for tumor cell migration. Lutheran (Lu), also known as basal cell adhesion molecule (B-CAM), competes with integrins for binding to laminin α5, a subunit of LM-511, a major component of basement membranes. Here we show that the preferential binding of Lu/B-CAM to laminin α5 promotes tumor cell migration. The attachment of Lu/B-CAM transfectants to LM-511 was slightly weaker than that of control cells, and this was because Lu/B-CAM disturbed integrin binding to laminin α5. Lu/B-CAM induced a spindle cell shape with pseudopods and promoted cell migration on LM-511. In addition, blocking with an anti-Lu/B-CAM antibody led to a flat cell shape and inhibited migration on LM-511, similar to the effects of an activating integrin β1 antibody. We conclude that tumor cell migration on LM-511 requires that Lu/B-CAM competitively modulates cell attachment through integrins. We suggest that this competitive interaction is involved in a balance between static and migratory cell behaviors.

Drosophila hemocyte migration: an in vivo assay for directional cell migration.

PubMed

Moreira, Carolina G A; Regan, Jennifer C; Zaidman-Rémy, Anna; Jacinto, Antonio; Prag, Soren

2011-01-01

This protocol describes an in vivo assay for random and directed hemocyte migration in Drosophila. Drosophila is becoming an increasingly powerful model system for in vivo cell migration analysis, combining unique genetic tools with translucency of the embryo and pupa, which allows direct imaging and traceability of different cell types. In the assay we present here, we make use of the hemocyte response to epithelium wounding to experimentally induce a transition from random to directed migration. Time-lapse confocal microscopy of hemocyte migration in untreated conditions provides a random cell migration assay that allows identification of molecular mechanisms involved in this complex process. Upon laser-induced wounding of the thorax epithelium, a rapid chemotactic response changes hemocyte migratory behavior into a directed migration toward the wound site. This protocol provides a direct comparison of cells during both types of migration in vivo, and combined with recently developed resources such as transgenic RNAi, is ideal for forward genetic screens.

A time and a place for everything: phylogenetic history and geography as joint predictors of oak plastome phylogeny

Treesearch

Kasey K. Pham; Andrew L. Hipp; Paul S. Manos; Richard C. Cronn

2017-01-01

Owing to high rates of introgressive hybridization, the plastid genome is poorly suited to fine-scale DNA barcoding and phylogenetic studies of the oak genus (Quercus, Fagaceae). At the tips of the oak plastome phylogeny, recent gene migration and reticulation generally cause topology to reflect geographic structure, while deeper branches reflect...

Feminist Collaboratives and Intercultural Inquiry: Constructing an Alternative to the (Not So) Hidden Logics and Practices of University Outreach and Microlending

ERIC Educational Resources Information Center

Clifton, Jennifer

2014-01-01

In an era of globalization, public-private partnerships often tip too easily toward privatization, where global processes of consumption, production, and migration complicate the conditions and consequences of engagement in public life. Like the logic of service, the logic of activist capitalism underlying social entrepreneurship and microlending…

Luminal mitosis drives epithelial cell dispersal within the branching ureteric bud

PubMed Central

Packard, Adam; Georgas, Kylie; Michos, Odyssé; Riccio, Paul; Cebrian, Cristina; Combes, Alexander N.; Ju, Adler; Ferrer-Vaquer, Anna; Hadjantonakis, Anna-Katerina; Zong, Hui; Little, Melissa H.; Costantini, Frank

2013-01-01

Summary The ureteric bud is an epithelial tube that undergoes branching morphogenesis to form the renal collecting system. Though development of a normal kidney depends on proper ureteric bud morphogenesis, the cellular events underlying this process remain obscure. Here, we used time-lapse microscopy together with several genetic labeling methods to observe ureteric bud cell behaviors in developing mouse kidneys. We observed an unexpected cell behavior in the branching tips of the ureteric bud, which we term “mitosis-associated cell dispersal”. Pre-mitotic ureteric tip cells delaminate from the epithelium and divide within the lumen; while one daughter cell retains a basal process, allowing it to reinsert into the epithelium at the site of origin, the other daughter cell reinserts at a position one to three cell diameters away. Given the high rate of cell division in ureteric tips, this cellular behavior causes extensive epithelial cell rearrangements that may contribute to renal branching morphogenesis. PMID:24183650

Differential role of PTEN in transforming growth factor β (TGF-β) effects on proliferation and migration in prostate cancer cells.

PubMed

Kimbrough-Allah, Mawiyah N; Millena, Ana C; Khan, Shafiq A

2018-04-01

Transforming growth factor-β (TGF-β) acts as a tumor suppressor in normal epithelial cells but as a tumor promoter in advanced prostate cancer cells. PI3-kinase pathway mediates TGF-β effects on prostate cancer cell migration and invasion. PTEN inhibits PI3-kinase pathway and is frequently mutated in prostate cancers. We investigated possible role(s) of PTEN in TGF-β effects on proliferation and migration in prostate cancer cells. Expression of PTEN mRNA and proteins were determined using RT-PCR and Western blotting in RWPE1 and DU145 cells. We also studied the role of PTEN in TGF-β effects on cell proliferation and migration in DU145 cells after transient silencing of endogenous PTEN. Conversely, we determined the role of PTEN in cell proliferation and migration after over-expression of PTEN in PC3 cells which lack endogenous PTEN. TGF-β1 and TGF-β3 had no effect on PTEN mRNA levels but both isoforms increased PTEN protein levels in DU145 and RWPE1 cells indicating that PTEN may mediate TGF-β effects on cell proliferation. Knockdown of PTEN in DU145 cells resulted in significant increase in cell proliferation which was not affected by TGF-β isoforms. PTEN overexpression in PC3 cells inhibited cell proliferation. Knockdown of endogenous PTEN enhanced cell migration in DU145 cells, whereas PTEN overexpression reduced migration in PC3 cells and reduced phosphorylation of AKT in response to TGF-β. We conclude that PTEN plays a role in inhibitory effects of TGF-β on cell proliferation whereas its absence may enhance TGF-β effects on activation of PI3-kinase pathway and cell migration. © 2018 Wiley Periodicals, Inc.

Tissue stiffening coordinates morphogenesis by triggering collective cell migration in vivo.

PubMed

Barriga, Elias H; Franze, Kristian; Charras, Guillaume; Mayor, Roberto

2018-02-22

Collective cell migration is essential for morphogenesis, tissue remodelling and cancer invasion. In vivo, groups of cells move in an orchestrated way through tissues. This movement involves mechanical as well as molecular interactions between cells and their environment. While the role of molecular signals in collective cell migration is comparatively well understood, how tissue mechanics influence collective cell migration in vivo remains unknown. Here we investigated the importance of mechanical cues in the collective migration of the Xenopus laevis neural crest cells, an embryonic cell population whose migratory behaviour has been likened to cancer invasion. We found that, during morphogenesis, the head mesoderm underlying the cephalic neural crest stiffens. This stiffening initiates an epithelial-to-mesenchymal transition in neural crest cells and triggers their collective migration. To detect changes in their mechanical environment, neural crest cells use mechanosensation mediated by the integrin-vinculin-talin complex. By performing mechanical and molecular manipulations, we show that mesoderm stiffening is necessary and sufficient to trigger neural crest migration. Finally, we demonstrate that convergent extension of the mesoderm, which starts during gastrulation, leads to increased mesoderm stiffness by increasing the cell density underneath the neural crest. These results show that convergent extension of the mesoderm has a role as a mechanical coordinator of morphogenesis, and reveal a link between two apparently unconnected processes-gastrulation and neural crest migration-via changes in tissue mechanics. Overall, we demonstrate that changes in substrate stiffness can trigger collective cell migration by promoting epithelial-to-mesenchymal transition in vivo. More broadly, our results raise the idea that tissue mechanics combines with molecular effectors to coordinate morphogenesis.

Glial cell migration in the eye disc.

PubMed

Silies, Marion; Yuva, Yeliz; Engelen, Daniel; Aho, Annukka; Stork, Tobias; Klämbt, Christian

2007-11-28

Any complex nervous system is made out of two major cell types, neurons and glial cells. A hallmark of glial cells is their pronounced ability to migrate. En route to their final destinations, glial cells are generally guided by neuronal signals. Here we show that in the developing visual system of Drosophila glial cell migration is largely controlled by glial-glial interactions and occurs independently of axonal contact. Differentiation into wrapping glia is initiated close to the morphogenetic furrow. Using single cell labeling experiments we identified six distinct glial cell types in the eye disc. The migratory glial population is separated from the wrapping glial cells by the so-called carpet cells, extraordinary large glial cells, each covering a surface area of approximately 10,000 epithelial cells. Subsequent cell ablation experiments demonstrate that the carpet glia regulates glial migration in the eye disc epithelium and suggest a new model underlying glial migration and differentiation in the developing visual system.

Low dose of kaempferol suppresses the migration and invasion of triple-negative breast cancer cells by downregulating the activities of RhoA and Rac1.

PubMed

Li, Shoushan; Yan, Ting; Deng, Rong; Jiang, Xuesong; Xiong, Huaping; Wang, Yuan; Yu, Qiao; Wang, Xiaohua; Chen, Cheng; Zhu, Yichao

2017-01-01

Triple-negative breast cancer (TNBC) is an especially aggressive and hard-to-treat disease. Although the anticancer role of kaempferol has been reported in breast cancer, the effect of kaempferol on TNBC remains unclear. This experiment investigated the migration-suppressive role of a low dose of kaempferol in TNBC cells. Wound-healing assays and cell invasion assays were used to confirm the migration and invasion of cells treated with kaempferol or transfected indicated constructs. We evaluated the activations of RhoA, Rac1 and Cdc42 in TNBC cells with a Rho activation assay. A panel of inhibitors of estrogen receptor/progesterone receptor/human epidermal growth factor receptor 2 (ER/PR/HER2) treated non-TNBC (SK-BR-3 and MCF-7) cells and blocked the ER/PR/HER2 activity. Wound-healing assays and Rho activation assays were employed to measure the effect of kaempferol and ER/PR/HER2 inhibitors on Rho activation and cell migration rates. A low dose of kaempferol (20 μmol/L) had a potent inhibitory effect on the migration and invasion of TNBC cells, but not on the migration of non-TNBC (SK-BR-3 and MCF-7) cells. The low dose of kaempferol downregulated the activations of RhoA and Rac1 in TNBC cells. Moreover, the low dose of kaempferol also inhibited the migration and RhoA activations of HER2-silence SK-BR-3 and ER/PR-silence MCF-7 cells. Overexpressed HER2 rescued the cell migration and RhoA and Rac1 activations of kaempferol-treated MDA-MB-231 cells. The low dose of kaempferol inhibits the migration and invasion of TNBC cells via blocking RhoA and Rac1 signaling pathway.

Translocation of an 89-kDa periplasmic protein is associated with Holospora infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwatani, Koichi; Dohra, Hideo; Lang, B. Franz

2005-12-02

The symbiotic bacterium Holospora obtusa infects the macronucleus of the ciliate Paramecium caudatum. After ingestion by its host, an infectious form of Holospora with an electron-translucent tip passes through the host digestive vacuole and penetrates the macronuclear envelope with this tip. To investigate the underlying molecular mechanism of this process, we raised a monoclonal antibody against the tip-specific 89-kDa protein, sequenced this partially, and identified the corresponding complete gene. The deduced protein sequence carries two actin-binding motifs. Indirect immunofluorescence microscopy shows that during escape from the host digestive vacuole, the 89-kDa proteins translocates from the inside to the outside ofmore » the tip. When the bacterium invades the macronucleus, the 89-kDa protein is left behind at the entry point of the nuclear envelope. Transmission electron microscopy shows the formation of fine fibrous structures that co-localize with the antibody-labeled regions of the bacterium. Our findings suggest that the 89-kDa protein plays a role in Holospora's escape from the host digestive vacuole, the migration through the host cytoplasm, and the invasion into the macronucleus.« less

Theory of buttressed marine ice sheet dynamics and its application to the assessment of tipping-point conditions

NASA Astrophysics Data System (ADS)

Pegler, S.

2017-12-01

Understanding the fate of the West Antarctic Ice Sheet is constrained by difficulties of resolving the buttressing effect of ice shelves and its dynamic response to grounding-line migration. This effect may be responsible for protecting a large majority of outlet glaciers in Antarctica against surging into the ocean. I present a theoretical methodology for assessing the positions and stability of grounding lines that incorporates closed-form, dynamic descriptions of ice-shelf buttressing and extensional (stretching) viscous stresses. The method is applied to assess the conditions for grounding-line tipping points. Such points are shown to produce abrupt `cliff-edge' transitions to runaway retreat, representing the so-called marine ice sheet instability. Depending on the bed profile, melt and calving rates, a tipping point can either lie very near to a local maximum in the bed topography or potentially far upstream of it, along a reverse bed. The model predictions for both wide and narrow embayments are validated by numerical simulations and laboratory experiments. A case study of Pine Island Glacier indicates the possibility for long-term stabilisation, with the analytical method affording an extensive exploration of scenarios. The theory also elucidates a mode of grounding-line migration controlled entirely by the determinants of the ice-shelf buttressing force, with a loss of sensitivity to basal conditions, contrasting with the conclusion from one-dimensional theory that the ice shelf is irrelevant. The results provide an interpretive framework for understanding grounding-line dynamics, its coupling with ice-shelf dynamics, an efficient exploration of parameter variation, and a complement to large-scale simulation.

Apparent migration of implantable port devices: normal variations in consideration of BMI.

PubMed

Wyschkon, Sebastian; Löschmann, Jan-Phillip; Scheurig-Münkler, Christian; Nagel, Sebastian; Hamm, Bernd; Elgeti, Thomas

2016-01-01

To evaluate the extent of normal variation in implantable port devices between supine fluoroscopy and upright chest x-ray in relation to body mass index (BMI) based on three different measurement methods. Retrospectively, 80 patients with implanted central venous access port systems from 2012-01-01 until 2013-12-31 were analyzed. Three parameters (two quantitative and one semi-quantitative) were determined to assess port positions: projection of port capsule to anterior ribs (PCP) and intercostal spaces, ratio of extra- and intravascular catheter portions (EX/IV), normalized distance of catheter tip to carina (nCTCD). Changes were analyzed for males and females and normal-weight and overweight patients using analysis of variance with Bonferroni-corrected pairwise comparison. PCP revealed significantly greater changes in chest x-rays in overweight women than in the other groups (p<0.001, F-test). EX/IV showed a significantly higher increase in overweight women than normal-weight women and men and overweight men (p<0.001). nCTCD showed a significantly greater increase in overweight women than overweight men (p = 0.0130). There were no significant differences between the other groups. Inter- and intra-observer reproducibility was high (Cronbach alpha of 0.923-1.0) and best for EX/IV. Central venous port systems show wide normal variations in the projection of catheter tip and port capsule. In overweight women apparent catheter migration is significantly greater compared with normal-weight women and with men. The measurement of EX/IV and PCP are straightforward methods, quick to perform, and show higher reproducibility than measurement of catheter tip-to-carina distance.

Analysis of Histone Deacetylase-Dependent Effects on Cell Migration Using the Stripe Assay.

PubMed

Mertsch, Sonja; Thanos, Solon

2017-01-01

For normal embryonic development/morphogenesis, cell migration and homing are well-orchestrated and important events requiring specific cellular mechanisms. In diseases such as cancer deregulated cell migration represents a major problem. Therefore, numerous efforts are under way to understand the molecular mechanisms of tumor cell migration and to generate more efficient tumor therapies. Cell migration assays are one of the most commonly used functional assays. The wound-healing assay or the Boyden chamber assay are variations of these assays. Nearly all of them are two-dimensional assays and the cells can only migrate on one substrate at a time. This is in contrast to the in vivo situation where the cells are faced simultaneously with different surfaces and interact with different cell types. To approach this in vivo situation we used a modified version of the stripe assay designed by Bonhoeffer and colleagues to examine mechanisms of axonal guidance. The design of this assay allows cells to decide between two different substrates offered at the same time. Utilizing alternating neuronal substrates for migration analyses we can partially mimic the complex in vivo situation for brain tumor cells. Here we describe the detailed protocol to perform a modified version of the stripe assay in order to observe substrate-dependent migration effects in vitro, to analyze the effect of Rho-dependent kinases (ROCKS), of histone deacetylases (HDACs) and of other molecules on glioma cells.

Electromicroinjection of particles into living cells

DOEpatents

Ray, F. Andrew; Cram, L. Scott; Galey, William R.

1988-01-01

Method and apparatus for introducing particles into living cells. Fluorescently-stained human chromosomes are introduced into cultured, mitotic Chinese hamster cells using electromicroinjection. The recipient cells frequently survived the physiological perturbation imposed by a successful chromosome injection. Successfully injected recipient cells maintained viability as evidenced by their ability to be expanded. The technique relies on the surface charge of fluorescently stained chromosomes and their ability to be attracted and repelled to and from the tip of a micropipette. The apparatus includes a micropipette having a tip suitable for piercing the membrane of a target cell and an electrode inserted into the lumen thereof. The target cells and suspended particles are located in an electrically conducted solution, and the lumen of the micropipette is filled with an electrically conducting solution which contacts the electrode located therein. A second electrode is also located in the conducting solution containing the target cells and particles. Voltages applied to the electrode within the micropipette attract the particles to the region of the tip thereof. The particles adhere to the surface of the micropipette with sufficient force that insertion of the micropipette tip and attached particle through the membrane of a target cell will not dislodge the particle. By applying a voltage having the opposite polarity of the attraction voltage, the particles are expelled from the micropipette to which is then withdrawn from the cell body.

Immunocytochemical localization of actin in epithelial cells of rat small intestine by light and electron microscopy.

PubMed

Hagen, S J; Trier, J S

1988-07-01

We used post-embedding immunocytochemical techniques and affinity-purified anti-actin antibody to evaluate localization of actin in epithelial cells of small intestine by fluorescence and electron microscopy. Small intestine was fixed with 2% formaldehyde-0.1% glutaraldehyde and embedded in Lowicryl K4M. One-micron or thin sections were stained with antibody followed by rhodamine- or colloidal gold-labeled goat anti-rabbit IgG, respectively. Label was present overlying microvilli, the apical terminal web, and the cytoplasm directly adjacent to occluding and intermediate junctions. Label was associated with outer mitochondrial membranes of all cells and the supranuclear Golgi region of goblet cells. Lateral cytoplasmic interdigitations between mature cells and subplasmalemmal filaments next to intrusive cells were densely labeled. The cytoplasm adjacent to unplicated domains of lateral membrane was focally labeled. Label was prominent over organized filament bundles within the subplasmalemmal web at the base of mature cells, whereas there was focal labeling of the cytoplasm adjacent to the basal membrane of undifferentiated cells. Basolateral epithelial cell processes were labeled. Label was focally present overlying the cellular ground substance. Our results demonstrate that actin is distributed in a distinctive fashion within intestinal epithelial cells. This distribution suggests that in addition to its function as a structural protein, actin may participate in regulation of epithelial tight junction permeability, in motile processes including migration of cells from the crypt to the villus tip, in accommodation of intrusive intraepithelial cells and in adhesion of cells to one another and to their substratum.

Migration of guinea pig airway epithelial cells in response to bombesin analogues.

PubMed

Kim, J S; McKinnis, V S; White, S R

1997-03-01

Bombesin-like peptides within neuroepithelial cells elicit proliferation of normal and malignant airway epithelial cells. It is not clear that these peptides also elicit epithelial cell migration, a necessary component of airway repair after injury. We studied the effects of the bombesin analogues, gastrin releasing peptide (GRP) and neuromedin B (NMB), on guinea pig tracheal epithelial cell (GPTEC) migration. Primary GPTEC were allowed to migrate through 8-microm-pore gelatin-coated filters for 6 h in a chemotaxis chamber, after which the number of migrated cells per 10 high power fields (10 hpf) were counted. Both neuropeptides elicited migration of GPTEC: 24.8 +/- 4.5 cells for 10(-11) M NMB (P < 0.001 versus control, n = 4) and 16.8 +/- 1.2 cells for 10(-12) M GRP (P < 0.001 versus control, n = 8). Migration was attenuated substantially by a bombesin receptor antagonist. To investigate further the relationship of migration through a filter to the repair of a damaged epithelium, we studied the repair of epithelial cells by video microscopy. A 0.3- to 0.5-microm2 wound was created in a confluent monolayer of GPTEC, and wound closure was followed over 24 h. There was no significant acceleration in the rate of repair of GRP- or NMB-stimulated monolayers compared to control. These data demonstrate that GRP and NMB elicit migration of airway epithelial cells but may not play a significant role in the early repair of the airway epithelium in culture.

NFAT5 promotes proliferation and migration of lung adenocarcinoma cells in part through regulating AQP5 expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Kai, E-mail: gk161@163.com; Department of Respiration, 161th Hospital, PLA, Wuhan 430015; Jin, Faguang, E-mail: jinfag@fmmu.edu.cn

2015-09-25

The osmoregulated transcription factor nuclear factor of activated T-cells 5(NFAT5), has been found to play important roles in the development of many kinds of human cancers, including breast cancer, colon carcinoma, renal cell carcinoma and melanoma. The aim of the present study was to determine whether NFAT5 is involved in the proliferation and migration of lung adenocarcinoma cells. We found that NFAT5 was upregulated in lung adenocarcinoma cells and knockdown of NFAT5 decreased proliferation and migration of the cells, accompanied by a significant reduction in the expression of AQP5. AQP5 was upregulated in lung adenocarcinoma cells and knockdown of AQP5more » also inhibited proliferation and migration of the cells as knockdown of NFAT5 did. Moreover, overexpression of NFAT5 promoted proliferation and migration of lung adenocarcinoma cells, accompanied by a significant increase in the expression of AQP5. These results indicate that NFAT5 plays important roles in proliferation and migration of human lung adenocarcinoma cells through regulating AQP5 expression, providing a new therapeutic option for lung adenocarcinoma therapy. - Highlights: • NFAT5 expression is higher in lung adenocarcinoma cells compared with normal cells. • NFAT5 knockdown decreases proliferation and migration of lung adenocarcinoma cells. • Knockdown of NFAT5 reduces AQP5 expression in human lung adenocarcinoma cells. • Overexpression of NFAT5 promotes proliferation and migration of lung adenocarcinoma cells. • Overexpression of NFAT5 increases AQP5 expression in human lung adenocarcinoma cells.« less

Downregulation of NEDD9 by apigenin suppresses migration, invasion, and metastasis of colorectal cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Jin; Van Wie, Peter G.; Fai, Leonard Yenwong

Apigenin is a natural flavonoid which possesses multiple anti-cancer properties such as anti-proliferation, anti-inflammation, and anti-metastasis in many types of cancers including colorectal cancer. Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a multi-domain scaffolding protein of the Cas family which has been shown to correlate with cancer metastasis and progression. The present study investigates the role of NEDD9 in apigenin-inhibited cell migration, invasion, and metastasis of colorectal adenocarcinoma DLD1 and SW480 cells. The results show that knockdown of NEDD9 inhibited cell migration, invasion, and metastasis and that overexpression of NEDD9 promoted cell migration and invasion of DLD1 cellsmore » and SW4890 cells. Apigenin treatment attenuated NEDD9 expression at protein level, resulting in reduced phosphorylations of FAK, Src, and Akt, leading to inhibition on cell migration, invasion, and metastasis of both DLD1 and SW480 cells. The present study has demonstrated that apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt cascade in colorectal cancer cells. NEDD9 may function as a biomarker for evaluation of cancer aggressiveness and for selection of therapeutic drugs against cancer progression. - Highlights: • Apigenin inhibits migration, invasion, and metastasis of colorectal cancer cells. • Apigenin downregulates NEDD9. • Apigenin decreases phosphorylations of FAK, Src, and Akt. • Apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt.« less

Dental pulp stem cell-derived chondrogenic cells demonstrate differential cell motility in type I and type II collagen hydrogels.

PubMed

Yao, Li; Flynn, Nikol

2018-06-01

Advances in the development of biomaterials and stem cell therapy provide a promising approach to regenerating degenerated discs. The normal nucleus pulposus (NP) cells exhibit similar phenotype to chondrocytes. Because dental pulp stem cells (DPSCs) can be differentiated into chondrogenic cells, the DPSCs and DPSCs-derived chondrogenic cells encapsulated in type I and type II collagen hydrogels can potentially be transplanted into degenerated NP to repair damaged tissue. The motility of transplanted cells is critical because the cells need to migrate away from the hydrogels containing the cells of high density and disperse through the NP tissue after implantation. The purpose of this study was to determine the motility of DPSC and DPSC-derived chondrogenic cells in type I and type II collagen hydrogels. The time lapse imaging that recorded cell migration was analyzed to quantify the cell migration velocity and distance. The cell viability of DPSCs in native or poly(ethylene glycol) ether tetrasuccinimidyl glutarate (4S-StarPEG)-crosslinked type I and type II collagen hydrogels was determined using LIVE/DEAD cell viability assay and AlamarBlue assay. DPSCs were differentiated into chondrogenic cells. The migration of DPSCs and DPSC-derived chondrogenic cells in these hydrogels was recorded using a time lapse imaging system. This study was funded by the Regional Institute on Aging and Wichita Medical Research and Education Foundation, and the authors declare no competing interest. DPSCs showed high cell viability in non-crosslinked and crosslinked collagen hydrogels. DPSCs migrated in collagen hydrogels, and the cell migration speed was not significantly different in either type I collagen or type II collagen hydrogels. The migration speed of DPSC-derived chondrogenic cells was higher in type I collagen hydrogel than in type II collagen hydrogel. Crosslinking of type I collagen with 4S-StarPEG significantly reduced the cell migration speed of DPSC-derived chondrogenic cells. After implantation of collagen hydrogels encapsulating DPSCs or DPSC-derived chondrogenic cells, the cells can potentially migrate from the hydrogels and migrate into the NP tissue. This study also explored the differential cell motility of DPSCs and DPSC-derived chondrogenic cells in these collagen hydrogels. Copyright © 2018 Elsevier Inc. All rights reserved.

Mitochondrial Ca{sup 2+} uniporter is critical for store-operated Ca{sup 2+} entry-dependent breast cancer cell migration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Shihao; Guangzhou No.12 Hospital, Guangzhou; Wang, Xubu

2015-02-27

Metastasis of cancer cells is a complicated multistep process requiring extensive and continuous cytosolic calcium modulation. Mitochondrial Ca{sup 2+} uniporter (MCU), a regulator of mitochondrial Ca{sup 2+} uptake, has been implicated in energy metabolism and various cellular signaling processes. However, whether MCU contributes to cancer cell migration has not been established. Here we examined the expression of MCU mRNA in the Oncomine database and found that MCU is correlated to metastasis and invasive breast cancer. MCU inhibition by ruthenium red (RuR) or MCU silencing by siRNA abolished serum-induced migration in MDA-MB-231 breast cancer cells and reduced serum- or thapsigargin (TG)-inducedmore » store-operated Ca2+ entry (SOCE). Serum-induced migrations in MDA-MB-231 cells were blocked by SOCE inhibitors. Our results demonstrate that MCU plays a critical role in breast cancer cell migration by regulating SOCE. - Highlights: • MCU is correlated to metastasis and invasive breast cancer. • MCU inhibition abolished serum-induced migration in MDA-MB-231 breast cancer cells and reduced serum- or TG-induced SOCE. • Serum-induced migrations in MDA-MB-231 cells were blocked by SOCE inhibitors. • MCU plays a critical role in MDA-MB-231 cell migration by regulating SOCE.« less

Directional Collective Cell Migration Emerges as a Property of Cell Interactions

PubMed Central

Woods, Mae L.; Carmona-Fontaine, Carlos; Barnes, Chris P.; Couzin, Iain D.; Mayor, Roberto; Page, Karen M.

2014-01-01

Collective cell migration is a fundamental process, occurring during embryogenesis and cancer metastasis. Neural crest cells exhibit such coordinated migration, where aberrant motion can lead to fatality or dysfunction of the embryo. Migration involves at least two complementary mechanisms: contact inhibition of locomotion (a repulsive interaction corresponding to a directional change of migration upon contact with a reciprocating cell), and co-attraction (a mutual chemoattraction mechanism). Here, we develop and employ a parameterized discrete element model of neural crest cells, to investigate how these mechanisms contribute to long-range directional migration during development. Motion is characterized using a coherence parameter and the time taken to reach, collectively, a target location. The simulated cell group is shown to switch from a diffusive to a persistent state as the response-rate to co-attraction is increased. Furthermore, the model predicts that when co-attraction is inhibited, neural crest cells can migrate into restrictive regions. Indeed, inhibition of co-attraction in vivo and in vitro leads to cell invasion into restrictive areas, confirming the prediction of the model. This suggests that the interplay between the complementary mechanisms may contribute to guidance of the neural crest. We conclude that directional migration is a system property and does not require action of external chemoattractants. PMID:25181349

Are fingernails a key to unlocking the puzzle of mammalian limb regeneration?

PubMed

Lehoczky, Jessica A

2017-06-01

Some mammalian digit tips, including those of mice and human children, can regenerate following amputation, whereas mammalian limb regeneration does not occur. One major difference between the digit tip and the rest of the limb is the presence of the nail, which is necessary for this type of regeneration. This couples well with the finding that canonical Wnt signalling and Lgr6, an agonist of Wnt signalling that marks nail stem cells, are necessary for digit tip regeneration. This viewpoint essay discusses the role of the nail in digit tip regeneration and explores whether nail stem cells and their presumptive niche can be solely accountable for why regeneration is possible in the digit tip, but not the rest of the limb. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The role of Exo70 in vascular smooth muscle cell migration.

PubMed

Ma, Wenqing; Wang, Yu; Yao, Xiaomeng; Xu, Zijian; An, Liguo; Yin, Miao

2016-01-01

As a key subunit of the exocyst complex, Exo70 has highly conserved sequence and is widely found in yeast, mammals, and plants. In yeast, Exo70 mediates the process of exocytosis and promotes anchoring and integration of vesicles with the plasma membrane. In mammalian cells, Exo70 is involved in maintaining cell morphology, cell migration, cell connection, mRNA splicing, and other physiological processes, as well as participating in exocytosis. However, Exo70's function in mammalian cells has yet to be fully recognized. In this paper, the expression of Exo70 and its role in cell migration were studied in a rat vascular smooth muscle cell line A7r5. Immunofluorescent analysis the expression of Exo70, α-actin, and tubulin in A7r5 cells showed a co-localization of Exo70 and α-actin, we treated the cells with cytochalasin B to depolymerize α-actin, in order to further confirm the co-localization of Exo70 and α-actin. We analyzed Exo70 co-localization with actin at the edge of migrating cells by wound-healing assay to establish whether Exo70 might play a role in cell migration. Next, we analyzed the migration and invasion ability of A7r5 cells before and after RNAi silencing through the wound healing assay and transwell assay. The mechanism of interaction between Exo70 and cytoskeleton can be clarified by the immunoprecipitation techniques and wound-healing assay. The results showed that Exo70 and α-actin were co-localized at the leading edge of migrating cells. The ability of A7r5 to undergo cell migration was decreased when Exo70 expression was silenced by RNAi. Reducing Exo70 expression in RNAi treated A7r5 cells significantly lowered the invasion and migration ability of these cells compared to the normal cells. These results indicate that Exo70 participates in the process of A7r5 cell migration. This research is importance for the study on the pathological process of vascular intimal hyperplasia, since it provides a new research direction for the treatment of cardiovascular diseases such as atherosclerosis and restenosis after balloon angioplasty.

Roles of endothelial A-type lamins in migration of T cells on and under endothelial layers

NASA Astrophysics Data System (ADS)

Song, Kwang Hoon; Lee, Jaehyun; Park, Hyoungjun; Kim, Hye Mi; Park, Jeehun; Kwon, Keon Woo; Doh, Junsang

2016-03-01

Stiff nuclei in cell-dense microenvironments may serve as distinct biomechanical cues for cell migration, but such a possibility has not been tested experimentally. As a first step addressing this question, we altered nuclear stiffness of endothelial cells (ECs) by reducing the expression of A-type lamins using siRNA, and investigated the migration of T cells on and under EC layers. While most T cells crawling on control EC layers avoided crossing over EC nuclei, a significantly higher fraction of T cells on EC layers with reduced expression of A-type lamins crossed over EC nuclei. This result suggests that stiff EC nuclei underlying T cells may serve as “duro-repulsive” cues to direct T cell migration toward less stiff EC cytoplasm. During subendothelial migration under EC layers with reduced expression of A-type lamins, T cells made prolonged contact and substantially deformed EC nuclei, resulting in reduced speed and directional persistence. This result suggests that EC nuclear stiffness promotes fast and directionally persistent subendothelial migration of T cells by allowing minimum interaction between T cells and EC nuclei.

The aquatic hyphomycete Heliscus lugdunensis protects its hyphae tip cells from cadmium: A micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy study

NASA Astrophysics Data System (ADS)

Isaure, Marie-Pierre; Leyh, Benjamin; Salomé, Murielle; Krauss, Gerd-Joachim; Schaumlöffel, Dirk; Dobritzsch, Dirk

2017-11-01

Aquatic fungi can be used to evaluate the functioning of natural ecosystems. Heliscus lugdunensis is an early colonizer of allochthone leafs. Since this aquatic hyphomycete is able to develop in metal contaminated habitats and tolerates cadmium, it appears to be a good candidate to investigate adaptation to metal pollution. This study aimed at examining the sequestration of Cd in the hyphae of H. lugdunensis, and particularly the role of the tip cells. For that, H. lugdunensis growth was evaluated under various Cd concentrations, and a combination of synchrotron micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy was carried out to determine the compartments of Cd accumulation and the Cd chemical species, respectively. Results showed that the hyphal tip cells were depleted in Cd, and that the metal was stored in older cells. Cd was mainly associated with sulfur ligands and to a lesser extent bound to phosphates and carboxyl/hydroxyl groups from cell wall and/or organic acids. Finally, the aquatic fungus was able to maintain the tip cell as a functional system, thus allowing the colonization of contaminated environments.

Tip cell-specific requirement for an atypical Gpr124- and Reck-dependent Wnt/β-catenin pathway during brain angiogenesis

PubMed Central

Vanhollebeke, Benoit; Stone, Oliver A; Bostaille, Naguissa; Cho, Chris; Zhou, Yulian; Maquet, Emilie; Gauquier, Anne; Cabochette, Pauline; Fukuhara, Shigetomo; Mochizuki, Naoki; Nathans, Jeremy; Stainier, Didier YR

2015-01-01

Despite the critical role of endothelial Wnt/β-catenin signaling during central nervous system (CNS) vascularization, how endothelial cells sense and respond to specific Wnt ligands and what aspects of the multistep process of intra-cerebral blood vessel morphogenesis are controlled by these angiogenic signals remain poorly understood. We addressed these questions at single-cell resolution in zebrafish embryos. We identify the GPI-anchored MMP inhibitor Reck and the adhesion GPCR Gpr124 as integral components of a Wnt7a/Wnt7b-specific signaling complex required for brain angiogenesis and dorsal root ganglia neurogenesis. We further show that this atypical Wnt/β-catenin signaling pathway selectively controls endothelial tip cell function and hence, that mosaic restoration of single wild-type tip cells in Wnt/β-catenin-deficient perineural vessels is sufficient to initiate the formation of CNS vessels. Our results identify molecular determinants of ligand specificity of Wnt/β-catenin signaling and provide evidence for organ-specific control of vascular invasion through tight modulation of tip cell function. DOI: http://dx.doi.org/10.7554/eLife.06489.001 PMID:26051822

Endothelial basement membrane limits tip cell formation by inducing Dll4/Notch signalling in vivo.

PubMed

Stenzel, Denise; Franco, Claudio A; Estrach, Soline; Mettouchi, Amel; Sauvaget, Dominique; Rosewell, Ian; Schertel, Andreas; Armer, Hannah; Domogatskaya, Anna; Rodin, Sergey; Tryggvason, Karl; Collinson, Lucy; Sorokin, Lydia; Gerhardt, Holger

2011-10-28

How individual components of the vascular basement membrane influence endothelial cell behaviour remains unclear. Here we show that laminin α4 (Lama4) regulates tip cell numbers and vascular density by inducing endothelial Dll4/Notch signalling in vivo. Lama4 deficiency leads to reduced Dll4 expression, excessive filopodia and tip cell formation in the mouse retina, phenocopying the effects of Dll4/Notch inhibition. Lama4-mediated Dll4 expression requires a combination of integrins in vitro and integrin β1 in vivo. We conclude that appropriate laminin/integrin-induced signalling is necessary to induce physiologically functional levels of Dll4 expression and regulate branching frequency during sprouting angiogenesis in vivo.

Endothelial basement membrane limits tip cell formation by inducing Dll4/Notch signalling in vivo

PubMed Central

Stenzel, Denise; Franco, Claudio A; Estrach, Soline; Mettouchi, Amel; Sauvaget, Dominique; Rosewell, Ian; Schertel, Andreas; Armer, Hannah; Domogatskaya, Anna; Rodin, Sergey; Tryggvason, Karl; Collinson, Lucy; Sorokin, Lydia; Gerhardt, Holger

2011-01-01

How individual components of the vascular basement membrane influence endothelial cell behaviour remains unclear. Here we show that laminin α4 (Lama4) regulates tip cell numbers and vascular density by inducing endothelial Dll4/Notch signalling in vivo. Lama4 deficiency leads to reduced Dll4 expression, excessive filopodia and tip cell formation in the mouse retina, phenocopying the effects of Dll4/Notch inhibition. Lama4-mediated Dll4 expression requires a combination of integrins in vitro and integrin β1 in vivo. We conclude that appropriate laminin/integrin-induced signalling is necessary to induce physiologically functional levels of Dll4 expression and regulate branching frequency during sprouting angiogenesis in vivo. PMID:21979816

Migration of lymphocytes on fibronectin-coated surfaces: temporal evolution of migratory parameters

NASA Technical Reports Server (NTRS)

Bergman, A. J.; Zygourakis, K.; McIntire, L. V. (Principal Investigator)

1999-01-01

Lymphocytes typically interact with implanted biomaterials through adsorbed exogenous proteins. To provide a more complete characterization of these interactions, analysis of lymphocyte migration on adsorbed extracellular matrix proteins must accompany the commonly performed adhesion studies. We report here a comparison of the migratory and adhesion behavior of Jurkat cells (a T lymphoblastoid cell line) on tissue culture treated and untreated polystyrene surfaces coated with various concentrations of fibronectin. The average speed of cell locomotion showed a biphasic response to substrate adhesiveness for cells migrating on untreated polystyrene and a monotonic decrease for cells migrating on tissue culture-treated polystyrene. A modified approach to the persistent random walk model was implemented to determine the time dependence of cell migration parameters. The random motility coefficient showed significant increases with time when cells migrated on tissue culture-treated polystyrene surfaces, while it remained relatively constant for experiments with untreated polystyrene plates. Finally, a cell migration computer model was developed to verify our modified persistent random walk analysis. Simulation results suggest that our experimental data were consistent with temporally increasing random motility coefficients.

Spatial distribution of filament elasticity determines the migratory behaviors of a cell

PubMed Central

Harn, Hans I-Chen; Hsu, Chao-Kai; Wang, Yang-Kao; Huang, Yi-Wei; Chiu, Wen-Tai; Lin, Hsi-Hui; Cheng, Chao-Min; Tang, Ming-Jer

2016-01-01

ABSTRACT Any cellular response leading to morphological changes is highly tuned to balance the force generated from structural reorganization, provided by actin cytoskeleton. Actin filaments serve as the backbone of intracellular force, and transduce external mechanical signal via focal adhesion complex into the cell. During migration, cells not only undergo molecular changes but also rapid mechanical modulation. Here we focus on determining, the role of spatial distribution of mechanical changes of actin filaments in epithelial, mesenchymal, fibrotic and cancer cells with non-migration, directional migration, and non-directional migration behaviors using the atomic force microscopy. We found 1) non-migratory cells only generated one type of filament elasticity, 2) cells generating spatially distributed two types of filament elasticity showed directional migration, and 3) pathologic cells that autonomously generated two types of filament elasticity without spatial distribution were actively migrating non-directionally. The demonstration of spatial regulation of filament elasticity of different cell types at the nano-scale highlights the coupling of cytoskeletal function with physical characters at the sub-cellular level, and provides new research directions for migration related disease. PMID:26919488

Role of the p55-gamma subunit of PI3K in ALK-induced cell migration: RNAi-based selection of cell migration regulators.

PubMed

Seo, Minchul; Kim, Jong-Heon; Suk, Kyoungho

2017-05-04

Recently, unbiased functional genetic selection identified novel cell migration-regulating genes. This RNAi-based functional selection was performed using 63,996 pooled lentiviral shRNAs targeting 21,332 mouse genes. After five rounds of selection using cells with accelerated or impaired migration, shRNAs were retrieved and identified by half-hairpin barcode sequencing using cells with the selected phenotypes. This selection process led to the identification of 29 novel cell migration regulators. One of these candidates, anaplastic lymphoma kinase (ALK), was further investigated. Subsequent studies revealed that ALK promoted cell migration through the PI3K-AKT pathway via the p55γ regulatory subunit of PI3K, rather than more commonly used p85 subunit. Western blot and immunohistochemistry studies using mouse brain tissues revealed similar temporal expression patterns of ALK, phospho-p55γ, and phospho-AKT during different stages of development. These data support an important role for the p55γ subunit of PI3K in ALK-induced cell migration during brain development.

Vinculin is required for cell polarization, migration, and extracellular matrix remodeling in 3D collagen

PubMed Central

Thievessen, Ingo; Fakhri, Nikta; Steinwachs, Julian; Kraus, Viola; McIsaac, R. Scott; Gao, Liang; Chen, Bi-Chang; Baird, Michelle A.; Davidson, Michael W.; Betzig, Eric; Oldenbourg, Rudolf; Waterman, Clare M.; Fabry, Ben

2015-01-01

Vinculin is filamentous (F)-actin-binding protein enriched in integrin-based adhesions to the extracellular matrix (ECM). Whereas studies in 2-dimensional (2D) tissue culture models have suggested that vinculin negatively regulates cell migration by promoting cytoskeleton–ECM coupling to strengthen and stabilize adhesions, its role in regulating cell migration in more physiologic, 3-dimensional (3D) environments is unclear. To address the role of vinculin in 3D cell migration, we analyzed the morphodynamics, migration, and ECM remodeling of primary murine embryonic fibroblasts (MEFs) with cre/loxP-mediated vinculin gene disruption in 3D collagen I cultures. We found that vinculin promoted 3D cell migration by increasing directional persistence. Vinculin was necessary for persistent cell protrusion, cell elongation, and stable cell orientation in 3D collagen, but was dispensable for lamellipodia formation, suggesting that vinculin-mediated cell adhesion to the ECM is needed to convert actin-based cell protrusion into persistent cell shape change and migration. Consistent with this finding, vinculin was necessary for efficient traction force generation in 3D collagen without affecting myosin II activity and promoted 3D collagen fiber alignment and macroscopical gel contraction. Our results suggest that vinculin promotes directionally persistent cell migration and tension-dependent ECM remodeling in complex 3D environments by increasing cell–ECM adhesion and traction force generation.—Thievessen, I., Fakhri, N., Steinwachs, J., Kraus, V., McIsaac, R. S., Gao, L., Chen, B.-C., Baird, M. A., Davidson, M. W., Betzig, E., Oldenbourg, R., Waterman, C., M., Fabry, B. Vinculin is required for cell polarization, migration, and extracellular matrix remodeling in 3D collagen. PMID:26195589

Carbon Ion Irradiation Inhibits Glioma Cell Migration Through Downregulation of Integrin Expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rieken, Stefan, E-mail: Stefan.Rieken@med.uni-heidelberg.de; Habermehl, Daniel; Wuerth, Lena

2012-05-01

Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration. Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. Results: Single photon doses of 2 Gy and 10 Gy enhanced {alpha}{sub {nu}}{beta}{sub 3} and {alpha}{sub {nu}}{beta}{sub 5} integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration onmore » both Vn and Fn. Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.« less

Guidance signalling regulates leading edge behaviour during collective cell migration of cardiac cells in Drosophila.

PubMed

Raza, Qanber; Jacobs, J Roger

2016-11-15

Collective cell migration is the coordinated movement of cells, which organize tissues during morphogenesis, repair and some cancers. The motile cell membrane of the advancing front in collective cell migration is termed the Leading Edge. The embryonic development of the vertebrate and Drosophila hearts are both characterized by the coordinated medial migration of a bilateral cluster of mesodermal cells. In Drosophila, the cardioblasts form cohesive bilateral rows that migrate collectively as a unit towards the dorsal midline to form the dorsal vessel. We have characterized the collective cell migration of cardioblasts as an in vivo quantitative model to study the behaviour of the Leading Edge. We investigated whether guidance signalling through Slit and Netrin pathways plays a role in cell migration during heart development. Through time-lapse imaging and quantitative assessment of migratory behaviour of the cardioblasts in loss-of-function mutants, we demonstrate that both Slit and Netrin mediated signals are autonomously and concomitantly required to maximize migration velocity, filopodial and lamellipodial activities. Additionally, we show that another Slit and Netrin receptor, Dscam1, the role of which during heart development was previously unknown, is required for both normal migration of cardioblasts and luminal expansion. Leading edge behaviour analysis revealed a dosage dependent genetic interaction between Slit and Netrin receptors suggesting that downstream signalling through these receptors converge on a common output that increases leading edge activity of the cardioblasts. Finally, we found that guidance signalling maintains the balance between epithelial and mesenchymal characteristics of the migrating cardioblasts. Copyright © 2016 Elsevier Inc. All rights reserved.

Modeled microgravity suppressed invasion and migration of human glioblastoma U87 cells through downregulating store-operated calcium entry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zi-xuan; Rao, Wei; Wang, Huan

Glioblastoma is the most common brain tumor and is characterized with robust invasion and migration potential resulting in poor prognosis. Previous investigations have demonstrated that modeled microgravity (MMG) could decline the cell proliferation and attenuate the metastasis potential in several cell lines. In this study, we studied the effects of MMG on the invasion and migration potentials of glioblastoma in human glioblastoma U87 cells. We found that MMG stimulation significantly attenuated the invasion and migration potentials, decreased thapsigargin (TG) induced store-operated calcium entry (SOCE) and downregulated the expression of Orai1 in U87 cells. Inhibition of SOCE by 2-APB or stromalmore » interaction molecule 1 (STIM1) downregulation both mimicked the effects of MMG on the invasion and migration potentials in U87 cells. Furthermore, upregulation of Orai1 significantly weakened the effects of MMG on the invasion and migration potentials in U87 cells. Therefore, these findings indicated that MMG stimulation inhibited the invasion and migration potentials of U87 cells by downregulating the expression of Orai1 and sequentially decreasing the SOCE, suggesting that MMG might be a new potential therapeutic strategy in glioblastoma treatment in the future. - Highlights: • Modeled microgravity (MMG) suppressed migration and invasion in U87 cells. • MMG downregulated the SOCE and the expression of Orai1. • SOCE inhibition mimicked the effects of MMG on migration and invasion potentials. • Restoration of SOCE diminished the effects of MMG on migration and invasion.« less

The E3 ubiquitin ligase NEDD4 mediates cell migration signaling of EGFR in lung cancer cells.

PubMed

Shao, Genbao; Wang, Ranran; Sun, Aiqin; Wei, Jing; Peng, Ke; Dai, Qian; Yang, Wannian; Lin, Qiong

2018-02-19

EGFR-dependent cell migration plays an important role in lung cancer progression. Our previous study observed that the HECT E3 ubiquitin ligase NEDD4 is significantly correlated with tumor metastasis and required for migration and invasion signaling of EGFR in gastric cancer cells. However, how NEDD4 promotes the EGFR-dependent lung cancer cell migration is unknown. This study is to elucidate the mechanism by which NEDD4 mediates the EGFR lung cancer migration signaling. Lentiviral vector-loaded NEDD4 shRNA was used to deplete endogenous NEDD4 in lung cancer cell lines. Effects of the NEDD4 knockdown on the EGFR-dependent or independent lung cancer cell migration were determined using the wound-healing and transwell assays. Association of NEDD4 with activated EGFR was assayed by co-immunoprecipitation. Co-expression of NEDD4 with EGFR or PTEN was determined by immunohistochemical (IHC) staining in 63 lung adenocarcinoma tissue samples. Effects of NEDD4 ectopic expression or knockdown on PTEN ubiquitination and down-regulation, AKT activation and lysosomal secretion were examined using the GST-Uba pulldown assay, immunoblotting, immunofluorescent staining and a human cathepsin B ELISA assay respectively. The specific cathepsin B inhibitor CA-074Me was used for assessing the role of cathepsin B in lung cancer cell migration. Knockdown of NEDD4 significantly reduced EGF-stimulated cell migration in non-small cell lung carcinoma (NSCLC) cells. Co-immunoprecipitation assay found that NEDD4 is associated with EGFR complex upon EGF stimulation, and IHC staining indicates that NEDD4 is co-expressed with EGFR in lung adenocarcinoma tumor tissues, suggesting that NEDD4 might mediate lung cancer cell migration by interaction with the EGFR signaling complex. Interestingly, NEDD4 promotes the EGF-induced cathepsin B secretion, possibly through lysosomal exocytosis, as overexpression of the ligase-dead mutant of NEDD4 impedes lysosomal secretion, and knockdown of NEDD4 significantly reduced extracellular amount of cathepsin B induced by EGF. Consistent with the role of NEDD4, cathepsin B is pivotal for both basal and the EGF-stimulated lung cancer cell migration. Our studies propose a novel mechanism underlying the EGFR-promoted lung cancer cell migration that is mediated by NEDD4 through regulation of cathepsin B secretion. NEDD4 mediates the EGFR lung cancer cell migration signaling through promoting lysosomal secretion of cathepsin B.

An intact centrosome is required for the maintenance of polarization during directional cell migration.

PubMed

Wakida, Nicole M; Botvinick, Elliot L; Lin, Justin; Berns, Michael W

2010-12-23

Establishing and maintaining polarization is critical during cell migration. It is known that the centrosome contains numerous proteins whose roles of organizing the microtubule network range include nucleation, stabilization and severing. It is not known whether the centrosome is necessary to maintain polarization. Due to its role as the microtubule organizing center, we hypothesize that the centrosome is necessary to maintain polarization in a migrating cell. Although there have been implications of its role in cell migration, there is no direct study of the centrosome's role in maintaining polarization. In this study we ablate the centrosome by intracellular laser irradiation to understand the role of the centrosome in two vastly different cell types, human osteosarcoma (U2OS) and rat kangaroo kidney epithelial cells (PtK). The PtK cell line has been extensively used as a model for cytoskeletal dynamics during cell migration. The U2OS cell line serves as a model for a complex, single migrating cell. In this study we use femtosecond near-infrared laser irradiation to remove the centrosome in migrating U2OS and PtK2 cells. Immunofluorescence staining for centrosomal markers verified successful irradiation with 94% success. A loss of cell polarization is observed between 30 and 90 minutes following removal of the centrosome. Changes in cell shape are correlated with modifications in microtubule and actin organization. Changes in cell morphology and microtubule organization were quantified revealing significant depolarization resulting from centrosome irradiation. This study demonstrates that the centrosome is necessary for the maintenance of polarization during directed cell migration in two widely different cell types. Removal of the centrosome from a polarized cell results in the reorganization of the microtubule network into a symmetric non-polarized phenotype. These results demonstrate that the centrosome plays a critical role in the maintenance of cytoskeletal asymmetry during cell migration.

Parallel macromolecular delivery and biochemical/electrochemical interface to cells employing nanostructures

DOEpatents

McKnight, Timothy E; Melechko, Anatoli V; Griffin, Guy D; Guillorn, Michael A; Merkulov, Vladimir L; Simpson, Michael L

2015-03-31

Systems and methods are described for parallel macromolecular delivery and biochemical/electrochemical interface to whole cells employing carbon nanostructures including nanofibers and nanotubes. A method includes providing a first material on at least a first portion of a first surface of a first tip of a first elongated carbon nanostructure; providing a second material on at least a second portion of a second surface of a second tip of a second elongated carbon nanostructure, the second elongated carbon nanostructure coupled to, and substantially parallel to, the first elongated carbon nanostructure; and penetrating a boundary of a biological sample with at least one member selected from the group consisting of the first tip and the second tip.

Irradiation of breast cancer cells enhances CXCL16 ligand expression and induces the migration of natural killer cells expressing the CXCR6 receptor.

PubMed

Yoon, Mee Sun; Pham, Chanh Tin; Phan, Minh-Trang Thi; Shin, Dong-Jun; Jang, Youn-Young; Park, Min-Ho; Kim, Sang-Ki; Kim, Seokho; Cho, Duck

2016-12-01

Few studies have examined the migration pattern of natural killer (NK) cells, especially after radiation treatment for cancer. We investigated whether irradiation can modulate the expression of chemokines in cancer cells and the migration of NK cells to irradiated tumor cells. The expression of chemokine receptors (CXCR3, CXCR4 and CXCR6) on interleukin-2 (IL-2)/IL-15-activated NK cells was assessed using flow cytometry. Related chemokine ligands (CXCL11, CXCL12 and CXCL16) in human breast cancer cell lines (MCF7, SKBR3 and MDA-MB231) irradiated at various doses were assessed using reverse transcription-polymerase chain reaction (RT-PCR), fluorescence-activated cell sorting (FACS) and enzyme-linked immunosorbent assay (ELISA). The cell-free culture supernatant was collected 96 h after irradiation of breast cancer cell lines for migration and blocking assays. The activated NK cells expressed CXCR6. Expression of the CXCR6 ligand CXCL16 increased in a time- and dose-dependent manner in all analyzed cancer cell lines. CXCL16 expression was statistically significantly enhanced in all breast cancer cell lines on day 3 after 20 Gy irradiation. Activated NK cells migration correlated with CXCL16 concentration (R 2  = 0.91; P <0.0001). Significantly enhanced migration of NK cells to irradiated cancer cells was observed for a dose of 20 Gy in MCF7 (P = 0.043) and SKBR3 (P = 0.043) cells, but not in MDA-MB231 (P = 0.225) cells. A blocking assay using a CXCR6 antibody showed a significant decrease in the migration of activated NK cells in all cancer cell lines. Our data indicate that irradiation induces CXCL16 chemokine expression in cancer cells and enhances the migration of activated NK cells expressing CXCR6 to irradiated breast cancer cells. These results suggest that radiation would improve the anti-tumor effect of NK cells through enhanced migration of NK cells to tumor site for the treatment of patients with breast cancer. Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

[Study of migration and distribution of bone marrow cells transplanted animals with B16 melanoma ].

PubMed

Poveshchenko, A F; Solovieva, A O; Zubareva, K E; Strunkin, D N; Gricyk, O B; Poveshchenko, O V; Shurlygina, A V; Konenkov, V I

2017-01-01

Purpose. Reveal features migration and distribution of syngeneic bone marrow cells (BMC) and subpopulations (MSC) after transplantation into the recipient carrier B16 melanoma bodies. Methods. We used mouse male and female C57BL/6 mice. Induction of Tumor Growth: B16 melanoma cells implanted subcutaneously into right hind paw of female C57BL/6 mice at a dose of 2.5 x 105 cells / mouse. migration study in vivo distribution and BMC and MSC was performed using genetic markers - Y-chromosome specific sequence line male C57Bl/6 syngeneic intravenous transplantation in females using the polymerase chain reaction (PCR) in real time on Authorized Termal Cycler - Light Cycler 480 II / 96 (Roche). Introduction suspension of unseparated bone marrow cells, mesenchymal stem cells from donor to recipient male mice (syngeneic recipient female C57BL/6), followed by isolation of recipients of organs was performed at regular intervals, then of organ recipients isolated DNA. Results. It was shown that bone marrow cells positive for Y-chromosome in migrate lymphoid (lymph nodes, spleen, bone marrow) or in non-lymphoid organs (liver, heart, brain, skin) syngeneic recipients. In addition to the migration of cells from the bone marrow to other organs, there is a way back migration of cells from the circulation to the bone marrow. B16 melanoma stimulates the migration of transplanted MSCs and BMC in bone marrow. It is found that tumor growth enhanced migration of transplanted bone marrow cells, including populations of MSCs in the bone marrow. In the early stages of tumor formation MSC migration activity higher than the BMC. In the later stages of tumor formation undivided population of bone marrow cells migrate to the intense swelling compared with a population of MSCs. Conclusion. The possibility of using bone marrow MSCs for targeted therapy of tumor diseases, because migration of MSCs in tumor tissue can be used to effectively deliver anticancer drugs.

Envisioning migration: Mathematics in both experimental analysis and modeling of cell behavior

PubMed Central

Zhang, Elizabeth R.; Wu, Lani F.; Altschuler, Steven J.

2013-01-01

The complex nature of cell migration highlights the power and challenges of applying mathematics to biological studies. Mathematics may be used to create model equations that recapitulate migration, which can predict phenomena not easily uncovered by experiments or intuition alone. Alternatively, mathematics may be applied to interpreting complex data sets with better resolution—potentially empowering scientists to discern subtle patterns amid the noise and heterogeneity typical of migrating cells. Iteration between these two methods is necessary in order to reveal connections within the cell migration signaling network, as well as to understand the behavior that arises from those connections. Here, we review recent quantitative analysis and mathematical modeling approaches to the cell migration problem. PMID:23660413

Envisioning migration: mathematics in both experimental analysis and modeling of cell behavior.

PubMed

Zhang, Elizabeth R; Wu, Lani F; Altschuler, Steven J

2013-10-01

The complex nature of cell migration highlights the power and challenges of applying mathematics to biological studies. Mathematics may be used to create model equations that recapitulate migration, which can predict phenomena not easily uncovered by experiments or intuition alone. Alternatively, mathematics may be applied to interpreting complex data sets with better resolution--potentially empowering scientists to discern subtle patterns amid the noise and heterogeneity typical of migrating cells. Iteration between these two methods is necessary in order to reveal connections within the cell migration signaling network, as well as to understand the behavior that arises from those connections. Here, we review recent quantitative analysis and mathematical modeling approaches to the cell migration problem. Copyright © 2013 Elsevier Ltd. All rights reserved.

Neuronal cell migration in C. elegans: regulation of Hox gene expression and cell position.

PubMed

Harris, J; Honigberg, L; Robinson, N; Kenyon, C

1996-10-01

In C. elegans, the Hox gene mab-5, which specifies the fates of cells in the posterior body region, has been shown to direct the migrations of certain cells within its domain of function. mab-5 expression switches on in the neuroblast QL as it migrates into the posterior body region. mab-5 activity is then required for the descendants of QL to migrate to posterior rather than anterior positions. What information activates Hox gene expression during this cell migration? How are these cells subsequently guided to their final positions? We address these questions by describing four genes, egl-20, mig-14, mig-1 and lin-17, that are required to activate expression of mab-5 during migration of the QL neuroblast. We find that two of these genes, egl-20 and mig-14, also act in a mab-5-independent way to determine the final stopping points of the migrating Q descendants. The Q descendants do not migrate toward any obvious physical targets in wild-type or mutant animals. Therefore, these genes appear to be part of a system that positions the migrating Q descendants along the anteroposterior axis.

A spindle pole antigen gene MoSPA2 is important for polar cell growth of vegetative hyphae and conidia, but is dispensable for pathogenicity in Magnaporthe oryzae.

PubMed

Li, Chao; Yang, Jun; Zhou, Wei; Chen, Xiao-Lin; Huang, Jin-Guang; Cheng, Zhi-Hua; Zhao, Wen-Sheng; Zhang, Yan; Peng, You-Liang

2014-11-01

Spa2 is an important component of the multiprotein complex polarisome, which is involved in the establishment, maintenance, termination of polarized cell growth and is important for defining tip growth of filamentous fungi. In this study, we isolated an insertional mutant of the rice blast fungus Magnaporthe oryzae that formed smaller colony and conidia compared with the wild type. In the mutant, a spindle pole antigen gene MoSPA2 was disrupted by the integration of an exogenous plasmid. Targeted gene deletion and complementation assays demonstrated the gene disruption was responsible for the defects of the insertional mutant. Interestingly, the MoSpa2-GFP fusion protein was found to accumulate as a spot at hyphal tips, septa of hyphae and conidial tip cells where germ tubes are usually produced, but not in appressoria, infection hyphae or at the septa of conidia. Furthermore, the deletion mutants of MoSPA2 exhibited slower hyphal tip growth, more hyphal branches, and smaller size of conidial tip cells. However, MoSPA2 is not required for plant infection. These results indicate that MoSPA2 is required for vegetative hyphal growth and maintaining conidium morphology and that spotted accumulation of MoSpa2 is important for its functions during cell polar growth.

ICK is essential for cell type-specific ciliogenesis and the regulation of ciliary transport.

PubMed

Chaya, Taro; Omori, Yoshihiro; Kuwahara, Ryusuke; Furukawa, Takahisa

2014-06-02

Cilia and flagella are formed and maintained by intraflagellar transport (IFT) and play important roles in sensing and moving across species. At the distal tip of the cilia/flagella, IFT complexes turn around to switch from anterograde to retrograde transport; however, the underlying regulatory mechanism is unclear. Here, we identified ICK localization at the tip of cilia as a regulator of ciliary transport. In ICK-deficient mice, we found ciliary defects in neuronal progenitor cells with Hedgehog signal defects. ICK-deficient cells formed cilia with mislocalized Hedgehog signaling components. Loss of ICK caused the accumulation of IFT-A, IFT-B, and BBSome components at the ciliary tips. In contrast, overexpression of ICK induced the strong accumulation of IFT-B, but not IFT-A or BBSome components at ciliary tips. In addition, ICK directly phosphorylated Kif3a, while inhibition of this Kif3a phosphorylation affected ciliary formation. Our results suggest that ICK is a Kif3a kinase and essential for proper ciliogenesis in development by regulating ciliary transport at the tip of cilia. © 2014 The Authors.

ICK is essential for cell type-specific ciliogenesis and the regulation of ciliary transport

PubMed Central

Chaya, Taro; Omori, Yoshihiro; Kuwahara, Ryusuke; Furukawa, Takahisa

2014-01-01

Cilia and flagella are formed and maintained by intraflagellar transport (IFT) and play important roles in sensing and moving across species. At the distal tip of the cilia/flagella, IFT complexes turn around to switch from anterograde to retrograde transport; however, the underlying regulatory mechanism is unclear. Here, we identified ICK localization at the tip of cilia as a regulator of ciliary transport. In ICK-deficient mice, we found ciliary defects in neuronal progenitor cells with Hedgehog signal defects. ICK-deficient cells formed cilia with mislocalized Hedgehog signaling components. Loss of ICK caused the accumulation of IFT-A, IFT-B, and BBSome components at the ciliary tips. In contrast, overexpression of ICK induced the strong accumulation of IFT-B, but not IFT-A or BBSome components at ciliary tips. In addition, ICK directly phosphorylated Kif3a, while inhibition of this Kif3a phosphorylation affected ciliary formation. Our results suggest that ICK is a Kif3a kinase and essential for proper ciliogenesis in development by regulating ciliary transport at the tip of cilia. PMID:24797473

Sexually Dimorphic Patterns of Cell Proliferation in the Brain Are Linked to Seasonal Life-History Transitions in Red-Sided Garter Snakes.

PubMed

Lutterschmidt, Deborah I; Lucas, Ashley R; Karam, Ritta A; Nguyen, Vicky T; Rasmussen, Meghann R

2018-01-01

Seasonal rhythms in physiology and behavior are widespread across diverse taxonomic groups and may be mediated by seasonal changes in neurogenesis, including cell proliferation, migration, and differentiation. We examined if cell proliferation in the brain is associated with the seasonal life-history transition from spring breeding to migration and summer foraging in a free-ranging population of red-sided garter snakes ( Thamnophis sirtalis ) in Manitoba, Canada. We used the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) to label newly proliferated cells within the brain of adult snakes collected from the den during the mating season or from a road located along their migratory route. To assess rates of cell migration, we further categorized BrdU-labeled cells according to their location within the ventricular zone or parenchymal region of the nucleus sphericus (homolog of the amygdala), preoptic area/hypothalamus, septal nucleus, and cortex (homolog of the hippocampus). We found that cell proliferation and cell migration varied significantly with sex, the migratory status of snakes, and reproductive behavior in males. In most regions of interest, patterns of cell proliferation were sexually dimorphic, with males having significantly more BrdU-labeled cells than females prior to migration. However, during the initial stages of migration, females exhibited a significant increase in cell proliferation within the nucleus sphericus, hypothalamus, and septal nucleus, but not in any subregion of the cortex. In contrast, migrating males exhibited a significant increase in cell proliferation within the medial cortex but no other brain region. Because it is unlikely that the medial cortex plays a sexually dimorphic role in spatial memory during spring migration, we speculate that cell proliferation within the male medial cortex is associated with regulation of the hypothalamus-pituitary-adrenal axis. Finally, the only brain region where cell migration into the parenchymal region varied significantly with sex or migratory status was the hypothalamus. These results suggest that the migration of newly proliferated cells and/or the continued division of undifferentiated cells are activated earlier or to a greater extent in the hypothalamus. Our data suggest that sexually dimorphic changes in cell proliferation and cell migration in the adult brain may mediate sex differences in the timing of seasonal life-history transitions.

Sexually Dimorphic Patterns of Cell Proliferation in the Brain Are Linked to Seasonal Life-History Transitions in Red-Sided Garter Snakes

PubMed Central

Lutterschmidt, Deborah I.; Lucas, Ashley R.; Karam, Ritta A.; Nguyen, Vicky T.; Rasmussen, Meghann R.

2018-01-01

Seasonal rhythms in physiology and behavior are widespread across diverse taxonomic groups and may be mediated by seasonal changes in neurogenesis, including cell proliferation, migration, and differentiation. We examined if cell proliferation in the brain is associated with the seasonal life-history transition from spring breeding to migration and summer foraging in a free-ranging population of red-sided garter snakes (Thamnophis sirtalis) in Manitoba, Canada. We used the thymidine analog 5-bromo-2′-deoxyuridine (BrdU) to label newly proliferated cells within the brain of adult snakes collected from the den during the mating season or from a road located along their migratory route. To assess rates of cell migration, we further categorized BrdU-labeled cells according to their location within the ventricular zone or parenchymal region of the nucleus sphericus (homolog of the amygdala), preoptic area/hypothalamus, septal nucleus, and cortex (homolog of the hippocampus). We found that cell proliferation and cell migration varied significantly with sex, the migratory status of snakes, and reproductive behavior in males. In most regions of interest, patterns of cell proliferation were sexually dimorphic, with males having significantly more BrdU-labeled cells than females prior to migration. However, during the initial stages of migration, females exhibited a significant increase in cell proliferation within the nucleus sphericus, hypothalamus, and septal nucleus, but not in any subregion of the cortex. In contrast, migrating males exhibited a significant increase in cell proliferation within the medial cortex but no other brain region. Because it is unlikely that the medial cortex plays a sexually dimorphic role in spatial memory during spring migration, we speculate that cell proliferation within the male medial cortex is associated with regulation of the hypothalamus-pituitary-adrenal axis. Finally, the only brain region where cell migration into the parenchymal region varied significantly with sex or migratory status was the hypothalamus. These results suggest that the migration of newly proliferated cells and/or the continued division of undifferentiated cells are activated earlier or to a greater extent in the hypothalamus. Our data suggest that sexually dimorphic changes in cell proliferation and cell migration in the adult brain may mediate sex differences in the timing of seasonal life-history transitions.

S. pombe CLASP needs dynein, not EB1 or CLIP170, to induce microtubule instability and slows polymerization rates at cell tips in a dynein-dependent manner

PubMed Central

Grallert, Agnes; Beuter, Christoph; Craven, Rachel A.; Bagley, Steve; Wilks, Deepti; Fleig, Ursula; Hagan, Iain M.

2006-01-01

The Schizosaccharomyces pombe CLIP170-associated protein (CLASP) Peg1 was identified in a screen for mutants with spindle formation defects and a screen for molecules that antagonized EB1 function. The conditional peg1.1 mutant enabled us to identify key features of Peg1 function. First, Peg1 was required to form a spindle and astral microtubules, yet destabilized interphase microtubules. Second, Peg1 was required to slow the polymerization rate of interphase microtubules that establish end-on contact with the cortex at cell tips. Third, Peg1 antagonized the action of S. pombe CLIP170 (Tip1) and EB1 (Mal3). Fourth, although Peg1 resembled higher eukaryotic CLASPs by physically associating with both Mal3 and Tip1, neither Tip1 nor Mal3 was required for Peg1 to destabilize interphase microtubules or for it to associate with microtubules. Conversely, neither Mal3 nor Tip1 required Peg1 to associate with microtubules or cell tips. Consistently, while mal3.Δ and tip1.Δ disrupted linear growth, corrupting peg1 + did not. Fifth, peg1.1 phenotypes resembled those arising from deletion of the single heavy or both light chains of fission yeast dynein. Furthermore, all interphase phenotypes arising from peg1 + manipulation relied on dynein function. Thus, the impact of S. pombe CLASP on interphase microtubule behavior is more closely aligned to dynein than EB1 or CLIP170. PMID:16951255

Substrate Topography Induces a Crossover from 2D to 3D Behavior in Fibroblast Migration

PubMed Central

Ghibaudo, Marion; Trichet, Léa; Le Digabel, Jimmy; Richert, Alain; Hersen, Pascal; Ladoux, Benoît

2009-01-01

Abstract In a three-dimensional environment, cells migrate through complex topographical features. Using microstructured substrates, we investigate the role of substrate topography in cell adhesion and migration. To do so, fibroblasts are plated on chemically identical substrates composed of microfabricated pillars. When the dimensions of the pillars (i.e., the diameter, length, and spacing) are varied, migrating cells encounter alternating flat and rough surfaces that depend on the spacing between the pillars. Consequently, we show that substrate topography affects cell shape and migration by modifying cell-to-substrate interactions. Cells on micropillar substrates exhibit more elongated and branched shapes with fewer actin stress fibers compared with cells on flat surfaces. By analyzing the migration paths in various environments, we observe different mechanisms of cell migration, including a persistent type of migration, that depend on the organization of the topographical features. These responses can be attributed to a spatial reorganization of the actin cytoskeleton due to physical constraints and a preferential formation of focal adhesions on the micropillars, with an increased lifetime compared to that observed on flat surfaces. By changing myosin II activity, we show that actomyosin contractility is essential in the cellular response to micron-scale topographic signals. Finally, the analysis of cell movements at the frontier between flat and micropillar substrates shows that cell transmigration through the micropillar substrates depends on the spacing between the pillars. PMID:19580774

Arginyltransferase ATE1 is targeted to the neuronal growth cones and regulates neurite outgrowth during brain development.

PubMed

Wang, Junling; Pavlyk, Iuliia; Vedula, Pavan; Sterling, Stephanie; Leu, N Adrian; Dong, Dawei W; Kashina, Anna

2017-10-01

Arginylation is an emerging protein modification mediated by arginyltransferase ATE1, shown to regulate embryogenesis and actin cytoskeleton, however its functions in different physiological systems are not well understood. Here we analyzed the role of ATE1 in brain development and neuronal growth by producing a conditional mouse knockout with Ate1 deletion in the nervous system driven by Nestin promoter (Nes-Ate1 mice). These mice were weaker than wild type, resulting in low postnatal survival rates, and had abnormalities in the brain that suggested defects in neuronal migration. Cultured Ate1 knockout neurons showed a reduction in the neurite outgrowth and the levels of doublecortin and F-actin in the growth cones. In wild type, ATE1 prominently localized to the growth cones, in addition to the cell bodies. Examination of the Ate1 mRNA sequence reveals the existence of putative zipcode-binding sequences involved in mRNA targeting to the cell periphery and local translation at the growth cones. Fluorescence in situ hybridization showed that Ate1 mRNA localized to the tips of the growth cones, likely due to zipcode-mediated targeting, and this localization coincided with spots of localization of arginylated β-actin, which disappeared in the presence of protein synthesis inhibitors. We propose that zipcode-mediated co-targeting of Ate1 and β-actin mRNA leads to localized co-translational arginylation of β-actin that drives the growth cone migration and neurite outgrowth. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Role of high-mobility group box 1 in methamphetamine-induced activation and migration of astrocytes.

PubMed

Zhang, Yuan; Zhu, Tiebing; Zhang, Xiaotian; Chao, Jie; Hu, Gang; Yao, Honghong

2015-09-04

Mounting evidence has indicated that high-mobility group box 1 (HMGB1) is involved in cell activation and migration. Our previous study demonstrated that methamphetamine mediates activation of astrocytes via sigma-1 receptor (σ-1R). However, the elements downstream of σ-1R in this process remain poorly understood. Thus, we examined the molecular mechanisms involved in astrocyte activation and migration induced by methamphetamine. The expression of HMGB1, σ-1R, and glial fibrillary acidic protein (GFAP) was examined by western blot and immunofluorescent staining. The phosphorylation of cell signaling pathways was detected by western blot, and cell migration was examined using a wound-healing assay in rat C6 astroglia-like cells transfected with lentivirus containing red fluorescent protein (LV-RFP) as well as in primary human astrocytes. The role of HMGB1 in astrocyte activation and migration was validated using a siRNA approach. Exposure of C6 cells to methamphetamine increased the expression of HMGB1 via the activation of σ-1R, Src, ERK mitogen-activated protein kinase, and downstream NF-κB p65 pathways. Moreover, methamphetamine treatment resulted in increased cell activation and migration in C6 cells and primary human astrocytes. Knockdown of HMGB1 in astrocytes transfected with HMGB1 siRNA attenuated the increased cell activation and migration induced by methamphetamine, thereby implicating the role of HMGB1 in the activation and migration of C6 cells and primary human astrocytes. This study demonstrated that methamphetamine-mediated activation and migration of astrocytes involved HMGB1 up-regulation through an autocrine mechanism. Targeting HMGB1 could provide insights into the development of a potential therapeutic approach for alleviation of cell activation and migration of astrocytes induced by methamphetamine.

Rac1 and Cdc42 Differentially Modulate Cigarette Smoke–Induced Airway Cell Migration through p120-Catenin–Dependent and –Independent Pathways

PubMed Central

Zhang, Lili; Gallup, Marianne; Zlock, Lorna; Finkbeiner, Walter E.; McNamara, Nancy A.

2014-01-01

The adherens junction protein p120-catenin (p120ctn) shuttles between E-cadherin–bound and cytoplasmic pools to regulate E-cadherin/catenin complex stability and cell migration, respectively. When released from the adherens junction, p120ctn promotes cell migration through modulation of the Rho GTPases Rac1, Cdc42, and RhoA. Accordingly, the down-regulation and cytoplasmic mislocalization of p120ctn has been reported in all subtypes of lung cancers and is associated with grave prognosis. Previously, we reported that cigarette smoke induced cytoplasmic translocation of p120ctn and cell migration, but the underlying mechanism was unclear. Using primary human bronchial epithelial cells exposed to smoke-concentrated medium (Smk), we observed the translocation of Rac1 and Cdc42, but not RhoA, to the leading edge of polarized and migrating human bronchial epithelial cells. Rac1 and Cdc42 were robustly activated by smoke, whereas RhoA was inhibited. Accordingly, siRNA knockdown of Rac1 or Cdc42 completely abolished Smk-induced cell migration, whereas knockdown of RhoA had no effect. p120ctn/Rac1 double knockdown completely abolished Smk-induced cell migration, whereas p120ctn/Cdc42 double knockdown did not. These data suggested that Rac1 and Cdc42 coactivation was essential to smoke-promoted cell migration in the presence of p120ctn, whereas migration proceeded via Rac1 alone in the absence of p120ctn. Thus, Rac1 may provide an omnipotent therapeutic target in reversing cell migration during the early (intact p120ctn) and late (loss of p120ctn) stages of lung carcinogenesis. PMID:23562274

Multiscale regime shifts and planetary boundaries.

PubMed

Hughes, Terry P; Carpenter, Stephen; Rockström, Johan; Scheffer, Marten; Walker, Brian

2013-07-01

Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a tipping point. Whether human activities will trigger such a global event in the near future is uncertain, due to critical knowledge gaps. In particular, we lack understanding of how regime shifts propagate across scales, and whether local or regional tipping points can lead to global transitions. The ongoing disruption of ecosystems and climate, combined with unprecedented breakdown of isolation by human migration and trade, highlights the need to operate within safe planetary boundaries. Copyright © 2013 Elsevier Ltd. All rights reserved.

Collective Behavior of Brain Tumor Cells: the Role of Hypoxia

NASA Astrophysics Data System (ADS)

Khain, Evgeniy; Katakowski, Mark; Hopkins, Scott; Szalad, Alexandra; Zheng, Xuguang; Jiang, Feng; Chopp, Michael

2013-03-01

We consider emergent collective behavior of a multicellular biological system. Specifically we investigate the role of hypoxia (lack of oxygen) in migration of brain tumor cells. We performed two series of cell migration experiments. The first set of experiments was performed in a typical wound healing geometry: cells were placed on a substrate, and a scratch was done. In the second set of experiments, cell migration away from a tumor spheroid was investigated. Experiments show a controversy: cells under normal and hypoxic conditions have migrated the same distance in the ``spheroid'' experiment, while in the ``scratch'' experiment cells under normal conditions migrated much faster than under hypoxic conditions. To explain this paradox, we formulate a discrete stochastic model for cell dynamics. The theoretical model explains our experimental observations and suggests that hypoxia decreases both the motility of cells and the strength of cell-cell adhesion. The theoretical predictions were further verified in independent experiments.

Time-lapse cinematography of the capillary tube cell migration inhibition test.

PubMed

Bray, M A

1980-01-01

The kinetics of human and guinea pig cell migration inhibition have been studied using time-lapse cinematography of cells migrating from capillary tubes. Guinea pig and human cells exhibit markedly different kinetics in the absence of inhibitors. Specific antigen causes a dose-related inhibition of migration for up to 60 h using guinea pig cells and a peak of inhibition after 18 h using the human leucocyte system. The timing of measurement of maximum activity more critical for the latter test. The kinetics of lymphokine generation have been examined and the migration inhibitory activity of the plant mitogen (PHA), a Kurloff cell product and a continuous cell line supernatant have been compared with the inhibitory profiles of lymphokine preparations and specific antigen.

Decorin inhibits cell migration through a process requiring its glycosaminoglycan side chain.

PubMed

Merle, B; Durussel, L; Delmas, P D; Clézardin, P

1999-12-01

Several studies overwhelmingly support the notion that decorin (DCN) is involved in matrix assembly, and in the control of cell adhesion and proliferation. However, nothing is known about the role of DCN during cell migration. Cell migration is a tightly regulated process which requires both adhesion (at the leading edge of the cell) and de-adhesion (at the trailing edge of the cell) from the substratum. We have determined in this study the effect of DCN on MG-63 osteosarcoma cell migration and have analyzed whether its effect is mediated by the protein core and/or the glycosaminoglycan side chain. DCN impeded the migration-promoting effect of matrix molecules (fibronectin, collagen type I) known to interact with the proteoglycan. Conversely, DCN did not counteract the migration-promoting effect of fibrinogen lacking proteoglycan affinity. DCN bearing dermatan-sulfate chains (i.e., skin and cartilage DCN) was about 20-fold more effective in inhibiting cell migration than DCN bearing chondroitin-sulfate chains (i.e., bone DCN). In addition, chondroitinase AC-treatment of cartilage DCN (which specifically removes chondroitin-sulfate chains) did not attenuate the inhibitory effect of this proteoglycan, while cartilage DCN deprived of both chondroitin- and dermatan-sulfate chains failed to alter cell migration promoted by either fibronectin or its heparin- and cell-binding domains. These data assert that the dermatan-sulfate chains of DCN are responsible for a negative influence on cell migration. However, isolated glycosaminoglycans failed to alter cell migration promoted by fibronectin, indicating that strongly negatively charged glycosaminoglycans alone cannot account for the impaired cell motility seen with DCN. Overall, these results show that the inhibitory action of DCN is dependent of substratum binding, is differentially mediated by its glycosaminoglycan side chains (chondroitin-sulfate vs. dermatan-sulfate chains), and is independent of a steric hindrance effect exerted by its glycosaminoglycan side chains. Copyright 1999 Wiley-Liss, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seomun, Young; Joo, Choun-Ki

Lumican is a major proteoglycans of the human cornea. Lumican knock-out mice have been shown to lose corneal transparency and to display delayed wound healing. The purpose of this study was to define the role of lumican in corneal epithelial cell migration. Over-expression of lumican in human corneal epithelial (HCE-T) cells increased both cell migration and proliferation, and increased levels of integrins {alpha}2 and {beta}1. ERK 1/2 was also activated in lumican over-expressed cells. When we treated HCE-T cells with the ERK-specific inhibitor U0126, cell migration and the expression of integrin {beta}1 were completely blocked. These data provide evidence thatmore » lumican stimulates cell migration in the corneal epithelium by activating ERK 1/2, and point to a novel signaling pathway implicated in corneal epithelial cell migration.« less

Trajectory Analysis Unveils Reelin's Role in the Directed Migration of Granule Cells in the Dentate Gyrus.

PubMed

Wang, Shaobo; Brunne, Bianka; Zhao, Shanting; Chai, Xuejun; Li, Jiawei; Lau, Jeremie; Failla, Antonio Virgilio; Zobiak, Bernd; Sibbe, Mirjam; Westbrook, Gary L; Lutz, David; Frotscher, Michael

2018-01-03

Reelin controls neuronal migration and layer formation. Previous studies in reeler mice deficient in Reelin focused on the result of the developmental process in fixed tissue sections. It has remained unclear whether Reelin affects the migratory process, migration directionality, or migrating neurons guided by the radial glial scaffold. Moreover, Reelin has been regarded as an attractive signal because newly generated neurons migrate toward the Reelin-containing marginal zone. Conversely, Reelin might be a stop signal because migrating neurons in reeler , but not in wild-type mice, invade the marginal zone. Here, we monitored the migration of newly generated proopiomelanocortin-EGFP -expressing dentate granule cells in slice cultures from reeler , reeler -like mutants and wild-type mice of either sex using real-time microscopy. We discovered that not the actual migratory process and migratory speed, but migration directionality of the granule cells is controlled by Reelin. While wild-type granule cells migrated toward the marginal zone of the dentate gyrus, neurons in cultures from reeler and reeler -like mutants migrated randomly in all directions as revealed by vector analyses of migratory trajectories. Moreover, live imaging of granule cells in reeler slices cocultured to wild-type dentate gyrus showed that the reeler neurons changed their directions and migrated toward the Reelin-containing marginal zone of the wild-type culture, thus forming a compact granule cell layer. In contrast, directed migration was not observed when Reelin was ubiquitously present in the medium of reeler slices. These results indicate that topographically administered Reelin controls the formation of a granule cell layer. SIGNIFICANCE STATEMENT Neuronal migration and the various factors controlling its onset, speed, directionality, and arrest are poorly understood. Slice cultures offer a unique model to study the migration of individual neurons in an almost natural environment. In the present study, we took advantage of the expression of proopiomelanocortin-EGFP by newly generated, migrating granule cells to analyze their migratory trajectories in hippocampal slice cultures from wild-type mice and mutants deficient in Reelin signaling. We show that the compartmentalized presence of Reelin is essential for the directionality, but not the actual migratory process or speed, of migrating granule cells leading to their characteristic lamination in the dentate gyrus. Copyright © 2018 the authors 0270-6474/18/380137-12$15.00/0.

Proteolytic Enzymes Clustered in Specialized Plasma-Membrane Domains Drive Endothelial Cells’ Migration

PubMed Central

Salamone, Monica; Carfì Pavia, Francesco

2016-01-01

In vitro cultured endothelial cells forming a continuous monolayer establish stable cell-cell contacts and acquire a “resting” phenotype; on the other hand, when growing in sparse conditions these cells acquire a migratory phenotype and invade the empty area of the culture. Culturing cells in different conditions, we compared expression and clustering of proteolytic enzymes in cells having migratory versus stationary behavior. In order to observe resting and migrating cells in the same microscopic field, a continuous cell monolayer was wounded. Increased expression of proteolytic enzymes was evident in cell membranes of migrating cells especially at sprouting sites and in shed membrane vesicles. Gelatin zymography and western blotting analyses confirmed that in migrating cells, expression of membrane-bound and of vesicle-associated proteolytic enzymes are increased. The enzymes concerned include MMP-2, MMP-9, MT1-MMP, seprase, DPP4 (DiPeptidyl Peptidase 4) and uPA. Shed membrane vesicles were shown to exert degradative activity on ECM components and produce substrates facilitating cell migration. Vesicles shed by migrating cells degraded ECM components at an increased rate; as a result their effect on cell migration was amplified. Inhibiting either Matrix Metallo Proteases (MMPs) or Serine Integral Membrane Peptidases (SIMPs) caused a decrease in the stimulatory effect of vesicles, inhibiting the spontaneous migratory activity of cells; a similar result was also obtained when a monoclonal antibody acting on DPP4 was tested. We conclude that proteolytic enzymes have a synergistic stimulatory effect on cell migration and that their clustering probably facilitates the proteolytic activation cascades needed to produce maximal degradative activity on cell substrates during the angiogenic process. PMID:27152413

Exposure to 60% oxygen promotes migration and upregulates angiogenesis factor secretion in breast cancer cells.

PubMed

Crowley, Peter D; Stuttgen, Vivian; O'Carroll, Emma; Ash, Simon A; Buggy, Donal J; Gallagher, Helen C

2017-01-01

Peri-operative factors, including anaesthetic drugs and techniques, may affect cancer cell biology and clinical recurrence. In breast cancer cells, we demonstrated that sevoflurane promotes migration and angiogenesis in high fractional oxygen but not in air. Follow-up analysis of the peri-operative oxygen fraction trial found an association between high inspired oxygen during cancer surgery and reduced tumor-free survival. Here we evaluated effects of acute, high oxygen exposure on breast cancer cell viability, migration and secretion of angiogenesis factors in vitro . MDA-MB-231 and MCF-7 breast cancer cells were exposed to 21%, 30%, 60%, or 80% v/v O 2 for 3 hours. Cell viability at 24 hours was determined by MTT and migration at 24 hours with the Oris™ Cell Migration Assay. Secretion of angiogenesis factors at 24 hours was measured via membrane-based immunoarray. Exposure to 30%, 60% or 80% oxygen did not affect cell viability. Migration of MDA-MB-231 and MCF-7 cells was increased by 60% oxygen ( P = 0.012 and P = 0.007, respectively) while 30% oxygen increased migration in MCF-7 cells ( P = 0.011). These effects were reversed by dimethyloxaloylglycine. In MDA-MB-231 cells high fractional oxygen increased secretion of angiogenesis factors monocyte chemotactic protein 1, regulated on activation normal T-cell expressed and vascular endothelial growth factor. In MCF-7 cells, interleukin-8, angiogenin and vascular endothelial growth factor secretion was significantly increased by high fractional oxygen. High oxygen exposure stimulates migration and secretion of angiogenesis factors in breast cancer cells in vitro .

Interstitial flow influences direction of tumor cell migration through competing mechanisms

PubMed Central

Polacheck, William J.; Charest, Joseph L.; Kamm, Roger D.

2011-01-01

Interstitial flow is the convective transport of fluid through tissue extracellular matrix. This creeping fluid flow has been shown to affect the morphology and migration of cells such as fibroblasts, cancer cells, endothelial cells, and mesenchymal stem cells. A microfluidic cell culture system was designed to apply stable pressure gradients and fluid flow and allow direct visualization of transient responses of cells seeded in a 3D collagen type I scaffold. We used this system to examine the effects of interstitial flow on cancer cell morphology and migration and to extend previous studies showing that interstitial flow increases the metastatic potential of MDA-MB-435S melanoma cells [Shields J, et al. (2007) Cancer Cell 11:526–538]. Using a breast carcinoma line (MDA-MB-231) we also observed cell migration along streamlines in the presence of flow; however, we further demonstrated that the strength of the flow as well as the cell density determined directional bias of migration along the streamline. In particular, we found that cells either at high seeding density or with the CCR-7 receptor inhibited migration against, rather than with the flow. We provide further evidence that CCR7-dependent autologous chemotaxis is the mechanism that leads to migration with the flow, but also demonstrate a competing CCR7-independent mechanism that causes migration against the flow. Data from experiments investigating the effects of cell concentration, interstitial flow rate, receptor activity, and focal adhesion kinase phosphorylation support our hypothesis that the competing stimulus is integrin mediated. This mechanism may play an important role in development of metastatic disease. PMID:21690404

Force dependent internalization of magnetic nanoparticles results in highly loaded endothelial cells for use as potential therapy delivery vectors.

PubMed

MacDonald, Cristin; Barbee, Kenneth; Polyak, Boris

2012-05-01

To investigate the kinetics, mechanism and extent of MNP loading into endothelial cells and the effect of this loading on cell function. MNP uptake was examined under field on/off conditions, utilizing varying magnetite concentration MNPs. MNP-loaded cell viability and functional integrity was assessed using metabolic respiration, cell proliferation and migration assays. MNP uptake in endothelial cells significantly increased under the influence of a magnetic field versus non-magnetic conditions. Larger magnetite density of the MNPs led to a higher MNP internalization by cells under application of a magnetic field without compromising cellular respiration activity. Two-dimensional migration assays at no field showed that higher magnetite loading resulted in greater cell migration rates. In a three-dimensional migration assay under magnetic field, the migration rate of MNP-loaded cells was more than twice that of unloaded cells and was comparable to migration stimulated by a serum gradient. Our results suggest that endothelial cell uptake of MNPs is a force dependent process. The in vitro assays determined that cell health is not adversely affected by high MNP loadings, allowing these highly magnetically responsive cells to be potentially beneficial therapy (gene, drug or cell) delivery systems.

Vascular pericyte density and angiogenesis associated with adenocarcinoma of the prostate.

PubMed

Killingsworth, Murray C; Wu, Xiaojuan

2011-01-01

Angiogenesis facilitates metabolism, proliferation and metastasis of adenocarcinoma cells in the prostate, as without the development of new vasculature tumor growth cannot be sustained. However, angiogenesis is variable with the well-known phenomenon of vascular 'hotspots' seen associated with viable tumor cell mass. With the recent recognition of pericytes as molecular regulators of angiogenesis, we have examined the interaction of these cells in actively growing new vessels. Pericyte interactions with developing new vessels were examined using transmission electron microscopy. Pericyte distribution was mapped from α-SMA+ immunostained histological sections and quantified using image analysis. Data was obtained from peripheral and more central regions of 27 cases with Gleason scores of 4-9. Pericyte numbers were increased around developing new vessel sprouts at sites of luminal maturation. Numbers were reduced around the actively growing tips of migrating endothelial cells and functional new vessels. Tumor regions internal to a 500-μm peripheral band showed higher microvessel pericyte density than the peripheral region. Pericytes were found to be key cellular components of developing new vessels in adenocarcinoma of the prostate. Their numbers increased at sites of luminal maturation with these cells displaying an activated phenotype different to quiescent pericytes. Increased pericyte density was found internal to the peripheral region, suggesting more mature vessels lie more centrally. Copyright © 2011 S. Karger AG, Basel.

Selective Modulation of Integrin-mediated Cell Migration by Distinct ADAM Family MembersV⃞

PubMed Central

Huang, Jing; Bridges, Lance C.; White, Judith M.

2005-01-01

A disintegrin and a metalloprotease (ADAM) family members have been implicated in many biological processes. Although it is recognized that recombinant ADAM disintegrin domains can interact with integrins, little is known about ADAM-integrin interactions in cellular context. Here, we tested whether ADAMs can selectively regulate integrin-mediated cell migration. ADAMs were expressed in Chinese hamster ovary cells that express defined integrins (α4β1, α5β1, or both), and cell migration on full-length fibronectin or on its α4β1 or α5β1 binding fragments was studied. We found that ADAMs inhibit integrin-mediated cell migration in patterns dictated by the integrin binding profiles of their isolated disintegrin domains. ADAM12 inhibited cell migration mediated by the α4β1 but not the α5β1 integrin. ADAM17 had the reciprocal effect; it inhibited α5β1- but not α4β1-mediated cell migration. ADAM19 and ADAM33 inhibited migration mediated by both α4β1 and α5β1 integrins. A point mutation in the ADAM12 disintegrin loop partially reduced the inhibitory effect of ADAM12 on cell migration on the α4β1 binding fragment of fibronectin, whereas mutations that block metalloprotease activity had no effect. Our results indicate that distinct ADAMs can modulate cell migration mediated by specific integrins in a pattern dictated, at least in part, by their disintegrin domains. PMID:16079176

Global Coastal Exposure due to Sea-level Rise beyond Tipping Points with Multiple Warming Pathways

NASA Astrophysics Data System (ADS)

Tawatari, R.; Iseri, Y.; Kiguchi, M.; Kanae, S.

2016-12-01

Sea-level is observed and estimated to continue rising. In the future, the rise could be abrupt and irreversible in century to millennial timescale even if we conduct strong reduction of greenhouse gas emission. Greenland ice sheet and West Antarctic ice sheet are considered as attributable climate systems which would significantly enhance presently-projected sea-level rise by several meters if global mean temperature passes certain "Tipping points" which would exist around +1-5 degree Celsius above present temperature (1980-1999 average). Therefore, vulnerable coastal low-lying area, especially small islands, deltas or poor developing countries, would suffer from semi-permanent inundation and forced to counteract due to the enhanced sea-level rise. This study estimate range of sea-level rise until the year 2300 and 3000 considering excess of tipping points with using multiple levels of temperature scenarios which consist of excess tipping points and non-excess tipping points pathways. We extract state-of-the-art knowledge of tipping elements from paper reviewing to express reasonable relationship between temperature and abruptly-changing sea-level transition across the ages. This study also calculate coastal exposure globally as affected population, area and asset below the estimated sea-level for each countries with overlaying 30 arc-second gridded topography, population distribution and the sea-level. The result indicates which country would be critically affected if we follow overshooting pathways. Furthermore, this study visualize uncertain coastal exposure due to sea-level rise in the future from the multiple warming pathways. This estimation of possible future beyond tipping point would be useful information for decision-makers to establish new planning of defense, migration or mitigation for the future societies.

Rear-polarized Wnt5a-receptor-actin-myosin-polarity (WRAMP) structures promote the speed and persistence of directional cell migration

PubMed Central

Connacher, Mary Katherine; Tay, Jian Wei; Ahn, Natalie G.

2017-01-01

In contrast to events at the cell leading edge, rear-polarized mechanisms that control directional cell migration are poorly defined. Previous work described a new intracellular complex, the Wnt5a-receptor-actomyosin polarity (WRAMP) structure, which coordinates the polarized localization of MCAM, actin, and myosin IIB in a Wnt5a-induced manner. However, the polarity and function for the WRAMP structure during cell movement were not determined. Here we characterize WRAMP structures during extended cell migration using live-cell imaging. The results demonstrate that cells undergoing prolonged migration show WRAMP structures stably polarized at the rear, where they are strongly associated with enhanced speed and persistence of directional movement. Strikingly, WRAMP structures form transiently, with cells displaying directional persistence during periods when they are present and cells changing directions randomly when they are absent. Cells appear to pause locomotion when WRAMP structures disassemble and then migrate in new directions after reassembly at a different location, which forms the new rear. We conclude that WRAMP structures represent a rear-directed cellular mechanism to control directional migration and that their ability to form dynamically within cells may control changes in direction during extended migration. PMID:28592632

A versatile microfluidic platform for the study of cellular interactions between endothelial cells and neutrophils.

PubMed

Wu, Xiaojie; Newbold, Molly A; Gao, Zhe; Haynes, Christy L

2017-05-01

Endothelial migration is a critical physiological process during vascular angiogenesis, growth and development, as well as in various disease conditions, such as cancer and cardiovascular diseases. Neutrophil migration, known as the important characteristic of immune responses, is also recognized as a contributor to the diseases involving endothelial migration. Herein, the mutually dependent relationship between neutrophil recruitment and endothelial migration was studied on a microfluidic platform for the first time. An in vivo-like microenvironment is created inside microfluidic devices by embedding a gel scaffold into the micro-chambers. This approach, with controllable stable chemical gradients and the ability to quantitate interaction characteristics, overcomes the limitations of the current in vivo and in vitro assays for cell migration studies. The number of neutrophils migrating through the endothelial cell layer is heavily influenced by the concentration of vascular endothelial growth factor (VEGF) that induces endothelial cell migration in the gel scaffold, and is not as correlated to the concentration of chemokine solution used for initiating neutrophil migration. More importantly, neutrophil migration diminishes the effects of the drug that inhibits endothelial migration and this process is regulated by the concentration of chemokine molecules instead of VEGF concentration. The results presented herein demonstrate the complicated cellular interactions between endothelial cells and neutrophils: endothelial migration delicately regulates neutrophil migration while the presence of neutrophils stabilizes the structures of endothelial migration. This study provides deeper understanding of the dynamic cellular interactions between neutrophils and endothelial cells as well as the pathogenesis of relevant diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Recovery patterns, histological observations and genetic integrity in Malus shoot tips cryopreserved using droplet-vitrification and encapsulation-dehydration procedures.

PubMed

Li, Bai-Quan; Feng, Chao-Hong; Wang, Min-Rui; Hu, Ling-Yun; Volk, Gayle; Wang, Qiao-Chun

2015-11-20

A droplet-vitrification procedure is described for cryopreservation of Malus shoot tips. Survival patterns, recovery types, histological observations, and genetic integrity were compared for Malus shoot tips cryopreserved using this droplet-vitrification procedure and an encapsulation-dehydration procedure that was previously reported by us. In both procedures, three types of shoot tip recovery were observed following cryopreservation: callus formation without shoot regrowth, leaf formation without shoot regrowth, and shoot regrowth. Three categories of histological observations were also identified in cross-sections of shoot tips recovered after cryopreservation using the two cryogenic procedures. In category 1, almost all of the cells (94-95%) in the apical dome (AD) were damaged or killed and only some cells (30-32%) in the leaf primordia (LPs) survived. In category 2, only a few cells (18-20%) in the AD and some cells (30-31%) in the LPs survived. In category 3, majority of the cells (60-62%) in the AD and some cells (30-33%) in the LPs survived. These data suggest that shoot regrowth is correlated to the presence of a majority of surviving cells in the AD after liquid nitrogen exposure. No polymorphic bands were detected by inter-simple sequence repeats or by random amplified polymorphic DNA assessments, and ploidy levels analyzed by flow cytometry were unchanged when plants recovered after cryoexposure were compared to controls. The droplet-vitrification procedure appears to be robust since seven genotypes representing four Malus species and one hybrid recovered shoots following cryopreservation. Mean shoot regrowth levels of these seven genotypes were 48% in the droplet-vitrification method, which were lower than those (61%) in the encapsulation-dehydration procedure reported in our previous study, suggesting the latter may be preferred for routine cryobanking applications for Malus shoot tips. Copyright © 2015 Elsevier B.V. All rights reserved.

Insulin promotes cell migration by regulating PSA-NCAM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monzo, Hector J.; Coppieters, Natacha; Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, 92019, Auckland

Cellular interactions with the extracellular environment are modulated by cell surface polysialic acid (PSA) carried by the neural cell adhesion molecule (NCAM). PSA-NCAM is involved in cellular processes such as differentiation, plasticity, and migration, and is elevated in Alzheimer's disease as well as in metastatic tumour cells. Our previous work demonstrated that insulin enhances the abundance of cell surface PSA by inhibiting PSA-NCAM endocytosis. In the present study we have identified a mechanism for insulin-dependent inhibition of PSA-NCAM turnover affecting cell migration. Insulin enhanced the phosphorylation of the focal adhesion kinase leading to dissociation of αv-integrin/PSA-NCAM clusters, and promoted cellmore » migration. Our results show that αv-integrin plays a key role in the PSA-NCAM turnover process. αv-integrin knockdown stopped PSA-NCAM from being endocytosed, and αv-integrin/PSA-NCAM clusters co-labelled intracellularly with Rab5, altogether indicating a role for αv-integrin as a carrier for PSA-NCAM during internalisation. Furthermore, inhibition of p-FAK caused dissociation of αv-integrin/PSA-NCAM clusters and counteracted the insulin-induced accumulation of PSA at the cell surface and cell migration was impaired. Our data reveal a functional association between the insulin/p-FAK-dependent regulation of PSA-NCAM turnover and cell migration through the extracellular matrix. Most importantly, they identify a novel mechanism for insulin-stimulated cell migration. - Highlights: • Insulin modulates PSA-NCAM turnover through upregulation of p-FAK. • P-FAK modulates αv-integrin/PSA-NCAM clustering. • αv-integrin acts as a carrier for PSA-NCAM endocytosis. • Cell migration is promoted by cell surface PSA. • Insulin promotes PSA-dependent migration in vitro.« less

Cut-cell method based large-eddy simulation of tip-leakage flow

NASA Astrophysics Data System (ADS)

Pogorelov, Alexej; Meinke, Matthias; Schröder, Wolfgang

2015-07-01

The turbulent low Mach number flow through an axial fan at a Reynolds number of 9.36 × 105 based on the outer casing diameter is investigated by large-eddy simulation. A finite-volume flow solver in an unstructured hierarchical Cartesian setup for the compressible Navier-Stokes equations is used. To account for sharp edges, a fully conservative cut-cell approach is applied. A newly developed rotational periodic boundary condition for Cartesian meshes is introduced such that the simulations are performed just for a 72° segment, i.e., the flow field over one out of five axial blades is resolved. The focus of this numerical analysis is on the development of the vortical flow structures in the tip-gap region. A detailed grid convergence study is performed on four computational grids with 50 × 106, 250 × 106, 1 × 109, and 1.6 × 109 cells. Results of the instantaneous and the mean fan flow field are thoroughly analyzed based on the solution with 1 × 109 cells. High levels of turbulent kinetic energy and pressure fluctuations are generated by a tip-gap vortex upstream of the blade, the separating vortices inside the tip gap, and a counter-rotating vortex on the outer casing wall. An intermittent interaction of the turbulent wake, generated by the tip-gap vortex, with the downstream blade, leads to a cyclic transition with high pressure fluctuations on the suction side of the blade and a decay of the tip-gap vortex. The disturbance of the tip-gap vortex results in an unsteady behavior of the turbulent wake causing the intermittent interaction. For this interaction and the cyclic transition, two dominant frequencies are identified which perfectly match with the characteristic frequencies in the experimental sound power level and therefore explain their physical origin.

ING3 promotes prostate cancer growth by activating the androgen receptor.

PubMed

Nabbi, Arash; McClurg, Urszula L; Thalappilly, Subhash; Almami, Amal; Mobahat, Mahsa; Bismar, Tarek A; Binda, Olivier; Riabowol, Karl T

2017-05-16

The androgen receptor (AR) is a major driver of prostate cancer, and increased AR levels and co-activators of the receptor promote the development of prostate cancer. INhibitor of Growth (ING) proteins target lysine acetyltransferase or lysine deacetylase complexes to the histone H3K4Me3 mark of active transcription, to affect chromatin structure and gene expression. ING3 is a stoichiometric member of the TIP60 lysine acetyltransferase complex implicated in prostate cancer development. Biopsies of 265 patients with prostate cancer were stained for ING3, pan-cytokeratin, and DNA. LNCaP and C4-2 androgen-responsive cells were used for in vitro assays including immunoprecipitation, western blotting, Luciferase reporter assay and quantitative polymerase chain reaction. Cell viability and migration assays were performed in prostate cancer cell lines using scrambled siRNA or siRNA targeting ING3. We find that ING3 levels and AR activity positively correlate in prostate cancer. ING3 potentiates androgen effects, increasing expression of androgen-regulated genes and androgen response element-driven reporters to promote growth and anchorage-independent growth. Conversely, ING3 knockdown inhibits prostate cancer cell growth and invasion. ING3 activates the AR by serving as a scaffold to increase interaction between TIP60 and the AR in the cytoplasm, enhancing receptor acetylation and translocation to the nucleus. Activation is independent of ING3's ability to target the TIP60 complex to H3K4Me3, identifying a previously unknown chromatin-independent cytoplasmic activity for ING3. In agreement with in vitro observations, analysis of The Cancer Genome Atlas (TCGA) data (n = 498) and a prostate cancer tissue microarray (n = 256) show that ING3 levels are higher in aggressive prostate cancers, with high levels of ING3 predicting shorter patient survival in a low AR subgroup. Including ING3 levels with currently used indicators such as the Gleason score provides more accurate prognosis in primary prostate cancer. In contrast to the majority of previous reports suggesting tumor suppressive functions in other cancers, our observations identify a clear oncogenic role for ING3, which acts as a co-activator of AR in prostate cancer. Data from TCGA and our previous and current tissue microarrays suggest that ING3 levels correlate with AR levels and that in patients with low levels of the receptor, ING3 level could serve as a useful prognostic biomarker.

Filopodial retraction force is generated by cortical actin dynamics and controlled by reversible tethering at the tip

PubMed Central

Bornschlögl, Thomas; Romero, Stéphane; Vestergaard, Christian L.; Joanny, Jean-François; Van Nhieu, Guy Tran; Bassereau, Patricia

2013-01-01

Filopodia are dynamic, finger-like plasma membrane protrusions that sense the mechanical and chemical surroundings of the cell. Here, we show in epithelial cells that the dynamics of filopodial extension and retraction are determined by the difference between the actin polymerization rate at the tip and the retrograde flow at the base of the filopodium. Adhesion of a bead to the filopodial tip locally reduces actin polymerization and leads to retraction via retrograde flow, reminiscent of a process used by pathogens to invade cells. Using optical tweezers, we show that filopodial retraction occurs at a constant speed against counteracting forces up to 50 pN. Our measurements point toward retrograde flow in the cortex together with frictional coupling between the filopodial and cortical actin networks as the main retraction-force generator for filopodia. The force exerted by filopodial retraction, however, is limited by the connection between filopodial actin filaments and the membrane at the tip. Upon mechanical rupture of the tip connection, filopodia exert a passive retraction force of 15 pN via their plasma membrane. Transient reconnection at the tip allows filopodia to continuously probe their surroundings in a load-and-fail manner within a well-defined force range. PMID:24198333

Carbon Nanoelectrodes for Single-Cell Probing

PubMed Central

Anderson, Sean E.; Bau, Haim H.

2015-01-01

Carbon nanoelectrodes with tip diameters ranging from tens to hundreds of nm are fabricated by pyrolitic deposition of carbon films along the entire inner surfaces of pulled-glass pipettes. The pulled end of each glass pipette is then etched to expose a desired length (typically, a few µm) of carbon pipe. The carbon film provides an electrically conductive path from the nanoscopic carbon tip to the distal, macroscopic end of the pipette, bridging between the nanoscale tip and the macroscale handle, without a need for assembly. We used our nanoelectrodes to penetrate into individual cells and cell nuclei and measured the variations in the electrode impedance upon cell and nucleus penetration as well as the electrode impedance as a function of cell penetration depth. Theoretical predictions based on a simple circuit model were in good agreement with experimental data. PMID:25876625

Plant Evo-Devo: How Tip Growth Evolved.

PubMed

Rensing, Stefan A

2016-12-05

Apical elongation of polarized plant cells (tip growth) occurs in root hairs of flowering plants and in rhizoids of bryophytes. A new report shows that the formation of these cells relies on genes already present in the first land plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cell intrinsic modulation of Wnt signaling controls neuroblast migration in C. elegans.

PubMed

Mentink, Remco A; Middelkoop, Teije C; Rella, Lorenzo; Ji, Ni; Tang, Chung Yin; Betist, Marco C; van Oudenaarden, Alexander; Korswagen, Hendrik C

2014-10-27

Members of the Wnt family of secreted signaling proteins are key regulators of cell migration and axon guidance. In the nematode C. elegans, the migration of the QR neuroblast descendants requires multiple Wnt ligands and receptors. We found that the migration of the QR descendants is divided into three sequential phases that are each mediated by a distinct Wnt signaling mechanism. Importantly, the transition from the first to the second phase, which is the main determinant of the final position of the QR descendants along the anteroposterior body axis, is mediated through a cell-autonomous process in which the time-dependent expression of a Wnt receptor turns on the canonical Wnt/β-catenin signaling response that is required to terminate long-range anterior migration. Our results show that, in addition to direct guidance of cell migration by Wnt morphogenic gradients, cell migration can also be controlled indirectly through cell-intrinsic modulation of Wnt signaling responses.

Endothelial Cell Morphology and Migration are Altered by Changes in Gravitational Fields

NASA Technical Reports Server (NTRS)

Melhado, Caroline; Sanford, Gary; Harris-Hooker, Sandra

1997-01-01

Endothelial cell migration is important to vascular wall regeneration following injury or stress. However, the mechanism(s) governing this response is not well understood. The microgravity environment of space may complicate the response of these cells to injury. To date, there are no reports in this area. We examined how bovine aortic (BAEC) and pulmonary (BPEC) endothelial cells respond to denudation injury under hypergravity (HGrav) and simulated microgravity (MGrav), using image analysis. In 10% FBS, the migration of confluent BAEC and BPEC into the denuded area was not affected by HGrav or MGrav. However, in low FBS (0.5%), signficantly retarded migration under MGrav, and increased migration under HGrav was found. MGrav also decreased the migration of postconfluent BPEC while HGrav showed no difference. Both MGrav and HGrav strongly decreased the migration of postconfluent BAEC. Also, both cell lines showed significant morphological changes by scanning electron microscopy. These studies indicate that endothelial cell function is affected by changes in gravity.

The distinct roles of the nucleus and nucleus-cytoskeleton connections in three-dimensional cell migration

PubMed Central

Khatau, Shyam B.; Bloom, Ryan J.; Bajpai, Saumendra; Razafsky, David; Zang, Shu; Giri, Anjil; Wu, Pei-Hsun; Marchand, Jorge; Celedon, Alfredo; Hale, Christopher M.; Sun, Sean X.; Hodzic, Didier; Wirtz, Denis

2012-01-01

Cells often migrate in vivo in an extracellular matrix that is intrinsically three-dimensional (3D) and the role of actin filament architecture in 3D cell migration is less well understood. Here we show that, while recently identified linkers of nucleoskeleton to cytoskeleton (LINC) complexes play a minimal role in conventional 2D migration, they play a critical role in regulating the organization of a subset of actin filament bundles – the perinuclear actin cap - connected to the nucleus through Nesprin2giant and Nesprin3 in cells in 3D collagen I matrix. Actin cap fibers prolong the nucleus and mediate the formation of pseudopodial protrusions, which drive matrix traction and 3D cell migration. Disruption of LINC complexes disorganizes the actin cap, which impairs 3D cell migration. A simple mechanical model explains why LINC complexes and the perinuclear actin cap are essential in 3D migration by providing mechanical support to the formation of pseudopodial protrusions. PMID:22761994

Alk1 and Alk5 inhibition by Nrp1 controls vascular sprouting downstream of Notch.

PubMed

Aspalter, Irene Maria; Gordon, Emma; Dubrac, Alexandre; Ragab, Anan; Narloch, Jarek; Vizán, Pedro; Geudens, Ilse; Collins, Russell Thomas; Franco, Claudio Areias; Abrahams, Cristina Luna; Thurston, Gavin; Fruttiger, Marcus; Rosewell, Ian; Eichmann, Anne; Gerhardt, Holger

2015-06-17

Sprouting angiogenesis drives blood vessel growth in healthy and diseased tissues. Vegf and Dll4/Notch signalling cooperate in a negative feedback loop that specifies endothelial tip and stalk cells to ensure adequate vessel branching and function. Current concepts posit that endothelial cells default to the tip-cell phenotype when Notch is inactive. Here we identify instead that the stalk-cell phenotype needs to be actively repressed to allow tip-cell formation. We show this is a key endothelial function of neuropilin-1 (Nrp1), which suppresses the stalk-cell phenotype by limiting Smad2/3 activation through Alk1 and Alk5. Notch downregulates Nrp1, thus relieving the inhibition of Alk1 and Alk5, thereby driving stalk-cell behaviour. Conceptually, our work shows that the heterogeneity between neighbouring endothelial cells established by the lateral feedback loop of Dll4/Notch utilizes Nrp1 levels as the pivot, which in turn establishes differential responsiveness to TGF-β/BMP signalling.

Alk1 and Alk5 inhibition by Nrp1 controls vascular sprouting downstream of Notch

PubMed Central

Aspalter, Irene Maria; Gordon, Emma; Dubrac, Alexandre; Ragab, Anan; Narloch, Jarek; Vizán, Pedro; Geudens, Ilse; Collins, Russell Thomas; Franco, Claudio Areias; Abrahams, Cristina Luna; Thurston, Gavin; Fruttiger, Marcus; Rosewell, Ian; Eichmann, Anne; Gerhardt, Holger

2015-01-01

Sprouting angiogenesis drives blood vessel growth in healthy and diseased tissues. Vegf and Dll4/Notch signalling cooperate in a negative feedback loop that specifies endothelial tip and stalk cells to ensure adequate vessel branching and function. Current concepts posit that endothelial cells default to the tip-cell phenotype when Notch is inactive. Here we identify instead that the stalk-cell phenotype needs to be actively repressed to allow tip-cell formation. We show this is a key endothelial function of neuropilin-1 (Nrp1), which suppresses the stalk-cell phenotype by limiting Smad2/3 activation through Alk1 and Alk5. Notch downregulates Nrp1, thus relieving the inhibition of Alk1 and Alk5, thereby driving stalk-cell behaviour. Conceptually, our work shows that the heterogeneity between neighbouring endothelial cells established by the lateral feedback loop of Dll4/Notch utilizes Nrp1 levels as the pivot, which in turn establishes differential responsiveness to TGF-β/BMP signalling. PMID:26081042

Cell Migration in 1D and 2D Nanofiber Microenvironments.

PubMed

Estabridis, Horacio M; Jana, Aniket; Nain, Amrinder; Odde, David J

2018-03-01

Understanding how cells migrate in fibrous environments is important in wound healing, immune function, and cancer progression. A key question is how fiber orientation and network geometry influence cell movement. Here we describe a quantitative, modeling-based approach toward identifying the mechanisms by which cells migrate in fibrous geometries having well controlled orientation. Specifically, U251 glioblastoma cells were seeded onto non-electrospinning Spinneret based tunable engineering parameters fiber substrates that consist of networks of suspended 400 nm diameter nanofibers. Cells were classified based on the local fiber geometry and cell migration dynamics observed by light microscopy. Cells were found in three distinct geometries: adhering two a single fiber, adhering to two parallel fibers, and adhering to a network of orthogonal fibers. Cells adhering to a single fiber or two parallel fibers can only move in one dimension along the fiber axis, whereas cells on a network of orthogonal fibers can move in two dimensions. We found that cells move faster and more persistently in 1D geometries than in 2D, with cell migration being faster on parallel fibers than on single fibers. To explain these behaviors mechanistically, we simulated cell migration in the three different geometries using a motor-clutch based model for cell traction forces. Using nearly identical parameter sets for each of the three cases, we found that the simulated cells naturally replicated the reduced migration in 2D relative to 1D geometries. In addition, the modestly faster 1D migration on parallel fibers relative to single fibers was captured using a correspondingly modest increase in the number of clutches to reflect increased surface area of adhesion on parallel fibers. Overall, the integrated modeling and experimental analysis shows that cell migration in response to varying fibrous geometries can be explained by a simple mechanical readout of geometry via a motor-clutch mechanism.

Notch1-Dll4 signaling and mechanical force regulate leader cell formation during collective cell migration

PubMed Central

Riahi, Reza; Sun, Jian; Wang, Shue; Long, Min; Zhang, Donna D.; Wong, Pak Kin

2015-01-01

At the onset of collective cell migration, a subset of cells within an initially homogenous population acquires a distinct “leader” phenotype with characteristic morphology and motility. However, the factors driving leader cell formation as well as the mechanisms regulating leader cell density during the migration process remain to be determined. Here, we use single cell gene expression analysis and computational modeling to show that leader cell identity is dynamically regulated by Dll4 signaling through both Notch1 and cellular stress in a migrating epithelium. Time-lapse microscopy reveals that Dll4 is induced in leader cells after the creation of the cell-free region and leader cells are regulated via Notch1-Dll4 lateral inhibition. Furthermore, mechanical stress inhibits Dll4 expression and leader cell formation in the monolayer. Collectively, our findings suggest that a reduction of mechanical force near the boundary promotes Notch1-Dll4 signaling to dynamically regulate the density of leader cells during collective cell migration. PMID:25766473

Platelet rich plasma promotes skeletal muscle cell migration in association with up-regulation of FAK, paxillin, and F-Actin formation.

PubMed

Tsai, Wen-Chung; Yu, Tung-Yang; Lin, Li-Ping; Lin, Mioa-Sui; Tsai, Ting-Ta; Pang, Jong-Hwei S

2017-11-01

Platelet rich plasma (PRP) contains various cytokines and growth factors which may be beneficial to the healing process of injured muscle. The aim of this study was to investigate the effect and molecular mechanism of PRP on migration of skeletal muscle cells. Skeletal muscle cells intrinsic to Sprague-Dawley rats were treated with PRP. The cell migration was evaluated by transwell filter migration assay and electric cell-substrate impedance sensing. The spreading of cells was evaluated microscopically. The formation of filamentous actin (F-actin) cytoskeleton was assessed by immunofluorescence staining. The protein expressions of paxillin and focal adhesion kinase (FAK) were assessed by Western blot analysis. Transfection of paxillin small-interfering RNA (siRNAs) to muscle cells was performed to validate the role of paxillin in PRP-mediated promotion of cell migration. Dose-dependently PRP promotes migration of and spreading and muscle cells. Protein expressions of paxillin and FAK were up-regulated dose-dependently. F-actin formation was also enhanced by PRP treatment. Furthermore, the knockdown of paxillin expression impaired the effect of PRP to promote cell migration. It was concluded that PRP promoting migration of muscle cells is associated with up-regulation of proteins expression of paxillin and FAK as well as increasing F-actin formation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2506-2512, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Texture sensing of cytoskeletal dynamics in cell migration

NASA Astrophysics Data System (ADS)

Das, Satarupa; Lee, Rachel; Hourwitz, Matthew J.; Sun, Xiaoyu; Parent, Carole; Fourkas, John T.; Losert, Wolfgang

Migrating cells can be directed towards a target by gradients in properties such as chemical concentration or mechanical properties of the surrounding microenvironment. In previous studies we have shown that micro/nanotopographical features on scales comparable to those of natural collagen fibers can guide fast migrating amoeboid cells by aligning actin polymerization waves to such nanostructures. We find that actin microfilaments and microtubules are aligned along the nanoridge topographies, modulating overall cell polarity and directional migration in epithelial cells. This work shows that topographic features on a biologically relevant length scale can modulate migration outcomes by affecting the texture sensing property of the cytoskeleton.

Dietary spices protect against hydrogen peroxide-induced DNA damage and inhibit nicotine-induced cancer cell migration.

PubMed

Jayakumar, R; Kanthimathi, M S

2012-10-01

Spices are rich sources of antioxidants due to the presence of phenols and flavonoids. In this study, the DNA protecting activity and inhibition of nicotine-induced cancer cell migration of 9 spices were analysed. Murine fibroblasts (3T3-L1) and human breast cancer (MCF-7) cells were pre-treated with spice extracts and then exposed to H₂O₂ and nicotine. The comet assay was used to analyse the DNA damage. Among the 9 spices, ginger, at 50 μg/ml protected against 68% of DNA damage in 3T3-L1 cells. Caraway, cumin and fennel showed statistically significant (p<0.05) DNA protecting activity. Treatment of MCF-7 cells with nicotine induced cell migration, whereas pre-treatment with spices reduced this migration. Pepper, long pepper and ginger exhibited a high rate of inhibition of cell migration. The results of this study prove that spices protect DNA and inhibit cancer cell migration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of TNF-alpha on Endothelial Cell Collective Migration

NASA Astrophysics Data System (ADS)

Chen, Desu; Wu, Di; Helim Aranda-Espinoza, Jose; Losert, Wolfgang

2013-03-01

Tumor necrosis factor (TNF-alpha) is a small cell-signaling protein usually released by monocytes and macrophages during an inflammatory response. Previous work had shown the effects of TNF-alpha on single cell morphology, migration, and biomechanical properties. However, the effect on collective migrations remains unexplored. In this work, we have created scratches on monolayers of human umbilical endothelial cells (HUVECs) treated with 25ng/mL TNF-alpha on glass substrates. The wound healing like processes were imaged with phase contrast microscopy. Quantitative analysis of the collective migration of cells treated with TNF-alpha indicates that these cells maintain their persistent motion and alignment better than untreated cells. In addition, the collective migration was characterized by measuring the amount of non-affine deformations of the wound healing monolayer. We found a lower mean non-affinity and narrower distribution of non-affinities upon TNF-alpha stimulation. These results suggest that TNF-alpha introduces a higher degree of organized cell collective migration.

Oxygen-induced cell migration and on-line monitoring biomarkers modulation of cervical cancers on a microfluidic system

PubMed Central

Lin, Xuexia; Chen, Qiushui; Liu, Wu; Zhang, Jie; Wang, Shiqi; Lin, Zhixiong; Lin, Jin-Ming

2015-01-01

In this work, we report an integrated microfluidic device for cell co-culture under different concentrations of oxygen, in which the secreted protein VEGF165 was on-line qualitatively and semi-quantitatively analyzed by functional nucleic acid, hemin, ABTS and peroxide system. This microfluidic platform allowed investigation of various oxygen and distances effect on cell-to-cell communication. Besides, the microfluidic device was used for real-time analysis of VEGF165 protein by aptamer-functionalized microchannels. Under 5% O2 condition, we found that the migration of CaSki cells was faster than the migration of human umbilical vein endothelial cells. However, the migration of CaSki cells was slower than the migration of HUVECs under 15% O2 condition. Moreover, the shorter intercellular distances, the quicker cells migration. Furthermore, HIF-1α and VEGF165 genes, ROS were analyzed, and the results would provide new perspectives for the diagnosis and medical treatment of cervical cancer. PMID:25905434

Research Techniques Made Simple: Analysis of Collective Cell Migration Using the Wound Healing Assay.

PubMed

Grada, Ayman; Otero-Vinas, Marta; Prieto-Castrillo, Francisco; Obagi, Zaidal; Falanga, Vincent

2017-02-01

Collective cell migration is a hallmark of wound repair, cancer invasion and metastasis, immune responses, angiogenesis, and embryonic morphogenesis. Wound healing is a complex cellular and biochemical process necessary to restore structurally damaged tissue. It involves dynamic interactions and crosstalk between various cell types, interaction with extracellular matrix molecules, and regulated production of soluble mediators and cytokines. In cutaneous wound healing, skin cells migrate from the wound edges into the wound to restore skin integrity. Analysis of cell migration in vitro is a useful assay to quantify alterations in cell migratory capacity in response to experimental manipulations. Although several methods exist to study cell migration (such as Boyden chamber assay, barrier assays, and microfluidics-based assays), in this short report we will explain the wound healing assay, also known as the "in vitro scratch assay" as a simple, versatile, and cost-effective method to study collective cell migration and wound healing. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Computational Models Reveal a Passive Mechanism for Cell Migration in the Crypt

PubMed Central

Dunn, Sara-Jane; Näthke, Inke S.; Osborne, James M.

2013-01-01

Cell migration in the intestinal crypt is essential for the regular renewal of the epithelium, and the continued upward movement of cells is a key characteristic of healthy crypt dynamics. However, the driving force behind this migration is unknown. Possibilities include mitotic pressure, active movement driven by motility cues, or negative pressure arising from cell loss at the crypt collar. It is possible that a combination of factors together coordinate migration. Here, three different computational models are used to provide insight into the mechanisms that underpin cell movement in the crypt, by examining the consequence of eliminating cell division on cell movement. Computational simulations agree with existing experimental results, confirming that migration can continue in the absence of mitosis. Importantly, however, simulations allow us to infer mechanisms that are sufficient to generate cell movement, which is not possible through experimental observation alone. The results produced by the three models agree and suggest that cell loss due to apoptosis and extrusion at the crypt collar relieves cell compression below, allowing cells to expand and move upwards. This finding suggests that future experiments should focus on the role of apoptosis and cell extrusion in controlling cell migration in the crypt. PMID:24260407

Dexamethasone disrupts cytoskeleton organization and migration of T47D Human breast cancer cells by modulating the AKT/mTOR/RhoA pathway.

PubMed

Meng, Xian-Guo; Yue, Shou-Wei

2014-01-01

Glucocorticoids are commonly co-administered with chemotherapy to prevent drug-induced allergic reactions, nausea, and vomiting, and have anti-tumor functions clinically; however, the distinct effects of GC on subtypes of tumor cells, especially in breast cancer cells, are still not well understood. In this study, we aimed to clarify the effect of GC on subtypes of T47D breast cancer cells by focusing on apoptosis, cell organization and migration, and underluing molecular mechanisms. The cell scratch test was performed to observe the cell migration rate in T47D cells treated with dexamethasone (Dex). Hoechst and MTT assays were conducted to detect cell survival and rhodamine-labeled phalloidin staining to observe cytoskeleton dynamics. Related factors in the AKT/mTOR pathway were determined by Western blotting. Dex treatment could effectively inhibit T47D breast cancer cell migration with disruption of the cytoskeletal dynamic organization. Moreover, the effect of Dex on cell migration and cytoskeleton may be mediated by AKT/ mTOR/RhoA pathway. Although Dex inhibited T47D cell migration, it alone may not induce cell apoptosis in T47D cells. Dex in T47D human breast cancer cells could effectively inhibit cell migration by disrupting the cytoskeletal dynamic organization, which may be mediated by the AKT/mTOR/RhoA pathway. Our work suggests that glucocorticoid/Dex clinical use may prove helpful for the treatment of breast cancer metastasis.

HMG-CoA reductase regulates CCL17-induced colon cancer cell migration via geranylgeranylation and RhoA activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Haidari, Amr A.; Syk, Ingvar; Thorlacius, Henrik, E-mail: henrik.thorlacius@med.lu.se

2014-03-28

Highlights: • Simvastatin blocked CCL17-induced and CCR4-dependent RhoA activation in HT29 cells. • CCL17/CCR4-mediated migration of colon cancer cells was antagonised by simvastatin. • Cell migration recovered by adding Mevalonate and geranylgeranyl pyrophosphate. • Targeting HMG-CoA reductase might be useful to inhibit colon cancer metastasis. - Abstract: Background: Simvastatin is widely used to lower cholesterol levels in patients with cardiovascular diseases, although accumulating evidence suggests that statins, such as simvastatin, also exert numerous anti-tumoral effects. Aim: The aim of this study was to examine the effect of simvastatin on colon cancer cell migration. Methods: Migration assays were performed to evaluatemore » CCL17-induced colon cancer cell (HT-29) chemotaxis. In vitro tumor growth and apoptosis were assessed using a proliferation assay and annexin V assay, respectively. Active RhoA protein levels in CCL17-stimulated colon cancer cells were quantified using a G-LISA assay. Results: We found that simvastatin dose-dependently decreased CCL17-induced colon cancer cell migration. Simvastatin had no effect on colon cancer cell proliferation or apoptosis. Inhibition of beta chemokine receptor 4, CCR4, reduced CCL17-evoked activation of RhoA in colon cancer cells. Moreover, administration of mevalonate reversed the inhibitory effect of simvastatin on CCL17-induced colon cancer cell migration. Interestingly, co-incubation with geranylgeranyl pyrophosphate (GGPP) antagonized the inhibitory impact of simvastatin on colon cancer cell migration triggered by CCL17. Moreover, we observed that simvastatin decreased CCL17-induced activation of RhoA in colon cancer cells. Administration of mevalonate and GGPP reversed the inhibitory effect of simvastatin on CCL17-provoked RhoA activation in colon cancer cells. Conclusions: Taken together, our findings show for the first time that HMG-CoA reductase regulates CCL17-induced colon cancer cell migration via inhibition of geranylgeranylation and RhoA activation. Thus, statins, such as simvastatin, might be effective tools to antagonize CCL17-dependent migration and metastasis of colon cancer cells.« less

Dynamin1 is a novel target for IRSp53 protein and works with mammalian enabled (Mena) protein and Eps8 to regulate filopodial dynamics.

PubMed

Chou, Ai Mei; Sem, Kai Ping; Wright, Graham Daniel; Sudhaharan, Thankiah; Ahmed, Sohail

2014-08-29

Filopodia are dynamic actin-based structures that play roles in processes such as cell migration, wound healing, and axonal guidance. Cdc42 induces filopodial formation through IRSp53, an Inverse-Bin-Amphiphysins-Rvs (I-BAR) domain protein. Previous work from a number of laboratories has shown that IRSp53 generates filopodia by coupling membrane protrusion with actin dynamics through its Src homology 3 domain binding partners. Here, we show that dynamin1 (Dyn1), the large guanosine triphosphatase, is an interacting partner of IRSp53 through pulldown and Förster resonance energy transfer analysis, and we explore its role in filopodial formation. In neuroblastoma cells, Dyn1 localizes to filopodia, associated tip complexes, and the leading edge just behind the anti-capping protein mammalian enabled (Mena). Dyn1 knockdown reduces filopodial formation, which can be rescued by overexpressing wild-type Dyn1 but not the GTPase mutant Dyn1-K44A and the loss-of-function actin binding domain mutant Dyn1-K/E. Interestingly, dynasore, an inhibitor of Dyn GTPase, also reduced filopodial number and increased their lifetime. Using rapid time-lapse total internal reflection fluorescence microscopy, we show that Dyn1 and Mena localize to filopodia only during initiation and assembly. Dyn1 actin binding domain mutant inhibits filopodial formation, suggesting a role in actin elongation. In contrast, Eps8, an actin capping protein, is seen most strongly at filopodial tips during disassembly. Taken together, the results suggest IRSp53 partners with Dyn1, Mena, and Eps8 to regulate filopodial dynamics. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Dynamics of cells function on laser cell-chip system

NASA Astrophysics Data System (ADS)

Kushibiki, Toshihiro; Sano, Tomoko; Ishii, Katsunori; Yoshihashi-Suzuki, Sachiko; Awazu, Kunio

2006-02-01

A new type of cell-cultivation system based on laser processing has been developed for the on-chip cultivation of living cells. We introduce a "laser cell-chip", on which migration of cells, such as stem cells, tumor cells or immunocompetent cells, can be observed. A sheet prepared from epoxy resin was processed by KrF excimer laser (248 nm, 1.6 J/cm2) for preparation of microgrooved surfaces with various groove width, spacing, and depth. A laser cell-chip can make kinetic studies of cell migration depending on the concentration gradient of a chemoattractant. In this study, megakaryocytes were used for the migration on a groove of laser cell-chip by the concentration gradient of the stromal cell derived factor 1 (SDF-1/CXCL12). SDF-1/CXCL12 plays an important and unique role in the regulation of stem/progenitor cell trafficking. A megakaryocyte was migrated on a groove of laser cell-chip depending on the optical concentration gradient of SDF-1/CXCL12. Since SDF-1/CXCL12-induced migration of mature megakaryocyte was known to increase the platelet production in the bone marrow extravascular space, the diagnosis of cell migration on laser cell-chip could provide a new strategy to potentially reconstitute hematopoiesis and avoid life-threatening hemorrhage after myelosuppression or bone marrow failure.

Mast cell migration to Th2 stimulated airway smooth muscle from asthmatics

PubMed Central

Sutcliffe, A; Kaur, D; Page, S; Woodman, L; Armour, C L; Baraket, M; Bradding, P; Hughes, J M; Brightling, C E

2006-01-01

Background Mast cell microlocalisation within the airway smooth muscle (ASM) bundle is an important determinant of the asthmatic phenotype. We hypothesised that mast cells migrate towards ASM in response to ASM derived chemokines. Methods Primary ASM cultures from subjects with and without asthma were stimulated with interleukin (IL)‐1β, IL‐4, and IL‐13 alone and in combination. Mast cell chemotaxis towards these ASM supernatants was investigated, and the chemotaxins mediating migration by using specific blocking antibodies for stem cell factor (SCF) and the chemokine receptors CCR3, CXCR1, 3 and 4 as well as the Gi inhibitor pertussis toxin and the tyrosine kinase inhibitor genistein were defined. The concentrations of CCL11, CXCL8, CXCL10, TGF‐β, and SCF in the supernatants were measured and the effect of non‐asthmatic ASM supernatants on the mast cell chemotactic activity of asthmatic ASM was examined. Results Human lung mast cells and HMC‐1 cells migrated towards Th2 stimulated ASM from asthmatics but not non‐asthmatics. Mast cell migration was mediated through the combined activation of CCR3 and CXCR1. CCL11 and CXCL8 expression by ASM increased markedly after stimulation, but was similar in those with and without asthma. ASM supernatants from non‐asthmatics inhibited mast cell migration towards the asthmatic ASM supernatant. Conclusion Th2 stimulated ASM from asthmatics is chemotactic for mast cells. Non‐asthmatic ASM releases a mediator or mediators that inhibit mast cell migration towards stimulated asthmatic ASM. Specifically targeting mast cell migration into the ASM bundle may provide a novel treatment for asthma. PMID:16601090

Tre1 GPCR initiates germ cell transepithelial migration by regulating Drosophila melanogaster E-cadherin

PubMed Central

Kunwar, Prabhat S.; Sano, Hiroko; Renault, Andrew D.; Barbosa, Vitor; Fuse, Naoyuki; Lehmann, Ruth

2008-01-01

Despite significant progress in identifying the guidance pathways that control cell migration, how a cell starts to move within an intact organism, acquires motility, and loses contact with its neighbors is poorly understood. We show that activation of the G protein–coupled receptor (GPCR) trapped in endoderm 1 (Tre1) directs the redistribution of the G protein Gβ as well as adherens junction proteins and Rho guanosine triphosphatase from the cell periphery to the lagging tail of germ cells at the onset of Drosophila melanogaster germ cell migration. Subsequently, Tre1 activity triggers germ cell dispersal and orients them toward the midgut for directed transepithelial migration. A transition toward invasive migration is also a prerequisite for metastasis formation, which often correlates with down-regulation of adhesion proteins. We show that uniform down-regulation of E-cadherin causes germ cell dispersal but is not sufficient for transepithelial migration in the absence of Tre1. Our findings therefore suggest a new mechanism for GPCR function that links cell polarity, modulation of cell adhesion, and invasion. PMID:18824569

Stromal cell-derived factor 1 (SDF-1) accelerated skin wound healing by promoting the migration and proliferation of epidermal stem cells.

PubMed

Guo, Rui; Chai, Linlin; Chen, Liang; Chen, Wenguang; Ge, Liangpeng; Li, Xiaoge; Li, Hongli; Li, Shirong; Cao, Chuan

2015-06-01

Epidermal stem cells could contribute to skin repair through the migration of cells from the neighboring uninjured epidermis, infundibulum, hair follicle, or sebaceous gland. However, little is known about the factors responsible for the complex biological processes in wound healing. Herein, we will show that the attracting chemokine, SDF-1/CXCR4, is a major regulator involved in the migration of epidermal stem cells during wound repair. We found that the SDF-1 levels were markedly increased at the wound margins following injury and CXCR4 expressed in epidermal stem cells and proliferating epithelial cells. Blocking the SDF-1/CXCR4 axis resulted in a significant reduction in epidermal stem cell migration toward SDF-1 in vitro and delayed wound healing in vivo, while an SDF-1 treatment enhanced epidermal stem cell migration and proliferation and accelerated wound healing. These results provide direct evidence that SDF-1 promotes epidermal stem cell migration, accelerates skin regeneration, and makes the development of new regenerative therapeutic strategies for wound healing possible.

E-cadherin is required for cranial neural crest migration in Xenopus laevis.

PubMed

Huang, Chaolie; Kratzer, Marie-Claire; Wedlich, Doris; Kashef, Jubin

2016-03-15

The cranial neural crest (CNC) is a highly motile and multipotent embryonic cell population, which migrates directionally on defined routes throughout the embryo, contributing to facial structures including cartilage, bone and ganglia. Cadherin-mediated cell-cell adhesion is known to play a crucial role in the directional migration of CNC cells. However, migrating CNC co-express different cadherin subtypes, and their individual roles have yet to be fully explored. In previous studies, the expression of individual cadherin subtypes has been analysed using different methods with varying sensitivities, preventing the direct comparison of expression levels. Here, we provide the first comprehensive and comparative analysis of the expression of six cadherin superfamily members during different phases of CNC cell migration in Xenopus. By applying a quantitative RT-qPCR approach, we can determine the copy number and abundance of each expressed cadherin through different phases of CNC migration. Using this approach, we show for the first time expression of E-cadherin and XB/C-cadherin in CNC cells, adding them as two new members of cadherins co-expressed during CNC migration. Cadherin co-expression during CNC migration in Xenopus, in particular the constant expression of E-cadherin, contradicts the classical epithelial-mesenchymal transition (EMT) model postulating a switch in cadherin expression. Loss-of-function experiments further show that E-cadherin is required for proper CNC cell migration in vivo and also for cell protrusion formation in vitro. Knockdown of E-cadherin is not rescued by co-injection of other classical cadherins, pointing to a specific function of E-cadherin in mediating CNC cell migration. Finally, through reconstitution experiments with different E-cadherin deletion mutants in E-cadherin morphant embryos, we demonstrate that the extracellular domain, but not the cytoplasmic domain, of E-cadherin is sufficient to rescue CNC cell migration in vivo. Copyright © 2016 Elsevier Inc. All rights reserved.

Physical limits of cell migration: control by ECM space and nuclear deformation and tuning by proteolysis and traction force.

PubMed

Wolf, Katarina; Te Lindert, Mariska; Krause, Marina; Alexander, Stephanie; Te Riet, Joost; Willis, Amanda L; Hoffman, Robert M; Figdor, Carl G; Weiss, Stephen J; Friedl, Peter

2013-06-24

Cell migration through 3D tissue depends on a physicochemical balance between cell deformability and physical tissue constraints. Migration rates are further governed by the capacity to degrade ECM by proteolytic enzymes, particularly matrix metalloproteinases (MMPs), and integrin- and actomyosin-mediated mechanocoupling. Yet, how these parameters cooperate when space is confined remains unclear. Using MMP-degradable collagen lattices or nondegradable substrates of varying porosity, we quantitatively identify the limits of cell migration by physical arrest. MMP-independent migration declined as linear function of pore size and with deformation of the nucleus, with arrest reached at 10% of the nuclear cross section (tumor cells, 7 µm²; T cells, 4 µm²; neutrophils, 2 µm²). Residual migration under space restriction strongly depended upon MMP-dependent ECM cleavage by enlarging matrix pore diameters, and integrin- and actomyosin-dependent force generation, which jointly propelled the nucleus. The limits of interstitial cell migration thus depend upon scaffold porosity and deformation of the nucleus, with pericellular collagenolysis and mechanocoupling as modulators.

The C. elegans tailless/Tlx homolog nhr-67 regulates a stage-specific program of linker cell migration in male gonadogenesis.

PubMed

Kato, Mihoko; Sternberg, Paul W

2009-12-01

Cell migration is a common event during organogenesis, yet little is known about how migration is temporally coordinated with organ development. We are investigating stage-specific programs of cell migration using the linker cell (LC), a migratory cell crucial for male gonadogenesis of C. elegans. During the L3 and L4 larval stages of wild-type males, the LC undergoes changes in its position along the migratory route, in transcriptional regulation of the unc-5 netrin receptor and zmp-1 zinc matrix metalloprotease, and in cell morphology. We have identified the tailless homolog nhr-67 as a cell-autonomous, stage-specific regulator of timing in LC migration programs. In nhr-67-deficient animals, each of the L3 and L4 stage changes is either severely delayed or never occurs, yet LC development before the early L3 stage or after the mid-L4 stage occurs with normal timing. We propose that there is a basal migration program utilized throughout LC migration that is modified by stage-specific regulators such as nhr-67.

Dioscin Inhibits HSC-T6 Cell Migration via Adjusting SDC-4 Expression: Insights from iTRAQ-Based Quantitative Proteomics.

PubMed

Yin, Lianhong; Qi, Yan; Xu, Youwei; Xu, Lina; Han, Xu; Tao, Xufeng; Song, Shasha; Peng, Jinyong

2017-01-01

Hepatic stellate cells (HSCs) migration, an important bioprocess, contributes to the development of liver fibrosis. Our previous studies have found the potent activity of dioscin against liver fibrosis by inhibiting HSCs proliferation, triggering the senescence and inducing apoptosis of activated HSCs, but the molecular mechanisms associated with cell migration were not clarified. In this work, iTRAQ (isobaric tags for relative and absolution quantitation)-based quantitative proteomics study was carried out, and a total of 1566 differentially expressed proteins with fold change ≥2.0 and p < 0.05 were identified in HSC-T6 cells treated by dioscin (5.0 μg/mL). Based on Gene Ontology classification, String and KEGG pathway assays, the effects of dioscin to inhibit cell migration via regulating SDC-4 were carried out. The results of wound-healing, cell migration and western blotting assays indicated that dioscin significantly inhibit HSC-T6 cell migration through SDC-4-dependent signal pathway by affecting the expression levels of Fn, PKCα, Src, FAK, and ERK1/2. Specific SDC-4 knockdown by shRNA also blocked HSC-T6 cell migration, and dioscin slightly enhanced the inhibiting effect. Taken together, the present work showed that SDC-4 played a crucial role on HSC-T6 cell adhesion and migration of dioscin against liver fibrosis, which may be one potent therapeutic target for fibrotic diseases.

Tumor cell migration screen identifies SRPK1 as breast cancer metastasis determinant.

PubMed

van Roosmalen, Wies; Le Dévédec, Sylvia E; Golani, Ofra; Smid, Marcel; Pulyakhina, Irina; Timmermans, Annemieke M; Look, Maxime P; Zi, Di; Pont, Chantal; de Graauw, Marjo; Naffar-Abu-Amara, Suha; Kirsanova, Catherine; Rustici, Gabriella; Hoen, Peter A C 't; Martens, John W M; Foekens, John A; Geiger, Benjamin; van de Water, Bob

2015-04-01

Tumor cell migration is a key process for cancer cell dissemination and metastasis that is controlled by signal-mediated cytoskeletal and cell matrix adhesion remodeling. Using a phagokinetic track assay with migratory H1299 cells, we performed an siRNA screen of almost 1,500 genes encoding kinases/phosphatases and adhesome- and migration-related proteins to identify genes that affect tumor cell migration speed and persistence. Thirty candidate genes that altered cell migration were validated in live tumor cell migration assays. Eight were associated with metastasis-free survival in breast cancer patients, with integrin β3-binding protein (ITGB3BP), MAP3K8, NIMA-related kinase (NEK2), and SHC-transforming protein 1 (SHC1) being the most predictive. Examination of genes that modulate migration indicated that SRPK1, encoding the splicing factor kinase SRSF protein kinase 1, is relevant to breast cancer outcomes, as it was highly expressed in basal breast cancer. Furthermore, high SRPK1 expression correlated with poor breast cancer disease outcome and preferential metastasis to the lungs and brain. In 2 independent murine models of breast tumor metastasis, stable shRNA-based SRPK1 knockdown suppressed metastasis to distant organs, including lung, liver, and spleen, and inhibited focal adhesion reorganization. Our study provides comprehensive information on the molecular determinants of tumor cell migration and suggests that SRPK1 has potential as a drug target for limiting breast cancer metastasis.

Interactions of UNC-34 Enabled With Rac GTPases and the NIK Kinase MIG-15 in Caenorhabditis elegans Axon Pathfinding and Neuronal Migration

PubMed Central

Shakir, M. Afaq; Gill, Jason S.; Lundquist, Erik A.

2006-01-01

Many genes that affect axon pathfinding and cell migration have been identified. Mechanisms by which these genes and the molecules they encode interact with one another in pathways and networks to control developmental events are unclear. Rac GTPases, the cytoskeletal signaling molecule Enabled, and NIK kinase have all been implicated in regulating axon pathfinding and cell migration. Here we present evidence that, in Caenorhabditis elegans, three Rac GTPases, CED-10, RAC-2, and MIG-2, define three redundant pathways that each control axon pathfinding, and that the NIK kinase MIG-15 acts in each Rac pathway. Furthermore, we show that the Enabled molecule UNC-34 defines a fourth partially redundant pathway that acts in parallel to Rac/MIG-15 signaling in axon pathfinding. Enabled and the three Racs also act redundantly to mediate AQR and PQR neuronal cell migration. The Racs and UNC-34 Ena might all control the formation of actin-based protrusive structures (lamellipodia and filopodia) that mediate growth cone outgrowth and cell migration. MIG-15 does not act with the three Racs in execution of cell migration. Rather, MIG-15 affects direction of PQR neuronal migration, similar to UNC-40 and DPY-19, which control initial Q cell polarity, and Wnt signaling, which acts later to control Q cell-directed migration. MIG-2 Rac, which acts with CED-10 Rac, RAC-2 Rac, and UNC-34 Ena in axon pathfinding and cell migration, also acts with MIG-15 in PQR directional migration. PMID:16204220

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Feng-zhen; Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, PR China.; Yu, Chao

O-GlcNAcylation is a dynamic and reversible posttranslational modification of nuclear and cytoplasmic proteins. In recent years, the roles of O-GlcNAcylation in several human malignant tumors have been investigated, and O-GlcNAcylation was found to be linked to cellular features relevant to metastasis. In this study, we modeled four diverse ovarian cancer cells and investigated the effects of O-GlcNAcylation on ovarian cancer cell migration. We found that total O-GlcNAcylation level was elevated in HO-8910PM cells compared to OVCAR3 cells. Additionally, through altering the total O-GlcNAcylation level by OGT silencing or OGA inhibition, we found that the migration of OVCAR3 cells was dramaticallymore » enhanced by PUGNAc and Thiamet G treatment, and the migration ability of HO-8910PM cells was significantly inhibited by OGT silencing. Furthermore, we also found that the expression of E-cadherin, an O-GlcNAcylated protein in ovarian cancer cells, was reduced by OGA inhibition in OVCAR3 cells and elevated by OGT silencing in HO-8910PM cells. These results indicate that O-GlcNAcylation could enhance ovarian cancer cell migration and decrease the expression of E-cadherin. Our studies also suggest that O-GlcNAcylation might become another potential target for the therapy of ovarian cancer. -- Highlights: • We examine the migration potential of diverse ovarian cancer cells. • We examine the total O-GlcNAcylation level of diverse ovarian cancer cells. • Increasing O-GlcNAcylation level will enhance the migration of ovarian cancer cells. • Reducing O-GlcNAcylation level will inhibit the migration of ovarian cancer cells. • The mechanism explains O-GlcNAcylation enhance ovarian cancer cell migration.« less

Collective cell migration of thyroid carcinoma cells: a beneficial ability to override unfavourable substrates.

PubMed

Lobastova, Liudmila; Kraus, Dominik; Glassmann, Alexander; Khan, Dilaware; Steinhäuser, Christian; Wolff, Christina; Veit, Nadine; Winter, Jochen; Probstmeier, Rainer

2017-02-01

Tumor cell invasion and metastasis are life threatening events. Invasive tumor cells tend to migrate as collective sheets. In the present in vitro study we aimed to (i) assess whether collective tumor cells gain benefits in their migratory potential compared to single cells and (ii) to identify its putative underlying molecular mechanisms. The migratory potential of single and collective carcinoma cells was assessed using video time lapse microscopy and cell migration assays in the absence and presence of seven potential gap junction inhibitors or the Rac1 inhibitor Z62954982. The perturbation of gap junctions was assessed using a dye diffusion assay. In addition, LDH-based cytotoxicity and RT-PCR-based expression analyses were performed. Whereas single breast, cervix and thyroid carcinoma cells were virtually immobile on unfavourable plastic surfaces, we found that they gained pronounced migratory capacities as collectives under comparable conditions. Thyroid carcinoma cells, that were studied in more detail, were found to express specific subsets of connexins and to form active gap junctions as revealed by dye diffusion analysis. Although all potential gap junction blockers suppressed intercellular dye diffusion in at least one of the cell lines tested, only two of them were found to inhibit collective cell migration and none of them to inhibit single cell migration. In the presence of the Rac1 inhibitor Z62954982 collective migration, but not single cell migration, was found to be reduced up to 20 %. Our data indicate that collective migration enables tumor cells to cross otherwise unfavourable substrate areas. This capacity seems to be independent of intercellular communication via gap junctions, whereas Rac1-dependent intracellular signalling seems to be essential.

Graded-index fiber tip optical tweezers: numerical simulation and trapping experiment.

PubMed

Gong, Yuan; Ye, Ai-Yan; Wu, Yu; Rao, Yun-Jiang; Yao, Yao; Xiao, Song

2013-07-01

Optical fiber tweezers based on a graded-index multimode fiber (GIMMF) tip is proposed. Light propagation characteristics and gradient force distribution near the GIMMF tip are numerically investigated, which are further compared with that of optical fiber tips based on conventional single mode fibers. The simulated results indicated that by selecting optimal GIMMF length, the gradient force of the GIMMF tip tweezers is about 4 times higher than that of the SMF tip tweezers with a same shape. To prove the feasibility of such a new concept, optical trapping of yeast cells with a diameter of ~5 μm using the chemically-etched GIMMF tip is experimentally demonstrated and the trapping force is also calculated.

Agmatine promotes the migration of murine brain endothelial cells via multiple signaling pathways.

PubMed

Jung, Hyun-Joo; Jeon, Yong-Heui; Bokara, Kiran Kumar; Koo, Bon-Nyeo; Lee, Won Taek; Park, Kyung Ah; Lee, Jong-Eun

2013-01-17

The combination of adhesion and migration of endothelial cells (ECs) is an integral process for evolution, organization, repair and vessel formation in living organisms. Agmatine, a polycationic amine existing in brain, has been investigated to exert neuroprotective effects. Up to date, there are no studies reporting that agmatine modulates murine brain endothelial (bEnd.3) cells migration. In the present study, we intend to investigate the role of agmatine in bEnd.3 cells migration and the molecular mechanism mediating this action. The effect of agmatine on the bEnd.3 cells migration was examined by migration assay, and the mechanism involved for this effect was investigated by western blot analysis and NO contents measurements. Agmatine treatment (50, 100 and 200 μM) significantly accelerated bEnd.3 cells migration in a concentration-dependent manner. Western blotting revealed that agmatine treatment significantly induced vascular endothelial growth factor (VEGF), VEGF receptor 2 (Flk-1/KDR or VEGFR2), phosphatidylinositol 3-kinase (PI3K), Akt/protein kinase B (also known as PKB, PI3K downstream effector protein), endothelial nitric oxide synthase (eNOS) nitric oxide (NO; product by eNOS) and intercellular adhesion molecule 1 (ICAM-1) expressions during bEnd.3 cells migration. The expression of ICAM-1 and migration of bEnd.3 cells, induced by agmatine, were significantly attenuated by treatment of wortmannin, a specific PI3K inhibitor. Taken together, we provide the first evidence that activation of VEGF/VEGFR2 and the consequential PI3K/Akt/eNOS/NO/ICAM-1 signaling pathways are serial events, through which the treatment of agmatine could lead to bEnd.3 cells migration. Copyright © 2012 Elsevier Inc. All rights reserved.

Enhanced migration of tissue inhibitor of metalloproteinase overexpressing hepatoma cells is attributed to gelatinases: Relevance to intracellular signaling pathways

PubMed Central

Roeb, Elke; Bosserhoff, Anja-Katrin; Hamacher, Sabine; Jansen, Bettina; Dahmen, Judith; Wagner, Sandra; Matern, Siegfried

2005-01-01

AIM: To study the effect of gelatinases (especially MMP-9) on migration of tissue inhibitor of metalloproteinase (TIMP-1) overexpressing hepatoma cells. METHODS: Wild type HepG2 cells, cells stably transfected with TIMP-1 and TIMP-1 antagonist (MMP-9-H401A, a catalytically inactive matrix metalloproteinase (MMP) which still binds and neutralizes TIMP-1) were incubated in Boyden chambers either with or without Galardin (a synthetic inhibitor of MMP-1, -2, -3, -8, -9) or a specific inhibitor of gelatinases. RESULTS: Compared to wild type HepG2 cells, the cells overexpressing TIMP-1 showed 115% migration (P<0.05) and the cells overexpressing MMP-9-H401A showed 62% migration (P<0.01). Galardin reduced cell migration dose dependently in all cases. The gelatinase inhibitor reduced migration in TIMP-1 overexpressing cells predominantly. Furthermore, we examined intracellular signal transduction pathways of TIMP-1-dependent HepG2 cells. TIMP-1 deactivates cell signaling pathways of MMP-2 and MMP-9 involving p38 mitogen-activated protein kinase. Specific blockade of the ERK pathway suppresses gelatinase expression either in the presence or absence of TIMP-1. CONCLUSION: Overexpressing functional TIMP-1- enhanced migration of HepG2-TIMP-1 cells depends on enhanced MMP-activity, especially MMP-9. PMID:15754388

Intravital multiphoton imaging reveals multicellular streaming as a crucial component of in vivo cell migration in human breast tumors

PubMed Central

Patsialou, Antonia; Bravo-Cordero, Jose Javier; Wang, Yarong; Entenberg, David; Liu, Huiping; Clarke, Michael; Condeelis, John S.

2014-01-01

Metastasis is the main cause of death in breast cancer patients. Cell migration is an essential component of almost every step of the metastatic cascade, especially the early step of invasion inside the primary tumor. In this report, we have used intravital multiphoton microscopy to visualize the different migration patterns of human breast tumor cells in live primary tumors. We used xenograft tumors of MDA-MB-231 cells as well as a low passage xenograft tumor from orthotopically injected patient-derived breast tumor cells. Direct visualization of human tumor cells in vivo shows two patterns of high-speed migration inside primary tumors: a. single cells and b. multicellular streams (i.e., cells following each other in a single file but without cohesive cell junctions). Critically, we found that only streaming and not random migration of single cells was significantly correlated with proximity to vessels, with intravasation and with numbers of elevated circulating tumor cells in the bloodstream. Finally, although the two human tumors were derived from diverse genetic backgrounds, we found that their migratory tumor cells exhibited coordinated gene expression changes that led to the same end-phenotype of enhanced migration involving activating actin polymerization and myosin contraction. Our data are the first direct visualization and assessment of in vivo migration within a live patient-derived breast xenograft tumor. PMID:25013744

Carbon Ion Radiation Inhibits Glioma and Endothelial Cell Migration Induced by Secreted VEGF

PubMed Central

Liu, Yang; Liu, Yuanyuan; Sun, Chao; Gan, Lu; Zhang, Luwei; Mao, Aihong; Du, Yuting; Zhou, Rong; Zhang, Hong

2014-01-01

This study evaluated the effects of carbon ion and X-ray radiation and the tumor microenvironment on the migration of glioma and endothelial cells, a key process in tumorigenesis and angiogenesis during cancer progression. C6 glioma and human microvascular endothelial cells were treated with conditioned medium from cultures of glioma cells irradiated at a range of doses and the migration of both cell types, tube formation by endothelial cells, as well as the expression and secretion of migration-related proteins were evaluated. Exposure to X-ray radiation-conditioned medium induced dose-dependent increases in cell migration and tube formation, which were accompanied by an upregulation of vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-2 and -9 expression. However, glioma cells treated with conditioned medium of cells irradiated at a carbon ion dose of 4.0 Gy showed a marked decrease in migratory potential and VEGF secretion relative to non-irradiated cells. The application of recombinant VEGF165 stimulated migration in glioma and endothelial cells, which was associated with increased FAK phosphorylation at Tyr861, suggesting that the suppression of cell migration by carbon ion radiation could be via VEGF-activated FAK signaling. Taken together, these findings indicate that carbon ion may be superior to X-ray radiation for inhibiting tumorigenesis and angiogenesis through modulation of VEGF level in the glioma microenvironment. PMID:24893038

Cell Adhesion-dependent Serine 85 Phosphorylation of Paxillin Modulates Focal Adhesion Formation and Haptotactic Migration via Association with the C-terminal Tail Domain of Talin*

PubMed Central

Kwak, Tae Kyoung; Lee, Mi-Sook; Ryu, Jihye; Choi, Yoon-Ju; Kang, Minkyung; Jeong, Doyoung; Lee, Jung Weon

2012-01-01

Integrin-mediated adhesion to extracellular matrix proteins is dynamically regulated during morphological changes and cell migration. Upon cell adhesion, protein-protein interactions among molecules at focal adhesions (FAs) play major roles in the regulation of cell morphogenesis and migration. Although tyrosine phosphorylation of paxillin is critically involved in adhesion-mediated signaling, the significance of paxillin phosphorylation at Ser-85 and the mechanism by which it regulates cell migration remain unclear. In this study, we examined how Ser-85 phosphorylation of paxillin affects FA formation and cell migration. We found that paxillin phosphorylation at Ser-85 occurred during HeLa cell adhesion to collagen I and was concomitant with tyrosine phosphorylation of both focal adhesion kinase and talin. However, the non-phosphorylatable S85A mutant of paxillin impaired cell spreading, FA turnover, and migration toward collagen I but not toward serum. Furthermore, whereas the (presumably indirect) interaction between paxillin and the C-terminal tail of talin led to dynamic FAs at the cell boundary, S85A paxillin did not bind talin and caused stabilized FAs in the central region of cells. Together, these observations suggest that cell adhesion-dependent Ser-85 phosphorylation of paxillin is important for its interaction with talin and regulation of dynamic FAs and cell migration. PMID:22761432

Downregulation of NEDD9 by apigenin suppresses migration, invasion, and metastasis of colorectal cancer cells

PubMed Central

Dai, Jin; Van Wie, Peter G.; Fai, Leonard Yenwong; Kim, Donghern; Wang, Lei; Poyil, Pratheeshkumar; Luo, Jia; Zhang, Zhuo

2018-01-01

Apigenin is a natural flavonoid which possesses multiple anti-cancer properties such as anti-proliferation, anti-inflammation, and anti-metastasis in many types of cancers including colorectal cancer. Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a multi-domain scaffolding protein of the Cas family which has been shown to correlate with cancer metastasis and progression. The present study investigates the role of NEDD9 in apigenin-inhibited cell migration, invasion, and metastasis of colorectal adenocarcinoma DLD1 and SW480 cells. The results show that knockdown of NEDD9 inhibited cell migration, invasion, and metastasis and that overexpression of NEDD9 promoted cell migration and invasion of DLD1 cells and SW4890 cells. Apigenin treatment attenuated NEDD9 expression at protein level, resulting in reduced phosphorylations of FAK, Src, and Akt, leading to inhibition on cell migration, invasion, and metastasis of both DLD1 and SW480 cells. The present study has demonstrated that apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt cascade in colorectal cancer cells. NEDD9 may function as a biomarker for evaluation of cancer aggressiveness and for selection of therapeutic drugs against cancer progression. PMID:27664007

A model for cell migration in non-isotropic fibrin networks with an application to pancreatic tumor islets.

PubMed

Chen, Jiao; Weihs, Daphne; Vermolen, Fred J

2018-04-01

Cell migration, known as an orchestrated movement of cells, is crucially important for wound healing, tumor growth, immune response as well as other biomedical processes. This paper presents a cell-based model to describe cell migration in non-isotropic fibrin networks around pancreatic tumor islets. This migration is determined by the mechanical strain energy density as well as cytokines-driven chemotaxis. Cell displacement is modeled by solving a large system of ordinary stochastic differential equations where the stochastic parts result from random walk. The stochastic differential equations are solved by the use of the classical Euler-Maruyama method. In this paper, the influence of anisotropic stromal extracellular matrix in pancreatic tumor islets on T-lymphocytes migration in different immune systems is investigated. As a result, tumor peripheral stromal extracellular matrix impedes the immune response of T-lymphocytes through changing direction of their migration.

Emergence and migration of trunk neural crest cells in a snake, the California Kingsnake (Lampropeltis getula californiae)

PubMed Central

2010-01-01

Background The neural crest is a group of multipotent cells that emerges after an epithelial-to-mesenchymal transition from the dorsal neural tube early during development. These cells then migrate throughout the embryo, giving rise to a wide variety derivatives including the peripheral nervous system, craniofacial skeleton, pigment cells, and endocrine organs. While much is known about neural crest cells in mammals, birds, amphibians and fish, relatively little is known about their development in non-avian reptiles like snakes and lizards. Results In this study, we show for the first time ever trunk neural crest migration in a snake by labeling it with DiI and immunofluorescence. As in birds and mammals, we find that early migrating trunk neural crest cells use both a ventromedial pathway and an inter-somitic pathway in the snake. However, unlike birds and mammals, we also observed large numbers of late migrating neural crest cells utilizing the inter-somitic pathway in snake. Conclusions We found that while trunk neural crest migration in snakes is very similar to that of other amniotes, the inter-somitic pathway is used more extensively by late-migrating trunk neural crest cells in snake. PMID:20482793

Emergence and migration of trunk neural crest cells in a snake, the California Kingsnake (Lampropeltis getula californiae).

PubMed

Reyes, Michelle; Zandberg, Katrina; Desmawati, Iska; de Bellard, Maria E

2010-05-18

The neural crest is a group of multipotent cells that emerges after an epithelial-to-mesenchymal transition from the dorsal neural tube early during development. These cells then migrate throughout the embryo, giving rise to a wide variety derivatives including the peripheral nervous system, craniofacial skeleton, pigment cells, and endocrine organs. While much is known about neural crest cells in mammals, birds, amphibians and fish, relatively little is known about their development in non-avian reptiles like snakes and lizards. In this study, we show for the first time ever trunk neural crest migration in a snake by labeling it with DiI and immunofluorescence. As in birds and mammals, we find that early migrating trunk neural crest cells use both a ventromedial pathway and an inter-somitic pathway in the snake. However, unlike birds and mammals, we also observed large numbers of late migrating neural crest cells utilizing the inter-somitic pathway in snake. We found that while trunk neural crest migration in snakes is very similar to that of other amniotes, the inter-somitic pathway is used more extensively by late-migrating trunk neural crest cells in snake.

SOX15 regulates proliferation and migration of endometrial cancer cells.

PubMed

Rui, Xiaohui; Xu, Yun; Jiang, Xiping; Guo, Caixia; Jiang, Jingting

2017-10-31

The study aimed to investigate the effects of Sry-like high mobility group box 15 ( SOX15 ) on proliferation and migration of endometrial cancer (EC) cells. Immunohistochemistry (IHC) was applied to determine the expression of SOX15 in EC tissues and adjacent tissues. We used cell transfection method to construct the HEC-1-A and Ishikawa cell lines with stable overexpression and low expression SOX15 Reverse-transcription quantitative real-time PCR (RT-qPCR) and Western blot were performed to examine expression of SOX15 mRNA and SOX15 protein, respectively. By conducting a series of cell proliferation assay and migration assay, we analyzed the influence of SOX15 overexpression or low expression on EC cell proliferation and migration. The expression of SOX15 mRNA and protein in EC tissues was significantly lower than that in adjacent tissues. After lentivirus-transfecting SOX15 , the expression level of SOX15 mRNA and protein was significantly increased in cells of SOX15 group, and decreased in sh- SOX15 group. Overexpression of SOX15 could suppress cell proliferation, while down-regulation of SOX15 increased cell proliferation. Flow cytometry results indicated that overexpression of SOX15 induced the ratio of cell-cycle arrest in G 1 stage. In addition, Transwell migration assay results showed that SOX15 overexpression significantly inhibited cell migration, and also down-regulation of SOX15 promoted the migration. As a whole, SOX15 could regulate the proliferation and migration of EC cells and up- regulation of SOX15 could be valuable for EC treatment. © 2017 The Author(s).

Steering cell migration by alternating blebs and actin-rich protrusions.

PubMed

Diz-Muñoz, Alba; Romanczuk, Pawel; Yu, Weimiao; Bergert, Martin; Ivanovitch, Kenzo; Salbreux, Guillaume; Heisenberg, Carl-Philipp; Paluch, Ewa K

2016-09-02

High directional persistence is often assumed to enhance the efficiency of chemotactic migration. Yet, cells in vivo usually display meandering trajectories with relatively low directional persistence, and the control and function of directional persistence during cell migration in three-dimensional environments are poorly understood. Here, we use mesendoderm progenitors migrating during zebrafish gastrulation as a model system to investigate the control of directional persistence during migration in vivo. We show that progenitor cells alternate persistent run phases with tumble phases that result in cell reorientation. Runs are characterized by the formation of directed actin-rich protrusions and tumbles by enhanced blebbing. Increasing the proportion of actin-rich protrusions or blebs leads to longer or shorter run phases, respectively. Importantly, both reducing and increasing run phases result in larger spatial dispersion of the cells, indicative of reduced migration precision. A physical model quantitatively recapitulating the migratory behavior of mesendoderm progenitors indicates that the ratio of tumbling to run times, and thus the specific degree of directional persistence of migration, are critical for optimizing migration precision. Together, our experiments and model provide mechanistic insight into the control of migration directionality for cells moving in three-dimensional environments that combine different protrusion types, whereby the proportion of blebs to actin-rich protrusions determines the directional persistence and precision of movement by regulating the ratio of tumbling to run times.

Effects of direct current electric fields on lung cancer cell electrotaxis in a PMMA-based microfluidic device.

PubMed

Li, Yaping; Xu, Tao; Chen, Xiaomei; Lin, Shin; Cho, Michael; Sun, Dong; Yang, Mengsu

2017-03-01

Tumor metastasis is the primary cause of cancer death. Numerous studies have demonstrated the electrotactic responses of various cancer cell types, and suggested its potential implications in metastasis. In this study, we used a microfluidic device to emulate endogenous direct current electric field (dcEF) environment, and studied the electrotactic migration of non-small cell lung cancer cell lines (H460, HCC827, H1299, and H1975) and the underlying mechanisms. These cell lines exhibited greatly different response in applied dcEFs (2-6 V/cm). While H460 cells (large cell carcinoma) showed slight migration toward cathode, H1299 cells (large cell carcinoma) showed increased motility and dcEF-dependent anodal migration with cell reorientation. H1975 cells (adenocarcinoma) showed dcEF-dependent cathodal migration with increased motility, and HCC827 cells (adenocarcinoma) responded positively in migration speed and reorientation but minimally in migrating directions to dcEF. Activation of MAPK and PI3K signaling pathways was found to be associated with the realignment and directed migration of lung cancer cells. In addition, both Ca 2+ influx through activated stretch-activated calcium channels (SACCs) (but not voltage-gated calcium channels, VGCCs) and Ca 2+ release from intracellular storage were involved in lung cancer cell electrotactic responses. The results demonstrated that the microfluidic device provided a stable and controllable microenvironment for cell electrotaxis study, and revealed that the electrotactic responses of lung cancer cells were heterogeneous and cell-type dependent, and multiple signals contributed to lung cancer cells electrotaxis.

Design of a high-throughput human neural crest cell migration assay to indicate potential developmental toxicants.

PubMed

Nyffeler, Johanna; Karreman, Christiaan; Leisner, Heidrun; Kim, Yong Jun; Lee, Gabsang; Waldmann, Tanja; Leist, Marcel

2017-01-01

Migration of neural crest cells (NCCs) is one of the pivotal processes of human fetal development. Malformations arise if NCC migration and differentiation are impaired genetically or by toxicants. In the currently available test systems for migration inhibition of NCC (MINC), the manual generation of a cell-free space results in extreme operator dependencies, and limits throughput. Here a new test format was established. The assay avoids scratching by plating cells around a commercially available circular stopper. Removal of the stopper barrier after cell attachment initiates migration. This microwell-based circular migration zone NCC function assay (cMINC) was further optimized for toxicological testing of human pluripotent stem cell (hPSC)-derived NCCs. The challenge of obtaining data on viability and migration by automated image processing was addressed by developing a freeware. Data on cell proliferation were obtained by labelling replicating cells, and by careful assessment of cell viability for each experimental sample. The role of cell proliferation as an experimental confounder was tested experimentally by performing the cMINC in the presence of the proliferation-inhibiting drug cytosine arabinoside (AraC), and by a careful evaluation of mitotic events over time. Data from these studies led to an adaptation of the test protocol, so that toxicant exposure was limited to 24 h. Under these conditions, a prediction model was developed that allows classification of toxicants as either inactive, leading to unspecific cytotoxicity, or specifically inhibiting NC migration at non-cytotoxic concentrations.

Quantitative analysis of eosinophil chemotaxis tracked using a novel optical device -- TAXIScan.

PubMed

Nitta, Nao; Tsuchiya, Tomoko; Yamauchi, Akira; Tamatani, Takuya; Kanegasaki, Shiro

2007-03-30

We have reported previously the development of an optically accessible, horizontal chemotaxis apparatus, in which migration of cells in the channel from a start line can be traced with time-lapse intervals using a CCD camera (JIM 282, 1-11, 2003). To obtain statistical data of migrating cells, we have developed quantitative methods to calculate various parameters in the process of chemotaxis, employing human eosinophil and CXCL12 as a model cell and a model chemoattractant, respectively. Median values of velocity and directionality of each cell within an experimental period could be calculated from the migratory pathway data obtained from time-lapse images and the data were expressed as Velocity-Directionality (VD) plot. This plot is useful for quantitatively analyzing multiple migrating cells exposed to a certain chemoattractant, and can distinguish chemotaxis from random migration. Moreover precise observation of cell migration revealed that each cell had a different lag period before starting chemotaxis, indicating variation in cell sensitivity to the chemoattractant. Thus lag time of each cell before migration, and time course of increment of the migrating cell ratio at the early stages could be calculated. We also graphed decrement of still moving cell ratio at the later stages by calculating the duration time of cell migration of each cell. These graphs could distinguish different motion patterns of chemotaxis of eosinophils, in response to a range of chemoattractants; PGD(2), fMLP, CCL3, CCL5 and CXCL12. Finally, we compared parameters of eosinophils from normal volunteers, allergy patients and asthma patients and found significant difference in response to PGD(2). The quantitative methods described here could be applicable to image data obtained with any combination of cells and chemoattractants and useful not only for basic studies of chemotaxis but also for diagnosis and for drug screening.

Autologous adipose tissue-derived stromal cells for treatment of spinal cord injury.

PubMed

Kang, Soo-Kyung; Shin, Myung-Joo; Jung, Jin Sup; Kim, Yong Geun; Kim, Cheul-Hong

2006-08-01

Isolated rat adipose tissue-derived stromal cells (rATSCs) contain pluripotent cells that can be differentiated into a variety of cell lineages, including neural cells. Recent work has shown that ATSCs can make neurosphere-like clumps and differentiate into neuron-like cells expressing neuronal markers, but their therapeutic effect is unclear. Here we report that intravenous infusion of oligodendrocyte precursor cells (OPCs) derived from rATSC autograft cells sources improve motor function in rat models of spinal cord injury (SCI). After 4-5 weeks, transplanted rATSC-OPC cells survived and migrated into the injured region of SCI very efficiently (30-35%) and migrated cells were partially differentiated into neurons and oligodendrocyte. Also, we found some of the engrafted OPCs migrated and integrated in the kidney, brain, lung, and liver through the intravenous system. Behavioral analysis revealed the locomotor functions of OPC-autografted SCI rats were significantly restored. Efficient migration of intravenously engrafted rATSC-OPCs cells into SCI lesion suggests that SCI-induced chemotaxic factors facilitate migration of rATSC-OPCs. Here, we verified that engrafted rATSCs and SCI-induced chemotaxic factors indeed play an important role in proliferation, migration, and differentiation of endogeneous spinal cord-derived neural progenitor cells in the injured region. In transplantation paradigms, the interaction between engrafted rATSC-OPCs and endogeneous spinal cord-derived neuronal progenitor cells will be important in promoting healing through fate decisions, resulting in coordinated induction of cell migration and differentiation.

DAN (NBL1) promotes collective neural crest migration by restraining uncontrolled invasion.

PubMed

McLennan, Rebecca; Bailey, Caleb M; Schumacher, Linus J; Teddy, Jessica M; Morrison, Jason A; Kasemeier-Kulesa, Jennifer C; Wolfe, Lauren A; Gogol, Madeline M; Baker, Ruth E; Maini, Philip K; Kulesa, Paul M

2017-10-02

Neural crest cells are both highly migratory and significant to vertebrate organogenesis. However, the signals that regulate neural crest cell migration remain unclear. In this study, we test the function of differential screening-selected gene aberrant in neuroblastoma (DAN), a bone morphogenetic protein (BMP) antagonist we detected by analysis of the chick cranial mesoderm. Our analysis shows that, before neural crest cell exit from the hindbrain, DAN is expressed in the mesoderm, and then it becomes absent along cell migratory pathways. Cranial neural crest and metastatic melanoma cells avoid DAN protein stripes in vitro. Addition of DAN reduces the speed of migrating cells in vivo and in vitro, respectively. In vivo loss of function of DAN results in enhanced neural crest cell migration by increasing speed and directionality. Computer model simulations support the hypothesis that DAN restrains cell migration by regulating cell speed. Collectively, our results identify DAN as a novel factor that inhibits uncontrolled neural crest and metastatic melanoma invasion and promotes collective migration in a manner consistent with the inhibition of BMP signaling. © 2017 McLennan et al.

DAN (NBL1) promotes collective neural crest migration by restraining uncontrolled invasion

PubMed Central

McLennan, Rebecca; Bailey, Caleb M.; Schumacher, Linus J.; Teddy, Jessica M.; Morrison, Jason A.; Kasemeier-Kulesa, Jennifer C.; Wolfe, Lauren A.; Gogol, Madeline M.; Baker, Ruth E.; Maini, Philip K.

2017-01-01

Neural crest cells are both highly migratory and significant to vertebrate organogenesis. However, the signals that regulate neural crest cell migration remain unclear. In this study, we test the function of differential screening-selected gene aberrant in neuroblastoma (DAN), a bone morphogenetic protein (BMP) antagonist we detected by analysis of the chick cranial mesoderm. Our analysis shows that, before neural crest cell exit from the hindbrain, DAN is expressed in the mesoderm, and then it becomes absent along cell migratory pathways. Cranial neural crest and metastatic melanoma cells avoid DAN protein stripes in vitro. Addition of DAN reduces the speed of migrating cells in vivo and in vitro, respectively. In vivo loss of function of DAN results in enhanced neural crest cell migration by increasing speed and directionality. Computer model simulations support the hypothesis that DAN restrains cell migration by regulating cell speed. Collectively, our results identify DAN as a novel factor that inhibits uncontrolled neural crest and metastatic melanoma invasion and promotes collective migration in a manner consistent with the inhibition of BMP signaling. PMID:28811280

In Vitro Propagation and Branching Morphogenesis from Single Ureteric Bud Cells.

PubMed

Yuri, Shunsuke; Nishikawa, Masaki; Yanagawa, Naomi; Jo, Oak D; Yanagawa, Norimoto

2017-02-14

A method to maintain and rebuild ureteric bud (UB)-like structures from UB cells in vitro could provide a useful tool for kidney regeneration. We aimed in our present study to establish a serum-free culture system that enables the expansion of UB progenitor cells, i.e., UB tip cells, and reconstruction of UB-like structures. We found that fibroblast growth factors or retinoic acid (RA) was sufficient for the survival of UB cells in serum-free condition, while the proliferation and maintenance of UB tip cells required glial cell-derived neurotrophic factor together with signaling from either WNT-β-catenin pathway or RA. The activation of WNT-β-catenin signaling in UB cells by endogenous WNT proteins required R-spondins. Together with Rho kinase inhibitor, our culture system facilitated the expansion of UB tip cells to form UB-like structures from dispersed single cells. The UB-like structures thus formed retained the original UB characteristics and integrated into the native embryonic kidneys. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Mechano-growth factor induces migration of rat mesenchymal stem cells by altering its mechanical properties and activating ERK pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jiamin; Wu, Kewen; Lin, Feng

2013-11-08

Highlights: •MGF induced the migration of rat MSC in a concentration-dependent manner. •MGF enhanced the mechanical properties of rMSC in inducing its migration. •MGF activated the ERK 1/2 signaling pathway of rMSC in inducing its migration. •rMSC mechanics may synergy with ERK 1/2 pathway in MGF-induced rMSC migration. -- Abstract: Mechano-growth factor (MGF) generated by cells in response to mechanical stimulation has been identified as a mechano effector molecule, playing a key role in regulating mesenchymal stem cell (MSC) function, including proliferation and migration. However, the mechanism(s) underlying how MGF-induced MSC migration occurs is still unclear. In the present study,more » MGF motivated migration of rat MSCs (rMSCs) in a concentration-dependent manner and optimal concentration of MGF at 50 ng/mL (defined as MGF treatment in this paper) was demonstrated. Notably, enhancement of mechanical properties that is pertinent to cell migration, such as cell traction force and cell stiffness were found to respond to MGF treatment. Furthermore, MGF increased phosphorylation of extracellular signal-regulated kinase (ERK), ERK inhibitor (i.e., PD98059) suppressed ERK phosphorylation, and abolished MGF-induced rMSC migration were found, demonstrating that ERK is involved molecule for MGF-induced rMSC migration. These in vitro evidences of MGF-induced rMSC migration and its direct link to altering rMSC mechanics and activating the ERK pathway, uncover the underlying biomechanical and biological mechanisms of MGF-induced rMSC migration, which may help find MGF-based application of MSC in clinical therapeutics.« less

Characterization of size-dependent mechanical properties of tip-growing cells using a lab-on-chip device.

PubMed

Hu, Chengzhi; Munglani, Gautam; Vogler, Hannes; Ndinyanka Fabrice, Tohnyui; Shamsudhin, Naveen; Wittel, Falk K; Ringli, Christoph; Grossniklaus, Ueli; Herrmann, Hans J; Nelson, Bradley J

2016-12-20

Quantification of mechanical properties of tissues, living cells, and cellular components is crucial for the modeling of plant developmental processes such as mechanotransduction. Pollen tubes are tip-growing cells that provide an ideal system to study the mechanical properties at the single cell level. In this article, a lab-on-a-chip (LOC) device is developed to quantitatively measure the biomechanical properties of lily (Lilium longiflorum) pollen tubes. A single pollen tube is fixed inside the microfluidic chip at a specific orientation and subjected to compression by a soft membrane. By comparing the deformation of the pollen tube at a given external load (compressibility) and the effect of turgor pressure on the tube diameter (stretch ratio) with finite element modeling, its mechanical properties are determined. The turgor pressure and wall stiffness of the pollen tubes are found to decrease considerably with increasing initial diameter of the pollen tubes. This observation supports the hypothesis that tip-growth is regulated by a delicate balance between turgor pressure and wall stiffness. The LOC device is modular and adaptable to a variety of cells that exhibit tip-growth, allowing for the straightforward measurement of mechanical properties.

Co-culture with Sertoli cells promotes proliferation and migration of umbilical cord mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fenxi, E-mail: fxzhang0824@gmail.com; Hong, Yan; Liang, Wenmei

Highlights: Black-Right-Pointing-Pointer Co-culture of Sertoli cells (SCs) with human umbilical cord mesenchymal stem cells (UCMSCs). Black-Right-Pointing-Pointer Presence of SCs dramatically increased proliferation and migration of UCMSCs. Black-Right-Pointing-Pointer Presence of SCs stimulated expression of Mdm2, Akt, CDC2, Cyclin D, CXCR4, MAPKs. -- Abstract: Human umbilical cord mesenchymal stem cells (hUCMSCs) have been recently used in transplant therapy. The proliferation and migration of MSCs are the determinants of the efficiency of MSC transplant therapy. Sertoli cells are a kind of 'nurse' cells that support the development of sperm cells. Recent studies show that Sertoli cells promote proliferation of endothelial cells and neuralmore » stem cells in co-culture. We hypothesized that co-culture of UCMSCs with Sertoli cells may also promote proliferation and migration of UCMSCs. To examine this hypothesis, we isolated UCMSCs from human cords and Sertoli cells from mouse testes, and co-cultured them using a Transwell system. We found that UCMSCs exhibited strong proliferation ability and potential to differentiate to other cell lineages such as osteocytes and adipocytes. The presence of Sertoli cells in co-culture significantly enhanced the proliferation and migration potential of UCMSCs (P < 0.01). Moreover, these phenotypic changes were accompanied with upregulation of multiple genes involved in cell proliferation and migration including phospho-Akt, Mdm2, phospho-CDC2, Cyclin D1, Cyclin D3 as well as CXCR4, phospho-p44 MAPK and phospho-p38 MAPK. These findings indicate that Sertoli cells boost UCMSC proliferation and migration potential.« less

Autonomy and Non-autonomy of Angiogenic Cell Movements Revealed by Experiment-Driven Mathematical Modeling.

PubMed

Sugihara, Kei; Nishiyama, Koichi; Fukuhara, Shigetomo; Uemura, Akiyoshi; Arima, Satoshi; Kobayashi, Ryo; Köhn-Luque, Alvaro; Mochizuki, Naoki; Suda, Toshio; Ogawa, Hisao; Kurihara, Hiroki

2015-12-01

Angiogenesis is a multicellular phenomenon driven by morphogenetic cell movements. We recently reported morphogenetic vascular endothelial cell (EC) behaviors to be dynamic and complex. However, the principal mechanisms orchestrating individual EC movements in angiogenic morphogenesis remain largely unknown. Here we present an experiment-driven mathematical model that enables us to systematically dissect cellular mechanisms in branch elongation. We found that cell-autonomous and coordinated actions governed these multicellular behaviors, and a cell-autonomous process sufficiently illustrated essential features of the morphogenetic EC dynamics at both the single-cell and cell-population levels. Through refining our model and experimental verification, we further identified a coordinated mode of tip EC behaviors regulated via a spatial relationship between tip and follower ECs, which facilitates the forward motility of tip ECs. These findings provide insights that enhance our mechanistic understanding of not only angiogenic morphogenesis, but also other types of multicellular phenomenon. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Hybrid mechanosensing system to generate the polarity needed for migration in fish keratocytes

PubMed Central

Okimura, Chika; Iwadate, Yoshiaki

2016-01-01

ABSTRACT Crawling cells can generate polarity for migration in response to forces applied from the substratum. Such reaction varies according to cell type: there are both fast- and slow-crawling cells. In response to periodic stretching of the elastic substratum, the intracellular stress fibers in slow-crawling cells, such as fibroblasts, rearrange themselves perpendicular to the direction of stretching, with the result that the shape of the cells extends in that direction; whereas fast-crawling cells, such as neutrophil-like differentiated HL-60 cells and Dictyostelium cells, which have no stress fibers, migrate perpendicular to the stretching direction. Fish epidermal keratocytes are another type of fast-crawling cell. However, they have stress fibers in the cell body, which gives them a typical slow-crawling cell structure. In response to periodic stretching of the elastic substratum, intact keratocytes rearrange their stress fibers perpendicular to the direction of stretching in the same way as fibroblasts and migrate parallel to the stretching direction, while blebbistatin-treated stress fiber-less keratocytes migrate perpendicular to the stretching direction, in the same way as seen in HL-60 cells and Dictyostelium cells. Our results indicate that keratocytes have a hybrid mechanosensing system that comprises elements of both fast- and slow-crawling cells, to generate the polarity needed for migration. PMID:27124267

Force Dependent Internalization of Magnetic Nanoparticles Results in Highly Loaded Endothelial Cells for Use as Potential Therapy Delivery Vectors

PubMed Central

MacDonald, Cristin; Barbee, Kenneth

2015-01-01

Purpose To investigate the kinetics, mechanism and extent of MNP loading into endothelial cells and the effect of this loading on cell function. Methods MNP uptake was examined under field on/off conditions, utilizing varying magnetite concentration MNPs. MNP-loaded cell viability and functional integrity was assessed using metabolic respiration, cell proliferation and migration assays. Results MNP uptake in endothelial cells significantly increased under the influence of a magnetic field versus non-magnetic conditions. Larger magnetite density of the MNPs led to a higher MNP internalization by cells under application of a magnetic field without compromising cellular respiration activity. Two-dimensional migration assays at no field showed that higher magnetite loading resulted in greater cell migration rates. In a three-dimensional migration assay under magnetic field, the migration rate of MNP-loaded cells was more than twice that of unloaded cells and was comparable to migration stimulated by a serum gradient. Conclusions Our results suggest that endothelial cell uptake of MNPs is a force dependent process. The in vitro assays determined that cell health is not adversely affected by high MNP loadings, allowing these highly magnetically responsive cells to be potentially beneficial therapy (gene, drug or cell) delivery systems. PMID:22234617

The role of backward cell migration in two-hit mutants' production in the stem cell niche.

PubMed

Bollas, Audrey; Shahriyari, Leili

2017-01-01

It has been discovered that there are two stem cell groups in the intestinal crypts: central stem cells (CeSCs), which are at the very bottom of the crypt, and border stem cells (BSCs), which are located between CeSCs and transit amplifying cells (TAs). Moreover, backward cell migration from BSCs to CeSCs has been observed. Recently, a bi-compartmental stochastic model, which includes CeSCs and BSCs, has been developed to investigate the probability of two-hit mutant production in the stem cell niche. In this project, we improve this stochastic model by adding the probability of backward cell migration to the model. The model suggests that the probability of two-hit mutant production increases when the frequency of backward cell migration increases. Furthermore, a small non-zero probability of backward cell migration leads to the largest range of optimal values for the frequency of symmetric divisions and the portion of divisions at each stem cell compartment in terms of delaying 2-hit mutant production. Moreover, the probability of two-hit mutant production is more sensitive to the probability of symmetric divisions than to the rate of backward cell migrations. The highest probability of two-hit mutant production corresponds to the case when all stem cell's divisions are asymmetric.

Tropomyosin isoform Tpm2.1 regulates collective and amoeboid cell migration and cell aggregation in breast epithelial cells.

PubMed

Shin, HyeRim; Kim, Dayoung; Helfman, David M

2017-11-10

Metastasis dissemination is the result of various processes including cell migration and cell aggregation. These processes involve alterations in the expression and organization of cytoskeletal and adhesion proteins in tumor cells. Alterations in actin filaments and their binding partners are known to be key players in metastasis. Downregulation of specific tropomyosin (Tpm) isoforms is a common characteristic of transformed cells. In this study, we examined the role of Tpm2.1 in non-transformed MCF10A breast epithelial cells in cell migration and cell aggregation, because this isoform is downregulated in primary and metastatic breast cancer as well as various breast cancer cell lines. Downregulation of Tpm2.1 using siRNA or shRNA resulted in retardation of collective cell migration but increase in single cell migration and invasion. Loss of Tpm2.1 is associated with enhanced actomyosin contractility and increased expression of E-cadherin and β-catenin. Furthermore, inhibition of Rho-associated kinase (ROCK) recovered collective cell migration in Tpm2.1-silenced cells. We also found that Tpm2.1-silenced cells formed more compacted spheroids and exhibited faster cell motility when spheroids were re-plated on 2D surfaces coated with fibronectin and collagen. When Tpm2.1 was downregulated, we observed a decrease in the level of AXL receptor tyrosine kinase, which may explain the increased levels of E-cadherin and β-catenin. These studies demonstrate that Tpm2.1 functions as an important regulator of cell migration and cell aggregation in breast epithelial cells. These findings suggest that downregulation of Tpm2.1 may play a critical role during tumor progression by facilitating the metastatic potential of tumor cells.

Contact guidance is cell cycle-dependent.

PubMed

Pourfarhangi, Kamyar Esmaeili; De La Hoz, Edgar Cardenas; Cohen, Andrew R; Gligorijevic, Bojana

2018-09-01

Cancer cell migration is essential for metastasis, during which cancer cells move through the tumor and reach the blood vessels. In vivo , cancer cells are exposed to contact guidance and chemotactic cues. Depending on the strength of such cues, cells will migrate in a random or directed manner. While similar cues may also stimulate cell proliferation, it is not clear whether cell cycle progression affects migration of cancer cells and whether this effect is different in random versus directed migration. In this study, we tested the effect of cell cycle progression on contact guided migration in 2D and 3D environments, in the breast carcinoma cell line, FUCCI-MDA-MB-231. The results were quantified from live cell microscopy images using the open source lineage editing and validation image analysis tools (LEVER). In 2D, cells were placed inside 10 μ m-wide microchannels to stimulate contact guidance, with or without an additional chemotactic gradient of the soluble epidermal growth factor. In 3D, contact guidance was modeled by aligned collagen fibers. In both 2D and 3D, contact guidance was cell cycle-dependent, while the addition of the chemo-attractant gradient in 2D increased cell velocity and persistence in directionally migrating cells, regardless of their cell cycle phases. In both 2D and 3D contact guidance, cells in the G1 phase of the cell cycle outperformed cells in the S/G2 phase in terms of migration persistence and instantaneous velocity. These data suggest that in the presence of contact guidance cues in vivo , breast carcinoma cells in the G1 phase of the cell cycle may be more efficient in reaching the neighboring vasculature.

Low-level stretching accelerates cell migration into a gap.

PubMed

Toume, Samer; Gefen, Amit; Weihs, Daphne

2017-08-01

We observed that radially stretching cell monolayers at a low level (3%) increases the rate at which they migrate to close a gap formed by in vitro injury. Wound healing has been shown to accelerate in vivo when deformations are topically applied, for example, by negative pressure wound therapy. However, the direct effect of deformations on cell migration during gap closure is still unknown. Thus, we have evaluated the effect of radially applied, sustained (static) tensile strain on the kinematics of en mass cell migration. Monolayers of murine fibroblasts were cultured on stretchable, linear-elastic substrates that were subjected to different tensile strains, using a custom-designed three-dimensionally printed stretching apparatus. Immediately following stretching, the monolayer was 'wounded' at its centre, and cell migration during gap closure was monitored and quantitatively evaluated. We observed a significant increase in normalised migration rates and a reduction of gap closure time with 3% stretching, relative to unstretched controls or 6% stretch. Interestingly, the initial gap area was linearly correlated with the maximum migration rate, especially when stretching was applied. Therefore, small deformations applied to cell monolayers during gap closure enhance en mass cell migration associated with wound healing and can be used to fine-tune treatment protocols. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Leptin promotes human endometriotic cell migration and invasion by up-regulating MMP-2 through the JAK2/STAT3 signaling pathway.

PubMed

Ahn, Ji-Hye; Choi, Youn Seok; Choi, Jung-Hye

2015-10-01

Despite evidence that leptin may play a role in the pathogenesis of endometriosis, the specific function of leptin in the migration and invasion of endometriotic cells is not well characterized. In this study, we investigated the effect of leptin on the migration, invasion and matrix metalloproteinase (MMP) expression levels of human endometriotic cells. We found that leptin stimulated the migration and invasion of endometriotic cells (11Z, 12Z and 22B) in a dose-dependent manner. Leptin receptor (ObR) siRNA significantly inhibited the migration and invasion induced by leptin in 11Z and 12Z cells. Leptin-induced migration and invasion were significantly attenuated by pretreatment with SB-3CT, a specific gelatinase (MMP-2 and MMP-9) inhibitor. In addition, leptin-induced increases in the mRNA and protein expression and enzyme activity of MMP-2 in 11Z and 12Z cells. Selectively inhibiting MMP-2 using siRNA and an inhibitor (GM6003), impaired the ability of leptin to stimulate the migration and invasion of endometriotic cells, suggesting that MMP-2 plays an essential role in leptin-induced migration and invasion. Janus Kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) inhibitor (AG490) significantly inhibited the migration, invasion and MMP-2 expression induced by leptin in endometriotic cells. Furthermore, the Extracellular signal-Regulated Kinase inhibitor PD98059 neutralized the migration and invasion promoting effects of leptin. Taken together, these results suggest that leptin may contribute to the migration and invasion abilities of endometriotic cells via the up-regulation of MMP-2 through an ObR-dependent JAK2/STAT3 signaling pathway. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Phosphorylation of Tip60 by GSK-3 determines the induction of PUMA and apoptosis by p53

PubMed Central

Charvet, Céline; Wissler, Manuela; Brauns-Schubert, Prisca; Wang, Shang-Jui; Tang, Yi; Sigloch, Florian C.; Mellert, Hestia; Brandenburg, Martin; Lindner, Silke E.; Breit, Bernhard; Green, Douglas R.; McMahon, Steven B.; Borner, Christoph; Gu, Wei; Maurer, Ulrich

2011-01-01

Summary Activation of p53 by DNA damage results in either cell cycle arrest, allowing DNA repair and cell survival, or induction of apoptosis. As these opposite outcomes are both mediated by p53 stabilization, additional mechanisms to determine this decision must exist. Here we show that glycogen synthase kinase-3 (GSK-3) is required for the p53-mediated induction of the pro-apoptotic BH3 only-protein PUMA, an essential mediator of p53-induced apoptosis. Inhibition of GSK-3 protected from cell death induced by DNA damage and promoted increased long-term cell survival. We demonstrate that GSK-3 phosphorylates serine 86 of the p53-acetyltransferase Tip60. A Tip60S86A mutant was less active to induce p53 K120 acetylation, Histone 4 acetylation and expression of PUMA. Our data suggest that GSK-3 mediated Tip60S86-phosphorylation provides a link between PI3K signaling and the choice for or against apoptosis induction by p53. PMID:21658600

Effects of Mg{sup 2+}, Co{sup 2+}, and Hg{sup 2+} on the nucleus and nucleolus in root tip cells of allium cepa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D.; Jiang, W.; Wang, W.

Metal toxicity in plants has been known for a long time. Much importance has increasingly been attached to the problems of metal pollution with the development of modern industry and agriculture. If metals in plants are accumulated to a large extent, it might seriously affect them. The cytological effects of cobalt and mercury have been studied in Allium cepa by documentation of c-mitosis. Also, the quantification of chromosome aberration in Vicia faba root-tip cells treated by magnesium sulphate and in Allium cepa by metyl mercury chloride and mercuric chloride has been reported. Cytological research on the poisoning effects of Mg,more » Co and Hg on the nuclei and nucleoli in root-tip cells of plants has hardly been reported. The aim of this study was to determine the effects of different concentrations of magnesium, cobalt and mercury ions on root growth, and on the nuclei and nucleoli of root tip cells of Allium-cepa. 20 refs., 3 figs.« less

Morphoregulatory functions of the RNA-binding motif protein 3 in cell spreading, polarity and migration.

PubMed

Pilotte, J; Kiosses, W; Chan, S W; Makarenkova, H P; Dupont-Versteegden, E; Vanderklish, P W

2018-05-09

RNA-binding proteins are emerging as key regulators of transitions in cell morphology. The RNA-binding motif protein 3 (RBM3) is a cold-inducible RNA-binding protein with broadly relevant roles in cellular protection, and putative functions in cancer and development. Several findings suggest that RBM3 has morphoregulatory functions germane to its roles in these contexts. For example, RBM3 helps maintain the morphological integrity of cell protrusions during cell stress and disease. Moreover, it is highly expressed in migrating neurons of the developing brain and in cancer invadopodia, suggesting roles in migration. We here show that RBM3 regulates cell polarity, spreading and migration. RBM3 was present in spreading initiation centers, filopodia and blebs that formed during cell spreading in cell lines and primary myoblasts. Reducing RBM3 triggered exaggerated spreading, increased RhoA expression, and a loss of polarity that was rescued by Rho kinase inhibition and overexpression of CRMP2. High RBM3 expression enhanced the motility of cells migrating by a mesenchymal mode involving extension of long protrusions, whereas RBM3 knockdown slowed migration, greatly reducing the ability of cells to extend protrusions and impairing multiple processes that require directional migration. These data establish novel functions of RBM3 of potential significance to tissue repair, metastasis and development.

The tip-link antigen, a protein associated with the transduction complex of sensory hair cells, is protocadherin-15.

PubMed

Ahmed, Zubair M; Goodyear, Richard; Riazuddin, Saima; Lagziel, Ayala; Legan, P Kevin; Behra, Martine; Burgess, Shawn M; Lilley, Kathryn S; Wilcox, Edward R; Riazuddin, Sheikh; Griffith, Andrew J; Frolenkov, Gregory I; Belyantseva, Inna A; Richardson, Guy P; Friedman, Thomas B

2006-06-28

Sound and acceleration are detected by hair bundles, mechanosensory structures located at the apical pole of hair cells in the inner ear. The different elements of the hair bundle, the stereocilia and a kinocilium, are interconnected by a variety of link types. One of these links, the tip link, connects the top of a shorter stereocilium with the lateral membrane of an adjacent taller stereocilium and may gate the mechanotransducer channel of the hair cell. Mass spectrometric and Western blot analyses identify the tip-link antigen, a hitherto unidentified antigen specifically associated with the tip and kinocilial links of sensory hair bundles in the inner ear and the ciliary calyx of photoreceptors in the eye, as an avian ortholog of human protocadherin-15, a product of the gene for the deaf/blindness Usher syndrome type 1F/DFNB23 locus. Multiple protocadherin-15 transcripts are shown to be expressed in the mouse inner ear, and these define four major isoform classes, two with entirely novel, previously unidentified cytoplasmic domains. Antibodies to the three cytoplasmic domain-containing isoform classes reveal that each has a different spatiotemporal expression pattern in the developing and mature inner ear. Two isoforms are distributed in a manner compatible for association with the tip-link complex. An isoform located at the tips of stereocilia is sensitive to calcium chelation and proteolysis with subtilisin and reappears at the tips of stereocilia as transduction recovers after the removal of calcium chelators. Protocadherin-15 is therefore associated with the tip-link complex and may be an integral component of this structure and/or required for its formation.

Spontaneous Contractility-Mediated Cortical Flow Generates Cell Migration in Three-Dimensional Environments

PubMed Central

Hawkins, Rhoda J.; Poincloux, Renaud; Bénichou, Olivier; Piel, Matthieu; Chavrier, Philippe; Voituriez, Raphaël

2011-01-01

We present a model of cell motility generated by actomyosin contraction of the cell cortex. We identify, analytically, dynamical instabilities of the cortex and show that they yield steady-state cortical flows, which, in turn, can induce cell migration in three-dimensional environments. This mechanism relies on the regulation of contractility by myosin, whose transport is explicitly taken into account in the model. Theoretical predictions are compared to experimental data of tumor cells migrating in three-dimensional matrigel and suggest that this mechanism could be a general mode of cell migration in three-dimensional environments. PMID:21889440

A novel mechanism of regulating breast cancer cell migration via palmitoylation-dependent alterations in the lipid raft affiliation of CD44.

PubMed

Babina, Irina S; McSherry, Elaine A; Donatello, Simona; Hill, Arnold D K; Hopkins, Ann M

2014-02-10

Most breast cancer-related deaths result from metastasis, a process involving dynamic regulation of tumour cell adhesion and migration. The adhesion protein CD44, a key regulator of cell migration, is enriched in cholesterol-enriched membrane microdomains termed lipid rafts. We recently reported that raft affiliation of CD44 negatively regulates interactions with its migratory binding partner ezrin. Since raft affiliation is regulated by post-translational modifications including palmitoylation, we sought to establish the contribution of CD44 palmitoylation and lipid raft affiliation to cell migration. Recovery of CD44 and its binding partners from raft versus non-raft membrane microdomains was profiled in non-migrating and migrating breast cancer cell lines. Site-directed mutagenesis was used to introduce single or double point mutations into both CD44 palmitoylation sites (Cys286 and Cys295), whereupon the implications for lipid raft recovery, phenotype, ezrin co-precipitation and migratory behaviour was assessed. Finally CD44 palmitoylation status and lipid raft affiliation was assessed in primary cultures from a small panel of breast cancer patients. CD44 raft affiliation was increased during migration of non-invasive breast cell lines, but decreased during migration of highly-invasive breast cells. The latter was paralleled by increased CD44 recovery in non-raft fractions, and exclusive non-raft recovery of its binding partners. Point mutation of CD44 palmitoylation sites reduced CD44 raft affiliation in invasive MDA-MB-231 cells, increased CD44-ezrin co-precipitation and accordingly enhanced cell migration. Expression of palmitoylation-impaired (raft-excluded) CD44 mutants in non-invasive MCF-10a cells was sufficient to reversibly induce the phenotypic appearance of epithelial-to-mesenchymal transition and to increase cell motility. Interestingly, cell migration was associated with temporal reductions in CD44 palmitoylation in wild-type breast cells. Finally, the relevance of these findings is underscored by the fact that levels of palmitoylated CD44 were lower in primary cultures from invasive ductal carcinomas relative to non-tumour tissue, while CD44 co-localisation with a lipid raft marker was less in invasive ductal carcinoma relative to ductal carcinoma in situ cultures. Our results support a novel mechanism whereby CD44 palmitoylation and consequent lipid raft affiliation inversely regulate breast cancer cell migration, and may act as a new therapeutic target in breast cancer metastasis.

A novel functional site of extracellular matrix metalloproteinase inducer (EMMPRIN) that limits the migration of human uterine cervical carcinoma cells.

PubMed

Sato, Takashi; Watanabe, Mami; Hashimoto, Kei; Ota, Tomoko; Akimoto, Noriko; Imada, Keisuke; Nomizu, Motoyoshi; Ito, Akira

2012-01-01

EMMPRIN (extracellular matrix metalloproteinase inducer)/CD147, a membrane-bound glycoprotein with two extracellular loop domains (termed loops I and II), progresses tumor invasion and metastasis by increasing the production of matrix metalloproteinase (MMP) in peritumoral stoma cells. EMMPRIN has also been associated with the control of migration activity in some tumor cells, but little is known about how EMMPRIN regulates tumor cell migration. In the present study, EMMPRIN siRNA suppressed the gene expression and production of EMMPRIN in human uterine cervical carcinoma SKG-II cells. An in vitro scratch wound assay showed enhancement of migration of EMMPRIN-knockdown SKG-II cells. In addition, the SKG-II cell migration was augmented by adding an E. coli-expressed human EMMPRIN mutant with two extracellular loop domains (eEMP-I/II), which bound to the cell surface of SKG-II cells. However, eEMP-I/II suppressed the native EMMPRIN-mediated augmentation of proMMP-1/procollagenase-1 production in a co-culture of the SKG-II cells and human uterine cervical fibroblasts, indicating that the augmentation of SKG-II cell migration resulted from the interference of native EMMPRIN functions by eEMP-I/II on the cell surface. Furthermore, a systematic peptide screening method using nine synthetic EMMPRIN peptides coding the loop I and II domains (termed EM1-9) revealed that EM9 (170HIENLNMEADPGQYR184) facilitated SKG-II cell migration. Moreover, SKG-II cell migration was enhanced by administration of an antibody against EM9, but not EM1 which is a crucial site for the MMP inducible activity of EMMPRIN. Therefore, these results provide novel evidence that EMMPRIN on the cell surface limits the cell migration of human uterine cervical carcinoma cells through 170HIENLNMEADPGQYR184 in the loop II domain. Finally, these results should provide an increased understanding of the functions of EMMPRIN in malignant cervical carcinoma cells, and could contribute to the development of clinical strategies for cervical cancer therapy.

Genotoxicity effects of silver nanoparticles on wheat (Triticum aestivum L.) root tip cells.

PubMed

Abdelsalam, Nader R; Abdel-Megeed, Ahmed; Ali, Hayssam M; Salem, Mohamed Z M; Al-Hayali, Muwafaq F A; Elshikh, Mohamed S

2018-07-15

The distribution and use of nanoparticles have rapidly increased over recent years, but the available knowledge regarding their mode of action, ecological tolerance and biodegradability remains insufficient. Wheat (Triticum aestivum L.) is the most important crop worldwide. In the current study, the effects of silver nanoparticles (AgNPs) obtained from two different sources, namely, green and chemical syntheses, on chromosomal aberrations and cell division were investigated. Wheat root tips were treated with four different AgNP concentrations (10, 20, 40 and 50 ppm) for three different exposure durations (8, 16 and 24 h), and the different concentrations of the nanoparticles were added to the tested grains until the root lengths reached 1.5-2 cm. For each concentration, the mitotic indexes (%) were obtained from an analysis of ~ 2000 cells. The treated root-tip cells exhibited various types of chromosomal aberrations, such as incorrect orientation at metaphase, chromosomal breakage, metaphasic plate distortion, spindle dysfunction, stickiness, aberrant movement at metaphase, fragmentation, scattering, unequal separation, scattering, chromosomal gaps, multipolar anaphase, erosion, and distributed and lagging chromosomes. These results demonstrate that the root tip cells of wheat can readily internalize the AgNPs and that the internalized AgNPs can interfere with the cells' normal function. Copyright © 2018 Elsevier Inc. All rights reserved.

In vivo collective cell migration requires an LPAR2-dependent increase in tissue fluidity

PubMed Central

Kuriyama, Sei; Theveneau, Eric; Benedetto, Alexandre; Parsons, Maddy; Tanaka, Masamitsu; Charras, Guillaume; Kabla, Alexandre

2014-01-01

Collective cell migration (CCM) and epithelial–mesenchymal transition (EMT) are common to cancer and morphogenesis, and are often considered to be mutually exclusive in spite of the fact that many cancer and embryonic cells that have gone through EMT still cooperate to migrate collectively. Here we use neural crest (NC) cells to address the question of how cells that have down-regulated cell–cell adhesions can migrate collectively. NC cell dissociation relies on a qualitative and quantitative change of the cadherin repertoire. We found that the level of cell–cell adhesion is precisely regulated by internalization of N-cadherin downstream of lysophosphatidic acid (LPA) receptor 2. Rather than promoting the generation of single, fully mesenchymal cells, this reduction of membrane N-cadherin only triggers a partial mesenchymal phenotype. This intermediate phenotype is characterized by an increase in tissue fluidity akin to a solid-like–to–fluid-like transition. This change of plasticity allows cells to migrate under physical constraints without abolishing cell cooperation required for collectiveness. PMID:25002680

Modeling and predictions of biphasic mechanosensitive cell migration altered by cell-intrinsic properties and matrix confinement.

PubMed

Pathak, Amit

2018-04-12

Motile cells sense the stiffness of their extracellular matrix (ECM) through adhesions and respond by modulating the generated forces, which in turn lead to varying mechanosensitive migration phenotypes. Through modeling and experiments, cell migration speed is known to vary with matrix stiffness in a biphasic manner, with optimal motility at an intermediate stiffness. Here, we present a two-dimensional cell model defined by nodes and elements, integrated with subcellular modeling components corresponding to mechanotransductive adhesion formation, force generation, protrusions and node displacement. On 2D matrices, our calculations reproduce the classic biphasic dependence of migration speed on matrix stiffness and predict that cell types with higher force-generating ability do not slow down on very stiff matrices, thus disabling the biphasic response. We also predict that cell types defined by lower number of total receptors require stiffer matrices for optimal motility, which also limits the biphasic response. For a cell type with robust biphasic migration on 2D surface, simulations in channel-like confined environments of varying width and height predict faster migration in more confined matrices. Simulations performed in shallower channels predict that the biphasic mechanosensitive cell migration response is more robust on 2D micro-patterns as compared to the channel-like 3D confinement. Thus, variations in the dimensionality of matrix confinement alters the way migratory cells sense and respond to the matrix stiffness. Our calculations reveal new phenotypes of stiffness- and topography-sensitive cell migration that critically depend on both cell-intrinsic and matrix properties. These predictions may inform our understanding of various mechanosensitive modes of cell motility that could enable tumor invasion through topographically heterogeneous microenvironments. © 2018 IOP Publishing Ltd.

Electrochemical Visualization of Intracellular Hydrogen Peroxide at Single Cells.

PubMed

He, Ruiqin; Tang, Huifen; Jiang, Dechen; Chen, Hong-yuan

2016-02-16

In this Letter, the electrochemical visualization of hydrogen peroxide inside one cell was achieved first using a comprehensive Au-luminol-microelectrode and electrochemiluminescence. The capillary with a tip opening of 1-2 μm was filled with the mixture of chitosan and luminol, which was coated with the thin layers of polyvinyl chloride/nitrophenyloctyl ether (PVC/NPOE) and gold as the microelectrode. Upon contact with the aqueous hydrogen peroxide, hydrogen peroxide and luminol in contact with the gold layer were oxidized under the positive potential resulting in luminescence for the imaging. Due to the small diameter of the electrode, the microelectrode tip was inserted into one cell and the bright luminescence observed at the tip confirmed the visualization of intracellular hydrogen peroxide. The further coupling of oxidase on the electrode surface could open the field in the electrochemical imaging of intracellular biomolecules at single cells, which benefited the single cell electrochemical detection.

Hedgehog Is a Positive Regulator of FGF Signalling during Embryonic Tracheal Cell Migration

PubMed Central

Butí, Elisenda; Mesquita, Duarte; Araújo, Sofia J.

2014-01-01

Cell migration is a widespread and complex process that is crucial for morphogenesis and for the underlying invasion and metastasis of human cancers. During migration, cells are steered toward target sites by guidance molecules that induce cell direction and movement through complex intracellular mechanisms. The spatio-temporal regulation of the expression of these guidance molecules is of extreme importance for both normal morphogenesis and human disease. One way to achieve this precise regulation is by combinatorial inputs of different transcription factors. Here we used Drosophila melanogaster mutants with migration defects in the ganglionic branches of the tracheal system to further clarify guidance regulation during cell migration. By studying the cellular consequences of overactivated Hh signalling, using ptc mutants, we found that Hh positively regulates Bnl/FGF levels during embryonic stages. Our results show that Hh modulates cell migration non-autonomously in the tissues surrounding the action of its activity. We further demonstrate that the Hh signalling pathway regulates bnl expression via Stripe (Sr), a zinc-finger transcription factor with homology to the Early Growth Response (EGR) family of vertebrate transcription factors. We propose that Hh modulates embryonic cell migration by participating in the spatio-temporal regulation of bnl expression in a permissive mode. By doing so, we provide a molecular link between the activation of Hh signalling and increased chemotactic responses during cell migration. PMID:24651658

Hedgehog is a positive regulator of FGF signalling during embryonic tracheal cell migration.

PubMed

Butí, Elisenda; Mesquita, Duarte; Araújo, Sofia J

2014-01-01

Cell migration is a widespread and complex process that is crucial for morphogenesis and for the underlying invasion and metastasis of human cancers. During migration, cells are steered toward target sites by guidance molecules that induce cell direction and movement through complex intracellular mechanisms. The spatio-temporal regulation of the expression of these guidance molecules is of extreme importance for both normal morphogenesis and human disease. One way to achieve this precise regulation is by combinatorial inputs of different transcription factors. Here we used Drosophila melanogaster mutants with migration defects in the ganglionic branches of the tracheal system to further clarify guidance regulation during cell migration. By studying the cellular consequences of overactivated Hh signalling, using ptc mutants, we found that Hh positively regulates Bnl/FGF levels during embryonic stages. Our results show that Hh modulates cell migration non-autonomously in the tissues surrounding the action of its activity. We further demonstrate that the Hh signalling pathway regulates bnl expression via Stripe (Sr), a zinc-finger transcription factor with homology to the Early Growth Response (EGR) family of vertebrate transcription factors. We propose that Hh modulates embryonic cell migration by participating in the spatio-temporal regulation of bnl expression in a permissive mode. By doing so, we provide a molecular link between the activation of Hh signalling and increased chemotactic responses during cell migration.

Gas6 induces cancer cell migration and epithelial–mesenchymal transition through upregulation of MAPK and Slug

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Yunhee; Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon; Lee, Mira

2013-04-26

Highlights: •We investigated the molecular mechanisms underlying Gas6-mediated cancer cell migration. •Gas6 treatment and subsequent Axl activation induce cell migration and EMT via upregulation of Slug. •Slug expression mediated by Gas6 is mainly through c-Jun and ATF-2 in an ERK1/2 and JNK-dependent manner. •The Gas6/Axl-Slug axis may be exploited as a target for anti-cancer metastasis therapy. -- Abstract: Binding of Gas6 to Axl (Gas6/Axl axis) alters cellular functions, including migration, invasion, proliferation, and survival. However, the molecular mechanisms underlying Gas6-mediated cell migration remain poorly understood. In this study, we found that Gas6 induced the activation of JNK and ERK1/2 signalingmore » in cancer cells expressing Axl, resulting in the phosphorylation of activator protein-1 (AP-1) transcription factors c-Jun and ATF-2, and induction of Slug. Depletion of c-Jun or ATF-2 by siRNA attenuated the Gas6-induced expression of Slug. Slug expression was required for cell migration and E-cadherin reduction/vimentin induction induced by Gas6. These results suggest that Gas6 induced cell migration via Slug upregulation in JNK- and ERK1/2-dependent mechanisms. These data provide an important insight into the molecular mechanisms mediating Gas6-induced cell migration.« less

S-Fms signalobody enhances myeloid cell growth and migration.

PubMed

Kawahara, Masahiro; Hitomi, Azusa; Nagamune, Teruyuki

2014-07-01

Since receptor tyrosine kinases (RTKs) control various cell fates in many types of cells, mimicry of RTK functions is promising for artificial control of cell fates. We have previously developed single-chain Fv (scFv)/receptor chimeras named signalobodies that can mimic receptor signaling in response to a specific antigen. While the RTK-based signalobodies enabled us to control cell growth and migration, further extension of applicability in another cell type would underlie the impact of the RTK-based signalobodies. In this study, we applied the scFv-c-Fms (S-Fms) signalobody in a murine myeloid progenitor cell line, FDC-P1. S-Fms transduced a fluorescein-conjugated BSA (BSA-FL)-dependent growth signal and activated downstream signaling molecules including MEK, ERK, Akt, and STAT3, which are major constituents of Ras/MAPK, PI3K/Akt, and JAK/STAT signaling pathways. In addition, S-Fms transduced a migration signal as demonstrated by the transwell-based migration assay. Direct real-time observation of the cells further confirmed that FDC/S-Fms cells underwent directional cell migration toward a positive gradient of BSA-FL. These results demonstrated the utility of the S-Fms signalobody for controlling growth and migration of myeloid cells. Further extension of our approach includes economical large-scale production of practically relevant blood cells as well as artificial control of cell migration for tissue regeneration and immune response. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Connecting single cell to collective cell behavior in a unified theoretical framework

NASA Astrophysics Data System (ADS)

George, Mishel; Bullo, Francesco; Campàs, Otger

Collective cell behavior is an essential part of tissue and organ morphogenesis during embryonic development, as well as of various disease processes, such as cancer. In contrast to many in vitro studies of collective cell migration, most cases of in vivo collective cell migration involve rather small groups of cells, with large sheets of migrating cells being less common. The vast majority of theoretical descriptions of collective cell behavior focus on large numbers of cells, but fail to accurately capture the dynamics of small groups of cells. Here we introduce a low-dimensional theoretical description that successfully captures single cell migration, cell collisions, collective dynamics in small groups of cells, and force propagation during sheet expansion, all within a common theoretical framework. Our description is derived from first principles and also includes key phenomenological aspects of cell migration that control the dynamics of traction forces. Among other results, we explain the counter-intuitive observations that pairs of cells repel each other upon collision while they behave in a coordinated manner within larger clusters.

Multiscale Cues Drive Collective Cell Migration

NASA Astrophysics Data System (ADS)

Nam, Ki-Hwan; Kim, Peter; Wood, David K.; Kwon, Sunghoon; Provenzano, Paolo P.; Kim, Deok-Ho

2016-07-01

To investigate complex biophysical relationships driving directed cell migration, we developed a biomimetic platform that allows perturbation of microscale geometric constraints with concomitant nanoscale contact guidance architectures. This permits us to elucidate the influence, and parse out the relative contribution, of multiscale features, and define how these physical inputs are jointly processed with oncogenic signaling. We demonstrate that collective cell migration is profoundly enhanced by the addition of contract guidance cues when not otherwise constrained. However, while nanoscale cues promoted migration in all cases, microscale directed migration cues are dominant as the geometric constraint narrows, a behavior that is well explained by stochastic diffusion anisotropy modeling. Further, oncogene activation (i.e. mutant PIK3CA) resulted in profoundly increased migration where extracellular multiscale directed migration cues and intrinsic signaling synergistically conspire to greatly outperform normal cells or any extracellular guidance cues in isolation.

Androgen-Induced Cell Migration: Role of Androgen Receptor/Filamin A Association

PubMed Central

Castoria, Gabriella; D'Amato, Loredana; Ciociola, Alessandra; Giovannelli, Pia; Giraldi, Tiziana; Sepe, Leandra; Paolella, Giovanni; Barone, Maria Vittoria; Migliaccio, Antimo; Auricchio, Ferdinando

2011-01-01

Background Androgen receptor (AR) controls male morphogenesis, gametogenesis and prostate growth as well as development of prostate cancer. These findings support a role for AR in cell migration and invasiveness. However, the molecular mechanism involved in AR-mediated cell migration still remains elusive. Methodology/Principal Findings Mouse embryo NIH3T3 fibroblasts and highly metastatic human fibrosarcoma HT1080 cells harbor low levels of transcriptionally incompetent AR. We now report that, through extra nuclear action, AR triggers migration of both cell types upon stimulation with physiological concentrations of the androgen R1881. We analyzed the initial events leading to androgen-induced cell migration and observed that challenging NIH3T3 cells with 10 nM R1881 rapidly induces interaction of AR with filamin A (FlnA) at cytoskeleton. AR/FlnA complex recruits integrin beta 1, thus activating its dependent cascade. Silencing of AR, FlnA and integrin beta 1 shows that this ternary complex controls focal adhesion kinase (FAK), paxillin and Rac, thereby driving cell migration. FAK-null fibroblasts migrate poorly and Rac inhibition by EHT impairs motility of androgen-treated NIH3T3 cells. Interestingly, FAK and Rac activation by androgens are independent of each other. Findings in human fibrosarcoma HT1080 cells strengthen the role of Rac in androgen signaling. The Rac inhibitor significantly impairs androgen-induced migration in these cells. A mutant AR, deleted of the sequence interacting with FlnA, fails to mediate FAK activation and paxillin tyrosine phosphorylation in androgen-stimulated cells, further reinforcing the role of AR/FlnA interaction in androgen-mediated motility. Conclusions/Significance The present report, for the first time, indicates that the extra nuclear AR/FlnA/integrin beta 1 complex is the key by which androgen activates signaling leading to cell migration. Assembly of this ternary complex may control organ development and prostate cancer metastasis. PMID:21359179

Cyclic Nucleotide-gated Channel α-3 (CNGA3) Interacts with Stereocilia Tip-Link Cadherin 23 + Exon 68 or Alternatively with Myosin VIIa, Two Proteins Required for Hair Cell Mechanotransduction*

PubMed Central

Selvakumar, Dakshnamurthy; Drescher, Marian J.; Drescher, Dennis G.

2013-01-01

Previously, we obtained evidence for a photoreceptor/olfactory type of CNGA3 transcript in a purified teleost vestibular hair cell preparation with immunolocalization of CNGA3 protein to stereocilia of teleost vestibular and mammalian cochlear hair cells. The carboxyl terminus of highly Ca2+-permeable CNGA3 expressed in the mammalian organ of Corti and saccular hair cells was found to interact with an intracellular domain of microfibril interface-located protein 1 (EMILIN 1), a member of the elastin superfamily, also immunolocalizd to hair cell stereocilia (Selvakumar, D., Drescher, M. J., Dowdall, J. R., Khan, K. M., Hatfield, J. S., Ramakrishnan, N. A., and Drescher, D. G. (2012) Biochem. J. 443, 463–476). Here, we provide evidence for organ of Corti proteins, of Ca2+-dependent binding of the amino terminus of CNGA3 specifically to the carboxyl terminus of stereocilia tip-link protein CDH23 +68 (cadherin 23 with expressed exon 68) by yeast two-hybrid mating and co-transformation protocols, pulldown assays, and surface plasmon resonance analysis. Myosin VIIa, required for adaptation of hair cell mechanotransduction (MET) channel(s), competed with CDH23 +68, with direct Ca2+-dependent binding to the amino terminus of CNGA3. Based upon the premise that hair cell stereocilia tip-link proteins are closely coupled with MET, these results are consistent with the possibility that CNGA3 participates in hair-cell MET. Together with the demonstration of protein-protein interaction between HCN1 and tip-link protein protocadherin 15 CD3 (Ramakrishnan, N. A., Drescher, M. J., Barretto, R. L., Beisel, K. W., Hatfield, J. S., and Drescher, D. G. (2009) J. Biol. Chem. 284, 3227–3238; Ramakrishnan, N. A., Drescher, M. J., Khan, K. M., Hatfield, J. S., and Drescher, D. G. (2012) J. Biol. Chem. 287, 37628–37646), a protein-protein interaction for CNGA3 and a second tip-link protein, CDH23 +68, further suggests possible association of two different channels with a single stereocilia tip link. PMID:23329832

Cyclic nucleotide-gated channel α-3 (CNGA3) interacts with stereocilia tip-link cadherin 23 + exon 68 or alternatively with myosin VIIa, two proteins required for hair cell mechanotransduction.

PubMed

Selvakumar, Dakshnamurthy; Drescher, Marian J; Drescher, Dennis G

2013-03-08

Previously, we obtained evidence for a photoreceptor/olfactory type of CNGA3 transcript in a purified teleost vestibular hair cell preparation with immunolocalization of CNGA3 protein to stereocilia of teleost vestibular and mammalian cochlear hair cells. The carboxyl terminus of highly Ca(2+)-permeable CNGA3 expressed in the mammalian organ of Corti and saccular hair cells was found to interact with an intracellular domain of microfibril interface-located protein 1 (EMILIN 1), a member of the elastin superfamily, also immunolocalizd to hair cell stereocilia (Selvakumar, D., Drescher, M. J., Dowdall, J. R., Khan, K. M., Hatfield, J. S., Ramakrishnan, N. A., and Drescher, D. G. (2012) Biochem. J. 443, 463-476). Here, we provide evidence for organ of Corti proteins, of Ca(2+)-dependent binding of the amino terminus of CNGA3 specifically to the carboxyl terminus of stereocilia tip-link protein CDH23 +68 (cadherin 23 with expressed exon 68) by yeast two-hybrid mating and co-transformation protocols, pulldown assays, and surface plasmon resonance analysis. Myosin VIIa, required for adaptation of hair cell mechanotransduction (MET) channel(s), competed with CDH23 +68, with direct Ca(2+)-dependent binding to the amino terminus of CNGA3. Based upon the premise that hair cell stereocilia tip-link proteins are closely coupled with MET, these results are consistent with the possibility that CNGA3 participates in hair-cell MET. Together with the demonstration of protein-protein interaction between HCN1 and tip-link protein protocadherin 15 CD3 (Ramakrishnan, N. A., Drescher, M. J., Barretto, R. L., Beisel, K. W., Hatfield, J. S., and Drescher, D. G. (2009) J. Biol. Chem. 284, 3227-3238; Ramakrishnan, N. A., Drescher, M. J., Khan, K. M., Hatfield, J. S., and Drescher, D. G. (2012) J. Biol. Chem. 287, 37628-37646), a protein-protein interaction for CNGA3 and a second tip-link protein, CDH23 +68, further suggests possible association of two different channels with a single stereocilia tip link.

Silymarin suppresses the PGE2 -induced cell migration through inhibition of EP2 activation; G protein-dependent PKA-CREB and G protein-independent Src-STAT3 signal pathways.

PubMed

Woo, Seon Min; Min, Kyoung-Jin; Chae, In Gyeong; Chun, Kyung-Soo; Kwon, Taeg Kyu

2015-03-01

Silymarin has been known as a chemopreventive agent, and possesses multiple anti-cancer activities including induction of apoptosis, inhibition of proliferation and growth, and blockade of migration and invasion. However, whether silymarin could inhibit prostaglandin (PG) E2 -induced renal cell carcinoma (RCC) migration and what are the underlying mechanisms are not well elucidated. Here, we found that silymarin markedly inhibited PGE2 -stimulated migration. PGE2 induced G protein-dependent CREB phosphorylation via protein kinase A (PKA) signaling, and PKA inhibitor (H89) inhibited PGE2 -mediated migration. Silymarin reduced PGE2 -induced CREB phosphorylation and CRE-promoter activity. PGE2 also activated G protien-independent signaling pathways (Src and STAT3) and silymarin reduced PGE2 -induced phosphorylation of Src and STAT3. Inhibitor of Src (Saracatinib) markedly reduced PGE2 -mediated migration. We found that EP2, a PGE2 receptor, is involved in PGE2 -mediated cell migration. Down regulation of EP2 by EP2 siRNA and EP2 antagonist (AH6809) reduced PGE2 -inudced migration. In contrast, EP2 agonist (Butaprost) increased cell migration and silymarin effectively reduced butaprost-mediated cell migration. Moreover, PGE2 increased EP2 expression through activation of positive feedback mechanism, and PGE2 -induced EP2 expression, as well as basal EP2 levels, were reduced in silymarin-treated cells. Taken together, our study demonstrates that silymarin inhibited PGE2 -induced cell migration through inhibition of EP2 signaling pathways (G protein dependent PKA-CREB and G protein-independent Src-STAT3). © 2013 Wiley Periodicals, Inc.

Wing-augmentation reduces femoral head cutting out of dynamic hip screw.

PubMed

Chen, Chih-Yu; Huang, Shu-Wei; Sun, Jui-Sheng; Lin, Shin-Yiing; Yu, Chih-Sheng; Pan, Hsu-Pin; Lin, Ping-Hung; Hsieh, Fan-Chun; Tsuang, Yang-Hwei; Lin, Feng-Huei; Yang, Rong-Sen; Cheng, Cheng-Kung

2017-06-01

The dynamic hip screw (DHS) is commonly used in the treatment of femoral intertrochanteric fracture with high satisfactory results. However, post-operative failure does occur and result in poor prognosis. The most common failure is femoral head varus collapse, followed by lag screw cut-out through the femoral head. In this study, a novel-designed DHS with two supplemental horizontal blades was used to improve the fixation stability. In this study, nine convention DHS and 9 Orthopaedic Device Research Center (ODRC) DHSs were tested in this study. Each implant was fixed into cellular polyurethane rigid foam as a surrogate of osteoporotic femoral head. Under biaxial rocking motion, all constructs were loaded to failure point (12mm axial displacement) or up to 20,000 cycles of 1.45kN peak magnitude were achieved, whichever occurred first. The migration kinematics was continuously monitored and recorded. The final tip-to-apex distance, rotational angle and varus deformation were also recorded. The results showed that the ODRC DHS sustained significantly more loading cycles and exhibited less axial migration in comparison to the conventional DHS. The ODRC DHS showed a significantly smaller bending strain and larger torsional strain compared to the conventional DHS. The changes in tip-to-apex distance (TAD), post-study varus angle, post-study rotational angle of the ODRC DHS were all significantly less than that of the conventional DHS (p < 0.05). We concluded that the ODRC DHS augmented with two horizontal wings would increase the bone-implant interface contact surface, dissipate the load to the screw itself, which improves the migration resistance and increases the anti-rotational implant effect. In conclusion, the proposed ODRC DHS demonstrated significantly better migration resistance and anti-rotational effect in comparison to the conventional DHS construct. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Silk Film Topography Directs Collective Epithelial Cell Migration

PubMed Central

Rosenblatt, Mark I.

2012-01-01

The following study provides new insight into how surface topography dictates directed collective epithelial cell sheet growth through the guidance of individual cell movement. Collective cell behavior of migrating human corneal limbal-epithelial cell sheets were studied on highly biocompatible flat and micro-patterned silk film surfaces. The silk film edge topography guided the migratory direction of individual cells making up the collective epithelial sheet, which resulted in a 75% increase in total culture elongation. This was due to a 3-fold decrease in cell sheet migration rate efficiency for movement perpendicular to the topography edge. Individual cell migration direction is preferred in the parallel approach to the edge topography where localization of cytoskeletal proteins to the topography’s edge region is reduced, which results in the directed growth of the collective epithelial sheet. Findings indicate customized biomaterial surfaces may be created to direct both the migration rate and direction of tissue epithelialization. PMID:23185573

Periodic direct current does not promote wound closure in an in vitro dynamic model of cell migration.

PubMed

Godbout, Charles; Frenette, Jérôme

2006-01-01

A prevailing paradigm is that electrical fields can promote cell migration and tissue healing. To further validate this paradigm, we tested the hypothesis that periodic direct current (DC) can enhance wound closure using an in vitro dynamic model of cell migration. Layers of primary fibroblasts were wounded and treated with DC under various voltages. Repair area, cell velocity, and directionality as well as lamellipodium area were evaluated at different times. Direct current had no beneficial effect on cell migration. Moreover, prolonged stimulation under the highest voltage led to significant reduction in wound closure and cell velocity. The reduction of membrane protusions in stimulated cells may be associated with the deleterious effect of DC. Contrary to the authors' expectations, they found that periodic DC did not promote wound closure, a finding that emphasizes the need to clarify the complex effects of electrical fields on migrating cells.

The role of backward cell migration in two-hit mutants’ production in the stem cell niche

PubMed Central

Bollas, Audrey

2017-01-01

It has been discovered that there are two stem cell groups in the intestinal crypts: central stem cells (CeSCs), which are at the very bottom of the crypt, and border stem cells (BSCs), which are located between CeSCs and transit amplifying cells (TAs). Moreover, backward cell migration from BSCs to CeSCs has been observed. Recently, a bi-compartmental stochastic model, which includes CeSCs and BSCs, has been developed to investigate the probability of two-hit mutant production in the stem cell niche. In this project, we improve this stochastic model by adding the probability of backward cell migration to the model. The model suggests that the probability of two-hit mutant production increases when the frequency of backward cell migration increases. Furthermore, a small non-zero probability of backward cell migration leads to the largest range of optimal values for the frequency of symmetric divisions and the portion of divisions at each stem cell compartment in terms of delaying 2-hit mutant production. Moreover, the probability of two-hit mutant production is more sensitive to the probability of symmetric divisions than to the rate of backward cell migrations. The highest probability of two-hit mutant production corresponds to the case when all stem cell’s divisions are asymmetric. PMID:28931019

Activation of Rho GTPase Cdc42 promotes adhesion and invasion in colorectal cancer cells.

PubMed

Gao, Lei; Bai, Lan; Nan, Qing zhen

2013-07-25

The purpose of this study was to investigate the role of activated Rho GTPase cell division control protein 42 homolog (Cdc42) in colorectal cancer cell adhesion, migration, and invasion. The constitutively active form of Cdc42 (GFP-Cdc42L61) or control vector was overexpressed in the colorectal cancer cell line SW480. The localization of active Cdc42 was monitored by immunofluorescence staining, and the effects of active Cdc42 on cell migration and invasion were examined using an attachment assay, a wound healing assay, and a Matrigel migration assay in vitro. Immunofluorescence staining revealed that constitutively active Cdc42 predominately localized to the plasma membrane. Compared to SW480 cells transfected with the control vector, overexpression of constitutively active Cdc42 in SW480 cells promoted filopodia formation and cell stretch and dramatically enhanced cell adhesion to the coated plates. The wound healing assay revealed a significant increase of migration capability in SW480 cells expressing active Cdc42 compared to the control cells. Additionally, the Matrigel invasion assay demonstrated that active Cdc42 significantly promoted SW480 cell migration through the chamber. Our results suggest that active Rho GTPase Cdc42 can greatly enhance colorectal cancer cell SW480 to spread, migrate, and invade, which may contribute to colorectal cancer metastasis.

Functional Coordination of WAVE and WASP in C. elegans Neuroblast Migration.

PubMed

Zhu, Zhiwen; Chai, Yongping; Jiang, Yuxiang; Li, Wenjing; Hu, Huifang; Li, Wei; Wu, Jia-Wei; Wang, Zhi-Xin; Huang, Shanjin; Ou, Guangshuo

2016-10-24

Directional cell migration is critical for metazoan development. We define two molecular pathways that activate the Arp2/3 complex during neuroblast migration in Caenorhabditis elegans. The transmembrane protein MIG-13/Lrp12 is linked to the Arp2/3 nucleation-promoting factors WAVE or WASP through direct interactions with ABL-1 or SEM-5/Grb2, respectively. WAVE mutations partially impaired F-actin organization and decelerated cell migration, and WASP mutations did not inhibit cell migration but enhanced migration defects in WAVE-deficient cells. Purified SEM-5 and MIG-2 synergistically stimulated the F-actin branching activity of WASP-Arp2/3 in vitro. In GFP knockin animals, WAVE and WASP were largely organized into separate clusters at the leading edge, and the amount of WASP was less than WAVE but could be elevated by WAVE mutations. Our results indicate that the MIG-13-WAVE pathway provides the major force for directional cell motility, whereas MIG-13-WASP partially compensates for its loss, underscoring their coordinated activities in facilitating robust cell migration. Copyright © 2016 Elsevier Inc. All rights reserved.

Tumor cell migration screen identifies SRPK1 as breast cancer metastasis determinant

PubMed Central

van Roosmalen, Wies; Le Dévédec, Sylvia E.; Golani, Ofra; Smid, Marcel; Pulyakhina, Irina; Timmermans, Annemieke M.; Look, Maxime P.; Zi, Di; Pont, Chantal; de Graauw, Marjo; Naffar-Abu-Amara, Suha; Kirsanova, Catherine; Rustici, Gabriella; Hoen, Peter A.C. ‘t; Martens, John W.M.; Foekens, John A.; Geiger, Benjamin; van de Water, Bob

2015-01-01

Tumor cell migration is a key process for cancer cell dissemination and metastasis that is controlled by signal-mediated cytoskeletal and cell matrix adhesion remodeling. Using a phagokinetic track assay with migratory H1299 cells, we performed an siRNA screen of almost 1,500 genes encoding kinases/phosphatases and adhesome- and migration-related proteins to identify genes that affect tumor cell migration speed and persistence. Thirty candidate genes that altered cell migration were validated in live tumor cell migration assays. Eight were associated with metastasis-free survival in breast cancer patients, with integrin β3–binding protein (ITGB3BP), MAP3K8, NIMA-related kinase (NEK2), and SHC-transforming protein 1 (SHC1) being the most predictive. Examination of genes that modulate migration indicated that SRPK1, encoding the splicing factor kinase SRSF protein kinase 1, is relevant to breast cancer outcomes, as it was highly expressed in basal breast cancer. Furthermore, high SRPK1 expression correlated with poor breast cancer disease outcome and preferential metastasis to the lungs and brain. In 2 independent murine models of breast tumor metastasis, stable shRNA-based SRPK1 knockdown suppressed metastasis to distant organs, including lung, liver, and spleen, and inhibited focal adhesion reorganization. Our study provides comprehensive information on the molecular determinants of tumor cell migration and suggests that SRPK1 has potential as a drug target for limiting breast cancer metastasis. PMID:25774502

Focal adhesion kinase is involved in mechanosensing during fibroblast migration

NASA Technical Reports Server (NTRS)

Wang, H. B.; Dembo, M.; Hanks, S. K.; Wang, Y.

2001-01-01

Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase localized at focal adhesions and is believed to mediate adhesion-stimulated effects. Although ablation of FAK impairs cell movement, it is not clear whether FAK might be involved in the guidance of cell migration, a role consistent with its putative regulatory function. We have transfected FAK-null fibroblasts with FAK gene under the control of the tetracycline repression system. Cells were cultured on flexible polyacrylamide substrates for the detection of traction forces and the application of mechanical stimulation. Compared with control cells expressing wild-type FAK, FAK-null cells showed a decrease in migration speed and directional persistence. In addition, whereas FAK-expressing cells responded to exerted forces by reorienting their movements and forming prominent focal adhesions, FAK-null cells failed to show such responses. Furthermore, FAK-null cells showed impaired responses to decreases in substrate flexibility, which causes control cells to generate weaker traction forces and migrate away from soft substrates. Cells expressing Y397F FAK, which cannot be phosphorylated at a key tyrosine site, showed similar defects in migration pattern and force-induced reorientation as did FAK-null cells. However, other aspects of F397-FAK cells, including the responses to substrate flexibility and the amplification of focal adhesions upon mechanical stimulation, were similar to that of control cells. Our results suggest that FAK plays an important role in the response of migrating cells to mechanical input. In addition, phosphorylation at Tyr-397 is required for some, but not all, of the functions of FAK in cell migration.

3D printing of biomimetic microstructures for cancer cell migration.

PubMed

Huang, Tina Qing; Qu, Xin; Liu, Justin; Chen, Shaochen

2014-02-01

To understand the physical behavior and migration of cancer cells, a 3D in vitro micro-chip in hydrogel was created using 3D projection printing. The micro-chip has a honeycomb branched structure, aiming to mimic 3D vascular morphology to test, monitor, and analyze differences in the behavior of cancer cells (i.e. HeLa) vs. non-cancerous cell lines (i.e. 10 T1/2). The 3D Projection Printing system can fabricate complex structures in seconds from user-created designs. The fabricated microstructures have three different channel widths of 25, 45, and 120 microns wide to reflect a range of blood vessel diameters. HeLa and 10 T1/2 cells seeded within the micro-chip were then analyzed for morphology and cell migration speed. 10 T1/2 cells exhibited greater changes in morphology due to channel size width than HeLa cells; however, channel width had a limited effect on 10 T1/2 cell migration while HeLa cancer cell migration increased as channel width decreased. This physiologically relevant 3D cancer tissue model has the potential to be a powerful tool for future drug discoveries and cancer migration studies.

Confinement and low adhesion induce fast amoeboid migration of slow mesenchymal cells.

PubMed

Liu, Yan-Jun; Le Berre, Maël; Lautenschlaeger, Franziska; Maiuri, Paolo; Callan-Jones, Andrew; Heuzé, Mélina; Takaki, Tohru; Voituriez, Raphaël; Piel, Matthieu

2015-02-12

The mesenchymal-amoeboid transition (MAT) was proposed as a mechanism for cancer cells to adapt their migration mode to their environment. While the molecular pathways involved in this transition are well documented, the role of the microenvironment in the MAT is still poorly understood. Here, we investigated how confinement and adhesion affect this transition. We report that, in the absence of focal adhesions and under conditions of confinement, mesenchymal cells can spontaneously switch to a fast amoeboid migration phenotype. We identified two main types of fast migration--one involving a local protrusion and a second involving a myosin-II-dependent mechanical instability of the cell cortex that leads to a global cortical flow. Interestingly, transformed cells are more prone to adopt this fast migration mode. Finally, we propose a generic model that explains migration transitions and predicts a phase diagram of migration phenotypes based on three main control parameters: confinement, adhesion, and contractility. Copyright © 2015 Elsevier Inc. All rights reserved.

On-Chip Quantitative Measurement of Mechanical Stresses During Cell Migration with Emulsion Droplets

NASA Astrophysics Data System (ADS)

Molino, D.; Quignard, S.; Gruget, C.; Pincet, F.; Chen, Y.; Piel, M.; Fattaccioli, J.

2016-07-01

The ability of immune cells to migrate within narrow and crowded spaces is a critical feature involved in various physiological processes from immune response to metastasis. Several in-vitro techniques have been developed so far to study the behaviour of migrating cells, the most recent being based on the fabrication of microchannels within which cells move. To address the question of the mechanical stress a cell is able to produce during the encounter of an obstacle while migrating, we developed a hybrid microchip made of parallel PDMS channels in which oil droplets are sparsely distributed and serve as deformable obstacles. We thus show that cells strongly deform droplets while passing them. Then, we show that the microdevice can be used to study the influence of drugs on migration at the population level. Finally, we describe a quantitative analysis method of the droplet deformation that allows measuring in real-time the mechanical stress exerted by a single cell. The method presented herein thus constitutes a powerful analytical tool for cell migration studies under confinement.

A Simple Force-Motion Relation for Migrating Cells Revealed by Multipole Analysis of Traction Stress

PubMed Central

Tanimoto, Hirokazu; Sano, Masaki

2014-01-01

For biophysical understanding of cell motility, the relationship between mechanical force and cell migration must be uncovered, but it remains elusive. Since cells migrate at small scale in dissipative circumstances, the inertia force is negligible and all forces should cancel out. This implies that one must quantify the spatial pattern of the force instead of just the summation to elucidate the force-motion relation. Here, we introduced multipole analysis to quantify the traction stress dynamics of migrating cells. We measured the traction stress of Dictyostelium discoideum cells and investigated the lowest two moments, the force dipole and quadrupole moments, which reflect rotational and front-rear asymmetries of the stress field. We derived a simple force-motion relation in which cells migrate along the force dipole axis with a direction determined by the force quadrupole. Furthermore, as a complementary approach, we also investigated fine structures in the stress field that show front-rear asymmetric kinetics consistent with the multipole analysis. The tight force-motion relation enables us to predict cell migration only from the traction stress patterns. PMID:24411233

Predicted molecular signaling guiding photoreceptor cell migration following transplantation into damaged retina

NASA Astrophysics Data System (ADS)

Unachukwu, Uchenna John; Warren, Alice; Li, Ze; Mishra, Shawn; Zhou, Jing; Sauane, Moira; Lim, Hyungsik; Vazquez, Maribel; Redenti, Stephen

2016-03-01

To replace photoreceptors lost to disease or trauma and restore vision, laboratories around the world are investigating photoreceptor replacement strategies using subretinal transplantation of photoreceptor precursor cells (PPCs) and retinal progenitor cells (RPCs). Significant obstacles to advancement of photoreceptor cell-replacement include low migration rates of transplanted cells into host retina and an absence of data describing chemotactic signaling guiding migration of transplanted cells in the damaged retinal microenvironment. To elucidate chemotactic signaling guiding transplanted cell migration, bioinformatics modeling of PPC transplantation into light-damaged retina was performed. The bioinformatics modeling analyzed whole-genome expression data and matched PPC chemotactic cell-surface receptors to cognate ligands expressed in the light-damaged retinal microenvironment. A library of significantly predicted chemotactic ligand-receptor pairs, as well as downstream signaling networks was generated. PPC and RPC migration in microfluidic ligand gradients were analyzed using a highly predicted ligand-receptor pair, SDF-1α - CXCR4, and both PPCs and RPCs exhibited significant chemotaxis. This work present a systems level model and begins to elucidate molecular mechanisms involved in PPC and RPC migration within the damaged retinal microenvironment.

Prohibitin, relocated to the front ends, can control the migration directionality of colorectal cancer cells

PubMed Central

Guo, Li-Li; Hu, Chun-Ting; Huang, Ying-Xin; Huang, Guan; Jing, Fang-Yan; Liu, Chao; Li, Zhuo-Yi; Zhou, Na; Yan, Qian-Wen; Lei, Yan; Zhu, Shi-Jie; Cheng, Zhi-Qiang; Cao, Guang-Wen; Deng, Yong-Jian; Ding, Yan-Qing

2017-01-01

Directional migration is a cost-effective movement allowing invasion and metastatic spread of cancer cells. Although migration related to cytoskeletal assembly and microenvironmental chemotaxis has been elucidated, little is known about interaction between extracellular and intracellular molecules for controlling the migrational directionality. A polarized expression of prohibitin (PHB) in the front ends of CRC cells favors metastasis and is correlated with poor prognosis for 545 CRC patients. A high level of vascular endothelial growth factor (VEGF) in the interstitial tissue of CRC patients is associated with metastasis. VEGF bound to its receptor, neuropilin-1, can stimulate the activation of cell division cycle 42, which recruits intra-mitochondrial PHB to the front end of a CRC cell. This intracellular relocation of PHB results in the polymerization and reorganization of filament actin extending to the front end of the cell. As a result, the migration directionality of CRC cells is targeted towards VEGF. Together, these findings identify PHB as a key modulator of directional migration of CRC cells and a target for metastasis. PMID:29100316

Gradient biomaterials and their influences on cell migration

PubMed Central

Wu, Jindan; Mao, Zhengwei; Tan, Huaping; Han, Lulu; Ren, Tanchen; Gao, Changyou

2012-01-01

Cell migration participates in a variety of physiological and pathological processes such as embryonic development, cancer metastasis, blood vessel formation and remoulding, tissue regeneration, immune surveillance and inflammation. The cells specifically migrate to destiny sites induced by the gradually varying concentration (gradient) of soluble signal factors and the ligands bound with the extracellular matrix in the body during a wound healing process. Therefore, regulation of the cell migration behaviours is of paramount importance in regenerative medicine. One important way is to create a microenvironment that mimics the in vivo cellular and tissue complexity by incorporating physical, chemical and biological signal gradients into engineered biomaterials. In this review, the gradients existing in vivo and their influences on cell migration are briefly described. Recent developments in the fabrication of gradient biomaterials for controlling cellular behaviours, especially the cell migration, are summarized, highlighting the importance of the intrinsic driving mechanism for tissue regeneration and the design principle of complicated and advanced tissue regenerative materials. The potential uses of the gradient biomaterials in regenerative medicine are introduced. The current and future trends in gradient biomaterials and programmed cell migration in terms of the long-term goals of tissue regeneration are prospected. PMID:23741610

Controlled surface topography regulates collective 3D migration by epithelial-mesenchymal composite embryonic tissues.

PubMed

Song, Jiho; Shawky, Joseph H; Kim, YongTae; Hazar, Melis; LeDuc, Philip R; Sitti, Metin; Davidson, Lance A

2015-07-01

Cells in tissues encounter a range of physical cues as they migrate. Probing single cell and collective migratory responses to physically defined three-dimensional (3D) microenvironments and the factors that modulate those responses are critical to understanding how tissue migration is regulated during development, regeneration, and cancer. One key physical factor that regulates cell migration is topography. Most studies on surface topography and cell mechanics have been carried out with single migratory cells, yet little is known about the spreading and motility response of 3D complex multi-cellular tissues to topographical cues. Here, we examine the response to complex topographical cues of microsurgically isolated tissue explants composed of epithelial and mesenchymal cell layers from naturally 3D organized embryos of the aquatic frog Xenopus laevis. We control topography using fabricated micropost arrays (MPAs) and investigate the collective 3D migration of these multi-cellular systems in these MPAs. We find that the topography regulates both collective and individual cell migration and that dense MPAs reduce but do not eliminate tissue spreading. By modulating cell size through the cell cycle inhibitor Mitomycin C or the spacing of the MPAs we uncover how 3D topographical cues disrupt collective cell migration. We find surface topography can direct both single cell motility and tissue spreading, altering tissue-scale processes that enable efficient conversion of single cell motility into collective movement. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Effects of selenium compounds on proliferation, migration and adhesion of HeLa cells].

PubMed

Sun, Licui; Lu, Jiaxi; Wang, Qin; Liu, Yiqun; Han, Feng; Yang, Yanhua; Zhang, Hongkun; Huang, Zhenwu

2015-03-01

To explore the effects of methylseleninic acid (MeSeA), selenomethionine (SeMet) and methylselenocysteine (MeSeCys) on proliferation, migration and adhesion of HeLa cells. HeLa cells were cultured and treated with MeSeA, SeMet and MeSeCys for 12 - 72 h respectively. MTT assay, healing assay and in vitro cell Matrigel adhesion assay were used to detect the proliferation, migration and adhesion of HeLa cells. Compared to the control group, the proliferation of HeLa cells was remarkably inhibited by MeSeA (P <0. 01). The migration of HeLa cells in MeSeA group was inhibited by 34% (P < 0. 05) and 26% (P < 0. 05) in 4 h and 8 h, respectively. However, the migration of HeLa cells with inhibitions of 18% and 13% was in SeMet group in 4 h and 8 h. The inhibitions of HeLa cell migration in MeSeCys group was 28% (P < 0.05) and 5% in 4 h and 8 h, respectively. In addition, the adhesive function of HeLa cells in the MeSeA group, the SeMet group as well as the MeSeCys group were inhibited by 36% (P < 0. 01), 25% and 49% (P < 0. 01). The proliferation and migration of HeLa cell were effectively inhibited by MeSeA, while the adhesive function of HeLa cell was remarkably inhibited by MeSeCys.

Overexpression of Rac1 in leukemia patients and its role in leukemia cell migration and growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiying; Rao, Qing, E-mail: raoqing@gmail.com; Wang, Min

2009-09-04

Rac1 belongs to the Rho family that act as critical mediators of signaling pathways controlling cell migration and proliferation and contributes to the interactions of hematopoietic stem cells with their microenvironment. Alteration of Rac1 might result in unbalanced interactions and ultimately lead to leukemogenesis. In this study, we analyze the expression of Rac1 protein in leukemia patients and determine its role in the abnormal behaviours of leukemic cells. Rac1 protein is overexpressed in primary acute myeloid leukemia cells as compared to normal bone marrow mononuclear cells. siRNA-mediated silencing of Rac1 in leukemia cell lines induced inhibition of cell migration, proliferation,more » and colony formation. Additionally, blocking Rac1 activity by an inhibitor of Rac1-GTPase, NSC23766, suppressed cell migration and growth. We conclude that overexpression of Rac1 contributes to the accelerated migration and high proliferation potential of leukemia cells, which could be implicated in leukemia development and progression.« less

Bleb Expansion in Migrating Cells Depends on Supply of Membrane from Cell Surface Invaginations.

PubMed

Goudarzi, Mohammad; Tarbashevich, Katsiaryna; Mildner, Karina; Begemann, Isabell; Garcia, Jamie; Paksa, Azadeh; Reichman-Fried, Michal; Mahabaleshwar, Harsha; Blaser, Heiko; Hartwig, Johannes; Zeuschner, Dagmar; Galic, Milos; Bagnat, Michel; Betz, Timo; Raz, Erez

2017-12-04

Cell migration is essential for morphogenesis, organ formation, and homeostasis, with relevance for clinical conditions. The migration of primordial germ cells (PGCs) is a useful model for studying this process in the context of the developing embryo. Zebrafish PGC migration depends on the formation of cellular protrusions in form of blebs, a type of protrusion found in various cell types. Here we report on the mechanisms allowing the inflation of the membrane during bleb formation. We show that the rapid expansion of the protrusion depends on membrane invaginations that are localized preferentially at the cell front. The formation of these invaginations requires the function of Cdc42, and their unfolding allows bleb inflation and dynamic cell-shape changes performed by migrating cells. Inhibiting the formation and release of the invaginations strongly interfered with bleb formation, cell motility, and the ability of the cells to reach their target. Copyright © 2017 Elsevier Inc. All rights reserved.

Doxycycline inhibits leukemic cell migration via inhibition of matrix metalloproteinases and phosphorylation of focal adhesion kinase

PubMed Central

WANG, CHUNHUAI; XIANG, RU; ZHANG, XIANGZHONG; CHEN, YUNXIAN

2015-01-01

Doxycycline, a tetracycline-based antibiotic, has been reported to attenuate melanoma cell migration through inhibiting the focal adhesion kinase (FAK) signaling pathway. However, it remains to be elucidated whether doxycycline exerts this effect on leukemia cell migration. The present study aimed to examine the role of doxycycline in leukemia cell migration. The invasion capacities of the human leukemia cell lines KG1a (acute myelogenous leukemia) and K562 (chronic myelogenous leukemia) were evaluated using Matrigel® matrix-coated Transwell® chamber assays; leukemic cell lines treated with doxycycline (1 µg/ml) or anti-β1-integrin antibodies were added to the upper chamber, while untreated cells were included as controls. Reverse transcription quantitative polymerase chain reaction was performed in order to further understand the influence of doxycycline treatment on the expression of FAK and gelatinases in the KG1a and K562 leukemic cell lines. In addition, FAK protein expression and phosphorylation were determined using western blot analysis in order to investigate the mechanism by which doxycycline inhibited leukemic cell migration. The results revealed that doxycycline treatment significantly attenuated the migration of KG1a and K562 cells, which was demonstrated to be associated with inhibition of the expression and phosphorylation of FAK. In addition, doxycycline treatment inhibited matrix metalloproteinase (MMP)-2 and MMP-9 expression. Furthermore, incubation with blocking anti-β1-integrin antibodies had an analogous inhibitory effect on leukemic cell migration to that of doxycycline. In conclusion, the results of the present study suggested that doxycycline attenuated leukemic cell migration through inhibiting the FAK signaling pathway. Therefore, doxycycline may have potential for use as a novel strategy for the treatment of leukemia. PMID:26004127

Quantitative Analysis of Complex Glioma Cell Migration on Electrospun Polycaprolactone Using Time-Lapse Microscopy

PubMed Central

Johnson, Jed; Nowicki, M. Oskar; Lee, Carol H.; Chiocca, E. Antonio; Viapiano, Mariano S.; Lawler, Sean E.

2009-01-01

Malignant gliomas are the most common tumors originating within the central nervous system and account for over 15,000 deaths annually in the United States. The median survival for glioblastoma, the most common and aggressive of these tumors, is only 14 months. Therapeutic strategies targeting glioma cells migrating away from the tumor core are currently hampered by the difficulty of reproducing migration in the neural parenchyma in vitro. We utilized a tissue engineering approach to develop a physiologically relevant model of glioma cell migration. This revealed that glioma cells display dramatic differences in migration when challenged by random versus aligned electrospun poly-ɛ-caprolactone nanofibers. Cells on aligned fibers migrated at an effective velocity of 4.2 ± 0.39 μm/h compared to 0.8 ± 0.08 μm/h on random fibers, closely matching in vivo models and prior observations of glioma spread in white versus gray matter. Cells on random fibers exhibited extension along multiple fiber axes that prevented net motion; aligned fibers promoted a fusiform morphology better suited to infiltration. Time-lapse microscopy revealed that the motion of individual cells was complex and was influenced by cell cycle and local topography. Glioma stem cell–containing neurospheres seeded on random fibers did not show cell detachment and retained their original shape; on aligned fibers, cells detached and migrated in the fiber direction over a distance sixfold greater than the perpendicular direction. This chemically and physically flexible model allows time-lapse analysis of glioma cell migration while recapitulating in vivo cell morphology, potentially allowing identification of physiological mediators and pharmacological inhibitors of invasion. PMID:19199562

Mechanical Coordination of Single-Cell and Collective-Cell Amoeboid Migration

NASA Astrophysics Data System (ADS)

Del Alamo, Juan Carlos

Amoeboid migration consists of the sequential repetition of pseudopod extensions and retractions driven by actin polymerization and actomyosin contraction, and requires cells to apply mechanical forces on their surroundings. We measure the three-dimensional forces exerted by chemotaxing Dictyostelium cells, and examine wild-type cells as well as mutants with defects in contractility, F-actin polymerization, internal F-actin crosslinking, and cortical integrity. We find that cells pull on their substrate adhesions using two distinct, yet interconnected mechanisms: axial actomyosin contractility and cortical tension. The 3D pulling forces generated by both mechanisms are internally balanced by an increase in cytoplasmic pressure that allows cells to push on their substrate, and we show that these pushing forces are relevant for cell invasion and migration in three-dimensional environments. We observe that cells migrate mainly by forming two stationary adhesion sites at the front and back of the cell, over which the cell body moves forward in a step-wise fashion. During this process, the traction forces at each adhesion site are switched off and subsequently their direction is reversed. The cell migration speed is found to be proportional to the rate at which cells are able regulate these forces to produce the cell shape changes needed for locomotion, which is increased when axial contractility overcomes the stabilizing effect of cortical tension. This spatiotemporal coordination is conserved in streams of multiple migratory cells connected head to tail, which also migrate by exerting traction forces on stationary sites. Furthermore, we observe that trailing cells reuse the adhesion sites of the leading cells. Finally, we provide evidence that the above modes of migration may be conserved in a range of other amoeboid-type moving cells such as neutrophils.

Cellular functions of TIP60.

PubMed

Sapountzi, Vasileia; Logan, Ian R; Robson, Craig N

2006-01-01

TIP60 was originally identified as a cellular acetyltransferase protein that interacts with HIV-1 Tat. As a consequence, the role of TIP60 in transcriptional regulation has been investigated intensively. Recent data suggest that TIP60 has more divergent functions than originally thought and roles for TIP60 in many processes, such as cellular signalling, DNA damage repair, cell cycle and checkpoint control and apoptosis are emerging. TIP60 is a tightly regulated transcriptional coregulator, acting in a large multiprotein complex for a range of transcription factors including androgen receptor, Myc, STAT3, NF-kappaB, E2F1 and p53. This usually involves recruitment of TIP60 acetyltransferase activities to chromatin. Additionally, in response to DNA double strand breaks, TIP60 is recruited to DNA lesions where it participates both in the initial as well as the final stages of repair. Here, we describe how TIP60 is a multifunctional enzyme involved in multiple nuclear transactions.

Brief Report: Robo1 Regulates the Migration of Human Subventricular Zone Neural Progenitor Cells During Development.

PubMed

Guerrero-Cazares, Hugo; Lavell, Emily; Chen, Linda; Schiapparelli, Paula; Lara-Velazquez, Montserrat; Capilla-Gonzalez, Vivian; Clements, Anna Christina; Drummond, Gabrielle; Noiman, Liron; Thaler, Katrina; Burke, Anne; Quiñones-Hinojosa, Alfredo

2017-07-01

Human neural progenitor cell (NPC) migration within the subventricular zone (SVZ) of the lateral ganglionic eminence is an active process throughout early brain development. The migration of human NPCs from the SVZ to the olfactory bulb during fetal stages resembles what occurs in adult rodents. As the human brain develops during infancy, this migratory stream is drastically reduced in cell number and becomes barely evident in adults. The mechanisms regulating human NPC migration are unknown. The Slit-Robo signaling pathway has been defined as a chemorepulsive cue involved in axon guidance and neuroblast migration in rodents. Slit and Robo proteins expressed in the rodent brain help guide neuroblast migration from the SVZ through the rostral migratory stream to the olfactory bulb. Here, we present the first study on the role that Slit and Robo proteins play in human-derived fetal neural progenitor cell migration (hfNPC). We describe that Robo1 and Robo2 isoforms are expressed in the human fetal SVZ. Furthermore, we demonstrate that Slit2 is able to induce a chemorepellent effect on the migration of hfNPCs derived from the human fetal SVZ. In addition, when Robo1 expression is inhibited, hfNPCs are unable to migrate to the olfactory bulb of mice when injected in the anterior SVZ. Our findings indicate that the migration of human NPCs from the SVZ is partially regulated by the Slit-Robo axis. This pathway could be regulated to direct the migration of NPCs in human endogenous neural cell therapy. Stem Cells 2017;35:1860-1865. © 2017 AlphaMed Press.

Brain-Derived Neurotrophic Factor Promotes Vasculature-Associated Migration of Neuronal Precursors toward the Ischemic Striatum

PubMed Central

Grade, Sofia; Weng, Yuan C.; Snapyan, Marina; Kriz, Jasna; Malva, João O.; Saghatelyan, Armen

2013-01-01

Stroke induces the recruitment of neuronal precursors from the subventricular zone (SVZ) into the ischemic striatum. In injured areas, de-routed neuroblasts use blood vessels as a physical scaffold to their migration, in a process that resembles the constitutive migration seen in the rostral migratory stream (RMS). The molecular mechanism underlying injury-induced vasculature-mediated migration of neuroblasts in the post-stroke striatum remains, however, elusive. Using adult mice we now demonstrate that endothelial cells in the ischemic striatum produce brain-derived neurotrophic factor (BDNF), a neurotrophin that promotes the vasculature-mediated migration of neuronal precursors in the RMS, and that recruited neuroblasts maintain expression of p75NTR, a low-affinity receptor for BDNF. Reactive astrocytes, which are widespread throughout the damaged area, ensheath blood vessels and express TrkB, a high-affinity receptor for BDNF. Despite the absence of BDNF mRNA, we observed strong BDNF immunolabeling in astrocytes, suggesting that these glial cells trap extracellular BDNF. Importantly, this pattern of expression is reminiscent of the adult RMS, where TrkB-expressing astrocytes bind and sequester vasculature-derived BDNF, leading to the entry of migrating cells into the stationary phase. Real-time imaging of cell migration in acute brain slices revealed a direct role for BDNF in promoting the migration of neuroblasts to ischemic areas. We also demonstrated that cells migrating in the ischemic striatum display higher exploratory behavior and longer stationary periods than cells migrating in the RMS. Our findings suggest that the mechanisms involved in the injury-induced vasculature-mediated migration of neuroblasts recapitulate, at least partially, those observed during constitutive migration in the RMS. PMID:23383048

On the role of PDZ domain-encoding genes in Drosophila border cell migration.

PubMed

Aranjuez, George; Kudlaty, Elizabeth; Longworth, Michelle S; McDonald, Jocelyn A

2012-11-01

Cells often move as collective groups during normal embryonic development and wound healing, although the mechanisms governing this type of migration are poorly understood. The Drosophila melanogaster border cells migrate as a cluster during late oogenesis and serve as a powerful in vivo genetic model for collective cell migration. To discover new genes that participate in border cell migration, 64 out of 66 genes that encode PDZ domain-containing proteins were systematically targeted by in vivo RNAi knockdown. The PDZ domain is one of the largest families of protein-protein interaction domains found in eukaryotes. Proteins that contain PDZ domains participate in a variety of biological processes, including signal transduction and establishment of epithelial apical-basal polarity. Targeting PDZ proteins effectively assesses a larger number of genes via the protein complexes and pathways through which these proteins function. par-6, a known regulator of border cell migration, was a positive hit and thus validated the approach. Knockdown of 14 PDZ domain genes disrupted migration with multiple RNAi lines. The candidate genes have diverse predicted cellular functions and are anticipated to provide new insights into the mechanisms that control border cell movement. As a test of this concept, two genes that disrupted migration were characterized in more detail: big bang and the Dlg5 homolog CG6509. We present evidence that Big bang regulates JAK/STAT signaling, whereas Dlg5/CG6509 maintains cluster cohesion. Moreover, these results demonstrate that targeting a selected class of genes by RNAi can uncover novel regulators of collective cell migration.

Lipid Raft Association Restricts CD44-Ezrin Interaction and Promotion of Breast Cancer Cell Migration

PubMed Central

Donatello, Simona; Babina, Irina S.; Hazelwood, Lee D.; Hill, Arnold D.K.; Nabi, Ivan R.; Hopkins, Ann M.

2012-01-01

Cancer cell migration is an early event in metastasis, the main cause of breast cancer-related deaths. Cholesterol-enriched membrane domains called lipid rafts influence the function of many molecules, including the raft-associated protein CD44. We describe a novel mechanism whereby rafts regulate interactions between CD44 and its binding partner ezrin in migrating breast cancer cells. Specifically, in nonmigrating cells, CD44 and ezrin localized to different membranous compartments: CD44 predominantly in rafts, and ezrin in nonraft compartments. After the induction of migration (either nonspecific or CD44-driven), CD44 affiliation with lipid rafts was decreased. This was accompanied by increased coprecipitation of CD44 and active (threonine-phosphorylated) ezrin-radixin-moesin (ERM) proteins in nonraft compartments and increased colocalization of CD44 with the nonraft protein, transferrin receptor. Pharmacological raft disruption using methyl-β-cyclodextrin also increased CD44-ezrin coprecipitation and colocalization, further suggesting that CD44 interacts with ezrin outside rafts during migration. Conversely, promoting CD44 retention inside lipid rafts by pharmacological inhibition of depalmitoylation virtually abolished CD44-ezrin interactions. However, transient single or double knockdown of flotillin-1 or caveolin-1 was not sufficient to increase cell migration over a short time course, suggesting complex crosstalk mechanisms. We propose a new model for CD44-dependent breast cancer cell migration, where CD44 must relocalize outside lipid rafts to drive cell migration. This could have implications for rafts as pharmacological targets to down-regulate cancer cell migration. PMID:23031255

Ring-Shaped Microlanes and Chemical Barriers as a Platform for Probing Single-Cell Migration.

PubMed

Schreiber, Christoph; Segerer, Felix J; Wagner, Ernst; Roidl, Andreas; Rädler, Joachim O

2016-05-31

Quantification and discrimination of pharmaceutical and disease-related effects on cell migration requires detailed characterization of single-cell motility. In this context, micropatterned substrates that constrain cells within defined geometries facilitate quantitative readout of locomotion. Here, we study quasi-one-dimensional cell migration in ring-shaped microlanes. We observe bimodal behavior in form of alternating states of directional migration (run state) and reorientation (rest state). Both states show exponential lifetime distributions with characteristic persistence times, which, together with the cell velocity in the run state, provide a set of parameters that succinctly describe cell motion. By introducing PEGylated barriers of different widths into the lane, we extend this description by quantifying the effects of abrupt changes in substrate chemistry on migrating cells. The transit probability decreases exponentially as a function of barrier width, thus specifying a characteristic penetration depth of the leading lamellipodia. Applying this fingerprint-like characterization of cell motion, we compare different cell lines, and demonstrate that the cancer drug candidate salinomycin affects transit probability and resting time, but not run time or run velocity. Hence, the presented assay allows to assess multiple migration-related parameters, permits detailed characterization of cell motility, and has potential applications in cell biology and advanced drug screening.

Coactosin accelerates cell dynamism by promoting actin polymerization.

PubMed

Hou, Xubin; Katahira, Tatsuya; Ohashi, Kazumasa; Mizuno, Kensaku; Sugiyama, Sayaka; Nakamura, Harukazu

2013-07-01

During development, cells dynamically move or extend their processes, which are achieved by actin dynamics. In the present study, we paid attention to Coactosin, an actin binding protein, and studied its role in actin dynamics. Coactosin was associated with actin and Capping protein in neural crest cells and N1E-115 neuroblastoma cells. Accumulation of Coactosin to cellular processes and its association with actin filaments prompted us to reveal the effect of Coactosin on cell migration. Coactosin overexpression induced cellular processes in cultured neural crest cells. In contrast, knock-down of Coactosin resulted in disruption of actin polymerization and of neural crest cell migration. Importantly, Coactosin was recruited to lamellipodia and filopodia in response to Rac signaling, and mutated Coactosin that cannot bind to F-actin did not react to Rac signaling, nor support neural crest cell migration. It was also shown that deprivation of Rac signaling from neural crest cells by dominant negative Rac1 (DN-Rac1) interfered with neural crest cell migration, and that co-transfection of DN-Rac1 and Coactosin restored neural crest cell migration. From these results we have concluded that Coactosin functions downstream of Rac signaling and that it is involved in neurite extension and neural crest cell migration by actively participating in actin polymerization. Copyright © 2013 Elsevier Inc. All rights reserved.

Displacement correlations between a single mesenchymal-like cell and its nucleus effectively link subcellular activities and motility in cell migration analysis

NASA Astrophysics Data System (ADS)

Lan, Tian; Cheng, Kai; Ren, Tina; Arce, Stephen Hugo; Tseng, Yiider

2016-09-01

Cell migration is an essential process in organism development and physiological maintenance. Although current methods permit accurate comparisons of the effects of molecular manipulations and drug applications on cell motility, effects of alterations in subcellular activities on motility cannot be fully elucidated from those methods. Here, we develop a strategy termed cell-nuclear (CN) correlation to parameterize represented dynamic subcellular activities and to quantify their contributions in mesenchymal-like migration. Based on the biophysical meaning of the CN correlation, we propose a cell migration potential index (CMPI) to measure cell motility. When the effectiveness of CMPI was evaluated with respect to one of the most popular cell migration analysis methods, Persistent Random Walk, we found that the cell motility estimates among six cell lines used in this study were highly consistent between these two approaches. Further evaluations indicated that CMPI can be determined using a shorter time period and smaller cell sample size, and it possesses excellent reliability and applicability, even in the presence of a wide range of noise, as might be generated from individual imaging acquisition systems. The novel approach outlined here introduces a robust strategy through an analysis of subcellular locomotion activities for single cell migration assessment.

Downregulation of NEDD9 by apigenin suppresses migration, invasion, and metastasis of colorectal cancer cells.

PubMed

Dai, Jin; Van Wie, Peter G; Fai, Leonard Yenwong; Kim, Donghern; Wang, Lei; Poyil, Pratheeshkumar; Luo, Jia; Zhang, Zhuo

2016-11-15

Apigenin is a natural flavonoid which possesses multiple anti-cancer properties such as anti-proliferation, anti-inflammation, and anti-metastasis in many types of cancers including colorectal cancer. Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a multi-domain scaffolding protein of the Cas family which has been shown to correlate with cancer metastasis and progression. The present study investigates the role of NEDD9 in apigenin-inhibited cell migration, invasion, and metastasis of colorectal adenocarcinoma DLD1 and SW480 cells. The results show that knockdown of NEDD9 inhibited cell migration, invasion, and metastasis and that overexpression of NEDD9 promoted cell migration and invasion of DLD1 cells and SW4890 cells. Apigenin treatment attenuated NEDD9 expression at protein level, resulting in reduced phosphorylations of FAK, Src, and Akt, leading to inhibition on cell migration, invasion, and metastasis of both DLD1 and SW480 cells. The present study has demonstrated that apigenin inhibits cell migration, invasion, and metastasis through NEDD9/Src/Akt cascade in colorectal cancer cells. NEDD9 may function as a biomarker for evaluation of cancer aggressiveness and for selection of therapeutic drugs against cancer progression. Copyright © 2016 Elsevier Inc. All rights reserved.

X-ray-enhanced cancer cell migration requires the linker of nucleoskeleton and cytoskeleton complex.

PubMed

Imaizumi, Hiromasa; Sato, Katsutoshi; Nishihara, Asuka; Minami, Kazumasa; Koizumi, Masahiko; Matsuura, Nariaki; Hieda, Miki

2018-04-01

The linker of nucleoskeleton and cytoskeleton (LINC) complex is a multifunctional protein complex that is involved in various processes at the nuclear envelope, including nuclear migration, mechanotransduction, chromatin tethering and DNA damage response. We recently showed that a nuclear envelope protein, Sad1 and UNC84 domain protein 1 (SUN1), a component of the LINC complex, has a critical function in cell migration. Although ionizing radiation activates cell migration and invasion in vivo and in vitro, the underlying molecular mechanism remains unknown. Here, we examined the involvement of the LINC complex in radiation-enhanced cell migration and invasion. A sublethal dose of X-ray radiation promoted human breast cancer MDA-MB-231 cell migration and invasion, whereas carbon ion beam radiation suppressed these processes in a dose-dependent manner. Depletion of SUN1 and SUN2 significantly suppressed X-ray-enhanced cell migration and invasion. Moreover, depletion or overexpression of each SUN1 splicing variant revealed that SUN1_888 containing 888 amino acids of SUN1 but not SUN1_916 was required for X-ray-enhanced migration and invasion. In addition, the results suggested that X-ray irradiation affected the expression level of SUN1 splicing variants and a SUN protein binding partner, nesprins. Taken together, our findings supported that the LINC complex contributed to photon-enhanced cell migration and invasion. © 2018 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

PM2.5 promotes human bronchial smooth muscle cell migration via the sonic hedgehog signaling pathway.

PubMed

Ye, Xiuqin; Hong, Wei; Hao, Binwei; Peng, Gongyong; Huang, Lingmei; Zhao, Zhuxiang; Zhou, Yumin; Zheng, Mengning; Li, Chenglong; Liang, Chunxiao; Yi, Erkang; Pu, Jinding; Li, Bing; Ran, Pixin

2018-03-02

The contribution of airway remodeling in chronic obstructive pulmonary disease (COPD) has been well documented, with airway smooth muscle cell proliferation and migration playing a role in the remodeling process. Here, we aimed to verify the effects of fine particulate matter (PM2.5) on human bronchial smooth muscle cell (HBSMC) migration and to explore the underlying signaling pathways. HBSMC apoptosis, proliferation and migration were measured using flow cytometry, cell counting and transwell migration assays, respectively. The role of the hedgehog pathway in cell migration was assessed by western blotting to measure the expression of Sonic hedgehog (Shh), Gli1 and Snail. Furthermore, siRNA was used to knock down Gli1 or Snail expression. PM2.5 induced HBSMC apoptosis in a dose-dependent manner, although certain concentrations of PM2.5 did not induce HBSMC proliferation or apoptosis. Interestingly, cell migration was stimulated by PM2.5 doses far below those that induced apoptosis. Additional experiments revealed that these PM2.5 doses enhanced the expression of Shh, Gli1 and Snail in HBSMCs. Furthermore, PM2.5-induced cell migration and protein expression were enhanced by recombinant Shh and attenuated by cyclopamine. Similar results were obtained by knocking down Gli1 or Snail. These findings suggest that PM2.5, which may exert its effects through the Shh signaling pathway, is necessary for the migration of HBSMCs. These data define a novel role for PM2.5 in airway remodeling in COPD.

Role of peptidylarginine deiminase 2 (PAD2) in mammary carcinoma cell migration.

PubMed

Horibata, Sachi; Rogers, Katherine E; Sadegh, David; Anguish, Lynne J; McElwee, John L; Shah, Pragya; Thompson, Paul R; Coonrod, Scott A

2017-05-26

Penetration of the mammary gland basement membrane by cancer cells is a crucial first step in tumor invasion. Using a mouse model of ductal carcinoma in situ, we previously found that inhibition of peptidylarginine deiminase 2 (PAD2, aka PADI2) activity appears to maintain basement membrane integrity in xenograft tumors. The goal of this investigation was to gain insight into the mechanisms by which PAD2 mediates this process. For our study, we modulated PAD2 activity in mammary ductal carcinoma cells by lentiviral shRNA-mediated depletion, lentiviral-mediated PAD2 overexpression, or PAD inhibition and explored the effects of these treatments on changes in cell migration and cell morphology. We also used these PAD2-modulated cells to test whether PAD2 may be required for EGF-induced cell migration. To determine how PAD2 might promote tumor cell migration in vivo, we tested the effects of PAD2 inhibition on the expression of several cell migration mediators in MCF10DCIS.com xenograft tumors. In addition, we tested the effect of PAD2 inhibition on EGF-induced ductal invasion and elongation in primary mouse mammary organoids. Lastly, using a transgenic mouse model, we investigated the effects of PAD2 overexpression on mammary gland development. Our results indicate that PAD2 depletion or inhibition suppresses cell migration and alters the morphology of MCF10DCIS.com cells. In addition, we found that PAD2 depletion suppresses the expression of the cytoskeletal regulatory proteins RhoA, Rac1, and Cdc42 and also promotes a mesenchymal to epithelial-like transition in tumor cells with an associated increase in the cell adhesion marker, E-cadherin. Our mammary gland organoid study found that inhibition of PAD2 activity suppresses EGF-induced ductal invasion. In vivo, we found that PAD2 overexpression causes hyperbranching in the developing mammary gland. Together, these results suggest that PAD2 plays a critical role in breast cancer cell migration. Our findings that EGF treatment increases protein citrullination and that PAD2 inhibition blocks EGF-induced cell migration suggest that PAD2 likely functions within the EGF signaling pathway to mediate cell migration.

Reciprocal Activation of Transcription Factors Underlies the Dichotomy between Proliferation and Invasion of Glioma Cells

PubMed Central

Dhruv, Harshil D.; McDonough Winslow, Wendy S.; Armstrong, Brock; Tuncali, Serdar; Eschbacher, Jenny; Kislin, Kerri; Loftus, Joseph C.; Tran, Nhan L.; Berens, Michael E.

2013-01-01

Histology of malignant glioma depicts dense proliferative areas rich in angiogenesis as well as dissemination of neoplastic cells into adjacent brain tissue. Although the mechanisms that trigger transition from proliferative to invasive phenotypes are complex, the dichotomy of cell proliferation and migration, the “Go or Grow” hypothesis, argues for specific and coordinated regulation of these phenotypes. We investigated transcriptional elements that accompany the phenotypes of migration and proliferation, and consider the therapeutic significance of the “Go or Grow” hypothesis. Interrogation of matched core and rim regions from human glioblastoma biopsy specimens in situ (n = 44) revealed higher proliferation (Ki67 labeling index) in cells residing at the core compared to the rim. Profiling activated transcription factors in a panel of migration-activated versus migration-restricted GBM cells portrayed strong NF-κB activity in the migratory cell population. In contrast, increased c-Myc activity was found in migration-restricted proliferative cells. Validation of transcriptional activity by NF-κB- or c-Myc-driven GFP or RFP, respectively, showed an increased NF-κB activity in the active migrating cells, whereas the proliferative, migration restricted cells displayed increased c-Myc activity. Immunohistochemistry on clinical specimens validated a robust phosphorylated c-Myc staining in tumor cells at the core, whereas increased phosphorylated NF-κB staining was detected in the invasive tumor cells at the rim. Functional genomics revealed that depletion of c-Myc expression by siRNA oligonucleotides reduced cell proliferation in vitro, but surprisingly, cell migration was enhanced significantly. Conversely, inhibition of NF-κB by pharmacological inhibitors, SN50 or BAY-11, decreased both cell migration in vitro and invasion ex vivo. Notably, inhibition of NF-κB was found to have no effect on the proliferation rate of glioma cells. These findings suggest that the reciprocal and coordinated suppression/activation of transcription factors, such as c-Myc and NF-κB may underlie the shift of glioma cells from a “growing-to-going” phenotype. PMID:23967279

In vivo collective cell migration requires an LPAR2-dependent increase in tissue fluidity.

PubMed

Kuriyama, Sei; Theveneau, Eric; Benedetto, Alexandre; Parsons, Maddy; Tanaka, Masamitsu; Charras, Guillaume; Kabla, Alexandre; Mayor, Roberto

2014-07-07

Collective cell migration (CCM) and epithelial-mesenchymal transition (EMT) are common to cancer and morphogenesis, and are often considered to be mutually exclusive in spite of the fact that many cancer and embryonic cells that have gone through EMT still cooperate to migrate collectively. Here we use neural crest (NC) cells to address the question of how cells that have down-regulated cell-cell adhesions can migrate collectively. NC cell dissociation relies on a qualitative and quantitative change of the cadherin repertoire. We found that the level of cell-cell adhesion is precisely regulated by internalization of N-cadherin downstream of lysophosphatidic acid (LPA) receptor 2. Rather than promoting the generation of single, fully mesenchymal cells, this reduction of membrane N-cadherin only triggers a partial mesenchymal phenotype. This intermediate phenotype is characterized by an increase in tissue fluidity akin to a solid-like-to-fluid-like transition. This change of plasticity allows cells to migrate under physical constraints without abolishing cell cooperation required for collectiveness. © 2014 Kuriyama et al.

Surface wettability of plasma SiOx:H nanocoating-induced endothelial cells' migration and the associated FAK-Rho GTPases signalling pathways

PubMed Central

Shen, Yang; Wang, Guixue; Huang, Xianliang; Zhang, Qin; Wu, Jiang; Tang, Chaojun; Yu, Qingsong; Liu, Xiaoheng

2012-01-01

Vascular endothelial cell (EC) adhesion and migration are essential processes in re-endothelialization of implanted biomaterials. There is no clear relationship and mechanism between EC adhesion and migration behaviour on surfaces with varying wettabilities. As model substrates, plasma SiOx:H nanocoatings with well-controlled surface wettability (with water contact angles in the range of 98.5 ± 2.3° to 26.3 ± 4.0°) were used in this study to investigate the effects of surface wettability on cell adhesion/migration and associated protein expressions in FAK-Rho GTPases signalling pathways. It was found that EC adhesion/migration showed opposite behaviour on the hydrophilic and hydrophobic surfaces (i.e. hydrophobic surfaces promoted EC migration but were anti-adhesions). The number of adherent ECs showed a maximum on hydrophilic surfaces, while cells adhered to hydrophobic surfaces exhibited a tendency for cell migration. The focal adhesion kinase (FAK) inhibitor targeting the Y-397 site of FAK could significantly inhibit cell adhesion/migration, suggesting that EC adhesion and migration on surfaces with different wettabilities involve (p)FAK and its downstream signalling pathways. Western blot results suggested that the FAK-Rho GTPases signalling pathways were correlative to EC migration on hydrophobic plasma SiOx:H surfaces, but uncertain to hydrophilic surfaces. This work demonstrated that surface wettability could induce cellular behaviours that were associated with different cellular signalling events. PMID:21715399

Past matrix stiffness primes epithelial cells and regulates their future collective migration through a mechanical memory.

PubMed

Nasrollahi, Samila; Walter, Christopher; Loza, Andrew J; Schimizzi, Gregory V; Longmore, Gregory D; Pathak, Amit

2017-11-01

During morphogenesis and cancer metastasis, grouped cells migrate through tissues of dissimilar stiffness. Although the influence of matrix stiffness on cellular mechanosensitivity and motility are well-recognized, it remains unknown whether these matrix-dependent cellular features persist after cells move to a new microenvironment. Here, we interrogate whether priming of epithelial cells by a given matrix stiffness influences their future collective migration on a different matrix - a property we refer to as the 'mechanical memory' of migratory cells. To prime cells on a defined matrix and track their collective migration onto an adjoining secondary matrix of dissimilar stiffness, we develop a modular polyacrylamide substrate through step-by-step polymerization of different PA compositions. We report that epithelial cells primed on a stiff matrix migrate faster, display higher actomyosin expression, form larger focal adhesions, and retain nuclear YAP even after arriving onto a soft secondary matrix, as compared to their control behavior on a homogeneously soft matrix. Priming on a soft ECM causes a reverse effect. The depletion of YAP dramatically reduces this memory-dependent migration. Our results present a previously unidentified regulation of mechanosensitive collective cell migration by past matrix stiffness, in which mechanical memory depends on YAP activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rhodamine B induces long nucleoplasmic bridges and other nuclear anomalies in Allium cepa root tip cells.

PubMed

Tan, Dehong; Bai, Bing; Jiang, Donghua; Shi, Lin; Cheng, Shunchang; Tao, Dongbing; Ji, Shujuan

2014-03-01

The cytogenetic toxicity of rhodamine B on root tip cells of Allium cepa was investigated. A. cepa were cultured in water (negative control), 10 ppm methyl methanesulfonate (positive control), and three concentrations of rhodamine B (200, 100, and 50 ppm) for 7 days. Rhodamine B inhibited mitotic activity; increased nuclear anomalies, including micronuclei, nuclear buds, and bridged nuclei; and induced oxidative stress in A. cepa root tissues. Furthermore, a substantial amount of long nucleoplasmic bridges were entangled together, and some nuclei were simultaneously linked to several other nuclei and to nuclear buds with nucleoplasmic bridges in rhodamine B-treated cells. In conclusion, rhodamine B induced cytogenetic effects in A. cepa root tip cells, which suggests that the A. cepa root is an ideal model system for detecting cellular interactions.

MicroRNA-224 inhibits proliferation and migration of breast cancer cells by down-regulating Fizzled 5 expression.

PubMed

Liu, Feng; Liu, Yang; Shen, Jingling; Zhang, Guoqiang; Han, Jiguang

2016-08-02

The Wnt/β-catenin signaling is crucial for the proliferation and migration of breast cancer cells. However, the expression of microRNA-224 (miR-224) in the different types of breast cancers and its role in the Wnt/β-catenin signaling and the proliferation and migration of breast cancer cells are poorly understood. In this study, the levels of miR-224 in different types of breast cancer tissues and cell lines were examined by quantitative RT-PCR and the potential targets of miR-224 in the Wnt/β-catenin signaling were investigated. The effects of altered miR-224 expression on the frequency of CD44+CD24- cancer stem-like cells (CSC), proliferation and migration of MCF-7 and MDA-MB-231 cells were examined by flow cytometry, MTT and transwell migration. We found that the levels of miR-224 expression in different types of breast cancer tissues and cell lines were associated inversely with aggressiveness of breast cancers. Enhanced miR-224 expression significantly reduced the fizzled 5-regulated luciferase activity in 293T cells, fizzled 5 expression in MCF-7 and MDA-MB-231 cells, the β-dependent luciferase activity in MCF-7 cells, and the nuclear translocation of β-catenin in MDA-MB-231 cells. miR-224 inhibition significantly increased the percentages of CSC in MCF-7 cells and enhanced proliferation and migration of MCF-7 cells. Enhanced miR-224 expression inhibited proliferation and migration of MDA-MB-231 cells, and the growth of implanted breast cancers in vivo. Induction of Frizzled 5 over-expression mitigated the miR-224-mediated inhibition of breast cancer cell proliferation. Collectively, these data indicated that miR-224 down-regulated the Wnt/β-catenin signaling possibly by binding to Frizzled 5 and inhibited proliferation and migration of breast cancer cells.

Response to 'Comment on 'Controllable local modification of fractured Nb-doped SrTiO{sub 3} surfaces' [Appl. Phys. Lett. 98, 256102 (2011)'.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chien, T. Y.; Santos, T. S.; Bode, M.

2011-06-20

In their comment, Chen et al. try to argue that the experimentally observed controllable voltage-induced surface modification, which was attributed to a local electric field-induced atom transfer from the surface to the tip, is rather caused by either an oxidation process and/or a resistance change. In this response, we will show that we can rule out these two effects in our experiment. The statements by Chen et al. are based on two arguments: (1) the tip modification after transferring an adatom should alter the dI/dV contrast, which was not seen in our experiments and (2) the vacuum conditions in ourmore » experiment are similar to earlier reports on resistance switching. First, Chen et al. discuss that the adsorption on the tip should alter the topographic contrast, as many papers have reported. In fact, in our experiments we frequently observed tip modifications at high bias voltage. These typically result in slight changes in scanning tunneling spectroscopy data [see, for example, the spectra in Fig. 3(b) in Ref. 4 and Fig. 2(d) of Ref. 5] but only weakly affected the topographic contrast. Second, Chen et al. claim that oxidation is another possible mechanism to explain our experimental observations. To support this claim, they compare our results to an earlier publication showing resistance switching. In fact, the resistance switching mechanism is related to oxygen vacancy migration or local surface oxidation. The mechanism of oxygen vacancy migration requires a 'forming' process with a threshold current in the order of microampere or even milliampere. In our experimental setup, however, we used tunneling currents in the order of 50 pA. Even during surface modification, which was performed at open feedback loop conditions with voltage pulse of up to 3 or -5 V, the maximum transient current did not exceed a few nanoampere. Therefore, we can safely exclude oxygen vacancy migration as a potential mechanism for the observed surface modification. As a second potential mechanism Chen et al. mention a local surface oxidation process. However, the total pressure at high-vacuum conditions used in experiments, where resistance switching was observed (10{sup -7} torr in Ref. 3) is three order magnitude higher than in our experiment performed under ultrahigh vacuum (UHV) conditions (below 10{sup -10} torr). Furthermore, mass spectra measured with a residual gas analyzer show that the main residue gas in our UHV system is hydrogen ({approx} 90%). Water, oxygen, and other oxygen-related gases are negligible with a partial pressure in the order of 10{sup -12} torr range or lower. Therefore, we can also exclude that local oxidation with reactants from the residual gas causes the observed modifications. In addition, in our experiment, the refilling of the modified areas at negative bias could not be observed with fresh tip, even for bias voltages as high as -10 V. In short, the mechanism for the modification on the UHV in situ fractured Nb:SrTiO{sub 3} (Nb-doped Strontium titanate) surfaces with scanning tunneling microscope (STM) tip is different from the mechanisms such as local surface oxidation or filament formation, used to explain the largecurrent induced resistance switching works.« less

LRIT3 is essential to localize TRPM1 to the dendritic tips of depolarizing bipolar cells and may play a role in cone synapse formation

PubMed Central

Neuillé, Marion; Morgans, Catherine W.; Cao, Yan; Orhan, Elise; Michiels, Christelle; Sahel, José-Alain; Audo, Isabelle; Duvoisin, Robert M.; Martemyanov, Kirill A.; Zeitz, Christina

2016-01-01

Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). The exact role of LRIT3 in ON-bipolar cell signaling cascade remains to be elucidated. Recently, we have characterized a novel mouse model lacking Lrit3 (no b-wave 6, (Lrit3nob6/nob6)), which displays similar abnormalities as patients with cCSNB with LRIT3 mutations. Here we compare the localization of components of the ON-bipolar cell signaling cascade in wild-type and Lrit3nob6/nob6 retinal sections by immunofluorescence confocal microscopy. An anti-LRIT3 antibody was generated. Immunofluorescent staining of LRIT3 in wild-type mice revealed a specific punctate labeling in the outer plexiform layer (OPL), which was absent in Lrit3nob6/nob6 mice. LRIT3 did not colocalize with ribeye or calbindin but colocalized with mGluR6. TRPM1 staining was severely decreased at the dendritic tips of all depolarizing bipolar cells in Lrit3nob6/nob6 mice. mGluR6, GPR179, RGS7, RGS11 and Gβ5 immunofluorescence was absent at the dendritic tips of cone ON-bipolar cells in Lrit3nob6/nob6 mice, while it was present at the dendritic tips of rod bipolar cells. Furthermore, PNA labeling was severely reduced in the OPL in Lrit3nob6/nob6 mice. This study confirmed the localization of LRIT3 at the dendritic tips of depolarizing bipolar cells in mouse retina and demonstrated the dependence of TRPM1 localization on the presence of LRIT3. Since tested components of the ON-bipolar cell signaling cascade and PNA revealed disrupted localization, an additional function of LRIT3 in cone synapse formation is suggested. These results point to a possibly different regulation of the mGluR6 signaling cascade between rod and cone ON-bipolar cells. PMID:25997951

Profilin1 activity in cerebellar granule neurons is required for radial migration in vivo

PubMed Central

Kullmann, Jan A; Wickertsheim, Ines; Minnerup, Lara; Costell, Mercedes; Friauf, Eckhard; Rust, Marco B

2015-01-01

Neuron migration defects are an important aspect of human neuropathies. The underlying molecular mechanisms of such migration defects are largely unknown. Actin dynamics has been recognized as an important determinant of neuronal migration, and we recently found that the actin-binding protein profilin1 is relevant for radial migration of cerebellar granule neurons (CGN). As the exploited brain-specific mutants lacked profilin1 in both neurons and glial cells, it remained unknown whether profilin1 activity in CGN is relevant for CGN migration in vivo. To test this, we capitalized on a transgenic mouse line that expresses a tamoxifen-inducible Cre variant in CGN, but no other cerebellar cell type. In these profilin1 mutants, the cell density was elevated in the molecular layer, and ectopic CGN occurred. Moreover, 5-bromo-2′-deoxyuridine tracing experiments revealed impaired CGN radial migration. Hence, our data demonstrate the cell autonomous role of profilin1 activity in CGN for radial migration. PMID:25495756

Superresolution and pulse-chase imaging reveal the role of vesicle transport in polar growth of fungal cells

PubMed Central

Zhou, Lu; Evangelinos, Minoas; Wernet, Valentin; Eckert, Antonia F.; Ishitsuka, Yuji; Fischer, Reinhard; Nienhaus, G. Ulrich; Takeshita, Norio

2018-01-01

Polarized growth of filamentous fungi requires continuous transport of biomolecules to the hyphal tip. To this end, construction materials are packaged in vesicles and transported by motor proteins along microtubules and actin filaments. We have studied these processes with quantitative superresolution localization microscopy of live Aspergillus nidulans cells expressing the photoconvertible protein mEosFPthermo fused to the chitin synthase ChsB. ChsB is mainly located at the Spitzenkörper near the hyphal tip and produces chitin, a key component of the cell wall. We have visualized the pulsatory dynamics of the Spitzenkörper, reflecting vesicle accumulation before exocytosis and their subsequent fusion with the apical plasma membrane. Furthermore, high-speed pulse-chase imaging after photoconversion of mEosFPthermo in a tightly focused spot revealed that ChsB is transported with two different speeds from the cell body to the hyphal tip and vice versa. Comparative analysis using motor protein deletion mutants allowed us to assign the fast movements (7 to 10 μm s−1) to transport of secretory vesicles by kinesin-1, and the slower ones (2 to 7 μm s−1) to transport by kinesin-3 on early endosomes. Our results show how motor proteins ensure the supply of vesicles to the hyphal tip, where temporally regulated exocytosis results in stepwise tip extension. PMID:29387789

Structure of a force-conveying cadherin bond essential for inner-ear mechanotransduction.

PubMed

Sotomayor, Marcos; Weihofen, Wilhelm A; Gaudet, Rachelle; Corey, David P

2012-12-06

Hearing and balance use hair cells in the inner ear to transform mechanical stimuli into electrical signals. Mechanical force from sound waves or head movements is conveyed to hair-cell transduction channels by tip links, fine filaments formed by two atypical cadherins known as protocadherin 15 and cadherin 23 (refs 4, 5). These two proteins are involved in inherited deafness and feature long extracellular domains that interact tip-to-tip in a Ca(2+)-dependent manner. However, the molecular architecture of this complex is unknown. Here we combine crystallography, molecular dynamics simulations and binding experiments to characterize the protocadherin 15-cadherin 23 bond. We find a unique cadherin interaction mechanism, in which the two most amino-terminal cadherin repeats (extracellular cadherin repeats 1 and 2) of each protein interact to form an overlapped, antiparallel heterodimer. Simulations predict that this tip-link bond is mechanically strong enough to resist forces in hair cells. In addition, the complex is shown to become unstable in response to Ca(2+) removal owing to increased flexure of Ca(2+)-free cadherin repeats. Finally, we use structures and biochemical measurements to study the molecular mechanisms by which deafness mutations disrupt tip-link function. Overall, our results shed light on the molecular mechanics of hair-cell sensory transduction and on new interaction mechanisms for cadherins, a large protein family implicated in tissue and organ morphogenesis, neural connectivity and cancer.

Fan Noise Source Diagnostic Test: LDV Measured Flow Field Results

NASA Technical Reports Server (NTRS)

Podboy, Gary C.; Krupar, Martin J.; Hughes, Christopher E.; Woodward, Richard P.

2003-01-01

Results are presented of an experiment conducted to investigate potential sources of noise in the flow developed by two 22-in. diameter turbofan models. The R4 and M5 rotors that were tested were designed to operate at nominal take-off speeds of 12,657 and 14,064 RPMC, respectively. Both fans were tested with a common set of swept stators installed downstream of the rotors. Detailed measurements of the flows generated by the two were made using a laser Doppler velocimeter system. The wake flows generated by the two rotors are illustrated through a series of contour plots. These show that the two wake flows are quite different, especially in the tip region. These data are used to explain some of the differences in the rotor/stator interaction noise generated by the two fan stages. In addition to these wake data, measurements were also made in the R4 rotor blade passages. These results illustrate the tip flow development within the blade passages, its migration downstream, and (at high rotor speeds) its merging with the blade wake of the adjacent (following) blade. Data also depict the variation of this tip flow with tip clearance. Data obtained within the rotor blade passages at high rotational speeds illustrate the variation of the mean shock position across the different blade passages.

Time-lapse imaging of neuroblast migration in acute slices of the adult mouse forebrain.

PubMed

Khlghatyan, Jivan; Saghatelyan, Armen

2012-09-12

There is a substantial body of evidence indicating that new functional neurons are constitutively generated from an endogenous pool of neural stem cells in restricted areas of the adult mammalian brain. Newborn neuroblasts from the subventricular zone (SVZ) migrate along the rostral migratory stream (RMS) to their final destination in the olfactory bulb (OB). In the RMS, neuroblasts migrate tangentially in chains ensheathed by astrocytic processes using blood vessels as a structural support and a source of molecular factors required for migration. In the OB, neuroblasts detach from the chains and migrate radially into the different bulbar layers where they differentiate into interneurons and integrate into the existing network. In this manuscript we describe the procedure for monitoring cell migration in acute slices of the rodent brain. The use of acute slices allows the assessment of cell migration in the microenvironment that closely resembling to in vivo conditions and in brain regions that are difficult to access for in vivo imaging. In addition, it avoids long culturing condition as in the case of organotypic and cell cultures that may eventually alter the migration properties of the cells. Neuronal precursors in acute slices can be visualized using DIC optics or fluorescent proteins. Viral labeling of neuronal precursors in the SVZ, grafting neuroblasts from reporter mice into the SVZ of wild-type mice, and using transgenic mice that express fluorescent protein in neuroblasts are all suitable methods for visualizing neuroblasts and following their migration. The later method, however, does not allow individual cells to be tracked for long periods of time because of the high density of labeled cells. We used a wide-field fluorescent upright microscope equipped with a CCD camera to achieve a relatively rapid acquisition interval (one image every 15 or 30 sec) to reliably identify the stationary and migratory phases. A precise identification of the duration of the stationary and migratory phases is crucial for the unambiguous interpretation of results. We also performed multiple z-step acquisitions to monitor neuroblasts migration in 3D. Wide-field fluorescent imaging has been used extensively to visualize neuronal migration. Here, we describe detailed protocol for labeling neuroblasts, performing real-time video-imaging of neuroblast migration in acute slices of the adult mouse forebrain, and analyzing cell migration. While the described protocol exemplified the migration of neuroblasts in the adult RMS, it can also be used to follow cell migration in embryonic and early postnatal brains.

Electric Signals Regulate the Directional Migration of Oligodendrocyte Progenitor Cells (OPCs) via β1 Integrin.

PubMed

Zhu, Bangfu; Nicholls, Matthew; Gu, Yu; Zhang, Gaofeng; Zhao, Chao; Franklin, Robin J M; Song, Bing

2016-11-22

The guided migration of neural cells is essential for repair in the central nervous system (CNS). Oligodendrocyte progenitor cells (OPCs) will normally migrate towards an injury site to re-sheath demyelinated axons; however the mechanisms underlying this process are not well understood. Endogenous electric fields (EFs) are known to influence cell migration in vivo, and have been utilised in this study to direct the migration of OPCs isolated from neonatal Sprague-Dawley rats. The OPCs were exposed to physiological levels of electrical stimulation, and displayed a marked electrotactic response that was dependent on β1 integrin, one of the key subunits of integrin receptors. We also observed that F-actin, an important component of the cytoskeleton, was re-distributed towards the leading edge of the migrating cells, and that this asymmetric rearrangement was associated with β1 integrin function.

Trafficking in Persons: U.S. Policy and Issues for Congress

DTIC Science & Technology

2010-02-18

incest; domestic violence; sexual assault; abusive sexual contact; prostitution; sexual exploitation; female genital mutilation ; being held hostage...approximately 600,000 to 800,000 people are trafficked across borders each year—80% of whom are female and up to 50% of whom are minors.7 If...documentation. They are often aided by corrupt police and migration officials. Female traffickers reportedly play a more prominent role in TIP than in other

Direct analysis of in-gel proteins by carbon nanotubes-modified paper spray ambient mass spectrometry.

PubMed

Han, Feifei; Yang, Yuhan; Ouyang, Jin; Na, Na

2015-02-07

The in situ and direct extraction, desorption and ionization of in-gel intact proteins after electrophoresis has been achieved by carbon nanotubes (CNTs)-modified paper spray mass spectrometry at ambient conditions. Characteristics of CNTs (including larger surface area, smaller pore diameter and enhanced conductivity) were endowed to the porous filter paper substrate by uniformly dispersing the CNTs on the filter paper. Upon applying electric potential to the CNTs-modified paper, the in-gel proteins were extracted from the gel and subsequently migrated to the tip of the filter paper by electrophoresis-like behavior for paper spray ionization, which was monitored by extracted ion chronograms. The characterizations of modified filter papers and CNTs nanoparticles further confirmed the role of CNTs in in-gel protein extraction, protein migration as well as spray ionization at the paper tip. Under optimized conditions, a mixture of cytochrome c, lysozyme and myoglobin was successfully separated by native electrophoresis and subsequently analysed by the present method, showing a limit of detection of 10 ng per gel band. The present strategy offers a new pathway for the direct detection of in-gel intact proteins at ambient conditions without any pre-treatment (e.g. digestion, chemical extraction and desalting), which exhibits potential applications in top-down proteomics.

RCP-driven α5β1 recycling suppresses Rac and promotes RhoA activity via the RacGAP1-IQGAP1 complex.

PubMed

Jacquemet, Guillaume; Green, David M; Bridgewater, Rebecca E; von Kriegsheim, Alexander; Humphries, Martin J; Norman, Jim C; Caswell, Patrick T

2013-09-16

Inhibition of αvβ3 or expression of mutant p53 promotes invasion into fibronectin (FN)-containing extracellular matrix (ECM) by enhancing Rab-coupling protein (RCP)-dependent recycling of α5β1 integrin. RCP and α5β1 cooperatively recruit receptor tyrosine kinases, including EGFR1, to regulate their trafficking and downstream signaling via protein kinase B (PKB)/Akt, which, in turn, promotes invasive migration. In this paper, we identify a novel PKB/Akt substrate, RacGAP1, which is phosphorylated as a consequence of RCP-dependent α5β1 trafficking. Phosphorylation of RacGAP1 promotes its recruitment to IQGAP1 at the tips of invasive pseudopods, and RacGAP1 then locally suppresses the activity of the cytoskeletal regulator Rac and promotes the activity of RhoA in this subcellular region. This Rac to RhoA switch promotes the extension of pseudopodial processes and invasive migration into FN-containing matrices, in a RhoA-dependent manner. Thus, the localized endocytic trafficking of α5β1 within the tips of invasive pseudopods elicits signals that promote the reorganization of the actin cytoskeleton, protrusion, and invasion into FN-rich ECM.

RCP-driven α5β1 recycling suppresses Rac and promotes RhoA activity via the RacGAP1–IQGAP1 complex

PubMed Central

Jacquemet, Guillaume; Green, David M.; Bridgewater, Rebecca E.; von Kriegsheim, Alexander; Humphries, Martin J.; Norman, Jim C.

2013-01-01

Inhibition of αvβ3 or expression of mutant p53 promotes invasion into fibronectin (FN)-containing extracellular matrix (ECM) by enhancing Rab-coupling protein (RCP)–dependent recycling of α5β1 integrin. RCP and α5β1 cooperatively recruit receptor tyrosine kinases, including EGFR1, to regulate their trafficking and downstream signaling via protein kinase B (PKB)/Akt, which, in turn, promotes invasive migration. In this paper, we identify a novel PKB/Akt substrate, RacGAP1, which is phosphorylated as a consequence of RCP-dependent α5β1 trafficking. Phosphorylation of RacGAP1 promotes its recruitment to IQGAP1 at the tips of invasive pseudopods, and RacGAP1 then locally suppresses the activity of the cytoskeletal regulator Rac and promotes the activity of RhoA in this subcellular region. This Rac to RhoA switch promotes the extension of pseudopodial processes and invasive migration into FN-containing matrices, in a RhoA-dependent manner. Thus, the localized endocytic trafficking of α5β1 within the tips of invasive pseudopods elicits signals that promote the reorganization of the actin cytoskeleton, protrusion, and invasion into FN-rich ECM. PMID:24019536

Cancer-associated fibroblasts promote directional cancer cell migration by aligning fibronectin.

PubMed

Erdogan, Begum; Ao, Mingfang; White, Lauren M; Means, Anna L; Brewer, Bryson M; Yang, Lijie; Washington, M Kay; Shi, Chanjuan; Franco, Omar E; Weaver, Alissa M; Hayward, Simon W; Li, Deyu; Webb, Donna J

2017-11-06

Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF-cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α-mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration. © 2017 Erdogan et al.

Cancer-associated fibroblasts promote directional cancer cell migration by aligning fibronectin

PubMed Central

Ao, Mingfang; White, Lauren M.; Means, Anna L.; Yang, Lijie; Washington, M. Kay; Franco, Omar E.; Li, Deyu; Webb, Donna J.

2017-01-01

Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF–cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α–mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration. PMID:29021221

Nectin-like molecule 1 inhibits the migration and invasion of U251 glioma cells by regulating the expression of an extracellular matrix protein osteopontin.

PubMed

Yin, Bin; Li, Ke-han; An, Tai; Chen, Tao; Peng, Xiao-zhong

2010-06-01

To investigate the molecular mechanism of nectin-like molecule 1 (NECL1) inhibiting the migration and invasion of U251 glioma cells. We infected U251 glioma cells with adeno-nectin-like molecule 1 (Ad-NECL1) or empty adenovirus (Ad). Transwell and wound healing assays were performed to observe the migration of U251 cells incubated with the cell supernatant from Ad-NECL1 or Ad infected U251 cells. DNA microarray was applied to screen the gene expression profile after the restoration of NECL1 in U251 glioma cell lines. The differential expression of osteopontin (OPN), a gene related to migration and invasion, was further analyzed with semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry. The restoration of NECL1 inhibited migration of U251 cells significantly (P<0.05). Altogether 195 genes were found differentially expressed by microarray, in which 175 were up-regulated and 20 down-regulated, including 9 extracellular matrix proteins involved in the migration of cells. Both mRNA and protein expressions of OPN, the most markedly reduced extracellular matrix protein, were found decreased in U251 cells after restoration of NECL1. Immunohistochemical assay also detected an increase of OPN in glioma tissues, related with the progressing of malignant grade. A link might exist between NECL1 and the extracellular matrix protein OPN in inhibiting the migration and invasion of U251 glioma cells.

Insulin promotes cell migration by regulating PSA-NCAM.

PubMed

Monzo, Hector J; Coppieters, Natacha; Park, Thomas I H; Dieriks, Birger V; Faull, Richard L M; Dragunow, Mike; Curtis, Maurice A

2017-06-01

Cellular interactions with the extracellular environment are modulated by cell surface polysialic acid (PSA) carried by the neural cell adhesion molecule (NCAM). PSA-NCAM is involved in cellular processes such as differentiation, plasticity, and migration, and is elevated in Alzheimer's disease as well as in metastatic tumour cells. Our previous work demonstrated that insulin enhances the abundance of cell surface PSA by inhibiting PSA-NCAM endocytosis. In the present study we have identified a mechanism for insulin-dependent inhibition of PSA-NCAM turnover affecting cell migration. Insulin enhanced the phosphorylation of the focal adhesion kinase leading to dissociation of αv-integrin/PSA-NCAM clusters, and promoted cell migration. Our results show that αv-integrin plays a key role in the PSA-NCAM turnover process. αv-integrin knockdown stopped PSA-NCAM from being endocytosed, and αv-integrin/PSA-NCAM clusters co-labelled intracellularly with Rab5, altogether indicating a role for αv-integrin as a carrier for PSA-NCAM during internalisation. Furthermore, inhibition of p-FAK caused dissociation of αv-integrin/PSA-NCAM clusters and counteracted the insulin-induced accumulation of PSA at the cell surface and cell migration was impaired. Our data reveal a functional association between the insulin/p-FAK-dependent regulation of PSA-NCAM turnover and cell migration through the extracellular matrix. Most importantly, they identify a novel mechanism for insulin-stimulated cell migration. Copyright © 2017 Elsevier Inc. All rights reserved.

Optical control demonstrates switch-like PIP3 dynamics underlying the initiation of immune cell migration

PubMed Central

Karunarathne, W. K. Ajith; Giri, Lopamudra; Patel, Anilkumar K.; Venkatesh, Kareenhalli V.; Gautam, N.

2013-01-01

There is a dearth of approaches to experimentally direct cell migration by continuously varying signal input to a single cell, evoking all possible migratory responses and quantitatively monitoring the cellular and molecular response dynamics. Here we used a visual blue opsin to recruit the endogenous G-protein network that mediates immune cell migration. Specific optical inputs to this optical trigger of signaling helped steer migration in all possible directions with precision. Spectrally selective imaging was used to monitor cell-wide phosphatidylinositol (3,4,5)-triphosphate (PIP3), cytoskeletal, and cellular dynamics. A switch-like PIP3 increase at the cell front and a decrease at the back were identified, underlying the decisive migratory response. Migration was initiated at the rapidly increasing switch stage of PIP3 dynamics. This result explains how a migratory cell filters background fluctuations in the intensity of an extracellular signal but responds by initiating directionally sensitive migration to a persistent signal gradient across the cell. A two-compartment computational model incorporating a localized activator that is antagonistic to a diffusible inhibitor was able to simulate the switch-like PIP3 response. It was also able simulate the slow dissipation of PIP3 on signal termination. The ability to independently apply similar signaling inputs to single cells detected two cell populations with distinct thresholds for migration initiation. Overall the optical approach here can be applied to understand G-protein–coupled receptor network control of other cell behaviors. PMID:23569254

Optical control demonstrates switch-like PIP3 dynamics underlying the initiation of immune cell migration.

PubMed

Karunarathne, W K Ajith; Giri, Lopamudra; Patel, Anilkumar K; Venkatesh, Kareenhalli V; Gautam, N

2013-04-23

There is a dearth of approaches to experimentally direct cell migration by continuously varying signal input to a single cell, evoking all possible migratory responses and quantitatively monitoring the cellular and molecular response dynamics. Here we used a visual blue opsin to recruit the endogenous G-protein network that mediates immune cell migration. Specific optical inputs to this optical trigger of signaling helped steer migration in all possible directions with precision. Spectrally selective imaging was used to monitor cell-wide phosphatidylinositol (3,4,5)-triphosphate (PIP3), cytoskeletal, and cellular dynamics. A switch-like PIP3 increase at the cell front and a decrease at the back were identified, underlying the decisive migratory response. Migration was initiated at the rapidly increasing switch stage of PIP3 dynamics. This result explains how a migratory cell filters background fluctuations in the intensity of an extracellular signal but responds by initiating directionally sensitive migration to a persistent signal gradient across the cell. A two-compartment computational model incorporating a localized activator that is antagonistic to a diffusible inhibitor was able to simulate the switch-like PIP3 response. It was also able simulate the slow dissipation of PIP3 on signal termination. The ability to independently apply similar signaling inputs to single cells detected two cell populations with distinct thresholds for migration initiation. Overall the optical approach here can be applied to understand G-protein-coupled receptor network control of other cell behaviors.

Cell migration is another player of the minute virus of mice infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcin, Pierre O.; Panté, Nelly, E-mail: pante@zoology.ubc.ca

2014-11-15

The parvovirus minute virus of mice, prototype strain (MVMp), preferentially infects and kills cancer cells. This intrinsic MVMp oncotropism may depend in part on the early stages of MVMp infection. To test this hypothesis, we investigated the early events of MVMp infection in mouse LA9 fibroblasts and a highly invasive mouse mammary tumor cell line derived from polyomavirus middle T antigen-mediated transformation. Using a combination of fluorescence and electron microscopy, we found that various parameters of the cell migration process affect MVMp infection. We show that, after binding to the plasma membrane, MVMp particles rapidly cluster at the leading edgemore » of migrating cells, which exhibit higher levels of MVMp uptake than non-motile cells. Moreover, promoting cell migration on a fibronectin matrix increased MVMp infection, and induction of epithelial–mesenchymal transition allowed MVMp replication in non-permissive epithelial cells. Hence, we propose that cell migration influences the early stages of MVMp infection. - Highlights: • We document early steps of MVMp infection. • We report that a fibronectin matrix promotes MVMp infection. • We show that cellular migration plays a role in MVMp uptake. • We show that epithelial–mesenchymal transition allows MVMp replication.« less

Modeling and analysis of collective cell migration in an in vivo three-dimensional environment

PubMed Central

Dai, Wei; Prasad, Mohit; Luo, Junjie; Gov, Nir S.; Montell, Denise J.

2016-01-01

A long-standing question in collective cell migration has been what might be the relative advantage of forming a cluster over migrating individually. Does an increase in the size of a collectively migrating group of cells enable them to sample the chemical gradient over a greater distance because the difference between front and rear of a cluster would be greater than for single cells? We combined theoretical modeling with experiments to study collective migration of the border cells in-between nurse cells in the Drosophila egg chamber. We discovered that cluster size is positively correlated with migration speed, up to a particular point above which speed plummets. This may be due to the effect of viscous drag from surrounding nurse cells together with confinement of all of the cells within a stiff extracellular matrix. The model predicts no relationship between cluster size and velocity for cells moving on a flat surface, in contrast to movement within a 3D environment. Our analyses also suggest that the overall chemoattractant profile in the egg chamber is likely to be exponential, with the highest concentration in the oocyte. These findings provide insights into collective chemotaxis by combining theoretical modeling with experimentation. PMID:27035964

Effects of inversion on plastid position and gravitropism in Ceratodon protonemata

NASA Technical Reports Server (NTRS)

Schwuchow, J.; Sack, F. D.

1993-01-01

When dark-grown tip cells of protonemata of the moss Ceratodon purpureus are turned to the horizontal, plastids first sediment towards gravity in a specific zone and then the tip curves upward. To determine whether gravitropism and plastid sedimentation occur in other orientations, protonemata were reoriented to angles other than 90 degrees. Qualitative and quantitative light microscopic observations show that plastid sedimentation along the cell axis occurs in both upright and inverted cells. However, only some plastids fall and sedimentation is incomplete; plastids remain distributed throughout the length of the cell, and those plastids that sediment do not fall all the way to the bottom of the cell. Tip cells are gravitropic regardless of stimulation angle, and as in higher plants, the maximal rate of initial curvature is in response to a 120 degrees reorientation. Infrared videomicroscopy, time-lapse studies of living, inverted protonemata indicate that amyloplast sedimentation precedes upward curvature. Together, these data further support (i) the hypothesis that amyloplast sedimentation functions in gravitropic sensing in these cells, and (ii) the idea that gravity affected the evolution of cell organization.