Project description:BackgroundThe behaviour of tumour cells depends on factors such as genetics and the tumour microenvironment. The latter plays a crucial role in normal mammary gland development and also in breast cancer initiation and progression. Breast cancer tissues tend to be highly desmoplastic and dense matrix as a pre-existing condition poses one of the highest risk factors for cancer development. However, matrix influence on tumour cell gene expression and behaviour such as cell migration is not fully elucidated.ResultsWe generated high-density (HD) matrices that mimicked tumour collagen content of 20?mg/cm3 that were ~14-fold stiffer than low-density (LD) matrix of 1?mg/cm3. Live-cell imaging showed breast cancer cells utilizing cytoplasmic streaming and cell body contractility for migration within HD matrix. Cell migration was blocked in the presence of both the ROCK inhibitor, Y-27632, and the MMP inhibitor, GM6001, but not by the drugs individually. This suggests roles for ROCK1 and MMP in cell migration are complicated by compensatory mechanisms. ROCK1 expression and protein activity, were significantly upregulated in HD matrix but these were blocked by treatment with a histone deacetylase (HDAC) inhibitor, MS-275. In HD matrix, the inhibition of ROCK1 by MS-275 was indirect and relied upon protein synthesis and Notch1. Inhibition of Notch1 using pooled siRNA or DAPT abrogated the inhibition of ROCK1 by MS-275.ConclusionIncreased matrix density elevates ROCK1 activity, which aids in cell migration via cell contractility. The upregulation of ROCK1 is epigenetically regulated in an indirect manner involving the repression of Notch1. This is demonstrated from inhibition of HDACs by MS-275, which caused an upregulation of Notch1 levels leading to blockade of ROCK1 expression.
Project description:Epstein-Barr virus-induced gene 2 (EBI2, also known as GPR183) is a G-protein-coupled receptor that is required for humoral immune responses; polymorphisms in the receptor have been associated with inflammatory autoimmune diseases. The natural ligand for EBI2 has been unknown. Here we describe the identification of 7?,25-dihydroxycholesterol (also called 7?,25-OHC or 5-cholesten-3?,7?,25-triol) as a potent and selective agonist of EBI2. Functional activation of human EBI2 by 7?,25-OHC and closely related oxysterols was verified by monitoring second messenger readouts and saturable, high-affinity radioligand binding. Furthermore, we find that 7?,25-OHC and closely related oxysterols act as chemoattractants for immune cells expressing EBI2 by directing cell migration in vitro and in vivo. A critical enzyme required for the generation of 7?,25-OHC is cholesterol 25-hydroxylase (CH25H). Similar to EBI2 receptor knockout mice, mice deficient in CH25H fail to position activated B cells within the spleen to the outer follicle and mount a reduced plasma cell response after an immune challenge. This demonstrates that CH25H generates EBI2 biological activity in vivo and indicates that the EBI2-oxysterol signalling pathway has an important role in the adaptive immune response.
Project description:Vertebrate hematopoietic stem cells are derived from vental mesoderm, which is postulated to migrate to both extra- and intraembryonic positions during gastrula and neurula stages. Extraembryonic migration has previously been documented, but the origin and migration of intraembryonic hematopoietic cells have not been visualized. The zebrafish and most other teleosts do not form yolk sac blood islands during early embryogenesis, but instead hematopoiesis occurs solely in a dorsal location known as the intermediate cell mass (IM) or Oellacher. In this report, we have isolated cDNAs encoding zebrafish homologs of the hematopoietic transcription factors GATA-1 and GATA-2 and have used these markers to determine that the IM is formed from mesodermal cells in a posterior-lateral position on the yolk syncytial layer of the gastrula yolk sac. Surprisingly, cells of the IM then migrate anteriorly through most of the body length prior to the onset of active circulation and exit onto the yolk sac. These findings support a hypothesis in which the hematopoietic program of vertebrates is established by variations in homologous migration pathways of extra- and intraembryonic progenitors.
Project description:ObjectivesCell migration has a key role in cancer metastasis, which contributes to drug resistance and tumour recurrence. Better understanding of the mechanisms involved in this process will potentially reveal new drug targets for cancer therapy. Fer is a non-receptor protein tyrosine kinase aberrantly expressed in various human cancers, whereas its role in tumour progression remains elusive.Materials and methodsTransgenic flies and epigenetic analysis were employed to investigate the role of Drosophila Fer (FER) in cell migration and underlying mechanisms. Co-immunoprecipitation assay was used to monitor the interaction between FER and Drosophila JNK (Bsk). The conservation of Fer in regulating JNK signalling was explored in mammalian cancer and non-cancer cells.ResultsOverexpression of FER triggered cell migration and activated JNK signalling in the Drosophila wing disc. Upregulation and downregulation in the basal activity of Bsk exacerbated and eliminated FER-mediated migration, respectively. In addition, loss of FER blocked signal transduction of the JNK pathway. Specifically, FER interacted with and promoted the activity of Bsk, which required both the kinase domain and the C-terminal of Bsk. Lastly, Fer regulated JNK activities in mammalian cells.ConclusionsOur study reveals FER as a positive regulator of JNK-mediated cell migration and suggests its potential role as a therapeutic target for cancer metastasis.
Project description:During cancer metastasis, tumor cells undergo significant deformation in order to traverse through endothelial cell junctions in the walls of blood vessels. As cells pass through narrow gaps, smaller than the nuclear diameter, the spatial configuration of chromatin must change along with the distribution of nuclear enzymes. Nuclear stiffness is an important determinant of the ability of cells to undergo transendothelial migration, yet no studies have been conducted to assess whether tumor cell cytoskeletal or nuclear stiffness changes during this critical process in order to facilitate passage. To address this question, we employed two non-contact methods, Brillouin confocal microscopy (BCM) and confocal reflectance quantitative phase microscopy (QPM), to track the changes in mechanical properties of live, transmigrating tumor cells in an in vitro collagen gel platform. Using these two imaging modalities to study transmigrating MDA-MB-231, A549, and A375 cells, we found that both the cells and their nuclei soften upon extravasation and that the nuclear membranes remain soft for at least 24 h. These new data suggest that tumor cells adjust their mechanical properties in order to facilitate extravasation.
Project description:Cell migration is orchestrated by a complicated mechanochemical system. However, few cell migration models take into account the coupling between the biochemical network and mechanical factors. Here, we construct a mechanochemical cell migration model to study the cell tension effect on cell migration. Our model incorporates the interactions between Rac-GTP, Rac-GDP, F-actin, myosin, and cell tension, and it is very convenient in capturing the change of cell shape by taking the phase field approach. This model captures the characteristic features of cell polarization, cell shape change, and cell migration modes. It shows that cell tension inhibits migration ability monotonically when cells are applied with persistent external stimuli. On the other hand, if random internal noise is significant, the regulation of cell tension exerts a nonmonotonic effect on cell migration. Because the increase of cell tension hinders the formation of multiple protrusions, migration ability could be maximized at intermediate cell tension under random internal noise. These model predictions are consistent with our single-cell experiments and other experimental results.
Project description:Although adhesive interactions between cells and nanostructured interfaces have been studied extensively, there is a paucity of data on how nanostructured interfaces repel cells by directing cell migration and cell-colony organization. Here, by using multiphoton ablation lithography to pattern surfaces with nanoscale craters of various aspect ratios and pitches, we show that the surfaces altered the cells' focal-adhesion size and distribution, thus affecting cell morphology, migration and ultimately localization. We also show that nanocrater pitch can disrupt the formation of mature focal adhesions to favour the migration of cells towards higher-pitched regions, which present increased planar area for the formation of stable focal adhesions. Moreover, by designing surfaces with variable pitch but constant nanocrater dimensions, we were able to create circular and striped cellular patterns. Our surface-patterning approach, which does not involve chemical treatments and can be applied to various materials, represents a simple method to control cell behaviour on surfaces.
Project description:Cell migration is a central biological process that requires fine coordination of molecular events in time and space. A deregulation of the migratory phenotype is also associated with pathological conditions including cancer where cell motility has a causal role in tumor spreading and metastasis formation. Thus cell migration is of critical and strategic importance across the complex disease spectrum as well as for the basic understanding of cell phenotype. Experimental studies of the migration of cells in monolayers are often conducted with 'wound healing' assays. Analysis of these assays has traditionally relied on how the wound area changes over time. However this method does not take into account the shape of the wound. Given the many options for creating a wound healing assay and the fact that wound shape invariably changes as cells migrate this is a significant flaw. Here we present a novel software package for analyzing concerted cell velocity in wound healing assays. Our method encompasses a wound detection algorithm based on cell confluency thresholding and employs a Bayesian approach in order to estimate concerted cell velocity with an associated likelihood. We have applied this method to study the effect of siRNA knockdown on the migration of a breast cancer cell line and demonstrate that cell velocity can track wound healing independently of wound shape and provides a more robust quantification with significantly higher signal to noise ratios than conventional analyses of wound area. The software presented here will enable other researchers in any field of cell biology to quantitatively analyze and track live cell migratory processes and is therefore expected to have a significant impact on the study of cell migration, including cancer relevant processes. Installation instructions, documentation and source code can be found at http://bowhead.lindinglab.science licensed under GPLv3.
Project description: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.
Project description:Directed cell migration is an important step in effective wound healing and requires the dynamic control of the formation of cell-extracellular matrix interactions. Plasma fibronectin is an extracellular matrix glycoprotein present in blood plasma that plays crucial roles in modulating cellular adhesion and migration and thereby helping to mediate all steps of wound healing. In order to seek safe sources of plasma fibronectin for its practical use in wound dressing, we isolated fibronectin from human (homo) and porcine plasma and demonstrated that both have a similar ability as a suitable substrate for the stimulation of cell adhesion and for directing cell migration. In addition, we also defined the N-glycosylation sites and N-glycans present on homo and porcine plasma fibronectin. These N-glycosylation modifications of the plasma fibronectin synergistically support the integrin-mediated signals to bring about mediating cellular adhesion and directed cell migration. This study not only determines the important function of N-glycans in both homo and porcine plasma fibronectin-mediated cell adhesion and directed cell migration, but also reveals the potential applications of porcine plasma fibronectin if it was applied as a material for clinical wound healing and tissue repair.