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1.
Cell–cell interactions among cell types constituting the fetal liver such as hepatoblasts, stellate cells and endothelial
cells lead to functional lobule development. The present study was undertaken to investigate hepatic histogenesis in the primary
culture of E12.5 mouse livers, including cell–cell and cell–matrix interactions. Fetal livers were dispersed with protease
treatment and cultured for 5 days. Cellular adhesion of each hepatic cell type, gene expression and extracellular matrix deposition
were analyzed by immunohistochemistry and immunoblotting. Immunohistochemical analysis demonstrated that the primary culture
of fetal liver cells contained at least hepatoblasts, mesenchymal cells, endothelial cells, hemopoietic cells and Kupffer
cells. Although hepatoblasts, mesenchymal cells, and endothelial cells aggregated separately in the initial step, they then
formed a spheroid together, adhering to the glass slide, which led to the formation of flattened hepatic organoids. Hepatoblasts
more preferentially adhered to mesenchymal cells than endothelial cells. Several extracellular matrix depositions were seen
in aggregates consisting of at least hepatoblasts and mesenchymal cells within 12 h, but were poor in those lacking hepatoblasts.
These data show that the primary culture of fetal liver cells contains most cell types constituting fetal livers, and may
be useful for studying cell–cell interactions during liver development. 相似文献
2.
Localization and activity of calmodulin is involved in cell–cell adhesion of tumor cells and endothelial cells in response to hypoxic stress 总被引:2,自引:0,他引:2
Shen WG Peng WX Shao Y Xu JF Dai G Zhang Y Pan FY Li CJ 《Cell biology and toxicology》2007,23(5):323-335
Adhesion of tumor cells to endothelial cells is known to be involved in the hematogenous metastasis of cancer, which is regulated
by hypoxia. Hypoxia is able to induce a significant increase in free intracellular Ca2+ levels in both tumor cells and endothelial cells. Here, we investigate the regulatory effects of calmodulin (CaM), an intracellular
calcium mediator, on tumor cell–endothelial cell adhesion under hypoxic conditions. Hypoxia facilitates HeLa cell–ECV304 endothelial
cell adhesion, and results in actin cytoskeleton rearrangement in both endothelial cells and tumor cells. Suppression of CaM
activation by CaM inhibitor W-7 disrupts actin cytoskeleton organization and CaM distribution in the cell–cell contact region,
and thus inhibits cell–cell adhesion. CaM inhibitor also downregulates hypoxia-induced HIF-1-dependent gene expression. These
results suggest that the Ca2+-CaM signaling pathway might be involved in tumor cell-endothelial cell adhesion, and that co-localization of CaM and actin
at cell–cell contact regions might be essential for this process under hypoxic stress.
W.-G. Shen and W.-X. Peng Contributed to this paper equally 相似文献
3.
Melissa Morley Claire Jones Mandeep Sidhu Vishal Gupta Suzanne M. Bernier Walter J. Rushlow Daniel J. Belliveau 《Cell and tissue research》2010,340(2):229-242
Gap junction intercellular communication and cell–cell adhesion are essential for maintaining a normal cellular phenotype,
including the control of growth and proliferation. Loss of either cell–cell adhesion or communication is common in cancers,
while restoration of function is associated with tumor suppression. Protein kinase C (PKC) isozymes regulate a broad spectrum
of cellular functions including growth and proliferation, and their overexpression has been correlated with carcinogenesis.
Consequently, PKC inhibitors are currently undergoing clinical trials as an anti-cancer agents although the precise cellular
alterations induced by PKC inhibitors remain to be elucidated. In the current study, the effects of PKC inhibitors on cell
interactions were investigated using human neuroblastoma (IMR32, SKNMC, and SHSY-5Y) cell lines. An analysis of intercellular
communication revealed an increase in gap junctional coupling with PKC inhibition. The observed increase in coupling was not
associated with a change in Connexin43 distribution or an alteration of phosphorylation status of the protein. There was also
an increase in cell–cell adhesion with PKC inhibitor treatment as indicated by a cell aggregation assay. Therefore, the growth
suppressive abilities of PKC inhibition on tumors may be due to the cancer suppressive effects of increased gap junction intercellular
communication and cell–cell adhesion. 相似文献
4.
The mammary gland undergoes hormonally controlled cycles of pubertal maturation, pregnancy, lactation, and involution, and
these processes rely on complex signaling mechanisms, many of which are controlled by cell–cell and cell–matrix adhesion.
The adhesion of epithelial cells to the extracellular matrix initiates signaling mechanisms that have an impact on cell proliferation,
survival, and differentiation throughout lactation. The control of integrin expression on the mammary epithelial cells, the
composition of the extracellular matrix and the presence of secreted matricellular proteins all contribute to essential adhesion
signaling during lactogenesis. In vitro and in vivo studies, including the results from genetically engineered mice, have
shed light on the regulation of these processes at the cell and tissue level and have led to increased understanding of the
essential signaling components that are regulated in temporal and cell specific manner during lactogenesis. Recent studies
suggest that a secreted matricellular protein, CTGF/CCN2, may play a role in lactogenic differentiation through binding to
β1 integrin complexes, enhancing the production of extracellular matrix components and contributions to cell adhesion signaling. 相似文献
5.
DePasquale JA 《Histochemistry and cell biology》1999,112(5):341-350
In response to treatment with 17β-estradiol, MCF-7 human breast carcinoma cells undergo a marked rearrangement of the F-actin
cytoskeleton. The most conspicuous aspect of this rearrangement is the formation of an extensive array of lamellipodial structures
which are situated beneath cell clusters. Treatment of cells with 17β-estradiol in the presence of the anti-estrogen ICI182,780
suppressed the development of the lamellipodial structures, indicating that this cytoskeletal rearrangement is mediated by
the estrogen receptor. Time-lapse, video-enhanced, differential interference contrast microscopy reveals that the lamellipodial
structures are actively motile beneath cell clusters. Furthermore, the lamellipodial structures form few focal contacts with
the underlying substrate of the coverslip, as evidenced by either interference reflection microscopy or staining for the focal
contact protein talin, indicating that these structures are not strongly adhered to the substratum. Immunofluorescence localization
of E-cadherin indicates that this cell–cell adhesion receptor is present within these structures as either adhesion plaque-
or point contact-like depositions. These findings implicate the cadherin-based cell–cell adhesion system in supporting tumor
cell motility over adjacent cell surfaces via discrete adhesive structures which are associated with motile lamellipodia.
Accepted: 1 September 1999 相似文献
6.
《Cell biology international reports》1984,8(1):65-77
Trifluoperazine (TFP) at 5μM completely blocks the formation of adhesion plaque complexes (adhaerens junctions) between aggregating fibroblasts; the drug at this same concentration did not prevent the cells from producing aggregates of normal size and appearance. Implicit in this finding is that aggregation does not rely on adhesion plaque complex formation. When thymidine-3 H labelled 16C and unlabelled BHK fibroblast cells were experimentally combined to form aggregates in which the cells were initially uniformly distributed, the 16C cells, which produced adhesion plaque complexes within minutes and in greater numbers than did BHK cells, congregated in an internal position after the aggregates had been cultured for 12h. This redistribution of the cells, indicated by the positioning of the labelled 16C nuclei, did not occur when the aggregates were exposed to TFP. Thus cell sorting, unlike aggregation, seems to be reliant on the formation of adhesion plaque complexes. 相似文献
7.
Endothelial cell adhesion and barrier function play a critical role in many biological and pathophysiological processes. The
decomposition of endothelial cell adhesion and barrier function into cell–cell and cell–matrix components using frequency
dependent cellular micro-impedance measurements has, therefore, received widespread application. Few if any studies, however,
have examined the precision of these model parameters. This study presents a parameter sensitivity analysis of a representative
cellular barrier function model using a concise geometric formulation that includes instrumental data acquisition settings.
Both model state dependence and instrumental noise distributions are accounted for within the framework of Riemannian manifold
theory. Experimentally acquired microimpedance measurements of attached endothelial cells define the model state domain, while
experimentally measured noise statistics define the data space Riemannian metric based on the Fisher information matrix. The
results of this analysis show that the sensitivity of cell–cell and cell–matrix impedance components are highly model state
dependent and several well defined regions of low precision exist. The results of this study further indicate that membrane
resistive components can significantly reduce the precision of the remaining parameters in these models.
This work was supported by a National Science Foundation CAREER Award (AE), BES-0238905, and in part by the American Heart
Association under Grant 0265029B (AE). 相似文献
8.
Liu XM Liu H Wu BC Li SC Ye LL Wang QW Huang PT Chen ZL 《Applied microbiology and biotechnology》2006,72(6):1144-1151
Cells of the human embryonic kidney cell line (HEK 293) grown in repeated suspension and perfusion systems were characterized and described. Cell aggregates that formed immediately after the HEK 293 cells were inoculated in stirred vessels in serum-containing Dulbecco’s modified Eagle’s medium (D-MEM)/F-12 medium. The mean diameter of the cell aggregates reflecting the aggregate size increased with culture time, shifting from 63 to 239 μm after 1 and 8 days of culture in spinner flasks, respectively. No significant differences in cell performance were observed between HEK 293 cell populations grown as suspended aggregates and those grown as anchored monolayers. Replacing the D-MEM/F-12 with CD 293 medium caused the compact spherical cell aggregates to dissociate into single cells and small irregular aggregates without any apparent effect on cell performance. Moreover, the spherical cell aggregates could reform from individual cells and small aggregates when exposed to the serum-containing D-MEM/F-12 dominant medium. Perfusion culture of HEK 293 cells grown as suspended aggregates in a 7.5-l stirred tank bioreactor for 17 days resulted in a maximum viable cell density of 1.2×107 cells ml−1. These results demonstrate the feasibility and proof-of-concept for using aggregates as an immobilization system in large-scale stirred bioreactors because a small-scale culture can be used as easily as the inoculum for larger bioreactors.The first two authors contributed equally to this work. 相似文献
9.
Impaired formation of desmosomal junctions in ADPKD epithelia 总被引:1,自引:1,他引:0
Russo RJ Husson H Joly D Bukanov NO Patey N Knebelmann B Ibraghimov-Beskrovnaya O 《Histochemistry and cell biology》2005,124(6):487-497
Mutations in polycystin-1 (PC-1) are responsible for autosomal dominant polycystic kidney disease (ADPKD), characterized by
formation of fluid-filled tubular cysts. The PC-1 is a multifunctional protein essential for tubular differentiation and maturation
found in desmosomal junctions of epithelial cells where its primary function is to mediate cell–cell adhesion. To address
the impact of mutated PC-1 on intercellular adhesion, we have analyzed the structure/function of desmosomal junctions in primary
cells derived from ADPKD cysts. Primary epithelial cells from normal kidney showed co-localization of PC-1 and desmosomal
proteins at cell–cell contacts. A striking difference was seen in ADPKD cells, where PC-1 and desmosomal proteins were lost
from the intercellular junction membrane, despite unchanged protein expression levels. Instead, punctate intracellular expression
for PC-1 and desmosomal proteins was detected. The N-cadherin, but not E-cadherin was expressed in adherens junctions of ADPKD
cells. These data together with co-sedimentation analysis demonstrate that, in the absence of functional PC-1, desmosomal
junctions cannot be properly assembled and remain sequestered in cytoplasmic compartments. Taken together, our results demonstrate
that PC-1 is crucial for formation of intercellular contacts. We propose that abnormal expression of PC-1 causes disregulation
of cellular adhesion complexes leading to increased proliferation, loss of polarity and, ultimately, cystogenesis. 相似文献
10.
We have previously assumed the presence of two mechanisms for the aggregation of Chinese hamster V79 cells, the Ca2+ -dependent one and the Ca2+ -independent one. In order to examine if each of these mechanisms contributed differently to the various aspects of cell aggregation, the morphology of V79 cell aggregates, pretreated so that they were provided with only one of the two adhesion mechanisms, was compared by light and electron microscopy. The adhesion among cells with only the Ca2+ -dependent mechanism was very tight, with the formation of gap and intermediate junctions. Cells were arranged in a rod or dendric shape in aggregates. In aggregates of cells with only the Ca2+ -independent mechanism, cells were loosely attached to each other without the formation of specialized junctions and the aggregates were of globular shape. In aggregates of cells with both mechanisms, both characteristics of the above two aggregates were found. Four clones of V79 cells, which formed colonies with different morphology when they were grown in soft agar, were isolated. It was found that such differences were due to the different activity of the Ca2+ -independent mechanism among these clones. These results suggested that the two adhesion mechanisms play different roles in the cell arrangement in aggregates. 相似文献
11.
Tetsuichiro Inai Akihito Sengoku Eiji Hirose Hiroshi Iida Yosaburo Shibata 《Histochemistry and cell biology》2009,131(6):681-690
Claudins constitute tight junction (TJ) strands. In order to examine the function of the second extracellular loop (ECL2),
we constructed 1CLΔFY and 1CLΔPL in which highly conserved amino acids, FY or PL, in the ECL2 of mouse claudin-1 were deleted.
They were then tagged with either EGFP at the NH2-terminus (EGFP1CLΔFY and EGFP1CLΔPL) or the myc-epitope at the COOH-terminus (1CLΔFYmyc and 1CLΔPLmyc). The expression of
EGFP1CLΔFY and EGFP1CLΔPL in TJ-free HEK293 cells formed TJ strands resembling those formed by wild-type claudin-1. The expression
of 1CLΔPLmyc in TJ-bearing MDCK II cells induced aberrant TJ strands in the lateral plasma membranes whose intramembranous
particles were almost equally distributed in the P- and E-face. In contrast, 1CLΔFYmyc formed aggregates of short continuous
strands which were frequently associated with vesicle-like structures. Coculture experiments with MDCK II cells showed that
1CLΔPLmyc was localized at heterotypic cell–cell junctions but 1CLΔFYmyc was not. These results suggest that changes in the
TJ morphology due to the expression of either 1CLΔFYmyc or 1CLΔPLmyc may be caused by some factors specific to epithelial
MDCK II cells including endogenous claudins.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Ling Li Jun Qin Qiang Feng Hao Tang Rong Liu Liqing Xu Zhinan Chen 《Molecular biotechnology》2011,47(1):9-17
While heparin has been shown to eliminate cell aggregation in suspension adaptations of insect and HEK293 cells for virus-based
cell cultures, the role of heparin in long period serum-free suspension adaptation of the anchorage-dependent Chinese hamster
ovary (CHO) cell lines remains inconclusive. In this paper, we explore the potential application of heparin in suspension
adaptation of CHO cell line which produces an anti-human chimeric antibody cHAb18. Heparin showed a concentration-dependent
inhibition of CHO–TS28 cell-to-cell adhesion, with a significant inhibitory effect occurring when the concentration exceeded
250 μg/ml (P < 0.001). Heparin also exhibited a cell aggregation elimination role at all concentrations (P < 0.001). Furthermore, heparin promoted cell growth and antibody secretion, with the highest cell density ((99.83 ± 12.21) × 104 cells/ml, P = 0.034) and maximum antibody yield ((9.46 ± 0.94) mg/l, P < 0.001) both occurring at 250 μg/ml heparin. When agitated, cell aggregates were effectively dispersed by 250 μg/ml heparin
and a single-cell suspension culture process was promoted. In suspension adapted CHO–TS28 cells, cell growth rates and specific
antibody productivity were maintained; while antigen-binding activity improved slightly. Together, our results show that heparin
may promote suspension adaptation of anchorage-depended CHO cells by resisting cell aggregation without reducing cell growth,
antibody secretion, and antigen-binding activity. 相似文献
13.
Jacob P. Hoj John A. DavisKendra E. Fullmer David J. MorrellNicholas E. Saguibo Jeffrey T. SchulerKevin J. Tuttle Marc D.H. Hansen 《Experimental cell research》2014
Epithelial scattering occurs when cells disassemble cell–cell junctions, allowing individual epithelial cells to act in a solitary manner. Epithelial scattering occurs frequently in development, where it accompanies epithelial–mesenchymal transitions and is required for individual cells to migrate and invade. While migration and invasion have received extensive research focus, how cell–cell junctions are detached remains poorly understood. An open debate has been whether disruption of cell–cell interactions occurs by remodeling of cell–cell adhesions, increased traction forces through cell substrate adhesions, or some combination of both processes. Here we seek to examine how changes in adhesion and contractility are coupled to drive detachment of individual epithelial cells during hepatocyte growth factor (HGF)/scatter factor-induced EMT. We find that HGF signaling does not alter the strength of cell–cell adhesion between cells in suspension, suggesting that changes in cell–cell adhesion strength might not accompany epithelial scattering. Instead, cell–substrate adhesion seems to play a bigger role, as cell–substrate adhesions are stronger in cells treated with HGF and since rapid scattering in cells treated with HGF and TGFβ is associated with a dramatic increase in focal adhesions. Increases in the pliability of the substratum, reducing cells ability to generate traction on the substrate, alter cells? ability to scatter. Further consistent with changes in substrate adhesion being required for cell–cell detachment during EMT, scattering is impaired in cells expressing both active and inactive RhoA mutants, though in different ways. In addition to its roles in driving assembly of both stress fibers and focal adhesions, RhoA also generates myosin-based contractility in cells. We therefore sought to examine how RhoA-dependent contractility contributes to cell–cell detachment. Inhibition of Rho kinase or myosin II induces the same effect on cells, namely an inhibition of cell scattering following HGF treatment. Interestingly, restoration of myosin-based contractility in blebbistatin-treated cells results in cell scattering, including global actin rearrangements. Scattering is reminiscent of HGF-induced epithelial scattering without a concomitant increase in cell migration or decrease in adhesion strength. This scattering is dependent on RhoA, as blebbistatin-induced scattering is reduced in cells expressing dominant-negative RhoA mutants. This suggests that induction of myosin-based cellular contractility may be sufficient for cell–cell detachment during epithelial scattering. 相似文献
14.
Christopher P. Toret Caitlin Collins W. James Nelson 《The Journal of cell biology》2014,207(5):577-587
Cell–cell contact formation is a dynamic process requiring the coordination of cadherin-based cell–cell adhesion and integrin-based cell migration. A genome-wide RNA interference screen for proteins required specifically for cadherin-dependent cell–cell adhesion identified an Elmo–Dock complex. This was unexpected as Elmo–Dock complexes act downstream of integrin signaling as Rac guanine-nucleotide exchange factors. In this paper, we show that Elmo2 recruits Dock1 to initial cell–cell contacts in Madin–Darby canine kidney cells. At cell–cell contacts, both Elmo2 and Dock1 are essential for the rapid recruitment and spreading of E-cadherin, actin reorganization, localized Rac and Rho GTPase activities, and the development of strong cell–cell adhesion. Upon completion of cell–cell adhesion, Elmo2 and Dock1 no longer localize to cell–cell contacts and are not required subsequently for the maintenance of cell–cell adhesion. These studies show that Elmo–Dock complexes are involved in both integrin- and cadherin-based adhesions, which may help to coordinate the transition of cells from migration to strong cell–cell adhesion. 相似文献
15.
In epithelial MDCK cells, the Na,K-ATPase is co-localized with adherens junctions in all stages of monolayer formation starting
from initiation of cell–cell contact. The Na,K-ATPase and adherens junction proteins stay partially co-localized even after
internalization due to disruption of intercellular contacts by Ca2+ deprivation. Similar to adherens junction proteins, the Na,K-ATPase is resistant to extraction with non-ionic detergent,
suggesting pump association with the cytoskeleton. In contrast, the heterodimer formed by expressed unglycosylated Na,K-ATPase
β1 subunit and the endogenous α1 subunit is easily dissociated from the adherens junctions and cytoskeleton by detergent extraction. The MDCK cells in which
half of the endogenous β1 subunits in the lateral membrane are substituted by unglycosylated β1 subunits display a slower rate of cell-to-cell contact formation and decreased ability to both spread over the surface and
migrate. The lack of N-glycans in the Na,K-ATPase β1 subunit results in an impairment of mature cell–cell junctions as detected by an increase in the paracellular permeability
of the MDCK cell monolayers and by a decrease in resistance of adherens junction proteins to extraction by a non-ionic detergent.
Therefore the N-glycans of the Na,K-ATPase β1 subunit are important for retention of the pump at the sites of cell–cell contact. Moreover, they are important for the integrity
and stability of cell–cell junctions in mature epithelia. In addition, N-glycans contribute to the formation of cell–cell
contacts between surface-attached dispersed cells by mediating lamellipodia formation and stabilizing the newly formed adherens
junctions. 相似文献
16.
While traditional cell culture methods have relied on growing cells as monolayers, three-dimensional (3D) culture systems
can provide a convenient in vitro model for the study of complex cell–cell and cell–matrix interactions in the absence of
exogenous substrates and may benefit the development of regenerative medicine strategies. In this study, mesenchymal stem
cell (MSC) spheroids, or “mesenspheres”, of different sizes, were formed using a forced aggregation technique and maintained
in suspension culture for extended periods of time thereafter. Cell proliferation and differentiation potential within mesenspheres
and dissociated cells retrieved from spheroids were compared to conventional adherent monolayer cultures. Mesenspheres maintained
in growth medium exhibited no evidence of cell necrosis or differentiation, while mesenspheres in differentiation media exhibited
differentiation similar to conventional 2D culture methods based on histological markers of osteogenic and adipogenic commitment.
Furthermore, when plated onto tissue culture plates, cells that had been cultured within mesenspheres in growth medium recovered
morphology typical of cells cultured continuously in adherent monolayers and retained their capacity for multi-lineage differentiation
potential. In fact, more robust matrix mineralization and lipid vacuole content were evident in recovered MSCs when compared
to monolayers, suggesting enhanced differentiation by cells cultured as 3D spheroids. Thus, this study demonstrates the development
of a 3D culture system for mesenchymal stem cells that may circumvent limitations associated with conventional monolayer cultures
and enhance the differentiation potential of multipotent cells. 相似文献
17.
A R Gingle 《Developmental biology》1977,58(2):394-401
Whole chick embryos incubated for 24–36 hr were disaggregated with EDTA. The populations of single cells were incubated both in suspension and after being plated at various densities on agar blocks in a humid environment. In both cases aggregates formed. The aggregation was enhanced by cAMP and 3-isobutyl-1-methylxanthine (IBMX; a phosphodiesterase inhibitor). The density of aggregates which formed on the agar blocks decreased sharply at a critical cell density, suggesting that aggregation was mediated by a relayed signal. The critical density was decreased by IBMX and increased by phosphodiesterase (PDE), suggesting that aggregation was mediated by a cyclic nucleotide, most probably cAMP. Evidence was obtained for the presence of an extracellular PDE. 相似文献
18.
Pamela A. Maher 《Experimental cell research》2000,260(2):189
Treatment of confluent chicken embryo fibroblasts (CEFs) with trypsin results in a dose- and time-dependent increase in c-Src protein tyrosine kinase (PTK) activity. A similar, but less marked, increase in c-Src PTK activity occurs upon incubation of CEFs in calcium-free phosphate-buffered saline, which also causes a decrease in cell–substrate adhesion. The increase in c-Src PTK activity following disruption of cell–substrate adhesion correlates with a decrease in the phosphorylation of c-Src at the regulatory site, Tyr527. The phosphotyrosine phosphatase inhibitor phenylarsine oxide blocks the increase in c-Src PTK activity seen following treatment with trypsin and the morphological changes associated with the disruption of cell–substrate adhesion. In contrast, disruption of cell–substrate adhesion causes a decrease in FAK PTK activity that rapidly returns to control levels when the cells are plated on fibronection-coated dishes. Treatment of cells with cytochalasin D, which disrupts actin filaments but not cell–substrate adhesion, causes only a slight increase in c-Src PTK activity. Thus, these studies demonstrate a ligand-independent mechanism for the activation of c-Src that is consistent with its role in both cell adhesion and cell motility. Furthermore, these data suggest that similar to adhesion, loss of adhesion is not a passive process but can activate specific signaling pathways that may have significant effects on cellular function. 相似文献
19.
《Cell communication & adhesion》2013,20(1):49-59
Vinculin, a 117-kDa protein, is a constituent of adhesion plaques and adherence junctions in non-muscle cells. We investigated the role of vinculin on the physical strength of cell-cell adhesion by conducting disaggregation assays on aggregates of parental wild-type F9 mouse embryonal carcinoma cells (clone BIM), two vinculin-depleted F9 cell lines, γ227 and γ229, and a reconstituted γ229 cell line (R3) that re-express vinculin. Immunoblotting demonstrated that the four cell lines used in the study had similar expressions of the cell-cell adhesion molecule E-cadherin and associated membrane proteins α- and β-catenin. Double immunofluorescence analysis showed that, in contrast to the vinculin-null cell lines, BIM and R3 cells expressed abundant vinculin at the cell margins in adhesion plaques and in cell-cell margins that also contained actin. Laminar flow assays showed that both the vinculin-positive and vinculinnegative cell aggregates that were formed in culture in the course of 24 to 48 hours largely remained intact despite the imposition of shear flow at high shear rates. Since laminar flow imposed on cell aggregates act to separate cells from each other, our data indicate that F9 cells that were adherent to a substrate formed strong cell-cell adhesion bonds independent of vinculin expression. On the other hand, aggregates of vinculin-depleted γ229 and γ227 cells that were formed in suspension during a two-hour static incubation at 37°C were desegregated more easily with the imposition of shear flow than the BIM and R3 cell aggregates formed under identical conditions. Loss of vinculin was associated with a reduction in cell-cell adhesion strength only among those cells lacking contact to a substrate. Overall, the results indicate that vinculin is not needed for forming strong cell-cell adhesion bonds between neighboring carcinoma cells which are adherent to the basal lamina. 相似文献
20.
Cadherins Promote Skeletal Muscle Differentiation in Three-dimensional Cultures 总被引:9,自引:2,他引:7
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The cell–cell adhesion molecule N-cadherin, with its associated catenins, is expressed by differentiating skeletal muscle and its precursors. Although N-cadherin's role in later events of skeletal myogenesis such as adhesion during myoblast fusion is well established, less is known about its role in earlier events such as commitment and differentiation. Using an in vitro model system, we have determined that N-cadherin– mediated adhesion enhances skeletal muscle differentiation in three-dimensional cell aggregates. We transfected the cadherin-negative BHK fibroblastlike cell line with N-cadherin. Expression of exogenous N-cadherin upregulated endogenous β-catenin and induced strong cell–cell adhesion. When BHK cells were cultured as three-dimensional aggregates, N-cadherin enhanced withdrawal from the cell cycle and stimulated differentiation into skeletal muscle as measured by increased expression of sarcomeric myosin and the 12/101 antigen. In contrast, N-cadherin did not stimulate differentiation of BHK cells in monolayer cultures. The effect of N-cadherin was not unique since E-cadherin also increased the level of sarcomeric myosin in BHK aggregates. However, a nonfunctional mutant N-cadherin that increased the level of β-catenin failed to promote skeletal muscle differentiation suggesting an adhesion-competent cadherin is required. Our results suggest that cadherin-mediated cell–cell interactions during embryogenesis can dramatically influence skeletal myogenesis. 相似文献