scholarly journals Mechanotransduction of Strain Regulates an Invasive Phenotype in Newly Transformed Epithelial Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Sophie Chagnon-Lessard ◽  
Hubert Jean-Ruel ◽  
Michel Godin ◽  
Andrew E. Pelling
Keyword(s):  
Epithelial Cells ◽  
Complex Dynamics ◽  
Mdck Cells ◽  
Cyclic Strain ◽  
Mechanical Stretch ◽  
Transformed Cells ◽  
Invasive Phenotype ◽  
Apical Extrusion ◽  
External Forces ◽  
Static Conditions

Our organs and tissues are in constant motion, exposing epithelial cells to mechanical stretch. How these external forces impact cellular morphology, organization and dynamics in healthy and diseased tissues is still being elucidated. Carcinoma, the most common type of cancer, develops in the sheets of cells forming the epithelium and lining our organs and cavities. It usually begins with the transformation of a single cell via the activation of oncogenes such as Ras. Here, we show in a model system how mechanical stretch in epithelial sheets results in a more invasive phenotype in transformed cells. Cyclic strain impedes the apical extrusion of RasV12 cells from the healthy monolayer and prevents the formation of strong circumferential belts of actin in RasV12 cells. Concurrently, strain also changes the metastatic phenotype of newly transformed cells by greatly promoting the formation of RasV12 protrusions, potentially making them harder to be eliminated from healthy tissues. We also show that RasV12 and wild type MDCK cells possess distinct sensitivity to strain. External forces remodel their actin cytoskeletons and adhesion complexes differently, resulting in a more invasive system dynamic. Our work demonstrates that the Rho-ROCK mechanotransduction pathway is involved in regulating a mechanically-induced switch to a more invasive phenotype. The insights gained in this study reveal that the complex dynamics at play in healthy and transformed epithelial cells is drastically different in a mechanically active microenvironment when compared to static conditions.

scholarly journals Mechanotransduction of strain regulates an invasive phenotype in newly transformed epithelial cells

2019 ◽  
Author(s):  
Sophie Chagnon-Lessard ◽  
Hubert Jean-Ruel ◽  
Michel Godin ◽  
Andrew E. Pelling
Keyword(s):  
Epithelial Cells ◽  
Cancer Progression ◽  
Defense Mechanism ◽  
Mdck Cells ◽  
Early Stage ◽  
Mechanical Stretch ◽  
Transformed Cells ◽  
Apical Extrusion ◽  
External Forces ◽  
Static Conditions

AbstractCarcinoma, the most common type of cancer, develops in the sheets of cells forming the epithelium and lining our organs and cavities. It usually begins with the transformation of a single cell via the activation of oncogenes such as Ras. The capacity of epithelia to eliminate newly transformed cells via apical extrusion is believed to be a critical defense mechanism to eradicate initial stages of carcinoma. Our organs and tissues are in constant motion, exposing epithelial cells to mechanical stretch. How these external forces impact the onset and progression of tumor growth is thus of primary interest, but little is known currently. Here we show that mechanical strains jeopardize the epithelial defense mechanisms against RasV12-transformed MDCK cells by impeding their apical extrusion. Concurrently, they prevent the formation of strong circumferential belts of actin in RasV12 cells, previously established as a primary step of apical extrusion under static conditions. Cyclic stretching also changes the metastatic phenotype of newly transformed cells by greatly promoting the formation of RasV12 protrusions. We show that RasV12 and wild type MDCK cells possess distinct sensitivity to strain. External forces remodel their actin cytoskeletons and adhesion complexes differently, resulting in a more invasive system dynamic. Our work also shows that the Rho-ROCK mechanotransduction pathway is involved in regulating the mechanically-induced switch to a more aggressive phenotype. Such insight may lead to the targeting of mechanotransduction pathways in innovative future therapies.Significance statementCancer progression is increasingly viewed as a complex journey in which the mechanical properties of the microenvironment play a key role. The entire human body is in constant motion, yet the initial stage of cancer development at the cellular level is commonly studied in static petri dishes. Here we demonstrate that in a mechanically dynamic microenvironment, oncogenic Ras-transformed cells exhibit drastically different cellular dynamics and movements when compared to static conditions. They grow larger invasive protrusions, and they are much less likely to be eliminated from the healthy tissues. A deeper understanding of how external physical cues regulate early stage microtumor growth can reveal potentially new and unexplored avenues for cancer therapies.

scholarly journals A role of the sphingosine-1-phosphate (S1P)–S1P receptor 2 pathway in epithelial defense against cancer (EDAC)

2016 ◽  
Vol 27 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Sayaka Yamamoto ◽  
Yuta Yako ◽  
Yoichiro Fujioka ◽  
Mihoko Kajita ◽  
Takeshi Kameyama ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Single Cells ◽  
Initial Step ◽  
Transformed Cells ◽  
Cell Competition ◽  
Positive Role ◽  
Normal Cells ◽  
Apical Extrusion ◽  
Sphingosine 1 Phosphate ◽  
S1p Receptor

At the initial step of carcinogenesis, transformation occurs in single cells within epithelia, where the newly emerging transformed cells are surrounded by normal epithelial cells. A recent study revealed that normal epithelial cells have an ability to sense and actively eliminate the neighboring transformed cells, a process named epithelial defense against cancer (EDAC). However, the molecular mechanism of this tumor-suppressive activity is largely unknown. In this study, we investigated a role for the sphingosine-1-phosphate (S1P)–S1P receptor 2 (S1PR2) pathway in EDAC. First, we show that addition of the S1PR2 inhibitor significantly suppresses apical extrusion of RasV12-transformed cells that are surrounded by normal cells. In addition, knockdown of S1PR2 in normal cells induces the same effect, indicating that S1PR2 in the surrounding normal cells plays a positive role in the apical elimination of the transformed cells. Of importance, not endogenous S1P but exogenous S1P is involved in this process. By using FRET analyses, we demonstrate that S1PR2 mediates Rho activation in normal cells neighboring RasV12-transformed cells, thereby promoting accumulation of filamin, a crucial regulator of EDAC. Collectively these data indicate that S1P is a key extrinsic factor that affects the outcome of cell competition between normal and transformed epithelial cells.

scholarly journals Cell competition with normal epithelial cells promotes apical extrusion of transformed cells through metabolic changes

2017 ◽  
Vol 19 (5) ◽  
pp. 530-541 ◽  
Author(s):  
Shunsuke Kon ◽  
Kojiro Ishibashi ◽  
Hiroto Katoh ◽  
Sho Kitamoto ◽  
Takanobu Shirai ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Metabolic Changes ◽  
Transformed Cells ◽  
Cell Competition ◽  
Apical Extrusion

scholarly journals Repetitive deformation activates Src-independent FAK-dependent ERK motogenic signals in human Caco-2 intestinal epithelial cells

2008 ◽  
Vol 294 (6) ◽  
pp. C1350-C1361 ◽  
Author(s):  
Lakshmi S. Chaturvedi ◽  
Christopher P. Gayer ◽  
Harold M. Marsh ◽  
Marc D. Basson
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Cyclic Strain ◽  
Mucosal Healing ◽  
Intestinal Epithelial ◽  
Erk Activation ◽  
Erk Phosphorylation ◽  
And Migration ◽  
Static Conditions ◽  
Si Rna

Repetitive deformation due to villous motility or peristalsis may support the intestinal mucosa, stimulating intestinal epithelial proliferation under normal circumstances and restitution in injured and inflamed mucosa rich in tissue fibronectin. Cyclic strain enhances Caco-2 and IEC-6 intestinal epithelial cell migration across fibronectin via ERK. However, the upstream mediators of ERK activation are unknown. We investigated whether Src and FAK mediate strain-induced ERK phosphorylation and migration in human Caco-2 intestinal epithelial cells on fibronectin. Monolayers on tissue fibronectin-precoated membranes were subjected to an average 10% repetitive deformation at 10 cycles/min. Phosphorylation of Src-Tyr418, FAK-Tyr397-Tyr576-Tyr925, and ERK were significantly increased by deformation. The stimulation of wound closure by strain was prevented by Src blockade with PP2 (10 μmol/l) or specific short interfering (si)RNA. Src inhibition also prevented strain-induced FAK phosphorylation at Tyr397 and Tyr576 but not FAK-Tyr925 or ERK phosphorylation. Reducing FAK by siRNA inhibited strain-induced ERK phosphorylation. Transfection of NH2-terminal tyrosine phosphorylation-deficient FAK mutants Y397F, Y576F-Y577F, and Y397F-Y576F-Y577F did not prevent the activation of ERK2 by cyclic strain, but a FAK mutant at the COOH terminal (Y925F) prevented the strain-induced activation of ERK2. Although the Y397F-Y576F-Y577F FAK construct exhibited less basal FAK-Tyr925 phosphorylation under static conditions, it nevertheless exhibited increased FAK-Tyr925 phosphorylation in response to strain. These results suggest that repetitive deformation stimulates intestinal epithelial motility across fibronectin in a manner that requires both Src activation and a novel Src-independent FAK-Tyr925-dependent pathway that activates ERK. This pathway may be an important target for interventions to promote mucosal healing in settings of intestinal ileus or fasting.

scholarly journals Numerical methods for General Relativistic particles

2018 ◽  
Vol 14 (S342) ◽  
pp. 19-23
Author(s):  
Fabio Bacchini ◽  
Bart Ripperda ◽  
Alexander Y. Chen ◽  
Lorenzo Sironi
Keyword(s):  
Numerical Methods ◽  
Gravitational Lensing ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Numerical Algorithms ◽  
Relativistic Effects ◽  
Compact Objects ◽  
Light Rays ◽  
Massive Particles ◽  
External Forces

AbstractWe present recent developments on numerical algorithms for computing photon and particle trajectories in the surrounding of compact objects. Strong gravity around neutron stars or black holes causes relativistic effects on the motion of massive particles and distorts light rays due to gravitational lensing. Efficient numerical methods are required for solving the equations of motion and compute i) the black hole shadow obtained by tracing light rays from the object to a distant observer, and ii) obtain information on the dynamics of the plasma at the microscopic scale. Here, we present generalized algorithms capable of simulating ensembles of photons or massive particles in any spacetime, with the option of including external forces. The coupling of these tools with GRMHD simulations is the key point for obtaining insight on the complex dynamics of accretion disks and jets and for comparing simulations with upcoming observational results from the Event Horizon Telescope.

scholarly journals Atypical Protein Kinase C Is Involved in the Evolutionarily Conserved Par Protein Complex and Plays a Critical Role in Establishing Epithelia-Specific Junctional Structures

2001 ◽  
Vol 152 (6) ◽  
pp. 1183-1196 ◽  
Author(s):  
Atsushi Suzuki ◽  
Tomoyuki Yamanaka ◽  
Tomonori Hirose ◽  
Naoyuki Manabe ◽  
Keiko Mizuno ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Polarity ◽  
Protein Complex ◽  
Mdck Cells ◽  
Critical Role ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Surface Polarity ◽  
C Elegans ◽  
Evolutionarily Conserved

We have previously shown that during early Caenorhabditis elegans embryogenesis PKC-3, a C. elegans atypical PKC (aPKC), plays critical roles in the establishment of cell polarity required for subsequent asymmetric cleavage by interacting with PAR-3 [Tabuse, Y., Y. Izumi, F. Piano, K.J. Kemphues, J. Miwa, and S. Ohno. 1998. Development (Camb.). 125:3607–3614]. Together with the fact that aPKC and a mammalian PAR-3 homologue, aPKC-specific interacting protein (ASIP), colocalize at the tight junctions of polarized epithelial cells (Izumi, Y., H. Hirose, Y. Tamai, S.-I. Hirai, Y. Nagashima, T. Fujimoto, Y. Tabuse, K.J. Kemphues, and S. Ohno. 1998. J. Cell Biol. 143:95–106), this suggests a ubiquitous role for aPKC in establishing cell polarity in multicellular organisms. Here, we show that the overexpression of a dominant-negative mutant of aPKC (aPKCkn) in MDCK II cells causes mislocalization of ASIP/PAR-3. Immunocytochemical analyses, as well as measurements of paracellular diffusion of ions or nonionic solutes, demonstrate that the biogenesis of the tight junction structure itself is severely affected in aPKCkn-expressing cells. Furthermore, these cells show increased interdomain diffusion of fluorescent lipid and disruption of the polarized distribution of Na+,K+-ATPase, suggesting that epithelial cell surface polarity is severely impaired in these cells. On the other hand, we also found that aPKC associates not only with ASIP/PAR-3, but also with a mammalian homologue of C. elegans PAR-6 (mPAR-6), and thereby mediates the formation of an aPKC-ASIP/PAR-3–PAR-6 ternary complex that localizes to the apical junctional region of MDCK cells. These results indicate that aPKC is involved in the evolutionarily conserved PAR protein complex, and plays critical roles in the development of the junctional structures and apico-basal polarization of mammalian epithelial cells.

scholarly journals Impact of Heterogeneity within Cultured Cells on Bacterial Invasion: Analysis of Pseudomonas aeruginosa andSalmonella enterica Serovar Typhi Entry into MDCK cells by Using a Green Fluorescent Protein-Labelled Cystic Fibrosis Transmembrane Conductance Regulator Receptor

2000 ◽  
Vol 68 (2) ◽  
pp. 861-870 ◽  
Author(s):  
A. Alev Gerçeker ◽  
Tanweer Zaidi ◽  
Peter Marks ◽  
David E. Golan ◽  
Gerald B. Pier
Keyword(s):  
Epithelial Cells ◽  
Protein Expression ◽  
Fluorescent Protein ◽  
Cultured Cells ◽  
Mdck Cells ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Bacterial Uptake ◽  
Cftr Protein ◽  
Green Fluorescent

ABSTRACT The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride ion channel that also serves as a receptor for entry ofPseudomonas aeruginosa and Salmonella entericaserovar Typhi into epithelial cells. To evaluate heterogeneity in CFTR protein expression in cultured cells and the effect of heterogeneity on internalization of different P. aeruginosa and serovar Typhi strains, we used two-color flow cytometry and confocal laser microscopy to study bacterial uptake by Madin-Darby canine kidney (MDCK) type I epithelial cells stably expressing a green fluorescent protein (GFP)-CFTR fusion construct (MDCK–GFP-CFTR cells). We found a strong correlation between cell size and GFP-CFTR protein expression, with 60 to 70% of cells expressing low levels of GFP-CFTR protein, 20 to 30% expressing intermediate levels, and <10% expressing high levels. The cells were sorted into low-, intermediate-, or high-level producers of CFTR protein; in vitro growth of each sorted population yielded the same distribution of CFTR protein expression as that in the original population. Cells expressing either low or high levels of CFTR protein internalized bacteria poorly; maximal bacterial uptake occurred in the cells expressing intermediate levels of CFTR protein. Treatment of MDCK cells with sodium butyrate markedly enhanced the production of CFTR protein without increasing cell size; butyrate treatment also increased the proportion of cells with internalized bacteria. However, there were fewer bacteria per butyrate-treated cell and, for P. aeruginosa, there was an overall decrease in the total level of bacterial uptake. The most highly ingested bacterial strains were internalized by fewer total MDCK–GFP-CFTR cells, indicating preferential bacterial uptake by a minority of epithelial cells within a given culture. Confocal fluorescence microscopy showed that P. aeruginosa and serovar Typhi induced cytoplasmic accumulation of CFTR protein close to the plasma membrane where the bacteria were adherent. These results show that within a population of MDCK–GFP-CFTR cells, there are cells with markedly different abilities to ingest bacteria via CFTR, the majority of the P. aeruginosa and serovar Typhi cells are ingested by the one-fourth to one-third of the cells that exhibit an intermediate size and level of CFTR protein expression, and overexpression of the CFTR receptor does not increase total bacterial uptake but rather allows more epithelial cells to ingest fewer total bacteria.

scholarly journals Iron Depletion Affects Genes Encoding Mitochondrial Electron Transport Chain and Genes of Non­Oxidative Metabolism, Pyruvate Kinase and Lactate Dehydrogenase, in Primary Human Cardiac Myocytes Cultured upon Mechanical Stretch

Cells ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 175 ◽  
Author(s):  
Magdalena Dziegala ◽  
Kamil Kobak ◽  
Monika Kasztura ◽  
Jacek Bania ◽  
Krystian Josiak ◽  
...  
Keyword(s):  
Lactate Dehydrogenase ◽  
Pyruvate Kinase ◽  
Cardiac Myocytes ◽  
Lactate Concentration ◽  
Mechanical Stretch ◽  
Iron Availability ◽  
Extracellular Lactate ◽  
Mitochondrial Complexes ◽  
Static Conditions ◽  
Iron Concentrations

(1) Background: Oxidative energy metabolism is presumed to rely on the optimal iron supply. Primary human cardiac myocytes (HCM) exposed to different iron availability conditions during mechanical stretch are anticipated to demonstrate expression changes of genes involved in aerobic and anaerobic metabolic pathways. (2) Methods: HCM were cultured for 48 h either in static conditions and upon mechanical stretch at the optimal versus reduced versus increased iron concentrations. We analyzed the expression of pyruvate kinase (PKM2), lactate dehydrogenase A (LDHA), and mitochondrial complexes I–V at the mRNA and protein levels. The concentration of l-lactate was assessed by means of lactate oxidase method-based kit. (3) Results: Reduced iron concentrations during mechanical work caused a decreased expression of complexes I–V (all p < 0.05). The expression of PKM2 and LDHA, as well as the medium concentration of l-lactate, was increased in these conditions (both p < 0.05). HCM exposed to the increased iron concentration during mechanical effort demonstrated a decreased expression of mitochondrial complexes (all p < 0.01); however, a decrement was smaller than in case of iron chelation (p < 0.05). The iron-enriched medium caused a decrease in expression of LDHA and did not influence the concentration of l-lactate. (4) Conclusions: During mechanical effort, the reduced iron availability enhances anaerobic glycolysis and extracellular lactate production, whilst decreasing mitochondrial aerobic pathway in HCM. Iron enrichment during mechanical effort may be protective in the context of intracellular protein machinery of non-oxidative metabolism with no effect on the extracellular lactate concentration.

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