scholarly journals Probing compression versus stretch activated recruitment of cortical actin and apical junction proteins using mechanical stimulations of suspended doublets

2018 ◽  
Author(s):  
Xumei Gao ◽  
Bipul R. Acharya ◽  
Wilfried Claude Otto Engl ◽  
Richard De Mets ◽  
Jean Paul Thiery ◽  
...  
Keyword(s):  
Experimental Approach ◽  
Hydrodynamic Force ◽  
Cell Contact ◽  
Cortical Actin ◽  
Suspended Cell ◽  
Actin Cortex ◽  
A Cell ◽  
Original Approach ◽  
Junction Proteins

ABSTRACTWe report an experimental approach to study the mechanosensitivity of cellcell contact upon mechanical stimulation in suspended cell-doublets. The doublet is placed astride an hourglass aperture, and a hydrodynamic force is selectively exerted on only one of the cells. The geometry of the device concentrates the mechanical shear over the junction area. Together with mechanical shear, the system also allows confocal quantitative live imaging of the recruitment of junction proteins (e.g. E-cadherin, ZO-1, Occludin and actin). We observed the time sequence over which proteins were recruited to the stretched region of the contact. The compressed side of the contact showed no response. We demonstrated how this mechanism polarizes the stress-induced recruitment of junctional components within one single junction. Finally, we demonstrated that stabilizing the actin cortex dynamics abolishes the mechanosensitive response of the junction. Our experimental design provides an original approach to study the role of mechanical force at a cell-cell contact with unprecedented control over stress application and quantitative optical analysis.

Role of cell–cell contact in the preservation of differentiation and response to thyrotrophin in cultured porcine thyroid cells

1987 ◽  
Vol 113 (2) ◽  
pp. 223-NP ◽  
Author(s):  
A. S. Yap ◽  
J. R. Bourke ◽  
S. W. Manley
Keyword(s):  
Follicular Development ◽  
Seeding Density ◽  
Cell Contact ◽  
Culture Dish ◽  
Thyroid Cells ◽  
A Cell ◽  
Free Membrane ◽  
Zero Time ◽  
Cell Cell

ABSTRACT Cultured porcine thyroid cells did not reassociate into functional follicles in the presence of TSH unless the initial seeding density was adequate. At 0·2 × 106 cells/35 mm diameter culture dish the cells rapidly formed a monolayer even in the presence of TSH (128 μu./ml), and radioiodide uptake was not significantly increased compared with that in control cells. Seeding densities of 1–3 × 106 cells/dish resulted in cultures which responded to TSH with follicular development and increased radioiodide uptake. A cell-free membrane fraction of thyroid homogenate restored the ability of cultures seeded at low densities to respond to TSH with development of follicular morphology and increased radioiodide uptake. Delaying the addition of TSH by 48 h markedly reduced the stimulation of follicular development and radioiodide uptake of cultures. Addition of membrane fractions, or an alkali-soluble fraction of membranes, at zero time improved the responses to TSH added after a 48-h delay. It was concluded that maintenance of differentiation and of TSH-responsiveness in cultured thyroid cells was influenced by cell–cell contact. J. Endocr. (1987) 113, 223–229

scholarly journals Role of the Nfa1 Protein in Pathogenic Naegleria fowleri Cocultured with CHO Target Cells

2005 ◽  
Vol 12 (7) ◽  
pp. 873-876 ◽  
Author(s):  
Su-Yeon Kang ◽  
Kyoung-Ju Song ◽  
Seok-Ryoul Jeong ◽  
Jong-Hyun Kim ◽  
Sun Park ◽  
...  
Keyword(s):  
Close Contact ◽  
Immunofluorescence Assay ◽  
Cell Contact ◽  
Target Cells ◽  
Naegleria Fowleri ◽  
Immune Mouse ◽  
A Cell ◽  
Nægleria Fowleri ◽  
Amoebic Meningoencephalitis

ABSTRACTNaegleria fowleri, a free-living amoeba, exists as a virulent pathogen which causes fatal primary amoebic meningoencephalitis in experimental animals and humans. Using infected and immune mouse sera, we previously cloned annfa1gene from a cDNA library ofN. fowleriby immunoscreening. Thenfa1gene (360 bp) produced a recombinant 13.1-kDa protein, and the Nfa1 protein showed pseudopodium-specific immunolocalization on a trophozoite ofN. fowleri. In this study, the role of the Nfa1 protein as a cell contact mechanism ofN. fowlericocultured with target cells was observed by an immunofluorescence assay with an anti-Nfa1 polyclonal antibody. Using confocal microscopic findings, the Nfa1 protein was located on the pseudopodia ofN. fowleritrophozoites. The Nfa1 protein inN. fowleritrophozoites cocultured with CHO target cells was also located on pseudopodia, as well as in a food cup formed as a phagocytic structure in close contact with target cells. The amount ofnfa1mRNA ofN. fowleriwas strongly increased 6 h after coculture.

scholarly journals Autonomous induction of hepatic polarity to construct single cell liver

2019 ◽  
Author(s):  
Yue Zhang ◽  
Richard de Mets ◽  
Cornelia Monzel ◽  
Pearlyn Toh ◽  
Noemi Van Hul ◽  
...  
Keyword(s):  
Single Cell ◽  
De Novo ◽  
Cell Contact ◽  
Embryonic Cells ◽  
Protein Distribution ◽  
Cytoskeleton Organization ◽  
Actin Cortex ◽  
Key Factor ◽  
A Cell ◽  
Bona Fide

AbstractSymmetry breaking of protein distribution and cytoskeleton organization is an essential aspect for development of apico-basal polarity. In embryonic cells this process is largely cell autonomous, while differentiated epithelial cells collectively polarize during epithelium formation. We report here that the de novo polarization of mature hepatocytes is a cell autonomous process. Single hepatocytes developed bona fide secretory hemi-apical lumens upon adhesion to finely tuned substrates bio-functionalized with cadherin and extra cellular matrix. The creation of this single cell liver allows unprecedented control and imaging resolution of the lumenogenesis process. We demonstrate that the density and localization of cadherins along the initial cell-cell contact acted as a key factor triggering the reorganization from lateral to apical actin cortex. Consequently, we established why hepatocytes could form asymmetric lumens in heterotypic doublets involving another ectopic epithelial cell originating from kidney, breast, or colon.

scholarly journals Cortical actin flow activates an alpha-catenin clutch to assemble adherens junctions

2021 ◽  
Author(s):  
Ivar Noordstra ◽  
Mario Diez Hermoso ◽  
Lilian Schimmel ◽  
Alexis Bonfim-Melo ◽  
Joseph Mathew Kalappurakkal ◽  
...  
Keyword(s):  
Adherens Junctions ◽  
Actin Binding ◽  
Cell Contact ◽  
Cortical Actin ◽  
Bond Behaviour ◽  
Catch Bond ◽  
Actin Cortex ◽  
Mediate Cell ◽  
E Cadherin ◽  
Cell Cell

Adherens junctions (AJs) fundamentally mediate cell-cell adhesion, yet the mechanisms that determine where or when AJs assemble are not understood. Here we reveal a mechanosensitive clutch that initiates AJ assembly. Before cell-cell contact, alpha-catenin couples surface E-cadherin complexes to retrograde flow of the actin cortex. Cortical flows with opposed orientations persist after contact, applying tension to alpha-catenin within trans-ligated cadherin complexes. Tension unfolds the alpha-catenin actin-binding domain (ABD), which is expected to mediate a catch bond with F-actin. However, catch bond behaviour is not sufficient for AJ assembly in a molecular clutch model. Instead, it is also necessary for the activated ABD to promote cis-clustering of E-cadherin molecules by bundling F-actin. Thus, this alpha-catenin clutch transduces the mechanical signal of cortical flow to assemble AJs.

CD38 as an immunomodulator in cancer

2020 ◽  
Vol 16 (34) ◽  
pp. 2853-2861
Author(s):  
Yanli Li ◽  
Rui Yang ◽  
Limo Chen ◽  
Sufang Wu
Keyword(s):  
Multiple Myeloma ◽  
Cell Activation ◽  
Human Tissues ◽  
Transmembrane Glycoprotein ◽  
Cell Activation Marker ◽  
Research Findings ◽  
A Cell ◽  
And Function ◽  
Human Molecule

CD38 is a transmembrane glycoprotein that is widely expressed in a variety of human tissues and cells, especially those in the immune system. CD38 protein was previously considered as a cell activation marker, and today monoclonal antibodies targeting CD38 have witnessed great achievements in multiple myeloma and promoted researchers to conduct research on other tumors. In this review, we provide a wide-ranging review of the biology and function of the human molecule outside the field of myeloma. We focus mainly on current research findings to summarize and update the findings gathered from diverse areas of study. Based on these findings, we attempt to extend the role of CD38 in the context of therapy of solid tumors and expand the role of the molecule from a simple marker to an immunomodulator.

An experimental approach to communal coping

2021 ◽  
pp. 026540752199246
Author(s):  
Melissa Zajdel ◽  
Vicki S. Helgeson
Keyword(s):  
Health Outcomes ◽  
Positive Relationship ◽  
Experimental Approach ◽  
Positive Mood ◽  
Self Report ◽  
Communal Coping ◽  
Observational Measures ◽  
Relationship Outcomes ◽  
The Individual

Communal coping has been linked to better psychological and physical health across a variety of stressful contexts. However, there has been no experimental work causally linking communal coping to relationship and health outcomes. In addition, research has emphasized the collaboration over the shared appraisal component of communal coping. The present study sought to isolate the role of appraisal by manipulating whether dyads viewed a stressor as shared or individual. Friend dyads (n = 64 dyads; 128 participants) were randomly assigned to view a stressor as either a shared or an individual problem, but both groups were allowed to work together. Across self-report and observational measures dyads reported more collaboration and support, better relationship outcomes, and more positive mood after the stressor in the shared than the individual appraisal group. This is the first laboratory evidence to establish causal links of communal coping—specifically shared appraisal—to positive relationship and health outcomes.

scholarly journals Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

2016 ◽  
Vol 113 (34) ◽  
pp. E4995-E5004 ◽  
Author(s):  
Wen Lu ◽  
Michael Winding ◽  
Margot Lakonishok ◽  
Jill Wildonger ◽  
Vladimir I. Gelfand
Keyword(s):  
Cytoplasmic Streaming ◽  
Cell Types ◽  
Nurse Cells ◽  
Wild Type ◽  
Actin Cortex ◽  
Microtubule Motor ◽  
Multiple Cell ◽  
Cytoplasmic Microtubules ◽  
Two Populations

Cytoplasmic streaming in Drosophila oocytes is a microtubule-based bulk cytoplasmic movement. Streaming efficiently circulates and localizes mRNAs and proteins deposited by the nurse cells across the oocyte. This movement is driven by kinesin-1, a major microtubule motor. Recently, we have shown that kinesin-1 heavy chain (KHC) can transport one microtubule on another microtubule, thus driving microtubule–microtubule sliding in multiple cell types. To study the role of microtubule sliding in oocyte cytoplasmic streaming, we used a Khc mutant that is deficient in microtubule sliding but able to transport a majority of cargoes. We demonstrated that streaming is reduced by genomic replacement of wild-type Khc with this sliding-deficient mutant. Streaming can be fully rescued by wild-type KHC and partially rescued by a chimeric motor that cannot move organelles but is active in microtubule sliding. Consistent with these data, we identified two populations of microtubules in fast-streaming oocytes: a network of stable microtubules anchored to the actin cortex and free cytoplasmic microtubules that moved in the ooplasm. We further demonstrated that the reduced streaming in sliding-deficient oocytes resulted in posterior determination defects. Together, we propose that kinesin-1 slides free cytoplasmic microtubules against cortically immobilized microtubules, generating forces that contribute to cytoplasmic streaming and are essential for the refinement of posterior determinants.

scholarly journals PapRIV, a BV-2 microglial cell activating quorum sensing peptide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yorick Janssens ◽  
Nathan Debunne ◽  
Anton De Spiegeleer ◽  
Evelien Wynendaele ◽  
Marta Planas ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Cell Model ◽  
Dependent Manner ◽  
Communication Signals ◽  
Gram Positive Bacteria ◽  
A Cell ◽  
Gastro Intestinal Tract

AbstractQuorum sensing peptides (QSPs) are bacterial peptides produced by Gram-positive bacteria to communicate with their peers in a cell-density dependent manner. These peptides do not only act as interbacterial communication signals, but can also have effects on the host. Compelling evidence demonstrates the presence of a gut-brain axis and more specifically, the role of the gut microbiota in microglial functioning. The aim of this study is to investigate microglial activating properties of a selected QSP (PapRIV) which is produced by Bacillus cereus species. PapRIV showed in vitro activating properties of BV-2 microglia cells and was able to cross the in vitro Caco-2 cell model and reach the brain. In vivo peptide presence was also demonstrated in mouse plasma. The peptide caused induction of IL-6, TNFα and ROS expression and increased the fraction of ameboid BV-2 microglia cells in an NF-κB dependent manner. Different metabolites were identified in serum, of which the main metabolite still remained active. PapRIV is thus able to cross the gastro-intestinal tract and the blood–brain barrier and shows in vitro activating properties in BV-2 microglia cells, hereby indicating a potential role of this quorum sensing peptide in gut-brain interaction.

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