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Arteriosclerosis, Thrombosis, and... Jul 2023Endothelial cells (ECs) are sensitive to physical forces created by blood flow, especially to laminar shear stress. Among the cell responses to laminar flow, EC...
BACKGROUND
Endothelial cells (ECs) are sensitive to physical forces created by blood flow, especially to laminar shear stress. Among the cell responses to laminar flow, EC polarization against the flow direction emerges as a key event, particularly during the development and remodeling of the vascular network. EC adopt an elongated planar cell shape with an asymmetrical distribution of intracellular organelles along the axis of blood flow. This study aimed to investigate the involvement of planar cell polarity via the receptor ROR2 (receptor tyrosine kinase-like orphan receptor 2) in endothelial responses to laminar shear stress.
METHODS
We generated a genetic mouse model with EC-specific deletion of , in combination with in vitro approaches involving loss- and gain-of-function experiments.
RESULTS
During the first 2 weeks of life, the endothelium of the mouse aorta undergoes a rapid remodeling associated with a loss of EC polarization against the flow direction. Notably, we found a correlation between ROR2 expression and endothelial polarization levels. Our findings demonstrate that deletion of in murine ECs impaired their polarization during the postnatal development of the aorta. In vitro experiments further validated the essential role of ROR2 in both EC collective polarization and directed migration under laminar flow conditions. Exposure to laminar shear stress triggered the relocalization of ROR2 to cell-cell junctions where it formed a complex with VE-Cadherin and β-catenin, thereby regulating adherens junctions remodeling at the rear and front poles of ECs. Finally, we showed that adherens junctions remodeling and cell polarity induced by ROR2 were dependent on the activation of the small GTPase Cdc42.
CONCLUSIONS
This study identified ROR2/planar cell polarity pathway as a new mechanism controlling and coordinating collective polarity patterns of EC during shear stress response.
Topics: Mice; Animals; Endothelial Cells; Receptor Tyrosine Kinase-like Orphan Receptors; Cell Polarity; Endothelium, Vascular; Intercellular Junctions; Stress, Mechanical
PubMed: 37199159
DOI: 10.1161/ATVBAHA.123.319106 -
Development (Cambridge, England) Dec 2020Planar cell polarity (PCP) is essential for tissue morphogenesis and homeostasis; however, the mechanisms that orchestrate the cell shape and packing dynamics required...
Planar cell polarity (PCP) is essential for tissue morphogenesis and homeostasis; however, the mechanisms that orchestrate the cell shape and packing dynamics required to establish PCP are poorly understood. Here, we identified a major role for the globular (G)-actin-binding protein thymosin-β4 (TMSB4X) in PCP establishment and cell adhesion in the developing epidermis. Depletion of in mouse embryos hindered eyelid closure and hair-follicle angling owing to PCP defects. depletion did not preclude epidermal cell adhesion or ; however, it resulted in abnormal structural organization and stability of adherens junction (AJ) due to defects in filamentous (F)-actin and G-actin distribution. In cultured keratinocytes, TMSB4X depletion increased the perijunctional G/F-actin ratio and decreased G-actin incorporation into junctional actin networks, but it did not change the overall actin expression level or cellular F-actin content. A pharmacological treatment that increased the G/F-actin ratio and decreased actin polymerization mimicked the effects of depletion on both AJs and PCP. Our results provide insights into the regulation of the actin pool and its involvement in AJ function and PCP establishment.
Topics: Actin Cytoskeleton; Actins; Adherens Junctions; Animals; Cell Adhesion; Cell Polarity; Cell Shape; Embryonic Development; Epidermal Cells; Epidermis; Homeostasis; Keratinocytes; Mice; Microfilament Proteins; Morphogenesis; Thymosin
PubMed: 33310787
DOI: 10.1242/dev.193425 -
Clinical Reviews in Allergy & Immunology Apr 2021Crohn's disease (CD) is a type of inflammatory bowel disease (IBD) and affects diverse segments of the entire gastrointestinal tract. Although the underlying causes of... (Review)
Review
Crohn's disease (CD) is a type of inflammatory bowel disease (IBD) and affects diverse segments of the entire gastrointestinal tract. Although the underlying causes of CD are not completely known, it is believed that disruption of the intestinal barrier and cell polarity may contribute to pathogenesis. The formation of the intestinal epithelial barrier, which is mainly regulated by cytoskeletal modulations, and apico-basal cell polarity are two major and mutually dependent features of the intestinal epithelial layer. As this layer serves as an important barrier between the external environment and the internal milieu, the defect can start an inflammatory cascade by failing to block the entrance of luminal pathogens and lead to CD. In this review, we highlight the factors and impact of intestinal barrier function and cell polarity in the natural history of CD. The discussion in the present review further strengthens the new challenge in facilitating the development of viable pharmacological targets.
Topics: Adherens Junctions; Animals; Cell Polarity; Crohn Disease; Cytoskeleton; Humans; Inflammatory Bowel Diseases; Intestinal Mucosa; Tight Junctions
PubMed: 32474815
DOI: 10.1007/s12016-020-08795-5 -
International Journal of Molecular... May 2020The intestinal epithelial apical junctional complex, which includes tight and adherens junctions, contributes to the intestinal barrier function via their role in... (Review)
Review
The intestinal epithelial apical junctional complex, which includes tight and adherens junctions, contributes to the intestinal barrier function via their role in regulating paracellular permeability. Myosin light chain II (MLC-2), has been shown to be a critical regulatory protein in altering paracellular permeability during gastrointestinal disorders. Previous studies have demonstrated that phosphorylation of MLC-2 is a biochemical marker for perijunctional actomyosin ring contraction, which increases paracellular permeability by regulating the apical junctional complex. The phosphorylation of MLC-2 is dominantly regulated by myosin light chain kinase- (MLCK-) and Rho-associated coiled-coil containing protein kinase- (ROCK-) mediated pathways. In this review, we aim to summarize the current state of knowledge regarding the role of MLCK- and ROCK-mediated pathways in the regulation of the intestinal barrier during normal homeostasis and digestive diseases. Additionally, we will also suggest potential therapeutic targeting of MLCK- and ROCK-associated pathways in gastrointestinal disorders that compromise the intestinal barrier.
Topics: Animals; Humans; Intestinal Mucosa; Myosin-Light-Chain Kinase; Permeability; Tight Junctions; rho-Associated Kinases
PubMed: 32443411
DOI: 10.3390/ijms21103550 -
Tissue Engineering. Part C, Methods Nov 2019Cell-cell adhesion complexes are macromolecular adhesive organelles that integrate cells into tissues. This mechanochemical coupling in cell-cell adhesion is required... (Review)
Review
Cell-cell adhesion complexes are macromolecular adhesive organelles that integrate cells into tissues. This mechanochemical coupling in cell-cell adhesion is required for a large number of cell behaviors, and perturbations of the cell-cell adhesion structure or related mechanotransduction pathways can lead to critical pathological conditions such as skin and heart diseases, arthritis, and cancer. Mechanical stretching has been a widely used method to stimulate the mechanotransduction process originating from the cell-cell adhesion and cell-extracellular matrix (ECM) complexes. These studies aimed to reveal the biophysical processes governing cell proliferation, wound healing, gene expression regulation, and cell differentiation in various tissues, including cardiac, muscle, vascular, and bone. This review explores techniques in mechanical stretching in two-dimensional settings with different stretching regimens on different cell types. The mechanotransduction responses from these different cell types will be discussed with an emphasis on their biophysical transformations during mechanical stretching and the cross talk between the cell-cell and cell-ECM adhesion complexes. Therapeutic aspects of mechanical stretching are reviewed considering these cellular responses after the application of mechanical forces, with a focus on wound healing and tissue regeneration. Impact Statement Mechanical stretching has been proposed as a therapeutic option for tissue regeneration and wound healing. It has been accepted that mechanotransduction processes elicited by mechanical stretching govern cellular response and behavior, and these studies have predominantly focused on the cell-extracellular matrix (ECM) sites. This review serves the mechanobiology community by shifting the focus of mechanical stretching effects from cell-ECM adhesions to the less examined cell-cell adhesions, which we believe play an equally important role in orchestrating the response pathways.
Topics: Adherens Junctions; Animals; Cell Adhesion; Desmosomes; Disease; Humans; Regeneration; Stress, Mechanical
PubMed: 31407627
DOI: 10.1089/ten.TEC.2019.0098 -
Nature Cardiovascular Research Dec 2022Vascular endothelial (VE)-cadherin in endothelial adherens junctions is an essential component of the vascular barrier, critical for tissue homeostasis and implicated in...
Vascular endothelial (VE)-cadherin in endothelial adherens junctions is an essential component of the vascular barrier, critical for tissue homeostasis and implicated in diseases such as cancer and retinopathies. Inhibitors of Src cytoplasmic tyrosine kinase have been applied to suppress VE-cadherin tyrosine phosphorylation and prevent excessive leakage, edema and high interstitial pressure. Here we show that the Src-related Yes tyrosine kinase, rather than Src, is localized at endothelial cell (EC) junctions where it becomes activated in a flow-dependent manner. EC-specific deletion suppresses VE-cadherin phosphorylation and arrests VE-cadherin at EC junctions. This is accompanied by loss of EC collective migration and exaggerated agonist-induced macromolecular leakage. Overexpression of causes ectopic VE-cadherin phosphorylation, while vascular leakage is unaffected. In contrast, in EC-specific Src-deficiency, VE-cadherin internalization is maintained, and leakage is suppressed. In conclusion, Yes-mediated phosphorylation regulates constitutive VE-cadherin turnover, thereby maintaining endothelial junction plasticity and vascular integrity.
PubMed: 37936984
DOI: 10.1038/s44161-022-00172-z -
EXCLI Journal 2023Cell junctions, including anchoring, occluding and communicating junctions, play an indispensable role in tissue architecture and homeostasis. Consequently,...
Cell junctions, including anchoring, occluding and communicating junctions, play an indispensable role in tissue architecture and homeostasis. Consequently, malfunctioning of cell junctions is linked with a wide range of disorders, including in liver. The present study was set up to investigate the effects of acute and chronic disease induced by chemical compounds on hepatic cell junctions in mice. Mice were either overdosed with paracetamol or repeatedly administered carbon tetrachloride followed by sampling at 24 hours or 8 weeks, respectively. mRNA and protein expression levels of adherens, gap and tight junction components were measured in liver using reverse transcription quantitative real-time polymerase chain reaction analysis and immunoblot techniques, respectively. It was found that protein levels of the adherens junction building blocks β-catenin and γ-catenin, the gap junction components Cx26 and Cx32, and the tight junction constituent zonula occludens 2 were decreased, while mRNA levels of the adherens junction building block E-cadherin, and the tight junction constituent zonula occludens 2 and claudin 1 were upregulated following paracetamol overdosing. Repeated administration of carbon tetrachloride increased protein levels of E-cadherin, β-catenin, Cx26, Cx32, Cx43 and claudin 1. The latter was reflected at the mRNA level. In conclusion, acute and chronic liver disease have different effects on cell junctions in liver.
PubMed: 36660194
DOI: 10.17179/excli2022-5559 -
Current Biology : CB Mar 2023Cell proliferation is central to epithelial tissue development, repair, and homeostasis. During cell division, small RhoGTPases control both actomyosin dynamics and...
Cell proliferation is central to epithelial tissue development, repair, and homeostasis. During cell division, small RhoGTPases control both actomyosin dynamics and cell-cell junction remodeling to faithfully segregate the genome while maintaining tissue polarity and integrity. To decipher the mechanisms of RhoGTPase spatiotemporal regulation during epithelial cell division, we generated a transgenic fluorescently tagged library for the 48 Drosophila Rho guanine exchange factors (RhoGEFs) and GTPase-activating proteins (GAPs), and we systematically characterized their endogenous distributions by time-lapse microscopy. Therefore, we unveiled candidate regulators of the interplay between actomyosin and junctional dynamics during epithelial cell division. Building on these findings, we established that the conserved RhoGEF Cysts and RhoGEF4 play sequential and distinct roles to couple cytokinesis with de novo junction formation. During ring contraction, Cysts via Rho1 participates in the neighbor mechanosensing response, promoting daughter-daughter cell membrane juxtaposition in preparation to de novo junction formation. Subsequently and upon midbody formation, RhoGEF4 via Rac acts in the dividing cell to ensure the withdrawal of the neighboring cell membranes, thus controlling de novo junction length and cell-cell arrangements upon cytokinesis. Altogether, our findings delineate how the RhoGTPases Rho and Rac are locally and temporally activated during epithelial cytokinesis, highlighting the RhoGEF/GAP library as a key resource to understand the broad range of biological processes regulated by RhoGTPases.
Topics: Animals; Rho Guanine Nucleotide Exchange Factors; Actomyosin; Cell Division; Epithelial Cells; Cytokinesis; Drosophila
PubMed: 36917931
DOI: 10.1016/j.cub.2023.01.028 -
Nature Communications Jul 2022The formation of a functional blood vessel network relies on the ability of endothelial cells (ECs) to dynamically rearrange their adhesive contacts in response to blood...
The formation of a functional blood vessel network relies on the ability of endothelial cells (ECs) to dynamically rearrange their adhesive contacts in response to blood flow and guidance cues, such as vascular endothelial growth factor-A (VEGF-A) and class 3 semaphorins (SEMA3s). Neuropilin 1 (NRP1) is essential for blood vessel development, independently of its ligands VEGF-A and SEMA3, through poorly understood mechanisms. Grounding on unbiased proteomic analysis, we report here that NRP1 acts as an endocytic chaperone primarily for adhesion receptors on the surface of unstimulated ECs. NRP1 localizes at adherens junctions (AJs) where, interacting with VE-cadherin, promotes its basal internalization-dependent turnover and favors vascular permeability initiated by histamine in both cultured ECs and mice. We identify a splice variant of tryptophanyl-tRNA synthetase (mini-WARS) as an unconventionally secreted extracellular inhibitory ligand of NRP1 that, by stabilizing it at the AJs, slows down both VE-cadherin turnover and histamine-elicited endothelial leakage. Thus, our work shows a role for NRP1 as a major regulator of AJs plasticity and reveals how mini-WARS acts as a physiological NRP1 inhibitory ligand in the control of VE-cadherin endocytic turnover and vascular permeability.
Topics: Adherens Junctions; Animals; Antigens, CD; Cadherins; Capillary Permeability; Endothelial Cells; Histamine; Ligands; Mice; Neuropilin-1; Proteomics; Tryptophan-tRNA Ligase; Vascular Endothelial Growth Factor A
PubMed: 35858913
DOI: 10.1038/s41467-022-31904-1 -
Annals of the New York Academy of... Sep 2022The integrity and functions of epithelial barriers depend on the formation of adherens junctions (AJs) and tight junctions (TJs). A characteristic feature of AJs and TJs... (Review)
Review
The integrity and functions of epithelial barriers depend on the formation of adherens junctions (AJs) and tight junctions (TJs). A characteristic feature of AJs and TJs is their association with the cortical cytoskeleton composed of actin filaments and nonmuscle myosin II (NM-II) motors. Mechanical forces generated by the actomyosin cytoskeleton are essential for junctional assembly, stability, and remodeling. Epithelial cells express two different actin proteins and three NM-II isoforms, all known to be associated with AJs and TJs. Despite their structural similarity, different actin and NM-II isoforms have distinct biochemical properties, cellular distribution, and functions. The diversity of epithelial actins and myosin motors could be essential for the regulation of different steps of junctional formation, maturation, and disassembly. This review focuses on the roles of actin and NM-II isoforms in controlling the integrity and barrier properties of various epithelia. We discuss the effects of the depletion of individual actin isoforms and NM-II motors on the assembly and barrier function of AJs and TJs in model epithelial monolayers in vitro. We also describe the functional consequences of either total or tissue-specific gene knockout of different actins and NM-II motors, with a focus on the development and integrity of different epithelia in vivo.
Topics: Actins; Actomyosin; Adherens Junctions; Epithelial Cells; Humans; Myosin Type II; Protein Isoforms; Tight Junctions
PubMed: 35673768
DOI: 10.1111/nyas.14808