Cell-matrix Adhesion Research Articles

Vinculin Y822 is an important determinant of ligand binding.

Vinculin is an actin-binding protein present at cell-matrix and cell-cell adhesions, which plays a critical role in bearing force experienced by cells and dissipating it onto the cytoskeleton. Recently, we identified a key tyrosine residue, Y822, whose phosphorylation plays a critical role in force transmission at cell-cell adhesions. The role of Y822 in human cancer remains unknown, even though Y822 is mutated to Y822C in uterine cancers. Here, we investigated the effect of this amino acid substitution and that of a phosphodeficient Y822F vinculin in cancer cells. We observed that the presence of the Y822C mutation led to cells that proliferate and migrate more rapidly and contained smaller focal adhesions when compared to cells with wild-type vinculin. In contrast, the presence of the Y822F mutation led to highly spread cells with larger focal adhesions and increased contractility. Furthermore, we provide evidence that Y822C vinculin forms a disulfide bond with paxillin, accounting for some of the elevated phosphorylated paxillin recruitment. Taken together, these data suggest that vinculin Y822 modulates the recruitment of ligands.

LGALS1 regulates cell adhesion to promote the progression of ovarian cancer.

The present study aimed to explore the significance and molecular mechanisms of galectin-1 (LGALS1) in ovarian cancer (OC). Using the Gene Expression Omnibus database and The Cancer Genome Atlas database, the results of the present study demonstrated that LGALS1 mRNA expression was markedly increased in OC and associated with advanced tumor, lymphatic metastasis and residual lesions. In Kaplan-Meier analysis, patients who expressed LGALS1 highly had a poor prognosis. Furthermore, using The Cancer Genome Atlas database, differentially expressed genes that are potentially regulated by LGALS1 in OC were determined. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Set Enrichment Analysis were used to build a biological network of upregulated differentially expressed genes. The results of the enrichment analysis revealed that the upregulated differentially expressed genes were primarily associated with 'ECM-receptor interaction', 'cell-matrix adhesion' and 'focal adhesion', which are closely associated with the metastasis of cancer cells. Subsequently, cell adhesion was selected for further analysis. The results demonstrated that LGALS1 was co-expressed with the candidate genes. Subsequently, the elevated expression levels of candidate genes were verified in OC tissues, and survival analysis indicated that high expression of candidate genes was associated with shortened overall survival of patients with OC. In the present study, OC samples were also collected to verify the high protein expression levels of LGALS1 and fibronectin 1. The results of the present study highlighted that LGALS1 may regulate cell adhesion and participate in the development of OC. Therefore, LGALS1 exhibits potential as a therapeutic target in OC.

Tamoxifen decreases ovarian toxicity without compromising cancer treatment in a rat model of mammary cancer

BackgroundPremenopausal women diagnosed with breast cancer often face aggressive chemotherapy resulting in infertility. Tamoxifen (TAM) is a selective estrogen receptor modulator that was previously suggested as a protective agent against chemotherapy-induced ovarian failure. In the current study, we examined mechanisms of the protective action of TAM in the ovaries of tumor-bearing rats treated with the chemotherapy drug cyclophosphamide (CPA).ResultsTAM prevented CPA-induced loss of ovarian follicular reserves. The protective TAM effect in the rat ovary partially resulted from decreased apoptosis. In addition, transcriptomic and proteomic screening also implicated the importance of DNA repair pathways as well as cell adhesion and extracellular matrix remodeling in the protective ovarian actions of TAM.ConclusionsTamoxifen shielded the ovary from the side effects of chemotherapy without lessening the tumoricidal actions of mammary cancer treatment.Graphical

Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation.

Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.

Smooth Muscle-Alpha Actin R149C Pathogenic Variant Downregulates Integrin Recruitment at Cell-Matrix Adhesions and Decreases Cellular Contractility.

Thoracic aortic aneurysm is found in patients with ACTA2 pathogenic variants. ACTA2 missense variants are associated with impaired aortic smooth muscle cell (SMC) contraction. This study tested the hypothesis that the Acta2R149C/+ variant alters actin isoform expression and decreases integrin recruitment, thus, reducing aortic contractility. Stress relaxation measurements in thoracic aortic rings showed two functional regimes with a reduction of stress relaxation in the aorta from Acta2R149C/+ mice at low tension, but not at high tension values. Contractile responses to phenylephrine and potassium chloride were 50% lower in Acta2R149C/+ mice than in wild-type (WT) mice. Additionally, SMC were immunofluorescently labeled for specific proteins and imaged by confocal or total internal reflection fluorescence microscopy. The quantification of protein fluorescence of Acta2R149C/+ SMC showed a downregulation in smooth muscle α-actin (SMα-actin) and a compensatory upregulation of smooth muscle γ-actin (SMγ-actin) compared to WT cells. These results suggest that downregulation of SMα-actin leads to reduced SMC contractility, while upregulation of SMγ-actin may lead to increased SMC stiffness. Decreased α5β1 and α2β1 integrin recruitment at cell-matrix adhesions further reduce the ability of mutant cells to participate in cell-matrix crosstalk. Collectively, the results suggest that mutant Acta2R149C/+ aortic SMC have reduced contractility and interaction with the matrix, which are potential long-term contributing factors to thoracic aortic aneurysms.

Modulation of Piezo1 influences human skin architecture and oxytocin expression.

Throughout our existence, the skin senses and analyses the mechanical forces imposed by the environment. In response to these environmental forces, skin can deform itself and achieve a biological response. The subsequent cutaneous plasticity emerges from mechanical properties arising from the collective action of the skin cells, particularly keratinocytes, that govern the tensile strength via cell-to-cell adhesions and via cell-matrix adhesion structures. In addition to serving as force-bearing entities, keratinocytes respond to forces by activating signalling pathways to control their own fate and function. To detect and adapt to mechanical signals, keratinocytes possess a panel of sensory receptors and junctional intercellular structures. Mechanically activated ion channel Piezo1 has been described as a force sensor and as being involved in pleasant touch perception. In this study, relationships between Piezo1 modulation and oxytocin synthesis were investigated. The expression of Piezo1 in the skin was studied and compared with the expression of TRPV1. Dooku1 antagonist and Jedi1 agonist were used to modulate Piezo1. The level of E-cadherin and oxytocin was monitored in ex vivo skin biopsies by immunodetection. Taken together, our results illustrate the major role of mechanosensitive ion channel Piezo1 in skin barrier integrity, and in peripheral oxytocin synthesis in the skin. In conclusion, this study highlights the relationships between pleasant touch, soft touch and local oxytocin synthesis.

Reticular adhesions are assembled at flat clathrin lattices and opposed by active integrin α5β1.

Reticular adhesions (RAs) consist of integrin αvβ5 and harbor flat clathrin lattices (FCLs), long-lasting structures with similar molecular composition as clathrin-mediated endocytosis (CME) carriers. Why FCLs and RAs colocalize is not known. Here, we show that RAs are assembled at FCLs in a process controlled by fibronectin (FN) and its receptor, integrin α5β1. We observed that cells on FN-rich matrices displayed fewer FCLs and RAs. CME machinery inhibition abolished RAs and live-cell imaging showed that RA establishment requires FCL coassembly. The inhibitory activity of FN was mediated by the activation of integrin α5β1 at Tensin1-positive fibrillar adhesions. Conventionally, endocytosis disassembles cellular adhesions by internalizing their components. Our results present a novel paradigm in the relationship between these two processes by showing that endocytic proteins can actively function in the assembly of cell adhesions. Furthermore, we show this novel adhesion assembly mechanism is coupled to cell migration via unique crosstalk between cell-matrix adhesions.

TRPV4 regulates β1 integrin-mediated cell-matrix adhesions and collagen remodeling.

Transient Receptor Potential Vanilloid-type 4 (TRPV4) is a mechanosensitive, Ca2+ -permeable plasma membrane channel that associates with focal adhesions, influences collagen remodeling, and is associated with fibrotic processes through undefined mechanisms. While TRPV4 is known to be activated by mechanical forces transmitted through collagen adhesion receptors containing the β1 integrin, it is not understood whether TRPV4 affects matrix remodeling by altering β1 integrin expression and function. We tested the hypothesis that TRPV4 regulates collagen remodeling through its impact on the β1 integrin in cell-matrix adhesions. In cultured fibroblasts derived from mouse gingival connective tissues, which exhibit very rapid collagen turnover, we found that higher TRPV4 expression is associated with reduced β1 integrin abundance and adhesion to collagen, reduced focal adhesion size and total adhesion area, and reduced alignment and compaction of extracellular fibrillar collagen. The reduction of β1 integrin expression mediated by TRPV4 is associated with the upregulation of miRNAs that target β1 integrin mRNA. Our data suggest a novel mechanism by which TRPV4 modulates collagen remodeling through post-transcriptional downregulation of β1 integrin expression and function.

ADAMDEC1 induces EMT and promotes colorectal cancer cells metastasis by enhancing Wnt/β-catenin signaling via negative modulation of GSK-3β

Colorectal cancer (CRC) is a highly invasive malignant tumor with pronounced proliferation capacity and is prone to epithelial-mesenchymal transition (EMT) and subsequent metastasis. A disintegrin and metalloproteinase domain-like decysin 1 (ADAMDEC1) is a proteolytically active metzincin metalloprotease that is involved in extracellular matrix remodeling, cell adhesion, invasion, and migration. However, the effects of ADAMDEC1 on CRC are unclear. This study was conducted to investigate the expression and biological role of ADAMDEC1 in CRC. We found that ADAMDEC1 was differentially expressed in CRC. Further, ADAMDEC1 was found to enhance CRC proliferation, migration, and invasion while inhibiting apoptosis. Exogenous ADAMDEC1 overexpression elicited EMT in CRC cells, as evidenced by alterations in E-cadherin, N-cadherin, and vimentin expression. In ADAMDEC1 knockdown or ADAMDEC1 overexpressed CRC cells, the western blotting analysis revealed that Wnt/β-catenin signaling pathway-related proteins were down-regulated or up-regulated. Furthermore, an inhibitor of the Wnt/β-catenin pathway (FH535) partially negated the effect of ADAMDEC1 overexpression on EMT and CRC cell proliferation. Further mechanistic research suggested that ADAMDEC1 knockdown may upregulate GSK-3β and inactivate the Wnt/β-catenin pathway, accompanied by suppressing the expression of β-catenin. Additionally, the blocker of GSK-3β (CHIR-99021) markedly abolished the inhibitory effect of ADAMDEC1 knockdown on Wnt/β-catenin signaling. Our results indicate that ADAMDEC1 promotes CRC metastasis by negatively regulating GSK-3β, activating the Wnt/β-catenin signaling pathway, and inducing EMT, presenting its potential as a therapeutic target for the treatment of metastatic CRC.

The long non-coding RNA, miRNA and mRNA landscapes ofcementoblasts during cementogenesis.

Stimulation of cementogenesis is essential to cementum regeneration and root restoration. Long non-coding RNAs (lncRNAs) participate in the regulatory networks of periodontal regeneration processes. We identified and analysed differentially expressed lncRNAs, miRNAs and mRNAs associated with cementogenic differentiation of cementoblasts. OCCM-30 immortalized mouse cementoblast cells were induced in cementogenic medium for 7 and 14 days. Total RNA was extracted and subjected to RNA sequencing to screen for differentially expressed lncRNAs, miRNAs and mRNAs. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to determine the expression levels of RNAs. Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to clarify the potential functions of differentially expressed genes in biological processes and pathways. lncRNA-miRNA-mRNA networks were constructed based on correlation and algorithmic analyses. In all, 461 lncRNAs, 89 miRNAs and 2157 mRNAs showed differential expression in OCCM-30 cells after cementoblast differentiation. At day 7, upregulation of 248 lncRNAs, 30 miRNAs and 905 mRNAs was observed, along with downregulation of 127 lncRNAs, 34 miRNAs and 960 mRNAs. At day 14, 197 lncRNAs, 13 miRNAs and 847 mRNAs were upregulated, while 74 lncRNAs, 12 miRNAs and 760 mRNAs were downregulated. The results of qRT-PCR showed that four candidate lncRNAs, H19, Gdap10, Foxo6os and Ipw, were significantly upregulated after 7 and 14 days of cementogenic induction. The lncRNA-miRNA-mRNA network illustrated a possible competitive endogenous RNA regulatory mechanism. GO analysis showed that consistently differentially expressed mRNAs were involved in blood vessel morphogenesis, cell-substrate adhesion, cell adhesion, ossification and extracellular matrix organization. KEGG analysis indicated that extracellular matrix-receptor interaction, focal adhesion, and the PI3K-Akt, Rap1, mitogen-activated protein kinase, and Ras signalling pathways varied significantly during cementogenesis. The expressions of lncRNA, miRNA and mRNA were significantly altered in cementoblasts after cementogenesis. This study highlighted the effect of lncRNAs in the process of cementogenesis and revealed their potential for the discovery of novel biomarkers and therapeutic targets for cementum regeneration.

Redox sensitive thiols identified on Jagged1 regulate endothelial cell cycle, adhesion, and extracellular matrix proteins

Redox sensitive thiols identified on Jagged1 regulate endothelial cell cycle, adhesion, and extracellular matrix proteins

Identification of key genes in HER2-positive breast cancer with brain metastasis via bioinformatics methods.

Brain metastasis (BM) represents one of the most common advanced disease states in breast cancer (BC), especially in human epidermal growth factor receptor 2 (HER2)-positive BC, and is associated with poor survival outcomes. In this study, in-depth analysis of the microarray data from the GSE43837 dataset with 19 BM samples of HER2-positive BC patients and 19 HER2-positive nonmetastatic primary BC samples was conducted. The differentially expressed genes (DEGs) between BM and primary BC samples were identified and function enrichment analysis of the DEGs was conducted to identify potential biological functions. The hub genes were identified by constructing the protein-protein interaction (PPI) network using STRING and Cytoscape. UALCAN and Kaplan-Meier plotter online tools were used to verify the clinical roles of the hub DEGs in HER2-positive BC with BM (BCBM). A total of 1,056 DEGs including 767 downregulated and 289 upregulated genes were identified by comparing the microarray data of the HER2-positive BM and primary BC samples. Functional enrichment analysis demonstrated that the DEGs were mainly enriched in pathways related to extracellular matrix (ECM) organization, cell adhesion, and collagen fibril organization. PPI network analysis identified 14 hub genes. Among these, CD44, COL1A2, MMP14, POSTN, and SOX9 were associated with the survival outcomes of HER2-positive patients. In summary, 5 BM-specific hub genes were identified in the study; those are potential prognostic biomarkers and therapeutic targets for HER2-positive BCBM patients. However, further investigations are necessary to unravel the mechanisms by which these 5 hub genes regulate BM in HER2-positive BC.

Initiation of fibronectin fibrillogenesis is an enzyme-dependent process

Fibronectin fibrillogenesis and mechanosensing both depend on integrin-mediated force transmission to the extracellular matrix. However, force transmission is in itself dependent on fibrillogenesis, and fibronectin fibrils are found in soft embryos where high forces cannot be applied, suggesting that force cannot be the sole initiator of fibrillogenesis. Here, we identify a nucleation step prior to force transmission, driven by fibronectin oxidation mediated by lysyl oxidase enzyme family members. This oxidation induces fibronectin clustering, which promotes early adhesion, alters cellular response to soft matrices, and enhances force transmission to the matrix. In contrast, absence of fibronectin oxidation abrogates fibrillogenesis, perturbs cell-matrix adhesion, and compromises mechanosensation. Moreover, fibronectin oxidation promotes cancer cell colony formation in soft agar as well as collective and single-cell migration. These results reveal a force-independent enzyme-dependent mechanism that initiates fibronectin fibrillogenesis, establishing a critical step in cell adhesion and mechanosensing.

Immunolocalization of epithelial cell adhesion molecule and matrix metalloproteinase-9 in oral epithelial dysplasia and oral squamous cell carcinoma.

Cancers are complex tissues composed of multiple distinct cell types that participate in heterotypic interactions with one another. Physiologically cell-to-cell contacts formed by dense populations of normal cells operate to suppress further cell proliferation. The objective of the study is to evaluate and compare the immunoexpression of matrix metalloproteinase-9 (MMP-9) and epithelial cell adhesion molecule (EpCAM) in oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) and to hypothesize their role in the progression in varying grades of these lesions. A total of 60 samples comprising of 30 cases each of OED and OSCC. Three micrometers thin sections were taken and subjected for hematoxylin and eosin stain and immunohistochemical procedure. The sections were incubated with monoclonal anti-EpCAM anti-MMP-9 antibody. The data were analyzed using SPSS software version 19. The results of the study show EpCAM immunoexpression decreased in OSCC when compared to OED. MMP-9 immunoexpression increased in OSCC when compared to OED (statistically significant, P ≤ 0.05). Correlation between EpCAM and MMP-9 may help to unravel the signaling cascades involved in the carcinomatous changes, tumor cell invasion, and progression of OSCCs.

Characterization of Porcine Ocular Surface Epithelial Microenvironment.

The porcine ocular surface is used as a model of the human ocular surface; however, a detailed characterization of the porcine ocular surface has not been documented. This is due, in part, to the scarcity of antibodies produced specifically against the porcine ocular surface cell types or structures. We performed a histological and immunohistochemical investigation on frozen and formalin-fixed, paraffin-embedded ocular surface tissue from domestic pigs using a panel of 41 different antibodies related to epithelial progenitor/differentiation phenotypes, extracellular matrix and associated molecules, and various niche cell types. Our observations suggested that the Bowman's layer is not evident in the cornea; the deep invaginations of the limbal epithelium in the limbal zone are analogous to the limbal interpalisade crypts of human limbal tissue; and the presence of goblet cells in the bulbar conjunctiva. Immunohistochemistry analysis revealed that the epithelial progenitor markers cytokeratin (CK)15, CK14, p63α, and P-cadherin were expressed in both the limbal and conjunctival basal epithelium, whereas the basal cells of the limbal and conjunctival epithelium did not stain for CK3, CK12, E-cadherin, and CK13. Antibodies detecting marker proteins related to the extracellular matrix (collagen IV, Tenascin-C), cell-matrix adhesion (β-dystroglycan, integrin α3 and α6), mesenchymal cells (vimentin, CD90, CD44), neurons (neurofilament), immune cells (HLA-ABC; HLA-DR, CD1, CD4, CD14), vasculature (von Willebrand factor), and melanocytes (SRY-homeobox-10, human melanoma black-45, Tyrosinase) on the normal human ocular surface demonstrated similar immunoreactivity on the normal porcine ocular surface. Only a few antibodies (directed against N-cadherin, fibronectin, agrin, laminin α3 and α5, melan-A) appeared unreactive on porcine tissues. Our findings characterize the main immunohistochemical properties of the porcine ocular surface and provide a morphological and immunohistochemical basis useful to research using porcine models. Furthermore, the analyzed porcine ocular structures are similar to those of humans, confirming the potential usefulness of pig eyes to study ocular surface physiology and pathophysiology.

A Prognostic Model Based on NSUN3 Was Established to Evaluate the Prognosis and Response to Immunotherapy in Liver Hepatocellular Carcinoma.

It is difficult for traditional therapies to further improve the prognosis of hepatocellular carcinoma (LIHC), and immunotherapy is considered to be a promising approach to overcome this dilemma. However, only a minority of patients benefit from immunotherapy, which greatly limits its application. Therefore, it is particularly urgent to elucidate the specific regulatory mechanism of tumor immunity so as to provide a new direction for immunotherapy. NOP2/Sun RNA methyltransferase 3 (NSUN3) is a protein with RNA binding and methyltransferase activity, which has been shown to be involved in the occurrence and development of a variety of tumors. At present, the relationship between NSUN3 and immune implication in LIHC has not been reported. In this study, we first revealed that NSUN3 expression is upregulated in LIHC and that patients with high NSUN3 expression have a poor prognosis through multiple databases. Pathway enrichment analysis demonstrated that NSUN3 may be participated in cell adhesion and cell matrix remodeling. Next, we obtained a set of genes coexpressed with NSUN3 (NCGs). Further LASSO regression was performed based on NCGs, and a risk score model was constructed, which proved to have good predictive power. In addition, Cox regression analysis revealed that the risk score of NCGs model was an independent risk factor for LIHC patients. Moreover, we established a nomogram based on the NCGs-related model, which was verified to have a good predictive ability for the prognosis of LIHC. Furthermore, we investigated the relationship between NCGs-related model and immune implication. The results implied that our model was closely related to immune score, immune cell infiltration, immunotherapy response, and multiple immune checkpoints. Finally, the pathway enrichment analysis of NCGs-related model showed that the model may be involved in the regulation of various immune pathways. In conclusion, our study revealed a novel role of NSUN3 in LIHC. The NSUN3-based prognostic model may be a promising biomarker for inspecting the prognosis and immunotherapy response of LIHC.

ConFERMing the role of talin in integrin activation and mechanosignaling.

Talin (herein referring to the talin-1 form), is a cytoskeletal adapter protein that binds integrin receptors and F-actin, and is a key factor in the formation and regulation of integrin-dependent cell-matrix adhesions. Talin forms the mechanical link between the cytoplasmic domain of integrins and the actin cytoskeleton. Through this linkage, talin is at the origin of mechanosignaling occurring at the plasma membrane-cytoskeleton interface. Despite its central position, talin is not able to fulfill its tasks alone, but requires help from kindlin and paxillin to detect and transform the mechanical tension along the integrin-talin-F-actin axis into intracellular signaling. The talin head forms a classical FERM domain, which is required to bind and regulate the conformation of the integrin receptor, as well as to induce intracellular force sensing. The FERM domain allows the strategic positioning of protein-protein and protein-lipid interfaces, including the membrane-binding and integrin affinity-regulating F1 loop, as well as the interaction with lipid-anchored Rap1 (Rap1a and Rap1b in mammals) GTPase. Here, we summarize the structural and regulatory features of talin and explain how it regulates cell adhesion and force transmission, as well as intracellular signaling at integrin-containing cell-matrix attachment sites.

First person – Rajeshwari B. R.

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping researchers promote themselves alongside their papers. Rajeshwari B. R. is first author on ‘ Kinetics of Arf1 inactivation regulates Golgi organization and function in non-adherent fibroblasts’, published in BiO. Rajeshwari is a PhD student in the lab of Dr Nagaraj Balasubramanian at the Indian Institute of Science Education and Research (IISER), Pune, investigating the role of cell-matrix adhesion in regulating the Golgi organization and function.

Targeted VEGFA therapy in regulating early acute kidney injury and late fibrosis.

Damage to peritubular capillaries is a key process that contributes to acute kidney injury (AKI) progression. Vascular endothelial growth factor A (VEGFA) plays a critical role in maintaining the renal microvasculature. However, the physiological role of VEGFA in various AKI durations remains unclear. A severe unilateral ischemia‒reperfusion injury model was established to provide an overview of VEGFA expression and the peritubular microvascular density from acute to chronic injury in mouse kidneys. Therapeutic strategies involving early VEGFA supplementation protecting against acute injury and late anti-VEGFA treatment for fibrosis alleviation were analyzed. A proteomic analysis was conducted to determine the potential mechanism of renal fibrosis alleviation by anti-VEGFA. The results showed that two peaks of extraglomerular VEGFA expression were observed during AKI progression: one occurred at the early phase of AKI, and the other occurred during the transition to chronic kidney disease (CKD). Capillary rarefaction progressed despite the high expression of VEGFA at the CKD stage, and VEGFA was associated with interstitial fibrosis. Early VEGFA supplementation protected against renal injury by preserving microvessel structures and counteracting secondary tubular hypoxic insults, whereas late anti-VEGFA treatment attenuated renal fibrosis progression. The proteomic analysis highlighted an array of biological processes related to fibrosis alleviation by anti-VEGFA, which included regulation of supramolecular fiber organization, cell-matrix adhesion, fibroblast migration, and vasculogenesis. These findings establish the landscape of VEGFA expression and its dual roles during AKI progression, which provides the possibility for the orderly regulation of VEGFA to alleviate early acute injury and late fibrosis.

Sensing context: Inhibitory receptors on non-hematopoietic cells.

Similar to immune cells, non-hematopoietic cells recognize microbial and endogenous threats. Their response to these stimuli is dependent on the environmental context. For example, intact intestinal epithelium expresses pattern recognition receptors (PRRs) but should tolerate commensal bacteria, while damaged epithelium should respond promptly to initiate an immune response. This indicates that non-hematopoietic cells possess mechanisms to sense environmental context and regulate their responses. Inhibitory receptors provide context sensing to immune cells. For instance, they raise the threshold for activation to prevent overzealous immune activation to harmless stimuli. Inhibitory receptors are typically studied on hematopoietic cells, but several of these receptors are expressed on non-hematopoietic cells. Here, we review evidence for the regulation of non-hematopoietic cells by inhibitory receptors, focusing on epithelial and endothelial cells. We explain that inhibitory receptors on these cells can sense a wide range of signals, including cell-cell adhesion, cell-matrix adhesion, and apoptotic cells. More importantly, they regulate various functions on these cells, including immune activation, proliferation, and migration. In conclusion, we propose that inhibitory receptors provide context to non-hematopoietic cells by fine tuning their response to endogenous or microbial stimuli. These findings prompt to investigate the functions of inhibitory receptors on non-hematopoietic cells more systematically.