At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence especially because of the propensity of the OC cells to spread in the abdominal cavity leading to peritoneal metastasis. The influence of ascites on the development of pre-metastatic niches, and on the biological mechanisms leading to cancer cell colonization of the mesothelium, remains poorly understood. Here, we show that ascites weakens the mesothelium by affecting the morphology of mesothelial cells and by destabilizing their distribution in the cell cycle. Ascites also causes destabilization of the integrity of mesothelium by modifying the organization of cell junctions, but it does not affect the synthesis of N-cadherin and ZO-1 by mesothelial cells. Moreover, ascites induces disorganization of focal contacts and causes actin cytoskeletal reorganization potentially dependent on the activity of Rac1. Ascites allows the densification and reorganization of ECM proteins of the mesothelium, especially fibrinogen/fibrin, and indicates that it is a source of the fibrinogen and fibrin surrounding OC spheroids. The fibrin in ascites leads to the adhesion of OC spheroids to the mesothelium, and ascites promotes their disaggregation followed by the clearance of mesothelial cells. Both αV and α5β1 integrins are involved. In conclusion ascites and its fibrinogen/fibrin composition affects the integrity of the mesothelium and promotes the integrin-dependent implantation of OC spheroids in the mesothelium.

The physical properties of nanoscale cell-extracellular matrix (ECM) ligands profoundly impact biological processes, such as adhesion, motility, and differentiation. While the mechanoresponse of cells to static ligands is well-studied, the effect of dynamic ligand presentation with \"adaptive\" properties on cell mechanotransduction remains less understood. Utilizing a controllable diffusible ligand interface, we demonstrated that cells on surfaces with rapid ligand mobility could recruit ligands through activating integrin α5β1, leading to faster focal adhesion growth and spreading at the early adhesion stage. By leveraging UV-light-sensitive anchor molecules to trigger a \"dynamic to static\" transformation of ligands, we sequentially activated α5β1 and αvβ3 integrins, significantly promoting osteogenic differentiation of mesenchymal stem cells. This study illustrates how manipulating molecular dynamics can directly influence stem cell fate, suggesting the potential of \"sequentially\" controlled mobile surfaces as adaptable platforms for engineering smart biomaterial coatings.

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the macula. The formation of macular neovascularization (MNV) and subretinal fibrosis of AMD is the most classic cause of the loss of vision in older adults worldwide. While the underlying causes of MNV and subretinal fibrosis remain elusive, the common feature of many common retinal diseases is changes the proportions of protein deposition in extracellular matrix (ECM) when compared to normal tissue. In ECM, fibronectin (FN) is a crucial component and plays a pivotal part not only in fibrotic diseases but also in the process of angiogenesis. The study aims to understand the role of ligand FN and its common integrin receptor α5β1 on MNV, and to understand the molecular mechanism involved. To study this, the laser-induced MNV mouse model and the rhesus macaque choroid-retinal endothelial cell line (RF/6A) chemical hypoxia mode were established, and the FN-α5β1 expression levels were detected by immunohistochemistry (IHC) and quantitative real-time PCR analysis (qRT-PCR). Fibronectin expression was silenced using small interfering RNA (siRNA) targeting FN. The tube formation and vitro scratch assays were used to assess the ability to form blood vessels and cell migration. To measure the formation of MNV, immunofluorescence, and Western blot assays were used. These results revealed that the expressions of FN and integrin α5β1 were distinctly increased in the laser-induced MNV mouse model and in the RF/6A cytochemically induced hypoxia model, and the expression tendency was identical. After the use of FN siRNA, the tube formation and migration abilities of the RF/6A cells were lower, the ability of endothelial cells to proliferate was confined and the scope of damage caused by the laser in animal models was significantly cut down. In addition, FN gene knockdown dramatically inhibited the expression of Wnt/β-catenin signal. The interaction of FN with the integrin receptor α5β1 in the constructed model, which may act through the Wnt/β-catenin signaling pathway, was confirmed in this study. In conclusion, FN may be a potential new molecular target for the prevention and treatment of subretinal fibrosis and MNV.

BACKGROUND: Acute type A aortic dissection (AAAD) is a devastating disease. Human aortic smooth muscle cells (HASMCs) exhibit decreased proliferation and increased apoptosis, and integrin α5β1 and FAK are important proangiogenic factors involved in regulating angiogenesis. The aim of this study was to investigate the role of integrin α5β1 and FAK in patients with AAAD and the potential underlying mechanisms.
METHODS: Aortic tissue samples were obtained from 8 patients with AAAD and 4 organ donors at Zhongshan Hospital of Fudan University. The level of apoptosis in the aortic tissues was assessed by immunohistochemical (IHC) staining and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assays. The expression of integrin α5β1 and FAK was determined. Integrin α5β1 was found to be significantly expressed in HASMCs, and its interaction with FAK was assessed via coimmunoprecipitation (Co-IP) analysis. Proliferation and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assays and flow cytometry after integrin α5β1 deficiency.
RESULTS: The levels of integrin α5β1 and FAK were both significantly decreased in patients with AAAD. Downregulating the expression of integrin α5β1-FAK strongly increased apoptosis and decreased proliferation in HASMCs, indicating that integrin α5β1-FAK might play an important role in the development of AAAD.
CONCLUSIONS: Downregulation of integrin α5β1-FAK is associated with increased apoptosis and decreased proliferation in aortic smooth muscle cells and may be a potential therapeutic strategy for AAAD.

Primary tumor growth and metastasis in triple-negative breast cancer (TNBC) require supporting vasculature, which develop through a combination of endothelial angiogenesis and vasculogenic mimicry (VM), a process associated with aggressive metastatic behavior in which vascular-like structures are lined by tumor cells. We developed αEGFR-E-P125A, an antibody-endostatin fusion protein that delivers a dimeric, mutant endostatin (E-P125A) payload that inhibits TNBC angiogenesis and VM in vitro and in vivo. To characterize the mechanisms associated with induction and inhibition of VM, RNA sequencing (RNA-seq) of MDA-MB-231-4175 TNBC cells grown in a monolayer (two-dimensional) was compared with cells plated on Matrigel undergoing VM [three-dimensional (3D)]. We then compared RNA-seq between TNBC cells in 3D and cells in 3D with VM inhibited by αEGFR-E-P125A (EGFR-E-P125A). Gene set enrichment analysis demonstrated that VM induction activated the IL6-JAK-STAT3 and angiogenesis pathways, which were downregulated by αEGFR-E-P125A treatment.Correlative analysis of the phosphoproteome demonstrated decreased EGFR phosphorylation at Y1069, along with decreased phosphorylation of focal adhesion kinase Y397 and STAT3 Y705 sites downstream of α5β1 integrin. Suppression of phosphorylation events downstream of EGFR and α5β1 integrin demonstrated that αEGFR-E-P125A interferes with ligand-receptor activation, inhibits VM, and overcomes oncogenic signaling associated with EGFR and α5β1 integrin cross-talk. In vivo, αEGFR-E-P125A treatment decreased primary tumor growth and VM, reduced lung metastasis, and confirmed the inhibition of signaling events observed in vitro. Simultaneous inhibition of EGFR and α5β1 integrin signaling by αEGFR-E-P125A is a promising strategy for the inhibition of VM, tumor growth, motility, and metastasis in TNBC and other EGFR-overexpressing tumors.
UNASSIGNED: αEGFR-E-P125A reduces VM, angiogenesis, tumor growth, and metastasis by inhibiting EGFR and α5β1 integrin signaling, and is a promising therapeutic agent for TNBC treatment, used alone or in combination with chemotherapy.

Laminins are essential in basement membrane architecture and critical in re-epithelialization and angiogenesis. These processes and collagen deposition are vital in skin wound healing. The role of angiogenic peptides in accelerating the wound-healing process has been known. The bioactive peptides could be a potential approach due to their similar effects as growth factors and inherent biocompatible and biodegradable nature with lower cost. They can also recognize ligand-receptor interaction and mimic the extracellular matrix. Here, we report novel angiogenic DYVRLAI, CDYVRLAI, angiogenic-collagen PGPIKVAV, and Ac-PGPIKVAV peptides conjugated sodium carboxymethyl cellulose hydrogel, which was designed from laminin. The designed peptide exhibits a better binding with the α3β1, αvβ3, and α5β1 integrins and CXCR2 receptor, indicating their angiogenic and collagen binding efficiency. The peptides were evaluated to stimulate wound healing in full-thickness excision wounds in normal and diabetic mice (type II). They demonstrated their efficacy in terms of angiogenesis (CD31), re-epithelialization through regeneration of the epidermis (H&E), and collagen deposition (MT). The synthesized peptide hydrogel (DYVRLAI and CDYVRLAI) showed enhanced wound contraction up to 10.1 % and 12.3 % on day 7th compared to standard becaplermin gel (49 %) in a normal wound model. The encouraging results were also observed with the diabetic model, where these peptides showed a significant decrease of 5.20 and 5.17 % in wound size on day 10th compared to the commercial gel (9.27 %). These outcomes signify that the modified angiogenic peptide is a cost effective, novel peptide motif to promote dermal wound healing in both models.

We previously found that the respiratory epithelial cells could eliminate the invaded group A streptococcus (GAS) through autophagy induced by binding a fibronectin (Fn) binding protein (FnBp) expressed on the surface of GAS to plasma protein Fn and its receptor integrin α5β1 of epithelial cells. Is autophagy initiated by FnBp+ bacteria via FnBp-Fn-Integrin α5β1 axis a common event in respiratory epithelial cells?
We chose Staphylococcus aureus (S. aureus/S. a) and Listeria monocytogenes (L. monocytogenes/L. m) as representatives of extracellular and intracellular FnBp+ bacteria, respectively. The FnBp of them was purified and the protein function was confirmed by western blot, viable bacteria count, confocal and pull-down. The key molecule downstream of the action axis was detected by IP, mass spectrometry and bio-informatics analysis.
We found that different FnBp from both S. aureus and L. monocytogenes could initiate autophagy through FnBp-Fn-integrin α5β1 axis and this could be considered a universal event, by which host tries to remove invading bacteria from epithelial cells. Importantly, we firstly reported that S100A8, as a key molecule downstream of integrin β1 chain, is highly expressed upon activation of integrin α5β1, which in turn up-regulates autophagy.
Various FnBp from FnBp+ bacteria have the ability to initiate autophagy via FnBp-Fn-Integrin α5β1 axis to promote the removal of invading bacteria from epithelial cells in the presence of fewer invaders. S100A8 is a key molecule downstream of Integrin α5β1 in this autophagy pathway.

Endothelial dysfunction plays a pivotal role in the pathogenesis of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Dipeptidyl peptidase IV (DPP-4), a cell surface glycoprotein, has been implicated in endothelial inflammation and barrier dysfunction. In this study, the role of DPP-4 on lipopolysaccharide (LPS)-induced pulmonary microvascular endothelial cells (HPMECs) dysfunction and the underlying mechanism were investigated by siRNA-mediated knockdown of DPP-4. Our results indicated that LPS (1 μg/ml) challenge resulted in either the production and releasing of DPP-4, as well as the secretion of IL-6 and IL-8 in HPMECs. DPP-4 knockdown inhibited chemokine releasing and monolayer hyper-permeability in LPS challenged HPMECs. When cocultured with human polymorphonuclear neutrophils (PMNs), DPP4 knockdown suppressed LPS-induced neutrophil-endothelial adhesion, PMN chemotaxis and trans-endothelial migration. Western blotting showed that DPP-4 knockdown attenuated LPS-induced activation of TLR4/NF-κB pathway. Immunoprecipitation and liquid chromatography-tandem mass spectrometry revealed that DPP-4 mediated LPS-induced endothelial inflammation by interacting with integrin-α5β1. Moreover, exogenous soluble DPP-4 treatment sufficiently activated integrin-α5β1 downstream FAK/AKT/NF-κB signaling, thereafter inducing ICAM-1 upregulation in HPMECs. Collectively, our results suggest that endothelia synthesis and release DPP-4 under the stress of endotoxin, which interact with integrin-α5β1 complex in an autocrine or paracrine manner to exacerbate endothelial inflammation and enhance endothelial cell permeability. Therefore, blocking DDP-4 could be a potential therapeutic strategy to prevent endothelial dysfunction in ALI/ARDS.

Head and neck squamous cell carcinoma (HNSCC) remains a formidable clinical challenge due to its high recurrence rate and limited targeted therapeutic options. This study aims to elucidate the role of tensin 4 (TNS4) in the pathogenesis of HNSCC across clinical, cellular, and animal levels. We found a significant upregulation of TNS4 expression in HNSCC tissues compared to normal controls. Elevated levels of TNS4 were associated with adverse clinical outcomes, including diminished overall survival. Functional assays revealed that TNS4 knockdown attenuated, and its overexpression augmented, the oncogenic capabilities of HNSCC cells both in vitro and in vivo. Mechanistic studies revealed that TNS4 overexpression promotes the interaction between integrin α5 and integrin β1, thereby activating focal adhesion kinase (FAK). This TNS4-mediated FAK activation simultaneously enhanced the PI3K/Akt signaling pathway and facilitated the interaction between TGFβRI and TGFβRII, leading to the activation of the TGFβ signaling pathway. Both of these activated pathways contributed to HNSCC tumorigenesis. Additionally, we found that hypoxia-inducible factor 1α (HIF-1α) transcriptionally regulated TNS4 expression. In conclusion, our findings provide the basis for innovative TNS4-targeted therapeutic strategies, which could potentially improve prognosis and survival rates for patients with HNSCC.

Integrins are cell surface nanosized receptors crucial for cell motility and mechanosensing of the extracellular environment, which are often targeted for the development of biomaterials and nanomedicines. As a key feature of integrins, their activity, structure and behavior are highly mechanosensitive, which are regulated by mechanical forces down to pico-Newton scale. Using single-molecule biomechanical approaches, we compared the force-modulated ectodomain bending/unbending conformational changes of two integrin species, α5β1 and αVβ3. It was found that the conformation of integrin α5β1 is determined by a threshold head-to-tail tension. By comparison, integrin αVβ3 exhibits bistability even without force and can spontaneously transition between the bent and extended conformations with an apparent transition time under a wide range of forces. Molecular dynamics simulations observed almost concurrent disruption of ∼2 hydrogen bonds during integrin α5β1 unbending, but consecutive disruption of ∼7 hydrogen bonds during integrin αVβ3 unbending. Accordingly, we constructed a canonical energy landscape for integrin α5β1 with a single energy well that traps the integrin in the bent state until sufficient force tilts the energy landscape to allow the conformational transition. In contrast, the energy landscape of integrin αVβ3 conformational changes was constructed with hexa-stable intermediate states and intermediate energy barriers that segregate the conformational change process into multiple small steps. Our study elucidates the different biomechanical inner workings of integrins α5β1 and αVβ3 at the submolecular level, helps understand their mechanosignaling processes and how their respective functions are facilitated by their distinctive mechanosensitivities, and provides useful design principles for the engineering of protein-based biomechanical nanomachines.