Vinculin in cell-cell and cell-matrix adhesions

F-Actin Dysplasia Involved in Organ of Corti Deformity in Gjb2 Knockdown Mouse Model

Mutations in the GJB2 gene encoding connexin26 (Cx26) protein are one of the most common causes of hereditary deafness. Previous studies have found that different Cx26-null mouse models have severe hearing loss and deformity of the organ of Corti (OC) as well as a reduction in microtubules in pillar cells (PCs). To explore the underlying mechanism of OC deformity caused by Cx26 downregulation further, we established Cx26 knockdown (KD) mouse models at postnatal days (P)0 and P8. The actin filaments contained in the pillar cells of mice in the P0 KD group were reduced by 54.85% and vinculin was increased by 22%, while the outer hair cells (OHCs) showed normal F-actin content. In the P8 KD group, PCs and OHCs of mice also showed almost normal F-actin content. The G-actin/F-actin ratio increased by 38% in the P0 KD group. No significant change was found in the mRNA or protein expression level of G-actin or the cadherin–catenin core complex in the P0 KD group at P6. Moreover, immunofluorescence showed that the intensity of LRRK2 was reduced by 97% in the P0 KD group at P6. Our results indicate that Cx26 is involved in the maturation of the cytoskeleton during the development of the OC at the early postnatal stage. The polymerization of G-actin into F-actin is prevented in Cx26 KD mice.

Into the Tissues: Extracellular Matrix and Its Artificial Substitutes: Cell Signalling Mechanisms

The existence of orderly structures, such as tissues and organs is made possible by cell adhesion, i.e., the process by which cells attach to neighbouring cells and a supporting substance in the form of the extracellular matrix. The extracellular matrix is a three-dimensional structure composed of collagens, elastin, and various proteoglycans and glycoproteins. It is a storehouse for multiple signalling factors. Cells are informed of their correct connection to the matrix via receptors. Tissue disruption often prevents the natural reconstitution of the matrix. The use of appropriate implants is then required. This review is a compilation of crucial information on the structural and functional features of the extracellular matrix and the complex mechanisms of cell-cell connectivity. The possibilities of regenerating damaged tissues using an artificial matrix substitute are described, detailing the host response to the implant. An important issue is the surface properties of such an implant and the possibilities of their modification.

Obesity influences the proteome of periodontal ligament tissues following periodontitis induction in rats

BACKGROUND AND OBJECTIVES

Many studies have been conducted to better understand the molecular mechanism involved with periodontitis progression. There has been growing interest in the potential impact of obesity on periodontitis onset and progression, but the mechanisms involved remain to be elucidated. The present study was designed to determine the impact of obesity on experimentally induced periodontitis in rats and identify novel pathways involved.

METHODS

Sixteen Holtzman rats were distributed into two groups (n = 8): ligature-induced periodontitis (P) and obesity plus ligature-induced periodontitis (OP). Obesity was induced by a high-fat diet for 70 days, whereas periodontitis was induced for 20 days, with a cotton thread placed around the upper first molars bilaterally. Alveolar bone loss was measured by microtomographic analysis and histologically by histometry on the hemimaxillae. The protein composition of the periodontal ligament was evaluated by proteomic analysis.

RESULTS

Data analysis (body weight, adipose tissue weight, and blood test) confirmed obesity induction, whereas bone loss was confirmed by micro-CT and histologic analyses. Proteome analysis from the periodontal ligament tissues (PDL) identified 819 proteins, 53 exclusive to the P group, 28 exclusive to the OP group, and 738 commonly expressed. Validation was performed by immunohistochemistry for selected proteins (spondin1, vinculin, and TRAP).

CONCLUSION

Histologically, it was found that obesity did not significantly affect bone loss resulting from periodontitis. However, the present study's findings indicated that obesity affects the proteome of PDL submitted to experimental periodontitis, allowing for identifying potential targets for personalized approaches.

Potential Therapeutic Applications of N-Cadherin Antagonists and Agonists

This review focuses on the cell adhesion molecule (CAM), known as neural (N)-cadherin (CDH2). The molecular basis of N-cadherin-mediated intercellular adhesion is discussed, as well as the intracellular signaling pathways regulated by this CAM. N-cadherin antagonists and agonists are then described, and several potential therapeutic applications of these intercellular adhesion modulators are considered. The usefulness of N-cadherin antagonists in treating fibrotic diseases and cancer, as well as manipulating vascular function are emphasized. Biomaterials incorporating N-cadherin modulators for tissue regeneration are also presented. N-cadherin antagonists and agonists have potential for broad utility in the treatment of numerous maladies.

Microgravity Modifies the Phenotype of Fibroblast and Promotes Remodeling of the Fibroblast-Keratinocyte Interaction in a 3D Co-Culture Model

Microgravity impairs tissue organization and critical pathways involved in the cell–microenvironment interplay, where fibroblasts have a critical role. We exposed dermal fibroblasts to simulated microgravity by means of a Random Positioning Machine (RPM), a device that reproduces conditions of weightlessness. Molecular and structural changes were analyzed and compared to control samples growing in a normal gravity field. Simulated microgravity impairs fibroblast conversion into myofibroblast and inhibits their migratory properties. Consequently, the normal interplay between fibroblasts and keratinocytes were remarkably altered in 3D co-culture experiments, giving rise to several ultra-structural abnormalities. Such phenotypic changes are associated with down-regulation of α-SMA that translocate in the nucleoplasm, altogether with the concomitant modification of the actin-vinculin apparatus. Noticeably, the stress associated with weightlessness induced oxidative damage, which seemed to concur with such modifications. These findings disclose new opportunities to establish antioxidant strategies that counteract the microgravity-induced disruptive effects on fibroblasts and tissue organization.

Reprogramming hormone sensitive prostate cancer to a lethal neuroendocrine cancer lineage by mitochondrial pyruvate carrier (MPC)

Cell lineage reprogramming is the main approach for cancer cells to acquire drug resistance and escape targeted therapy. The use of potent targeted therapies in cancers has led to the development of highly aggressive carcinoma, including neuroendocrine prostate cancer (NEPC). Although metabolic reprogramming has been reported to be essential for tumor growth and energy production, the relationship between metabolic reprogramming and lineage differentiation which can cause hormone therapy resistance has never been reported in prostate cancer (PCa). Moreover, as there is still no efficient therapy for NEPC, it is urgent to reverse this lineage differentiation during the hormone therapy. Here for the first time, we used in vitro and in vivo human PCa models to study the effect of metabolic reprogramming on the lineage differentiation from the androgen receptor (AR)–dependent adenocarcinoma to AR-independent NEPC. This lineage differentiation leads to antiandrogen drug resistance and tumor development. This phenotype is enabled by the loss of mitochondrial pyruvate carrier (MPC), the gate for mitochondrial pyruvate influx, and can be reversed by MPC overexpression. Morphologic and cellular studies also demonstrate that the pyruvate kinase M2 (PKM2) involved epithelium–mesenchymal transition process mediated this lineage alteration. Its inhibition is a potential treatment for MPC-lo tumors. All of these results suggest that metabolic rewiring can act as a starter for increased cellular plasticity which leads to antiandrogen therapy resistance through lineage differentiation. This study provides us with a potent treatment target for therapy-induced, enzalutamide-resistant NE-like prostate cancer.

1.

Metabolic rewiring induced by mitochondrial pyruvate carrier (MPC) loss can act as a starter for increased cellular lineage plasticity from adenocarcinoma into neuroendocrine prostate cancer (NEPC).

2.

An M2-pyruvate kinase (PKM2) involved epithelium–mesenchymal transition (EMT) process mediated this lineage switch from the androgen receptor (AR)–dependent adenocarcinoma to AR-independent neuroendocrine prostate cancer (NEPC); this process is induced by the decrease of mitochondria pyruvate influx.

3.

Mitochondria pyruvate influx can be a potential target for the NEPC treatment.

Understanding the molecular basis of cardiomyopathy

Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.

Canonical TGFβ signaling induces collective invasion in colorectal carcinogenesis through a Snail1- and Zeb1-independent partial EMT

Local invasion is the initial step towards metastasis, the main cause of cancer mortality. In human colorectal cancer (CRC), malignant cells predominantly invade as cohesive collectives and may undergo partial epithelial-mesenchymal transition (pEMT) at the invasive front. How this particular mode of stromal infiltration is generated is unknown. Here we investigated the impact of oncogenic transformation and the microenvironment on tumor cell invasion using genetically engineered organoids as CRC models. We found that inactivation of the Apc tumor suppressor combined with expression of oncogenic Kras^G12D and dominant-negative Trp53^R172H did not cell-autonomously induce invasion in vitro. However, oncogenic transformation primed organoids for activation of a collective invasion program upon exposure to the prototypical microenvironmental factor TGFβ1. Execution of this program co-depended on a permissive extracellular matrix which was further actively remodeled by invading organoids. Although organoids shed some epithelial properties particularly at the invasive edge, TGFβ1-stimulated organoids largely maintained epithelial gene expression while additionally implementing a mesenchymal transcription pattern, resulting in a pEMT phenotype that did not progress to a fully mesenchymal state. Notably, while TGFβ1 induced pEMT and promoted collective invasion, it abrogated self-renewal capacity of TKA organoids which correlated with the downregulation of intestinal stem cell (ISC) marker genes. Mechanistically, induction of the non-progressive pEMT required canonical TGFβ signaling mediated by Smad transcription factors (TFs), whereas the EMT master regulators Snail1 and Zeb1 were dispensable. Gene expression profiling provided further evidence for pEMT of TGFβ1-treated organoids and showed that their transcriptomes resemble those of human poor prognosis CMS4 cancers which likewise exhibit pEMT features. We propose that collective invasion in colorectal carcinogenesis is triggered by microenvironmental stimuli through activation of a novel, transcription-mediated form of non-progressive pEMT independently of classical EMT regulators.

GSDMB is increased in IBD and regulates epithelial restitution/repair independent of pyroptosis

Gasdermins are a family of structurally related proteins originally described for their role in pyroptosis. Gasdermin B (GSDMB) is currently the least studied, and while its association with genetic susceptibility to chronic mucosal inflammatory disorders is well established, little is known about its functional relevance during active disease states. Herein, we report increased GSDMB in inflammatory bowel disease, with single-cell analysis identifying epithelial specificity to inflamed colonocytes/crypt top colonocytes. Surprisingly, mechanistic experiments and transcriptome profiling reveal lack of inherent GSDMB-dependent pyroptosis in activated epithelial cells and organoids but instead point to increased proliferation and migration during in vitro wound closure, which arrests in GSDMB-deficient cells that display hyper-adhesiveness and enhanced formation of vinculin-based focal adhesions dependent on PDGF-A-mediated FAK phosphorylation. Importantly, carriage of disease-associated GSDMB SNPs confers functional defects, disrupting epithelial restitution/repair, which, altogether, establishes GSDMB as a critical factor for restoration of epithelial barrier function and the resolution of inflammation.

Complete Model of Vinculin Suggests the Mechanism of Activation by Helical Super-Bundle Unfurling

To shed light onto the activation mechanism of vinculin, we carried out a detailed refinement of chicken vinculin and compared it to the human protein which is greater than 95% identical. Refinement resulted in a complete and significantly improved model. This model includes important elements such as a pro-rich strap region (PRR) and C-terminus. The conformation of the PRR stabilized by its inter- and intra-molecular contacts shows a dynamic, but relatively stable motif that constitutes a docking platform for multiple molecules. The contact of the C-terminus with the PRR suggests that phosphorylation of Tyr1065 might control activation and membrane binding. Improved electron densities showed the presence of large solvent molecules such as phosphates/sulfates and a head-group of PIP2. The improved model allowed for a computational stability analysis to be performed by the program Corex/Best which located numerous hot-spots of increased and decreased stability. Proximity of the identified binding sites for regulatory partners involved in inducing or suppressing the activation of vinculin to the unstable elements sheds new light onto the activation pathway and differential activation. This stability analysis suggests that the activation pathway proceeds by unfurling of the super-bundle built from four bundles of helices without separation of the Vt region (840-1066) from the head. According to our mechanism, when activating proteins bind at the strap region a separation of N and C terminal bundles occurs, followed by unfurling of the super-bundle and flattening of the general shape of the molecule, which exposes the interaction sites for binding of auxiliary proteins.

Integrating Soft Hydrogel with Nanostructures Reinforces Stem Cell Adhesion and Differentiation

Biophysical cues can regulate stem cell behaviours and have been considered as critical parameters of synthetic biomaterials for tissue engineering. In particular, hydrogels have been utilized as promising biomimetic and biocompatible materials to emulate the microenvironment. Therefore, well-defined mechanical properties of a hydrogel are important to direct desirable phenotypes of cells. Yet, limited research pays attention to engineering soft hydrogel with improved cell adhesive property, which is crucial for stem cell differentiation. Herein, we introduce silica nanoparticles (SiO2 NPs) onto the surface of methacrylated hyaluronic (MeHA) hydrogel to manipulate the presentation of cell adhesive ligands (RGD) clusters, while remaining similar bulk mechanical properties (2.79 ± 0.31 kPa) to that of MeHA hydrogel (3.08 ± 0.68 kPa). RGD peptides are either randomly decorated in the MeHA hydrogel network or on the immobilized SiO2 NPs (forming MeHA–SiO2). Our results showed that human mesenchymal stem cells exhibited a ~1.3-fold increase in the percentage of initial cell attachment, a ~2-fold increase in cell spreading area, and enhanced expressions of early-stage osteogenic markers (RUNX2 and alkaline phosphatase) for cells undergoing osteogenic differentiation with the osteogenic medium on MeHA–SiO2 hydrogel, compared to those cultured on MeHA hydrogel. Importantly, the cells cultivated on MeHA–SiO2 expressed a ~5-fold increase in nuclear localization ratio of the yes-associated protein, which is known to be mechanosensory in stem cells, compared to the cells cultured on MeHA hydrogel, thereby promoting osteogenic differentiation of stem cells. These findings demonstrate the potential use of nanomaterials into a soft polymeric matrix for enhanced cell adhesion and provide valuable guidance for the rational design of biomaterials for implantation.

Microarray analysis of lncRNA and mRNA expression profiles in patients with Legg-Calve-Perthes disease

BACKGROUND

The etiology and underlying pathogenic mechanisms of Legg-Calve-Perthes disease (LCPD) still remain unclear. A disruption of blood supply to the femoral head, producing ischemic necrosis, appears to be the critical pathological event. The lncRNAs play crucial roles in many biological processes and are dysregulated in various human diseases. However, its expression profiles and the potential regulatory roles in the development of LCPD have not been investigated.

METHODS

In this study, differentially expressed lncRNA and mRNA of Legg-Calve-Perthes disease patients were profiled. Several GO terms and pathways that play important roles in the regulation of vascular structure, function or coagulation were selected for further analysis. The lncRNA -mRNA interacting networks in LCPD tissues were constructed to identify novel potential targets for further investigation.

RESULTS

The microarray analysis revealed that 149 lncRNAs and 37 mRNAs were up-regulated, and 64 lncRNAs and 250 mRNAs were down-regulated in LCPD tissues. After filtering, we finally found 14 mRNAs and constructed an mRNA-lncRNA interacting network. Through the analysis of the interaction network, we finally found 13 differentially expressed lncRNAs, which may be implicated in the pathogenesis of LCPD. These mRNAs/lncRNAs were further validated with qRT-PCR.

CONCLUSION

The findings of this study established a co-expression network of disease-related lncRNAs and mRNAs which screened out from the concerned G.O. terms and Pathways, which may provide new sights for future studies on molecular mechanisms of LCPD.

Hyperosmotic stress induces epithelial-mesenchymal transition through rearrangements of focal adhesions in tubular epithelial cells

Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is a hallmark of renal tubulointerstitial fibrosis and is associated with chronic renal injury as well as acute renal injury. As one of the incidences and risk factors for acute renal injury, increasing the osmolality in the proximal tubular fluid by administration of intravenous mannitol has been reported, but the detailed mechanisms remain unclear. Hyperosmotic conditions caused by mannitol in the tubular tissue may generate not only osmotic but also mechanical stresses, which are known to be able to induce EMT in epithelial cells, thereby contributing to renal injury. Herein, we investigate the effect of hyperosmolarity on EMT in tubular epithelial cells. Normal rat kidney (NRK)-52E cells were exposed to mannitol-induced hyperosmotic stress. Consequently, the hyperosmotic stress led to a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker, α-smooth muscle actin (α-SMA), which indicates an initiation of EMT in NKR-52E cells. The hyperosmotic condition also induced time-dependent disassembly and rearrangements of focal adhesions (FAs) concomitant with changes in actin cytoskeleton. Moreover, prevention of FAs rearrangements by cotreatment with Y-27632, a Rho-associated protein kinase inhibitor, could abolish the effects of hyperosmotic mannitol treatment, thus attenuating the expression of α-SMA to the level in nontreated cells. These results suggest that hyperosmotic stress may induce EMT through FAs rearrangement in proximal tubular epithelial cells.

Cervical cancer-derived exosomal miR-663b promotes angiogenesis by inhibiting vinculin expression in vascular endothelial cells

BACKGROUND

Angiogenesis provides essential nutrients and oxygen for tumor growth and has become the main mechanism of tumor invasion and metastasis. Exosomes are nanoscale membrane vesicles containing proteins, lipids, mRNA and microRNA (miRNA), which mediate intercellular communication and play an important role in tumor progression. Accumulated evidence indicates that tumor-derived exosomal miRNAs participate in the tumor microenvironment and promote angiogenesis.

METHODS

Bioinformatic target prediction and dual luciferase reporter assays were performed to identify the binding site between miR-663b and the 3'-UTR of vinculin (VCL). VCL overexpression lentivirus and miR-663b overexpression/inhibition lentivirus were used to create a VCL overexpression model and miR-663b overexpression/inhibition model in-vitro. Immunohistochemistry (IHC) assays and western blot assays were used to detect protein expression. Exosome-cell cocultures, wound healing assays, tube formation assays and transwell assays were used to measure the migration and tube formation ability of vascular endothelial cells [human umbilical vein endothelial cells (HUVECs)]. siRNA targeted VCL was used to knockdown VCL.

RESULTS

In the present study, we found that miR-663b was elevated in cervical cancer tissue and exosomes. miR-663b could bind the 3'-UTR of VCL and inhibit its expression. VCL is downregulated in cervical cancer, and decreased VCL has a negative correlation with a high level of miR-663b. Further studies demonstrated that exosomes secreted by cervical cancer cells can deliver miR-663b to HUVECs and inhibit the expression of VCL, thereby promoting angiogenesis and tumor growth.

CONCLUSIONS

miR-663b derived from cancer cell exosomes acts as a driving factor for angiogenesis and a potential target of antiangiogenic therapy in cervical cancer. Our findings illustrated a new signaling pathway, including exosomes, miRNAs and target genes, which provides potential targets for antiangiogenic therapy.

A functional PVA aerogel-based membrane obtaining sutureability through modified electrospinning technology and achieving promising anti-adhesion effect after cardiac surgery

Pericardial barrier destruction, inflammatory cell infiltration, and fibrous tissue hyperplasia, trigger adhesions after cardiac surgery. There are few anti-adhesion materials that are both functional and sutureable for pericardial reconstruction. Besides, a few studies have reported on the mechanism of preventing pericardial adhesion. Herein, a functional barrier membrane with sutureability was developed via a modified electrospinning method. It was composed of poly(l-lactide-co-caprolactone) (PLCL) nanofibers, poly(vinyl alcohol) (PVA) aerogel, and melatonin, named PPMT. The PPMT had a special microstructure manifested as a staggered arrangement of nanofibers on the surface and a layered macroporous aerogel structure in a cross-section. Besides providing the porosity and hydrophilicity obtained from PVA, the structure also had suitable mechanical properties for stitching due to the addition of PLCL nanofibers. Furthermore, it inhibited the proliferation of fibroblasts by suppressing the activation of Fas and P53, and achieved anti-inflammatory effects by affecting the activity of inflammatory cells and reducing the release of pro-inflammatory factors, such as interleukin 8 (IL-8) and tumor necrosis factor α (TNF-α). Finally, in vivo transplantation showed that it up-regulated the expression of matrix metalloproteinase-1 (MMP1) and tissue inhibitor of metalloproteinase-1 (TIMP1), and down-regulated the expression of Vinculin and transforming growth factor β (TGF-β) in the myocardium, thereby reducing the formation of adhesions. Collectively, these results demonstrate a great potential of PPMT membrane for practical application to anti-adhesion.

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A functional PVA aerogel-based membrane (PPMT) obtained sutureability through modified electrospinning technology.

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The primary mechanism to anti-adhesion of PPMT membrane was explored.

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Promising anti-adhesion effect of PPMT membrane was accomplished in pericardium reconstruction in rabbit.

Use of Electrospun Phenylalanine/Poly-ε-Caprolactone Chiral Hybrid Scaffolds to Promote Endothelial Remodeling

The fabrication of tissue-engineered vascular grafts to replace damaged vessels is a promising therapy for cardiovascular diseases. Endothelial remodeling in the lumen of TEVGs is critical for successful revascularization. However, the construction of well-functioning TEVGs remains a fundamental challenge. Herein, chiral hybrid scaffolds were prepared by electrospinning using D/L-phenylalanine based gelators [D(L)PHEG] and poly-ε-caprolactone (PCL). The chirality of scaffolds significantly affected the endothelial remodeling progress of TEVGs. Compared with L-phenylalanine based gelators/poly-ε-caprolactone (L/PCL) and PCL, D-phenylalanine based gelators/poly-ε-caprolactone (D/PCL) scaffolds enhanced cell adhesion, and proliferation and upregulated the expression of fibronectin-1, and vinculin. These results suggests that chiral hybrid scaffolds can promote endothelial remodeling of TEVGs by upregulating adhesion-associated protein levels. This study offers an innovative strategy for endothelial remodeling of TEVGs by fabricating chiral hybrid scaffolds, and provides new insight for the treatment of cardiovascular diseases.

Effect of a Nanostructured Titanium Surface on Gingival Cell Adhesion, Viability and Properties against P. gingivalis

OBJECTIVES

The transgingival part of titanium implants is either machined or polished. Cell-surface interactions as a result of nano-modified surfaces could help gingival fibroblast adhesion and support antibacterial properties by means of the physico-mechanical aspects of the surfaces. The aim of the present study was to determine how a nanocavity titanium surface affects the viability and adhesion of human gingival fibroblasts (HGF-1). Additionally, its properties against Porphyromonas gingivalis were tested.

MATERIAL AND METHODS

Two different specimens were evaluated: commercially available machined titanium discs (MD) and nanostructured discs (ND). To obtain ND, machined titanium discs with a diameter of 15 mm were etched with a 1:1 mixture of 98% H₂SO₄ and 30% H₂O₂ (piranha etching) for 5 h at room temperature. Surface topography characterization was performed via scanning electron microscopy (SEM) and atomic force microscopy (AFM). Samples were exposed to HGF-1 to assess the effect on cell viability and adhesion, which were compared between the two groups by means of MTT assay, immunofluorescence and flow cytometry. After incubation with P. gingivalis, antibacterial properties of MD and ND were determined by conventional culturing, live/dead staining and SEM. Results: The present study successfully created a nanostructured surface on commercially available machined titanium discs. The etching process created cavities with a 10-20 nm edge-to-edge diameter. MD and ND show similar adhesion forces equal to about 10-30 nN. The achieved nanostructuration reduced the cell alignment along machining structures and did not negatively affect the proliferation of gingival fibroblasts when compared to MD. No differences in the expression levels of both actin and vinculin proteins, after incubation on MD or ND, were observed. However, the novel ND surface failed to show antibacterial effects against P. gingivalis.

CONCLUSION

Antibacterial effects against P. gingivalis cannot be achieved with nanocavities within a range of 10-20 nm and based on the piranha etching procedure. The proliferation of HGF-1 and the expression levels and localization of the structural proteins actin and vinculin were not influenced by the surface nanostructuration. Further studies on the strength of the gingival cell adhesion should be performed in the future.

CLINICAL RELEVANCE

Since osseointegration is well investigated, mucointegration is an important part of future research and developments. Little is known about how nanostructures on the machined transgingival part of an implant could possibly influence the surrounding tissue. Targeting titanium surfaces with improved antimicrobial properties requires extensive preclinical basic research to gain clinical relevance.

Anti-Malignant Effect of Tensile Loading to Adherens Junctions in Cutaneous Squamous Cell Carcinoma Cells

Actomyosin contractility regulates various cellular processes including proliferation and differentiation while dysregulation of actomyosin activity contributes to cancer development and progression. Previously, we have reported that actomyosin-generated tension at adherens junctions is required for cell density-dependent inhibition of proliferation of normal skin keratinocytes. However, it remains unclear how actomyosin contractility affects the hyperproliferation ability of cutaneous squamous cell carcinoma (cSCC) cells. In this study, we find that actomyosin activity is impaired in cSCC cells both in vitro and in vivo. External application of tensile loads to adherens junctions by sustained mechanical stretch attenuates the proliferation of cSCC cells, which depends on intact adherens junctions. Forced activation of actomyosin of cSCC cells also inhibits their proliferation in a cell-cell contact-dependent manner. Furthermore, the cell cycle arrest induced by tensile loading to adherens junctions is accompanied by epidermal differentiation in cSCC cells. Our results show that the degree of malignant properties of cSCC cells can be reduced by applying tensile loads to adherens junctions, which implies that the mechanical status of adherens junctions may serve as a novel therapeutic target for cSCC.

Paxillin Promotes Breast Tumor Collective Cell Invasion through Maintenance of Adherens Junction Integrity

Distant organ metastasis is linked to poor prognosis during cancer progression. The expression level of the focal adhesion adapter protein paxillin varies among different human cancers, but its role in tumor progression is unclear. Herein, we utilize a newly generated PyMT mammary tumor mouse model with conditional paxillin ablation in breast tumor epithelial cells, combined with in vitro 3D tumor organoids invasion analysis and 2D calcium switch assays, to assess the roles for paxillin in breast tumor cell invasion. Paxillin had little effect on primary tumor initiation and growth but is critical for the formation of distant lung metastasis. In paxillin-depleted 3D tumor organoids, collective cell invasion was substantially perturbed. Two-dimensional cell culture revealed paxillin-dependent stabilization of adherens junctions (AJ). Mechanistically, paxillin is required for AJ assembly through facilitating E-cadherin endocytosis and recycling and HDAC6-mediated microtubule acetylation. Furthermore, Rho GTPase activity analysis and rescue experiments with a RhoA activator or Rac1 inhibitor suggest paxillin is potentially regulating the E-cadherin-dependent junction integrity and contractility through control of the balance of RhoA and Rac1 activities. Together, these data highlight new roles for paxillin in the regulation of cell-cell adhesion and collective tumor cell migration to promote the formation of distance organ metastases. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].

Intrinsic Mechanical Cues and Their Impact on Stem Cells and Embryogenesis

Although understanding how soluble cues direct cellular processes revolutionised the study of cell biology in the second half of the 20th century, over the last two decades, new insights into how mechanical cues similarly impact cell fate decisions has gained momentum. During development, extrinsic cues such as fluid flow, shear stress and compressive forces are essential for normal embryogenesis to proceed. Indeed, both adult and embryonic stem cells can respond to applied forces, but they can also detect intrinsic mechanical cues from their surrounding environment, such as the stiffness of the extracellular matrix, which impacts differentiation and morphogenesis. Cells can detect changes in their mechanical environment using cell surface receptors such as integrins and focal adhesions. Moreover, dynamic rearrangements of the cytoskeleton have been identified as a key means by which forces are transmitted from the extracellular matrix to the cell and vice versa. Although we have some understanding of the downstream mechanisms whereby mechanical cues are translated into changes in cell behaviour, many of the signalling pathways remain to be defined. This review discusses the importance of intrinsic mechanical cues on adult cell fate decisions, the emerging roles of cell surface mechano-sensors and the cytoskeleton in enabling cells to sense its microenvironment, and the role of intracellular signalling in translating mechanical cues into transcriptional outputs. In addition, the contribution of mechanical cues to fundamental processes during embryogenesis such as apical constriction and convergent extension is discussed. The continued development of tools to measure the biomechanical properties of soft tissues in vivo is likely to uncover currently underestimated contributions of these cues to adult stem cell fate decisions and embryogenesis, and may inform on regenerative strategies for tissue repair.

Nonthermal Plasma Brush Treatment on Titanium and Zirconia To Improve Periabutment Epithelium Formation

The peri-implant soft tissue with inferior adhesion takes a long healing period to form, which is undesirable for the reaction around the peri-implant soft tissues. The aim of this study is to improve the physicochemical properties of titanium (Ti) and zirconia (ZrO₂) implant abutments and shorten the formation period of periabutment epithelium tissue. A nonthermal atmospheric plasma brush (NTAPB, N) was employed for Ti and ZrO₂ activation. The surface topographies, roughness, crystallinity, wettability, and chemical elements of the abutment materials were examined. The epithelial cell behavior analysis and tissue remodeling of the periabutment epithelial tissue were performed in vitro and in vivo. N-Ti and N-ZrO₂ had a similar good surface wettability, with a 65 and 70% increase in oxygen content and a 70 and 75% decrease in carbon content, respectively. Both N-Ti and N-ZrO₂ showed excellent adhesion, spread, and proliferation of epithelial cells in vitro, with improved adhesion molecule expression levels compared to untreated samples. N-Ti and N-ZrO₂ abutments were placed in the implantation sites of rats. From week 2 to week 6 after implantation, N-Ti and N-ZrO₂ had similar periabutment epithelium tissue formation, and both had increased plectin-positive and laminin γ2-positive cell numbers compared to Ti and ZrO₂. The NTAPB shows promising abutment modification abilities. It promotes the expression levels of adhesion molecules and the epithelial cell performance, which later leads to a quicker formation and remodeling of the important periabutment epithelial tissue.

Mechanistic Insight in Surface Nanotopography Driven Cellular Migration

Cellular migration plays a vital role in many physiological processes. To elucidate the role of surface nanotopography on the downstream signaling pathways underlying cell migration, model surfaces having well-defined hill-like surface nanotopography and uniform surface chemistry were designed and implemented using plasma polymerization and covalent attachment of nanoparticles of predetermined size. A scratch wound assay, immunostaining, and gene expression of focal adhesion (FA) proteins were performed to determine the influence of surface nanotopography on cell migration. The results of this study demonstrate that the gap closure between cell monolayers is faster on surfaces having greater nanoscale topography. The phenomenon is predominantly driven by cell migration and was independent from cell proliferation. Qualitative and quantitative assessment of proteins involved in the signaling pathways underlying cell migration showed significant modulation by surface nanotopography. Specifically, focal adhesion sites decreased with the increase in surface nanotopography scale while the expression of FA proteins increased. This implies that nanotopography mediated modulation of cell migration is directly governed by the recruitment of receptor and adapter proteins responsible for cell-surface interaction. The results of this study indicate that biomaterial devices and constructs having rationally designed surface nanotopography and chemistry could be utilized to regulate wound healing and tissue regeneration.

Draxin inhibits chick trunk neural crest delamination and migration by increasing cell adhesion

The neural crest is a multipotent cell population that migrates extensively to play important roles during embryonic development. After acquiring motility, trunk neural crest cells delaminate from the spinal cord and migrate to various regions of the body. Several cellular adhesion molecules, such as vinculin, are involved in the regulation of neural crest delamination and migration. In the present study, we found that draxin could inhibit delamination and migration of neural crest cells from the chick spinal cord and abnormal aggregation of the migrating neural crest cells. In the presence of draxin, the resuspended neural crest regained its adhesive ability such that it was significantly increased. Overexpression of draxin caused increased vinculin expression in vivo. Our data indicate that draxin might control delamination and migration of chick trunk neural crest by increasing cell adhesion.

Striated muscle proteins are regulated both by mechanical deformation and by chemical post-translational modification

All cells sense force and build their cytoskeleton to optimize function. How is this achieved? Two major systems are involved. The first is that load deforms specific protein structures in a proportional and orientation-dependent manner. The second is post-translational modification of proteins as a consequence of signaling pathway activation. These two processes work together in a complex way so that local subcellular assembly as well as overall cell function are controlled. This review discusses many cell types but focuses on striated muscle. Detailed information is provided on how load deforms the structure of proteins in the focal adhesions and filaments, using α-actinin, vinculin, talin, focal adhesion kinase, LIM domain-containing proteins, filamin, myosin, titin, and telethonin as examples. Second messenger signals arising from external triggers are distributed throughout the cell causing post-translational or chemical modifications of protein structures, with the actin capping protein CapZ and troponin as examples. There are numerous unanswered questions of how mechanical and chemical signals are integrated by muscle proteins to regulate sarcomere structure and function yet to be studied. Therefore, more research is needed to see how external triggers are integrated with local tension generated within the cell. Nonetheless, maintenance of tension in the sarcomere is the essential and dominant mechanism, leading to the well-known phrase in exercise physiology: "use it or lose it."

Force-Dependent Interactions between Talin and Full-Length Vinculin

Talin and vinculin are part of a multicomponent system involved in mechanosensing in cell-matrix adhesions. Both exist in autoinhibited forms, and activation of vinculin requires binding to mechanically activated talin, yet how forces affect talin's interaction with vinculin has not been investigated. Here by quantifying the kinetics of force-dependent talin-vinculin interactions using single-molecule analysis, we show that mechanical exposure of a single vinculin binding site (VBS) in talin is sufficient to relieve the autoinhibition of vinculin, resulting in high-affinity binding. We provide evidence that the vinculin undergoes dynamic fluctuations between an autoinhibited closed conformation and an open conformation that is stabilized upon binding to the VBS. Furthermore, we discover an additional level of regulation in which the mechanically exposed VBS binds vinculin significantly more tightly than the isolated VBS alone. Molecular dynamics simulations reveal the basis of this new regulatory mechanism, identifying a sensitive force-dependent change in the conformation of an exposed VBS that modulates binding. Together, these results provide a comprehensive understanding of how the interplay between force and autoinhibition provides exquisite complexity within this major mechanosensing axis.

Osteoinductive and antimicrobial mechanisms of graphene-based materials for enhancing bone tissue engineering

Graphene-based materials (GMs) have great application prospects in bone tissue engineering due to their osteoinductive ability and antimicrobial activity. GMs induce osteogenic differentiation through several mechanisms and pathways in bone tissue engineering. First of all, the surface and high hardness of the porous folds of graphene or graphene oxide (GO) can generate mechanical stimulation to initiate a cascade of reactions that promote osteogenic differentiation without any chemical inducers. In addition, change of the extracellular matrix (ECM), regulation of macrophage polarization, the oncostatin M (OSM) signaling pathway, the MAPK signaling pathway, the BMP signaling pathway, the Wnt/β-catenin signaling pathway, and other pathways are involved in GMs' regulation of osteogenesis. In bone tissue engineering, GMs prevent the formation of microbial biofilms mainly through preventing microbial adhesion and killing them. The former is mainly achieved by reducing surface free energy (SFE) and increasing hydrophobicity. The latter mainly includes oxidative stress and photothermal/photodynamic effects. Graphene and its derivatives (GDs) are mainly combined with bioactive ceramic materials, metal materials and macromolecular polymers to play an antimicrobial effect in bone tissue engineering. Concentration, number of layers, and type of GDs often affect the antimicrobial activity of GMs. In this paper, we reviewed relevant osteoinductive and antimicrobial mechanisms of GMs and their applications in bone tissue engineering.

The Early Adhesion Effects of Human Gingival Fibroblasts on Bovine Serum Albumin Loaded Hydrogenated Titanium Nanotube Surface

The soft tissue sealing at the transmucal portion of implants is vital for the long-term stability of implants. Hydrogenated titanium nanotubes (H₂-TNTs) as implant surface treatments were proved to promote the adhesion of human gingival fibroblasts (HGFs) and have broad usage as drug delivery systems. Bovine serum albumin (BSA) as the most abundant albumin in body fluid was crucial for cell adhesion and was demonstrated as a normal loading protein. As the first protein arriving on the surface of the implant, albumin plays an important role in initial adhesion of soft tissue cells, it is also a common carrier, transferring and loading different endogenous and exogenous substances, ions, drugs, and other small molecules. The aim of the present work was to investigate whether BSA-loaded H₂-TNTs could promote the early adhesion of HGFs; H₂-TNTs were obtained by hydrogenated anodized titanium dioxide nanotubes (TNTs) in thermal treatment, and BSA was loaded in the nanotubes by vacuum drying; our results showed that the superhydrophilicity of H₂-TNTs is conducive to the loading of BSA. In both hydrogenated titanium nanotubes and non-hydrogenated titanium nanotubes, a high rate of release was observed over the first hour, followed by a period of slow and sustained release; however, BSA-loading inhibits the early adhesion of human gingival fibroblasts, and H₂-TNTs has the best promoting effect on cell adhesion. With the release of BSA after 4 h, the inhibitory effect of BSA on cell adhesion was weakened.

Evolution of mechanisms controlling epithelial morphogenesis across animals: new insights from dissociation-reaggregation experiments in the sponge Oscarella lobularis

BACKGROUND

The ancestral presence of epithelia in Metazoa is no longer debated. Porifera seem to be one of the best candidates to be the sister group to all other Metazoa. This makes them a key taxon to explore cell-adhesion evolution on animals. For this reason, several transcriptomic, genomic, histological, physiological and biochemical studies focused on sponge epithelia. Nevertheless, the complete and precise protein composition of cell-cell junctions and mechanisms that regulate epithelial morphogenetic processes still remain at the center of attention.

RESULTS

To get insights into the early evolution of epithelial morphogenesis, we focused on morphogenic characteristics of the homoscleromorph sponge Oscarella lobularis. Homoscleromorpha are a sponge class with a typical basement membrane and adhaerens-like junctions unknown in other sponge classes. We took advantage of the dynamic context provided by cell dissociation-reaggregation experiments to explore morphogenetic processes in epithelial cells in a non-bilaterian lineage by combining fluorescent and electron microscopy observations and RNA sequencing approaches at key time-points of the dissociation and reaggregation processes.

CONCLUSIONS

Our results show that part of the molecular toolkit involved in the loss and restoration of epithelial features such as cell-cell and cell-matrix adhesion is conserved between Homoscleromorpha and Bilateria, suggesting their common role in the last common ancestor of animals. In addition, sponge-specific genes are differently expressed during the dissociation and reaggregation processes, calling for future functional characterization of these genes.

Non-invasive Regulation of Cellular Morphology Using a Photoswitchable Mechanical DNA Polymer

The extracellular matrix (ECM) in which the cells reside provides a dynamic and reversible environment. Spatiotemporal cues are essential when cells are undergoing morphogenesis, repair and differentiation. Emulation of such an intricate system with reversible presentation of nanoscale cues can help us better understand cellular processes and can allow the precise manipulation of cell function in vitro. Herein, we formulated a photoswitchable DNA mechanical nanostructure containing azobenzene moieties and dynamically regulated the spatial distance between adhesion peptides using a photoswitchable DNA polymer with photoirradiation. We found that the DNA polymer reversibly forms two different structures, a relaxed linear and shrunken compact form, observed by AFM. Using the mechanical properties of this DNA polymer, UV and visible light irradiation induced a significant morphology change of the cells between a round shape and spindle shape, thus providing a tool to decipher the language of the ECM better.

Key Roles of RGD-Recognizing Integrins During Cardiac Development, on Cardiac Cells, and After Myocardial Infarction

Cardiac cells interact with the extracellular matrix (ECM) proteins through integrin mechanoreceptors that control many cellular events such as cell survival, apoptosis, differentiation, migration, and proliferation. Integrins play a crucial role in cardiac development as well as in cardiac fibrosis and hypertrophy. Integrins recognize oligopeptides present on ECM proteins and are involved in three main types of interaction, namely with collagen, laminin, and the oligopeptide RGD (Arg-Gly-Asp) present on vitronectin and fibronectin proteins. To date, the specific role of integrins recognizing the RGD has not been addressed. In this review, we examine their role during cardiac development, their role on cardiac cells, and their upregulation during pathological processes such as heart fibrosis and hypertrophy. We also examine their role in regenerative and angiogenic processes after myocardial infarction (MI) in the peri-infarct area. Specific targeting of these integrins may be a way of controlling some of these pathological events and thereby improving medical outcomes.

Effect of Washing Treatment on the Textural Properties and Bioactivity of Silica/Chitosan/TCP Xerogels for Bone Regeneration

Silica/biopolymer hydrogel-based materials constitute very attractive platforms for various emerging biomedical applications, particularly for bone repair. The incorporation of calcium phosphates in the hybrid network allows for designing implants with interesting biological properties. Here, we introduce a synthesis procedure for obtaining silica–chitosan (CS)–tricalcium phosphate (TCP) xerogels, with CS nominal content varying from 4 to 40 wt.% and 10 to 20 wt.% TCP. Samples were obtained using the sol-gel process assisted with ultrasound probe, and the influence of ethanol or water as washing solvents on surface area, micro- and mesopore volume, and average pore size were examined in order to optimize their textural properties. Three washing solutions with different soaking conditions were tested: 1 or 7 days in absolute ethanol and 30 days in distilled water, resulting in E1, E7, and W30 washing series, respectively. Soaked samples were eventually dried by evaporative drying at air ambient pressure, and the formation of interpenetrated hybrid structures was suggested by Fourier transformed infrared (FTIR) spectroscopy. In addition the impact that both washing solvent and TCP content have on the biodegradation, in vitro bioactivity and osteoconduction of xerogels were explored. It was found that calcium and phosphate-containing ethanol-washed xerogels presented in vitro release of calcium (2–12 mg/L) and silicon ions (~60–75 mg/L) after one week of soaking in phosphate-buffered saline (PBS), as revealed by inductive coupled plasma (ICP) spectroscopy analysis. However, only the release of silicon was detected for water-washed samples. Besides, all the samples exhibited in vitro bioactivity in simulated body fluid (SBF), as well as enhanced in vitro cell growth and also significant focal adhesion development and maturation.

Investigating the nature of active forces in tissues reveals how contractile cells can form extensile monolayers

Actomyosin machinery endows cells with contractility at a single-cell level. However, within a monolayer, cells can be contractile or extensile based on the direction of pushing or pulling forces exerted by their neighbours or on the substrate. It has been shown that a monolayer of fibroblasts behaves as a contractile system while epithelial or neural progentior monolayers behave as an extensile system. Through a combination of cell culture experiments and in silico modelling, we reveal the mechanism behind this switch in extensile to contractile as the weakening of intercellular contacts. This switch promotes the build-up of tension at the cell-substrate interface through an increase in actin stress fibres and traction forces. This is accompanied by mechanotransductive changes in vinculin and YAP activation. We further show that contractile and extensile differences in cell activity sort cells in mixtures, uncovering a generic mechanism for pattern formation during cell competition, and morphogenesis.

Vinculin-mediated axon growth requires interaction with actin but not talin in mouse neocortical neurons

The actin-binding protein vinculin is a major constituent of focal adhesion, but its role in neuronal development is poorly understood. We found that vinculin deletion in mouse neocortical neurons attenuated axon growth both in vitro and in vivo. Using functional mutants, we found that expression of a constitutively active vinculin significantly enhanced axon growth while the head-neck domain had an inhibitory effect. Interestingly, we found that vinculin-talin interaction was dispensable for axon growth and neuronal migration. Strikingly, expression of the tail domain delayed migration, increased branching, and stunted axon. Inhibition of the Arp2/3 complex or abolishing the tail domain interaction with actin completely reversed the branching phenotype caused by tail domain expression without affecting axon length. Super-resolution microscopy showed increased mobility of actin in tail domain expressing neurons. Our results provide novel insights into the role of vinculin and its functional domains in regulating neuronal migration and axon growth.

Positive Effects of Three-Dimensional Collagen-Based Matrices on the Behavior of Osteoprogenitors

Recent research has demonstrated that reinforced three-dimensional (3D) collagen matrices can provide a stable scaffold for restoring the lost volume of a deficient alveolar bone. In the present study, we aimed to comparatively investigate the migratory, adhesive, proliferative, and differentiation potential of mesenchymal stromal ST2 and pre-osteoblastic MC3T3-E1 cells in response to four 3D collagen-based matrices. Dried acellular dermal matrix (DADM), hydrated acellular dermal matrix (HADM), non-crosslinked collagen matrix (NCM), and crosslinked collagen matrix (CCM) did all enhance the motility of the osteoprogenitor cells. Compared to DADM and NCM, HADM and CCM triggered stronger migratory response. While cells grown on DADM and NCM demonstrated proliferative rates comparable to control cells grown in the absence of a biomaterial, cells grown on HADM and CCM proliferated significantly faster. The pro-proliferative effects of the two matrices were supported by upregulated expression of genes regulating cell division. Increased expression of genes encoding the adhesive molecules fibronectin, vinculin, CD44 antigen, and the intracellular adhesive molecule-1 was detected in cells grown on each of the scaffolds, suggesting excellent adhesive properties of the investigated biomaterials. In contrast to genes encoding the bone matrix proteins collagen type I (Col1a1) and osteopontin (Spp1) induced by all matrices, the expression of the osteogenic differentiation markers Runx2, Alpl, Dlx5, Ibsp, Bglap2, and Phex was significantly increased in cells grown on HADM and CCM only. Short/clinically relevant pre-coating of the 3D biomaterials with enamel matrix derivative (EMD) or recombinant bone morphogenetic protein-2 (rBMP-2) significantly boosted the osteogenic differentiation of both osteoprogenitor lines on all matrices, including DADM and NCM, indicating that EMD and BMP-2 retained their biological activity after being released from the matrices. Whereas EMD triggered the expression of all osteogenesis-related genes, rBMP-2 upregulated early, intermediate, and late osteogenic differentiation markers except for Col1a1 and Spp1. Altogether, our results support favorable influence of HADM and CCM on the recruitment, growth, and osteogenic differentiation of the osteoprogenitor cell types. Furthermore, our data strongly support the biofunctionalization of the collagen-based matrices with EMD or rBMP-2 as a potential treatment modality for bone defects in the clinical practice.

Alterations of Growth and Focal Adhesion Molecules in Human Breast Cancer Cells Exposed to the Random Positioning Machine

In this study, we evaluated changes in focal adhesions (FAs) in two types of breast cancer cell (BCC) lines (differentiated MCF-7 and the triple-negative MDA-MB-231 cell line) exposed to simulated microgravity (s-μg) created by a random positioning machine (RPM) for 24 h. After exposure, the BCC changed their growth behavior and exhibited two phenotypes in RPM samples: one portion of the cells grew as a normal two-dimensional monolayer [adherent (AD) BCC], while the other portion formed three-dimensional (3D) multicellular spheroids (MCS). After 1 h and 30 min (MDA-MB-231) and 1 h 40 min (MCF-7), the MCS adhered completely to the slide flask bottom. After 2 h, MDA-MB-231 MCS cells started to migrate, and after 6 h, a large number of the cells had left the MCS and continued to grow in a scattered pattern, whereas MCF-7 cells were growing as a confluent monolayer after 6 h and 24 h. We investigated the genes associated with the cytoskeleton, the extracellular matrix and FAs. ACTB, TUBB, FN1, FAK1, and PXN gene expression patterns were not significantly changed in MDA-MB-231 cells, but we observed a down-regulation of LAMA3, ITGB1 mRNAs in AD cells and of ITGB1, TLN1 and VCL mRNAs in MDA-MB-231 MCS. RPM-exposed MCF-7 cells revealed a down-regulation in the gene expression of FAK1, PXN, TLN1, VCL and CDH1 in AD cells and PXN, TLN and CDH1 in MCS. An interaction analysis of the examined genes involved in 3D growth and adhesion indicated a central role of fibronectin, vinculin, and E-cadherin. Live cell imaging of eGFP-vinculin in MCF-7 cells confirmed these findings. β-catenin-transfected MCF-7 cells revealed a nuclear expression in 1g and RPM-AD cells. The target genes BCL9, MYC and JUN of the Wnt/β-catenin signaling pathway were differentially expressed in RPM-exposed MCF-7 cells. These findings suggest that vinculin and β-catenin are key mediators of BCC to form MCS during 24 h of RPM-exposure.

Proteomic Analysis Reveals Commonly Secreted Proteins of Mesenchymal Stem Cells Derived from Bone Marrow, Adipose Tissue, and Synovial Membrane to Show Potential for Cartilage Regeneration in Knee Osteoarthritis

Paracrine factors secreted by mesenchymal stem cells (MSCs) reportedly modulate inflammation and reparative processes in damaged tissues and have been explored for knee osteoarthritis (OA) therapy. Although various studies have reported the effects of paracrine factors in knee OA, it is not yet clear which paracrine factors directly affect the regeneration of damaged cartilage and which are secreted under various knee OA conditions. In this study, we cultured MSCs derived from three types of tissues and treated each type with IL-1β and TNF-α or not to obtain conditioned medium. Each conditioned medium was used to analyse the paracrine factors related to cartilage regeneration using liquid chromatography-tandem mass spectrometry. Bone marrow-, adipose tissue-, and synovial membrane-MSCs (all-MSCs) exhibited expression of 93 proteins under normal conditions and 105 proteins under inflammatory conditions. It was confirmed that the types of secreted proteins differed depending on the environmental conditions, and the proteins were validated using ELISA. The results of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis using a list of proteins secreted by all-MSCs under each condition confirmed that the secreted proteins were closely related to cartilage repair under inflammatory conditions. Protein-protein interaction networks were confirmed to change depending on environmental differences and were found to enhance the secretion of paracrine factors related to cartilage regeneration under inflammatory conditions. In conclusion, our results demonstrated that compared with knee OA conditions, the differential expression proteins may contribute to the regeneration of damaged cartilage. In addition, the detailed information on commonly secreted proteins by all-MSCs provides a comprehensive basis for understanding the potential of paracrine factors to influence tissue repair and regeneration in knee OA.

HDAC6 inhibitor ACY1215 inhibits the activation of NLRP3 inflammasome in acute liver failure by regulating the ATM/F-actin signalling pathway

Acute liver failure (ALF) is a rare and critical medical condition. This study was designed to investigate the protective effects and underlying mechanism of ACY1215 in ALF mice. Our findings suggested that ACY1215 treatment ameliorates the pathological hepatic damage of ALF and decreases the serum levels of ALT and AST. Furthermore, ACY1215 pretreatment increased the level of ATM, γ‐H2AX, Chk2, p53, p21, F‐actin and vinculin in ALF. Moreover, ACY1215 inhibited the level of NLRP3, ASC, caspase‐1, IL‐1β and IL‐18 in ALF. The ATM inhibitor KU55933 could decrease the level of ATM, γ‐H2AX, Chk2, p53, p21, F‐actin and vinculin in ALF with ACY1215 pretreatment. The F‐actin inhibitor cytochalasin B decreased the level of F‐actin and vinculin in ALF with ACY1215 pretreatment. However, cytochalasin B had no effect on protein levels of ATM, Chk2, p53 and p21 in ALF with ACY1215 pretreatment. Cytochalasin B could dramatically increase the level of NLRP3, ASC, caspase‐1, IL‐1β and IL‐18 in ALF with ACY1215 pretreatment. These results indicated that ACY1215 exhibited hepatoprotective properties, which was associated with the inhibition of NLRP3 inflammasome, and this effect of ACY1215 was connected with upregulation of the ATM/F‐actin mediated signalling pathways.

Tissue mechanics in stem cell fate, development, and cancer

Cells in tissues experience a plethora of forces that regulate their fate and modulate development and homeostasis. Cells sense mechanical cues through localized mechanoreceptors or by influencing cytoskeletal or plasma membrane organization. Cells translate force and modulate their behavior through a process termed mechanotransduction. Cells tune their tension upon exposure to chronic force by engaging cellular machinery that modulates actin tension, which in turn stimulates matrix remodeling and stiffening and alters cell-cell adhesions until cells achieve a state of tensional homeostasis. Loss of tensional homeostasis can be induced through oncogene activity and/or tissue fibrosis, accompanies tumor progression, and is associated with increased cancer risk. The mechanical stresses that develop in tumors can also foster the mesenchymal-like transdifferentiation of cells to induce a stem-like phenotype that contributes to their aggression, metastatic dissemination, and treatment resistance. Thus, strategies that ameliorate tumor mechanics may comprise an effective strategy to prevent aggressive tumor behavior.

Layer-Number-Dependent Effects of Graphene Oxide on the Pluripotency of Mouse Embryonic Stem Cells Through the Regulation of the Interaction Between the Extracellular Matrix and Integrins

Introduction

Embryonic stem cells (ESCs) possess great application prospects in biological research and regenerative medicine, so it is important to obtain ESCs with excellent and stable cellular states during in vitro expansion. The feeder layer culture system with the addition of leukemia inhibitory factor (LIF) is currently applied in ESC cultures, but it has a series of disadvantages that could influence the culture efficiency and quality of the ESCs. With the development of nanotechnology, many studies have applied nanomaterials to optimize the stem cell culture system and regulate the fate of stem cells. In this study, we investigated the layer-number-dependent biofunction of graphene oxide (GO) on the pluripotency of ESCs from mice (mESCs).

Methods

Single-layer GO (SGO) and multi-layer GO (MGO) were characterized and their effects on the cytotoxicity and self-renewal of mESCs were detected in vitro. The differentiation potentials of mESCs were identified through the formation of embryoid bodies and teratomas. The regulatory mechanism of GO was verified by blocking the target receptors on the surface of mESCs using antibodies.

Results

Both SGO and MGO were biocompatible with mESCs, but only MGO effectively sustained their self-renewal and differentiation potential. In addition, GO influenced the cellular activities of mESCs by regulating the interactions between extracellular matrix proteins and integrins.

Conclusion

This work demonstrates the layer-number-dependent effects of GO on regulating the cell behavior of mESCs and reveals the extracellular regulatory mechanism of this process.

First body of evidence suggesting a role of a tankyrase-binding motif (TBM) of vinculin (VCL) in epithelial cells

BACKGROUND

Adherens junctions (AJ) are involved in cancer, infections and neurodegeneration. Still, their composition has not been completely disclosed. Poly(ADP-ribose) polymerases (PARPs) catalyze the synthesis of poly(ADP-ribose) (PAR) as a posttranslational modification. Four PARPs synthesize PAR, namely PARP-1/2 and Tankyrase-1/2 (TNKS). In the epithelial belt, AJ are accompanied by a PAR belt and a subcortical F-actin ring. F-actin depolymerization alters the AJ and PAR belts while PARP inhibitors prevent the assembly of the AJ belt and cortical actin. We wondered which PARP synthesizes the belt and which is the PARylation target protein. Vinculin (VCL) participates in the anchorage of F-actin to the AJ, regulating its functions, and colocalized with the PAR belt. TNKS has been formerly involved in the assembly of epithelial cell junctions.

HYPOTHESIS

TNKS poly(ADP-ribosylates) (PARylates) epithelial belt VCL, affecting its functions in AJ, including cell shape maintenance.

MATERIALS AND METHODS

Tankyrase-binding motif (TBM) sequences in hVCL gene were identified and VCL sequences from various vertebrates, Drosophila melanogaster and Caenorhabditis elegans were aligned and compared. Plasma membrane-associated PAR was tested by immunocytofluorescence (ICF) and subcellular fractionation in Vero cells while TNKS role in this structure and cell junction assembly was evaluated using specific inhibitors. The identity of the PARylated proteins was tested by affinity precipitation with PAR-binding reagent followed by western blots. Finally, MCF-7 human breast cancer epithelial cells were subjected to transfection with Tol2-plasmids, carrying a dicistronic expression sequence including Gallus gallus wt VCL (Tol-2-GgVCL), or the same VCL gene with a point mutation in TBM-II (Tol2-GgVCL/*TBM) under the control of a β-actin promoter, plus green fluorescent protein following an internal ribosome entry site (IRES-GFP) to allow the identification of transfected cells without modifying the transfected protein of interest.

RESULTS AND DISCUSSION

In this work, some of the hypothesis predictions have been tested. We have demonstrated that: (1) VCL TBMs were conserved in vertebrate evolution while absent in C. elegans; (2) TNKS inhibitors disrupted the PAR belt synthesis, while PAR and an endogenous TNKS pool were associated to the plasma membrane; (3) a VCL pool was covalently PARylated; (4) transfection of MCF-7 cells leading to overexpression of Gg-VCL/*TBM induced mesenchymal-like cell shape changes. This last point deserves further investigation, bypassing the limits of our transient transfection and overexpression system. In fact, a 5th testable prediction would be that a single point mutation in VCL TBM-II under endogenous expression control would induce an epithelial to mesenchymal transition (EMT). To check this, a CRISPR/Cas9 substitution approach followed by migration, invasion, gene expression and chemo-resistance assays should be performed.

ASAP1 regulates the uptake of Mycobacterium tuberculosis H37Ra in THP1-derived macrophages by remodeling actin cytoskeleton

Tuberculosis is initiated by the entry of Mycobacterium tuberculosis (Mtb) into macrophages in the lungs. A study of the cellular factors responsible for the entry of Mtb into host cells will potentially benefit the development of therapeutic treatments or preventive agents against Mtb infection. Using human THP1-derived macrophages as a model, we found that infection of Mtb H37Ra transiently reduced the level of ASAP1, an ADP ribosylation factor (Arf)-GTPase activating protein. Furthermore, knockdown of ASAP1 increased the efficiency of H37Ra entry into the cell and altered the status of actin remodeling as indicated by the enhanced aggregation of F-actin and the increased numbers of vinculin- and paxillin-rich puncta. Collectively, the results in this report identified ASAP1 as a regulator controlling the entry of Mtb H37Ra into macrophage by remodeling actin cytoskeleton.

Helicase-like transcription factor-deletion from the tumor microenvironment in a cell line-derived xenograft model of colorectal cancer reprogrammed the human transcriptome-S-nitroso-proteome to promote inflammation and redirect metastasis

Methylation of the HLTF gene in colorectal cancer (CRC) cells occurs more frequently in men than women. Progressive epigenetic silencing of HLTF in tumor cells is accompanied by negligible expression in the tumor microenvironment (TME). Cell line-derived xenografts (CDX) were established in control (Hltf+/+) and Hltf-deleted male Rag2-/-IL2rg-/- mice by direct orthotopic cell microinjection (OCMI) of HLTF+/+HCT116 Red-FLuc cells into the submucosa of the cecum. Combinatorial induction of IL6 and S100A8/A9 in the Hltf-deleted TME with ICAM-1 and IL8 in the primary tumor activated a positive feedback loop. The proinflammatory niche produced a major shift in CDX metastasis to peritoneal dissemination compared to controls. Inducible nitric oxide (iNOS) gene expression and transactivation of the iNOS-S100A8/A9 signaling complex in Hltf-deleted TME reprogrammed the human S-nitroso-proteome. POTEE, TRIM52 and UN45B were S-nitrosylated on the conserved I/L-X-C-X2-D/E motif indicative of iNOS-S100A8/A9-mediated S-nitrosylation. 2D-DIGE and protein identification by MALDI-TOF/TOF mass spectrometry authenticated S-nitrosylation of 53 individual cysteines in half-site motifs (I/L-X-C or C-X-X-D/E) in CDX tumors. POTEE in CDX tumors is both a general S-nitrosylation target and an iNOS-S100A8/A9 site-specific (Cys638) target in the Hltf-deleted TME. REL is an example of convergence of transcriptomic-S-nitroso-proteomic signaling. The gene is transcriptionally activated in CDX tumors with an Hltf-deleted TME, and REL-SNO (Cys143) was found in primary CDX tumors and all metastatic sites. Primary CDX tumors from Hltf-deleted TME shared 60% of their S-nitroso-proteome with all metastatic sites. Forty percent of SNO-proteins from primary CDX tumors were variably expressed at metastatic sites. Global S-nitrosylation of proteins in pathways related to cytoskeleton and motility was strongly implicated in the metastatic dissemination of CDX tumors. Hltf-deletion from the TME played a major role in the pathogenesis of inflammation and linked protein S-nitrosylation in primary CDX tumors with spatiotemporal continuity in metastatic progression when the tumor cells expressed HLTF.

Bottom-up reconstitution of focal adhesion complexes

Focal adhesions (FA) are large macromolecular assemblies relevant for various cellular and pathological events such as migration, polarization, and metastatic cancer formation. At FA sites at the migrating periphery of a cell, hundreds of players gather and form a network to respond to extra cellular stimuli transmitted by the integrin receptor, the most upstream component within a cell, initiating the FA signaling pathway. Numerous cellular experiments have been performed to understand the FA architecture and functions; however, their intricate network formation hampers unraveling the precise molecular actions of individual players. Here, in vitro bottom‐up reconstitution presents an advantageous approach for elucidating the FA machinery and the hierarchical crosstalk of involved cellular players.

A low-temperature-printed hierarchical porous sponge-like scaffold that promotes cell-material interaction and modulates paracrine activity of MSCs for vascularized bone regeneration

Mesenchymal stem cells (MSCs) secrete paracrine trophic factors that are beneficial for tissue regeneration. In this study, a sponge-like scaffold with hierarchical and interconnected pores was developed using low-temperature deposition modeling (LDM) printing. Its effects on the cellular behavior, especially on the paracrine secretion patterns of MSCs, were comprehensively investigated. We found that compared with the scaffolds printed via the fused deposition modeling (FDM) technique, the LDM-printed sponges enhanced the adhesion, retention, survival, and ingrowth of MSCs and promoted cell-material interactions. Moreover, the paracrine functions of the cultured MSCs on the LDM-printed sponges were improved, with significant secretion of upregulated immunomodulatory, angiogenic, and osteogenic factors. MSCs on the LDM-printed sponges exert beneficial paracrine effects on multiple regenerative processes, including macrophage polarization, tube formation, and osteogenesis, verifying the enhanced immunomodulatory, angiogenic, and osteogenic potential. Further protein function assays indicated that focal adhesion kinase (FAK), downstream AKT, and yes-associated-protein (YAP) signaling might participate in the required mechanotransductive pathways, through which the hierarchical porous structures stimulated the paracrine effects of MSCs. In a rat distal femoral defect model, the MSC-laden LDM-printed sponges significantly promoted vascularized bone regeneration. The results of the present study demonstrate that the hierarchical porous biomimetic sponges prepared via LDM printing have potential applications in tissue engineering based on their cell-material interaction promotion and MSC paracrine function modulation effects. Furthermore, our findings suggest that the optimization of biomaterial properties to direct the paracrine signaling of MSCs would enhance tissue regeneration.

Sodium butyrate modulates chicken macrophage proteins essential for Salmonella Enteritidis invasion

Salmonella Enteritidis is an intracellular foodborne pathogen that has developed multiple mechanisms to alter poultry intestinal physiology and infect the gut. Short chain fatty acid butyrate is derived from microbiota metabolic activities, and it maintains gut homeostasis. There is limited understanding on the interaction between S. Enteritidis infection, butyrate, and host intestinal response. To fill this knowledge gap, chicken macrophages (also known as HTC cells) were infected with S. Enteritidis, treated with sodium butyrate, and proteomic analysis was performed. A growth curve assay was conducted to determine sub-inhibitory concentration (SIC, concentration that do not affect bacterial growth compared to control) of sodium butyrate against S. Enteritidis. HTC cells were infected with S. Enteritidis in the presence and absence of SIC of sodium butyrate. The proteins were extracted and analyzed by tandem mass spectrometry. Our results showed that the SIC was 45 mM. Notably, S. Enteritidis-infected HTC cells upregulated macrophage proteins involved in ATP synthesis through oxidative phosphorylation such as ATP synthase subunit alpha (ATP5A1), ATP synthase subunit d, mitochondrial (ATP5PD) and cellular apoptosis such as Cytochrome-c (CYC). Furthermore, sodium butyrate influenced S. Enteritidis-infected HTC cells by reducing the expression of macrophage proteins mediating actin cytoskeletal rearrangements such as WD repeat-containing protein-1 (WDR1), Alpha actinin-1 (ACTN1), Vinculin (VCL) and Protein disulfide isomerase (P4HB) and intracellular S. Enteritidis growth and replication such as V-type proton ATPase catalytic subunit A (ATPV1A). Interestingly, sodium butyrate increased the expression of infected HTC cell protein involving in bacterial killing such as Vimentin (VIM). In conclusion, sodium butyrate modulates the expression of HTC cell proteins essential for S. Enteritidis invasion.

Quantitative comparative phosphoproteomic analysis of the effects of colostrum and milk feeding on liver tissue of neonatal calves

Posttranslational modifications, mostly phosphorylation, are critical for protein structure and function. However, the association between liver phosphoproteins in neonatal calves and colostrum intake is not well understood. In this study, we examined the liver phosphoproteome profile in neonatal calves after receiving colostrum or milk. Liver tissue samples were collected from control calves (CON, n = 3) 2 h after birth and from calves that received colostrum (CG, n = 3) or milk (MG, n = 3) 24 h after birth. Hepatic phosphoprotein expression profiles were analyzed using quantitative proteomics based on the liquid chromatography-tandem mass spectrometry method. In total, 1,587 phosphorylated sites were identified in 1,011 liver proteins. The most abundant phosphorylation site AA was serine (87.5%), followed by threonine (11.9%) and tyrosine (0.5%). Among the 1,011 phosphoproteins, 219, 453, and 26 displayed differential expression in the CG versus MG, CG versus CON, and MG versus CON comparisons, respectively. Differentially expressed phosphoproteins in the CG-MG comparison included 3-phosphoinositide-dependent protein kinase 1, glucose transporter member 4, protein kinase N2, and vinculin, which were mainly involved in the glycogen metabolic process, transport, growth and development, and cell adhesion process, according to Gene Ontology analysis. Pathway analysis indicated their enrichment in the insulin signaling pathway, spliceosome, and adherens junction. The CG-CON comparison identified differentially expressed phosphoproteins and their target genes that were largely involved in the cellular process, macromolecule metabolic process, developmental process, and transport. Pathway analysis indicated their association with endocytosis, mechanistic target of rapamycin, AMP-activated protein kinase, and insulin signaling pathways. These data demonstrate that changes in the phosphoproteins of liver tissues may play an important role in energy metabolism and immune response in the calves that received colostrum. These results provide novel insights into the crucial roles of protein phosphorylation during the early life of newborn calves.

Lumican Inhibits In Vivo Melanoma Metastasis by Altering Matrix-Effectors and Invadopodia Markers

It was reported that lumican inhibits the activity of metalloproteinase MMP-14 and melanoma cell migration in vitro and in vivo. Moreover, Snail triggers epithelial-to-mesenchymal transition and the metastatic potential of cancer cells. Therefore, the aim of this study was to examine the effect of lumican on Mock and Snail overexpressing melanoma B16F1 cells in vivo. Lung metastasis was analyzed after intravenous injections of Mock-B16F1 and Snail-B16F1 cells in Lum+/+ and Lum-/- mice. At day 14, mice were sacrificed, and lungs were collected. The number of lung metastatic nodules was significantly higher in mice injected with Snail-B16F1 cells as compared to mice injected with Mock-B16F1 cells confirming the pro-metastatic effect of Snail. This effect was stronger in Lum-/- mice as compared to Lum+/+, suggesting that endogenous lumican of wild-type mice significantly inhibits metastasis to lungs. Scanning electron and confocal microscopy investigations demonstrated that lumican inhibits the development of elongated cancer cell phenotypes which are known to develop invadopodia releasing MMPs. Moreover, lumican was shown to affect the expression of cyclin D1, cortactin, vinculin, hyaluronan synthase 2, heparanase, MMP-14 and the phosphorylation of FAK, AKT, p130 Cas and GSK3α/β. Altogether, these data demonstrated that lumican significantly inhibits lung metastasis in vivo, as well as cell invasion in vitro, suggesting that a lumican-based strategy targeting Snail-induced metastasis could be useful for melanoma treatment.