miRNA-ome plasma analysis unveils changes in blood-brain barrier integrity associated with acute liver failure in rats.

BACKGROUND: Hepatic encephalopathy (HE) symptoms associated with liver insufficiency are linked to the neurotoxic effects of ammonia and other toxic metabolites reaching the brain via the blood-brain barrier (BBB), further aggravated by the inflammatory response. Cumulative evidence documents that the non-coding single-stranded RNAs, micro RNAs (miRs) control the BBB functioning. However, miRs' involvement in BBB breakdown in HE is still underexplored. Here, we hypothesized that in rats with acute liver failure (ALF) or rats subjected to hyperammonemia, altered circulating miRs affect BBB composing proteins. METHODS: Transmission electron microscopy was employed to delineate structural alterations of the BBB in rats with ALF (thioacetamide (TAA) intraperitoneal (ip.) administration) or hyperammonemia (ammonium acetate (OA) ip. administration). The BBB permeability was determined with Evans blue dye and sodium fluorescein assay. Plasma MiRs were profiled by Next Generation Sequencing (NGS), followed by in silico analysis. Selected miRs, verified by qRT-PCR, were examined in cultured rat brain endothelial cells. Targeted protein alterations were elucidated with immunofluorescence, western blotting, and, after selected miR mimics transfection, through an in vitro resistance measurement. RESULTS: Changes in BBB structure and increased permeability were observed in the prefrontal cortex of TAA rats but not in the brains of OA rats. The NGS results revealed divergently changed miRNA-ome in the plasma of both rat models. The in silico analysis led to the selection of miR-122-5p and miR-183-5p with their target genes occludin and integrin ß1, respectively, as potential contributors to BBB alterations. Both proteins were reduced in isolated brain vessels and cortical homogenates in TAA rats. We documented in cultured primary brain endothelial cells that ammonia alone and, in combination with TNFα increases the relative expression of NGS-selected miRs with a less pronounced effect of TNFα when added alone. The in vitro study also confirmed miR-122-5p-dependent decrease in occludin and miR-183-5p-related reduction in integrin ß1 expression. CONCLUSION: This work identified, to our knowledge for the first time, potential functional links between alterations in miRs residing in brain endothelium and BBB dysfunction in ALF.

Umbilical Cord Blood-Derived M1 Macrophage Exosomes Loaded with Cisplatin Target Ovarian Cancer In Vivo and Reverse Cisplatin Resistance.

We investigated the therapeutic efficacy of umbilical cord blood (UCB)-derived M1 macrophage exosomes loaded with cisplatin (CIS) in ovarian cancer and platinum resistance. M1 macrophages were purified by using CD14 magnetic beads and characterized by flow cytometry. Our analyses included morphology, particle size, particle concentration, potential, drug loading capacity, counts of entry into cells, antitumor effect in vivo, and the ability to reverse drug resistance. A2780, SKOV3, and A2780/DDP, SKOV3/DDP ovarian cancer cells (CIS-sensitive and CIS-resistant cell lines, respectively) were treated with CIS or CIS-loaded M1 macrophage exosomes (M1exoCISs). The encapsulation efficiency of CIS loading into M1 macrophage exosomes was approximately 30%. In vitro, M1exoCIS treatment reduced the CIS IC50 values of both A2780, SKOV3, and A2780/DDP, SKOV3/DDP cells. We evaluated the effect of M1exoCIS on tumor growth using a mouse ovarian cancer subcutaneous transplantation tumor model inoculated with A2780/DDP cells. M1exoCIS was observed in the liver, spleen, and tumor sites 24 h posttreatment; the fluorescence intensity of M1exoCIS is higher than that of CIS. After 7 days, M1exoCIS significantly inhibited the growth of subcutaneously transplanted tumors compared with CIS alone and had a longer survival time. Moreover, the toxicity test shows that M1exoCIS has less hepatorenal toxicity than CIS. To investigate the mechanism of M1exoCIS targeting, homing, and reversing drug resistance, we performed RT-PCR, Western blotting, and Proteome Profiler Human Receptor Array analyses. We found that A2780 and A2780/DDP cells expressed the integrin ß1/CD29 receptor, while M1 exosomes expressed integrin ß1/CD29. In addition, M1exos carries long noncoding RNA H19, implicated in PTEN protein upregulation and miR-130a and Pgp gene downregulation, leading to the reversal of CIS drug resistance. Therefore, UCB-derived M1exoCIS target tumor sites of ovarian cancer in vivo and can be used to increase the CIS sensitivity and cytotoxicity.

Luteolin inhibits angiogenesis and enhances radiotherapy sensitivity of laryngeal cancer via downregulating Integrin ß1.

AIM: To demonstrate the role and mechanism of luteolin in radio-sensitization and angiogenesis of laryngeal cancer. METHODS: Firstly, we analyzed the cytotoxicity of Luteolin and radiation sensitive cytotoxicity through CCK8, and selected subsequent radiation doses and Luteolin concentrations. Next, we further analyzed the effects of Luteolin on radiation sensitivity and neovascularization of laryngeal cancer, and conducted CCK8, plate cloning, and angiogenesis experiments, respectively. At the same time, the effects of individual treatment and combination treatment on the expression of Integrin ß1 and VEGFA were analyzed through immunofluorescence analysis. We also analyzed the regulation of Integrin ß1 protein expression by Luteolin through Western blot. To investigate the mechanism of Integrin ß1, we transfected overexpressed and silenced Integrin ß1 vectors and analyzed the role of Integrin ß1 in Luteolin enhancing radiation sensitivity of laryngeal cancer by repeating the above experiments. We have also constructed an in vivo subcutaneous tumor transplantation model to further validate the cell experimental results. The expression of Integrin, KI67, VEGFA, and CD31 was analyzed through Western blot and immunohistochemistry experiments. RESULTS: Radiation inhibited cell proliferation and decreased Integrin ß1 expression, and increased the radiosensitivity through inhibiting cell proliferation, and inhibit angiogenesis during radiation. Overexpression of Integrin ß1 weakened radiotherapy sensitivity on the basis of cells treated with combined administration. Integrin ß1 is considered as the downstream molecule of luteolin, participating in radiosensitivity of luteolin to FaDu cells. Animal experiments also demonstrated that luteolin strengthened tumor suppression and anti-angiogenesis during radiation via Integrin ß1. CONCLUSION: In summary, our results manifested that radio-sensitivity effect of luteolin depended on downregulating Integrin ß1 in laryngocarcinoma.

Dynamic-stiffening collagen-coated substrate enhances osteogenic differentiation of mesenchymal stem cells through integrin α2ß1.

Matrix stiffness dynamically increases during the bone formation process. Enhancement of the osteogenic differentiation of mesenchymal stem cells (MSCs) by the dynamic stiffening of the substrate has been reported in previous research. However, the mechanism by which the dynamic stiffening of the matrix effects the osteogenic differentiation of MSCs remains quite unknown. A previously reported dynamic hydrogel system with dynamic matrix stiffening was used in this study to investigate the mechanical transduction mechanism of MSCs. The integrin α2ß1 and phosphorylation focal adhesion kinase levels were evaluated. The results indicated that dynamic stiffening of the matrix mediated the activation of integrin α2ß1, and further influenced the focal adhesion kinase (FAK) phosphorylation level of MSCs. In addition, integrin α2 is a probable integrin subunit that causes integrin ß1 activation during the matrix dynamic stiffening process. The integrin ß1 is the main integrin subunit regulating the osteogenic differentiation of MSCs induced by FAK phosphorylation. Overall, the results suggested that the dynamic stiffness facilitated the osteogenic differentiation process of the MSCs by regulating the integrin-α2ß1-mediated mechanical transduction pathway, which implied that integrin α2ß1 played a crucial role in the physical biological coupling in the dynamic matrix microenvironment.

Diallyl Trisulfide, a Major Bioactive Constituent of Garlic, Promotes Colonic Mucosal Healing in Ulcerative Colitis through Accelerating Focal Adhesion Assembly and Consequent Epithelial Cell Migration via the Rab21-Integrin ß1-Fak Pathway.

SCOPE: Colonic mucosal healing is the terminal goal for the treatment of ulcerative colitis (UC), but there is currently no specific drug available. This study investigates the beneficial effect of diallyl trisulfide (DATS) on the colonic mucosal healing. METHODS AND RESULTS: Dextran sulfate sodium (DSS) is used to induce colitis in female C57BL/6 mice, and DATS is orally administered during the recovery period. DATS hardly impacts the inflammation of the colonic tissues, but significantly promotes the mucosal repair. DATS promotes the migration but not proliferation of colonic epithelial cells in the colitis mice. In addition, DATS accelerates the wound healing, cell migration, focal adhesion assembly, and phosphorylation of focal adhesion kinase (FAK) of colonic epithelial cells in vitro, which are evidently reversed by combined use of FAK inhibitor PF-573228. Similar results are shown in colitis mice. Mechanically, DATS promotes the binding of Rab21 to integrin ß1 and accelerates the endocytosis of integrin ß1, which is significantly attenuated by the knockdown of Rab21. CONCLUSIONS: DATS promotes the binding of Rab21 to integrin ß1 and the endocytosis of integrin ß1, thereby increases FAK phosphorylation and focal adhesion assembly, finally accelerates the migration of colonic epithelial cells and mucosal healing.

In Situ Regulation and Mechanisms of 3D Matrix Stiffness on the Activation and Reversion of Hepatic Stellate Cells.

Activated hepatic stellate cells (HSCs) is a key event in the progression of liver fibrosis. HSCs transdifferentiate into myofibroblasts and secrete large amounts of extracellular matrix, resulting in increased liver stiffness. It is difficult for platforms constructed in vitro to simulate the structure, composition, and stiffness of the 3D microenvironment of HSCs in vivo. Here, 3D scaffolds with different stiffness are constructed by decellularizing rat livers at different stages of fibrosis. The effects of matrix stiffness on the proliferation, activation, and reversion of HSCs are studied. The results demonstrate these scaffolds have good cytocompatibility. It is also found that the high stiffness can significantly promote the activation of HSCs, and this process is accompanied by the activation of integrin ß1 as well as the nucleation and activation of Yes-associated protein (YAP). Moreover, the low stiffness of the scaffold can promote the reversion of activated HSCs, which is associated with cell apoptosis and accompanied by the inactivation of integrin ß1 and YAP. These results suggest that YAP may be a potential therapeutic target for the treatment of liver fibrosis and the theoretical feasibility of inducing activated HSCs reversion to the resting state by regulating matrix stiffness of liver.

Role of ß1-integrin in promoting cell motility and tamoxifen resistance of human breast cancer MCF-7 cells.

BACKGROUND: The mechanism of acquired resistance of tamoxifen in endocrine therapy of breast cancer is not fully understood. In this study, we investigated the genomic changes in acquired tamoxifen-resistant cell lines. METHODS: Tamoxifen-resistant subclones (MCF-7R) derived from parent MCF-7 cells, which is an ER(+) breast cancer cell line, cultured with 4-hydrotamoxifen more than 6 months were used to obtain genomic alterations. Cell growth, microarray, and quantitative real-time PCR (q-RTPCR) assays were conducted. Additionally, the ITGB1 function was investigated in MCF-7R cells and MCF-7R ITGB1-silenced subclones using MTT and Transwell assays. Online pathway analysis was performed to assess the genetic characteristics of tamoxifen resistance. RESULTS: The gene expression profile of the tamoxifen-resistant cell line was considerably changed compared to the tamoxifen-sensitive cell line. Of 4102 genes with altered expressions, 1986 genes were upregulated, whereas 2116 were downregulated. The ITGB1 expression in MCF-7R cells was higher than that in MCF-7 cells. Interestingly, ITGB1 silencing partially rescued the sensitivity of MCF-7R cells to tamoxifen and reduced their motility. The activation of the ß1-integrin signaling pathway was probably responsible for this phenomenon. CONCLUSIONS: Our data confirm the presence of alterations in the genes of tamoxifen-resistance breast cancer cells. ITGB1 probably partially contributes to tamoxifen resistance and cell motility via the ß1-integrin signaling pathway. Thus, ITGB1 may be a potential target for the improvement of anti-hormone therapy reaction in ER(+) breast cancer patients.

Alcohol promotes epithelial mesenchymal transformation-mediated premetastatic niche formation of colorectal cancer by activating interaction between laminin-γ2 and integrin-ß1.

BACKGROUND: Colorectal cancer (CRC) is a common malignant tumor. Alcohol consumption is positively correlated with CRC malignant metastasis; however, the mechanism is unclear. The interaction between laminin-γ2 (LAMC2) and integrin-ß1 (ITGB1) plays a role in premetastatic niche signaling, which may induce epithelial mesenchymal transformation (EMT) and lead to metastasis. AIM: To investigate the effects of alcohol on CRC metastasis from the molecular mechanism of the premetastatic niche. METHODS: The interaction between LAMC2 and ITGB1 was measured by Duolink assay, and the expression levels of LAMC2, ITGB1 and focal adhesion kinase (FAK), snail, fibronectin, N-cadherin and special AT-rich sequence binding protein 1 (SATB1) were measured by quantitative real-time polymerase chain reaction, immunohistochemistry and western blotting. Interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and IL-6 levels were measured via enzyme-linked immunosorbent assay, histopathological assessment via hematoxylin eosin staining, and determination of aberrant crypt foci via methylene blue. RESULTS: The lymph node metastasis rate was higher in the alcohol group than non-alcohol group. There was a significant increase in interaction signals between LAMC2 and ITGB1, and an increase in phosphorylate-FAK/FAK, snail, fibronectin, N-cadherin and SATB1, whereas E-cadherin was reduced in the alcohol group compared to the non-alcohol group in both animal and clinical samples. Serum IL-1ß, TNF-α and IL-6 were higher in alcohol group than in non-alcohol group. Alcohol may promote CRC metastasis by influencing the molecular mechanism of the premetastatic niche. CONCLUSION: Our study suggests that alcohol promotes EMT-mediated premetastatic niche formation of CRC by activating the early interaction between LAMC2 and ITGB1 and lead to CRC metastasis.

Effect of Amino Acid Substitution on Cell Adhesion Properties of Octa-arginine.

Octa-arginine (R8) is a cell-permeable peptide with excellent cell adhesion properties. Surface-immobilized R8 mediates cell attachment via cell surface receptors, such as heparan sulfate proteoglycans and integrin ß1, and promotes cell spreading and proliferation. However, it is not clear how these properties are affected by specific peptide composition and if they could be improved. Here, we synthesized XR8 peptides, in which half of the original R8 arginine residues were replaced with another amino acid (X). We then aimed to investigate the effect of the substitution on cell adhesion and proliferation on XR8-conjugated agarose matrices. The XR8-matrix showed slightly better cell attachment when X was a hydrophobic or aromatic amino acid. However, hydrophobic XR8-matrices tended to promote cell proliferation to a less extent. Eventually, YR8-matrix most efficiently promoted cell adhesion, spreading, and proliferation among the XR8-matrices tested. Collectively, these observations indicate that the properties of residue X play a major role in the biological activity of XR8-matrices and shed light on the interaction between small peptides and the cell membrane. Further, YR8 is a promising cell-adhesive peptide for the development of cell culture substrates and biomaterials.

Collagens I and V differently regulate the proliferation and adhesion of rat islet INS-1 cells through the integrin ß1/E-cadherin/ß-catenin pathway.

Extracellular matrix (ECM) plays an important role in tissue repair, cell proliferation, and differentiation. Our previous study showed that collagen I and collagen V differently regulate the proliferation of rat pancreatic ß cells (INS-1 cells) through opposite influences on the nuclear translocation of ß-catenin. In this study, we investigated the ß-catenin pathway in INS-1 cells on dishes coated with collagen I or V. We found that nuclear translocation of the transcription factor Yes-associated protein (YAP) was enhanced by collagen I and suppressed by collagen V, but had no effect on INS-1 cell proliferation. Morphologically, INS-1 cells on collagen V-coated dishes showed stronger cell-to-cell adhesion, while the cells on collagen I-coated dishes showed weaker cell-to-cell adhesion in comparison with the cells on non-coated dishes. E-cadherin played an inhibitory role in the proliferation of INS-1 cells cultured on collagen I or collagen V coated dishes via regulation of the nuclear translocation of ß-catenin. Integrin ß1 was enhanced with collagen I, while it was repressed with collagen V. The integrin ß1 pathway positively regulated the cell proliferation. Inhibition of integrin ß1 pathway restored the protein level of E-cadherin and inhibited the nuclear translocation of ß-catenin in the cells on collagen I-coated dishes, but no effect was observed in the cells on collagen V-coated dishes. In conclusion, collagen I enhances the proliferation of INS-1 cells via the integrin ß1 and E-cadherin/ß-catenin signaling pathway. In INS-1 cells on collagen V-coated dishes, both integrin ß1 and E-cadherin/ß-catenin signal pathways are involved in the inhibition of proliferation.

Tissue factor potentiates adherence of breast cancer cells to human umbilical vein endothelial cells under static and flow conditions.

Tissue factor (TF) has been extensively studied for tumor metastasis, but its role in mediating cancer cell adhesion to vasculature remains unknown. This study aimed to measure the ability of TF to mediate the adhesion of breast cancer cells to human umbilical vein endothelial cells (HUVECs). MDA-MB-231 cells expressed the highest TF level and adhered more to HUVECs under static and flow conditions, a neutralizing TF antibody abolished the enhanced adhesion of MDA-MB-231 cells to HUVECs. Recombinant human soluble TF (rTF) bonded ß1integrin on HUVECs surfaces, ß1 or α3integrin antibody combined with TF antibody abolished more cell-cell adhesion. These data suggested that TF mediated adhesion of breast cancer cells to endothelial cells may rely on ß1integrin on HUVECs surfaces.

Integrin ß1 in Adipose-Derived Stem Cells Accelerates Wound Healing via Activating PI3K/AKT Pathway.

BACKGROUND: This study aims to investigate the effect of integrin ß1 on wound healing induced by adipose-derived stem cells (ADSCs), as well as the corresponding mechanism. METHODS: Integrin ß1 was overexpressed in ADSCs. Thereafter, flow cytometry and transwell chambers technology were used to measure the endothelial-like differentiation (CD31 as a biomarker of endothelial cell) and cell migration, respectively. Western blot was used to detect the activation of PI3K/AKT, NF-κB and ERK signaling pathways. The effects of integrin ß1 overexpression on healing time, healing rate and fibroblast number were further evaluated in the rat models of chronic refractory wound. RESULTS: The overexpression of integrin ß1 increased CD31+ endothelial-like cells (about 3.6-fold), promoted cell migration (about 1.9-fold) and enhanced the activation of PI3K (p-PI3K; about 2.1-fold) and AKT (p-AKT; about 2.2-fold). These effects were all weakened when PI3K/AKT pathway was inhibited by LY294002 treatment. In addition, the experiments in rat wound models showed that integrin ß1 overexpression obviously shortened healing time (approximately 0.41-fold), increased healing rate (about 2.7-fold, 2.8-fold and 1.6-fold at day 7, 14 and 21) and increased the number of fibroblasts (approximately 3.1-fold at day 21). All of the above differences were statistically significant (p < 0.05). CONCLUSION: Integrin ß1 can promote the migration and endothelial-like differentiation of ADSCs by activating PI3K/AKT pathway and then enhance the function of ADSCs in promoting wound healing.

Effect of integrin ß1 in the treatment of stress urinary incontinence by electrical stimulation.

The aim of the present study was to investigate the protective effect of integrin ß1 in the treatment of stress urinary incontinence (SUI) by electrical stimulation, and the underlying mechanisms by which electrical stimulation regulates the collagen metabolism of female vaginal wall fibroblasts (FVWFs). FVWFs obtained from the vaginal wall tissue of patients with (Ingelman­Sundberg scale; grade II, n=8; grade III, n=10) or without (n=8) SUI during gynecological operations were isolated by enzymatic digestion and subsequently identified by immunocytochemistry. Following this, cultured FVWFs were treated with an inhibitor of integrin ß1, recombinant human integrin ß1 and electrical stimulation (100 mv/mm, 2 h, 20 Hz), followed by total mRNA and protein extraction. mRNA and protein expression levels of integrin ß1, transforming growth factor (TGF)­ß1 and collagen (COL) I and III in FVWFs were quantified by reverse transcription­quantitative PCR (RT­qPCR) and western blot analysis respectively. Integrin ß1, TGF­ß1 and COL I and III expression levels were decreased in patients with SUI compared with healthy controls, and the grade III group had lower levels than the grade II group. Following electrical stimulation treatment, the expression levels of TGF­ß1, COL I and III were enhanced in the grade II group, but not in the grade III group. Nevertheless, the inhibitor of integrin ß1 reduced the protective effect of electrical stimulation in the grade II group. In addition, electrical stimulation combined with recombinant human integrin ß1 could also protect cells from SUI in the grade III group. The present study provides evidence for the increased degradation of the extracellular matrix and integrin ß1 in the vaginal wall tissues of patients with SUI, and the protective effect of electrical stimulation against SUI via integrin ß1. These results provide a novel mechanism for the treatment of SUI using electrical stimulation.

Human plasma fibronectin promotes proliferation and differentiation of odontoblast.

OBJECTIVE: To assess the effect of fibronectin (Fn) and porcine type I collagen (PCOL) on odontoblast-like cells in vitro. MATERIAL AND METHODS: Rat odontoblast-like cells (MDPC-23 cells) were inoculated and cultured on Fn-coated or type I collagen-coated substrates. Proliferation assay, alkaline phosphatase activity (ALP activity), mRNA expression of hard tissue-forming markers, and Alizarin red staining were investigated over a period of 10 days. RESULTS: Cells maintained a high proliferation activity on Fn and PCOL even at a low seeding concentration (0.5×104/mL) as demonstrated by CCK-8 assay. The proliferation activity of cells on Fn increases in a concentration-dependent manner while it reached a plateau after 10 µg/mL. Cells adopted long, thin and spindle shape on Fn(10-50) and PCOL. Parallel actin filaments were observed in MDPC-23 cells cultured on Fn and PCOL. ALP activity was markedly up-regulated on Fn and PCOL-coated surfaces. Importantly, gene expression of BSP (Fn10: 2.44±0.32; Fn20: 3.05±0.01; Fn30: 2.90±0.21; Fn40: 2.74±0.30; Fn50: 2.64±0.12; PCOL: 2.20±0.03) and OCN (Fn10: 2.52±0.23; Fn20: 2.28±0.24; Fn30: 2.34±0.21; Fn40: 2.34±0.25; Fn50: 2.20±0.22; PCOL: 1.56±0.16) was significantly enhanced on Fn and PCOL substrates as compared with control; moreover, expression of integrin beta 1 (ITGB1), an ubiquitous cell surface receptor was augmented in Fn(10-50) and PCOL groups simultaneously. In accordance with the ALP activity and gene expression data, calcific deposition in cells grown on Fn(10-50) and PCOL was observed as well. CONCLUSION: Despite the limitation of this study, the findings indicate that a surface coating of Fn enhances the proliferation, differentiation and mineralization of odontoblast-like cells by activation of integrin beta 1 (ITG B1). The promoting effects of Fn on MDPC-23 cells were achieved at a comparatively lower coating concentration than type I collagen (300 µg/mL). Specifically, it is suggested that the optimum coating concentration of Fn to be 10 µg/mL.

Human plasma fibronectin promotes proliferation and differentiation of odontoblast

Abstract Objective To assess the effect of fibronectin (Fn) and porcine type I collagen (PCOL) on odontoblast-like cells in vitro. Material and Methods Rat odontoblast-like cells (MDPC-23 cells) were inoculated and cultured on Fn-coated or type I collagen-coated substrates. Proliferation assay, alkaline phosphatase activity (ALP activity), mRNA expression of hard tissue-forming markers, and Alizarin red staining were investigated over a period of 10 days. Results Cells maintained a high proliferation activity on Fn and PCOL even at a low seeding concentration (0.5×104/mL) as demonstrated by CCK-8 assay. The proliferation activity of cells on Fn increases in a concentration-dependent manner while it reached a plateau after 10 µg/mL. Cells adopted long, thin and spindle shape on Fn(10-50) and PCOL. Parallel actin filaments were observed in MDPC-23 cells cultured on Fn and PCOL. ALP activity was markedly up-regulated on Fn and PCOL-coated surfaces. Importantly, gene expression of BSP (Fn10: 2.44±0.32; Fn20: 3.05±0.01; Fn30: 2.90±0.21; Fn40: 2.74±0.30; Fn50: 2.64±0.12; PCOL: 2.20±0.03) and OCN (Fn10: 2.52±0.23; Fn20: 2.28±0.24; Fn30: 2.34±0.21; Fn40: 2.34±0.25; Fn50: 2.20±0.22; PCOL: 1.56±0.16) was significantly enhanced on Fn and PCOL substrates as compared with control; moreover, expression of integrin beta 1 (ITGB1), an ubiquitous cell surface receptor was augmented in Fn(10-50) and PCOL groups simultaneously. In accordance with the ALP activity and gene expression data, calcific deposition in cells grown on Fn(10-50) and PCOL was observed as well. Conclusion Despite the limitation of this study, the findings indicate that a surface coating of Fn enhances the proliferation, differentiation and mineralization of odontoblast-like cells by activation of integrin beta 1 (ITG B1). The promoting effects of Fn on MDPC-23 cells were achieved at a comparatively lower coating concentration than type I collagen (300 µg/mL). Specifically, it is suggested that the optimum coating concentration of Fn to be 10 µg/mL.

ß1-Integrin alters ependymal stem cell BMP receptor localization and attenuates astrogliosis after spinal cord injury.

Astrogliosis after spinal cord injury (SCI) is a major impediment to functional recovery. More than half of new astrocytes generated after SCI are derived from ependymal zone stem cells (EZCs). We demonstrate that expression of ß1-integrin increases in EZCs following SCI in mice. Conditional knock-out of ß1-integrin increases GFAP expression and astrocytic differentiation by cultured EZCs without altering oligodendroglial or neuronal differentiation. Ablation of ß1-integrin from EZCs in vivo reduced the number of EZC progeny that continued to express stem cell markers after SCI, increased the proportion of EZC progeny that differentiated into GFAP+ astrocytes, and diminished functional recovery. Loss of ß1-integrin increased SMAD1/5/8 and p38 signaling, suggesting activation of BMP signaling. Coimmunoprecipitation studies demonstrated that ß1-integrin directly interacts with the bone morphogenetic protein receptor subunits BMPR1a and BMPR1b. Ablation of ß1-integrin reduced overall levels of BMP receptors but significantly increased partitioning of BMPR1b into lipid rafts with increased SMAD1/5/8 and p38 signaling. Thus ß1-integrin expression by EZCs reduces movement of BMPR1b into lipid rafts, thereby limiting the known deleterious effects of BMPR1b signaling on glial scar formation after SCI.

Matrix metalloproteinase 2 and membrane type 1 matrix metalloproteinase co-regulate axonal outgrowth of mouse retinal ganglion cells.

Restoration of correct neural activity following central nervous system (CNS) damage requires the replacement of degenerated axons with newly outgrowing, functional axons. Unfortunately, spontaneous regeneration is largely lacking in the adult mammalian CNS. In order to establish successful regenerative therapies, an improved understanding of axonal outgrowth and the various molecules influencing it, is highly needed. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Using an ex vivo retinal explant model, we were able to show that broad-spectrum MMP inhibition reduces axon outgrowth of mouse retinal ganglion cells (RGCs), implicating MMPs as beneficial factors in axonal regeneration. Additional studies, using more specific MMP inhibitors and MMP-deficient mice, disclosed that both MMP-2 and MT1-MMP, but not MMP-9, are involved in this process. Furthermore, administration of a novel antibody to MT1-MMP that selectively blocks pro-MMP-2 activation revealed a functional co-involvement of these proteinases in determining RGC axon outgrowth. Subsequent immunostainings showed expression of both MMP-2 and MT1-MMP in RGC axons and glial cells. Finally, results from combined inhibition of MMP-2 and ß1-integrin were suggestive for a functional interaction between these molecules. Overall, our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules. Axonal regeneration in the central nervous system is lacking in adult mammals, thereby impeding recovery from injury to the nervous system. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Inhibition of specific MMPs reduced neurite outgrowth from mouse retinal explants. Our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules and show a possible link between MMP-2 and ß1-integrin in axon outgrowth.

Cross-talk between integrin receptor and insulin-like growth factor receptor in regulation of collagen biosynthesis in cultured fibroblasts.

PURPOSE: Cellular processes are regulated by signals generated by adhesion receptors and growth factor receptors. IGFbinding protein 1 (IGFBP-1) is a molecule which may affect the both signaling pathways through inactivation of IGF-I (ligand for IGF-IR) and binding to RGD region of integrin receptors. Whether this phenomenon is important in communication between insulin-like growth factor receptor (IGF-IR) and ß1-integrin receptor in regulation of prolidase activity and collagen biosynthesis is the aim of this study. MATERIAL AND METHOD: We studied the effects of IGFBP-1, IGF-I, thrombin (integrin activator), echistatin (disintegrin), phosphatidylinositol 3-kinase inhibitor (LY-294002) and ERK 1/2 inhibitors (PD98059 and UO126) on prolidase activity, collagen biosynthesis and expression of proteins participating in pathways generated by these receptors. RESULTS: Stimulation of ß1-integrin and IGF-I receptors by standard ligands was proved to up-regulate collagen synthesis in cultured fibroblasts. IGFBP-1, similarly as echistatin and studied inhibitors, contributed to down-regulation of ERK1/2, Akt, mTOR expression and up-regulation of NFκB. It was accompanied by parallel decrease in prolidase activity and collagen biosynthesis. CONCLUSION: The data suggest that "cross talk" between IGF-I receptor and integrin receptor may play important role in regulation of prolidase activity and collagen biosynthesis.

Differential effects of extracellular matrix and mechanical strain on airway smooth muscle cells from ovalbumin- vs. saline-challenged Brown Norway rats.

The asthmatic airway is characterized by alterations in decorin and biglycan and increased airway smooth muscle (ASM). Further, the asthmatic airway may be subjected to abnormal mechanical strain. We hypothesized that ASM cells obtained from ovalbumin (OVA)--and saline (SAL)--challenged rats would respond differently to matrix and mechanical strain. ASMC were seeded on plastic, decorin or biglycan. Additional cells were grown on decorin, biglycan or collagen type 1, and then subjected to mechanical strain (Flexercell). The number of OVA ASMC was significantly greater than SAL ASM when seeded on plastic. A significant decrease was observed for both OVA and SAL ASMC seeded on decorin compared to plastic; the reduction in ASMC number was more modest for OVA. Biglycan decreased SAL ASMC number only. Strain reduced cell number for SAL and OVA ASMC grown on all matrices. Strain affected expression of ß1-integrin differently in OVA vs. SAL ASMC. These data suggest that matrix and mechanical strain modulate ASMC number; these effects are differentially observed in OVA ASMC.

A crosstalk between ß1 and ß3 integrins controls glycine receptor and gephyrin trafficking at synapses.

The regulation of glycine receptor (GlyR) number at synapses is necessary for the efficacy of inhibition and the control of neuronal excitability in the spinal cord. GlyR accumulation at synapses depends on the scaffolding molecule gephyrin and is linked to GlyR synaptic dwell time. However, the mechanisms that tune GlyR synaptic exchanges in response to different neuronal environments are unknown. Integrins are cell adhesion molecules and signaling receptors. Using single quantum dot imaging and fluorescence recovery after photobleaching, we found in rats that ß1 and ß3 integrins adjust synaptic strength by regulating the synaptic dwell time of both GlyRs and gephyrin. ß1 and ß3 integrins crosstalked via calcium/calmodulin-dependent protein kinase II and adapted GlyR lateral diffusion and gephyrin-dependent trapping at synapses. This provides a mechanism for maintaining or adjusting the steady state of postsynaptic molecule exchanges and the level of glycinergic inhibition in response to neuron- and glia-derived signals or extracellular matrix remodeling.