Thrombin promotes actin stress fiber formation in RPE through Rho/ROCK-mediated MLC phosphorylation

Micro/nano topological modification of TiO2 nanotubes activates Thy-1 signaling to control osteogenic differentiation of stem cells

Micro/nano topological modification is critical for improving the in vivo behaviors of bone implants, regulating multiple cellular functions. Titania (TiO2) nanotubes show the capacity of promoting osteoblast-related cell differentiation and induce effective osseointegration, serving as a model material for studying the effects of micro/nano-topological modifications on cells. However, the intracellular signaling pathways by which TiO2 nanotubes regulate the osteogenic differentiation of stem cells are not fully defined. Thy-1 (CD90), a cell surface glycoprotein anchored by glycosylphosphatidylinositol, has been considered a key molecule in osteoblast differentiation in recent years. Nevertheless, whether the micro/nano topology of the implant surface leads to changes in Thy-1 is unknown, as well as whether these changes promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Here, TiO2 nanotubes of various diameters were prepared by adjusting the anodizing voltage. qPCR and immunoblot were carried out to assess the mechanism by which TiO2 nanotubes regulate Thy-1. The results revealed Ti plates harboring TiO2 nanotubes ∼100-nm diameter (TNT-100) markedly upregulated Thy-1. Subsequently, upregulated Thy-1 promoted the activation of Fyn/RhoA/MLC Ⅱ/F-actin axis, which enhanced the nuclear translocation of YAP. After Thy-1 knockdown by siRNA, the Fyn/RhoA/MLC Ⅱ/F-actin axis was significantly inhibited and TiO2 nanotubes showed decreased effects on osteogenic differentiation. Therefore, Thy-1 upregulation might be a major mechanism by which micro/nano-topological modification of TiO2 nanotubes promotes osteogenic differentiation in BMSCs. This study provides novel insights into the molecular mechanism of TiO2 nanotubes, which may help design improved bone implants for clinical application.

Inhibition of Rho kinase (ROCK) impairs cytoskeletal contractility in human Müller glial cells without effects on cell viability, migration, and extracellular matrix production

The epiretinal membrane is a fibrocontractile tissue that forms on the inner surface of the retina, causing visual impairment ranging from mild to severe, and even retinal detachment. Müller glial cells actively participate in the formation of this membrane. Current research is constantly seeking for new therapeutic approaches that aim to prevent or treat cellular dysfunctions involved in the progression of this common fibrosis condition. The Rho GTPases signaling pathway regulates several processes associated with the epiretinal membrane, such as cell proliferation, migration, and contraction. Rho kinase (ROCK), an effector of the RhoA GTPase, is an interesting potential therapeutic target. This study aimed to evaluate the effects of a ROCK inhibitor (Y27632) on human Müller cells viability, growth, cytoskeletal organization, expression of extracellular matrix components, myofibroblast differentiation, migration, and contractility. Müller cells of the MIO-M1 lineage were cultured and treated for different periods with the inhibitor. Viability was evaluated by MTT assay and trypan blue exclusion method, and growth was evaluated by growth curve and BrdU incorporation assay. The actin cytoskeleton was stained with fluorescent phalloidin, intermediate filaments and microtubules were analyzed with immunofluorescence for vimentin and α-tubulin. Gene and protein expression of collagens I and V, laminin and fibronectin were evaluated by rt-PCR and immunofluorescence. Chemotactic and spontaneous cell migration were studied by transwell assay and time-lapse observation of live cells, respectively. Cell contractility was assessed by collagen gel contraction assay. The results showed that ROCK inhibition by Y27632 did not affect cell viability, but decreased cell growth and proliferation after 72 h. There was a change in cell morphology and organization of F-actin, with a reduction in the cell body, disappearance of stress fibers and formation of long, branched cell extensions. Microtubules and vimentin filaments were also affected, possibly because of F-actin alterations. The inhibitor also reduced gene expression and immunoreactivity of smooth muscle α-actin, a marker of myofibroblasts. The expression of extracellular matrix components was not affected by the inhibitor. Chemotactic cell migration showed no significant changes, while cell contractility was substantially reduced. No spontaneous migration of MIO-M1 cells was observed. In conclusion, pharmacological inhibition of ROCK in Müller cells could be a potentially promising approach to treat epiretinal membranes by preventing cell proliferation, contractility and transdifferentiation, without affecting cell viability.

A crucial stem cell plasticity regulation pathway: identification of key elements using the NCCIT human embryonic carcinoma cell line

Upon removal of stemness factors, a small subpopulation of embryonic stem cells (ESCs) spontaneously extrudes the t-SNARE protein syntaxin-4, which upregulates the cell adhesion molecule P-cadherin and induces the onset of epithelial-mesenchymal transition (EMT)-like behaviors with loss of stemness in each cell. In this study, we identified a series of molecular elements responsible for this phenomenon using several small-molecule inhibitors and the human embryonic carcinoma cell line, NCCIT. We found that the syntaxin-4-triggered morphological changes and a decrease in stemness signatures were independently induced by the activation of Rho-associated kinase (ROCK) and the abrogation of PI3K/Akt signaling. We also found that the extracellular expression of syntaxin-4 inactivated focal adhesion kinase (FAK) in association with the augmented expression of P-cadherin, and comparable controls of either of these downstream elements of syntaxin-4 accelerated both ROCK-induced F-actin stress fiber formation and P13K/Akt-suppressed loss of stemness signatures. Cells expressing P-cadherin inactivated FAK but FAK inhibition did not affect P-cadherin expression, demonstrating a causal relationship between P-cadherin and FAK in the event of syntaxin-4 induction. These results reveal a novel signaling axis in stem cells and shed new light on the crucial elements for stem cell plasticity and the maintenance of stemness.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

Glucuronoxylomannan intranasal challenge prior to Cryptococcus neoformans pulmonary infection enhances cerebral cryptococcosis in rodents

The encapsulated fungus Cryptococcus neoformans is the most common cause of fungal meningitis, with the highest rate of disease in patients with AIDS or immunosuppression. This microbe enters the human body via inhalation of infectious particles. C. neoformans capsular polysaccharide, in which the major component is glucuronoxylomannan (GXM), extensively accumulates in tissues and compromises host immune responses. C. neoformans travels from the lungs to the bloodstream and crosses to the brain via transcytosis, paracytosis, or inside of phagocytes using a "Trojan horse" mechanism. The fungus causes life-threatening meningoencephalitis with high mortality rates. Hence, we investigated the impact of intranasal exogenous GXM administration on C. neoformans infection in C57BL/6 mice. GXM enhances cryptococcal pulmonary infection and facilitates fungal systemic dissemination and brain invasion. Pre-challenge of GXM results in detection of the polysaccharide in lungs, serum, and surprisingly brain, the latter likely reached through the nasal cavity. GXM significantly alters endothelial cell tight junction protein expression in vivo, suggesting significant implications for the C. neoformans mechanisms of brain invasion. Using a microtiter transwell system, we showed that GXM disrupts the trans-endothelial electrical resistance, weakening human brain endothelial cell monolayers co-cultured with pericytes, supportive cells of blood vessels/capillaries found in the blood-brain barrier (BBB) to promote C. neoformans BBB penetration. Our findings should be considered in the development of therapeutics to combat the devastating complications of cryptococcosis that results in an estimated ~200,000 deaths worldwide each year.

Spiromesifen contributes vascular developmental toxicity via disrupting endothelial cell proliferation and migration in zebrafish embryos

Spiromesifen (SPF) is a specific contact pesticide, which has been widely used to control the growth of sucking insects like mites and whiteflies on crops. Although its residues in crops and effects on organisms has been extensively reported, its impact on the vasculature is still not being reported. In the present study, using human umbilical vein endothelial cells (HUVECs) and zebrafish embryos, we investigated the effects of SPF on blood vessel development and its mechanism of action. SPF exposure triggered abnormal blood vessel development, including vascular deletions and malformations, inhibition of CCV remodeling, and decrease of SIV areas. SPF exposure also obstructed the migration of endothelial cell from caudal hematopoietic tissue in zebrafish embryos. SPF damaged cytoskeleton, caused cell cycle arrest, inhibited the viability and migration of HUVECs. In addition, SPF also inhibited the expression of the VEGF/VEGFR pathway-related genes (hif1a, vegfa, flt1, and kdrl), cell cycle-related genes (ccnd1, ccne1, cdk2, and pcna), and Rho/ROCK pathway-related genes (itgb1, rho, rock, mlc-1, and vim-1). Taken together, SPF may inhibit the proliferation and migration of vascular endothelial cells through disturbing cytoskeleton via the Rho/ ROCK pathway, resulting in vascular malformation. Our study contributes to potential insight into the mechanism of SPF toxicity in angiocardiopathy.

Sphingosine-1-phosphate and ceramide-1-phosphate promote migration, pro-inflammatory and pro-fibrotic responses in retinal pigment epithelium cells

Retinal pigment epithelium (RPE) cells, essential for preserving retina homeostasis, also contribute to the development of retina proliferative diseases, through their exacerbated migration, epithelial to mesenchymal transition (EMT) and inflammatory response. Uncovering the mechanisms inducing these changes is crucial for designing effective treatments for these pathologies. Sphingosine-1-phosphate (S1P) and ceramide-1-phosphate (C1P) are bioactive sphingolipids that promote migration and inflammation in several cell types; we recently established that they stimulate the migration of retina Müller glial cells (Simón et al., 2015; Vera et al., 2021). We here analyzed whether S1P and C1P regulate migration, inflammation and EMT in RPE cells. We cultured two human RPE cell lines, ARPE-19 and D407 cells, and supplemented them with either 5 μM S1P or 10 μM C1P, or their vehicles, for 24 h. Analysis of cell migration by the scratch wound assay showed that S1P addition significantly enhanced migration in both cell lines. Pre-treatment with W146 and BML-241, antagonists for S1P receptor 1 (S1P1) and 3 (S1P3), respectively, blocked exogenous S1P-induced migration. Inhibiting sphingosine kinase 1 (SphK1), the enzyme involved in S1P synthesis, significantly reduced cell migration and exogenous S1P only partially restored it. Addition of C1P markedly stimulated cell migration. Whereas inhibiting C1P synthesis did not affect C1P-induced migration, inhibiting S1P synthesis strikingly decreased it; noteworthy, addition of C1P promoted the transcription of SphK1. These results suggest that S1P and C1P stimulate RPE cell migration and their effect requires S1P endogenous synthesis. Both S1P and C1P increase the transcription of pro-inflammatory cytokines IL-6 and IL-8, and of EMT marker α-smooth muscle actin (α-SMA) in ARPE-19 cells. Collectively, our results suggest new roles for S1P and C1P in the regulation of RPE cell migration and inflammation; since the deregulation of sphingolipid metabolism is involved in several proliferative retinopathies, targeting their metabolism might provide new tools for treating these pathologies.

Extracellular vesicles-incorporated microRNA signature as biomarker and diagnosis of prediabetes state and its complications

Extracellular vesicles (EVs) are small anuclear vesicles, delimited by a lipid bilayer, released by almost all cell types, carrying functionally active biological molecules that can be transferred to the neighbouring or distant cells, inducing phenotypical and functional changes, relevant in various physio-pathological conditions. The microRNAs are the most significant active components transported by EVs, with crucial role in intercellular communication and significant effects on recipient cells. They may also server as novel valuable biomarkers for the diagnosis of metabolic disorders. Moreover, EVs are supposed to mediate type 2 diabetes mellitus (T2DM) risk and its progress. The T2DM development is preceded by prediabetes, a state that is associated with early forms of nephropathy and neuropathy, chronic kidney disease, diabetic retinopathy, and increased risk of macrovascular disease. Although the interest of scientists was focused not only on the pathogenesis of diabetes, but also on the early diagnosis, little is known about EVs-incorporated microRNA involvement in prediabetes state and its microvascular and macrovascular complications. Here, we survey the biogenesis, classification, content, biological functions and the most popular primary isolation methods of EVs, review the EVs-associated microRNA profiling connexion with early stages of diabetes and discuss the role of EVs containing specific microRNAs in prediabetes complications.

Sulforaphane suppresses metastasis of triple-negative breast cancer cells by targeting the RAF/MEK/ERK pathway

Breast cancer metastasis is the main cause of cancer death in women, so far, no effective treatment has inhibited breast cancer metastasis. Sulforaphane (SFN), a natural compound derived from broccoli, has shown potential health benefits in many cancers. However, research on breast cancer metastasis is still insufficient. Here, we showed that SFN, including its two isomers of R-SFN and S-SFN, significantly inhibited TGF-β1-induced migration and invasion in breast cancer cells. Proteomic and phosphoproteomic analysis showed that SFN affected the formation of the cytoskeleton. Subsequent experiments confirmed that SFN significantly inhibited TGF-β1-induced actin stress fiber formation and the expression of actin stress fiber formation-associated proteins, including paxillin, IQGAP1, FAK, PAK2, and ROCK. Additionally, SFN is directly bound to RAF family proteins (including ARAF, BRAF, and CRAF) and inhibited MEK and ERK phosphorylation. These in vitro results indicate that SFN targets the RAF/MEK/ERK signaling pathway to inhibit the formation of actin stress fibers, thereby inhibiting breast cancer cell metastasis.

Roles of RAGE/ROCK1 Pathway in HMGB1-Induced Early Changes in Barrier Permeability of Human Pulmonary Microvascular Endothelial Cell

Background

High mobility group box 1 (HMGB1) causes microvascular endothelial cell barrier dysfunction during acute lung injury (ALI) in sepsis, but the mechanisms have not been well understood. We studied the roles of RAGE and Rho kinase 1 (ROCK1) in HMGB1-induced human pulmonary endothelial barrier disruption.

Methods

In the present study, the recombinant human high mobility group box 1 (rhHMGB1) was used to stimulate human pulmonary microvascular endothelial cells (HPMECs). The endothelial cell (EC) barrier permeability was examined by detecting FITC-dextran flux. CCK-8 assay was used to detect cell viability under rhHMGB1 treatments. The expression of related molecules involved in RhoA/ROCK1 pathway, phosphorylation of myosin light chain (MLC), F-actin, VE-cadherin and ZO-1 of different treated groups were measured by pull-down assay, western blot and immunofluorescence. Furthermore, we studied the effects of Rho kinase inhibitor (Y-27632), ROCK1/2 siRNA, RAGE-specific blocker (FPS-ZM1) and RAGE siRNA on endothelial barrier properties to elucidate the related mechanisms.

Results

In the present study, we demonstrated that rhHMGB1 induced EC barrier hyperpermeability in a dose-dependent and time-dependent manner by measuring FITC-dextran flux, a reflection of the loss of EC barrier integrity. Moreover, rhHMGB1 induced a dose-dependent and time-dependent increases in paracellular gap formation accompanied by the development of stress fiber rearrangement and disruption of VE-cadherin and ZO-1, a phenotypic change related to increased endothelial contractility and endothelial barrier permeability. Using inhibitors and siRNAs directed against RAGE and ROCK1/2, we systematically determined that RAGE mediated the rhHMGB1-induced stress fiber reorganization via RhoA/ROCK1 signaling activation and the subsequent MLC phosphorylation in ECs.

Conclusion

HMGB1 is capable of disrupting the endothelial barrier integrity. This study demonstrates that HMGB1 activates RhoA/ROCK1 pathway via RAGE, which phosphorylates MLC inducing stress fiber formation at short time, and HMGB1/RAGE reduces AJ/TJ expression at long term independently of RhoA/ROCK1 signaling pathway.

Rho-Kinase Inhibitors for the Treatment of Refractory Diabetic Macular Oedema

Diabetic macular oedema (DMO) is one of the leading causes of vision loss associated with diabetic retinopathy (DR). New insights in managing this condition have changed the paradigm in its treatment, with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) having become the standard therapy for DMO worldwide. However, there is no single standard therapy for all patients DMO refractory to anti-VEGF treatment; thus, further investigation is still needed. The key obstacles in developing suitable therapeutics for refractory DMO lie in its complex pathophysiology; therefore, there is an opportunity for further improvements in the progress and applications of new drugs. Previous studies have indicated that Rho-associated kinase (Rho-kinase/ROCK) is an essential molecule in the pathogenesis of DMO. This is why the Rho/ROCK signalling pathway has been proposed as a possible target for new treatments. The present review focuses on the recent progress on the possible role of ROCK and its therapeutic potential in DMO. A systematic literature search was performed, covering the years 1991 to 2021, using the following keywords: "rho-Associated Kinas-es", "Diabetic Retinopathy", "Macular Edema", "Ripasudil", "Fasudil" and "Netarsudil". Better insight into the pathological role of Rho-kinase/ROCK may lead to the development of new strategies for refractory DMO treatment and prevention.

High-expression of ROCK1 modulates the apoptosis of lens epithelial cells in age-related cataracts by targeting p53 gene

Background

Age-related cataract (ARC) is a serious visual impairment disease, and its pathogenesis is unclear. This article aims to investigate the role of ROCK1 in the apoptosis of lens epithelial cells (LECs) in age-related cataracts.

Methods

We collect anterior capsule samples from normal people, patients with age-related cataracts, young mice and naturally aging cataract mice. The oxidative stress-induced apoptosis model was constructed by cultivating HLE-B3 cells with H₂O₂. MTT, Hoechst 33342, and TUNEL assay were performed to explore proliferation and apoptosis. HE assay was used to observe cell morphology. The gene and protein expression were assessed by quantitative real-time PCR, western blot, immunofluorescence, and immunohistochemical staining.

Result

The results from the clinic and mice experiments showed that the numbers of lens epithelial cells from cataract individuals were less than the control individuals. In vitro, the apoptotic cells were increased in lens epithelial cells under H₂O₂ treatment. The ROCK1 protein level increased in the lens epithelial cells from age-related cataract patients and the old mice, respectively. Meanwhile, the up-regulation of the ROCK1 gene was associated with H₂O₂-induced HLE-B3 cells apoptosis. MTT and apoptosis assay showed ROCK1 was necessary in mediating H₂O₂-induced lens epithelial cells apoptosis through ROCK1 over-expression and knockdown experiment, respectively. Further investigation showed that p53 protein levels had been increased during ROCK1-mediated apoptosis in response to H₂O₂. Besides, ROCK1 phosphorylated p53 at ser15 to up-regulate its protein level.

Conclusions

This study established the novel association of ROCK1/p53 signaling with lens epithelial cells apoptosis and age-related cataract genesis.

Polarity and epithelial-mesenchymal transition of retinal pigment epithelial cells in proliferative vitreoretinopathy

Under physiological conditions, retinal pigment epithelium (RPE) is a cellular monolayer composed of mitotically quiescent cells. Tight junctions and adherens junctions maintain the polarity of RPE cells, and are required for cellular functions. In proliferative vitreoretinopathy (PVR), upon retinal tear, RPE cells lose cell-cell contact, undergo epithelial-mesenchymal transition (EMT), and ultimately transform into myofibroblasts, leading to the formation of fibrocellular membranes on both surfaces of the detached retina and on the posterior hyaloids, which causes tractional retinal detachment. In PVR, RPE cells are crucial contributors, and multiple signaling pathways, including the SMAD-dependent pathway, Rho pathway, MAPK pathways, Jagged/Notch pathway, and the Wnt/β-catenin pathway are activated. These pathways mediate the EMT of RPE cells, which play a key role in the pathogenesis of PVR. This review summarizes the current body of knowledge on the polarized phenotype of RPE, the role of cell-cell contact, and the molecular mechanisms underlying the RPE EMT in PVR, emphasizing key insights into potential approaches to prevent PVR.

Thrombin-activated PAR1 membrane expression is regulated by Rab11a-RCP complex dissociation

PAR1 activation by thrombin promotes intracellular signaling leading to RPE cell transformation, proliferation, and migration, characteristic of fibroproliferative eye diseases. Due to the cleavage of PAR1 N-terminal domain, carried by thrombin, the arrest of PAR1 signaling is achieved by transport into lysosomes and degradation. Recent findings suggest that the GTPase Rab11a in conjunction with its effector RCP may direct PAR1 to lysosomes. Hereby we demonstrate that thrombin-induced PAR1 internalization and lysosomal targeting requires the disassembly of the Rab11a/RCP complex, and that this process depends on thrombin-induced intracellular calcium increase and calpain activation. These findings unveil a novel mechanism that regulates thrombin activated PAR1 internalization and degradation.

RhoA/ROCK Pathway Activation is Regulated by AT1 Receptor and Participates in Smooth Muscle Migration and Dedifferentiation via Promoting Actin Cytoskeleton Polymerization

BACKGROUND

In this study, we investigated the mechanism of Rho GTPases signaling on Ang II-mediated cell migration and dedifferentiation in human aortic vascular smooth muscle cells (HA-VSMCs) and an Ang II-infusion mouse model.

METHODS

Cells were pretreated with different inhibitors or Ang II. Cell migration was detected by Wound healing and Transwell assay. Mice were treated with Ad-RhoA-shRNA virus or Irbesartan or fasudil and then infused with Ang II.

RESULTS

Ang II treatment induced HA-VSMCs migration in a dose- and time-dependent manner and reduced the expression of VSMC contractile proteins. These effects were significantly suppressed by the inhibition of Ang II type 1 receptor (AT1 receptor), RhoA, and Rho-associated kinase (ROCK). Furthermore, Ang II treatment promoted the activation of RhoA and ROCK, which was reduced by AT1 receptor inhibition. Meanwhile, Ang II treatment induced F-actin polymerization, which was inhibited after ROCK inhibition. In mice, Ang II infusion increased VSMC migration into the neointima and reduced VSMC differentiation proteins levels, and these effects were shown to be dependent on AT1 receptor and RhoA/ROCK pathway.

CONCLUSION

This study reveals a novel mechanism by which Ang II regulates RhoA/ROCK signaling and actin polymerization via AT1 receptor and then affects VSMC dedifferentiation.

Cylindrospermopsin induces abnormal vascular development through impairing cytoskeleton and promoting vascular endothelial cell apoptosis by the Rho/ROCK signaling pathway

Cylindrospermopsin (CYN) is a widely distributed cyanobacterial toxin in water bodies and is considered to pose growing threats to human and environmental health. Although its potential toxicity has been reported, its effects on the vascular system are poorly understood. In this study, we examined the toxic effects of CYN on vascular development and the possible mechanism of vascular toxicity induced by CYN using zebrafish embryos and human umbilical vein endothelial cells (HUVECs). CYN exposure induced abnormal vascular development and led to an increase in the growth of common cardinal vein (CCV), in which CCV remodeling was delayed as reflected by the larger CCV area and wider ventral diameter. CYN decreased HUVECs viability, inhibited HUVECs migration, promoted HUVECs apoptosis, destroyed cytoskeleton, and increased intracellular ROS levels. Additionally, CYN could promote the expression of Bax, Bcl-2, and MLC-1 and inhibit the expression of ITGB1, Rho, ROCK, and VIM-1. Taken together, CYN may induce cytoskeleton damage and promote vascular endothelial cell apoptosis by the Rho/ROCK signaling pathway, leading to abnormal vascular development. The current results provide potential insight into the mechanism of CYN toxicity in angiocardiopathy and are beneficial for understanding the environmental risks of CYN for aquatic organisms and human health.

The Traditional Chinese Medicine Compound, GRS, Alleviates Blood-Brain Barrier Dysfunction

Introduction

Traditional Chinese medicine (TCM) provides unique advantages for treatment of ischemic stroke, an aging-related vascular disease. Shengmai powder (GRS) is composed of three active components, specifically, ginsenoside Rb1, ruscogenin and schisandrin A, at a ratio of 6:0.75:6. The main objective of this study was to evaluate the effects of GRS on blood–brain barrier (BBB) dysfunction under conditions of middle cerebral artery occlusion/reperfusion (MCAO/R).

Methods

C57BL/6J mice subjected to MCAO/R were used as a model to assess the protective effects of varying doses of GRS (6.4, 12.8, and 19.2 mg/kg) on BBB dysfunction.

Results

GRS reduced cerebral infarct volume and degree of brain tissue damage, improved behavioral scores, decreased water content and BBB permeability, and restored cerebral blood flow. Moreover, GRS promoted expression of zona occludens-1 (ZO-1) and claudin-5 while inhibiting matrix metalloproteinase 2/9 (MMP-2/9) expression and myosin light chain (MLC) phosphorylation. In vitro, GRS (1, 10, and 100 ng/mL) enhanced the viability of bEnd.3 cells subjected to oxygen glucose deprivation/reoxygenation (OGD/R) and decreased sodium fluorescein permeability.

Conclusion

Consistent with in vivo findings, ZO-1 and claudin-5 were significantly upregulated by GRS in bEnd.3 cells under OGD/R and MMP-2/9 levels and MLC phosphorylation reduced through the Rho-associated coil-forming protein kinase (ROCK)/cofilin signaling pathway. Based on the collective findings, we propose that the TCM compound, GRS, plays a protective role against I/R-induced BBB dysfunction.

Forsythoside A and Forsythoside B Contribute to Shuanghuanglian Injection-Induced Pseudoallergic Reactions through the RhoA/ROCK Signaling Pathway

In recent years, hypersensitivity reactions to the Shuanghuanglian injection have attracted broad attention. However, the componential chief culprits inducing the reactions and the underlying mechanisms involved have not been completely defined. In this study, we used a combination of approaches based on the mouse model, human umbilical vein endothelial cell monolayer, real-time cellular monitoring, immunoblot analysis, pharmacological inhibition, and molecular docking. We demonstrated that forsythoside A and forsythoside B contributed to Shuanghuanglian injection-induced pseudoallergic reactions through activation of the RhoA/ROCK signaling pathway. Forsythoside A and forsythoside B could trigger dose-dependent vascular leakage in mice. Moreover, forsythoside A and forsythoside B slightly elicited mast cell degranulation. Correspondingly, treatment with forsythoside A and forsythoside B disrupted the endothelial barrier and augmented the expression of GTP-RhoA, p-MYPT1, and p-MLC2 in a concentration-dependent manner. Additionally, the ROCK inhibitor effectively alleviated forsythoside A/forsythoside B-induced hyperpermeability in both the endothelial cells and mice. Similar responses were not observed in the forsythoside E-treated animals and cells. These differences may be related to the potential of the tested compounds to react with RhoA-GTPγS and form stable interactions. This study innovatively revealed that some forsythosides may cause vascular leakage, and therefore, limiting their contents in injections should be considered.

Glucose Transporter 1 Promotes the Malignant Phenotype of Non-Small Cell Lung Cancer through Integrin β1/Src/FAK Signaling

Background: Glucose transporter 1 (GLUT1) is the main factor of Warburg effect, which is associated with poor prognosis in many tumors. However, the underlying molecular mechanism of GLUT1 in the progression of non-small cell lung cancer (NSCLC) is unclear.

Methods: We used quantitative real-time PCR to detect GLUT1 mRNA expression in bronchial brushing samples and performed Western Blot and biological behavior testing to check the effect of GLUT1 on NSCLC cell proliferation, migration, invasion and apoptosis.

Results: We found that the C(t) normalized value of GLUT1 in malignant bronchial brushing samples was significantly higher than that in benign samples (P<0.05). GLUT1 significantly increased the expressions of cyclin A, cyclin D1, cyclin E, cyclin dependent kinase 2 (CDK2), CDK4, CDK6 and matrix metalloproteinase 2 (MMP2), but decreased the expressions of p53 and p130 in NSCLC cells. The biological behavior testing indicated that GLUT1 enhanced NSCLC cell proliferation, invasion and migration but inhibited cell apoptosis. In addition, GLUT1 upregulated the expression of integrin β1 and promoted the phosphorylation of focal adhesion kinase (FAK, phosphorylation at Tyr576/577) and Src (Src phosphorylation at Tyr530). siRNA knock down of integrin β1 expression suppressed GLUT1 induced NSCLC cell biological behavior, as well as the phosphorylation of FAK and Src.

Conclusion: Taken together, our data confirms that GLUT1 promotes the malignant phenotype of NSCLC through integrin β1/Src/FAK signaling, which provides a new therapeutic target for the treatment and research of lung cancer.

Prediction of skin anti-aging clinical benefits of an association of ingredients from marine and maritime origins: Ex vivo evaluation using a label-free quantitative proteomic and customized data processing approach

BACKGROUND

The application of ingredients from marine and maritime origins is increasingly common in skin care products, driven by consumer expectations for natural ingredients. However, these ingredients are typically studied for a few isolated in vitro activities.

OBJECTIVES

The purpose of this study was to carry out a comprehensive evaluation of the activity on the skin of an association of ingredients from marine and maritime origins using label-free quantitative proteomic analysis, in order to predict the clinical benefits if used in a skin care product.

METHODS

An aqueous gel containing 6.1% of ingredients from marine and maritime origins (amino acid-enriched giant kelp extract, trace element-enriched seawater, dedifferentiated sea fennel cells) was topically applied on human skin explants. The skin explants' proteome was analyzed in a label-free manner by high-performance liquid nano-chromatography coupled with tandem mass spectrometry. A specific data processing pipeline (CORAVALID) providing an objective and comprehensive interpretation of the statistically relevant biological activities processed the results.

RESULTS

Compared to untreated skin explants, 64 proteins were significantly regulated by the gel treatment (q-value ≤ 0.05). Computer data processing revealed an activity of the ingredients on the epidermis and the dermis. These significantly regulated proteins are involved in gene expression, cell survival and metabolism, inflammatory processes, dermal extracellular matrix synthesis, melanogenesis and keratinocyte proliferation, migration, and differentiation.

CONCLUSIONS

These results suggest that the tested ingredients could help to preserve a healthy epidermis and dermis, and possibly to prevent the visible signs of skin aging.

A proteomics study to explore the role of adsorbed serum proteins for PC12 cell adhesion and growth on chitosan and collagen/chitosan surfaces

The aim of this article is to apply proteomics in the comparison of the molecular mechanisms of PC12 cell adhesion and growth mediated by the adsorbed serum proteins on the surfaces of chitosan and collagen/chitosan films. First, the chitosan and the collagen/chitosan films were prepared by spin coating; and their surface morphologies were characterized by scanning electron microscopy, X-ray energy dispersive spectroscopy, contact angle measurement and Fourier transform infrared spectroscopy. Subsequently, cell proliferation experiments on two materials were performed and the dynamic curves of protein adsorption on their surfaces were measured. Then, proteomics and bioinformatics were used to analyze and compare the adsorbed serum proteins on the surfaces of two biomaterials; and their effects on cell adhesion were discussed. The results showed that the optimum concentration of chitosan film was 2% w/v. When compared with chitosan film, collagen/chitosan film promoted the growth and proliferation of PC12 cells more significantly. Although the dynamic curves showed no significant difference in the total amount of the adsorbed proteins on both surfaces, proteomics and bioinformatics analyses revealed a difference in protein types: the chitosan surface adsorbed more vitronectin whereas collagen/chitosan surface adsorbed more fibronectin 1 and contained more cell surface receptor binding sites and more Leu-Asp-Val sequences in its surface structure; the collagen/chitosan surface were more conducive to promoting cell adhesion and growth.

Vascularization converts the lineage fate of bone mesenchymal stem cells to endothelial cells in tissue-engineered bone grafts by modulating FGF2-RhoA/ROCK signaling

The prevascularization of tissue-engineered bone grafts (TEBGs) has been shown to accelerate capillary vessel ingrowth in bone defect remodeling and to enhance new bone formation. However, the exact mechanisms behind this positive effect remain unknown. Here, we report that basic fibroblast growth factor (FGF2)-Ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) signaling functions as a molecular switch to regulate the lineage fate of bone mesenchymal stem cells (BMSCs) and that prevascularization promotes the cell fate switch, which contributes to increased bone regeneration with the use of prevascularized TEBGs compared with control TEBGs. Prevascularized TEBGs enhanced the in vivo endothelial differentiation of BMSCs by inhibiting RhoA/ROCK signaling. In vitro data more clearly showed that BMSCs differentiated into von Willebrand factor (vWF)-positive endothelial cells, and FGF2-induced inhibition of RhoA/ROCK signaling played a key role. Our novel findings uncovered a new mechanism that stimulates the increased vascularization of engineered bone and enhanced regeneration by promoting the endothelial differentiation of BMSCs implanted in TEBGs. These results offer a new molecular target to regulate TEBG-induced bone regeneration.

miR‑133b regulates proliferation and apoptosis in high‑glucose‑induced human retinal endothelial cells by targeting ras homolog family member A

The aim of the present study was to investigate the role of microRNA (miR)‑133b in high‑glucose‑induced human retinal endothelial cells (hRECs), particularly regarding its potential targeting of ras homolog family member A (RhoA). To establish the high‑glucose‑induced diabetic retinopathy (DR) model, hRECs were cultured in high‑glucose medium for 1, 2 and 3 days. An Annexin allophycocyanin (APC)/7‑aminoactinomycin D (7‑AAD) staining assay was performed to measure the apoptosis of hRECs. Next, the cells were transfected with miR‑133b inhibitors or mimics, and the cell proliferation and apoptosis were measured by MTT and Annexin‑APC/7‑AAD staining assays, respectively. In addition, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), western blotting and immunocytochemistry were used to detect the expression levels of RhoA, Rho‑associated protein kinase 1 (ROCK1), LIM domain kinase 1 (LIMK), myosin light chain (MLC) and phosphorylated (p)‑MLC. It was observed that high‑glucose or miR‑133b inhibitor treatment attenuated the apoptosis of hRECs, and upregulated the mRNA and protein expression levels of RhoA, ROCK1 and LIMK, as well as the p‑MLC protein level, in the hRECs. However, miR‑133b overexpression inhibited the cell proliferation, promoted apoptosis, and downregulated the mRNA and protein levels of RhoA, ROCK1 and LIMK, as well as p‑MLC protein, in high‑glucose‑induced hRECs. In conclusion, overexpression of miR‑133b inhibited the proliferation and promoted apoptosis in a DR cell model by downregulating RhoA expression.

Go with the flow: GEF-H1 mediated shear stress mechanotransduction in neutrophils

Neutrophils in circulation experience significant shear forces due to blood flow when they tether to the vascular endothelium. Biochemical and biophysical responses of neutrophils to the physical force of flowing blood modulate their behavior and promote tissue recruitment under pro-inflammatory conditions. Neutrophil mechanotransduction responses occur through mechanisms that are not yet fully understood. In our recent work, we showed that GEF-H1, a RhoA specific guanine nucleotide exchange factor (GEF), is required to maintain neutrophil motility and migration in response to shear stress. GEF-H1 re-localizes to flottilin-rich uropods in neutrophils in response to fluid shear stress and promotes spreading and crawling on activated endothelial cells. GEF-H1 drives cellular contractility through myosin light chain (MLC) phosphorylation downstream of the Rho-ROCK signaling axis. We propose that GEF-H1-dependent cell spreading and crawling in shear stress-dependent neutrophil recruitment from the vasculature are due to the specific localization of Rho-induced contractility in the uropod.

Macrophage differentiation induced by PMA is mediated by activation of RhoA/ROCK signaling

In order to investigate the effects of RhoA/ROCK signaling in macrophage differentiation, we used 100 ng/mL PMA to induce macrophage differentiation from U937 cells in vitro. The observation of cell morphology and the expression of CD68 and SR-A were performed to confirm the differentiation induced by PMA. Western blot analysis showed that the expression of ROCK1 and ROCK2 and the phosphorylation of MYPT1 were significantly increased after PMA treatment. Pulldown assay showed that the activation of RhoA was obviously enhanced when U937 cells were treated with PMA. In order to further demonstrate whether RhoA/ROCK signaling could mediate the macrophage differentiation induced by PMA, we successfully suppressed the expression of RhoA, ROCK1 and ROCK2 by performing siRNA technology in U937 cells, respectively. The macrophage differentiation and the expression of CD68 and SR-A were significantly inhibited by the suppression of RhoA, ROCK1 or ROCK2 in PMA-induced U937 cells, indicating that the macrophage differentiation induced by PMA is associated with RhoA/ROCK signaling pathway. In addition, we pretreated U937 cells with Y27632 (ROCK inhibitor, 20 μM) for 30 min and then observed the macrophage differentiation induced by PMA. The result illustrated that Y27632 pretreatment obviously inhibited PMA-induced differentiation and the expression of CD68 and SR-A. In conclusion, the activation of RhoA/ROCK signaling is responsible for the macrophage differentiation induced by PMA.

HIF-3α Promotes Metastatic Phenotypes in Pancreatic Cancer by Transcriptional Regulation of the RhoC-ROCK1 Signaling Pathway

Hypoxia contributes to pancreatic cancer progression and promotes its growth and invasion. Previous research principally focused on hypoxia-inducible factor-1 alpha (HIF-1α) and HIF-2α (HIF1A and EPAS1) as the major hypoxia-associated transcription factors in pancreatic cancer. However, the role of HIF-3α (HIF3A) has not been investigated. Therefore, HIF-1α, HIF-2α, and HIF-3α expression levels were measured under normoxic and hypoxic conditions. In addition, HIF-3α expression was measured in human pancreatic cancer tissue specimens and the impact of altered HIF-3α expression on cell invasion and migration was investigated in vitro and in vivo, as well as the underlying mechanisms. Under hypoxic conditions, HIF-3α expression was stimulated in pancreatic cancer cells to a greater degree than HIF-1α and HIF-2α expression. HIF-3α protein levels were also elevated in pancreatic cancer tissues and correlated with reduced survival and greater local invasion and distant metastasis, whereas knockdown of HIF-3α, under hypoxic conditions, suppressed pancreatic cancer cell invasion and migration. Under normoxia, HIF-3α overexpression promoted pancreatic cancer cell invasion and migration and stimulated F-actin polymerization. In summary, HIF-3α promotes pancreatic cancer cell invasion and metastasis in vivo and promotes pancreatic cancer cell invasion and metastasis by transcriptionally activating the RhoC-ROCK1 signaling pathway.Implications: HIF3α is overexpressed in pancreatic cancer, and targeting the HIF3α/RhoC-ROCK1 signaling pathway may be a novel therapeutic approach for the treatment of pancreatic cancer invasion and metastasis. Mol Cancer Res; 16(1); 124-34. ©2017 AACR.

Raf-1/CK2 and RhoA/ROCK signaling promote TNF-α-mediated endothelial apoptosis via regulating vimentin cytoskeleton

Both RhoA/ROCK and Raf-1/CK2 pathway play essential roles in cell proliferation, apoptosis, differentiation, and multiple other common cellular functions. We previously reported that vimentin is responsible for TNF-α-induced cell apoptosis. Herein, we investigated the regulation of RhoA/ROCK and Raf-1/CK2 signaling on vimentin filaments and endothelial apoptosis mediated by TNF-α. Treatment with TNF-α significantly induced the activation of RhoA and ROCK, and the expression of ROCK1. RhoA deficiency could obviously inhibit ROCK activation and ROCK1 expression induced by TNF-α. Both RhoA deficiency and ROCK activity inhibition (Y-27632) greatly inhibited endothelial apoptosis and preserved cell viability in TNF-α-induced human umbilical vein endothelial cells (HUVECs). Also vimentin phosphorylation and the remodeling of vimentin or phospho-vimentin induced by TNF-α were obviously attenuated by RhoA suppression and ROCK inhibition. TNF-α-mediated vimentin cleavage was significantly inhibited by RhoA suppression and ROCK inhibition through decreasing the activation of caspase3 and 8. Furthermore, TNF-α treatment greatly enhanced the activation of Raf-1. Suppression of Raf-1 or CK2 by its inhibitor (GW5074 or TBB) blocked vimentin phosphorylation, remodeling and endothelial apoptosis, and preserved cell viability in TNF-α-induced HUVECs. However, Raf-1 inhibition showed no significant effect on TNF-α-induced ROCK expression and activation, suggesting that the regulation of Raf-1/CK2 signaling on vimentin was independent of ROCK. Taken together, these results indicate that both RhoA/ROCK and Raf-1/CK2 pathway are responsible for TNF-α-mediated endothelial cytotoxicity via regulating vimentin cytoskeleton.

Correlation between Interleukin-6 and Thrombin-Antithrombin III Complex Levels in Retinal Diseases

PURPOSE

This study aims to evaluate and correlate the levels of interleukin-6 (IL-6) and thrombin-antithrombin III complex (TAT) in the vitreous of patients with different vitreoretinal pathologies.

METHODS

Vitreous samples were collected from 78 patients scheduled for pars plana vitrectomy at a tertiary medical center. Patients were divided by the underlying vitreoretinal pathophysiology, as follows: macular hole (MH)/epiretinal membrane (ERM) (n = 26); rhegmatogenous retinal detachment (RRD) (n = 32); and proliferative diabetic retinopathy (PDR) (n = 20). Levels of IL-6 and TAT were measured by enzyme-linked immunosorbent assay and compared among the groups.

RESULTS

A significant difference was found in the vitreal IL-6 and TAT levels between the MH/ERM group and both the PDR and RRD groups (P < 0.001 for all). Diabetes was associated with higher IL-6 levels in the RRD group. Different relationships between the IL-6 and TAT levels were revealed in patients with different ocular pathologies.

CONCLUSION

Our results imply that variations in vitreal TAT level may be attributable not only to an inflammatory reaction or blood-retinal barrier breakdown, but also to intraocular tissue-dependent regulation of thrombin.

The Role of IRE-XBP1 Pathway in Regulation of Retinal Pigment Epithelium Tight Junctions

Purpose

The retinal pigment epithelium (RPE) tight junctions play a pivotal role in maintaining the homeostatic environment of the neural retina. Herein, we investigated the role of X-box binding protein 1 (XBP1), an endoplasmic reticulum (ER) stress-responsive transcription factor, in regulation of RPE tight junctions.

Methods

Human RPE cell line (ARPE-19) and primary primate RPE cells were used for in vitro experiments and RPE-specific XBP1 knockout (KO) mice were used for in vivo study. Endoplasmic reticulum stress was induced by a sublethal dose of thapsigargin or tunicamycin. XBP1 activation was manipulated by IRE inhibitor 4μ8C, which suppresses XBP1 mRNA splicing. The integrity of tight junctions and the involvement of calcium-dependent RhoA/Rho kinase pathway were examined.

Results

Induction of ER stress by thapsigargin, but not tunicamycin, disrupted RPE tight junctions in ARPE-19 cells. Inhibition of XBP1 activation by 4μ8C resulted in a remarkable downregulation of tight junction proteins (ZO-1 and occludin) and defects in tight junction formation in the presence or absence of ER stress inducers. Overexpression of active XBP1 partially reversed 4μ8C-induced anomalies in tight junctions. Mechanistically, XBP1 inhibition resulted in increased intracellular Ca2+ concentration, upregulation of RhoA expression, redistribution of F-actin, and tight junction damage, which was attenuated by Rho kinase inhibitor Y27632. In vivo, deletion of XBP1 in the RPE resulted in defective RPE tight junctions accompanied by increased VEGF expression.

Conclusions

Taken together, these results suggest a protective role of XBP1 in maintaining RPE tight junctions possibly through regulation of calcium-dependent RhoA/Rho kinase signaling and actin cytoskeletal reorganization.

Involvement of Histamine and RhoA/ROCK in Penicillin Immediate Hypersensitivity Reactions

The mechanism of penicillin immediate hypersensitivity reactions has not been completely elucidated. These reactions are generally considered to be mediated by IgE, but penicillin-specific IgE could not be detected in most cases. This study demonstrated that penicillin was able to cause vascular hyperpermeability in a mouse model mimicking clinical symptoms of penicillin immediate hypersensitivity reactions. The first exposure to penicillin also induced immediate edema and exudative reactions in ears and lungs of mice in a dose-dependent manner. Vasodilation was noted in microvessels in ears. These reactions were unlikely to be immune-mediated reactions, because no penicillin-specific IgE was produced. Furthermore, penicillin treatment directly elicited rapid histamine release. Penicillin also led to F-actin reorganization in human umbilical vein endothelial cells and increased the permeability of the endothelial monolayer. Activation of the RhoA/ROCK signaling pathway was observed in ears and lungs of mice and in endothelial cells after treatment with penicillin. Both an anti-histamine agent and a ROCK inhibitor attenuated penicillin immediate hypersensitivity reactions in mice. This study presents a novel mechanism of penicillin immediate hypersensitivity reactions and suggests a potential preventive approach against these reactions.

Angiotensin II induces reorganization of the actin cytoskeleton and myosin light-chain phosphorylation in podocytes through rho/ROCK-signaling pathway

AIMS

In the present study, we have evaluated the effect of angiotensin II (Ang II) on actin cytoskeleton reorganization and myosin light-chain (MLC) phosphorylation in podocytes to demonstrate whether the Rho/Rho-associated coiled kinase (ROCK) pathway is involved podocyte injury.

METHODS

Eighteen male Sprague-Dawley rats were divided into three groups and treated with Ang II, saline or telmisartan. Morphological changes were studied at 28 days after treatment. Immunohistochemistry and Western blotting were used to determine the renal expression of p-MLC and ROCK2. Cultured podocytes were treated with Ang II (10(-7 )M) with or without Rho-kinase inhibitor (Y27632, 10(-6 )M) for variable time periods. F-actin was visualized with fluorescein isothiocyanate (FITC)-conjugated phalloidin or tetraethyl rhodamine isothiocyanate (TRITC)-conjugated phalloidin. p-MLC expression was evaluated by immunofluorescence and Western blot. The activation of Rho/ROCK was evaluated by Western blot.

RESULTS

The expression of p-MLC in glomeruli increased significantly in rats treated with Ang II when compared to the control rats as shown by Western blot (p < 0.05). In cultured podocytes, Rho A and ROCK2 increased after incubation with Ang II. Ang II increased the expression of ROCK2, which was accompanied with altered morphology, redistribution of actin and increased phosphorylation of MLC. The distribution of actin changed to a large extent, although overall quantitative differences were not observed. Addition of Y-27632 to podocytes treated with Ang II could ameliorate F-actin cytoskeleton remodeling and the increment in p-MLC expression.

CONCLUSION

Ang II-induced podocyte cytoskeleton protein expression changing through the RhoA/ROCK2 p-MLC/F-actin pathway.

Restoration of mesenchymal retinal pigmented epithelial cells by TGFβ pathway inhibitors: implications for age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of blindness. Most vision loss occurs following the transition from a disease of deposit formation and inflammation to a disease of neovascular fibrosis and/or cell death. Here, we investigate how repeated wound stimulus leads to seminal changes in gene expression and the onset of a perpetual state of stimulus-independent wound response in retinal pigmented epithelial (RPE) cells, a cell-type central to the etiology of AMD.

METHODS

Transcriptome wide expression profiles of human fetal RPE cell cultures as a function of passage and time post-plating were determined using Agilent 44 K whole genome microarrays and RNA-Seq. Using a systems level analysis, differentially expressed genes and pathways of interest were identified and their role in the establishment of a persistent mesenchymal state was assessed using pharmacological-based experiments.

RESULTS

Using a human fetal RPE cell culture model that considers monolayer disruption and subconfluent culture as a proxy for wound stimulus, we show that prolonged wound stimulus leads to terminal acquisition of a mesenchymal phenotype post-confluence and altered expression of more than 40 % of the transcriptome. In contrast, at subconfluence fewer than 5 % of expressed transcripts have two-fold or greater expression differences after repeated passage. Protein-protein and pathway interaction analysis of the genes with passage-dependent expression levels in subconfluent cultures reveals a 158-node interactome comprised of two interconnected modules with functions pertaining to wound response and cell division. Among the wound response genes are the TGFβ pathway activators: TGFB1, TGFB2, INHBA, INHBB, GDF6, CTGF, and THBS1. Significantly, inhibition of TGFBR1/ACVR1B mediated signaling using receptor kinase inhibitors both forestalls and largely reverses the passage-dependent loss of epithelial potential; thus extending the effective lifespan by at least four passages. Moreover, a disproportionate number of RPE wound response genes have altered expression in neovascular and geographic AMD, including key members of the TGFβ pathway.

CONCLUSIONS

In RPE cells the switch to a persistent mesenchymal state following prolonged wound stimulus is driven by lasting activation of the TGFβ pathway. Targeted inhibition of TGFβ signaling may be an effective approach towards retarding AMD progression and producing RPE cells in quantity for research and cell-based therapies.

Wogonin inhibits LPS-induced vascular permeability via suppressing MLCK/MLC pathway

Wogonin, a naturally occurring monoflavonoid extracted from the root of Scutellaria baicalensis Georgi, has been shown to have anti-inflammatory and anti-tumor activities and inhibits oxidant stress-induced vascular permeability. However, the influence of wogonin on vascular hyperpermeability induced by overabounded inflammatory factors often appears in inflammatory diseases and tumor is not well known. In this study, we evaluate the effects of wogonin on LPS induced vascular permeability in human umbilical vein endothelial cells (HUVECs) and investigate the underlying mechanisms. We find that wogonin suppresses the LPS-stimulated hyperactivity and cytoskeleton remodeling of HUVECs, promotes the expression of junctional proteins including VE-Cadherin, Claudin-5 and ZO-1, as well as inhibits the invasion of MDA-MB-231 across EC monolayer. Miles vascular permeability assay proves that wogonin can restrain the extravasated Evans in vivo. The mechanism studies reveal that the expressions of TLR4, p-PLC, p-MLCK and p-MLC are decreased by wogonin without changing the total steady state protein levels of PLC, MLCK and MLC. Moreover, wogonin can also inhibit KCl-activated MLCK/MLC pathway, and further affect vascular permeability. Significantly, compared with wortmannin, the inhibitor of MLCK/MLC pathway, wogonin exhibits similar inhibition effects on the expression of p-MLCK, p-MLC and LPS-induced vascular hyperpermeability. Taken together, wogonin can inhibit LPS-induced vascular permeability by suppressing the MLCK/MLC pathway, suggesting a therapeutic potential for the diseases associated with the development of both inflammatory and tumor.

Estrogen regulates Hippo signaling via GPER in breast cancer

The G protein-coupled estrogen receptor (GPER) mediates both the genomic and nongenomic effects of estrogen and has been implicated in breast cancer development. Here, we compared GPER expression in cancerous tissue and adjacent normal tissue in patients with invasive ductal carcinoma (IDC) of the breast and determined that GPER is highly upregulated in cancerous cells. Additionally, our studies revealed that GPER stimulation activates yes-associated protein 1 (YAP) and transcriptional coactivator with a PDZ-binding domain (TAZ), 2 homologous transcription coactivators and key effectors of the Hippo tumor suppressor pathway, via the Gαq-11, PLCβ/PKC, and Rho/ROCK signaling pathways. TAZ was required for GPER-induced gene transcription, breast cancer cell proliferation and migration, and tumor growth. Moreover, TAZ expression positively correlated with GPER expression in human IDC specimens. Together, our results suggest that the Hippo/YAP/TAZ pathway is a key downstream signaling branch of GPER and plays a critical role in breast tumorigenesis.

Different Effects of Thrombin on VEGF Secretion, Proliferation, and Permeability in Polarized and Non-polarized Retinal Pigment Epithelial Cells

We investigated the effect of thrombin on the secretion of vascular endothelial growth factor (VEGF), on cellular proliferation, and on the integrity of the barrier function of polarized retinal pigment epithelial (RPE) cells. In addition, we compared the responses of polarized to that of non-polarized RPE cells. Porcine polarized RPE cells were established using Transwell membranes. The polarization of the RPE cells was determined by their high transepithelial electrical resistance (TER > 200 Ω cm(2)) and by their differential secretion of VEGF (basal direction >apical direction by 2.5×). RPE cells were incubated with thrombin (5-20 U/ml) for 24 h. The concentration of VEGF in the culture medium was measured by enzyme-linked immunosorbent assay, and the TER was measured. Cellular proliferation was assessed by Ki-67 immunostaining. The area of laser-induced choroidal naovascularization (CNV) was measured in rat eyes and compare to that of controls with or without thrombin. Our results showed that thrombin significantly increased VEGF secretion both in polarized and non-polarized RPE cells in a dose-dependent way. Thrombin did not significantly affect the TER or the expression of tight-junctional proteins in polarized RPE cells, but decreased it in non-polarized RPE cells by inducing intercellular gaps. Ki-67-positive cells were observed in non-polarized RPE cells but not in polarized RPE cells as controls. After thrombin exposure, the number of Ki-67-positive cells increased significantly in non-polarized RPE cells but not in polarized RPE cells. The area of CNV was larger in thrombin-injected eye than control eyes. Although thrombin increased VEGF secretion regardless of cell polarity, its effects on proliferation and barrier integrity were dependent upon cell polarity. Cell polarization is an important factor for determining the response of RPE cells to thrombin, and the different responsive patterns to thrombin upon cell polarity might explain the complicated pathology of such diseases as age-related macular degeneration.

Low anticoagulant heparin blocks thrombin-induced endothelial permeability in a PAR-dependent manner

Acute lung injury and acute respiratory distress syndrome are accompanied by thrombin activation and fibrin deposition that enhance lung inflammation, activate endothelial cells and disrupt lung paracellular permeability. Heparin possesses anti-inflammatory properties but its clinical use is limited by hemorrhage and heparin induced thrombocytopenia. We studied the effects of heparin and low anticoagulant 2-O, 3-O desulfated heparin (ODSH) on thrombin-induced increases in paracellular permeability of cultured human pulmonary endothelial cells (ECs). Pretreatment with heparin or ODSH blocked thrombin-induced decrease in the EC transendothelial electrical resistance (TER), attenuated thrombin-stimulated paracellular gap formation and actin cytoskeletal rearrangement. Our data demonstrated that heparin and ODSH had inhibitory effects on thrombin-induced RhoA activation and intracellular calcium elevation. Thrombin-stimulated phosphorylation of the cytoskeletal regulatory proteins, myosin light chain and ezrin/radixin/moesin was also reduced. In these effects, low anticoagulant ODSH was more potent than heparin. Heparin or ODSH alone produced decreases in the EC TER that were abolished by siRNA-mediated depletion of the thrombin receptor, PAR-1. We also demonstrated that, in contrast to heparin, ODSH did not possess thrombin-binding activity. Results suggest that heparin and low anticoagulant ODSH can interfere with thrombin-activated signaling.

Regulation of paracellular permeability: factors and mechanisms

Epithelial permeability is composed of transcellular permeability and paracellular permeability. Paracellular permeability is controlled by tight junctions (TJs). Claudins and occludin are two major transmembrane proteins in TJs, which directly determine the paracellular permeability to different ions or large molecules. Intracellular signaling pathways including Rho/Rho-associated protein kinase, protein kinase Cs, and mitogen-activated protein kinase, modulate the TJ proteins to affect paracellular permeability in response for diverse stimuli. Cytokines, growth factors and hormones in organism can regulate the paracellular permeability via signaling pathway. The transcellular transporters such as Na-K-ATPase, Na(+)-coupled transporters and chloride channels, can interact with paracellular transport and regulate the TJs. In this review, we summarized the factors affecting paracellular permeability and new progressions of the related mechanism in recent studies, and pointed out further research areas.

Rap1 GTPase activation and barrier enhancement in rpe inhibits choroidal neovascularization in vivo

Loss of barrier integrity precedes the development of pathologies such as metastasis, inflammatory disorders, and blood-retinal barrier breakdown present in neovascular age-related macular degeneration. Rap1 GTPase is involved in regulating both endothelial and epithelial cell junctions; the specific role of Rap1A vs. Rap1B isoforms is less clear. Compromise of retinal pigment epithelium barrier function is a contributing factor to the development of AMD. We utilized shRNA of Rap1 isoforms in cultured human retinal pigment epithelial cells, along with knockout mouse models to test the role of Rap1 on promoting RPE barrier properties, with emphasis on the dynamic junctional regulation that is triggered when the adhesion between cells is challenged. In vitro, Rap1A shRNA reduced steady-state barrier integrity, whereas Rap1B shRNA affected dynamic junctional responses. In a laser-induced choroidal neovascularization (CNV) model of macular degeneration, Rap1b^−/− mice exhibited larger CNV volumes compared to wild-type or Rap1a^−/−. In vivo, intravitreal injection of a cAMP analog (8CPT-2′-O-Me-cAMP) that is a known Rap1 activator significantly reduced laser-induced CNV volume, which correlated with the inhibition of CEC transmigration across 8CPT-2′O-Me-cAMP-treated RPE monolayers in vitro. Rap1 activation by 8CPT-2′-O-Me-cAMP treatment increased recruitment of junctional proteins and F-actin to cell-cell contacts, increasing both the linearity of junctions in vitro and in cells surrounding laser-induced lesions in vivo. We conclude that in vitro, Rap1A may be important for steady state barrier integrity, while Rap1B is involved more in dynamic junctional responses such as resistance to junctional disassembly induced by EGTA and reassembly of cell junctions following disruption. Furthermore, activation of Rap1 in vivo inhibited development of choroidal neovascular lesions in a laser-injury model. Our data suggest that targeting Rap1 isoforms in vivo with 8CPT-2′-O-Me-cAMP may be a viable pharmacological means to strengthen the RPE barrier against the pathological choroidal endothelial cell invasion that occurs in macular degeneration.

TGF-β1 induces the dissolution of tight junctions in human renal proximal tubular cells: role of the RhoA/ROCK signaling pathway

The RhoA/ROCK signaling pathway plays a significant role in transforming growth factor (TGF)-β1-mediated epithelial-mesenchymal transition (EMT). It remains unclear, however, whether the RhoA/ROCK signaling pathway mediates TGF-β1-induced EMT by promoting the dissolution of tight junctions (TJs) in renal proximal tubular epithelial cells. In this study, we aimed to investigate the association between TGF-β1-mediated Rho/ROCK signaling and TJs in a cell line derived from human renal proximal tubular cells (HK-2 cells). HK-2 cells were treated with 5 ng/ml TGF-β1 for 0, 12, 24 and 48 h. Zona occludens protein 1 (also known as tight junction protein 1; ZO-1) and occludin mRNA and protein levels were determined by real-time PCR and western blot analysis, respectively. The HK-2 cells were then divided into three groups: a control group (serum-free culture medium for 24 h); a TGF-β1 group (treated with 5 ng/ml TGF-β1 for 24 h); and a TGF-β1 + Y-27632 (a specific ROCK inhibitor) group (pre-treated with 10 µM Y-27632 for 2 h and subsequently treated with 5 ng/ml TGF-β1 for 24 h). The levels of ZO-1 and occludin were detected by real-time PCR, western blot analysis and immunofluorescence. As shown by our results, the mRNA and protein levels of ZO-1 and occludin were decreased in the HK-2 cells following treatment with TGF-β1 in a time-dependent manner; in addition, ZO-1 and occludin levels in the TGF-β1 + Y-27632 group were significantly increased compared with those of the TGF-β1 group (P<0.05), with no significant changes compared with the control group. Our results indicate that the Rho/ROCK signaling pathway mediated by TGF-β1 plays a role in the dissolution of TJs during EMT.

Senescent fibroblasts enhance early skin carcinogenic events via a paracrine MMP-PAR-1 axis

The incidence of carcinoma increases greatly with aging, but the cellular and molecular mechanisms underlying this correlation are only partly known. It is established that senescent fibroblasts promote the malignant progression of already-transformed cells through secretion of inflammatory mediators. We investigated here whether the senescent fibroblast secretome might have an impact on the very first stages of carcinogenesis. We chose the cultured normal primary human epidermal keratinocyte model, because after these cells reach the senescence plateau, cells with transformed and tumorigenic properties systematically and spontaneously emerge from the plateau. In the presence of medium conditioned by autologous senescent dermal fibroblasts, a higher frequency of post-senescence emergence was observed and the post-senescence emergent cells showed enhanced migratory properties and a more marked epithelial-mesenchymal transition. Using pharmacological inhibitors, siRNAs, and blocking antibodies, we demonstrated that the MMP-1 and MMP-2 matrix metalloproteinases, known to participate in late stages of cancer invasion and metastasis, are responsible for this enhancement of early migratory capacity. We present evidence that MMPs act by activating the protease-activated receptor 1 (PAR-1), whose expression is specifically increased in post-senescence emergent keratinocytes. The physiopathological relevance of these results was tested by analyzing MMP activity and PAR-1 expression in skin sections. Both were higher in skin sections from aged subjects than in ones from young subjects. Altogether, our results suggest that during aging, the dermal and epidermal skin compartments might be activated coordinately for initiation of skin carcinoma, via a paracrine axis in which MMPs secreted by senescent fibroblasts promote very early epithelial-mesenchymal transition of keratinocytes undergoing transformation and oversynthesizing the MMP-activatable receptor PAR-1.

Coronin 1B regulates S1P-induced human lung endothelial cell chemotaxis: role of PLD2, protein kinase C and Rac1 signal transduction

Coronins are a highly conserved family of actin binding proteins that regulate actin-dependent processes such as cell motility and endocytosis. We found that treatment of human pulmonary artery endothelial cells (HPAECs) with the bioactive lipid, sphingosine-1-phosphate (S1P) rapidly stimulates coronin 1B translocation to lamellipodia at the cell leading edge, which is required for S1P-induced chemotaxis. Further, S1P-induced chemotaxis of HPAECs was attenuated by pretreatment with small interfering RNA (siRNA) targeting coronin 1B (∼36%), PLD2 (∼45%) or Rac1 (∼50%) compared to scrambled siRNA controls. Down regulation PLD2 expression by siRNA also attenuated S1P-induced coronin 1B translocation to the leading edge of the cell periphery while PLD1 silencing had no effect. Also, S1P-induced coronin 1B redistribution to cell periphery and chemotaxis was attenuated by inhibition of Rac1 and over-expression of dominant negative PKC δ, ε and ζ isoforms in HPAECs. These results demonstrate that S1P activation of PLD2, PKC and Rac1 is part of the signaling cascade that regulates coronin 1B translocation to the cell periphery and the ensuing cell chemotaxis.

Thrombin induces slug-mediated E-cadherin transcriptional repression and the parallel up-regulation of N-cadherin by a transcription-independent mechanism in RPE cells

The proliferation, directional migration to the vitreous and epithelial-mesenchymal transition (EMT) of quiescent, differentiated retinal pigment epithelium (RPE) cells is a major feature in the development of proliferative vitreoretinopathy (PVR) following exposure of the immuno-privileged eye niche to serum components, thrombin among them. We have previously documented thrombin induction of RPE cell proliferation and migration. We here analyzed the effect of thrombin on the E/N cadherin switch, a hallmark of EMT. Results show that thrombin induces the specific repression of epithelial E-cadherin gene transcription, alongside with the up-regulation of mesenchymal N-cadherin protein in RPE cells. We demonstrate, for the first time, that thrombin induces E-cadherin repression by stimulating snail-2 (SLUG) transcription factor expression, and the concomitant up-regulation of N-cadherin through the transcription-independent increase in protein translation promoted by PI3K/PKC-ζ/mTOR signaling. Our present findings suggest that the activation of protease-activated receptor-1 (PAR-1) by thrombin induces EMT of RPE cells, further supporting a central role for thrombin in PVR pathogenesis.

ERK1/2-dependent activation of mTOR/mTORC1/p70S6K regulates thrombin-induced RPE cell proliferation

Epithelial-mesenchymal transition (EMT), proliferation and migration of RPE cells characterize the development of proliferative vitreoretinopathy (PVR) and other fibro-proliferative eye diseases leading to blindness. A common event in these pathologies is the alteration of the BRB which allows the interaction of RPE cells with thrombin, a pro-inflammatory protease contained in serum. Thrombin promotion of cytoskeletal reorganization, proliferation, and migration has been reported in different cell types, although the molecular mechanisms involved in these processes remain poorly understood. Our previous work demonstrated that thrombin promotes RPE cell proliferation, cytoskeletal remodeling and migration, hallmark processes in the development of PVR. Thrombin induction of RPE cell proliferation requires PI3K, PDK1, and Akt/PKB (Akt) signaling leading to cyclin D1 gene expression. Since Akt functions as an upstream activator of mechanistic target of rapamycin complex 1 (mTORC1) and is also a downstream target for mTORC2, the aim of this work was to determine whether mTOR is involved in thrombin-induced RPE cell proliferation by regulating cyclin D1 expression in immortalized rat RPE-J cell line. Results demonstrate that thrombin-induced cyclin D1 expression and cell proliferation require Akt-independent phosphorylation/activation of mTOR at Ser 2448 mediated by PI3K/PKC-ζ/ERK1/2 signaling, concomitant to Akt-dependent activation of p70S6K carried by mTORC1.

Echovirus 30 induced neuronal cell death through TRIO-RhoA signaling activation

BACKGROUND

Echovirus 30 (Echo30) is one of the most frequently identified human enteroviruses (EVs) causing aseptic meningitis and encephalitis. However the mechanism underlying the pathogenesis of Echo30 infection with significant clinical outcomes is not completely understood. The aim of this investigation is to illustrate molecular pathologic alteration in neuronal cells induced by Echo30 infection using clinical isolate from young patient with neurologic involvement.

METHODOLOGY/PRINCIPAL FINDINGS

To characterize the neuronal cellular response to Echo30 infection, we performed a proteomic analysis based on two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF Mass Spectrophotometric (MS) analysis. We identified significant alteration of several protein expression levels in Echo30-infected SK-N-SH cells. Among these proteins, we focused on an outstanding up-regulation of Triple functional domain (TRIO) in Echo30-infected SK-N-SH cells. Generally, TRIO acts as a key component in the regulation of axon guidance and cell migration. In this study, we determined that TRIO plays a role in the novel pathways in Echo30 induced neuronal cell death.

CONCLUSIONS/SIGNIFICANCE

Our finding shows that TRIO plays a critical role in neuronal cell death by Echo30 infection. Echo30 infection activates TRIO-guanine nucleotide exchange factor (GEF) domains (GEFD2) and RhoA signaling in turn. These results suggest that Echo30 infection induced neuronal cell death by activation of the TRIO-RhoA signaling. We expect the regulation of TRIO-RhoA signaling may represent a new therapeutic approach in treating aseptic meningitis and encephalitis induced by Echo30.