The cytoskeletal protein ezrin regulates EC proliferation and angiogenesis via TNF-alpha-induced transcriptional repression of cyclin A

A comprehensive review of stroke-related signaling pathways and treatment in western medicine and traditional Chinese medicine

This review provides insight into the complex network of signaling pathways and mechanisms involved in stroke pathophysiology. It summarizes the historical progress of stroke-related signaling pathways, identifying potential interactions between them and emphasizing that stroke is a complex network disease. Of particular interest are the Hippo signaling pathway and ferroptosis signaling pathway, which remain understudied areas of research, and are therefore a focus of the review. The involvement of multiple signaling pathways, including Sonic Hedgehog (SHH), nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE), hypoxia-inducible factor-1α (HIF-1α), PI3K/AKT, JAK/STAT, and AMPK in pathophysiological mechanisms such as oxidative stress and apoptosis, highlights the complexity of stroke. The review also delves into the details of traditional Chinese medicine (TCM) therapies such as Rehmanniae and Astragalus, providing an analysis of the recent status of western medicine in the treatment of stroke and the advantages and disadvantages of TCM and western medicine in stroke treatment. The review proposes that since stroke is a network disease, TCM has the potential and advantages of a multi-target and multi-pathway mechanism of action in the treatment of stroke. Therefore, it is suggested that future research should explore more treasures of TCM and develop new therapies from the perspective of stroke as a network disease.

Immunohistochemical markers for equine granulosa cell tumors: a pilot study

Sex cord-stromal tumors (SCSTs), generally referred to as granulosa cell tumors (GCTs) or granulosa-theca cell tumors (GTCTs) in equids, show complex compositions and variable numbers of hormone-producing cells. These tumors can be difficult to diagnose, especially in early stages. Therefore, we tested a panel of antibodies for vimentin, smooth muscle actin, laminin, Ki-67, E-cadherin, calretinin, moesin, p-ezrin, AMH, and aromatase, markers used for tumor composition and classification, progression, and prognosis in human SCSTs, on an exemplary grapefruit-size equine GCT within the left ovary of a 13-year-old mare with stallion-like behavior and elevated testosterone levels in comparison with normal ovarian tissue. The tumor showed a low proliferation rate and prominent moesin and p-ezrin staining in granulosa cells. E-cadherin, calretinin, aromatase, and AMH are suggested to be potential markers for different cell components of equine SCSTs that can support tumor diagnosis and classification.

Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target

Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.

Calcitriol ameliorates damage in high-salt diet-induced hypertension: Evidence of communication with the gut-kidney axis

Several studies have established a link between high-salt diet, inflammation, and hypertension. Vitamin D supplementation has shown anti-inflammatory effects in many diseases; gut microbiota is also associated with a wide variety of cardiovascular diseases, but potential role of vitamin D and gut microbiota in high-salt diet-induced hypertension remains unclear. Therefore, we used rats with hypertension induced by a high-salt diet as the research object and analyzed the transcriptome of their tissues (kidney and colon) and gut microbiome to conduct an overall analysis of the gut-kidney axis. We aimed to confirm the effects of high salt and calcitriol on the gut-kidney immune system and the composition of the intestinal flora. We demonstrate that consumption of a high-salt diet results in hypertension and inflammation in the colon and kidney and alteration of gut microbiota composition and function. High-salt diet-induced hypertension was found to be associated with seven microbial taxa and mainly associated with reduced production of the protective short-chain fatty acid butyrate. Calcitriol can reduce colon and kidney inflammation, and there are gene expression changes consistent with restored intestinal barrier function. The protective effect of calcitriol may be mediated indirectly by immunological properties. Additionally, the molecular pathways of the gut microbiota-mediated blood pressure regulation may be related to circadian rhythm signals, which needs to be further investigated. An innovative association analysis of the microbiota may be a key strategy to understanding the association between gene patterns and host.

Cardiac Differentiation of Mesenchymal Stem Cells: Impact of Biological and Chemical Inducers

Cardiovascular disorders (CVDs) are the leading cause of global death, widely occurs due to irreparable loss of the functional cardiomyocytes. Stem cell-based therapeutic approaches, particularly the use of Mesenchymal Stem Cells (MSCs) is an emerging strategy to regenerate myocardium and thereby improving the cardiac function after myocardial infarction (MI). Most of the current approaches often employ the use of various biological and chemical factors as cues to trigger and modulate the differentiation of MSCs into the cardiac lineage. However, the recent advanced methods of using specific epigenetic modifiers and exosomes to manipulate the epigenome and molecular pathways of MSCs to modify the cardiac gene expression yield better profiled cardiomyocyte like cells in vitro. Hitherto, the role of cardiac specific inducers triggering cardiac differentiation at the cellular and molecular level is not well understood. Therefore, the current review highlights the impact and recent trends in employing biological and chemical inducers on cardiac differentiation of MSCs. Thereby, deciphering the interactions between the cellular microenvironment and the cardiac inducers will help us to understand cardiomyogenesis of MSCs. Additionally, the review also provides an insight on skeptical roles of the cell free biological factors and extracellular scaffold assisted mode for manipulation of native and transplanted stem cells towards translational cardiac research.

Proteoglycans regulate protein tyrosine phosphatase receptor σ organization on hematopoietic stem/progenitor cells

Protein tyrosine phosphatase receptor σ (PTPσ) is highly expressed by murine and human hematopoietic stem cells (HSCs) and negatively regulates HSC self-renewal and regeneration. Previous studies of the nervous system suggest that heparan sulfate proteoglycans can inactivate PTPσ by clustering PTPσ receptors on neurons, but this finding has yet to be visually verified with adequate resolution. Here, we sought to visualize and quantify how heparan sulfate proteoglycans regulate the organization and activation of PTPσ in hematopoietic stem/progenitor cells (HSPCs). Our study illustrates that syndecan-2 promotes PTPσ clustering, which sustains phospho-tyrosine and phospho-ezrin levels in association with augmentation of hematopoietic colony formation. Strategies that promote clustering of PTPσ on HSPCs may serve to powerfully augment hematopoietic function.

Spatially resolved cell polarity proteomics of a human epiblast model

Critical early steps in human embryonic development include polarization of the inner cell mass, followed by formation of an expanded lumen that will become the epiblast cavity. Recently described three-dimensional (3D) human pluripotent stem cell-derived cyst (hPSC-cyst) structures can replicate these processes. To gain mechanistic insights into the poorly understood machinery involved in epiblast cavity formation, we interrogated the proteomes of apical and basolateral membrane territories in 3D human hPSC-cysts. APEX2-based proximity bioinylation, followed by quantitative mass spectrometry, revealed a variety of proteins without previous annotation to specific membrane subdomains. Functional experiments validated the requirement for several apically enriched proteins in cyst morphogenesis. In particular, we found a key role for the AP-1 clathrin adaptor complex in expanding the apical membrane domains during lumen establishment. These findings highlight the robust power of this proximity labeling approach for discovering novel regulators of epithelial morphogenesis in 3D stem cell-based models.

Bidirectional Tumor-Promoting Activities of Macrophage Ezrin

Ezrin links the cytoskeleton to cell surface integrins and plasma membrane receptors, contributing to the proliferative and metastatic potential of cancer cells. Elevated ezrin expression in several cancers is associated with poor outcomes. Tumor cell ezrin expression and function have been investigated in depth; however, its role in macrophages and other tumor microenvironment cells remains unexplored. Macrophages profoundly influence tumorigenesis, and here we explore ezrin’s influence on tumor-promoting macrophage functions. Ezrin knockdown in THP-1 macrophages reveals its important contribution to adhesion to endothelial cells. Unexpectedly, ezrin is essential for the basal and breast cancer cell-stimulated THP-1 expression of ITGAM mRNA that encodes integrin CD11b, critical for cell adhesion. Ezrin skews the differentiation of THP-1 macrophages towards the pro-tumorigenic, M2 subtype, as shown by the reduced expression of FN1, IL10, and CCL22 mRNAs following ezrin knockdown. Additionally, macrophage ezrin contributes to the secretion of factors that stimulate tumor cell migration, invasion, and clonogenic growth. Lastly, THP-1 ezrin is critical for the expression of mRNAs encoding vascular endothelial growth factor (VEGF)-A and matrix metalloproteinase (MMP)-9, consistent with pro-tumorigenic function. Collectively, our results provide insight into ezrin’s role in tumorigenesis, revealing a bidirectional interaction between tumor-associated macrophages and tumor cells, and suggest myeloid cell ezrin as a target for therapeutic intervention against cancer.

Novel Applications of Mesenchymal Stem Cell-derived Exosomes for Myocardial Infarction Therapeutics

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally, representing approximately a third of all deaths every year. The greater part of these cases is represented by myocardial infarction (MI), or heart attack as it is better known, which occurs when declining blood flow to the heart causes injury to cardiac tissue. Mesenchymal stem cells (MSCs) are multipotent stem cells that represent a promising vector for cell therapies that aim to treat MI due to their potent regenerative effects. However, it remains unclear the extent to which MSC-based therapies are able to induce regeneration in the heart and even less clear the degree to which clinical outcomes could be improved. Exosomes, which are small extracellular vesicles (EVs) known to have implications in intracellular communication, derived from MSCs (MSC-Exos), have recently emerged as a novel cell-free vector that is capable of conferring cardio-protection and regeneration in target cardiac cells. In this review, we assess the current state of research of MSC-Exos in the context of MI. In particular, we place emphasis on the mechanisms of action by which MSC-Exos accomplish their therapeutic effects, along with commentary on the current difficulties faced with exosome research and the ongoing clinical applications of stem-cell derived exosomes in different medical contexts.

LOXL2 Upregulates Phosphorylation of Ezrin to Promote Cytoskeletal Reorganization and Tumor Cell Invasion

Lysyl oxidase-like 2 (LOXL2), a copper-dependent enzyme of the lysyl oxidase family and its nonsecreted, catalytically dead spliced isoform L2Δ13, enhance cell migration and invasion, stimulate filopodia formation, modulate the expression of cytoskeletal genes, and promote tumor development and metastasis in vivo. We previously showed that LOXL2 reorganizes the actin cytoskeleton in esophageal squamous cell carcinoma (ESCC) cells, however, the underlying molecular mechanisms were not identified. Here, using interactome analysis, we identified ezrin (EZR), fascin (FSCN1), heat shock protein beta-1 (HSPB1), and tropomodulin-3 (TMOD3) as actin-binding proteins that associate with cytoplasmic LOXL2, as well as with its L2Δ13 variant. High levels of LOXL2 and L2Δ13 and their cytoskeletal partners correlated with poor clinical outcome in patients with ESCC. To better understand the significance of these interactions, we focused on the interaction of LOXL2 with ezrin. Phosphorylation of ezrin at T567 was greatly reduced following depletion of LOXL2 and was enhanced following LOXL2/L2Δ13 reexpression. Furthermore, LOXL2 depletion inhibited the ability of ezrin to promote tumor progression. These results suggest that LOXL2-induced ezrin phosphorylation, which also requires PKCα, is critical for LOXL2-induced cytoskeletal reorganization that subsequently promotes tumor cell invasion and metastasis in ESCC. In summary, we have characterized a novel molecular mechanism that mediates, in part, the protumorigenic activity of LOXL2. These findings may enable the future development of therapeutic agents targeting cytoplasmic LOXL2. SIGNIFICANCE: LOXL2 and its spliced isoform L2Δ13 promote cytoskeletal reorganization and invasion of esophageal cancer cells by interacting with cytoplasmic actin-binding proteins such as ezrin.

Discovery of Ezrin Expression as a Potential Biomarker for Chemically Induced Ocular Irritation Using Human Corneal Epithelium Cell Line and a Reconstructed Human Cornea-like Epithelium Model

Numerous studies have attempted to develop a new in vitro eye irritation test (EIT). To obtain more reliable results from EIT, potential new biomarkers that reflect eye irritation by chemicals must be identified. We investigated candidate biomarkers for eye irritation, using a proteomics approach. Sodium lauryl sulfate (SLS) or benzalkonium chloride (BAC) was applied on a reconstructed human cornea-like epithelium model, MCTT HCE, and corneal protein expression was examined by two-dimensional gel electrophoresis. We found that ezrin (EZR) was significantly upregulated by SLS or BAC. In addition, upregulation of EZR in immortalized human corneal cells treated with SLS or BAC was confirmed by quantitative reverse transcription-PCR and western blot analysis. Furthermore, other well-known eye irritants such as cetylpyridinium bromide, Triton X-100, cyclohexanol, ethanol, 2-methyl-1-pentanol, and sodium hydroxide significantly increased EZR expression in immortalized human corneal cells. Induction of EZR promoter activity in irritant-treated human corneal cells was confirmed by a luciferase gene reporter assay. In conclusion, EZR expression may be a potential biomarker for detecting eye irritation, which may substantially improve the performance of in vitro EIT.

Perspectives for Ezrin and Radixin in Astrocytes: Kinases, Functions and Pathology

Astrocytes are increasingly perceived as active partners in physiological brain function and behaviour. The structural correlations of the glia–synaptic interaction are the peripheral astrocyte processes (PAPs), where ezrin and radixin, the two astrocytic members of the ezrin-radixin-moesin (ERM) family of proteins are preferentially localised. While the molecular mechanisms of ERM (in)activation appear universal, at least in mammalian cells, and have been studied in great detail, the actual ezrin and radixin kinases, phosphatases and binding partners appear cell type specific and may be multiplexed within a cell. In astrocytes, ezrin is involved in process motility, which can be stimulated by the neurotransmitter glutamate, through activation of the glial metabotropic glutamate receptors (mGluRs) 3 or 5. However, it has remained open how this mGluR stimulus is transduced to ezrin activation. Knowing upstream signals of ezrin activation, ezrin kinase(s), and membrane-bound binding partners of ezrin in astrocytes might open new approaches to the glial role in brain function. Ezrin has also been implicated in invasive behaviour of astrocytomas, and glial activation. Here, we review data pertaining to potential molecular interaction partners of ezrin in astrocytes, with a focus on PKC and GRK2, and in gliomas and other diseases, to stimulate further research on their potential roles in glia-synaptic physiology and pathology.

The interaction of lncRNA EZR-AS1 with SMYD3 maintains overexpression of EZR in ESCC cells

EZR, a member of the ezrin-radixin-moesin (ERM) family, is involved in multiple aspects of cell migration and cancer. SMYD3, a histone H3–lysine 4 (H3–K4)-specific methyltransferase, regulates EZR gene transcription, but the molecular mechanisms of epigenetic regulation remain ill-defined. Here, we show that antisense lncRNA EZR-AS1 was positively correlated with EZR expression in both human esophageal squamous cell carcinoma (ESCC) tissues and cell lines. Both in vivo and in vitro studies revealed that EZR-AS1 promoted cell migration through up-regulation of EZR expression. Mechanistically, antisense lncRNA EZR-AS1 formed a complex with RNA polymerase II to activate the transcription of EZR. Moreover, EZR-AS1 could recruit SMYD3 to a binding site, present in a GC-rich region downstream of the EZR promoter, causing the binding of SMYD3 and local enrichment of H3K4me3. Finally, the interaction of EZR-AS1 with SMYD3 further enhanced EZR transcription and expression. Our findings suggest that antisense lncRNA EZR-AS1, as a member of an RNA polymerase complex and through enhanced SMYD3-dependent H3K4 methylation, plays an important role in enhancing transcription of the EZR gene to promote the mobility and invasiveness of human cancer cells.

Rho-Associated Coiled-Coil Kinase (ROCK) in Molecular Regulation of Angiogenesis

Identified as a major downstream effector of the small GTPase RhoA, Rho-associated coiled-coil kinase (ROCK) is a versatile regulator of multiple cellular processes. Angiogenesis, the process of generating new capillaries from the pre-existing ones, is required for the development of various diseases such as cancer, diabetes and rheumatoid arthritis. Recently, ROCK has attracted attention for its crucial role in angiogenesis, making it a promising target for new therapeutic approaches. In this review, we summarize recent advances in understanding the role of ROCK signaling in regulating the permeability, migration, proliferation and tubulogenesis of endothelial cells (ECs), as well as its functions in non-ECs which constitute the pro-angiogenic microenvironment. The therapeutic potential of ROCK inhibitors in angiogenesis-related diseases is also discussed.

Role of the PDZ-scaffold protein NHERF1/EBP50 in cancer biology: from signaling regulation to clinical relevance

The transmission of cellular information requires fine and subtle regulation of proteins that need to interact in a coordinated and specific way to form efficient signaling networks. The spatial and temporal coordination relies on scaffold proteins. Thanks to protein interaction domains such as PDZ domains, scaffold proteins organize multiprotein complexes enabling the proper transmission of cellular information through intracellular networks. NHERF1/EBP50 is a PDZ-scaffold protein that was initially identified as an organizer and regulator of transporters and channels at the apical side of epithelia through actin-binding ezrin-moesin-radixin proteins. Since, NHERF1/EBP50 has emerged as a major regulator of cancer signaling network by assembling cancer-related proteins. The PDZ-scaffold EBP50 carries either anti-tumor or pro-tumor functions, two antinomic functions dictated by EBP50 expression or subcellular localization. The dual function of NHERF1/EBP50 encompasses the regulation of several major signaling pathways engaged in cancer, including the receptor tyrosine kinases PDGFR and EGFR, PI3K/PTEN/AKT and Wnt-β-catenin pathways.

Parallels between single cell migration and barrier formation: The case of RhoB and Rac1 trafficking

The appearance of multicellularity implied the adaptation of signaling networks required for unicellular life to new functions arising in this remarkable evolutionary transition. A hallmark of multicellular organisms is the formation of cellular barriers that compartmentalize spaces and functions. Here we discuss recent findings concerning the role of RhoB in the negative control of Rac1 trafficking from endosomes to the cell border, in order to induce membrane extensions to restore endothelial barrier function after acute contraction. This role closely resembles that proposed for RhoB in controlling single cell migration through Rac1, which has also been observed in cancer cell invasion. We highlight these similarities as a signaling paradigm that shows that endothelial barrier integrity is controlled not only by the formation of cell-cell junctions, but also by a balance between ancestral mechanisms of cell spreading and contraction conserved from unicellular organisms and orchestrated by Rho GTPases.

Restoration of Hydrogen Sulfide Production in Diabetic Mice Improves Reparative Function of Bone Marrow Cells

BACKGROUND

Bone marrow cell (BMC)-based treatment for critical limb ischemia in diabetic patients yielded a modest therapeutic effect resulting from cell dysfunction. Therefore, approaches that improve diabetic stem/progenitor cell functions may provide therapeutic benefits. Here, we tested the hypothesis that restoration of hydrogen sulfide (H₂S) production in diabetic BMCs improves their reparative capacities.

METHODS

Mouse BMCs were isolated by density-gradient centrifugation. Unilateral hind limb ischemia was conducted in 12- to 14-week-old db/+ and db/db mice by ligation of the left femoral artery. The H₂S level was measured by either gas chromatography or staining with florescent dye sulfidefluor 7 AM.

RESULTS

Both H₂S production and cystathionine γ-lyase (CSE), an H₂S enzyme, levels were significantly decreased in BMCs from diabetic db/db mice. Administration of H₂S donor diallyl trisulfide (DATS) or overexpression of CSE restored H₂S production and enhanced cell survival and migratory capacity in high glucose (HG)-treated BMCs. Immediately after hind limb ischemia surgery, the db/+ and db/db mice were administered DATS orally and/or given a local intramuscular injection of green fluorescent protein-labeled BMCs or red fluorescent protein-CSE-overexpressing BMCs (CSE-BMCs). Mice with hind limb ischemia were divided into 6 groups: db/+, db/db, db/db+BMCs, db/db+DATS, db/db+DATS+BMCs, and db/db+CSE-BMCs. DATS and CSE overexpression greatly enhanced diabetic BMC retention in ischemic hind limbs followed by improved blood perfusion, capillary/arteriole density, skeletal muscle architecture, and cell survival and decreased perivascular CD68⁺ cell infiltration in the ischemic hind limbs of diabetic mice. It is interesting to note that DATS or CSE overexpression rescued high glucose-impaired migration, tube formation, and survival of BMCs or mature human cardiac microvascular endothelial cells. Moreover, DATS restored nitric oxide production and decreased endothelial nitric oxide synthase phosphorylation at threonine 495 levels in human cardiac microvascular endothelial cells and improved BMC angiogenic activity under high glucose condition. Last, silencing CSE by siRNA significantly increased endothelial nitric oxide synthase phosphorylation at threonine 495 levels in human cardiac microvascular endothelial cells.

CONCLUSIONS

Decreased CSE-mediated H₂S bioavailability is an underlying source of BMC dysfunction in diabetes mellitus. Our data indicate that H₂S and overexpression of CSE in diabetic BMCs may rescue their dysfunction and open novel avenues for cell-based therapeutics of critical limb ischemia in diabetic patients.

Binding of nuclear factor κB to noncanonical consensus sites reveals its multimodal role during the early inflammatory response

Mammalian cells have developed intricate mechanisms to interpret, integrate, and respond to extracellular stimuli. For example, tumor necrosis factor (TNF) rapidly activates proinflammatory genes, but our understanding of how this occurs against the ongoing transcriptional program of the cell is far from complete. Here, we monitor the early phase of this cascade at high spatiotemporal resolution in TNF-stimulated human endothelial cells. NF-κB, the transcription factor complex driving the response, interferes with the regulatory machinery by binding active enhancers already in interaction with gene promoters. Notably, >50% of these enhancers do not encode canonical NF-κB binding motifs. Using a combination of genomics tools, we find that binding site selection plays a key role in NF-κΒ–mediated transcriptional activation and repression. We demonstrate the latter by describing the synergy between NF-κΒ and the corepressor JDP2. Finally, detailed analysis of a 2.8-Mbp locus using sub-kbp-resolution targeted chromatin conformation capture and genome editing uncovers how NF-κΒ that has just entered the nucleus exploits pre-existing chromatin looping to exert its multimodal role. This work highlights the involvement of topology in cis-regulatory element function during acute transcriptional responses, where primary DNA sequence and its higher-order structure constitute a regulatory context leading to either gene activation or repression.

IL-10 Accelerates Re-Endothelialization and Inhibits Post-Injury Intimal Hyperplasia following Carotid Artery Denudation

The role of inflammation on atherosclerosis and restenosis is well established. Restenosis is thought to be a complex response to injury, which includes early thrombus formation, acute inflammation and neo-intimal growth. Inflammatory cells are likely contributors in the host response to vascular injury, via cytokines and chemokines secretion, including TNF-alpha (TNF). We have previously shown that IL-10 inhibits TNF and other inflammatory mediators produced in response to cardiovascular injuries. The specific effect of IL-10 on endothelial cell (ECs) biology is not well elucidated. Here we report that in a mouse model of carotid denudation, IL-10 knock-out mice (IL-10KO) displayed significantly delayed Re-endothelialization and enhanced neo-intimal growth compared to their WT counterparts. Exogenous recombinant IL-10 treatment dramatically blunted the neo-intimal thickening while significantly accelerating the recovery of the injured endothelium in WT mice. In vitro, IL-10 inhibited negative effects of TNF on ECs proliferation, ECs cell cycle, ECs-monocyte adhesion and ECs apoptosis. Furthermore, IL-10 treatment attenuated TNF-induced smooth muscle cells proliferation. Our data suggest that IL-10 differentially regulate endothelial and vascular smooth cells proliferation and function and thus inhibits neo-intimal hyperplasia. Thus, these results may provide insights necessary to develop new therapeutic strategies to limit vascular restenosis during percutaneous coronary intervention (PCI) in the clinics.

In Vivo Effects of Mesenchymal Stromal Cells in Two Patients With Severe Acute Respiratory Distress Syndrome

Mesenchymal stromal cells (MSCs) have been investigated as a treatment for various inflammatory diseases because of their immunomodulatory and reparative properties. However, many basic questions concerning their mechanisms of action after systemic infusion remain unanswered. We performed a detailed analysis of the immunomodulatory properties and proteomic profile of MSCs systemically administered to two patients with severe refractory acute respiratory distress syndrome (ARDS) on a compassionate use basis and attempted to correlate these with in vivo anti-inflammatory actions. Both patients received 2×10(6) cells per kilogram, and each subsequently improved with resolution of respiratory, hemodynamic, and multiorgan failure. In parallel, a decrease was seen in multiple pulmonary and systemic markers of inflammation, including epithelial apoptosis, alveolar-capillary fluid leakage, and proinflammatory cytokines, microRNAs, and chemokines. In vitro studies of the MSCs demonstrated a broad anti-inflammatory capacity, including suppression of T-cell responses and induction of regulatory phenotypes in T cells, monocytes, and neutrophils. Some of these in vitro potency assessments correlated with, and were relevant to, the observed in vivo actions. These experiences highlight both the mechanistic information that can be gained from clinical experience and the value of correlating in vitro potency assessments with clinical effects. The findings also suggest, but do not prove, a beneficial effect of lung protective strategies using adoptively transferred MSCs in ARDS. Appropriate randomized clinical trials are required to further assess any potential clinical efficacy and investigate the effects on in vivo inflammation.

SIGNIFICANCE

This article describes the cases of two patients with severe refractory adult respiratory syndrome (ARDS) who failed to improve after both standard life support measures, including mechanical ventilation, and additional measures, including extracorporeal ventilation (i.e., in a heart-lung machine). Unlike acute forms of ARDS (such in the current NIH-sponsored study of mesenchymal stromal cells in ARDS), recovery does not generally occur in such patients.

Scaffolding during the cell cycle by A-kinase anchoring proteins

Cell division relies on coordinated regulation of the cell cycle. A process including a well-defined series of strictly regulated molecular mechanisms involving cyclin-dependent kinases, retinoblastoma protein, and polo-like kinases. Dysfunctions in cell cycle regulation are associated with disease such as cancer, diabetes, and neurodegeneration. Compartmentalization of cellular signaling is a common strategy used to ensure the accuracy and efficiency of cellular responses. Compartmentalization of intracellular signaling is maintained by scaffolding proteins, such as A-kinase anchoring proteins (AKAPs). AKAPs are characterized by their ability to anchor the regulatory subunits of protein kinase A (PKA), and thereby achieve guidance to different cellular locations via various targeting domains. Next to PKA, AKAPs also associate with several other signaling elements including receptors, ion channels, protein kinases, phosphatases, small GTPases, and phosphodiesterases. Taking the amount of possible AKAP signaling complexes and their diverse localization into account, it is rational to believe that such AKAP-based complexes regulate several critical cellular events of the cell cycle. In fact, several AKAPs are assigned as tumor suppressors due to their vital roles in cell cycle regulation. Here, we first briefly discuss the most important players of cell cycle progression. After that, we will review our recent knowledge of AKAPs linked to the regulation and progression of the cell cycle, with special focus on AKAP12, AKAP8, and Ezrin. At last, we will discuss this specific AKAP subset in relation to diseases with focus on a diverse subset of cancer.

12-O-Tetradecanoylphorbol-13-Acetate Induces Up-Regulated Transcription of Variant 1 but Not Variant 2 of VIL2 in Esophageal Squamous Cell Carcinoma Cells via ERK1/2/AP-1/Sp1 Signaling

The membrane-cytoskeleton link organizer ezrin may be the most "dramatic" tumor marker, being strongly over-expressed in nearly one-third of human malignancies. However, the molecular mechanisms of aberrant ezrin expression still need to be clarified. Ezrin, encoded by the VIL2 gene, has two transcript variants that differ in the transcriptional start site (TSS): V1 and V2. Both V1 and V2 encode the same protein. Here, we found that 12-O-tetradecanoylphorbol-13-acetate (TPA) induced over-expression of human VIL2 in esophageal squamous cell carcinoma (ESCC) cells. Furthermore, VIL2 V1 but not V2 was up-regulated after TPA stimulation in a time-dependent manner. AP-1 and Sp1 binding sites within the promoter region of VIL2 V1 acted not only as basal transcriptional elements but also as a composite TPA-responsive element (TRE) for the transcription of VIL2 V1. TPA stimulation enhanced c-Jun and Sp1 binding to the TRE via activation of the ERK1/2 pathway and increased protein levels of c-Jun, c-Fos, and Sp1, resulting in over-expression of VIL2 V1, whereas the MEK1/2 inhibitor U0126 blocked these events. Finally, we showed that TPA promoted the migration of ESCC cells whereas MEK1/2 inhibitor or ezrin silencing could partially inverse this alteration. Taken together, these results suggest that TPA is able to induce VIL2 V1 over-expression in ESCC cells by activating MEK/ERK1/2 signaling and increasing binding of Sp1 and c-Jun to the TRE of the VIL2 V1 promoter, and that VIL2 is an important TPA-induced effector.

Plasmodium vivax inhibits erythroid cell growth through altered phosphorylation of the cytoskeletal protein ezrin

BACKGROUND

The underlying causes of severe malarial anaemia are multifactorial. In previously reports, Plasmodium vivax was found to be able to directly inhibited erythroid cell proliferation and differentiation. The molecular mechanisms underlying the suppression of erythropoiesis by P. vivax are remarkably complex and remain unclear. In this study, a phosphoproteomic approach was performed to dissect the molecular mechanism of phosphoprotein regulation, which is involved in the inhibitory effect of parasites on erythroid cell development.

METHODS

This study describes the first comparative phosphoproteome analysis of growing erythroid cells (gECs), derived from human haematopoietic stem cells, exposed to lysates of infected erythrocytes (IE)/uninfected erythrocytes (UE) for 24, 48 and 72 h. This study utilized IMAC phosphoprotein isolation directly coupled with LC MS/MS analysis.

RESULTS

Lysed IE significantly inhibited gEC growth at 48 and 72 h and cell division resulting in the accumulation of cells in G0 phase. The relative levels of forty four phosphoproteins were determined from gECs exposed to IE/UE for 24-72 h and compared with the media control using the label-free quantitation technique. Interestingly, the levels of three phosphoproteins: ezrin, alpha actinin-1, and Rho kinase were significantly (p < 0.05) altered. These proteins display interactions and are involved in the regulation of the cellular cytoskeleton. Particularly affected was ezrin (phosphorylated at Thr567), which is normally localized to gEC cell extension peripheral processes. Following exposure to IE, for 48-72 h, the ezrin signal intensity was weak or absent. This result suggests that phospho-ezrin is important for actin cytoskeleton regulation during erythroid cell growth and division.

CONCLUSIONS

These findings suggest that parasite proteins are able to inhibit erythroid cell growth by down-regulation of ezrin phosphorylation, leading to ineffective erythropoiesis ultimately resulting in severe malarial anaemia. A better understanding of the mechanisms of ineffective erythropoiesis may be beneficial in the development of therapeutic strategies to prevent severe malarial anaemia.

Rho/Rho-associated coiled-coil forming kinase pathway as therapeutic targets for statins in atherosclerosis

SIGNIFICANCE

The 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors or statins are important therapeutic agents for lowering serum cholesterol levels. However, recent studies suggest that statins may exert atheroprotective effects beyond cholesterol lowering. These so-called "pleiotropic effects" include effects of statins on vascular and inflammatory cells. Thus, it is important to understand whether other signaling pathways that are involved in atherosclerosis could be targets of statins, and if so, whether individuals with "overactivity" of these pathways could benefit from statin therapy, regardless of serum cholesterol level.

RECENT ADVANCES

Statins inhibit the synthesis of isoprenoids, which are important for the function of the Rho/Rho-associated coiled-coil containing kinase (ROCK) pathway. Indeed, recent studies suggest that inhibition of the Rho/ROCK pathway by statins could lead to improved endothelial function and decreased vascular inflammation and atherosclerosis. Thus, the Rho/ROCK pathway has emerged as an important target of statin therapy for reducing atherosclerosis and possibly cardiovascular disease.

CRITICAL ISSUES

Because atherosclerosis is both a lipid and an inflammatory disease, it is important to understand how inhibition of Rho/ROCK pathway could contribute to statins' antiatherosclerotic effects.

FUTURE DIRECTIONS

The role of ROCKs (ROCK1 and ROCK2) in endothelial, smooth muscle, and inflammatory cells needs to be determined in the context of atherogenesis. This could lead to the development of specific ROCK1 or ROCK2 inhibitors, which could have greater therapeutic benefits with less toxicity. Also, clinical trials will need to be performed to determine whether inhibition of ROCKs, with and without statins, could lead to further reduction in atherosclerosis and cardiovascular disease.

Sphingolipid regulation of ezrin, radixin, and moesin proteins family: implications for cell dynamics

A key but poorly studied domain of sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive sphingolipids. This review describes the current understanding of sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.

Alcohol consumption negates estrogen-mediated myocardial repair in ovariectomized mice by inhibiting endothelial progenitor cell mobilization and function

We have shown previously that estrogen (estradiol, E2) supplementation enhances voluntary alcohol consumption in ovariectomized female rodents and that increased alcohol consumption impairs ischemic hind limb vascular repair. However, the effect of E2-induced alcohol consumption on post-infarct myocardial repair and on the phenotypic/functional properties of endothelial progenitor cells (EPCs) is not known. Additionally, the molecular signaling of alcohol-estrogen interactions remains to be elucidated. This study examined the effect of E2-induced increases in ethanol consumption on post-infarct myocardial function/repair. Ovariectomized female mice, implanted with 17β-E2 or placebo pellets were given access to alcohol for 6 weeks and subjected to acute myocardial infarction. Left ventricular functions were consistently depressed in mice consuming ethanol compared with those receiving only E2. Alcohol-consuming mice also displayed significantly increased infarct size and reduced capillary density. Ethanol consumption also reduced E2-induced mobilization and homing of EPCs to injured myocardium compared with the E2-alone group. In vitro, exposure of EPCs to ethanol suppressed E2-induced proliferation, survival, and migration and markedly altered E2-induced estrogen receptor-dependent cell survival signaling and gene expression. Furthermore, ethanol-mediated suppression of EPC biology was endothelial nitric oxide synthase-dependent because endothelial nitric oxide synthase-null mice displayed an exaggerated response to post-acute myocardial infarction left ventricular functions. These data suggest that E2 modulation of alcohol consumption, and the ensuing EPC dysfunction, may negatively compete with the beneficial effects of estrogen on post-infarct myocardial repair.

Immunohistochemical profile of ezrin and radixin in human liver epithelia during fetal development and pediatric cholestatic diseases

AIM

Ezrin and radixin are actin-binding proteins that contribute to the integrity of epithelia. Abnormalities of bile secretion occur primarily in cholestatic liver diseases and are associated with changes in cell cytoskeleton. Expression of these proteins during liver development and in cholestatic liver diseases remains poorly investigated.

METHODS

Ezrin and radixin expression was analyzed in fetal, adult and pediatric cholestatic human liver (i.e. biliary atresia, sclerosing cholangitis) by immunohistochemistry.

RESULTS

In adult and fetal livers, ezrin was expressed exclusively in the cells of the biliary lineage (i.e. biliary epithelial cells and ductal cells) whereas radixin was located not only in hepatocytes but also in cells of the biliary lineage. In the lobule of mature livers, radixin displayed a zonal distribution with predominant expression in the periportal region. In cholestatic diseases, both proteins were expressed in cells of the ductular reaction. An aberrant expression of ezrin was detected in hepatocytes of cirrhotic nodules with a CK7-positive pattern and in malignant hepatocytes in a course of cholestatic disease toward cancer.

CONCLUSIONS

Among the components of the liver epithelial cells, ezrin was exclusively expressed in biliary phenotype cells, while radixin was found in biliary and hepatocytic lineages, with a periportal zonal expression. In cholestatic diseases, ezrin was expressed in hepatocytes supporting the appearance of a biliary phenotype.

The therapeutic potential of mesenchymal stem cell-derived extracellular vesicles

Extracellular vesicles (EVs), membrane vesicles that are secreted by a variety of mammalian cell types, have been shown to play an important role in intercellular communication. The contents of EVs, including proteins, microRNAs, and mRNAs, vary according to the cell type that secreted them. Accordingly, researchers have demonstrated that EVs derived from various cell types play different roles in biological phenomena. Considering the ubiquitous presence of mesenchymal stem cells (MSCs) in the body, MSC-derived EVs may take part in a wide range of events. In particular, MSCs have recently attracted much attention due to the therapeutic effects of their secretory factors. MSC-derived EVs may therefore provide novel therapeutic approaches. In this review, we first summarize the wide range of functions of EVs released from different cell types, emphasizing that EVs echo the phenotype of their parent cell. Then, we describe the various therapeutic effects of MSCs and pay particular attention to the significance of their paracrine effect. We then survey recent reports on MSC-derived EVs and consider the therapeutic potential of MSC-derived EVs. Finally, we discuss remaining issues that must be addressed before realizing the practical application of MSC-derived EVs, and we provide some suggestions for enhancing their therapeutic efficiency.

MYADM controls endothelial barrier function through ERM-dependent regulation of ICAM-1 expression

The endothelium maintains a barrier between blood and tissue that becomes more permeable during inflammation. Membrane rafts are ordered assemblies of cholesterol, glycolipids, and proteins that modulate proinflammatory cell signaling and barrier function. In epithelial cells, the MAL family members MAL, MAL2, and myeloid-associated differentiation marker (MYADM) regulate the function and dynamics of ordered membrane domains. We analyzed the expression of these three proteins in human endothelial cells and found that only MYADM is expressed. MYADM was confined in ordered domains at the plasma membrane, where it partially colocalized with filamentous actin and cell-cell junctions. Small interfering RNA (siRNA)-mediated MYADM knockdown increased permeability, ICAM-1 expression, and leukocyte adhesion, all of which are features of an inflammatory response. Barrier function decrease in MYADM-silenced cells was dependent on ICAM-1 expression. Membrane domains and the underlying actin cytoskeleton can regulate each other and are connected by ezrin, radixin, and moesin (ERM) proteins. In endothelial cells, MYADM knockdown induced ERM activation. Triple-ERM knockdown partially inhibited ICAM-1 increase induced by MYADM siRNA. Importantly, ERM knockdown also reduced ICAM-1 expression in response to the proinflammatory cytokine tumor necrosis factor-α. MYADM therefore regulates the connection between the plasma membrane and the cortical cytoskeleton and so can control the endothelial inflammatory response.

Advanced glycation end-products induce calpain-mediated degradation of ezrin

Advanced glycation end-products (AGEs) are important mediators of diabetic complications via incompletely understood pathways. AGEs bind to intracellular ERM proteins (ezrin, radixin and moesin) that modulate cell shape, motility, adhesion and signal transduction. AGEs bind to the N-terminal domain of ezrin but not full-length ezrin. The AGE binding site may be made accessible either by proteolysis releasing an N-terminal fragment or ezrin activation by phosphorylation. Increased intracellular calcium is a primary event in cell activation by high glucose or AGEs. Calpain activity is increased concomitantly, and ezrin is a calpain substrate. The present study assessed whether glycated proteins affect ezrin cleavage and activation in renal tubule epithelial cells. After 7 days, AGE-BSA decreased ezrin levels in MDCK renal tubular cells to 66 ± 4% of control. AGE-RNAse, ribosylated fetal bovine serum and methylglyoxal-BSA all had similar effects. The AGE-BSA-induced decrease in ezrin was abolished by calpastatin peptide, a specific calpain inhibitor, and 1,2-bis-aminophenoxyethane-tetraacetic acid acetoxymethyl ester (BAPTA-AM), a calcium chelator. Ezrin breakdown products were increased in AGE-BSA-treated cells, with a main fragment of ∼ 43 kDa. In vitro, calpain 1 cleaved recombinant human ezrin, generating breakdown fragments including an N-terminal fragment of ∼ 43 kDa. Studies with ezrin mutants showed that non-phosphorylated ezrin was more susceptible to calpain cleavage. AGE-BSA decreased phosphorylated ERM levels to 31 ± 12% in MDCK cells. Thus, AGE-BSA promotes calpain-mediated proteolysis of ezrin in MDCK cells by both increasing calpain activity and reducing phosphorylation. Therapies targeting both glycated proteins and calpain may provide protection against diabetic complications.

Interleukin-10 treatment attenuates pressure overload-induced hypertrophic remodeling and improves heart function via signal transducers and activators of transcription 3-dependent inhibition of nuclear factor-κB

BACKGROUND

Inflammation plays a critical role in adverse cardiac remodeling and heart failure. Therefore, approaches geared toward inhibiting inflammation may provide therapeutic benefits. We tested the hypotheses that genetic deletion of interleukin-10 (IL-10), a potent antiinflammatory cytokine, exacerbates pressure overload-induced adverse cardiac remodeling and hypertrophy and that IL-10 therapy inhibits this pathology.

METHODS AND RESULTS

Cardiac hypertrophy was induced in wild-type and IL-10 knockout mice by isoproterenol (ISO) infusion. ISO-induced left ventricular dysfunction and hypertrophic remodeling, including fibrosis and fetal gene expression, were further exaggerated in knockout mice compared with wild-type mice. Systemic recombinant mouse IL-10 administration markedly improved left ventricular function and not only inhibited but also reversed ISO-induced cardiac remodeling. Intriguingly, a very similar cardioprotective response of IL-10 was found in transverse aortic constriction-induced hypertrophy and heart failure models. In neonatal rat ventricular myocytes and H9c2 myoblasts, ISO activated nuclear factor-κB and inhibited signal transducers and activators of transcription 3 (STAT3) phosphorylation. Interestingly, IL-10 suppressed ISO-induced nuclear factor-κB activation and attenuated STAT3 inhibition. Moreover, pharmacological and genetic inhibition of STAT3 reversed the protective effects of IL-10, whereas ectopic expression of constitutively active STAT3 mimicked the IL-10 responses on the ISO effects, confirming that the IL-10-mediated inhibition of nuclear factor-κB is STAT3 dependent.

CONCLUSION

Taken together, our results suggest IL-10 treatment as a potential therapeutic approach to limit the progression of pressure overload-induced adverse cardiac remodeling.

Proteomic analysis of microvesicles derived from human mesenchymal stem cells

Mesenchymal stem cells (MSCs) have emerged as a promising means for treating degenerative or incurable diseases. Recent studies have shown that microvesicles (MVs) from MSCs (MSC-MVs) contribute to recovery of damaged tissues in animal disease models. Here, we profiled the MSC-MV proteome to investigate their therapeutic effects. LC-MS/MS analysis of MSC-MVs identified 730 MV proteins. The MSC-MV proteome included five positive and two variable known markers of MSCs, but no negative marker, as well as 43 surface receptors and signaling molecules controlling self-renewal and differentiation of MSCs. Functional enrichment analysis showed that cellular processes represented by the MSC-MV proteins include cell proliferation, adhesion, migration, and morphogenesis. Integration of MSC's self-renewal and differentiation-related genes and the proteome of MSC-conditioned media (MSC-CM) with the MSC-MV proteome revealed potential MV protein candidates that can be associated with the therapeutic effects of MSC-MVs: (1) surface receptors (PDGFRB, EGFR, and PLAUR); (2) signaling molecules (RRAS/NRAS, MAPK1, GNA13/GNG12, CDC42, and VAV2); (3) cell adhesion (FN1, EZR, IQGAP1, CD47, integrins, and LGALS1/LGALS3); and (4) MSC-associated antigens (CD9, CD63, CD81, CD109, CD151, CD248, and CD276). Therefore, the MSC-MV proteome provides a comprehensive basis for understanding the potential of MSC-MVs to affect tissue repair and regeneration.

Improvement of cardiac function in mouse myocardial infarction after transplantation of epigenetically-modified bone marrow progenitor cells

Objective

To study usefulness of bone marrow progenitor cells (BPCs) epigenetically altered by chromatin modifying agents in mediating heart repair after myocardial infarction in mice.

Methods and Results

We tested the therapeutic efficacy of bone marrow progenitor cells treated with the clinically-used chromatin modifying agents Trichostatin A (TSA, histone deacetylase inhibitor) and 5Aza-2-deoxycytidine (Aza, DNA methylation inhibitor) in a mouse model of acute myocardial infarction (AMI). Treatment of BPCs with Aza and TSA induced expression of pluripotent genes Oct4, Nanog, Sox2, and thereafter culturing these cells in defined cardiac myocyte-conditioned medium resulted in their differentiation into cardiomyocyte progenitors and subsequently into cardiac myocytes. Their transition was deduced by expression of repertoire of markers: Nkx2.5, GATA4, cardiotroponin T, cardiotroponin I, α-sarcomeric actinin, Mef2c and MHC-α. We observed that the modified BPCs had greater AceH3K9 expression and reduced histone deacetylase1 (HDAC1) and lysine-specific demethylase1 (LSD1) expression compared to untreated BPCs, characteristic of epigenetic changes. Intra-myocardial injection of modified BPCs after AMI in mice significantly improved left ventricular function. These changes were ascribed to differentiation of the injected cells into cardiomyocytes and endothelial cells.

Conclusion

Treatment of BPCs with Aza and TSA converts BPCs into multipotent cells, which can then be differentiated into myocyte progenitors. Transplantation of these modified progenitor cells into infarcted mouse hearts improved left ventricular function secondary to differentiation of cells in the niche into myocytes and endothelial cells.

Potential transcriptional regulatory regions exist upstream of the human ezrin gene promoter in esophageal carcinoma cells

We previously demonstrated that the region -87/+134 of the human ezrin gene (VIL2) exhibited promoter activity in human esophageal carcinoma EC109 cells, and a further upstream region -1324/-890 positively regulated transcription. In this study, to identify the transcriptional regulatory regions upstream of the VIL2 promoter, we cloned VIL2 -1541/-706 segment containing the -1324/-890, and investigated its transcriptional regulatory properties via luciferase assays in transiently transfected cells. In EC109 cells, it was found that VIL2 -1541/-706 possessed promoter and enhancer activities. We also localized transcriptional regulatory regions by fusing 5'- or 3'-deletion segments of VIL2 -1541/-706 to a luciferase reporter. We found that there were three positive and one negative transcriptional regulatory regions within VIL2 -1541/-706 in EC109 cells. When these regions were separately located upstream of the luciferase gene without promoter, or located upstream of the VIL2 promoter or SV40 promoter directing the luciferase gene, only VIL2 -1297/-1186 exhibited considerable promoter and enhancer activities, which were lower than those of -1541/-706. In addition, transient expression of Sp1 increased ezrin expression and the transcriptional activation of VIL2 -1297/-1186. Other three regions, although exhibiting significantly positive or negative transcriptional regulation in deletion experiments, showed a weaker or absent regulation. These data suggested that more than one region upstream of the VIL2 promoter participated in VIL2 transcription, and the VIL2 -1297/-1186, probably as a key transcriptional regulatory region, regulated VIL2 transcription in company with other potential regulatory regions.

Increased phosphorylation of ezrin/radixin/moesin proteins contributes to proliferation of rheumatoid fibroblast-like synoviocytes

OBJECTIVES

Increasing evidence indicates that ezrin/radixin/moesin (ERM) proteins may play a critical role in cell proliferation. This study examined the role of ERM proteins in proliferation of fibroblast-like synoviocytes (FLS) from patients with RA.

METHODS

Synovial tissues (STs) were obtained from 18 RA and 6 OA patients. The expression of ERM and its phosphorylated proteins in cultured FLS and ST was assessed by western blots or IF staining. Small interference RNA (siRNA)-mediated ERM knockdown was used to inhibit phosphorylation of ERM. Proliferation of FLS was measured by bromodeoxyuridine (BrdU) incorporation into cell DNA and by PCNA immunoblotting.

RESULTS

Our study showed that increased phosphorylation of ERM proteins was found in ST and FLS from patients with RA as compared with OA patients and non-arthritis controls. Treatment with TNF-α, IL-1β or PDGF-induced phosphorylation of ERM proteins in dose- and time-dependent manner by RA FLS, but did not affect the expression of total ERM protein. Rho kinase and p38MAPK signal pathways were involved in TNF-α-induced ERM phosphorylation. We further showed that inhibition of ERM phosphorylation by siRNA-mediated ERM knockdown suppressed TNF-α- or IL-1β-induced BrdU incorporation and PCNA expression in RA FLS.

CONCLUSIONS

This study provides the novel evidence that increased phosphorylation of ERM proteins may contribute to proliferation of RA FLS, suggesting that specific inhibition of ERM phosphorylation may be a new therapeutic approach for RA.

Rho-associated coiled-coil-forming kinases (ROCKs): potential targets for the treatment of atherosclerosis and vascular disease

ROCKs are important regulators of the actin cytoskeleton. Because changes in the actin cytoskeleton underlie vascular contractility and remodeling, inflammatory cell recruitment, and cell proliferation, it is likely that the Rho/ROCK pathway will play a central role in mediating vascular function. Indeed, increased ROCK activity is observed in cerebral and coronary vasospasm, hypertension, vascular inflammation, arteriosclerosis, and atherosclerosis. Recent experimental and clinical studies suggest that inhibition of ROCK could be a promising target for the treatment of cardiovascular disease. For example, inhibition of ROCK might be the underlying mechanism by which statins or HMG-CoA reductase inhibitors exert their therapeutic benefits beyond cholesterol reduction. In this review we summarize current understanding of the crucial role of RhoA/ROCK pathway in the regulation of vascular function and discuss its therapeutic potential in the treatment of atherosclerosis and vascular disease.

Sonic hedgehog induces angiogenesis via Rho kinase-dependent signaling in endothelial cells

The morphogen Sonic hedgehog (Shh) promotes neovascularization in adults by inducing pro-angiogenic cytokine expression in fibroblasts; however, the direct effects of Shh on endothelial cell (EC) function during angiogenesis are unknown. Our findings indicate that Shh promotes capillary morphogenesis (tube length on Matrigel increased to 271+/-50% of the length in untreated cells, p=0.00003), induces EC migration (modified Boyden chamber assay, 191+/-35% of migration in untreated cells, p=0.00009), and increases EC expression of matrix metalloproteinase 9 (MMP-9) and osteopontin (OPN) mRNA (real-time RT-PCR), which are essential for Shh-induced angiogenesis both in vitro and in vivo. Shh activity in ECs is mediated by Rho, rather than through the "classic" Shh signaling pathway, which involves the Gli transcription factors. The Rho dependence of Shh-induced EC angiogenic activity was documented both in vitro, with dominant-negative RhoA and Rho kinase (ROCK) constructs, and in vivo, with the ROCK inhibitor Y27632 in the mouse corneal angiogenesis model. Finally, experiments performed in MMP-9- and OPN-knockout mice confirmed the roles of the ROCK downstream targets MMP-9 and OPN in Shh-induced angiogenesis. Collectively, our results identify a "nonclassical" pathway by which Shh directly modulates EC phenotype and angiogenic activity.

Aberrant localization of ezrin correlates with salivary acini disorganization in Sjogren's Syndrome

OBJECTIVES

To analyse whether the alterations in the structure and organization of microvilli in salivary acinar cells from SS patients are linked to changes in the expression and/or cellular localization of ezrin.

METHODS

Salivary gland (SG) acini from controls and SS patients were used to evaluate ezrin expression by western blot and localization of total and activated (phospho-Thr567) ezrin by IF and EM.

RESULTS

In acini from control labial SGs, ezrin was located predominantly at the apical pole and to a lesser extent at the basal region of these cells. Conversely, in acini extracts from SS patients, ezrin showed significantly elevated levels, which were accompanied with localization mostly at the basal region. Moreover, F-actin maintained its distribution in both the apical region and basolateral cortex; however, it was also observed in the acinar cytoplasm. Phospho-ezrin (active form) was located exclusively at the apical pole of acinar cells from control subjects and abundantly located at the basal cytoplasm in SS samples. These results were confirmed by immunogold studies.

CONCLUSIONS

The decrease of ezrin and phospho-ezrin at the apical pole and the cytoplasmic redistribution of F-actin suggest an altered interaction between the F-actin-cytoskeleton and plasma membrane in SS patient acini, which may explain the microvilli disorganization. These alterations could eventually contribute to SG hyposecretion in SS patients.

Direct bone formation during distraction osteogenesis does not require TNFalpha receptors and elevated serum TNFalpha fails to inhibit bone formation in TNFR1 deficient mice

Distraction osteogenesis (DO) is a process which induces direct new bone formation as a result of mechanical distraction. Tumor necrosis factor-alpha (TNF) is a cytokine that can modulate osteoblastogenesis. The direct effects of TNF on direct bone formation in rodents are hypothetically mediated through TNF receptor 1 and/or 2 (TNFR1/2) signaling. We utilized a unique model of mouse DO to assess the effects of 1) TNFR homozygous null gene alterations on direct bone formation and 2) rmTNF on wild type (WT), TNFR1(-/-) (R1KO), and TNR2(-/-) (R2KO) mice. Radiological and histological analyses of direct bone formation in the distraction gaps demonstrated no significant differences between the WT, R1KO, R2KO, or TNFR1(-/-) and R2(-/-) (R1 and 2KO) mice. R1 and 2KO mice had elevated levels of serum TNF but demonstrated no inhibition of new bone formation. Systemic administration by osmotic pump of rmTNF during DO (10 microg/kg/day) resulted in significant inhibition of gap bone formation measures in WT and R2KO mice, but not in R1KO mice. We conclude that exogenous rmTNF and/or endogenous TNF act to inhibit new bone formation during DO by signaling primarily through TNFR1.

Restoration of regenerative osteoblastogenesis in aged mice: modulation of TNF

Skeletal changes accompanying aging are associated with both increased risk of fractures and impaired fracture healing, which, in turn, is due to compromised bone regeneration potential. These changes are associated with increased serum levels of selected proinflammatory cytokines, e.g., tumor necrosis factor alpha (TNF-alpha). We have used a unique model of bone regeneration to demonstrate (1) that aged-related deficits in direct bone formation can be restored to young mice by treatment with TNF blockers and (2) that the cyclin-dependent kinase inhibitor p21 is a candidate for mediation of the osteoinhibitory effects of TNF. It has been hypothesized recently that TNF antagonists may represent novel anabolic agents, and we believe that the data presented here represent a successful test of this hypothesis.

The Janus-faced role of ezrin in "linking" cells to either normal or metastatic phenotype

In the majority of eukaryotic cells, the ezrin, radixin and moesin (ERM) proteins are involved in many physiologic functions including regulation of actin cytoskeleton, control of cell shape, adhesion, motility and modulation of signal transduction pathways. In a previous study, we used a dominant negative ezrin-mutant to address ezrin involvement in remodeling of actin cytoskeleton and subsequently we depicted ezrin key role in melanoma cell migration and progression. Herein, we highlight recent advances on ezrin involvement in the metastatic phenomenon, including also some more neglected ezrin-related functions. Novel molecular processes driven by ezrin activation include: phagocytosis, acquisition of resistance to chemotherapeutics and triggering of programmed cell death signals. Recent data support an integrated role of ezrin also in development of tumor malignancy. On one hand, ezrin may be responsible of deranged execution of specific known functions such as adhesion and motility and on the other, it may also participate to unique metastatic determinants, through the establishment of aberrant linkages with tumor-related proteins. For instance, ezrin misslocalization, absence or deranged activity has started to be correlated with tumor progression in many tumors of different species, including humans. Concomitantly, ezrin may act simultaneously as a regulatory or deregulatory chaperon in both normal and tumor cells. It is still to be established whether this Janus-faced feature of ezrin is due to some unknown transforming Zelig-like property or to the fact that a tumor-associated molecule preferentially links to ezrin thus distracting it from its normal connections. However, the contribution of ezrin functional deregulation to the acquisition of the metastatic phenotype appears clear and ezrin or ezrin aberrant associations may represent good candidates for future anti-tumor therapies.

PI3K, Rho, and ROCK play a key role in hypoxia-induced ATP release and ATP-stimulated angiogenic responses in pulmonary artery vasa vasorum endothelial cells

We recently reported that vasa vasorum expansion occurs in the pulmonary artery (PA) adventitia of chronically hypoxic animals and that extracellular ATP is a pro-angiogenic factor for isolated vasa vasorum endothelial cells (VVEC). However, the sources of extracellular ATP in the PA vascular wall, as well as the molecular mechanisms underlying its release, remain elusive. Studies were undertaken to explore whether VVEC release ATP in response to hypoxia and to determine signaling pathways involved in this process. We found that hypoxia (1-3% O2) resulted in time- and O2-dependent ATP release from VVEC. Preincubation with the inhibitors of vesicular transport (monensin, brefeldin A, and N-ethylmaleimide) significantly decreased ATP accumulation in the VVEC conditioned media, suggesting that hypoxia-induced ATP release occurs through vesicular exocytosis. Additionally, both hypoxia and exogenously added ATP resulted in the activation of PI3K and accumulation of GTP-bound RhoA in a time-dependent manner. Pharmacological inhibition of PI3K and ROCK or knockout of RhoA by small interfering RNA significantly abolished hypoxia-induced ATP release from VVEC. Moreover, RhoA and ROCK play a critical role in ATP-induced increases in VVEC DNA synthesis, migration, and tube formation, indicating a functional contribution of PI3K, Rho, and ROCK to both the autocrine mechanism of ATP release and ATP-mediated angiogenic activation of VVEC. Taken together, our findings provide novel evidence for the signaling mechanisms that link hypoxia-induced increases in extracellular ATP and vasa vasorum expansion.

Pleiotropic function of ezrin in human metastatic melanomas

The membrane cytoskeleton cross-linker, ezrin, has recently been depicted as a key regulator in the progression and metastasis of several pediatric tumors. Less defined appears the role of ezrin in human adult tumors, especially melanoma. We therefore addressed ezrin involvement in the metastatic phenotype of human adult metastatic melanoma cells. Our results show that cells resected from melanoma metastatic lesions of patients, display marked metastatic spreading capacity in SCID mice organs. Stable transfection of human melanoma cells with an ezrin deletion mutant comprising only 146 N-terminal aminoacids led to the abolishment of metastatic dissemination. In vitro experiments revealed ezrin direct molecular interactions with molecules related to metastatic functions such as CD44, merlin and Lamp-1, consistent with its participation to the formation of phagocitic vacuoles, vesicular sorting and migration capacities of melanoma cells. Moreover, the ezrin fragment capable of binding to CD44 was shorter than that previously reported, and transfection with the ezrin deletion mutant abrogated plasma membrane Lamp-1 recruitment. This study highlights key involvement of ezrin in a complex machinery, which allows metastatic cancer cells to migrate, invade and survive in very unfavorable conditions. Our in vivo and in vitro data reveal that ezrin is the hub of the metastatic behavior also in human adult tumors.

Roles of ezrin in the growth and invasiveness of esophageal squamous carcinoma cells

Ezrin, which crosslinks the cytoskeleton and plasma membrane, is involved in the growth and metastatic potential of cancer cells. Ezrin expression in esophageal squamous cell carcinoma (ESCC) was described recently, but its roles and the underlying mechanism(s) remain unclear. In our study, we first showed that ezrin in ESCC cell is expressed in the nucleus as well as in the cytoplasm and plasma membrane. Then, by using RNAi, we revealed that interference of ezrin expression suppressed the growth, adhesion and invasiveness of ESCC cells. Tumorigenesis experiments revealed that ezrin may directly regulate tumor formation in vivo. To explore the molecular mechanisms through which ezrin contributes to the proliferation and invasiveness of ESCC cells, we used cDNA microarrays to analyze ezrin knockdown cells and the control cells; of 39,000 genes examined, 297 were differentially expressed upon ezrin knockdown, including some proliferation- and invasiveness-related genes such as ATF3, CTGF and CYR61. Furthermore, pathway analysis showed that ezrin knockdown led to decreased activation of the TGF-beta and MAPK pathways, and ezrin-mediated cell invasiveness alteration was dependent on the activation of these pathways. Finally, immunohistochemical staining on 80 ESCC specimens and 50 normal esophageal mucosae revealed that the expression levels of 3 altered genes involved in the regulation of cell proliferation and tumor metastasis, including CTGF, CYR61 and ATF3, were altered in ESCCs, and their expression pattern correlated with ezrin expression. Taken together, we propose that ezrin might function in the growth and invasiveness of ESCC cells through the MAPK and TGF-beta pathways.

Sp1 and AP-1 regulate expression of the human gene VIL2 in esophageal carcinoma cells

Ezrin, encoded by VIL2, is a membrane-cytoskeletal linker protein that has been suggested to be involved in tumorigenesis. Ezrin expression in esophageal squamous cell carcinoma (ESCC) was described recently, but its clinical significance and the molecular mechanism underlying its regulated expression remain unclear. Thus, we retrospectively evaluated ezrin expression by immunohistochemistry in a tissue microarray representing 193 ESCCs. Ezrin overexpression in 90 of 193 tumors (46.6%) was associated with poor survival (p = 0.048). We then explored the mechanism by which ezrin expression is controlled in ESCC by assessing the transcriptional regulatory regions of human VIL2 by fusing deletions or site-directed mutants of the 5'-flanking region of the gene to a luciferase reporter. We found that the region -87/-32 containing consensus Sp1 (-75/-69) and AP-1 (-64/-58) binding sites is crucial for VIL2 promoter activity in esophageal carcinoma cells (EC109) derived from ESCC. AP-1 is comprised of c-Jun and c-Fos. Electrophoretic mobility shift and chromatin immunoprecipitation experiments demonstrated that Sp1 and c-Jun bound specifically to their respective binding sites within the VIL2 promoter. In addition, transient expression of Sp1, c-Jun, or c-Fos increased ezrin expression and VIL2 promoter activity. Use of selective inhibitors revealed that VIL2 transactivation required the MEK1/2 signal transduction pathway but not JNK or p38 MAPK. Taken together, we propose a possible signal transduction pathway whereby MEK1/2 phosphorylates ERK1/2, which phosphorylates Sp1 and AP-1 that in turn bind to their respective binding sites to regulate the expression of human VIL2 in ESCC cells.

An ezrin/calpain/PI3K/AMPK/eNOSs1179 signaling cascade mediating VEGF-dependent endothelial nitric oxide production

Calpain was recently reported to mediate vascular endothelial growth factor (VEGF)-induced angiogenesis. In the present study, we investigated detailed molecular mechanisms. VEGF (100 ng/mL) induced a marked increase in endothelial cell production of NO(*), specifically detected by electron spin resonance. This response was abolished by inhibition of calpain with N-acetyl-leucyl-leucyl-norleucinal (ALLN) or Calpeptin. Both also diminished membrane-specific calpain activation by VEGF, which was intriguingly attenuated by silencing ezrin with RNA interference. A rapid membrane colocalization of calpain and ezrin occurred as short as 10 minutes after VEGF stimulation. AKT, AMP-dependent kinase (AMPK), and endothelial nitric oxide synthase (eNOS)(s1179) phosphorylations in VEGF-stimulated endothelial cells were markedly enhanced, which were however significantly attenuated by either ALLN, Calpeptin, or ezrin small interfering RNA, as well as by Wortmannin or compound C (respectively for phosphatidylinositol 3-kinase [PI3K] or AMPK). The latter 3 also abolished VEGF induction of NO(*). These data indicate that AMPK and AKT are both downstream of PI3K and that AKT activation is partially dependent on AMPK. The interrelationship between AMPK and AKT, although known to be individually important in mediating VEGF activation of eNOS, is clearly characterized. Furthermore, AMPK/AKT/eNOS(s1179) was found downstream of a calpain/ezrin membrane interaction. These data no doubt provide new insights into the long mystified signaling gap between VEGF receptors and PI3K/AKT or AMPK-dependent eNOS activation. In view of the well-established significance of VEGF-dependent angiogenesis, these findings might have broad and important implications in cardiovascular pathophysiology.

Tumor necrosis factor-alpha downregulates endothelial nitric oxide synthase mRNA stability via translation elongation factor 1-alpha 1

Endothelium-derived nitric oxide (NO) is an important regulator of vascular function. NO is produced by endothelial NO synthase (eNOS), whose expression is downregulated by tumor necrosis factor (TNF)-alpha at the posttranscriptional level. To elucidate the molecular basis of TNF-alpha-mediated eNOS mRNA instability, eNOS 3' untranslated region (3'-UTR) binding proteins were purified by RNA affinity chromatography from cytosolic fractions of TNF-alpha-stimulated human umbilical vein endothelial cells (HUVECs). The formation of 3'-UTR ribonucleoprotein complexes, with molecular weight of 52 and 57 kDa, was increased by TNF-alpha. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of the 52-kDa protein identified 3 peptides that comprise the peptide sequence of translation elongation factor 1-alpha 1 (eEF1A1). In HUVECs, TNF-alpha rapidly increased eEF1A1 expression, which is maximal after 1 hour and persists for up to 48 hours. RNA gel mobility-shift and UV cross-linking assays indicated that recombinant glutathione S-transferase-eEF1A1 fusion protein specifically binds to a UC-rich sequence in the 3'-UTR of eNOS mRNA. In addition, the domain III of eEF1A1 mediates the binding of eNOS 3'-UTR in eEF1A1. Overexpression of eEF1A1 markedly attenuated the expression of eNOS and luciferase gene fused with eNOS 3'-UTR in both COS-7 cells and bovine aortic endothelial cells (BAECs). Furthermore, adenovirus-mediated overexpression of eEF1A1 increased eNOS mRNA instability, whereas knockdown of eEF1A1 substantially attenuated TNF-alpha-induced destabilization of eNOS mRNA and downregulation of eNOS expression in HUVECs. These results indicate that eEF1A1 is a novel eNOS 3'-UTR binding protein that plays a critical role in mediating TNF-alpha-induced decrease in eNOS mRNA stability.