Cyr61 Protects against Hyperoxia-Induced Cell Death via Akt Pathway in Pulmonary Epithelial Cells

Astragaloside IV improves pulmonary arterial hypertension by increasing the expression of CCN1 and activating the ERK1/2 pathway

The aim of the present study was to investigate the underlying mechanism of AS-IV and CCN1 in PAH and to evaluate whether the protective effect of AS-IV against PAH is associated with CCN1 and its related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS-IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS-IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT- and hypoxia-induced increased the hemodynamic parameters and apoptosis. AS-IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α-SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS-IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p-ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS-IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS-IV against PAH.

Increased CYR61 expression activates CCND1/c-Myc pathway to promote nasal epithelial cells proliferation in chronic rhinosinusitis with nasal polyps

PURPOSE

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is a chronic sinonasal inflammatory disease characterized histologically by hyperplastic nasal epithelium and epithelial cells proliferation. Cysteine-rich angiogenic inducer 61 (CYR61) acts as a positive regulator of cell cycle process. Cyclin D1 (CCND1) and c-Myc play key roles in the processes of cell cycle and cell growth. The purpose of our research was to explore the expression and roles of CYR61, CCND1 and c-Myc in CRSwNP.

METHODS

FeaturePlot and vlnPlot functions embedded in the seurat package (version 4.1.1) of R software (version 4.2.0) were applied to explore the cellular distribution of CYR61, CCND1 and c-Myc in the single-cell RNA sequencing (scRNA-seq) dataset of nasal tissue samples. CYR61, CCND1 and c-Myc immunolabeling and mRNA levels in nasal tissue samples were assessed by immunohistochemistry and real-time PCR. Co-localization of CYR61, CCND1 and c-Myc with basal epithelial cell marker P63 was assayed using double-label immunofluorescence staining. Furthermore, we collected and cultured human nasal epithelial cells (HNEC) to assess the regulation and role of CYR61 in vitro study.

RESULTS

CYR61, CCND1 and c-Myc were primarily expressed by nasal epithelial cells. Significant upregulation of CYR61, CCND1 and c-Myc positive cells and increased levels of CYR61, CCND1 and c-Myc mRNA were found in nasal polyps in comparison to control samples. Of note, CYR61 mRNA and protein levels were altered by SEB, LPS, IFN-γ, IL-13, IL-17A and TGF-β1 in HNEC. In addition, CYR61 intervention could increase CCND1 and c-Myc mRNA and protein levels to promote HNEC proliferation, and siRNA against ITGA2 (si-ITGA2) could reverse CYR61 induced upregulation of CCND1 and c-Myc mRNA and protein levels in HNEC and cell proliferation of HNEC.

CONCLUSIONS

CYR61, CCND1 and c-Myc were primarily expressed by epithelial cells in nasal mucosa. CYR61, CCND1 and c-Myc expression levels were increased in CRSwNP compared with controls. CYR61 could interact with ITGA2 to enhance HNEC proliferation via upregulating CCND1 and c-Myc levels in the HNEC, leading to hyperplastic nasal epithelium in CRSwNP.

Serum CYR61 as a potential biomarker to improve breast cancer diagnostics

Purpose: To investigate the role of serum CYR61 as a biomarker for the diagnosis of breast cancer and to analyze the association between serum CYR61 levels and the clinicopathological features in breast cancer patients. Methods: Serum CYR61 was measured in breast cancer patients and healthy controls by ELISA. Results: The serum levels of CYR61 in breast cancer patients were higher than those in healthy controls. The area under the receiver operating characteristic curve for CYR61 was higher than that for carcinoembryonic antigen and carbohydrate antigen 15-3. The increased CYR61 levels were correlated with menopausal status and Ki67 expression. Conclusion: Serum CYR61 might be a novel biomarker to assist the diagnosis and clinicopathological status assessment of breast cancer.

Differential Transcriptomic Profiles Following Stimulation with Lipopolysaccharide in Intestinal Organoids from Dogs with Inflammatory Bowel Disease and Intestinal Mast Cell Tumor

Lipopolysaccharide (LPS) is associated with chronic intestinal inflammation and promotes intestinal cancer progression in the gut. While the interplay between LPS and intestinal immune cells has been well-characterized, little is known about LPS and the intestinal epithelium interactions. In this study, we explored the differential effects of LPS on proliferation and the transcriptome in 3D enteroids/colonoids obtained from dogs with naturally occurring gastrointestinal (GI) diseases including inflammatory bowel disease (IBD) and intestinal mast cell tumor. The study objective was to analyze the LPS-induced modulation of signaling pathways involving the intestinal epithelia and contributing to colorectal cancer development in the context of an inflammatory (IBD) or a tumor microenvironment. While LPS incubation resulted in a pro-cancer gene expression pattern and stimulated proliferation of IBD enteroids and colonoids, downregulation of several cancer-associated genes such as Gpatch4, SLC7A1, ATP13A2, and TEX45 was also observed in tumor enteroids. Genes participating in porphyrin metabolism (CP), nucleocytoplasmic transport (EEF1A1), arachidonic acid, and glutathione metabolism (GPX1) exhibited a similar pattern of altered expression between IBD enteroids and IBD colonoids following LPS stimulation. In contrast, genes involved in anion transport, transcription and translation, apoptotic processes, and regulation of adaptive immune responses showed the opposite expression patterns between IBD enteroids and colonoids following LPS treatment. In brief, the crosstalk between LPS/TLR4 signal transduction pathway and several metabolic pathways such as primary bile acid biosynthesis and secretion, peroxisome, renin-angiotensin system, glutathione metabolism, and arachidonic acid pathways may be important in driving chronic intestinal inflammation and intestinal carcinogenesis.

Blood-based detection of lung cancer using cysteine-rich angiogenic inducer 61 (CYR61) as a circulating protein biomarker: a pilot study

Lung cancer is the most often diagnosed cancer and the main cause of cancer deaths in the world compared with other tumor entities. To date, the only screening method for high‐risk lung cancer patients is low‐dosed computed tomography which still suffers from high false‐positive rates and overdiagnosis. Therefore, there is an obvious need to identify biomarkers for the detection of lung cancer that could be used to guide the use of low‐dosed computed tomography or other imaging procedures. We aimed to assess the performance of the protein cysteine‐rich angiogenic inducer 61 (CYR61) as a circulating biomarker for the detection of lung cancer. CYR61 concentrations in plasma were significantly elevated in 87 lung cancer patients (13.7 ± 18.6 ng·mL⁻¹) compared with 150 healthy controls (0.29 ± 0.22 ng·mL⁻¹). Subset analysis stratified by sex revealed increased CYR61 concentrations for adenocarcinoma and squamous cell carcinoma in men compared with women. For male lung cancer patients versus male healthy controls, the sensitivity was 84% at a specificity of 100%, whereas for females, the sensitivity was 27% at a specificity of 99%. The determination of circulating CYR61 protein in plasma might improve the detection of lung cancer in men. The findings of this pilot study support further verification of CYR61 as a biomarker for lung cancer detection in men. Additionally, CYR61 is significantly elevated in women but sensitivity and specificity for CYR61 are too low for the improvement of the detection of lung cancer in women.

Somanath P, Zhang D. The Roles of CCN1/CYR61 in Pulmonary Diseases

CCN1 (cysteine-rich 61, connective tissue growth factor, and nephroblastoma-1), previously named CYR61 (cysteine-rich angiogenic inducer 61) belongs to the CCN family of matricellular proteins. CCN1 plays critical roles in the regulation of proliferation, differentiation, apoptosis, angiogenesis, and fibrosis. Recent studies have extensively characterized the important physiological and pathological roles of CCN1 in various tissues and organs. In this review, we summarize both basic and clinical aspects of CCN1 in pulmonary diseases, including acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), lung fibrosis, pulmonary arterial hypertension (PAH), lung infection, and lung cancer. We also emphasize the important challenges for future investigations to better understand the CCN1 and its role in physiology and pathology, as well as the questions that need to be addressed for the therapeutic development of CCN1 antagonists in various lung diseases.

Alveolar CCN1 is associated with mechanical stretch and acute respiratory distress syndrome severity

The cellular communication network factor 1 (CCN1) is a matricellular protein that can modulate multiple tissue responses, including inflammation and repair. We have previously shown that adenoviral overexpression of Ccn1 is sufficient to cause acute lung injury in mice. We hypothesized that CCN1 is present in the airspaces of lungs during the acute phase of lung injury, and higher concentrations are associated with acute respiratory distress syndrome (ARDS) severity. We tested this hypothesis by measuring 1) CCN1 in bronchoalveolar lavage fluid (BALF) and lung homogenates from mice subjected to ventilation-induced lung injury (VILI), 2) Ccn1 gene expression and protein levels in MLE-12 cells (alveolar epithelial cell line) subjected to mechanical stretch, and 3) CCN1 in BALF from mechanically ventilated humans with and without ARDS. BALF CCN1 concentrations and whole lung CCN1 protein levels were significantly increased in mice with VILI (n = 6) versus noninjured controls (n = 6). Ccn1 gene expression and CCN1 protein levels were increased in MLE-12 cells cultured under stretch conditions. Subjects with ARDS (n = 77) had higher BALF CCN1 levels compared with mechanically ventilated subjects without ARDS (n = 45) (P < 0.05). In subjects with ARDS, BALF CCN1 concentrations were associated with higher total protein, sRAGE, and worse [Formula: see text]/[Formula: see text] ratios (all P < 0.05). CCN1 is present in the lungs of mice and humans during the acute inflammatory phase of lung injury, and concentrations are higher in patients with increased markers of severity. Alveolar epithelial cells may be an important source of CCN1 under mechanical stretch conditions.

The roles of microRNAs in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and irreversible airflow obstruction, with an abnormal lung function. The etiology of COPD correlates with complex interactions between environmental and genetic determinants. However, the exact pathogenesis of COPD is obscure although it involves multiple aspects including oxidative stress, imbalance between proteolytic and anti-proteolytic activity, immunity and inflammation, apoptosis, and repair and destruction in both airways and lungs. Many genes have been demonstrated to be involved in those pathogenic processes of this disease in patients exposed to harmful environmental factors. Previous reports have investigated promising microRNAs (miRNAs) to disclose the molecular mechanisms for COPD development induced by different environmental exposure and genetic predisposition encounter, and find some potential miRNA biomarkers for early diagnosis and treatment targets of COPD. In this review, we summarized the expression profiles of the reported miRNAs from studies of COPD associated with environmental risk factors including cigarette smoking and air pollution exposures, and provided an overview of roles of those miRNAs in the pathogenesis of the disease. We also highlighted the potential utility and limitations of miRNAs serving as diagnostic biomarkers and therapeutic targets for COPD.

The matricellular protein CCN1 in tissue injury repair

The expression of Ccn1 (Cyr61) is essential for cardiovascular development during embryogenesis, whereas in adulthood it is associated with inflammation, wound healing, injury repair, and related pathologies including fibrosis and cancer. Recent studies have found that CCN1 plays a critical role in promoting wound healing and tissue repair. Mechanistically, CCN1 functions through direct interaction with specific integrin receptors expressed in various cell types in the wound tissue microenvironment to coordinate diverse cellular functions for repair. Here we briefly summarize the current knowledge on the functions of CCN1 in tissue injury repair and discuss pertinent unanswered questions.

Recombinant CCN1 prevents hyperoxia-induced lung injury in neonatal rats

BackgroundCystein-rich protein 61 (Cyr61/CCN1) is a member of the CCN family of matricellular proteins that has an important role in tissue development and remodeling. However, the role of CCN1 in the pathogenesis of bronchopulmonary dysplasia (BPD) is unknown. Accordingly, we have investigated the effects of CCN1 on a hyperoxia-induced lung injury model in neonatal rats.MethodsIn experiment 1, newborn rats were randomized to room air (RA) or 85% oxygen (O₂) for 7 or 14 days, and we assessed the expression of CCN1. In experiment 2, rat pups were exposed to RA or O₂ and received placebo or recombinant CCN1 by daily intraperitoneal injection for 10 days. The effects of CCN1 on hyperoxia-induced lung inflammation, alveolar and vascular development, vascular remodeling, and right ventricular hypertrophy (RVH) were observed.ResultsIn experiment 1, hyperoxia downregulated CCN1 expression. In experiment 2, treatment with recombinant CCN1 significantly decreased macrophage and neutrophil infiltration, reduced inflammasome activation, increased alveolar and vascular development, and reduced vascular remodeling and RVH in the hyperoxic animals.ConclusionThese results demonstrate that hyperoxia-induced lung injury is associated with downregulated basal CCN1 expression, and treatment with CCN1 can largely reverse hyperoxic injury.

MicroRNA-181c inhibits cigarette smoke-induced chronic obstructive pulmonary disease by regulating CCN1 expression

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an obstinate pulmonary disease, causing irreversible alveoli collapse and increasing the risk for cardiovascular disease. Accumulating evidence has shown that the dysregulation of miRNAs is crucially involved in the pathogenesis and development of COPD. However, the effects and role of microRNA-181c (miR-181c) have not been investigated in a murine model of COPD.

METHODS

miR-181c expression was detected in human lung tissue samples of 34 patients, an in vivo murine model of CS exposure, and primary human bronchial epithelial cells (HBECs) by qRT-PCR. Degeneration of lung tissue, necrosis, infiltration and neutrophil cells were assessed with H&E and flow cytometry. Interleukin (IL)-6 and IL-8 levels were determined by an enzyme-linked immunosorbent assay and qRT-PCR. Luciferase reporter assay and correlation analyses were used to confirm and measure the levels between miR-181c and its target CCN1.

RESULTS

We showed that miR-181c was significantly down-regulated in lung tissues from patients with COPD compared to individuals who had never smoked (p < 0.01). We also observed a down-regulation of miR-181c in HBECs and a mouse model after cigarette smoke (CS) exposure. Functional assays demonstrated that miR-181c over-expression decreased the inflammatory response, neutrophil infiltration, reactive oxygen species (ROS) generation, and inflammatory cytokines induced by CS, while its down-regulation produced the opposite effects. Subsequent investigation found that CCN1 was a direct target of miR-181c. CCN1 expression was increased in lung tissues of COPD patients, and was negatively correlated with miR-181c expression in human COPD samples (p < 0.01).

CONCLUSIONS

Taken together, our data suggest the critical roles of miR-181c and its target CCN1 in COPD development, and provide potential therapeutic targets for COPD treatment.

Epithelial HO-1/STAT3 affords the protection of subanesthetic isoflurane against zymosan-induced lung injury in mice

Epithelial dysfunction is a key characteristic of acute lung injury (ALI). Isoflurane (ISO) confers lung protection via anti-inflammatory and anti-apoptotic properties. However, the specific role and potential mechanisms of subanesthetic ISO in lung epithelium protection during zymosan-induced ALI remain unclear. In this study, zymosan increased the expression and activity of beneficial heme oxygenase-1 (HO-1) and signal transducers and activators of transcription 3 (STAT3) in the lung and isolated type II alveolar epithelial cells (AECs-II) from wild-type (WT) mice, which was further enhanced by ISO treatment. ISO reduced the mortality, lung edema, histological changes and pulmonary cell apoptosis, and simultaneously decreased total cells, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels in bronchoalveolar lavage fluid in the zymosan-stimulated WT mice but not in HO-1-deficient mice. Moreover, ISO abated zymosan-augmented lactate dehydrogenase activity, TNF-α and IL-1β production, and apoptosis in WT AECs-II but not in HO-1- or STAT3-silenced cells. Mechanisticly, the epithelial protective effects of ISO on zymosan insult in vivo and in vitro were mediated by a positive feedback loop comprising STAT3 and HO-1. Pro-survival and anti-apoptosis by ISO was highly reliant on activated STAT3, involving in downstream Akt activation and reduced ratio of pro-apoptotic/anti-apoptotic molecules. Overall, HO-1/STAT3 signaling is in favor of lung epithelial protection of ISO in zymosan-challenged mice, suggesting ISO as a valuable therapeutic agent for ALI.

Lipopolysaccharide-induced CCN1 production enhances interleukin-6 secretion in bronchial epithelial cells

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a clinical complication caused by primary or secondary lung injury, as well as by systemic inflammation. Researches regarding molecular pathophysiology of ALI/ARDS are immerging with an ultimate aim towards developing prognostic molecular biomarkers and molecule-based therapy. However, the molecular mechanisms concerning ALI/ARDS are still not completely understood. The purpose of the present study was to identify a crucial role of CCN1 in inflammatory microenvironment during ALI/ARDS and focus on a potential communication between CCN1 and interleukin-6 (IL-6) in the airway epithelial cells. Our data illustrated that the expression levels of CCN1 and IL-6 in bronchoalveolar lavage fluid (BALF) in a lipopolysaccharide (LPS)-induced ALI mouse model were significantly elevated and the pulmonary expression of CCN1 was restricted to bronchial epithelial cells. Interestingly, both endogenous and exogenous CCN1 stimulated IL-6 production in vitro. Furthermore, LPS-induced IL-6 production in a bronchial epithelial cell line was blocked by CCN siRNA whereas CCN1 induced by LPS was sensitive to PI3K inhibition. Together, our data indicate a linear signal pathway, LPS-CCN1-IL-6, existing in bronchial epithelial cells after LPS exposure. This finding may represent an additional mechanism and a novel target for development of therapy and biomarker on ALI/ARDS.

Altered expression of the CCN genes in the lungs of mice in response to cigarette smoke exposure and viral and bacterial infections

The CCN proteins are key signaling and regulatory molecules involved in many biological functions and contribute to malignant and non-malignant lung diseases. Despite the high morbidity and mortality of the lung respiratory infectious diseases, there is very little data related to the expression of the CCNs during infection. We investigated in mice the pulmonary mRNA expression levels of five CCNs (1 to 5) in response to influenza A virus (IAV) and bacterial agents (Nontypeable Haemophilus influenzae (NTHi), lipopolysaccharide (LPS) and lipoteichoic acid (LTA)). IAV, NTHi, LPS or LTA were instilled intranasally into mice. Mice were also exposed for 4days or 8weeks to cigarette smoke alone or prior infection to IAV in order to determine if CS modifies the CCN response to a viral infection. All challenges induced a robust inflammation. The mRNA expression of CCN1, CCN2 and CCN3 was decreased after short exposure to CS whereas prolonged exposure altered the expression of CCN1, CCN3 and CCN4. Influenza A virus infection increased CCN1, 2, 4 and 5 mRNA levels but expression of CCN3 was significantly decreased. Acute CS exposure prior infection had little effect on the expression of CCN genes but prolonged exposure abolished the IAV-dependent induction. Treatment with LPS or LTA and infection with NTHi revealed that both Gram-positive and Gram-negative bacteria rapidly modulate the expression of the CCN genes. Our findings reveal that several triggers of lung inflammation influence differently the CCN genes. CCN3 deserves special attention since its mRNA expression is decreased by all the triggers studied.

CCN1 acutely increases nitric oxide production via integrin αvβ3-Akt-S6K-phosphorylation of endothelial nitric oxide synthase at the serine 1177 signaling axis

Although CCN1 (also known as cysteine-rich, angiogenic inducer 61, CYR61) has been reported to promote angiogenesis and neovascularization in endothelial cells (ECs), its effects on endothelial nitric oxide (NO) production have never been studied. Using human umbilical vein ECs, we investigated whether and how CCN1 regulates NO production. CCN1 acutely increased NO production in a time- and dose-dependent manner, which was accompanied by increased phosphorylation of endothelial NO synthase (eNOS) at serine 1177 (eNOS-Ser(1177)), but not that of eNOS-Thr(495) or eNOS-Ser(114). The level of total eNOS expression was unaltered. Treatment with either LY294002, a selective inhibitor of phosphoinositide 3-kinase known as an upstream kinase of Akt, or H-89, an inhibitor of protein kinase A, mitogen- and stress-activated protein kinase 1, Rho-associated protein kinase 2, and ribosomal protein S6 kinase (S6K), inhibited CCN1-stimulated eNOS-Ser(1177) phosphorylation and subsequent NO production. Ectopic expression of small interfering RNA against Akt and S6K significantly inhibited the effects of CCN1. Consistently, CCN1 increased the phosphorylation of Akt-Ser(473) and S6K-Thr(389). However, CCN1 did not alter the expression or secretion of VEGF, a known downstream factor of CCN1 and a potential upstream factor of Akt-mediated eNOS-Ser(1177) phosphorylation. Furthermore, neutralization of integrin αvβ3 with corresponding antibody completely reversed all of the observed effects of CCN1. Moreover, CCN1 increased acetylcholine-induced relaxation in the rat aortas. Finally, we also found that CCN1-stimulated eNOS-Ser(1177) phosphorylation and NO production are true for other types of EC tested. In conclusion, CCN1 acutely increases NO production via activation of a signaling axis in integrin αvβ3-Akt-S6K-eNOS-Ser(1177) phosphorylation, suggesting an important role for CCN1 in vasodilation.

Eyeing the Cyr61/CTGF/NOV (CCN) group of genes in development and diseases: highlights of their structural likenesses and functional dissimilarities

“CCN” is an acronym referring to the first letter of each of the first three members of this original group of mammalian functionally and phylogenetically distinct extracellular matrix (ECM) proteins [i.e., cysteine-rich 61 (CYR61), connective tissue growth factor (CTGF), and nephroblastoma-overexpressed (NOV)]. Although “CCN” genes are unlikely to have arisen from a common ancestral gene, their encoded proteins share multimodular structures in which most cysteine residues are strictly conserved in their positions within several structural motifs. The CCN genes can be subdivided into members developmentally indispensable for embryonic viability (e.g., CCN1, 2 and 5), each assuming unique tissue-specific functions, and members not essential for embryonic development (e.g., CCN3, 4 and 6), probably due to a balance of functional redundancy and specialization during evolution. The temporo-spatial regulation of the CCN genes and the structural information contained within the sequences of their encoded proteins reflect diversity in their context and tissue-specific functions. Genetic association studies and experimental anomalies, replicated in various animal models, have shown that altered CCN gene structure or expression is associated with “injury” stimuli—whether mechanical (e.g., trauma, shear stress) or chemical (e.g., ischemia, hyperglycemia, hyperlipidemia, inflammation). Consequently, increased organ-specific susceptibility to structural damages ensues. These data underscore the critical functions of CCN proteins in the dynamics of tissue repair and regeneration and in the compensatory responses preceding organ failure. A better understanding of the regulation and mode of action of each CCN member will be useful in developing specific gain- or loss-of-function strategies for therapeutic purposes.

Single and Compound Knock-outs of MicroRNA (miRNA)-155 and Its Angiogenic Gene Target CCN1 in Mice Alter Vascular and Neovascular Growth in the Retina via Resident Microglia

The response of the retina to ischemic insult typically leads to aberrant retinal neovascularization, a major cause of blindness. The epigenetic regulation of angiogenic gene expression by miRNAs provides new prospects for their therapeutic utility in retinal neovascularization. Here, we focus on miR-155, a microRNA functionally important in inflammation, which is of paramount importance in the pathogenesis of retinal neovascularization. Whereas constitutive miR-155-deficiency in mice results in mild vascular defects, forced expression of miR-155 causes endothelial hyperplasia and increases microglia count and activation. The mouse model of oxygen-induced retinopathy, which recapitulates ischemia-induced aberrant neovessel growth, is characterized by increased expression of miR-155 and localized areas of microglia activation. Interestingly, miR-155 deficiency in mice reduces microglial activation, curtails abnormal vessel growth, and allows for rapid normalization of the retinal vasculature following ischemic insult. miR-155 binds to the 3'-UTR and represses the expression of the CCN1 gene, which encodes an extracellular matrix-associated integrin-binding protein that both promotes physiological angiogenesis and harnesses growth factor-induced abnormal angiogenic responses. Single CCN1 deficiency or double CCN1 and miR-155 knock-out in mice causes retinal vascular malformations typical of faulty maturation, mimicking the vascular alterations of miR-155 gain of function. During development, the miR-155/CCN1 regulatory axis balances the proangiogenic and proinflammatory activities of microglia to allow for their function as guideposts for sprout fusion and anastomosis. Under ischemic conditions, dysregulated miR-155 and CCN1 expression increases the inflammatory load and microglial activation, prompting aberrant angiogenic responses. Thus, miR-155 functions in tandem with CCN1 to modulate inflammation-induced vascular homeostasis and repair.

Matrix protein CCN1 induced by bacterial DNA and CpG ODN limits lung inflammation and contributes to innate immune homeostasis

To defend against pulmonary infections, lung epithelial cells are equipped with complex innate immunity closely linked to inflammation. Dysregulated innate immunity/inflammation leads to self-perpetuating lung injury. The CpG motif in bacterial DNA is one of the factors involved in bacterial infection-associated inflammation. Bacterial DNA and synthetic CpG oligonucleotide (ODN) induced CCN1 secretion from lung epithelial cells, functioning as a potential "braking" signal to prevent uncontrolled inflammatory responses. CpG ODN-induced endoplasmic reticulum (ER) stress resulted in Src-Y527 phosphorylation (pY527) and Src/CCN1 vWF domain dissociation. Src-Y527 activated caveolin-1 (cav-1) phosphorylation at Y14 and then modulated CCN1 secretion via pCav-1 interaction with the CCN1 IGFbp domain. Functionally, secreted CCN1 promoted anti-inflammatory cytokine interleukin (IL)-10 release from epithelial cells via integrin αVβ6-PKC, and this subsequently suppressed tumor necrosis factor (TNF)-α, macrophage inflammatory protein 2 (MIP-2)-2 secretion and neutrophil infiltration in the lungs. Collectively, bacterial DNA/CpG ODN-stimulated CCN1 secretion via the BiP/GRP78-Src(Y527)-JNK-Cav-1(Y14) pathway and CpG-induced CCN1 conferred anti-inflammatory roles. Our studies suggested a novel paradigm by which the lung epithelium maintains innate immune homeostasis after bacterial infection.

Collagen matrix-induced expression of integrin αVβ3 in circulating angiogenic cells can be targeted by matricellular protein CCN1 to enhance their function

Circulating angiogenic cells (CACs) play an important role in vascular homeostasis and hold therapeutic promise for treating a variety of cardiovascular diseases. However, further improvements are needed because the effects of CAC therapy remain minimal or transient. The regenerative potential of these cells can be improved by culture on a collagen-based matrix through the up-regulation of key integrin proteins. We found that human CAC function was enhanced by using the matricellular protein CCN1 (CYR61/CTGF/NOV family member 1) to target integrin αV and β3, which are up-regulated on matrix. Compared to matrix-cultured CACs, CCN1-matrix CACs exhibited a 2.2-fold increase in cell proliferation, 1.8-fold greater migration toward VEGF, and 1.7-fold more incorporation into capillary-like structures in an angiogenesis assay. In vivo, intramuscular injection of CCN1-matrix-cultured CACs into ischemic hind limbs of CD-1 nude mice resulted in blood flow recovery to 80% of baseline, which was greater than matrix-cultured CACs (66%) and PBS (35%) treatment groups. Furthermore, transplanted CCN1-matrix CACs exhibited greater engraftment (11-fold) and stimulated the up-regulation of survival and angiogenic genes (>3-fold). These findings reveal the importance of cell-matrix interactions in regulating CAC function and also reveal a mechanism by which these may be exploited to enhance cell therapies for ischemic disease.

The matricellular "cysteine-rich protein 61" is released from activated platelets and increased in the circulation during experimentally induced sepsis

Sepsis and sepsis-induced organ dysfunction remain lethal and common conditions among intensive care patients. Accumulating evidence suggests that the matricellular Cyr61/CCN1 (cysteine-rich, angiogenic-inducer, 61) protein is involved in the regulation of inflammatory responses and possesses organ-protective capabilities in diseases of an inflammatory etiology. However, its regulation in sepsis remains largely unexplored. The present study provides a comprehensive description of CCN1 regulation in the circulation and vital organs during experimentally induced sepsis with developing organ dysfunction. Female CD-1 mice served as baseline controls or were subjected to cecal ligation and puncture (CLP) for 18 to 96 h, and CCN1 regulation was analyzed in selected organs and in the circulation. A 5-, 5-, and 3-fold increases in circulating CCN1 protein were observed at 18, 48, and 96 h after CLP, respectively. Hepatic and pulmonary CCN1 mRNA expression was down-regulated by 80%, 60%, and 55% and 85%, 80%, and 65% at 18, 48, and 96 h after CLP and undetectable in circulating white blood cells. To identify a potential source for the circulating protein, mouse and human platelets were explored and revealed to contain CCN1. Human platelets were stimulated by thrombin and a specific PAR1 agonist (SFLLRN) in vitro. Both agonists induced an instant CCN1 release, and the effect of SFLLRN was blocked by the specific antagonist RWJ56110. The current study demonstrates that experimental sepsis is associated with a robust increase in circulating CCN1 protein levels and a paradoxical downregulation of CCN1 mRNA expression in vital organs. It provides evidence that CCN1 is released from activated platelets, suggesting that platelets constitute a novel source for CCN1 release to the circulation during sepsis.

Interaction of CCN1 with αvβ3 integrin induces P-glycoprotein and confers vinblastine resistance in renal cell carcinoma cells

Renal cell carcinoma (RCC) ranks among the most chemoresistant tumors, and P-glycoprotein (P-gp) predominates multidrug resistance mechanisms by reducing the accumulation of intracellular chemotherapy drugs such as vinblastine (VBL), which is considered the most effective chemotherapeutic agent for this neoplasia. Unfortunately, the mechanism by which the expression of P-gp is regulated and the ways to inhibit the function of P-gp are poorly understood. Our study was carried out to determine the possible role of CCN1 in P-pg-mediated drug resistance on the basis of the validated function of CCN1, an extracellular matrix protein, in promoting chemoresistance. As expected, CCN1 was overexpressed in VBL-resistant cell lines (ACHN/VBL, A498/VBL, Caki-1/VBL, and Caki-2/VBL) as measured by enzyme-linked immunosorbent assay. We then transfected non-VBL-resistant cell lines with Ad-CCN1 and observed that the IC50 of VBL increased by about 3-5 times. Furthermore, both CCN1 antibody neutralization and αvβ3 integrin antibody blockade decreased the IC50 of VBL, which showed that CCN1 and αvβ3 are associated with resistance to VBL in RCC. Simultaneously, the enhanced expression of CCN1 triggered the intracellular PI3K/Akt pathway by binding αvβ3 integrin, as shown by western blot. P-gp expression was augmented in response to activation of the PI3K/Akt pathway, which could be modified by PI3K inhibitor LY294002 or multidrug resistance siRNA transfection. Therefore, targeted restraint of CCN1 or αvβ3 integrin in combination with the administration of VBL may be beneficial in the treatment of primary and metastatic RCC.

CCN1 secretion induced by cigarette smoking extracts augments IL-8 release from bronchial epithelial cells

Inflammation involves in many cigarette smoke (CS) related diseases including the chronic obstructive pulmonary disease (COPD). Lung epithelial cell released IL-8 plays a crucial role in CS induced lung inflammation. CS and cigarette smoke extracts (CSE) both induce IL-8 secretion and subsequently, IL-8 recruits inflammatory cells into the lung parenchyma. However, the molecular and cellular mechanisms by which CSE triggers IL-8 release remain not completely understood. In this study, we identified a novel extracellular matrix (ECM) molecule, CCN1, which mediated CSE induced IL-8 secretion by lung epithelial cells. We first found that CS and CSE up-regulated CCN1 expression and secretion in lung epithelial cells in vivo and in vitro. CSE up-regulated CCN1 via induction of reactive oxygen spices (ROS) and endoplasmic reticulum (ER) stress. p38 MAPK and JNK activation were also found to mediate the signal pathways in CSE induced CCN1. CCN1 was secreted into ECM via Golgi and membrane channel receptor aquaporin4. After CSE exposure, elevated ECM CCN1 functioned via an autocrine or paracrine manner. Importantly, CCN1 activated Wnt pathway receptor LRP6, subsequently stimulated Wnt pathway component Dvl2 and triggered beta-catenin translocation from cell membrane to cytosol and nucleus. Treatment of Wnt pathway inhibitor suppressed CCN1 induced IL-8 secretion from lung epithelial cells. Taken together, CSE increased CCN1 expression and secretion in lung epithelial cells via induction of ROS and ER stress. Increased ECM CCN1 resulted in augmented IL-8 release through the activation of Wnt pathway.

Degradome products of the matricellular protein CCN1 as modulators of pathological angiogenesis in the retina

CCN1 is a matricellular protein involved in normal vascular development and tissue repair. CCN1 exhibits cell- and context-dependent activities that are reflective of its tetramodular structure phylogenetically linked to four domains found in various matrix proteins. Here, we show that vitreal fluids from patients with proliferative diabetic retinopathy (PDR) were enriched with a two-module form of CCN1 comprising completely or partially the insulin-like growth factor-binding protein (IGFBP) and von Willebrand factor type C (vWC) domains. The two- and three-module forms comprising, in addition to IGFBP and vWC, the thrombospondin type 1 (TSP1) repeats are CCN1 degradome products by matrix metalloproteinase-2 and -14. The functional significance of CCN1 and its truncated variants was determined in the mouse model of oxygen-induced retinopathy, which simulates neovascular growth associated with PDR and assesses treatment outcomes. In this model, lentivirus-mediated expression of either CCN1 or the IGFBP-vWC-TSP1 form reduced ischemia-induced neovascularization, whereas ectopic expression of the IGFBP-vWC variant exacerbated pathological angiogenesis. The IGFBP-vWC form has potent proangiogenic properties promoting retinal endothelial cell growth, migration, and three-dimensional tubular structure formation, whereas the IGFBP-vWC-TSP1 variant suppressed cell growth and angiogenic gene expression. Both IGFBP-vWC and IGFBP-vWC-TSP1 forms exhibited predictable variations of their domain folding that enhanced their functional potential. These data provide new insights into the formation and activities of CCN1-truncated variants and raise the predictive value of the form containing completely or partially the IGFBP and vWC domains as a surrogate marker of CCN1 activity in PDR distinguishing pathological from physiological angiogenesis.

Cysteine-rich protein 61 (CCN1) and connective tissue growth factor (CCN2) at the crosshairs of ocular neovascular and fibrovascular disease therapy

The vasculature forms a highly branched network investing every organ of vertebrate organisms. The retinal circulation, in particular, is supported by a central retinal artery branching into superficial arteries, which dive into the retina to form a dense network of capillaries in the deeper retinal layers. The function of the retina is highly dependent on the integrity and proper functioning of its vascular network and numerous ocular diseases including diabetic retinopathy, age-related macular degeneration and retinopathy of prematurity are caused by vascular abnormalities culminating in total and sometimes irreversible loss of vision. CCN1 and CCN2 are inducible extracellular matrix (ECM) proteins which play a major role in normal and aberrant formation of blood vessels as their expression is associated with developmental and pathological angiogenesis. Both CCN1 and CCN2 achieve disparate cell-type and context-dependent activities through modulation of the angiogenic and synthetic phenotype of vascular and mesenchymal cells respectively. At the molecular level, CCN1 and CCN2 may control capillary growth and vascular cell differentiation by altering the composition or function of the constitutive ECM proteins, potentiating or interfering with the activity of various ligands and/or their receptors, physically interfering with the ECM-cell surface interconnections, and/or reprogramming gene expression driving cells toward new phenotypes. As such, these proteins emerged as important prognostic markers and potential therapeutic targets in neovascular and fibrovascular diseases of the eye. The purpose of this review is to highlight our current knowledge and understanding of the most recent data linking CCN1 and CCN2 signaling to ocular neovascularization bolstering the potential value of targeting these proteins in a therapeutic context.

Ariadne's ChemEffect and Pathway Studio knowledge base

IMPORTANCE OF THE FIELD

Drug discovery and development is a very complex and costly process. Understanding the detailed molecular mechanisms of a disease and drug actions can make it more efficient not only for new target discovery but also for lead prioritization, drug repositioning and development of biomarkers for drug efficacy and safety. Access to formalized knowledge about functions of proteins and small molecules is crucial for rationalization of the drug development process, and scientific publications are the main source of this knowledge. Protein knowledge networks capturing protein functions, protein-protein relations and organization of proteins in complex cellular sub-systems are making their way into modern drug discovery. Chemical networks representing multiple aspects of chemical functional information integrated into a protein systems biology network is even more advanced and promising paradigm.

AREAS COVERED IN THIS REVIEW

This review describes utilization of literature-derived protein and chemical functional knowledge bases in drug development.

WHAT THE READER WILL GAIN

Readers will gain an understanding of how integrated protein and chemical knowledge networks can be used for understanding and building the models of cellular events, disease mechanisms, and drug actions, finding biomarkers of drug efficacy and safety, as well as interpretation of high-throughput gene expression, proteomic and metabolomic experiments.

TAKE HOME MESSAGE

Integrated literature-derived protein and chemical knowledge bases can rationalize many aspects of drug development process including drug repositioning and biomarker design.

Differential Effects of MicroRNAs on Glioblastoma Growth and Migration

Glioblastoma multiforme is characterized by rapid proliferation, aggressive metastatic potential, and resistance to radio- and chemotherapy. The matricellular protein CYR61 regulates cellular proliferation and migration and is highly expressed in Glioblastomas. MicroRNAs are 22-nucleotides long RNAs that regulate gene expression post-transcriptionally. Here, we utilized the LN229 glioblastoma cell line and found that CYR61 is a target of miR-136, miR-155, and miR-634. Over-expression of miR-136 and miR-634 miRNAs negatively affected proliferation, but not migration, while expression of miR-155 reduced migration but did not affect the proliferation of LN229 cells. Investigation of the molecular mechanisms affected by expression of miR-634 revealed an increased phosphorylation of p70S6 kinase, suggesting an induction of the mammalian target of rapamycin (mTOR) complex 1 pathway. Additionally, in miR-634 overexpressing cells, TSC2, a negative regulator of mTOR signaling, was found to be decreased. Altogether, our study provides insights on the differential roles of miRs-136, -155, and -634 in regulating glioblastoma cell growth and migration, and how microRNAs could be manipulated to decrease the aggressiveness and metastatic potential of tumor cells.

Role of β-catenin-regulated CCN matricellular proteins in epithelial repair after inflammatory lung injury

Repair of the lung epithelium after injury is integral to the pathogenesis and outcomes of diverse inflammatory lung diseases. We previously reported that β-catenin signaling promotes epithelial repair after inflammatory injury, but the β-catenin target genes that mediate this effect are unknown. Herein, we examined which β-catenin transcriptional coactivators and target genes promote epithelial repair after inflammatory injury. Transmigration of human neutrophils across cultured monolayers of human lung epithelial cells resulted in a fall in transepithelial resistance and the formation of discrete areas of epithelial denudation ("microinjury"), which repaired via cell spreading by 96 h. In mice treated with intratracheal (i.t.) LPS or keratinocyte chemokine, neutrophil emigration was associated with increased permeability of the lung epithelium, as determined by increased bronchoalveolar lavage (BAL) fluid albumin concentration, which decreased over 3-6 days. Activation of β-catenin/p300-dependent gene expression using the compound ICG-001 accelerated epithelial repair in vitro and in murine models. Neutrophil transmigration induced epithelial expression of the β-catenin/p300 target genes Wnt-induced secreted protein (WISP) 1 and cysteine-rich (Cyr) 61, as determined by real-time PCR (qPCR) and immunostaining. Purified neutrophil elastase induced WISP1 upregulation in lung epithelial cells, as determined by qPCR. WISP1 expression increased in murine lungs after i.t. LPS, as determined by ELISA of the BAL fluid and qPCR of whole lung extracts. Finally, recombinant WISP1 and Cyr61 accelerated repair, and Cyr61-neutralizing antibodies delayed repair of the injured epithelium in vitro. We conclude that β-catenin/p300-dependent expression of WISP1 and Cyr61 is critical for epithelial repair and represents a potential therapeutic target to promote epithelial repair after inflammatory injury.

The matri-cellular proteins 'cysteine-rich, angiogenic-inducer, 61' and 'connective tissue growth factor' are regulated in experimentally-induced sepsis with multiple organ dysfunction

Organ failure is a severe complication in sepsis for which the pathophysiology remains incompletely understood. Recently, the matri-cellular cysteine-rich, angiogenic induced, 61 (Cyr61/CCN1); connective tissue growth factor (Ctgf/CCN2); and nephroblastoma overexpressed gene (Nov/CCN3) (CCN)-protein family have been attributed organ-protective properties. Their expression is sensitive to mediators of sepsis pathophysiology but a potential role in sepsis remains elusive. To provide an initial assessment, 50 rats were subjected to 18 h of cecal-ligation and puncture or sham operation. Hepatic and pulmonary CCN1 mRNA displayed an average 7.4- and 3.3-fold induction, while its cardiac expression was unchanged. The changes coincided with excessive hepatic and pulmonary inflammatory gene activation and a restricted cardiac inflammation. Furthermore, hepatocytes displayed a dosage-dependent CCN1 mRNA response in vitro, supporting a cytokine-mediated CCN1 regulation in sepsis. CCN2 mRNA was 2.2-fold induced in the liver, while 2.0-fold and 1.4-fold repressed in the heart and lung. Meanwhile, it did not respond to TNF-α exposure in vitro, which indicates different means of regulation than for CCN1. Taken together, this study provides the first evidence for multi-organ regulation of CCN1 and CCN2 in early stages of sepsis, and implies the eruption of inflammatory mediators as a potential mechanism behind the observed CCN1 regulation.

Positive end-expiratory pressure and surfactant decrease lung injury during initiation of ventilation in fetal sheep

The initiation of ventilation in preterm, surfactant-deficient sheep without positive end-expiratory pressure (PEEP) causes airway injury and lung inflammation. We hypothesized that PEEP and surfactant treatment would decrease the lung injury from initiation of ventilation with high tidal volumes. Fetal sheep at 128-day gestational age were randomized to ventilation with: 1) no PEEP, no surfactant; 2) 8-cmH(2)O PEEP, no surfactant; 3) no PEEP + surfactant; 4) 8-cmH(2)O PEEP + surfactant; or 5) control (2-cmH(2)O continuous positive airway pressure) (n = 6-7/group). After maternal anesthesia and hysterotomy, the head and chest were exteriorized, and the fetus was intubated. While maintaining placental circulation, the fetus was ventilated for 15 min with a tidal volume escalating to 15 ml/kg using heated, humidified, 100% nitrogen. The fetus then was returned to the uterus, and tissue was collected after 30 min for evaluation of early markers of lung injury. Lambs receiving both surfactant and PEEP had increased dynamic compliance, increased static lung volumes, and decreased total protein and heat shock proteins 70 and 60 in bronchoalveolar lavage fluid compared with other groups. Ventilation, independent of PEEP or surfactant, increased mRNA expression of acute phase response genes and proinflammatory cytokine mRNA in the lung tissue compared with controls. PEEP decreased mRNA for cytokines (2-fold) compared with groups receiving no PEEP. Surfactant administration further decreased some cytokine mRNAs and changed the distribution of early growth response protein-1 expression. The use of PEEP during initiation of ventilation at birth decreased early mediators of lung injury. Surfactant administration changed the distribution of injury and had a moderate additive protective effect.

CCN1/CYR61: the very model of a modern matricellular protein

CCN1 (CYR61) is a dynamically expressed, multifunctional matricellular protein that plays essential roles in cardiovascular development during embryogenesis, and regulates inflammation, wound healing and fibrogenesis in the adult. Aberrant CCN1 expression is associated with myriad pathologies, including various cancers and diseases associated with chronic inflammation. CCN1 promotes diverse and sometimes opposing cellular responses, which can be ascribed, as least in part, to disparate activities mediated through its direct binding to distinct integrins in different cell types and contexts. Accordingly, CCN1 promotes cell proliferation, survival and angiogenesis by binding to integrin α(v)β(3), and induces apoptosis and senescence through integrin α(6)β(1) and heparan sulfate proteoglycans. The ability of CCN1 to trigger the accumulation of a robust and sustained level of reactive oxygen species underlies some of its unique activities as a matrix cell-adhesion molecule. Emerging studies suggest that CCN1 might be useful as a biomarker or therapeutic target in certain diseases.

Computational approaches for drug repositioning and combination therapy design

Heterogeneous high-throughput biological data become readily available for various diseases. The amount of data points generated by such experiments does not allow manual integration of the information to design the most optimal therapy for a disease. We describe a novel computational workflow for designing therapy using Ariadne Genomics Pathway Studio software. We use publically available microarray experiments for glioblastoma and automatically constructed ResNet and ChemEffect databases to exemplify how to find potentially effective chemicals for glioblastoma--the disease yet without effective treatment. Our first approach involved construction of signaling pathway affected in glioblastoma using scientific literature and data available in ResNet database. Compounds known to affect multiple proteins in this pathway were found in ChemEffect database. Another approach involved analysis of differential expression in glioblastoma patients using Sub-Network Enrichment Analysis (SNEA). SNEA identified angiogenesis-related protein Cyr61 as the major positive regulator upstream of genes differentially expressed in glioblastoma. Using our findings, we then identified breast cancer drug Fulvestrant as a major inhibitor of glioblastoma pathway as well as Cyr61. This suggested Fulvestrant as a potential treatment against glioblastoma. We further show how to increase efficacy of glioblastoma treatment by finding optimal combinations of Fulvestrant with other drugs.

Deletion of caveolin-1 protects hyperoxia-induced apoptosis via survivin-mediated pathways

Hyperoxia-induced lung injury is an established model that mimics human acute respiratory distress syndrome. Cell death is a prominent feature in lungs following prolonged hyperoxia. Caveolae are omega-shaped invaginations of the plasma membrane. Caveolin-1 (cav-1), a 22-kDa transmembrane scaffolding protein, is the principal structural component of caveolae. We have recently shown that deletion of cav-1 (cav-1-/-) protected against hyperoxia-induced cell death and lung injury both in vitro and in vivo; however, the mechanisms remain unclear. Survivin, a member of the inhibitor of apoptosis protein family, inhibits apoptosis in tumor cells. Although emerging evidence suggests that survivin is involved in wound healing, especially in vascular injuries, its role in hyperoxia-induced lung injury has not been investigated. Our current data demonstrated that hyperoxia induced apoptosis via suppressing survivin expression. Deletion of cav-1 abolished this suppression and subsequently protected against hyperoxia-induced apoptosis. Using "gain" and "loss" of function assays, we determined that survivin protected lung cells from hyperoxia-induced apoptosis via the inhibition of apoptosis executor caspase-3. Overexpression of survivin by deletion of cav-1 was regulated by Egr-1. Egr-1 functioned as a negative regulator of survivin expression. Deletion of cav-1 upregulated survivin via decreased Egr-1 binding of the survivin promoter region. Together, this study illustrates the effect of hyperoxia on survivin expression and the role of survivin in hyperoxia-induced apoptosis. We also demonstrate that deletion of cav-1 protects hyperoxia-induced apoptosis via modulation of survivin expression.

Caveolin-1 regulates the secretion and cytoprotection of Cyr61 in hyperoxic cell death

Cysteine-rich 61 (Cyr61) belongs to the CCN family and mediates cell proliferation, survival, and apoptosis. Our previous studies showed that Cyr61 protected against hyperoxia-induced lung cell death via Akt phosphorylation. Caveolin-1 (cav-1), a 22-kDa transmembrane scaffolding protein, is the principal structural component of caveolae. Emerging data show that cav-1 regulates signal transduction-associated proteins that reside in the caveolae. Numerous integrin-related pathways, including PI3K/Akt-induced cell survival are controlled by cav-1-mediated signaling. Our data showed that recombinant Cyr61 promoted cell proliferation and resistance to hyperoxia-induced cell death in vitro. Neutralizing antibodies reversed the above effects, indicating functional role of secreted Cyr61 in response to hyperoxic stress. While deletion of cav-1 protected cells from hyperoxia-induced cell death, Cyr61-neutralizing antibodies abolished this protective effect. Furthermore, Cyr61 and cav-1 colocalized and physically interacted via integrins in bronchial epithelial cells. Deletion of cav-1 increased extracellular and decreased cytosolic Cyr61, both in vitro and in vivo. Pretreatment with Brefeldin A increased intracellular Cyr61 in cav-1(-/-) cells, while decreasing extracellular Cyr61. Taken together, Cav-1/Cyr61 interaction via integrins represents a novel pathway of Cyr61 signaling involving cav-1-dependent processes, which play a critical role in regulating hyperoxia-induced cell death.

Functional properties and intracellular signaling of CCN1/Cyr61

CCN1/Cyr61 is a member of the protein family that can be promptly induced by growth factors. CCN1/Cyr61 promotes cell proliferation, adhesion, and differentiation. It plays important roles in angiogenesis and extracellular matrix production. In addition, CCN1/Cyr61 has many potential functions in tumorigenesis, development, embryo implantation, as well as formation of endometriotic lesions. Expression of CCN1/Cyr61 is regulated by a variety of agents including cytokines, growth factors, steroid hormones, and some drugs. These inducers regulate the transcription of CCN1/Cyr61 through several signaling transduction pathways. CCN1/Cyr61 is able to interact either with the cell itself or the surrounding cells through an autocrine-paracrine mechanism. It has been reported that CCN1/Cyr61 exerts its functions via interacting with at least five integrins as well as heparan sulfate proteoglycan. By activating Wnt, NF-kappaB, or tyrosine kinase signaling pathways, CCN1/Cyr61 is not only able to control the growth of epithelial cells and fibroblasts, but also induce or suppress apoptosis in a cell type-specific manner.

Wnt-induced secreted protein-1 is a prohypertrophic and profibrotic growth factor

Wnt1-induced secreted protein-1 (WISP-1) is a member of the cysteine-rich 61, connective tissue growth factor, and nephroblastoma overexpressed (CCN) family of growth factors and is expressed in the heart at low basal levels. The purpose of this study was to investigate whether WISP-1 is upregulated in postinfarct myocardium and whether WISP-1 exerts prohypertrophic and mitogenic effects stimulating myocyte hypertrophy, cardiac fibroblast (CF) proliferation, and collagen expression. Male C57Bl/6 (25 g) mice underwent permanent occlusion of the left anterior descending coronary artery. mRNA and protein levels were analyzed by Northern and Western blot analyses. Cardiomyocyte hypertrophy was quantified by protein and DNA synthesis. CF proliferation was quantified by CyQuant assay, and soluble collagen release by Sircol assay. A time-dependent increase in WISP-1 expression was detected in vivo in the noninfarct zone of the left ventricle, which peaked at 24 h (3.1-fold, P < 0.01). Similarly, biglycan expression was increased by 3.71-fold (P < 0.01). IL-1beta and TNF-alpha expression preceded WISP-1 expression in vivo and stimulated WISP-1 expression in neonatal rat ventricular myocytes in vitro. WISP-1-induced cardiomyocyte hypertrophy was evidenced by increased protein (2.78-fold), but not DNA synthesis, and enhanced Akt phosphorylation and activity. Treatment of primary CF with WISP-1 significantly stimulated proliferation at 48 h (6,966 +/- 264 vs. 5,476 +/- 307 cells/well, P < 0.01) and enhanced collagen release by 72 h (18.4 +/- 3.1 vs. 8.4 +/- 1.0 ng/cell, P < 0.01). Our results demonstrate for the first time that WISP-1 and biglycan are upregulated in the noninfarcted myocardium in vivo, suggesting a positive amplification of WISP-1 signaling. WISP-1 stimulates cardiomyocyte hypertrophy, fibroblast proliferation, and ECM expression in vitro. These results suggest that WISP-1 may play a critical role in post-myocardial infarction remodeling.

CCN1 protects cardiac myocytes from oxidative stress via β1 integrin–Akt pathway

CCN1 (Cyr61) is a secreted matricellular protein, mediating angiogenesis and cell survival through interaction with integrins. Although CCN1 expression is induced in the heart during ischemia and pressure overload, its function in cardiac myocytes remains to be elucidated. We hypothesized that CCN1 may not only induce angiogenesis but may also have a direct effect on cardiac myocytes during ischemia. In this study, we investigated the effect of CCN1 on survival of cardiac myocytes under oxidative stress and examined a signal transduction pathway downstream of CCN1. A solid-phase binding assay demonstrated that CCN1 was bound to cardiac myocytes in a dose-dependent, saturable manner. Inactivation of beta1 integrin in cardiac myocytes inhibited binding with CCN1, indicating that CCN1 was bound to cardiac myocytes via beta1 integrin. Knockdown of endogenous CCN1 decreased the number of surviving cells under oxidative stress, while pretreatment of cardiac myocytes with recombinant CCN1 significantly increased the number of surviving cells. Moreover, TUNEL staining showed that CCN1 significantly decreased apoptotic cells. Furthermore, treatment of cardiac myocytes with CCN1 induced phosphorylation of Akt and extracellular signal-regulated kinase (ERK). Inactivation of beta1 integrin inhibited CCN1-induced phosphorylation of these kinases and abolished the protective effect of CCN1. Moreover, pretreatment of cells with wortmannin completely blocked the protective effect of CCN1 on cardiac myocytes under oxidative stress, indicating that the protective effect of CCN1 was mainly mediated by activation of Akt. The antiapoptotic effect of CCN1 on cardiac myocytes together with its proangiogenic property could be beneficial in the treatment of ischemic heart disease.

Genomic expression profiling of human inflammatory cardiomyopathy (DCMi) suggests novel therapeutic targets

The clinical phenotype of human dilated cardiomyopathy (DCM) encompasses a broad spectrum of etiologically distinct disorders. As targeting of etiology-related pathogenic pathways may be more efficient than current standard heart failure treatment, we obtained the genomic expression profile of a DCM subtype characterized by cardiac inflammation to identify possible new therapeutic targets in humans. In this inflammatory cardiomyopathy (DCMi), a distinctive cardiac expression pattern not described in any previous study of cardiac disorders was observed. Two significantly altered gene networks of particular interest and possible interdependence centered around the cysteine-rich angiogenic inducer 61 (CYR61) and adiponectin (APN) gene. CYR61 overexpression, as in human DCMi hearts in situ, was similarly induced by inflammatory cytokines in vascular endothelial cells in vitro. APN was strongly downregulated in DCMi hearts and completely abolished cytokine-dependent CYR61 induction in vitro. Dysbalance between the CYR61 and APN networks may play a pathogenic role in DCMi and contain novel therapeutic targets. Multiple immune cell-associated genes were also deregulated (e.g., chemokine ligand 14, interleukin-17D, nuclear factors of activated T cells). In contrast to previous investigations in patients with advanced or end-stage DCM where etiology-related pathomechanisms are overwhelmed by unspecific processes, the deregulations detected in this study occurred at a far less severe and most probably fully reversible disease stage.

Mitochondrial aldehyde dehydrogenase attenuates hyperoxia-induced cell death through activation of ERK/MAPK and PI3K-Akt pathways in lung epithelial cells

Oxygen toxicity is one of the major risk factors in the development of the chronic lung disease or bronchopulmonary dysplasia in premature infants. Using proteomic analysis, we discovered that mitochondrial aldehyde dehydrogenase (mtALDH or ALDH2) was downregulated in neonatal rat lung after hyperoxic exposure. To study the role of mtALDH in hyperoxic lung injury, we overexpressed mtALDH in human lung epithelial cells (A549) and found that mtALDH significantly reduced hyperoxia-induced cell death. Compared with control cells (Neo-A549), the necrotic cell death in mtALDH-overexpressing cells (mtALDH-A549) decreased from 25.3 to 6.5%, 50.5 to 9.1%, and 52.4 to 15.1% after 24-, 48-, and 72-h hyperoxic exposure, respectively. The levels of intracellular and mitochondria-derived reactive oxygen species (ROS) in mtALDH-A549 cells after hyperoxic exposure were significantly lowered compared with Neo-A549 cells. mtALDH overexpression significantly stimulated extracellular signal-regulated kinase (ERK) phosphorylation under normoxic and hyperoxic conditions. Inhibition of ERK phosphorylation partially eliminated the protective effect of mtALDH in hyperoxia-induced cell death, suggesting ERK activation by mtALDH conferred cellular resistance to hyperoxia. mtALDH overexpression augmented Akt phosphorylation and maintained the total Akt level in mtALDH-A549 cells under normoxic and hyperoxic conditions. Inhibition of phosphatidylinositol 3-kinase (PI3K) activation by LY294002 in mtALDH-A549 cells significantly increased necrotic cell death after hyperoxic exposure, indicating that PI3K-Akt activation by mtALDH played an important role in cell survival after hyperoxia. Taken together, these data demonstrate that mtALDH overexpression attenuates hyperoxia-induced cell death in lung epithelial cells through reduction of ROS, activation of ERK/MAPK, and PI3K-Akt cell survival signaling pathways.

Endothelial STAT3 is essential for the protective effects of HO-1 in oxidant-induced lung injury

Administering high levels of inspired oxygen, or hyperoxia, is commonly used as a life-sustaining measure in critically ill patients. Unfortunately, the oxidant stress generated by prolonged hyperoxia can lead to respiratory failure, multiorgan failure, and death. Although the endothelial cell is known to be a target for hyperoxia-induced injury, its precise role is unclear. Heme oxygenase-1 (HO-1) and "signal transducer and activator of transcription 3" (STAT3) have been found to confer protection against endothelial cell injury. We sought to elucidate the specific roles of HO-1 and STAT3 in hyperoxic lung and endothelial cell injury. Mice or murine lung endothelial cells (MLEC) administered HO-1 siRNA exhibited marked injury and death compared with nonspecific siRNA. Overexpression of either HO-1 or STAT3 confers protection. However, HO-1 and its reaction product carbon monoxide (CO) lose their protective effects in the presence of STAT3 siRNA in MLEC or in endothelial-specific, STAT3-deficient mice. STAT3 overexpression is able to partially rescue HO-1-deficient MLEC from hyperoxia-induced cell death. Our results demonstrate 1) the importance of the endothelium in lethal hyperoxic injury, 2) HO-1 and CO require endothelial STAT3 for their protective effects, and 3) STAT3 confers endothelial cell protection via both HO-1-dependent and independent mechanisms.

Microarray and phosphokinase screenings leading to studies on ERK and JNK regulation of connective tissue growth factor expression by angiotensin II 1a and bradykinin B2 receptors in Rat1 fibroblasts

Rat1 fibroblasts stably transfected with the rat angiotensin II (AngII) AT1a and bradykinin (BK) B2 receptor cDNAs gained the ability to bind Ang II and BK. Wild-type Rat1 cells bound neither ligand. Exposure to either effector led to characteristic Galphai and Galphaq signal cascades, the release of arachidonic acid (ARA), and the intracellular accumulation of inositol phosphates (IP). Microarray analyses in response to BK or AngII showed that both receptors markedly induce the CCN family genes, CTGF (CCN2) and Cyr61 (CCN1), as well as the vasculature-related genes, Cnn1 and Egr1. Real time PCR confirmed the increased expression of connective tissue growth factor (CTGF) mRNA. Combined sequence-based analysis of gene promoter regions with statistical prevalence analyses identified CREB, SRF, and ATF-1, downstream targets of ERK, and JNK, as prominent products of genes that are regulated by ligand binding to the BK or AngII receptors. The binding of AngII or BK markedly stimulated the phosphorylation and thus the activation of ERK2, JNK, and p38MAPK. A BKB2R and an AT1aR chimera which displayed only negligible G-protein-related signaling were constructed. Both mutant receptors continued to activate these kinases and stimulate CTGF expression. Inhibitors of ERK1/2 and JNK but not p38MAPK inhibited the BK- and AngII-stimulated expression of CTGF in cells expressing either the WT or mutant receptors, illustrating that ERK and JNK participate in the control of CTGF expression in a manner that appears to be independent of G-protein. Conversely, addition of BK or AngII to the cell line expressing WT AT1aR and BKB2R downregulated the expression of collagen alpha1(I) (COL1A1) mRNA. However, these effectors did not have this effect in cells expressing the mutant receptors. Thus, a robust G-protein related response is necessary for BK or AngII to affect COL1A1 expression.