Cyr61 mediates the expression of VEGF, alphav-integrin, and alpha-actin genes through cytoskeletally based mechanotransduction mechanisms in bladder smooth muscle cells

Cyr61 delivery promotes angiogenesis during bone fracture repair

Compromised vascular supply and insufficient neovascularization impede bone repair, increasing risk of non-union. Cyr61, Cysteine-rich angiogenic inducer of 61kD (also known as CCN1), is a matricellular growth factor that is regulated by mechanical cues during fracture repair. Here, we map the distribution of endogenous Cyr61 during bone repair and evaluate the effects of recombinant Cyr61 delivery on vascularized bone regeneration. In vitro, Cyr61 treatment did not alter chondrogenesis or osteogenic gene expression, but significantly enhanced angiogenesis. In a mouse femoral fracture model, Cyr61 delivery did not alter cartilage or bone formation, but accelerated neovascularization during fracture repair. Early initiation of ambulatory mechanical loading disrupted Cyr61-induced neovascularization. Together, these data indicate that Cyr61 delivery can enhance angiogenesis during bone repair, particularly for fractures with stable fixation, and may have therapeutic potential for fractures with limited blood vessel supply.

Novel polysaccharide extracted from Sipunculus nudus inhibits HepG2 tumour growth in vivo by enhancing immune function and inducing tumour cell apoptosis

A novel polysaccharide was extracted from Sipunculus nudus (SNP). The molecular weight (MW) of SNP was determined to be 9223 Da by high‐performance gel permeation chromatography analyses, and the structure of the SNP repeat units was determined to be →3,4‐β‐D‐GlcpNAC (1→ and →4) ‐α‐D‐Glcp (1→ in the ratio of 15:1; →2) ‐α ‐D‐Galp ‐ (1→ as a side chain; and β‐D‐Galp‐(1→ and α‐ D‐Glcp ‐ (1→ as end groups by GC‐MS analysis and NMR assays. The effect of SNP on hepatoma HepG2‐bearing mice was analysed to verify its potential in the clinical treatment of liver cancer. A total of 90 male athymic nu/nu mice were divided into therapeutic and preventive groups and fed with different amounts of SNP. The antitumour effect of SNP on HepG2‐bearing mice and mechanism of such were studied by analysing the tumour size, spleen index, thymus index, immune factors in the blood, tumour apoptosis factors, etc. The results suggest that SNP not only increased the index of immune organs in the body, but also enhanced the secretion of immune factors, including interleukin‐2, interferon gamma and tumour necrosis factor‐alpha in the serum. SNP induced the apoptosis of tumour cells via the mitochondrial apoptosis pathway, which upregulated caspase‐3, caspase‐8, caspase‐9 and BCL2‐associated X, but downregulated B‐cell lymphoma‐2 and vascular endothelial growth factor protein expression. In conclusion, SNP inhibited tumour growth by enhancing immune function and inducing tumour cell apoptosis in HepG2‐bearing mice. Therefore, SNP may be further investigated as a promising candidate for future antitumour drugs.

CYR61 as a potential biomarker for the preoperative identification of muscle-invasive bladder cancers

Background

The biological behaviors, clinical treatment, prognosis of non-muscle-invasive bladder cancers (NMIBCs) and muscle-invasive bladder cancers (MIBCs) are distinct. Accurate staging is pivotal in optimal therapy planning for bladder cancers (BCs). However, it is insufficient for urologists in preoperative determining whether the tumor has invaded within the muscularis propria through cystoscope and imaging methods (CT or MRI). Therefore, searching for ideal biomarkers from the tumor tissues and urine is important for identifying the MIBCs preoperatively.

Methods

Differentially expressed genes between NMIBCs and MIBCs were identified by microarray analysis and validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical analysis. The correlation between cysteine-rich angiogenic inducer 61 (CYR61) expression and Kaplan-Meier test evaluated patients’ overall survival (OS). CYR61 protein levels were measured using enzyme-linked immunosorbent assay (ELISA) in preoperatively collected urine samples from BC patients. The receiver-operating characteristic (ROC) curve analyzed the diagnostic accuracy of uric CYR61. The siRNA mediated silencing of CYR61 in bladder carcinoma cells was performed using Lipofectamine 2000. Cell migration and invasion were assessed using wound healing and transwell assay, respectively.

Results

Differential gene expression analysis using microarray between 14 MIBCs and 16 NMIBCs human tumor samples revealed a significant increase (P<0.001) in the expression of CYR61 in MIBCs compared with NMIBCs. Higher expression of CYR61 in MIBCs was found in additional 54 tumor samples using qRT-PCR. Therefore, the overexpression of CYR61 in MIBCs could be used as a potential biomarker to distinguish between MIBCs and NMIBCs. ELISA detected elevated levels of CYR61 in the urine samples of MIBC patients (average 2.5-fold) compared with NMIBCs, with 72.7% sensitivity and 86.0% specificity to distinguish MIBCs from NMIBCs. Wound healing and transwell assays using CYR61-silenced carcinoma cells indicated the role of CYR61 in cell migration and invasion.

Conclusions

CYR61 expression is higher in MIBCs compared with NMIBCs and can serve as a promising biomarker for the preoperative diagnosis of MIBCs with prognostic value; however, multicentric prospective validation is essential for the further evaluation of CYR61.

Aberrant regulation of retinoic acid signaling genes in cerebral arterio venous malformation nidus and neighboring astrocytes

BACKGROUND

Cerebral arterio venous malformations (AVM) are a major causal factor for intracranial hemorrhage, which result in permanent disability or death. The molecular mechanisms of AVM are complex, and their pathogenesis remains an enigma. Current research on cerebral AVM is focused on characterizing the molecular features of AVM nidus to elucidate the aberrant signaling pathways. The initial stimuli that lead to the development of AVM nidus structures between a dilated artery and a vein are however not known.

METHODS

In order to understand the molecular basis of development of cerebral AVM, we used in-depth RNA sequencing with the total RNA isolated from cerebral AVM nidus. Immunoblot and qRT-PCR assays were used to study the differential gene expression in AVM nidus, and immunofluorescence staining was used to study the expression pattern of aberrant proteins in AVM nidus and control tissues. Immunohistochemistry was used to study the expression pattern of aberrant proteins in AVM nidus and control tissues.

RESULTS

The transcriptome study has identified 38 differentially expressed genes in cerebral AVM nidus, of which 35 genes were upregulated and 3 genes were downregulated. A final modular analysis identified an upregulation of ALDH1A2, a key rate-limiting enzyme of retinoic acid signaling pathway. Further analysis revealed that CYR61, a regulator of angiogenesis, and the target gene for retinoic acid signaling is upregulated in AVM nidus. We observed that astrocytes associated with AVM nidus are abnormal with increased expression of GFAP and Vimentin. Triple immunofluorescence staining of the AVM nidus revealed that CYR61 was also overexpressed in the abnormal astrocytes associated with AVM tissue.

CONCLUSION

Using high-throughput RNA sequencing analysis and immunostaining, we report deregulated expression of retinoic acid signaling genes in AVM nidus and its associated astrocytes and speculate that this might trigger the abnormal angiogenesis and the development of cerebral AVM in humans.

Exosomal encapsulation of miR-125a-5p inhibited trophoblast cell migration and proliferation by regulating the expression of VEGFA in preeclampsia

This study is aimed to examine the association between umbilical cord blood (UCB) derived exosomal microRNA (miRNA) with preeclampsia (PE) and to further explore the mechanism of a key differential gene (hsa-miR-125a-5p) in preeclampsia. Umbilical cord blood exosomal miRNA(exo-miRNA) from normal pregnant women and pregnant women with preeclampsia was processed via miRNA sequencing. Quantitative real-time polymerase chain reaction (QRT-PCR) was performed to assess the expression of miR-125a-5p in normal and PE placental tissues and peripheral blood derived exosomes in the third trimester. Human trophoblast cell line HTR8/SVneo was assigned as the negative control and miR-125a-5p mimics. QRT-PCR and Western blot were performed to identify the expressions of miR-125a-5p and vascular endothelial growth factor A (VEGFA). CCK8, flow cytometry, wound-healing and Transwell assays were used to analyze the effect of miR-125a-5p on HTR8/SVneo cell migration, proliferation, and cycle distribution. Tube formation was performed to estimate the angiogenesis ability of miR-125a-5p on HUVECs. In conclusion, miR-125a-5p expression in PE placental tissues was higher than in normal subjects, while the expression of VEGFA was lower in PE placental tissues. We then compared the miR-125a-5p mimics group with the negative control group and found that in the mimics group, the cell migration, proliferation and angiogenesis abilities were decreased, and more cells were arrested in the S stage. Our study systematically profiled the UCB exo-miRNA in normal and PE pregnant women and demonstrated that dysregulation of miR-125a-5p might affect HTR8/SVneo cell proliferation and migration and inhibit angiogenesis by regulating VEGFA, indicating that miR-125a-5p is involved in the progression of PE.

CYR61, a potential biomarker of tumor inflammatory response in epithelial ovarian cancer microenvironment of tumor progress

Background

Recent studies have found that inflammatory response is involved in the pathogenesis of ovarian cancer. Advanced ovarian cancer is often presented with ascites that is rich in cytokines, inflammatory factors or cancer cells. Therefore, it is important to study the microenvironment of ascites in order to further clarify the occurrence and progression of ovarian cancer. As a pro-inflammatory factor, the Cyr61 expression patterns are inconsistent in human tumors. Although it has been reported that Cyr61 is related to the progression of ovarian cancer, its specific mechanism is not yet clear. This study sought to evaluate the Cyr61 levels of ascites, serum and different tissues of ovarian cancer to explore the potential association of Cyr61with the tumor-associated inflammatory microenvironment of EOC.

Methods

Tumor specimens were procured from patients with ovarian serous cystadenocarcinoma and ovarian serous cystadenoma. Cyr61 and IL-6 levels of serum or ascites were determined by ELISA (Enzyme-Linked ImmunoSorbent Assay), while Cyr61 expressions of different ovarian tumor tissues were evaluated by IHC (Immunohistochemistry). Then the correlation of Cyr61 level in ascites with clinicopathologic features was analyzed. And other laboratory data were obtained from medical records.

Results

Both in ascites and serum, significantly higher Cyr61 levels were found in ovarian serous cystadenocarcinoma. In malignant ascites, higher Cyr61 level of ovarian serous cystadenocarcinoma was more closely associated with FIGO stage, initial tumor size > 10 cm and the residual tumor size. And the increased IL-6 level was linearly related to Cyr61 level. Moreover, the serum levels of Cyr61, IL-6 and CRP in advanced stage of ovarian cancer were much higher than those in early stage. Lastly, the IHC data demonstrate that Cyr61 expression of ovarian serous adenocarcinoma was higher than that of ovarian serous cystadenoma, but it was lower than the paired metastatic lesions.

Conclusions

As a pro-inflammatory factor, increased ascites Cyr61 level is associated with FIGO stage, initial tumor size > 10 cm and the residual tumor size. Moreover, serum Cyr61 may be used as a potential marker for EOC inflammatory response. Finally, Cyr61 may be involved in the process of tumor metastasis and progression by producing IL-6 and CRP in the EOC inflammatory microenvironment.

Responses of bladder smooth muscle to the stretch go through extracellular signal-regulated kinase (ERK)/p90 ribosomal S6 protein kinase (p90RSK)/Nuclear factor-κB (NF-κB) Pathway

AIMS

The present study was designed to study changes and its potential mechanisms in human bladder smooth muscle subjected to stretch.

METHODS

Bioinformatics analyses including differential expression analysis, overrepresentation enrichment analysis, principal component analysis, and weighted gene coexpression network analysis were used to analyze a microarray dataset (GSE47080) of partial bladder outlet obstruction (pBOO) in rat to find the potential changes of gene expressions. Bladder from pBOO model and human bladder smooth muscle cells (HBSMCs) subjected to sustained prolonged stretch were collected for Western blot analysis, real-time polymerase chain reaction, and fluorescence analysis to verify the changes of gene expressions and preliminarily study the potential role of signaling pathway regulation in treatment of pBOO.

RESULTS

The bioinformatics analysis showed that chronic obstruction activated mitogen-activated protein kinase pathway and changed cytoskeleton structure in bladder smooth muscle. In in vivo experiments in mice, pBOO was verified by cystometry. Partial BOO activated the extracellular signal-regulated kinase (ERK)/p90 ribosomal S6 protein kinase (p90RSK)/nuclear factor-κB (NF-κB) signaling pathway in DM. The messenger RNA (mRNA) expressions of contractile phenotypic proteins increased after pBOO. In in vitro experiments of HBSMCs, mechanical stretch activated ERK/p90RSK/NF-κB in HBSMCs in a time-dependent manner. The mRNA expressions of α-smooth muscle actin and SM22 also increased and filamentous actin (F-actin) polymerization was enhanced as well. Inhibition of ERK/p90RSK/NF-κB pathway reversed mechanical stretch-induced changes of contractile phenotypic expression and F-action polymerization.

CONCLUSIONS

Continuous stretch increases expressions of contractile phenotypic proteins and promotes the polymerization of F-actin. This process partially goes through ERK/p90RSK/NF-κB pathway.

CYR61 improves muscle force recreation in a rabbit trauma model

BACKGROUND

Critically elevated compartment pressures after complicated tibial fractures may result in fibrosis and therefore scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Cysteine-rich angiogenic inducer 61 (CYR61) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring or improve angiogenesis after acute musculoskeletal trauma.

OBJECTIVE

We researched whether local application of CYR61 (1) restores muscle force, (2) reduces scar tissue formation, and (3) improves angiogenesis.

METHODS

We generated acute soft tissue trauma with temporary ischemia and increased compartment pressure in 22 rabbits and shortened the limbs to simulate surgical fracture debridement. In the test group, a CYR61-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after trauma we euthanized the animals and histologically determined the percentage of connective and muscle tissue. Immunohistology was performed to analyze angiogenesis.

RESULTS

Recovery of preinjury muscle strength was significantly greater in the CYR61 group (2.8 N; 88%) as compared to the control (1.8 N; 53%) with a moderate reduction of connective tissue (9.9% vs. 8.5%). Immunohistochemical staining showed that blood vessel formation increased significantly (trauma vs. control 38.75 ± 27.45 mm2 vs. 24.16 ± 19.81 mm2).

CONCLUSIONS

Local application of CYR61 may improve restoration of muscle force and accelerate muscle force recovery by improving angiogenesis and moderately reducing connective tissue.

Unchain My Heart: Integrins at the Basis of iPSC Cardiomyocyte Differentiation

The cellular response to the extracellular matrix (ECM) microenvironment mediated by integrin adhesion is of fundamental importance, in both developmental and pathological processes. In particular, mechanotransduction is of growing importance in groundbreaking cellular models such as induced pluripotent stem cells (iPSC), since this process may strongly influence cell fate and, thus, augment the precision of differentiation into specific cell types, e.g., cardiomyocytes. The decryption of the cellular machinery starting from ECM sensing to iPSC differentiation calls for new in vitro methods. Conveniently, engineered biomaterials activating controlled integrin-mediated responses through chemical, physical, and geometrical designs are key to resolving this issue and could foster clinical translation of optimized iPSC-based technology. This review introduces the main integrin-dependent mechanisms and signalling pathways involved in mechanotransduction. Special consideration is given to the integrin-iPSC linkage signalling chain in the cardiovascular field, focusing on biomaterial-based in vitro models to evaluate the relevance of this process in iPSC differentiation into cardiomyocytes.

Stretch-induced Expression of CYR61 Increases the Secretion of IL-8 in A549 Cells via the NF-κβ/lκβ Pathway

Mechanical ventilation (MV) with large tidal volumes can increase lung alveolar permeability and initiate inflammatory responses, resulting in ventilator-induced lung injury (VILI). The mechanisms of the injurious effects of MV and the genetic susceptibility remain unclear. VILI-related genes such as cysteine-rich angiogenic inducer 61 (Cyr61) have been demonstrated to play a detrimental role in the aggressive ventilation strategies. In the present study, we investigated the involvement of Cyr61 in the VILI and the underlying mechanism. A549 cells were exposed to cyclic stretch of varying durations and then the mRNA and protein levels of Cyr61 were measured by real-time PCR and Western blotting, respectively. Additionally, after exposure of A549 cells to cyclic stretch for 5 min to 1 h,the expression levels of nuclear factor kappaB (NF-κB) and IL-8 were detected by E L I S A and Western blotting. Thereafter, Cyr61 expression was depressed in A549 cells with the siRNA pGenesil1.1-Cyr61-3 before the cyclic stretch, and IL-8 secretion and the activation of NF-κB pathways were probed by ELISA and Western blotting, respectively. Moreover, A NF-κB inhibitor (PDTC) and an activator (TNF) were used before mechanical stretch. Realtime PCR and ELISA were performed to detect the mRNA and protein of IL-8, respectively. The results showed that the mechanical cyclic stretch led to increased Cyr61 expression at mRNA and protein levels in A549 cells. Additionally, cyclic stretch also mobilized NF-κB from the cytoplasm to the nucleus and increased IL-8 secretion in A549 cells. The inhibition of Cyr61 blocked the NF-κB activation and IL-8 secretion in response to cyclic stretch. Inhibition of NF-κB attenuated the mRNA and protein expression of IL-8 in A549 cells transfected with Cyr61 siRNA. It was suggested that Cyr61/NF-κB signaling pathway mediates the upregulation of IL-8 in response to cyclic stretch in A594 cells. These findings support the hypothesis that Cyr61 plays a critical role in acute lung inflammation triggered by mechanical strain.

CYR61/CCN1 Regulates Sclerostin Levels and Bone Maintenance

CYR61/CCN1 is a matricellular protein that resides in the extracellular matrix, but serves regulatory rather than structural roles. CYR61/CCN1 is found in mineralized tissues and has been shown to influence bone healing in vivo and osteogenic differentiation in vitro. In this study we generated Cyr61 bone-specific knockout mice to examine the physiological role of CYR61/CCN1 in bone development and maintenance in vivo. Extensive analysis of Cyr61 conditional knockout mice showed a significant decrease in both trabecular and cortical bone mass as compared to WT littermates. Our data suggest that CYR61/CCN1 exerts its effects on mature osteoblast/osteocyte function to modulate bone mass. Specifically, changes were observed in osteocyte/osteoblast expression of RankL, VegfA, and Sost. The increase in RankL expression was correlated with a significant increase in osteoclast number; decreased VegfA expression was correlated with a significant decrease in bone vasculature; increased Sost expression was associated with decreased Wnt signaling, as revealed by decreased Axin2 expression and increased adiposity in the bone marrow. Although the decreased number of vascular elements in bone likely contributes to the low bone mass phenotype in Cyr61 conditional knockout mice, this cannot explain the observed increase in osteoclasts and the decrease in Wnt signaling. We conducted in vitro assays using UMR-106 osteosarcoma cells to explore the role CYR61/CCN1 plays in modulating Sost mRNA and protein expression in osteocytes and osteoblasts. Overexpression of CYR61/CCN1 can suppress Sost expression in both control and Cyr61 knockout cells, and blocking Sost with siRNA can rescue Wnt responsiveness in Cyr61 knockout cells in vitro. Overall, our data suggest that CYR61/CCN1 modulates mature osteoblast and osteocyte function to regulate bone mass through angiogenic effects as well as by modulating Wnt signaling, at least in part through the Wnt antagonist Sost. © 2018 American Society for Bone and Mineral Research.

TLR9 (Toll-Like Receptor 9) Agonist Suppresses Angiogenesis by Differentially Regulating VEGFA (Vascular Endothelial Growth Factor A) and sFLT1 (Soluble Vascular Endothelial Growth Factor Receptor 1) in Preeclampsia

Preeclampsia is a common pregnancy-specific disorder characterized by elevated blood pressure and proteinuria. Activation of the maternal immune system and impaired placental angiogenesis are thought to contribute to the pathogenesis of preeclampsia. TLR9 (Toll-like receptor 9) plays a role in innate immunity, defending the organism against infection. The purpose of this study was to determine whether TLR9 inhibits angiogenesis at the fetomaternal interface under conditions of preeclampsia. We confirmed the downregulation of VEGFA (vascular endothelial growth factor A) and upregulation of TLR9 and sFLT1 (soluble vascular endothelial growth factor receptor 1) in placentas from preeclamptic women. Then, we established a mouse model with preeclampsia-like symptoms using the synthetic TLR9 agonist CpG (cytidine-phosphate-guanosine)-ODN (oligodeoxynucleotide; ODN1826). We observed the downregulation of VEGFA and the upregulation of sFLT1 in placentas from the preeclampsia-like animal model and in trophoblasts treated with CpG-ODN (ODN2006). In addition, silencing TLR9 promoted the migration and invasion of HTR8/SVneo cells. In conclusion, TLR9 is capable of robustly suppressing angiogenesis by differentially regulating the expression of VEGFA and sFLT1 at the fetomaternal interface, potentially contributing to the development of preeclampsia.

Cardiovascular Risk Factors and Markers

Cardiovascular risk is assessed for the prediction and appropriate management of patients using collections of identified risk markers obtained from clinical questionnaire information, concentrations of certain blood molecules (e.g., N-terminal proB-type natriuretic peptide fragment and soluble receptors of tumor-necrosis factor-α and interleukin-2), imaging data using various modalities, and electrocardiographic variables, in addition to traditional risk factors.

High expression levels of Cyr61 and VEGF are associated with poor prognosis in osteosarcoma

Cysteine Rich Angiogenic Inducer 61 (Cyr61) and Vascular Endothelial Growth Factor (VEGF) are signaling proteins involved in the regulation of tumor angiogenesis and progression. The purpose of this study was to investigate the clinicopathological and prognostic significance of Cyr61 and VEGF expressions in osteosarcoma. Immunohistochemical staining was performed to evaluate the expression of both the proteins in 84 osteosarcoma samples. Correlation between Cyr61/VEGF expressions and clinicopathological parameters was determined using Rank sum test and Spearman's rank correlation coefficient. Prognostic factors were identified using univariate and multivariate Cox regression analysis. The expressions of Cyr61 and VEGF were weak in 26.2% and 17.9%, moderate in 26.2% and 23.8%, and strong in 47.6% and 58.3% of osteosarcoma samples, respectively. Cyr61 and VEGF expressions moderately correlated with each other in osteosarcoma, and exhibited significant association with Enneking stage and distant metastasis. In addition, the high expression of both proteins significantly correlated with short overall survival time in these patients. The key finding in this study was that both Cyr61 and VEGF expressions were independent prognostic indicators of overall survival. In summary, our results indicate that expression of Cyr61 and VEGF may serve as important prognostic predictors in patients with osteosarcoma.

Dissection of mechanoresponse elements in promoter sites of the mechanoresponsive CYR61 gene

Mechanotransduction is important for mesenchymal regeneration and differentiation. Exaggerated high or very low impact yields pathological outcome resulting in fracture or tissue atrophy. Pathological strain in animal models was described but tools to dissect the respective stimuli and downstream pathways are limited. We expand the analytical tools to describe DNA strain response elements in a reporter gene approach. Deletion constructs of the human cysteine-rich protein 61 (CYR61) promoter were cloned into luciferase vectors and stably transfected into human telomerase-immortalised mesenchymal stem cells (hMSC-TERT). Cells were mechanically stimulated with variable frequencies, amplitudes and durations. Promoter activity was determined as well as CYR61 mRNA and protein expression. In silico promoter analysis identified putative transcription factor binding sites, one of which was a cAMP response element, verified by electrophoretic mobility shift assay. We demonstrate for the first time that the activity of promoter regions is inhibited in low, but stimulated in high frequency stimulations. We conclude that by varying conditions of mechanical strain it is possible to characterize stimulatory versus inhibitory strain on cellular levels. Our work may be helpful in future studies to dissect the molecular pathways of physiological versus pathological strain and may have implications for clinical exercise based treatment strategies.

Cysteine‑rich 61 RNA interference inhibits pathological angiogenesis via the phosphatidylinositol 3‑kinase/Akt‑vascular endothelial growth factor signaling pathway in endothelial cells

Hypoxia is a key factor in the pathogenesis of angiogenesis, and cysteine‑rich 61 (CCN1), an angiogenic factor, is involved in the development of pathological angiogenesis. The aim of the present study was to investigate the mechanism of CCN1 RNA interference (RNAi)‑induced inhibition of hypoxia‑induced pathological angiogenesis in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions in vitro. The effects of inhibiting phosphoinositide 3‑kinase (PI3K)/Akt signaling using LY294002 were investigated in hypoxic HUVECs. The proliferation and apoptosis of HUVECs under hypoxia were assessed using CCN1 RNAi. The CCN1‑PI3K/Akt‑vascular endothelial growth factor (VEGF) pathway was analyzed under hypoxic conditions using reverse transcription‑quantitative polymerase chain reaction and western blotting. CCN1 RNAi inhibited the proliferation and induced the apoptosis of the HUVECs under hypoxia, with hypoxia significantly increasing the mRNA and protein expression levels of CCN1, Akt and VEGF. By contrast, CCN1 RNAi reduced the mRNA and protein expression levels of CCN1, Akt and VEGF in the HUVECs (P<0.05). Furthermore, LY294002 reduced the mRNA and protein expression levels of CCN1 in the hypoxic cells (P<0.05). These data indicated that CCN1 inhibits apoptosis and promotes proliferation in HUVECs. Therefore, CCN1 RNAi may offer a novel therapeutic strategy, which may aid in the treatment of pathological angiogenesis via inhibition of the PI3K/Akt‑VEGF pathway.

Regulating the regulators of angiogenesis by CCN1 and taking it up a Notch

CCN1 is encoded by an extracellular matrix protein-gene that is essential for the proper development of the cardiovascular system and the control of angiogenesis, inflammation, progenitor cell lineage commitment and extracellular matrix protein remodeling during the adult life. High-precision genetic models of tissue-specific gene deletion demonstrated a pivotal role of CCN1 in providing positional information to angiogenic endothelial cells (ECs) during the outgrowth and maturation of nascent blood vessel sprouts, fine-controlling Notch-dependent inter-endothelial cell communications and mediating interaction with inflammatory cells. Some of these pleiotropic activities of CCN1 are unique among proteins of the extracellular matrix. Thus, CCN1 represents a model molecule for investigating and unraveling novel aspects of extracellular protein signaling in vascular development and diseases.

The Role of Genetically Modified Mesenchymal Stem Cells in Urinary Bladder Regeneration

Recent studies have demonstrated that mesenchymal stem cells (MSCs) combined with CD34⁺ hematopoietic/stem progenitor cells (HSPCs) can function as surrogate urinary bladder cells to synergistically promote multi-faceted bladder tissue regeneration. However, the molecular pathways governing these events are unknown. The pleiotropic effects of Wnt5a and Cyr61 are known to affect aspects of hematopoiesis, angiogenesis, and muscle and nerve regeneration. Within this study, the effects of Cyr61 and Wnt5a on bladder tissue regeneration were evaluated by grafting scaffolds containing modified human bone marrow derived MSCs. These cell lines were engineered to independently over-express Wnt5a or Cyr61, or to exhibit reduced expression of Cyr61 within the context of a nude rat bladder augmentation model. At 4 weeks post-surgery, data demonstrated increased vessel number (~250 vs ~109 vessels/mm²) and bladder smooth muscle content (~42% vs ~36%) in Cyr61OX (over-expressing) vs Cyr61KD (knock-down) groups. Muscle content decreased to ~25% at 10 weeks in Cyr61KD groups. Wnt5aOX resulted in high numbers of vessels and muscle content (~206 vessels/mm² and ~51%, respectively) at 4 weeks. Over-expressing cell constructs resulted in peripheral nerve regeneration while Cyr61KD animals were devoid of peripheral nerve regeneration at 4 weeks. At 10 weeks post-grafting, peripheral nerve regeneration was at a minimal level for both Cyr61OX and Wnt5aOX cell lines. Blood vessel and bladder functionality were evident at both time-points in all animals. Results from this study indicate that MSC-based Cyr61OX and Wnt5aOX cell lines play pivotal roles with regards to increasing the levels of functional vasculature, influencing muscle regeneration, and the regeneration of peripheral nerves in a model of bladder augmentation. Wnt5aOX constructs closely approximated the outcomes previously observed with the co-transplantation of MSCs with CD34⁺ HSPCs and may be specifically targeted as an alternate means to achieve functional bladder regeneration.

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.

Cyclic hydrodynamic pressure induced proliferation of bladder smooth muscle cells via integrin alpha5 and FAK

According to previous studies, integrins play an important role in the mechanotransduction. The aim of this study was to examine the role of integrin subunits and its down-stream signaling molecules in the cyclic hydrodynamic pressure-induced proliferation of human bladder smooth muscle cells (HBSMCs) cultured in scaffolds. The HBSMCs cultured in scaffolds were subjected to four different levels of cyclic hydrodynamic pressure for 24 hours, which were controlled by a BOSE BioDynamic bioreactor. Flow cytometry was used to examine cell cycle distribution. Real-time RT-PCR and western blotting were used to examine the expression levels of integrin subunits and their downstream signaling molecules. Integrin alpha5 siRNA was applied to validate the role of integrin alpha5 in cell proliferation. Here, we showed that cyclic hydrodynamic pressure promoted proliferation of HBSMCs. The cyclic hydrodynamic pressure also increased expression of integrin alpha5 and phosphorylation of FAK, the key mediator of integrin alpha5 signaling, but not that of integrin alpha1, alpha3, alpha4, alphav, beta1 and beta3. Moreover, inhibition of integrin alpha5 decreased the level of p-FAK and abolished proliferation of HBSMCs stimulated by cyclic hydrodynamic pressure. Taken together, we demonstrate for the ?rst time that the integrin alpha5-FAK signaling pathway controls the proliferation of HBSMCs in response to cyclic hydrodynamic pressure.

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.

High bias gas flows increase lung injury in the ventilated preterm lamb

BACKGROUND

Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI), leading to the development of bronchopulmonary dysplasia (BPD). It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI.

METHODS

Preterm lambs of 131 days' gestation (term = 147 d) were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13), 18 L/min (n = 12) or 28 L/min (n = 14). Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate.

RESULTS

High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung.

CONCLUSIONS

High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

Cyclic stretch-induced thrombin generation by rat vascular smooth muscle cells is mediated by the integrin αvβ3 pathway

AIMS

Vascular smooth muscle cell (VSMC) phenotypic modulation plays a pivotal role in atherothrombotic diseases. Thrombin generation at the surface of VSMCs and activation of integrin mechanotransduction pathways represent potential mechanisms. Here, we examine whether mechanical stretch increases thrombin generation on cultured rat aortic VSMCs.

METHODS AND RESULTS

The integrin α(v)β(3) antagonist peptide (cRGDPV) dose-dependently decreased thrombin generation without stretch. Static stretch (5%, 1 Hz) failed to modify the thrombin-forming capacity of VSMCs, whereas 10% cyclic stretch during 60 and 360 min enhanced integrin α(v)β(3) expression and thrombin generation at the surface of VSMCs by 30% without inducing apoptosis. Cyclic stretch also stimulated Src phosphorylation, cleavage of talin, and binding of prothrombin to VSMCs. Upregulation of α(v)β(3) expression, Src phosphorylation, and enhanced thrombin generation by cyclic stretch were abolished by cRGDPV and silencing RNA (siRNA) against α(v) as well as by selective inhibition of integrin α(v)β(3) inside-out signalling by a talin-siRNA. Complete abolition of stretch-induced VSMC-supported thrombin generation by the RGT peptide, which disrupts the interaction of Src with the β(3) cytoplasmic tail, demonstrates the link between outside-in pathways involving β(3)-Src interaction and thrombin activity dependent on inside-out signalling.

CONCLUSION

These data show that the contribution of cyclic stretch to VSMC-supported thrombin generation is driven by the integrin α(v)β(3) signalling pathway and suggest a role for pulsatility-induced intramural thrombin in VSMC-dependent vascular remodelling.

Acute impact of intermittent pneumatic leg compression frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression in humans

The mechanisms by which intermittent pneumatic leg compression (IPC) treatment effectively treats symptoms associated with peripheral artery disease remain speculative. With the aim of gaining mechanistic insight into IPC treatment, the purpose of this study was to investigate the effect of IPC frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression. In this two study investigation, healthy male subjects underwent an hour of either high-frequency (HF; 2-s inflation/3-s deflation) or low-frequency (LF; 4-s inflation/16-s deflation) IPC treatment of the foot and calf. In study 1 (n = 11; 23.5 ± 4.7 yr), subjects underwent both HF and LF treatment on separate days. Doppler/ultrasonography was used to measure popliteal artery diameter and blood velocity at baseline and during IPC treatment. Flow-mediated dilation (FMD) and peak reactive hyperemia blood flow (RHBF) were determined before and after IPC treatment. In study 2 (n = 19; 22.0 ± 4.6 yr), skeletal muscle biopsies were taken from the lateral gastrocnemius of the treated and control limb at baseline and at 30- and 150-min posttreatment. Quantitative PCR was used to assess mRNA concentrations of genes associated with inflammation and vascular remodeling. No treatment effect on vascular function was observed. Cuff deflation resulted in increased blood flow (BF) and shear rate (SR) in both treatments at the onset of treatment compared with baseline (P < 0.01). BF and SR significantly diminished by 45 min of HF treatment only (P < 0.01). Both treatments reduced BF and SR and elevated oscillatory shear index compared with baseline (P < 0.01) during cuff inflation. IPC decreased the mRNA expression of cysteine-rich protein 61 from baseline and controls (P <0 .01) and connective tissue growth factor from baseline (P < 0.05) in a frequency-dependent manner. In conclusion, a single session of IPC acutely impacts limb hemodynamics and skeletal muscle gene expression in a frequency-dependent manner but does not impact vascular function.

Elevation of angiogenic factor Cysteine-rich 61 levels in vitreous of patients with proliferative diabetic retinopathy

PURPOSE

Cysteine-rich 61 (Cyr61) is one of the angiogenic factors involved in proliferative diabetic retinopathy (PDR). To further investigate its role, we measure and compare the vitreous levels of Cyr61 and vascular endothelial growth factor in patients with PDR and to localize Cyr61 expression in associated proliferative epiretinal membranes.

METHODS

Vitreous obtained from 56 patients with active PDR, 16 patients with active PDR pretreated with bevacizumab, 19 patients with quiescent PDR, 15 non-PDR patients with diabetic macular edema, and 25 patients with non-diabetic-related eye diseases were subjected to enzyme-linked immunosorbent assay for Cyr61 and vascular endothelial growth factor levels. Epiretinal membranes from 18 patients were stained immunohistochemically for Cyr61.

RESULTS

Vitreous Cyr61 levels were significantly higher in active PDR patients, quiescent PDR patients, and diabetic macular edema patients compared with non-diabetic control patients (P < 0.01). Pretreatment of bevacizumab significantly suppressed vitreous vascular endothelial growth factor levels; however, it did not inhibit vitreous Cyr61 levels in active PDR patients. Cysteine-rich 61 was strongly detected in endothelial cells and myofibroblasts within active PDR membranes but not in idiopathic epiretinal membrane.

CONCLUSION

Vitreous Cyr61 levels were related to different states of PDR and correlated with vascular endothelial growth factor levels in PDR patients. Pretreatment of bevacizumab did not inhibit vitreous Cyr61 levels in active PDR patients. Cysteine-rich 61 might mediate angiogenesis and post-angiogenic fibrosis in PDR.

Airway response to acute mechanical stress in a human bronchial model of stretch

INTRODUCTION

Lung inflation may have deleterious effects on the alveoli during mechanical ventilation. However, the consequences of stretch during excessive lung inflation on basal tone and responsiveness of human bronchi are unknown. This study was undertaken to devise an experimental model of acute mechanical stretch in isolated human bronchi and to investigate its effect on airway tone and responsiveness.

METHODS

Bronchi were removed from 48 thoracic surgery patients. After preparation and equilibration in an organ bath, bronchial rings were stretched for 5 min using a force (2.5 × basal tone) that corresponded to airway-inflation pressure > 30 cm H₂O. The consequences of stretch were examined by using functional experiments, analysis of organ-bath fluid, and ribonucleic acid (RNA) isolation from tissue samples.

RESULTS

Following removal of the applied force the airways immediately developed an increase in basal tone (P < 0.0001 vs. paired controls) that was sustained and it did so without significantly increasing responsiveness to acetylcholine. The spontaneous tone was abolished with a Rho-kinase inhibitor and epithelium removal, a leukotriene antagonist or nitric oxide synthase inhibitors reduced it, whereas indomethacin, sensory nerve inhibitors or antagonists for muscarinic, endothelin and histamine receptors had no effect. Stretch enhanced leukotriene-E4 production during the immediate spontaneous contraction of human bronchi (P < 0.05). Moreover, stretch up-regulated the early mRNA expression of genes involved in wingless-type mouse mammary tumor virus integration-site family (WNT)-signaling and Rho-kinase pathways.

CONCLUSIONS

Stretching human bronchi for only 5 min induces epithelial leukotriene release via nitric oxide synthase activation and provokes a myogenic response dependent on Rho-kinase and WNT-signaling pathways. From a clinical perspective, these findings highlight the response of human airway to acute mechanical stress during excessive pulmonary inflation.

Selective blockade of cytoskeletal actin remodeling reduces experimental choroidal neovascularization

PURPOSE

The efficacy of the peptide Ac-EEED on reducing cell adhesion and proliferation in vitro and choroidal neovascularization (CNV) in vivo was examined.

METHODS

The peptide chimera containing the Ac-EEED sequence was chemically linked to the N terminus of the XMTM delivery peptide from the E(rns) viral surface protein. Ac-EEED or scrambled control peptide (SCRAM) was added to cultures of vascular smooth muscle cells, pericytes, endothelial cells, and fibroblasts, and adhesion, growth, and matrix production was assessed. Ac-EEED or SCRAM was injected into the vitreous of mice undergoing laser rupture of Bruch's membrane to induce CNV and lesion volume, neovascularization and lesion fibrosis were assessed.

RESULTS

Ac-EEED-induced changes in the morphology of the actin cytoskeleton by inhibiting polymerization of G-actin and disrupting the formation of stress fibers. Pretreatment with Ac-EEED resulted in endothelial cells becoming less responsive to the mitogenic and pro-adhesive effects of VEGF. Ac-EEED treatment in fibroblasts reduced TGF-β-induced fibrosis as assessed by decreased levels of connective tissue growth factor, cysteine-rich 61, collagen I (COL1A2), and collagen III (COL3A1). CNV lesion size and fibrosis were reduced in a concentration-dependent manner by up to 60%.

CONCLUSIONS

In vitro studies showed that Ac-EEED affects a broad range of mechanical properties associated with cytoskeletal actin to reduce growth factor effects. The utilization of Ac-EEED in vivo may offer a novel therapeutic strategy by both suppressed neovessel growth and curtailing fibrosis typically associated with the involutional stage of CNV.

The matricellular protein cysteine-rich protein 61 (CCN1/Cyr61) enhances physiological adaptation of retinal vessels and reduces pathological neovascularization associated with ischemic retinopathy

Retinal vascular damages are the cardinal hallmarks of retinopathy of prematurity (ROP), a leading cause of vision impairment and blindness in childhood. Both angiogenesis and vasculogenesis are disrupted in the hyperoxia-induced vaso-obliteration phase, and recapitulated, although aberrantly, in the subsequent ischemia-induced neovessel formation phase of ROP. Yet, whereas the histopathological features of ROP are well characterized, many key modulators with a therapeutic potential remain unknown. The CCN1 protein also known as cysteine-rich protein 61 (Cyr61) is a dynamically expressed, matricellular protein required for proper angiogenesis and vasculogenesis during development. The expression of CCN1 becomes abnormally reduced during the hyperoxic and ischemic phases of ROP modeled in the mouse eye with oxygen-induced retinopathy (OIR). Lentivirus-mediated re-expression of CCN1 enhanced physiological adaptation of the retinal vasculature to hyperoxia and reduced pathological angiogenesis following ischemia. Remarkably, injection into the vitreous of OIR mice of hematopoietic stem cells (HSCs) engineered to express CCN1 harnessed ischemia-induced neovessel outgrowth without adversely affecting the physiological adaptation of retinal vessels to hyperoxia. In vitro exposure of HSCs to recombinant CCN1 induced integrin-dependent cell adhesion, migration, and expression of specific endothelial cell markers as well as many components of the Wnt signaling pathway including Wnt ligands, their receptors, inhibitors, and downstream targets. CCN1-induced Wnt signaling mediated, at least in part, adhesion and endothelial differentiation of cultured HSCs, and inhibition of Wnt signaling interfered with normalization of the retinal vasculature induced by CCN1-primed HSCs in OIR mice. These newly identified functions of CCN1 suggest its possible therapeutic utility in ischemic retinopathy.

Regulation of Cyr61/CCN1 expression by hypoxia through cooperation of c-Jun/AP-1 and HIF-1α in retinal vascular endothelial cells

Hypoxia is the most important factor in the pathogenesis of diabetic retinopathy. Cysteine-rich 61 (Cyr61) is one of the angiogenic factors involved in the development of proliferative diabetic retinopathy (PDR). The aim of this study was to investigate the mechanism of hypoxia-induced Cyr61 expression in retinal vascular endothelial cells. The hypoxia-induced expression of mRNA and protein of Cyr61 was studied in monkey choroidal retinal vascular endothelial (RF/6A) cells. Luciferase reporter assays and electrophoretic mobility shift assays were used to identify the hypoxia responsible region and transcription factors in the Cyr61 promoter. Chromatin immunoprecipitation and immunoprecipitation were performed to study the role of hypoxia-inducible factor (HIF)-1α and c-Jun/activator protein-1 (AP-1) in Cyr61 transcriptional regulation. The results showed that hypoxia significantly induced Cyr61 mRNA and protein expression in RF/6A cells. The effect was mediated through phosphorylation of c-Jun. Luciferase assays, electrophoretic mobility shift assays, chromatin immunoprecipitation and immunoprecipitation showed that HIF-1α interacted with c-Jun/AP-1 and their binding on the AP-1 binding motif within the Cyr61 promoter induced the expression of Cyr61. In conclusion, hypoxia controlled the transcriptional regulation of the Cyr61 gene in RF/6A cells by cooperation of HIF-1α and c-Jun/AP-1. Cyr61 might play an important role in ischemic retinal diseases, such as PDR.

MicroRNA-155 contributes to preeclampsia by down-regulating CYR61

OBJECTIVE

The aim of this study was to characterize the molecular mechanism of preeclampsia (PE) development through miR-155.

STUDY DESIGN

PE and normal placentas were used to measure miR-155 and cysteine-rich protein 61 (CYR61) expression. CYR61 3' untranslated region was validated as the target of miR-155 using in vitro transfections. miR-155 and CYR61 expression levels were assessed by real-time reverse transcription polymerase chain reaction or Western blot.

RESULTS

An inverse correlation was found between miR-155 and CYR61 expression levels, with miR-155 up-regulated and CYR61 down-regulated in PE tissues. Luciferase assays and CYR61 transfection assays experimentally validated that miR-155 efficiently targets the 3' untranslated region of CYR61.

CONCLUSION

This study reported for the first time that overexpression of miR-155 contributes to PE development by targeting and down-regulating angiogenic regulating factor CYR61, leading to pathological alterations. This finding not only characterizes a new mechanism for the disease but also provides a potential therapeutic target.

Vascular endothelial growth factor and bladder from a different perspective: not only an angiogenic factor

Angiogenesis has a key role for embryonic development and is crucial in several major diseases. Molecular basis of angiogenesis has been widely investigated (J Biochem Mol Biol. 2006;39:469-478, Oncogene. 2000;19:5598-5605). In this review, vascular endothelial growth factor (VEGF) and related receptors and their key roles in embryonic bladder development are discussed. The normal VEGF expression and related angiogenesis pattern of embryonic bladder are highlighted. The VEGF family especially VEGF-A is the major player in angiogenesis as well as many other angiogenic factors and activates 2 tyrosine kinase receptors, VEGFR-1 and VEGFR-2 (J Biochem Mol Biol. 2006;39:469-478). Besides its worthy role in angiogenesis, VEGF-A also seems to participate in normal bladder development (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225). In previous studies, we have shown that exogenous VEGF or hypoxia-induced endogenous upregulation of this protein accelerates the growth of the bladder by detrusor and urothelium hypertrophy and hyperplasia (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225, Dev Biol. 1997;183:139-149, Neurourol Urodyn. 2004;23:342-348). This abrupt role of VEGF on detrusor muscle through a hypoxic pathway may potentially be a part of the solution for many urologic conditions such as remodeling of detrusor muscle in antenatal bladder outlet obstruction.

Role of the actin cytoskeleton in tuning cellular responses to external mechanical stress

Mechanical forces are essential for tissue homeostasis. In adherent cells, cell-matrix adhesions connect the extracellular matrix (ECM) with the cytoskeleton and transmit forces in both directions. Integrin receptors and signaling molecules in cell-matrix adhesions transduce mechanical into chemical signals, thereby regulating many cellular processes. This review focuses on how cellular mechanotransduction is tuned by actin-generated cytoskeletal tension that balances external with internal mechanical forces. We point out that the cytoskeleton rapidly responds to external forces by RhoA-dependent actin assembly and contraction. This in turn induces remodeling of cell-matrix adhesions and changes in cell shape and orientation. As a consequence, a cell constantly modulates its response to new bouts of external mechanical stimulation. Changes in actin dynamics are monitored by MAL/MKL-1/MRTF-A, a co-activator of serum response factor. Recent evidence suggests that MAL is also involved in coupling mechanically induced changes in the actin cytoskeleton to gene expression. Compared with other, more rapid and transient signals evoked at the cell surface, this parallel mechanotransduction pathway is more sustained and provides spatial and temporal specificity to the response. We describe examples of genes that are regulated by mechanical stress in a manner depending on actin dynamics, among them the ECM protein, tenascin-C.

Early biomarkers and potential mediators of ventilation-induced lung injury in very preterm lambs

Background

Bronchopulmonary dysplasia (BPD) is closely associated with ventilator-induced lung injury (VILI) in very preterm infants. The greatest risk of VILI may be in the immediate period after birth, when the lungs are surfactant deficient, still partially filled with liquid and not uniformly aerated. However, there have been very few studies that have examined this immediate post-birth period and identified the initial injury-related pathways that are activated. We aimed to determine if the early response genes; connective tissue growth factor (CTGF), cysteine rich-61 (CYR61) and early growth response 1 (EGR1), were rapidly induced by VILI in preterm lambs and whether ventilation with different tidal volumes caused different inflammatory cytokine and early response gene expression.

Methods

To identify early markers of VILI, preterm lambs (132 d gestational age; GA, term ~147 d) were resuscitated with an injurious ventilation strategy (V_T 20 mL/kg for 15 min) then gently ventilated (5 mL/kg) for 15, 30, 60 or 120 min (n = 4 in each). To determine if early response genes and inflammatory cytokines were differentially regulated by different ventilation strategies, separate groups of preterm lambs (125 d GA; n = 5 in each) were ventilated from birth with a V_T of 5 (VG5) or 10 mL/kg (VG10) for 135 minutes. Lung gene expression levels were compared to levels prior to ventilation in age-matched control fetuses.

Results

CTGF, CYR61 and EGR1 lung mRNA levels were increased ~25, 50 and 120-fold respectively (p < 0.05), within 30 minutes of injurious ventilation. VG5 and VG10 caused significant increases in CTGF, CYR61, EGR1, IL1-β, IL-6 and IL-8 mRNA levels compared to control levels. CTGF, CYR61, IL-6 and IL-8 expression levels were higher in VG10 than VG5 lambs; although only the IL-6 and CYR61 mRNA levels reached significance.

Conclusion

CTGF, CYR61 and EGR1 may be novel early markers of lung injury and mechanical ventilation from birth using relatively low tidal volumes may be less injurious than using higher tidal volumes.

G protein-coupled receptors go extracellular: RhoA integrates the integrins

The identification of downstream effectors of G protein-coupled receptors (GPCRs) is critical for understanding the interactions between signaling cascades and for developing new pharmacological approaches for controlling GPCR-mediated responses. RhoA is a small G protein that serves as a proximal downstream effector of numerous GPCRs and regulates a variety of basic cell functions, including migration, survival, and proliferation. Intriguingly, GPCR ligands such as thrombin, sphingosine-1-phosphate, and lysophosphatidic acid, which signal through G(12/13) and activate RhoA, have recently been shown to induce the expression of the extracellular matrix protein Cyr61 (i.e., CCN1). Cyr61 is secreted and interacts with cell surface integrins to activate kinase and transcriptional cascades that are also known to contribute to cell migration, survival, and proliferation. The GPCR/RhoA/Cyr61/integrin pathway defines a novel convergence mechanism for integrating GPCR-and integrin-dependent signaling cascades that may contribute to sustained and pathophysiological responses to GPCR activation.

Genome-wide expression profiling reveals distinct clusters of transcriptional regulation during bovine preimplantation development in vivo

Bovine embryos can be generated by in vitro fertilization or somatic nuclear transfer; however, these differ from their in vivo counterparts in many aspects and exhibit a higher proportion of developmental abnormalities. Here, we determined for the first time the transcriptomes of bovine metaphase II oocytes and all stages of preimplantation embryos developing in vivo up to the blastocyst using the Affymetrix GeneChip Bovine Genome Array which examines approximately 23,000 transcripts. The data show that bovine oocytes and embryos transcribed a significantly higher number of genes than somatic cells. Several hundred genes were transcribed well before the 8-cell stage, at which the major activation of the bovine genome expression occurs. Importantly, stage-specific expression patterns in 2-cell, 4-cell, and 8-cell stages, and in morulae and blastocysts, were detected, indicating dynamic changes in the embryonic transcriptome and in groups of transiently active genes. Pathway analysis revealed >120 biochemical pathways that are operative in early preimplantation bovine development. Significant differences were observed between the mRNA expression profiles of in vivo and in vitro matured oocytes, highlighting the need to include in vivo derived oocytes/embryos in studies evaluating assisted reproductive techniques. This study provides the first comprehensive analysis of gene expression and transcriptome dynamics of in vivo developing bovine embryos and will serve as a basis for improving assisted reproductive technology.

Mechanical strain activates a program of genes functionally involved in paracrine signaling of angiogenesis

Studies were performed to examine the extent to which mechanical stimuli mediate control of angiogenesis in bladder cells both in vitro and in vivo. Differential gene expression between control nonstretched and cyclically stretched bladder smooth muscle cells was assessed using oligonucleotide microarrays and pathway analysis by the web tool Fast Assignment and Transference of Information (FatiGO). Data showed that a substantial proportion (33 of 86) of mechanically responsive genes were angiogenesis-related and include cytokines, growth-related factors, adhesion proteins, and matricellular, signal transduction, extracellular matrix (ECM), and inflammatory molecules. Integrative knowledge of protein-protein interactions revealed that 12 mechano-sensitive gene-encoded proteins have interacting partner(s) in the vascular system confirming their potential role in paracrine regulation of angiogenesis. Angiogenic genes include matricellular proteins such as Cyr61/CCN1, CTGF/CCN2 and tenascin C, components of the VEGF and IGF systems, ECM proteins such as type I collagen and proteoglycans, and matrix metalloproteinases. In an in vivo model of bladder overdistension, 5 of 11 mechano-responsive angiogenic genes, independently tested by real-time PCR, were upregulated as a result of pressure overload including Cyr61/CCN1, CTGF/CCN2, MCP-1, VEGF-A, MMP-1, and midkine. Meanwhile, the molecular anatomy of angiogenic gene promoters reveals the presence of GA box-binding for the myc-associated zinc finger protein, MAZ, often found adjacent to binding sites for mechano-responsive transcription factors (e.g., NF-kappaB), suggesting that the coordinated activity of these factors may induce selective angiogenic gene transcription. These data suggest that mechanical control of angiogenic genes is an integral part of the adaptive and plasticity responses to mechanical overload.

Thrombin receptor and RhoA mediate cell proliferation through integrins and cysteine-rich protein 61

A subset of G-protein coupled receptors (GPCRs), including the thrombin receptor (PAR1), elicits mitogenic responses. Thrombin also activates Ras homolog gene family member A (RhoA) and activating protein (AP-1) -mediated gene expression in 1321N1 astrocytoma cells, whereas the nonmitogenic agonist carbachol does not. Transcriptomic analysis was used to explore differential gene induction by these agonists and revealed that the matricellular protein cysteine-rich 61 (Cyr61/CCN1) is selectively induced by thrombin. The ability of GPCR agonists to induce Cyr61 parallels their ability to activate RhoA; agonist-stimulated Cyr61 expression is inhibited by C3 toxin. When Cyr61 is down-regulated using short interfering RNA (siRNA) or short-hairpin RNA (shRNA), thrombin-induced DNA synthesis is significantly attenuated. When Cyr61 expression is induced, it appears in the extracellular compartment and on the cell surface. Extracellular Cyr61 interacts with alpha(5), alpha(6), and beta(1) integrins on these cells, and monoclonal antibodies directed against alpha(5) and beta(1) integrins inhibit thrombin-induced DNA synthesis. Functional blockade of Cyr61 with soluble heparin or anti-Cyr61 antibodies also inhibits thrombin-induced DNA synthesis. Thus Cyr61 is a highly inducible, secreted extracellular factor through which GPCR and RhoA signaling pathways engage integrins that contribute to GPCR-mediated proliferation.

Histopathology of the Urinary Bladders of Cynomolgus Monkeys Treated with PPAR Agonists

Peroxisome proliferator-activated receptors (PPAR) are involved in the pathogenesis of insulin resistance, diabetes, hyperlipidemias, and related complications. Consequently, a mechanistic understanding of PPAR subtypes and their activation provides promising therapeutic targets for the management of type 2 diabetes mellitus and the metabolic syndrome. Available data from rodent carcinogenicity studies, however, demonstrate that PPAR agonists can be tumorigenic in one or more species of rodents at multiple sites. Sufficient data are not yet available to explain the mode(s) of action for most of these tumor types. There has been information presented by FDA that indicates there are urothelial changes in the monkey (and possibly the dog) in addition to the rat. Outstanding questions exist regarding potency, species differences, safety margins, and other issues.

In 2005, the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) PPAR Agonist Project Committee was established to advance research on the modes of action and potential human relevance of emerging rodent tumor data. Additionally, the HESI PPAR Agonist Project Committee authorized a Pathology Working Group (PWG) to examine the urinary bladder from cynomolgus monkeys. The focus of this PWG was to establish consistent diagnostic criteria for urothelial changes and to assess the potential relationship of these changes to treatment. Specific diagnostic criteria and nomenclature were recommended for the diagnosis of urothelial granules, vacuolation, hypertrophy, and hyperplasia in studies conducted with PPARγ and dual α/γ agonists in cynomolgus monkeys, which will assist investigators performing toxicity studies to provide data in a consistent manner between studies and laboratories. In this review of selected tissues, treatment with PPAR agonists was not associated with urothelial hypertrophy or hyperplasia, but there was an increased incidence in the size and frequency of vacuoles within the superficial urothelial and adjacent intermediate cell layers.

RhoA/Rho-kinase contribute to the pathogenesis of diabetic renal disease

OBJECTIVE

Accumulation of glomerular matrix proteins is central to the pathogenesis of diabetic nephropathy, with resident mesangial cells (MCs) known to upregulate matrix protein synthesis in response to high glucose. Because activation of the GTPase RhoA has been implicated in matrix upregulation, we studied its role in induction of the matrix protein fibronectin in diabetic MCs and in vivo in diabetic nephropathy.

RESEARCH DESIGN AND METHODS

Glucose (30 mmol/l)-induced RhoA/Rho-kinase, AP-1 activation, and fibronectin upregulation were assessed by immunoblotting, luciferase, electrophoretic mobility shift assay, enzyme-linked immunosorbent assay, real-time PCR, Northern blots, and immunofluorescence. Streptozotocin-induced diabetic rats were treated with the rho-kinase inhibitor fasudil, which was compared with enalapril, and functional and pathologic parameters were assessed.

RESULTS

Glucose led to RhoA and downstream Rho-kinase activation. Mannitol was without effect. Activity of the transcription factor AP-1, increased in diabetic MCs and kidneys, is important in the profibrotic effects of glucose, and this was dependent on Rho-kinase signaling. Upregulation of fibronectin by glucose, shown to be mediated by activator protein-1 (AP-1), was prevented by Rho-kinase inhibition. RhoA siRNA and dominant-negative RhoA also markedly attenuated fibronectin upregulation by high glucose. Applicability of these findings were tested in vivo. Fasudil prevented glomerular fibronectin upregulation, glomerular sclerosis, and proteinuria in diabetic rats, with effectiveness similar to enalapril.

CONCLUSIONS

High glucose activates RhoA/Rho-kinase in MCs, leading to downstream AP-1 activation and fibronectin induction. Inhibition of this pathway in vivo prevents the pathologic changes of diabetic nephropathy, supporting a potential role for inhibitors of RhoA/Rho in the treatment of diabetic renal disease.

Exercise-induced expression of angiogenic growth factors in skeletal muscle and in capillaries of healthy and diabetic mice

Background

Diabetes has negative, and exercise training positive, effects on the skeletal muscle vasculature, but the mechanisms are not yet fully understood. In the present experiment the effects of running exercise on the mRNA expression of pro- and antiangiogenic factors were studied in healthy and diabetic skeletal muscle. The responses in capillaries and muscle fibers, collected from the muscle with laser capture microdissection, were also studied separately.

Methods

Healthy and streptozotocin-induced diabetic mice were divided into sedentary and exercise groups. Exercise was a single bout of 1 h running on a treadmill. Gastrocnemius muscles were harvested 3 h and 6 h post exercise, and angiogenesis-related gene expressions were analyzed with real-time PCR. In addition to muscle homogenates, capillaries and muscle fibers were collected from the muscle with laser capture microdissection method and analyzed for vascular endothelial growth factor-A (VEGF-A) and thrombospondin-1 (TSP-1) mRNA expression.

Results

Of the proangiogenic factors, VEGF-A and VEGF receptor-2 (VEGFR-2) mRNA expression increased significantly (P < 0.05) in healthy skeletal muscle 6 h post exercise. VEGF-B also showed a similar trend (P = 0.08). No significant change was observed post exercise in diabetic muscles in the expression of VEGF-A, VEGFR-2 or VEGF-B. The expression of angiogenesis inhibitor TSP-1 and angiogenic extracellular matrix protein Cyr61 were significantly increased in diabetic muscles (P < 0.05–0.01). Capillary mRNA expression resembled that in the muscle homogenates, however, the responses were greater in capillaries compared to muscle homogenates and pure muscle fibers.

Conclusion

The present study is the first to report the effects of a single bout of exercise on the expression of pro- and antiangiogenic factors in diabetic skeletal muscle, and it provides novel data about the separate responses in capillaries and muscle fibers to exercise and diabetes. Diabetic mice seem to have lower angiogenic responses to exercise compared to healthy mice, and they show markedly increased expression of angiogenesis inhibitor TSP-1. Furthermore, exercise-induced VEGF-A expression was shown to be greater in capillaries than in muscle fibers.

Cysteine-rich protein 61 and connective tissue growth factor induce deadhesion and anoikis of retinal pericytes

Loss of retinal pericytes is one of the distinctive features of diabetic retinopathy (DR), which is characterized by retinal capillary obliteration. The matricellular proteins, cysteine-rich protein 61 (Cyr61) and connective tissue growth factor (CTGF), are aberrantly expressed in the retinal vasculature from the early stages of DR, but their effects on retinal pericytes are unknown. We show herein that rat retinal pericytes (RRPs) exposed to advanced glycosylation-end products, an important injurious stimulus of diabetes, express increased levels of both Cyr61 and CTGF, and concomitantly undergo anoikis, a form of apoptosis by loss of cell-matrix interactions. Adenovirus-mediated expression of Cyr61 and/or CTGF conferred an anoikis-prone phenotype to rat retinal pericytes, including decreased phosphotyrosine protein levels at focal adhesion points and formation of cortical actin rings. When used as substrates for pericyte attachment and compared with other matrix proteins (e.g. type IV collagen), recombinant Cyr61 and CTGF proteins exhibited antiadhesive and apoptogenic activities. Phosphatase inhibitors reversed these effects, suggesting that Cyr61 and CTGF promote dephosphorylation events. Furthermore, Cyr61- and CTGF-induced apoptosis was mediated through the intrinsic pathway and involved the expression of genes that have been functionally grouped as p53 target genes. Expression of the matrix metalloproteinase-2 gene, a known target of p53, was increased in pericytes overexpressing either Cyr61 or CTGF. Inhibition of matrix metalloproteinase-2 had, at least in part, a protective effect against Cyr61- and CTGF-induced apoptosis. Taken together, these findings support the involvement of Cyr61 and CTGF in pericyte detachment and anoikis, implicating these proteins in the pathogenesis of DR.

Gene expression profiling in brain following acute systemic hypertonicity: novel genes possibly involved in osmoadaptation

In brain osmoprotective genes known to be involved in cellular osmoadaptation to hypertonicity, as well as the related transcription factor tonicity-responsive enhancer binding protein (TonEBP) are only expressed in some cell subsets. In the search for other genes possibly involved in osmoadaptation of brain cells we have analyzed, through microarray, the transcriptional profile of forebrain from rats subjected to 45 min, 90 min, and 6 h systemic hypertonicity. Microarray data were validated by quantitative real-time PCR. Around 23 000 genes gave a reliable hybridization signal. The number of genes showing a higher expression increased from around 15 (45 min) up to nearly 200 (6 h). Among about 30 immediate early genes (IEGs) encoding transcription factors, only Atf3, Verge, and Klf4 showed a rapid increased expression. TonEBP-mRNA tissue level and TonEBP-mRNA labeling in neurons remained unchanged whereas TonEBP labeling was rapidly increased in neurons. Sodium-dependent neutral amino acid transporter-2 (SNAT2) encoded by gene Slc38a2 showed a delayed increased expression. The rapid tonicity-induced activation of Atf3, Verge, and Klf4 may regulate genes involved in osmoadaptation. Nfat5 encoding TonEBP is not an IEG and the early tonicity-induced expression of TonEBP in neurons may result from translational activation. Increased expression of sodium-dependent neutral amino-acid transporter 2 may lead to the cellular accumulation of amino acids for adaptation to hypertonicity.

A single bout of exercise with high mechanical loading induces the expression of Cyr61/CCN1 and CTGF/CCN2 in human skeletal muscle

High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1α. The mRNA expression of Cyr61 and CTGF increased 30 min after the exercise (14- and 2.5-fold, respectively; P < 0.001). Cyr61 remained elevated 48 h postexercise (threefold; P < 0.05). The mRNA levels of VEGF-A, VEGF-B, VEGF-C, VEGF-D, or hypoxia-inducible factor-1α did not change significantly at either 30 min or 48 h postexercise; however, the variation between subjects increased markedly in VEGF-A and VEGF-B mRNA. Cyr61 protein levels were higher at both 30 min and 48 h after the exercise compared with the control ( P < 0.05). Cyr61 and CTGF proteins were localized to muscle fibers and the surrounding ECM by immunohistochemistry. Fast fibers stained more intensively than slow fibers. In conclusion, mechanical loading induces rapid expression of CCN proteins in human skeletal muscle. This may be one of the early mechanisms involved in skeletal muscle remodeling after exercise, since Cyr61 and CTGF regulate the expression of genes involved in angiogenesis and ECM remodeling.

Vascular endothelial growth factor (VEGF)-induced up-regulation of CCN1 in osteoblasts mediates proangiogenic activities in endothelial cells and promotes fracture healing

Angiogenesis is indispensable during fracture repair, and vascular endothelial growth factor (VEGF) is critical in this process. CCN1 (CYR61) is an extracellular matrix signaling molecule that has been implicated in neovascularization through its interactions with several endothelial integrin receptors. CCN1 has been shown to be up-regulated during the reparative phase of fracture healing; however, the role of CCN1 therein remains unclear. Here, the regulation of CCN1 expression in osteoblasts and the functional consequences thereof were studied. Stimulation of osteoblasts with VEGF resulted in a dose- and time-dependent up-regulation of CCN1 mRNA and protein. An up-regulation of both cell surface-associated CCN1 as well as extracellular matrix-associated CCN1 in osteoblasts was found. The supernatant of VEGF-prestimulated osteoblasts was chemotactic for endothelial cells, increasing their migration and stimulated capillary-like sprout formation. These effects could be attributed to the presence of CCN1 in the osteoblast supernatant as they were prevented by an antibody against CCN1 or by small interfering RNA-mediated knockdown of osteoblast CCN1. Moreover, the supernatant of VEGF-prestimulated osteoblasts induced angiogenesis in Matrigel plugs in vivo in a CCN1-dependent manner. In addition, blockade of CCN1 prevented bone fracture healing in mice. Taken together, the present work demonstrates a potential paracrine loop consisting of the VEGF-mediated up-regulation of CCN1 in osteoblasts that attracts endothelial cells and promotes angiogenesis. Such a loop could be operative during fracture healing.

The angiogenic factor CCN1 promotes adhesion and migration of circulating CD34+ progenitor cells: potential role in angiogenesis and endothelial regeneration

Tissue regeneration involves the formation of new blood vessels regulated by angiogenic factors. We reported recently that the expression of the angiogenic factor CCN1 is up-regulated under various pathophysiologic conditions within the cardiovascular system. Because CD34+ progenitor cells participate in cardiovascular tissue regeneration, we investigated whether CCN1-detected for the first time in human plasma-promotes the recruitment of CD34+ progenitor cells to endothelial cells, thereby enhancing endothelial proliferation and neovascularization. In this study, we demonstrated that CCN1 and supernatants from CCN1-stimulated human CD34+ progenitor cells promoted proliferation of endothelial cells and angiogenesis in vitro and in vivo. In addition, CCN1 induced migration and transendothelial migration of CD34+ cells and the release of multiple growth factors, chemokines, and matrix metalloproteinase-9 (MMP-9) from these cells. Moreover, the CCN1-specific integrins alpha(M)beta(2) and alpha(V)beta(3) are expressed on CD34+ cells and CCN1 stimulated integrin-dependent signaling. Furthermore, integrin antagonists (RGD-peptides) suppressed both binding of CCN1 to CD34+ cells and CCN1-induced adhesion of CD34+ cells to endothelial cells. These data suggest that CCN1 promotes integrin-dependent recruitment of CD34+ progenitor cells to endothelial cells, which may contribute to paracrine effects on angiogenesis and tissue regeneration.

Vascular Endothelial Growth Factor Mediates Hypoxic Stimulated Embryonic Bladder Growth in Organ Culture

PURPOSE

Tissue hypoxia enhances embryonic angiogenesis at least in part by up-regulating vascular endothelial growth factor. Additionally, exogenous vascular endothelial growth factor-A enhances embryonic bladder explant growth. We hypothesized that developing bladders are hypoxic in vivo and oxygen tensions modulate explanted bladder growth by altering vascular endothelial growth factor-A expression.

MATERIALS AND METHODS

Embryonic day 14 mouse bladders were cultured in 20% O(2) or 3% O(2) atmospheres. Some cultures were supplemented with a vascular endothelial growth factor receptor 1/Fc chimera to block vascular endothelial growth factor bioactivity. After 6 days explant areas, DNA, protein, total cell numbers, and proportions expressing endothelial and smooth muscle markers were measured. Pimonidazole was administered to pregnant mice and hypoxia was sought in embryonic tissues by immunohistochemistry.

RESULTS

In vivo pimonidazole adducts and vascular endothelial growth factor-A immunolocalized to embryonic urothelium and bladders up-regulated total vascular endothelial growth factor-A between embryonic days 14 and 18. All growth parameters and vascular endothelial growth factor-A protein levels were enhanced in hypoxic vs normoxic culture. Addition of vascular endothelial growth factor receptor 1/Fc prevented this accelerated growth.

CONCLUSIONS

In vivo embryonic bladders are hypoxic and express vascular endothelial growth factor-A. In vitro, when oxygen tensions are manipulated, vascular endothelial growth factor-A protein positively correlates with the growth of whole explants as well as endothelium. Normal embryonic bladder development may be driven at least in part by hypoxic up-regulation of vascular endothelial growth factor-A.

Mechanical regulation of the Cyr61/CCN1 and CTGF/CCN2 proteins

Cells in various anatomical locations are constantly exposed to mechanical forces from shear, tensile and compressional forces. These forces are significantly exaggerated in a number of pathological conditions arising from various etiologies e.g., hypertension, obstruction and hemodynamic overload. Increasingly persuasive evidence suggests that altered mechanical signals induce local production of soluble factors that interfere with the physiologic properties of tissues and compromise normal functioning of organ systems. Two immediate early gene-encoded members of the family of the Cyr61/CTGF/Nov proteins referred to as cysteine-rich protein 61 (Cyr61/CCN1) and connective tissue growth factor (CTGF/CCN2), are highly expressed in several mechanical stress-related pathologies, which result from either increased externally applied or internally generated forces by the actin cytoskeleton. Both Cyr61 and CTGF are structurally related but functionally distinct multimodular proteins that are expressed in many organs and tissues only during specific developmental or pathological events. In vitro assessment of their biological activities revealed that Cyr61 expression induces a genetic reprogramming of angiogenic, adhesive and structural proteins while CTGF promotes distinctively extracellular matrix accumulation (i.e., type I collagen) which is the principal hallmark of fibrotic diseases. At the molecular level, expression of the Cyr61 and CTGF genes is regulated by alteration of cytoskeletal actin dynamics orchestrated by various components of the signaling machinery, i.e., small Rho GTPases, mitogen-activated protein kinases, and actin binding proteins. This review discusses the mechanical regulation of the Cyr61 and CTGF in various tissues and cell culture models with a special attention to the cytoskeletally based mechanisms involved in such regulation.

Vascular endothelial growth factor stimulates embryonic urinary bladder development in organ culture

OBJECTIVES

To determine whether vascular endothelial growth factor A (VEGF) and its receptors are expressed during bladder development in mice when capillaries are forming, and whether exogenous VEGF might enhance the growth of endothelia and other types of bladder cells, using an embryonic organ-culture model.

MATERIALS AND METHODS

Whole bladders from wild-type mice, at embryonic day (E) 14, were grown in serum-free organ culture in an air/5% CO2 atmosphere; some cultures were supplemented with VEGF and/or with VEGF receptor 1/Fc chimera (VEGFR1/Fc), which blocks VEGF bioactivity. Organs were harvested after 6 days and the expression of VEGF and related molecules assessed using immunohistochemistry.

RESULTS

VEGF, VEGFR1 and VEGFR2 positive cells were immunodetected in E14 and E18 bladders. Exogenous VEGF increased whole-organ growth, as assessed by explant areas, total cell numbers, DNA and protein content; proliferation was enhanced, and apoptosis decreased, in urothelium and surrounding tissues. VEGF also increased the proportions of cells expressing endothelial (CD31) and smooth muscle (alpha smooth muscle actin) markers. VEGFR1/Fc blocked the growth-enhancing effects of exogenous VEGF.

CONCLUSIONS

In organ culture, exogenous VEGF not only stimulated embryonic bladder endothelial cells but also strikingly enhanced the growth of the whole organ. Whether the effects of VEGF on diverse bladder cell populations are direct or indirect requires further investigation. The finding that VEGF protein is present in embryonic bladders in vivo raises the possibility that it has similar actions during normal development. The results also illuminate the pathobiology of certain bladder diseases in which VEGF levels have been shown to be increased.

Ovarian carcinomas: CCN genes are aberrantly expressed and CCN1 promotes proliferation of these cells

PURPOSE

The connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed (CCN) family consists of six matricellular proteins that are involved in various cellular functions, such as proliferation, development, and angiogenesis. The purpose of this study was to explore the possibility that CCN genes are involved in ovarian cancers.

EXPERIMENTAL DESIGN

We quantified CCN expression in a series of 59 ovarian cancers using quantitative real-time reverse transcription-PCR. CCN1 protein levels were further determined by immunohistochemistry and Western blot analysis. Overexpression and inhibition of CCN1 expression by small interfering RNA were used to examine its role in ovarian cancer cell proliferation in vitro and in vivo.

RESULTS

We found dysregulation of levels of the various CCN mRNAs in ovarian cancers compared with their expression in normal whole ovaries. Expression of CCN1 protein was detected in normal ovarian epithelial cells and ovarian tumors as well as in ovarian cancer cell lines. Furthermore, estrogen increased CCN1 mRNA and protein levels in ovarian cancer cells. Ectopic expression of CCN1 enhanced the growth of ovarian cancer cells in liquid culture, whereas inhibition of its expression decreased proliferation and increased apoptosis in these cells. The observed changes in cell growth were accompanied with activation of Akt and extracellular signal-regulated kinase (ERK) signaling pathways. Stable expression of CCN1 in SKOV3 cells significantly increased tumorigenicity in nude mice. Finally, overexpression of CCN1 conferred resistant to carboplatin-induced apoptosis in SKOV3 cells.

CONCLUSIONS

This is the first study to show abnormalities in CCN expression in ovarian carcinomas. Furthermore, our results suggest that CCN1 may play a role in ovarian carcinogenesis by stimulating survival and antiapoptotic signaling pathways.