Short Hairpin RNA Knockdown of Connective Tissue Growth Factor by Ultrasound-Targeted Microbubble Destruction Improves Renal Fibrosis

The purpose of this study was to evaluate whether ultrasound-targeted microbubble destruction transfer of interfering RNA against connective tissue growth factor (CTGF) in the kidney would ameliorate renal fibrosis in vivo. A short hairpin RNA (shRNA) targeting CTGF was cloned into a tool plasmid and loaded onto the surface of a cationic microbubble product. A unilateral ureteral obstruction (UUO) model in mice was used to evaluate the effect of CTGF knockdown. Mice were administered the plasmid-carrying microbubble intravenously, and ultrasound was applied locally to the obstructed kidney. Mice undergoing a sham UUO surgery and untreated UUO mice were used as disease controls, and mice administered plasmid alone, plasmid with ultrasound treatment and microbubbles and plasmid without ultrasound were used as treatment controls. Mice were treated once and then evaluated at day 14. CTGF in the kidney was measured by quantitative reverse transcription polymerase chain reaction and Western blot. Expression of CTGF, transforming growth factor β1, α smooth muscle actin and type I collagen in the obstructed kidney was evaluated by immunohistochemistry. The cohort treated with plasmid-carrying microbubbles and ultrasound exhibited reduced mRNA and protein expression of CTGF (p < 0.01). Furthermore, CTGF gene silencing decreased the interstitial deposition of transforming growth factor β1, α smooth muscle actin and type I collagen as assessed in immunohistochemistry, as well as reduced renal fibrosis in pathologic alterations (p < 0.01). No significant changes in target mRNA, protein expression or disease pathology were observed in the control cohorts. A single treatment of ultrasound-targeted microbubble destruction is able to deliver sufficient shRNA to inhibit the expression of CTGF and provide a meaningful reduction in disease severity. This technique may be a potential therapy for treatment of renal fibrosis.

Inhibition of connective tissue growth factor attenuates paraquat-induced lung fibrosis in a human MRC-5 cell line

Chronic exposure to Paraquat (PQ) may result in progressive pulmonary fibrosis and subsequent chronic obstructive pulmonary malfunction. Connective tissue growth factor (CTGF) has been proposed as a key determinant in the development of lung fibrosis. We investigated thus whether knock down of CTGF can prevent human lung fibroblasts (MRC-5) activation and proliferation with the subsequent inhibition of PQ-induced fibrosis. MRC-5 was transfected with CTGF-siRNAs and exposed to different concentrations of PQ. The siRNA-silencing efficacy was evaluated using western blotting analyses, qRT-PCR and flow cytometry. Next, the viability and migration of MRC-5 was determined. MMP-2, MMP-9, and TIMP-1 accumulation were quantified to evaluate the lung fibrosis exposure to PQ. Over expression of CTGF mRNA was observed in human MRC-5 cell as early as 6 h following PQ stimulation. CTGF gene expression in MRC-5 cells was substantially reduced by RNAi, which significantly suppressed the expression of the lung fibrosis markers such as tissue inhibitor of metalloproteinase-2 (TIMP-2), Matrix metalloproteinase-2 (MMP-2) and Matrix metalloproteinase-9 (MMP-9) that were stimulated by PQ. Inhibition of CTGF expression suppressed impeded the proliferation and migration ability of MRC-5 cells and resulted in cell-extracellular matrix (ECM) protein accumulation in cells. Our results suggest that CTGF promoted the development of PQ-induced lung fibrosis in collaboration with transforming growth factor β1 (TGFβ1). Furthermore, the observed arresting effects of CTGF knock down during this process suggested that CTGF is the potential target site for preventing PQ-induced pulmonary fibrosis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1620-1626, 2016.

Atheroprotective laminar flow inhibits Hippo pathway effector YAP in endothelial cells

Atherosclerosis is a mechanobiology-related disease that preferentially develops in the aortic arch and arterial branches, which are exposed to disturbed/turbulent blood flow but less in thoracic aorta where the flow pattern is steady laminar flow (LF). Increasing evidence supports that steady LF with high shear stress is protective against atherosclerosis. However, the molecular mechanisms of LF-mediated atheroprotection remain incompletely understood. Hippo/YAP (yes-associated protein) pathway senses and effects mechanical cues and has been reported to be a master regulator of cell proliferation, differentiation, and tissue homeostasis. Here, we show that LF inhibits YAP activity in endothelial cells (ECs). We observed that YAP is highly expressed in mouse EC-enriched tissues (lung and aorta) and in human ECs. Furthermore, we found in apolipoprotein E deficient (ApoE(-/-)) mice and human ECs, LF decreased the level of nuclear YAP protein and YAP target gene expression (connective tissue growth factor and cysteine-rich protein 61) through promoting Hippo kinases LATS1/2-dependent YAP (Serine 127) phosphorylation. Functionally, we revealed that YAP depletion in ECs phenocopying LF responses, reduced the expression of cell cycle gene cyclin A1 (CCNA1) and proinflammatory gene CCL2 (MCP-1). Taken together, we demonstrate that atheroprotective LF inhibits endothelial YAP activation, which may contribute to LF-mediated ECs quiescence and anti-inflammation.

[Berberine inhibits cardiac fibrosis of diabetic rats]

Objective To explore the effect of berberine on cardiac fibrosis of diabetic rats by observing the expressions of serum transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF) , collagen type 1 (Col1) and collagen type 3 (Col3) in myocardial tissues of diabetic rats after berberine treatment. Methods The diabetic model was induced by intraperitoneal injection of streptococci (STZ). Forty-three diabetic rats were randomly divided into diabetic model group (n=9), berberine treated groups of different doses [50, 100, 150 mg/(kg.d), gavage administration for 12 weeks; n=9, 9, 8 respectively], and metformin group as positive control (n=8); other 8 normal rats served as a negative control group. After the last administration, fasting blood glucose, left ventricular systolic pressure (LVSP) and left ventricular end diastolic pressure (LVEDP) were measured; rats' heart were taken to calculate the heart mass index (HMI); ELISA was used to detect the serum levels of TGF-β1 and CTGF; collagenous fibers in cardiac tissues were tested by Masson staining; collagen volume fraction (CVF) was measured by image analysis; Col1 and Col3 in cardiac tissues were determined by Western blotting. Results Compared with the normal control group, the fasting blood glucose, LVSP, LVEDP absolute value, HMI, the degree of cardiac fibrosis, the expressions of TGF-β1, CTGF, Col1 and Col3 significantly increased in the model group. All indexes mentioned above were reduced obviously in berberine treated groups of 100 and 150 mg/(kg.d). Conclusion Berberine improves cardiac fibrosis in diabetic rats through down-regulating the expressions of TGF-β1 and CTGF and reducing the synthesis and deposition of Col1 and Col3.

The Role of the Rho/ROCK Pathway in Ang II and TGF-β1-Induced Atrial Remodeling

Objectives

To study the role of the Rho/ROCK pathway in Ang II and TGF-β1-induced atrial remodeling.

Methods and Results

A canine atrial fibrillation (AF) model was established by rapid atrial pacing (RAP) of the left atrium. The roles of TGF-β1, the RhoA/ROCK signaling pathway and connective tissue growth factor (CTGF) in atrial remodeling were studied via both in vitro and in vivo experiments. Each of the dogs that received RAP developed persistent AF within 4 weeks. The mRNA expression levels of TGF-β1 (1.32±0.38), Collagen-I(1.33±0.91), CTGF(5.83±3.71), RhoA(1.23±0.57) and ROCK-1 (1.02±0.27) in the left atrium were significantly increased following 4 weeks of RAP. Angiotensin II (Ang II) induced the proliferation of atrial fibroblasts and up-regulated the expression of both CTGF and ROCK-1 in a dose-dependent manner. Simvastatin and Y27632 reversed Ang II-induced CFs proliferation, as well as ROCK-1(0.89±0.05 and 1.27±0.03, respectively) and CTGF (0.87±0.04 and 0.91±0.02, respectively) expression. The expression mRNA of ROCK-1(1.74±0.13) and CTGF (2.28±0.11) can upregulated by TGF-β1, and down-regulated by Simvastatin (1.22±0.03 vs 2.27±0.11), Y27632 (1.01±0.04 vs 1.64±0.03), Los (1.04±0.11 vs 1.26±0.05), respectively. Losartan and Simvastatin attenuated the effects of TGF-β1, inhibited RhoA activity as opposed to RhoA protein expression. Y27632 had no effect on either the expression or the activity of RhoA.

Conclusions

The increased expression of profibrotic factors (CTGF, ROCK1 and Smad2/3) played an important role in our RAP-induced AF model. Increased atrial profibrotic factors involve the activation of either the TGF-β1/RhoA/ROCK-1 or the TGF-β1/Smad2/3 signaling pathway.

Connective tissue growth factor is critical for proper β-cell function and pregnancy-induced β-cell hyperplasia in adult mice

During pregnancy, maternal β-cells undergo compensatory changes, including increased β-cell mass and enhanced glucose-stimulated insulin secretion. Failure of these adaptations to occur results in gestational diabetes mellitus. The secreted protein connective tissue growth factor (CTGF) is critical for normal β-cell development and promotes regeneration after partial β-cell ablation. During embryogenesis, CTGF is expressed in pancreatic ducts, vasculature, and β-cells. In adult pancreas, CTGF is expressed only in the vasculature. Here we show that pregnant mice with global Ctgf haploinsufficiency (Ctgf(LacZ/+)) have an impairment in maternal β-cell proliferation; no difference was observed in virgin Ctgf(LacZ/+) females. Using a conditional CTGF allele, we found that mice with a specific inactivation of CTGF in endocrine cells (Ctgf(ΔEndo)) develop gestational diabetes during pregnancy, but this is due to a reduction in glucose-stimulated insulin secretion rather than impaired maternal β-cell proliferation. Moreover, virgin Ctgf(ΔEndo) females also display impaired GSIS with glucose intolerance, indicating that underlying β-cell dysfunction precedes the development of gestational diabetes in this animal model. This is the first time a role for CTGF in β-cell function has been reported.

GPER Mediates Non-Genomic Effects of Estrogen

Estrogens are important modulators of a broad spectrum of physiological functions in humans. However, despite their beneficial actions, a number of lines of evidence correlate the sustained exposure to exogenous estrogen with increased risk of the onset of various cancers. Mainly these steroid hormones induce their effects by binding and activating estrogen receptors (ERα and ERβ). These receptors belong to the family of ligand-regulated transcription factors, and upon activation they regulate the expression of different target genes by binding directly to specific DNA sequences. On the other hand, in recent years it has become clear that the G protein-coupled estrogen receptor 30 (GPR30/GPER) is able to mediate non-genomic action of estrogens in different cell contexts. In particular, GPER has been shown to specifically bind estrogens, and in turn to functionally cross-react with diverse cell signaling systems such as the epidermal growth factor receptor (EGFR) pathway, the Notch signaling pathway and the mitogen-activated protein kinases (MAPK) pathway. In this chapter we will present some of the different experimental techniques currently used to demonstrate the functional role of GPER in mediating non-genomic actions of estrogens, such as the dual luciferase assay, assessment of the involvement of GPER in the stimulation of cell migration in breast cancer cell lines and in cancer-associated fibroblasts, and chromatin immunoprecipitation assay. Overall, the experimental procedures described herein represent key instruments for assessing the biological role of GPER in mediating non-genomic signals of estrogen.

Induction of Connective Tissue Growth Factor Expression by Hypoxia in Human Lung Fibroblasts via the MEKK1/MEK1/ERK1/GLI-1/GLI-2 and AP-1 Pathways

Several reports have indicated that hypoxia, GLI, and connective tissue growth factor (CTGF) contribute to pulmonary fibrosis in idiopathic pulmonary fibrosis. We investigated the participation of mitogen-activated protein kinase kinase (MEK) kinase 1 (MEKK1)/MEK1/ERK1/GLI-1/2 and activator protein-1 (AP-1) signaling in hypoxia-induced CTGF expression in human lung fibroblasts. Hypoxia time-dependently increased CTGF expression, which was attenuated by the small interfering RNA (siRNA) of GLI-1 (GLI-1 siRNA) and GLI-2 (GLI-2 siRNA) in both human lung fibroblast cell line (WI-38) and primary human lung fibroblasts (NHLFs). Moreover, GLI-1 siRNA and GLI-2 siRNA attenuated hypoxia-induced CTGF-luciferase activity, and the treatment of cells with hypoxia induced GLI-1 and GLI-2 translocation. Furthermore, hypoxia-induced CTGF expression was reduced by an MEK inhibitor (PD98059), MEK1 siRNA, ERK inhibitor (U0126), ERK1 siRNA, and MEKK1 siRNA. Both PD98059 and U0126 significantly attenuated hypoxia-induced CTGF-luciferase activity. Hypoxia time-dependently increased MEKK1, ERK, and p38 MAPK phosphorylation. Moreover, SB203580 (a p38 MAPK inhibitor) also apparently inhibited hypoxia-induced CTGF expression. The treatment of cells with hypoxia induced ERK, GLI-1, or GLI-2 complex formation. Hypoxia-induced GLI-1 and GLI-2 translocation into the nucleus was significantly attenuated by U0126. In addition, hypoxia-induced ERK Tyr204 phosphorylation was impeded by MEKK1 siRNA. Moreover, hypoxia-induced CTGF-luciferase activity was attenuated by cells transfected with AP-1 site mutation in a CTGF construct. Exposure to hypoxia caused a time-dependent phosphorylation of c-Jun, but not of c-Fos. Chromatin immunoprecipitation (ChIP) revealed that hypoxia induced the recruitment of c-Jun, GLI-1, and GLI-2 to the AP-1 promoter region of CTGF. Hypoxia-treated cells exhibited an increase in α-smooth muscle actin (α-SMA) and collagen production, which was blocked by GLI-1 siRNA and GLI-2 siRNA. Overall, these data implied that the MEKK1/MEK1/ERK1/GLI-1/GLI-2, and AP-1 pathways mediated hypoxia-induced CTGF expression in human lung fibroblasts. Furthermore, GLI-1 and GLI-2 found to be involved in hypoxia-induced α-SMA and collagen expression.

Simvastatin Reduces Capsular Fibrosis around Silicone Implants

Capsular fibrosis and contracture occurs in most breast reconstruction patients who undergo radiotherapy, and there is no definitive solution for its prevention. Simvastatin was effective at reducing fibrosis in various models. Peri-implant capsular formation is the result of tissue fibrosis development in irradiated breasts. The purpose of this study was to examine the effect of simvastatin on peri-implant fibrosis in rats. Eighteen male Sprague-Dawley rats were allocated to an experimental group (9 rats, 18 implants) or a control group (9 rats, 18 implants). Two hemispherical silicone implants, 10 mm in diameter, were inserted in subpanniculus pockets in each rat. The next day, 10-Gy of radiation from a clinical accelerator was targeted at the implants. Simvastatin (15 mg/kg/day) was administered by oral gavage in the experimental group, while animals in the control group received water. At 12 weeks post-implantation, peri-implant capsules were harvested and examined histologically and by real-time polymerase chain reaction. The average capsular thickness was 371.2 μm in the simvastatin group and 491.2 μm in the control group. The fibrosis ratio was significantly different, with 32.33% in the simvastatin group and 58.44% in the control group (P < 0.001). Connective tissue growth factor (CTGF) and transforming growth factor (TGF)-β1 gene expression decreased significantly in the simvastatin group compared to the control group (P < 0.001). This study shows that simvastatin reduces radiation-induced capsular fibrosis around silicone implants in rats. This finding offers an alternative therapeutic strategy for reducing capsular fibrosis and contracture after implant-based breast reconstruction.

Nelumbo nucifera Gaertn leaves extract inhibits the angiogenesis and metastasis of breast cancer cells by downregulation connective tissue growth factor (CTGF) mediated PI3K/AKT/ERK signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Nelumbo nucifera Gaertn (Nymphaeaceae) has been recognized as a medicinal plant, which was distributed throughout the Asia. The aqueous extract of Nelumbo nucifera leaves extract (NLE) has various biologically active components such as polyphenols, flavonoids, oligomeric procyanidines. However, the role of NLE in breast cancer therapy is poorly understood.

THE AIM OF THIS STUDY

The purpose of this study was to identify the hypothesis that NLE can suppress tumor angiogenesis and metastasis through CTGF (connective tissue growth factor), which has been implicated in tumor angiogenesis and progression in breast cancer MDA-MB-231 cells.

RESULTS

We examined the effects of NLE on angiogenesis in the chicken chorioallantoic membrane (CAM) model. The data showed that NLE could reduce the chorionic plexus at day 17 in CAM and the duration of this inhibition was dose-dependent. In Xenograft model, NLE treatment significantly reduced tumor weight and CD31 (capillary density) over control, respectively. We examined the role of angiogenesis involved restructuring of endothelium using human umbilical vein endothelial cell (HUVEC) in Matrigel angiogenesis model. The results indicated that vascular-like structure formation was further blocked by NLE treatment. Moreover, knockdown of CTGF expression markedly reduced the expression of MMP2 as well as VEGF, and attenuated PI3K-AKT-ERK activation, indication that these signaling pathways are crucial in mediating CTGF function.

CONCLUSION

The present results suggest that NLE might be useful for treatment in therapy-resistance triple negative breast cancer.

Increased Epithelial Expression of CTGF and S100A7 with Elevated Subepithelial Expression of IL-1β in Trachomatous Trichiasis

Purpose

To characterize the histological appearance and expression of pro-inflammatory mediators, growth factors, matrix metalloproteinases and biomarkers of epithelial-mesenchymal transition (EMT) in healthy control and trachomatous trichiasis (TT) conjunctival tissue.

Methods

Conjunctival biopsies were taken from 20 individuals with TT and from 16 individuals with healthy conjunctiva, which served as controls. Study participants were of varying ethnicity and were living in a trachoma-endemic region of northern Tanzania. Formalin-fixed paraffin-embedded tissue sections were stained using hematoxylin and eosin or by immunohistochemistry using antibodies against: IL-1β, IL-6, IL-17A, IL-22, CXCL5, S100A7, cleaved caspase 1 (CC1), PDGF, CTGF, TGFβ2, MMP7, MMP9, E-cadherin, vimentin, and αSMA.

Results

Tissue from TT cases had a greater inflammatory cell infiltrate relative to controls and greater disruption of collagen structure. CTGF and S100A7 were more highly expressed in the epithelium and IL-1β was more highly expressed in the substantia propria of TT cases relative to controls. Latent TGFβ2 was slightly more abundant in the substantia propria of control tissue. No differences were detected between TT cases and controls in the degree of epithelial atrophy, the number of myofibroblasts or expression of EMT biomarkers.

Conclusions

These data indicate that the innate immune system is active in the immunopathology of trachoma, even in the absence of clinical inflammation. CTGF might provide a direct link between inflammation and fibrosis and could be a suitable target for therapeutic treatment to halt the progression of trachomatous scarring.

Progressive scarring of the conjunctiva in individuals with trachoma causes the eyelids to contract, drawing the eyelashes inwards (trichiasis) so that they scratch the cornea, causing pain and eventually blindness. Disease is initiated in childhood by repeated conjunctival infection with Chlamydia trachomatis (Ct), however, infection is not commonly found in adults, yet chronic inflammation and fibrosis progress throughout the lives of many individuals. A better understanding of the mechanisms driving inflammation and fibrosis are required in order to develop treatments to halt disease progression. The tissue expression and localization of a number of pro-inflammatory cytokines, growth and matrix factors were investigated in eyelid tissue from 20 individuals with trichiasis and from 16 control individuals. By staining tissue sections with dyes and specific antibodies, pro-inflammatory signaling molecules IL-1β and S100A7 and pro-fibrotic growth factor CTGF were found to be more highly expressed in individuals with trichiasis. CTGF and S100A7 were highly expressed in the epithelium; the outermost layer of the conjunctiva, whereas IL-1β was more highly expressed deeper in the tissue, where scarring occurs. Numerous inflammatory cells were found in the tissue of trichiasis patients even in the absence of clinically apparent inflammation. Future research should seek to describe a causative mechanism linking these factors.

[Tranilast inhibits myocardial fibrosis in mice with viral myocarditis]

OBJECTIVE

To investigate the effect of tranilast on myocardial fibrosis in mice with viral myocarditis (VMC).

METHODS

Male balb/c mice (n=72) were randomly divided into control, VMC and tranilast groups (n=24 each). In the VMC and tranilast groups, the mice were infected with Coxsackie virus B3 (CVB3) to prepare VMC model, while the control group was treated with Eagle's medium. After modeling, the tranilast group was administrated with tranilast [200 mg/(kg.d)] until the day before sampling. On days 7, 14 and 28 after CVB3 or Eagle's medium infection, heart specimens (n=8) were taken and examined after Toluidine blue staining and Nissl staining for counts of mast cells (MC), hematoxylin-eosin staining for myocardial pathological changes, and Masson staining for myocardial fibrosis. The expression of CTGF and type I collagen (Col I) in the myocardial tissue was measured by RT-PCR and Western blot. The correlations of CTGF mRNA expression with MC counts and Col I expression were analyzed.

RESULTS

The myocardial pathological changes and collagen volume fraction in the VMC group were significantly higher than in the control group at all three time points (P<0.05). Tranilast treatment significantly decreased the myocardial pathological changes and collagen volume fraction compared with the VMC group (P<0.05). The mRNA and protein expression of CTGF and Col I increased in the VMC group compared with the control group, and the increases were reduced with tranilast treatment (P<0.05). The number of MC was positively correlated to CTGF mRNA expression on the 7th day and 14th day (r=0.439, P=0.049) in the VMC group. There were positive correlations between the mRNA expression of Col I and CTGF on the 7th day and 14th day (r=0.646, P=0.007) and the 28th day (r=0.326, P=0.031).

CONCLUSIONS

Tranilast may inhibit the aggregation of MC and down-regulate the expression of CTGF, relieving myocardial fibrosis of mice with VMC.

[Tranilast inhibits myocardial fibrosis in mice with viral myocarditis]

OBJECTIVE

To investigate the effect of tranilast on myocardial fibrosis in mice with viral myocarditis (VMC).

METHODS

Male balb/c mice (n=72) were randomly divided into control, VMC and tranilast groups (n=24 each). In the VMC and tranilast groups, the mice were infected with Coxsackie virus B3 (CVB3) to prepare VMC model, while the control group was treated with Eagle's medium. After modeling, the tranilast group was administrated with tranilast [200 mg/(kg.d)] until the day before sampling. On days 7, 14 and 28 after CVB3 or Eagle's medium infection, heart specimens (n=8) were taken and examined after Toluidine blue staining and Nissl staining for counts of mast cells (MC), hematoxylin-eosin staining for myocardial pathological changes, and Masson staining for myocardial fibrosis. The expression of CTGF and type I collagen (Col I) in the myocardial tissue was measured by RT-PCR and Western blot. The correlations of CTGF mRNA expression with MC counts and Col I expression were analyzed.

RESULTS

The myocardial pathological changes and collagen volume fraction in the VMC group were significantly higher than in the control group at all three time points (P<0.05). Tranilast treatment significantly decreased the myocardial pathological changes and collagen volume fraction compared with the VMC group (P<0.05). The mRNA and protein expression of CTGF and Col I increased in the VMC group compared with the control group, and the increases were reduced with tranilast treatment (P<0.05). The number of MC was positively correlated to CTGF mRNA expression on the 7th day and 14th day (r=0.439, P=0.049) in the VMC group. There were positive correlations between the mRNA expression of Col I and CTGF on the 7th day and 14th day (r=0.646, P=0.007) and the 28th day (r=0.326, P=0.031).

CONCLUSIONS

Tranilast may inhibit the aggregation of MC and down-regulate the expression of CTGF, relieving myocardial fibrosis of mice with VMC.

NADPH oxidase 4 contributes to connective tissue growth factor expression through Smad3-dependent signaling pathway

Transforming growth factor-β (TGF-β)/Smad signaling has been implicated in connective tissue growth factor (CTGF) expression in vascular smooth muscle cells (VSMC). Reactive oxygen species (ROS) are involved in activation of TGF-β/Smad signaling. However, detailed mechanisms underlying the process remain unclear. In present study, we demonstrated TGF-β1 strongly induced CTGF expression, Smad3 activation, NADPH oxidase 4 (Nox4) expression and increased ROS production in primary rat VSMC in vitro. NADPH oxidases inhibitor diphenylene iodonium (DPI) eliminated TGF-β1-induced CTGF expression and ROS generation. In addition, small-interfering RNA (siRNA) silencing of Smad3 or Nox4 significantly suppressed TGF-β1-mediated CTGF expression in VSMC. Furthermore, Nox4 silencing or inhibition eliminated TGF-β1-induced Smad3 activation and interaction between Nox4 and Smad3. In vivo studies further identified a positive correlation of Nox4 levels with Smad3 activation and CTGF expression in atherosclerotic arteries of patients and animal models. These data established that a novel mechanistic link of Nox4-dependent activation of Smad3 to increased TGF-β1-induced CTGF in the process of vascular remodeling, which suggested a new potential pathway for therapeutic interventions.

Downregulation of miR-30c promotes renal fibrosis by target CTGF in diabetic nephropathy

MicroRNAs (miRs) play important roles in initiation and progression of many pathologic processes. However, the role of miR-30c in diabetic nephropathy (DN) remains unclear. This study was to determine whether miR-30c was involved in the mechanism of renal fibrosis by inhibiting target CTGF expression in DN. In this study, In Situ Hybridization(ISH), RT-PCR, cell transfection, western blotting and laser confocal telescope were used, respectively. ISH showed that miR-30c, concentrated in cytoplasmic foci in the proximity of the nucleus, was mainly localized in glomerular and renal tubular epithelial cells within the cortex. RT-PCR showed that miR-30c expression was significantly decreased in DN (p<0.05), consistent with of the results of ISH. Luciferase reporter gene assays showed that CTGF was a validated target of miR-30c. Furthermore, miR-30c overexpression directly decreased CTGF mRNA and protein. Conversely, miR-30c inhibitor enhanced CTGF expression. Interestingly, miR-30c expression was negatively correlated with ACR (r=-0.870, P=0.003) and positively correlated with Ccr (r=0.8230, P=0.01), whereas it was uncorrelated with KW/BW, SBP, HbA1C, HOMR-IR and T-Cho (p>0.05). More importantly, miR-30c mimics significantly decreased col-IV, FN, GSI, GBM, GA, MRA/CLA and ACR (p<0.05) and, in contrast, slightly but significantly increased Ccr (p<0.05). In conclusion, our results suggested that loss of miR-30c may contribute to the pathogenesis of DN by inhibiting target CTGF expression; replenishing miR-30c may ameliorate renal structure and function by reducing renal fibrosis in DN.

TGFβ and BMP Dependent Cell Fate Changes Due to Loss of Filamin B Produces Disc Degeneration and Progressive Vertebral Fusions

Spondylocarpotarsal synostosis (SCT) is an autosomal recessive disorder characterized by progressive vertebral fusions and caused by loss of function mutations in Filamin B (FLNB). FLNB acts as a signaling scaffold by linking the actin cytoskleteon to signal transduction systems, yet the disease mechanisms for SCT remain unclear. Employing a Flnb knockout mouse, we found morphologic and molecular evidence that the intervertebral discs (IVDs) of Flnb^–/–mice undergo rapid and progressive degeneration during postnatal development as a result of abnormal cell fate changes in the IVD, particularly the annulus fibrosus (AF). In Flnb^–/–mice, the AF cells lose their typical fibroblast-like characteristics and acquire the molecular and phenotypic signature of hypertrophic chondrocytes. This change is characterized by hallmarks of endochondral-like ossification including alterations in collagen matrix, expression of Collagen X, increased apoptosis, and inappropriate ossification of the disc tissue. We show that conversion of the AF cells into chondrocytes is coincident with upregulated TGFβ signaling via Smad2/3 and BMP induced p38 signaling as well as sustained activation of canonical and noncanonical target genes p21 and Ctgf. These findings indicate that FLNB is involved in attenuation of TGFβ/BMP signaling and influences AF cell fate. Furthermore, we demonstrate that the IVD disruptions in Flnb^–/–mice resemble aging degenerative discs and reveal new insights into the molecular causes of vertebral fusions and disc degeneration.

Whereas there is a large foundation of knowledge concerning skeletal formation and development, identifying the molecular changes behind Intervertebral Disc (IVD) aging and degeneration has been a challenge. The loss of Filamin B, a protein component of the cell’s cytoskeletal structure, gives rise to Spondylocarpotarsal Synostosis, a rare genetic disorder characterized by fusions of the vertebral bodies. Similarly, mice lacking the Filamin B protein show fusions of the vertebral bodies. We found that these fusions are caused by the early degeneration and eventual ossification of the IVDs. Our study demonstrates that this degeneration is caused by the increase in TGFβ and BMP activity, developmental pathways essential in bone and cartilage formation. These findings represent a significant step forward in our understanding of the molecular basis of IVD degeneration. as well as revealing filamin B’s role in TGFβ/BMP signaling regulation. Moreover, we demonstrate that the study of the rare disease spondylocarpotarsal synostosis in a model organism can uncover mechanisms underlying more common diseases. Finally, our findings provide a model system that will facilitate further discoveries regarding disc degeneration, which affects a significant proportion of the population.

Multistrand Structure Prediction of Nucleic Acid Assemblies and Design of RNA Switches

RNA is an attractive material for the creation of molecular logic gates that release programmed functionalities only in the presence of specific molecular interaction partners. Here we present HyperFold, a multistrand RNA/DNA structure prediction approach for predicting nucleic acid complexes that can contain pseudoknots. We show that HyperFold also performs competitively compared to other published folding algorithms. We performed a large variety of RNA/DNA hybrid reassociation experiments for different concentrations, DNA toehold lengths, and G+C content and find that the observed tendencies for reassociation correspond well to computational predictions. Importantly, we apply this method to the design and experimental verification of a two-stranded RNA molecular switch that upon binding to a single-stranded RNA toehold disease-marker trigger mRNA changes its conformation releasing an shRNA-like Dicer substrate structure. To demonstrate the concept, connective tissue growth factor (CTGF) mRNA and enhanced green fluorescent protein (eGFP) mRNA were chosen as trigger and target sequences, respectively. In vitro experiments confirm the formation of an RNA switch and demonstrate that the functional unit is being released when the trigger RNA interacts with the switch toehold. The designed RNA switch is shown to be functional in MDA-MB-231 breast cancer cells. Several other switches were also designed and tested. We conclude that this approach has considerable potential because, in principle, it allows the release of an siRNA designed against a gene that differs from the gene that is utilized as a biomarker for a disease state.

The Hippo pathway mediates inhibition of vascular smooth muscle cell proliferation by cAMP

AIMS

Inhibition of vascular smooth muscle cell (VSMC) proliferation by intracellular cAMP prevents excessive neointima formation and hence angioplasty restenosis and vein-graft failure. These protective effects are mediated via actin-cytoskeleton remodelling and subsequent regulation of gene expression by mechanisms that are incompletely understood. Here we investigated the role of components of the growth-regulatory Hippo pathway, specifically the transcription factor TEAD and its co-factors YAP and TAZ in VSMC.

METHODS AND RESULTS

Elevation of cAMP using forskolin, dibutyryl-cAMP or the physiological agonists, Cicaprost or adenosine, significantly increased phosphorylation and nuclear export YAP and TAZ and inhibited TEAD-luciferase report gene activity. Similar effects were obtained by inhibiting RhoA activity with C3-transferase, its downstream kinase, ROCK, with Y27632, or actin-polymerisation with Latrunculin-B. Conversely, expression of constitutively-active RhoA reversed the inhibitory effects of forskolin on TEAD-luciferase. Forskolin significantly inhibited the mRNA expression of the pro-mitogenic genes, CCN1, CTGF, c-MYC and TGFB2 and this was reversed by expression of constitutively-active YAP or TAZ phospho-mutants. Inhibition of YAP and TAZ function with RNAi or Verteporfin significantly reduced VSMC proliferation. Furthermore, the anti-mitogenic effects of forskolin were reversed by overexpression of constitutively-active YAP or TAZ.

CONCLUSION

Taken together, these data demonstrate that cAMP-induced actin-cytoskeleton remodelling inhibits YAP/TAZ-TEAD dependent expression of pro-mitogenic genes in VSMC. This mechanism contributes novel insight into the anti-mitogenic effects of cAMP in VSMC and suggests a new target for intervention.

Endothelin-1 Overexpression Improves Renal Function in eNOS Knockout Mice

BACKGROUND/AIMS

To investigate the renal phenotype under conditions of an activated renal ET-1 system in the status of nitric oxide deficiency, we compared kidney function and morphology in wild-type, ET-1 transgenic (ET+/+), endothelial nitric oxide synthase knockout (eNOS-/-) and ET+/+eNOS-/- mice.

METHODS

We assessed blood pressure, parameters of renal morphology, plasma cystatin C, urinary protein excretion, expression of genes associated with glomerular filtration barrier and tissue remodeling, and plasma metabolites using metabolomics.

RESULTS

eNOS-/- and ET+/+eNOS-/- mice developed hypertension. Osteopontin, albumin and protein excretion were increased in eNOS-/- and restored in ET+/+eNOS-/- animals. All genetically modified mice developed renal interstitial fibrosis and glomerulosclerosis. Genes involved in tissue remodeling (serpine1, TIMP1, Col1a1, CCL2) were up-regulated in eNOS-/-, but not in ET+/+eNOS-/- mice. Plasma levels of free carnitine and acylcarnitines, amino acids, diacyl phosphatidylcholines, lysophosphatidylcholines and hexoses were descreased in eNOS-/- and were in the normal range in ET+/+eNOS-/- mice.

CONCLUSION

eNOS-/- mice developed renal dysfunction, which was partially rescued by ET-1 overexpression in eNOS-/- mice. The metabolomics results suggest that ET-1 overexpression on top of eNOS knockout is associated with a functional recovery of mitochondria (rescue effect in β-oxidation of fatty acids) and an increase in antioxidative properties (normalization of monounsaturated fatty acids levels).

Regulation of Connective Tissue Growth Factor and Cardiac Fibrosis by an SRF/MicroRNA-133a Axis

Myocardial fibrosis contributes to the remodeling of heart and the loss of cardiac function leading to heart failure. SRF is a transcription factor implicated in the regulation of a large variety of genes involved in cardiac structure and function. To investigate the impact of an SRF overexpression in heart, we developed a new cardiac-specific and tamoxifen-inducible SRF overexpression mouse model by the Cre/loxP strategy. Here, we report that a high level overexpression of SRF leads to severe modifications of cardiac cytoarchitecture affecting the balance between cardiomyocytes and cardiac fibroblasts and also a profound alteration of cardiac gene expression program. The drastic development of fibrosis was characterized by intense sirius red staining and associated with an increased expression of genes encoding extracellular matrix proteins such as fibronectin, procollagen type 1α1 and type 3α1 and especially connective tissue growth factor (CTGF). Furthermore miR-133a, one of the most predominant cardiac miRNAs, is strongly downregulated when SRF is overexpressed. By comparison a low level overexpression of SRF has minor impact on these different processes. Investigation with miR-133a, antimiR-133a and AdSRF-VP16 experiments in H9c2 cardiac cells demonstrated that: 1)–miR-133a acts as a repressor of SRF and CTGF expression; 2)–a simultaneous overexpression of SRF by AdSRF-VP16 and inhibition of miR-133a by a specific antimiR increase CTGF expression; 3)–miR-133a overexpression can block the upregulation of CTGF induced by AdSRF-VP16. Taken together, these findings reveal a key role of the SRF/CTGF/miR-133a axis in the regulation of cardiac fibrosis.

Sildenafil attenuates the fibrotic phenotype of skin fibroblasts in patients with systemic sclerosis

Systemic sclerosis (SSc) is a multi-organ fibrotic disease that affects the skin and various internal organs. Therapeutic strategies for tissue fibrosis have not been established; however, aberrantly activated fibroblasts in affected lesions are key targets for modulating fibrosis. Recently, increased intracellular cyclic GMP (cGMP) levels were demonstrated to improve fibrosis levels in various diseases. The purpose of this study was to assess the anti-fibrotic properties of cGMP in cultured fibroblasts from patients with SSc. The phosphodiesterase (PDE) 5 inhibitor sildenafil increased the intracellular cGMP levels in skin fibroblasts in a dose-dependent manner. Sildenafil treatment also significantly decreased the expression of several pro-fibrotic factors that were upregulated by TGF-β1 treatment in SSc skin fibroblasts. These inhibitory effects occurred via non-canonical TGF-β signaling. Our findings revealed that sildenafil might be a novel strategy to treat tissue fibrosis and vasculopathy in SSc.

Ranolazine protects from doxorubicin-induced oxidative stress and cardiac dysfunction

AIMS

Doxorubicin is widely used against cancer; however, it can produce heart failure (HF). Among other hallmarks, oxidative stress is a major contributor to HF pathophysiology. The late INa inhibitor ranolazine has proven effective in treating experimental HF. Since elevated [Na+]i is present in failing myocytes, and has been recently linked with reactive oxygen species (ROS) production, our aim was to assess whether ranolazine prevents doxorubicin-induced cardiotoxicity, and whether blunted oxidative stress is a mechanism accounting for such protection.

METHODS AND RESULT

In C57BL6 mice, doxorubicin treatment for 7 days produced LV dilation and decreased echo-measured fractional shortening (FS). Ranolazine (305 mg/kg/day) prevented LV dilation and dysfunction when co-administered with doxorubicin. Doxorubicin-induced cardiotoxicity was accompanied instead by elevations in atrial natriuretic peptide (ANP), BNP, connective tissue growth factor (CTGF), and matrix metalloproteinase 2 (MMP2) mRNAs, which were not elevated on co-treatment with ranolazine. Alterations in extracellular matrix remodelling were confirmed by an increase in interstitial collagen, which did not rise in ranolazine-co-treated hearts. Levels of poly(ADP-ribose) polymerase (PARP) and pro-caspase-3 measured by western blotting were lowered with doxorubicin, with increased cleavage of caspase-3, indicating activation of the proapoptotic machinery. Again, ranolazine prevented this activation. Furthermore, in HL-1 cardiomyocytes transfected with HyPer to monitor H2O2 emission, besides reducing the extent of cell death, ranolazine prevented the occurrence of oxidative stress caused by doxorubicin. Interestingly, similar protective results were obtained with the Na+/Ca2+ exchanger (NCX) inhibitor KB-R7943.

CONCLUSIONS

Ranolazine protects against experimental doxorubicin cardiotoxicity. Such protection is accompanied by a reduction in oxidative stress, suggesting that INa modulates cardiac redox balance, resulting in functional and morphological derangements.

Ets-1 upregulation mediates angiotensin II-related cardiac fibrosis

Ets-1, the prototypical member of the family of Ets transcription factors, has been shown to participate in tissue fibrotic remodeling. However, its role in cardiac fibrosis has not been established. The aim of this study was to investigate the role of Ets-1 in profibrotic actions of angiotensin II (Ang II) in cardiac fibroblasts (CFs) and in the in vivo heart. In growth-arrested CFs, Ang II induced Ets-1 expression in a time- and concentration-dependent manner. Pretreatment with Ang II type 1 receptor blocker losartan, protein kinase C inhibitor bisindolylmaleimide I, extracellular signal-regulated kinase (ERK) inhibitor PD98059, or c-Jun NH(2)-terminal kinase (JNK) inhibitor SP600125 partly inhibited this induction accompanied with impaired cell proliferation and production of plasminogen activator inhibitor-1 (PAI-1) and connective tissue growth factor (CTGF) protein, the two downstream targets of Ets-1. Knockdown of Ets-1 by siRNA significantly inhibited the inductive effects of Ang II on cell proliferation and expression of CTGF and PAI-1. Moreover, the levels of Ets-1, PAI-1 and CTGF protein were simultaneously upregulated in left ventricle of Ang II-infused rats in parallel with an increase in the activation of ERK and JNK. Our data suggest that Ets-1 may mediate Ang II-induced cardiac fibrotic effects.

Cucurbitacin I Attenuates Cardiomyocyte Hypertrophy via Inhibition of Connective Tissue Growth Factor (CCN2) and TGF- β/Smads Signalings

Cucurbitacin I is a naturally occurring triterpenoid derived from Cucurbitaceae family plants that exhibits a number of potentially useful pharmacological and biological activities. However, the therapeutic impact of cucurbitacin I on the heart has not heretofore been reported. To evaluate the functional role of cucurbitacin I in an in vitro model of cardiac hypertrophy, phenylephrine (PE)-stimulated cardiomyocytes were treated with a sub-cytotoxic concentration of the compound, and the effects on cell size and mRNA expression levels of ANF and β-MHC were investigated. Consequently, PE-induced cell enlargement and upregulation of ANF and β-MHC were significantly suppressed by pretreatment of the cardiomyocytes with cucurbitacin I. Notably, cucurbitacin I also impaired connective tissue growth factor (CTGF) and MAPK signaling, pro-hypertrophic factors, as well as TGF-β/Smad signaling, the important contributing factors to fibrosis. The protective impact of cucurbitacin I was significantly blunted in CTGF-silenced or TGF-β1-silenced hypertrophic cardiomyocytes, indicating that the compound exerts its beneficial actions through CTGF. Taken together, these findings signify that cucurbitacin I protects the heart against cardiac hypertrophy via inhibition of CTGF/MAPK, and TGF- β/Smad-facilitated events. Accordingly, the present study provides new insights into the defensive capacity of cucurbitacin I against cardiac hypertrophy, and further suggesting cucurbitacin I's utility as a novel therapeutic agent for the management of heart diseases.