CTGF modulates cell cycle progression in cAMP-arrested NRK fibroblasts

Do not overwork: cellular communication network factor 3 for life in cartilage

Cellular communication network factor (CCN) 3, which is one of the founding members of the CCN family, displays diverse functions. However, this protein generally represses the proliferation of a variety of cells. Along with skeletal development, CCN3 is produced in cartilaginous anlagen, growth plate cartilage and epiphysial cartilage. Interestingly, CCN3 is drastically induced in the growth plates of mice lacking CCN2, which promotes endochondral ossification. Notably, chondrocytes in these mutant mice with elevated CCN3 production also suffer from impaired glycolysis and energy metabolism, suggesting a critical role of CCN3 in cartilage metabolism. Recently, CCN3 was found to be strongly induced by impaired glycolysis, and in our study, we located an enhancer that mediated CCN3 regulation via starvation. Subsequent investigations specified regulatory factor binding to the X-box 1 (RFX1) as a transcription factor mediating this CCN3 regulation. Impaired glycolysis is a serious problem, resulting in an energy shortage in cartilage without vasculature. CCN3 produced under such starved conditions restricts energy consumption by repressing cell proliferation, leading chondrocytes to quiescence and survival. This CCN3 regulatory system is indicated to play an important role in articular cartilage maintenance, as well as in skeletal development. Furthermore, CCN3 continues to regulate cartilage metabolism even during the aging process, probably utilizing this regulatory system. Altogether, CCN3 seems to prevent "overwork" by chondrocytes to ensure their sustainable life in cartilage by sensing energy metabolism. Similar roles are suspected to exist in relation to systemic metabolism, since CCN3 is found in the bloodstream.

BMP and activin membrane-bound inhibitor regulate connective tissue growth factor controlling mesothelioma cell proliferation

Background

Malignant mesothelioma (MM) is an aggressive mesothelial cell cancer type linked mainly to asbestos inhalation. MM characterizes by rapid progression and resistance to standard therapeutic modalities such as surgery, chemotherapy, and radiotherapy. Our previous studies have suggested that tumor cell-derived connective tissue growth factor (CTGF) regulates the proliferation of MM cells as well as the tumor growth in mouse xenograft models.

Methods

In this study, we knock downed the bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) and CTGF in MM cells and investigated the relationship between both and their impact on the cell cycle and cell proliferation.

Results

The knockdown of CTGF or BAMBI reduced MM cell proliferation. In contrast to CTGF knockdown which decreased BAMBI, knockdown of BAMBI increased CTGF levels. Knockdown of either BAMBI or CTGF reduced expression of the cell cycle regulators; cyclin D3, cyclin-dependent kinase (CDK)2, and CDK4. Further, in silico analysis revealed that higher BAMBI expression was associated with shorter overall survival rates among MM patients.

Conclusions

Our findings suggest that BAMBI is regulated by CTGF promoting mesothelioma growth by driving cell cycle progression. Therefore, the crosstalk between BAMBI and CTGF may be an effective therapeutic target for MM treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10080-x.

Molecular and Genetic Interactions between CCN2 and CCN3 behind Their Yin-Yang Collaboration

Cellular communication network factor (CCN) 2 and 3 are the members of the CCN family that conduct the harmonized development of a variety of tissues and organs under interaction with multiple biomolecules in the microenvironment. Despite their striking structural similarities, these two members show contrastive molecular functions as well as temporospatial emergence in living tissues. Typically, CCN2 promotes cell growth, whereas CCN3 restrains it. Where CCN2 is produced, CCN3 disappears. Nevertheless, these two proteins collaborate together to execute their mission in a yin–yang fashion. The apparent functional counteractions of CCN2 and CCN3 can be ascribed to their direct molecular interaction and interference over the cofactors that are shared by the two. Recent studies have revealed the mutual negative regulation systems between CCN2 and CCN3. Moreover, the simultaneous and bidirectional regulatory system of CCN2 and CCN3 is also being clarified. It is of particular note that these regulations were found to be closely associated with glycolysis, a fundamental procedure of energy metabolism. Here, the molecular interplay and metabolic gene regulation that enable the yin–yang collaboration of CCN2 and CCN3 typically found in cartilage development/regeneration and fibrosis are described.

Mulberry leaf (Morus alba L.): A review of its potential influences in mechanisms of action on metabolic diseases

The leaves of Morus alba L. (called Sangye in Chinese, ML), which belong to the genus Morus., are highly valuable edible plants in nutrients and nutraceuticals. In Asian countries including China, Japan and Korea, ML are widely used as functional foods including beverages, noodles and herbal tea because of its biological and nutritional value. Meanwhile, ML-derived products in the form of powders, extracts and capsules are widely consumed as dietary supplements for controlling blood glucose and sugar. Clinical studies showed that ML play an important role in the treatment of metabolic diseases including the diabetes, dyslipidemia, obesity, atherosclerosis and hypertension. People broadly use ML due to their nutritiousness, deliciousness, safety, and abundant active benefits. However, the systematic pharmacological mechanisms of ML on metabolic diseases have not been fully revealed. Therefore, in order to fully utilize and scale relevant products about ML, this review summarizes the up-to-date information about the ML and its constituents effecting on metabolic disease.

Knockout of MMP3 Weakens Solid Tumor Organoids and Cancer Extracellular Vesicles

The tumor organoid (tumoroid) model in three-dimensional (3D) culture systems has been developed to reflect more closely the in vivo tumors than 2D-cultured tumor cells. Notably, extracellular vesicles (EVs) are efficiently collectible from the culture supernatant of gel-free tumoroids. Matrix metalloproteinase (MMP) 3 is a multi-functional factor playing crucial roles in tumor progression. However, roles of MMP3 within tumor growth and EVs have not unveiled. Here, we investigated the protumorigenic roles of MMP3 on integrities of tumoroids and EVs. We generated MMP3-knockout (KO) cells using the CRISPR/Cas9 system from rapidly metastatic LuM1 tumor cells. Moreover, we established fluorescent cell lines with palmitoylation signal-fused fluorescent proteins (tdTomato and enhanced GFP). Then we confirmed the exchange of EVs between cellular populations and tumoroids. LuM1-tumoroids released large EVs (200-1000 nm) and small EVs (50-200 nm) while the knockout of MMP3 resulted in the additional release of broken EVs from tumoroids. The loss of MMP3 led to a significant reduction in tumoroid size and the development of the necrotic area within tumoroids. MMP3 and CD9 (a category-1 EV marker tetraspanin protein) were significantly down-regulated in MMP3-KO cells and their EV fraction. Moreover, CD63, another member of the tetraspanin family, was significantly reduced only in the EVs fractions of the MMP3-KO cells compared to their counterpart. These weakened phenotypes of MMP3-KO were markedly rescued by the addition of MMP3-rich EVs or conditioned medium (CM) collected from LuM1-tumoroids, which caused a dramatic rise in the expression of MMP3, CD9, and Ki-67 (a marker of proliferating cells) in the MMP3-null/CD9-low tumoroids. Notably, MMP3 enriched in tumoroids-derived EVs and CM deeply penetrated recipient MMP3-KO tumoroids, resulting in a remarkable enlargement of solid tumoroids, while MMP3-null EVs did not. These data demonstrate that EVs can mediate molecular transfer of MMP3, resulting in increasing the proliferation and tumorigenesis, indicating crucial roles of MMP3 in tumor progression.

Evaluation of tear and aqueous humor level, and genetic variants of connective tissue growth factor as biomarkers for early detection of pseudoexfoliation syndrome/glaucoma

Pseudoexfoliation syndrome (PEX) may lead to the development of pseudoexfoliative glaucoma (PEG), a potential cause of irreversible blindness, if left untreated. This type of glaucoma often presents with much higher intraocular pressure (IOP) values than observed in primary open angle glaucoma, and patients are often unaware of their condition. Therefore, early diagnosis is of utmost importance in PEX and PEG. Unfortunately, no valid objective biomarkers are available that can be used for this purpose. The excessive synthesis and deposition of elastic microfibrillar pseudoexfoliation material is observed in the pathophysiology of PEX, therefore, growth factors may play roles in this pathology. Thus, in this study, we sought to determine the roles of phenotypes and genotypes of connective tissue growth factor (CTGF) as objective biomarkers for early diagnosis of PEX and PEG. Thus, we investigated possible associations involving tear and aqueous humor CTGF concentrations and four single nucleotide polymorphisms (SNPs) of the CTGF gene in PEX and PEG. The study was designed as a 2-year case-control study in the Turkish population. Study population was composed of 214 patients with PEG, 214 patients with PEX, and 214 age-matched controls for CTGF SNP analysis. Tear fluid study group consisted of 78 patients with PEG, 77 patients with PEX, and 78 controls. Aqueous humor analysis included 8 patients with PEG, 17 patients with PEX, and 23 controls. Tear fluid was collected using Schirmer strips, and aqueous humor samples were taken during cataract surgery. CTGF concentration was determined by ELISA, and total protein concentration was determined by Bradford assay in tear and aqueous humor samples. PCR followed by restriction fragment length polymorphism analysis was used for genotyping of rs6918698 G/C and rs9399005 C/T, while real-time PCR was used for rs9402373 C/G and rs12526196 T/C. Intraocular pressure, visual field score, mean deviation, and pattern standard deviation parameters were also evaluated. CTGF concentration in tear fluid was significantly higher in PEG patients compared with controls (P = 0.001), while it was lower in PEX patients. Similarly, total protein concentration in tear fluid was significantly increased in PEG patients relative to PEX patients (P = 0.026) and controls (P = 0.004). CTGF concentration in aqueous humor did not differ markedly between the groups, whereas total protein was significantly higher in the PEG group compared with the PEX group (P = 0.012) and controls (P = 0.003). Receiver operating characteristic analysis revealed that total protein in aqueous humor was a robust classifier for evaluating the presence of PEG against controls (Area under the curve = 0.897, P = 0.001). The genotypes of the studied SNPs were not significantly correlated with CTGF concentration in aqueous humor or tear fluid, and did not exhibit significant association with PEG or PEX. In conclusion, this was the first study to investigate tear fluid CTGF concentration in PEX and PEG, which came out not to be a good classifier for PEG or PEX. Total protein level in tear fluid and CTGF SNPs also did not predict PEG or PEX status successfully.

Circular RNA hsa_circ_0016070 Is Associated with Pulmonary Arterial Hypertension by Promoting PASMC Proliferation

Noncoding RNAs play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). In this study, we investigated the roles of hsa_circ_0016070, miR-942, and CCND1 in PAH. circRNA microarray was used to search circRNAs involved in PAH, whereas real-time PCR and western blot analysis were performed to detect miR-942 and CCND1 expression in different groups. In addition, the effect of miR-942 on CCND1 expression, as well as the effect of hsa_circ_0016070 on the expression of miR-942 and CCND1, was also studied using real-time PCR and western blot analysis. Moreover, MTT assay and flow cytometry were used to detect the effect of hsa _circ_0016070 on cell proliferation and cell cycle. According to the results of circRNA microarray analysis, hsa _circ_0016070 was identified to be associated with the risk of PAH in chronic obstructive pulmonary disease (COPD) patients. The miR-942 level in the COPD(+) PAH(+) group was much lower than that in the COPD(+) PAH(−) group, while the CCND1 level in the COPD(+) PAH(+) group was much higher. CCND1 was identified as a candidate target gene of miR-942, and the luciferase assay showed that the luciferase activity of wild-type CCND1 3′ UTR was inhibited by miR-942 mimics. In addition, hsa _circ_0016070 reduced miR-942 expression and enhanced CCND1 expression. Furthermore, hsa _circ_0016070 evidently increased cell viability and decreased the number of cells arrested in the G1/G0 phase. In summary, the results of this study suggested that hsa_circ_0016070 was associated with vascular remodeling in PAH by promoting the proliferation of pulmonary artery smooth muscle cells (PASMCs) via the miR-942/CCND1. Accordingly, has_circ_0016070 might be used as a novel biomarker in the diagnosis and treatment of PAH.

Proteasome inhibitor MG132 inhibits the process of renal interstitial fibrosis

The proteasome inhibitor pathway serves a crucial role in cell cycle progression and apoptosis, and in the activation of transcription factors and cytokines in tumor cells. The aim of the current study was to investigate the effect of the proteasome inhibitor, MG132, on transforming growth factor (TGF)-β1-induced expression of extracellular matrix proteins in rat renal interstitial fibroblasts (NRK-49F cells) and to better elucidate the mechanism by which MG132 functions. The level of connective tissue growth factor (CTGF), α-smooth muscle actin (SMA), fibronectin (FN) and collagen type III (Col III) in the MG132-pretreated groups was significantly decreased compared with groups treated with TGF-β1 alone. MG132 significantly decreased mRNA and the protein levels of fibrosis-associated factors induced by TGF-β1 treatment. The MG132-pretreated groups exhibited lower phosphorylated-mothers against decapentaplegic homolog (p-Smad)2, p-Smad3 and FN protein expression compared with the groups treated with TGF-β1 alone. In conclusion, MG132 reduced mRNA and protein expression of fibrosis-associated factors. It can successfully inhibit the inflammatory reaction induced by TGF-β via the Smad signaling pathway. These results indicate that MG132 appears to have a potent effect in counteracting renal fibrosis. MG132 may be applied in the treatment of patients with chronic kidney disease.

Mulberry leaf active components alleviate type 2 diabetes and its liver and kidney injury in db/db mice through insulin receptor and TGF-β/Smads signaling pathway

Mulberry leaf is one of the commonly used traditional Chinese medicines, has been shown to exert hypoglycemic effects against diabetes. The aim of this study is to investigate the effects and mechanism of mulberry leaf flavonoids (MF), polysaccharides (MP) and alkaloids (MA) on diabetic and its liver and kidney injury. The db/db mice was adopted and the results showed that the FBG (fasting blood glucose) of model group continued to increase and associated liver and kidney injury. After the intervention of MP and MA, the value of FBG exhibited the most obvious hypoglycemic effect. MF and MP have obvious improved effect on kidney injury, which reduced the content of mALB/Cre (microalbumin/creatinine) in urine and improved the tubular epithelial cells edematous and renal cystic epithelial thickening. While the MF and MA possessed a significant effect on liver damage, manifested in reducing the levels of ALT (alanine aminotransferase) and AST (aspartate aminotransferase) and pathological changes of liver on db/db mice. Through metabolomics analysis, 13 endogenous potential biomarkers were identified in serum. The three effective components of mulberry can regulate the 13 potential biomarkers and the corresponding metabolic pathway. Collectively, the components of mulberry leaf have clear hypoglycemic effect and protective effect on liver and kidney injury and the effects are related to insulin receptor and TGF-β/Smads signaling pathway.

Microrna-26b attenuates monocrotaline-induced pulmonary vascular remodeling via targeting connective tissue growth factor (CTGF) and cyclin D1 (CCND1)

MicroRNAs are involved in the control of cell growth, and deregulated pulmonary artery smooth muscle cell proliferation plays an essential role in the development of pulmonary hypertension. The objective of this study was to identify differentially expressed microRNA(s) and explore its therapeutic role in treatment of the disease. MicroRNA expression profile analysis showed microRNA-26b was differentially expressed in pulmonary artery smooth muscle cells harvested from monocrotaline-treated rats, and we validated microRNA-26b targets, in vitro and in vivo, CTGF and CCND1, both of which have been shown, in our previous work, to be involved in the pathogenesis of pulmonary hypertension. In vivo experiments demonstrated monocrotaline-induced pulmonary artery remodeling could be almost completely abolished by administration of microRNA-26b, while CTGF or CCND1 shRNA significantly, but only partially, attenuated the remodeling by silencing the designed target. Additionally, exogenous expression of the microRNA-26b substantially downregulated CTGF and CCND1 in human pulmonary artery smooth muscle cells. MicroRNA-26b might be a potent therapeutic tool to treat pulmonary hypertension.

TAZ responds to fluid shear stress to regulate the cell cycle

Physical forces associated with tumor growth and drainage alter cancer cell invasiveness and metastatic potential. We previously showed that fluid frictional force, or shear stress, typical of lymphatic flow induces YAP1/TAZ activation in prostate cancer cells to promote motility dependent upon YAP1 but not TAZ. Here, we show that shear stress elevates TAZ protein levels and promotes TAZ nuclear localization. Increased TAZ activity drives increased DNA synthesis and induces AMOTL2, ANKRD1, and CTGF gene transcription independently of YAP1. Ectopic expression of constitutively activated TAZ increases expression of these TAZ target genes and promotes cell proliferation of prostate cancer cells. Conversely, silencing of TAZ results in reduced proliferation. Together, our data show that force-induced TAZ regulates signaling that dictates cell division, and suggest that TAZ may govern cellular proliferation of cancer cells traveling through the lymphatics in response to biophysical cues.

WWC3 downregulation correlates with poor prognosis and inhibition of Hippo signaling in human gastric cancer

The aim of this study was to investigate the clinicopathological significance and biological roles of WWC3 in human gastric cancer (GC). Clinical significance of WWC3 in human GCs was examined by using immunohistochemistry (IHC). WWC3 was downregulated in 48 of 111 human GCs, and its downregulation was associated with advanced stage, positive nodal status, and higher relapse rate. Importantly, WWC3 downregulation correlated with poor survival. It was also found that WWC3 protein expression was downregulated in GC cell lines compared with normal cell line GES-1. On one hand, WWC3 overexpression inhibited the cell growth rate and invading ability in HGC-27 cell line. On the other hand, depleting WWC3 by small interfering RNA (siRNA) promoted proliferation rate and invading ability in the SGC-7901 cell line. In addition, cell cycle analysis showed that WWC3 overexpression inhibited while its depletion accelerated cell cycle progression at the G1/S transition. Western blot (WB) analysis demonstrated that WWC3 repressed cyclin D1 and cyclin E while upregulated p27 expression. Luciferase reporter assay showed that WWC3 activated Hippo signaling pathway by suppressing TEAD transcription activity, with downregulation of total and nuclear YAP and its target CTGF. WWC3 siRNA depletion exhibited the opposite effects. In conclusion, this study indicates that WWC3 serves as a tumor suppressor in GC by activating Hippo signaling.

Transforming Growth Factor β1 Promotes Migration and Invasion of Human Hepatocellular Carcinoma Cells Via Up-Regulation of Connective Tissue Growth Factor

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with a poor patient survival. Expression of TGF-β1 is up-regulated in HCC and is thought to play a crucial role in the occurrence and development of HCC. However, the mechanism of TGF-β1-mediated facilitation of malignant growth and invasion remains unclear, although some previous studies highlighted a potential involvement of the connective tissue growth factor (CTGF). Here we demonstrate that the in vitro migration of the HCC cell line SMMC-7721 is increased in the presence of recombinant TGF-β1, and that this effect is reversed by the specific inhibitor SB431542. Furthermore, TGF-β1 treatment up-regulated the expression of its own mRNA as well as the expression of CTGF mRNA. The TGF-β1-stimulated migration of SMMC-7721 cells was diminished by siRNA silencing of CTGF. These in vitro observations were validated in a murine xenograft model. In particular, silencing of CTFG diminished the TGF-β1-induced tumorigenesis in experimental animals. In conclusion, TGF-β1 plays a critical role in HCC migration and invasion, and this effect is dependent on CTGF.

Connective Tissue Metabolism and Gingival Overgrowth

Gingival overgrowth occurs mainly as a result of certain anti-seizure, immunosuppressive, or antihypertensive drug therapies. Excess gingival tissues impede oral function and are disfiguring. Effective oral hygiene is compromised in the presence of gingival overgrowth, and it is now recognized that this may have negative implications for the systemic health of affected patients. Recent studies indicate that cytokine balances are abnormal in drug-induced forms of gingival overgrowth. Data supporting molecular and cellular characteristics that distinguish different forms of gingival overgrowth are summarized, and aspects of gingival fibroblast extracellular matrix metabolism that are unique to gingival tissues and cells are reviewed. Abnormal cytokine balances derived principally from lymphocytes and macrophages, and unique aspects of gingival extracellular matrix metabolism, are elements of a working model presented to facilitate our gaining a better understanding of mechanisms and of the tissue specificity of gingival overgrowth.

The role of lamina cribrosa cells in optic nerve head fibrosis in glaucoma

Glaucoma is a chronic progressive optic neuropathy. There are extracellular matrix (ECM) changes associated with optic disc cupping in the optic nerve head (ONH) and subsequent visual field defects. The primary risk factor for onset and progression of glaucoma is raised intraocular pressure (IOP). Elevated IOP causes deformation at the ONH specifically at the lamina cribrosa (LC) region where there is also deposition of ECM causing the LC to initially undergo thickening and posterior migration with eventual shearing and collapse of the LC plates leading to a thin fibrotic connective tissue structure/scar. Cells that populate the LC region of the ONH are those cells that are positive for GFAP (the astrocytes) and those negative for GFAP (the LC cells). The LC cell plays an integral role in ECM remodelling producing ECM when exposed to high level mechanical stretch, TGF- β1 and a hypoxic environment.

Stroma-Derived Connective Tissue Growth Factor Maintains Cell Cycle Progression and Repopulation Activity of Hematopoietic Stem Cells In Vitro

Hematopoietic stem cells (HSCs) are preserved in co-cultures with UG26-1B6 stromal cells or their conditioned medium. We performed a genome-wide study of gene expression changes of UG26-1B6 stromal cells in contact with Lineage⁻ SCA-1⁺ KIT⁺ (LSK) cells. This analysis identified connective tissue growth factor (CTGF) to be upregulated in response to LSK cells. We found that co-culture of HSCs on CTGF knockdown stroma (shCtgf) shows impaired engraftment and long-term quality. Further experiments demonstrated that CD34⁻ CD48⁻ CD150⁺ LSK (CD34⁻ SLAM) cell numbers from shCtgf co-cultures increase in G0 and senescence and show delayed time to first cell division. To understand this observation, a CTGF signaling network model was assembled, which was experimentally validated. In co-culture experiments of CD34⁻ SLAM cells with shCtgf stromal cells, we found that SMAD2/3-dependent signaling was activated, with increasing p27(Kip1) expression and downregulating cyclin D1. Our data support the view that LSK cells modulate gene expression in the niche to maintain repopulating HSC activity.

The Association Between Aqueous Connective Tissue Growth Factor and the Severity of Age-related Cataracts as Graded by the Lens Opacities Classification System III

PURPOSE

To evaluate the relationship between aqueous humor concentrations of connective tissue growth factor (CTGF) and the severity of age-related cataracts.

MATERIALS AND METHODS

We conducted a prospective clinical study on 43 eyes of 43 patients with senile cataracts scheduled to undergo routine phacoemulsification surgery. Before surgery, all patients were graded for cataract severity using the Lens Opacities Classification System III in terms of four features: nuclear opalescence (NO), nuclear color (NC), cortical cataracts (C), and posterior sub-capsular cataracts (P). During surgery, aqueous humor samples were obtained from all patients, and sandwich enzyme-linked immunosorbent assays (ELISAs) were used to determine CTGF concentrations. To assess any relationship between cataract severity and CTGF levels of the aqueous humor, various correlation analyses and multiple linear regression were used.

RESULTS

We found a positive correlation between the overall cataract grade and aqueous CTGF level (p < 0.05). In addition, four features of the cataract grade (nuclear opalescence, nuclear color, cortical cataract and posterior sub-capsular cataract) were positively correlated with the aqueous CTGF concentration (p < 0.05). The final regression model identified overall cataract grade as an independent predictor of increased CTGF levels in the aqueous humor (p < 0.05).

CONCLUSIONS

CTGF tends to increase in the aqueous humor as the severity of age-related cataracts increases. Therefore, this cytokine may play an important role in the pathogenesis of age-related cataracts. Additional studies are required for clarification of this finding.

Whole-genome profiling highlights the molecular complexity underlying eccentric cardiac hypertrophy

OBJECTIVES

Heart failure is typically preceded by myocardial hypertrophy and remodeling, which can be concentric due to pressure overload (PO), or eccentric because of volume overload (VO). The molecular mechanisms that underlie these differing patterns of hypertrophy are distinct and have yet to be fully elucidated. Thus, the goal of this work is to identify novel therapeutic targets for cardiovascular conditions marked by hypertrophy that have previously been resistant to medical treatment, such as a pure VO.

METHODS

Concentric or eccentric hypertrophy was induced in rats for 2 weeks with transverse aortic constriction (TAC) or aortocaval fistula (ACF), respectively. Hemodynamic and echocardiographic analysis were used to assess the development of left ventricular (LV) hypertrophy and functional differences between groups. Changes in gene expression were determined by microarray and further characterized with Ingenuity Pathway Analysis.

RESULTS

Both models of hypertrophy increased LV mass. Rats with TAC demonstrated concentric LV remodeling while rats with ACF exhibited eccentric LV remodeling. Microarray analysis associated eccentric remodeling with a more extensive alteration of gene expression compared with concentric remodeling. Rats with VO had a marked activation of extracellular matrix genes, promotion of cell cycle genes, downregulation of genes associated with oxidative metabolism, and dysregulation of genes critical to cardiac contractile function. Rats with PO demonstrated similar categorical changes, but with the involvement of fewer individual genes.

CONCLUSIONS

Our results indicate that eccentric remodeling is a far more complex process than concentric remodeling. This study highlights the importance of several key biological functions early in the course of VO, including regulation of matrix, metabolism, cell proliferation, and contractile function. Thus, the results of this analysis will inform the ongoing search for new treatments to prevent the progression to heart failure in VO.

Functional and structural alterations of peritoneum and secretion of fibrotic cytokines in rats caused by high glucose peritoneal dialysis solutions

OBJECTIVE

To determine functional and structural alterations of peritoneum and fibrotic cytokines expression in peritoneal dialysis (PD) rats.

METHODS

28 Sprague-Dawley (S-D) rats were randomly divided into four groups and dialyzed with various solutions daily for four weeks: (1) no solution (CON group), (2) 0.9% Saline solution (NS group), (3) 1.5% Dianeal (LG group), (4) 4.25% Dianeal (HG group). Peritoneal equilibration tests, ultrafiltration function and effluent protein quantification were measured. Peritoneum morphology was studied and immunohistochemistry were performed for detection of transforming growth factor β1 (TGF-β1), connective tissue growth factor (CTGF), and fibronectin (FN) proteins. Reverse transcriptional-polymerase chain reaction was used to analyze the expression of TGF-β1, CTGF mRNA.

RESULTS

Administration of 4.25% Dianeal caused functional and structural changes of peritoneum, including protein loss through the transport process, decrease of peritoneal solute transport rate and ultrafiltration capacity. The collagen of peritoneum in the HG group was thicker than the other groups. The levels of CTGF, TGF-β1, and FN proteins were significantly the highest in the HG group, followed by the LG group. The liner correlation analysis showed positive correlations between the levels of CTGF, TGF-β1, and FN proteins and the collagen thickness. The expression of TGF-β1 and CTGF mRNA in the HG group were significantly higher than those in the other groups and were indicated positive correlation.

CONCLUSION

Using high glucose peritoneal dialysis solutions in rats may not only lead to processing of peritoneal fibrosis, which is promoted by ectopic expression of TGF-β1, but also increase the expression of CTGF. CTGF is an important fibrotic media of peritoneal fibrosis in PD rats.

New therapeutic targets for intraocular pressure lowering

Primary open-angle glaucoma (POAG) is a leading cause of irreversible and preventable blindness and ocular hypertension is the strongest known risk factor. With current classes of drugs, management of the disease focuses on lowering intraocular pressure (IOP). Despite of their use to modify the course of the disease, none of the current medications for POAG is able to reduce the IOP by more than 25%-30%. Also, some glaucoma patients show disease progression despite of the therapeutics. This paper examines the new described physiological targets for reducing the IOP. The main cause of elevated IOP in POAG is thought to be an increased outflow resistance via the pressure-dependent trabecular outflow system, so there is a crescent interest in increasing trabecular meshwork outflow by extracellular matrix remodeling and/or by modulation of contractility/TM cytoskeleton disruption. Modulation of new agents that act mainly on trabecular meshwork outflow may be the future hypotensive treatment for glaucoma patients. There are also other agents in which modulation may decrease aqueous humour production or increase uveoscleral outflow by different mechanisms from those drugs available for glaucoma treatment. Recently, a role for the ghrelin-GHSR system in the pathophysiology modulation of the anterior segment, particularly regarding glaucoma, has been proposed.

CTGF mediates Smad-dependent transforming growth factor β signaling to regulate mesenchymal cell proliferation during palate development

Transforming growth factor β (TGF-β) signaling plays crucial functions in the regulation of craniofacial development, including palatogenesis. Here, we have identified connective tissue growth factor (Ctgf) as a downstream target of the TGF-β signaling pathway in palatogenesis. The pattern of Ctgf expression in wild-type embryos suggests that it may be involved in key processes during palate development. We found that Ctgf expression is downregulated in both Wnt1-Cre; Tgfbr2(fl/fl) and Osr2-Cre; Smad4(fl/fl) palates. In Tgfbr2 mutant embryos, downregulation of Ctgf expression is associated with p38 mitogen-activated protein kinase (MAPK) overactivation, whereas loss of function of Smad4 itself leads to downregulation of Ctgf expression. We also found that CTGF regulates its own expression via TGF-β signaling. Osr2-Cre; Smad4(fl/fl) mice exhibit a defect in cell proliferation similar to that of Tgfbr2 mutant mice, as well as cleft palate. We detected no alteration in bone morphogenetic protein (BMP) downstream targets in Smad4 mutant palates, suggesting that the reduction in cell proliferation is due to defective transduction of TGF-β signaling via decreased Ctgf expression. Significantly, an exogenous source of CTGF was able to rescue the cell proliferation defect in both Tgfbr2 and Smad4 mutant palates. Collectively, our data suggest that CTGF regulates proliferation as a mediator of the canonical pathway of TGF-β signaling during palatogenesis.

Inhibition of connective tissue growth factor (CTGF/CCN2) in gallbladder cancer cells leads to decreased growth in vitro

Gallbladder cancer (GBC) is an aggressive neoplasm associated with late diagnosis, unsatisfactory treatment and poor prognosis. Previous work showed that connective tissue growth factor (CTGF) expression is increased in this malignancy. This matricellular protein plays an important role in various cellular processes and its involvement in the tumorigenesis of several human cancers has been demonstrated. However, the precise function of CTGF expression in cancer cells is yet to be determined. The aim of this study was to evaluate the CTGF expression in gallbladder cancer cell lines, and its effect on cell viability, colony formation and in vitro cell migration. CTGF expression was evaluated in seven GBC cell lines by Western blot assay. Endogenous CTGF expression was downregulated by lentiviral shRNA directed against CTGF mRNA in G-415 cells, and the effects on cell viability, anchorage-independent growth and migration was assessed by comparing them to scrambled vector-transfected cells. Knockdown of CTGF resulted in significant reduction in cell viability, colony formation and anchorage-independent growth (P < 0.05). An increased p27 expression was observed in G-415 cells with loss of CTGF function. Our results suggest that high expression of this protein in gallbladder cancer may confer a growth advantage for neoplastic cells.

Role of CTGF/CCN2 in reparative dentinogenesis in human dental pulp

Connective tissue growth factor/CCN family 2 (CTGF/CCN2) has been considered to participate in tooth development. To date, the expression and role of CTGF/CCN2 in reparative dentinogenesis have been unclear. Our previous study revealed that matrix metalloproteinase-3 (MMP-3) stimulates cell migration via CTGF/CCN2 expression and secretion in human dental pulp cells, and that this is dependent on dynamin-related endocytosis and independent of protease activity. The objective of the present study was to determine the expression of CTGF/CCN2 in reparative dentin in human carious teeth and to examine the effect of CTGF/CCN2 on mineralization in cultured human dental pulp cells. Minimal expression of CTGF/CCN2 was evident in odontoblasts subjacent to the dentin-pulp junction in healthy teeth, whereas strong expression was detected in odontoblast-like cells lining the reparative dentin subjacent to dental caries. In human dental pulp cells, CTGF/CCN2 promoted mineralization but failed to induce proliferation, suggesting that this molecule has the ability to induce the differentiation of human dental pulp cells. Taken together, the data suggest that CTGF/CCN2 is likely involved in reparative dentinogenesis through formation of hard tissue in human carious teeth.

CCN2 promotes cigarette smoke-induced proliferation of rat pulmonary artery smooth muscle cells through upregulating cyclin D1 expression

Cigarette smoke has been demonstrated to induce pulmonary vascular remodeling, which is characterized by medial thickening of the pulmonary arteries mainly resulting from the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs). However, the molecular mechanism underlying this process is still unclear. In the present study, we investigated whether CCN2 regulated rat PASMCs (rPASMCs) proliferation induced by cigarette smoke extract (CSE) and nicotine by upregulating cyclin D1 in vitro. CCN2 siRNA or cyclin D1 siRNA were transfected to rPASMCs which were then exposed to CSE and nicotine. Both mRNA and protein expressions of CCN2 were significantly increased in rPASMCs treated with 2% CSE or 1 µM nicotine, which markedly promoted the proliferation of rPASMCs. CCN2 siRNA inhibited the proliferation of rPASMCs induced by CSE or nicotine. Furthermore, CCN2 siRNA markedly suppressed the mRNA and protein expressions of cyclin D1 in rPASMCs and led to cell cycle arrest in G0/G1 phase resulting in reduced rPASMCs proliferation. These findings suggest that CCN2 contributes to the CSE and nicotine-induced proliferation of rPASMCs at least in part by upregulating cyclin D1 expression.

Knockdown of connective tissue growth factor by plasmid-based short hairpin RNA prevented pulmonary vascular remodeling in cigarette smoke-exposed rats

Cigarette smoking may contribute to pulmonary hypertension in chronic obstructive pulmonary disease by resulting in pulmonary vascular remodeling that involves pulmonary artery smooth muscle cell proliferation. Connective tissue growth factor (CTGF) is a cysteine-rich peptide implicated in several biological processes such as cell proliferation, survival, and migration. This study investigated the potential role of CTGF in pulmonary vascular remodeling. We constructed a plasmid-based short hairpin RNA (shRNA) to knock down the expression of CTGF in primary cultured rat pulmonary artery smooth muscle cells (rPASMCs) and in rat lung vessels. Rat PASMCs were challenged with cigarette smoke extract (CSE). Rats were exposed to cigarette smoke for 3 months in the absence or in the presence of plasmid-based short hairpin RNA against CTGF which was administrated by tail vein injection. CTGFshRNA significantly prevented CTGF and cyclin D1 expression, arrested cell cycle at G0/G1 phase and suppressed cell proliferation in rPASMCs exposed to CSE. CTGFshRNA administration ameliorated pulmonary vascular remodeling, inhibited cigarette smoke-induced CTGF elevation and reversed the cyclin D1 increase in pulmonary vessels in rats. Collectively, our data demonstrated that plasmid-based shRNA against CTGF attenuated pulmonary vascular remodeling in cigarette smoke-exposed rats.

Southwest Oncology Group Study S0530: a phase 2 trial of clofarabine and cytarabine for relapsed or refractory acute lymphocytic leukaemia

Clofarabine and cytarabine target different steps in DNA synthesis and replication, are synergistic in vivo, and have non-overlapping toxicities, making this combination a potentially promising treatment for acute lymphocytic leukaemia. Thirty-seven patients were treated. The median age was 41 years, 44% of patients were either in ≥2nd relapse or had refractory disease and 59% of patients had poor risk cytogenetics. Six out of 36 patients (17%) achieved a complete remission with or without complete count recovery; median overall survival was 3 months. Nucleoside transporter expression did not predict outcome. This regimen lacked sufficient activity to warrant further testing.

Connective tissue growth factor knockdown attenuated matrix protein production and vascular endothelial growth factor expression induced by transforming growth factor-beta1 in cultured human peritoneal mesothelial cells

Connective tissue growth factor (CTGF), a downstream mediator of transforming growth factor-beta1 (TGF-beta1) inducing fibrosis, has recently been implicated in peritoneal fibrosis. Extracellular matrix (ECM) accumulation and angiogenesis are characteristic changes in peritoneal fibrosis. In this study we investigated the effect of CTGF knockdown via interference RNA (RNAi) on ECM production and vascular endothelial growth factor (VEGF) expression induced by TGF-beta1 in human peritoneal mesothelial cells (HPMCs). Four CTGF short hairpin RNA (shRNA) expression constructs were generated using the pRetroSuper vector, and infectious retroviral particles were prepared to infect HPMCs. Expression levels of CTGF, fibronectin(FN), collagen 1 (col 1), laminin, and VEGF mRNA and protein were measured by semi-quantitative reverse transcription polymerase chain reaction and western blot assay. CTGF expression was increased after stimulation with TGF-beta1, but inhibited using each of the four independent CTGF shRNA constructs (P < 0.01). Moreover, expression of ECM proteins (FN, col 1, and laminin) and VEGF were upregulated after incubation with TGF-beta1, but elevated levels of ECM and VEGF induced by TGF-beta1 were significantly inhibited by RNAi (P < 0.01), but not by the empty retroviral vector (P > 0.05). From these results, we concluded that retrovirus-mediated CTGF shRNA can effectively inhibit ECM production and VEGF expression induced by TGF-beta1 in HPMCs. This study suggests that downregulation of CTGF may represent a potential therapeutic approach for peritoneal fibrosis through decreasing ECM accumulation and angiogenesis.

[Effect of compound Biejia Ruangan tablet on expressions of connective tissue growth factor mRNA and protein in kidney tissue of rats with adriamycin-induced nephropathy]

OBJECTIVE

To investigate the changes of connective tissue growth factor (CTGF) protein and CTGF mRNA in kidney tissue of rats with adriamycin (ADR)-induced nephropathy and to study the effects of compound Biejia Ruangan tablet (CBJRGT), a traditional Chinese herbal medicine for treatment of liver fibrosis.

METHODS

A rat model of ADR-induced nephropathy after one-sided nephrectomy was established. Forty-five Wistar rats were randomly divided into 5 groups: normal control group, sham-operated group, untreated group, lotensin-treated group and CBJRGT-treated group. Pathological changes of the kidney tissue were observed by microscopy after 10-week drug administration. The expressions of CTGF protein and CTGF mRNA in the kidney tissue were measured by the methods of immunohistochemistry and in situ hybridization.

RESULTS

The expressions of CTGF protein and CTGF mRNA in the normal and sham-operated groups were decreased in the intracytoplasm of glomerular mesangial cells, renal tubular epithelial cells and interstitial cells. Compared with the sham-operated group, the expressions of CTGF protein and CTGF mRNA in the untreated group were markedly increased and the development of renal fibrosis in the untreated group could be observed. CBJRGT could significantly decrease the expressions of CTGF protein and CTGF mRNA, and there was no significant difference between CBJRGT-treated group and lotensin-treated group.

CONCLUSION

CBJRGT may suppress the development of fibrosis through down-regulating the expressions of CTGF protein and CTGF mRNA.

Identification of G1-regulated genes in normally cycling human cells

Background

Obtaining synchronous cell populations is essential for cell-cycle studies. Methods such as serum withdrawal or use of drugs which block cells at specific points in the cell cycle alter cellular events upon re-entry into the cell cycle. Regulatory events occurring in early G1 phase of a new cell cycle could have been overlooked.

Methodology and Findings

We used a robotic mitotic shake-off apparatus to select cells in late mitosis for genome-wide gene expression studies. Two separate microarray experiments were conducted, one which involved isolation of RNA hourly for several hours from synchronous cell populations, and one experiment which examined gene activity every 15 minutes from late telophase of mitosis into G1 phase. To verify synchrony of the cell populations under study, we utilized methods including BrdU uptake, FACS, and microarray analyses of histone gene activity. We also examined stress response gene activity. Our analysis enabled identification of 200 early G1-regulated genes, many of which currently have unknown functions. We also confirmed the expression of a set of genes candidates (fos, atf3 and tceb) by qPCR to further validate the newly identified genes.

Conclusion and Significance

Genome-scale expression analyses of the first two hours of G1 in naturally cycling cells enabled the discovery of a unique set of G1-regulated genes, many of which currently have unknown functions, in cells progressing normally through the cell division cycle. This group of genes may contain future targets for drug development and treatment of human disease.

Connective tissue growth factor: structure-function relationships of a mosaic, multifunctional protein

Connective tissue growth factor (CTGF) is a member of the CCN family of six small secreted, cysteine-rich growth factors. The unique modular structure encompasses distinct functional domains which enable CTGF to interact with growth factors, surface receptors and matrix components. Widely expressed, CTGF has critical roles in embryonic development and the maintenance of normal cell and connective tissue function. It is also important for tissue repair following injury, and has been implicated in common diseases including atherosclerosis, pulmonary and renal fibrotic disorders and cancer. Factors that regulate CTGF transcription in response to exogenous stimuli, as well as downstream signalling pathways, have been described. However, only recently have studies begun to unravel how the functional domains within the CTGF modules orchestrate signals and control key biological processes. This article highlights how the structural and functional domains of CTGF and CTGF cleavage fragments integrate multiple extracellular events into cell signals.

Connective tissue growth factor (CTGF) expression and outcome in adult patients with acute lymphoblastic leukemia

We compared the gene expression profile of adult acute lymphoblastic leukemia (ALL) to normal hematopoietic and non-ALL samples using oligonucleotide arrays. Connective tissue growth factor (CTGF) was the highest overexpressed gene in B-cell ALL compared with the other groups, and displayed heterogeneous expression, suggesting it might have prognostic relevance. CTGF expression was examined by quantitative reverse transcriptase-polymerase chain reaction (ORT-PCR) on 79 adult ALL specimens. CTGF expression levels were significantly increased in ALL cases with B-lineage (P < .001), unfavorable cytogenetics (P < .001), and blasts expressing CD34 (P < .001). In a multivariate proportional hazards model, higher CTGF expression levels corresponded to worsening of overall survival (OS; hazard ratio 1.36, for each 10-fold increase in expression; P = .019). Further studies are ongoing to confirm the prognostic value of CTGF expression in ALL and to investigate its role in normal and abnormal lymphocyte biology.

Forkhead transcription factor FOXO3a is a negative regulator of angiogenic immediate early gene CYR61, leading to inhibition of vascular smooth muscle cell proliferation and neointimal hyperplasia

Cysteine-rich angiogenic protein 61 (CYR61, CCN1) is an immediate early gene expressed in vascular smooth muscle cells (VSMCs) on growth factor stimulation, and its expression has been suggested to be associated with postangioplasty restenosis. The forkhead transcription factors are reported to play various roles in cellular proliferation, apoptosis, and even adaptation to cellular stress. We hypothesized that the forkhead transcription factor FOXO3a may regulate CYR61 expression in VSMCs and investigated the CYR61-modulating effect of FOXO3a in the process of vascular response to vasoactive signals and vascular injury. To evaluate the effect of FOXO3a on CYR61 expression, rat VSMCs were infected with adenoviral vectors expressing constitutively active FOXO3a (Ad-TM-FOXO3a). Constitutively active FOXO3a gene transduction suppressed CYR61 expression. Luciferase assay with the deletion constructs of the forkhead factor binding motif in CYR61 promoter region, which resulted in a significant decrease in luciferase expression compared with the intact construct, and chromatin immunoprecipitation analysis confirmed transcriptional regulation of CYR61 by FOXO3a. Serum and angiotensin II rapidly induced CYR61 expression, which was significantly reduced by Ad-TM-FOXO3a. Reduction of VSMC proliferation and migration associated with FOXO3a activation was significantly reversed by cotransfection of adenoviral vector expressing CYR61, whereas apoptosis induction by FOXO3a was not influenced. In a rat balloon carotid arterial injury model, CYR61 was rapidly induced in VSMCs in the early stage of injury and remained elevated until 14 days, which was suppressed by Ad-TM-FOXO3a transfection. After 14 days, there was a significant reduction in neointima by FOXO3a transduction compared with the control group (0.06+/-0.02 versus 0.20+/-0.07 mm(2), P<0.01). Such reduction of neointimal hyperplasia by Ad-TM-FOXO3a was reversed by CYR61 replenishment. These data suggest that FOXO3a is a negative transcription factor of CYR61 and that suppression of CYR61 is among several mechanisms by which FOXO3a inhibits VSMC proliferation and neointimal hyperplasia.

Mechanical stretch modulates the promoter activity of the profibrotic factor CCN2 through increased actin polymerization and NF-kappaB activation

The connective tissue growth factor known as CCN2 is an inducible, profibrotic molecule that becomes aberrantly expressed in mechanical overload-bearing tissues. In this study, we found that CCN2 gene expression is rapidly induced in cyclically stretched bladder smooth muscle cells (SMCs) in vitro and in the detrusor muscle of a mechanically overloaded bladder in a rat model of experimental urethral obstruction. The activity of CCN2 promoter constructs, transiently transfected into cultured SMCs, was increased (up to 6-fold) by continuous cyclic stretching. Molecular analyses of the CCN2 promoter by serial construct deletions, cis-element mutagenesis, and electrophoretic mobility shift assays revealed that a highly conserved NF-kappaB binding site located within the CCN2 proximal promoter region is responsible for the activation of the promoter by stretch. Chromatin immunoprecipitation assays showed that NF-kappaB binds to the endogenous CCN2 promoter in both stretched cells and mechanically overloaded bladder tissues. Furthermore, stretch-dependent CCN2 promoter activity was significantly reduced upon inhibition of either phosphatidylinositol 3-kinase, p38 stress-activated kinase, or RhoA GTPase and was completely abolished upon inhibition of actin polymerization. Concordantly, actin polymerization was increased in either mechanically stretched cells or overloaded bladder tissues. Incubation of cultured SMCs with a cell-penetrating peptide containing the N-terminal sequence, Ac-EEED, of smooth muscle alpha-actin, altered both actin cytoskeleton organization and stretch-mediated nuclear relocation of NF-kappaB, and subsequently, it reduced CCN2 promoter activity. Thus, mechanical stretch-induced changes in actin dynamics mediate NF-kappaB activation and induce CCN2 gene expression, which probably initiates the fibrotic reactions observed in mechanical overload-associated pathologies.

Individual domains of connective tissue growth factor regulate fibroblast proliferation and myofibroblast differentiation

All members of the Ctgf, Cyr61, and Nov (CCN) family share a high degree of sequence homology and conservation of structural motifs and domains. Here, we present data about a structure function analysis of connective tissue growth factor (CTGF), a prototypic member of the CCN family, which has been shown to be a downstream mediator of transforming growth factor-beta activities on fibroblasts. Our findings demonstrate the two domains of CTGF function to mediate two distinct biological effects. The N-terminal domain of CTGF mediates myofibroblast differentiation and collagen synthesis. The C-terminal domain of CTGF mediates fibroblast proliferation. These data provide a molecular basis for the divergence of CTGF actions on connective tissue cell types and suggest a model for functional analysis of all of the CCN family gene products.

Lipoxin A4 inhibits proliferation of human lung fibroblasts induced by connective tissue growth factor

Connective tissue growth factor (CTGF) plays an important role in pathways leading to lung fibrosis via the mitogenic action of CTGF on fibroblasts. Studies have shown that lipoxin A4 (LXA4) inhibits proliferation of renal mesangial cells induced by leukotriene D4 or platelet-derived growth factor. This study investigates the regulatory role of LXA4 on proliferation of human lung fibroblasts (HLF) induced by CTGF and mechanisms of LXA4 action. CTGF induced HLF proliferation; enhanced the expression of cyclin D1; phosphorylated extracellular signal-regulated kinase (ERK)1/2, phosphoinositide 3-kinase (PI3-K), protein kinase B (PKB), and DNA-binding activity of signal transducers and activators of transcription-3 (STAT3); and inhibited expression of p27(kip1). LXA4 downregulated the CTGF-stimulated HLF proliferation and expression of cyclin D1; and phosphorylated ERK1/2, PI3-K, PKB, and DNA-binding activity of STAT3. CTGF-induced decrement in expression of p27(kip1) was ameliorated by LXA4. PI3-K or STAT blockade but not ERK1/2 blockade partially inhibited the CTGF-activated proliferation of HLF. Transfection of the human LXA4 receptor gene into HLF intensified the inhibition of LXA4 on CTGF-induced cell proliferation. These results demonstrate that CTGF induces proliferation of HLF via upregulation of PI3-K/PKB, STAT3, and cyclin D1, and downregulation of p27(kip1). LXA4 inhibits these effects of CTGF on HLF.

Angiotensin II increases connective tissue growth factor in the kidney

Connective tissue growth factor (CTGF) has been described as a novel fibrotic mediator. CTGF is overexpressed in several kidney diseases and is induced by different factors involved in renal injury. Angiotensin II (AngII) participates in the pathogenesis of kidney damage, contributing to fibrosis; however, whether AngII regulates CTGF in the kidney has not been explored. Systemic infusion of AngII into normal rats for 3 days increased renal CTGF mRNA and protein levels. At day 7, AngII-infused rats presented overexpression of CTGF in glomeruli, tubuli, and renal arteries, as well as tubular injury and elevated fibronectin deposition. Only treatment with an AT(1) receptor antagonist, but not an AT(2), diminished CTGF and fibronectin overexpression and ameliorated tubular damage. In rats with immune complex nephritis, renal overexpression of CTGF was diminished by the ACE inhibitor quinapril, correlated with a diminution in fibrosis. In cultured renal cells (mesangial and tubular epithelial cells) AngII, via AT(1), increased CTGF mRNA and protein production, and a CTGF antisense oligonucleotide decreased AngII-induced fibronectin synthesis. Our data show that AngII regulates CTGF in the kidney and cultured in mesangial and tubular cells. This novel finding suggests that CTGF could be a mediator of the profibrogenic effects of AngII in the kidney.

Biphasic role of TGF-beta1 in signal transduction and crosstalk

TGF-beta1 induces cell cycle activation in mouse embryonic fibroblasts by down regulation of p27(Kip1) but it can also induce delay of EGF-induced cell cycle activation in these cells under similar conditions. In an attempt to determine the basis for these responses, the study of early TGF-beta1-induced signal transduction pathways in the presence and absence of EGF was undertaken. It is proposed that a likely target for the inhibition by TGF-beta1 of the early EGF-induced p42/p44 MAPK is at the c-Raf locus. The finding that the catalytic subunits of PKA are associated with Raf-1 within minutes following application of TGF-beta1 but not EGF in fibroblasts arrested in early G1 is suggestive of a role of PKA-Raf-1 interaction in TGF-beta1 induced delay of EGF-induced cell cycle kinetics. A model for TGF-beta1 induced translocation to the plasma membrane-associated Raf-1 is proposed. Reports that Rho-like GTPase activity is critical for the activation of TGF-beta1 downstream pathways raises the question as to whether Rho proteins are involved in these observed TGF-beta1-induced responses. Post-receptor signaling mechanisms for TGF-beta1 and cross-talk with PKA-mediated pathways are examined in an effort to explain the modulation by TGF-beta1 of mitogen-induced cell proliferation in mesenchymal cells.

Expression of connective tissue growth factor in asthmatic airway smooth muscle cells

There is strong evidence to implicate transforming growth factor-beta in the remodeling that occurs in asthma, as levels are increased in bronchial lavage fluid and gene expression is increased in bronchial tissue. Transforming growth factor-beta is also known to increase the release of collagen from airway smooth muscle. Here we identify for the first time a possible mechanism for the effects of transforming growth factor-beta. Transforming growth factor-beta specifically induces mRNA and protein for connective tissue growth factor in airway smooth muscle, and moreover, we report that the connective tissue growth factor response is greater in airway smooth muscle cultured from patients with asthma compared with patients without asthma. This occurs at both the level of mRNA (37.53 +/- 11.62- and 13.59 +/- 3.12-fold increase at 24 hours compared with time 0, respectively, p < 0.02) and protein production (67.57 +/- 27.80- and 3.58 +/- 0.6-fold increase at 24 hours compared with time 0, respectively, p < 0.03). The differential connective tissue growth factor response to transforming growth factor-beta in asthmatic airway smooth muscle identifies a potential role for connective tissue growth factor in the remodeling that is characteristic of severe persistent asthma.

Connective tissue growth factor and regulation of the mesangial cell cycle: role in cellular hypertrophy

Connective tissue growth factor (CTGF) is now considered to be one of the important driver molecules for the pathogenesis of diabetic nephropathy (DN) and possibly many other fibrotic disorders. However, the molecular mechanisms by which CTGF functions remain to be established. In an attempt to define these mechanisms, this study was designed to investigate whether CTGF has any effect on the cell cycle of human mesangial cells (HMC), which are known to undergo hypertrophy in DN. This report provides the first evidence that CTGF is a hypertrophic factor for HMC. CTGF stimulates HMC to actively enter the G(1) phase from G(0), but they do not then progress further through the cell cycle. The molecular mechanisms underlying this G(1) phase arrest appear to be due to the induction of the cyclin-dependent kinase inhibitors (CDKI) p15(INK4), p21(Cip1), and p27(Kip1), which are known to bind and inactivate cyclinD/CDK4/6 and the cyclin E/CDK2 kinase complexes. This could account for the maintenance of pRb protein in a non- or very low-phosphorylated state, preventing cell cycle progression. Using CTGF antisense oligonucleotides, the results also indicate that the previously identified transforming growth factor-beta (TGF-beta)-induced hypertrophy in mesangial cells is CTGF-dependent. Mesangial cell hypertrophy is one of the earliest abnormalities of diabetic nephropathy; therefore, therapeutic strategies targeting CTGF may be beneficial in controlling DN.

Connective tissue growth factor: a new and important player in the pathogenesis of fibrosis

Connective tissue fibrosis is the final common pathogenic process for almost all forms of chronic tissue injury. Whether caused by vascular dysfunction, inflammation, metabolic injury, trauma, or environmental agents, once initiated the fibrogenic process results in the progressive replacement of the normal tissue architecture with fibrotic lesions that eventually lead to organ compromise and failure. Fibrosis can be considered as a dysregulation in the normal tissue repair mechanism, resulting in severe tissue scarring. Fibrosis appears to be a consequence of linked processes, including the proliferation of resident fibroblast cell types, the increased production and deposition of extracellular matrix components, and the transition of fibroblasts into cells exhibiting a myofibroblast phenotype. Although transforming growth factor-beta (TGF beta) has long been regarded as a pivotal growth factor in the formation and maintenance of connective tissues and as a major driving influence in many progressive fibrotic diseases, attention has focused recently on the role of connective tissue growth factor (CTGF) in fibrosis. CTGF is selectively and rapidly induced in mesenchymally derived cells by the action of TGF beta. CTGF expression is increased in many fibrosing diseases. In addition, increasing evidence from in vivo and in vitro models of tissue remodeling and fibrosis suggest that CTGF may represent a downstream effector molecule of the profibrotic activities of TGF beta in the maintenance and repair of connective tissues and within fibrotic disease settings.

Connective tissue growth factor as a major angiogenic agent that is induced by hypoxia in a human breast cancer cell line

Connective tissue growth factor (CTGF) is known to be a potent angiogenic factor. Here, we present the evidence that the hypoxic induction of angiogenesis by human breast cancer cells (MDA-231) can be ascribed at least in part to CTGF. Our results indicate that (i) CTGF is abundantly present in MDA-231 cells in vitro and in vivo, (ii) its secretion is up-regulated by hypoxia, and (iii) its gene expression is enhanced in MDA-231 cells cultured under hypoxic conditions. These data suggest CTGF may stimulate angiogenesis by paracrine mechanisms, thereby contributing to the invasion of breast cancer cells. This is the first evidence that human cancer cells differentially express CTGF protein and mRNA under the control of hypoxic conditions.

Expression of connective tissue growth factor in human renal fibroblasts: regulatory roles of RhoA and cAMP

The induction of connective tissue growth factor (CTGF) was investigated in a human renal fibroblast cell line that exhibited many characteristics of primary human renal fibroblasts. Induction of CTGF mRNA was observed after treatment of the cells with transforming growth factor-beta (TGF-beta) or, even more prominently, lysophosphatidic acid (LPA). LPA induced a rapid transient increase in CTGF mRNA expression, with maximal levels being observed after 1 to 2 h. This increase was accompanied by CTGF protein synthesis. Induction of CTGF was insensitive to pertussis toxin and was not dependent on the activation of p42/44 mitogen-activated protein kinases. Inhibition of the proteins of the Rho family with toxin B from Clostridium difficile abrogated basal and LPA-mediated induction of CTGF. Specific targeting of RhoA with C3 exotoxin or of the Rho kinases with the inhibitor Y-27632 similarly prevented induction of CTGF, implicating RhoA as a signaling module downstream of LPA. Inhibition of RhoA depolymerized the actin cytoskeleton, as did treatment with cytochalasin D. Preincubation of the human renal fibroblasts with cytochalasin D prevented induction of CTGF by LPA, indicating a strong contribution of an intact cytoskeleton. Interference with RhoA signaling similarly inhibited the induction of CTGF by TGF-beta. Elevation of intracellular levels of cAMP and thus activation of protein kinase A prevented induction of CTGF expression. The cytoskeletal effects of cAMP, however, were reversed by LPA. These data indicate complex interactions involving LPA-mediated activation of RhoA- and protein kinase A-dependent signaling pathways. The data thus demonstrate the regulatory functions of the small GTPase RhoA and of an intact cytoskeleton in the expression of CTGF after stimulation with LPA or TGF-beta. Analogous signal transduction pathways were previously demonstrated in rat mesangial cells, suggesting a more general role for RhoA in the regulation of CTGF expression.

CYR61 stimulates human skin fibroblast migration through Integrin alpha vbeta 5 and enhances mitogenesis through integrin alpha vbeta 3, independent of its carboxyl-terminal domain

CYR61, an angiogenic factor and a member of the CCN protein family, is an extracellular matrix-associated, heparin-binding protein that mediates cell adhesion, promotes cell migration, and enhances growth factor-stimulated cell proliferation. CYR61 induces angiogenesis and promotes tumor growth in vivo and is expressed in dermal fibroblasts during cutaneous wound healing. It has been demonstrated recently that adhesion of primary skin fibroblasts to CYR61 is mediated through integrin alpha(6)beta(1) and cell surface heparan sulfate proteoglycans, resulting in adhesive signaling and up-regulation of matrix metalloproteinases 1 and 3. CYR61 is composed of four discrete structural domains that bear sequence similarities to the insulin-like growth factor-binding proteins, von Willebrand factor type C repeat, thrombospondin type 1 repeat, and a carboxyl-terminal (CT) domain that resembles cysteine knots found in some growth factors. In this study, we show that a CYR61 mutant (CYR61DeltaCT) that has the CT domain deleted is unable to support adhesion of primary human skin fibroblasts but is still able to stimulate chemotaxis and enhance basic fibroblast growth factor-induced mitogenesis similar to wild type. In addition, fibroblast migration to CYR61 is mediated through integrin alpha(v)beta(5) but not integrins alpha(6)beta(1) or alpha(v)beta(3). Furthermore, we show that CYR61 binds directly to purified integrin alpha(v)beta(5) in vitro. By contrast, CYR61 enhancement of basic fibroblast growth factor-induced DNA synthesis is mediated through integrin alpha(v)beta(3), a known receptor for CYR61 that mediates CYR61-dependent cell adhesion and chemotaxis in vascular endothelial cells. Thus, CYR61 promotes primary human fibroblast adhesion, migration, and mitogenesis through integrins alpha(6)beta(1), alpha(v)beta(5), and alpha(v)beta(3), respectively. Together, these findings establish CYR61 as a novel ligand for integrin alpha(v)beta(5) and show that CYR61 interacts with distinct integrins to mediate disparate activities in a cell type-specific manner.

Renal fibrosis: an update

Tubulointerstitial fibrosis invariably accompanies the course of chronic renal failure towards end-stage renal disease. Tubular epithelial cells, the predominant cell type in the tubulointerstitium, are increasingly being recognized for playing a dominant role as mediators of renal fibrogenesis. Tubular epithelial cells become activated either by the glomerular ultrafiltrate from their apical side or by mononuclear cells from their basolateral side. They initiate the scarring process by secreting chemokines, which in return attract mononuclear cells as well as growth factors that stimulate interstitial fibroblasts. In later phases of renal fibrogenesis, cellular changes of tubular epithelial cells contribute to the chronic impairment of renal function. Whereas tubular epithelial cells react by proliferation or hypertrophy to initial stimuli, they may undergo apoptosis or transdifferentiate into fibroblasts, and thus contribute to tubular atrophy in later stages of progressive renal disease. Resident interstitial fibroblasts are also important in renal fibrogenesis, and recent research has demonstrated that these cells are much more heterogeneous than expected. Cytokines such as fibroblast growth factor type 2 and epithelial growth factor have been shown to be pro-fibrogenic, whereas hepatocyte growth factor and bone morphogenic protein type 7 may inhibit fibrogenesis. Despite recent progress, further research is mandatory for a better understanding and the development of novel therapeutic approaches.

CTGF expression is induced by TGF- beta in cardiac fibroblasts and cardiac myocytes: a potential role in heart fibrosis

Connective tissue growth factor (CTGF) is a cysteine-rich protein induced by transforming growth factor beta (TGF- beta) in connective tissue cells. CTGF can trigger many of the cellular processes underlying fibrosis, such as cell proliferation, adhesion, migration and the synthesis of extracellular matrix; however, its role in acute and chronic cardiac injury is not fully understood. Here, we show that TGF- beta is a specific inducer of CTGF expression in both cardiac fibroblasts and cardiac myocytes. The activity of a CTGF promoter-based reporter construct correlated with endogenous CTGF expression, suggesting that TGF- beta induces CTGF expression most likely by activating its promoter. Upregulation of CTGF coincided with an increase in fibronectin, collagen type I and plasminogen activator inhibitor-1 production. Forskolin, a stimulator of cyclic AMP, blocked TGF- beta induced CTGF expression and reduced the basal level of CTGF, whereas an inhibitor that blocks the MAP kinase signaling pathway (PD 98059) significantly enhanced TGF- beta induced CTGF expression. Furthermore, we found that both TGF- beta and CTGF mRNAs were significantly elevated in the left ventricles and septa of rat hearts 2-16 weeks following myocardial infarction. This correlated well with concomitant increases in fibronectin, and type I and type III collagen mRNA levels in these animal hearts. Significant upregulation of CTGF was also detected in human heart samples derived from patients diagnosed with cardiac ischemia. Based on these findings, we propose that CTGF is an important mediator of TGF- beta signaling in the heart and abnormal expression of this gene could be used as a diagnostic marker for cardiac fibrosis.

Connective tissue growth factor: potential role in glomerulosclerosis and tubulointerstitial fibrosis

Transforming growth factor beta (TGF-beta) is a pivotal driver of glomerulosclerosis and tubulointerstitial fibrosis in renal diseases. Because TGF-beta also plays important anti-inflammatory and antiproliferative roles in mammalian systems, there has been a recent drive to elucidate downstream mediators of TGF-beta's pro-fibrotic effects with the ultimate goal of developing new anti-fibrotic strategies for treatment of chronic diseases. Connective tissue growth factor (CTGF) belongs to the CCN family of immediate early response genes. Several lines of evidence suggest that CTGF is an important pro-fibrotic molecule in renal disease and that CTGF contributes to TGF-beta bioactivity in this setting. CTGF expression is increased in the glomeruli and tubulointerstium in a variety of renal disease in association with scarring and sclerosis of renal parenchyma. In model systems in vitro, mesangial cell CTGF expression is induced by high extracellular glucose, cyclic mechanical strain and TGF-beta. Recombinant human CTGF augments the production of fibronectin and type IV collagen by mesangial cells and the effects of high glucose on mesangial cell CTGF expression and matrix production are attenuated, in part, by anti-TGF-beta antibody. In aggregate, these observations identify CTGF as an attractive therapeutic target in fibrotic renal diseases.