[Show abstract][Hide abstract] ABSTRACT: Background:
One of the main contributors to maladaptive cardiac remodeling is fibrosis. Connective tissue growth factor (CTGF), a matricellular protein that is secreted into the cardiac extracellular matrix by both cardiomyocytes and fibroblasts, is often associated with development of fibrosis. However, recent studies have questioned the role of CTGF as a pro-fibrotic factor. Therefore, we aimed to investigate the effect of CTGF on cardiac fibrosis, and on functional, structural, and electrophysiological parameters in a mouse model of CTGF knockout (KO) and chronic pressure overload.
Methods and results:
A new mouse model of global conditional CTGF KO induced by tamoxifen-driven deletion of CTGF, was subjected to 16weeks of chronic pressure overload via transverse aortic constriction (TAC, control was sham surgery). CTGF KO TAC mice presented with hypertrophic hearts, and echocardiography revealed a decrease in contractility on a similar level as control TAC mice. Ex vivo epicardial mapping showed a low incidence of pacing-induced ventricular arrhythmias (2/12 in control TAC vs. 0/10 in CTGF KO TAC, n.s.) and a tendency towards recovery of the longitudinal conduction velocity of CTGF KO TAC hearts. Picrosirius Red staining on these hearts unveiled increased fibrosis at a similar level as control TAC hearts. Furthermore, genes related to fibrogenesis were also similarly upregulated in both TAC groups. Histological analysis revealed an increase in fibronectin and vimentin protein expression, a significant reduction in connexin43 (Cx43) protein expression, and no difference in NaV1.5 expression of CTGF KO ventricles as compared with sham treated animals.
Conditional CTGF inhibition failed to prevent TAC-induced cardiac fibrosis and hypertrophy. Additionally, no large differences were found in other parameters between CTGF KO and control TAC mice. With no profound effect of CTGF on fibrosis formation, other factors or pathways are likely responsible for fibrosis development.
Journal of Molecular and Cellular Cardiology 09/2015; DOI:10.1016/j.yjmcc.2015.09.015 · 4.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metastatic melanoma is characterized by an extremely poor prognosis with few durable remissions. The secreted matricellular protein connective tissue growth factor (CTGF, CCN2) is overexpressed in cancers including melanoma and may represent a viable therapeutic target. However, the mechanism underlying the contribution of CCN2 to melanoma progression is unclear. In this report, we use the highly metastatic murine melanoma cell line B16(F10) and syngeneic mice in which CCN2 expression is knocked out in fibroblasts, to demonstrate that loss of CCN2, either in melanoma cells or in the niche, impedes the ability of melanoma cells to invade. Specifically, loss of CCN2 in melanoma cells diminished their ability to invade through collagen in vitro and loss of fibroblast-derived CCN2 decreased spontaneous metastases of melanoma cells from the skin to the lungs, in vivo. Proliferation and tumor growth were not affected by loss of CCN2. CCN2-deficient B16(F10) cells showed reduced expression of the matricellular protein periostin; addition of recombinant periostin rescued the in vitro invasion defect of these cells. Immunohistochemical analysis of CCN2-deficient mice confirmed loss of periostin expression in the absence of CCN2. CCN2 and periostin mRNA levels are positively correlated with each other and with the stromal composition of human melanoma lesions but not BRAF mutations. Thus CCN2 promotes invasion and metastasis via periostin and should be further evaluated as a possible therapeutic target for melanoma.Journal of Investigative Dermatology accepted article preview online, 13 July 2015. doi:10.1038/jid.2015.279.
Journal of Investigative Dermatology 07/2015; DOI:10.1038/jid.2015.279 · 7.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Systemic sclerosis (SSc, scleroderma) is an often-fatal disease characterized by connective tissue fibrosis of skin and internal organs. In scleroderma, there is an excessive production and accumulation of extracellular matrix (ECM) components resulting from an increase in collagen synthesis and matrix stability. Understanding how this how excessive ECM is produced and remodeled may represent a novel therapeutic approach. In this review, the transcription factors and collagen-modifying enzymes underlying collagen overexpression and enhancing stability in SSc are discussed. Moreover, the role of matrix stiffness in promoting fibrosis via a feed-forward mechanism is discussed. Indeed, the emerging evidence is that enhanced ECM remodeling resulting in increased ECM stiffness may be sufficient in itself to sustain persistence fibrosis in SSc.
Seminars in Immunopathology 07/2015; 37(5). DOI:10.1007/s00281-015-0508-2 · 7.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transforming growth factor (TGF)β acts on fibroblasts to promote the production and remodeling of extracellular matrix (ECM). In adult humans, excessive action of TGFβ is associated with fibrotic disease and fibroproliferative conditions, including gingival hyperplasia. Understanding how the TGFβ1 signals in fibroblasts is therefore likely to result in valuable insights into the fundamental mechanisms underlying fibroproliferative disorders. Previously, we used the TAK1 inhibitor (5Z)-7-Oxozeaenol to show that, in dermal fibroblasts, the non-canonical TAK1 pathway mediates the ability of TGFβ1 to induce genes promoting tissue remodeling and repair. However, the extent to which TAK1 mediates fibroproliferative responses in fibroblasts in response to TGFβ1 remains unclear. Herein, we show that, in gingival fibroblasts, (5Z)-7-Oxozeaenol blocks the ability of TGFβ1 to induce expression of the pro-fibrotic mediator CCN2 (connective tissue growth factor, CTGF) and type I collagen protein. Moreover, genome-wide expression profiling revealed that, in gingival fibroblasts, (5Z)-7-Oxozeaenol reduces the ability of TGFβ1 to induce mRNA expression of essentially all TGFβ1-responsive genes (139/147), including those involved with a hyperproliferative response. Results from microarray analysis were confirmed using real time polymerase chain reaction analysis and a functional cell proliferation assay. Our results are consistent with the hypothesis that TAK1 inhibitors might be useful in treating fibroproliferative disorders, including that in the oral cavity.
PLoS ONE 04/2015; 10(4):e0123689. DOI:10.1371/journal.pone.0123689 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic wounds, especially on the feet, are a clinical feature resulting from diabetes and often result in limb amputation. Identification of strategies that promote closure of chronic wounds are essential. In a study authored by Henshaw et al. (J Diabetes Res. 2015;2015:236238), CCN2/CTGF was able to accelerated closure of wounds in diabetic rats. Moreover, in humans, the ability of wounds in diabetic patients to heal correlated with CCN2 expression. Thus CCN2 might, in the future, be used to promote healing of chronic wounds.Diabetic foot ulcers are a significant cause of morbidity and are a substantial financial burden. Approximately 25 % of diabetics have foot ulcers, and these account for up to 70 % of non traumatic lower limb amputations (Most and Sinnock 1983). About 6.5 million people in the USA suffer from chronic wounds, costing ~ $25 billion dollars (Sen et al. 2009). Developing novel methods of promoting closure of chronic diabetic wounds is therefore of paramount importanc ...
Journal of Cell Communication and Signaling 04/2015; 9(3). DOI:10.1007/s12079-015-0292-8
[Show abstract][Hide abstract] ABSTRACT: Fibrotic diseases are a significant cause of mortality. It is being increasingly appreciated that the cellular microenvironment plays a key role in promoting pathological fibrosis. A previous Bits and Bytes described an elegant series of experiments published by Bruce Riser and colleagues (Am J Pathol. 2009: 174:1725-34) that showed that CCN3 (nov) antagonizes the fibrogenic effects of CCN2.and hence could represent a novel anti-fibrotic therapy. They have continued their excellent work and have recently used the ob/ob mouse as a model of obesity and diabetic nephropathy to show that CCN3 could block the induction of profibrotic gene expression, fibrosis and loss of kidney function (Am J Pathol. 2014;184:2908-21). Also, reversal of fibrosis was observed. Thus this paper provides strong evidence that CCN3 may be used as a novel therapy to treat diabetes caused by obesity.
Journal of Cell Communication and Signaling 02/2015; 9(1). DOI:10.1007/s12079-015-0281-y
[Show abstract][Hide abstract] ABSTRACT: Elevated adhesive signaling promotes fibrosis. Protein phosphatase and tensin homologue (PTEN) dephosphorylates focal adhesion kinase and suppresses the activation of Akt and hence suppresses adhesive signaling. Loss of PTEN expression is associated with lung fibrosis, but whether PTEN expression by type I collagen-expressing cells controls lung fibrosis is unclear. Here, we use mice expressing tamoxifen-dependent cre recombinase expressed under the control of a COL1A2 promoter/enhancer and mice harboring floxed-PTEN and/or floxed-CCN2 alleles to assess whether loss of PTEN expression by type I collagen producing cells results in lung fibrosis in a CCN2-dependent fashion. In vivo, loss of PTEN expression resulted in the overexpression of both collagen type I and the pro-adhesive matricellular protein connective tissue growth factor (CTGF/CCN2). However, α−smooth muscle actin expression was unaffected. Loss of CCN2 expression by lung fibroblasts rescues this phenotype; i.e.., mice deficient in both PTEN and CCN2 in collagen type I-expressing cells do not develop significant collagen deposition in the lung. PTEN expression by collagen type I-expressing cells controls collagen deposition; therapeutic strategies blocking CCN2 may be of benefit in blocking excessive collagen deposition in fibrosis.
[Show abstract][Hide abstract] ABSTRACT: Connective tissue growth factor (CTGF/CCN2), a member of the CCN family of matricellular proteins is upregulated in both fibrosis as well as tissue repair. Recently, we showed that, in mice, CCN2 expression by fibroblasts was required for dermal fibrogenesis, but not for cutaneous tissue repair. Lineage tracing analysis linked the ability of CCN2 to promote fibrosis to the requirement for CCN2 to recruit cells expressing the progenitor cell marker Sox2 to fibrotic connective tissue and for differentiating these cells into myofibroblasts. Herein, we show that although loss of CCN2 expression by Sox2-expressing cells does not impair cutaneous tissue repair, CCN2 was required for recruitment of cells derived from Sox2-expressing cells to the wound area. Collectively, these results are consistent with the notion that neither CCN2 nor Sox2-expressing progenitor cells are essential for cutaneous tissue repair and that CCN2 represents a specific anti-fibrotic target.
Journal of Cell Communication and Signaling 10/2014; DOI:10.1007/s12079-014-0245-7
[Show abstract][Hide abstract] ABSTRACT: Unlabelled:
Connective tissue growth factor (CTGF) is a matricellular protein that mediates cell-matrix interaction through various subtypes of integrin receptors. This study investigated the role of CTGF and integrin αvβ6 in hepatic progenitor/oval cell activation, which often occurs in the form of ductular reactions (DRs) when hepatocyte proliferation is inhibited during severe liver injury. CTGF and integrin αvβ6 proteins were highly expressed in DRs of human cirrhotic livers and cholangiocarcinoma. Confocal microscopy analysis of livers from Ctgf promoter-driven green fluorescent protein reporter mice suggested that oval cells and cholangiocytes were the main sources of CTGF and integrin αvβ6 during liver injury induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Deletion of exon 4 of the Ctgf gene using tamoxifen-inducible Cre-loxP system down-regulated integrin αvβ6 in DDC-damaged livers of knockout mice. Ctgf deficiency or inhibition of integrin αvβ6, by administrating the neutralizing antibody, 6.3G9 (10 mg/kg body weight), caused low levels of epithelial cell adhesion molecule and cytokeratin 19 gene messenger RNAs. Also, there were smaller oval cell areas, fewer proliferating ductular epithelial cells, and lower cholestasis serum markers within 2 weeks after DDC treatment. Associated fibrosis was attenuated, as indicated by reduced expression of fibrosis-related genes, smaller areas of alpha-smooth muscle actin staining, and low collagen production based on hydroxyproline content and Sirius Red staining. Finally, integrin αvβ6 could bind to CTGF mediating oval cell adhesion to CTGF and fibronection substrata and promoting transforming growth factor (TGF)-β1 activation in vitro.
CTGF and integrin αvβ6 regulate oval cell activation and fibrosis, probably through interacting with their common matrix and signal partners, fibronectin and TGF-β1. CTGF and integrin αvβ6 are potential therapeutic targets to control DRs and fibrosis in related liver disease.
[Show abstract][Hide abstract] ABSTRACT: The so-called "matricellular" proteins have recently emerged as important regulators of cell-extracellular matrix (ECM) interactions. These proteins modulate a variety of cell functions through a range of interactions with cell-surface receptors, hormones, proteases and structural components of the ECM. As such, matricellular proteins are crucial regulators of cell phenotype, and consequently tissue function. The distinct cell types and microenvironments that together form the IVD provide an excellent paradigm to study how matricellular proteins mediate communication within and between adjacent tissue types. In recent years, the role of several matricellular proteins in the intervertebral disc has been explored in vivo using mutant mouse models in which the expression of target matricellular proteins was deleted from either one or all compartments of the intervertebral disc. The current review outlines what is presently known about the roles of the matricellular proteins belonging to the CCN family, SPARC (Secreted Protein, Acidic, and Rich in Cysteine), and thrombospondin (TSP) 2 in regulating intervertebral disc cell-ECM interactions, ECM synthesis and disc tissue homeostasis using genetically modified mouse models. Furthermore, we provide a brief overview of recent preliminary studies of other matricellular proteins including, periostin (POSTN) and tenascin (TN). Each specific tissue type of the IVD contains a different matricellular protein signature, which varies based on the specific stage of development, maturity or disease. A growing body of direct genetic evidence links IVD development, maintenance and repair to the coordinate interaction of matricellular proteins within their respective niches and suggest that several of these signalling modulators hold promise in the development of diagnostics and/or therapeutics targeting intervertebral disc aging and/or degeneration.
Matrix biology: journal of the International Society for Matrix Biology 05/2014; 37. DOI:10.1016/j.matbio.2014.05.005 · 5.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this report, chairs of the 7th International Workshop on the CCN family of Genes, review the progress made in understanding the biological functions of CCN proteins (CCN1, CCN2, CCN3, CCN4, CCN5 and CCN6) with a particular focus on their implications in various pathological conditions, including cancer, fibrosis, diabetes, and cardiovascular diseases.
Journal of Cell Communication and Signaling 04/2014; 8(1). DOI:10.1007/s12079-014-0227-9
[Show abstract][Hide abstract] ABSTRACT: Purpose:
This study aimed to elucidate the role of connective tissue growth factor (CTGF) in healthy eyes and wounded corneas of mice and rabbits. Conditional knockout mice were used to determine the role of CTGF in corneal healing.
CTGF expression was determined using transgenic mice carrying CTGF promoter driven-eGFP, quantitative RT-PCR, and immunofluorescent staining. Mice that carried two floxed CTGF alleles and a Cre/ERT2 transgene under the control of human ubiquitin C (ubc) promoter were used to conditionally delete CTGF gene in a tamoxifen-inducible manner. Phototherapeutic keratectomy (PTK) was used to generate an acute corneal wound and corneal re-epithelialization was assessed by fluorescein staining.
Connective tissue growth factor expression was found in multiple ocular tissues with relatively high levels in the corneal endothelium, lens subcapsular epithelium, and in the vasculature of the iris and retina. Wounded corneas responded with an immediate upregulation of CTGF in the epithelium at the wound margin and a sustained CTGF induction during re-epithelialization. At the onset of haze formation, CTGF protein becomes more focused in the basal epithelium. Deletion of the CTGF gene caused a 40% reduction (P < 0.01) in the cornea re-epithelialization rate in knockout mice compared with wild-type mice.
Connective tissue growth factor is expressed in the naïve cornea, lens, iris, and retina, and is expressed immediately after epithelial injury. Loss of CTGF impairs efficient re-epithelialization of corneal wounds.
[Show abstract][Hide abstract] ABSTRACT: The potent profibrotic cytokine TGFβ induces connective tissue growth factor (CCN2/CTGF) is induced in fibroblasts in a fashion sensitive to SB-431542, a specific pharmacological inhibitor of TGFβ type I receptor (ALK5). In several cell types, TGFβ induces CCN1 but suppresses CCN3, which opposes CCN1/CCN2 activities. However, whether SB-431542 alters TGFβ-induced CCN1 or CCN3 in human foreskin fibroblasts in unclear. Here we show that TGFβ induces CCN1 but suppresses CCN3 expression in human foreskin fibroblasts in a SB-431542-sensitive fashion. These results emphasize that CCN1/CCN2 and CCN3 are reciprocally regulated and support the notion that blocking ALK5 or addition of CCN3 may be useful anti-fibrotic approaches.
Journal of Cell Communication and Signaling 02/2014; 8(1). DOI:10.1007/s12079-014-0229-7
[Show abstract][Hide abstract] ABSTRACT: Scarring, which occurs in essentially all adult tissue, is characterized by the excessive production and remodeling of extracellular matrix by α-smooth muscle actin (SMA)-expressing myofibroblasts located within connective tissue. Excessive scarring can cause organ failure and death. Oral gingivae do not scar. Compared to dermal fibroblasts, gingival fibroblasts do not respond to transforming growth factor (TGFβ) by inducing α-SMA expression, due to the reduced expression and activity of focal adhesion kinase (FAK) by this cell type. Herein, we show that, compared with dermal fibroblasts, gingival fibroblasts show reduced expression of miR-218. Introduction of pre-miR-218 into gingival fibroblasts elevates FAK expression and, via a FAK/src-dependent mechanism, results in the ability of TGFβ to induce α-SMA. The deubiquitinase cezanne is a direct target of miR-218 and has increased expression in gingival fibroblasts compared with dermal fibroblasts. Knockdown of cezanne in gingival fibroblasts increases FAK expression and causes TGFβ to induce α-SMA. These results suggest that miR-218 regulates the ability of TGFβ to induce myofibroblast differentiation in fibroblasts via cezanne/FAK.
Molecular biology of the cell 02/2014; 25(7). DOI:10.1091/mbc.E13-08-0451 · 4.47 Impact Factor