Connective tissue growth factor regulates retinal neovascularization through p53 protein-dependent transactivation of the matrix metalloproteinase (MMP)-2 gene

CCN-Hippo YAP signaling in vision and its role in neuronal, glial and vascular cell function and behavior

The retina is a highly specialized tissue composed of a network of neurons, glia, and vascular and epithelial cells; all working together to coordinate and transduce visual signals to the brain. The retinal extracellular matrix (ECM) shapes the structural environment in the retina but also supplies resident cells with proper chemical and mechanical signals to regulate cell function and behavior and maintain tissue homeostasis. As such, the ECM affects virtually all aspects of retina development, function and pathology. ECM-derived regulatory cues influence intracellular signaling and cell function. Reversibly, changes in intracellular signaling programs result in alteration of the ECM and downstream ECM-mediated signaling network. Our functional studies in vitro, genetic studies in mice, and multi omics analyses have provided evidence that a subset of ECM proteins referred to as cellular communication network (CCN) affects several aspects of retinal neuronal and vascular development and function. Retinal progenitor, glia and vascular cells are major sources of CCN proteins particularly CCN1 and CCN2. We found that expression of the CCN1 and CCN2 genes is dependent on the activity of YAP, the core component of the hippo-YAP signaling pathway. Central to the Hippo pathway is a conserved cascade of inhibitory kinases that regulate the activity of YAP, the final transducer of this pathway. Reversibly, YAP expression and/or activity is dependent on CCN1 and CCN2 downstream signaling, which creates a positive or negative feedforward loop driving developmental processes (e.g., neurogenesis, gliogenesis, angiogenesis, barriergenesis) and, when dysregulated, disease progression in a range of retinal neurovascular disorders. Here we describe mechanistic hints involving the CCN-Hippo-YAP regulatory axis in retina development and function. This regulatory pathway represents an opportunity for targeted therapies in neurovascular and neurodegenerative diseases. The CCN-YAP regulatory loop in development and pathology.

Encephalopsin (OPN3) is required for normal refractive development and the GO/GROW response to induced myopia

Purpose

Myopia, or nearsightedness, is the most common form of refractive error and is increasing in prevalence. While significant efforts have been made to identify genetic variants that predispose individuals to myopia, these variants are believed to account for only a small portion of the myopia prevalence, leading to a feedback theory of emmetropization, which depends on the active perception of environmental visual cues. Consequently, there has been renewed interest in studying myopia in the context of light perception, beginning with the opsin family of G-protein coupled receptors (GPCRs). Refractive phenotypes have been characterized in every opsin signaling pathway studied, leaving only Opsin 3 (OPN3), the most widely expressed and blue-light sensing noncanonical opsin, to be investigated for function in the eye and refraction.

Methods

Opn3 expression was assessed in various ocular tissues using an Opn3eGFP reporter. Weekly refractive development in Opn3 retinal and germline mutants from 3 to 9 weeks of age was measured using an infrared photorefractor and spectral domain optical coherence tomography (SD-OCT). Susceptibility to lens-induced myopia was then assessed using skull-mounted goggles with a -30 diopter experimental and a 0 diopter control lens. Mouse eye biometry was similarly tracked from 3 to 6 weeks. A myopia gene expression signature was assessed 24 h after lens induction for germline mutants to further assess myopia-induced changes.

Results

Opn3 was found to be expressed in a subset of retinal ganglion cells and a limited number of choroidal cells. Based on an assessment of Opn3 mutants, the OPN3 germline, but not retina conditional Opn3 knockout, exhibits a refractive myopia phenotype, which manifests in decreased lens thickness, shallower aqueous compartment depth, and shorter axial length, atypical of traditional axial myopias. Despite the short axial length, Opn3 null eyes demonstrate normal axial elongation in response to myopia induction and mild changes in choroidal thinning and myopic shift, suggesting that susceptibility to lens-induced myopia is largely unchanged. Additionally, the Opn3 null retinal gene expression signature in response to induced myopia after 24 h is distinct, with opposing Ctgf, Cx43, and Egr1 polarity compared to controls.

Conclusions

The data suggest that an OPN3 expression domain outside the retina can control lens shape and thus the refractive performance of the eye. Prior to this study, the role of Opn3 in the eye had not been investigated. This work adds OPN3 to the list of opsin family GPCRs that are implicated in emmetropization and myopia. Further, the work to exclude retinal OPN3 as the contributing domain in this refractive phenotype is unique and suggests a distinct mechanism when compared to other opsins.

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.

A Monoclonal Anti-HMGB1 Antibody Attenuates Neurodegeneration in an Experimental Animal Model of Glaucoma

Neuroinflammation is a crucial process for the loss of retinal ganglion cells (RGC), a major characteristic of glaucoma. High expression of high-mobility group box protein 1 (HMGB1) plays a detrimental role in inflammatory processes and is elevated in the retinas of glaucoma patients. Therefore, this study aimed to investigate the effects of the intravitreal injection of an anti-HMGB1 monoclonal antibody (anti-HMGB1 Ab) in an experimental animal model of glaucoma. Two groups of Spraque Dawley rats received episcleral vein occlusion to chronically elevate intraocular pressure (IOP): (1) the IgG group, intravitreal injection of an unspecific IgG as a control, n = 5, and (2) the HMGB1 group, intravitreal injection of an anti-HMGB1 Ab, n = 6. IOP, retinal nerve fiber layer thickness (RNFLT), and the retinal flash response were monitored longitudinally. Post-mortem examinations included immunohistochemistry, microarray, and mass spectrometric analysis. RNFLT was significantly increased in the HMGB1 group compared with the IgG group (p < 0.001). RGC density showed improved neuronal cell survival in the retina in HMGB1 compared with the IgG group (p < 0.01). Mass spectrometric proteomic analysis of retinal tissue showed an increased abundance of RNA metabolism-associated heterogeneous nuclear ribonucleoproteins (hnRNPs), such as hnRNP U, D, and H2, in animals injected with the anti-HMGB1 Ab, indicating that the application of the antibody may cause increased gene expression. Microarray analysis showed a significantly decreased expression of C-X-C motif chemokine ligand 8 (CXCL8, p < 0.05) and connective tissue growth factor (CTGF, p < 0.01) in the HMGB1 group. Thus, these data suggest that intravitreal injection of anti-HMGB1 Ab reduced HMGB1-dependent inflammatory signaling and mediated RGC neuroprotection.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

CCN2-induced lymphangiogenesis is mediated by the integrin αvβ5-ERK pathway and regulated by DUSP6

Lymphangiogenesis is essential for the development of the lymphatic system and is important for physiological processes such as homeostasis, metabolism and immunity. Cellular communication network factor 2 (CCN2, also known as CTGF), is a modular and matricellular protein and a well-known angiogenic factor in physiological and pathological angiogenesis. However, its roles in lymphangiogenesis and intracellular signaling in lymphatic endothelial cells (LECs) remain unclear. Here, we investigated the effects of CCN2 on lymphangiogenesis. In in vivo Matrigel plug assays, exogenous CCN2 increased the number of Podoplanin-positive vessels. Subsequently, we found that CCN2 induced phosphorylation of ERK in primary cultured LECs, which was almost completely inhibited by the blockade of integrin αvβ5 and partially decreased by the blockade of integrin αvβ3. CCN2 promoted direct binding of ERK to dual-specific phosphatase 6 (DUSP6), which regulated the activation of excess ERK by dephosphorylating ERK. In vitro, CCN2 promoted tube formation in LECs, while suppression of Dusp6 further increased tube formation. In vivo, immunohistochemistry also detected ERK phosphorylation and DUSP6 expression in Podoplanin-positive cells on CCN2-supplemented Matrigel. These results indicated that CCN2 promotes lymphangiogenesis by enhancing integrin αvβ5-mediated phosphorylation of ERK and demonstrated that DUSP6 is a negative regulator of excessive lymphangiogenesis by CCN2.

Diabetes Promotes Retinal Vascular Endothelial Cell Injury by Inducing CCN1 Expression

Purpose: Diabetic retinopathy (DR) is one of the most common diabetic microvascular complications. However, the pathogenesis of DR has not yet been fully elucidated. This study aimed to discover novel and key molecules involved in the pathogenesis of DR, which could potentially be targets for therapeutic DR intervention.

Methods: To identify potential genes involved in the pathogenesis of DR, we analyzed the public database of neovascular membranes (NVMs) from patients with proliferative diabetic retinopathy (PDR) and healthy controls (HCs) (GSE102485, https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE102485). Further, we compared these findings by performing RNA-sequencing analysis of peripheral blood mononuclear cells (PBMC) from patients with DR, control patients with non-complicated diabetes mellitus (DMC), and HCs. To determine the critical role of candidate genes in DR, knockdown or knockout was performed in human retinal vascular endothelial cells (HRVECs). The oxidative stress pathway, as well as tight junction integrity, was analyzed.

Results: Transcriptional profiles showed distinct patterns between the NVMs of patients with DR and those of the HCs. Those genes enriched in either extracellular matrix (ECM)-receptor interaction or focal adhesion pathways were considerably upregulated. Both pathways were important for maintaining the integrity of retinal vascular structure and function. Importantly, the gene encoding the matricellular protein CCN1, a key gene in cell physiology, was differentially expressed in both pathways. Knockdown of CCN1 by small interfering RNA (siRNA) or knockout of CCN1 by the CRISPR-Cas9 technique in HRVECs significantly increased the levels of VE-cadherin, reduced the level of NADPH oxidase 4 (NOX4), and inhibited the generation of reactive oxygen species (ROS).

Conclusion: The present study identifies CCN1 as an important regulator in the pathogenesis of DR. Increased expression of CCN1 stimulates oxidative stress and disrupts tight junction integrity in endothelial cells by inducing NOX4. Thus, targeting the CCN1/NOX4 axis provides a therapeutic strategy for treating DR by alleviating endothelial cell injury.

Transcriptomic analysis of the mouse retina after acute and chronic normobaric and hypobaric hypoxia

Oxygen delivery to the retinal pigment epithelium and the outer retina is essential for metabolism, function, and survival of photoreceptors. Chronically reduced oxygen supply leads to retinal pathologies in patients and causes age-dependent retinal degeneration in mice. Hypoxia can result from decreased levels of inspired oxygen (normobaric hypoxia) or reduced barometric pressure (hypobaric hypoxia). Since the response of retinal cells to chronic normobaric or hypobaric hypoxia is mostly unknown, we examined the effect of six hypoxic conditions on the retinal transcriptome and photoreceptor morphology. Mice were exposed to short- and long-term normobaric hypoxia at 400 m or hypobaric hypoxia at 3450 m above sea level. Longitudinal studies over 11 weeks in normobaric hypoxia revealed four classes of genes that adapted differentially to the hypoxic condition. Seventeen genes were specifically regulated in hypobaric hypoxia and may affect the structural integrity of the retina, resulting in the shortening of photoreceptor segment length detected in various hypoxic groups. This study shows that retinal cells have the capacity to adapt to long-term hypoxia and that consequences of hypobaric hypoxia differ from those of normobaric hypoxia. Our datasets can be used as references to validate and compare retinal disease models associated with hypoxia.

A CTGF-YAP Regulatory Pathway Is Essential for Angiogenesis and Barriergenesis in the Retina

Connective tissue growth factor (CTGF) or cellular communication network 2 (CCN2) is a matricellular protein essential for normal embryonic development and tissue repair. CTGF exhibits cell- and context-dependent activities, but CTGF function in vascular development and barrier function is unknown. We show that endothelial cells (ECs) are one of the major cellular sources of CTGF in the developing and adult retinal vasculature. Mice lacking CTGF expression either globally or specifically in ECs exhibit impaired vascular cell growth and morphogenesis and blood barrier breakdown. The global molecular signature of CTGF includes cytoskeletal and extracellular matrix protein, growth factor, and transcriptional co-regulator genes such as yes-associated protein (YAP). YAP, itself a transcriptional activator of CTGF, mediates several CTGF-controlled angiogenic and barriergenic transcriptional programs. Re-expression of YAP rescues, at least partially, angiogenesis and barriergenesis in CTGF mutant mouse retinas. Thus, the CTGF-YAP regulatory loop is integral to retinal vascular development and barrier function.

•

CTGF has a strong and persistent expression in the retinal vasculature

•

Mice lacking CTGF exhibit defects in angiogenesis and blood barrier integrity

•

CTGF-targeted genes include matrix, growth, and transcription co-factors like YAP

•

YAP re-expression partly rescues angiogenic and barriergenic defects of CTGF loss

Eyeing the Extracellular Matrix in Vascular Development and Microvascular Diseases and Bridging the Divide between Vascular Mechanics and Function

The extracellular matrix (ECM) is critical in all aspects of vascular development and health: supporting cell anchorage, providing structure, organization and mechanical stability, and serving as a sink for growth factors and sustained survival signals. Abnormal changes in ECM protein expression, organization, and/or properties, and the ensuing changes in vascular compliance affect vasodilator responses, microvascular pressure transmission, and collateral perfusion. The changes in microvascular compliance are independent factors initiating, driving, and/or exacerbating a plethora of microvascular diseases of the eye including diabetic retinopathy (DR) and vitreoretinopathy, retinopathy of prematurity (ROP), wet age-related macular degeneration (AMD), and neovascular glaucoma. Congruently, one of the major challenges with most vascular regenerative therapies utilizing localized growth factor, endothelial progenitor, or genetically engineered cell delivery, is the regeneration of blood vessels with physiological compliance properties. Interestingly, vascular cells sense physical forces, including the stiffness of their ECM, through mechanosensitive integrins, their associated proteins and the actomyosin cytoskeleton, which generates biochemical signals that culminate in a rapid expression of matricellular proteins such as cellular communication network 1 (CCN1) and CCN2 (aka connective tissue growth factor or CTGF). Loss or gain of function of these proteins alters genetic programs of cell growth, ECM biosynthesis, and intercellular signaling, that culminate in changes in cell behavior, polarization, and barrier function. In particular, the function of the matricellular protein CCN2/CTGF is critical during retinal vessel development and regeneration wherein new blood vessels form and invest a preformed avascular neural retina following putative gradients of matrix stiffness. These observations underscore the need for further in-depth characterization of the ECM-derived cues that dictate structural and functional properties of the microvasculature, along with the development of new therapeutic strategies addressing the ECM-dependent regulation of pathophysiological stiffening of blood vessels in ischemic retinopathies.

Decreased CCN3 in Systemic Sclerosis Endothelial Cells Contributes to Impaired Angiogenesis

Systemic sclerosis (SSc) is a rare and severe connective tissue disease combining autoimmune and vasculopathy features, ultimately leading to organ fibrosis. Impaired angiogenesis is an often silent and life-threatening complication of the disease. We hypothesize that CCN3, a member of the CCN family of extracellular matrix proteins, which is an antagonist of the profibrotic protein CCN2 as well as a proangiogenic factor, is implicated in SSc pathophysiology. We performed skin biopsies on 26 patients with SSc, both in fibrotic and nonfibrotic areas for 17 patients, and collected 18 healthy control skin specimens for immunohistochemistry and cell culture. Histological analysis of nonfibrotic and fibrotic SSc skin shows a systemic decrease of papillary dermis surface as well as disappearance of capillaries. CCN3 expression is systematically decreased in the dermis of patients with SSc compared with healthy controls, particularly in dermal blood vessels. Moreover, CCN3 is decreased in vitro in endothelial cells from patients with SSc. We show that CCN3 is essential for endothelial cell migration and angiogenesis in vitro. In conclusion, CCN3 may represent a promising therapeutic target for patients with SSc presenting with vascular involvement.

Caught between a "Rho" and a hard place: are CCN1/CYR61 and CCN2/CTGF the arbiters of microvascular stiffness?

The extracellular matrix (ECM) is a deformable dynamic structure that dictates the behavior, function and integrity of blood vessels. The composition, density, chemistry and architecture of major globular and fibrillar proteins of the matrisome regulate the mechanical properties of the vasculature (i.e., stiffness/compliance). ECM proteins are linked via integrins to a protein adhesome directly connected to the actin cytoskeleton and various downstream signaling pathways that enable the cells to respond to external stimuli in a coordinated manner and maintain optimal tissue stiffness. However, cardiovascular risk factors such as diabetes, dyslipidemia, hypertension, ischemia and aging compromise the mechanical balance of the vascular wall. Stiffening of large blood vessels is associated with well-known qualitative and quantitative changes of fibrillar and fibrous macromolecules of the vascular matrisome. However, the mechanical properties of the thin-walled microvasculature are essentially defined by components of the subendothelial matrix. Cellular communication network (CCN) 1 and 2 proteins (aka Cyr61 and CTGF, respectively) of the CCN protein family localize in and act on the pericellular matrix of microvessels and constitute primary candidate markers and regulators of microvascular compliance. CCN1 and CCN2 bind various integrin and non-integrin receptors and initiate signaling pathways that regulate connective tissue remodeling and response to injury, the associated mechanoresponse of vascular cells, and the subsequent inflammatory response. The CCN1 and CCN2 genes are themselves responsive to mechanical stimuli in vascular cells, wherein mechanotransduction signaling converges into the common Rho GTPase pathway, which promotes actomyosin-based contractility and cellular stiffening. However, CCN1 and CCN2 each exhibit unique functional attributes in these processes. A better understanding of their synergistic or antagonistic effects on the maintenance (or loss) of microvascular compliance in physiological and pathological situations will assist more broadly based studies of their functional properties and translational value.

CCN proteins as potential actionable targets in scleroderma

Systemic sclerosis (SSc) is a complex autoimmune connective tissue disease combining inflammatory, vasculopathic and fibrotic manifestations. Skin features, which give their name to the disease and are considered as diagnostic as well as prognostic markers, have not been thoroughly investigated in terms of therapeutic targets. CCN proteins (CYR61/CCN1, CTGF/CCN2, NOV/CCN3 and WISP1-2-3 as CCN4-5-6) are a family of secreted matricellular proteins implicated in major cellular processes such as cell growth, migration, differentiation. They have already been implicated in key pathophysiological processes of SSc, namely fibrosis, vasculopathy and inflammation. In this review, we discuss the possible implication of CCN proteins in SSc pathogenesis, with a special focus on skin features, and identify the potential actionable CCN targets.

Differential protective effects of connective tissue growth factor against Aβ neurotoxicity on neurons and glia

Impaired clearance of amyloid-β peptide (Aβ) leads to abnormal extracellular accumulation of this neurotoxic protein that drives neurodegeneration in sporadic Alzheimer's disease (AD). Connective tissue growth factor (CTGF/CCN2) expression is elevated in plaque-surrounding astrocytes in AD patients. However, the role of CTGF in AD pathogenesis remains unclear. Here we characterized the neuroprotective activity of CTGF. We found that CTGF facilitated Aβ uptake and subsequent degradation within primary glia and neuroblastoma cells. CTGF enhanced extracellular Aβ degradation via membrane-bound matrix metalloproteinase-14 (MMP14) in glia and extracellular MMP13 in neurons. In the brain of a Drosophila AD model, glial-expression of CTGF reduced Aβ deposits, improved locomotor function, and rescued memory deficits. Neuroprotective potential of CTGF against Aβ42-induced photoreceptor degeneration was disrupted through silencing MMPs. Therefore, CTGF may represent a node for potential AD therapeutics as it intervenes in glia-neuron communication via specific MMPs to alleviate Aβ neurotoxicity in the central nervous system.

The Gene Therapy Resource Program: A Decade of Dedication to Translational Research by the National Heart, Lung, and Blood Institute

Over a 10-year period, the Gene Therapy Resource Program (GTRP) of the National Heart Lung and Blood Institute has provided a set of core services to investigators to facilitate the clinical translation of gene therapy. These services have included a preclinical (research-grade) vector production core; current Good Manufacturing Practice clinical-grade vector cores for recombinant adeno-associated virus and lentivirus vectors; a pharmacology and toxicology core; and a coordinating center to manage program logistics and to provide regulatory and financial support to early-phase clinical trials. In addition, the GTRP has utilized a Steering Committee and a Scientific Review Board to guide overall progress and effectiveness and to evaluate individual proposals. These resources have been deployed to assist 82 investigators with 172 approved service proposals. These efforts have assisted in clinical trial implementation across a wide range of genetic, cardiac, pulmonary, and blood diseases. Program outcomes and potential future directions of the program are discussed.

Targeting of CCN2 suppresses tumor progression and improves chemo-sensitivity in urothelial bladder cancer

Urothelial bladder cancer (UBC) is the most common urinary neoplasm in China. CCN family protein 2 (CCN2), a cysteine-rich matricellular protein, is abnormally expressed in several cancer types and involved in tumor progression or chemo-resistance. However, detailed expression patterns and effects of CCN2 in UBC still remain unknown. We found that down-regulation of CCN2 suppressed proliferation, migration and invasion of UBC cells in vitro and targeting of CCN2 decelerated xenograft growth in vivo. When treated with mitomycin C (MMC), CCN2-scilencing UBC cells showed lower survival and higher apoptotic rates and these effects were probably mediated via inactivation of Akt and Erk pathways. We also demonstrated the clinical significance of CCN2 expression, which was higher in UBC tissues and associated with advanced tumor stage and high pathologic grade. Taken together, our data suggest that CCN2 is an oncogene in UBC and might serve as a matricellular target for improving chemotherapeutic efficacy.

Anti-connective tissue growth factor detects and reduces plaque inflammation in early-stage carotid atherosclerotic lesions

This study explored connective tissue growth factor (CTGF)-targeted ultrasmall superparamagnetic iron oxides (USPIOs) for noninvasive MRI of CTGF within carotid atherosclerotic lesions in apoE-deficient (apoE^-/-) mice. Anti-CTGF polyclonal and nonspecific IgG antibodies were conjugated to polyethylene glycol-coated USPIOs, and apoE^-/- carotid partial ligation-model mice were imaged via MRI before and after contrast administration. ApoE^-/- mice were treated with CTGF-neutralizing antibodies for 3 weeks. Carotid artery diameter and plaque volume were measured via MRI in IgG and CTGF antibody-treated groups. Anti-CTGF-USPIO-treated macrophages showed the greatest iron uptake. MRI signal loss was observed in carotid atherosclerotic lesions 24 h after anti-CTGF-USPIO administration, consistent with the presence of nanoparticles, as indicated by pathological examinations. Atheromata in anti-CTGF-treated mice showed reduced macrophage deposition, CTGF expression, and plaque volume. Anti-CTGF-USPIOs can be used for the direct detection of CTGF and imaging of atherosclerotic lesions in vivo. CTGF is a potential therapeutic target for treating atherosclerosis.

CTGF upregulation correlates with MMP-9 level in airway remodeling in a murine model of asthma

INTRODUCTION

Connective tissue growth factor (CTGF) mediates hypertrophy, proliferation, and extracellular matrix synthesis. Matrix metalloproteinase (MMP) plays a role in airway extracellular matrix remodeling. The correlation between CTGF and MMP in airway remodeling of asthma was unknown. This study investigated lung CTGF expression and its correlation with MMP and airway structural changes in a murine model of asthma.

MATERIAL AND METHODS

Female BALB/c mice were sensitized and challenged by intraperitoneal injections and intranasal phosphate-buffered saline (PBS) or ovalbumin (OVA). Airway responsiveness and serum OVA-specific IgE were measured. Airway structural changes were quantified by morphometric analysis. Differential cell counts and MMP-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-1 were evaluated in bronchoalveolar lavage fluid (BALF). Lung CTGF was determined by Western blot.

RESULTS

Serum OVA-specific IgE level and airway responsiveness in enhanced pause (Penh) is significantly higher in sensitized mice challenged with OVA compared to PBS-challenged mice. MMP-2, MMP-9, and TIMP-1 in BALF were significantly higher in OVA mice. Airway structural changes of animals' lungs with OVA challenge showed increased thickness of the smooth muscle layer and numbers of Goblet cells and inflammatory cells and eosinophils near airways and perivascular areas. Lung CTGF expression significantly increased in OVA-challenged mice. CTGF expressions positively correlated with MMP-9 (r = 0.677, p < 0.05), TIMP-1 (r = 0.574, p < 0.05) and thickness of the smooth muscle layer (r = 0.499, p < 0.05).

CONCLUSIONS

This study indicates that CTGF upregulation correlates with MMP-9, probably involved in the pathogenesis of airway remodeling of asthma.

Analysis of CCN Protein Expression and Activities in Vasoproliferative Retinopathies

The retina is a complex neurovascular structure that conveys light/visual image through the optic nerve to the visual cortex of the brain. Neuronal and vascular activities in the retina are physically and functionally intertwined, and vascular alterations are consequential to the proper function of the entire visual system. In particular, alteration of the structure and barrier function of the retinal vasculature is commonly associated with the development of vasoproliferative ischemic retinopathy, a set of clinically well-defined chronic ocular microvascular complications causing blindness in all age groups. Experimentally, the retinal tissue provides researchers with a convenient, easily accessible, and directly observable model suitable to investigate whether and how newly identified genes regulate vascular development and regeneration. The six mammalian CCN gene-encoded proteins are part of an extracellular network of bioactive molecules that regulate various aspects of organ system development and diseases. Whether and how these molecules regulate the fundamental aspects of blood vessel development and pathology and subsequently the neurovascular link in the retina are open-ended questions. Sophisticated methods have been developed to gain insight into the pathogenesis of retinal vasculopathy. This chapter describes several useful methodologies and animal models to investigate the regulation and potential relevance of the CCN proteins in vasoproliferative diseases of the retina.

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

ETHNOPHARMACOLOGICAL RELEVANCE

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

THE AIM OF THIS STUDY

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

RESULTS

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

CONCLUSION

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

Association of MMP-2 gene haplotypes with thoracic aortic dissection in chinese han population

Background

Thoracic aortic dissection (TAD) is the most common life-threatening disorder, and MMP-2 is involved in TAD pathogenesis. Our purpose is to systematically evaluate the association of the MMP-2 gene with TAD risk in Chinese Han population.

Methods

In our case–control study, we recruited 755 unrelated participants: 315 case participants with TAD and 440 controls. Twenty-two tag SNPs were selected from MMP-2 gene and were genotyped. Genotype data were analyzed by logistic regression.

Results

Although we did not find any significant association for MMP-2 SNPs using single-marker analysis, we identified many windows with haplotype frequencies significantly different between case participants and control participants using a variable-sized sliding-window strategy. In particular, the most significant association was shown by a 2-SNP window consisting of rs2241145 and rs9928731 (omnibus test: asymptotic P_asym = 7.48 × 10 ⁻⁵ and empirical P_emp = 0.001867). There were two protective haplotypes: CT (P_asym = 0.00303; odds ratio [OR], 0.403) and GC (P_asym = 0.000976; OR, 0.448).

Conclusions

MMP-2 haplotypes are associated with genetic susceptibility to thoracic aortic dissection in Chinese Han population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0188-4) contains supplementary material, which is available to authorized users.

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

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

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

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

The role of extracellular matrix in retinal vascular development and preretinal neovascularization

Extracellular matrix (ECM) plays a central role in angiogenesis. ECM degrading enzymes breakdown the pre-existing vascular basement membrane at an early stage of angiogenesis and subsequently degrade stromal ECM as the new vessels invade into tissues. Conversely certain ECM components including collagen, fibronectin or fibrin are required for endothelial cell migration and tube morphogenesis. As the new vessels form they lay down a basement membrane that surrounds the endothelial tubes and is essential for their stability. In the rodent eye the transient expression of fibronectin and matricellular proteins plays a key role in retinal vascular development. In pathological retinal angiogenesis, such as in proliferative diabetic retinopathy, preretinal neovascularization occurs where new blood vessels invade the cortical vitreous gel and these blood vessels require vitreous collagen for their growth. The vitreous is normally anti-angiogenic and contains endogenous ECM inhibitors of angiogenesis including opticin and thombospondins, and ECM fragments such as endostatin. In preretinal neovascularization, the combined anti-angiogenic effects of these molecules are overcome by an excess of growth factors such as vascular endothelial growth factor-A, and new vessels grow into the vitreous with potentially blinding sequelae.

The role of CTGF in diabetic retinopathy

Connective tissue growth factor (CTGF, CCN2) contributes to fibrotic responses in diabetic retinopathy, both before clinical manifestations occur in the pre-clinical stage of diabetic retinopathy (PCDR) and in proliferative diabetic retinopathy (PDR), the late clinical stage of the disease. CTGF is a secreted protein that modulates the actions of many growth factors and extracellular matrix (ECM) proteins, leading to tissue reorganization, such as ECM formation and remodeling, basal lamina (BL) thickening, pericyte apoptosis, angiogenesis, wound healing and fibrosis. In PCDR, CTGF contributes to thickening of the retinal capillary BL and is involved in loss of pericytes. In this stage, CTGF expression is induced by advanced glycation end products, and by growth factors such as vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β. In PDR, the switch from neovascularization to a fibrotic phase - the angio-fibrotic switch - in PDR is driven by CTGF, in a critical balance with vascular endothelial growth factor (VEGF). We discuss here the roles of CTGF in the pathogenesis of DR in relation to ECM remodeling and wound healing mechanisms, and explore whether CTGF may be a potential novel therapeutic target in the clinical management of early as well as late stages of DR.

The matricellular protein CCN1 controls retinal angiogenesis by targeting VEGF, Src homology 2 domain phosphatase-1 and Notch signaling

Physiological angiogenesis depends on the highly coordinated actions of multiple angiogenic regulators. CCN1 is a secreted cysteine-rich and integrin-binding matricellular protein required for proper cardiovascular development. However, our understanding of the cellular origins and activities of this molecule is incomplete. Here, we show that CCN1 is predominantly expressed in angiogenic endothelial cells (ECs) at the leading front of actively growing vessels in the mouse retina. Endothelial deletion of CCN1 in mice using a Cre-Lox system is associated with EC hyperplasia, loss of pericyte coverage and formation of dense retinal vascular networks lacking the normal hierarchical arrangement of arterioles, capillaries and venules. CCN1 is a product of an immediate-early gene that is transcriptionally induced in ECs in response to stimulation by vascular endothelial growth factor (VEGF). We found that CCN1 activity is integrated with VEGF receptor 2 (VEGF-R2) activation and downstream signaling pathways required for tubular network formation. CCN1-integrin binding increased the expression of and association between Src homology 2 domain-containing protein tyrosine phosphatase-1 (SHP-1) and VEGF-R2, which leads to rapid dephosphorylation of VEGF-R2 tyrosine, thus preventing EC hyperproliferation. Predictably, CCN1 further brings receptors/signaling molecules into proximity that are otherwise spatially separated. Furthermore, CCN1 induces integrin-dependent Notch activation in cultured ECs, and its targeted gene inactivation in vivo alters Notch-dependent vascular specification and remodeling, suggesting that functional levels of Notch signaling requires CCN1 activity. These data highlight novel functions of CCN1 as a naturally optimized molecule, fine-controlling key processes in physiological angiogenesis and safeguarding against aberrant angiogenic responses.

BMP9 Crosstalk with the Hippo Pathway Regulates Endothelial Cell Matricellular and Chemokine Responses

Endoglin is a type III TGFβ auxiliary receptor that is upregulated in endothelial cells during angiogenesis and, when mutated in humans, results in the vascular disease hereditary hemorrhagic telangiectasia (HHT). Though endoglin has been implicated in cell adhesion, the underlying molecular mechanisms are still poorly understood. Here we show endoglin expression in endothelial cells regulates subcellular localization of zyxin in focal adhesions in response to BMP9. RNA knockdown of endoglin resulted in mislocalization of zyxin and altered formation of focal adhesions. The mechanotransduction role of focal adhesions and their ability to transmit regulatory signals through binding of the extracellular matrix are altered by endoglin deficiency. BMP/TGFβ transcription factors, SMADs, and zyxin have recently been implicated in a newly emerging signaling cascade, the Hippo pathway. The Hippo transcription coactivator, YAP1 (yes-associated protein 1), has been suggested to play a crucial role in mechanotransduction and cell-cell contact. Identification of BMP9-dependent nuclear localization of YAP1 in response to endoglin expression suggests a mechanism of crosstalk between the two pathways. Suppression of endoglin and YAP1 alters BMP9-dependent expression of YAP1 target genes CCN1 (cysteine-rich 61, CYR61) and CCN2 (connective tissue growth factor, CTGF) as well as the chemokine CCL2 (monocyte chemotactic protein 1, MCP-1). These results suggest a coordinate effect of endoglin deficiency on cell matrix remodeling and local inflammatory responses. Identification of a direct link between the Hippo pathway and endoglin may reveal novel mechanisms in the etiology of HHT.

CTGF increases matrix metalloproteinases expression and subsequently promotes tumor metastasis in human osteosarcoma through down-regulating miR-519d

Osteosarcoma, the most common primary malignant bone tumor, shows potent capacity for local invasion and distant metastasis. Connective tissue growth factor (CTGF/CCN2), a secreted protein, binds to integrins, modulates invasive behavior of certain human cancer cells. Effect of CTGF in metastasis of human osteosarcoma is unknown. We found overexpression of CTGF increasing matrix metalloproteinases (MMPs)-2 and MMP-3 expression as well as promoting cell migration. MicroRNA (miRNA) analysis of CTGF-overexpressed osteosarcoma versus control cells probed mechanisms of CTGF-mediated promotion of migration. Among miRNAs regulated by CTGF, miR-519d was most downregulated after CTGF treatment. Co-transfection with miR-519d mimic reversed CTGF-mediated MMPs expression and cell migration. Also, MEK and ERK inhibitors or mutants reduced CTGF-increased cell migration and miR-519d suppression. By contrast, knockdown of CTGF diminished lung metastasis in vivo. Clinical samples indicate CTGF expression as linked with clinical stage and tumor metastasis. Taken together, data show CTGF elevating MMPs expression and subsequently promoting tumor metastasis in human osteosarcoma, down-regulating miR-519d via MEK and ERK pathways, making CTGF a new molecular therapeutic target in osteosarcoma metastasis.

Cellular and molecular actions of CCN2/CTGF and its role under physiological and pathological conditions

CCN family protein 2 (CCN2), also widely known as connective tissue growth factor (CTGF), is one of the founding members of the CCN family of matricellular proteins. Extensive investigation on CCN2 over decades has revealed the novel molecular action and functional properties of this unique signalling modulator. By its interaction with multiple molecular counterparts, CCN2 yields highly diverse and context-dependent biological outcomes in a variety of microenvironments. Nowadays, CCN2 is recognized to conduct the harmonized development of relevant tissues, such as cartilage and bone, in the skeletal system, by manipulating extracellular signalling molecules involved therein by acting as a hub through a web. However, on the other hand, CCN2 occasionally plays profound roles in major human biological disorders, including fibrosis and malignancies in major organs and tissues, by modulating the actions of key molecules involved in these clinical entities. In this review, the physiological and pathological roles of this unique protein are comprehensively summarized from a molecular network-based viewpoint of CCN2 functionalities.

Bevacizumab modulates the process of fibrosis in vitro

BACKGROUND

Fibrosis is the most common side effect after anti-vascular epithelial growth factor (VEGF) therapy (intravitreal bevacizumab) for retinal or choroidal neovascularization. This study was to investigate the efficacy of bevacizumab on the expressions of fibrosis-related cytokines in human umbilical vein endothelial cells (HUVECs) in vitro.

METHODS

Cultured HUVECs were divided into groups of controls (group 1), hypoxia (group 2) and hypoxia combined with bevacizumab (group 3). No treatment was given in group 1. In group 2, cobalt(II) chloride (CoCl₂) (200 μm) was added to the medium. In group 3, in addition to CoCl₂, bevacizumab was mixed in the medium, with a final concentration of 0.25 mg/mL, roughly equal to the concentration used clinically. The expressions of connective tissue growth factor (CTGF), transforming growth factor-β₂ (TGF-β₂) and basic fibroblast growth factor-2 (bFGF-2) were evaluated by SYBR green real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay at 6 h, 12 h, 24 h and 48 h. Matrix metalloproteinases (MMP)-2 was detected by SYBR green real-time PCR and Western blotting at each time point.

RESULTS

Both messenger RNA and protein levels of CTGF, bFGF, TGF-β₂ and MMP-2 in group 2 were higher than group 1 (P < 0.05). In group 3, the expressions of CTGF, bFGF, TGF-β₂ and MMP-2 were upregulated compared with group 2 (P < 0.05).

CONCLUSIONS

Bevacizumab at clinical doses can exert pro-fibrotic effects on HUVECs by upregulating the expressions of CTGF, bFGF, TGF-β₂ and MMP-2. This may be involved in fibrosis after anti-VEGF therapy.

Remodeling of aorta extracellular matrix as a result of transient high oxygen exposure in newborn rats: implication for arterial rigidity and hypertension risk

Neonatal high-oxygen exposure leads to elevated blood pressure, microvascular rarefaction, vascular dysfunction and arterial (aorta) rigidity in adult rats. Whether structural changes are present in the matrix of aorta wall is unknown. Considering that elastin synthesis peaks in late fetal life in humans, and early postnatal life in rodents, we postulated that transient neonatal high-oxygen exposure can trigger premature vascular remodelling. Sprague Dawley rat pups were exposed from days 3 to 10 after birth to 80% oxygen (vs. room air control) and were studied at 4 weeks. Blood pressure and vasomotor response of the aorta to angiotensin II and to the acetylcholine analogue carbachol were not different between groups. Vascular superoxide anion production was similar between groups. There was no difference between groups in aortic cross sectional area, smooth muscle cell number or media/lumen ratio. In oxygen-exposed rats, aorta elastin/collagen content ratio was significantly decreased, the expression of elastinolytic cathepsin S was increased whereas collagenolytic cathepsin K was decreased. By immunofluorescence we observed an increase in MMP-2 and TIMP-1 staining in aortas of oxygen-exposed rats whereas TIMP-2 staining was reduced, indicating a shift in the balance towards degradation of the extra-cellular matrix and increased deposition of collagen. There was no significant difference in MMP-2 activity between groups as determined by gelatin zymography. Overall, these findings indicate that transient neonatal high oxygen exposure leads to vascular wall alterations (decreased elastin/collagen ratio and a shift in the balance towards increased deposition of collagen) which are associated with increased rigidity. Importantly, these changes are present prior to the elevation of blood pressure and vascular dysfunction in this model, and may therefore be contributory.

The development of hyperbaric oxygen therapy for skin rejuvenation and treatment of photoaging

Hyperbaric oxygen therapy (HBOT), a therapy that have patients breath in pure oxygen in a pressurized chamber, has been long used as a treatment for conditions such as decompression sickness and carbon monoxide poisoning. Oxygen recently has been found to be an important component in skin rejuvenation, treatment of photoaging skin, and improvement in skin complexions. The interest in the use of HBOT for this purpose is continually growing and becoming more widespread. In addition to aging and genetic makeup, chronic UV radiation due to everyday exposure, especially UV-B, can greatly increase the rate of wrinkle formation through increasing skin angiogenesis and degradation of extracellular matrix molecules. The use of HBOT and hyperoxia conditions has been found to attenuate the formation of wrinkles from UV irradiation. It accomplishes the task by possibly inhibiting various processes and pathways involved such as the HIF1-α, VEGF, neutrophil infiltrations, and MMP-2 & MMP-9, which are directly involved with promoting skin angiogenesis in its active state. There are currently medical aesthetic clinics that are using oxygen therapy under high pressure applied directly to skin to reduce visible wrinkles but this procedure is not widespread yet due to more research that needs to be done on this topic. However, this treatment for wrinkles is definitely growing due to recent studies done showing the effectiveness of oxygen therapy on wrinkles. This review article will explore and summarize researches done on possible mechanisms dealing with the use of oxygen therapy for reduction of UVB-caused wrinkles, its side effects, and its possible future improvement and use in medicine.

Connective tissue growth factor is involved in structural retinal vascular changes in long-term experimental diabetes

Early retinal vascular changes in the development of diabetic retinopathy (DR) include capillary basal lamina (BL) thickening, pericyte loss and the development of acellular capillaries. Expression of the CCN (connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed) family member CCN2 or connective tissue growth factor (CTGF), a potent inducer of the expression of BL components, is upregulated early in diabetes. Diabetic mice lacking one functional CTGF allele (CTGF⁺/⁻) do not show this BL thickening. As early events in DR may be interrelated, we hypothesized that CTGF plays a role in the pathological changes of retinal capillaries other than BL thickening. We studied the effects of long-term (6-8 months) streptozotocin-induced diabetes on retinal capillary BL thickness, numbers of pericytes and the development of acellular capillaries in wild type and CTGF⁺/⁻ mice. Our results show that an absence of BL thickening of retinal capillaries in long-term diabetic CTGF⁺/⁻ mice is associated with reduced pericyte dropout and reduced formation of acellular capillaries. We conclude that CTGF is involved in structural retinal vascular changes in diabetic rodents. Inhibition of CTGF in the eye may therefore be protective against the development of DR.

Establishment of a novel murine model of ischemic cardiomyopathy with multiple diffuse coronary lesions

Objectives

Atherosclerotic lesions of the coronary arteries are the pathological basis for myocardial infarction and ischemic cardiomyopathy. Progression of heart failure after myocardial infarction is associated with cardiac remodeling, which has been studied by means of coronary ligation in mice. However, this ligation model requires excellent techniques. Recently, a new murine model, HypoE mouse was reported to exhibit atherogenic Paigen diet-induced coronary atherosclerosis and myocardial infarction; however, the HypoE mice died too early to make possible investigation of cardiac remodeling. Therefore, we aimed to modify the HypoE mouse model to establish a novel model for ischemic cardiomyopathy caused by atherosclerotic lesions, which the ligation model does not exhibit.

Methods and Results

In our study, the sustained Paigen diet for the HypoE mice was shortened to 7 or 10 days, allowing the mice to survive longer. The 7-day Paigen diet intervention starting when the mice were 8 weeks old was adequate to permit the mice to survive myocardial infarction. Our murine model, called the “modified HypoE mouse”, was maintained until 8 weeks, with a median survival period of 36 days, after the dietary intervention (male, n = 222). Echocardiography demonstrated that the fractional shortening 2 weeks after the Paigen diet (n = 14) significantly decreased compared with that just before the Paigen diet (n = 6) (31.4±11.9% vs. 54.4±2.6%, respectively, P<0.01). Coronary angiography revealed multiple diffuse lesions. Cardiac remodeling and fibrosis were identified by serial analyses of cardiac morphological features and mRNA expression levels in tissue factors such as MMP-2, MMP-9, TIMP-1, collagen-1, and TGF-β.

Conclusion

Modified HypoE mice are a suitable model for ischemic cardiomyopathy with multiple diffuse lesions and may be considered as a novel and convenient model for investigations of cardiac remodeling on a highly atherogenic background.

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

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

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

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