Integrin-dependent Functions of the Angiogenic Inducer NOV (CCN3)

Integrins regulation of wound healing processes: insights for chronic skin wound therapeutics

Integrins are heterodimers composed of non-covalently associated alpha and beta subunits that mediate the dynamic linkage between extracellular adhesion molecules and the intracellular actin cytoskeleton. Integrins are present in various tissues and organs and are involved in different physiological and pathological molecular responses in vivo. Wound healing is an important process in the recovery from traumatic diseases and consists of three overlapping phases: inflammation, proliferation, and remodeling. Integrin regulation acts throughout the wound healing process to promote wound healing. Prolonged inflammation may lead to failure of wound healing, such as wound chronicity. One of the main causes of chronic wound formation is bacterial colonization of the wound. In this review, we review the role of integrins in the regulation of wound healing processes such as angiogenesis and re-epithelialization, as well as the role of integrins in mediating bacterial infections during wound chronicity, and the challenges and prospects of integrins as therapeutic targets for infected wound healing.

CCN3, POSTN, and PTHLH as potential key regulators of genomic integrity and cellular survival in iPSCs

Reprogramming human somatic cells into a pluripotent state, achieved through the activation of well-defined transcriptional factors known as OSKM factors, offers significant potential for regenerative medicine. While OSKM factors are a robust reprogramming method, efficiency remains a challenge, with only a fraction of cells undergoing successful reprogramming. To address this, we explored genes related to genomic integrity and cellular survival, focusing on iPSCs (A53T-PD1) that displayed enhanced colony stability. Our investigation had revealed three candidate genes CCN3, POSTN, and PTHLH that exhibited differential expression levels and potential roles in iPSC stability. Subsequent analyses identified various protein interactions for these candidate genes. POSTN, significantly upregulated in A53T-PD1 iPSC line, showed interactions with extracellular matrix components and potential involvement in Wnt signaling. CCN3, also highly upregulated, demonstrated interactions with TP53, CDKN1A, and factors related to apoptosis and proliferation. PTHLH, while upregulated, exhibited interactions with CDK2 and genes involved in cell cycle regulation. RT-qPCR validation confirmed elevated CCN3 and PTHLH expression in A53T-PD1 iPSCs, aligning with RNA-seq findings. These genes' roles in preserving pluripotency and cellular stability require further exploration. In conclusion, we identified CCN3, POSTN, and PTHLH as potential contributors to genomic integrity and pluripotency maintenance in iPSCs. Their roles in DNA repair, apoptosis evasion, and signaling pathways could offer valuable insights for enhancing reprogramming efficiency and sustaining pluripotency. Further investigations are essential to unravel the mechanisms underlying their actions.

CCN3/NOV serum levels in coronary artery disease (CAD) patients and its correlation with TNF-α and IL-6

INTRODUCTION

Dysregulation in the secretion of adipokines or adipocytokines plays a significant role in triggering a pro-inflammatory state, leading to endothelial dysfunction and insulin resistance, and ultimately elevating the risk of atherosclerosis and coronary artery disease (CAD). Previous studies have shown a link between NOV/CCN3 (an adipokine) and obesity, insulin resistance, and inflammation. However, no research has explored the relationship between CCN3 serum levels and CAD. Therefore, we conducted the first investigation to examine the correlation between CCN3 and CAD risk factors in patients.

METHODS

In a case-control study, we measured the serum levels of CCN3, IL-6, adiponectin, and TNF-α in 88 angiography-confirmed CAD patients and 88 control individuals using ELISA kits. Additionally, we used an auto analyzer and commercial kits to measure the biochemical parameters.

RESULTS

In patients with CAD, the serum levels of CCN3, TNF-α, and IL-6 were significantly higher compared to the control group, whereas lower levels of adiponectin were observed in the CAD group (P < 0.0001). A positive correlation was found between CCN3 and IL-6 and TNF-α in the CAD group ([r = 0.38, P < 0.0001], [r = 0.39, P < 0.0001], respectively). A binary logistic regression analysis showed the risk of CAD in the model adjusted (OR [95% CI] = 1.29 [1.19 - 1.41]), (P < 0.0001). We determined a cut-off value of CCN3 (3169.6 pg/mL) to distinguish CAD patients from the control group, with good sensitivity and specificity obtained for this finding (83.8% and 87.5%, respectively).

CONCLUSION

This study provides evidence of a positive association between CCN3 serum levels and CAD, as well as inflammation markers such as IL-6 and TNF-α. These findings suggest that CCN3 may serve as a potential biomarker for CAD, and further investigations are necessary to validate this association and explore its potential use in clinical settings.

Non-classical monocytes promote neurovascular repair in cerebral small vessel disease associated with microinfarctions via CX3CR1

Cerebral small vessel disease (cSVD) constitutes a major risk factor for dementia. Monocytes play important roles in cerebrovascular disorders. Herein, we aimed to investigate the contribution of non-classical C-X3-C motif chemokine receptor (CX3CR)1 monocytes to cSVD pathobiology and therapy. To this end, we generated chimeric mice in which CX3CR1 in non-classical monocytes was either functional (CX3CR1GFP/+) or dysfunctional (CX3CR1GFP/GFP). cSVD was induced in mice via the micro-occlusion of cerebral arterioles, and novel immunomodulatory approaches targeting CX3CR1 monocyte production were used. Our findings demonstrate that CX3CR1GFP/+ monocytes transiently infiltrated the ipsilateral hippocampus and were recruited to the microinfarcts 7 days after cSVD, inversely associated with neuronal degeneration and blood-brain barrier (BBB) disruption. Dysfunctional CX3CR1GFP/GFP monocytes failed to infiltrate the injured hippocampus and were associated with exacerbated microinfarctions and accelerated cognitive decline, accompanied with an impaired microvascular structure. Pharmacological stimulation of CX3CR1GFP/+ monocyte generation attenuated neuronal loss and improved cognitive functions by promoting microvascular function and preserving cerebral blood flow (CBF). These changes were associated with elevated levels of pro-angiogenic factors and matrix stabilizers in the blood circulation. The results indicate that non-classical CX3CR1 monocytes promote neurovascular repair after cSVD and constitute a promising target for the development of new therapies.

Blocking CCN2 Reduces Established Palmar Neuromuscular Fibrosis and Improves Function Following Repetitive Overuse Injury

The matricellular protein cell communication factor 2/connective tissue growth factor (CCN2/CTGF) is critical to development of neuromuscular fibrosis. Here, we tested whether anti-CCN2 antibody treatment will reduce established forepaw fibro-degenerative changes and improve function in a rat model of overuse injury. Adult female rats performed a high repetition high force (HRHF) task for 18 weeks. Tissues were collected from one subset after 18 wks (HRHF-Untreated). Two subsets were provided 6 wks of rest with concurrent treatment with anti-CCN2 (HRHF-Rest/anti-CCN2) or IgG (HRHF-Rest/IgG). Results were compared to IgG-treated Controls. Forepaw muscle fibrosis, neural fibrosis and entheseal damage were increased in HRHF-Untreated rats, compared to Controls, and changes were ameliorated in HRHF-Rest/anti-CCN2 rats. Anti-CCN2 treatment also reduced phosphorylated-β-catenin (pro-fibrotic protein) in muscles and distal bone/entheses complex, and increased CCN3 (anti-fibrotic) in the same tissues, compared to HRHF-Untreated rats. Grip strength declines and mechanical sensitivity observed in HRHF-Untreated improved with rest; grip strength improved further in HRHF-Rest/anti-CCN2. Grip strength declines correlated with muscle fibrosis, entheseal damage, extraneural fibrosis, and decreased nerve conduction velocity, while enhanced mechanical sensitivity (a pain-related behavior) correlated with extraneural fibrosis. These studies demonstrate that blocking CCN2 signaling reduces established forepaw neuromuscular fibrosis and entheseal damage, which improves forepaw function, following overuse injury.

Functions for platelet factor 4 (PF4/CXCL4) and its receptors in fibroblast-myofibroblast transition and fibrotic failure of arteriovenous fistulas (AVFs)

BACKGROUND

Over 60% of End Stage Renal Disease (ESRD) patients are relying on hemodialysis (HD) to survive, and the arteriovenous fistula (AVF) is the preferred vascular access method for HD. However approximately half of all newly created AVF fail to mature and cannot be used without a salvage procedure. We have recently demonstrated an association between AVF maturation failure and post-operative fibrosis, while our RNA-seq study also revealed that veins that ultimately failed during AVF maturation had elevated levels of platelet factor 4 (PF4/CXCL4). However, a link between these two findings was yet to be established.

METHODS

In this study, we investigated potential mechanisms between PF4 levels and fibrotic remodeling in veins. We compared the local expression of PF4 and fibrosis marker integrin β6 (ITGB6) in veins that successfully underwent maturation with that in veins that ultimately failed to mature. We also measured the changes of expression level of α-smooth muscle actin (αSMA/ACTA2) and collagen (Col1/COL1A1) in venous fibroblasts upon various treatments, such as PF4 pharmacological treatment, alteration of PF4 expression, and blocking of PF4 receptors.

RESULTS

We found that PF4 is expressed in veins and co-localizes with αSMA. In venous fibroblasts, PF4 stimulates expression of αSMA and Col1 via different pathways. The former requires integrins αvβ5 and α5β1, while chemokine receptor CXCR3 is needed for the latter. Interestingly, we also discovered that the expression of PF4 is associated with that of ITGB6, the β subunit of integrin αvβ6. This integrin is critical for the activation of the major fibrosis factor TGFβ, and overexpression of PF4 promotes activation of the TGFβ pathway.

CONCLUSIONS

These results indicate that upregulation of PF4 may cause venous fibrosis both directly by stimulating fibroblast differentiation and expression of extracellular matrix (ECM) molecules and indirectly by facilitating the activation of the TGFβ pathway.

The advance of CCN3 in fibrosis

The extracellular matrix (ECM) is comprised of various extracellular macromolecules, including collagen, enzymes, and glycoproteins, which offer structural and biochemical support to neighboring cells. After tissue injury, extracellular matrix proteins deposit in the damaged tissue to promote tissue healing. However, an imbalance between ECM production and degradation can result in excessive deposition, leading to fibrosis and subsequent organ dysfunction. Acting as a regulatory protein within the extracellular matrix, CCN3 plays a crucial role in numerous biological processes, such as cell proliferation, angiogenesis, tumorigenesis, and wound healing. Many studies have demonstrated that CCN3 can reduce the production of ECM in tissues through diverse mechanisms thereby exerting an inhibitory effect on fibrosis. Consequently, CCN3 emerges as a promising therapeutic target for ameliorating fibrosis.

Myofibroblast Ccn3 is regulated by Yap and Wwtr1 and contributes to adverse cardiac outcomes

Introduction

While Yap and Wwtr1 regulate resident cardiac fibroblast to myofibroblast differentiation following cardiac injury, their role specifically in activated myofibroblasts remains unexplored.

Methods

We assessed the pathophysiological and cellular consequence of genetic depletion of Yap alone (Yap fl/fl ;Postn MCM ) or Yap and Wwtr1 (Yap fl/fl ;Wwtr1 fl/+ ;Postn MCM ) in adult mouse myofibroblasts following myocardial infarction and identify and validate novel downstream factors specifically in cardiac myofibroblasts that mediate pathological remodeling.

Results

Following myocardial infarction, depletion of Yap in myofibroblasts had minimal effect on heart function while depletion of Yap/Wwtr1 resulted in smaller scars, reduced interstitial fibrosis, and improved ejection fraction and fractional shortening. Single cell RNA sequencing of interstitial cardiac cells 7 days post infarction showed suppression of pro-fibrotic genes in fibroblasts derived from Yap fl/fl ,Wwtr1 fl/+ ;Postn MCM hearts. In vivo myofibroblast depletion of Yap/Wwtr1 as well in vitro knockdown of Yap/Wwtr1 dramatically decreased RNA and protein expression of the matricellular factor Ccn3. Administration of recombinant CCN3 to adult mice following myocardial infarction remarkably aggravated cardiac function and scarring. CCN3 administration drove myocardial gene expression of pro-fibrotic genes in infarcted left ventricles implicating CCN3 as a novel driver of cardiac fibrotic processes following myocardial infarction.

Discussion

Yap/Wwtr1 depletion in myofibroblasts attenuates fibrosis and significantly improves cardiac outcomes after myocardial infarction and we identify Ccn3 as a factor downstream of Yap/Wwtr1 that contributes to adverse cardiac remodeling post MI. Myofibroblast expression of Yap, Wwtr1, and Ccn3 could be further explored as potential therapeutic targets for modulating adverse cardiac remodeling post injury.

The meningeal transcriptional response to traumatic brain injury and aging

Emerging evidence suggests that the meningeal compartment plays instrumental roles in various neurological disorders, however, we still lack fundamental knowledge about meningeal biology. Here, we utilized high-throughput RNA sequencing (RNA-seq) techniques to investigate the transcriptional response of the meninges to traumatic brain injury (TBI) and aging in the sub-acute and chronic time frames. Using single-cell RNA sequencing (scRNA-seq), we first explored how mild TBI affects the cellular and transcriptional landscape in the meninges in young mice at one-week post-injury. Then, using bulk RNA-seq, we assessed the differential long-term outcomes between young and aged mice following TBI. In our scRNA-seq studies, we highlight injury-related changes in differential gene expression seen in major meningeal cell populations including macrophages, fibroblasts, and adaptive immune cells. We found that TBI leads to an upregulation of type I interferon (IFN) signature genes in macrophages and a controlled upregulation of inflammatory-related genes in the fibroblast and adaptive immune cell populations. For reasons that remain poorly understood, even mild injuries in the elderly can lead to cognitive decline and devastating neuropathology. To better understand the differential outcomes between the young and the elderly following brain injury, we performed bulk RNA-seq on young and aged meninges 1.5 months after TBI. Notably, we found that aging alone induced upregulation of meningeal genes involved in antibody production by B cells and type I IFN signaling. Following injury, the meningeal transcriptome had largely returned to its pre-injury signature in young mice. In stark contrast, aged TBI mice still exhibited upregulation of immune-related genes and downregulation of genes involved in extracellular matrix remodeling. Overall, these findings illustrate the dynamic transcriptional response of the meninges to mild head trauma in youth and aging.

Matricellular proteins in cutaneous wound healing

Cutaneous wound healing is a complex process that encompasses alterations in all aspects of the skin including the extracellular matrix (ECM). ECM consist of large structural proteins such as collagens and elastin as well as smaller proteins with mainly regulative properties called matricellular proteins. Matricellular proteins bind to structural proteins and their functions include but are not limited to interaction with cell surface receptors, cytokines, or protease and evoking a cellular response. The signaling initiated by matricellular proteins modulates differentiation and proliferation of cells having an impact on the tissue regeneration. In this review we give an overview of the matricellular proteins that have been found to be involved in cutaneous wound healing and summarize the information known to date about their functions in this process.

Fibroblast Growth Factors and Cellular Communication Network Factors: Intimate Interplay by the Founding Members in Cartilage

Fibroblast growth factors (FGFs) constitute a large family of signaling molecules that act in an autocrine/paracrine, endocrine, or intracrine manner, whereas the cellular communication network factors (CCN) family is composed of six members that manipulate extracellular signaling networks. FGFs and CCNs are structurally and functionally distinct, except for the common characteristics as matricellular proteins. Both play significant roles in the development of a variety of tissues and organs, including the skeletal system. In vertebrates, most of the skeletal parts are formed and grow through a process designated endochondral ossification, in which chondrocytes play the central role. The growth plate cartilage is the place where endochondral ossification occurs, and articular cartilage is left to support the locomotive function of joints. Several FGFs, including FGF-2, one of the founding members of this family, and all of the CCNs represented by CCN2, which is required for proper skeletal development, can be found therein. Research over a decade has revealed direct binding of CCN2 to FGFs and FGF receptors (FGFRs), which occasionally affect the biological outcome via FGF signaling. Moreover, a recent study uncovered an integrated regulation of FGF and CCN genes by FGF signaling. In this review, after a brief introduction of these two families, molecular and genetic interactions between CCN and FGF family members in cartilage, and their biological effects, are summarized. The molecular interplay represents the mutual involvement of the other in their molecular functions, leading to collaboration between CCN2 and FGFs during skeletal development.

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.

Identification of Key Determinants of Cerebral Malaria Development and Inhibition Pathways

Cerebral malaria (CM), coma caused by Plasmodium falciparum-infected red blood cells (iRBCs), is the deadliest complication of malaria. The mechanisms that lead to CM development are incompletely understood. Here we report on the identification of activation and inhibition pathways leading to mouse CM with supporting evidence from the analysis of human specimens. We find that CM suppression can be induced by vascular injury when sporozoites exit the circulation to infect the liver and that CM suppression is mediated by the release of soluble factors into the circulation. Among these factors is insulin like growth factor 1 (IGF1), administration of which inhibits CM development in mice. IMPORTANCE Liver infection by Plasmodium sporozoites is a required step for infection of the organism. We found that alternate pathways of sporozoite liver infection differentially influence cerebral malaria (CM) development. CM is one of the primary causes of death following malaria infection. To date, CM research has focused on how CM phenotypes develop but no successful therapeutic treatment or prognostic biomarkers are available. Here we show for the first time that sporozoite liver invasion can trigger CM-inhibitory immune responses. Importantly, we identified a number of early-stage prognostic CM inhibitory biomarkers, many of which had never been associated with CM development. Serological markers identified using a mouse model are directly relevant to human CM.

Cellular communication network factor 3 in cartilage development and maintenance

Cellular communication network factor (CCN) 3 is one of the classical members of the CCN family, which are characterized by common molecular structures and multiple functionalities. Although this protein was discovered as a gene product overexpressed in a truncated form in nephroblastoma, recent studies have revealed its physiological roles in the development and homeostasis of mammalian species, in addition to its pathological association with a number of diseases. Cartilage is a tissue that creates most of the bony parts and cartilaginous tissues that constitute the human skeleton, in which CCN3 is also differentially produced to exert its molecular missions therein. In this review article, after the summary of the molecular structure and function of CCN3, recent findings on the regulation of ccn3 expression and the roles of CCN3 in endochondral ossification, cartilage development, maintenance and disorders are introduced with an emphasis on the metabolic regulation and function of this matricellular multifunctional molecule.

RFX1-mediated CCN3 induction that may support chondrocyte survival under starved conditions

Cellular communication network factor (CCN) family members are multifunctional matricellular proteins that manipulate and integrate extracellular signals. In our previous studies investigating the role of CCN family members in cellular metabolism, we found three members that might be under the regulation of energy metabolism. In this study, we confirmed that CCN2 and CCN3 are the only members that are tightly regulated by glycolysis in human chondrocytic cells. Interestingly, CCN3 was induced under a variety of impaired glycolytic conditions. This CCN3 induction was also observed in two breast cancer cell lines with a distinct phenotype, suggesting a basic role of CCN3 in cellular metabolism. Reporter gene assays indicated a transcriptional regulation mediated by an enhancer in the proximal promoter region. As a result of analyses in silico, we specified regulatory factor binding to the X-box 1 (RFX1) as a candidate that mediated the transcriptional activation by impaired glycolysis. Indeed, the inhibition of glycolysis induced the expression of RFX1, and RFX1 silencing nullified the CCN3 induction by impaired glycolysis. Subsequent experiments with an anti-CCN3 antibody indicated that CCN3 supported the survival of chondrocytes under impaired glycolysis. Consistent with these findings in vitro, abundant CCN3 production by chondrocytes in the deep zones of developing epiphysial cartilage, which are located far away from the synovial fluid, was confirmed in vivo. Our present study uncovered that RFX1 is the mediator that enables CCN3 induction upon cellular starvation, which may eventually assist chondrocytes in retaining their viability, even when there is an energy supply shortage.

PVT1 signals an androgen-dependent transcriptional repression program in prostate cancer cells and a set of the repressed genes predicts high-risk tumors

BACKGROUND

Androgen receptor (AR) and polycomb repressive complex 2 (PRC2) are known to co-occupy the loci of genes that are downregulated by androgen-stimulus. Long intergenic non-coding RNA (lincRNA) PVT1 is an overexpressed oncogene that is associated with AR in LNCaP prostate cancer cells, and with PRC2 in HeLa and many other types of cancer cells. The possible involvement of PVT1 in mediating androgen-induced gene expression downregulation in prostate cancer has not been explored.

METHODS

LNCaP cell line was used. Native RNA-binding-protein immunoprecipitation with anti-AR or anti-EZH2 was followed by RT-qPCR with primers for PVT1. Knockdown of PVT1 with specific GapmeRs (or a control with scrambled GapmeR) was followed by differentially expressed genes (DEGs) determination with Agilent microarrays and with Significance Analysis of Microarrays statistical test. DEGs were tested as a tumor risk classifier with a machine learning Random Forest algorithm run with gene expression data from all TCGA-PRAD (prostate adenocarcinoma) tumors as input. ChIP-qPCR was performed for histone marks at the promoter of one DEG.

RESULTS

We show that PVT1 knockdown in androgen-stimulated LNCaP cells caused statistically significant expression upregulation/downregulation of hundreds of genes. Interestingly, PVT1 knockdown caused upregulation of 160 genes that were repressed by androgen, including a significantly enriched set of tumor suppressor genes, and among them FAS, NOV/CCN3, BMF, HRK, IFIT2, AJUBA, DRAIC and TNFRSF21. A 121-gene-set (out of the 160) was able to correctly predict the classification of all 293 intermediate- and high-risk TCGA-PRAD tumors, with a mean ROC area under the curve AUC = 0.89 ± 0.04, pointing to the relevance of these genes in cancer aggressiveness. Native RIP-qPCR in LNCaP showed that PVT1 was associated with EZH2, a component of PRC2. PVT1 knockdown followed by ChIP-qPCR showed significant epigenetic remodeling at the enhancer and promoter regions of tumor suppressor gene NOV, one of the androgen-repressed genes that were upregulated upon PVT1 silencing.

CONCLUSIONS

Overall, we provide first evidence that PVT1 was involved in signaling a genome-wide androgen-dependent transcriptional repressive program of tumor suppressor protein-coding genes in prostate cancer cells. Identification of transcriptional inhibition of tumor suppressor genes by PVT1 highlights the pathway to the investigation of mechanisms that lie behind the oncogenic role of PVT1 in cancer. Video Abstract.

Analysis of putative cis-regulatory elements regulating blood pressure variation

Hundreds of loci have been associated with blood pressure (BP) traits from many genome-wide association studies. We identified an enrichment of these loci in aorta and tibial artery expression quantitative trait loci in our previous work in ~100 000 Genetic Epidemiology Research on Aging study participants. In the present study, we sought to fine-map known loci and identify novel genes by determining putative regulatory regions for these and other tissues relevant to BP. We constructed maps of putative cis-regulatory elements (CREs) using publicly available open chromatin data for the heart, aorta and tibial arteries, and multiple kidney cell types. Variants within these regions may be evaluated quantitatively for their tissue- or cell-type-specific regulatory impact using deltaSVM functional scores, as described in our previous work. We aggregate variants within these putative CREs within 50 Kb of the start or end of 'expressed' genes in these tissues or cell types using public expression data and use deltaSVM scores as weights in the group-wise sequence kernel association test to identify candidates. We test for association with both BP traits and expression within these tissues or cell types of interest and identify the candidates MTHFR, C10orf32, CSK, NOV, ULK4, SDCCAG8, SCAMP5, RPP25, HDGFRP3, VPS37B and PPCDC. Additionally, we examined two known QT interval genes, SCN5A and NOS1AP, in the Atherosclerosis Risk in Communities Study, as a positive control, and observed the expected heart-specific effect. Thus, our method identifies variants and genes for further functional testing using tissue- or cell-type-specific putative regulatory information.

Higher Serum CCN3 Is Associated with Disease Activity and Inflammatory Markers in Rheumatoid Arthritis

Nephroblastoma overexpressed protein (NOV/CCN3), the early discovered member of the CCN family, has recently been suggested to be involved in a number of inflammatory processes, including wound healing, alveolar epithelial cell inflammation, cancer metastasis, and macrophage foam cell formation. However, the role of CCN3 in rheumatoid arthritis (RA), a classic autoimmune and inflammatory disease, remains elusive. RA is a chronic systemic autoimmune disease that eventually leads to cartilage and bone destruction and joint dysfunction. In this study, we investigated the potential of serum CCN3 as a biomarker for RA. The serum levels of CCN3 were measured by ELISA. The clinical and laboratory parameters were collected from a clinical record system, and disease activity was determined by joint disease activity score 28 (DAS28). Our results showed that the serum levels of CCN3 were significantly increased in RA patients compared to healthy controls. Furthermore, the CCN3 level was positively correlated with DAS28 (CRP), DAS28 (ESR), and the level of anti-CCP Ab, an autoantibody highly specific for RA. Furthermore, CCN3 showed a positive correlation with inflammatory cytokine IL-6, while no significant correlation with TNF-α was observed. These data suggest that CCN3 plays an important role in the development of RA and might be a potential disease activity biomarker for RA.

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.

Systems-wide analysis unravels the new roles of CCM signal complex (CSC)

Cerebral cavernous malformations (CCMs) are characterized by abnormally dilated intracranial capillaries that result in increased susceptibility to stroke. Three genes have been identified as causes of CCMs; KRIT1 (CCM1), MGC4607 (CCM2) and PDCD10 (CCM3); one of them is disrupted in most CCM cases. It was demonstrated that both CCM1 and CCM3 bind to CCM2 to form a CCM signaling complex (CSC) to modulate angiogenesis. In this report, we deployed both RNA-seq and proteomic analysis of perturbed CSC after depletion of one of three CCM genes to generate interactomes for system-wide studies. Our results demonstrated a unique portrait detailing alterations in angiogenesis and vascular integrity. Interestingly, only in-direct overlapped alterations between RNA and protein levels were detected, supporting the existence of multiple layers of regulation in CSC cascades. Notably, this is the first report identifying that both β4 integrin and CAV1 signaling are downstream of CSC, conveying the angiogenic signaling. Our results provide a global view of signal transduction modulated by the CSC, identifies novel regulatory signaling networks and key cellular factors associated with CSC.

The Predictive Role of Tenascin-C and Cellular Communication Network Factor 3 (CCN3) in Post Hepatectomy Liver Failure in a Rat Model and 50 Patients Following Partial Hepatectomy

Background

Matricellular proteins of the extracellular matrix (ECM) include tenascin-C (TNC) and cellular communication network factor 3 (CCN3). This study aimed to investigate the role of TNC and CCN3 as prognostic factors for post hepatectomy liver failure (PHLF) in a rat model of partial hepatectomy and 50 patients following partial hepatectomy.

Material/Methods

Sprague-Dawley rats underwent 85% (n=53) or 90% hepatectomy (n=53) in the partial hepatectomy (PHx) model. TNC and CCN3 mRNA expression in residual liver tissue was evaluated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and enzyme-linked immunoassay (ELISA) determined the serum levels of TNC and CCN3. In 50 patients who underwent partial hepatectomy, TNC and CCN3 serum levels were measured on postoperative day 1 and day 3.

Results

In the rat partial hepatectomy model, mRNA and serum levels of TNC and CCN3 were significantly increased within the first 24 h, and were higher in the 90% PHx group compared with the 85% PHx group. Fifty patients who underwent partial hepatectomy, included patients with PHLF (n=12) and patients without PHLF (n=38). Multivariate analysis confirmed that serum levels on postoperative day 3 TNC^high+CCN3^high was a significant predictor of PHLF, which was associated with more than twice the risk of severe morbidity when compared with the low-risk patients (80% vs. 30%) and a significantly longer hospital stay (17 days vs. 8 days).

Conclusions

Further studies are needed to evaluate the potential role of the matricellular proteins, TNC and CCN3 as early clinical predictors for PHLF.

Imatinib independent aberrant methylation of NOV/CCN3 in chronic myelogenous leukemia patients: a mechanism upstream of BCR-ABL1 function?

Background

The NOV gene product, CCN3, has been reported in a diverse range of tumors to serve as a negative growth regulator, while acting as a tumor suppressor in Chronic Myelogenous Leukemia (CML). However, the precise mechanism of its silencing in CML is poorly understood. In the current study, we aimed to query if the gene regulation of CCN3 is mediated by the promoter methylation in the patients with CML. In addition, to clarify whether the epigenetic silencing is affected by BCR-ABL1 inhibition, we assessed the methylation status in the patients at different time intervals following the tyrosine kinase inhibition using imatinib therapy, as the first-line treatment for this type of leukemia.

Methods

To address this issue, we applied bisulfite-sequencing technique as a high-resolution method to study the regulatory segment of the CCN3 gene. The results were analyzed in newly diagnosed CML patients as well as following imatinib therapy. We also evaluated the correlation of CCN3 promoter methylation with BCR-ABL1 levels.

Results

Our findings revealed that the methylation occurs frequently in the promoter region of CML patients showing a significant increase of the methylated percentage at the CpG sites compared to normal individuals. Interestingly, this hypermethylation was indicated to be independent of BCR-ABL1 titers in both groups, which might suggest a mechanism beyond the BCR-ABL1 function.

Conclusion

Despite suggesting that the CCN3 hypermethylation acts as a molecular mechanism independent of BCR-ABL1 function in CML patients, this scenario requires further validation by complementary experiments. In the case of acting upstream of BCR-ABL1 signaling, the methylation marker can provide early detection and a novel platform for targeted epigenetic modifiers for efficient treatment in imatinib resistant patients.

Role of the CCN protein family in cancer

The CCN protein family is composed of six matricellular proteins, which serve regulatory roles rather than structural roles in the extracellular matrix. First identified as secreted proteins which are induced by oncogenes, the acronym CCN came from the names of the first three members: CYR61, CTGF, and NOV. All six members of the CCN family consist of four cysteine-rich modular domains. CCN proteins are known to regulate cell adhesion, proliferation, differentiation, and apoptosis. In addition, CCN proteins are associated with cardiovascular and skeletal development, injury repair, inflammation, and cancer. They function either through binding to integrin receptors or by regulating the expression and activity of growth factors and cytokines. Given their diverse roles related to the pathology of certain diseases such as fibrosis, arthritis, atherosclerosis, diabetic nephropathy, retinopathy, and cancer, there are many emerging studies targeting CCN protein signaling pathways in attempts to elucidate their potentials as therapeutic targets. [BMB Reports 2018; 51(10): 486-493].

CCN3 and DLL1 co-regulate osteogenic differentiation of mouse embryonic fibroblasts in a Hey1-dependent manner

Notch signaling pathway is one of the most important pathways to regulate intercellular signal transduction and is crucial in the regulation of bone regeneration. Nephroblastoma overexpressed (NOV or CCN3) serves as a non-canonical secreted ligand of Notch signaling pathway and its role in the process of osteogenic differentiation of mesenchymal stem cells (MSCs) was undefined. Here we conducted a comprehensive study on this issue. In vivo and in vitro studies have shown that CCN3 significantly inhibited the early and late osteogenic differentiation of mouse embryonic fibroblasts (MEFs), the expression of osteogenesis-related factors, and the subcutaneous ectopic osteogenesis of MEFs in nude mice. In mechanism studies, we found that CCN3 significantly inhibited the expression of BMP9 and the activation of BMP/Smad and BMP/MAPK signaling pathways. There was also a mutual inhibition between CCN3 and DLL1, one of the classic membrane protein ligands of Notch signaling pathway. Additionally, we further found that Hey1, the target gene shared by BMP and Notch signaling pathways, partially reversed the inhibitory effect of CCN3 on osteoblastic differentiation of MEFs. In summary, our findings suggested that CCN3 significantly inhibited the osteogenic differentiation of MEFs. The inhibitory effect of CCN3 was mainly through the inhibition of BMP signaling and the mutual inhibition with DLL1, so as to inhibit the expression of Hey1, the target gene shared by BMP and Notch signaling pathways.

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.

Regulation and bioactivity of the CCN family of genes and proteins in obesity and diabetes

Across the years the CCNs have been increasingly implicated in the development of obesity, diabetes and its complications. Evidence for this is currently derived from their dysregulation in key metabolic pathological states in humans, animal and in vitro models, and also pre-clinical effects of their bioactivities. CCN2 is the best studied in this disease process and the other CCNs are yet to be better defined. Key steps where CCNs may play a pathogenic metabolic role include: (i) obesity and insulin resistance, where CCN2 inhibits fat cell differentiation in vitro and CCN3 may induce obesity and insulin resistance; (ii) elevated blood glucose levels to diabetes mellitus onset, where CCN2 may contribute to pancreatic beta cell and islet function; and (iii) in diabetes complications, such as nephropathy, retinopathy, liver disease (NAFLD/NASH), CVD and diabetes with heart failure. In contrast, CCN1, CCN2 and possibly CCN3, may have a reparative role in wound healing in diabetes, and CCN2 in islet cell development. In terms of CCN2 regulation by a diabetes metabolic environment and related mechanisms, the author's laboratory and others have progressively shown that advanced glycation-end products, protein kinase C isoforms, saturated fatty acids, reactive oxygen species and haemodynamic factors upregulate CCN2 in relevant cell and animal systems. Recent data has suggested that CCN2, CCN3 and CCN6 may affect energy homeostasis including in regulating glycolysis and mitochondrial function. This paper will address the current data implicating CCNs in diabetes and its complications, focusing on recent aspects with translational clinical relevance and future directions.

CCN3 suppresses TGF-β1-induced extracellular matrix accumulation in human mesangial cells in vitro

Glomerular sclerosis is characterized by mesangial cell proliferation and progressive extracellular matrix (ECM) accumulation. CCN3 belongs to the CCN family of matrix proteins; increasing evidence suggests that CCN3 is an endogenous negative regulator of the ECM and fibrosis. However, the exact role of CCN3 in the accumulation of ECM remains unknown. The aim of the present study was to investigate the effects of CCN3 on TGF-β1-induced production of ECM in human mesangial cells (HMCs) in vitro. Treatment with TGF-β1 (0.5-2.0 ng/mL) suppressed the mRNA and protein expression of CCN3 in HMCs in dose- and time-dependent manners. Furthermore, treatment with TGF-β1 significantly increased the expression of the two markers of renal fibrosis, fibronectin (FN) and type I collagen (COLI), in HMCs. Moreover, treatment with TGF-β1 significantly decreased the expression of metalloproteinase (MMP)-2 and MMP-9, and markedly increased the expression of tissue inhibitor of metalloproteinase (TIMP)-1 in HMCs. Pretreatment of HMCs with exogenous CCN3 (5-500 ng/mL) or overexpression of CCN3 significantly attenuated TGF-β1-induced changes in FN, COLI, MMP-2, MMP-9 and TIMP-1 in HMCs. These results suggest that CCN3 suppresses TGF-β1-induced accumulation of ECM in HMCs. CCN3 may have potential as a novel therapeutic target for alleviating glomerulosclerosis.

The matricellular protein CCN6 (WISP3) decreases Notch1 and suppresses breast cancer initiating cells

Increasing evidence supports that the epithelial to mesenchymal transition (EMT) in breast cancer cells generates tumor initiating cells (TICs) but the contribution of the tumor microenvironment to these programs needs further elucidation. CCN6 (WISP3) is a secreted matrix-associated protein (36.9 kDa) of the CCN family (named after CTGF, Cyr61 and Nov) that is reduced or lost in invasive carcinomas of the breast with lymph node metastasis and in inflammatory breast cancer. CCN6 exerts breast cancer growth and invasion inhibitory functions, but the mechanisms remain to be defined. In the present study we discovered that ectopic CCN6 overexpression in triple negative (TN) breast cancer cells and in cells derived from patients is sufficient to induce a mesenchymal to epithelial transition (MET) and to reduce TICs. In vivo, CCN6 overexpression in the TIC population of MDA-MB-231 cells delayed tumor initiation, reduced tumor volume, and inhibited the development of metastasis. Our studies reveal a novel CCN6/Slug signaling axis that regulates Notch1 signaling activation, epithelial cell phenotype and breast TICs, which requires the conserved thrombospondin type 1 (TSP1) motif of CCN6. The relevance of these data to human breast cancer is highlighted by the finding that CCN6 protein levels are inversely correlated with Notch1 intracellular activated form (NICD1) in 69.5% of invasive breast carcinomas. These results demonstrate that CCN6 regulates epithelial and mesenchymal states transition and TIC programs, and pinpoint one responsible mechanism.

CCN3 Expression Marks a Sulfomucin-nonproducing Unique Subset of Colonic Goblet Cells in Mice

Intestinal goblet cells are characterized by their unique morphology and specialized function to secrete mucins. Although it is known that they are a heterogeneous population of cells, there have been few studies that relate the expression of a particular gene with functionally distinct subpopulations of intestinal goblet cells. Here we show that CCN3, a gene encoding a member of the CCN family proteins, is induced by inhibition of Notch signaling in colonic epithelial cells and expressed in goblet cells in mice. We demonstrate that CCN3 expression is confined to a subpopulation of goblet cells in the lower crypt of the proximal and middle colon. In addition, CCN3+ cells in the colon correlate well with the cells that are positive for alcian blue (AB) staining but negative for high-iron diamine (HID) staining in histology. We also show that CCN3+ cells, which are absent in the normal distal colon, transiently and ectopically emerge in regenerating crypts during the repair phase of DSS-induced colitis model. Our study thus suggests that CCN3 labels a unique subpopulation of sulfomucin-nonproducing colonic goblet cells that function in both normal and diseased colonic epithelia.

Functional dissection of astrocyte-secreted proteins: Implications in brain health and diseases

Astrocytes, which are homeostatic cells of the central nervous system (CNS), display remarkable heterogeneity in their morphology and function. Besides their physical and metabolic support to neurons, astrocytes modulate the blood-brain barrier, regulate CNS synaptogenesis, guide axon pathfinding, maintain brain homeostasis, affect neuronal development and plasticity, and contribute to diverse neuropathologies via secreted proteins. The identification of astrocytic proteome and secretome profiles has provided new insights into the maintenance of neuronal health and survival, the pathogenesis of brain injury, and neurodegeneration. Recent advances in proteomics research have provided an excellent catalog of astrocyte-secreted proteins. This review categorizes astrocyte-secreted proteins and discusses evidence that astrocytes play a crucial role in neuronal activity and brain function. An in-depth understanding of astrocyte-secreted proteins and their pathways is pivotal for the development of novel strategies for restoring brain homeostasis, limiting brain injury/inflammation, counteracting neurodegeneration, and obtaining functional recovery.

Periostin is required for matricellular localization of CCN3 in periodontal ligament of mice

CCN3 is a matricellular protein that belongs to the CCN family. CCN3 consists of 4 domains: insulin-like growth factor-binding protein-like domain (IGFBP), von Willebrand type C-like domain (VWC), thrombospondin type 1-like domain (TSP1), and the C-terminal domain (CT) having a cysteine knot motif. Periostin is a secretory protein that binds to extracellular matrix proteins such as fibronectin and collagen. In this study, we found that CCN3 interacted with periostin. Immunoprecipitation analysis revealed that the TSP1-CT interacted with the 4 repeats of the Fas 1 domain of periostin. Immunofluorescence analysis showed co-localization of CCN3 and periostin in the periodontal ligament of mice. In addition, targeted disruption of the periostin gene in mice decreased the matricellular localization of CCN3 in the periodontal ligament. Thus, these results indicate that periostin was required for the matricellular localization of CCN3 in the periodontal ligament, suggesting that periostin mediated an interaction between CCN3 and the extracellular matrix.

Renal Fibrosis mRNA Classifier: Validation in Experimental Lithium-Induced Interstitial Fibrosis in the Rat Kidney

Accurate diagnosis of fibrosis is of paramount clinical importance. A human fibrosis classifier based on metzincins and related genes (MARGS) was described previously. In this investigation, expression changes of MARGS genes were explored and evaluated to examine whether the MARGS-based algorithm has any diagnostic value in a rat model of lithium nephropathy. Male Wistar rats (n = 12) were divided into 2 groups (n = 6). One group was given a diet containing lithium (40 mmol/kg food for 7 days, followed by 60mmol/kg food for the rest of the experimental period), while a control group (n = 6) was fed a normal diet. After six months, animals were sacrificed and the renal cortex and medulla of both kidneys removed for analysis. Gene expression changes were analysed using 24 GeneChip^® Affymetrix Rat Exon 1.0 ST arrays. Statistically relevant genes (p-value<0.05, fold change>1.5, t-test) were further examined. Matrix metalloproteinase-2 (MMP2), CD44, and nephroblastoma overexpressed gene (NOV) were overexpressed in the medulla and cortex of lithium-fed rats compared to the control group. TGFβ2 was overrepresented in the cortex of lithium-fed animals 1.5-fold, and 1.3-fold in the medulla of the same animals. In Gene Set Enrichment Analysis (GSEA), both the medulla and cortex of lithium-fed animals showed an enrichment of the MARGS, TGFβ network, and extracellular matrix (ECM) gene sets, while the cortex expression signature was enriched in additional fibrosis-related-genes and the medulla was also enriched in immune response pathways. Importantly, the MARGS-based fibrosis classifier was able to classify all samples correctly. Immunohistochemistry and qPCR confirmed the up-regulation of NOV, CD44, and TGFβ2. The MARGS classifier represents a cross-organ and cross-species classifier of fibrotic conditions and may help to design a test to diagnose and to monitor fibrosis. The results also provide evidence for a common pathway in the pathogenesis of fibrosis.

NOV/CCN3: A New Adipocytokine Involved in Obesity-Associated Insulin Resistance

Identification of new adipokines that potentially link obesity to insulin resistance represents a major challenge. We recently showed that NOV/CCN3, a multifunctional matricellular protein, is synthesized and secreted by adipose tissue, with plasma levels highly correlated with BMI. NOV involvement in tissue repair, fibrotic and inflammatory diseases, and cancer has been previously reported. However, its role in energy homeostasis remains unknown. We investigated the metabolic phenotype of NOV(-/-) mice fed a standard or high-fat diet (HFD). Strikingly, the weight of NOV(-/-) mice was markedly lower than that of wild-type mice but only on an HFD. This was related to a significant decrease in fat mass associated with an increased proportion of smaller adipocytes and to a higher expression of genes involved in energy expenditure. NOV(-/-) mice fed an HFD displayed improved glucose tolerance and insulin sensitivity. Interestingly, the absence of NOV was associated with a change in macrophages profile (M1-like to M2-like), in a marked decrease in adipose tissue expression of several proinflammatory cytokines and chemokines, and in enhanced insulin signaling. Conversely, NOV treatment of adipocytes increased chemokine expression. Altogether, these results show that NOV is a new adipocytokine that could be involved in obesity-associated insulin-resistance.

MAGP2 controls Notch via interactions with RGD binding integrins: Identification of a novel ECM-integrin-Notch signaling axis

Canonical Notch signaling involves Notch receptor activation via interaction with cell surface bound Notch ligand. Recent findings also indicate that Notch signaling may be modulated by cross-talk with other signaling mechanisms. The ECM protein MAGP2 was previously shown to regulate Notch in a cell type dependent manner, although the molecular details of this interaction have not been dissected. Here, we report that MAGP2 cell type specific control of Notch is independent of individual Notch receptor-ligand combinations but dependent on interaction with RGD binding integrins. Overexpressed MAGP2 was found to suppress transcriptional activity from the Notch responsive Hes1 promoter activity in endothelial cells, while overexpression of a RGD→RGE MAGP2 mutant increased Notch signaling in the same cell type. This effect was not unique to MAGP2 since the RGD domain of the ECM protein EGFL7 was also found to be an important modulator of Hes1 promoter activity. Independently of MAGP2 or EGFL7, inhibition of RGD-binding integrins with soluble RGD peptides also increased accumulation of active N1ICD fragments and Notch responsive promoter activity independently of changes in Notch1, Jag1, or Dll4 expression. Finally, β1 or β3 integrin blocking antibodies also enhanced Notch signaling. Collectively, these results answer the question of how MAGP2 controls cell type dependent Notch signaling, but more importantly uncover a new mechanism to understand how extracellular matrices and cellular environments impact Notch signaling.

Targeted mutation of NOV/CCN3 in mice disrupts joint homeostasis and causes osteoarthritis-like disease

OBJECTIVE

The matricellular protein NOV/CCN3, is implicated in osteoarthritis (OA) and targeted mutation of NOV in mice (Nov(del3)) leads to joint abnormalities. This investigation tested whether NOV is required for joint homeostasis and if its disruption causes joint degeneration.

METHOD

NOV expression in the adult mouse joint was characterized by immunohistochemistry. A detailed comparison of the joints of Nov(del3)-/- and Nov(del3)+/+ (wild-type) males and females at 2, 6 and 12 months of age was determined by X-ray, histology and immunohistochemistry.

RESULTS

NOV protein was found in specific cells in articular cartilage, meniscus, synovium and ligament attachment sites in adult knees. Nov(del3)-/- males exhibited severe OA-like pathology at 12 months (OARSI score 5.0 ± 0.5, P < 0.001), affecting all tissues of the joint: erosion of the articular cartilage, meniscal enlargement, osteophytic outgrowths, ligament degeneration and expansion of fibrocartilage. Subchondral sclerosis and changes in extracellular matrix composition consistent with OA, were also seen. The density of articular cartilage cells in Nov(del3)+/+ knee joints is maintained at a constant level from 2 to 12 months of age whereas this is not the case in Nov(del3)-/- mice. Compared with age and sex-matched Nov(del3)+/+ mice, a significant increase in articular cartilage density was seen in Nov(del3)-/- males at 2 months, whereas a significant decrease was seen at 6 and 12 months in both Nov(del3)-/- males and females.

CONCLUSION

NOV is required for the maintenance of articular cartilage and for joint homeostasis, with disruption of NOV in ageing Nov(del3)-/- male mice causing OA-like disease.

Expansion of melanoma-specific lymphocytes in alternate gamma chain cytokines: gene expression variances between T cells and T-cell subsets exposed to IL-2 versus IL-7/15

We have previously demonstrated that expansion of activated tumor-sensitized T cells in interleukin (IL)-7/15 results in greater expansion and anti-tumor activity than expansion in IL-2. We sought to determine whether T cells exposed to IL-2 versus IL-7/15 exhibited distinct gene expression patterns. Lymphocytes were harvested from Pmel-1 mice immunized with B16-GMCSF melanoma cells, activated in vitro, and cultured in IL-2 or IL-7/15 for 1, 3 or 6 days. T cells were harvested and analyzed by microarray, real-time quantitative polymerase chain reaction (RT-QPCR), or sorted into T cell subsets and analyzed. We found significant differences in gene expression for T cells cultured in IL-2 vs. IL-7/15, starting at day 3. This was not a function of subset differentiation; when T cell were divided into subsets, the central memory (T_CM), effector memory (T_EM) and effector (T_E) T cells cultured in the IL-2 more closely resembled each other than the identical phenotypic subset exposed to IL-7/15. Thus, the differences in gene expression induced by culture in IL-2 versus IL-7/15 do not merely reflect differences in frequency of T_CM vs. T_EM vs. T_E cells, but rather reflect that the gene expression of those T cell subsets when exposed to different cytokines are fundamentally different.

Wnt5a-induced Wnt1-inducible secreted protein-1 suppresses vascular smooth muscle cell apoptosis induced by oxidative stress

OBJECTIVE

Apoptosis of vascular smooth muscle cells (VSMCs) contributes to thinning and rupture of the atherosclerotic plaque fibrous cap and is thereby associated with myocardial infarction. Wnt protein activation of β-catenin regulates numerous genes that are associated with cell survival. We therefore investigated Wnt/β-catenin survival signaling in VSMCs and assessed the presence of this pathway in human atherosclerotic plaques at various stages of the disease process.

APPROACH AND RESULTS

Wnt5a induced β-catenin/T-cell factor signaling and retarded oxidative stress (H₂O₂)-induced apoptosis in mouse aortic VSMCs. Quantification of mRNA levels revealed a >4-fold (P<0.05; n=9) increase in the expression of the Wnt/β-catenin responsive gene, Wnt1-inducible secreted protein-1 (WISP-1), which was dependent on cAMP response element-binding protein and sustained in the presence of H₂O₂. Exogenous WISP-1 significantly reduced H₂O₂-induced apoptosis by 43% (P<0.05; n=3) and was shown using silencing small interfering RNA, to be important for Wnt5a-dependent survival responses to H₂O₂ (P<0.05; n=3). WISP-1 protein levels were significantly lower (≈50%) in unstable atherosclerosis compared with stable plaques (n=11 and n=14).

CONCLUSIONS

These results indicate for the first time that Wnt5a induces β-catenin survival signaling in VSMCs via WISP-1. The deficiency of the novel survival factor, WISP-1 in intimal VSMCs of unstable coronary plaques, suggests that there is altered Wnt/β-catenin/ T-cell factor signaling with progressive atherosclerosis, and restoration of WISP-1 protein might be an effective stabilization factor for vulnerable atherosclerotic plaques.

Revisiting the matricellular concept

The concept of a matricellular protein was first proposed by Paul Bornstein in the mid-1990s to account for the non-lethal phenotypes of mice with inactivated genes encoding thrombospondin-1, tenascin-C, or SPARC. It was also recognized that these extracellular matrix proteins were primarily counter or de-adhesive. This review reappraises the matricellular concept after nearly two decades of continuous investigation. The expanded matricellular family as well as the diverse and often unexpected functions, cellular location, and interacting partners/receptors of matricellular proteins are considered. Development of therapeutic strategies that target matricellular proteins are discussed in the context of pathology and regenerative medicine.

Nov/CCN3 regulates long-term repopulating activity of murine hematopoietic stem cells via integrin αvβ3

Throughout life, hematopoietic stem cells (HSCs) sustain the blood cell supply through their capacities for self-renewal and multilineage differentiation. These processes are regulated within a specialized microenvironment termed the 'niche'. Here, we show a novel mechanism for regulating HSC function that is mediated by nephroblastoma overexpressed (Nov/CCN3), a matricellular protein member of the CCN family. We found that Nov contributes to the maintenance of long-term repopulating (LTR) activity through association with integrin αvβ3 on HSCs. The resultant β3 integrin outside-in signaling is dependent on thrombopoietin (TPO), a crucial cytokine involved in HSC maintenance. TPO was required for Nov binding to integrin αvβ3, and stimulated Nov expression in HSCs. However, in the presence of IFNγ, a cytokine known to impair HSC function, not only was TPO-induced expression of Nov suppressed, but the LTR activity was conversely impaired by TPO-mediated ligation of integrin αvβ3 with exogenous ligands, including Nov, as well. Thus, Nov/integrin αvβ3-mediated maintenance of HSCs appears to be modulated by simultaneous stimulation by other cytokines. Our finding suggests that this system contributes to the regulation of HSCs within the bone marrow niche.

The matricellular protein CCN5 regulates podosome function via interaction with integrin αvβ 3

CCN proteins play crucial roles in cell motility, matrix turnover, and proliferation. In particular, CCN5 plays a role in cell motility and proliferation in several cell types; however, no functional binding proteins for CCN5 have been identified. In this study we report that CCN5 binds to the cell surface receptor integrin αvβ3 in vascular smooth muscle cells. Furthermore, this interaction takes place in podosomes, organelles known to degrade matrix and mediate motility. We show that CCN5 regulates the ability of podosomes to degrade matrix, but does not affect podosome formation. The level of CCN5 present in a podosome negatively correlates with its ability to degrade matrix. Conversely, knockdown of CCN5 greatly enhances the matrix-degrading ability of podosomes. These findings suggest that the antimotility effects of CCN5 may be mediated through the direct interaction of CCN5 and integrin αvβ3 in podosomes and the concomitant suppression of matrix degradation that is required for cell migration.

Promotion of dentin regeneration via CCN3 modulation on Notch and BMP signaling pathways

Dentin regeneration remains a great challenge in clinic. Dental pulp stem cells (DPSCs) actively contribute to dentinogenesis, which is orchestrated by a spectrum of signaling factors. However, the exact mechanism underlying the reparative dentin regeneration process is largely unknown and the application of DPSCs in the repair of dentin defect is thus limited. Here, using a rat reparative dentin regeneration model, we observed that DPSCs underwent a proliferation phase followed by a differentiation phase after dental injury. A transient elevation of nephroblastoma overexpressed (NOV, or CCN3) expression correlated with this progressive dental tissue restoration process. Further studies revealed that over-expression of CCN3 promoted human DPSCs proliferation via activation of Notch. Moreover, using cocultured cells (DPSCs/CCN3 and DPSCs) in vitro and the cocultured cells-poly (lactic-co-glycolic acid) (PLGA) scaffold complex in vivo, we demonstrated that CCN3 was capable of promoting mineralization in a non-cell autonomous manner through promoting secretion of BMP2. CCN3 can promote dentinogenesis by coordinating proliferation and odontoblastic differentiation of DPSCs via modulating Notch and BMP2 signaling pathways and CCN3 is a promising therapeutic target in dentin tissue engineering.

Overexpression of periostin predicts poor prognosis in non-small cell lung cancer

The periostin protein, encoded by the POSTN gene, is a component of the extracellular matrix, which is expressed by fibroblasts and has been observed in a variety of human malignancies. The present study aimed to detect the expression of periostin in the tissues of non-small cell lung cancer (NSCLC) patients and benign lung tumors, and to correlate the results with the clinicopathological data of the subjects, in order to evaluate periostin as a potential prognostic marker. In total, 49 NSCLC patients and 6 benign lung tumors were included in this study. The protein level of periostin was detected in paired normal/paratumor/cancer tissues by a western blot analysis and the mRNA level in paired normal/cancer tissues was detected by quantitative polymerase chain reaction (qPCR). The results were then correlated with established biological and prognostic factors. Immunohistochemistry was used to confirm the location of periostin in the NSCLC tissues. Uni- and multivariate analyses were performed using Cox's proportional hazards regression model. The protein level of periostin was elevated in the cancer tissue of the NSCLC patients compared with the normal (P=0.017) and paratumor (P=0.000) tissues. The expression level in the male patients was much higher than in the female patients at the protein (P=0.001) and mRNA (P=0.010) levels. The mRNA level in the non-adenocarcinoma (non-ADC) patients was much higher than in the adenocarcinoma (ADC) patients (P=0.029). Periostin was demonstrated higher expression at the protein level in the pseudotumors and tuberculosis patients than in the adjacent (P=0.016) and surrounding tissues (P=0.001). Immunostaining indicated that high levels of periostin were present in the mesenchymal areas, but not in the cancer cells themselves. The patients with tumors exhibiting high-level periostin expression showed a significantly shorter survival time (P=0.036, log-rank test). The 3-year survival rate was 81.5% for patients with low-level periostin expression (periostin-L; n=27) and 45.4% for patients with high-level periostin expression (periostin-H; n=22). Similarly, pathological node (pN) status was a significant prognostic marker in the univariate Cox survival analysis. Notably, periostin-H expression was also identified as an independent prognostic factor by the multivariate analysis (P=0.011). These results showed that the overexpression of periostin predicts a poor prognosis, therefore it may be regarded as a novel molecule in the progression and development of NSCLC. The results provide an additional target for the adjuvant treatment of NSCLC.

CCN3 protein participates in bone regeneration as an inhibitory factor

CCN3, a member of the CCN protein family, inhibits osteoblast differentiation in vitro. However, the role of CCN3 in bone regeneration has not been well elucidated. In this study, we investigated the role of CCN3 in bone regeneration. We identified the Ccn3 gene by microarray analysis as a highly expressed gene at the early phase of bone regeneration in a mouse bone regeneration model. We confirmed the up-regulation of Ccn3 at the early phase of bone regeneration by RT-PCR, Western blot, and immunofluorescence analyses. Ccn3 transgenic mice, in which Ccn3 expression was driven by 2.3-kb Col1a1 promoter, showed osteopenia compared with wild-type mice, but Ccn3 knock-out mice showed no skeletal changes compared with wild-type mice. We analyzed the bone regeneration process in Ccn3 transgenic mice and Ccn3 knock-out mice by microcomputed tomography and histological analyses. Bone regeneration in Ccn3 knock-out mice was accelerated compared with that in wild-type mice. The mRNA expression levels of osteoblast-related genes (Runx2, Sp7, Col1a1, Alpl, and Bglap) in Ccn3 knock-out mice were up-regulated earlier than those in wild-type mice, as demonstrated by RT-PCR. Bone regeneration in Ccn3 transgenic mice showed no significant changes compared with that in wild-type mice. Phosphorylation of Smad1/5 was highly up-regulated at bone regeneration sites in Ccn3 KO mice compared with wild-type mice. These results indicate that CCN3 is up-regulated in the early phase of bone regeneration and acts as a negative regulator for bone regeneration. This study may contribute to the development of new strategies for bone regeneration therapy.

CCN3 regulates proliferation and migration properties in Jeg3 trophoblast cells via ERK1/2, Akt and Notch signalling

Previous studies showed that CCN3 is deregulated in early-onset pre-eclampsia (PE), a pregnancy disease associated with impaired trophoblast invasion, which leads to reduced fetal oxygen and nutrition support. Recently, we identified the glycosylated (g-CCN3) and the non-glycosylated (ng-CCN3) form of matricellular CCN3 as key factors in regulation of trophoblast proliferation and invasion. While Jeg3 cells revealed a decreased proliferation upon stimulation with both forms of CCN3, enhanced migration and invasion properties were only found for ng-CCN3. Here, we focused on the signalling cascades mitogen-activated protein kinase (MAPK), PI3 kinase/Akt and Notch/p21 for mediating the dual function of CCN3 on trophoblast proliferation versus migration in Jeg3 cells upon stimulation with g- and ng-recombinant CCN3 (g/ng-rCCN3). Analysis of the CCN3-mediated signalling pathways showed that ng-rCCN3 stimulated migration properties by activating the Akt as well as the MAPK pathway. Moreover, cell migration stimulated by ng-rCCN3 was mediated via Akt and integrin α5β1 but not the antiproliferative effect of CCN3. There was evidence that the Notch pathway might contribute to the antiproliferative properties of both forms of CCN3 by an increase in Notch1 expression and its target gene, the cell cycle inhibitor p21. Our data showed that the presence of both forms of CCN3 is accompanied by a balance of trophoblast proliferation and migration/invasion properties, which are triggered by different signalling pathways. Thus, a deregulated expression of g/ng-CCN3 could lead to an imbalance in proliferation versus invasion, and might contribute to the shallow trophoblast invasion observed in PE.

Temporal and spatial expression of CCN3 during retina development

NOV/CCN3 is one of the founding members of the CCN (Cyr61 CTGF NOV) family. In the avian retina, CCN3 expression is mostly located within the central region of the inner nuclear layer. As retinal development progresses and this retinal layer differentiates and matures, CCN3 expression forms a dorsal-ventral and a central-peripheral gradient. CCN3 is produced by two glial cell types, peripapillary cells and Müller cells, as well as by horizontal, amacrine, and bipolar interneurons. In retinal neurons and Müller cell cultures, CCN3 expression is induced by activated BMP signaling, whereas Notch signaling decreases CCN3 mRNA and protein levels in Müller cells and has no effect in retinal neurons. In Müller cells, the CCN3 expression detected may thus result from a balance between the Notch and BMP signaling pathways.

Study of CCN3 (NOV) and DDR1 in normal melanocytes and vitiligo skin

We have hypothesised that melanocytes disappear in vitiligo because they are weakly attached to the epidermal basal membrane (melanocytorrhagy). In the epidermis, attachment of melanocytes to collagen IV is mediated through DDR1, which is under the control of CCN3. DDR1 genetic variants have been associated with vitiligo in patients of different ethnic origin. In vitro studies have shown that inhibition of CCN3 induces the detachment of melanocytes. We have studied in parallel the expression of CCN3 and DDR1 in lesional and perilesional skin of patients with vitiligo and the impact of the silencing of CCN3 and DDR1 in normal human melanocytes on their behaviour in epidermal reconstructs. Our in vivo study provides evidence of a dysregulation of the DDR1-CCN3 interaction in vitiligo skin as melanocytes remaining in perilesional skin did not express CCN3. Expression of DDR1 was decreased in lesional versus perilesional vitiligo skin in the majority of patients, and the expression of collagen IV was found decreased in all patients. Silencing of CCN3 in melanocytes induced a significant inhibition of cell adhesion to collagen IV whereas melanocytes transduced with shDDR1 still adhered well on collagen IV and did not increase melanocyte loss in epidermal reconstructs as compared with normal melanocytes. Melanocyte detachment was observed but not in all reconstructs using CCN3 silenced melanocytes. Overall, our study confirms that a downregulation of CCN3 is implicated in melanocyte adhesion in part through DDR1. In vitiligo skin, the interaction of CCN3 with other molecules, such as TGFβ and CCN2, needs to be addressed.