Tenascin-C in fibrosis in multiple organs: Translational implications.

Systemic sclerosis (SSc, scleroderma) is a complex disease with a pathogenic triad of autoimmunity, vasculopathy, and fibrosis involving the skin and multiple internal organs [1]. Because fibrosis accounts for as much as 45% of all deaths worldwide and appears to be increasing in prevalence [2], understanding its pathogenesis and progression is an urgent scientific challenge. Fibroblasts and myofibroblasts are the key effector cells executing physiologic tissue repair on one hand, and pathological fibrogenesis leading to chronic fibrosing conditions on the other. Recent studies identify innate immune signaling via toll-like receptors (TLRs) as a key driver of persistent fibrotic response in SSc. Repeated injury triggers the in-situ generation of "damage-associated molecular patterns" (DAMPs) or danger signals. Sensing of these danger signals by TLR4 on resident cells elicits potent stimulatory effects on fibrotic gene expression and myofibroblast differentiation triggering the self-limited tissue repair response to self-sustained pathological fibrosis characteristic of SSc. Our unbiased survey for DAMPs associated with SSc identified extracellular matrix glycoprotein tenascin-C as one of the most highly up-regulated ECM proteins in SSc skin and lung biopsies [3,4]. Furthermore, tenascin C is responsible for driving sustained fibroblasts activation, thereby progression of fibrosis [3]. This review summarizes recent studies examining the regulation and complex functional role of tenascin C, presenting tenascin-TLR4 axis in pathological fibrosis, and novel anti-fibrotic approaches targeting their signaling.

Tenascin-C-EGFR activation induces functional human satellite cell proliferation and promotes wound-healing of skeletal muscles via oleanic acid.

Human satellite cells (HuSCs) have been deemed to be the potential cure to treat muscular atrophy diseases such as Duchenne muscular dystrophy. However, the clinical trials of HuSCs were restricted to the inadequacy of donors because of that freshly isolated HuSCs quickly lost the Pax7 expression and myogenesis capacity in vivo after a few days of culture. Here we found that oleanic acid, a kind of triterpenoid endowed with diverse biological functions with treatment potential, could efficiently promote HuSCs proliferation. The HuSCs cultured in the medium supplement with oleanic acid could maintain a high expression level of Pax7 and retain the ability to differentiate into myotubes as well as facilitate muscle regeneration in injured muscles of recipient mice. We further revealed that Tenascin-C acts as the core mechanism to activate the EGFR signaling pathway followed by HuSCs proliferation. Taken together, our data provide an efficient method to expand functional HuSCs and a novel mechanism that controls HuSCs proliferation, which sheds light on the HuSCs-based therapy to treat muscle diseases.

Tenascin-C-enriched regeneration-specific extracellular matrix guarantees superior muscle regeneration in Ambystoma mexicanum.

Severe muscle injury causes distress and difficulty in humans. Studying the high regenerative ability of the axolotls may provide hints for the development of an effective treatment for severe injuries to muscle tissue. Here, we examined the regenerative process in response to a muscle injury in axolotls. We found that axolotls are capable of complete regeneration in response to a partial muscle resection called volumetric muscle loss (VML), which mammals cannot perfectly regenerate. We investigated the mechanisms underlying this high regenerative capacity in response to VML, focusing on the migration of muscle satellite cells and the extracellular matrix (ECM) formed during VML injury. Axolotls form tenascin-C (TN-C)-enriched ECM after VML injury. This TN-C-enriched ECM promotes the satellite cell migration. We confirmed the importance of TN-C in successful axolotl muscle regeneration by creating TN-C mutant animals. Our results suggest that the maintenance of a TN-C-enriched ECM environment after muscle injury promotes the release of muscle satellite cells and supports eventually high muscle regenerative capacity. In the future, better muscle regeneration may be achieved in mammals through the maintenance of TN-C expression.

Advances on the roles of tenascin-C in cancer.

The roles of the extracellular matrix molecule tenascin-C (TNC) in health and disease have been extensively reviewed since its discovery over 40 years ago. Here, we will describe recent insights into the roles of TNC in tumorigenesis, angiogenesis, immunity and metastasis. In addition to high levels of expression in tumors, and during chronic inflammation, and bacterial and viral infection, TNC is also expressed in lymphoid organs. This supports potential roles for TNC in immunity control. Advances using murine models with engineered TNC levels were instrumental in the discovery of important functions of TNC as a danger-associated molecular pattern (DAMP) molecule in tissue repair and revealed multiple TNC actions in tumor progression. TNC acts through distinct mechanisms on many different cell types with immune cells coming into focus as important targets of TNC in cancer. We will describe how this knowledge could be exploited for cancer disease management, in particular for immune (checkpoint) therapies.

Tenascin-C promotes endochondral ossification and fracture healing through Hedgehog and Hippo signaling.

Fractures are frequent and severe musculoskeletal injuries. This study aimed to investigate the function of tenascin-C (TNC) in regulating chondrogenic during fracture healing and elucidate the underlying molecular mechanisms. A well-established femur fracture model in male C57BL/6J mice was used to transect the middle diaphysis of the femur. To identify the essential role of TNC, shTNC lentiviruses or TNC protein were administered in the animal model. Micro-CT analysis, histologic analysis, immunostaining assays, and gene expression analysis were employed to investigate the effect of TNC during fracture healing. An in vitro mesenchymal stem cell culture system was developed to investigate the role and molecular mechanism of TNC in regulating chondrogenesis. TNC expression was induced at the inflammatory phase and peaked at the cartilaginous callus phase during fracture healing. Knockdown of TNC expression in callus results in decreased callus formation and impaired fracture healing. Conversely, administration of exogenous TNC promoted chondrogenic differentiation, cartilage template formation and ultimately improved fracture healing. Both the Hedgehog and Hippo signaling pathways were found to be involved in the pro-chondrogenic function of TNC. Our observations demonstrate that TNC is a crucial factor responsible for endochondral ossification in fracture healing and provide a potential therapeutic strategy for promoting fracture healing.

Preclinical evaluation of an 18F-labeled Tenascin-C aptamer for PET imaging of atherosclerotic plaque in mouse models of atherosclerosis.

Tenascin-C is an extracellular matrix glycoprotein strongly expressed in coronary atherosclerotic plaque. Aptamers are single-stranded oligonucleotides that bind to specific target molecules with high affinity. This study hypothesized that tenascin-C expression at atherosclerotic plaque in vivo could be detected by tenascin-C specific aptamers using positron emission tomography (PET). This paper reports the radiosynthesis of a fluorine-18 (18F)-labeled tenascin-C aptamer for the biodistribution and PET imaging of the tenascin-C expression in apolipoprotein E-deficient (ApoE-/-) mice. The aortas ApoE-/- mice showed significantly increased positive areas of Oil red O staining than control C57BL/6 mice, and tenascin-C expression was detected in foam cells accumulated in the subendothelial lesions of ApoE-/- mice. The ex vivo biodistribution of the 18F-labeled tenascin-C aptamer showed significantly increased uptake at the aorta of ApoE-/- mice, and ex vivo autoradiography of aorta revealed the high accumulation of the 18F-labeled tenascin-C aptamer in the atherosclerotic lesions of ApoE-/- mice, which was consistent with the location of the atherosclerotic plaques detected by Oil red O staining. PET imaging of the 18F-labeled tenascin-C aptamer revealed a significantly higher mean standardized uptake in the aorta of the ApoE-/- mice than the control C57BL/6 mice. These data highlight the potential use of tenascin-C aptamer to diagnose atherosclerotic lesions in vivo.

Tenascin C as a novel zinc finger protein 750 target regulating the immunogenicity via DNA damage in lung squamous cell carcinoma.

Modulation of DNA damage repair in lung squamous cell carcinoma (LUSC) can result in the generation of neoantigens and heightened immunogenicity. Therefore, understanding DNA damage repair mechanisms holds significant clinical relevance for identifying targets for immunotherapy and devising therapeutic strategies. Our research has unveiled that the tumor suppressor zinc finger protein 750 (ZNF750) in LUSC binds to the promoter region of tenascin C (TNC), leading to reduced TNC expression. This modulation may impact the malignant behavior of tumor cells and is associated with patient prognosis. Additionally, single-cell RNA sequencing (scRNA-seq) of LUSC tissues has demonstrated an inverse correlation between ZNF750/TNC expression levels and immunogenicity. Manipulation of the ZNF750-TNC axis in vitro within LUSC cells has shown differential sensitivity to CD8+ cells, underscoring its pivotal role in regulating cellular immunogenicity. Further transcriptome sequencing analysis, DNA damage repair assay, and single-strand break analyses have revealed the involvement of the ZNF750-TNC axis in determining the preference for homologous recombination (HR) repair or non-homologous end joining (NHEJ) repair of DNA damage. with involvement of the Hippo/ERK signaling pathway. In summary, this study sheds light on the ZNF750-TNC axis's role in DNA damage repair regulation in LUSC, laying a groundwork for future translational research in immune cell therapy for LUSC.

Extracellular Matrix Structure and Interaction with Immune Cells in Adult Astrocytic Tumors.

The extracellular matrix (ECM) is a dynamic set of molecules produced by the cellular component of normal and pathological tissues of the embryo and adult. ECM acts as critical regulator in various biological processes such as differentiation, cell proliferation, angiogenesis, and immune control. The most frequent primary brain tumors are gliomas and by far the majority are adult astrocytic tumors (AATs). The prognosis for patients with these neoplasms is poor and the treatments modestly improves survival. In the literature, there is a fair number of studies concerning the composition of the ECM in AATs, while the number of studies relating the composition of the ECM with the immune regulation is smaller. Circulating ECM proteins have emerged as a promising biomarker that reflect the general immune landscape of tumor microenvironment and may represent a useful tool in assessing disease activity. Given the importance it can have for therapeutic and prognostic purposes, the aim of our study is to summarize the biological properties of ECM components and their effects on the tumor microenvironment and to provide an overview of the interactions between major ECM proteins and immune cells in AATs. As the field of immunotherapy in glioma is quickly expanding, we retain that current data together with future studies on ECM organization and functions in glioma will provide important insights into the tuning of immunotherapeutic approaches.

Targeting myocardial inflammation: investigating the therapeutic potential of atrial natriuretic peptide in atrial fibrosis.

BACKGROUND: Atrial Fibrillation (AF), a prevalent arrhythmic condition, is intricately associated with atrial fibrosis, a major pathological contributor. Central to the development of atrial fibrosis is myocardial inflammation. This study focuses on Atrial Natriuretic Peptide (ANP) and its role in mitigating atrial fibrosis, aiming to elucidate the specific mechanisms by which ANP exerts its effects, with an emphasis on fibroblast dynamics. METHODS AND RESULTS: The study involved forty Sprague-Dawley rats, divided into four groups: control, Angiotensin II (Ang II), Ang II + ANP, and ANP only. The administration of 1 µg/kg/min Ang II was given to Ang II and Ang II + ANP groups, while both Ang II + ANP and ANP groups received 0.1 µg/kg/min ANP intravenously for a duration of 14 days. Cardiac fibroblasts were used for in vitro validation of the proposed mechanisms. The study observed that rats in the Ang II and Ang II + ANP groups showed an increase in blood pressure and a decrease in body weight, more pronounced in the Ang II group. Diastolic dysfunction, a characteristic of the Ang II group, was alleviated by ANP. Additionally, ANP significantly reduced Ang II-induced atrial fibrosis, myofibroblast proliferation, collagen overexpression, macrophage infiltration, and the elevated expression of Interleukin 6 (IL-6) and Tenascin-C (TN-C). Transcriptomic sequencing indicated enhanced PI3K/Akt signaling in the Ang II group. Furthermore, in vitro studies showed that ANP, along with the PI3K inhibitor LY294002, effectively reduced PI3K/Akt pathway activation and the expression of TN-C, collagen-I, and collagen-III, which were induced by Ang II. CONCLUSIONS: The study demonstrates ANP's potential in inhibiting myocardial inflammation and reducing atrial fibrosis. Notably, ANP's effect in countering atrial fibrosis seems to be mediated through the suppression of the Ang II-induced PI3K/Akt-Tenascin-C signaling pathway. These insights enhance our understanding of AF pathogenesis and position ANP as a potential therapeutic agent for treating atrial fibrosis.

Bioactive TNIIIA2 Sequence in Tenascin-C Is Responsible for Macrophage Foam Cell Transformation; Potential of FNIII14 Peptide Derived from Fibronectin in Suppression of Atherosclerotic Plaque Formation.

One of the extracellular matrix proteins, tenascin-C (TN-C), is known to be upregulated in age-related inflammatory diseases such as cancer and cardiovascular diseases. Expression of this molecule is frequently detected, especially in the macrophage-rich areas of atherosclerotic lesions; however, the role of TN-C in mechanisms underlying the progression of atherosclerosis remains obscure. Previously, we found a hidden bioactive sequence termed TNIIIA2 in the TN-C molecule and reported that the exposure of this sequence would be carried out through limited digestion of TN-C by inflammatory proteases. Thus, we hypothesized that some pro-atherosclerotic phenotypes might be elicited from macrophages when they were stimulated by TNIIIA2. In this study, TNIIIA2 showed the ability to accelerate intracellular lipid accumulation in macrophages. In this experimental condition, an elevation of phagocytic activity was observed, accompanied by a decrease in the expression of transporters responsible for lipid efflux. All these observations were mediated through the induction of excessive ß1-integrin activation, which is a characteristic property of the TNIIIA2 sequence. Finally, we demonstrated that the injection of a drug that targets TNIIIA2's bioactivity could rescue mice from atherosclerotic plaque expansion. From these observations, it was shown that TN-C works as a pro-atherosclerotic molecule through an internal TNIIIA2 sequence. The possible advantages of clinical strategies targeting TNIIIA2 are also indicated.

Involvement of Matricellular Proteins in Cellular Senescence: Potential Therapeutic Targets for Age-Related Diseases.

Senescence is a physiological and pathological cellular program triggered by various types of cellular stress. Senescent cells exhibit multiple characteristic changes. Among them, the characteristic flattened and enlarged morphology exhibited in senescent cells is observed regardless of the stimuli causing the senescence. Several studies have provided important insights into pro-adhesive properties of cellular senescence, suggesting that cell adhesion to the extracellular matrix (ECM), which is involved in characteristic morphological changes, may play pivotal roles in cellular senescence. Matricellular proteins, a group of structurally unrelated ECM molecules that are secreted into the extracellular environment, have the unique ability to control cell adhesion to the ECM by binding to cell adhesion receptors, including integrins. Recent reports have certified that matricellular proteins are closely involved in cellular senescence. Through this biological function, matricellular proteins are thought to play important roles in the pathogenesis of age-related diseases, including fibrosis, osteoarthritis, intervertebral disc degeneration, atherosclerosis, and cancer. This review outlines recent studies on the role of matricellular proteins in inducing cellular senescence. We highlight the role of integrin-mediated signaling in inducing cellular senescence and provide new therapeutic options for age-related diseases targeting matricellular proteins and integrins.

Clinical Utility of Pro-inflammatory Oligomeric Glycoprotein Tenascin-C in the Diagnosis of Seropositive and Seronegative Rheumatoid Arthritis.

Owing to limited usefulness of Rheumatoid Factor and anti-CCP in rheumatoid arthritis, there is a need to identify a more sensitive and specific biomarker to detect rheumatoid arthritis (RA), particularly seronegative RA cases. Tenascin-C is an extracellular matrix glycoprotein, which has been implicated in the pathophysiology of RA. The objective of our study was to evaluate the diagnostic utility of serum Tenascin-C in seropositive and seronegative rheumatoid arthritis patients. We conducted a cross-sectional case control study. Sixty patients who fulfilled the ACR 2010 criteria for rheumatoid arthritis were included in the study. Thirty patients were found to be positive for RF and/or anti-CCP and 30 were negative for both RF and anti-CCP. Thirty age and gender-matched healthy subjects were taken as controls. Serum Tenascin-C was measured by quantitative sandwich enzyme immunoassay technique. The mean serum concentration of Tenascin-C in controls, seronegative and seropositive cases was 0.66 ng/ml, 20.54 ng/ml and 23.42 ng/ml, respectively. Tenascin-C levels were significantly higher in RA cases compared to controls (p < 0.0001). There was no significant difference in Tenascin-C between seropositive and seronegative cases (p = 0.603). ROC curve analysis showed a sensitivity of 96.6% and specificity of 100% with AUC of 0.98 at 2.21 ng/ml as cut-off value for diagnosing RA. Tenascin-C is elevated in both seronegative and seropositive RA, which indicates that it can be used as a sensitive marker for RA. The addition of Tenascin-C to the existing RF and anti-CCP may help in identifying a large number of patients with RA, particularly seronegative rheumatoid arthritis cases.

A virological view of tenascin-C in infection.

Tenascin-C is a large extracellular matrix glycoprotein with complex, not yet fully unveiled roles. Its context- and structure-dependent modus operandi renders tenascin-C a puzzling protein. Since its discovery ∼40 years ago, research into tenascin-C biology continues to reveal novel functions, the most recent of all being its immunomodulatory activity, especially its role in infection, which is just now beginning to emerge. Here, we explore the role of tenascin-C in the immune response to viruses, including SARS-CoV-2 and HIV-1. Recently, tenascin-C has emerged as a biomarker of disease severity during COVID-19 and other viral infections, and we highlight relevant RNA sequencing and proteomic analyses that suggest a correlation between tenascin-C levels and disease severity. Finally, we ask what the function of this protein during viral replication is and propose tenascin-C as an intercellular signal of inflammation shuttled to distal sites via exosomes, a player in the repair and remodeling of infected and damaged tissues during severe infectious disease, as well as a ligand for specific pathogens with distinct implications for the host.

The long non-coding RNA ET-20 mediates EMT by impairing desmosomes in breast cancer cells.

The vast majority of breast cancer-associated deaths are due to metastatic spread of cancer cells, a process aided by epithelial-to-mesenchymal transition (EMT). Mounting evidence has indicated that long non-coding RNAs (lncRNAs) also contribute to tumor progression. We report the identification of 114 novel lncRNAs that change their expression during TGFß-induced EMT in murine breast cancer cells (referred to as EMT-associated transcripts; ETs). Of these, the ET-20 gene localizes in antisense orientation within the tenascin C (Tnc) gene locus. TNC is an extracellular matrix protein that is critical for EMT and metastasis formation. Both ET-20 and Tnc are regulated by the EMT master transcription factor Sox4. Notably, ablation of ET-20 lncRNA effectively blocks Tnc expression and with it EMT. Mechanistically, ET-20 interacts with desmosomal proteins, thereby impairing epithelial desmosomes and promoting EMT. A short transcript variant of ET-20 is shown to be upregulated in invasive human breast cancer cell lines, where it also promotes EMT. Targeting ET-20 appears to be a therapeutically attractive lead to restrain EMT and breast cancer metastasis in addition to its potential utility as a biomarker for invasive breast cancer.

Alterations in Coronary Resistance Artery Network Geometry in Diabetes and the Role of Tenascin C.

Background: Geometrical alterations in the coronary resistance artery network and the potential involvement of Tenascin C (TNC) extracellular matrix protein were investigated in diabetic and control mice. Methods: Diabetes was induced by streptozotocin (STZ) injections (n = 7-11 animals in each group) in Tenascin C KO (TNC KO) mice and their Wild type (A/J) littermates. After 16-18 weeks the heart was removed and the whole subsurface network of the left coronary artery was prepared (down to branches of 40 µ m outer diameter), in situ pressure-perfused and studied using video-microscopy. Outer and inner diameters, wall thicknesses and bifurcation angles were measured on whole network pictures reconstructed into collages at 1.7 µ m pixel resolutions. Results: Diabetes induced abnormal morphological alterations including trifurcations, sharp bends of larger branches, and branches directed retrogradely (p < 0.001 by the χ 2 test). Networks of TNC KO mice tended to form early divisions producing parallelly running larger branches (p < 0.001 by the χ 2 probe). Networks of coronary resistance arteries were substantially more abundant in 100-180 µ m components, appearing in 2-5 mm flow distance from orifice in diabetes. This was accompanied by thickening of the wall of larger arterioles ( > 220 µ m) and thinning of the wall of smaller (100-140 µ m) arterioles (p < 0.001). Blood flow should cover larger distances in diabetic networks, but interestingly STZ-induced diabetes did not generate further geometrical changes in TNC KO mice. Conclusions: Diabetes promotes hypertrophic and hypotrophic vascular remodeling and induces vasculogenesis at well defined, specific positions of the coronary vasculature. TNC plays a pivotal role in the formation of coronary network geometry, and TNC deletion causes parallel fragmentation preventing diabetes-induced abnormal vascular morphologies.

The paired-related homeobox protein 1 promotes cardiac fibrosis via the Twist1-Prrx1-tenascin-C loop.

Cardiac fibrosis is a common pathology in the advanced stage of cardiovascular diseases, which leads to cardiac systolic and diastolic dysfunction. It is important to prevent cardiac fibrosis during myocardial injury. The transcription factor Prrx1 is involved in cancer-associated fibrosis and other organ fibrosis. However, the role and mechanism of Prrx1 in cardiac fibrosis deserves further exploration. We identified that overexpressed Prrx1 promoted the proliferation and migration of cardiac fibroblasts, and transform cardiac fibroblasts to myofibroblasts in vitro. We demonstrated that the expression of Prrx1 is upregulated in TGF-ß1-treated fibroblasts. And silencing Prrx1 could attenuate cardiac fibrosis induced by TGF-ß1 in vitro. In addition, a Twist1-paired-related homeobox 1 (Prrx1)-tenascin-C (TNC) positive feedback loop (PFL) combined with Twist1, Prrx1, and TNC activated fibroblasts, which was the mechanism the Prrx1 in cardiac fibrosis. In conclusion, our findings showed that the deficiency of Prrx1 attenuated cardiac fibrosis in vitro and reveal a novel Twist1-Prrx1-TNC PFL in the regulation of cardiac fibrosis.

DNA methyltransferase 3A induces the occurrence of oral submucous fibrosis by promoting the methylation of the von Hippel-Lindau.

BACKGROUND: Oral submucous fibrosis (OSF) is associated with malignant disorders. DNA methyltransferase 3A (DNMT3A) is a DNA methylesterase reported to be upregulated in multiple organs and shown to inhibit fibrosis. However, the detailed effect of DNMT3A on OSF remains unclear. METHODS: To mimic OSF in vitro, oral fibroblasts were exposed to arecoline and molecular biological experiments were performed to detect the function of DNMT3A in OSF. RESULTS: We found that von Hippel-Lindau (VHL) was downregulated and highly methylated in OSF. Arecoline remarkably increased the viability, invasiveness, and migration of oral fibroblasts, but upregulation of VHL partially reversed these effects. DNMT3A induces DNA hypermethylation in the VHL promoter, and VHL markedly inhibits the level of tenascin-C (TNC) by inducing the ubiquitination of TNC. TNC reversed the inhibitory effect of VHL upregulation on the differentiation of oral fibroblasts into myofibroblasts. CONCLUSION: DNMT3A induces OSF by promoting methylation of the VHL promoter. Hence, our study provides novel insights into the discovery of novel strategies that can be employed against OSF.

Developmental Changes in Patterns of Distribution of Fibronectin and Tenascin-C in the Chicken Cornea: Evidence for Distinct and Independent Functions during Corneal Development and Morphogenesis.

The cornea forms the tough and transparent anterior part of the eye and by accurate shaping forms the major refractive element for vision. Its largest component is the stroma, a dense collagenous connective tissue positioned between the epithelium and the endothelium. In chicken embryos, the stroma initially develops as the primary stroma secreted by the epithelium, which is then invaded by migratory neural crest cells. These cells secrete an organised multi-lamellar collagenous extracellular matrix (ECM), becoming keratocytes. Within individual lamellae, collagen fibrils are parallel and orientated approximately orthogonally in adjacent lamellae. In addition to collagens and associated small proteoglycans, the ECM contains the multifunctional adhesive glycoproteins fibronectin and tenascin-C. We show in embryonic chicken corneas that fibronectin is present but is essentially unstructured in the primary stroma before cell migration and develops as strands linking migrating cells as they enter, maintaining their relative positions as they populate the stroma. Fibronectin also becomes prominent in the epithelial basement membrane, from which fibronectin strings penetrate into the stromal lamellar ECM at right angles. These are present throughout embryonic development but are absent in adults. Stromal cells associate with the strings. Since the epithelial basement membrane is the anterior stromal boundary, strings may be used by stromal cells to determine their relative anterior-posterior positions. Tenascin-C is organised differently, initially as an amorphous layer above the endothelium and subsequently extending anteriorly and organising into a 3D mesh when the stromal cells arrive, enclosing them. It continues to shift anteriorly in development, disappearing posteriorly, and finally becoming prominent in Bowman's layer beneath the epithelium. The similarity of tenascin-C and collagen organisation suggests that it may link cells to collagen, allowing cells to control and organise the developing ECM architecture. Fibronectin and tenascin-C have complementary roles in cell migration, with the former being adhesive and the latter being antiadhesive and able to displace cells from their adhesion to fibronectin. Thus, in addition to the potential for associations between cells and the ECM, the two could be involved in controlling migration and adhesion and subsequent keratocyte differentiation. Despite the similarities in structure and binding capabilities of the two glycoproteins and the fact that they occupy similar regions of the developing stroma, there is little colocalisation, demonstrating their distinctive roles.

Chemokine Binding to Tenascin-C Influences Chemokine-Induced Immune Cell Migration.

Tenascin-C (TNC) is a complex glycoprotein of the extracellular matrix (ECM) involved in a plethora of (patho-)physiological processes, such as oncogenesis and inflammation. Since chemokines play an essential role in both disease processes, we have investigated here the binding of TNC to some of the key chemokines, namely CCL2, CCL26, CXCL8, CXCL10, and CXCL12. Thereby, a differential chemokine-TNC binding pattern was observed, with CCL26 exhibiting the highest and CCL2 the lowest affinity for TNC. Heparan sulfate (HS), another member of the ECM, proved to be a similarly high-affinity ligand of TNC, with a Kd value of 730 nM. Chemokines use glycosa-minoglycans such as HS as co-receptors to induce immune cell migration. Therefore, we assumed an influence of TNC on immune cell chemotaxis due to co-localization within the ECM. CCL26- and CCL2-induced mobilization experiments of eosinophils and monocytes, respectively, were thus performed in the presence and the absence of TNC. Pre-incubation of the immune cells with TNC resulted in a 3.5-fold increase of CCL26-induced eosinophil chemotaxis, whereas a 1.3-fold de-crease in chemotaxis was observed when monocytes were pre-incubated with CCL2. As both chemokines have similar HS binding but different TNC binding affinities, we speculate that TNC acts as an attenuator in monocyte and as an amplifier in eosinophil mobilization by impeding CCL2 from binding to HS on the one hand, and by reinforcing CCL26 to bind to HS on the other hand.

Investigating Chemokine-Matrix Networks in Breast Cancer: Tenascin-C Sets the Tone for CCL2.

Bidirectional dialogue between cellular and non-cellular components of the tumor microenvironment (TME) drives cancer survival. In the extracellular space, combinations of matrix molecules and soluble mediators provide external cues that dictate the behavior of TME resident cells. Often studied in isolation, integrated cues from complex tissue microenvironments likely function more cohesively. Here, we study the interplay between the matrix molecule tenascin-C (TNC) and chemokine CCL2, both elevated in and associated with the progression of breast cancer and playing key roles in myeloid immune responses. We uncover a correlation between TNC/CCL2 tissue levels in HER2+ breast cancer and examine the physical and functional interactions of these molecules in a murine disease model with tunable TNC levels and in in vitro cellular and cell-free models. TNC supported sustained CCL2 synthesis, with chemokine binding to TNC via two distinct domains. TNC dominated the behavior of tumor-resident myeloid cells; CCL2 did not impact macrophage survival/activation whilst TNC facilitated an immune suppressive macrophage phenotype that was not dependent on or altered by CCL2 co-expression. Together, these data map new binding partners within the TME and demonstrate that whilst the matrix exerts transcriptional control over the chemokine, each plays a distinct role in subverting anti-tumoral immunity.