Distinct structural basis and catalytic classification of matrix metalloproteinases and their endogenous tissue inhibitors with glycosylation issue in cellular and tissue regulation

Matrix metalloproteinase (MMP) enzymes cleave proteins on the extracellular matrix (ECM) region. MMPs are categorized as Zn2+-binding endo-proteinases. MMPs are stringently regulated in cancers, inflammatory cells and tissues. There are 29 types of MMPs as initially expressed in inactive zymogens (proMMPs) and activated by proteolysis in vertebrates including human. MMPs consist of three highly conserved parts of pro-MMP in precursor, catalytic and hemopexin domains. The MMPs are composed of systemic complexes with their endogenously expressed inhibitors of the tissue inhibitors of metalloproteinases (TIMPs). Therefore, TIMPs intrinsically control such activated MMPs, indicating the existence of self-modulation capacity. N-linked glycosylation (N-glycosylation) saves biological information than known phosphorylation, ubiquitination and acetylation. The MMPs are roughly present as membrane-merged and secreted glycoproteins. MMPs N-glycans regulate cellular behaviors, immune tolerance, and developing angiogenesis. Aberrant N-glycosylation of MMPs may cause the pathogenic properties. N-glycosylation shapes phenotypes of MMPs-producing cells during early MMPs involved in human. Additionally, issues of MMPs and TIMPs glycosylation have been described to view the importance of the glycans in their interaction with owns and other targets. Most of MMPs and 4 TIMPs are not well studied for their glycosylation and its functional roles.

Basigin in cerebrovascular diseases: Roles, mechanisms, and therapeutic target potential

Cerebrovascular diseases are major global health issues, responsible for significant morbidity and mortality. Basigin (additionally called CD147 or EMMPRIN) is a glycosylated transmembrane protein that facilitates intercellular communication. Recent research has highlighted the critical role of Basigin in inducing matrix metalloproteinases (MMPs), which contribute to the progression of cerebrovascular diseases. Consequently, Basigin has emerged as a promising therapeutic target for these conditions. However, inhibiting the pivotal role of Basigin in mediating cerebrovascular disease is an urgent area of investigation. In this review, we systematically examine the pathological mechanisms by which Basigin contributes to the development of cerebrovascular diseases. We present evidence demonstrating the protective effect of targeted inhibition of Basigin in these conditions and suggest future research directions.

Hydrogen Sulfide Modulation of Matrix Metalloproteinases and CD147/EMMPRIN: Mechanistic Pathways and Impact on Atherosclerosis Progression

Atherosclerosis is a chronic inflammatory condition marked by endothelial dysfunction, lipid accumulation, inflammatory cell infiltration, and extracellular matrix (ECM) remodeling within arterial walls, leading to plaque formation and potential cardiovascular events. Key players in ECM remodeling and inflammation are matrix metalloproteinases (MMPs) and CD147/EMMPRIN, a cell surface glycoprotein expressed on endothelial cells, vascular smooth muscle cells (VSMCs), and immune cells, that regulates MMP activity. Hydrogen sulfide (H₂S), a gaseous signaling molecule, has emerged as a significant modulator of these processes including oxidative stress mitigation, inflammation reduction, and vascular remodeling. This systematic review investigates the mechanistic pathways through which H₂S influences MMPs and CD147/EMMPRIN and assesses its impact on atherosclerosis progression. A comprehensive literature search was conducted across PubMed, Scopus, and Web of Science databases, focusing on studies examining H₂S modulation of MMPs and CD147/EMMPRIN in atherosclerosis contexts. Findings indicate that H₂S modulates MMP expression and activity through transcriptional regulation and post-translational modifications, including S-sulfhydration. By mitigating oxidative stress, H₂S reduces MMP activation, contributing to plaque stability and vascular remodeling. H₂S also downregulates CD147/EMMPRIN expression via transcriptional pathways, diminishing inflammatory responses and vascular cellular proliferation within plaques. The dual regulatory role of H₂S in inhibiting MMP activity and downregulating CD147 suggests its potential as a therapeutic agent in stabilizing atherosclerotic plaques and mitigating inflammation. Further research is warranted to elucidate the precise molecular mechanisms and to explore H₂S-based therapies for clinical application in atherosclerosis.

MCT4 and CD147 colocalize with MMP14 in invadopodia and support matrix degradation and invasion by breast cancer cells

Expression levels of the lactate-H+ cotransporter MCT4 (also known as SLC16A3) and its chaperone CD147 (also known as basigin) are upregulated in breast cancers, correlating with decreased patient survival. Here, we test the hypothesis that MCT4 and CD147 favor breast cancer invasion through interdependent effects on extracellular matrix (ECM) degradation. MCT4 and CD147 expression and membrane localization were found to be strongly reciprocally interdependent in MDA-MB-231 breast cancer cells. Overexpression of MCT4 and/or CD147 increased, and their knockdown decreased, migration, invasion and the degradation of fluorescently labeled gelatin. Overexpression of both proteins led to increases in gelatin degradation and appearance of the matrix metalloproteinase (MMP)-generated collagen-I cleavage product reC1M, and these increases were greater than those observed upon overexpression of each protein alone, suggesting a concerted role in ECM degradation. MCT4 and CD147 colocalized with invadopodia markers at the plasma membrane. They also colocalized with MMP14 and the lysosomal marker LAMP1, as well as partially with the autophagosome marker LC3, in F-actin-decorated intracellular vesicles. We conclude that MCT4 and CD147 reciprocally regulate each other and interdependently support migration and invasiveness of MDA-MB-231 breast cancer cells. Mechanistically, this involves MCT4-CD147-dependent stimulation of ECM degradation and specifically of MMP-mediated collagen-I degradation. We suggest that the MCT4-CD147 complex is co-delivered to invadopodia with MMP14.

Protein glycosylation in lung cancer from a mass spectrometry perspective

Lung cancer is a severe disease for which better diagnostic and therapeutic approaches are urgently needed. Increasing evidence implies that aberrant protein glycosylation plays a crucial role in the pathogenesis and progression of lung cancer. Differences in glycosylation patterns have been previously observed between healthy and cancerous samples as well as between different lung cancer subtypes, which suggests untapped diagnostic potential. In addition, understanding the changes mediated by glycosylation may shed light on possible novel therapeutic targets and personalized treatment strategies for lung cancer patients. Mass spectrometry based glycomics and glycoproteomics have emerged as powerful tools for in-depth characterization of changes in protein glycosylation, providing valuable insights into the molecular basis of lung cancer. This paper reviews the literature on the analysis of protein glycosylation in lung cancer using mass spectrometry, which is dominated by manuscripts published over the past 5 years. Studies analyzing N-glycosylation, O-glycosylation, and glycosaminoglycan patterns in tissue, serum, plasma, and rare biological samples of lung cancer patients are highlighted. The current knowledge on the potential utility of glycan and glycoprotein biomarkers is also discussed.

A comprehensive investigation on the receptor BSG expression reveals the potential risk of healthy individuals and cancer patients to 2019-nCoV infection

BACKGROUND

Coronavirus disease-2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a newly emerging coronavirus. BSG (basigin) is involved in the tumorigenesis of multiple tumors and recently emerged as a novel viral entry receptor for SARS-CoV-2. However, its expression profile in normal individuals and cancer patients are still unclear.

METHODS

We performed a comprehensive analysis of the expression and distribution of BSG in normal tissues, tumor tissues, and cell lines via bioinformatics analysis and experimental verification. In addition, we investigated the expression of BSG and its isoforms in multiple malignancies and adjacent normal tissues, and explored the prognostic values across pan-cancers. Finally, we conducted function analysis for co-expressed genes with BSG.

RESULTS

We found BSG was highly conserved in different species, and was ubiquitously expressed in almost all normal tissues and significantly increased in some types of cancer tissues. Moreover, BSG at mRNA expression level was higher than ACE2 in normal lung tissues, and lung cancer tissues. High expression of BSG indicated shorter overall survival (OS) in multiple tumors. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that BSG is mostly enriched in genes for mitochondria electron transport, oxidoreduction-driven active transmembrane transporter activity, mitochondrial inner membrane, oxidative phosphorylation, and genes involving COVID-19.

CONCLUSIONS

Our present work emphasized the value of targeting BSG in the treatment of COVID-19 and cancer, and also provided several novel insights for understanding the SARS-CoV-2 pandemic.

Core fucosylation and its roles in gastrointestinal glycoimmunology

Glycosylation is a common post-translational modification in eukaryotic cells. It is involved in the production of many biologically active glycoproteins and the regulation of protein structure and function. Core fucosylation plays a vital role in the immune response. Most immune system molecules are core fucosylated glycoproteins such as complements, cluster differentiation antigens, immunoglobulins, cytokines, major histocompatibility complex molecules, adhesion molecules, and immune molecule synthesis-related transcription factors. These core fucosylated glycoproteins play important roles in antigen recognition and clearance, cell adhesion, lymphocyte activation, apoptosis, signal transduction, and endocytosis. Core fucosylation is dominated by fucosyltransferase 8 (Fut8), which catalyzes the addition of α-1,6-fucose to the innermost GlcNAc residue of N-glycans. Fut8 is involved in humoral, cellular, and mucosal immunity. Tumor immunology is associated with aberrant core fucosylation. Here, we summarize the roles and potential modulatory mechanisms of Fut8 in various immune processes of the gastrointestinal system.

CD147 and MMPs as key factors in physiological and pathological processes

Cluster of differentiation 147 (CD147) or extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that induces the synthesis of matrix metalloproteinases (MMPs). MMPs, as zinc-dependent proteases and versatile enzymes, play critical roles in the degradation of the extracellular matrix (ECM) components, cleaving of the receptors of cellular surfaces, signaling molecules, and other precursor proteins, which may lead to attenuation or activation of such targets. CD147 and MMPs play essential roles in physiological and pathological conditions and any disorder in the expression, synthesis, or function of CD147 and MMPs may be associated with various types of disease. In this review, we have focused on the roles of CD147 and MMPs in some major physiological and pathological processes.

Role of MMP-2 and CD147 in kidney fibrosis

Matrix metalloproteinase-2 (MMP-2) and cluster of differentiation 147 (CD147) both play important roles in the development of kidney fibrosis, and CD147 can induce the production and activation of MMP-2. In the early stage of kidney fibrosis, MMP-2 promotes extracellular matrix (ECM) production and accelerates the development of kidney fibrosis, while in the advanced stage, MMP-2 activity decreases, leading to reduced ECM degradation and making it difficult to alleviate kidney fibrosis. The reason for the decrease in MMP-2 activity in the advanced stage is still unclear. On the one hand, it may be related to hypoxia and endocytosis, which lead to changes in the expression of MMP-2-related active regulatory molecules; on the other hand, it may be related to insufficient CD147 function. At present, the specific process by which CD147 is involved in the regulation of MMP-2 activity is not completely clear, and further in-depth studies are needed to clarify the roles of both factors in the pathophysiology of kidney fibrosis.

Impairment of neutrophil functions and homeostasis in COVID-19 patients: association with disease severity

Background

A dysregulated immune response is emerging as a key feature of critical illness in COVID-19. Neutrophils are key components of early innate immunity that, if not tightly regulated, contribute to uncontrolled systemic inflammation. We sought to decipher the role of neutrophil phenotypes, functions, and homeostasis in COVID-19 disease severity and outcome.

Methods

By using flow cytometry, this longitudinal study compares peripheral whole-blood neutrophils from 90 COVID-19 ICU patients with those of 22 SARS-CoV-2-negative patients hospitalized for severe community-acquired pneumonia (CAP) and 38 healthy controls. We also assessed correlations between these phenotypic and functional indicators and markers of endothelial damage as well as disease severity.

Results

At ICU admission, the circulating neutrophils of the COVID-19 patients showed continuous basal hyperactivation not seen in CAP patients, associated with higher circulating levels of soluble E- and P-selectin, which reflect platelet and endothelial activation. Furthermore, COVID-19 patients had expanded aged-angiogenic and reverse transmigrated neutrophil subsets—both involved in endothelial dysfunction and vascular inflammation. Simultaneously, COVID-19 patients had significantly lower levels of neutrophil oxidative burst in response to bacterial formyl peptide. Moreover patients dying of COVID-19 had significantly higher expansion of aged-angiogenic neutrophil subset and greater impairment of oxidative burst response than survivors.

Conclusions

These data suggest that neutrophil exhaustion may be involved in the pathogenesis of severe COVID-19 and identify angiogenic neutrophils as a potentially harmful subset involved in fatal outcome.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04002-3.

The Role of CD147 in Pathological Cardiac Hypertrophy Is Regulated by Glycosylation

CD147, also known as EMMPRIN or basigin, is a transmembrane glycoprotein receptor that activates matrix metalloproteinases and promotes inflammation. CD147 function is regulated by posttranslational modifications of which glycosylation has attracted the most attention. In this study, we demonstrated that glycosylated CD147 was the dominant form in heart tissue, and its levels were markedly elevated in response to transverse aortic constriction (TAC). Adeno-associated virus 9-mediated, cardiac-specific overexpression of wild-type CD147 in mice significantly promoted pressure overload-induced pathological cardiac remodeling accompanied by augmented oxidative stress and ferroptosis. By contrast, mutations of CD147 glycosylation sites notably weakened these detrimental effects of CD147. Mechanistically, CD147 exacerbated TAC-induced pathological cardiac remodeling via direct binding with the adaptor molecule TRAF2 and subsequent activation of TAK1 signalling, which was dependent on glycosylation of CD147. Collectively, our findings provide the first evidence that CD147 promoted pathological cardiac remodeling and dysfunction in a glycosylation-dependent manner through binding the adaptor protein TRAF2 and activating the downstream TRAF2-TAK1 signalling pathway. Thus, glycosylation of CD147 may be a potent interventional target for heart failure treatment.

CD147 Levels in Blood and Adipose Tissues Correlate with Vascular Dysfunction in Obese Diabetic Adults

CD147 is a glycoprotein that stimulates the production of matrix metalloproteinases (MMPs), known contributors to cardiovascular risk. The activity of CD147 protein depends on its glycosylation. However, it is unclear whether CD147 protein expression or glycosylation are influenced by the diabetic milieu characterized by hyperglycemia and abundant glycation-end-products (AGEs). We examined the circulating and visceral adipose tissue (VAT) levels of CD147 and their correlation with vascular function in obese, obese diabetic, and non-obese controls (n = 40, each). The circulating levels of CD147 and the glycosylated CD147 protein in VAT were considerably higher in obese, particularly obese diabetic subjects compared to controls. Obese diabetics had the lowest brachial and arteriolar vasoreactivity and the highest carotid pulse-wave velocity (PWV, a measure of arterial stiffness) among the three groups. CD147 correlated positively with body mass index (BMI), total and visceral fat mass, PWV, and plasma levels of glucose, insulin, MMPs, and AGEs and negatively with brachial artery and VAT-arteriolar vasoreactivity and nitric oxide production. Multivariate regression revealed that BMI, body fat mass, insulin, and glucose levels significantly predicted CD147. Our data suggest that higher levels of CD147 in obese subjects, particularly those with diabetes, are linked to vascular dysfunction and several cardiometabolic risk factors.

CRISPR/Cas9 genome editing reveals an essential role for basigin in maintaining a nonkeratinized squamous epithelium in cornea

One of the primary functions of nonkeratinized stratified squamous epithelia is to protect underlying tissues against chemical, microbial, and mechanical insult. Basigin is a transmembrane matrix metalloproteinase inducer commonly overexpressed during epithelial wound repair and cancer but whose physiological significance in normal epithelial tissue has not been fully explored. Here we used a CRISPR/Cas9 system to study the effect of basigin loss in a human cornea model of squamous epithelial differentiation. We find that epithelial cell cultures lacking basigin change shape and fail to produce a flattened squamous layer on the apical surface. This process is associated with the abnormal expression of the transcription factor SPDEF and the decreased biosynthesis of MUC16 and involucrin necessary for maintaining apical barrier function and structural integrity, respectively. Expression analysis of genes encoding tight junction proteins identified a role for basigin in promoting physiological expression of occludin and members of the claudin family. Functionally, disruption of basigin expression led to increased epithelial cell permeability as evidenced by the decrease in transepithelial electrical resistance and increase in rose bengal flux. Overall, these results suggest that basigin plays a distinct role in maintaining the normal differentiation of stratified squamous human corneal epithelium and could have potential implications to therapies targeting basigin function.

Novel gene-encoded intermolecular FRET sensor for tracking glycosylation of CD147 in living cells

CD147 is involved in various physiological processes and plays important roles for tumor metastasis. Glycosylation of the protein determines numerous functions of CD147. Up to now, hardly any sensor has been developed for detecting glycosylation of CD147 in live cells. There is a pressing requirement of development of a selective and continuous biosensor for cell imaging. The emergence of gene-encoded fluorescence resonance energy transfer (FRET) sensor provides a new way to develop the sensors to analysts. We designed and constructed novel gene-encoded FRET proteins sensing glycosylation of CD147 by measuring FRET ratio of two intermolecular motifs. With the decrease of CD147 glycosylation level in cells, the FRET ratio increased significantly. The specificity of the sensor targeting to CD147 was also determined by siRNA interference experiment. Finally, continuous living cell image of deglycosylation process of CD147 using the newly developed sensor has been performed successfully. The work not only provides useful tools for analyzing glycosylation of CD147 in living cells, but also implicates alternative strategy for detecting other glycosylated proteins.

Discovery and Biological Evaluation of CD147 N-Glycan Inhibitors: A New Direction in the Treatment of Tumor Metastasis

N-glycosylation is instrumental to the regulation of CD147 functions, including the maturation of CD147, secretion of matrix metalloproteinases (MMPs), and promotion of tumor metastasis. Glycosylated CD147 is highly expressed in various cancer types, participates in metastasis, and is associated with the poor prognosis of malignant tumors. However, to date, there has been little development of target-specific inhibitors for CD147 glycosylation. In this work, we report a strategy for discovering CD147 glycosylation inhibitors through computer-aided screening and inhibition assays. Four compounds were screened as potential CD147 glycosylation inhibitors. Of these, compound 72 was finally identified as the best candidate. Further experiments confirmed that compound 72 inhibited the production of MMPs and the metastasis of cancer cells in the Hela cell line. Results further suggest that compound 72 could promote the expression of E-cadherin by targeting CD147, thereby inhibiting tumor migration. Finally, the structures of the other potential CD147 N-glycosylation inhibitors may eventually provide guidance for future optimization.

ACE2: from protection of liver disease to propagation of COVID-19

Twenty years ago, the discovery of angiotensin-converting enzyme 2 (ACE2) was an important breakthrough dramatically enhancing our understanding of the renin-angiotensin system (RAS). The classical RAS is driven by its key enzyme ACE and is pivotal in the regulation of blood pressure and fluid homeostasis. More recently, it has been recognised that the protective RAS regulated by ACE2 counterbalances many of the deleterious effects of the classical RAS. Studies in murine models demonstrated that manipulating the protective RAS can dramatically alter many diseases including liver disease. Liver-specific overexpression of ACE2 in mice with liver fibrosis has proved to be highly effective in antagonising liver injury and fibrosis progression. Importantly, despite its highly protective role in disease pathogenesis, ACE2 is hijacked by SARS-CoV-2 as a cellular receptor to gain entry to alveolar epithelial cells, causing COVID-19, a severe respiratory disease in humans. COVID-19 is frequently life-threatening especially in elderly or people with other medical conditions. As an unprecedented number of COVID-19 patients have been affected globally, there is an urgent need to discover novel therapeutics targeting the interaction between the SARS-CoV-2 spike protein and ACE2. Understanding the role of ACE2 in physiology, pathobiology and as a cellular receptor for SARS-CoV-2 infection provides insight into potential new therapeutic strategies aiming to prevent SARS-CoV-2 infection related tissue injury. This review outlines the role of the RAS with a strong focus on ACE2-driven protective RAS in liver disease and provides therapeutic approaches to develop strategies to prevent SARS-CoV-2 infection in humans.

Lymphocyte Changes in Severe COVID-19: Delayed Over-Activation of STING?

Upon recognition of microbial DNA or self-DNA, the cyclic-GMP-AMP synthase (cGAS) of the host catalyzes the production of the cyclic dinucleotide cGAMP. cGAMP is the main activator of STING, stimulator of interferon genes, leading to interferon synthesis through the STING-TBK1-IRF3 pathway. STING is also a hub for activation of NF-κB and autophagy. The present review details the striking similarities between T and B cell responses in severe coronavirus disease 2019 (COVID-19) and both animal or human models of STING gain of function (SAVI syndromes: STING-associated vasculopathy with onset in infancy). Those similarities may be further clues for a delayed activation of STING in severe COVID-19 patients, due to DNA damages following severe acute respiratory syndrome coronaviruses (SARS-CoV-2) infection and unusual role of STING in SARS-CoV-2 control. In early stages, Th2 differentiation are noticed in both severe COVID-19 and SAVI syndromes; then, CD4+ and CD8+ T cells functional exhaustion/senescent patterns due to TCR hyper-responsiveness are observed. T cell delayed over-responses can contribute to pneumonitis and delayed cytokine secretion with over-production of IL-6. Last, STING over-activation induces progressive CD4+ and CD8+ T lymphopenia in SAVI syndromes, which parallels what is observed in severe COVID-19. ACE2, the main receptor of SARS-CoV-2, is rarely expressed in immune cells, and it has not been yet proven that some human lymphocytes could be infected by SARS-CoV-2 through CD147 or CD26. However, STING, expressed in humans T cells, might be triggered following excessive transfer of cGAMP from infected antigen presenting cells into activated CD4+ and CD8+ T cells lymphocytes. Indeed, those lymphocytes highly express the cGAMP importer SLC19A1. Whereas STING is not expressed in human B cells, B cells counts are much less affected, either in COVID-19 or SAVI syndromes. The recognition of delayed STING over-activation in severe COVID-19 patients could prompt to target STING with specific small molecules inhibitors already designed and/or aspirin, which inhibits cGAS.

Golgi α1,2-mannosidase I induces clustering and compartmentalization of CD147 during epithelial cell migration

CD147 is a widely expressed matrix metalloproteinase inducer involved in the regulation of cell migration. The high glycosylation and ability to undergo oligomerization have been linked to CD147 function, yet there is limited understanding on the molecular mechanisms behind these processes. The current study demonstrates that the expression of Golgi α1,2-mannosidase I is key to maintaining the cell surface organization of CD147 during cell migration. Using an in vitro model of stratified human corneal epithelial wound healing, we show that CD147 is clustered within lateral plasma membranes at the leading edge of adjacent migrating cells. This localization correlates with a surge in matrix metalloproteinase activity and an increase in the expression of α1,2-mannosidase subtype IC (MAN1C1). Global inhibition of α1,2-mannosidase I activity with deoxymannojirimycin markedly attenuates the glycosylation of CD147 and disrupts its surface distribution at the leading edge, concomitantly reducing the expression of matrix metalloproteinase-9. Likewise, treatment with deoxymannojirimycin or siRNA-mediated knockdown of MAN1C1 impairs the ability of the carbohydrate-binding protein galectin-3 to stimulate CD147 clustering in unwounded cells. We conclude that the mannose-trimming activity of α1,2-mannosidase I coordinates the clustering and compartmentalization of CD147 that follows an epithelial injury.

Mapping glycan-mediated galectin-3 interactions by live cell proximity labeling

Galectin-3 is a glycan-binding protein (GBP) that binds β-galactoside glycan structures to orchestrate a variety of important biological events, including the activation of hepatic stellate cells and regulation of immune responses. While the requisite glycan epitopes needed to bind galectin-3 have long been elucidated, the cellular glycoproteins that bear these glycan signatures remain unknown. Given the importance of the three-dimensional (3D) arrangement of glycans in dictating GBP interactions, strategies that allow the identification of GBP receptors in live cells, where the native glycan presentation and glycoprotein expression are preserved, have significant advantages over static and artificial systems. Here we describe the integration of a proximity labeling method and quantitative mass spectrometry to map the glycan and glycoprotein interactors for galectin-3 in live human hepatic stellate cells and peripheral blood mononuclear cells. Understanding the identity of the glycoproteins and defining the structures of the glycans will empower efforts to design and develop selective therapeutics to mitigate galectin-3-mediated biological events.

Distribution of ACE2, CD147, CD26, and other SARS-CoV-2 associated molecules in tissues and immune cells in health and in asthma, COPD, obesity, hypertension, and COVID-19 risk factors

BACKGROUND

Morbidity and mortality from COVID-19 caused by novel coronavirus SARS-CoV-2 is accelerating worldwide, and novel clinical presentations of COVID-19 are often reported. The range of human cells and tissues targeted by SARS-CoV-2, its potential receptors and associated regulating factors are still largely unknown. The aim of our study was to analyze the expression of known and potential SARS-CoV-2 receptors and related molecules in the extensive collection of primary human cells and tissues from healthy subjects of different age and from patients with risk factors and known comorbidities of COVID-19.

METHODS

We performed RNA sequencing and explored available RNA-Seq databases to study gene expression and co-expression of ACE2, CD147 (BSG), and CD26 (DPP4) and their direct and indirect molecular partners in primary human bronchial epithelial cells, bronchial and skin biopsies, bronchoalveolar lavage fluid, whole blood, peripheral blood mononuclear cells (PBMCs), monocytes, neutrophils, DCs, NK cells, ILC1, ILC2, ILC3, CD4⁺ and CD8⁺ T cells, B cells, and plasmablasts. We analyzed the material from healthy children and adults, and from adults in relation to their disease or COVID-19 risk factor status.

RESULTS

ACE2 and TMPRSS2 were coexpressed at the epithelial sites of the lung and skin, whereas CD147 (BSG), cyclophilins (PPIA andPPIB), CD26 (DPP4), and related molecules were expressed in both epithelium and in immune cells. We also observed a distinct age-related expression profile of these genes in the PBMCs and T cells from healthy children and adults. Asthma, COPD, hypertension, smoking, obesity, and male gender status generally led to the higher expression of ACE2- and CD147-related genes in the bronchial biopsy, BAL, or blood. Additionally, CD147-related genes correlated positively with age and BMI. Interestingly, we also observed higher expression of CD147-related genes in the lesional skin of patients with atopic dermatitis.

CONCLUSIONS

Our data suggest different receptor repertoire potentially involved in the SARS-CoV-2 infection at the epithelial barriers and in the immune cells. Altered expression of these receptors related to age, gender, obesity and smoking, as well as with the disease status, might contribute to COVID-19 morbidity and severity patterns.

Distribution of ACE2, CD147, CD26, and other SARS-CoV-2 associated molecules in tissues and immune cells in health and in asthma, COPD, obesity, hypertension, and COVID-19 risk factors

Background

Morbidity and mortality from COVID‐19 caused by novel coronavirus SARS‐CoV‐2 is accelerating worldwide, and novel clinical presentations of COVID‐19 are often reported. The range of human cells and tissues targeted by SARS‐CoV‐2, its potential receptors and associated regulating factors are still largely unknown. The aim of our study was to analyze the expression of known and potential SARS‐CoV‐2 receptors and related molecules in the extensive collection of primary human cells and tissues from healthy subjects of different age and from patients with risk factors and known comorbidities of COVID‐19.

Methods

We performed RNA sequencing and explored available RNA‐Seq databases to study gene expression and co‐expression of ACE2, CD147 (BSG), and CD26 (DPP4) and their direct and indirect molecular partners in primary human bronchial epithelial cells, bronchial and skin biopsies, bronchoalveolar lavage fluid, whole blood, peripheral blood mononuclear cells (PBMCs), monocytes, neutrophils, DCs, NK cells, ILC1, ILC2, ILC3, CD4⁺ and CD8⁺ T cells, B cells, and plasmablasts. We analyzed the material from healthy children and adults, and from adults in relation to their disease or COVID‐19 risk factor status.

Results

ACE2 and TMPRSS2 were coexpressed at the epithelial sites of the lung and skin, whereas CD147 (BSG), cyclophilins (PPIA andPPIB), CD26 (DPP4), and related molecules were expressed in both epithelium and in immune cells. We also observed a distinct age‐related expression profile of these genes in the PBMCs and T cells from healthy children and adults. Asthma, COPD, hypertension, smoking, obesity, and male gender status generally led to the higher expression of ACE2‐ and CD147‐related genes in the bronchial biopsy, BAL, or blood. Additionally, CD147‐related genes correlated positively with age and BMI. Interestingly, we also observed higher expression of CD147‐related genes in the lesional skin of patients with atopic dermatitis.

Conclusions

Our data suggest different receptor repertoire potentially involved in the SARS‐CoV‐2 infection at the epithelial barriers and in the immune cells. Altered expression of these receptors related to age, gender, obesity and smoking, as well as with the disease status, might contribute to COVID‐19 morbidity and severity patterns.

Immunology of COVID-19: Mechanisms, clinical outcome, diagnostics, and perspectives-A report of the European Academy of Allergy and Clinical Immunology (EAACI)

With the worldwide spread of the novel severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) resulting in declaration of a pandemic by the World Health Organization (WHO) on March 11, 2020, the SARS‐CoV‐2‐induced coronavirus disease‐19 (COVID‐19) has become one of the main challenges of our times. The high infection rate and the severe disease course led to major safety and social restriction measures worldwide. There is an urgent need of unbiased expert knowledge guiding the development of efficient treatment and prevention strategies. This report summarizes current immunological data on mechanisms associated with the SARS‐CoV‐2 infection and COVID‐19 development and progression to the most severe forms. We characterize the differences between adequate innate and adaptive immune response in mild disease and the deep immune dysfunction in the severe multiorgan disease. The similarities of the human immune response to SARS‐CoV‐2 and the SARS‐CoV and MERS‐CoV are underlined. We also summarize known and potential SARS‐CoV‐2 receptors on epithelial barriers, immune cells, endothelium and clinically involved organs such as lung, gut, kidney, cardiovascular, and neuronal system. Finally, we discuss the known and potential mechanisms underlying the involvement of comorbidities, gender, and age in development of COVID‐19. Consequently, we highlight the knowledge gaps and urgent research requirements to provide a quick roadmap for ongoing and needed COVID‐19 studies.

Characterization of basigin monoclonal antibodies for receptor-mediated drug delivery to the brain

The brain uptake of biotherapeutics for brain diseases is hindered by the blood–brain barrier (BBB). The BBB selectively regulates the transport of large molecules into the brain and thereby maintains brain homeostasis. Receptor-mediated transcytosis (RMT) is one mechanism to deliver essential proteins into the brain parenchyma. Receptors expressed in the brain endothelial cells have been explored to ferry therapeutic antibodies across the BBB in bifunctional antibody formats. In this study, we generated and characterized monoclonal antibodies (mAbs) binding to the basigin receptor, which recently has been proposed as a target for RMT across the BBB. Antibody binding properties such as affinity have been demonstrated to be important factors for transcytosis capability and efficiency. Nevertheless, studies of basigin mAb properties' effect on RMT are limited. Here we characterize different basigin mAbs for their ability to associate with and subsequently internalize human brain endothelial cells. The mAbs were profiled to determine whether receptor binding epitope and affinity affected receptor-mediated uptake efficiency. By competitive epitope binning studies, basigin mAbs were categorized into five epitope bins. mAbs from three of the epitope bins demonstrated properties required for RMT candidates judged by binding characteristics and their superior level of internalization in human brain endothelial cells.

A lectin-based glycomic approach identifies FUT8 as a driver of radioresistance in oesophageal squamous cell carcinoma

PURPOSE

Radio-resistance is recognized as a main factor in the failure of radiotherapy in oesophageal squamous cell carcinoma (ESCC). Aberrant cell surface glycosylation has been reported to correlate with radio-resistance in different kinds of tumours. However, glycomic alterations and the corresponding enzymes associated with ESCC radio-resistance have not yet been defined.

METHODS

Two radioresistant cell lines, EC109R and TE-1R, were established from parental ESCC cell lines EC109 and TE-1 by fractionated irradiation. A lectin microarray was used to screen for altered glycan patterns. RNA-sequencing (RNA-seq) was employed to identify differentially expressed glycosyltransferases. Cell Counting Kit-8, colony formation and flow cytometry assays were used to measure cell viability and radiosensitivity. Expression of glycosyltransferase in ESCC tissues was assessed by immunohistochemistry. In vivo radiosensitivity was analysed using a nude mouse xenograft model. Downstream effectors of the enzyme were verified using a lectin-based pull-down assay combined with mass spectrometry.

RESULTS

We found that EC109R and TE-1R cells were more resistant to irradiation than the parental EC109 and TE-1 cells. Using lectin microarrays combined with RNA sequencing, we found that α1, 6-fucosyltransferase (FUT8) was overexpressed in the radioresistant ESCC cell lines. Both gain- and loss-of-function studies confirmed that FUT8 regulates the sensitivity of ESCC cells to irradiation. Importantly, we found that high FUT8 expression was positively linked to radio-resistance and a poor prognosis in ESCC patients who received radiation therapy. Moreover, FUT8 inhibition suppressed the growth and formation of xenograft tumours in nude mice after irradiation. Using a lectin-based pull-down assay and mass spectrometry, we found that CD147 could be glycosylated by FUT8. As expected, inhibition of CD147 partly reversed FUT8-induced radio-resistance in ESCC cells.

CONCLUSIONS

Our results indicate that FUT8 functions as a driver of radio-resistance in ESCC by targeting CD147. Therefore, FUT8 may serve as a marker for predicting the response to radiation therapy in patients with ESCC.

The phosphorylation of CD147 by Fyn plays a critical role for melanoma cells growth and metastasis

CD147, also known as extracellular matrix metalloproteinase inducer (EMMPRIN), is a transmembrane glycoprotein that is highly expressed in tumor cells, particularly melanoma cells, and plays critical roles in tumor cell metastasis through the regulation of matrix metalloprotease (MMP) expression. In this study, we identified Fyn as a novel interacting protein of CD147. Fyn is a member of the Src family of nonreceptor tyrosine kinases that regulates diverse physiological processes, such as T lymphocyte differentiation, through the TCR signaling pathway. Our findings demonstrated that Fyn directly phosphorylates CD147 at Y140 and Y183. Two phosphospecific antibodies against Y140 and Y183 were developed to validate the phosphorylation of CD147 by Fyn. Moreover, the CD147-FF (Y140F/Y183F) mutation impaired the interaction between CD147 and GnT-V, leading to decreased CD147 glycosylation and membrane recruitment. In addition, CD147-FF significantly blocked MMP-9 expression as well as cell migration. Moreover, we found that Fyn is overexpressed in clinical melanoma tissues as well as in melanoma cell lines. Knockdown of Fyn expression markedly attenuated the malignant phenotype of melanoma cells in vitro and in vivo through downregulation of CD147 phosphorylation, indicating that Fyn/CD147 is a potential target molecule in melanoma treatment. Finally, through virtual screening, we identified amodiaquine as a potential inhibitor targeting the Fyn/CD147 axis. Amodiaquine treatment dramatically inhibited the phosphorylation of CD147 by Fyn, thus attenuating melanoma cell growth and invasion in vitro and in vivo, suggesting that amodiaquine is a promising inhibitor for melanoma treatment.

High Throughput Multiplex SNP-analysis in Chronic Obstructive Pulmonary Disease and Lung Cancer

Background:

A number of human inflammatory diseases and tumors have been shown to cause alterations in the glycosylation pattern of plasma proteins in a specific manner. These highly variable and versatile post-translational modifications finetune protein functions by influencing sorting, folding, enzyme activity and subcellular localization. However, relatively little is known about regulatory factors of this procedure and about the accurate causative connection between glycosylation and disease.

Objective:

The aim of the present study was to investigate whether certain single nucleotide polymorphisms (SNPs) in genes encoding glycosyltransferases and glycosidases could be associated with elevated risk for chronic obstructive pulmonary disease (COPD) and lung adenocarcinoma.

Methods:

A total of 32 SNPs localized in genes related to N-glycosylation were selected for the association analysis. Polymorphisms with putative biological functions (missense or regulatory variants) were recruited. SNPs were genotyped by a TaqMan OpenArray platform. A single base extension-based method in combination with capillary gel electrophoresis was used for verification.

Results:

The TaqMan OpenArray approach provided accurate and reliable genotype data (global call rate: 94.9%, accuracy: 99.6%). No significant discrepancy was detected between the obtained and expected genotype frequency values (Hardy–Weinberg equilibrium) in the healthy control sample group in case of any SNP confirming reliable sampling and genotyping. Allele frequencies of the rs3944508 polymorphism localized in the 3’ UTR of the MGAT5 gene significantly differed between the sample groups compared.

Conclusion:

Our results suggest that the rs34944508 SNP might modulate the risk for lung cancer by influencing the expression of MGAT5. This enzyme catalyzes the addition of N-acetylglucosamine (GlcNAc) in beta 1-6 linkage to the alpha-linked mannose of biantennary N-linked oligosaccharides, thus, increasing branching that is the characteristic of invasive malignancies.

Receptor recognition by meningococcal type IV pili relies on a specific complex N-glycan

Bacterial infections are frequently based on the binding of lectin-like adhesins to specific glycan determinants exposed on host cell receptors. These interactions confer species-specific recognition and tropism for particular host tissues and represent attractive antibacterial targets. However, the wide structural diversity of carbohydrates hampers the characterization of specific glycan determinants. Here, we characterized the receptor recognition of type IV pili (Tfp), a key adhesive factor present in numerous bacterial pathogens, using Neisseria meningitidis as a model organism. We found that meningococcal Tfp specifically recognize a triantennary sialylated poly-N-acetyllactosamine-containing N-glycan exposed on the human receptor CD147/Basigin, while fucosylated derivatives of this N-glycan impaired bacterial adhesion. Corroborating the inhibitory role of fucosylation on receptor recognition, adhesion of the meningococcus on nonhuman cells expressing human CD147 required prior defucosylation. These findings reveal the molecular basis of the selective receptor recognition by meningococcal Tfp and thereby, identify a potential antibacterial target.

YIPF2 is a novel Rab-GDF that enhances HCC malignant phenotypes by facilitating CD147 endocytic recycle

An increased surface level of CIE (clathrin-independent endocytosis) proteins is a new feature of malignant neoplasms. CD147 is a CIE glycoprotein highly up-regulated in hepatocellular carcinoma (HCC). The ability to sort out the early endosome and directly target the recycling pathway confers on CD147 a prolonged surface half-life. However, current knowledge on CD147 trafficking to and from the cell-surface is limited. In this study, an MSP (membrane and secreted protein)-cDNA library was screened against EpoR/LR-F3/CD147EP-expressed cells by MAPPIT (mammalian protein–protein interaction trap). CD147 co-expressing with the new binder was investigated by GEPIA (gene expression profiling interactive analysis). The endocytosis, ER-Golgi trafficking and recycling of CD147 were measured by confocal imaging, flow cytometry, and biotin-labeled chase assays, respectively. Rab GTPase activation was checked by GST-RBD pull-down and MMP activity was measured by gelatin zymography. HCC malignant phenotypes were determined by cell adhesion, proliferation, migration, Transwell motility, and invasion assays. An ER-Golgi-resident transmembrane protein YIPF2 was identified as an intracellular binder to CD147. YIPF2 correlated and co-expressed with CD147, which is a survival predictor for HCC patients. YIPF2 is critical for CD147 glycosylation and trafficking functions in HCC cells. YIPF2 acts as a Rab-GDF (GDI-displacement factor) regulating three independent trafficking steps. First, YIPF2 recruits and activates Rab5 and Rab22a GTPases to the endomembrane structures. Second, YIPF2 modulates the endocytic recycling of CD147 through distinctive regulation on Rab5 and Rab22a. Third, YIPF2 mediates the mature processing of CD147 via the ER-Golgi trafficking route. Decreased YIPF2 expression induced a CD147 efficient delivery to the cell-surface, promoted MMP secretion, and enhanced the adhesion, motility, migration, and invasion behaviors of HCC cells. Thus, YIPF2 is a new trafficking determinant essential for CD147 glycosylation and transport. Our findings revealed a novel YIPF2-controlled ER-Golgi trafficking signature that promotes CD147-medated malignant phenotypes in HCC.

SP-8356, a (1S)-(-)-verbenone derivative, exerts in vitro and in vivo anti-breast cancer effects by inhibiting NF-κB signaling

Breast cancer exhibits high lethality in women because it is frequently detected at an advanced stage and aggressive forms such as triple-negative breast cancer (TNBC), which are often characterized by metastasis through colonization of secondary tumors. Thus, developing therapeutic agents that target the metastatic process is crucial to successfully treat aggressive breast cancer. We evaluated SP-8356, an anti-inflammatory synthetic verbenone derivative, with respect to its regulation of breast cancer cell behavior and cancer progression. Treatment of SP-8356 arrested cell cycle and reduced growth in various types of breast cancer cells with mild cytotoxicity. Particularly, SP-8356 significantly reduced the motility and invasiveness of TNBC cells. Assays using an in vivo xenograft mouse model confirmed the cell-specific anti-proliferative and anti-metastatic activity of SP-8356. Functional studies revealed that SP-8356 suppressed serum response element-dependent reporter gene expression and NF-κB-related signaling, resulting in downregulation of many genes related to cancer invasion. We conclude that SP-8356 suppresses breast cancer progression through multimodal functions, including inhibition of NF-κB signaling and growth-related signaling pathways.

N-Glycosylation in progression of skin cancer

Skin cancer can be classified as cutaneous malignant melanoma, basal cell carcinoma, and squamous cell carcinoma. Due to the high level of morbidity and mortality, skin cancer has become a global public health issue worldwide while the pathogenesis of skin cancer is still unclear. It is necessary to further identify the pathogenesis of skin cancer and find candidate targets to diagnose and treat skin cancer. A variety of factors are known to be associated with skin cancer including N-glycosylation, which partly explained the malignant behaviors of skin cancer. In this review, we retrieved databases such as PubMed and Web of Science to elucidate its relationship between glycosylation and skin cancer. We summarized some key glycosyltransferases and proteins during the process of N-glycosylation related to skin cancer, which was helpful to unmask the additional mechanism of skin cancer and find some novel targets of skin cancer.

Highly glycosylated CD147 promotes hemorrhagic transformation after rt-PA treatment in diabetes: a novel therapeutic target?

Background

Diabetes is known to be a main risk factor of post-stroke hemorrhagic transformation following recombinant tissue plasminogen activator (rt-PA) therapy. However, the mechanism through which diabetes exacerbates hemorrhagic transformation is insufficiently understood. We aimed to verify that CD147, the extracellular matrix metalloproteinase (MMP) inducer, played a vital role in the progress.

Methods

We performed middle cerebral artery occlusion on diabetic and non-diabetic rats, with or without rt-PA treatment, and then compared the glycosylation level of CD147, caveolin-1, MMPs activities, and blood-brain barrier (BBB) permeability. In vitro, tunicamycin treatment and genetic tools were used to produce non-glycosylated and lowly glycosylated CD147. An endogenous glucagon-like peptide-1 receptor (GLP-1R) agonist was used to downregulate the glycosylation of CD147 in vivo.

Results

Compared with non-diabetic rats, diabetic rats expressed higher levels of highly glycosylated CD147 in endothelium and astrocytes following rt-PA treatment accompanied by higher activity of MMPs and BBB permeability, in the middle cerebral artery occlusion model. Caveolin-1 was also overexpressed and co-localized with CD147 in astrocytes and endothelium in diabetic rats. In vitro, advanced glycation end products increased the expression of highly glycosylated CD147 in astrocytes and endothelial cells. Downregulating the glycosylation of CD147 lowered the activity of MMPs and promoted the expression of tight junction proteins. The expression of caveolin-1 in endothelial cells and astrocytes was not inhibited by tunicamycin, which revealed that caveolin-1 was an upstream of CD147. In vivo, GLP-1R agonist downregulated the glycosylation of CD147 and further reduced the activity of MMPs and protected the BBB in diabetic rats.

Conclusion

CD147 is essential for diabetes-associated rt-PA-induced hemorrhagic transformation, and downregulation of CD147 glycosylation is a promising therapy for neurovascular-unit repair after rt-PA treatment of patients with diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1460-1) contains supplementary material, which is available to authorized users.

Crosstalk in cancer resistance and metastasis

The main obstacles that lead to clinical failure in cancer treatment are the development of resistant to chemotherapy and a rise in invasive characteristics in cancer tumor cells due to prolonged chemotherapeutic processes. Recent studies have revealed some evidence about the existence of a direct relationship between development of drug resistance and triggering of invasive capability in tumor cells. Therefore, devising and application of chemotherapeutic procedures that are not prone to the development of chemotherapy resistance are necessary. Here, we focus on CD147, CD44, ANAX2, P-gp, MMPs, and UCH-L1 proteins involved in the crosstalk between metastasis and cancer treatment. We think that further structural and functional analysis of these proteins may direct scientists towards designing highly effective chemotherapy procedures.

β3GnT8 Promotes Colorectal Cancer Cells Invasion via CD147/MMP2/Galectin3 Axis

β1,3-N-acetylglucosaminyltransferase (β3GnT8) and β3GnT2 are key enzymes that catalyzes the formation of polylactosamine glycan structures by transferring GlcNAc to tetra-antennary β1-6-branched N-glycan and it also has an important effect on the progression of various types of human cancer. They have been reported to participate in tumor invasion and metastasis by regulating the expression of matrix metalloproteinases (MMPs), CD147, and polylactosamine. However, whether β3GnT8 and β3GnT2 play a role in colorectal cancer and, if so, the underlying mechanisms remain unclear. In our study, we detected the expression of β3GnT8, CD147, MMP2, and galectin3 by immunohistochemistry on 90 paraffin-embedded slices. And β3GnT8, CD147, MMP2, and galectin3 were over-expressed in colorectal cancer tissues. We found that overexpression of β3GnT8 and β3GnT2 promoted invasion of colorectal cancer cells, whereas knockdown of β3GnT8 and β3GnT2 inhibited the invasive activity. Mechanistically, β3GnT8 and β3GnT2 regulated the expression of HG-CD147 and the level of polylactosamines in colorectal cancer cells. Together, these results illustrate that the novel role and the molecular mechanism of β3GnT8 and β3GnT2 in promotion of colorectal cancer invasion. These results suggest that the potential use of β3GnT8 as a tumor target for the therapy of colorectal cancer.

N-glycosylation by N-acetylglucosaminyltransferase V enhances the interaction of CD147/basigin with integrin β1 and promotes HCC metastasis

While the importance of protein N-glycosylation in cancer cell migration is well appreciated, the precise mechanisms by which N-acetylglucosaminyltransferase V (GnT-V) regulates cancer processes remain largely unknown. In the current study, we report that GnT-V-mediated N-glycosylation of CD147/basigin, a tumor-associated glycoprotein that carries β1,6-N-acetylglucosamine (β1,6-GlcNAc) glycans, is upregulated during TGF-β1-induced epithelial-to-mesenchymal transition (EMT), which correlates with tumor metastasis in patients with hepatocellular carcinoma (HCC). Interruption of β1,6-GlcNAc glycan modification of CD147/basigin decreased matrix metalloproteinase (MMP) expression in HCC cell lines and affected the interaction of CD147/basigin with integrin β1. These results reveal that β1,6-branched glycans modulate the biological function of CD147/basigin in HCC metastasis. Moreover, we showed that the PI3K/Akt pathway regulates GnT-V expression and that inhibition of GnT-V-mediated N-glycosylation suppressed PI3K signaling. In summary, β1,6-branched N-glycosylation affects the biological function of CD147/basigin and these findings provide a novel approach for the development of therapeutic strategies targeting metastasis. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

CD147: a small molecule transporter ancillary protein at the crossroad of multiple hallmarks of cancer and metabolic reprogramming

Increased expression of CD147 in pancreatic cancer has been proposed to play a critical role in cancer progression via CD147 chaperone function for lactate monocarboxylate transporters (MCTs). Here, we show for the first time that CD147 interacts with membrane transporters beyond MCTs and exhibits a protective role for several of its interacting partners. CD147 prevents its interacting partner's proteasome-dependent degradation and incorrect plasma membrane localization through the CD147 transmembrane (TM) region. The interactions with transmembrane small molecule and ion transporters identified here indicate a central role of CD147 in pancreatic cancer metabolic reprogramming, particularly with respect to amino acid anabolism and calcium signaling. Importantly, CD147 genetic ablation prevents pancreatic cancer cell proliferation and tumor growth in vitro and in vivo in conjunction with metabolic rewiring towards amino acid anabolism, thus paving the way for future combined pharmacological treatments.

c-Jun-dependent β3GnT8 promotes tumorigenesis and metastasis of hepatocellular carcinoma by inducing CD147 glycosylation and altering N-glycan patterns

β3GnT8, a key polylactosamine synthase, plays a vital role in progression of various types of human cancer. The role of β3GnT8 in hepatocellular carcinoma (HCC) and the underlying mechanisms, however, remain largely unknown. In this study, we found that β3GnT8 and polylactosamine were highly expressed in HCC tissues compared with those in adjacent paracancer tissues. Overexpression of β3GnT8 promoted while knockdown of β3GnT8 inhibited HCC cell invasion and migration in vitro. Importantly, enhanced tumorigenesis was observed in nude mice inoculated with β3GnT8-overexpressing HCC cells, suggesting that β3GnT8 is important for HCC development in vitro and in vivo. Mechanistically, β3GnT8 modulated the N-glycosylation patterns of CD147 and altered the polylactosamine structures in HCC cells by physically interacting with CD147. In addition, our data showed the c-Jun could directly bind to the promoter of β3GnT8 gene and regulate β3GnT8 expression. β3GnT8 regulated HCC cell invasion and migration in a C-Jun-dependent manner. Collectively, our study identified β3GnT8 as a novel regulator for HCC invasion and tumorigenesis. Targeting β3GnT8 may be a potential therapeutic strategy against HCC.

The role of extracellular matrix metalloproteinase inducer glycosylation in regulating matrix metalloproteinases in periodontitis

BACKGROUND AND OBJECTIVE

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that may induce activation of matrix metalloproteinases (MMPs) and lead to the destruction of periodontal tissue. The level of EMMPRIN glycosylation might be involved in this process. This study aims to investigate the role of EMMPRIN glycosylation in regulating MMP-2 and MMP-9 during the progression of periodontitis.

MATERIAL AND METHODS

Gingival tissues were collected from patients with chronic periodontitis and from patients undergoing crown-lengthening procedures (healthy gingival tissue). Tissues were used for immunohistochemistry and double immunofluorescence. A human immortalized oral epithelial cell (HIOEC) line was stably transfected by an N-acetylglucosaminyltransferase-V (GnT-V) RNA interference (RNAi) lentivirus to suppress EMMPRIN glycosylation. Gene silence efficiency was detected by western blot, quantitative real-time PCR and immunofluorescence (IF) staining. An HIOEC/human gingival fibroblast (HGF) co-culture model and an individual culture model were used in this study. After exposure of cells to Porphyromonas gingivalis lipopolysaccharide (Pg. LPS), the expression of EMMPRIN, MMP-2 and MMP-9 were assessed by western blot, quantitative real-time PCR and IF, and the secretion of MMP-2 and MMP-9 were detected by gelatin-degradation assays.

RESULTS

Compared with the periodontally healthy group, patients with periodontitis showed increased expression of EMMPRIN on the gingival epithelial cell membrane. GnT-V, a key regulator of EMMPRIN glycosylation, was co-expressed with EMMPRIN in gingival epithelial cells in patients with periodontitis. Knockdown of GnT-V reduced the level of EMMPRIN glycosylation in HIOECs. Furthermore, in the HIOEC/HGF co-culture model, stimulation with Pg. LPS (10 μg/mL, 4 hours) promoted EMMPRIN glycosylation and increased the activities of MMP-2 and MMP-9, while suppression of EMMPRIN glycosylation by GnT-V knockdown reduced the synthesis and activities of MMP-2 and MMP-9 under Pg. LPS stimulation. Moreover, the gelatin-degradation assay showed that inhibition of EMMPRIN glycosylation suppressed the Pg. LPS-induced degradation of gelatin in the co-culture model.

CONCLUSION

We conclude that EMMPRIN glycosylation participates in the regulation of MMP-2 and MMP-9 production through mediating the interaction of HIOECs and HGFs. Inhibiting EMMPRIN glycosylation can reduce the activation of MMP-2 and MMP-9 and suppress the degradation of extracellular matrix (ECM) in the HIOEC/HGF co-culture model. Therefore, this study suggests that EMMPRIN glycosylation may affect the host immune-inflammatory response by regulating MMPs in periodontitis.

c-Jun-mediated β-1,3-N-acetylglucosaminyltransferase 8 expression: A novel mechanism regulating the invasion and metastasis of colorectal carcinoma cells

β-1,3-N-Acetylglucosaminyltransferase 8 (β3GnT8) is a key enzyme that catalyzes the formation of polylactosamine glycan structures by transferring GlcNAc to tetra-antennary β1-6-branched N-glycans, and it has been reported to participate in tumor invasion and metastasis by regulating the expression of matrix metalloproteinases (MMPs), cluster of differentiation 147 (CD147) and polylactosamine. By contrast, the role of transcription factor c-Jun in cell cycle progression has been well established. c-Jun has an important role in tumor cell invasion and metastasis. However, the precise molecular mechanisms by which c-Jun regulates these processes in colorectal carcinoma cells are not fully elucidated. In the present study, c-Jun had a significant effect on the invasive and migratory abilities of SW480 and LoVo cells. Additionally, overexpression of c-Jun was able to increase the expression of β3GnT8, MMPs, CD147 and polylactosamine. Similarly, knockdown of c-Jun was able to decrease the expression of β3GnT8, MMPs, CD147 and polylactosamine. These results suggest that c-Jun is able to regulate colorectal carcinoma cell invasion and metastasis via β3GnT8. A chromatin immunoprecipitation assay indicated that c-Jun is able to bind directly to the promoter regions of β3GnT8 in SW480 and LoVo cells. This leads to transcriptional activation of β3GnT8, which in turn regulates the expression of tumor invasion and metastasis-associated genes. The results of the present study demonstrate a novel mechanism underlying colorectal carcinoma cell invasion and metastasis, where β3GnT8 is transcriptionally activated via c-Jun binding to its promoter.

Cytoplasmic fragment of CD147 generated by regulated intramembrane proteolysis contributes to HCC by promoting autophagy

Hepatocellular carcinoma (HCC) is one of the most lethal and prevalent cancers worldwide. CD147 (EMMPRIN or basigin) is a leading gene relating to hepatocarcinogenesis and metastasis, and is detected in transmembrane, exosome or circulating forms in HCC patients. The endosome recycling of CD147 further enhances the function of this oncoprotein from a dynamic perspective. However, previous studies about CD147 mainly focused on one separate form, and little attention has been paid to how the different forms of tumor-derived CD147 changes. Moreover, uncovering the roles of the residual C-terminal portion of CD147 after shedding is inevitable to fully understand CD147 promoting tumor progression. In this study, we discovered that under low-cholesterol condition, CD147 endocytosis is inhibited but its shedding mediated by ADAM10 is enhanced. Further procession of residual CD147 in the lysosome produces nuclear-localized CD147-ICD (intracellular domain of CD147), which contributes to autophagy through NF-κB–TRAIL–caspase8–ATG3 axis. As autophagy endows cancer cells with increased adaptability to chemotherapy, and HAb 18 (a specific antibody targeting CD147) inhibits CD147 shedding and sequential CD147-ICD enhances autophagy, we found the combination of HAb 18 and cisplatin exhibited marked antitumor efficiency.

Glycosylation of matrix metalloproteases and tissue inhibitors: present state, challenges and opportunities

Current knowledge about the glycosylation of matrix metalloproteinases (MMPs) and the inhibitors of metalloproteinases (TIMPs) is reviewed. Whereas structural and functional aspects of the glycobiology of many MMPs is unknown, research on MMP-9 and MMP-14 glycosylation reveals important functional implications, such as altered inhibitor binding and cellular localization. This, together with the fact that MMPs contain conserved and many potential attachment sites for N-linked and O-linked oligosaccharides, proves the need for further studies on MMP glycobiology.

Matrix metalloproteases (MMPs) are crucial components of a complex and dynamic network of proteases. With a wide range of potential substrates, their production and activity are tightly controlled by a combination of signalling events, zymogen activation, post-translational modifications and extracellular inhibition. Slight imbalances may result in the initiation or progression of specific disease states, such as cancer and pathological inflammation. As glycosylation modifies the structures and functions of glycoproteins and many MMPs contain N- or O-linked oligosaccharides, we examine, compare and evaluate the evidence for whether glycosylation affects MMP catalytic activity and other functions. It is interesting that the catalytic sites of MMPs do not contain O-linked glycans, but instead possess a conserved N-linked glycosylation site. Both N- and O-linked oligosaccharides, attached to specific protein domains, endow these domains with novel functions such as the binding to lectins, cell-surface receptors and tissue inhibitors of metalloproteases (TIMPs). Validated glycobiological data on N- and O-linked oligosaccharides of gelatinase B/MMP-9 and on O-linked structures of membrane-type 1 MMP/MMP-14 indicate that in-depth research of other MMPs may yield important insights, e.g. about subcellular localizations and functions within macromolecular complexes.

Emmprin, released as a microvesicle in epithelioid sarcoma, interacts with fibroblasts

Emmprin (extracellular matrix metalloproteinase inducer, CD147) is a glycosylated transmembrane protein, consisting of two immunoglobulin domains, that stimulates the production of matrix metalloproteinases (MMPs) by tumor-associated fibroblasts. These effects play important roles in tumor invasion and metastasis. However, the precise mechanisms by which emmprin acts on fibroblasts have not been fully elucidated, especially in sarcoma cells. Previously, we demonstrated that emmprin, expressed in conditioned medium collected from the epithelioid sarcoma cell line (FU-EPS-1), stimulates MMP-2 production via interactions with fibroblasts. In this study, we used microvesicles derived from sarcoma cells, and determined whether emmprin exists in the microvesicles, which enhance the production of MMP-2 via fibroblasts. Microvesicles released from FU-EPS-1 cells were shown to contain full-length emmprin, identified as a 45-kDa protein characterized by polylactosamine glycosylation. Microvesicles collected from FU-EPS-1 cells transfected with emmprin-specific siRNA or transduced with shRNA displayed significantly reduced MMP-2 production by fibroblasts compared with those from control-transfected cells. Our findings show that emmprin is released through microvesicle shedding in sarcoma cells, and emmprin in microvesicles regulates MMP-2 production by influencing the activity of fibroblasts located at sites distant from the tumor cells.

β3GnT8 Promotes Gastric Cancer Invasion by Regulating the Glycosylation of CD147

β1, 3-N-acetylglucosminyltransferase 8(β3GnT8) synthesizes a unique cabohydrate structure known as polylactosamine, and plays a vital role in progression of various human cancer types. However, its involvement in gastric cancer remains unclear. In this study, we analyzed the expression and clinical significance of β3GnT8 by Western blot in 6 paired fresh gastric cancer tissues, noncancerous tissues and immunohistochemistry on 110 paraffin-embedded slices. β3GnT8 was found to be over-expressed in gastric cancer tissues, which correlated with lymph node metastasis and TNM stage. Forced the expression of β3GnT8 promoted migration and invasion of gastric cancer cells, whereas β3GnT8 knockdown led to the opposite results. Further studies showed that the regulated β3GnT8 could convert the heterogeneous N-glycosylated forms of CD147 and change the polylactosamine structures carried on CD147. In addition, our data suggested the annexin A2 (ANXA2) to be an essential interaction partner of β3GnT8 during the process of CD147 glycosylation. Collectively, these results provide a novel molecular mechanism for β3GnT8 in promotion of gastric cancer invasion and metastasis. Targeting β3GnT8 could serve as a new strategy for future gastric cancer therapy.

F-Box Protein FBXO22 Mediates Polyubiquitination and Degradation of CD147 to Reverse Cisplatin Resistance of Tumor Cells

Drug resistance remains a major clinical obstacle to successful treatment of cancer. As posttranslational modification is becoming widely recognized to affect the function of oncoproteins, targeting specific posttranslational protein modification provides an attractive strategy for anticancer drug development. CD147 is a transmembrane glycoprotein contributing to chemo-resistance of cancer cells in a variety of human malignancies. Ubiquitination is an important posttranslational modification mediating protein degradation. Degradation of oncoproteins, CD147 included, emerges as an attractive alternative for tumor inhibition. However, the ubiquitination of CD147 remains elusive. Here in this study, we found that deletion of the CD147 intracellular domain (CD147-ICD) prolonged the half-life of CD147 in HEK293T cells, and we identified that CD147-ICD interacts with FBXO22 using mass spectrometry and Western blot. Then, we demonstrated that FBXO22 mediates the polyubiquitination and degradation of CD147 by recognizing CD147-ICD. While knocking down of FBXO22 prolonged the half-life of CD147 in HEK293T cells, we found that FBXO22 regulates CD147 protein turnover in SMMC-7721, Huh-7 and A549 cells. Moreover, we found that the low level of FBXO22 contributes to the accumulation of CD147 and thereafter the cisplatin resistance of A549/DDP cells. To conclude, our study demonstrated that FBXO22 mediated the polyubiquitination and degradation of CD147 by interacting with CD147-ICD, and CD147 polyubiquitination by FBXO22 reversed cisplatin resistance of tumor cells.

A novel small-molecule compound targeting CD147 inhibits the motility and invasion of hepatocellular carcinoma cells

CD147, a type I transmembrane glycoprotein, is highly expressed in various cancer types and plays important roles in tumor progression, especially by promoting the motility and invasion of hepatocellular carcinoma (HCC) cells. These crucial roles make CD147 an attractive target for therapeutic intervention in HCC, but no small-molecule inhibitors of CD147 have been developed to date. To identify a candidate inhibitor, we used a pharmacophore model derived from the structure of CD147 to virtually screen over 300,000 compounds. The 100 highest-ranked compounds were subjected to biological assays, and the most potent one, dubbed AC-73 (ID number: AN-465/42834501), was studied further. We confirmed that AC-73 targeted CD147 and further demonstrated it can specifically disrupt CD147 dimerization. Moreover, molecular docking and mutagenesis experiments showed that the possible binding sites of AC-73 on CD147 included Glu64 and Glu73 in the N-terminal IgC2 domain, which two residues are located in the dimer interface of CD147. Functional assays revealed that AC-73 inhibited the motility and invasion of typical HCC cells, but not HCC cells that lacked the CD147 gene, demonstrating on-target action. Further, AC-73 reduced HCC metastasis by suppressing matrix metalloproteinase (MMP)-2 via down-regulation of the CD147/ERK1/2/signal transducer and activator of transcription 3 (STAT3) signaling pathway. Finally, AC-73 attenuated progression in an orthotopic nude mouse model of liver metastasis, suggesting that AC-73 or its derivatives have potential for use in HCC intervention. We conclude that the novel small-molecule inhibitor AC-73 inhibits HCC mobility and invasion, probably by disrupting CD147 dimerization and thereby mainly suppressing the CD147/ERK1/2/STAT3/MMP-2 pathways, which are crucial for cancer progression.

N-linked glycosylation at Asn152 on CD147 affects protein folding and stability: promoting tumour metastasis in hepatocellular carcinoma

Cluster of differentiation 147 (CD147), also known as extracellular matrix metalloproteinase inducer, is a transmembrane glycoprotein that mediates oncogenic processes partly through N-glycosylation modifications. N-glycosylation has been demonstrated to be instrumental for the regulation of CD147 function during malignant transformation. However, the role that site-specific glycosylation of CD147 plays in its defective function in hepatocellular carcinomacells needs to be determined. Here, we demonstrate that the modification of N-glycosylation at Asn152 on CD147 strongly promotes hepatocellular carcinoma (HCC) invasion and migration. After the removal of N-glycans at Asn152, CD147 was more susceptible to degradation by ER-localized ubiquitin ligase-mediated endoplasmic reticulum-associated degradation (ERAD). Furthermore, N-linked glycans at Asn152 were required for CD147 to acquire and maintain proper folding in the ER. Moreover, N-linked glycans at Asn152 functioned as a recognition motif that was directly mediated by the CNX quality control system. Two phases in the retention-based ER chaperones system drove ER-localized CD147 trafficking to degradation. Deletion of N-linked glycosylation at Asn152 on CD147 significantly suppressed in situ tumour metastasis. These data could potentially shed light on the molecular regulation of CD147 through glycosylation and provide a valuable means of developing drugs that target N-glycans at Asn152 on CD147.