Heparan sulfate proteoglycans

Insight into microRNAs-Mediated Communication between Liver and Brain: A Possible Approach for Understanding Acute Liver Failure?

Acute liver failure (ALF) is a life-threatening consequence of hepatic function rapid loss without preexisting liver disease. ALF may result in a spectrum of neuropsychiatric symptoms that encompasses cognitive impairment, coma, and often death, collectively defined as acute hepatic encephalopathy. Micro RNAs are small non-coding RNAs that modulate gene expression and are extensively verified as biomarker candidates in various diseases. Our systematic literature review based on the last decade's reports involving a total of 852 ALF patients, determined 205 altered circulating miRNAs, of which 25 miRNAs were altered in the blood, regardless of study design and methodology. Selected 25 miRNAs, emerging predominantly from the analyses of samples obtained from acetaminophen overdosed patients, represent the most promising biomarker candidates for a diagnostic panel for symptomatic ALF. We discussed the role of selected miRNAs in the context of tissue-specific origin and its possible regulatory role for molecular pathways involved in blood-brain barrier function. The defined several common pathways for 15 differently altered miRNAs were relevant to cellular community processes, indicating loss of intercellular, structural, and functional components, which may result in blood-brain barrier impairment and brain dysfunction. However, a causational relationship between circulating miRNAs differential expression, and particular clinical features of ALF, has to be demonstrated in a further study.

A Comprehensive View on the Host Factors and Viral Proteins Associated With Porcine Epidemic Diarrhea Virus Infection

Porcine epidemic diarrhea virus (PEDV), a coronavirus pathogen of the pig intestinal tract, can cause fatal watery diarrhea in piglets, thereby causing huge economic losses to swine industries around the world. The pathogenesis of PEDV has intensively been studied; however, the viral proteins of PEDV and the host factors in target cells, as well as their interactions, which are the foundation of the molecular mechanisms of viral infection, remain to be summarized and updated. PEDV has multiple important structural and functional proteins, which play various roles in the process of virus infection. Among them, the S and N proteins play vital roles in biological processes related to PEDV survival via interacting with the host cell proteins. Meanwhile, a number of host factors including receptors are required for the infection of PEDV via interacting with the viral proteins, thereby affecting the reproduction of PEDV and contributing to its life cycle. In this review, we provide an updated understanding of viral proteins and host factors, as well as their interactions in terms of PEDV infection. Additionally, the effects of cellular factors, events, and signaling pathways on PEDV infection are also discussed. Thus, these comprehensive and profound insights should facilitate for the further investigations, control, and prevention of PEDV infection.

Blocking of inflammatory heparan sulfate domains by specific antibodies is not protective in experimental glomerulonephritis

Glomerulonephritis is an acquired serious glomerular disease, which involves the interplay of many factors such as cytokines, chemokines, inflammatory cells, and heparan sulfate (HS). We previously showed that blocking of inflammatory heparan sulfate domains on cultured glomerular endothelium by specific anti-HS single chain antibodies reduced polymorphonuclear cell (PMN) adhesion and chemokine binding. We hypothesized that injection of anti-HS antibodies in PMN-driven experimental glomerulonephritis should reduce glomerular influx of PMNs and thereby lead to a better renal outcome. In contrast to our hypothesis, co-injection of anti-HS antibodies did not alter the final outcome of anti-glomerular basement membrane (anti-GBM)-induced glomerulonephritis. Glomerular PMN influx, normally peaking 2 hours after induction of glomerulonephritis with anti-GBM IgG was not reduced by co-injection of anti-HS antibodies. Four days after induction of glomerulonephritis, albuminuria, renal function, glomerular hyalinosis and fibrin deposition were similar in mice treated and not treated with anti-HS antibodies. Interestingly, we observed transient effects in mice co-injected with anti-HS antibodies compared to mice that did not receive anti-HS antibodies: (i) a decreased renal function 2 hours and 1 day after induction of glomerulonephritis; (ii) an increased albuminuria after 2 hours and 1 day; (iii) an increased glomerular fibrin deposition after 1 day; (iv) a reduced glomerular macrophage influx after 1 day; (v) a sustained glomerular presence of PMNs at day 1 and 4, accompanied by an increased renal expression of IL-6, CXCL1, ICAM-1, L-selectin, CD11b and NF-κB. The mechanism underlying these observations induced by anti-HS antibodies remains unclear, but may be explained by a temporarily altered glycocalyx and/or altered function of PMNs due to the binding of anti-HS antibodies. Nevertheless, the evaluated anti-HS antibodies do not show therapeutic potential in anti-GBM-induced glomerulonephritis. Future research should evaluate other strategies to target HS domains involved in inflammatory processes during glomerulonephritis.

Curcumin May Prevent Basement Membrane Disassembly by Matrix Metalloproteinases and Progression of the Bladder Cancer

Authors present a review of crucial mechanisms contributing to the invasion of the basement membrane (BM) of the urothelium by cancer cells and to the progression of bladder cancer (BC). The breeching of the urothelial BM, facilitated by an aberrant activation of matrix metalloproteinases (MMP) is particularly perilous. Inhibition of activation of these proteinases constitutes a logic opportunity to restrain progression. Because of limited efficacy of current therapeutic methods, the search for the development of alternative approaches constitutes "the hot spot" of modern oncology. Recent studies revealed significant anticancer potential of natural phytochemicals. Especially, curcumin has emerged as a one of the most promising phytochemicals and showed its efficacy in several human malignancies. Therefore, this article addresses experimental and clinical data indicating multi-directional inhibitory effect of curcumin on the growth of bladder cancer. We particularly concentrate on the mechanisms, by which curcumin inhibits the MMP's activities, thereby securing BM integrity and alleviating the eventual cancer invasion into the bladder muscles. Authors review the recently accumulating data, that curcumin constitutes a potent factor contributing to the more effective treatment of the bladder cancer.

[Tetraspanins and syndecans: Partners in crime for 'dealing' exosomes?]

Exosomes are small extracellular vesicles derived from endosomal compartments. The molecular mechanisms supporting the biology of exosomes, from their biogenesis to their internalization by target cells, rely on 'dedicated' membrane proteins. These mechanisms of action need to be further clarified. This will help to better understand how exosome composition and heterogeneity are established. This would also help to rationalize their use as source of biomarkers and therapeutic tools. Here we discuss how syndecans and tetraspanins, two families of membrane scaffold proteins, cooperate to regulate different steps of exosome biology.

Cell-derived extracellular matrix enhanced by collagen-binding domain-decorated exosomes to promote neural stem cells neurogenesis

Enhancing neurogenesis of neural stem cells (NSCs) is crucial in stem cell therapy for neurodegenerative diseases. Within the extracellular microenvironment, extracellular matrix (ECM) plays a pivotal role in modulating cell behaviors. However, a single ECM biomaterial is not sufficient to establish an ideal microenvironment. As multifunctional nanocarriers, exosomes display tremendous advantages for the treatments of various diseases. Herein, collagen binding domain peptide-modified exosomes (CBD-Exo) were obtained from the SH-SY5Y cell line infected with lentivirus particles encoding CBD-lysosome associated membrane glycoprotein 2b (CBD-Lamp2b) to improve the binding efficiency of exosomes and ECM. An exosomes-functionalized ECM (CBD-Exo/ECM) was then constructed via the interaction between CBD and collagen in ECM. Then, CBD-Exo/ECM was employed as a carrier for NSCs culture. The results showed that CBD-Exo/ECM can support the neurogenesis of NSCs with the percentage of proliferation marker EdU-positive (35.8% ± 0.47% vs 21.9% ± 2.32%) and neuron maker Tuj-1-positive (55.8% ± 0.47% vs 30.6% ± 2.62%) were both significantly increased in the exosomes-functionalized ECM system. This exosomes-functionalized ECM was capable to promote the cell proliferation and accelerate neuronal differentiation of NSCs, providing a potential biomedical material for stem cell application in tissue engineering and regenerative medicine.

Clinicopathological and Molecular Prognostic Classifier for Intermediate/High-Risk Clear Cell Renal Cell Carcinoma

Simple Summary

In this report, we identified biomarkers for tumor progression from tissue samples of intermediate/high-risk ccRCC. Using the molecular findings and the clinical data, we developed an improved prognostic model which could help to provide better individualized management recommendations.

Abstract

The probability of tumor progression in intermediate/high-risk clear cell renal cell carcinoma (ccRCC) is highly variable, underlining the lack of predictive accuracy of the current clinicopathological factors. To develop an accurate prognostic classifier for these patients, we analyzed global gene expression patterns in 13 tissue samples from progressive and non-progressive ccRCC using Illumina Hi-seq 4000. Expression levels of 22 selected differentially expressed genes (DEG) were assessed by nCounter analysis in an independent series of 71 ccRCCs. A clinicopathological-molecular model for predicting tumor progression was developed and in silico validated in a total of 202 ccRCC patients using the TCGA cohort. A total of 1202 DEGs were found between progressive and non-progressive intermediate/high-risk ccRCC in RNAseq analysis, and seven of the 22 DEGs selected were validated by nCounter. Expression of HS6ST2, pT stage, tumor size, and ISUP grade were found to be independent prognostic factors for tumor progression. A risk score generated using these variables was able to distinguish patients at higher risk of tumor progression (HR 7.27; p < 0.001), consistent with the results obtained from the TCGA cohort (HR 2.74; p < 0.002). In summary, a combined prognostic algorithm was successfully developed and validated. This model may aid physicians to select high-risk patients for adjuvant therapy.

The Glomerular Endothelium Restricts Albumin Filtration

Inflammatory activation and/or dysfunction of the glomerular endothelium triggers proteinuria in many systemic and localized vascular disorders. Among them are the thrombotic microangiopathies, many forms of glomerulonephritis, and acute inflammatory episodes like sepsis and COVID-19 illness. Another example is the chronic endothelial dysfunction that develops in cardiovascular disease and in metabolic disorders like diabetes. While the glomerular endothelium is a porous sieve that filters prodigious amounts of water and small solutes, it also bars the bulk of albumin and large plasma proteins from passing into the glomerular filtrate. This endothelial barrier function is ascribed predominantly to the endothelial glycocalyx with its endothelial surface layer, that together form a relatively thick, mucinous coat composed of glycosaminoglycans, proteoglycans, glycolipids, sialomucins and other glycoproteins, as well as secreted and circulating proteins. The glycocalyx/endothelial surface layer not only covers the glomerular endothelium; it extends into the endothelial fenestrae. Some glycocalyx components span or are attached to the apical endothelial cell plasma membrane and form the formal glycocalyx. Other components, including small proteoglycans and circulating proteins like albumin and orosomucoid, form the endothelial surface layer and are bound to the glycocalyx due to weak intermolecular interactions. Indeed, bound plasma albumin is a major constituent of the endothelial surface layer and contributes to its barrier function. A role for glomerular endothelial cells in the barrier of the glomerular capillary wall to protein filtration has been demonstrated by many elegant studies. However, it can only be fully understood in the context of other components, including the glomerular basement membrane, the podocytes and reabsorption of proteins by tubule epithelial cells. Discovery of the precise mechanisms that lead to glycocalyx/endothelial surface layer disruption within glomerular capillaries will hopefully lead to pharmacological interventions that specifically target this important structure.

Interactions of renin-angiotensin system and COVID-19: the importance of daily rhythms in ACE2, ADAM17 and TMPRSS2 expression

Angiotensin-converting enzyme 2 (ACE2) was identified as a molecule that mediates the cellular entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several membrane molecules of the host cell must cooperate in this process. While ACE2 serves in a membrane receptor-mediating interaction with the surface spike (S) glycoprotein of SARS-CoV-2 located on the virus envelope, enzyme A disintegrin and metalloproteinase 17 (ADAM17) regulates ACE2 availability on the membrane and transmembrane protease serine 2 (TMPRSS2) facilitates virus-cell membrane fusion. Interestingly, ACE2, ADAM17 and TMPRSS2 show a daily rhythm of expression in at least some mammalian tissue. The circadian system can also modulate COVID-19 progression via circadian control of the immune system (direct, as well as melatonin-mediated) and blood coagulation. Virus/ACE2 interaction causes ACE2 internalization into the cell, which is associated with suppressed activity of ACE2. As a major role of ACE2 is to form vasodilatory angiotensin 1-7 from angiotensin II (Ang II), suppressed ACE2 levels in the lung can contribute to secondary COVID-19 complications caused by up-regulated, pro-inflammatory vasoconstrictor Ang II. This is supported by the positive association of hypertension and negative COVID-19 prognosis although this relationship is dependent on numerous comorbidities. Hypertension treatment with inhibitors of renin-angiotensin system does not negatively influence prognosis of COVID-19 patients. It seems that tissue susceptibility to SARS-CoV-2 shows negative correlation to ACE2 expression. However, in lungs of infected patient, a high ACE2 expression is associated with better outcome, compared to low ACE2 expression. Manipulation of soluble ACE2 levels is a promising COVID-19 therapeutic strategy.

SARS-CoV-2 Spike triggers barrier dysfunction and vascular leak via integrins and TGF-β signaling

Severe COVID-19 is associated with epithelial and endothelial barrier dysfunction within the lung as well as in distal organs. While it is appreciated that an exaggerated inflammatory response is associated with barrier dysfunction, the triggers of this pathology are unclear. Here, we report that cell-intrinsic interactions between the Spike (S) glycoprotein of SARS-CoV-2 and epithelial/endothelial cells are sufficient to trigger barrier dysfunction in vitro and vascular leak in vivo , independently of viral replication and the ACE2 receptor. We identify an S-triggered transcriptional response associated with extracellular matrix reorganization and TGF-β signaling. Using genetic knockouts and specific inhibitors, we demonstrate that glycosaminoglycans, integrins, and the TGF-β signaling axis are required for S-mediated barrier dysfunction. Our findings suggest that S interactions with barrier cells are a contributing factor to COVID-19 disease severity and offer mechanistic insight into SARS-CoV-2 triggered vascular leak, providing a starting point for development of therapies targeting COVID-19 pathogenesis.

Revisiting the grammar of Tau aggregation and pathology formation: how new insights from brain pathology are shaping how we study and target Tauopathies

Converging evidence continues to point towards Tau aggregation and pathology formation as central events in the pathogenesis of Alzheimer's disease and other Tauopathies. Despite significant advances in understanding the morphological and structural properties of Tau fibrils, many fundamental questions remain about what causes Tau to aggregate in the first place. The exact roles of cofactors, Tau post-translational modifications, and Tau interactome in regulating Tau aggregation, pathology formation, and toxicity remain unknown. Recent studies have put the spotlight on the wide gap between the complexity of Tau structures, aggregation, and pathology formation in the brain and the simplicity of experimental approaches used for modeling these processes in research laboratories. Embracing and deconstructing this complexity is an essential first step to understanding the role of Tau in health and disease. To help deconstruct this complexity and understand its implication for the development of effective Tau targeting diagnostics and therapies, we firstly review how our understanding of Tau aggregation and pathology formation has evolved over the past few decades. Secondly, we present an analysis of new findings and insights from recent studies illustrating the biochemical, structural, and functional heterogeneity of Tau aggregates. Thirdly, we discuss the importance of adopting new experimental approaches that embrace the complexity of Tau aggregation and pathology as an important first step towards developing mechanism- and structure-based therapies that account for the pathological and clinical heterogeneity of Alzheimer's disease and Tauopathies. We believe that this is essential to develop effective diagnostics and therapies to treat these devastating diseases.

Tight Junctions of the Neurovascular Unit

The homeostatic balance of the brain and retina is maintained by the presence of the blood-brain and inner blood-retinal barrier (BBB/iBRB, respectively) which are highly specialized barriers. Endothelial cells forming the lining of these blood vessels are interconnected by the presence of tight junctions which form the BBB and iBRB. These tight junctions, formed of numerous interacting proteins, enable the entry of molecules into neural tissues while restricting the entry of harmful material such as anaphylatoxins, bacteria and viruses. If the tight junction complex becomes dysregulated due to changes in expression levels of one or more of the components, this can have detrimental effects leading to brain and retinal pathology.

Heparan Sulfate Biosynthesis and Sulfation Profiles as Modulators of Cancer Signalling and Progression

Heparan Sulfate Proteoglycans (HSPGs) are important cell surface and Extracellular Matrix (ECM) maestros involved in the orchestration of multiple cellular events in physiology and pathology. These glycoconjugates bind to various bioactive proteins via their Heparan Sulfate (HS) chains, but also through the protein backbone, and function as scaffolds for protein-protein interactions, modulating extracellular ligand gradients, cell signalling networks and cell-cell/cell-ECM interactions. The structural features of HS chains, including length and sulfation patterns, are crucial for the biological roles displayed by HSPGs, as these features determine HS chains binding affinities and selectivity. The large HS structural diversity results from a tightly controlled biosynthetic pathway that is differently regulated in different organs, stages of development and pathologies, including cancer. This review addresses the regulatory mechanisms underlying HS biosynthesis, with a particular focus on the catalytic activity of the enzymes responsible for HS glycan sequences and sulfation motifs, namely D-Glucuronyl C5-Epimerase, N- and O-Sulfotransferases. Moreover, we provide insights on the impact of different HS structural epitopes over HSPG-protein interactions and cell signalling, as well as on the effects of deregulated expression of HS modifying enzymes in the development and progression of cancer. Finally, we discuss the clinical potential of HS biosynthetic enzymes as novel targets for therapy, and highlight the importance of developing new HS-based tools for better patients' stratification and cancer treatment.

Broad-Spectrum Antiviral Peptides and Polymers

As the human cost of the pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still being witnessed worldwide, the development of broad-spectrum antiviral agents against emerging and re-emerging viruses is seen as a necessity to hamper the spread of infections. Various targets during the viral life-cycle can be considered to inhibit viral infection, from viral attachment to viral fusion or replication. Macromolecules represent a particularly attractive class of therapeutics due to their multivalency and versatility. Although several antiviral macromolecules hold great promise in clinical applications, the emergence of resistance after prolonged exposure urges the need for improved solutions. In the present article, the recent advancement in the discovery of antiviral peptides and polymers with diverse structural features and antiviral mechanisms is reviewed. Future perspectives, such as, the development of virucidal peptides/polymers and their coatings against SARS-CoV-2 infection, standardization of antiviral testing protocols, and use of artificial intelligence or machine learning as a tool to accelerate the discovery of antiviral macromolecules, are discussed.

A Genome-Wide CRISPR/Cas9-Based Screen Identifies Heparan Sulfate Proteoglycans as Ligands of Killer-Cell Immunoglobulin-Like Receptors

While human leukocyte antigen (HLA) and HLA-like proteins comprise an overwhelming majority of known ligands for NK-cell receptors, the interactions of NK-cell receptors with non-conventional ligands, particularly carbohydrate antigens, is less well described. We previously found through a bead-based HLA screen that KIR3DS1, a formerly orphan member of the killer-cell immunoglobulin-like receptor (KIR) family, binds to HLA-F. In this study, we assessed the ligand binding profile of KIR3DS1 to cell lines using Fc fusion constructs, and discovered that KIR3DS1-Fc exhibited binding to several human cell lines including ones devoid of HLA. To identify these non-HLA ligands, we developed a magnetic enrichment-based genome-wide CRISPR/Cas9 knock-out screen approach, and identified enzymes involved in the biosynthesis of heparan sulfate as crucial for the binding of KIR3DS1-Fc to K562 cells. This interaction between KIR3DS1 and heparan sulfate was confirmed via surface plasmon resonance, and removal of heparan sulfate proteoglycans from cell surfaces abolished KIR3DS1-Fc binding. Testing of additional KIR-Fc constructs demonstrated that KIR family members containing a D0 domain (KIR3DS1, KIR3DL1, KIR3DL2, KIR2DL4, and KIR2DL5) bound to heparan sulfate, while those without a D0 domain (KIR2DL1, KIR2DL2, KIR2DL3, and KIR2DS4) did not. Overall, this study demonstrates the use of a genome-wide CRISPR/Cas9 knock-out strategy to unbiasedly identify unconventional ligands of NK-cell receptors. Furthermore, we uncover a previously underrecognized binding of various activating and inhibitory KIRs to heparan sulfate proteoglycans that may play a role in NK-cell receptor signaling and target-cell recognition.

Keratinocyte growth factor in focus: A comprehensive review from structural and functional aspects to therapeutic applications of palifermin

Palifermin (Kepivance™) is the first therapeutic approved by the Food and Drug Administration for preventing and managing the oral mucositis provoked by myelotoxic and mucotoxic therapies. Palifermin is a recombinant protein generated from human keratinocyte growth factor (KGF) and imitates the function of endogenous KGF. KGF is an epithelial mitogen involved in various biological processes which belongs to the FGF family. KGF possesses a high level of receptor specificity and plays an important role in tissue repair and maintaining of the mucosal barrier integrity. Based on these unique features, palifermin was developed to enhance the growth of damaged epithelial tissues. Administration of palifermin has shown success in the reduction of toxicities of chemotherapy and radiotherapy, and improvement of the patient's quality of life. Notwithstanding all merits, the clinical application of palifermin is limited owing to its instability and production challenges. Hence, a growing number of ongoing researches are designed to deal with these problems and enhance the physicochemical and pharmaceutical properties of palifermin. In the current review, we discuss KGF structure and function, potential therapeutic applications of palifermin, as well as the latest progress in the production of recombinant human KGF and its challenges ahead.

Glucocorticoids Elevate Pseudomonas aeruginosa Binding to Airway Epithelium by Upregulating Syndecan-1 Expression

Glucocorticoids are commonly used for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Inhaled corticosteroids are associated with a significantly increased risk of pneumonia. Syndecan-1 (SDC1) located in the cell membrane of airway epithelial cell is the crucial molecule mediating infections by P. aeruginosa (PA). In the present study, we found that SDC1 expression was upregulated and the adhesion of PA to human bronchial epithelial (HBE) cells increased to 125 and 138%, respectively, after stimulation by dexamethasone or budesonide. The HBE cells knocking down SDC1 showed lower affinity to PA compared with control. CCAAT-enhancer-binding protein β (C/EBP β) and its phosphorylated form participated in the regulation of glucocorticoid to SDC1 for interfering C/EBP β or inhibiting phosphorylation of C/EBP β by LiCl and BIO, which are inhibitors of glycogen synthase kinase 3β (GSK-3β), and could prevent glucocorticoids from upregulating SDC1 expression. One should be cautious in administering glucocorticoids in chronic lung disease because of their property of increasing the expression of SDC1 and PA binding to the airway epithelium.

Disease-specific glycosaminoglycan patterns in the extracellular matrix of human lung and brain

A wide variety of diseases throughout the mammalian organism is characterized by abnormal deposition of various components of the extracellular matrix (ECM), including the heterogeneous family of glycosaminoglycans (GAGs), which contribute considerably to the ECM architecture as part of the so-called proteoglycans. The GAG's unique sulfation pattern, derived from highly dynamic and specific modification processes, has a massive impact on critical mediators such as cytokines and growth factors. Due to the strong connection between the specific sulfation pattern and GAG function, slight alterations of this pattern are often associated with enormous changes at the cell as well as at the organ level. This review aims to investigate the connection between modifications of GAG sulfation patterns and the wide range of pathological conditions, mainly focusing on a range of chronic diseases of the central nervous system (CNS) as well as the respiratory tract.

Biological role of heparan sulfate in osteogenesis: A review

Heparan sulfate (HS) is extensively expressed in cells, for example, cell membrane and extracellular matrix of most mammalian cells and tissues, playing a key role in the growth and development of life by maintaining homeostasis and implicating in the etiology and diseases. Recent studies have revealed that HS is involved in osteogenesis via coordinating multiple signaling pathways. The potential effect of HS on osteogenesis is a complicated and delicate biological process, which involves the participation of osteocytes, chondrocytes, osteoblasts, osteoclasts and a variety of cytokines. In this review, we summarized the structural and functional characteristics of HS and highlighted the molecular mechanism of HS in bone metabolism to provide novel research perspectives for the further medical research.

Biological Significance and Targeting of the FGFR Axis in Cancer

The pleiotropic effects of fibroblast growth factors (FGFs), the widespread expression of all seven signalling FGF receptors (FGFRs) throughout the body, and the dramatic phenotypes shown by many FGF/R knockout mice, highlight the diversity, complexity and functional importance of FGFR signalling. The FGF/R axis is critical during normal tissue development, homeostasis and repair. Therefore, it is not surprising that substantial evidence also pinpoints the involvement of aberrant FGFR signalling in disease, including tumourigenesis. FGFR aberrations in cancer include mutations, gene fusions, and amplifications as well as corrupted autocrine/paracrine loops. Indeed, many clinical trials on cancer are focusing on targeting the FGF/FGFR axis, using selective FGFR inhibitors, nonselective FGFR tyrosine kinase inhibitors, ligand traps, and monoclonal antibodies and some have already been approved for the treatment of cancer patients. The heterogeneous tumour microenvironment and complexity of FGFR signalling may be some of the factors responsible for the resistance or poor response to therapy with FGFR axis-directed therapeutic agents. In the present review we will focus on the structure and function of FGF(R)s, their common irregularities in cancer and the therapeutic value of targeting their function in cancer.

Heparin and Derivatives for Advanced Cell Therapies

Heparin and its derivatives are saving thousands of human lives annually, by successfully preventing and treating thromboembolic events. Although the mode of action during anticoagulation is well studied, their influence on cell behavior is not fully understood as is the risk of bleeding and other side effects. New applications in regenerative medicine have evolved supporting production of cell-based therapeutics or as a substrate for creating functionalized matrices in biotechnology. The currently resurgent interest in heparins is related to the expected combined anti-inflammatory, anti-thrombotic and anti-viral action against COVID-19. Based on a concise summary of key biochemical and clinical data, this review summarizes the impact for manufacturing and application of cell therapeutics and highlights the need for discriminating the different heparins.

Dispatching plasma membrane cholesterol and Sonic Hedgehog dispatch: two sides of the same coin?

Vertebrate and invertebrate Hedgehog (Hh) morphogens signal over short and long distances to direct cell fate decisions during development and to maintain tissue homeostasis after birth. One of the most important questions in Hh biology is how such Hh signaling to distant target cells is achieved, because all Hh proteins are secreted as dually lipidated proteins that firmly tether to the outer plasma membrane leaflet of their producing cells. There, Hhs multimerize into light microscopically visible storage platforms that recruit factors required for their regulated release. One such recruited release factor is the soluble glycoprotein Scube2 (Signal sequence, cubulin domain, epidermal-growth-factor-like protein 2), and maximal Scube2 function requires concomitant activity of the resistance-nodulation-division (RND) transporter Dispatched (Disp) at the plasma membrane of Hh-producing cells. Although recently published cryo-electron microscopy-derived structures suggest possible direct modes of Scube2/Disp-regulated Hh release, the mechanism of Disp-mediated Hh deployment is still not fully understood. In this review, we discuss suggested direct modes of Disp-dependent Hh deployment and relate them to the structural similarities between Disp and the related RND transporters Patched (Ptc) and Niemann-Pick type C protein 1. We then discuss open questions and perspectives that derive from these structural similarities, with particular focus on new findings that suggest shared small molecule transporter functions of Disp to deplete the plasma membrane of cholesterol and to modulate Hh release in an indirect manner.

Role of glypican-1 in regulating multiple cellular signaling pathways

Glypican-1 (GPC1) is one of the six glypican family members in humans. It is composed of a core protein with three heparan sulfate chains and attached to the cell membrane by a glycosyl-phosphatidylinositol anchor. GPC1 modulates various signaling pathways including fibroblast growth factors (FGF), vascular endothelial growth factor-A (VEGF-A), transforming growth factor-β (TGF-β), Wnt, Hedgehog (Hh), and bone morphogenic protein (BMP) through specific interactions with pathway ligands and receptors. The impact of these interactions on signaling pathways, activating or inhibitory, is dependent upon specific GPC1 domain interaction with pathway components, as well as cell surface context. In this review, we summarize the current understanding of the structure of GPC1, as well as its role in regulating multiple signaling pathways. We focus on the functions of GPC1 in cancer cells and how new insights into these signaling processes can inform its translational potential as a therapeutic target in cancer.

Healing through the lens of immunothrombosis: Biology-inspired, evolution-tailored, and human-engineered biomimetic therapies

Evolution, from invertebrates to mammals, has yielded and shaped immunoclotting as a defense and repair response against trauma and infection. This mosaic of immediate and local wound-sealing and pathogen-killing mechanisms results in survival, restoration of homeostasis, and tissue repair. In mammals, immunoclotting has been complemented with the neuroendocrine system, platelets, and contact system among other embellishments, adding layers of complexity through interconnecting blood-born proteolytic cascades, blood cells, and the neuroendocrine system. In doing so, immunothrombosis endows humans with survival advantages, but entails vulnerabilities in the current unprecedented and increasingly challenging environment. Immunothrombosis and tissue repair appear to go hand in hand with common mechanisms mediating both processes, a fact that is underlined by recent advances that are deciphering the mechanisms of the repair process and of the biochemical pathways that underpins coagulation, hemostasis and thrombosis. This review is intended to frame both the universal aspects of tissue repair and the therapeutic use of autologous fibrin matrix as a biology-as-a-drug approach in the context of the evolutionary changes in coagulation and hemostasis. In addition, we will try to shed some light on the molecular mechanisms underlying the use of the autologous fibrin matrix as a biology-inspired, evolution-tailored, and human-engineered biomimetic therapy.

Receptors and ligands for herpes simplex viruses: Novel insights for drug targeting

Human herpes simplex viruses (HSVs) belong to the Herpesviridae family. At present, no vaccine or curative treatment is available for the prevention of HSV infections. Here, we review the cell surface receptors that are recognized by HSV's glycoprotein B, glycoprotein C, glycoprotein D, and the glycoprotein H - glycoprotein L complex to facilitate entry into host cells. These receptors include heparan sulfate (HS), herpesvirus entry mediator (HVEM), and nectin-1/-2, 3-O-sulfated heparan sulfate (3-OS HS).

Improvement of the performance of anticancer peptides using a drug repositioning pipeline

The use of anticancer peptides (ACPs) as an alternative/complementary strategy to conventional chemotherapy treatments has been shown to decrease drug resistance and/or severe side effects. However, the efficacy of the positively-charged ACP is inhibited by elevated levels of negatively-charged cell-surface components which trap the peptides and prevent their contact with the cell membrane. Consequently, this decreases ACP-mediated membrane pore formation and cell lysis. Negatively-charged heparan sulphate (HS) and chondroitin sulphate (CS) have been shown to inhibit the cytotoxic effect of ACPs. In this study, we propose a strategy to promote the broad utilization of ACPs. In this context, we developed a drug repositioning pipeline to analyse transcriptomics data generated for four different cancer cell lines (A549, HEPG2, HT29, and MCF7) treated with hundreds of drugs in the LINCS L1000 project. Based on previous studies identifying genes modulating levels of the glycosaminoglycans (GAGs) HS and CS at the cell surface, our analysis aimed at identifying drugs inhibiting genes correlated with high HS and CS levels. As a result, we identified six chemicals as likely repositionable drugs with the potential to enhance the performance of ACPs. The codes in R and Python programming languages are publicly available in https://github.com/ElyasMo/ACPs_HS_HSPGs_CS. As a conclusion, these six drugs are highlighted as excellent targets for synergistic studies with ACPs aimed at lowering the costs associated with ACP-treatment.

Direct Current Stimulation Disrupts Endothelial Glycocalyx and Tight Junctions of the Blood-Brain Barrier in vitro

Transcranial direct current stimulation (tDCS) is a non-invasive physical therapy to treat many psychiatric disorders and to enhance memory and cognition in healthy individuals. Our recent studies showed that tDCS with the proper dosage and duration can transiently enhance the permeability (P) of the blood-brain barrier (BBB) in rat brain to various sized solutes. Based on the in vivo permeability data, a transport model for the paracellular pathway of the BBB also predicted that tDCS can transiently disrupt the endothelial glycocalyx (EG) and the tight junction between endothelial cells. To confirm these predictions and to investigate the structural mechanisms by which tDCS modulates P of the BBB, we directly quantified the EG and tight junctions of in vitro BBB models after DCS treatment. Human cerebral microvascular endothelial cells (hCMECs) and mouse brain microvascular endothelial cells (bEnd3) were cultured on the Transwell filter with 3 μm pores to generate in vitro BBBs. After confluence, 0.1–1 mA/cm² DCS was applied for 5 and 10 min. TEER and P to dextran-70k of the in vitro BBB were measured, HS (heparan sulfate) and hyaluronic acid (HA) of EG was immuno-stained and quantified, as well as the tight junction ZO-1. We found disrupted EG and ZO-1 when P to dextran-70k was increased and TEER was decreased by the DCS. To further investigate the cellular signaling mechanism of DCS on the BBB permeability, we pretreated the in vitro BBB with a nitric oxide synthase (NOS) inhibitor, L-NMMA. L-NMMA diminished the effect of DCS on the BBB permeability by protecting the EG and reinforcing tight junctions. These in vitro results conform to the in vivo observations and confirm the model prediction that DCS can disrupt the EG and tight junction of the BBB. Nevertheless, the in vivo effects of DCS are transient which backup its safety in the clinical application. In conclusion, our current study directly elucidates the structural and signaling mechanisms by which DCS modulates the BBB permeability.

The Heparanase Regulatory Network in Health and Disease

The extracellular matrix (ECM) is a structural framework that has many important physiological functions which include maintaining tissue structure and integrity, serving as a barrier to invading pathogens, and acting as a reservoir for bioactive molecules. This cellular scaffold is made up of various types of macromolecules including heparan sulfate proteoglycans (HSPGs). HSPGs comprise a protein core linked to the complex glycosaminoglycan heparan sulfate (HS), the remodeling of which is important for many physiological processes such as wound healing as well as pathological processes including cancer metastasis. Turnover of HS is tightly regulated by a single enzyme capable of cleaving HS side chains: heparanase. Heparanase upregulation has been identified in many inflammatory diseases including atherosclerosis, fibrosis, and cancer, where it has been shown to play multiple roles in processes such as epithelial-mesenchymal transition, angiogenesis, and cancer metastasis. Heparanase expression and activity are tightly regulated. Understanding the regulation of heparanase and its downstream targets is attractive for the development of treatments for these diseases. This review provides a comprehensive overview of the regulators of heparanase as well as the enzyme's downstream gene and protein targets, and implications for the development of new therapeutic strategies.

The CCN2/CTGF interactome: an approach to understanding the versatility of CCN2/CTGF molecular activities

Cellular communication network 2 (CCN2), also known as connective tissue growth factor (CTGF) regulates diverse cellular processes, some at odds with others, including adhesion, proliferation, apoptosis, and extracellular matrix (ECM) protein synthesis. Although a cause-and-effect relationship between CCN2/CTGF expression and local fibrotic reactions has initially been established, CCN2/CTGF manifests cell-, tissue-, and context-specific functions and differentially affects developmental and pathological processes ranging from progenitor cell fate decisions and angiogenesis to inflammation and tumorigenesis. CCN2/CTGF multimodular structure, binding to and activation or inhibition of multiple cell surface receptors, growth factors and ECM proteins, and susceptibility for proteolytic cleavage highlight the complexity to CCN2/CTGF biochemical attributes. CCN2/CTGF expression and dosage in the local environment affects a defined community of its interacting partners, and this results in sequestration of growth factors, interference with or potentiation of ligand-receptor binding, cellular internalization of CCN2/CTGF, inhibition or activation of proteases, and generation of CCN2/CTGF degradome products that add molecular diversity and expand the repertoire of functional modules in the cells and their microenvironment. Through these interactions, different intracellular signals and cellular responses are elicited culminating into physiological or pathological reactions. Thus, the CCN2/CTGF interactome is a defining factor of its tissue- and context-specific effects. Mapping of new CCN2/CTGF binding partners might shed light on yet unknown roles of CCN2/CTGF and provide a solid basis for tissue-specific targeting this molecule or its interacting partners in a therapeutic context.

Heparanized chitosans: towards the third generation of chitinous biomaterials

The functionalization of chitosans is an emerging research area in the design of solutions for a wide range of biomedical applications. In particular, the modification of chitosans to incorporate sulfate groups has generated great interest since they show structural similarity to heparin and heparan sulfates. Most of the biomedical applications of heparan sulfates are derived from their ability to bind different growth factors and other proteins, as through these interactions they can modulate the cellular response. This review aims to summarize the most recent advances in the synthesis, and structural and physicochemical characterization of heparanized chitosan, a remarkably interesting family of polysaccharides that have demonstrated the ability to mimic heparan sulfates as ligands for different proteins, thereby exerting their biological activity by mimicking the function of these glycosaminoglycans.

Glypican 1 and syndecan 1 differently regulate noradrenergic hypertension development: Focus on IP3R and calcium

BACKGROUND

Vascular dysfunction is a checkpoint to the development of hypertension. Heparan sulfate proteoglycans (HSPG) participate in nitric oxide (NO) and calcium signaling, key regulators of vascular function. The relationship between HSPG-mediated NO and calcium signaling and vascular dysfunction has not been explored. Likewise, the role of HSPG on the control of systemic blood arterial pressure is unknown. Herein, we sought to determine if the HSPG syndecan 1 and glypican 1 control systemic blood pressure and the progression of hypertension.

PURPOSE

To determine the mechanisms whereby glypican 1 and syndecan 1 regulate vascular tone and contribute to the development of noradrenergic hypertension.

EXPERIMENTAL APPROACH AND KEY RESULTS

By assessing systemic arterial blood pressure we observed that syndecan 1 (Sdc1-/-) and glypican 1 (Gpc1-/-) knockout mice show a similar phenotype of decreased systolic blood pressure that is presented in a striking manner in the Gpc1-/- strain. Gpc1-/- mice are also uniquely protected from a norepinephrine hypertensive challenge failing to become hypertensive. This phenotype was associated with impaired calcium-dependent vasoconstriction and altered expression of calcium-sensitive proteins including SERCA and calmodulin. In addition, Gpc1-/- distinctively showed decreased IP3R activity and increased calcium storage in the endoplasmic reticulum.

CONCLUSIONS AND IMPLICATIONS

Glypican 1 is a trigger for the development of noradrenergic hypertension that acts via IP3R- and calcium-dependent signaling pathways. Glypican 1 may be a potential target for the development of new therapies for resistant hypertension or conditions where norepinephrine levels are increased.

Novel Insight Into Glycosaminoglycan Biosynthesis Based on Gene Expression Profiles

Glycosaminoglycans (GAGs) including chondroitin sulfate, dermatan sulfate, heparan sulfate, and keratan sulfate, except for hyaluronan that is a free polysaccharide, are covalently attached to core proteins to form proteoglycans. More than 50 gene products are involved in the biosynthesis of GAGs. We recently developed a comprehensive glycosylation mapping tool, GlycoMaple, for visualization and estimation of glycan structures based on gene expression profiles. Using this tool, the expression levels of GAG biosynthetic genes were analyzed in various human tissues as well as tumor tissues. In brain and pancreatic tumors, the pathways for biosynthesis of chondroitin and dermatan sulfate were predicted to be upregulated. In breast cancerous tissues, the pathways for biosynthesis of chondroitin and dermatan sulfate were predicted to be up- and down-regulated, respectively, which are consistent with biochemical findings published in the literature. In addition, the expression levels of the chondroitin sulfate-proteoglycan versican and the dermatan sulfate-proteoglycan decorin were up- and down-regulated, respectively. These findings may provide new insight into GAG profiles in various human diseases including cancerous tumors as well as neurodegenerative disease using GlycoMaple analysis.

The Endothelial Glycocalyx: Physiology and Pathology in Neonates, Infants and Children

The endothelial glycocalyx (EG) as part of the endothelial surface layer (ESL) is an important regulator of vascular function and homeostasis, including permeability, vascular tone, leukocyte recruitment and coagulation. Located at the interface between the endothelium and the blood stream, this highly fragile structure is prone to many disruptive factors such as inflammation and oxidative stress. Shedding of the EG has been described in various acute and chronic diseases characterized by endothelial dysfunction and angiopathy, such as sepsis, trauma, diabetes and cardiovascular disease. Circulating EG components including syndecan-1, hyaluronan and heparan sulfate are being evaluated in animal and clinical studies as diagnostic and prognostic markers in several pathologies, and advances in microscopic techniques have enabled in vivo assessment of the EG. While research regarding the EG in adult physiology and pathology has greatly advanced throughout the last decades, our knowledge of the development of the glycocalyx and its involvement in pathological conditions in the pediatric population is limited. Current evidence suggests that the EG is present early during fetal development and plays a critical role in vessel formation and maturation. Like in adults, EG shedding has been demonstrated in acute inflammatory conditions in infants and children and chronic diseases with childhood-onset. However, the underlying mechanisms and their contribution to disease manifestation and progression still need to be established. In the future, the glycocalyx might serve as a marker to identify pediatric patients at risk for vascular sequelae and as a potential target for early interventions.

Enhanced Antiviral Function of Magnesium Chloride-Modified Heparin on a Broad Spectrum of Viruses

Previous studies reported on the broad-spectrum antiviral function of heparin. Here we investigated the antiviral function of magnesium-modified heparin and found that modified heparin displayed a significantly enhanced antiviral function against human adenovirus (HAdV) in immortalized and primary cells. Nuclear magnetic resonance analyses revealed a conformational change of heparin when complexed with magnesium. To broadly explore this discovery, we tested the antiviral function of modified heparin against herpes simplex virus type 1 (HSV-1) and found that the replication of HSV-1 was even further decreased compared to aciclovir. Moreover, we investigated the antiviral effect against the new severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and measured a 55-fold decreased viral load in the supernatant of infected cells associated with a 38-fold decrease in virus growth. The advantage of our modified heparin is an increased antiviral effect compared to regular heparin.

Tissue-specific parameters for the design of ECM-mimetic biomaterials

The extracellular matrix (ECM) is a complex network of biomolecules that mechanically and biochemically directs cell behavior and is crucial for maintaining tissue function and health. The heterogeneous organization and composition of the ECM varies within and between tissue types, directing mechanics, aiding in cell-cell communication, and facilitating tissue assembly and reassembly during development, injury and disease. As technologies like 3D printing rapidly advance, researchers are better able to recapitulate in vivo tissue properties in vitro; however, tissue-specific variations in ECM composition and organization are not given enough consideration. This is in part due to a lack of information regarding how the ECM of many tissues varies in both homeostatic and diseased states. To address this gap, we describe the components and organization of the ECM, and provide examples for different tissues at various states of disease. While many aspects of ECM biology remain unknown, our goal is to highlight the complexity of various tissues and inspire engineers to incorporate unique components of the native ECM into in vitro platform design and fabrication. Ultimately, we anticipate that the use of biomaterials that incorporate key tissue-specific ECM will lead to in vitro models that better emulate human pathologies. STATEMENT OF SIGNIFICANCE: Biomaterial development primarily emphasizes the engineering of new materials and therapies at the expense of identifying key parameters of the tissue that is being emulated. This can be partially attributed to the difficulty in defining the 3D composition, organization, and mechanics of the ECM within different tissues and how these material properties vary as a function of homeostasis and disease. In this review, we highlight a range of tissues throughout the body and describe how ECM content, cell diversity, and mechanical properties change in diseased tissues and influence cellular behavior. Accurately mimicking the tissue of interest in vitro by using ECM specific to the appropriate state of homeostasis or pathology in vivo will yield results more translatable to humans.

Syndecan-2 expression enriches for hematopoietic stem cells and regulates stem cell repopulating capacity

The discovery of novel hematopoietic stem cell (HSC) surface markers can enhance understanding of HSC identity and function. We have discovered a population of primitive bone marrow (BM) HSCs distinguished by their expression of the heparan sulfate proteoglycan, Syndecan-2, which serves as both a marker and regulator of HSC function. Syndecan-2 expression was increased 10-fold in CD150+CD48-CD34-c-Kit+Sca-1+Lineage- cells (long-term - HSCs, LT-HSCs) compared to differentiated hematopoietic cells. Isolation of BM cells based solely on Syndecan-2 surface expression produced a 24-fold enrichment for LT-HSCs, 6-fold enrichment for alpha-catulin+c-kit+ HSCs, and yielded HSCs with superior in vivo repopulating capacity compared to CD150+ cells. Competitive repopulation assays revealed the HSC frequency to be 17-fold higher in Syndecan-2+CD34-KSL cells compared to Syndecan-2-CD34-KSL cells and indistinguishable from CD150+CD34-KSL cells. Syndecan-2 expression also identified nearly all repopulating HSCs within the CD150+CD34-KSL population. Mechanistically, Syndecan-2 regulates HSC repopulating capacity through control of expression of Cdkn1c (p57) and HSC quiescence. Loss of Syndecan-2 expression caused increased HSC cell cycle entry, downregulation of Cdkn1c and loss of HSC long-term - repopulating capacity. Syndecan-2 is a novel marker of HSCs which regulates HSC repopulating capacity via control of HSC quiescence.

Proteoglycan profiling of human, rat and mouse insulin-secreting cells

Proteoglycans (PGs) are proteins with glycosaminoglycan (GAG) chains, such as chondroitin sulfate (CS) or heparan sulfate (HS), attached to serine residues. We have earlier shown that prohormones can carry CS, constituting a novel class of PGs. The mapping of GAG modifications of proteins in endocrine cells may thus assist us in delineating possible roles of PGs in endocrine cellular physiology. With this aim, we applied a glycoproteomic approach to identify PGs, their GAG chains and their attachment sites in insulin-secreting cells. Glycopeptides carrying GAG chains were enriched from human pancreatic islets, rat (INS-1 832/13) and mouse (MIN6, NIT-1) insulinoma cell lines by exchange chromatography, depolymerized with GAG lyases, and analyzed by nanoflow liquid chromatography tandem mass spectrometry. We identified CS modifications of chromogranin-A (CgA), islet amyloid polypeptide, secretogranin-1 and secretogranin-2, immunoglobulin superfamily member 10, and protein AMBP. Additionally, we identified two HS-modified prohormones (CgA and secretogranin-1), which was surprising, as prohormones are not typically regarded as HSPGs. For CgA, the glycosylation site carried either CS or HS, making it a so-called hybrid site. Additional HS sites were found on syndecan-1, syndecan-4, nerurexin-2, protein NDNF and testican-1. These results demonstrate that several prohormones, and other constituents of the insulin-secreting cells are PGs. Cell-targeted mapping of the GAG glycoproteome forms an important basis for better understanding of endocrine cellular physiology, and the novel CS and HS sites presented here provide important knowledge for future studies.

Plasma cell survival: The intrinsic drivers, migratory signals, and extrinsic regulators

Antibody-secreting cells (ASC) are the effectors of protective humoral immunity and the only cell type that produces antibodies or immunoglobulins in mammals. In addition to their formidable capacity to secrete massive quantities of proteins, ASC are terminally differentiated and have unique features to become long-lived plasma cells (LLPC). Upon antigen encounter, B cells are activated through a complex multistep process to undergo fundamental morphological, subcellular, and molecular transformation to become an efficient protein factory with lifelong potential. The ASC survival potential is determined by factors at the time of induction, capacity to migration from induction to survival sites, and ability to mature in the specialized bone marrow microenvironments. In the past decade, considerable progress has been made in identifying factors regulating ASC longevity. Here, we review the intrinsic drivers, trafficking signals, and extrinsic regulators with particular focus on how they impact the survival potential to become a LLPC.

Basement Membrane Extracellular Matrix Proteins in Pulmonary Vascular and Right Ventricular Remodeling in Pulmonary Hypertension

The extracellular matrix (ECM), a highly organized network of structural and nonstructural proteins, plays a pivotal role in cellular and tissue homeostasis. Changes in the ECM are critical for normal tissue repair, whereas dysregulation contributes to aberrant tissue remodeling. Pulmonary arterial hypertension is a severe disorder of the pulmonary vasculature characterized by pathologic remodeling of the pulmonary vasculature and right ventricle, increased production and deposition of structural and nonstructural proteins, and altered expression of ECM growth factors and proteases. Furthermore, ECM remodeling plays a significant role in disease progression, as several dynamic changes in its composition, quantity, and organization are documented in both humans and animal models of disease. These ECM changes impact vascular cell biology and affect proliferation of resident cells. Furthermore, ECM components determine the tissue architecture of the pulmonary and myocardial vasculature as well as the myocardium itself and provide mechanical stability crucial for tissue homeostasis. However, little is known about the basement membrane (BM), a specialized, self-assembled conglomerate of ECM proteins, during remodeling. In the vasculature, the BM is in close physical association with the vascular endothelium and smooth muscle cells. While in the myocardium, each cardiomyocyte is enclosed by a BM that serves as the interface between cardiomyocytes and the surrounding interstitial matrix. In this review, we provide a brief overview on the current state of knowledge of the BM and its ECM composition and their impact on pulmonary vascular remodeling and right ventricle dysfunction and failure in pulmonary arterial hypertension.

The Differential Roles for Neurodevelopmental and Neuroendocrine Genes in Shaping GnRH Neuron Physiology and Deficiency

Gonadotropin releasing hormone (GnRH) neurons are hypothalamic neuroendocrine cells that control sexual reproduction. During embryonic development, GnRH neurons migrate from the nose to the hypothalamus, where they receive inputs from several afferent neurons, following the axonal scaffold patterned by nasal nerves. Each step of GnRH neuron development depends on the orchestrated action of several molecules exerting specific biological functions. Mutations in genes encoding for these essential molecules may cause Congenital Hypogonadotropic Hypogonadism (CHH), a rare disorder characterized by GnRH deficiency, delayed puberty and infertility. Depending on their action in the GnRH neuronal system, CHH causative genes can be divided into neurodevelopmental and neuroendocrine genes. The CHH genetic complexity, combined with multiple inheritance patterns, results in an extreme phenotypic variability of CHH patients. In this review, we aim at providing a comprehensive and updated description of the genes thus far associated with CHH, by dissecting their biological relevance in the GnRH system and their functional relevance underlying CHH pathogenesis.

APRIL limits atherosclerosis by binding to heparan sulfate proteoglycans

Atherosclerotic cardiovascular disease causes heart attacks and strokes, which are the leading causes of mortality worldwide¹. The formation of atherosclerotic plaques is initiated when low-density lipoproteins bind to heparan-sulfate proteoglycans (HSPGs)² and become trapped in the subendothelial space of large and medium size arteries, which leads to chronic inflammation and remodelling of the artery wall². A proliferation-inducing ligand (APRIL) is a cytokine that binds to HSPGs³, but the physiology of this interaction is largely unknown. Here we show that genetic ablation or antibody-mediated depletion of APRIL aggravates atherosclerosis in mice. Mechanistically, we demonstrate that APRIL confers atheroprotection by binding to heparan sulfate chains of heparan-sulfate proteoglycan 2 (HSPG2), which limits the retention of low-density lipoproteins, accumulation of macrophages and formation of necrotic cores. Indeed, antibody-mediated depletion of APRIL in mice expressing heparan sulfate-deficient HSPG2 had no effect on the development of atherosclerosis. Treatment with a specific anti-APRIL antibody that promotes the binding of APRIL to HSPGs reduced experimental atherosclerosis. Furthermore, the serum levels of a form of human APRIL protein that binds to HSPGs, which we termed non-canonical APRIL (nc-APRIL), are associated independently of traditional risk factors with long-term cardiovascular mortality in patients with atherosclerosis. Our data reveal properties of APRIL that have broad pathophysiological implications for vascular homeostasis.

Heparan sulfate inhibits transforming growth factor β signaling and functions in cis and in trans to regulate prostate stem/progenitor cell activities

Prostate stem/progenitor cells (PrSCs) are responsible for adult prostate tissue homeostasis and regeneration. However, the related regulatory mechanisms are not completely understood. In this study, we examined the role of heparan sulfate (HS) in PrSC self-renewal and prostate regeneration. Using an in vitro prostate sphere formation assay, we found that deletion of the glycosyltransferase exostosin 1 (Ext1) abolished HS expression in PrSCs and disrupted their ability to self-renew. In associated studies, we observed that HS loss inhibited p63 and CK5 expression, reduced the number of p63+- or CK5+-expressing stem/progenitor cells, elevated CK8+ expression and the number of differentiated CK8+ luminal cells and arrested the spheroid cells in the G1/G0 phase of cell cycle. Mechanistically, HS expressed by PrSCs (in cis) or by neighboring cells (in trans) could maintain sphere formation. Furthermore, HS deficiency upregulated transforming growth factor β (TGFβ) signaling and inhibiting TGFβ signaling partially restored the sphere-formation activity of the HS-deficient PrSCs. In an in vivo prostate regeneration assay, simultaneous loss of HS in both epithelial cell and stromal cell compartments attenuated prostate tissue regeneration, whereas the retention of HS expression in either of the two cellular compartments was sufficient to sustain prostate tissue regeneration. We conclude that HS preserves self-renewal of adult PrSCs by inhibiting TGFβ signaling and functions both in cis and in trans to maintain prostate homeostasis and to support prostate regeneration.

The Heparan Sulfate Binding Peptide in Tumor Progression of Triple-Negative Breast Cancer

Angiogenesis is the formation of new vessels from pre-existing vasculature. The heparan sulfate chains from endothelial cell proteoglycans interact with the major angiogenic factors, regulating blood vessels´ formation. Since the FDA´s first approval, anti-angiogenic therapy has shown tumor progression inhibition and increased patient survival. Previous work in our group has selected an HS-binding peptide using a phage display system. Therefore, we investigated the effect of the selected peptide in angiogenesis and tumor progression. The HS-binding peptide showed a higher affinity for heparin N-sulfated. The HS-binding peptide was able to inhibit the proliferation of human endothelial umbilical cord cells (HUVEC) by modulation of FGF-2. It was verified a significant decrease in the tube formation of human endothelial cells and capillary formation of mice aorta treated with HS-binding peptide. HS-binding peptide also inhibited the formation of sub-intestinal blood vessels in zebrafish embryos. Additionally, in zebrafish embryos, the tumor size decreased after treatment with HS-binding peptide.

Pro-angiogenic effects of pregnancy-specific glycoproteins in endothelial and extravillous trophoblast cells

We previously reported that binding to heparan sulfate (HS) is required for the ability of the placentally secreted pregnancy-specific glycoprotein 1 (PSG1) to induce endothelial tubulogenesis. PSG1 is composed of four immunoglobulin-like domains but which domains of the protein bind to HS remains unknown. To analyze the interaction of PSG1 with HS, we generated several recombinant proteins, including the individual domains, chimeric proteins between two PSG1 domains, and mutants. Using flow cytometric and surface plasmon resonance studies, we determined that the B2 domain of PSG1 binds to HS and that the positively charged amino acids encompassed between amino acids 43-59 are required for this interaction. Furthermore, we showed that the B2 domain of PSG1 is required for the increase in the formation of tubes by endothelial cells (EC) including a human endometrial EC line and two extravillous trophoblast (EVT) cell lines and for the pro-angiogenic activity of PSG1 observed in an aortic ring assay. PSG1 enhanced the migration of ECs while it increased the expression of matrix metalloproteinase-2 in EVTs, indicating that the pro-angiogenic effect of PSG1 on these two cell types may be mediated by different mechanisms. Despite differences in amino acid sequence, we observed that all human PSGs bound to HS proteoglycans and confirmed that at least two other members of the family, PSG6 and PSG9, induce tube formation. These findings contribute to a better understanding of the pro-angiogenic activity of human PSGs and strongly suggest conservation of this function among all PSG family members.

Adaptation and Virulence of Enterovirus-A71

Outbreaks of hand, foot, and mouth disease caused by enterovirus-A71 (EV-A71) can result in many deaths, due to central nervous system complications. Outbreaks with many fatalities have occurred sporadically in the Asia-Pacific region and have become a serious public health concern. It is hypothesized that virulent mutations in the EV-A71 genome cause these occasional outbreaks. Analysis of EV-A71 neurovirulence determinants is important, but there are no virulence determinants that are widely accepted among researchers. This is because most studies have been done in artificially infected mouse models and because EV-A71 mutates very quickly to adapt to the artificial host environment. Although EV-A71 uses multiple receptors for infection, it is clear that adaptation-related mutations alter the binding specificity of the receptors and allow the virus to adopt the best entry route for each environment. Such mutations have confused interpretations of virulence in animal models. This article will discuss how environment-adapted mutations in EV-A71 occur, how they affect virulence, and how such mutations can be avoided. We also discuss future perspectives for EV-A71 virulence research.

GPN-1/glypican and UNC-52/perlecan do not appear to function in BMP signaling to pattern the C. elegans postembryonic mesoderm

Heparan sulfate proteoglycans (HSPGs) are diverse macromolecules consisting of a protein core modified with glycosaminoglycan (GAG) chains. HSPGs, including glypicans and perlecans, have been implicated in shaping the extracellular matrix (ECM) to affect growth factor signaling. Here, we tested if GPN-1/glypicanor UNC-52/perlecan plays a role in the bone morphogenetic protein (BMP) signaling pathway in patterning the C. elegans postembryonic mesoderm. Using the suppression of sma-9(0) (Susm)assay, we found that animals carrying mutant alleles of gpn-1 or unc-52 do not exhibit any Susm phenotype. We also tested and found that the two glypicans GPN-1 and LON-2 do not share functional redundancy in the BMP pathway. Our results suggest that GPN-1/glypican and UNC-52/perlecan do not play a major role in the C. elegans BMP pathway, at least in patterning of the postembryonic mesoderm.

Crystal structure of the C-terminal domain of envelope protein VP37 from white spot syndrome virus reveals sulphate binding sites responsible for heparin binding

White spot syndrome virus (WSSV) is the most virulent pathogen causing high mortality and economic loss in shrimp aquaculture and various crustaceans. Therefore, the understanding of molecular mechanisms of WSSV infection is important to develop effective therapeutics to control the spread of this viral disease. In a previous study, we found that VP37 could bind with shrimp haemocytes through the interaction between its C-terminal domain and heparin-like molecules on the shrimp cells, and this interaction can also be inhibited by sulphated galactan. In this study, we present the crystal structure of C-terminal domain of VP37 from WSSV at a resolution of 2.51 Å. The crystal structure contains an eight-stranded β-barrel fold with an antiparallel arrangement and reveals a trimeric assembly. Moreover, there are two sulphate binding sites found in the position corresponding to R213 and K257. In order to determine whether these sulphate binding sites are involved in binding of VP37 to heparin, mutagenesis was performed to replace these residues with alanine (R213A and K257A), and the Surface Plasmon Resonance (SPR) system was used to study the interaction of each mutated VP37 with heparin. The results showed that mutants R213A and K257A exhibited a significant loss in heparin binding activity. These findings indicated that the sites of R213 and K257 on the C-terminal domain of envelope protein VP37 are essential for binding to sulphate molecules of heparin. This study provides further insight into the structure of C-terminal domain of VP37 and it is anticipated that the structure of VP37 might be used as a guideline for development of antivirus agent targeting on the VP37 protein.

Quantitative Proteomic Analysis of Plasma after Remote Ischemic Conditioning in a Rhesus Monkey Ischemic Stroke Model

Background: Animal and clinical studies have shown that remote ischemic conditioning (RIC) has protective effects for cerebral vascular diseases, with induced humoral factor changes in the peripheral blood. However, many findings are heterogeneous, perhaps due to differences in the RIC intervention schemes, enrolled populations, and sample times. This study aimed to examine the RIC-induced changes in the plasma proteome using rhesus monkey models of strokes. Methods: Two adult rhesus monkeys with autologous blood clot-induced middle cerebral artery (MCA) occlusion underwent RIC interventions twice a week for five consecutive weeks. Each RIC treatment included five cycles of five minutes of ischemia alternating with five minutes of reperfusion of the forearm. The blood samples were taken from the median cubital vein of the monkeys at baseline and immediately after each week’s RIC stimulus. The plasma samples were isolated for a proteomic analysis using mass spectrometry (MS). Results: Several proteins related to lipid metabolism (Apolipoprotein A-II and Apolipoprotein C-II), coagulation (Fibrinogen alpha chain and serpin), immunoinflammatory responses (complement C3 and C1), and endovascular hemostasis (basement membrane-specific heparan sulfate proteoglycan) were significantly modulated after the RIC intervention. Many of these induced changes, such as in the lipid metabolism regulation and anticoagulation responses, starting as early as two weeks following the RIC intervention. The complementary activation and protection of the endovascular cells occurred more than three weeks postintervention. Conclusions: Multiple protective effects were induced by RIC and involved lipid metabolism regulation (anti-atherogenesis), anticoagulation (antithrombosis), complement activation, and endovascular homeostasis (anti-inflammation). In conclusion, this study indicates that RIC results in significant modulations of the plasma proteome. It also provides ideas for future research and screening targets.