Syndecan-3 in Inflammation and Angiogenesis

Exploring the potential role of palladin in modulating human CAF/ECM functional units

Fibroblasts, crucial for maintaining tissue homeostasis, significantly shape the tumor microenvironment (TME). In pancreatic cancer, a highly aggressive malignancy, cancer-associated fibroblast (CAF)/extracellular matrix (ECM) units dominate the TME, influencing tumor initiation, progression, and treatment responses. Palladin, an actin-associated protein, is vital for fibroblast structural integrity and activation, playing a key role in CAF/ECM functionality. Palladin interacts with cytoskeletal proteins such as alpha-actinin (α-Act) and can therefore regulate other proteins like syndecans, modulating cytoskeletal features, cell adhesion, integrin recycling, and signaling. In this review, we propose that targeting the palladin/α-Act/syndecan interaction network could modulate CAF/ECM units, potentially shifting the TME from a tumor-promoting to a tumor-suppressive state. In silico data and reported studies to suggest that stabilizing palladin-α-Act interactions, via excess palladin, influences syndecan functions; potentially modulating integrin endocytosis via syndecan engagement with protein kinase C alpha as opposed to syndecan binding to α-Act. This mechanism can then affect the distribution of active α5β1-integrin between the plasma membrane and known intracellular vesicular compartments, thereby influencing the tumor-suppressive versus tumor-promoting functions of CAF/ECM units. Understanding these interactions offers likely future therapeutic avenues for stroma normalization in pancreatic and other cancers, aiming to inhibit tumor progression and improve future treatment outcomes.

Progressive Irreversible Proprioceptive Piezo2 Channelopathy-Induced Lost Forced Peripheral Oscillatory Synchronization to the Hippocampal Oscillator May Explain the Onset of Amyotrophic Lateral Sclerosis Pathomechanism

Amyotrophic lateral sclerosis (ALS) is a mysterious lethal multisystem neurodegenerative disease that gradually leads to the progressive loss of motor neurons. A recent non-contact dying-back injury mechanism theory for ALS proposed that the primary damage is an acquired irreversible intrafusal proprioceptive terminal Piezo2 channelopathy with underlying genetic and environmental risk factors. Underpinning this is the theory that excessively prolonged proprioceptive mechanotransduction under allostasis may induce dysfunctionality in mitochondria, leading to Piezo2 channelopathy. This microinjury is suggested to provide one gateway from physiology to pathophysiology. The chronic, but not irreversible, form of this Piezo2 channelopathy is implicated in many diseases with unknown etiology. Dry eye disease is one of them where replenishing synthetic proteoglycans promote nerve regeneration. Syndecans, especially syndecan-3, are proposed as the first critical link in this hierarchical ordered depletory pathomechanism as proton-collecting/distributing antennas; hence, they may play a role in ALS pathomechanism onset. Even more importantly, the shedding or charge-altering variants of Syndecan-3 may contribute to the Piezo2 channelopathy-induced disruption of the Piezo2-initiated proton-based ultrafast long-range signaling through VGLUT1 and VGLUT2. Thus, these alterations may not only cause disruption to ultrafast signaling to the hippocampus in conscious proprioception, but could disrupt the ultrafast proprioceptive signaling feedback to the motoneurons. Correspondingly, an inert Piezo2-initiated proton-based ultrafast signaled proprioceptive skeletal system is coming to light that is suggested to be progressively lost in ALS. In addition, the lost functional link of the MyoD family of inhibitor proteins, as auxiliary subunits of Piezo2, may not only contribute to the theorized acquired Piezo2 channelopathy, but may explain how these microinjured ion channels evolve to be principal transcription activators.

Capillary leak and endothelial permeability in critically ill patients: a current overview

Capillary leak syndrome (CLS) represents a phenotype of increased fluid extravasation, resulting in intravascular hypovolemia, extravascular edema formation and ultimately hypoperfusion. While endothelial permeability is an evolutionary preserved physiological process needed to sustain life, excessive fluid leak-often caused by systemic inflammation-can have detrimental effects on patients' outcomes. This article delves into the current understanding of CLS pathophysiology, diagnosis and potential treatments. Systemic inflammation leading to a compromise of endothelial cell interactions through various signaling cues (e.g., the angiopoietin-Tie2 pathway), and shedding of the glycocalyx collectively contribute to the manifestation of CLS. Capillary permeability subsequently leads to the seepage of protein-rich fluid into the interstitial space. Recent insights into the importance of the sub-glycocalyx space and preserving lymphatic flow are highlighted for an in-depth understanding. While no established diagnostic criteria exist and CLS is frequently diagnosed by clinical characteristics only, we highlight more objective serological and (non)-invasive measurements that hint towards a CLS phenotype. While currently available treatment options are limited, we further review understanding of fluid resuscitation and experimental approaches to target endothelial permeability. Despite the improved understanding of CLS pathophysiology, efforts are needed to develop uniform diagnostic criteria, associate clinical consequences to these criteria, and delineate treatment options.

Syndecan-4 as a genetic determinant of the metabolic syndrome

BACKGROUND

Syndecan-4 (SDC4) is a member of the heparan sulfate proteoglycan family of cell-surface receptors. We and others previously reported that variation in the SDC4 gene was associated with several components of the metabolic syndrome, including intra-abdominal fat, fasting glucose and triglyceride levels, and hypertension, in human cohorts. Additionally, we demonstrated that high fat diet (HFD)-induced obese female mice with a Sdc4 genetic deletion had higher visceral adiposity and a worse metabolic profile than control mice. Here, we aimed to first investigate whether the mouse Sdc4 null mutation impacts metabolic phenotypes in a sex- and diet-dependent manner. We then tested whether SDC4 polymorphisms are related to the metabolic syndrome (MetS) in humans.

METHODS

For the mouse experiment, Sdc4-deficient (Sdc4-/-) and wild-type (WT) mice were treated with 14-weeks of low-fat diet (LFD). Body composition, energy balance, and selected metabolic phenotypes were assessed. For the human genetic study, we used logistic regression models to test 11 SDC4 SNPs for association with the MetS and its components in a cohort of 274 (113 with MetS) elderly subjects from southern Italy.

RESULTS

Following the dietary intervention in mice, we observed that the effects of the Sdc4 null mutation on several phenotypes were different from those previously reported in the mice kept on an HFD. Nonetheless, LFD-fed female Sdc4-/- mice, but not males, displayed higher levels of triglycerides and lower insulin sensitivity at fasting than WT mice, as seen earlier in the HFD conditions. In the parallel human study, we found that carriers of SDC4 rs2228384 allele C and rs2072785 allele T had reduced risk of MetS. The opposite was true for carriers of the SDC4 rs1981429 allele G. Additionally, the SNPs were found related to fasting triglyceride levels and triglyceride glucose (TyG) index, a reliable indicator of insulin resistance, with sex-stratified analysis detecting the association of rs1981429 with these phenotypes only in females.

CONCLUSIONS

Altogether, our results suggest that SDC4 is an evolutionary conserved genetic determinant of MetS and that its genetic variation is associated with fasting triglyceride levels in a female-specific manner.

ClearF++: Improved Supervised Feature Scoring Using Feature Clustering in Class-Wise Embedding and Reconstruction

Feature selection methods are essential for accurate disease classification and identifying informative biomarkers. While information-theoretic methods have been widely used, they often exhibit limitations such as high computational costs. Our previously proposed method, ClearF, addresses these issues by using reconstruction error from low-dimensional embeddings as a proxy for the entropy term in the mutual information. However, ClearF still has limitations, including a nontransparent bottleneck layer selection process, which can result in unstable feature selection. To address these limitations, we propose ClearF++, which simplifies the bottleneck layer selection and incorporates feature-wise clustering to enhance biomarker detection. We compare its performance with other commonly used methods such as MultiSURF and IFS, as well as ClearF, across multiple benchmark datasets. Our results demonstrate that ClearF++ consistently outperforms these methods in terms of prediction accuracy and stability, even with limited samples. We also observe that employing the Deep Embedded Clustering (DEC) algorithm for feature-wise clustering improves performance, indicating its suitability for handling complex data structures with limited samples. ClearF++ offers an improved biomarker prioritization approach with enhanced prediction performance and faster execution. Its stability and effectiveness with limited samples make it particularly valuable for biomedical data analysis.

Syndecan-3 Coregulates Milk Fat Metabolism and Inflammatory Reactions in Bovine Mammary Epithelial Cells through AMPK/SIRT1 Signaling Pathway

Transcriptome sequencing showed that syndecan-3 (SDC3) was differentially expressed in high-fat and low-fat mammary epithelial cells of Chinese Holstein cows. Previous studies found that SDC3 plays an important role in inflammatory diseases and virus infection. However, those studies did not confirm whether or not the functional gene SDC3, which plays an important role in regulating milk fat metabolism, has an effect on susceptibility to breast tissue diseases. Therefore, we studied the effects of SDC3 on milk lipid metabolism and inflammation in bovine mammary epithelial cells (BMECs) and further explored the common regulatory pathway of SDC3 in both. The overexpression of SDC3 increased the contents of triglycerides and cholesterol, reduced the content of non-esterified fatty acids, inhibited the expression of inflammatory factors (IL-6, IL-1β, TNF-α and COX-2), and reduced the production of ROS in BMECs. However, silenced SDC3 had the opposite effect. Further exploring the mechanisms of SDC3, we found that SDC3 upregulated the expression of peroxisome proliferator-activated receptor gamma (PPARG) through the AMPK/SIRT1 signal pathway to promote milk fat synthesis. It also regulated the activation of the NF-κB pathway through the AMPK/SIRT1 signal pathway, reducing the expression of inflammatory factors and ROS production, thus inhibiting the inflammatory response of BMECs. Nuclear factor kappa B subunit 1 (NF-κB p50) was an important target of SDC3 in this process. To sum up, our results showed that SDC3 coregulated milk fat metabolism and inflammation through the AMPK/SIRT1 signaling pathway. This study laid a foundation for the comprehensive evaluation of breeding value based on multi-effect functional genes in dairy cow molecular breeding.

Syndecan-3 regulates the time of transition from cell cycle exit to initial differentiation stage in mouse cerebellar granule cell precursors

To analyze the role of syndecan-3 (SDC3), a heparan sulfate proteoglycan, in cerebellum development, we examined the effect of SDC3 on the transition from cell cycle exit to the initial differentiation stage of cerebellar granule cell precursors (CGCPs). First, we examined SDC3 localization in the developing cerebellum. SDC3 was mainly localized to the inner external granule layer where the transition from the cell cycle exit to the initial differentiation of CGCPs occurs. To examine how SDC3 regulates the cell cycle exit of CGCPs, we performed SDC3-knockdown (SDC3-KD) and -overexpression (Myc-SDC3) assays using primary CGCPs. SDC3-KD significantly increased the ratio of p27^Kip1+ cells to total cells at day 3 in vitro (DIV3) and 4, but Myc-SDC3 reduced that at DIV3. Regarding the cell cycle exit efficiency using 24 h-labelled bromodeoxyuridine (BrdU) and a marker of cell cycling, Ki67, SDC3-KD significantly increased cell cycle exit efficiency (Ki67^-; BrdU⁺ cells/BrdU⁺ cells) in primary CGCP at DIV4 and 5, but Myc-SDC3 reduced that at DIV4 and 5. However, SDC3-KD and Myc-SDC3 did not affect the efficiency of the final differentiation from CGCPs to granule cells at DIV3-5. Furthermore, the ratio of CGCPs in the cell cycle exiting stage to total cells, identified by initial differentiation markers TAG1 and Ki67 (TAG1⁺; Ki67⁺ cells), was considerably decreased by SDC3-KD at DIV4, but increased by Myc-SDC3 at DIV4 and 5. Altogether, these results indicate that SDC3 regulates the timing of the transition from the cell cycle exit stage to the initial differentiation stage of CGCP.

Endothelial Damage and the Microcirculation in Critical Illness

Endothelial integrity maintains microcirculatory flow and tissue oxygen delivery. The endothelial glycocalyx is involved in cell signalling, coagulation and inflammation. Our ability to treat critically ill and septic patients effectively is determined by understanding the underpinning biological mechanisms. Many mechanisms govern the development of sepsis and many large trials for new treatments have failed to show a benefit. Endothelial dysfunction is possibly one of these biological mechanisms. Glycocalyx damage is measured biochemically. Novel microscopy techniques now mean the glycocalyx can be indirectly visualised, using sidestream dark field imaging. How the clinical visualisation of microcirculation changes relate to biochemical laboratory measurements of glycocalyx damage is not clear. This article reviews the evidence for a relationship between clinically evaluable microcirculation and biological signal of glycocalyx disruption in various diseases in ICU. Microcirculation changes relate to biochemical evidence of glycocalyx damage in some disease states, but results are highly variable. Better understanding and larger studies of this relationship could improve phenotyping and personalised medicine in the future. Damage to the glycocalyx could underpin many critical illness pathologies and having real-time information on the glycocalyx and microcirculation in the future could improve patient stratification, diagnosis and treatment.

Genome-wide association analysis of anti-TNF-α treatment response in Chinese patients with psoriasis

Background: TNF-α inhibitors are effective biological agents for treating psoriasis, but the treatment responses differ across patients. This study aimed to identify genetic biomarkers of anti-TNF-α response in Chinese psoriasis patients using a genome-wide association approach.

Methods: We recruited two independent cohorts of Chinese psoriasis patients administered etanercept biosimilar (with or without methotrexate). We identified 61 and 87 good responders (PASI improvement ≥75%), 19 and 10 poor responders (PASI improvement <50%) after 24 weeks treatment in the two cohorts, respectively. Then we performed genome-wide association studies (GWAS) on anti-TNF-α response in each cohort independently, followed by a fixed-effects inverse-variance meta-analysis in the 148 good and 29 poor responders.

Results: We tested genetic associations with >3 million genetic variants in either cohort. Meta-analysis identified significant associations within seven loci at p < 10⁻⁵, which also showed consistent association evidence in the two cohorts. These seven loci include rs2431355 (OR = 6.65, p = 4.46 × 10⁻⁷, IQGAP2-F2RL2 on 5q13.3), rs11801616 (OR = 0.11, p = 1.75 × 10⁻⁶, SDC3 on 1p35.2), rs3754679 (OR = 0.17, p = 7.71 × 10⁻⁶, CNOT11 on 2q11.2), rs13166823 (OR = 0.09, p = 3.71 × 10⁻⁶, IRF1-AS1 on 5q31.1), rs10220768 (OR = 5.49, p = 1.48 × 10⁻⁶, NPAP1 on 15q11.2), rs4796752 (OR = 5.56, p = 1.49 × 10⁻⁶, KRT31 on 17q21.2), and rs13045590 (OR = 0.08, p = 9.67 × 10⁻⁷, CTSZ on 20q13.3). Of the seven SNPs, six SNPs showed significant eQTL effect (p < 1 × 10⁻⁶) for several genes in multiple tissues.

Conclusion: These results suggest novel biological mechanisms and potential biomarkers for the response to anti-TNF therapies. These findings warrant further validation.

The Cell Surface Heparan Sulfate Proteoglycan Syndecan-3 Promotes Ovarian Cancer Pathogenesis

Syndecans are transmembrane heparan sulfate proteoglycans that integrate signaling at the cell surface. By interacting with cytokines, signaling receptors, proteases, and extracellular matrix proteins, syndecans regulate cell proliferation, metastasis, angiogenesis, and inflammation. We analyzed public gene expression datasets to evaluate the dysregulation and potential prognostic impact of Syndecan-3 in ovarian cancer. Moreover, we performed functional in vitro analysis in syndecan-3-siRNA-treated SKOV3 and CAOV3 ovarian cancer cells. In silico analysis of public gene array datasets revealed that syndecan-3 mRNA expression was significantly increased 5.8-fold in ovarian cancer tissues (n = 744) and 3.4-fold in metastases (n = 44) compared with control tissue (n = 46), as independently confirmed in an RNAseq dataset on ovarian serous cystadenocarcinoma tissue (n = 374, controls: n = 133, 3.5-fold increase tumor vs. normal). Syndecan-3 siRNA knockdown impaired 3D spheroid growth and colony formation as stemness-related readouts in SKOV3 and CAOV3 cells. In SKOV3, but not in CAOV3 cells, syndecan-3 depletion reduced cell viability both under basal conditions and under chemotherapy with cisplatin, or cisplatin and paclitaxel. While analysis of the SIOVDB database did not reveal differences in Syndecan-3 expression between patients, sensitive, resistant or refractory to chemotherapy, KM Plotter analysis of 1435 ovarian cancer patients revealed that high syndecan-3 expression was associated with reduced survival in patients treated with taxol and platin. At the molecular level, a reduction in Stat3 activation and changes in the expression of Wnt and notch signaling constituents were observed. Our study suggests that up-regulation of syndecan-3 promotes the pathogenesis of ovarian cancer by modulating stemness-associated pathways.

The role of the cell surface glycocalyx in drug delivery to and through the endothelium

Cell membranes are key interfaces where materials engineering meets biology. Traditionally regarded as just the location of receptors regulating the uptake of molecules, we now know that all mammalian cell membranes are 'sugar coated'. These sugars, or glycans, form a matrix bound at the cell membrane via proteins and lipids, referred to as the glycocalyx, which modulate access to cell membrane receptors crucial for interactions with drug delivery systems (DDS). Focusing on the key blood-tissue barrier faced by most DDS to enable transport from the place of administration to target sites via the circulation, we critically assess the design of carriers for interactions at the endothelial cell surface. We also discuss the current challenges for this area and provide opportunities for future research efforts to more fully engineer DDS for controlled, efficient, and targeted interactions with the endothelium for therapeutic application.

Syndecan-3 as a Novel Biomarker in Alzheimer's Disease

Early diagnosis of Alzheimer's disease (AD) is of paramount importance in preserving the patient's mental and physical health in a fairly manageable condition for a longer period. Reliable AD detection requires novel biomarkers indicating central nervous system (CNS) degeneration in the periphery. Members of the syndecan family of transmembrane proteoglycans are emerging new targets in inflammatory and neurodegenerative disorders. Reviewing the growing scientific evidence on the involvement of syndecans in the pathomechanism of AD, we analyzed the expression of the neuronal syndecan, syndecan-3 (SDC3), in experimental models of neurodegeneration. Initial in vitro studies showed that prolonged treatment of tumor necrosis factor-alpha (TNF-α) increases SDC3 expression in model neuronal and brain microvascular endothelial cell lines. In vivo studies revealed elevated concentrations of TNF-α in the blood and brain of APPSWE-Tau transgenic mice, along with increased SDC3 concentration in the brain and the liver. Primary brain endothelial cells and peripheral blood monocytes isolated from APPSWE-Tau mice exhibited increased SDC3 expression than wild-type controls. SDC3 expression of blood-derived monocytes showed a positive correlation with amyloid plaque load in the brain, demonstrating that SDC3 on monocytes is a good indicator of amyloid pathology in the brain. Given the well-established role of blood tests, the SDC3 expression of monocytes could serve as a novel biomarker for early AD detection.

Single-Cell RNA Sequencing Reveals the Temporal Diversity and Dynamics of Cardiac Immunity after Myocardial Infarction

Myocardial infarction (MI) is strongly associated with the temporal regulation of cardiac immunity. However, a variety of current clinical trials have failed because of the lack of post-MI immunomodulating/anti-inflammatory targets. Single-cell RNA sequencing analysis of the cardiac Cd45⁺ immune cell at 0, 3, 7, and 14 d after injury in a mouse left anterior descending coronary artery ligation model is performed. Major immune cell populations, distinct subsets, and dynamic changes are identified. Macrophages (Mø) are most abundant, peaking at 3 d after infarction. Mø-5 and Mø-6 are the predominant infiltrated subsets at this time point, with strong expression of inflammatory factors. Further analysis demonstrates that suppressing these sets attenuated pathological MI progression by preventing subsequent leukocyte extravasation and adverse remodeling. Abundant apoptotic neutrophils and a profibrotic macrophage subset on days 7 and 14, respectively, are also detected. These results provide a basis for developing cell type- and time-specific interventions in MI.

Hyperglycemia-induced effects on glycocalyx components in the retina

PURPOSE

Diabetic retinopathy is a vision-threatening complication of diabetes characterized by endothelial injury and vascular dysfunction. The loss of the endothelial glycocalyx, a dynamic layer lining all endothelial cells, contributes to several microvascular pathologies, including an increase in vascular permeability, leukocyte plugging, and capillary occlusion, and may drive the progression of retinopathy. Previously, a significant decrease in glycocalyx thickness has been observed in diabetic retinas. However, the effects of diabetes on specific components of the retinal glycocalyx have not yet been studied. Therefore, the aim of our study was to investigate changes in synthesis, expression, and shedding of retinal glycocalyx components induced by hyperglycemia, which could provide a novel therapeutic target for diabetic retinopathy.

METHODS

Primary rat retinal microvascular endothelial cells (RRMECs) were grown under normal glucose (5 mM) or high-glucose (25 mM) conditions for 6 days. The mRNA and protein levels of the glycocalyx components were examined using qRT-PCR and Western blot analysis, respectively. Further, mass spectrometry was used to analyze protein intensities of core proteins. In addition, the streptozotocin-induced Type 1 diabetic rat model was used to study changes in the expression of the retinal glycocalyx in vivo. The shedding of the glycocalyx was studied in both culture medium and in plasma using Western blot analysis.

RESULTS

A significant increase in the shedding of syndecan-1 and CD44 was observed both in vitro and in vivo under high-glucose conditions. The mRNA levels of syndecan-3 were significantly lower in the RRMECs grown under high glucose conditions, whereas those of syndecan-1, syndecan-2, syndecan-4, glypican-1, glypican-3, and CD44 were significantly higher. The protein expression of syndecan-3 and glypican-1 in RRMECs was reduced considerably following exposure to high glucose, whereas that of syndecan-1 and CD44 increased significantly. In addition, mass spectrometry data also suggests a significant increase in syndecan-4 and a significant decrease in glypican-3 protein levels with high glucose stimulation. In vivo, our data also suggest a significant decrease in the mRNA transcripts of syndecan-3 and an increase in mRNA levels of glypican-1 and CD44 in the retinas of diabetic rats. The diabetic rats exhibited a significant reduction in the retinal expression of syndecan-3 and CD44. However, the expression of syndecan-1 and glypican-1 increased significantly in the diabetic retina.

CONCLUSIONS

One of the main findings of our study was the considerable diversity of glucose-induced changes in expression and shedding of various components of endothelial glycocalyx, for example, increased endothelial and retinal syndecan-1, but decreased endothelial and retinal syndecan-3. This indicates that the reported decrease in the retinal glycocalyx in diabetes in not a result of a non-specific shedding mechanism. Moreover, mRNA measurements indicated a similar diversity, with increases in endothelial and/or retinal levels of syndecan-1, glypican-1, and CD44, but a decrease for syndecan-3, with these increases in mRNA potentially a compensatory reaction to the overall loss of glycocalyx.

The ERK/CREB/PTN/syndecan-3 pathway involves in heparin-mediated neuro-protection and neuro-regeneration against cerebral ischemia-reperfusion injury following cardiac arrest

BACKGROUND

Heparin, a commonly used anticoagulant, has been found to improve cerebral ischemia-reperfusion injury (CIR-CA) following cardiopulmonary resuscitation (CPR). Here, we aimed to explore the role of pleiotrophin (PTN)/syndecan-3 pathway in heparin therapy for CIR-CA.

MATERIALS AND METHODS

The CA-CPR model was constructed in Sprague-Dawley (SD) rats, which were treated with low molecular weight heparin, and the neurological changes and brain histopathological changes were evaluated. For in-vitro experiments, the ischemic injury model of primary neurons was established by oxygen and glucose deprivation (OGD), and the neuron regeneration was detected via the Cell counting Kit-8 (CCK8) method, flow cytometry and microscopy. CREB antagonist (KG-501), ERK antagonist (PD98059) and si-PTN were used respectively to inhibit the expression of CREB, ERK and PTN in cells, so as to explore the role of heparin in regulating neuronal regeneration.

RESULTS

Compared with the sham rats, the neurological deficits and cerebral edema of CA-CPR rats were significantly improved after heparin treatment. Heparin also attenuated OGD-mediated neuronal apoptosis and promoted neurite outgrowth in vitro. Moreover, heparin attenuated CA-CPR-mediated neuronal apoptosis and microglial neuroinflammation. In terms of the mechanism, heparin upregulated the expression of ERK, CREB, NF200, BDNF, NGF, PTN and syndecan-3 in the rat brains. Inhibition of ERK, CREB and interference with PTN expression notably weakened the heparin-mediated neuroprotective effects and restrained the expression of ERK/CREB and PTN/syndecan-3 pathway.

CONCLUSION

Heparin attenuates the secondary brain injury induced by CA-CPR through regulating the ERK/CREB-mediated PTN/syndecan-3 pathway.

Pathological Angiogenesis Requires Syndecan-4 for Efficient VEGFA-Induced VE-Cadherin Internalization

[Figure: see text].

Syndecans and Pancreatic Ductal Adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) is a fatal disease with poor prognosis because patients rarely express symptoms in initial stages, which prevents early detection and diagnosis. Syndecans, a subfamily of proteoglycans, are involved in many physiological processes including cell proliferation, adhesion, and migration. Syndecans are physiologically found in many cell types and their interactions with other macromolecules enhance many pathways. In particular, extracellular matrix components, growth factors, and integrins collect the majority of syndecans associations acting as biochemical, physical, and mechanical transducers. Syndecans are transmembrane glycoproteins, but occasionally their extracellular domain can be released from the cell surface by the action of matrix metalloproteinases, converting them into soluble molecules that are capable of binding distant molecules such as extracellular matrix (ECM) components, growth factor receptors, and integrins from other cells. In this review, we explore the role of syndecans in tumorigenesis as well as their potential as therapeutic targets. Finally, this work reviews the contribution of syndecan-1 and syndecan-2 in PDAC progression and illustrates its potential to be targeted in future treatments for this devastating disease.

Integrin Regulation in Immunological and Cancerous Cells and Exosomes

Integrins represent the biologically and medically significant family of cell adhesion molecules that govern a wide range of normal physiology. The activities of integrins in cells are dynamically controlled via activation-dependent conformational changes regulated by the balance of intracellular activators, such as talin and kindlin, and inactivators, such as Shank-associated RH domain interactor (SHARPIN) and integrin cytoplasmic domain-associated protein 1 (ICAP-1). The activities of integrins are alternatively controlled by homotypic lateral association with themselves to induce integrin clustering and/or by heterotypic lateral engagement with tetraspanin and syndecan in the same cells to modulate integrin adhesiveness. It has recently emerged that integrins are expressed not only in cells but also in exosomes, important entities of extracellular vesicles secreted from cells. Exosomal integrins have received considerable attention in recent years, and they are clearly involved in determining the tissue distribution of exosomes, forming premetastatic niches, supporting internalization of exosomes by target cells and mediating exosome-mediated transfer of the membrane proteins and associated kinases to target cells. A growing body of evidence shows that tumor and immune cell exosomes have the ability to alter endothelial characteristics (proliferation, migration) and gene expression, some of these effects being facilitated by vesicle-bound integrins. As endothelial metabolism is now thought to play a key role in tumor angiogenesis, we also discuss how tumor cells and their exosomes pleiotropically modulate endothelial functions in the tumor microenvironment.

Syndecan receptors: pericellular regulators in development and inflammatory disease

The syndecans are the major family of transmembrane proteoglycans, usually bearing multiple heparan sulfate chains. They are present on virtually all nucleated cells of vertebrates and are also present in invertebrates, indicative of a long evolutionary history. Genetic models in both vertebrates and invertebrates have shown that syndecans link to the actin cytoskeleton and can fine-tune cell adhesion, migration, junction formation, polarity and differentiation. Although often associated as co-receptors with other classes of receptors (e.g. integrins, growth factor and morphogen receptors), syndecans can nonetheless signal to the cytoplasm in discrete ways. Syndecan expression levels are upregulated in development, tissue repair and an array of human diseases, which has led to the increased appreciation that they may be important in pathogenesis not only as diagnostic or prognostic agents, but also as potential targets. Here, their functions in development and inflammatory diseases are summarized, including their potential roles as conduits for viral pathogen entry into cells.

Heparan Sulfate Glycosaminoglycans: (Un)Expected Allies in Cancer Clinical Management

In an era when cancer glycobiology research is exponentially growing, we are witnessing a progressive translation of the major scientific findings to the clinical practice with the overarching aim of improving cancer patients' management. Many mechanistic cell biology studies have demonstrated that heparan sulfate (HS) glycosaminoglycans are key molecules responsible for several molecular and biochemical processes, impacting extracellular matrix properties and cellular functions. HS can interact with a myriad of different ligands, and therefore, hold a pleiotropic role in regulating the activity of important cellular receptors and downstream signalling pathways. The aberrant expression of HS glycan chains in tumours determines main malignant features, such as cancer cell proliferation, angiogenesis, invasion and metastasis. In this review, we devote particular attention to HS biological activities, its expression profile and modulation in cancer. Moreover, we highlight HS clinical potential to improve both diagnosis and prognosis of cancer, either as HS-based biomarkers or as therapeutic targets.

Syndecans in cancer: A review of function, expression, prognostic value, and therapeutic significance

While our understanding of tumors and how to treat them has advanced significantly since the days of Aminopterin and the radical mastectomy, cancer remains among the leading causes of death worldwide. Despite innumerable advancements in medical technology the non-static and highly heterogeneous nature of a tumor can make characterization and treatment exceedingly difficult. Because of this complexity, the identification of new cellular constituents that can be used for diagnostic, prognostic, and therapeutic purposes is crucial in improving patient outcomes worldwide. Growing evidence has demonstrated that among the myriad of changes seen in cancer cells, the Syndecan family of proteins has been observed to undergo drastic alterations in expression. Syndecans are transmembrane heparan sulfate proteoglycans that are responsible for cell signaling, proliferation, and adhesion, and many studies have shed light on their unique involvement in both tumor progression and suppression. This review seeks to discuss Syndecan expression levels in various cancers, whether they make reliable biomarkers for detection and prognosis, and whether they may be viable targets for future cancer therapies. The conclusions drawn from the literature reviewed in this article indicate that changes in expression of Syndecan protein can have profound effects on tumor size, metastatic capability, and overall patient survival rate. Further, while data regarding the therapeutic targeting of Syndecan proteins is sparse, the available literature does demonstrate promise for their use in cancer treatment going forward.

Hypoxia Promotes Syndecan-3 Expression in the Tumor Microenvironment

The syndecan (Sdc) family is comprised of four members of cell surface molecules (Sdc-1 to 4) with different biological functions. Syndecan-3 (Sdc-3) is known to be mainly expressed in the brain and nervous tissue and plays a key role in development, cell adhesion, and migration. Recent studies point to important roles for Sdc-3 in inflammatory disease, but the patterns of expression and significance of Sdc-3 in cancer remains unexplored. Here we show that Sdc-3 expression is upregulated on several cancer types, especially in solid tumors that are known to be hypoxic. The Cancer Genome Atlas program (TCGA) data demonstrated that Sdc-3 expression in the tumor microenvironment positively correlates with a hypoxia gene signature. To confirm a potential cause-effect, we performed experiments with tumor cell lines showing increased expression upon in vitro exposure to 1% oxygen or dimethyloxalylglycine, an inhibitor of prolyl hydroxylases, indicating that Sdc-3 expression is promoted by hypoxia inducible factors (HIFs). HIF-1α was responsible for this upregulation as confirmed by CRISPR-engineered tumor cells. Using single-cell RNA sequencing data of melanoma patients, we show that Sdc-3 is expressed on tumor associated macrophages, cancer cells, and endothelial cells. Syndecan-3 expression positively correlated with a macrophage gene signature across several TCGA cancer types. In vitro experiments demonstrated that hypoxia (1% oxygen) or treatment with IFN-γ stimulate Sdc-3 expression on RAW-264.7 derived macrophages, linking Sdc-3 expression to a proinflammatory response. Syndecan-3 expression correlates with a better patient overall survival in hypoxic melanoma tumors.

Coronaviruses: Is Sialic Acid a Gate to the Eye of Cytokine Storm? From the Entry to the Effects

Coronaviruses (CoVs) are a diverse family of the enveloped human and animal viruses reported as causative agents for respiratory and intestinal infections. The high pathogenic potential of human CoVs, including SARS-CoV, MERS-CoV and SARS-CoV-2, is closely related to the invasion mechanisms underlying the attachment and entry of viral particles to the host cells. There is increasing evidence that sialylated compounds of cellular glycocalyx can serve as an important factor in the mechanism of CoVs infection. Additionally, the sialic acid-mediated cross-reactivity with the host immune lectins is known to exert the immune response of different intensity in selected pathological stages. Here, we focus on the last findings in the field of glycobiology in the context of the role of sialic acid in tissue tropism, viral entry kinetics and immune regulation in the CoVs infections.