Inhibition of protein glycosylation is a novel pro-angiogenic strategy that acts via activation of stress pathways

Glucosamine-Mediated Hexosamine Biosynthesis Pathway Activation Uses ATF4 to Promote "Exercise-Like" Angiogenesis and Perfusion Recovery in PAD

BACKGROUND

Endothelial cells (ECs) use glycolysis to produce energy. In preclinical models of peripheral arterial disease, further activation of EC glycolysis was ineffective or deleterious in promoting hypoxia-dependent angiogenesis, whereas pentose phosphate pathway activation was effective. Hexosamine biosynthesis pathway, pentose phosphate pathway, and glycolysis are closely linked. Glucosamine directly activates hexosamine biosynthesis pathway.

METHODS

Hind-limb ischemia in endothelial nitric oxide synthase knockout (eNOS-/-) and BALB/c mice was used. Glucosamine (600 μg/g per day) was injected intraperitoneally. Blood flow recovery was assessed using laser Doppler perfusion imaging and angiogenesis was studied by CD31 immunostaining. In vitro, human umbilical vein ECs and mouse microvascular ECs with glucosamine, L-glucose, or vascular endothelial growth factor (VEGF165a) were tested under hypoxia and serum starvation. Cell Counting Kit-8, tube formation, intracellular reactive oxygen species, electric cell-substrate impedance sensing, and fluorescein isothiocyanate dextran permeability were assessed. Glycolysis and oxidative phosphorylation were assessed by seahorse assay. Gene expression was assessed using RNA sequencing, real-time quantitative polymerase chain reaction, and Western blot. Human muscle biopsies from patients with peripheral arterial disease were assessed for EC O-GlcNAcylation before and after supervised exercise versus standard medical care.

RESULTS

On day 3 after hind-limb ischemia, glucosamine-treated versus control eNOS-/- mice had less necrosis (n=4 or 5 per group). Beginning on day 7 after hind-limb ischemia, glucosamine-treated versus control BALB/c mice had higher blood flow, which persisted to day 21, when ischemic muscles showed greater CD31 staining per muscle fiber (n=8 per group). In vitro, glucosamine versus L-glucose ECs showed improved survival (n=6 per group) and tube formation (n=6 per group). RNA sequencing of glucosamine versus L-glucose ECs showed increased amino acid metabolism (n=3 per group). That resulted in increased oxidative phosphorylation (n=8-12 per group) and serine biosynthesis pathway without an increase in glycolysis or pentose phosphate pathway genes (n=6 per group). This was associated with better barrier function (n=6-8 per group) and less reactive oxygen species (n=7 or 8 per group) compared with activating glycolysis by VEGF165a. These effects were mediated by activating transcription factor 4, a driver of exercise-induced angiogenesis. In muscle biopsies from humans with peripheral arterial disease, EC/O-GlcNAcylation was increased by 12 weeks of supervised exercise versus standard medical care (n=6 per group).

CONCLUSIONS

In cells, mice, and humans, activation of hexosamine biosynthesis pathway by glucosamine in peripheral arterial disease induces an "exercise-like" angiogenesis and offers a promising novel therapeutic pathway to treat this challenging disorder.

Cadmium Exposure Induces Apoptosis and Necrosis of Thyroid Cells via the Regulation of miR-494-3p/PTEN Axis

Cadmium (Cd) exposure is a persistent pollution problem, necessitating caution in using cadmium-expelling complexing agents. Currently, there is no targeted therapy to treat Cd poisoning. The thyroid gland is a major endocrine organ that directly regulates thyroid hormones involved in various physiological processes and is a target organ for Cd accumulation. Herein, the effects of Cd exposure on swine thyroid glands were investigated. Six-week-old male pigs were randomly divided into the Cd and control groups. The control group was fed a normal diet containing 0 mg Cd/kg, while the Cd group was fed a diet containing 20 mg Cd/kg (CdCl2) for 40 days. The regulation mechanism of phosphatase and tensin homolog (PTEN) microRNA-494-3p (miR-494-3p) was evaluated to determine the toxic effects of Cd exposure on free radicals' cleaner. Notably, heat shock proteins (HSPs) were triggered as defense agents against Cd. Cd exposure increased the enzyme activity of superoxide dismutase1(SOD1) and SOD2, catalase (CAT), and glutathione (GSH), and the endoplasmic reticulum stress in thyroid cells. Histopathological staining, RT-qPCR, and Western Blot assays were further employed to detect possible apoptosis and necroptosis of thyroid cells induced by Cd exposure. The assays revealed increased thyroid inflammatory injury, fibrosis, and apoptosis caused by Cd exposure. This study demonstrates the role of microRNAs in regulating Cd toxicity in pig thyroid tissue and provides evidence of Cd's negative effects. It further provides an assessment of the toxicological impact of Cd as an environmental endocrine disruptor (ED) that threatens public health and safety, which forms a basis for the development of Cd poisoning treatment therapies.

FLT4 causes developmental disorders of the cardiovascular and lymphovascular systems via pleiotropic molecular mechanisms

AIMS

Rare, deleterious genetic variants in FLT4 are associated with Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease. The distinct genetic variants in FLT4 are also an established cause of Milroy disease, the most prevalent form of primary hereditary lymphoedema. The phenotypic features of these two conditions are non-overlapping, implying pleiotropic cellular mechanisms during development.

METHODS AND RESULTS

In this study, we show that FLT4 variants identified in patients with TOF, when expressed in primary human endothelial cells, cause aggregation of FLT4 protein in the perinuclear endoplasmic reticulum, activating proteostatic and metabolic signalling, whereas lymphoedema-associated FLT4 variants and wild-type (WT) FLT4 do not. FLT4 TOF variants display characteristic gene expression profiles in key developmental signalling pathways, revealing a role for FLT4 in cardiogenesis distinct from its role in lymphatic development. Inhibition of proteostatic signalling abrogates these effects, identifying potential avenues for therapeutic intervention. Depletion of flt4 in zebrafish caused cardiac phenotypes of reduced heart size and altered heart looping. These phenotypes were rescued with coinjection of WT human FLT4 mRNA, but incompletely or not at all by mRNA harbouring FLT4 TOF variants.

CONCLUSION

Taken together, we identify a pathogenic mechanism for FLT4 variants predisposing to TOF that is distinct from the known dominant negative mechanism of Milroy-causative variants. FLT4 variants give rise to conditions of the two circulatory subdivisions of the vascular system via distinct developmental pleiotropic molecular mechanisms.

Endothelial Slc35a1 Deficiency Causes Loss of LSEC Identity and Exacerbates Neonatal Lipid Deposition in the Liver in Mice

BACKGROUND & AIMS

The functional maturation of the liver largely occurs after birth. In the early stages of life, the liver of a newborn encounters enormous high-fat metabolic stress caused by the consumption of breast milk. It is unclear how the maturing liver adapts to high lipid metabolism. Liver sinusoidal endothelial cells (LSECs) play a fundamental role in establishing liver vasculature and are decorated with many glycoproteins on their surface. The Slc35a1 gene encodes a cytidine-5'-monophosphate (CMP)-sialic acid transporter responsible for transporting CMP-sialic acids between the cytoplasm and the Golgi apparatus for protein sialylation. This study aimed to determine whether endothelial sialylation plays a role in hepatic vasculogenesis and functional maturation.

METHODS

Endothelial-specific Slc35a1 knockout mice were generated. Liver tissues were collected for histologic analysis, lipidomic profiling, RNA sequencing, confocal immunofluorescence, and immunoblot analyses.

RESULTS

Endothelial Slc35a1-deficient mice exhibited excessive neonatal hepatic lipid deposition, severe liver damage, and high mortality. Endothelial deletion of Slc35a1 led to sinusoidal capillarization and disrupted hepatic zonation. Mechanistically, vascular endothelial growth factor receptor 2 (VEGFR2) in LSECs was desialylated and VEGFR2 signaling was enhanced in Slc35a1-deficient mice. Inhibition of VEGFR2 signaling by SU5416 alleviated lipid deposition and restored hepatic vasculature in Slc35a1-deficient mice.

CONCLUSIONS

Our findings suggest that sialylation of LSECs is critical for maintaining hepatic vascular development and lipid homeostasis. Targeting VEGFR2 signaling may be a new strategy to prevent liver disorders associated with abnormal vasculature and lipid deposition.

Temperature-sensitive hydrogel releasing pectolinarin facilitate scarless wound healing

The dressing that promotes scarless healing is essential for both normal function and aesthetics after a wound. With a deeper understanding of the mechanisms involved in scar formation during the wound healing process, the ideal dressing becomes clearer and more promising. For instance, the yes-associated transcriptional regulator (YAP) has been extensively studied as a key gene involved in regulating scar formation. However, there has been limited attention given to pectolinarin, a natural flavonoid that may exhibit strong binding affinity to YAP, in the context of scarless healing. In this study, we successfully developed a temperature-sensitive Pluronic@F-127 hydrogel as a platform for delivering pectolinarin to promote scarless wound healing. The bioactive pectolinarin was released from the hydrogel, effectively enhancing endothelial cell migration, proliferation and the expression of angiogenesis-related genes. Additionally, a concentration of 20 μg/mL of pectolinarin demonstrated remarkable antioxidant ability, capable of counteracting the detrimental effects of reactive oxygen species (ROS). Our results from rat wound healing models demonstrated that the hydrogel accelerated wound healing, promoting re-epithelialization and facilitating skin appendage regeneration. Furthermore, we discovered that a concentration of 50 μg/mL of pectolinarin incorporated to the hydrogel exhibited the most favourable outcomes in terms of promoting wound healing and minimizing scar formation. Overall, our study highlights that the significant potential of locally released pectolinarin might substantially inhibit YAP and promoting scarless wound healing.

Fingerprint of the oxido-reductase ERO1: A protein disulfide bond producer and supporter of cancer

Endoplasmic reticulum oxidoreductin 1 (ERO1) alpha (ERO1A) is an endoplasmic reticulum (ER)-localized protein disulfide oxidoreductase, involved in the disulfide bond formation of proteins. ERO1's activity in oxidative protein folding is redundant in higher eukaryotes and its loss is well compensated. Although it is dispensable in non-cancer cells, high ERO1 levels are seen with different cancers and predict their malignant phenotype. ERO1 fosters tumor aggressiveness and the response to drug therapy in hypoxic and highly metastatic tumors. It regulates vascular endothelial growth factor (VEGF) levels, oxidative folding and N-glycosylation in hypoxic conditions, boosting tumor fitness and angiogenesis on multiple levels. In addition, ERO1 regulates protein death ligand-1 (PD-L1) on tumors, interfering with the related immune surveillance mechanism, hence acting on the tumors' response to immune check-point inhibitors (ICI). This all points to inhibition of ERO1 as an effective pharmacological tool, selectively targeting tumors while sparing non-cancer cells from cytotoxicity. The critical discussion here closely examines the molecular basis for ERO1's involvement in tumors and ERO1 inhibition strategies for their treatment.

Biology and therapeutic targeting of vascular endothelial growth factor A

The formation of new blood vessels, called angiogenesis, is an essential pathophysiological process in which several families of regulators have been implicated. Among these, vascular endothelial growth factor A (VEGFA; also known as VEGF) and its two tyrosine kinase receptors, VEGFR1 and VEGFR2, represent a key signalling pathway mediating physiological angiogenesis and are also major therapeutic targets. VEGFA is a member of the gene family that includes VEGFB, VEGFC, VEGFD and placental growth factor (PLGF). Three decades after its initial isolation and cloning, VEGFA is arguably the most extensively investigated signalling system in angiogenesis. Although many mediators of angiogenesis have been identified, including members of the FGF family, angiopoietins, TGFβ and sphingosine 1-phosphate, all current FDA-approved anti-angiogenic drugs target the VEGF pathway. Anti-VEGF agents are widely used in oncology and, in combination with chemotherapy or immunotherapy, are now the standard of care in multiple malignancies. Anti-VEGF drugs have also revolutionized the treatment of neovascular eye disorders such as age-related macular degeneration and ischaemic retinal disorders. In this Review, we emphasize the molecular, structural and cellular basis of VEGFA action as well as recent findings illustrating unexpected interactions with other pathways and provocative reports on the role of VEGFA in regenerative medicine. We also discuss clinical and translational aspects of VEGFA. Given the crucial role that VEGFA plays in regulating angiogenesis in health and disease, this molecule is largely the focus of this Review.

Targeting angiogenesis in oncology, ophthalmology and beyond

Angiogenesis is an essential process in normal development and in adult physiology, but can be disrupted in numerous diseases. The concept of targeting angiogenesis for treating diseases was proposed more than 50 years ago, and the first two drugs targeting vascular endothelial growth factor (VEGF), bevacizumab and pegaptanib, were approved in 2004 for the treatment of cancer and neovascular ophthalmic diseases, respectively. Since then, nearly 20 years of clinical experience with anti-angiogenic drugs (AADs) have demonstrated the importance of this therapeutic modality for these disorders. However, there is a need to improve clinical outcomes by enhancing therapeutic efficacy, overcoming drug resistance, defining surrogate markers, combining with other drugs and developing the next generation of therapeutics. In this Review, we examine emerging new targets, the development of new drugs and challenging issues such as the mode of action of AADs and elucidating mechanisms underlying clinical benefits; we also discuss possible future directions of the field.

Expression and Characterization of a GH38 α-Mannosidase from the Hyperthermophile Pseudothermotoga thermarum

This study focused on the bio-characterization of a GH38 α-mannosidase from the hyperthermophile Pseudothermotoga thermarum DSM 5069. We aimed to successfully express and characterize this thermophilic α-mannosidase and to assess its functional properties. Subsequently, recombinant α-mannosidase PtαMan was expressed in Escherichia coli BL21(DE3) and purified via affinity chromatography, and native protein was verified as a tetramer by size exclusion chromatography. In addition, the activity of α-mannosidase PtαMan was relatively stable at pH 5.0-6.5 and temperatures up to 75 ℃. α-Mannosidase PtαMan was active toward Co²⁺ and had a good catalytic efficiency deduced from the kinetic parameters. However, its activity was strongly inhibited by Cu²⁺, Zn²⁺, SDS, and swainsonine. In summary, this cobalt-required α-mannosidase is putatively involved in the direct modification of glycoproteins.

Targeting VEGF-A/VEGFR2 Y949 Signaling-Mediated Vascular Permeability Alleviates Hypoxic Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) is associated with increased expression of VEGF-A (vascular endothelial growth factor A) and its receptor, VEGFR2 (vascular endothelial growth factor 2), but whether and how activation of VEGF-A signal participates in the pathogenesis of PH is unclear.

METHODS

VEGF-A/VEGFR2 signal activation and VEGFR2 Y949-dependent vascular leak were investigated in lung samples from patients with PH and mice exposed to hypoxia. To study their mechanistic roles in hypoxic PH, we examined right ventricle systolic pressure, right ventricular hypertrophy, and pulmonary vasculopathy in mutant mice carrying knock-in of phenylalanine that replaced the tyrosine at residual 949 of VEGFR2 (Vefgr2^Y949F) and mice with conditional endothelial deletion of Vegfr2 after chronic hypoxia exposure.

RESULTS

We show that PH leads to excessive pulmonary vascular leak in both patients and hypoxic mice, and this is because of an overactivated VEGF-A/VEGFR2 Y949 signaling axis. In the context of hypoxic PH, activation of Yes1 and c-Src and subsequent VE-cadherin phosphorylation in endothelial cells are involved in VEGFR2 Y949-induced vascular permeability. Abolishing VEGFR2 Y949 signaling by Vefgr2^Y949F point mutation was sufficient to prevent pulmonary vascular permeability and inhibit macrophage infiltration and Rac1 activation in smooth muscle cells under hypoxia exposure, thereby leading to alleviated PH manifestations, including muscularization of distal pulmonary arterioles, elevated right ventricle systolic pressure, and right ventricular hypertrophy. It is important that we found that VEGFR2 Y949 signaling in myeloid cells including macrophages was trivial and dispensable for hypoxia-induced vascular abnormalities and PH. In contrast with selective blockage of VEGFR2 Y949 signaling, disruption of the entire VEGFR2 signaling by conditional endothelial deletion of Vegfr2 promotes the development of PH.

CONCLUSIONS

Our results support the notion that VEGF-A/VEGFR2 Y949-dependent vascular permeability is an important determinant in the pathogenesis of PH and might serve as an attractive therapeutic target pathway for this disease.

Deglycosylation Increases the Aggregation and Angiogenic Properties of Mutant Tissue Inhibitor of Metalloproteinase 3 Protein: Implications for Sorsby Fundus Dystrophy

Sorsby fundus dystrophy (SFD) is an autosomal dominant macular disorder caused by mutations in tissue Inhibitor of the metalloproteinase-3 (TIMP3) gene with the onset of symptoms including choroidal neovascularization as early as the second decade of life. We have previously reported that wild-type TIMP3 is an endogenous angiogenesis inhibitor that inhibits Vascular Endothelial Growth Factor (VEGF)-mediated signaling in endothelial cells. In contrast, SFD-related S179C-TIMP3 when expressed in endothelial cells, does not have angiogenesis-inhibitory properties. To evaluate if this is a common feature of TIMP3 mutants associated with SFD, we examined and compared endothelial cells expressing S179C, Y191C and S204C TIMP3 mutants for their angiogenesis-inhibitory function. Western blot analysis, zymography and reverse zymography and migration assays were utilized to evaluate TIMP3 protein, Matrix Metalloproteinase (MMP) and MMP inhibitory activity, VEGF signaling and in vitro migration in endothelial cells expressing (VEGF receptor-2 (VEGFR-2) and wild-type TIMP3 or mutant-TIMP3. We demonstrate that mutant S179C, Y191C- and S204C-TIMP3 all show increased glycosylation and multimerization/aggregation of the TIMP3 protein. In addition, endothelial cells expressing TIMP3 mutations show increased angiogenic activities and elevated VEGFR-2. Removal of N-glycosylation by mutation of Asn¹⁸⁴, the only potential N-glycosylation site in mutant TIMP3, resulted in increased aggregation of TIMP3, further upregulation of VEGFR-2, VEGF-induced phosphorylation of VEGFR2 and VEGF-mediated migration concomitant with reduced MMP inhibitory activity. These results suggest that even though mutant TIMP3 proteins are more glycosylated, post-translational deglycosylation may play a critical role in the aggregation of mutant TIMP3 and contribute to the pathogenesis of SFD. The identification of factors that might contribute to changes in the glycome of patients with SFD will be useful. Future studies will evaluate whether variations in the glycosylation of mutant TIMP3 proteins are contributing to the severity of the disease.

ERO1 alpha deficiency impairs angiogenesis by increasing N-glycosylation of a proangiogenic VEGFA

N-glycosylation and disulfide bond formation are two essential steps in protein folding that occur in the endoplasmic reticulum (ER) and reciprocally influence each other. Here, to analyze crosstalk between N-glycosylation and oxidation, we investigated how the protein disulfide oxidase ERO1-alpha affects glycosylation of the angiogenic VEGF¹²¹, a key regulator of vascular homeostasis. ERO1 deficiency, while retarding disulfide bond formation in VEGF¹²¹, increased utilization of its single N-glycosylation sequon, which lies close to an intra-polypeptide disulfide bridge, and concomitantly slowed its secretion. Unbiased mass-spectrometric analysis revealed interactions between VEGF¹²¹ and N-glycosylation pathway proteins in ERO1-knockout (KO), but not wild-type cells. Notably, MAGT1, a thioredoxin-containing component of the post-translational oligosaccharyltransferase complex, was a major hit exclusive to ERO1-deficient cells. Thus, both a reduced rate of formation of disulfide bridges, and the increased trapping potential of MAGT1 may increase N-glycosylation of VEGF¹²¹. Extending our investigation to tissues, we observed altered lectin staining of ERO1 KO breast tumor xenografts, implicating ERO1 as a physiologic regulator of protein N-glycosylation. Our study, highlighting the effect of ERO1 loss on N-glycosylation of proteins, is particularly relevant not only to angiogenesis but also to other cancer patho-mechanisms in light of recent findings suggesting a close causal link between alterations in protein glycosylation and cancer development.

Combining Single-Cell and Transcriptomic Data Revealed the Prognostic Significance of Glycolysis in Pancreatic Cancer

Background: Pancreatic cancer (PC), the most common fatal solid malignancy, has a very dismal prognosis. Clinical computerized tomography (CT) and pathological TNM staging are no longer sufficient for determining a patient’s prognosis. Although numerous studies have suggested that glycolysis is important in the onset and progression of cancer, there are few publications on its impact on PC.

Methods: To begin, the single-sample gene set enrichment analysis (ssGSEA) approach was used to quantify the glycolysis pathway enrichment fraction in PC patients and establish its prognostic significance. The genes most related to the glycolytic pathway were then identified using weighted gene co-expression network analysis (WGCNA). The glycolysis-associated prognostic signature in PC patients was then constructed using univariate Cox regression and lasso regression methods, which were validated in numerous external validation cohorts. Furthermore, we investigated the activation of the glycolysis pathway in PC cell subtypes at the single-cell level, performed a quasi-time series analysis on the activated cell subtypes and then detected gene changes in the signature during cell development. Finally, we constructed a decision tree and a nomogram that could divide the patients into different risk subtypes, according to the signature score and their different clinical characteristics and assessed the prognosis of PC patients.

Results: Glycolysis plays a risky role in PC patients. Our glycolysis-related signature could effectively discriminate the high-risk and low-risk patients in both the trained cohort and the independent externally validated cohort. The survival analysis and multivariate Cox analysis indicated this gene signature to be an independent prognostic factor in PC. The prognostic ROC curve analysis suggested a high accuracy of this gene signature in predicting the patient prognosis in PC. The single-cell analysis suggested that the glycolytic pathway may be more activated in epithelial cells and that the genes in the signature were also mainly expressed in epithelial cells. The decision tree analysis could effectively identify patients in different risk subgroups, and the nomograms clearly show the prognostic assessment of PC patients.

Conclusion: Our study developed a glycolysis-related signature, which contributes to the risk subtype assessment of patients with PC and to the individualized management of patients in the clinical setting.

Quantification of Tumor Abnormal Proteins in the Diagnosis and Postoperative Prognostic Evaluation of Gastric Cancer

Background:

Abnormal glycosylation of proteins has been identified in almost all types of cancers and is closely related to the cancer progression, metastasis, and survival of cancer patients. This study was to explore the values of serum tumor abnormal protein (TAP), an abnormal glycochain protein, in the diagnosis and prognosis of gastric cancer (GC).

Methods:

A total of 335 GC patients were included as the study group, and another 335 subjects served as the control group. Tumor abnormal protein expression was compared between the 2 groups. Correlation analysis was used to assess the correlations of TAP with clinicopathological factors. Gastric cancer patients were divided into training set and test set at a ratio of 2:1. Univariate and multivariate Cox regression analyses in training set were used to evaluate the prognostic significance of TAP in GC patients and explore the independent risk factors for overall survival (OS) and disease-free survival (DFS) to establish a prognostic model, followed by testing of the model. According to the median of TAP, 335 GC patients were divided into 2 groups to plot the survival curves of OS and DFS.

Results:

Tumor abnormal protein expression in the study group was significantly higher than in the control group. Taking the best cut-off value of TAP (110.128 μm²) as the diagnostic criteria for GC, the sensitivity and specificity of TAP were 83.58% and 97.61%, respectively, and the area under the receiver operating characteristics (ROC) curve was 0.935, which was not inferior to computed tomography (CT). Tumor abnormal protein expression was an independent risk factor for OS and DFS. The prognostic predictive value of TAP was better than that of pathological stage in GC patients. The model with TAP was effective in predicting prognosis.

Conclusion:

Tumor abnormal protein is an effective indicator for early screening and prognostic evaluation of GC and can also assist the clinical diagnosis and treatment of GC.

2-Deoxy-d-glucose induces deglycosylation of proinflammatory cytokine receptors and strongly reduces immunological responses in mouse models of inflammation

Anti‐proinflammatory cytokine therapies against interleukin (IL)‐6, tumor necrosis factor (TNF)‐α, and IL‐1 are major advancements in treating inflammatory diseases, especially rheumatoid arthritis. Such therapies are mainly performed by injection of antibodies against cytokines or cytokine receptors. We initially found that the glycolytic inhibitor 2‐deoxy‐d‐glucose (2‐DG), a simple monosaccharide, attenuated cellular responses to IL‐6 by inhibiting N‐linked glycosylation of the IL‐6 receptor gp130. Aglycoforms of gp130 did not bind to IL‐6 or activate downstream intracellular signals that included Janus kinases. 2‐DG completely inhibited dextran sodium sulfate‐induced colitis, a mouse model for inflammatory bowel disease, and alleviated laminarin‐induced arthritis in the SKG mouse, an experimental model for human rheumatoid arthritis. These diseases have been shown to be partially dependent on IL‐6. We also found that 2‐DG inhibited signals for other proinflammatory cytokines such as TNF‐α, IL‐1β, and interferon ‐γ, and accordingly, prevented death by another inflammatory disease, lipopolysaccharide (LPS) shock. Furthermore, 2‐DG prevented LPS shock, a model for a cytokine storm, and LPS‐induced pulmonary inflammation, a model for acute respiratory distress syndrome of coronavirus disease 2019 (COVID‐19). These results suggest that targeted therapies that inhibit cytokine receptor glycosylation are effective for treatment of various inflammatory diseases.

Synthesis of zwitterionic polymer modified graphene oxide for hydrophilic enrichment of N-glycopeptides from urine of healthy subjects and patients with lung adenocarcinoma

As one of the most common and important post-translational modifications, protein N-glycosylation plays essential roles in many biological processes and have long been considered closely correlated with the occurrence and progression of multiple diseases. Systematic characterization of these disease-related protein N-glycosylation is one of the most convenient ways for new diagnostic biomarker and therapeutic drug target discovering. However, the biological samples are extremely complex and the abundance of N-glycoproteins are especially low, which make highly efficient N-glycoprotein/glycopeptide enrichment before mass spectrometry analysis a prerequisite. In this work, a new type of hydrophilic material (GO-pDMAPS) was prepared by in situ growth of linear zwitterionic polymer chains on the surface of GO and it was successfully applied for N-glycopeptide enrichment from human urine. Due to the excellent hydrophilicity and the facilitate interactions between this GO-pDMAPS and the targets, a total of 1426 N-glycosylated sites corresponding to 766 N-glycoproteins as well as 790 N-glycosylation sites corresponding to 470 N-glycoproteins were enriched and identified from urine of healthy subjects and patients with lung adenocarcinoma, respectively. Among which, 27 N-glycoproteins were expressed exclusively and 4 N-glycoproteins were upregulated at least 3 times comparing with the healthy group, demonstrating the tremendous potential of this new hydrophilic material for large scale and in depth N-glycoproteome research.

Elevated N-Glycosylation Contributes to the Cisplatin Resistance of Non-Small Cell Lung Cancer Cells Revealed by Membrane Proteomic and Glycoproteomic Analysis

Chemoresistance is the major restriction on the clinical use of cisplatin. Aberrant changes in protein glycosylation are closely associated with drug resistance. Comprehensive study on the role of protein glycosylation in the development of cisplatin resistance would contribute to precise elucidation of the complicated mechanism of resistance. However, comprehensive characterization of glycosylated proteins remains a big challenge. In this work, we integrated proteomic and N-glycoproteomic workflow to comprehensively characterize the cisplatin resistance-related membrane proteins. Using this method, we found that proteins implicated in cell adhesion, migration, response to drug, and signal transduction were significantly altered in both protein abundance and glycosylation level during the development of cisplatin resistance in the non-small cell lung cancer cell line. Accordingly, the ability of cell migration and invasion was markedly increased in cisplatin-resistant cells, hence intensifying their malignancy. In contrast, the intracellular cisplatin accumulation was significantly reduced in the resistant cells concomitant with the down-regulation of drug uptake channel protein, LRRC8A, and over-expression of drug efflux pump proteins, MRP1 and MRP4. Moreover, the global glycosylation was elevated in the cisplatin-resistant cells. Consequently, inhibition of N-glycosylation reduced cell resistance to cisplatin, whereas promoting the high-mannose or sialylated type of glycosylation enhanced the resistance, suggesting that critical glycosylation type contributes to cisplatin resistance. These results demonstrate the high efficiency of the integrated proteomic and N-glycoproteomic workflow in discovering drug resistance-related targets, and provide new insights into the mechanism of cisplatin resistance.

LIF, a mitogen for choroidal endothelial cells, protects the choriocapillaris: implications for prevention of geographic atrophy

In the course of our studies aiming to discover vascular bed-specific endothelial cell (EC) mitogens, we identified leukemia inhibitory factor (LIF) as a mitogen for bovine choroidal EC (BCE), although LIF has been mainly characterized as an EC growth inhibitor and an anti-angiogenic molecule. LIF stimulated growth of BCE while it inhibited, as previously reported, bovine aortic EC (BAE) growth. The JAK-STAT3 pathway mediated LIF actions in both BCE and BAE cells, but a caspase-independent proapoptotic signal mediated by cathepsins was triggered in BAE but not in BCE. LIF administration directly promoted activation of STAT3 and increased blood vessel density in mouse eyes. LIF also had protective effects on the choriocapillaris in a model of oxidative retinal injury. Analysis of available single-cell transcriptomic datasets shows strong expression of the specific LIF receptor in mouse and human choroidal EC. Our data suggest that LIF administration may be an innovative approach to prevent atrophy associated with AMD, through protection of the choriocapillaris.

Heparin-binding VEGFR1 variants as long-acting VEGF inhibitors for treatment of intraocular neovascular disorders

Neovascularization is a key feature of ischemic retinal diseases and the wet form of age-related macular degeneration (AMD), all leading causes of severe vision loss. Vascular endothelial growth factor (VEGF) inhibitors have transformed the treatment of these disorders. Millions of patients have been treated with these drugs worldwide. However, in real-life clinical settings, many patients do not experience the same degree of benefit observed in clinical trials, in part because they receive fewer anti-VEGF injections. Therefore, there is an urgent need to discover and identify novel long-acting VEGF inhibitors. We hypothesized that binding to heparan-sulfate proteoglycans (HSPG) in the vitreous, and possibly other ocular structures, may be a strategy to promote intraocular retention, ultimately leading to a reduced burden of intravitreal injections. We designed a series of VEGF receptor 1 variants and identified some with strong heparin-binding characteristics and ability to bind to vitreous matrix. Our data indicate that some of our variants have longer duration and greater efficacy in animal models of intraocular neovascularization than current standard of care. Our study represents a systematic attempt to exploit the functional diversity associated with heparin affinity of a VEGF receptor.