O-GlcNAc Transferase Regulates Angiogenesis in Idiopathic Pulmonary Arterial Hypertension

Dysregulation of the Long Non-coding RNA Xist Expression in Male Patients with Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a sex-biased disease with female gender as a significant risk factor. Recently, we reported that increased expression of the long non-coding (lnc)RNA Xist, as induced by an intersectin-1s protein fragment with proliferative potential (EHITSN), may explain the sexual dimorphism of female pulmonary artery endothelial cells (ECs) and at least in part, the imbalance sex/ratio of PAH. Xist is essential for X-chromosome inactivation and dosage compensation of X-linked genes. Increased Xist expression was also detected in a subset of ECs and lung tissue samples of male PAH patients. The role of different Xist expression levels in ECs of male PAH patients (ECPAH) was studied in several lines of male ECPAH in conjunction with molecular, biochemical, morphological, and functional approaches. Male ECPAH showed on average 10.3-fold increase in high Xist vs. low Xist, a significant association between Xist levels and their proliferative potential, and a heterogeneous methylation of the Xist/Tsix locus. Interestingly, Xist up-regulation in male ECPAH decreases the expression of Klf2, via EHITSN interaction with EZH2, the catalytic subunit of the polycomb repressive complex 2. Moreover, the studies demonstrate that EHITSN-triggered p38/Elk1/c-Fos signaling is a pathological mechanism central to ECPAH proliferation and the dynamic crosstalk with cell cycle regulatory proteins ccna1/ccnd2, and Xist-EZH2-Klf2 interaction participate directly and differentially in establishing the proliferative profile of male ECPAH.

O-GlcNAc regulates anti-fibrotic genes in lung fibroblasts through EZH2

Epigenetic modifications are involved in fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), and contribute to the silencing of anti-fibrotic genes. H3K27me3, a key repressive histone mark, is catalysed by the methyltransferase enhancer of Zeste homologue 2 (EZH2), which is regulated by the post-translational modification, O-linked N-Acetylglucosamine (O-GlcNAc). In this study, we explored the effects of O-GlcNAc and EZH2 on the expression of antifibrotic genes, cyclooxygenase-2 (Cox2) and Heme Oxygenase (Homx1). The expression of Cox2 and Hmox1 was examined in primary IPF or non-IPF lung fibroblasts with or without EZH2 inhibitor EZP6438, O-GlcNAc transferase (OGT) inhibitor (OSMI-1) or O-GlcNAcase (OGA) inhibitor (thiamet G). Non-IPF cells were also subjected to TGF-β1 with or without OGT inhibition. The reduced expression of Cox2 and Hmox1 in IPF lung fibroblasts is restored by OGT inhibition. In non-IPF fibroblasts, TGF-β1 treatment reduces Cox2 and Hmox1 expression, which was restored by OGT inhibition. ChIP assays demonstrated that the association of H3K27me3 is reduced at the Cox2 and Hmox1 promoter regions following OGT or EZH2 inhibition. EZH2 levels and stability were decreased by reducing O-GlcNAc. Our study provided a novel mechanism of O-GlcNAc modification in regulating anti-fibrotic genes in lung fibroblasts and in the pathogenesis of IPF.

FUT8-Mediated Core Fucosylation Promotes the Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive cardiopulmonary disease with unclear underlying molecular mechanisms and limited therapeutic options. This study aimed to explore the role of core fucosylation and the only glycosyltransferase FUT8 in PAH. We observed increased core fucosylation in a monocrotaline (MCT)-induced PAH rat model and isolated rat pulmonary artery smooth muscle cells (PASMCs) treated with platelet-derived growth factor-BB (PDGF-BB). We found that 2-fluorofucose (2FF), a drug used to inhibit core fucosylation, improved hemodynamics and pulmonary vascular remodeling in MCT-induced PAH rats. In vitro, 2FF effectively restrains the proliferation, migration, and phenotypic switching of PASMCs and promotes apoptosis. Compared with controls, serum FUT8 concentration in PAH patients and MCT-induced rats was significantly elevated. FUT8 expression appeared increased in the lung tissues of PAH rats, and the co-localization of FUT8 with α-SMA was also observed. SiRNA was used to knockdown FUT8 in PASMCs (siFUT8). After effectively silencing FUT8 expression, phenotypic changes induced in PASMCs by PDGF-BB stimulation were alleviated. FUT8 activated the AKT pathway, while the admission of AKT activator SC79 could partially counteract the negative effect of siFUT8 on the proliferation, apoptotic resistance, and phenotypic switching of PASMCs, which may be involved in the core fucosylation of vascular endothelial growth factor receptor (VEGFR). Our research confirmed the critical role of FUT8 and its mediated core fucosylation in pulmonary vascular remodeling in PAH, providing a potential novel therapeutic target for PAH.

Comprehensive analyses of m6A RNA methylation patterns and related immune microenvironment in idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening disease with a poor prognosis and high heritability, characterized by elevated pulmonary vascular resistance (PVR) and pulmonary artery pressure. N6-methyladenosine (m6A) RNA modification influences many RNA metabolism pathways. However, the position of m6A methylation regulators in IPAH remains unknown. Therefore, the study aims to disclose the function m6A regulators exert in the pathological mechanisms of IPAH and the immune microenvironment involved. The GSE117261 dataset was downloaded from the Gene Expression Omnibus (GEO) to screen the differentially expressed genes (DEGs) between normal and IPAH samples. Functional and pathway enrichment analyses of DEGs were then conducted by Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG). We also identified the differentially-expressed m6A (DEm6A) regulators between normal and IPAH samples. Key m6A regulators related to the prediction of IPAH were selected using the random forest model. The results showed that FMR1, RBM15, HNRNPA2B1 and IGFBP3 were upregulated in IPAH. In contrast, LRPPRC was downregulated. The single sample gene set enrichment analysis (ssGSEA) method was then adopted to estimate the immune microenvironment in distinct m6A clusters and m6A phenotype-related genes (PRGs) clusters, respectively. Furthermore, we calculated the m6A score via principal component analysis (PCA), and the Sankey diagram was selected to present the correlation among the m6A clusters, m6A PRGs clusters and m6A score. Finally, quantitative RT-PCR and Western blotting were used to validate the key genes in human pulmonary artery smooth muscle cells (HPASMCs) treated by human platelet-derived growth factor-BB (PDGF-BB). The relative mRNA and protein expression levels of FMR1 were significantly elevated, however, the relative mRNA and protein expression levels of LRPPRC were downregulated. Besides, the relative mRNA level of HNRNPA2B1 was increased. Generally, this bioinformatics analysis might provoke more insights into diagnosing and treating IPAH.

Oscillatory shear stress-mediated aberrant O-GlcNAc SIRT3 accelerates glycocalyx inflammatory injury via LKB1/p47phox/Hyal2 signaling

Glycocalyx coating on endothelial surface layer helps to sense shear forces and maintain endothelial function. However, the underlying mechanism of endothelial glycocalyx degradation upon disordered shear stress stimulation is not fully understood. SIRT3, a major NAD⁺-dependent protein deacetylases, is required for protein stability during vascular homeostasis and partly involved in atherosclerotic process. While few studies showed that SIRT3 is responsible for endothelial glycocalyx homeostasis under shear stress, the underlying mechanisms remain largely unknown. Here, we demonstrated that oscillatory shear stress (OSS) induces glycocalyx injury by activating LKB1/p47^phox/Hyal2 axis both in vivo and in vitro. And O-GlcNAc modification served to prolong SIRT3 deacetylase activity and stabilized p47/Hyal2 complex. OSS could decrease SIRT3 O-GlcNAcylation to activate LKB1, further accelerated endothelial glycocalyx injury in inflammatory microenvironment. SIRT3^Ser329 mutation or inhibition of SIRT3 O-GlcNAcylation strongly promoted glycocalyx degradation. On the contrary, overexpression of SIRT3 reverse glycocalyx damage upon OSS treatment. Together, our findings indicated that targeting O-GlcNAcylation of SIRT3 could prevent and/or treat diseases whereby glycocalyx injured.

Targeting protein glycosylation to regulate inflammation in the respiratory tract: novel diagnostic and therapeutic candidates for chronic respiratory diseases

Protein glycosylation is a widespread posttranslational modification that can impact the function of proteins. Dysregulated protein glycosylation has been linked to several diseases, including chronic respiratory diseases (CRDs). CRDs pose a significant public health threat globally, affecting the airways and other lung structures. Emerging researches suggest that glycosylation plays a significant role in regulating inflammation associated with CRDs. This review offers an overview of the abnormal glycoenzyme activity and corresponding glycosylation changes involved in various CRDs, including chronic obstructive pulmonary disease, asthma, cystic fibrosis, idiopathic pulmonary fibrosis, pulmonary arterial hypertension, non-cystic fibrosis bronchiectasis, and lung cancer. Additionally, this review summarizes recent advances in glycomics and glycoproteomics-based protein glycosylation analysis of CRDs. The potential of glycoenzymes and glycoproteins for clinical use in the diagnosis and treatment of CRDs is also discussed.

Protein O-GlcNAcylation in cardiovascular diseases

O-GlcNAcylation is a post-translational modification of protein in response to genetic variations or environmental factors, which is controlled by two highly conserved enzymes, i.e. O-GlcNAc transferase (OGT) and protein O-GlcNAcase (OGA). Protein O-GlcNAcylation mainly occurs in the cytoplasm, nucleus, and mitochondrion, and it is ubiquitously implicated in the development of cardiovascular disease (CVD). Alterations of O-GlcNAcylation could cause massive metabolic imbalance and affect cardiovascular function, but the role of O-GlcNAcylation in CVD remains controversial. That is, acutely increased O-GlcNAcylation is an adaptive heart response, which temporarily protects cardiac function. While it is harmful to cardiomyocytes if O-GlcNAcylation levels remain high in chronic conditions or in the long run. The underlying mechanisms include regulation of transcription, energy metabolism, and other signal transduction reactions induced by O-GlcNAcylation. In this review, we will focus on the interactions between protein O-GlcNAcylation and CVD, and discuss the potential molecular mechanisms that may be able to pave a new avenue for the treatment of cardiovascular events.

Bladder Cancer-Derived Small Extracellular Vesicles Promote Tumor Angiogenesis by Inducing HBP-Related Metabolic Reprogramming and SerRS O-GlcNAcylation in Endothelial Cells

A malformed tumour vascular network provokes the nutrient-deprived tumour microenvironment (TME), which conversely activates endothelial cell (EC) functions and stimulates neovascularization. Emerging evidence suggests that the flexible metabolic adaptability of tumour cells helps to establish a metabolic symbiosis among various cell subpopulations in the fluctuating TME. In this study, the authors propose a novel metabolic link between bladder cancer (BCa) cells and ECs in the nutrient-scarce TME, in which BCa-secreted glutamine-fructose-6-phosphate aminotransferase 1 (GFAT1) via small extracellular vesicles (sEVs) reprograms glucose metabolism by increasing hexosamine biosynthesis pathway flux in ECs and thus enhances O-GlcNAcylation. Moreover, seryl-tRNA synthetase (SerRS) O-GlcNAcylation at serine 101 in ECs promotes its degradation by ubiquitination and impeded importin α5-mediated nuclear translocation. Intranuclear SerRS attenuates vascular endothelial growth factor transcription by competitively binding to the GC-rich region of the proximal promotor. Additionally, GFAT1 knockout in tumour cells blocks SerRS O-GlcNAcylation in ECs and attenuates angiogenesis both in vitro and in vivo. However, administration of GFAT1-overexpressing BCa cells-derived sEVs increase the angiogenetic activity in the ECs of GFAT1-knockout mice. In summary, this study suggests that inhibiting sEV-mediated GFAT1 secretion from BCa cells and targeting SerRS O-GlcNAcylation in ECs may serve as novel strategies for BCa antiangiogenetic therapy.

Integrated Microarray for Identifying the Hub mRNAs and Constructed MiRNA-mRNA Network in Coronary In-stent Restenosis

As a major complication after percutaneous coronary intervention (PCI) in patients who suffer from coronary artery disease, in-stent restenosis (ISR) poses a significant challenge for clinical management. A miRNA-mRNA regulatory network of ISR can be constructed to better reveal the occurrence of ISR. The relevant dataset from the Gene Expression Omnibus (GEO) database was downloaded, and 284 differentially expressed miRNAs (DE-miRNAs) and 849 differentially expressed mRNAs (DE-mRNAs) were identified. As predicted by online tools, 65 final functional genes (FmRNAs) were overlapping DE-mRNAs and DE-miRNAs target genes. In the biological process (BP) terms of Gene Ontology (GO) functional analysis, the FmRNAs were mainly enriched in cellular response to peptide, epithelial cell proliferation and response to peptide hormone. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the FmRNAs were mainly enriched in breast cancer, endocrine resistance and cushing syndrome. Jun Proto-Oncogene, AP-1 Transcription Factor Subunit (JUN), Insulin Like Growth Factor 1 Receptor (IGF1R), Member RAS Oncogene Family (RAB14), Specificity Protein 1 (SP1), Protein Tyrosine Phosphatase Non-Receptor Type1(PTPN1), DDB1 And CUL4 Associated Factor 10 (DCAF10), Retinoblastoma-Binding Protein 5 (RBBP5) and Eukaryotic Initiation Factor 4A-I (EIF4A1) were hub genes in the protein-protein interaction network (PPI network). The miRNA-mRNA network containing DE-miRNA and hub genes was built. Hsa-miR-139-5p-JUN, hsa-miR-324-5p-SP1 axis pairs were found in the miRNA-mRNA network, which could promote ISR development. The above results indicate that the miRNA-mRNA network constructed in ISR has a regulatory role in the development of ISR, and may provide new approaches for clinical treatment and experimental development.

The Effect of High and Variable Glucose on the Viability of Endothelial Cells Co-Cultured with Smooth Muscle Cells

Diabetes mellitus causes endothelial dysfunction. The aim of this study was to investigate the effect of normal (5 mmol/L), high (20 mmol/L), and fluctuating (5 and 20 mmol/L changed every day) glucose concentration in the culture medium on the viability of human umbilical vein endothelial cells (HUVECs) co-cultured with human umbilical artery smooth muscle cells (HUASMCs). The cultures were conducted on semi-permeable flat polysulfone (PSU) fibronectin-coated membranes immobilized in self-made inserts. The insert contained either HUVECs on a single membrane or HUASMCs and HUVECs on two membranes close to each other. Cultures were conducted for 7 or 14 days. Apoptosis, mitochondrial potential, and the production of reactive oxygen species and lactate by HUVECs were investigated. The results indicate that fluctuations in glucose concentration have a stronger negative effect on HUVECs viability than constant high glucose concentration. High and fluctuating glucose concentrations slow down cell proliferation compared to the culture carried out in the medium with normal glucose concentration. In conclusion, HUASMCs affect the viability of HUVECs when both types of cells are co-cultured in medium with normal or variable glucose concentration.

The Glycobiology of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease of complex etiology. Cases of PAH that do not receive therapy after diagnosis have a low survival rate. Multiple reports have shown that idiopathic PAH, or IPAH, is associated with metabolic dysregulation including altered bioavailability of nitric oxide (NO) and dysregulated glucose metabolism. Multiple processes such as increased proliferation of pulmonary vascular cells, angiogenesis, apoptotic resistance, and vasoconstriction may be regulated by the metabolic changes demonstrated in PAH. Recent reports have underscored similarities between metabolic abnormalities in cancer and IPAH. In particular, increased glucose uptake and altered glucose utilization have been documented and have been linked to the aforementioned processes. We were the first to report a link between altered glucose metabolism and changes in glycosylation. Subsequent reports have highlighted similar findings, including a potential role for altered metabolism and aberrant glycosylation in IPAH pathogenesis. This review will detail research findings that demonstrate metabolic dysregulation in PAH with an emphasis on glycobiology. Furthermore, this report will illustrate the similarities in the pathobiology of PAH and cancer and highlight the novel findings that researchers have explored in the field.

The Role of Glutamine and Glutaminase in Pulmonary Hypertension

Pulmonary hypertension (PH) refers to a clinical and pathophysiological syndrome in which pulmonary vascular resistance and pulmonary arterial pressure are increased due to structural or functional changes in pulmonary vasculature caused by a variety of etiologies and different pathogenic mechanisms. It is followed by the development of right heart failure and even death. In recent years, most studies have found that PH and cancer shared a complex common pathological metabolic disturbance, such as the shift from oxidative phosphorylation to glycolysis. During the shifting process, there is an upregulation of glutamine decomposition driven by glutaminase. However, the relationship between PH and glutamine hydrolysis, especially by glutaminase is yet unclear. This review aims to explore the special linking among glutamine hydrolysis, glutaminase and PH, so as to provide theoretical basis for clinical precision treatment in PH.

Heterotypic Multicellular Spheroids as Experimental and Preclinical Models of Sprouting Angiogenesis

Sprouting angiogenesis is the common response of live tissues to physiological and pathological angiogenic stimuli. Its accurate evaluation is of utmost importance for basic research and practical medicine and pharmacology and requires adequate experimental models. A variety of assays for angiogenesis were developed, none of them perfect. In vitro approaches are generally less physiologically relevant due to the omission of essential components regulating the process. However, only in vitro models can be entirely non-xenogeneic. The limitations of the in vitro angiogenesis assays can be partially overcome using 3D models mimicking tissue O2 and nutrient gradients, the influence of the extracellular matrix (ECM), and enabling cell-cell interactions. Here we present a review of the existing models of sprouting angiogenesis that are based on the use of endothelial cells (ECs) co-cultured with perivascular or other stromal cells. This approach provides an excellent in vitro platform for further decoding of the cellular and molecular mechanisms of sprouting angiogenesis under conditions close to the in vivo conditions, as well as for preclinical drug testing and preclinical research in tissue engineering and regenerative medicine.

Identification of Hub Genes and MicroRNAs Associated With Idiopathic Pulmonary Arterial Hypertension by Integrated Bioinformatics Analyses

Objective

The aim of this study is the identification of hub genes associated with idiopathic pulmonary arterial hypertension (IPAH).

Materials and Methods

GSE15197 gene expression data was downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified by screening IPAH patients and controls. The 5,000 genes with the greatest variances were analyzed using a weighted gene co-expression network analysis (WGCNA). Modules with the strongest correlation with IPAH were chosen, followed by a functional enrichment analysis. Protein–protein interaction (PPI) networks were constructed to identify hub gene candidates using calculated degrees. Real hub genes were found from the overlap of DEGs and candidate hub genes. microRNAs (miRNAs) targeting real hub genes were found by screening miRNet 2.0. The most important IPAH miRNAs were identified.

Results

There were 4,395 DEGs identified. WGCNA indicated that green and brown modules associated most strongly with IPAH. Functional enrichment analysis showed that green and brown module genes were mainly involved in protein digestion and absorption and proteoglycans in cancer, respectively. The top ten candidate hub genes in green and brown modules were identified, respectively. After overlapping with DEGs, 11 real hub genes were identified: EP300, MMP2, CDH2, CDK2, GNG10, ALB, SMC2, DHX15, CUL3, BTBD1, and LTN1. These genes were expressed with significant differences in IPAH versus controls, indicating a high diagnostic ability. The miRNA–gene network showed that hsa-mir-1-3p could associate with IPAH.

Conclusion

EP300, MMP2, CDH2, CDK2, GNG10, ALB, SMC2, DHX15, CUL3, BTBD1, and LTN1 may play essential roles in IPAH. Predicted miRNA hsa-mir-1-3p could regulate gene expression in IPAH. Such hub genes may contribute to the pathology and progression in IPAH, providing potential diagnostic and therapeutic opportunities for IPAH patients.

ECM2 and GLT8D2 in human pulmonary artery hypertension: fruits from weighted gene co-expression network analysis

Background

Pulmonary artery hypertension (PAH) is an incurable disease with a high mortality rate. Current medications ameliorate symptoms but cannot target adverse vascular remodeling. New therapeutic strategies for PAH need to be established.

Methods

Using the weighted gene coexpression network analysis (WGCNA) algorithm, we constructed a coexpression network of dataset GSE117261 from the Gene Expression Omnibus (GEO) database. Key modules were identified by the relationship between module eigengenes and clinical traits. Hub genes were screened out based on gene significance (GS), module membership (MM), and mean pulmonary artery pressure (mPAP). External validations were conducted in GSE48149 and GSE113439. Functional enrichment and immune cell infiltration were analyzed using Metascape and CIBERSORTx.

Results

The WGCNA analysis revealed 13 coexpression modules. The pink module had the highest correlation with PAH in terms of module eigengene (r=0.79; P=2e-18) and module significance (MS =0.43). Functional enrichment indicated genes in the pink module contributed to the immune system process and extracellular matrix (ECM). In the pink module, ECM2 (GS =0.65, MM =0.86, ρ=0.407, P=0.0019) and GLT8D2 (GS =0.63, MM =0.85, ρ=0.443, P=0.006) were identified as hub genes. For immune cells infiltration in PAH lung tissue, hub genes were positively correlated with M2 macrophages and resting mast cells, and were negatively correlated with monocytes, neutrophils, and CD4-naïve T cells.

Conclusions

Our research identified 2 hub genes ECM2 and GLT8D2 related to PAH. The functions of these hub genes were involved in the immune process and ECM, indicating that they might serve as candidate therapeutic targets for PAH.

P53 in the impaired lungs

Our laboratory is focused on investigating the supportive role of P53 towards the maintenance of lung homeostasis. Acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, pulmonary fibrosis, bronchial asthma, pulmonary arterial hypertension, pneumonia and tuberculosis are respiratory pathologies, associated with dysfunctions of this endothelium defender (P53). Herein we review the evolving role of P53 towards the aforementioned inflammatory disorders, to potentially reveal new therapeutic possibilities in pulmonary disease.

Effects of FTMT Expression by Retinal Pigment Epithelial Cells on Features of Angiogenesis

Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, can result from pathological angiogenesis. As a mutation in the mitochondrial ferritin (FTMT) gene has been associated with AMD, its possible role in modulating angiogenic factors and angiogenesis was investigated. FTMT is an iron-sequestering protein primarily expressed in metabolically active cells and tissues with high oxygen demand, including retina. In this study, we utilized the human retinal pigment epithelial cell line ARPE-19, both as undifferentiated and differentiated cells. The effects of proinflammatory cytokines, FTMT knockdown, and transient and stable overexpression of FTMT were investigated on expression of pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial-derived factor (PEDF). Proinflammatory cytokines induced FTMT and VEGF expression, while NF-κB inhibition significantly reduced FTMT expression. VEGF protein and mRNA expression were significantly increased in FTMT-silenced ARPE-19 cells. Using an in vitro angiogenesis assay with endothelial cells, we showed that conditioned media from FTMT-overexpressing cells had significant antiangiogenic effects. Collectively, our findings indicate that increased levels of FTMT inhibit angiogenesis, possibly by reducing levels of VEGF and increasing PEDF expression. The cellular models developed can be used to investigate if increased FTMT may be protective in angiogenic diseases, such as AMD.

Metabolic Reprogramming in Health and Disease

This editorial aims to summarize the six scientific papers that contributed to this Special Issue.

Regulatory Effects of O-GlcNAcylation in Vascular Smooth Muscle Cells on Diabetic Vasculopathy

Vascular complications from uncontrolled hyperglycemia are the leading cause of death in patients with diabetes mellitus. Previous reports have shown a strong correlation between hyperglycemia and vascular calcification, which increases mortality and morbidity in individuals with diabetes. However, the precise underlying molecular mechanisms of hyperglycemia-induced vascular calcification remain largely unknown. Transdifferentiation of vascular smooth muscle cells (VSMC) into osteoblast-like cells is a known culprit underlying the development of vascular calcification in the diabetic vasculature. Pathological conditions such as high glucose levels and oxidative stress are linked to enhanced osteogenic differentiation of VSMC both in vivo and in vitro. It has been demonstrated that increased expression of runt-related transcription factor 2 (Runx2), a bone-related transcription factor, in VSMC is necessary and sufficient for the induction of VSMC calcification. Addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) moiety to the serine/threonine residues of target proteins (O-GlcNAcylation) has been observed in the arteries of diabetic patients, as well as in animal models in association with the enhanced expression of Runx2 and aggravated vascular calcification. O-GlcNAcylation is a dynamic and tightly regulated process, that is mediated by 2 enzymes, O-GlcNAc transferase and O-GlcNAcase. Glucose is metabolized into UDP-β-D-N-acetylglucosamine, an active sugar donor of O-GlcNAcylation via the hexosamine biosynthetic pathway. Overall increases in the O-GlcNAcylation of cellular proteins have been closely associated with cardiovascular complications of diabetes. In this review, the authors provide molecular insights into cardiovascular complications, including diabetic vasculopathy, that feature increased O-GlcNAcylation in people with diabetes.