Disruption of tissue-specific fucosyltransferase VII, an enzyme necessary for selectin ligand synthesis, suppresses atherosclerosis in mice

The effects of glycosylation modifications on monocyte recruitment and foam cell formation in atherosclerosis

The monocyte recruitment and foam cell formation have been intensively investigated in atherosclerosis. Nevertheless, as the study progressed, it was obvious that crucial molecules participated in the monocyte recruitment and the membrane proteins in macrophages exhibited substantial glycosylation modifications. These modifications can exert a significant influence on protein functions and may even impact the overall progression of diseases. This article provides a review of the effects of glycosylation modifications on monocyte recruitment and foam cell formation. By elaborating on these effects, we aim to understand the underlying mechanisms of atherogenesis further and to provide new insights into the future treatment of atherosclerosis.

Identification of FUT7 hypomethylation as the blood biomarker in the prediction of early-stage lung cancer

Early detection of lung cancer (LC) is vital for reducing LC-related mortality. However, noninvasive diagnostic tools remain a great challenge. We aim to identify blood-based biomarkers for the early detection of LC. Here, LC-associated hypomethylation in alpha-1,3-fucosyltransferase VII (FUT7) is identified via the Illumina 850K array in a discovery study and validated by mass spectrometry in two independent case-control studies with blood samples from 1720 LC patients (86.8% LC at stage I, blood is collected before surgery and treatment) and 3143 healthy controls. Compared to the controls, blood-based FUT7 hypomethylation is identified in LC patients at stage I, and even in LC patients with malignant nodules ≤ 1 cm and in patients with adenocarcinoma in situ. Gender plays a role in the LC-associated FUT7 hypomethylation in blood, which is more significant in males than in females. We also reveal that FUT7 hypomethylation in LC could be enhanced by the advanced stage of cancer, involvement of lymph nodes, and larger tumor size. Based on a large sample size and semi-quantitative methods, our study reveals a strong association between blood-based FUT7 hypomethylation and LC, suggesting that methylation signatures in blood may be a group of potential biomarkers for detection of early-stage LC.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

The α1,3-fucosyltransferase FUT7 regulates IL-1β-induced monocyte-endothelial adhesion via fucosylation of endomucin

Monocyte-endothelial adhesion is a hallmark feature of atherosclerosis at early stage and emerging evidence suggests that the glycosylation of vascular adhesive molecules and its ligands is involved in this process. Nevertheless, the mechanism underlying this process remains incompletely elucidated. In this study, we reported that treatment with inflammatory factors interleukin-1β (IL-1β) pronouncedly upregulated α1,3-fucosyltransferase VII gene (FUT7) mRNA and protein expression level in EA.hy926 endothelial cells. Moreover, FUT7 overexpression significantly promoted monocyte-endothelial adhesion, while FUT7 knockdown obviously inhibited IL-1β-induced monocyte-endothelial adhesion. Further analysis demonstrated that fucosylation of selectin ligand endomucin was directly involved in IL-1β-induced monocyte-endothelial adhesion. Finally, we demonstrated that p38 and extracellular signal-regulated kinase (ERK) MAPK signaling pathway was activated by IL-1β, while inhibition of p38/ERK signaling pathway decreased FUT7 expression level and IL-1β-induced monocyte-endothelial adhesion. In summary, these results provide a novel insight that FUT7-mediated fucosylation contribute to the initiation and progression of atherosclerosis.

P-selectin and subclinical and clinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

P-selectin is a cellular adhesion molecule that has been shown to be crucial in development of coronary heart disease (CHD). We sought to determine the role of P-selectin on the risk of atherosclerosis in a large multi-ethnic population.

METHODS

Data from the Multi-Ethnic Study of Atherosclerosis (MESA), including 1628 African, 702 Chinese, 2393 non-Hispanic white, and 1302 Hispanic Americans, were used to investigate the association of plasma P-selectin with CHD risk factors, coronary artery calcium (CAC), intima-media thickness, and CHD. Regression models were used to investigate the association between P-selectin and risk factors, Tobit model for CAC, and Cox regression for CHD events.

RESULTS

Mean levels of P-selectin differed by ethnicity and were higher in men (P<0.001). For all ethnic groups, P-selectin was positively associated with measures of adiposity, blood pressure, current smoking, LDL, and triglycerides and inversely with HDL. A significant ethnic interaction was observed for the association of P-selectin and prevalent diabetes; however, P-selectin was positively associated with HbA1c in all groups. Higher P-selectin levels were associated with greater prevalence of CAC. Over 10.1 years of follow-up, there were 335 incident CHD events. There was a positive linear association between P-selectin levels and rate of incident CHD after adjustment for traditional risk factors. However, association was only significant in non-Hispanic white Americans (HR: 1.81, 95% CI 1.07 to 3.07, P=0.027).

CONCLUSION

We observed ethnic heterogeneity in the association of P-selectin and risk of CHD.

Glycosyltransferases, glycosylation and atherosclerosis

Cardiovascular diseases arising from atherosclerosis are currently the leading cause of mortality worldwide. Leukocyte recruitment is a key step for the successful initiation of atherosclerosis and occurs predominantly in the inflamed endothelium. Leukocyte recruitment is mediated by a group of adhesive molecules and chemokine receptors, which are often glycosylated protein. Recent studies demonstrated that post-translational glycosylation by glycosyltransferases is necessary for adhesive molecules and chemokine receptors activities. Several glycosyltransferases, such as α2,3-sialyltransferases IV, α1,3-fucosyltransferases IV and VII, core 2 β1,6-N-acetylglucosaminyltransferase-I, are considered to participate in the synthesis of glycosylation for adhesive molecules and chemokine receptors, and the initiation of atherosclerotic lesions. In this review, we will discuss new data concerning the roles of different glycosyltransferases in atherogenesis. The knowledge of glycosyltransferases in atherogenesis offers the opportunity to develop novel therapeutic strategies.

Molecular biology of atherosclerosis

At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.

α(1,3)-Fucosyltransferases FUT4 and FUT7 control murine susceptibility to thrombosis

The α(1,3)-fucosyltransferases, types IV and VII (FUT4 and FUT7, respectively), are required for the synthesis of functional selectin-type leukocyte adhesion molecule ligands. The selectins and their ligands modulate leukocyte trafficking, and P-selectin and its ligand, P-selectin glycoprotein ligand-1, can modulate hemostasis and thrombosis. Regulation of thrombosis by FUT4 and/or FUT7 activity was examined in mouse models of carotid artery thrombosis and collagen/epinephrine-induced thromboembolism. Mice lacking both FUT4 and FUT7 (Fut(-/-) mice) had a shorter time to occlusive thrombus formation in the injured carotid artery and a higher mortality due to collagen/epinephrine-induced pulmonary thromboemboli. Mice lacking P-selectin or P-selectin glycoprotein ligand-1 did not have a prothrombotic phenotype. Whole blood platelet aggregation was enhanced, and plasma fibrinogen content, clot weight, and clot strength were increased in Fut(-/-) mice, and in vitro clot lysis was reduced compared with wild type. Fut4(-/-), but not Fut7(-/-), mice had increased pulmonary thromboembolism-induced mortality and decreased thromboemboli dissolution in vivo. These data show that FUT4 and FUT7 activity regulates thrombosis in a P-selectin- and P-selectin glycoprotein ligand-1-independent manner and suggest that FUT4 activity is important for thrombolysis.

Global metabolic inhibitors of sialyl- and fucosyltransferases remodel the glycome

Despite the fundamental roles of sialyl- and fucosyltransferases in mammalian physiology, there are few pharmacological tools to manipulate their function in a cellular setting. Although fluorinated analogs of the donor substrates are well-established transition state inhibitors of these enzymes, they are not membrane permeable. By exploiting promiscuous monosaccharide salvage pathways, we show that fluorinated analogs of sialic acid and fucose can be taken up and metabolized to the desired donor substrate-based inhibitors inside the cell. Because of the existence of metabolic feedback loops, they also act to prevent the de novo synthesis of the natural substrates, resulting in a global, family-wide shutdown of sialyl- and/or fucosyltransferases and remodeling of cell-surface glycans. As an example of the functional consequences, the inhibitors substantially reduce expression of the sialylated and fucosylated ligand sialyl Lewis X on myeloid cells, resulting in loss of selectin binding and impaired leukocyte rolling.