O-GlcNAcylation Suppresses the Ion Current IClswell by Preventing the Binding of the Protein ICln to α-Integrin

O-GlcNAc transferase mediates O-GlcNAcylation of NLRP3 regulates pyroptosis in spinal cord injury

BACKGROUND

Spinal cord injury (SCI) represents a severe disorder of the nervous system, imposing significant physical, psychological, and socioeconomic burdens on affected individuals and society.

OBJECTIVE

We investigated the implication of O-linked β-N-acetylglucosamine (O-GlcNAcylation) in regulating pyroptosis related proteins at the posttranslational level.

MATERIALS AND METHODS

PC12 cells were stimulated with lipopolysaccharide (LPS). The O-GlcNAcylation pathway was modified by manipulating the expression of O-GlcNAc transferase (OGT) or O-GlcNAcase (OGA). Pro-inflammatory cytokine levels and cell pyroptosis were assessed. Co-immunoprecipitation (Co-IP) assays were employed to investigate the interaction between NLRP3 and OGT. For in vivo studies, an established SCI rat model was utilized. Levels of pro-inflammatory factors, NLRP3 inflammasome components, and proteins associated with pyroptosis were measured.

RESULTS

Both O-GlcNAc levels and OGT expression were significantly elevated in the SCI model cells. Inhibition of OGT led to a marked reduction in the levels of pro-inflammatory cytokines and a suppression of pyroptosis. Furthermore, inhibition of OGT resulted in downregulation of NLRP3 and its O-GlcNAcylation, while overexpression of OGT produced the opposite effect. We verified the endogenous and exogenous interactions between NLRP3 and OGT. Importantly, knockout of OGT mitigated the progression of SCI in an animal model, suggesting a protective role of OGT inhibition in SCI.

DISCUSSION AND CONCLUSION

This study preliminarily proved that the mechanism of OGT mediated O-GlcNAcylation of NLRP3 participates in the action of pyroptosis in SCI. Targeting OGT and NLRP3 may be novel therapy method in SCI.

O-linked β-N-acetylglucosamine (O-GlcNAc) modification: Emerging pathogenesis and a therapeutic target of diabetic nephropathy

AIMS

O-Linked β-N-acetylglucosamine (O-GlcNAc) modification, a unique post-translational modification of proteins, is elevated in diabetic nephropathy. This review aims to summarize the current knowledge on the mechanisms by which O-GlcNAcylation of proteins contributes to the pathogenesis and progression of diabetic nephropathy, as well as the therapeutic potential of targeting O-GlcNAc modification for its treatment.

METHODS

Current evidence in the literature was reviewed and synthesized in a narrative review.

RESULTS

Hyperglycemia increases glucose flux into the hexosamine biosynthesis pathway, which activates glucosamino-fructose aminotransferase expression and activity, leading to the production of O-GlcNAcylation substrate UDP-GlcNAc and an increase in protein O-GlcNAcylation in kidney cells. Protein O-GlcNAcylation regulates the function of kidney cells including mesangial cells, podocytes, and proximal tubular cells, and promotes renal interstitial fibrosis, resulting in kidney damage. Current treatments for diabetic nephropathy, such as sodium-glucose cotransporter 2 (SGLT-2) inhibitors and renin-angiotensin-aldosterone system (RAAS) inhibitors, delay disease progression, and suppress protein O-GlcNAcylation.

CONCLUSIONS

Increased protein O-GlcNAcylation mediates renal cell damage and promotes renal interstitial fibrosis, leading to diabetic nephropathy. Although the full significance of inhibition of O-GlcNAcylation is not yet understood, it may represent a novel target for treating diabetic nephropathy.

Melatonin protects Kir2.1 function in an oxidative stress-related model of aging neuroglia

Melatonin is a pleiotropic biofactor and an effective antioxidant and free radical scavenger and, as such, can be protective in oxidative stress-related brain conditions including epilepsy and aging. To test the potential protective effect of melatonin on brain homeostasis and identify the corresponding molecular targets, we established a new model of oxidative stress-related aging neuroglia represented by U-87 MG cells exposed to D-galactose (D-Gal). This model was characterized by a substantial elevation of markers of oxidative stress, lipid peroxidation, and protein oxidation. The function of the inward rectifying K+ channel Kir2.1, which was identified as the main Kir channel endogenously expressed in these cells, was dramatically impaired. Kir2.1 was unlikely a direct target of oxidative stress, but the loss of function resulted from a reduction of protein abundance, with no alterations in transcript levels and trafficking to the cell surface. Importantly, melatonin reverted these changes. All findings, including the melatonin antioxidant effect, were reproduced in heterologous expression systems. We conclude that the glial Kir2.1 can be a target of oxidative stress and further suggest that inhibition of its function might alter the extracellular K+ buffering in the brain, therefore contributing to neuronal hyperexcitability and epileptogenesis during aging. Melatonin can play a protective role in this context.

AAPH-induced oxidative damage reduced anion exchanger 1 (SLC4A1/AE1) activity in human red blood cells: protective effect of an anthocyanin-rich extract

Introduction: During their lifespan in the bloodstream, red blood cells (RBCs) are exposed to multiple stressors, including increased oxidative stress, which can affect their morphology and function, thereby contributing to disease. Aim: This investigation aimed to explore the cellular and molecular mechanisms related to oxidative stress underlying anion exchanger 1 activity (band 3, SLC4A1/AE1) in human RBCs. To achieve this aim, the relationship between RBC morphology and functional and metabolic activity has been explored. Moreover, the potential protective effect of an anthocyanin-enriched fraction extracted from Callistemon citrinus flowers was studied. Methods: Cellular morphology, parameters of oxidative stress, as well as the anion exchange capability of band 3 have been analyzed in RBCs treated for 1 h with 50 mM of the pro-oxidant 2,2'-azobis (2-methylpropionamide)-dihydrochloride (AAPH). Before or after the oxidative insult, subsets of cells were exposed to 0.01 μg/mL of an anthocyanin-enriched fraction for 1 h. Results: Exposure to AAPH caused oxidative stress, exhaustion of reduced glutathione, and over-activation of the endogenous antioxidant machinery, resulting in morphological alterations of RBCs, specifically the formation of acanthocytes, increased lipid peroxidation and oxidation of proteins, as well as abnormal distribution and hyper-phosphorylation of band 3. Expected, oxidative stress was also associated with a decreased band 3 ion transport activity and an increase of oxidized haemoglobin, which led to abnormal clustering of band 3. Exposure of cells to the anthocyanin-enriched fraction prior to, but not after, oxidative stress efficiently counteracted oxidative stress-related alterations. Importantly, protection of band3 function from oxidative stress could only be achieved in intact cells and not in RBC ghosts. Conclusion: These findings contribute a) to clarify oxidative stress-related physiological and biochemical alterations in human RBCs, b) propose anthocyanins as natural antioxidants to neutralize oxidative stress-related modifications, and 3) suggest that cell integrity, and therefore a cytosolic component, is required to reverse oxidative stress-related pathophysiological derangements in human mature RBCs.

Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD

ABSTRACT

Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.

Mechanisms underlying the anti-aging activity of bergamot (Citrus bergamia) extract in human red blood cells

Introduction: Aging is a process characterised by a decline in physiological functions. Reactive species play a crucial role in the aging rate. Due to the close relationship between aging and oxidative stress, functional foods rich in phytochemicals are excellent candidates to neutralise age-related changes. Aim: This investigation aims to verify the potential protective role of bergamot (Citrus bergamia, Femminello cultivar) peel and juice extract in a model of aging represented by human red blood cells (RBCs) exposed to D-Galactose (DGal). Methods: Bergamot peel and juice extracts were subjected to RP-HPLC/PDA/MS for determination of their composition in bioactive compounds. Markers of oxidative stress, including ROS production, thiobarbituric acid reactive substances (TBARS) levels -a marker of lipid peroxidation, oxidation of total protein sulfhydryl groups, as well as the expression and anion exchange capability of band 3 and glycated haemoglobin (A1c) production have been investigated in RBCs treated with D-Gal for 24 h, with or without pre-incubation for 15 min with 5 μg/mL peel or juice extract. In addition, the activity of the endogenous antioxidant system, including catalase (CAT) and superoxide dismutase (SOD), as well as the diversion of the RBC metabolism from glycolysis towards the pentose phosphate pathway shunt, as denoted by activation of glucose-6-phosphate dehydrogenase (G6PDH), have been explored. Results: Data shown here suggest that bergamot peel and juice extract i) prevented the D-Gal-induced ROS production, and consequently, oxidative stress injury to biological macromolecules including membrane lipids and proteins; ii) significantly restored D-Gal-induced alterations in the distribution and ion transport kinetics of band 3; iii) blunted A1c production; iv) effectively impeded the over-activation of the endogenous antioxidant enzymes CAT and SOD; and v) significantly prevented the activation of G6PDH. Discussion: These results further contribute to shed light on aging mechanisms in human RBCs and identify bergamot as a functional food rich in natural antioxidants useful for prevention and treatment of oxidative stress-related changes, which may lead to pathological states during aging.

Aging Injury Impairs Structural Properties and Cell Signaling in Human Red Blood Cells; Açaì Berry Is a Keystone

Red blood cell (RBC) deformability is the ability of cells to modulate their shape to ensure transit through narrow capillaries of the microcirculation. A loss of deformability can occur in several pathological conditions, during natural RBC aging through an increase in membrane protein phosphorylation, and/or through the structural rearrangements of cytoskeletal proteins due to oxidative conditions, with a key role played by band 3. Due to the close relationship between aging and oxidative stress, flavonoid-rich foods are good candidates to counteract age-related alterations. This study aims to verify the beneficial role of Açaì extract in a d-Galactose (d-Gal)-induced model of aging in human RBCs. To this end, band 3 phosphorylation and structural rearrangements in membrane cytoskeleton-associated proteins, namely spectrin, ankyrin, and/or protein 4.1, are analyzed in RBCs treated with 100 mM d-Gal for 24 h, with or without pre-incubation with 10 μg/mL Açaì extract for 1 h. Furthermore, RBC deformability is also measured. Tyrosine phosphorylation of band 3, membrane cytoskeleton-associated proteins, and RBC deformability (elongation index) are analyzed using western blotting analysis, FACScan flow cytometry, and ektacytometry, respectively. The present data show that: (i) Açaì berry extract restores the increase in band 3 tyrosine phosphorylation and Syk kinase levels after exposure to 100 mM d-Gal treatment; and (ii) Açaì berry extract partially restores alterations in the distribution of spectrin, ankyrin, and protein 4.1. Interestingly, the significant decrease in membrane RBC deformability associated with d-Gal treatment is alleviated by pre-treatment with Açaì extract. These findings further contribute to clarify mechanisms of natural aging in human RBCs, and propose flavonoid substances as potential natural antioxidants for the treatment and/or prevention of oxidative-stress-related disease risk.

Emerging Role of Protein O-GlcNAcylation in Liver Metabolism: Implications for Diabetes and NAFLD

O-linked b-N-acetyl-glucosaminylation (O-GlcNAcylation) is one of the most common post-translational modifications of proteins, and is established by modifying the serine or threonine residues of nuclear, cytoplasmic, and mitochondrial proteins. O-GlcNAc signaling is considered a critical nutrient sensor, and affects numerous proteins involved in cellular metabolic processes. O-GlcNAcylation modulates protein functions in different patterns, including protein stabilization, enzymatic activity, transcriptional activity, and protein interactions. Disrupted O-GlcNAcylation is associated with an abnormal metabolic state, and may result in metabolic disorders. As the liver is the center of nutrient metabolism, this review provides a brief description of the features of the O-GlcNAc signaling pathway, and summarizes the regulatory functions and underlying molecular mechanisms of O-GlcNAcylation in liver metabolism. Finally, this review highlights the role of O-GlcNAcylation in liver-associated diseases, such as diabetes and nonalcoholic fatty liver disease (NAFLD). We hope this review not only benefits the understanding of O-GlcNAc biology, but also provides new insights for treatments against liver-associated metabolic disorders.

N-acetylglucosamine-bearing polymers mimicking O-GlcNAc-modified proteins elicit anti-fibrotic activities in myofibroblasts and activated stellate cells

O-linked β-N-acetylglucosamine (O-GlcNAc)-modified proteins are post-translationally modified with GlcNAc conjugated to serine and threonine residues. This modification is associated with various physiological functions such as serine and threonine phosphorylation and Notch signaling. Here, we demonstrated that O-GlcNAc-modified proteins leaked from dead cells and GlcNAc-bearing polymers mimicking the multivalent GlcNAc moiety of these proteins induced anti-fibrotic activities, such as the suppression of α-smooth muscle actin and collagen and the induction of matrix metalloprotease 1 in myofibroblasts. We have previously reported that O-GlcNAc-modified proteins and GlcNAc-bearing polymers could interact with cell surface vimentin and desmin. In the current study, it was demonstrated that a multivalent GlcNAc moiety structure of these molecules activated PI3K/Akt and p38MAPK pathway and elicited these anti-fibrotic activities in myofibroblasts by interacting with cell surface vimentin. Since the interaction of O-GlcNAc-modified proteins with desmin was observed in the fibrotic liver of carbon tetrachloride-treated mice via an in situ proximity ligation assay, it was assumed that the activated stellate cells could bind to the O-GlcNAc-modified proteins from the damaged hepatocytes. In addition, the administration of anti-O-GlcNAc antibody to inhibit the interaction exacerbated liver fibrosis in the mice. Moreover, administration of the GlcNAc-bearing polymers into carbon tetrachloride-treated mice could ameliorate liver fibrosis. Thus, O-GlcNAc-modified proteins leaked from dead cells can interact with myofibroblasts and activated stellate cells and function as fibrosis suppressors. Moreover, we anticipate that GlcNAc-bearing polymers mimicking O-GlcNAc-modified proteins will be applied as novel therapeutic tools for fibrosis.

Oxidative Stress and Immune Response in Melanoma: Ion Channels as Targets of Therapy

Oxidative stress and immune response play an important role in the development of several cancers, including melanoma. Ion channels are aberrantly expressed in tumour cells and regulate neoplastic transformation, malignant progression, and resistance to therapy. Ion channels are localized in the plasma membrane or other cellular membranes and are targets of oxidative stress, which is particularly elevated in melanoma. At the same time, ion channels are crucial for normal and cancer cell physiology and are subject to multiple layers of regulation, and therefore represent promising targets for therapeutic intervention. In this review, we analyzed the effects of oxidative stress on ion channels on a molecular and cellular level and in the context of melanoma progression and immune evasion. The possible role of ion channels as targets of alternative therapeutic strategies in melanoma was discussed.

GABAA and GABAB Receptors Mediate GABA-Induced Intracellular Ca2+ Signals in Human Brain Microvascular Endothelial Cells

Numerous studies recently showed that the inhibitory neurotransmitter, γ-aminobutyric acid (GABA), can stimulate cerebral angiogenesis and promote neurovascular coupling by activating the ionotropic GABA_A receptors on cerebrovascular endothelial cells, whereas the endothelial role of the metabotropic GABA_B receptors is still unknown. Preliminary evidence showed that GABA_A receptor stimulation can induce an increase in endothelial Ca²⁺ levels, but the underlying signaling pathway remains to be fully unraveled. In the present investigation, we found that GABA evoked a biphasic elevation in [Ca²⁺]_i that was initiated by inositol-1,4,5-trisphosphate- and nicotinic acid adenine dinucleotide phosphate-dependent Ca²⁺ release from neutral and acidic Ca²⁺ stores, respectively, and sustained by store-operated Ca²⁺ entry. GABA_A and GABA_B receptors were both required to trigger the endothelial Ca²⁺ response. Unexpectedly, we found that the GABA_A receptors signal in a flux-independent manner via the metabotropic GABA_B receptors. Likewise, the full Ca²⁺ response to GABA_B receptors requires functional GABA_A receptors. This study, therefore, sheds novel light on the molecular mechanisms by which GABA controls endothelial signaling at the neurovascular unit.

O-GlcNAcylation of SIRT1 Protects against Cold Stress-Induced Skeletal Muscle Damage via Amelioration of Mitochondrial Homeostasis

Cold stress disturbs cellular metabolic and energy homeostasis, which is one of the causes of stress-induced illnesses. O-GlcNAcylation is a nutrient-sensing pathway involved in a myriad of cellular processes. It plays a key role in metabolic homeostasis. Nevertheless, a specific sensing mechanism linking skeletal muscle to O-GlcNAcylation in cold stress is unknown. In this study, O-GlcNAcylation of SIRT1 was targeted to explore the mechanism of skeletal muscle adaptation to cold stress. Ogt mKO aggravated skeletal muscle fibrosis induced by cold stress. At the same time, Ogt gene deletion accelerated the homeostasis imbalance and oxidative stress of skeletal muscle mitochondria induced by cold stress. In vitro results showed that inhibition of SIRT1's O-GlcNAcylation accelerated mild hypothermia induced mitochondrial homeostasis in mouse myogenic cells (C2C12 cells). However, overexpression of SIRT1's O-GlcNAcylation improved the above phenomena. Thus, these results reveal a protective role of OGT-SIRT1 in skeletal muscle's adaptation to cold stress, and our findings will provide new avenues to combat stress-induced diseases.

Antioxidant Activity of Quercetin in a H2O2-Induced Oxidative Stress Model in Red Blood Cells: Functional Role of Band 3 Protein

During their lifespan, red blood cells (RBCs) are exposed to a large number of stressors and are therefore considered as a suitable model to investigate cell response to oxidative stress (OS). This study was conducted to evaluate the potential beneficial effects of the natural antioxidant quercetin (Q) on an OS model represented by human RBCs treated with H₂O₂. Markers of OS, including % hemolysis, reactive oxygen species (ROS) production, thiobarbituric acid reactive substances (TBARS) levels, oxidation of protein sulfhydryl groups, CD47 and B3p expression, methemoglobin formation (% MetHb), as well as the anion exchange capability through Band 3 protein (B3p) have been analyzed in RBCs treated for 1 h with 20 mM H₂O₂ with or without pre-treatment for 1 h with 10 μM Q, or in RBCs pre-treated with 20 mM H₂O₂ and then exposed to 10 µM Q. The results show that pre-treatment with Q is more effective than post-treatment to counteract OS in RBCs. In particular, pre-exposure to Q avoided morphological alterations (formation of acanthocytes), prevented H₂O₂-induced OS damage, and restored the abnormal distribution of B3p and CD47 expression. Moreover, H₂O₂ exposure was associated with a decreased rate constant of SO₄²⁻ uptake via B3p, as well as an increased MetHb formation. Both alterations have been attenuated by pre-treatment with 10 μM Q. These results contribute (1) to elucidate OS-related events in human RBCs, (2) propose Q as natural antioxidant to counteract OS-related alterations, and (3) identify B3p as a possible target for the treatment and prevention of OS-related disease conditions or aging-related complications impacting on RBCs physiology.

The Important Role of Ion Transport System in Cervical Cancer

Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca²⁺ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl⁻ channels and K⁺-Cl⁻ cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca²⁺ homeostasis, the Ca²⁺ store sensor STIM molecules and plasma membrane Ca²⁺ channel Orai proteins, the predominant Ca²⁺ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.

Role and Function of O-GlcNAcylation in Cancer

Simple Summary

Despite the rapid advancement in immunotherapy and targeted agents, many patients diagnosed with cancer have poor prognosis with dismal overall survival. One of the key hallmarks of cancer is the ability of cancer cells to reprogram their energy metabolism. O-GlcNAcylation is an emerging potential mechanism for cancer cells to induce proliferation and progression of tumor cells and resistance to chemotherapy. This review summarizes the mechanism behind O-GlcNAcylation and discusses the role of O-GlcNAcylation, including its function with receptor tyrosine kinase and chemo-resistance in cancer, and immune response to cancer and as a prognostic factor. Further pre-clinical studies on O-GlcNAcylation are warranted to assess the clinical efficacy of agents targeting O-GlcNAcylation.

Abstract

Cancer cells are able to reprogram their glucose metabolism and retain energy via glycolysis even under aerobic conditions. They activate the hexosamine biosynthetic pathway (HBP), and the complex interplay of O-linked N-acetylglucosaminylation (O-GlcNAcylation) via deprivation of nutrients or increase in cellular stress results in the proliferation, progression, and metastasis of cancer cells. Notably, cancer is one of the emerging diseases associated with O-GlcNAcylation. In this review, we summarize studies that delineate the role of O-GlcNAcylation in cancer, including its modulation in metastasis, function with receptor tyrosine kinases, and resistance to chemotherapeutic agents, such as cisplatin. In addition, we discuss the function of O-GlcNAcylation in eliciting immune responses associated with immune surveillance in the tumor microenvironment. O-GlcNAcylation is increasingly accepted as one of the key players involved in the activation and differentiation of T cells and macrophages. Finally, we discuss the prognostic role of O-GlcNAcylation and potential therapeutic agents such as O-linked β-N-acetylglucosamine-transferase inhibitors, which may help overcome the resistance mechanism associated with the reprogramming of glucose metabolism.

Chronic Kidney Disease: Strategies to Retard Progression

Chronic kidney disease (CKD), defined as the presence of irreversible structural or functional kidney damages, increases the risk of poor outcomes due to its association with multiple complications, including altered mineral metabolism, anemia, metabolic acidosis, and increased cardiovascular events. The mainstay of treatments for CKD lies in the prevention of the development and progression of CKD as well as its complications. Due to the heterogeneous origins and the uncertainty in the pathogenesis of CKD, efficacious therapies for CKD remain challenging. In this review, we focus on the following four themes: first, a summary of the known factors that contribute to CKD development and progression, with an emphasis on avoiding acute kidney injury (AKI); second, an etiology-based treatment strategy for retarding CKD, including the approaches for the common and under-recognized ones; and third, the recommended approaches for ameliorating CKD complications, and the final section discusses the novel agents for counteracting CKD progression.

Role of Glycosylation in Vascular Calcification

Glycosylation is an important step in post-translational protein modification. Altered glycosylation results in an abnormality that causes diseases such as malignancy and cardiovascular diseases. Recent emerging evidence highlights the importance of glycosylation in vascular calcification. Two major types of glycosylation, N-glycosylation and O-glycosylation, are involved in vascular calcification. Other glycosylation mechanisms, which polymerize the glycosaminoglycan (GAG) chain onto protein, resulting in proteoglycan (PG), also have an impact on vascular calcification. This paper discusses the role of glycosylation in vascular calcification.