scholarly journals Cross-talk between GlcNAcylation and phosphorylation: roles in insulin resistance and glucose toxicity

2008 ◽  
Vol 295 (1) ◽  
pp. E17-E28 ◽  
Author(s):  
Ronald J. Copeland ◽  
John W. Bullen ◽  
Gerald W. Hart

O-linked β- N-acetylglucosamine ( O-GlcNAc) is a dynamic posttranslational modification that, analogous to phosphorylation, cycles on and off serine and/or threonine hydroxyl groups. Cycling of O-GlcNAc is regulated by the concerted actions of O-GlcNAc transferase and O-GlcNAcase. GlcNAcylation is a nutrient/stress-sensitive modification that regulates proteins involved in a wide array of biological processes, including transcription, signaling, and metabolism. GlcNAcylation is involved in the etiology of glucose toxicity and chronic hyperglycemia-induced insulin resistance, a major hallmark of type 2 diabetes. Several reports demonstrate a strong positive correlation between GlcNAcylation and the development of insulin resistance. However, recent studies suggest that inhibiting GlcNAcylation does not prevent hyperglycemia-induced insulin resistance, suggesting that other mechanisms must also be involved. To date, proteomic analyses have identified more than 600 GlcNAcylated proteins in diverse functional classes. However, O-GlcNAc sites have been mapped on only a small percentage (<15%) of these proteins, most of which were isolated from brain or spinal cord tissue and not from other metabolically relevant tissues. Mapping the sites of GlcNAcylation is not only necessary to elucidate the complex cross-talk between GlcNAcylation and phosphorylation but is also key to the design of site-specific mutational studies and necessary for the generation of site-specific antibodies, both of which will help further decipher O-GlcNAc's functional roles. Recent technical advances in O-GlcNAc site-mapping methods should now finally allow for a much-needed increase in site-specific analyses to address the functional significance of O-GlcNAc in insulin resistance and glucose toxicity as well as other major biological processes.

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 159-OR
Author(s):  
THEODORE P. CIARALDI ◽  
SUNDER MUDALIAR ◽  
LIWU LI ◽  
ROSARIO SCALIA ◽  
XIAO JIAN SUN ◽  
...  

2019 ◽  
Vol 25 (23) ◽  
pp. 2602-2606 ◽  
Author(s):  
Shahzad Khan ◽  
Mohammad A. Kamal

: Insulin resistance and type 2 Diabetes mellitus resulting in chronic hyperglycemia is a major health problem in the modern world. Many drugs have been tested to control hyperglycemia which is believed to be the main factor behind many of the diabetes-related late-term complications. Wogonin is a famous herbal medicine which has been shown to be effective in controlling diabetes and its complications. In our previous work, we showed that wogonin is beneficial in many ways in controlling diabetic cardiomyopathy. In this review, we mainly explained wogonin anti-hyperglycemic property through AKT/GLUT4 pathway. Here we briefly discussed that wogonin increases Glut4 trafficking to plasma membrane which allows increased entry of glucose and thus alleviates hyperglycemia. Conclusion: Wogonin can be used as an anti-diabetic and anti-hyperglycemic drug and works via AKT/GLUT4 pathway.


2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Gaoyue Jiang ◽  
Chunxia Li ◽  
Meng Lu ◽  
Kefeng Lu ◽  
Huihui Li

AbstractLysine crotonylation has been discovered in histone and non-histone proteins and found to be involved in diverse diseases and biological processes, such as neuropsychiatric disease, carcinogenesis, spermatogenesis, tissue injury, and inflammation. The unique carbon–carbon π-bond structure indicates that lysine crotonylation may use distinct regulatory mechanisms from the widely studied other types of lysine acylation. In this review, we discussed the regulation of lysine crotonylation by enzymatic and non-enzymatic mechanisms, the recognition of substrate proteins, the physiological functions of lysine crotonylation and its cross-talk with other types of modification. The tools and methods for prediction and detection of lysine crotonylation were also described.


2021 ◽  
Vol 22 (7) ◽  
pp. 3463
Author(s):  
Chia-Hung Lin ◽  
Chen-Chung Liao ◽  
Mei-Yu Chen ◽  
Teh-Ying Chou

Protein O-GlcNAcylation is a dynamic post-translational modification involving the attachment of N-acetylglucosamine (GlcNAc) to the hydroxyl groups of Ser/Thr residues on numerous nucleocytoplasmic proteins. Two enzymes are responsible for O-GlcNAc cycling on substrate proteins: O-GlcNAc transferase (OGT) catalyzes the addition while O-GlcNAcase (OGA) helps the removal of GlcNAc. O-GlcNAcylation modifies protein functions; therefore, dysregulation of O-GlcNAcylation affects cell physiology and contributes to pathogenesis. To maintain homeostasis of cellular O-GlcNAcylation, there exists feedback regulation of OGT and OGA expression responding to fluctuations of O-GlcNAc levels; yet, little is known about the molecular mechanisms involved. In this study, we investigated the O-GlcNAc-feedback regulation of OGT and OGA expression in lung cancer cells. Results suggest that, upon alterations in O-GlcNAcylation, the regulation of OGA expression occurs at the mRNA level and likely involves epigenetic mechanisms, while modulation of OGT expression is through translation control. Further analyses revealed that the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) contributes to the downregulation of OGT induced by hyper-O-GlcNAcylation; the S5A/S6A O-GlcNAcylation-site mutant of 4E-BP1 cannot support this regulation, suggesting an important role of O-GlcNAcylation. The results provide additional insight into the molecular mechanisms through which cells may fine-tune intracellular O-GlcNAc levels to maintain homeostasis.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Muhammad Sohail Khan ◽  
Muhammad Ikram ◽  
Tae Ju Park ◽  
Myeong Ok Kim

The pathology and neurodegeneration in type 2 diabetes- (T2D-) mediated Alzheimer’s disease (AD) have been reported in several studies. Despite the lack of information regarding the basic underlying mechanisms involved in the development of T2D-mediated AD, some common features of the two conditions have been reported, such as brain atrophy, reduced cerebral glucose metabolism, and insulin resistance. T2D phenotypes such as glucose dyshomeostasis, insulin resistance, impaired insulin signaling, and systemic inflammatory cytokines have been shown to be involved in the progression of AD pathology by increasing amyloid-beta accumulation, tau hyperphosphorylation, and overall neuroinflammation. Similarly, oxidative stress, mitochondrial dysfunction, and the generation of advanced glycation end products (AGEs) and their receptor (RAGE) as a result of chronic hyperglycemia may serve as critical links between diabetes and AD. The natural dietary polyflavonoid anthocyanin enhances insulin sensitivity, attenuates insulin resistance at the level of the target tissues, inhibits free fatty acid oxidation, and abrogates the release of peripheral inflammatory cytokines in obese (prediabetic) individuals, which are responsible for insulin resistance, systemic hyperglycemia, systemic inflammation, brain metabolism dyshomeostasis, amyloid-beta accumulation, and neuroinflammatory responses. In this review, we have shown that obesity may induce T2D-mediated AD and assessed the recent therapeutic advances, especially the use of anthocyanin, against T2D-mediated AD pathology. Taken together, the findings of current studies may help elucidate a new approach for the prevention and treatment of T2D-mediated AD by using the polyflavonoid anthocyanin.


Author(s):  
DIVYA JYOTHI P ◽  
DOONDI PHANI KUMAR N ◽  
VINAY MOHAN A ◽  
RAMYA A

Diabetes mellitus (DM) is not one disorder; it represents a series of metabolic conditions related to hyperglycemia and caused by defects in hormone secretion and hormone action. Exposure to chronic hyperglycemia may result in microvascular complications in the retina (diabetic retinopathy), kidney (diabetic nephropathy), neuron (diabetic-neuropathy), skin, foot, and cardiac complications (stroke, hypertension…etc.). International Diabetes Federation estimates that 1.1 million children and adolescents aged 14–19 years have type one DM. Without interventions to halt the increase in diabetes, there will be at least 629 million people living with diabetes by 2045. In the body, white adipose tissue is the leading site for the storage of excess energy produced from the food intake in large quantities, of the development of insulin resistance (IR) and type 2 DM by the over intake of fatty acid in the body. It results in the accumulation of fatty acyl co-A (FA-CoA) within the myocytes. It leads to improper signaling of the insulin and reduces the level in the myocytes and pancreases beta cells. It combines with genetically reduces the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) coactivator-1, initiates the inflammation process by the activation of the tumor necrotic factor alpha and protein kinase C. These alterations lead to further increase the intramyocellular FA-CoA and triglycerides. The sequence of events may develop mitochondrial dysfunction in the sarcolemma outer layers. Finally improves IR also with increasing intramyocellular lipids. This concept might be helpful to those who are pursuing endocrinology specialization, nursing staff, pharmacists, and other medical departments.


2018 ◽  
Vol 115 (38) ◽  
pp. E8996-E9005 ◽  
Author(s):  
Brandon M. Gassaway ◽  
Max C. Petersen ◽  
Yulia V. Surovtseva ◽  
Karl W. Barber ◽  
Joshua B. Sheetz ◽  
...  

Insulin resistance drives the development of type 2 diabetes (T2D). In liver, diacylglycerol (DAG) is a key mediator of lipid-induced insulin resistance. DAG activates protein kinase C ε (PKCε), which phosphorylates and inhibits the insulin receptor. In rats, a 3-day high-fat diet produces hepatic insulin resistance through this mechanism, and knockdown of hepatic PKCε protects against high-fat diet-induced hepatic insulin resistance. Here, we employed a systems-level approach to uncover additional signaling pathways involved in high-fat diet-induced hepatic insulin resistance. We used quantitative phosphoproteomics to map global in vivo changes in hepatic protein phosphorylation in chow-fed, high-fat–fed, and high-fat–fed with PKCε knockdown rats to distinguish the impact of lipid- and PKCε-induced protein phosphorylation. This was followed by a functional siRNA-based screen to determine which dynamically regulated phosphoproteins may be involved in canonical insulin signaling. Direct PKCε substrates were identified by motif analysis of phosphoproteomics data and validated using a large-scale in vitro kinase assay. These substrates included the p70S6K substrates RPS6 and IRS1, which suggested cross talk between PKCε and p70S6K in high-fat diet-induced hepatic insulin resistance. These results identify an expanded set of proteins through which PKCε may drive high-fat diet-induced hepatic insulin resistance that may direct new therapeutic approaches for T2D.


Author(s):  
Eric C. Westman ◽  
Emily Maguire ◽  
William S. Yancy

Obesity and type 2 diabetes mellitus (T2DM) have reached epidemic proportions worldwide. While characterized by chronic hyperglycemia, the underlying cause of T2DM is insulin resistance—most often related to an increase in abdominal adiposity caused by obesity. The goal of treatment of T2DM is to put the disease into remission by targeting the underlying insulin resistance. The observation that dietary carbohydrate is the major factor to cause glycosuria and hyperglycemia, has been known since the early days of modern medicine. As a result, low-carbohydrate, ketogenic diets were employed to treat obesity and diabetes in the nineteenth and early twentieth centuries. This chapter reviews the rationale and recent clinical research supporting the use of a low-carbohydrate, ketogenic diet in individuals with obesity and diabetes. For individuals affected by obesity-related T2DM, clinical studies have shown that carbohydrate restriction and weight loss can improve hyperglycemia, obesity, and T2DM.


PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e101269 ◽  
Author(s):  
Fenping Zheng ◽  
Saifei Zhang ◽  
Weina Lu ◽  
Fang Wu ◽  
Xueyao Yin ◽  
...  

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