Role of Histone Modifications and 12/15-lipoxygenase Metabolic Pathway in the Development of Diabetic Kidney Disease / 中山大学学报(医学科学版)

Diabetic kidney disease （DKD） is one of the most common microvascular complications in patients with diabetes. DKD is also the main cause of end-stage renal failure， with very complex pathogenesis. A large number of experiments have confirmed that epigenetic mechanisms， including histone chemical modifications and lipid metabolites 12/15-lipoxygenase （12/15-LO）， are involved in regulating the characteristic pathophysiological process of DKD， based on which， this review further explores the pathogenesis of DKD and provides the new research direction for DKD treatment.

Research progress on epigenetic modification involved in metabolic memory of diabetic retinopathy / 国际眼科杂志(Guoji Yanke Zazhi)

Diabetes retinopathy(DR)may continue to develop even if blood sugar is well controlled, which indicates that previous hyperglycemia will lead to long-term harmful vascular dysfunction, and this phenomenon is defined as “metabolic memory” of diabetes retinopathy. Because the onset of DR is insidious, clinical symptomatic treatment is mainly used. Effective means of early diagnosis, accurate treatment and prognosis are lacking and new diagnosis and treatment ideas need to be developed urgently. In recent years, many new studies have shown that epigenetic modification is involved in the pathogenesis of DR “metabolic memory” in DNA methylation, histone post-translational modification and microRNA(microRNAs,miRNAs)regulation, which provides a direction and strategy for the exploration of DR molecular mechanism. In this review, we discussed the role of epigenetic modification in the pathogenesis of DR and analyzed the challenges and prospects of its application in the treatment of DR, with a view to provide a reference for early diagnosis and treatment of DR in the future.

Transcriptome analysis of the transformation of podocytes into mesenchymal cells in high glucose memory model / 解放军医学杂志

Objective: To investigate, with transcriptome sequencing, the mechanism of metabolic memory in epithelial-mensenchymal transition (EMT) of podocytes induced by high glucose. Methods: Mouse glomerular podocytes were cultured in four groups: normal glucose group (NG, 5 mmol/L D-glucose X48 h); high glucose group (HG, 30 mmol/L D-glucose X48 h); metabolic memory group (MG, 30 mmol/L D-glucose x48 h, +5.5 mmol/L D-glouse x48 h); osmotic pressure group (OSM, 5.5 mmol/L D-glucose + 24.5 mmol/L mannitol X48 h). The expressions of Nephrin and α-SMA in podocyte EMT were detected by Western blotting and immunofluorescence. Illumina Hiseq 2000 was applied to characterize the transcriptome profiles of NG, HG and MG groups, DESeq was used to identify the differentially expressed genes (DEGs), gene ontology (GO) enrichment analysis and kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis were implemented for DEGs. The expression levels of the selected DEGs were detected by real-time fluorescence quantitative PCR. Results: Compared with NG group, both Western blotting and immunofluorescence showed that the expression level of Nephrin decreased, while of ct-SMA increased (P0.05). RNA-Seq showed that 194 genes (119 up-regulation and 75 down-regulation) were differentially expressed between HG and NG groups, while 532 genes (316 up-regulation and 216 down-regulation) were differentially expressed between MG and NG groups. Further comparison of the above DEGs showed 108 genes (35 up-regulation and 73 down-regulation) had similar expression patterns in HG and MG groups. The GO enrichment analysis showed 10 GO terms were significantly enriched, and the KEGG pathway enrichment analysis showed TGF-β, focal adhesion plaque, Rap1 and pluripotent regulation of stem cells signal pathways were significantly enriched. PCR showed that the expression levels of Smad9, Snai1 and Mapkapk3 were higher, while of Igf1, Fgf22, Lama1 and Zfhx3 were lower in HG and MG group than in NG group. Conclusions: High glucose can induce podocyte EMT in vitro, and there is a "memory phenomenon" even after normal glucose culture. The occurrence of this phenomenon may be potentially related to TGF-β, focal adhesion plaque, Rap1 and pluripotent regulation of stem cells signal pathways, and upregulation of Smad9, Snai1 and Mapkapk3, as well as downregulation of Igf1, Fgf22, Lama1 and Zfhx3.

Discussion on Regulating AGEs to Improve Diabetic Macrovascular Disease Based on Fu-xie Theory / 中国实验方剂学杂志

The long-term existence of hyperglycemia leads to the occurrence of metabolic memory effect， which is an important reason for the formation of diabetic macrovascular disease， so the early control of metabolic memory is the key to the prevention and treatment of diabetes and its complications. The excessive formation of advanced glycation end products （AGEs） is not only an important factor to cause metabolic memory， but also the core mechanism for diabetic macrovascular disease. It is believed in traditional Chinese medicine（TCM） that Fu-xie （incubative pathogen） is the key pathogenesis of the formation of diabetic vascular diseases， and it is necessary to adopt the principle of removing pathogenic factors and opening collaterals as early as possible to prevent and cure the disease. During the Spring and Autumn Period and the Warring States Period， the theory of Fu-xie was germinated， and got mature in the Ming and Qing dynasties after the continuous development. The so-called Fu-xie means that the pathogens are of a potential nature but not cause diseases immediately. The theory of Fu-xie first appeared in Huangdi Neijing， with an original meaning of epidemic febrile disease occurring after incubation， and then its meaning continues to expand， now referring to all potential pathogenic factors that would not immediately cause diseases. As the cause and pathogenesis of many diseases， the theory of Fu-xie is widely used in clinical practice to guide the treatment of diseases. In the body， the accumulation of AEGs can induce the subsequent cascade effect in the body， and finally promote the formation and development of diabetic macrovascular diseases. This is very similar to the process of inducing metabolic disorder and disease in TCM due to the accumulation of phlegm and silt. Therefore， under the guidance of Fu-xie theory， the mechanism of AEGs in blocking metabolic memory and preventing and treating diabetic macrovascular disease was analyzed in this paper. On the one hand， it will provide a scientific basis for the exploration of Fu-xie theory affecting the disease course of diabetic macrovascular disease by regulating the generation of AEGs. On the other hand， it can also provide the material change basis for the development of Fu-xie theory in the occurrence and development of diabetic macroangiopathy.

Bile acids and their effects on diabetes / 医学前沿

Diabetes is a widespread, rapidly increasing metabolic disease that is driven by hyperglycemia. Early glycemic control is of primary importance to avoid vascular complications including development of retinal disorders leading to blindness, end-stage renal disease, and accelerated atherosclerosis with a higher risk of myocardial infarction, stroke and limb amputations. Even after hyperglycemia has been brought under control, "metabolic memory," a cluster of irreversible metabolic changes that allow diabetes to progress, may persist depending on the duration of hyperglycemia. Manipulation of bile acid (BA) receptors and the BA pool have been shown to be useful in establishing glycemic control in diabetes due to their ability to regulate energy metabolism by binding and activating nuclear transcription factors such as farnesoid X receptor (FXR) in liver and intestine as well as the G-protein coupled receptor, TGR5, in enteroendocrine cells and pancreatic β-cells. The downstream targets of BA activated FXR, FGF15/21, are also important for glucose/insulin homeostasis. In this review we will discuss the effect of BAs on glucose and lipid metabolism and explore recent research on establishing glycemic control in diabetes through the manipulation of BAs and their receptors in the liver, intestine and pancreas, alteration of the enterohepatic circulation, bariatric surgery and alignment of circadian rhythms.

The mechanism of exosome-mediated signaling on the metabolic memory of diabetes / 医学研究生学报

The metabolic memory formed by early hyperglycemia in diabetes is one of the important factors triggering the development of diabetes and relavant complications. At present, treatment of various adverse factors of metabolic memory shows a limited clinical efficacy. In recent years, exosome emerged as an important mediator of cellular communication and have gradually gained importance attendance in the field of diabetes treatments. This review summarizes the main mechanisms involved in the metabolic memory of exosomes in the pathological state, including inflammation, insulin resistance, oxidative stress and apoptosis. In addition, protection mechanisms of the stress pretreatment and stem cells derived exosomes on metabolic memory are discussed in this review. Finally, the possible ways to obtain therapeutic exosomes are elaborated, which is beneficial to generate new ideas for the clinical drug treatment.

The alterations of PGC-1α expression and epigenetic modifications in the retina of streptozotocin-induced diabetic rats / 中华实验眼科杂志

Objective To investigate the role of epigenetic regulations of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in the development of diabetic retinopathy and the metabolic memory phenomenon after hyperglycemia was terminated.Methods Diabetic rat model was established by intraperitoneal injection of streptozotocin (STZ).Sixty diabetic rats were randomly divided into 3 groups,poor glycemic control group rats were maintained in poor glycemic control for 4 months;semi glycemic control group rats were maintained in poor glycemic control for 2 months,followed by good glycemic control for 2 additional months;good glycemic control group rats were maintained in good glycemic control for 4 months.Twenty normal rats served as control group.The mRNA expression of PGC-1α and superoxide dismutase 2 (SOD2) of retina were measured by real-time PCR;the expression of PGC-1α and manganese superoxide dismutase (MnSOD) protein were measured by Western blot;the situation of DNA methylation in the promotor region of PPARGC1A was measured by bisulfite sequencing.Results The body-weight in the control group was significantly higher than that in the poor glycemic control group,semi glycemic control group and good glycemic control group (all at P =0.000).The blood glucose value in the poor glycemic control group was significantly higher than that in the control group (P =0.000).The expression levels of PGC-1 α mRNA were significantly lower and the expression levels of SOD2 mRNA were significantly higher in the good glycemic control group,semi glycemic control group and poor glycemic control group than those in the control group (all at P＜0.05).The expression levels of PGC-1α and SOD2 mRNA were significantly different between the good glycemic control group and poor glycemic control group (both at P＜0.05).Compared with the control group,the expression levels of PGC-1α and MnSOD protein were decreased in the diabetic model groups,with significant differences between them (all at P＜0.05).The expression level of PGC-1 α protein was significantly higher in the good glycemic control group than that in the poor glycemic control group (P＜0.05).Diabetes increased DNA methylation in the promotor region of PPARGC1A gene of retina.The DNA methylation level was significantly higher in the poor glycemic control group and semi glycemic control group than that in the control group (P =0.008,0.031).No statistical difference was found between the poor glycemic control group and semi glycemic control group (P ＞ 0.05).Conclusions The expressions of PGC-1o mRNA and protein and MnSOD protein in the retina of STZ induced diabetic rats are decreased,the expression of SOD2 mRNA is increased,the expression changes have metabolic memory characteristics.Increased DNA methylation in the promotor region of PPARGC1A when exposed to high glucose may have a role in the regulation of PGC-1 α expression and metabolic memory.

Metabolic memory and diabetic nephropathy / 复旦学报（医学版）

Metabolic memory is a phenomenon that the diabetic complications continue to develop and progress in individuals who exposed a period of high glucose in the early stage and then returned to normal blood glucose after effective control.Diabetic nephropathy (DN) is one of the common diabetic microangiopathy and the main cause of end stage renal disease (ESRD).This review mainly summarizes the relationships between metabolic memory and the development of DN.

A long-term follow-up study after the open-label proof-of-concept trial of metformin in systemic lupus erythematosus / 上海交通大学学报（医学版）

Objective: To evaluate the efficacy and safety of a long-term adding metformin to a basic treatment strategy in systemic lupus erythematosus (SLE), and analyze whether the beneficial effects of metformin add-on treatment during the open-label proof-of-concept trial persisted during a posttrial follow-up (the metabolic memory effect), as there is a paucity of systematically collected data concerning long-term metformin use in SLE. Methods: Subjects who had participated in the open-label proof-of-concept trial and gave informed consent to this study were enrolled, and the disease flares and long-term adverse effects between metformin group and control group were compared. In addition, whether the benefit regarding decreased disease flare persisted after metformin withdrawal during the post-trial follow-up was investigated. Results: Twenty-nine subjects in the former metformin add-on strategy group and 28 subjects in the former control group were enrolled. No adverse reactions of metformin occurred during the study. The risk of disease flare in the control group was higher than that in the continuous metformin group, but the difference was not statistically significant (P=0.326). After metformin withdrawal, the risk of disease flare in the metformin group gradually increased to the control group (P=0.998). There was no significant difference between the two continuous metformin use groups whose metformin using duration are 2.56 years and 5.00 years respectively (P=0.802). Conclusion: A long-term metformin add-on treatment is security, and can keep SLE patients in a lower risk of disease flare. The metabolic regulation of metformin in SLE immune disorder may present a time-dependent metabolic memory effect.

Transient high glucose induces persistent inflammatory status in rat glomerular mesangial cell via histone methylation modification / 中华肾脏病杂志

Objective To investigate whether the effect of transient high glucose on inflammatory factors expression could be continuous in rat glomerular mesangial cell,and its relation with histone methylation modification.Methods Rat glomerular mesangial cells (HBZY-l) were divided into three groups:the high glucose group (25.0 mmol/L glucose),the hypertonic group (MA,5.5 mmol/L glucose+ 19.5 mmol/L mannitol) and the normal-glucose control group (5.5 mmol/L glucose),which were cultured for 24 h respectively.All 3 groups were then changed with normal-glucose medium to culture for 24 h,48 h and 72 h.Their protein,mRNA and supernatant were harvested.The protein expressions of mono-methylation of H3 lysine 4 (H3K4mel) was measured by Western blotting,and the mRNA expressions of NF-κB subunit p65 and set7/9 were determined by real timequantitative PCR.The expression of monocyte chemoattractant protein 1 (MCP-1) and vascular cell adhesion molecule 1 (VCAM-1) were detected by enzyme-linked immunosorbent assay.Results (1)Compared with those in normal control group,the expressions of H3K4mel protein and set7/9 mRNA were first up-regulated in high glucose group,then gradually down-regulated in the following 48 h normal-glucose medium (as compared with those at 0 h,all P ＜ 0.05).At 72 h there was no statistic difference between high glucose group and normal control group (all P ＞ 0.05).(2) Compared with those in normal control group,the up-regulated p65 mRNA,VCAM-1 and MCP-1 sustained at least for 72 h in high glucose group.Conclusions Transient high glucose can induce persistent inflammatory factors expression in rat glomerular mesangial cells,which may via histone modification.

Advances of mechanisms of metabolic memory-based diabetic complications and therapeutic drugs / 中国药科大学学报

At present,metabolic memory is a major obstacle hindering the effective control of diabetes.Controlling blood sugar level solely by drugs can not prevent multiple diabetic complications.Understanding the molecular mechanisms of mediating diabetic complications,therefore,will eliminate the "metabolic memory" effect.In this artical,the molecular mechanism of metabolic memory mediating diabetic complications and prospective treatment drugs were reviewed,which provides basis to the further research on prevention and treatment of metabolic memory.

Effects of atorvastatin and valsartan on high glucose memory-induced injury to endothelial cell / 中华内分泌代谢杂志

Objective To explore the effects of atorvastatin and valsartan on high glucose-induced human umbilical vein endothelial cells (HUVECs) injury.Methods Cultured HUVECs were divided and assigned to 9 groups:normal control group,mannitol control group,high glucose group,low dose atorvastatin group (0.1 μ mol/L),medium dose atorvastatin group (1 μmol/L),high dose atorvastatin group (10 μ mol/L),low dose valsartan group (0.1 μmol/L),medium dose valsartan group (1 μmol/L),and high dose valsartan group (10 μmol/L).H UVECs were pretreated with or without 30 mmol/L glucose plus various concentrations of atorvastatin and valsartan (0.1,1,10 μmol/L) for 16 hours and then incubated with 5.5 mmol/L glucose for 6 days.The levels of vascular cell adhesion molecule 1 (VCAM-1),monocyte chemotactic protein 1 (MCP-1),and plasminogen activator inhibitor 1 (PAI-1) in the culture supernatant were measured by enzyme-linked immunosorbent assay.Results Compared with normal glucose group,hyperglycemia memory increased the levels of VCAM-1,MCP-1,and PAI-1 (all P＜0.05),which were still maintained at high levels even after withdrawal of high glucose.Atorvastatin and valsartan treatment decreased the levels of VCAM-1,MCP-1,and PAI-1 (all P＜0.05).Conclusion Atorvastatin and valsartan may lower the secretion of VCAM-1,MCP-1,and PAI-1,and prevent high glucose memory-induced injury to endothelial cell.

Effects of resveratrol on high glucose memory-induced injury to endothelial cell / 中华内分泌代谢杂志

Cultured human umbilical vein endothelial cells (HUVECs) were divided and assigned to 6 groups:normal control group,mannitol control group,high glucose group,low dose resveratrol group,medium dose resveratrol group,and high dose resveratrol group.HUVECs were pretreated with or without 30 mmol/L glucose plus various concentrations of resveratrol (0.1,1,10 μmol/L) for 16 hours and then incubated with 5.5 mmol/L glucose for 6 days.The levels of vascular cell adhesion molecule 1 (VCAM-1),monocyte chemotactic protein 1 (MCP-1),and plasminogen activator inhibitor 1 (PAI-1) in the culture supernatant were measured by ELISA.NF-κB expression was detected by Western blot.Compared with normal glucose group,high glucose up-regulated the expression of NF-κB,along with the increased levels of VCAM-1,MCP-1,and PAI-1 (all P＜0.05),which were still maintained at high levels even after withdrawal of high glucose.Resveratrol treatment down-regulated the expression of NF-κB and lowered the levels of VCAM-1,MCP-1,and PAI-1 (all P＜0.05).These results suggest that resveratrol may decrease the secretion of VCAM-1,MCP-1,and PAI-1 and prevent high glucose memory-induced injury to endothelial cell via NF-κB pathway.

Role of histone acetylation in diabetes mellitus / 中华内分泌代谢杂志

Histone acetylation is a crucial part of histone modifications in epigenetics.Histone acetylation is involved in the onset of diabetes and diabetic complications,through the mechanism of inducing hyperglycemia by means of metabolic memory effect,interfering islet development and regulating the expression of inflammatory factors and pathogenic genes.Genome-wide association studies are gradually unveilling the pathogenesis of diabetes and preclinical studies are rapidly elucidating that histone deacetylase should be considered as a new target for the treatment of diabetes.

Progress in epigenetics research in diabetic vascular diseases / 中华内分泌代谢杂志

The concept of epigenetics was first proposed by Waddington in 1942,referring to phenotypic changes that are not related to the underlying DNA sequence,yet alterations in the level and function of gene expression can be heritable,such as DNA methylation,histone modifications,microRNA interference,etc.Phenotype changes while genotype remains unchanged,this controlled mechanism can be kept stable throughout cell division,proliferation,and subsequent process of development.This process thus may cause corresponding changes in the pathophysiology,which are correlated with the occurrence of cancer,immune disorder,cardiovascular disease,metabolic syndrome and so on.Diabetes mellitus is the third heaviest chronic diseases in the world,and does serious harm to human health,especially the diabetic vascular diseases.Even if the blood glucose level is controlled in an ideal state,vascular inflammation still persists,indicating the existence of metabolic memory.Studies have suggested that the pathogenesis can be elucidated at the level of epigenetics.This paper mainly focuses on DNA methylation,histone modifications,and is an overview of epigenetics research progress in diabetic vascular diseases.

Convergence role of transcriptional coactivator p300 and apparent modification on hmcs metabolic memory induced by high glucose / 解放军医学杂志

Objective To investigate the protein expression of transcriptional coactivator p300, acetylated histone H3 (Ac-H3) and Ac-H4 in human renal mesangial cell (HMCs) as imitative "metabolic memory" in vitro, and explore the potential role of convergence point of p300. Methods The HMCs were divided into the following groups: {circled digit 1} High glucose metabolic memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d), high glucose group (HG, 2Smmol/L D-glucose × 2d), memory groups (Ml, M2, M3, 2Smmol/L D-glucose × 2days + S.Smmol/L D-glucose × 3d, 6d or 9d), persisting normal glucose group (NG, S.Smmol/L D-glucose × 9d). {circled digit 2} Advanced glycation end products memory model: normal glucose group (NG, S.Smmol/ L D-glucose × 2d), NG+AGEs group (AGEs, S.Smmol/L D-glucose+2S0μg/ml AGEs × 2d); AGEs memory group (AGEs-M, S.Smmol/L D-glucose + 2S0μg/ml AGEs × 2d + S.Smmol/L D-glucose × 3d); BSA control group (NG+BSA, S.Smmol/L D-glucose + 2S0μg/ml BSA × 2d). {circled digit 3} H202 was used to simulate oxidative stress memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d), NG+H202 group (H202, S.Smmol/L D-glucose +100μmol/L H202 × 30min); H202 memory group [(S.Smmol/ L D-glucose + 100μmol/L H202 × 30min) + S.Smmol/L D-glucose × 3d]; normal glucose control group (NG3, S.Smmol/L D-glucose X 3d). {circled digit 4} Transfection with PKCβ2 memory model: normal glucose group (NG, S.Smmol/L D-glucose × 2d); high glucose group (HG, 2Smmol/L D-glucose × 2d); memory group (M, 2Smmol/L D-glucose × 2d + S.Smmol/L D-glucose × 3d); AdS-null memory group (HN, 2Smmol/L D-glucose + AdS-null × 2d + S.Smmol/L D-glucose × 3d); PKCβ2 memory group (PO, 2Smmol/L D-glucose + AdS-PKCβ2 × 2d + S.Smmol/L D-glucose × 3d); inhibitor of PKCβ2 memory group (PI, 2Smmol/L D-glucose × 2d + 10μmol/L CGPS33S3 + S.Smmol/L D-glucose × 3d). The expression of intracellular reactive oxygen species (ROS) was detected by fluorescence microscope and fluorescence microplate reader. The expression levels of p300, Ac-H3, Ac-H4 and PKCβ2 proteins were determined by Western blotting. Results The expression levels of p300, Ac-H3 and Ac-H4 protein in HG group increased, being 2.15, 1.93 and 1.87 fold of those in group NG (P<0.05), accompanying with the up-regulation of PKCβ2 protein and ROS levels in HG group. The p300, Ac-H3, Ac-H4, PKCβ2 protein expression and ROS levels in Ml, M2, M3 group were higher than those in NG group, and was 1.75, 1.49, 1.47, 1.98 and 1.48 fold higher in M3 group than in NG group. The protein expressions of p300, Ac-H3 and Ac-H4 in AGEs group were increased by 1.73, 1.08 and 1.05 folds, and in AGE-M group increased by 1.47, 0.95 and 1.03 folds of that in control group (P<0.05). The protein expression levels of p300, Ac-H3 and Ac-H4 in H202 group increased by 1.03, 0.85 and 0.79 folds of those in control group (P<0.05). However, no significantly difference in these indices was found between H202-M and control groups. The protein expression levels of p300, Ac-H3 and Ac-H4 in PO group increased more obviously by 1.25, 1.06 and 1.10 folds of those in M group (P<0.05). However, the elective PKCβ2 inhibitor CGP533S3 could lower those indices significantly. Conclusion Persistent activation of transcriptional coactivator p300 and apparent modification may be normalized in HMCs. p300 may be the convergent point of glucose-induced metabolic "memory" stimulations.

The role of epigenetic modification in diabetic metabolic memory / 中华内分泌代谢杂志

It is evident that metabolic memory,whereby diabetic complications continue to develop and progress in individuals who returned to normal glycemic control after a period of transient hyperglycemia,has long lasting effects.Recent studies suggest that “metabolic memory” may be due to epigenetic changes in target oells.Understanding the molecular changes in chromatin structure and the functional relationship with altered signaling pathways is now considered to represent an important conceptual challenge to explain diabetes and the phenomenon of metabolic memory.Emerging evidences indicate that critical gene-activating epigenetic changes may confer future cell memories. Many experimental evidences show that histone acetyltransferases (HATs), histone deacetylases (HDACs),histone methyltransferases (HMTs),histone lysine demethylases (KDMs),and microRNAs play important roles in the epigenetic changes of several key genes related to diabetic complications. Transient hyperglycemia promotes gene-activating epigenetic changes and signaling events critical in the development and progression of diabetic vascular complications.Further characterisation of these glucose-induced epigenetic events and the identification of key enzymes involved will help us to develop new therapeutic strategies for diabetes and its complications.

Local aldosterone system mediated "hyperglycaemic memory" in human mesangial cells / 第二军医大学学报

Objective: To investigate the effect of hyperglycaemic memory on the local aldosterone system, reactive oxygen species (ROS) and expression of oncofetal fibronectin (oncofetal FN) mRNA in human mesangial cells (HMCs),and to further understand the role of local aldosterone system in the process. Methods: In this study HMCs were divided into the following groups:normal glucose group (NG, 5 mmol/L D-glucose for 2 days),high glucose group (HG, 25 mmol/L D-glucose for 2 days), memory group (M, 25 mmol/L D-glucose for 2 days→5 mmol/L D-glucose for 4 days), memory + eplerenone group (MY,25 mmol/L D-glucose for 2 days→5 mmol/L D-glucose+10 μ mol/L eplerenone for 4 days), normal glucose + eplerenone group (NY, 5 mmol/L D-glucose for 2 days→5 mmol/L D-glucose+10 μmol/L eplerenone for 4 days), and persistent normal glucose group (SN, 5 mmol/L D-glucose for 6 days). ROS levels were tested by fluorescence microscope and fluorescence microplate reader. Aldosterone synthase (CYP11B2) protein expression was detected by Western blotting analysis. The mRNA expressions of llβ-hydroxysteroid dehydrogenase type 2, CYP11B2 and oncofetal FN were detected by RT-PCR. The expression and translocation of mineralocorticoid receptor (MR) was observed by laser scanning confocal microscope (LSCM). Aldosterone level in cell culture supernatant was detected by radioimmu noassay. Results: (DCYP11B2 mRNA and protein expression in group HG and in group M were all significantly increased, being 3. 45, 2. 09 and 3. 14, 2. 06 folds of those in group NG, respectively (all P<0. 05). The aldosterone levels in HMCs culture supernatant were significantly increased in group HG and group M, being 2. 01 and 1. 81 folds of that in group NG, respectively (P<0. 05). MR was activated and translocated from the cytosol to the nucleus in group HG and group M. Quantitative analysis showed that the ratios of cytosol/ nucleus fluorescence intensity in group HG and group M were decreased by 30% and 21% compared with that in group NG, respectively (all P<0. 05). (2)Oncofetal FN mRNA expression and ROS levels in group HG and group M were significantly increased,being2.23, 1. 99 and 2. 16, 1. 90 folds those of group NG, respectively (all P<0. 05). Oncofetal FN mRNA expression and ROS levels in group MY were significantly decreased,being 35% and 51% of those in group M (all P<0. 05). Conclusion: HMCs have hyperglycaemic memory effect, which might be mediated by the local aldosterone system.

Effects of metabolic memory mediated by high glucose on functional injury of human umbilical vein endothelial cells / 中华内分泌代谢杂志

Cultured primary human umbilical vein endothelial cells (HUVECs) were divided into 4 groups:normal control( NG ),persistent high glucose ( HG ),hyperglycemia group ( TG ),and mannitol control ( MA )groups.After 1,4,and 7 days of culture,cells were collected.Cell proliferation,cell apoptosis,ROS,SOD,MDA,and NO level,eNOS mRNA and protein level were measured.Endothelial cell proliferation was inhibited in HG,TG,and MA groups compared with NG group.Hyperglycemia memory induced apoptosis of endothelial cells,increased ROS and MDA generation,and down-regulated intracellular SOD level,findings similar to those in HG group.After 24 h of culturing,eNOS expression and NO generation in both HG and TG groups were higher than those in NG group.However,after 7 days of culturing,eNOS expression and NO generation in both HG and TG groups were lower than those in NG group.These results suggest that in hyperglycemia memory cell model,transient hyperglysemia may lead to persistent imbalance in oxidative stress and reduce endothelium-derived relaxing factor NO level,indicating that hyperglycemia memory may play an important role in persistent vascular endothelial cell injury.

Epigenetic modifications and diabetic nephropathy

Diabetic nephropathy (DN) is a major complication associated with both type 1 and type 2 diabetes, and a leading cause of end-stage renal disease. Conventional therapeutic strategies are not fully efficacious in the treatment of DN, suggesting an incomplete understanding of the gene regulation mechanisms involved in its pathogenesis. Furthermore, evidence from clinical trials has demonstrated a "metabolic memory" of prior exposure to hyperglycemia that continues to persist despite subsequent glycemic control. This remains a major challenge in the treatment of DN and other vascular complications. Epigenetic mechanisms such as DNA methylation, nucleosomal histone modifications, and noncoding RNAs control gene expression through regulation of chromatin structure and function and post-transcriptional mechanisms without altering the underlying DNA sequence. Emerging evidence indicates that multiple factors involved in the etiology of diabetes can alter epigenetic mechanisms and regulate the susceptibility to diabetes complications. Recent studies have demonstrated the involvement of histone lysine methylation in the regulation of key fibrotic and inflammatory genes related to diabetes complications including DN. Interestingly, histone lysine methylation persisted in vascular cells even after withdrawal from the diabetic milieu, demonstrating a potential role of epigenetic modifications in metabolic memory. Rapid advances in high-throughput technologies in the fields of genomics and epigenomics can lead to the identification of genome-wide alterations in key epigenetic modifications in vascular and renal cells in diabetes. Altogether, these findings can lead to the identification of potential predictive biomarkers and development of novel epigenetic therapies for diabetes and its associated complications.