High Glucose Stress Research Articles

Effect of calcium levels on structure and function of mitochondria in yeast under high glucose fermentation.

In this study, the effects of calcium levels on structure and function of mitochondria under high glucose environment were studied. In the high glucose environment, yeast growth capacity was inhibited, and intracellular reactive oxygen species (ROS) content was increased from 6 h to 12 h, while ROS content was reduced in group with 1 × 10-1 and 1 g/L CaCl2 level from 24 h to 36 h. Exogenous calcium addition had a significant effect on the elevation of intracellular Ca2+ and cytochrome C content in yeast from 6 h to 12 h; mitochondrial membrane potential decreased with the increase of CaCl2 level under high glucose levels. Mitochondrial swelling of yeast was influenced by high glucose levels and showed a regulatory dynamic change by Ca2+ levels. Isocitrate dehydrogenase activity increased in 1 × 10-3 g/L CaCl2 level from 6 h to 12 h, α-ketoglutarate dehydrogenase activity increased with an increase in CaCl2 level from 6 h to 24 h. Calcium affected the structure and function of mitochondria by regulating the intracellular signal, enzymes in tricarboxylic acid cycle, and cytochrome system of yeast under high glucose stress.

SIRT1 Inhibits High Glucose-Induced TXNIP/NLRP3 Inflammasome Activation and Cataract Formation.

To determine whether SIRT1 regulates high glucose (HG)-induced inflammation and cataract formation through modulating TXNIP/NLRP3 inflammasome activation in human lens epithelial cells (HLECs) and rat lenses. HG stress from 25 to 150 mM was imposed on HLECs, with treatments using small interfering RNAs (siRNAs) targeting NLRP3, TXNIP, and SIRT1, as well as a lentiviral vector (LV) for SIRT1. Rat lenses were cultivated with HG media, with or without the addition of NLRP3 inhibitor MCC950 or SIRT1 agonist SRT1720. High mannitol groups were applied as the osmotic controls. Real-time PCR, Western blots, and immunofluorescent staining evaluated the mRNA and protein levels of SIRT1, TXNIP, NLRP3, ASC, and IL-1β. Reactive oxygen species (ROS) generation, cell viability, and death were also assessed. HG stress induced a decline in SIRT1 expression and caused TXNIP/NLRP3 inflammasome activation in a concentration-dependent manner in HLECs, which was not observed in the high mannitol-treated groups. Knocking down NLRP3 or TXNIP inhibited NLRP3 inflammasome-induced IL-1β p17 secretion under HG stress. Transfections of si-SIRT1 and LV-SIRT1 exerted inverse effects on NLRP3 inflammasome activation, suggesting that SIRT1 acts as an upstream regulator of TXNIP/NLRP3 activity. HG stress induced lens opacity and cataract formation in cultivated rat lenses, which was prevented by MCC950 or SRT1720 treatment, with concomitant reductions in ROS production and TXNIP/NLRP3/IL-1β expression levels. The TXNIP/NLRP3 inflammasome pathway promotes HG-induced inflammation and HLEC pyroptosis, which is negatively regulated by SIRT1. This suggests viable strategies for treating diabetic cataract.

Prediction of ethanol fermentation under stressed conditions using yeast morphological data

A high sugar concentration is used as a starting condition in alcoholic fermentation by budding yeast, which shows changes in intracellular state and cell morphology under conditions of high-sugar stress. In this study, we developed artificial intelligence (AI) models to predict ethanol yields in yeast fermentation cultures under conditions of high-sugar stress using cell morphological data. Our method involves the extraction of high-dimensional morphological data from phase contrast images using image processing software, and predicting ethanol yields by supervised machine learning. The neural network algorithm produced the best performance, with a coefficient of determination (R2) of 0.95, and could predict ethanol yields well even 60min in the future. Morphological data from cells cultured in low-glucose medium could not be used for accurate prediction under conditions of high-glucose stress. Cells cultured in high-concentration glucose medium were similar in terms of morphology to cells cultured under high osmotic pressure. Feeding experiments revealed that morphological changes differed depending on the fermentation phase. By monitoring the morphology of yeast under stress, it was possible to understand the intracellular physiological conditions, suggesting that analysis of cell morphology can aid the management and stable production of desired biocommodities.

Long noncoding RNA TPTEP1 suppresses diabetic retinopathy byreducing oxidative stress and targetingthe miR-489-3p/NRF2 axis.

Diabetic retinopathy (DR) is a diabetic complication with complex etiology and severe visual impairment. Dysregulated long noncoding RNAs (lncRNAs) are closely associated with DR. This article focused on the impact of lncRNA transmembrane phosphatase with tensin homology pseudogene 1 (TPTEP1) in DR. First, sera were collected from DR patients and healthy control. Human retinal vascular endothelial cells (HRVECs) were exposed to high glucose (HG) to construct a DR model in vitro. A real-time quantitative polymerase chain reaction (RT-qPCR) was carried out to detect TPTEP1. Targeting relationships were predicted using StarBase and TargetScan, and confirmed by the Dual-Luciferase Reporter Assay. Cell Counting Kit 8 (CCK-8) and EdU staining were applied to measure cell viability and proliferation, respectively. Protein expression was determined by a western blotting assay. lncRNA TPTEP1 expression was significantly decreased in the serum of DR patients and HG-stimulated HRVECs. Overexpression of TPTEP1 reduced cell viability and proliferation induced by HG and oxidative stress. In addition, overexpression of miR-489-3p impaired the effects of TPTEP1. Nrf2, which was targeted by miR-489-3p, was down-regulated in HG-treatment HRVECs. Knockdown of Nrf2 enhanced the influence of miR-489-3p and antagonized the effects of TPTEP1. This study demonstrated that a TPTEP1/miR-489-3p/NRF2 axis affects the development of DR by regulating oxidative stress.

Apollo-IRE1: A genetically encoded sensor for live cell and multiplexed imaging of ER stress.

Several metabolic diseases, such as Alzheimer's, diabetes, and arthritis, are caused in part by the cellular accumulation of improperly folded proteins in the Endoplasmic Reticulum (ER). In response to protein misfolding, a transmembrane stress-sensor called IRE1α activates the Unfolded Protein Response (UPR) to maintain protein folding homeostasis. To measure ER stress response in living beta-cells with spatial and temporal resolution, we developed a genetically encoded sensor based on fluorescent protein-tagged IRE1α. This sensor homo-oligomerizes to dimeric and tetrameric conformations under early and chronic ER stress, respectively, resulting in homoFRET and an associated decrease in steady-state fluorescence anisotropy (i.e., decreased IRE1 anisotropy/polarisation of fluorescence due oligomerization (Apollo-IRE1)). Apollo-IRE1 responds to chemical and physiological (high glucose) stress in a rat beta-cell line (INS-1E) and mouse islets. Preliminary data suggest that UPR-associated XBP1 mRNA splicing is highly correlated with sensor response. Furthermore, individual cells with the highest sensor response (correlating to late-stage UPR) show elevated levels of pro-apoptotic protein TXNIP. The single colour design of Apollo sensors also makes them ideal for multiplexing, offering an exciting opportunity to explore multiparametric analysis of cellular metabolic characteristics. To demonstrate the multiplexing capability of Apollo-IRE1, we will explore simultaneously imaging of a sensor for NADPH (Apollo-NADP+) and by immunofluorescence with other ER stress markers. These data validate and demonstrate the utility of Apollo-IRE1 in sensing early and chronic ER stress through live cell imaging and multiplexed analysis.

Citrus flavanone metabolites significantly modulate global proteomic profile in pancreatic β-cells under high-glucose-induced metabolic stress

Hesperidin and narirutin are the major citrus flavanones. Several studies have associated these compounds with pancreatic β-cell survival through their capacity to reduce oxidative stress, inflammation, and inhibit apoptosis. However, the molecular mechanisms of action of flavanones in pancreatic β-cells under high-glycemic stress is still largely unknown. Therefore, this study aimed to decipher molecular mechanisms of flavanone metabolites in pancreatic β-cells treated with high glucose concentration using untargeted shotgun proteomics. We identified 569 proteins differentially expressed in cells exposed to hesperetin 7-glucuronide (H7G) and 265 in cells exposed to 3-(4′-hydroxyphenyl) propanoic acid (PA). Comparison of global proteomic profiles suggest that these metabolites could counteract changes in protein expression induced by high glucose stress. The bioinformatic analyses suggested that H7G and PA modulated the expression of proteins involved in cell adhesion, cell signaling, metabolism, inflammation, and protein processing in endoplasmic reticulum (ER) pathways. Taken together, this study suggests that H7G and PA can modulate the expression of proteins that may prevent dysfunction of pancreatic β-cells under stress induced by high glucose.

Vitamin B3 inhibits apoptosis and promotes autophagy of islet β cells under high glucose stress

Background: Hyperglycemia is a typical symptom of diabetes. High glucose induces apoptosis of islet β cells. While autophagy functions in cytoprotection and autophagic cell death. The interaction between autophagy and apoptosis is important in the modulation of the function of islet β cells. Vitamin B3 can induce autophagy and inhibit islet β apoptosis.Method: The mechanism of vitamin B3-mediated protective effect on the function of islet β cells was explored by the method of western blot, immunofluorescence and flow cytometry.Results: In the present study, high glucose stress increased the apoptosis rate, while vitamin B3 reduced the apoptosis rate. The effect of vitamin B3 on autophagy flux under normal and high glucose stress was also investigated. Vitamin B3 increased the number of autophagosomes and increased the light chain (LC)3-II/LC3-I ratio. In contrast, vitamin B3 decreased sequestosome 1 (SQSTM1)/p62 protein expression and inhibited the phosphorylation of mammalian ribosomal protein S6 kinase β-1 (p70S6K/S6K1), which was a substrate of mammalian target of rapamycin (mTOR) under normal and high glucose stress. To further verify the protective effect of vitamin B3 on apoptosis, we treated islet β cell RIN-m5F with autophagy inhibitor 3-methyladenine (3-MA). Vitamin B3 decreased the apoptosis rate under high glucose stress, while the inhibition of apoptosis by vitamin B3 was blocked after adding 3-MA.Conclusion: Our data suggested that vitamin B3 reduced the apoptosis rate of β cells, possibly through inducing autophagy under high glucose stress.

Circ_0008529 Contributes to Renal Tubular Cell Dysfunction in High Glucose Stress via miR-185-5p/SMAD2 Pathway in Diabetic Nephropathy.

Circular RNA (circRNA) is key regulator of diabetic nephropathy (DN) progression. However, the role of circ_0008529 in DN progression remains to be better deciphered. Cell viability, cell cycle, apoptosis and inflammation were measured by MTS assay, flow cytometry and corresponding assay kits. RT-qPCR was used to assess the expression of circ_0008529, miR-185-5p and SMAD family member 2 (SMAD2). Also, western blotting was performed to measure protein expression. Target relationship was validated by RNA pull-down assay, dual-luciferase reporter assay and RNA immunoprecipitation assay. Urinary exosome was isolated using ultracentrifugation method and identified by transmission electron microscopy. Receiver operating characteristic curve was used to analyze the diagnostic value of circ_0008529 in DN patients. Circ_0008529 and SMAD2 were upregulated, while miR-185-5p was downregulated in high glucose (HG)-induced renal tubular HK-2 cells. Under HG treatment, cell viability and cell cycle process were suppressed, while apoptosis, inflammation and extracellular matrix accumulation were enhanced. However, interfering circ_0008529 could attenuate HG-induced effects, and this protection was abated by miR-185 inhibition or SMAD2 re-expression. Mechanically, circ_0008529 and SMAD2 were competing endogenous RNAs for miR-185-5p via target binding, and circ_0008529 regulated SMAD2 expression via miR-185-5p. Notably, circ_0008529 expression was upregulated in urinary exosomes of DN patients, and showed diagnostic value (Sensitivity: 70.21%; Specificity: 86.67%). Circ_0008529 might be a potential target for DN, which regulated DN progression via miR-185-5p/SMAD2 pathway.

Vitamin B6 Inhibits High Glucose-Induced Islet β Cell Apoptosis by Upregulating Autophagy.

Vitamin B6 may alleviate diabetes by regulating insulin secretion and increasing insulin sensitivity, but its mechanism remains to be explored. In this study, vitamin B6-mediated autophagy and high glucose-induced apoptosis were tested to investigate the mechanism by which vitamin B6 regulates insulin release. The results showed that 20 mM glucose increased the apoptosis rate from 10.39% to 22.44%. Vitamin B6 reduced the apoptosis rate of RIN-m5F cells from 22.44% to 11.31%. Our data also showed that the vitamin B6 content in processed eggs was decreased and that the hydrothermal process did not affect the bioactivity of vitamin B6. Vitamin B6 increased the number of autophagosomes and the ratio of autophagosome marker protein microtubule associated protein 1 light chain 3 beta to microtubule associated protein 1 light chain 3 alpha (LC3-II/LC3-I). It also decreased the amount of sequetosome 1 (SQSTM1/p62) and inhibited the phosphorylation of p70 ribosomal protein S6 kinase (p70S6K) under normal and high glucose stress. Another study showed that vitamin B6 inhibited the apoptosis rate, whereas the autophagy inhibitor 3-methyladenine (3-MA) blocked the protective effect of vitamin B6 against apoptosis induced by high glucose. The hydrothermal process decreased the vitamin B6 content in eggs but had no effect on the cytoprotective function of vitamin B6 in RIN-m5f cells. In conclusion, we demonstrated that vitamin B6-mediated autophagy protected RIN-m5f cells from high glucose-induced apoptosis might via the mTOR-dependent pathway. Our data also suggest that low temperatures and short-term hydrothermal processes are beneficial for dietary eggs.

Long-Term IGF1 Stimulation Leads to Cellular Senescence via Functional Interaction with the Thioredoxin-Interacting Protein, TXNIP.

The growth hormone (GH)–insulin-like growth factor-1 (IGF1) signaling pathway plays a major role in orchestrating cellular interactions, metabolism, growth and aging. Studies from worms to mice showed that downregulated activity of the GH/IGF1 pathway could be beneficial for the extension of lifespan. Laron syndrome (LS) is an inherited autosomal recessive disorder caused by molecular defects of the GH receptor (GHR) gene, leading to congenital IGF1 deficiency. Life-long exposure to minute endogenous IGF1 levels in LS is associated with low stature as well as other endocrine and metabolic deficits. Epidemiological surveys reported that patients with LS have a reduced risk of developing cancer. Studies conducted on LS-derived lymphoblastoid cells led to the identification of a novel link between IGF1 and thioredoxin-interacting protein (TXNIP), a multifunctional mitochondrial protein. TXNIP is highly expressed in LS patients and plays a critical role in cellular redox regulation by thioredoxin. Given that IGF1 affects the levels of TXNIP under various stress conditions, including high glucose and oxidative stress, we hypothesized that the IGF1–TXNIP axis plays an essential role in helping maintain a physiological balance in cellular homeostasis. In this study, we show that TXNIP is vital for the cell fate choice when cells are challenged by various stress signals. Furthermore, prolonged IGF1 treatment leads to the establishment of a premature senescence phenotype characterized by a unique senescence network signature. Combined IGF1/TXNIP-induced premature senescence can be associated with a typical secretory inflammatory phenotype that is mediated by STAT3/IL-1A signaling. Finally, these mechanistic insights might help with the understanding of basic aspects of IGF1-related pathologies in the clinical setting.

Jatrorrhizine Improves Endothelial Function in Diabetes and Obesity through Suppression of Endoplasmic Reticulum Stress.

Jatrorrhizine (JAT) is one of the major bioactive protoberberine alkaloids found in rhizoma coptidis, which has hypoglycemic and hypolipidemic potential. This study aimed to evaluate the vasoprotective effects of JAT in diabetes and obesity and the underlying mechanism involved. Mouse aortas, carotid arteries and human umbilical cord vein endothelial cells (HUVECs) were treated with risk factors (high glucose or tunicamycin) with and without JAT ex vivo and in vitro. Furthermore, aortas were obtained from mice with chronic treatment: (1) control; (2) diet-induced obese (DIO) mice fed a high-fat diet (45% kcal% fat) for 15 weeks; and (3) DIO mice orally administered JAT at 50 mg/kg/day for the last 5 weeks. High glucose or endoplasmic reticulum (ER) stress inducer tunicamycin impaired acetylcholine-induced endothelium-dependent relaxations (EDRs) in mouse aortas, induced oxidative stress in carotid arteries and HUVECs, downregulated phosphorylations of Akt at Ser473 and eNOS at Ser1177 and enhanced ER stress in mouse aortas and HUVECs, and these impairments were reversed by cotreatment with JAT. JAT increased NO release in high-glucose-treated mouse aortas and HUVECs. In addition, chronic JAT treatment restored endothelial function with EDRs comparable to the control, increased Akt/eNOS phosphorylation, and attenuated ER stress and oxidative stress in aortas from DIO mice. Blood pressure, glucose sensitivity, fatty liver and its morphological change, as well as plasma levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and plasma lipid profile, were also normalized by JAT treatment. Collectively, our data may be the first to reveal the vasoprotective effect of JAT that ameliorates endothelial dysfunction in diabetes and obesity through enhancement of the Akt/eNOS pathway and NO bioavailability, as well as suppression of ER stress and oxidative stress.

Long non-coding RNAs in retinal neovascularization: current research and future directions.

Retinal neovascularization (RNV) is an intractable pathological hallmark of numerous ocular blinding diseases, including diabetic retinopathy, retinal vein occlusion, and retinopathy of prematurity. However, current therapeutic methods have potential side effects and limited efficacy. Thus, further studies on the pathogenesis of RNV-related disorders and novel therapeutic targets are critically required. Long non-coding RNAs (lncRNAs) have various functions and participate in almost all biological processes in living cells, such as translation, transcription, signal transduction, and cell cycle control. In addition, recent research has demonstrated critical modulatory roles of various lncRNAs in RNV. In this review, we summarize current knowledge about the expression and regulatory functions of lncRNAs related to the progression of pathological RNV. We searched databases such as PubMed and Webof Scienceto gather and review information from the publishedliterature. In general, lncRNA MEG3 attenuatesRNV, thus protecting the retina from excessive and dysregulated angiogenesis under high glucosestress. In contrast, lncRNAs MALAT1, MIAT, ANRIL, HOTAIR, HOTTIP, and SNHG16, have been identified as causative molecules in the pathological progression of RNV. Comprehensive and in-depth studies of the roles of lncRNAs in RNV indicate that targeting lncRNAs may be an alternative therapeutic approach in the near future, enabling new options for attenuating RNV progression and treating RNV-related retinal diseases.

TRNA-derived fragment tRF-1020 ameliorates diabetes-induced retinal microvascular complications.

Transfer RNA (tRNA)‐derived fragments are the non‐coding single‐stranded RNAs involved in several physiological and pathological processes. Herein, we investigated the role of tRF‐1020, a tRNA fragment, in diabetes‐induced retinal microvascular complications. The results showed that the levels of tRF‐1020 expression were down‐regulated in diabetic retinal vessels and retinal endothelial cells following high glucose or H2O2 stress. Overexpressing tRF‐1020 led to decreased endothelial cell viability, proliferation, migration, and tube formation and alleviated retinal vascular dysfunction as shown by decreased retinal acellular capillaries, vascular leakage, and inflammation. By contrast, tRF‐1020 silencing displayed the opposite effects. tRF‐1020 regulated endothelial angiogenic functions and retinal vascular dysfunction by targeting Wnt signalling. Moreover, the levels of tRF‐1020 expression were reduced in aqueous humour and vitreous samples of the patients with diabetic retinopathy. Collectively, tRF‐1020 is a potential target for the diagnosis and treatment of diabetic retinopathy.

High Glucose and Carbonyl Stress Impair HIF-1-Regulated Responses and the Control of Mycobacterium tuberculosis in Macrophages.

ABSTRACTDiabetes mellitus (DM) increases the risk of developing tuberculosis (TB), but the mechanisms behind diabetes-TB comorbidity are still undefined. Here, we studied the role of hypoxia-inducible factor-1 (HIF-1), a main regulator of metabolic and inflammatory responses, in the outcome of Mycobacterium tuberculosis infection of bone marrow-derived macrophages (BMM). We observed that M. tuberculosis infection of BMM increased the expression of HIF-1α and HIF-1-regulated genes. Treatment with the hypoxia mimetic deferoxamine (DFO) further increased levels of HIF-1-regulated immune and metabolic molecules and diminished the intracellular bacterial load in BMM and in the lungs of infected mice. The expression of HIF-1-regulated immunometabolic genes was reduced, and the intracellular M. tuberculosis levels were increased in BMM incubated with high-glucose levels or with methylglyoxal (MGO), a reactive carbonyl compound elevated in DM. In line with the in vitro findings, high M. tuberculosis levels and low HIF-1-regulated transcript levels were found in the lungs from hyperglycemic Leprdb/db compared with wild-type mice. The increased intracellular M. tuberculosis growth and the reduced expression of HIF-1-regulated metabolic and inflammatory genes in BMM incubated with MGO or high glucose were reverted by additional treatment with DFO. Hif1a-deficient BMM showed ablated responses of immunometabolic transcripts after mycobacterial infection at normal or high-glucose levels. We propose that HIF-1 may be targeted for the control of M. tuberculosis during DM.

The SLIM1 transcription factor affects sugar signaling during sulfur deficiency in Arabidopsis.

The homeostasis of major macronutrient metabolism needs to be tightly regulated, especially when the availability of one or more nutrients fluctuates in the environment. Both sulfur metabolism and glucose signaling are important processes throughout plant growth and development, as well as during stress responses. Still, very little is known about how these processes affect each other, although they are positively connected. Here, we showed in Arabidopsis that the crucial transcription factor of sulfur metabolism, SLIM1, is involved in glucose signaling during shortage of sulfur. The germination rate of the slim1_KO mutant was severely affected by high glucose and osmotic stress. The expression of SLIM1-dependent genes in sulfur deficiency appeared to be additionally induced by a high concentration of either mannitol or glucose, but also by sucrose, which is not only the source of glucose but another signaling molecule. Additionally, SLIM1 affects PAP1 expression during sulfur deficiency by directly binding to its promoter. The lack of PAP1 induction in such conditions leads to much lower anthocyanin production. Taken together, our results indicate that SLIM1 is involved in the glucose response by modulating sulfur metabolism and directly controlling PAP1 expression in Arabidopsis during sulfur deficiency stress.

Neutrophil Extracellular Traps Promote NLRP3 Inflammasome Activation and Glomerular Endothelial Dysfunction in Diabetic Kidney Disease.

Diabetes mellitus is a metabolic disease largely due to lifestyle and nutritional imbalance, resulting in insulin resistance, hyperglycemia and vascular complications. Diabetic kidney disease (DKD) is a major cause of end-stage renal failure contributing to morbidity and mortality worldwide. Therapeutic options to prevent or reverse DKD progression are limited. Endothelial and glomerular filtration barrier (GFB) dysfunction and sterile inflammation are associated with DKD. Neutrophil extracellular traps (NETs), originally identified as an innate immune mechanism to combat infection, have been implicated in sterile inflammatory responses in non-communicable diseases. However, the contribution of NETs in DKD remains unknown. Here, we show that biomarkers of NETs are increased in diabetic mice and diabetic patients and that these changes correlate with DKD severity. Mechanistically, NETs promote NLRP3 inflammasome activation and glomerular endothelial dysfunction under high glucose stress in vitro and in vivo. Inhibition of NETs (PAD4 inhibitor) ameliorate endothelial dysfunction and renal injury in DKD. Taken together, NET-induced sterile inflammation promotes diabetes-associated endothelial dysfunction, identifying a new pathomechanism contributing to DKD. Inhibition of NETs may be a promising therapeutic strategy in DKD.

RAGE management: ETS1- EGR1 mediated transcriptional networks regulate angiogenic factors in wood frogs

Freeze-tolerant species, such as wood frogs (Rana sylvatica), are susceptible to multiple co-occurring stresses that they must overcome to survive. Freezing is accompanied by mechanical stress and dehydration due to ice crystal formation in the extracellular space, ischemia/anoxia due to interruption in blood flood, and hyperglycemia due to cryoprotective measures. Wood frogs can survive dehydration, anoxia, and high glucose stress independently of freezing, thereby creating a multifactorial model for studying freeze-tolerance. Oxidative stress and high glucose levels favors the production of pro-oxidant molecules and advanced glycation end product (AGE) adducts that could cause substantial cellular damage. In this study, the involvement of the high mobility group box 1 (HMGB1)-AGE/RAGE (receptor for AGE) axis and the regulation of ETS1 and EGR1-mediated angiogenic responses were investigated in liver of wood frogs expose to freeze/thaw, anoxia/reoxygenation and dehydration/rehydration treatments. HMGB1 and not AGE-adducts are likely to induce the activation of ETS1 and EGR1 via the RAGE pathway. The increase in nuclear localization of both ETS1 and EGR1, but not DNA binding activity in response to stress hints to a potential spatial and temporal regulation in inducing angiogenic factors. Freeze/thaw and dehydration/rehydration treatments increase the levels of both pro- and anti-angiogenic factors, perhaps to prepare for the distribution of cryoprotectants or enable the repair of damaged capillaries and wounds when needed. Overall, wood frogs appear to anticipate the need for angiogenesis in response to freezing and dehydration but not anoxic treatments, probably due to mechanical stress associated with the two former conditions.

Progranulin Preserves Autophagy Flux and Mitochondrial Function in Rat Cortical Neurons Under High Glucose Stress.

Chronic hyperglycemia in type II diabetes results in impaired autophagy function, accumulation of protein aggregates, and neurodegeneration. However, little is known about how to preserve autophagy function under hyperglycemic conditions. In this study, we tested whether progranulin (PGRN), a neurotrophic factor required for proper lysosome function, can restore autophagy function in neurons under high-glucose stress. We cultured primary cortical neurons derived from E18 Sprague-Dawley rat pups to maturity at 10 days in vitro (DIV) before incubation in high glucose medium and PGRN for 24-72 h before testing for autophagy flux, protein turnover, and mitochondrial function. We found that although PGRN by itself did not upregulate autophagy, it attenuated impairments in autophagy seen under high-glucose conditions. Additionally, buildup of the autophagosome marker light chain 3B (LC3B) and lysosome marker lysosome-associated membrane protein 2A (LAMP2A) changed in both neurons and astrocytes, indicating a possible role for glia in autophagy flux. Protein turnover, assessed by remaining advanced glycation end-product levels after a 6-h incubation, was preserved with PGRN treatment. Mitochondrial activity differed by complex, although PGRN appeared to increase overall activity in high glucose. We also found that activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and glycogen synthase kinase 3β (GSK3β), kinases implicated in autophagy function, increased with PGRN treatment under stress. Together, our data suggest that PGRN prevents hyperglycemia-induced decreases in autophagy by increasing autophagy flux via increased ERK1/2 kinase activity in primary rat cortical neurons.

Bruceine A protects against diabetic kidney disease via inhibiting galectin-1

Bruceine A is a natural quassinoid compound extracted from the fruit of the Traditional Chinese Medicine Brucea javanica (L.) Merr. that has various types of various biological activities. However, whether the compound has a protective effect on diabetic kidney disease remains unknown. Galectin-1 is actively involved in a variety of chronic inflammation-relevant human diseases including diabetic kidney disease. Here, we identified Bruceine A as a kidney protective molecule against a model of diabetic kidney disease in db/db mice with potent anti-inflammatory activity both invitro and invivo. Mechanistically, by selectively binding to the conserved carbohydrate-recognition domain of galectin-1 and disrupting the interaction between galectin-1 and the receptor for activated protein C kinase 1, Bruceine A was found to inhibit galectin-1-mediated inflammatory signal transduction under high glucose stress in rat mesangial HBZY-1 cells. Thus, our findings reveal Bruceine A as an unidentified galectin-1 inhibitor affording significant protection against diabetic kidney disease and may provide novel pharmacological therapeutics for the disease.

LXR activation ameliorates high glucose stress-induced aberrant mitochondrial dynamics via downregulation of Calpain1 expression in H9c2 cardiomyoblasts

Liver-X-receptor (LXR) has previously been shown to exert a cardioprotective effect against the development of diabetic cardiomyopathy (DCM) associated with a reduction in mitochondrial dysfunction. However, the underlying mechanism by which LXR activation attenuates the structural and functional mitochondrial impairments caused by high glucose (HG) stress remains unclear. We demonstrate here that LXR activation inhibits HG stress-induced mitochondrial dysfunction and ameliorates aberrant mitochondrial dynamics. Furthermore, LXR activation regulates mitochondrial dynamics by inhibiting HG stress-induced upregulation of Calpain1 expression. These data indicate that amelioration of Calpain1-mediated aberrant mitochondrial dynamics may be at least part of the mechanism underlying the cardioprotective effects of LXR against HG stress. Therefore, LXR is a potentially attractive molecular target for treating cardiac mitochondrial dysfunction in patients with diabetes.