FNDC5/Irisin mitigates high glucose-induced neurotoxicity in HT22 cell via ferroptosis.

Diabetes-induced neuropathy represents a major etiology of dementia, highlighting an urgent need for the development of effective therapeutic interventions. In this study, we explored the role of fibronectin type III domain containing 5 (FNDC5)/Irisin in mitigating hyperglycemia-induced neurotoxicity in HT22 cells and investigated the underlying mechanisms. Our findings reveal that high glucose conditions are neurotoxic, leading to reduced viability of HT22 cells and increased apoptosis. Furthermore, the elevated expression of the intracellular ferroptosis marker Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), along with increased levels of ferrous ions and malondialdehyde (MDA), suggests that high glucose conditions may induce ferroptosis in HT22 cells. FNDC5/Irisin treatment effectively mitigates high glucose-induced neurotoxicity and ferroptosis in HT22 cells. Mechanistically, FNDC5/Irisin enhances cellular antioxidant capacity, regulates ACSL4 expression, and improves intracellular redox status, thereby inhibiting ferroptosis and increasing HT22 cell survival under high-glucose conditions. These results highlight the neuroprotective potential of FNDC5/Irisin in high glucose environments, offering a promising avenue for developing treatments for diabetes-related neurodegenerative diseases.

miR-210 as a therapeutic target in diabetes-associated endothelial dysfunction.

BACKGROUND AND PURPOSE: MicroRNA (miR)-210 function in endothelial cells and its role in diabetes-associated endothelial dysfunction are not fully understood. We aimed to characterize the miR-210 function in endothelial cells and study its therapeutic potential in diabetes. EXPERIMENTAL APPROACH: Two different diabetic mouse models (db/db and Western diet-induced), miR-210 knockout and transgenic mice, isolated vessels and human endothelial cells were used. KEY RESULTS: miR-210 levels were lower in aortas isolated from db/db than in control mice. Endothelium-dependent relaxation (EDR) was impaired in aortas from miR-210 knockout mice, and this was restored by inhibiting miR-210 downstream protein tyrosine phosphatase 1B (PTP1B), mitochondrial glycerol-3-phosphate dehydrogenase 2 (GPD2), and mitochondrial oxidative stress. Inhibition of these pathways also improved EDR in both diabetic mouse models. High glucose reduced miR-210 levels in endothelial cells and impaired EDR in mouse aortas, effects that were reversed by overexpressing miR-210. However, plasma miR-210 levels were not affected in individuals with type 2 diabetes (T2D) following improved glycaemic status. Of note, genetic overexpression using miR-210 transgenic mice and pharmacological overexpression using miR-210 mimic in vivo ameliorated endothelial dysfunction in both diabetic mouse models by decreasing PTP1B, GPD2 and oxidative stress. Genetic overexpression of miR-210 altered the aortic transcriptome, decreasing genes in pathways involved in oxidative stress. miR-210 mimic restored decreased nitric oxide production by high glucose in endothelial cells. CONCLUSION AND IMPLICATIONS: This study unravels the mechanisms by which down-regulated miR-210 by high glucose induces endothelial dysfunction in T2D and demonstrates that miR-210 serves as a novel therapeutic target.

High glucose combined with lipopolysaccharide stimulation inhibits cell proliferation and migration of human HaCaT keratinocytes by impacting redox homeostasis and activating the polyol pathway.

BACKGROUND: High glucose level and chronic inflammation are characteristic features of diabetic cutaneous wounds. Keratinocytes make up the epidermis and play an important role in skin repair. However, metabolomic changes of keratinocytes in chronic diabetic ulcers have not been fully studied. METHODS AND RESULTS: This study used high levels of glucose combined with lipopolysaccharide to treat human HaCaT keratinocytes. Untargeted metabolomic combined with colorimetric assays were used to explore the changes of keratinocyte metabolites and related metabolic pathways caused by high glucose and lipopolysaccharide. Results demonstrated that high glucose combined with lipopolysaccharide treatment increased intracellular reactive oxygen species and impaired proliferation and migration of keratinocytes. Untargeted metabolomics analysis identified a total of 273 differential metabolites. Redox metabolism associated metabolites were largely altered. Reduced nicotinamide adenine dinucleotide, gamma-glutamylcysteine, superoxide dismutase activity and SOD2 gene expression were significantly upregulated while nicotinamide adenine dinucleotide, glutathione, glutathione peroxidase, several types of lysophosphatidylcholine, lysophosphatidylinositol, and GPR55 gene expression were downregulated. Alterations of glutathione and nicotinamide adenine dinucleotide were verified by colorimetric assays. For the first time, high glucose and LPS were observed to boost the levels of fructose, aldose reductase and sorbitol dehydrogenase of the polyol pathway in HaCaT cells. Further treatment of HaCaT with fructose leading to inhibition of cell proliferation and migration. CONCLUSIONS: Our data suggest high glucose combined with lipopolysaccharide significantly altered redox homeostasis associated metabolites and activate the polyol pathway in keratinocytes to impact cell proliferation and migration, providing new strategies for the treatment of chronic diabetic ulcers.

Role of Exogenous Pyruvate in Maintaining Adenosine Triphosphate Production under High-Glucose Conditions through PARP-Dependent Glycolysis and PARP-Independent Tricarboxylic Acid Cycle.

Pyruvate serves as a key metabolite in energy production and as an anti-oxidant. In our previous study, exogenous pyruvate starvation under high-glucose conditions induced IMS32 Schwann cell death because of the reduced glycolysis-tricarboxylic acid (TCA) cycle flux and adenosine triphosphate (ATP) production. Thus, this study focused on poly-(ADP-ribose) polymerase (PARP) to investigate the detailed molecular mechanism of cell death. Rucaparib, a PARP inhibitor, protected Schwann cells against cell death and decreased glycolysis but not against an impaired TCA cycle under high-glucose conditions in the absence of pyruvate. Under such conditions, reduced pyruvate dehydrogenase (PDH) activity and glycolytic and mitochondrial ATP production were observed but not oxidative phosphorylation or the electric transfer chain. In addition, rucaparib supplementation restored glycolytic ATP production but not PDH activity and mitochondrial ATP production. No differences in the increased activity of caspase 3/7 and the localization of apoptosis-inducing factor were found among the experimental conditions. These results indicate that Schwann cells undergo necrosis rather than apoptosis or parthanatos under the aforementioned conditions. Exogenous pyruvate plays a pivotal role in maintaining the flux in PARP-dependent glycolysis and the PARP-independent TCA cycle in Schwann cells under high-glucose conditions.

PSAT1 is upregulated by METTL3 to attenuate high glucose-induced retinal pigment epithelial cell apoptosis and oxidative stress.

BACKGROUND: Diabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, and a significant cause of visual impairment and blindness in adults. Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis, which might improve insulin signaling and insulin sensitivity. Furthermore, it has been reported that the m6A methylation in mRNA controls gene expression under many physiological and pathological conditions. Nevertheless, the influences of m6A methylation on PSAT1 expression and DR progression at the molecular level have not been reported. METHODS: High-glucose (HG) was used to treat human retinal pigment epithelial cells (ARPE-19) to construct a cell injury model. PSAT1 and Methyltransferase-like 3 (METTL3) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). PSAT1, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), and METTL3 protein levels were examined by western blot assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and TUNEL assays. Reactive oxygen species (ROS), malondialdehyde (MDA), and Glutathione peroxidase (GSH-Px) levels were examined using special assay kits. Interaction between METTL3 and PSAT1 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay. RESULTS: PSAT1 and METTL3 levels were decreased in DR patients and HG-treated ARPE-19 cells. Upregulation of PSAT1 might attenuate HG-induced cell viability inhibition and apoptosis and oxidative stress promotion in ARPE-19 cells. Moreover, PSAT1 was identified as a downstream target of METTL3-mediated m6A modification. METTL3 might improve the stability of PSAT1 mRNA via m6A methylation. CONCLUSION: METTL3 might mitigate HG-induced ARPE-19 cell damage partly by regulating the stability of PSAT1 mRNA, providing a promising therapeutic target for DR.

The mRNA stability of PIEZO1, regulated by METTL3 via m6A modification in a YTHDF2-dependent manner, facilitates the progression of diabetic retinopathy.

Diabetic retinopathy (DR) is the major ocular complication of diabetes mellitus caused by chronic hyperglycemia, which leads to incurable blindness. Currently, the effectiveness of therapeutic interventions is limited. This study aimed to investigate the function of piezo-type mechanosensitive ion channel component 1 (PIEZO1) and its potential regulatory mechanism in DR progression. The results showed that PIEZO1 expression was upregulated in the retinal tissues of streptozotocin-induced diabetic mice and high glucose (HG)-triggered Müller cells. Functionally, the knockdown of PIEZO1 improves the abnormal retinal function of diabetic mice and impedes inflammatory cytokine secretion and gliosis of Müller cells under HG conditions. Mechanistic investigations utilizing RIP-qPCR, MeRIP-qPCR, and luciferase reporter assays demonstrated that PIEZO1 was a downstream target of methyltransferase-like 3 (METTL3). These studies revealed that METTL3-mediated N6-methyladenosine (m6A) modification within the coding sequence of PIEZO1 mRNA significantly shortened its half-life. In HG-stimulated cells, there was a negative regulatory relationship between PIEZO1 and YTH domain family 2 (YTHDF2), a recognized m6A reader. The loss of YTHDF2 resulted in an extended half-life of PIEZO1 in cells with overexpression of METTL3, indicating that the effect of METTL3 on the mRNA stability of PIEZO1 was dependent on YTHDF2. Taken together, this study demonstrated the protective role of the PIEZO1 silencing in DR development, and the degradation of PIEZO1 mRNA is accelerated by METTL3/YTHDF2-mediated m6A modification.

Homoplantaginin alleviates high glucose-induced vascular endothelial senescence by inhibiting mtDNA-cGAS-STING pathway via blunting DRP1-mitochondrial fission-VDAC1 axis.

Vascular endothelial senescence is a major risk factor for diabetic vascular complications. Abnormal mitochondrial fission by dynamically related protein 1 (DRP1) accelerates vascular endothelial cell senescence. Homoplantaginin (Hom) is a flavonoid in Salvia plebeia R. Br. with protecting mitochondrial and repairing vascular properties. However, the relevant mechanism of Hom against diabetic vascular endothelial cell senescence remains unclear. Here, we used db/db mice and high glucose (HG)-treated human umbilical vein endothelial cells (HUVECs) to assess the anti-vascular endothelial cell senescence of Hom. We found that Hom inhibited senescence-associated ß-galactosidase activity, decreased the levels of senescence markers, and senescence-associated secretory phenotype factors. Additionally, Hom inhibited the expression of cGAS-STING pathway and downstream inflammatory factors. STING inhibitor H-151 delayed endothelial senescence, whereas STING overexpression attenuated the anti-endothelial senescence effect of Hom. Furthermore, we observed that Hom reduced mitochondrial fragmentation and inhibited abnormal mitochondrial fission using transmission electron microscopy. Importantly, Hom has a stronger effect on mitochondrial fission protein than mitochondrial fusion protein, especially downregulated the expression of DRP1. DRP1 inhibitor Mdivi-1 suppressed cGAS-STING pathway and vascular endothelial senescence, yet DRP1 agonist FCCP attenuated the effect of Hom. Surprisingly, Hom blunted abnormal mitochondrial fission mediated by DRP1 mitochondrial localization, suppressed interaction of DRP1 with VDAC1 and prevented VDAC1 oligomerization, which was necessary for mtDNA escape and subsequent cGAS-STING pathway activation. These results revealed a previously unrecognized mechanism that Hom alleviated vascular endothelial senescence by inhibited mtDNA-cGAS-STING signaling pathway via blunting DRP1-mitochondrial fission-VDAC1 axis.

MiR-146a Is Mutually Regulated by High Glucose-Induced Oxidative Stress in Human Periodontal Ligament Cells.

The high-glucose conditions caused by diabetes mellitus (DM) exert several effects on cells, including inflammation. miR-146a, a kind of miRNA, is involved in inflammation and may be regulated mutually with reactive oxygen species (ROS), which are produced under high-glucose conditions. In the present study, we used human periodontal ligament cells (hPDLCs) to determine the effects of the high-glucose conditions of miR-146a and their involvement in the regulation of oxidative stress and inflammatory cytokines using Western blotting, PCR, ELISA and other methods. When hPDLCs were subjected to high glucose (24 mM), cell proliferation was not affected; inflammatory cytokine expression, ROS induction, interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) expression increased, but miR-146a expression decreased. Inhibition of ROS induction with the antioxidant N-acetyl-L-cysteine restored miR-146a expression and decreased inflammatory cytokine expression compared to those under high-glucose conditions. In addition, overexpression of miR-146a significantly suppressed the expression of the inflammatory cytokines IRAK1 and TRAF6, regardless of the glucose condition. Our findings suggest that oxidative stress and miR-146a expression are mutually regulated in hPDLCs under high-glucose conditions.

High glucose- or AGE-induced oxidative stress inhibits hippocampal neuronal mitophagy through the Keap1-Nrf2-PHB2 pathway in diabetic encephalopathy.

Diabetic encephalopathy (DE) is a severe complication of diabetes, but its pathogenesis remains unclear. This study aimed to investigate the roles and underlying mechanisms of high glucose (HG)- and advanced glycosylation end product (AGE)-induced oxidative stress (OS) in the cognitive decline in DE. The DE mouse model was established using a high-fat diet and streptozotocin, and its cognitive functions were evaluated using the Morris Water Maze, novel object recognition, and Y-maze test. The results revealed increased reactive oxygen species (ROS) generation, mitophagy inhibition, and decreased prohibitin 2 (PHB2) expression in the hippocampal neurons of DE mice and HG- or AGE-treated HT-22 cells. However, overexpression of PHB2 reduced ROS generation, reversed mitophagy inhibition, and improved mitochondrial function in the HG- or AGE-treated HT-22 cells and ameliorated cognitive decline, improved mitochondrial structural damage, and reversed mitophagy inhibition of hippocampal neurons in DE mice. Further analysis revealed that the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was involved in the HG- or AGE-mediated downregulation of PHB2 in HT-22 cells. These results demonstrate that HG- or AGE-induced OS inhibits the mitophagy of hippocampal neurons via the Keap1-Nrf2-PHB2 pathway, thereby contributing to the cognitive decline in DE.

High glucose elevates intracellular calcium level and induces ferroptosis in glomerular endothelial cells through the miR-223-3p/ITPR3 pathway.

We investigated the link between ferroptosis and the miR-223-3p/inositol 1,4,5-trisphosphate receptor type 3 (ITPR3) pathway in diabetic kidney disease (DKD). Blood samples from DKD patients and healthy controls were analysed for iron ions, calcium ions, and lipid peroxidation. High-glucose-induced glomerular endothelial cells were used to simulate DKD. MiR-223-3p overexpression or silencing was achieved using adenoviruses, affecting ferroptosis regulators (glutathione peroxidase 4 [GPX4], cystine/glutamate transporter (xCT), and long-chain acyl-CoA synthetase 4 [ACSL4]) and ITPR3. DKD patients showed elevated levels of iron ions, calcium ions, and lipid peroxidation. High glucose downregulated miR-223-3p, reducing xCT and GPX4 expression and increasing ACSL4 expression. MiR-223-3p was confirmed to target ITPR3 through luciferase reporter assay. MiR-223-3p overexpression reversed high-glucose-induced effects on ferroptosis markers and ITPR3 expression. In summary, high glucose levels decreased miR-223-3p expression, leading to increased calcium ion levels and ferroptosis, potentially through ITPR3 modulation. These findings provide insights into the mechanisms underlying DKD and its potential therapeutic targets.

Effect of High Glucose on Embryological Development of Zebrafish, Brachyodanio, Rerio through Wnt Pathway.

Gestational diabetes mellitus (GDM) is a worldwide pregnancy complication. Gestational diabetes can significantly impact fetus development. However, the effects of high glucose on embryological development post-fertilization are yet to be researched. Danio rerio embryos are a great model for studying embryonic development. In this study, the effects on embryological (morphological and genetic) development were examined in the presence of a high-glucose environment that mimics the developing fetus in pregnant women with GDM. Fertilized zebrafish embryos were treated with normal media and high glucose for 5 days from 3 h post-fertilization (hpf) to 96 hpf, respectively, as control and experimental groups. Morphological changes are recorded with microscope images. Hatch rate and heart rate are compared between groups at set time points. RNA-Seq is performed to examine the gene changes in the experimental group. Glucose delayed the zebrafish embryo development by slowing the hatch rate by about 24 h. The brain, heart, and tail started showing smaller morphology in the glucose group compared to the control group at 24 hpf. Heart rate was faster in the glucose group compared to the control group on days 2 and 3 with a statistically significant difference. Among the zebrafish whole genome, the significantly changed genes were 556 upregulated genes and 1118 downregulated genes, respectively, in the high-glucose group. The metabolic and Wnt pathways are altered under high-glucose conditions. These conditions contribute to significant physiological differences that may provide insight into the functionality of post-embryological development.

Exendin-4 exhibits cardioprotective effects against high glucose-induced mitochondrial abnormalities: Potential role of GLP-1 receptor and mTOR signaling.

Mitochondrial dysfunction is associated with hyperglycemic conditions and insulin resistance leading to cellular damage and apoptosis of cardiomyocytes in diabetic cardiomyopathy. The dysregulation of glucagon-like peptide-1 (GLP-1) receptor and mammalian target of rapamycin (mTOR) is linked to cardiomyopathies and myocardial dysfunctions mediated by hyperglycemia. However, the involvements of mTOR for GLP-1 receptor-mediated cardioprotection against high glucose (HG)-induced mitochondrial disturbances are not clearly identified. The present study demonstrated that HG-induced cellular stress and mitochondrial damage resulted in impaired ATP production and oxidative defense markers such as catalase and SOD2, along with a reduction in survival markers such as Bcl-2 and p-Akt, while an increased expression of pro-apoptotic marker Bax was observed in H9c2 cardiomyoblasts. In addition, the autophagic marker LC3-II was considerably reduced, together with the disruption of autophagy regulators (p-mTOR and p-AMPKα) under the hyperglycemic state. Furthermore, there was a dysregulated expression of several indicators related to mitochondrial homeostasis, including MFN2, p-DRP1, FIS1, MCU, UCP3, and Parkin. Remarkably, treatment with either exendin-4 (GLP-1 receptor agonist) or rapamycin (mTOR inhibitor) significantly inhibited HG-induced mitochondrial damage while co-treatment of exendin-4 and rapamycin completely reversed all mitochondrial abnormalities. Antagonism of GLP-1 receptors using exendin-(9-39) abolished these cardioprotective effects of exendin-4 and rapamycin under HG conditions. In addition, exendin-4 attenuated HG-induced phosphorylation of mTOR, and this inhibitory effect was antagonized by exendin-(9-39), indicating the regulation of mTOR by GLP-1 receptor. Therefore, improvement of mitochondrial dysfunction by stimulating the GLP-1 receptor/AMPK/Akt pathway and inhibiting mTOR signaling could ameliorate cardiac abnormalities caused by hyperglycemic conditions.

P4HB regulates the TGFß/SMAD3 signaling pathway through PRMT1 to participate in high glucose-induced epithelial-mesenchymal transition and fibrosis of renal tubular epithelial cells.

BACKGROUND: Diabetic nephropathy (DN) is a common complication of diabetes mellitus, and Prolyl 4-Hydroxylase Subunit Beta (P4HB) expression is increased in high glucose (HG)-induced renal tubular epithelial cells (TECs). But it's role in HG-induced TECs remains to be elucidated. METHODS: The HK-2 cells were induced using HG and transfected with SiRNA-P4HB. DCFH-DA staining was utilized for the detection of cellular levels of ROS. WB and immunofluorescence were utilized to detect the expression of P4HB, epithelial-mesenchymal transition (EMT), fibrosis, and TGFß/SMAD3-related proteins in HK-2 cells. Online databases were utilized for predicting the interaction target of P4HB, and immunoprecipitation (IP) experiments were employed to validate the binding of P4HB with the target. SiRNA and overexpression vectors of target gene were used to verify the mechanism of action of P4HB. RESULTS: HG induced an increase in the expression of P4HB and TGFß, p-SMAD3, and ROS in HK-2 cells. Furthermore, HG downregulated the expression of E-cadherin and upregulated the expression of N-cadherin, Vimentin, α-SMA, Fibronectin, Collagen IV, SNAIL, and SLUG in HK-2 cells. Interfering with P4HB significantly reversed the expression of these proteins. Database predictions and IP experiments showed that P4HB interacts with PRMT1, and the expression of PRMT1 was increased in HG-induced HK-2 cells. Interfering with PRMT1 inhibited the changes in expression of EMT and fibrosis related proteins induced by HG. However, overexpression of PRMT1 weakened the regulatory effect of P4HB interference on the EMT, fibrosis, and TGFß/SMAD3-related proteins in HK-2 cells. CONCLUSION: P4HB regulated the TGFß/SMAD3 signaling pathway through PRMT1 and thus participates in HG-induced EMT and fibrosis in HK-2 cells.

Banxia Xiexin Tang attenuates high glucose-induced hepatocyte injury by activating SOD2 to scavenge ROS via PGC-1α/IGFBP1.

This study aimed to explore the protective mechanism of Banxia Xiexin Tang (BXXXT) on liver cell damage caused by high glucose (H-G) and to clarify its molecular regulatory pathways. First, the main components in BXXXT-containing serum were analyzed by high-performance liquid chromatography (HPLC) to provide basic data for subsequent experiments. Subsequently, the effect of BXXXT on high glucose (H-G)-induced hepatocyte activity was evaluated through screening of the optimal concentration of drug-containing serum. Experimental results showed that BXXXT significantly reduced the loss of cell activity caused by high glucose. Further research focuses on the regulatory effect of BXXXT on high glucose-induced hepatocyte apoptosis, especially its effect on the PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α) pathway. Experimental results showed that BXXXT reduced high-glucose-induced hepatocyte apoptosis and exerted its protective effect by upregulating the activity of the PGC-1α pathway. BXXXT significantly increased the expression level of IGFBP1 (insulin-like growth factor-binding proteins) in hepatocytes under a high-glucose environment. It cleared mitochondrial ROS (reactive oxygen species) by enhancing SOD2 (superoxide dismutase) enzyme activity and maintained the survival of hepatocytes under a high-glucose environment. Finally, the regulation of PGC-1α by BXXXT is indeed involved in the regulation of IGFBP1 expression in hepatocytes and its downstream SOD2 effector signaling. Taken together, this study provides an in-depth explanation of the protective mechanism of BXXXT on hepatocytes in a high-glucose environment, focusing on regulating the expression of the PGC-1α pathway and IGFBP1, and reducing cell damage by scavenging ROS. This provides an experimental basis for further exploring the potential of BXXXT in the treatment of diabetes-related liver injury. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-024-04060-0.

Melatonin alleviates high glucose-induced cardiomyocyte injury through suppressing mitochondrial FUNDC1-DRP1 axis.

OBJECTIVES: To use H9c2 cardiomyocytes to establish a diabetic cardiomyopathic model by exposing these cells to high glucose (HG), followed by treating them with melatonin (MEL) or plasmid vectors overexpressing FUN14 Domain Containing 1 (FUNDC1). METHODS: We employed quantitative real-time PCR, mitochondrial staining, and biochemical assays to measure the activity of various antioxidant and mitochondrial complex functions under various treatment conditions. KEY FINDINGS: Our results showed that HG induced the expression of FUNDC1 and increased mitochondrial oxidative stress and fragmentation, while MEL treatment reversed most of these pathological effects. Moreover, HG exposure activated dynamin-related protein 1 expression and its translocation to mitochondria. Modulation of AMP-activated protein kinase level was found to be another pathological hallmark. In silico molecular docking, analysis revealed that MEL could directly bind the catalytic groove of FUNDC1 through Van der Waal's force and hydrogen bonding. Finally, MEL ameliorated diabetic cardiomyopathy-induced mitochondrial injury through FUNDC1 in vivo. CONCLUSIONS: Hyperglycemia induced mitochondrial fragmentation and altered electron transport chain complex functions, which could be ameliorated by MEL treatment, suggesting its potential as a cardiovascular therapeutic.

Effects of GABA on Oxidative Stress and Metabolism in High-Glucose Cultured Mongolian Sheep Kidney Cells.

The Mongolian sheep, emblematic of the Inner Mongolian grasslands, is renowned for its exceptional stress resistance and adaptability to harsh environments, drawing considerable attention. Recent research has unveiled the novel role of γ-aminobutyric acid (GABA) in combating oxidative stress. This investigation examined how GABA impacts renal-cortex and medulla cells from Mongolian sheep exposed to high-glucose stress conditions, utilizing gene expression analysis and non-targeted metabolomics. Elevated glucose levels significantly reduced the viability of Mongolian sheep renal cells and increased reactive oxygen species (ROS) levels. Conversely, the introduction of GABA notably enhanced cell viability, reduced ROS production, and stimulated the expression of antioxidant genes (e.g., Gpx, SOD, CAT) in the renal cortex. In the renal medulla, CAT expression increased, while Gpx gene expression showed mixed responses. Metabolomics analysis indicated that high-glucose exposure altered various metabolites, whereas GABA alleviated the metabolic stress induced by high glucose through modulating glycolysis and the tricarboxylic acid cycle. In Mongolian sheep renal cells, GABA effectively mitigated oxidative damage triggered by high-glucose stress by upregulating antioxidant genes and regulating metabolic pathways, revealing insights into its potential mechanism for adapting to extreme environments. This finding offers a fresh perspective on understanding the stress resilience of Mongolian sheep and may provide valuable insights for research across diverse disciplines.

Corilagin alleviates podocyte injury in diabetic nephropathy by regulating autophagy via the SIRT1-AMPK pathway.

BACKGROUND: Diabetic nephropathy (DN) is the most frequent chronic microvascular consequence of diabetes, and podocyte injury and malfunction are closely related to the development of DN. Studies have shown that corilagin (Cor) has hepatoprotective, anti-inflammatory, antibacterial, antioxidant, anti-hypertensive, anti-diabetic, and anti-tumor activities. AIM: To explore the protective effect of Cor against podocyte injury in DN mice and the underlying mechanisms. METHODS: Streptozotocin and a high-fat diet were combined to generate DN mice models, which were then divided into either a Cor group or a DN group (n = 8 in each group). Mice in the Cor group were intraperitoneally injected with Cor (30 mg/kg/d) for 12 wk, and mice in the DN group were treated with saline. Biochemical analysis was used to measure the blood lipid profiles. Hematoxylin and eosin staining was used to detect pathological changes in kidney tissue. Immunohistochemistry and Western blotting were used to assess the protein expression of nephrin and podocin. Mouse podocyte cells (MPC5) were cultured and treated with glucose (5 mmol/L), Cor (50 µM), high glucose (HG) (30 mmol/L), and HG (30 mmol/L) plus Cor (50 µM). Real-time quantitative PCR and Western blotting were performed to examine the effects of Cor on podocyte autophagy. RESULTS: Compared with the control group, the DN mice models had increased fasting blood glucose, glycosylated hemoglobin, triglycerides, and total cholesterol, decreased nephrin and podocin expression, increased apoptosis rate, elevated inflammatory cytokines, and enhanced oxidative stress. All of the conditions mentioned above were alleviated after intervention with Cor. In addition, Cor therapy improved SIRT1 and AMPK expression (P < 0.001), inhibited reactive oxygen species and oxidative stress, and elevated autophagy in HG-induced podocytes (P < 0.01). CONCLUSION: Cor alleviates podocyte injury by regulating autophagy via the SIRT1-AMPK pathway, thereby exerting its protective impact on renal function in DN mice.

[Daidzein attenuates high glucose-induced inflammatory injury in macrophages by regulating NLRP3 inflammasome signaling pathway].

This study aims to explore the inhibitory effect of daidzein on macrophage inflammation induced by high glucose via regulating the NOD-like receptor protein 3(NLRP3) inflammasome signaling pathway. The cell counting kit-8(CCK-8) assay was employed to detect the effects of daidzein at different concentrations on the viability of RAW264.7 cells. Western blot was employed to determine the protein level of tumor necrosis factor(TNF)-α in macrophages exposed to different concentrations of glucose for different time periods as well as the expression levels of proteins involved in the polarization and Toll-like receptor 4(TLR4)-myeloid differentiation factor(MyD88)-NLRP3 inflammasome pathway of the macrophages exposed to high glucose. Enzyme-linked immunosorbent assay was employed to measure the levels of TNF-α, interleukin(IL)-18, and IL-1ß secreted by macrophages. The expression level of nuclear factor-kappa B(NF-κB) p65 in macrophages exposed to high glucose was detected by immunofluorescence, and the level of intracellular reactive oxygen species(ROS) was detected by the DCFH-DA fluorescent probe. The mRNA levels of NLRP3, TNF-α, and IL-18 in macrophages were determined by qRT-PCR. The results showed that treatment with 30 mmol·L~(-1) glucose for 48 h was the best condition for the modeling of macrophage injury. Compared with the blank group, the model group showed improved polarization of macrophages, increased secretion of TNF-α, IL-18, and IL-1ß, elevated ROS level, and up-regulated expression of NF-κB p65. In addition, the modeling up-regulated the mRNA levels of NLRP3, TNF-α, and IL-18 and the protein levels of TLR4, MyD88, NLRP3, NF-κB p65, p-NF-κB p65, I-κB, p-I-κB, ASC, pro-caspase-1, pro-IL-1ß, cleaved IL-1ß, and pro-IL-18. Compared with the model group, daidzein(10, 20, and 40 µmol·L~(-1)) lowered the levels of inflammatory cytokines and down-regulated the mRNA levels of NLRP3, TNF-α, and IL-18 as well as the protein levels of TLR4, MyD88, NLRP3, NF-κB p65, p-NF-κB p65, I-κB, p-I-κB, ASC, pro-caspase-1, pro-IL-1ß, cleaved IL-1ß, and pro-IL-18. In addition, daidzein reduced intracellular ROS. According to the available reports and the experimental results, high glucose can induce the polarization of macrophages and promote the secretion of inflammatory cytokines. Daidzein can inhibit the expression of ROS in macrophages by regulating the NLRP3 inflammasome signaling pathway, thereby reducing the inflammation of macrophages exposed to high glucose.

Identification and functional characterization of differentially expressed circRNAs in high glucose treated endothelial cells: Construction of circRNA-miRNA-mRNA network.

Background: Endothelial dysfunction is a complication of diabetes mellitus (DM), characterized by impaired endothelial function in both microvessels and macrovessels, closely linked to atherosclerosis (AS). Endothelial dysfunction, characterized by impaired endothelial cell (EC) function, is a pivotal factor in AS and DM. Circular RNAs (circRNAs) are endogenous non-coding RNAs that can act as competing endogenous RNAs (ceRNAs) and regulate gene expression. However, the role of circRNAs in ECs dysfunction and AS under high glucose (HG) condition remains elusive. Methods: We performed high-throughput sequencing to identify differentially expressed (DE) circRNAs in human umbilical vein endothelial cells (HUVEC) exposed to HG, one risk factors of endothelial dysfunction and AS. We then validated eight candidate circRNAs by qRT-PCR and functional analysis, directing our attention to hsa_circ_0122319. Moreover, microarray analysis identified the differential expression profiles of miRNAs and mRNAs regulated by hsa_circ_0122319. Subsequently, the construction of the ceRNAs network employed bioinformatic analysis and Cytoscape software. Furthermore, the role of the PI3K-Akt signaling pathway in regulating ceRNAs was evaluated. Results: We detected 917 DE circRNAs in HG treated HUVEC. The parental genes of these circRNAs were enriched in cell cycle, cellular senescence and endocytosis related pathways. The differential expression of hsa_circ_0122319 was confirmed to be most obvious at the cellular level and in clinical samples by qPCR experiments. After overexpression of hsa_circ_0122319, 49 DE miRNAs and 459 DE mRNAs were identified using microarray analysis. Subsequently, a ceRNAs network was constructed, comprising hsa_circ_0122319, 8 miRNAs, and 41 mRNAs. Conclusion: In summary, our study delves into the role of circRNAs in endothelial dysfunction associated with DM and AS. Through high-throughput sequencing and validation, we identified hsa_circ_0122319 as a pivotal regulator of ECs function under HG conditions. It also showed that hsa_circ_0123319 has the potential to serve as a biomarker for DM and its vascular complications, and provides new evidence for future exploration of the intricate molecular mechanisms of endothelial dysfunction in the progression of DM and AS.

Urolithin A Ameliorates the TGF Beta-Dependent Impairment of Podocytes Exposed to High Glucose.

Increased activity of transforming growth factor-beta (TGF-ß) is a key factor mediating kidney impairment in diabetes. Glomerular podocytes, the crucial component of the renal filter, are a direct target of TGF-ß action, resulting in irreversible cell loss and progression of chronic kidney disease (CKD). Urolithin A (UA) is a member of the family of polyphenol metabolites produced by gut microbiota from ellagitannins and ellagic acid-rich foods. The broad spectrum of biological activities of UA makes it a promising candidate for the treatment of podocyte disorders. In this in vitro study, we investigated whether UA influences the changes exerted in podocytes by TGF-ß and high glucose. Following a 7-day incubation in normal (NG, 5.5 mM) or high (HG, 25 mM) glucose, the cells were treated with UA and/or TGF-ß1 for 24 h. HG and TGF-ß1, each independent and in concert reduced expression of nephrin, increased podocyte motility, and up-regulated expression of b3 integrin and fibronectin. These typical-for-epithelial-to-mesenchymal transition (EMT) effects were inhibited by UA in both HG and NG conditions. UA also reduced the typically elevated HG expression of TGF-ß receptors and activation of the TGF-ß signal transducer Smad2. Our results indicate that in podocytes cultured in conditions mimicking the diabetic milieu, UA inhibits and reverses changes underlying podocytopenia in diabetic kidneys. Hence, UA should be considered as a potential therapeutic agent in podocytopathies.