Catabolite Repression Research Articles

Biosynthesis of D-1,2,4-butanetriol promoted by a glucose-xylose dual metabolic channel system in engineered Escherichia coli

D-1,2,4-butanetriol (BT) is a widely used fine chemical that can be manufactured by engineered Escherichia coli expressing heterologous pathways and using xylose as a substrate. The current study developed a glucose-xylose dual metabolic channel system in an engineered E. coli and Combinatorially optimized it using multiple strategies to promote BT production. The carbon catabolite repression effects were alleviated by deleting the gene ptsG that encodes the major glucose transporter IICBGlc and mutating the gene crp that encodes the catabolite repressor protein, thereby allowing C-fluxes of both glucose and xylose into their respective metabolic channels separately and simultaneously, which increased BT production by 33% compared with that of the original MJ133K-1 strain. Then, the branch metabolic pathways of intermediates in the BT channel were investigated, the transaminase HisC, the ketoreductases DlD, OLD, and IlvC, and the aldolase MhpE and YfaU were identified as the enzymes for the branched metabolism of 2-keto-3-deoxy-xylonate, deletion of the gene hisC increased BT titer by 21.7%. Furthermore, the relationship between BT synthesis and the intracellular NADPH level was examined, and deletion of the gene pntAB that encodes a transhydrogenase resulted in an 18.1% increase in BT production. The combination of the above approaches to optimize the metabolic network increased BT production by 47.5%, resulting in 2.67 g/L BT in 24 deep-well plates. This study provides insights into the BT biosynthesis pathway and demonstrates effective strategies to increase BT production, which will promote the industrialization of the biosynthesis of BT.

Fructose vs. glucose: modulating stem cell growth and function through sugar supplementation.

In multicellular organisms, stem cells are impacted by microenvironmental resources such as nutrient availability and oxygen tension for their survival, growth, and differentiation. However, the accessibility of these resources in the pericellular environment greatly varies from organ to organ. This divergence in resource availability leads to variations in the potency and differentiation potential of stem cells. This study aimed to explore the distinct effects of glucose and fructose, as well as different oxygen tensions, on the growth dynamics, cytokine production, and differentiation of stem cells. We showed that replacing glucose with fructose subjected stem cells to stress, resulting in increased Hif1α expression and stability, which in turn led to a reduction in cell proliferation, and alterations in cytokine production. However, fructose failed to induce differentiation of human mesenchymal stem cells (hMSCs) as well as mouse fibroblasts into mature adipocytes compared to glucose, despite the upregulation of key markers of adipogenesis, including C/EBPβ, and PPARγ. Conversely, we showed that fructose induced undifferentiated mouse fibroblasts to release cytokines associated with senescence, including IL1α1, IL6, IL8, MCP1, and TNF1α, suggesting that these cells were undergoing lipolysis. Taken together, our results suggest that altering the culture conditions through changes in hexose levels and oxygen tension places considerable stress on stem cells. Additional research is required to further characterize the mechanisms governing stem cell response to their microenvironments.

The efficacy of self-monitoring of blood glucose (SMBG) intervention package through a subscription model among type-2 diabetes mellitus in Malaysia: a preliminary trial

BackgroundThe aim of this study was to determine the effect of a Self-Monitoring Blood Glucose (SMBG) intervention package through a subscription model in improving HbA1c and health parameters among type-2 diabetes mellitus (T2DM) individuals in Malaysia.MethodsThis is a quasi-experimental study involving a total number of 111 individuals with T2DM (mean age 57.0 ± 11.7 years, 61% men) who were assigned to intervention (n = 51) and control (n = 60) groups. The intervention group participants were the subscribers of SugO365 program which provided a personalized care service based on self-recorded blood glucose values. Subscribers received a Contour® Plus One glucometer which can connect to Health2Sync mobile app to capture all blood glucose readings as well as physical and virtual follow up with dietitians, nutritionists, and pharmacists for 6 months. Outcome measures were body weight, body mass index (BMI), random blood glucose (RBG), glycated haemoglobin (HbA1c) and health-related quality of life (HRQoL, assessed by SF-36 questionnaire). Data were measured at baseline, third and sixth months.ResultsRepeated-measure analysis of covariance showed significant improvement in HbA1c level (ƞp2 = 0.045, p = 0.008) in the intervention (baseline mean 7.7% ± 1.1%; end mean 7.3% ± 1.3%) as compared to control (baseline mean 7.7% ± 0.9%; end mean 8.1% ± 1.6%) group. Similar trend was observed for Role Emotional domain of the quality of life (ƞp2 = 0.047, p = 0.023) in the intervention (baseline mean 62.8 ± 35.1, end mean 86.3 ± 21.3) compared to control (baseline mean group 70.5 ± 33.8; end mean 78.4 ± 27.3) group. Negative association was found in HbA1c changes using Z-score and Physical Function domain (r = − 0.217, p = 0.022).ConclusionA 6 months SMBG intervention package through a subscription model improved blood glucose control as measured by HbA1c and health-related quality of life, particularly the Role Emotional domain. Elevated HbA1c levels are correlated with decreased physical function.There is a need to further examine the efficacy of SMBG intervention package using a larger sample and a longer period of intervention and to determine its cost efficacy.

Potential causal association of diabetes mellitus and blood glucose related indexes with the onset of epilepsy: a two-sample Mendelian randomization study.

Diabetes mellitus (DM) may promote the occurrence of epilepsy through mechanisms, such as inflammation, immune imbalance, and cerebrovascular injury, caused by metabolic abnormalities. However, evidence for the effects of DM and blood glucose (BG) on the risk of epilepsy is limited. Herein, this study used the Mendelian randomization (MR) method to investigate the potential causal associations of DM and BG-related indexes with epilepsy. In this two-sample MR study, summary statistics data of the genome-wide association studies (GWASs) on exposures, including type 1 diabetes mellitus (T1DM), T2DM, fasting glucose, and glycated hemoglobin (HbAlc), were extracted from the MRC-Integrative Epidemiology Unit (MRC-IEU). The GWAS data on study outcomes, including epilepsy, focal epilepsy, and generalized epilepsy, were obtained from the FinnGen consortium. MR-Egger regression was used to examine horizontal pleiotropism of instrumental variables (IVs), and Cochran's Q statistics was used to quantify the heterogeneity. MR analysis methods including inverse variance weighted (IVW) tests, weighted median, and MR-Egger were utilized to investigate the causal associations between DM and BG-related indexes with epilepsy. The evaluation indexes were odds ratios (ORs) and 95% confidence intervals (CIs). Reverse causal association analyses were also performed. In addition, IVW-radial and leave-one-out tests were utilized for sensitivity analyses. IVW estimates suggested that T1DM has potential causal associations with epilepsy (OR = 1.057, 95% CI: 1.031-1.084) and generalized epilepsy (OR = 1.066, 95% CI: 1.018-1.116). No significant reverse causal associations of T1DM with epilepsy or generalized epilepsy were found (all P > 0.05). In addition, sensitivity analysis results identified no outlier, indicating that the associations of T1DM with epilepsy and generalized epilepsy were relatively robust. Patients with T1DM had a potential risk of developing epilepsy, and prompt treatment of DM and dynamic monitoring may be beneficial to prevent epilepsy in this high-risk population. However, the causal associations of DM and BG with epilepsy may warrant further verification.

Changes in adiponectin levels of subclinical ketosis cows and their effects on steroid hormone secretion and proliferation in follicular granulosa cells

In dairy cows, the occurrence of subclinical ketosis (SCK) is particularly high during early lactation. Previously, we documented alterations in the abundance of adiponectin (ADPN) in anestrus cows with SCK in comparison to cows in estrus. In the present study, 60 cows were divided into two groups: control (C, n = 30) and SCK (n = 30). Based on cow’s estrus situation in two group at 55–60 days postpartum, 15 anestrus SCK cows and estrus cows were designated the SCK-A group and C-E group, respectively. The SCK-A group had downregulated serum and follicular fluid ADPN levels compared with the C-E group. The serum ADPN level was positively correlated with the insulin level and follicle growth rate, and there was a positive correlation between ADPN and glucose in the follicular fluid. Primary culture of dairy cow granulosa cells (GCs) was established to observe the effect of low glucose (Glu) and/or ADPN on GCs cyclins and proteins important for steroid synthesis. The results showed that the addition of 1 µg/mL ADPN alleviated the negative effects of low Glu treatment on the proliferation of GCs and the expression of steroid secretion related protein proteins. Treatment with LY294002 (PI3K inhibitor) four experimental GCs groups: control (0 µg/mL ADPN), 1 µg/mL ADPN, LY294002 inhibitor, and 1 µg/mL ADPN+LY294002. The results showed that ADPN promotes the secretion of steroid hormones by GCs through the PI3K–AKT. In summary, ADPN plays a crucial role in ameliorating postpartum anestrus in dairy cows with SCK.

Glucose-induced endocytic degradation of the maltose transporter MalP is mediated through ubiquitination by the HECT-ubiquitin ligase HulA and its adaptor CreD in Aspergillus oryzae

In the filamentous fungus Aspergillus oryzae, large amounts of amylolytic enzymes are inducibly produced by isomaltose, which is converted from maltose incorporated via the maltose transporter MalP. In contrast, the preferred sugar glucose strongly represses the expression of both amylolytic and malP genes through carbon catabolite repression. Simultaneously, the addition of glucose triggers the endocytic degradation of MalP on the plasma membrane. In budding yeast, the signal-dependent ubiquitin modification of plasma membrane transporters leads to selective endocytosis into the vacuole for degradation. In addition, during glucose-induced MalP degradation, the homologous of E6AP C-terminus-type E3 ubiquitin ligase (HulA) is responsible for the ubiquitin modification of MalP, and the arrestin-like protein CreD is required for HulA targeting. Although CreD-mediated MalP internalization occurs in response to glucose, the mechanism by which CreD regulates HulA-dependent MalP ubiquitination remains unclear. In this study, we demonstrated that three (P/L)PxY motifs present in the CreD protein are essential for functioning as HulA adaptors so that HulA can recognize MalP in response to glucose stimulation, enabling MalP internalization. Furthermore, four lysine residues (three highly conserved among Aspergillus species and yeast and one conserved among Aspergillus species) of CreD were found to be necessary for its ubiquitination, resulting in efficient glucose-induced MalP endocytosis. The results of this study pave the way for elucidating the regulatory mechanism of MalP endocytic degradation through ubiquitination by the HulA–CreD complex at the molecular level.

Differential signaling effects of blood glucose on delay discounting in individuals with and without type 1 diabetes.

Based on the signaling hypothesis of blood glucose (BG), a rise in BG levels signals a positive energy budget for healthy individuals but cellular starvation for individuals with type 1 diabetes. We examined this novel prediction and its intervention implications in the context of delay discounting, the degree to which delayed rewards are discounted, and the regulatory effects of insulin ingestion. We recruited 44 adults with type 1 diabetes (mean age 30.8 years, diabetes duration 15.4 years) and recorded their BG levels. The delay discounting rate was measured using the intertemporal choice task, where participants were required to choose between sets of smaller-and-sooner (SS) and larger-and-later (LL) rewards. In addition, 82 age-matched healthy participants were recruited to provide a baseline comparison on delay discounting. Random forest analysis showed that among many diagnostic factors, delay discounting was most dominating in differentiating the individuals with type 1 diabetes from the control participants. A hierarchical linear mixed model revealed that participants with type 1 diabetes had a stronger preference for SS rewards (p < .001) after controlling for covariates. Participants who had insulin delivered before the last meal exhibited a stronger preference for LL rewards compared to after-meal delivery. In contrast, subjective measures (e.g., self-reported hunger) failed to predict the participants' actual BG levels and delay discounting rates. In sum, individuals with type 1 diabetes tend to discount future rewards excessively compared to the control participants. Pre-meal insulin ingestion was associated with a higher LL preference for future rewards.

Progress in the study of association between hematological indicators and retinopathy of prematurity (Review).

Retinopathy of prematurity (ROP) is a retinopathy caused by abnormal proliferation of blood vessels in premature infants. It can lead to retinal detachment and, in severe cases, blindness, rendering ROP a critical condition. Advances in neonatal medicine have improved survival rates of low birth weight and low gestational age infants. However, this progress has also led to a rise in incidence of ROP. Currently, premature birth, low birth weight and high postpartum oxygen levels are independent risk factors for ROP. Other factors include mode of delivery, multiple births, anemia, blood transfusion, maternal pregnancy factors, neonatal bronchopulmonary dysplasia, use of surfactants, arterial ductus arteriosus and necrotizing enterocolitis. Laboratory indicators in premature infants such as platelet count, levels of blood glucose, inflammatory cells, lipid and hemoglobin and blood transfusion may also be associated with ROP. However, the etiology and pathogenesis of ROP are not fully understood. A number of factors may influence the onset and progression of ROP, including decreased platelet counts, decreased hemoglobin levels, increased white blood cell counts, increased blood glucose levels, and disorders of lipid metabolism. The present study reviewed the effects of platelet count, hemoglobin, blood glucose, inflammatory cells and factors, blood lipids, and plasma metabolic pathways on ROP.

Differential Carbon Catabolite Repression and Hemicellulolytic Ability among Pathotypes of Colletotrichum lindemuthianum against Natural Plant Substrates.

Colletotrichum lindemuthianum is a phytopathogenic fungus that causes anthracnose in common beans (Phaseolus vulgaris) and presents a great diversity of pathotypes with different levels of virulence against bean varieties worldwide. The purpose of this study was to establish whether pathotypic diversity is associated with differences in the mycelial growth and secretion of plant-cell-wall-degrading enzymes (PCWDEs). We evaluated growth, hemicellulase and cellulase activity, and PCWDE secretion in four pathotypes of C. lindemuthianum in cultures with glucose, bean hypocotyls and green beans of P. vulgaris, and water hyacinth (Eichhornia crassipes). The results showed differences in the mycelial growth, hemicellulolytic activity, and PCWDE secretion among the pathotypes. Glucose was not the preferred carbon source for the best mycelial growth in all pathotypes, each of which showed a unique PCWDE secretion profile, indicating different levels of carbon catabolite regulation (CCR). The pathotypes showed a high differential hemicellulolytic capacity to degrade host and water hyacinth tissues, suggesting CCR by pentoses and that there are differences in the absorption and metabolism of different monosaccharides and/or disaccharides. We propose that different levels of CCR could optimize growth in different host tissues and could allow for consortium behavior in interactions with bean crops.

Inactivation of Pseudomonas putida KT2440 pyruvate dehydrogenase relieves catabolite repression and improves the usefulness of this strain for degrading aromatic compounds.

Pyruvate dehydrogenase (PDH) catalyses the irreversible decarboxylation of pyruvate to acetyl-CoA, which feeds the tricarboxylic acid cycle. We investigated how the loss of PDH affects metabolism in Pseudomonas putida. PDH inactivation resulted in a strain unable to utilize compounds whose assimilation converges at pyruvate, including sugars and several amino acids, whereas compounds that generate acetyl-CoA supported growth. PDH inactivation also resulted in the loss of carbon catabolite repression (CCR), which inhibits the assimilation of non-preferred compounds in the presence of other preferred compounds. Pseudomonas putida can degrade many aromatic compounds, most of which produce acetyl-CoA, making it useful for biotransformation and bioremediation. However, the genes involved in these metabolic pathways are often inhibited by CCR when glucose or amino acids are also present. Our results demonstrate that the PDH-null strain can efficiently degrade aromatic compounds even in the presence of other preferred substrates, which the wild-type strain does inefficiently, or not at all. As the loss of PDH limits the assimilation of many sugars and amino acids and relieves the CCR, the PDH-null strain could be useful in biotransformation or bioremediation processes that require growth with mixtures of preferred substrates and aromatic compounds.

Associations between blood glucose and early- and late-onset colorectal cancer: evidence from two prospective cohorts and Mendelian randomization analyses

BackgroundThe incidence of early-onset colorectal cancer (EOCRC), which exhibits differential clinical, pathological, and molecular features compared to late-onset CRC (LOCRC), is rising globally. The potential differential effects of blood glucose on EOCRC compared to LOCRC have not been investigated. MethodsThis study analyzed 374,568 participants from the UK Biobank cohort and 172,809 participants from the Kailuan cohort. The linear associations between blood glucose and EOCRC/LOCRC were estimated using Cox regression models. Restricted cubic spline (RCS) analysis and non-linear Mendelian randomization (MR) analysis using a 70-SNPs genetic instrument for fasting glucose were used to explore the potential non-linear associations. ResultsParticipants in the highest quintile of blood glucose had higher overall CRC risk compared to the lowest quintile (HR = 1.10 in the UK Biobank cohort, 95% CI: 1.01–1.21, P-trend = 0.012; HR = 1.23 in the Kailuan cohort, 95% CI: 1.01–1.51, P-trend = 0.036). Elevated glucose (>7.0 mmol/L) was more strongly associated with increased risk of EOCRC (HR = 1.61, 95% CI: 1.07–2.44) than with LOCRC (HR = 1.14, 95% CI: 1.02–1.27) in the UK Biobank cohort (P-heterogeneity = 0.014). Elevated glucose (>7.0 mmol/L) was associated with increased risk of LOCRC (HR = 1.25, 95% CI: 1.04–1.65) in the Kailuan cohort as well. There was no evidence for non-linear associations between blood glucose and risks of EOCRC/LOCRC. ConclusionsThis study showed a positive association between blood glucose and CRC risk in a dose-response manner, particularly for EOCRC, suggesting that tighter glucose control should be a priority for younger age groups.

High glucose inhibits autophagy and promotes the proliferation and metastasis of colorectal cancer through the PI3K/AKT/mTOR pathway.

Colorectal cancer (CRC) ranks among the most prevalent malignancies worldwide, characterized by its complex etiology and slow research progress. Diabetes, as an independent risk factor for CRC, has been widely certified. Consequently, this study centers on elucidating the intricacies of CRC cells initiation and progression within a high-glucose environment. A battery of assays was employed to assess the proliferation and metastasis of CRC cells cultured under varying glucose concentrations. Optimal glucose levels conducive to cells' proliferation and migration were identified. Western blot analyses were conducted to evaluate alterations in apoptosis, autophagy, and EMT-related proteins in CRC cells under high-glucose conditions. The expression of PI3K/AKT/mTOR pathway-associated proteins was assessed using western blot. The effect of high glucose on xenograft growth was investigated invivo by MC38 cells, and changes in inflammatory factors (IL-4, IL-13, TNF-α, IL-5, and IL-12) were measured via serum ELISA. Our experiments demonstrated that elevated glucose concentrations promoted both the proliferation and migration of CRC cells; the most favorable glucose dose is 20 mM. Western blot analyses revealed a decrease in apoptotic proteins, such as Bim, Bax, and caspase-3 with increasing glucose levels. Concurrently, the expression of EMT-related proteins, including N-cadherin, vimentin, ZEB1, and MMP9, increased. High-glucose cultured cells exhibited elevated levels of PI3K/AKT/mTOR pathway proteins. In the xenograft model, tumor cells stimulated by high glucose exhibited accelerated growth, larger tumor volumes, and heightened KI67 expression of immunohistochemistry. ELISA experiments revealed higher expression of IL-4 and IL-13 and lower expression of TNF-α and IL-5 in the serum of high-glucose-stimulated mice. The most favorable dose and time for tumor cells proliferation and migration is 20 mM, 48 h. High glucose fosters CRC cell proliferation and migration while suppressing autophagy through the activation of the PI3K/AKT/mTOR pathway.

The effect of SGLT2 inhibitors and GLP1 receptor agonists on arterial stiffness: A meta-analysis of randomized controlled trials

BackgroundPulse wave velocity (PWV) and augmentation index (AIx) are indices used to assess arterial stiffness. We evaluated the effect of sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP1-RA) on arterial stiffness indices. MethodsWe searched PubMed (up to January 2024) for RCTs assessing the effect of SGLT2i or GLP1-RA on arterial stiffness with reporting outcomes PWV and AIx. Effect sizes of the included studies were expressed as weighted mean difference (WMD) and 95 % confidence interval. Subgroup analyses were performed based on comparator (placebo vs. active comparator), design (RCT vs. crossover), population (diabetic vs. all) and blindness (yes vs. no). ResultsA total of 19 studies (SGLT2i, 12 studies; GLP1-RA, 5 studies; SGLT2i/GLP1-RA combination, 2 studies) assessing 1212 participants were included. We did not find any statistically significant association between GLP1-RA or SGLT2i and PWV or AIx. None of the subgroup analyses showed any statistically significant result. ConclusionNo evidence of a favorable change in arterial stiffness indices (PWV, AIx) was found following the administration of SGLT2i or GLP1-RA.

Regulatory Role of Fatty Acid Metabolism on Glucose-Induced Changes in Insulin and Glucagon Secretion by Pancreatic Islet Cells.

A detailed study of palmitate metabolism in pancreatic islets subject to different experimental conditions, like varying concentrations of glucose, as well as fed or starved conditions, has allowed us to explore the interaction between the two main plasma nutrients and its consequences on hormone secretion. Palmitate potentiates glucose-induced insulin secretion in a concentration-dependent manner, in a physiological range of both palmitate (0-2 mM) and glucose (6-20 mM) concentrations; at glucose concentrations lower than 6 mM, no metabolic interaction with palmitate was apparent. Starvation (48 h) increased islet palmitate oxidation two-fold, and the effect was resistant to its inhibition by glucose (6-20 mM). Consequently, labelled palmitate and glucose incorporation into complex lipids were strongly suppressed, as well as glucose-induced insulin secretion and its potentiation by palmitate. 2-bromostearate, a palmitate oxidation inhibitor, fully recovered the synthesis of complex lipids and insulin secretion. We concluded that palmitate potentiation of the insulin response to glucose is not attributable to its catabolic mitochondrial oxidation but to its anabolism to complex lipids: islet lipid biosynthesis is dependent on the uptake of plasma fatty acids and the supply of α-glycerol phosphate from glycolysis. Islet secretion of glucagon and somatostatin showed a similar dependence on palmitate anabolism as insulin. The possible mechanisms implicated in the metabolic coupling between glucose and palmitate were commented on. Moreover, possible mechanisms responsible for islet gluco- or lipotoxicity after a long-term stimulation of insulin secretion were also discussed. Our own data on the simultaneous stimulation of insulin, glucagon, and somatostatin by glucose, as well as their modification by 2-bromostearate in perifused rat islets, give support to the conclusion that increased FFA anabolism, rather than its mitochondrial oxidation, results in a potentiation of their stimulated release. Starvation, besides suppressing glucose stimulation of insulin secretion, also blocks the inhibitory effect of glucose on glucagon secretion: this suggests that glucagon inhibition might be an indirect or direct effect of insulin, but not of glucose. In summary, there seems to exist three mechanisms of glucagon secretion stimulation: 1. glucagon stimulation through the same secretion coupling mechanism as insulin, but in a different range of glucose concentrations (0 to 5 mM). 2. Direct or indirect inhibition by secreted insulin in response to glucose (5-20 mM). 3. Stimulation by increased FFA anabolism in glucose intolerance or diabetes in the context of hyperlipidemia, hyperglycemia, and hypo-insulinemia. These conclusions were discussed and compared with previous published data in the literature. Specially, we discussed the mechanism for inhibition of glucagon release by glucose, which was apparently contradictory with the secretion coupling mechanism of its stimulation.

ADAM10 as a major activator of reactive oxygen species production and klotho shedding in podocytes under diabetic conditions

Early stages of diabetes are characterized by elevations of insulin and glucose concentrations. Both factors stimulate reactive oxygen species (ROS) production, leading to impairments in podocyte function and disruption of the glomerular filtration barrier. Podocytes were recently shown to be an important source of αKlotho (αKL) expression. Low blood Klotho concentrations are also associated with an increase in albuminuria, especially in patients with diabetes. We investigated whether ADAM10, which is known to cleave αKL, is activated in glomeruli and podocytes under diabetic conditions and the potential mechanisms by which ADAM10 mediates ROS production and disturbances of the glomerular filtration barrier.In cultured human podocytes, high glucose increased ADAM10 expression, shedding, and activity, NADPH oxidase activity, ROS production, and albumin permeability. These effects of glucose were inhibited when cells were pretreated with an ADAM10 inhibitor or transfected with short-hairpin ADAM10 (shADAM10) or after the addition soluble Klotho. We also observed increases in ADAM10 activity, NOX4 expression, NADPH oxidase activity, and ROS production in αKL-depleted podocytes. This was accompanied by an increase in albumin permeability in shKL-expressing podocytes. The protein expression and activity of ADAM10 also increased in isolated glomeruli and urine samples from diabetic rats. Altogether, these results reveal a new mechanism by which hyperglycemia in diabetes increases albumin permeability through ADAM10 activation and an increase in oxidative stress via NOX4 enzyme activation. Moreover, αKlotho downregulates ADAM10 activity and supports redox balance, consequently protecting the slit diaphragm of podocyteσ under hyperglycemic conditions.

Effects of water and exogenous glucose on apple seedling growth and soil enzyme activity in semiarid area.

Soil water and organic carbon (C) are key factors affecting the growth and development of apple seedlings. The objective of the study was to investigate the effects of different soil moisture and glucose supplies on apple seedling growth and soil enzyme activities. We hypothesized that the growth of apple seedlings was affected by soil water and C content through their effects on root structure, plant physiological properties and soil enzymatic activities. A pot experiment consisting of nine treatments was set up, including three water treatments with soil moisture contents at 75-85% (normal irrigation, CK), 65-75% (light water stress, LS), and 55-65% (mild water stress, MS) of the soil field capacity, in combination with three glucose treatments with carbon/nitrogen (C/N) ratio of 7.5 (C1, no adding glucose), 10 (C2) and 15 (C3), respectively. Results showed that the LSC2 treatment significantly increased plant height by 7%, stem diameter by 5% and leaf area by 17%, as compared with LSC1. Also, LSC2 significantly increased root dry weight, root vitality and soil enzyme activities. Moreover, results of leaf photosynthetic, malondialdehyde (MDA), peroxidase (POD), superoxide dismutase (SOD) and proline contents also proved that adding glucose improved the drought resistance of plants. LSC2 treatment is more conducive to the growth of apple seedlings, and application of carbon has a good alleviation effect on plant water stress. The study demonstrated that addition of exogenous glucose alleviated light water deficiency, significantly affected root vitality, and promoted apple seedling growth. © 2024 Society of Chemical Industry.

Effects of sodium glucose co-transporter-2 inhibitor on atrial tachyarrhythmia burden in patients with cardiovascular implantable electronic device

Abstract Introduction Previous studies showed that sodium glucose co-transporter-2 inhibitors (SGLT2i) were associated with a lower atrial fibrillation (AF) incidence. Purpose Since mitochondrial dysfunction has been linked with AF, we aimed to examine the effects of SGLT2i on AF burden and mitochondrial function in patients with cardiovascular implantable electronic device (CIED). Methods Patients with CIED were randomly assigned to receive either dapagliflozin 10 mg daily or placebo for 3 months. The AF burden was measured as atrial high-rate episodes (AHRE) via CIED interrogations, and data were collected at baseline and 3-months post-treatment. Oxidative stress and mitochondrial function were determined in peripheral blood mononuclear cells (PBMCs). Results The study enrolled 54 CIED patients. There were 9 (16.7%) patients with diabetes mellitus and 36 (66.7%) patients with history of clinical AF. The changes of AHRE burden after 3-month treatments did not differ between dapagliflozin and placebo groups. However, in those with clinical AF, dapagliflozin significantly decreased the number of AHRE per month as compared to placebo (-2.2 vs. +0.6 episodes per month, p=0.048) (Table 1). Mitochondrial spare respiratory capacity (SRC) percentage was significantly increased after treatment with dapagliflozin (162.1% to 203.2%, p=0.003), whereas this was not found in the placebo group (Figure 1). In the subgroup analysis of patients with clinical AF, dapagliflozin showed significant improvement in both the SRC percentage (165.7 to 201.7%, p=0.016) and a reduction in cellular oxidative stress (26,840.5 to 18,164.0 arbitrary unit, p=0.049). Conclusions Dapagliflozin significantly reduced the number of AHRE per month in patients with history of clinical AF. The improvement in PBMC’s mitochondrial function and reduced cellular oxidative stress among dapagliflozin users could be the mechanisms responsible for its anti-atrial arrhythmic effect.Table 1Figure 1

#930 Elevated glucose in kidney organoids induces epithelial detachment driven by proinflammatory cytokines

Abstract Background and Aims Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease affecting 40% of diabetics. The pathogenesis of DKD is linked with inflammation, altered metabolism, and hemodynamic change but the relationship between these factors is not well understood. Proteinuria and albuminuria are common features, suggesting that impairments in the renal glomerular filtration barrier may be among the primary disease initiators. Limited DKD models are available, which has hampered our disease understanding and the ability to develop new therapies. Therefore, creating an in-vitro model that harbors multiple renal cell types organized in their natural complex arrangement becomes an attractive option to fill in this gap. Here, we conducted a systematic investigation of the effects of high glucose on kidney organoids, with the goal of understanding whether these cultures can reflect specific features relevant to DKD. Method To evaluate the effect of high glucose, kidney organoids were differentiated until maturation (day 21) in standard glucose and then switched for six days to concentrations of 5.5, 11, 33 and 100 mM. Then, to test the effect of proinflammatory cytokines on the injury phenotypes we switched organoids, at day 21, in control glucose condition (11 mM) ± TNFα or high glucose (33 mM) ± inhibitors (TNFα). Morphology was analysed via immunostaining, LDH and live/dead assay were used for toxicity, qPCR and western blotting to investigate differences in gene and protein expression, and mannose was used as an osmotic control. scRNA-seq of organoid in 11 vs 33 mM was conducted to gain insight into the molecular mechanism(s) contributing to the high glucose. Results Organoids remain well preserved in glucose up to 11 mM whereas organoids cultured in 33 and 100 mM showed a ∼30% reduction in overall organoid number between days 3 and 6. Moreover, in high glucose (33 and 100 mM), we observed an increase in the number of small, single PODXL+ cells surrounding the main organoid body, suggesting detachment from the podocyte clusters that normally form in organoids (Fig. A). To quantify it, we divided the total PODXL+ area into two sub-regions, classified as intact area and detached area, and calculated their ratio (Fig. B). Results indicated a 2-fold reduction of the intact vs detached area between 11 and 33 mM (p = 0.0011), suggesting that organoids undergo a spreading process under the influence of high glucose (Fig. C). Comparison of equimolar glucose vs mannose, live/dead and LDH assays identify a non-osmotic and non-apoptotic cause of the injury. ScRNA-seq analysis identified TNF-α as an upregulated pathway, which was confirmed with qPCR (p = 0.0131). Comparison of organoids at 11mM ± TNFα indicated that TNFα addition sensitizes podocytes to detachment at lower glucose levels, specifically, we identified a 4-fold reduction of the PODXL+ intact vs detached area at 11 mM ± TNFα (p &amp;lt; 0.0001), Fig. D. To further validate these findings and investigate possible therapeutic strategies, organoids were cultured with 33 mM glucose with TNF-α inhibitor and we identified a protective effect of the inhibitor which prevented the podocyte spreading phenotype at 33 mM glucose (Fig. E). Conclusion Our experiments identify an injury phenotype under high glucose concentrations, in kidney organoids, characterized by podocyte detachment from the main organoid body. Moreover, no osmotic or toxicity effect was observed. Importantly, this phenotype resembles disease features identified in diabetic patients, where podocyte loss and detachment from the glomerular basement membrane is associated with pathophysiology. We identified a correlation between the injury phenotype, characterized by epithelial detachment, and proinflammatory cytokine upregulation, which is driven by high glucose, and we have shown it can be targeted therapeutically. Therefore, this new experimental model in-vitro offers up new insights into the pathophysiology of diabetes and its complications, and represents a new platform to screen for therapeutics.

Effects of Five Dietary Carbohydrate Sources on Growth, Glucose Metabolism, Antioxidant Capacity and Immunity of Largemouth Bass (Micropterus salmoides).

This study investigated the effects of glucose (GLU), tapioca starch (TS), gelatinized tapioca starch (GTS), potato starch (PS) and gelatinized potato starch (GPS) on growth and physiological responses in juvenile largemouth bass Micropterus salmoides. After 8 weeks, fish fed with starch diets had better weight gain and growth rates. Counts of red blood cells and monocytes were increased in the PS and GPS groups, compared to GLU group. Contents of serum triglyceride and total cholesterol were markedly elevated in the TS, PS and GPS groups. There were lower levels of serum glucose, insulin and cholecystokinin, and higher agouti-related peptide contents in the PS group compared to GLU group. PS and GPS could enhance glycolysis and TCA cycle by increasing their enzyme activities and transcriptional levels. Additionally, starch sources markedly heightened mRNA levels of key genes involved in the respiratory electron transport chain. Additionally, elevated mRNA levels of key antioxidant genes were shown in the TS and GTS groups. Moreover, TS and PS could promote immunity by upregulating transcriptional levels of the complement system, lysozyme and hepcidin. Taken together, starch exhibited better growth via increasing glycolysis and TCA cycle compared with GLU, and PS could improve antioxidant and immune capacities in largemouth bass.

Short- and long-term exposure to high glucose induces unique transcriptional changes in osteoblasts in vitro.

Bone is increasingly recognized as a target for diabetic complications. In order to evaluate the direct effects of high glucose on bone, we investigated the global transcriptional changes induced by hyperglycemia in osteoblasts in vitro. Rat bone marrow-derived mesenchymal stromal cells were differentiated into osteoblasts for 10days, and prior to analysis, they were exposed to hyperglycemia (25 mM) for the short-term (1 or 3days) or long-term (10 days). Genes and pathways regulated by hyperglycemia were identified using mRNA sequencing and verified with qPCR. Genes upregulated by 1-day hyperglycemia were, for example, related to extracellular matrix organization, collagen synthesis and bone formation. This stimulatory effect was attenuated by 3days. Long-term exposure impaired osteoblast viability, and downregulated, for example, extracellular matrix organization and lysosomal pathways, and increased intracellular oxidative stress. Interestingly, transcriptional changes by different exposure times were mostly unique and only 89 common genes responding to glucose were identified. In conclusion, short-term hyperglycemia had a stimulatory effect on osteoblasts and bone formation, whereas long-term hyperglycemia had a negative effect on intracellular redox balance, osteoblast viability and function.