Advanced Glycosylation End Products Induced Synaptic Deficits and Cognitive Decline Through ROS-JNK-p53/miR-34c/SYT1 Axis in Diabetic Encephalopathy

Exploring the effect and mechanism of action of Jinlida granules (JLD) in the treatment of diabetes-associated cognitive impairment based on network pharmacology with experimental validation

OBJECTIVES

To explore the effect and the probable mechanisms of JLD in the treatment of type 2 diabetes mellitus (T2DM) - associated cognitive impairment (TDACI).

METHODS

The effect of JLD in combating TDACI was assessed in T2DM model mice by conducting Morris water maze (MWM) behaviour testing. Active components and their putative targets, as well as TDACI-related targets, were collected from public databases. Protein-protein interactions (PPIs), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses and molecular docking were then utilized to explore potential molecular network mechanisms. Finally, the main targets were verified in animal model experiments.

RESULTS

MWM test showed that JLD improved aspects of behaviour in T2DM model mice. JLD improved glucose intolerance, tissue insulin sensitivity, lipid metabolism and enhanced synapse-associated protein expression in hippocampus tissue. Network pharmacology revealed 185 active components, 337 targets of JLD, and 7998 TDACI related targets were obtained . PPI network analyses revealed 39 core targets. GO and KEGG analyses suggested that JLD might improve TDACI by regulating gene expression, apoptotic processes and inflammatory responses mainly via PI3K-AKT and AGE-RAGE signaling pathways. Molecular docking revealed strong binding of the main components to core targets. JLD reduced hippocampus tissue expression of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL6), core targets of treatment of TDACI.

CONCLUSIONS

The findings suggested that JLD has the potential to improve TDACI through multiple components, multiple targets and multiple pathways. JLD may be a promising treatment for diabetic cognitive impairment.

Dietary modulation of microRNAs in insulin resistance and type 2 diabetes

The prevalence of type 2 diabetes is increasing worldwide. Various molecular mechanisms have been proposed to interfere with the insulin signaling pathway. Recent advances in proteomics and genomics indicate that one such mechanism involves the post-transcriptional regulation of insulin signaling by microRNA (miRNA). These noncoding RNAs typically induce messenger RNA (mRNA) degradation or translational repression by interacting with the 3' untranslated region (3'UTR) of target mRNA. Dietary components and patterns, which can either enhance or impair the insulin signaling pathway, have been found to regulate miRNA expression in both in vitro and in vivo studies. This review provides an overview of the current knowledge of how dietary components influence the expression of miRNAs related to the control of the insulin signaling pathway and discusses the potential application of these findings in precision nutrition.

Identification of common biomarkers in diabetic kidney disease and cognitive dysfunction using machine learning algorithms

Cognitive dysfunction caused by diabetes has become a serious global medical issue. Diabetic kidney disease (DKD) exacerbates cognitive dysfunction in patients, although the precise mechanism behind this remains unclear. Here, we conducted an investigation using RNA sequencing data from the Gene Expression Omnibus (GEO) database. We analyzed the differentially expressed genes in DKD and three types of neurons in the temporal cortex (TC) of diabetic patients with cognitive dysfunction. Through our analysis, we identified a total of 133 differentially expressed genes (DEGs) shared between DKD and TC neurons (62 up-regulated and 71 down-regulated). To identify potential common biomarkers, we employed machine learning algorithms (LASSO and SVM-RFE) and Venn diagram analysis. Ultimately, we identified 8 overlapping marker genes (ZNF564, VPS11, YPEL4, VWA5B1, A2ML1, KRT6A, SEC14L1P1, SH3RF1) as potential biomarkers, which exhibited high sensitivity and specificity in ROC curve analysis. Functional analysis using Gene Ontology (GO) revealed that these genes were primarily enriched in autophagy, ubiquitin/ubiquitin-like protein ligase activity, MAP-kinase scaffold activity, and syntaxin binding. Further enrichment analysis using Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) indicates that these biomarkers may play a crucial role in the development of cognitive dysfunction and diabetic nephropathy. Building upon these biomarkers, we developed a diagnostic model with a reliable predictive ability for DKD complicated by cognitive dysfunction. To validate the 8 biomarkers, we conducted RT-PCR analysis in the cortex, hippocampus and kidney of animal models. The results demonstrated the up-regulation of SH3RF1 in the cortex, hippocampus and kidney of mice, which was further confirmed by immunofluorescence and Western blot validation. Notably, SH3RF1 is a scaffold protein involved in cell survival in the JNK signaling pathway. Based on these findings, we support that SH3RF1 may be a common gene expression feature that influences DKD and cognitive dysfunction through the apoptotic pathway.

Cinnamaldehyde protects SH-SY5Y cells against advanced glycation end-products induced ectopic cell cycle re-entry

Accumulation of advanced glycation end-products (AGEs) in the brain contributes significantly to cognitive impairment in patients with diabetes by disrupting the post-mitotic state of neuronal cells, thereby triggering ectopic cell cycle re-entry (CCR) and subsequent neuronal apoptosis. Cinnamaldehyde (CINA), a potential mitigator of cognitive impairment due to its blood glucose-lowering properties, warrants exploration for its role in counteracting diabetes-related neurological damage. In this study, we examined the neuroprotective effect of CINA on AGE-damaged SH-SY5Y human neuroblastoma cells differentiated in vitro. We investigated the impact of CINA on AGE-induced neuronal CCR and apoptosis, finding that it substantially suppressed aberrant DNA replication, precluded cells from entering the mitotic preparatory phase, and diminished apoptosis. Additionally, CINA inhibited the expression of eIF4E without altering S6K1 phosphorylation. These findings indicate that CINA safeguards neuronal cells from AGE-related damage by preventing abnormal CCR, preserving the post-mitotic state of neuronal cells, and reducing AGE-induced apoptosis, potentially through the inhibition of eIF4E-controlled cell proliferation. Our results highlight the prospective utility of CINA in managing diabetic neuropathy.

Exploration of Polysaccharides from Phyllanthus emblica: Isolation, Identification, and Evaluation of Antioxidant and Anti-Glycolipid Metabolism Disorder Activities

Phyllanthus emblica is a natural medicinal herb with diverse bioactivities. Certain extracts from this herb have been confirmed to possess anti-glycolipid metabolic disorder activity. To further develop its utility value and explore its potential in combating glycolipid metabolic disorders, we designed a series of experiments to investigate the structure, antioxidant activity, and anti-glycolipid metabolic disorder activity of Phyllanthus emblica polysaccharides. In this study, we extracted and purified polysaccharides from Phyllanthus emblica and thoroughly analyzed their structure using various techniques, including NMR, methylation analysis, and surface-enhanced Raman spectroscopy. We investigated the hypolipidemic and anti-glycolipid metabolism disorder activity of Phyllanthus emblica polysaccharides for the first time utilizing oleic acid (OA) and advanced glycation end products (AGEs) as inducers. Additionally, the antioxidant activity of Phyllanthus emblica polysaccharides was assessed in vitro. These findings lay the groundwork for future investigations into the potential application of Phyllanthus emblica polysaccharides as an intervention for preventing and treating diabetes.

Metabolic memory: mechanisms and diseases

Metabolic diseases and their complications impose health and economic burdens worldwide. Evidence from past experimental studies and clinical trials suggests our body may have the ability to remember the past metabolic environment, such as hyperglycemia or hyperlipidemia, thus leading to chronic inflammatory disorders and other diseases even after the elimination of these metabolic environments. The long-term effects of that aberrant metabolism on the body have been summarized as metabolic memory and are found to assume a crucial role in states of health and disease. Multiple molecular mechanisms collectively participate in metabolic memory management, resulting in different cellular alterations as well as tissue and organ dysfunctions, culminating in disease progression and even affecting offspring. The elucidation and expansion of the concept of metabolic memory provides more comprehensive insight into pathogenic mechanisms underlying metabolic diseases and complications and promises to be a new target in disease detection and management. Here, we retrace the history of relevant research on metabolic memory and summarize its salient characteristics. We provide a detailed discussion of the mechanisms by which metabolic memory may be involved in disease development at molecular, cellular, and organ levels, with emphasis on the impact of epigenetic modulations. Finally, we present some of the pivotal findings arguing in favor of targeting metabolic memory to develop therapeutic strategies for metabolic diseases and provide the latest reflections on the consequences of metabolic memory as well as their implications for human health and diseases.

Exposure to fluoride exacerbates the cognitive deficit of diabetic patients living in areas with endemic fluorosis, as well as of rats with type 2 diabetes induced by streptozotocin via a mechanism that may involve excessive activation of the poly(ADP ribose) polymerase-1/P53 pathway

Epidemiology has shown that fluoride exposure is associated with the occurrence of diabetes. However, whether fluoride affects diabetic encephalopathy is unclear. Elderly diabetic patients in areas with endemic (n = 169) or no fluorosis (108) and controls (85) underwent Montreal Cognitive Assessment. Sprague-Dawley rats receiving streptozotocin and/or different fluoride doses were examined for spatial learning and memory, brain morphology, blood-brain barrier, fasting blood glucose and insulin. Cultured SH-SY5Y cells were treated with 50 mM glucose and/or low- or high-dose fluoride, and P53-knockdown or poly-ADP-ribose polymerase-1 (PARP-1) inhibition. The levels of PARP-1, P53, poly-ADP-ribose (PAR), apoptosis-inducing factor (AIF), and phosphorylated-histone H2A.X (ser139) were measured by Western blotting. Reactive oxygen species (ROS), 8-hydroxydeguanosine (8-OHdG), PARP-1 activity, acetyl-P53, nicotinamide adenine dinucleotide (NAD+), activities of mitochondrial hexokinase1 (HK1) and citrate synthase (CS), mitochondrial membrane potential and apoptosis were assessed biochemically. Cognition of diabetic patients in endemic fluorosis areas was poorer than in other regions. In diabetic rats, fasting blood glucose, insulin resistance and blood-brain barrier permeability were elevated, while spatial learning and memory and Nissl body numbers in neurons declined. In these animals, expression and activity of P53 and PARP-1 and levels of NAD+, PAR, ROS, 8-OHdG, p-histone H2A.X (ser139), AIF and apoptosis content increased; whereas mitochondrial HK1 and CS activities and membrane potential decreased. SH-SY5Y cells exposed to glucose exhibited changes identical to diabetic rats. The changes in diabetic rats and cells treated with glucose were aggravated by fluoride. P53-knockout or PARP-1 inhibition mitigated the effects of glucose with/without low-dose fluoride. Elevation of diabetic encephalopathy was induced by exposure to fluoride and the underlying mechanism may involve overactivation of the PARP-1/P53 pathway.

Early life stress enhances the susceptibility to depression and interferes with neuroplasticity in the hippocampus of adolescent mice via regulating miR-34c-5p/SYT1 axis

Early life events are major risk factors for the onset of depression and have long-term effects on the neurobiological changes and behavioral development of rodents. However, little is known about the specific mechanisms of early life adversity in the susceptibility to subsequent stress exposure in adolescence. This study characterized the effect of maternal separation (MS), an animal model of early life adversity, on the behavioral responses to restraint stress in mice during adolescence and investigated the molecular mechanism underlying behavioral vulnerability to chronic stress induced by MS. Our results showed that MS exposure could further reinforce the depressive vulnerability to restraint stress in adolescent mice. In addition, miR-34c-5p expression was obviously up-regulated in the hippocampi of MS mice at postnatal day (P) 14 and P42. Further, synaptotagmin-1 (SYT1) was deemed as a target gene candidate of miR-34c-5p on the basis of dual luciferase assay. It was found that the downregulation of miR-34c-5p expression in the hippocampi of MS mice could ameliorate dysfunction of synaptic plasticity by targeting molecule SYT1, effects which were accompanied by alleviation of depressive and anxious behaviors in these mice. The results demonstrated that the miR-34c-5p/SYT1 pathway was involved in the susceptibility to depression induced by MS via regulating neuroplasticity in the hippocampi of mice.

Depletion of PIEZO1 expression is accompanied by upregulating p53 signaling in mice with perioperative neurocognitive disorder

As the common complications observed in surgical elder patients, perioperative neurocognitive disorders (PND) cause a series of serious perioperative health problems. However, there are no effective treatments, and the exact mechanisms are still largely unknown. In this study, transcriptome sequencing was performed to investigate the differentially expressed genes (DEGs) in the hippocampus of C57BL/6J aged mice with or without PND. Compared with the Mock group, the expression of 352, 395, and 772 genes changed significantly in the PND group at days 1, 7, and 21 after surgery, respectively. Gene ontology (GO) and gene set enrichment analysis (GSEA) showed that DEGs were mainly associated with p53 signaling. Moreover, GSEA revealed potentially p53-related DEGs such as leucine-rich repeat serine/threonine-protein kinase 1 (LRRK1), monooxygenase DBH-like 1 (MOXD1), and piezo type mechanosensitive ion channel component 1 (PIEZO1). Furthermore, we confirmed the decreased interaction of PIEZO1 with p53 in PND, and upregulation of PIEZO1 resulted in a decrease in p53 protein levels through increased ubiquitination of p53. In conclusion, this study contributes to the knowledge of global changes in gene expression and mechanisms during PND.

Research Progress on Lipocalin-2 in Diabetic Encephalopathy

Diabetic encephalopathy is a central nervous complication of diabetes mellitus which is characterized by cognitive impairment and structural and neurochemical abnormalities, which is easily neglected. Lipocalin-2 (LCN2) is a 25 kDa transporter in the lipocalin family that can transport small molecules, including fatty acids, iron, steroids, and lipopolysaccharides in the circulation. Recently, LCN2 has been found to be a significant regulator of insulin resistance and glucose homeostasis. Numerous studies have shown that LCN2 is connected to central nervous system abnormalities, including neuroinflammation and neurodegeneration, while the latest researches have found that LCN2 is closely related to the development of diabetic encephalopathy. Nevertheless, its precise role in the pathogenesis of diabetic encephalopathy remains to be determined. In this paper, we review recent evidence on the role of LCN2 in diabetic encephalopathy from multiple perspectives in order to decipher the impact of LCN2 in both the aetiology and treatment of diabetic encephalopathy.