Microarray Analysis Identifies Key Differentially Expressed Circular RNAs in Aged Mice With Postoperative Cognitive Dysfunction

The role of epigenetic modification in postoperative cognitive dysfunction

With the ageing of the population, the health problems of elderly individuals have become particularly important. Through a large number of clinical studies and trials, it has been confirmed that elderly patients can experience postoperative cognitive dysfunction after general anesthesia/surgery. However, the mechanism of postoperative cognitive dysfunction is still unknown. In recent years, the role of epigenetics in postoperative cognitive dysfunction has been widely studied and reported. Epigenetics includes the genetic structure and biochemical changes of chromatin not involving changes in the DNA sequence. This article summarizes the epigenetic mechanism of cognitive impairment after general anesthesia/surgery and analyses the broad prospects of epigenetics as a therapeutic target for postoperative cognitive dysfunction.

Comprehensive analysis of the coding and non-coding RNA transcriptome expression profiles of hippocampus tissue in tx-J animal model of Wilson's disease

Wilson's disease (WD) is an autosomal recessive disorder with a genetic basis. The predominant non-motor symptom of WD is cognitive dysfunction, although the specific genetic regulatory mechanism remains unclear. Tx-J mice, with an 82% sequence homology of the ATP7B gene to the human gene, are considered the most suitable model for WD. This study employs deep sequencing to investigate the differences in RNA transcript profiles, both coding and non-coding, as well as the functional characteristics of the regulatory network involved in WD cognitive impairment. The cognitive function of tx-J mice was evaluated using the Water Maze Test (WMT). Long non-coding RNA (lncRNA), circular RNA (circRNA), and messenger RNA (mRNA) profiles were analyzed in the hippocampal tissue of tx-J mice to identify differentially expressed RNAs (DE-RNAs). Subsequently, the DE-RNAs were used to construct protein-protein interaction (PPI) networks, as well as DE-circRNAs and lncRNAs-associated competing endogenous RNA (ceRNA) expression networks, and coding-noncoding co-expression (CNC) networks. To elucidate their biological functions and pathways, the PPI and ceRNA networks were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. A total of 361 differentially expressed mRNAs (DE-mRNAs), comprising 193 up-regulated and 168 down-regulated mRNAs, 2627 differentially expressed long non-coding RNAs (DE-lncRNAs), consisting of 1270 up-regulated and 1357 down-regulated lncRNAs, and 99 differentially expressed circular RNAs (DE-circRNAs), consisting of 68 up-regulated and 31 down-regulated circRNAs, were observed in the tx-J mice group when compared to the control mice group. Gene Ontology (GO) and pathway analyses revealed that DE-mRNAs were enriched in cellular processes, calcium signaling pathways, and mRNA surveillance pathways. In contrast, the DE-circRNAs-associated competing endogenous RNA (ceRNA) network was enriched for covalent chromatin modification, histone modification, and axon guidance, whereas the DE-lncRNAs-associated ceRNA network was enriched for dendritic spine, regulation of cell morphogenesis involved in differentiation, and mRNA surveillance pathway. The study presented the expression profiles of lncRNA, circRNA, and mRNA in the hippocampal tissue of tx-J mice. Furthermore, the study constructed PPI, ceRNA, and CNC expression networks. The findings are significant in comprehending the function of regulatory genes in WD associated with cognitive impairment. These results also offer valuable information for the diagnosis and treatment of WD.

Construction and analysis of circular RNA-associated competing endogenous RNA network in the hippocampus of aged mice for the occurrence of postoperative cognitive dysfunction

Circular RNAs are highly stable single-stranded circular RNAs and enriched in the brain. Previous studies showed that circRNAs, as part of competing endogenous RNAs (ceRNAs) network, play an important role in neurodegenerative and psychiatric diseases. However, the mechanism of circRNA-related ceRNA networks in postoperative cognitive dysfunction (POCD) has not been elucidated yet. POCD usually occurs in elderly patients and is characterized by hippocampal dysfunction. Here, aged C57BL/6 mice were subjected to exploratory laparotomy under sevoflurane anesthesia, and this POCD model was verified by Morris water maze test. Whole-transcriptome sequencing was performed on the hippocampus of control group (Con) and surgery group. One hundred and seventy-seven DEcircRNAs, 221 DEmiRNAs and 2,052 DEmRNAs were identified between two groups. A ceRNA network was established with 92 DEcircRNAs having binding sites with 76 DEmiRNAs and 549 target DEmRNAs. In functional enrichment analysis, a pathological pattern of POCD was highlighted in the ceRNA network: Abnormal metabolic process in neural cells, including oxygen metabolism, could promote apoptosis and then affect the synaptic function, which may undermine the neural plasticity and eventually lead to changes in cognitive function and other behavioral patterns. In conclusion, this specific ceRNA network of circRNAs–miRNAs–mRNAs has provided novel insights into the regulatory mechanisms of POCD and revealed potential therapeutic gene targets.

Research progress on perioperative blood-brain barrier damage and its potential mechanism

The blood-brain barrier (BBB) is an important barrier separating the central nervous system from the periphery. The composition includes endothelial cells, pericytes, astrocytes, synapses and tight junction proteins. During the perioperative period, anesthesia and surgical operations are also a kind of stress to the body, which may be accompanied by blood-brain barrier damage and brain metabolism dysfunction. Perioperative blood-brain barrier destruction is closely associated with cognitive impairment and may increase the risk of postoperative mortality, which is not conducive to enhanced recovery after surgery. However, the potential pathophysiological process and specific mechanism of blood-brain barrier damage during the perioperative period have not been fully elucidated. Changes in blood-brain barrier permeability, inflammation and neuroinflammation, oxidative stress, ferroptosis, and intestinal dysbiosis may be involved in blood-brain barrier damage. We aim to review the research progress of perioperative blood-brain barrier damage and its potential adverse effects and potential molecular mechanisms, and provide ideas for the study of homeostasis maintenance of brain function and precision anesthesia.

Hippocampal gene expression patterns in Sevoflurane anesthesia associated neurocognitive disorders: A bioinformatic analysis

Background

Several studies indicate general anesthetics can produce lasting effects on cognitive function. The commonly utilized anesthetic agent Sevoflurane has been implicated in neurodegenerative processes. The present study aimed to identify molecular underpinnings of Sevoflurane anesthesia linked neurocognitive changes by leveraging publically available datasets for bioinformatics analysis.

Methods

A Sevoflurane anesthesia related gene expression dataset was obtained. Sevoflurane related genes were obtained from the CTD database. Neurocognitive disorders (NCD) related genes were downloaded from DisGeNET and CTD. Intersecting differentially expressed genes between Sevoflurane and NCD were identified as cross-talk genes. A protein-protein interaction (PPI) network was constructed. Hub genes were selected using LASSO regression. Single sample gene set enrichment analysis; functional network analysis, pathway correlations, composite network analysis and drug sensitivity analysis were performed.

Results

Fourteen intersecting cross-talk genes potentially were identified. These were mainly involved in biological processes including peptidyl-serine phosphorylation, cellular response to starvation, and response to gamma radiation, regulation of p53 signaling pathway, AGE-RAGE signaling pathway and FoxO signaling. Egr1 showed a central role in the PPI network. Cdkn1a, Egr1, Gadd45a, Slc2a1, and Slc3a2 were identified as important or hub cross-talk genes. Among the interacting pathways, Interleukin-10 signaling and NF-kappa B signaling enriched among Sevoflurane-related DEGs were highly correlated with HIF-1 signaling enriched in NCD-related genes. Composite network analysis showed Egr1 interacted with AGE-RAGE signaling and Apelin signaling pathways, Cdkn1a, and Gadd45a. Cdkn1a was implicated in in FoxO signaling, PI3K-Akt signaling, ErbB signaling, and Oxytocin signaling pathways, and Gadd45a. Gadd45a was involved in NF-kappa B signaling and FoxO signaling pathways. Drug sensitivity analysis showed Egr1 was highly sensitive to GENIPIN.

Conclusion

A suite of bioinformatics analysis revealed several key candidate hippocampal genes and associated functional signaling pathways that could underlie Sevoflurane associated neurodegenerative processes.

Identification of circRNA-miRNA-mRNA networks to explore the molecular mechanism and immune regulation of postoperative neurocognitive disorder

Postoperative neurocognitive disorder (PND) is a common complication in older patients. However, its pathogenesis has still remained elusive. Recent studies have shown that circular RNA (circRNA) plays an important role in the development of neurodegenerative diseases, such as PND after surgery. CircRNA, as a competitive endogenous RNA (ceRNA), mainly acts as a molecular sponge for miRNA to "adsorb" microRNA (miRNA) and to reduce the inhibitory effects of miRNAs on target mRNA. The sequencing data of circRNA were obtained from the Gene Expression Omnibus (GEO) database. By bioinformatic methods, circAtlas, miRDB, miRTarBase and miRwalk databases were applied to construct circRNA-miRNA-mRNA networks and screen differentially expressed mRNAs. To improve the accuracy of the data, we randomly divided aging mice into control (non-PND group) and PND groups, and used high-throughput sequencing to analyze their brain hippocampal tissue for analysis. Three key genes were cross-detected in the data of both groups, which were Unc13c, Tbx20 and St8sia2 (as hub genes), providing new targets for PND treatment. According to the results of the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, immune cell infiltration analysis, gene set enrichment analysis (GSEA), Connectivity Map (CMap) analysis, quantitative real-time polymerase chain reaction (qRT-PCR), the genes that were not related to the central nervous system were removed, and finally, mmu_circ_0000331/miR-1224-3p/Unc13c and mmu_circ_0000406/miR-24-3p/St8sia2 ceRNA networks were identified. In addition, the CMap method was used to select the top 4 active compounds with the largest negative correlation absolute values, including cimaterol, Rucaparib, FG-7142, and Hydrocortisone.

Decoding competitive endogenous RNA regulatory network in postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a common postoperative neurological complication in elderly patients. Circular RNAs (circRNAs) are abundant in the mammalian brain and can probably regulate cognitive function. However, the competitive endogenous RNA (ceRNA) regulatory network in POCD remains illiterate. Transcriptomic signatures in the hippocampus of POCD mice derived from the Gene Expression Omnibus (GEO) dataset GSE190880, GSE95070, and GSE115440 were used to identify the circRNA, miRNA, and mRNA expression profiles of POCD mice compared with controls, respectively. A set of differentially expressed RNAs, including 119 circRNAs, 33 miRNAs, and 49 mRNAs were identified. Transcript validation showed the enhanced expression of circ_0001634, circ_0001345, and circ_0001493. A ceRNA regulatory network composed of three circRNAs, three miRNAs, and six mRNAs was established. The hub mRNAs in the ceRNA network were further found to be involved in the hormone catabolic process and regulation of canonical Wnt signaling pathway, revealing their crucial role in POCD. Finally, three miRNAs and four mRNAs were verified by qRT-PCR. These results based on bioinformatics and PCR array suggest that circ_0001634/miR-490-5p/Rbm47, circ_0001634/miR-490-5p/Sostdc1, circ_0001634/miR-7001-5p/Sostdc1, circ_0001345/miR-7001-5p/Sostdc1, and circ_0001493/miR-7001-5p/Sostdc1 may be novel diagnostic biomarkers and therapeutic targets for POCD.

Identification of Potential Key circRNAs in Aged Mice With Postoperative Delirium

Postoperative delirium (POD) is a common postoperative complication in elderly patients and seriously affects postoperative recovery. The exact mechanism of POD is still unclear. Therefore, it is necessary to explore the mechanism of POD in transcriptional regulation. At present, circRNAs have been proven to play an important role in a variety of mental health and cognitive disorders, such as Alzheimer’s disease, depression and schizophrenia. To reveal the effect of circRNA on POD, we used microarray to analyze the differential expression profiles of circRNAs in the hippocampus of 12-month-old mice between the tibial fracture and control groups. A total of 1,4236 circRNAs were identified. Compared with the control group, there were 500 circRNAs with increased expression and 187 with decreased expression. The accuracy of the microarray data was further verified by qRT–PCR. Finally, GO enrichment and KEGG pathway analyses indicated that changes in axon orientation, ubiquitin-mediated proteolysis, glutamate synapses, the estrogen signaling pathway, the RAS signaling pathway and other systems may be important potential pathological mechanisms in the progression of POD. In particular, we found that the HOMER1 gene and its transcript mmu_circRNA_26701 are specifically expressed in the glutamate synapse, which may provide new clues and intervention targets for the progression of this refractory disease.

Novel implications of a strictly monomorphic (GCC) repeat in the human PRKACB gene

PRKACB (Protein Kinase CAMP-Activated Catalytic Subunit Beta) is predominantly expressed in the brain, and regulation of this gene links to neuroprotective effects against tau and Aβ-induced toxicity. Here we studied a (GCC)-repeat spanning the core promoter and 5′ UTR of this gene in 300 human subjects, consisting of late-onset neurocognitive disorder (NCD) (N = 150) and controls (N = 150). We also implemented several models to study the impact of this repeat on the three-dimensional (3D) structure of DNA. While the PRKACB (GCC)-repeat was strictly monomorphic at 7-repeats, we detected two 7/8 genotypes only in the NCD group. In all examined models, the (GCC)7 and its periodicals had the least range of divergence variation on the 3D structure of DNA in comparison to the 8-repeat periodicals and several hypothetical repeat lengths. A similar inert effect on the 3D structure was not detected in other classes of short tandem repeats (STRs) such as GA and CA repeats. In conclusion, we report monomorphism of a long (GCC)-repeat in the PRKACB gene in human, its inert effect on DNA structure, and enriched divergence in late-onset NCD. This is the first indication of natural selection for a monomorphic (GCC)-repeat, which probably evolved to function as an “epigenetic knob”, without changing the regional DNA structure.