Mechanism underlying circularRNA_014301-mediated regulation of neuronal cell inflammation and apoptosis

In-depth analyses of lncRNA and circRNA expression in the hippocampus of LPS-induced AD mice by Byu d Mar 25

Byu d Mar 25 (BM25) has been verified to have neuroprotective effects in Alzheimer's disease (AD) mice. However, the molecular mechanism remains unclear. We aimed to investigate the expression profiling of lncRNAs and circRNAs by microarray analysis. Six hippocampus from LPS-mediated AD mice model treated with (normal saline (NS) (n = 3) and AD mice model treated with BM25 (n = 3) were selected. Microarray analysis was performed to detect the expression profiles of lncRNAs and circRNAs in hippocampus. Differentially expressed (DE) lncRNAs, mRNAs and circRNAs were identified through scatter plot and volcano plot filtering with a threshold of fold-change ≥2 and P  ≤ 0.05. Co-expression network is analyzed by Circos software. Cis - and Trans - regulation were analyzed using RIsearch-2.0 and FEELNC softwares. LncRNA-transcription factors (TFs) and LncRNA-Target-TFs network were analyzed by Clusterprofiler software. The prediction of miRNAs bind to circRNAs were performed with miRNAbase. A total of 113 DElncRNAs, 117 DEmRNAs, and 4 DEcircRNAs were detected. The pathway analysis showed the mRNAs that correlated with lncRNAs were involved in apoptosis, inflammatory mediator regulation of TRP channels, NF-kappa B and PI3K-Akt signaling pathway. The lncRNA-TFs network analysis suggested the lncRNAs were mostly regulated by Ncoa1, Phf5a, Klf6, Lmx1b, and Pax3. Additionally, lncRNA-target-TFs network analysis indicated the GATA6, Junb, Smad1, Twist1, and Mafb mostly regulate the same lncRNAs: XR_001783430.1 and NR_051982.1. Furthermore, 480 miRNAs were predicted binding to 4 identified circRNAs. The BM25 may affect AD by regulating the expression of lncRNAs and circRNAs, which could regulate the expressions of mRNAs or miRNAs by LncRNA-Target-TFs network.

Circular RNAs and inflammation: Epigenetic regulators with diagnostic role

Circular RNAs (circRNAs) are a group of transcripts generally known to be non-coding transcripts, but occasionally producing short peptides. Circ_Ttc3/miR-148a, circ_TLK1/miR-106a-5p, circ_VMA21/miR-9-3p, circ_0068,888/miR-21-5p, circ_VMA21/miR-199a-5p, circ_AFF2/miR-375, circ_0008360/miR-135b-5p and circ-FBXW7/miR-216a-3p are examples of circRNA/miRNA pairs that contribute in the pathogenesis of immune-related conditions. CircRNAs have been found to regulate function of immune system and participate in the pathophysiology of immune-related disorders. In the current study, we searched PubMed and Google Scholar databases until July 2022 with the key words "circRNA" OR "circular RNA" AND "inflammation". Then, we assessed the abstract of retrieved articles to include original articles that assessed contribution of circRNAs in the pathoetiology of inflammation and related disorders. Finally, we went through the main texts of the articles and tabulated the available information. Therefore, the current study summarizes the role of circRNAs in the pathoetiology of sepsis, atherosclerosis, rheumatoid arthritis and osteoarthritis, immune-related cardiovascular, pulmonary, gastrointestinal and nervous system disorders.

Astaxanthin attenuates cognitive deficits in Alzheimer's disease models by reducing oxidative stress via the SIRT1/PGC-1α signaling pathway

OBJECTIVE

Oxidative stress plays a pivotal role in neurodegenerative diseases. Astaxanthin (AST) can play a neuroprotective role owing to its long-chain conjugated unsaturated double bond, which imparts potent antioxidant, anti-neuroinflammatory, and anti-apoptotic properties. However, the biological mechanisms underlying these effects remain unknown. Therefore, this study aimed to investigate and validate the protective effect of AST on neuronal senescence and apoptosis caused by oxidative stress induced by Aβ25-35 peptide, with the goal of preventing the onset of cognitive dysfunction.

METHODS

Alzheimer's disease models comprising ICR mice and PC12 cells were established using Aβ25-35. The Morris water maze test was used to assess mouse behavior. Nissl staining revealed morphological changes in the mouse hippocampal neurons. To elucidate the mechanism of action of AST, ICR mice and PC12 cells were treated with the silent information regulator 1 (SIRT1) inhibitor nicotinamide (NAM). Additionally, immunofluorescence, western blotting, and reverse transcription polymerase chain reaction were used to evaluate changes in the expression of Bcl-2 and Bax in the mouse hippocampus, and SIRT1/PGC-1α signaling pathway proteins were detected. Moreover, the oxidative stress markers in ICR mice and PC12 cells were evaluated. Further, CCK-8 assays, Annexin V/PI double staining, and β-galactosidase activity assays were performed in PC12 cells to evaluate the anti-senescence and apoptotic effects of AST.

RESULTS

In vivo experiments showed that Aβ25-35 impaired cognitive function, promoted morphological changes in hippocampal neurons, decreased Bcl-2 expression, increased Bax expression, decreased superoxide dismutase and GSH-px levels, and increased reactive oxygen species and malondialdehyde levels. Conversely, AST alleviated the impact of Aβ25-35 in mice, with reversed outcomes. NAM administration reduced SIRT1 and PGC-1α expression in the hippocampus. This decrease was accompanied by cognitive dysfunction and hippocampal neuron atrophy, which were also evident in the mice. Additionally, in vitro experiments showed that Aβ25-35 could promote oxidative stress and induce the senescence and apoptosis of PC12 cells. Nonetheless, AST treatment counteracted this effect by inhibiting oxidative stress and altering the state of PC12 cells. Notably, the Aβ + NAM group exhibited the most significant rates of senescence and apoptosis in PC12 cells following NAM treatment.

CONCLUSION

AST can improve cellular senescence and apoptosis mediated by oxidative stress via the SIRT1/PGC-1α signaling pathway and plays a vital role in inhibiting neuronal senescence and apoptosis and enhancing cognitive ability.

Non-Coding RNAs Regulate Spinal Cord Injury-Related Neuropathic Pain via Neuroinflammation

Secondary chronic neuropathic pain (NP) in addition to sensory, motor, or autonomic dysfunction can significantly reduce quality of life after spinal cord injury (SCI). The mechanisms of SCI-related NP have been studied in clinical trials and with the use of experimental models. However, in developing new treatment strategies for SCI patients, NP poses new challenges. The inflammatory response following SCI promotes the development of NP. Previous studies suggest that reducing neuroinflammation following SCI can improve NP-related behaviors. Intensive studies of the roles of non-coding RNAs in SCI have discovered that ncRNAs bind target mRNA, act between activated glia, neuronal cells, or other immunocytes, regulate gene expression, inhibit inflammation, and influence the prognosis of NP.

Knockdown of circEXOC6 inhibits cell progression and glycolysis by sponging miR-433-3p and mediating FZD6 in glioma

BACKGROUND

The effect of circular RNA in many human cancers is widely studied. Nevertheless, their specific biological functions and mechanisms in glioma remain unclear.

METHODS

CircEXOC6, miR-433-3p, and frizzled class receptor 6 (FZD6) mRNA expression levels were measured by quantitative reverse transcription polymerase chain reaction assay. Cell proliferation, migration, invasion, apoptosis, and angiogenesis were tested by colony formation, cell-light 5-ethynyl-2'-deoxyuridine, transwell, and tube formation assays, respectively. Moreover, glucose consumption and lactate production were calculated to evaluate the glycolytic metabolism using the respective kits. Western blot assay was carried out to measure the protein levels of apoptotic markers (Bcl-2 and Bax), glycolytic markers (HK2 and GLUT1), and FZD6. The targeted relationship of miR-433-3p and circEXOC6 or FZD6 was verified by dual-luciferase reporter or RNA immunoprecipitation assays. In vivo, xenograft and immunohistochemistry assay was conducted to discriminate the effect of circEXOC6.

RESULTS

CircEXOC6 and FZD6 were highly expressed, while miR-433-3p was significantly lowly expressed in glioma tissues or cells. Deficiency of circEXOC6 inhibited cell proliferation, migration, invasion, angiogenesis, and glycolysis, and triggered cell apoptosis ratio in glioma; simultaneously, it could block the growth of tumor in vivo. In addition, miR-433-3p was a target of circEXOC6, and downregulated miR-433-3p could partly weaken the inhibitory effect of circEXOC6 deficiency. Besides, miR-433-3p enrichment inhibited cell progression and glycolysis in glioma, and the effect was reversed by overexpression of FZD6.

CONCLUSION

Deletion of circEXOC6 restrained cell progression and glycolysis by sponging miR-433-3p and interacting with FZD6, which might provide an underlying target for glioma treatment.

Potential value of differentially expressed circular RNAs derived from circulating exosomes in the pathogenesis of rat spinal cord injury

Spinal cord injury (SCI) remains one kind of devastating neurological damage, and specific molecular mechanisms involved need to be understood deeply. Currently, circular RNAs (circRNAs), as a newly discovered type of non-coding RNAs (ncRNAs), have been under active investigation. Through functional interactions with disease-associated microRNAs (miRNAs), exosome-derived circRNAs have been extensively implicated in various organ pathogenesis. Nevertheless, the functional involvement of circulating circRNAs in SCI onset, progression as well as repair remains poorly explored until now. Of note, there still lacks clinical and experimental evidence in this regard. To obtain some relevant knowledge in this field, this study was originally designed to have a general overview of differentially expressed circRNAs derived from circulating exosomes in SCI rats in comparison with the control rats. It turned out that 709 types of downregulated circRNAs and 346 kinds of upregulated circRNAs were preliminarily screened out. Functional enrichment analyses including kyoto encyclopedia of genes and genomes (KEGG) pathway and gene ontology (GO) were performed to evaluate the possible biological functions of upregulated as well as downregulated circRNAs involved in SCI. Furthermore, five types of upregulated circulating circRNAs including chr4:208359914–208362182+, chr15:20088296–20092102+, chr1:175098934– 175134845–, chr1:175099657– 175128203–, and chr1:175104454– 175134845–, and plus five kinds of downregulated circulating circRNAs including chr11:74154652– 74159524–, chr12:45412398– 45412635–, chr7:137630261– 137648924–, chr6:6280974–6281188+, and chr4:225251864–225254087+, were verified through reverse transcription-polymerase chain reaction (RT-PCR). At last, taking these differentially expressed circRNAs in the center, the circRNA-miRNA-mRNA gene interaction network was constructed to predict the possible functionalities of circRNAs in SCI through anticipating specific interactive miRNAs, giving new insights into how circRNAs contribute to this pathological process. Taken together, these findings suggest the possible involvement and functional significance of circRNAs in SCI.