Long non-coding RNA NEAT1 promotes lipopolysaccharide-induced acute lung injury by regulating miR-424-5p/MAPK14 axis

METTL3 aggravates cell damage induced by Streptococcus pneumoniae via the NEAT1/CTCF/MUC19 axis

Disruption of the alveolar barrier can trigger acute lung injury. This study elucidated the association of methyltransferase-like 3 (METTL3) with Streptococcus pneumoniae (SP)-induced apoptosis and inflammatory injury of alveolar epithelial cells (AECs). AECs were cultured and then infected with SP. Furthermore, the expression of METTL3, interleukin (IL)-10, IL-6, tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1), mucin 19 (MUC19), N6-methyladenosine (m6A), and NEAT1 after m6A modification were detected by qRT-PCR, Western blot, and enzyme-linked immunosorbent, m6A quantification, and methylated RNA immunoprecipitation-qPCR analyses, respectively. Moreover, the subcellular localization of NEAT1 was analyzed by nuclear/cytosol fractionation assay, and the binding between NEAT1 and CCCTC-binding factor (CTCF) was also analyzed. The results of this investigation revealed that SP-induced apoptosis and inflammatory injury in AECs and upregulated METTL3 expression. In addition, the downregulation of METTL3 alleviated apoptosis and inflammatory injury in AECs. METTL3-mediated m6A modification increased NEAT1 and promoted its binding with CTCF to facilitate MUC19 transcription. NEAT1 or MUC19 overexpression disrupted their protective role of silencing METTL3 in AECs, thereby increasing apoptosis and inflammatory injury. In conclusion, this is the first study to suggest that METTL3 aggravates SP-induced cell damage via the NEAT1/CTCF/MUC19 axis.

Breviscapine Reduces Sepsis-Induced Acute Lung Injury by Targeting CASP8 to Regulate Neutrophil Apoptosis and Inflammation

Background

Breviscapine has been demonstrated to have beneficial effects in ameliorating acute lung injury (ALI), yet its potential therapeutic value and molecular mechanisms in sepsis-induced ALI remain unexplored.

Methods

We utilized network pharmacology approach to identify the potential targets and mechanisms of breviscapine in treating sepsis-induced ALI. To construct a murine model of sepsis, we performed cecal ligation and puncture (CLP). Hematoxylin and eosin (HE) staining and enzyme-linked immunosorbent assay (ELISA) were employed to respectively determine the pathologic changes and levels of inflammatory factors. Neutrophil count and total protein level in bronchoalveolar lavage fluid (BALF) were detected by corresponding kit. Additionally, we utilized flow cytometry, immunofluorescence, Western blotting, and real-time reverse transcription PCR (qRT-PCR) to detect cell apoptosis, protein expression, and gene expression. Finally, we used ELISA kits to detect the activity of myeloperoxidase (MPO) and caspase-8 (CASP8).

Results

Breviscapine was revealed to target 81 potential proteins in the treatment of sepsis-induced ALI, while CASP8 was the most important one as demonstrated by network analysis. In vivo experiments demonstrated that breviscapine effectively reduced the severity of sepsis-induced ALI and inflammation, and significantly suppressed neutrophil infiltration in the lung tissues of CLP mice and promoted neutrophil apoptosis in the peripheral blood. In vitro experiments revealed that lipopolysaccharide (LPS)-induced neutrophil apoptosis was inhibited, and the expression and activity of CASP8 were down-regulated. Breviscapine intervention markedly up-regulated the expression and activity of CASP8, consequently activating neutrophil apoptosis and inhibiting inflammatory response by activating the NF-κB signaling pathway.

Conclusion

Breviscapine is remarkably effective in improving sepsis-induced ALI, and its mechanism of action may be to induce neutrophil apoptosis, inhibit inflammatory overreaction and reduce its infiltration in pulmonary tissues by up-regulating the expression and activity of CASP8.

Knockdown of lncRNA NEAT1 suppresses streptococcus pneumoniae-induced ferroptosis in alveolar epithelial cells by regulating the Nrf2-GPX4 pathway

OBJECTIVES

Streptococcus pneumoniae (SP) is a major cause of community-acquired pneumonia. Ferroptosis pitches in pneumonia. Long noncoding RNA nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) regulates ferroptosis in various cells. Therefore, this study probed the mechanism of lncRNA NEAT1 on SP-induced ferroptosis in AECs.

METHODS

Serum lncRNA NEAT1 level in 36 streptococcus pneumonia patients were retrospectively detected, with its correlations with inflammatory factor (TNF-α/IL-1β/IL-6) levels analyzed. Human pulmonary alveolar epithelial cells (HPAEpiC) were transfected with sh-NEAT1 and induced by SP. Cell viability was evaluated by CCK-8. Lactate dehydrogenase (LDH) activity was assessed. Iron content, and levels of TNF-α/IL-1β/IL-6/IL-10/lncRNA NEAT1/lipid peroxidation products [malondialdehyde (MDA)/glutathione (GSH)/reactive oxygen species/(ROS)]/ferroptosis-related proteins [Cyclooxgenase 2 (COX2)/recombinant solute carrier family 7 member 11 (SLC7A11)/total nuclear factor erythroid 2-related factor 2 (Nrf2)/cytoplasmic Nrf2 (C-Nrf2)/nuclear Nrf2 (N-Nrf2)/GPX4)] were determined by kit/ELISA/RT-qPCR/kits/Western blot. Nrf2 nuclear translocation was detected by immunofluorescence assay. On top of lncRNA NEAT1 knockdown, SP-induced HPAEpiC were treated with ML385.

RESULTS

Serum lncRNA NEAT1 level was elevated in streptococcus pneumonia patients, and were positively interrelated with TNF-α/IL-1β/IL-6 levels. SP promoted cell HPAEpiC injury and inflammatory response, and up-regulated lncRNA NEAT1 level. LncRNA NEAT1 knockdown suppressed HPAEpiC injury/inflammatory response (reduced LDH activity and TNF-α/IL-1β/IL-6 levels, elevated IL-10) and suppressed ferroptosis (decreased iron/MDA/ROS contents and COX2 level, increased GSH/SLC7A11), facilitated Nrf2 nuclear translocation, and up-regulated GPX4. Nrf2-GPX4 pathway inhibition annulled NEAT1 knockdown-mediated improvement on SP-induced HPAEpiC ferroptosis/injury/inflammatory response.

CONCLUSIONS

LncRNA NEAT1 knockdown suppressed SP-induced HPAEpiC ferroptosis by activating Nrf2-GPX4 pathway, thereby alleviating cell injury and inflammatory response.

Circular RNA KIAA0564 Serves as a Competitive Endogenous RNA for MicroRNA-424-5p, Mediating the Expression of Lysine Demethylase 4a, Thereby Facilitating Intervertebral Disc Degeneration

A growing body of research has confirmed the involvement of circular RNAs (circRNAs) in the regulation of intervertebral disc degeneration (IDD) progression. However, the underlying molecular networks remain largely elusive. This study aimed to explore whether a novel circRNA, named circKIAA0564, affects nucleus pulposus (NP) cell injury and to elucidate its molecular mechanism. Both in vivo and in vitro IDD models were established, and the expression patterns of circKIAA0564/miR-424-5p/lysine demethylase 4a (KDM4A) were evaluated through quantitative reverse transcription PCR and Western blot analysis. Actinomycin D, RNase R, and Northern blotting were utilized to assess the circular structure of circKIAA0564. The Cell Counting Kit-8, flow cytometry, enzyme-linked immunosorbent assay, commercial assay kits, Western blotting, and reactive oxygen species (ROS) probes were employed to assess the inflammatory and oxidative stress status in NP cells and tissues. Hematoxylin and eosin and TUNEL staining were used to evaluate pathological damage in mouse NP tissues. RNA immunoprecipitation and dual-luciferase reporter assays were conducted to assess the direct targeting relationships among circKIAA0564, miR-424-5p, and KDM4A. CircKIAA0564 was found to be abnormally overexpressed in IDD, functioning as a novel circRNA. Knockdown of circKIAA0564 ameliorated interleukin-1 beta (IL-1β)-induced inflammation and oxidative stress in NP cells. The therapeutic effect of circKIAA0564 knockdown on NP cells was reversed by the silencing of miR-424-5p. Overexpression of circKIAA0564 exacerbated IL-1β-induced NP cell injury, a process that was reversed by knockdown of KDM4A. CircKIAA0564 activated the toll-like receptor 4 (TLR4)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)/NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) signaling pathway by regulating the miR-424-5p/KDM4A axis. CircKIAA0564 exacerbates IL-1β-induced inflammation and oxidative stress in NP cells by competitively binding miR-424-5p, thereby mediating KDM4A and activating the TLR4/NF-κB/NLRP3 signaling pathway. These findings provide robust data support for targeted therapy of IDD and the development of future pharmaceuticals.

Functional roles of circular RNAs in lung injury

Lung injury leads to respiratory dysfunction, low quality of life, and even life-threatening conditions. Circular RNAs (circRNAs) are endogenous RNAs produced by selective RNA splicing. Studies have reported their involvement in the progression of lung injury. Understanding the roles of circRNAs in lung injury may aid in elucidating the underlying mechanisms and provide new therapeutic targets. Thus, in this review, we aimed to summarize and discuss the characteristics and biological functions of circRNAs, and their roles in lung injury from existing research, to provide a theoretical basis for the use of circRNAs as a diagnostic and therapeutic target for lung injury.

hsa-miR-424-5p and hsa-miR-513c-3p dysregulation mediated by IFN-γ is associated with salivary gland dysfunction in Sjögren's syndrome patients

Salivary secretory dysfunction in SS-patients is associated with altered proteostasis, upregulation of ATF6α and components of the ERAD complex, such as SEL1L, and downregulation of XBP-1s and GRP78. Hsa-miR-424-5p is downregulated and hsa-miR-513c-3p is overexpressed in salivary glands from SS-patients. These miRNAs emerged as candidates that could regulate ATF6/SEL1L and XBP-1s/GRP78 levels, respectively. This study aimed to evaluate the effect of IFN-γ on hsa-miR-424-5p and hsa-miR-513c-3p expression and how these miRNAs regulate their targets. In labial salivary glands (LSG) biopsies from 9 SS-patients and 7 control subjects and IFN-γ-stimulated 3D-acini were analyzed. hsa-miR-424-5p and hsa-miR-513c-3p levels were measured by TaqMan assays and their localization by ISH. mRNA, protein levels, and localization of ATF6, SEL1L, HERP, XBP-1s and GRP78 were determined by qPCR, Western blot, or immunofluorescence. Functional and interaction assays were also performed. In LSGs from SS-patients and IFN-γ-stimulated 3D-acini, hsa-miR-424-5p was downregulated and ATF6α and SEL1L were upregulated. ATF6α and SEL1L were decreased after hsa-miR-424-5p overexpression, while ATF6α, SEL1L and HERP increased after hsa-miR-424-5p silencing. Interaction assays revealed that hsa-miR-424-5p targets ATF6α directly. hsa-miR-513c-3p was upregulated and XBP-1s and GRP78 were downregulated. XBP-1s and GRP78 were decreased after hsa-miR-513c-3p overexpression, while increases in XBP-1s and GRP78 were observed after hsa-miR-513c-3p silencing. Furthermore, we determined that hsa-miR-513c-3p targets XBP-1s directly. Significant correlations were found between both miRNA levels and clinical parameters. In conclusion, IFN-γ-dependent hsa-miR-424-5p and hsa-miR-513c-3p levels affect the expression of important factors involved in cellular proteostasis that control secretory function in LSG from SS-patients.

MiR-424/TGIF2-Mediated Pro-Fibrogenic Responses in Oral Submucous Fibrosis

Oral submucous fibrosis (OSF) has been recognized as a potentially malignant disorder and is characterized by inflammation and the deposition of collagen. Among various regulators of fibrogenesis, microRNAs (miR) have received great attention but the detailed mechanisms underlying the miR-mediated modulations remain largely unknown. Here, we showed that miR-424 was aberrantly overexpressed in OSF tissues, and then we assessed its functional role in the maintenance of myofibroblast characteristics. Our results demonstrated that the suppression of miR-424 markedly reduced various myofibroblast activities (such as collagen contractility and migration ability) and downregulated the expression of fibrosis markers. Moreover, we showed that miR-424 exerted this pro-fibrosis property via direct binding to TGIF2, an endogenous repressor of the TGF-β signaling. In addition, our findings indicated that overexpression of miR-424 activated the TGF-β/Smad pathway, leading to enhanced myofibroblast activities. Altogether, our data revealed how miR-424 contributed to myofibroblast transdifferentiation, and targeting the miR-424/TGIF2 axis may be a viable direction for achieving satisfactory results from OSF treatment.

Circular RNA circESPL1 knockdown alleviates lipopolysaccharide (LPS)-induced lung cell injury via sponging miR-326 to regulate MAPK14

BACKGROUND

Infantile pneumonia (IP) is a common inflammatory disease, which brings a heavy burden to young children's health. Previous studies suggested that circular RNA (circRNA) hsa_circ_0026579 (also called circESPL1) was significantly upregulated in pneumonia patients, which was associated with the disease severity. This subject aimed to explore the functional effects and potential regulatory mechanism of circESPL1 on lipopolysaccharide (LPS)-induced lung cell injury.

METHODS

WI-38 and MRC-5 cells were stimulated by LPS to mimic the inflammatory injury model. CircESPL1, microRNA-326 (miR-326), and Mitogen-Activated Protein Kinase 14 (MAPK14)levels were measured using real-time quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays were performed to assess cell proliferation and apoptosis. Western blot analysis of B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), C-caspase 3, and MAPK14 protein levels. Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), and IL-1β levels were examined using an Enzyme-linked immunosorbent assay (ELISA). Using Starbase analysis, the binding between miR-326 and circESPL1 or MAPK14 was predicted, followed by confirmation using a dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays.

RESULTS

Increased circESPL1 and MAPK14, and reduced miR-326 were observed in serum samples from preeclampsia sufferers and LPS-treated lung cells (P < 0.05). Furthermore, circESPL1 deficiency overturned LPS-mediated cell proliferation, apoptosis, and inflammatory response in vitro (P < 0.05). In terms of molecular mechanisms, circESPL1 worked as a sponge of miR-326, and miR-326 absence reversed the protective role of circESPL1 silencing on LPS-triggered lung cell injury (P < 0.05). Also, miR-326 directly targeted MAPK14, and MAPK14 overexpression abolished miR-326-mediated impacts under LPS treatment (P < 0.05).

CONCLUSION

CircESPL1 knockdown might attenuate LPS-caused lung cell injury by regulating the miR-326/ MAPK14 axis, providing useful insight for exploring a novel therapeutic approach for IP.

MicroRNA-424-5p Alleviates Isoflurane Anesthesia-Induced Neurotoxicity in Human Embryonic Stem Cell-Derived Neurons by Targeting FASN

Isoflurane (ISO) is a type of anesthetic that might cause neurotoxicity in children. Although miR-424-5p is considerably downregulated in ISO-treated rat brain samples, its physiological role in ISO-induced neuronal injury in human embryonic stem cell-derived neurons remains unknown (hESC-derived neurons). miR-424-5p expression and fatty acid synthase (FASN) in ISO-treated hESC-derived neurons were tested via qRT-PCR. The amount of protein for Bax, Cleaved-caspase-8, Bcl-2, and FASN was investigated through western blot analysis. The viability and apoptosis of hESC-derived neurons were estimated through cell counting kit-8 assessment and TUNEL assay, accordingly. Superoxide dismutase, glutathione, and malondialdehyde levels were discovered via corresponding kits. The contents of inflammatory factors including interleukin-6 and tumor necrosis factor-α were examined by enzyme-linked immunosorbent assays. The combination between FASN and miR-424-5p was resolute via dual-luciferase reporter assessment. After exposure to ISO, induced neurotoxicity and a decreased miR-424-5p production were identified in hESC-derived neurons. Upregulation of miR-424-5p repressed ISO-induced apoptosis and mitigated ISO-induced inflammatory response and oxidative stress in vitro. FASN expression levels were reduced by elevation of miR-424-5p and upregulated after ISO treatment. Mechanically, FASN was directly targeted by miR-424-5p in hESC-derived neurons. Of note, the miR-424-5p elevation-suppressed neuronal apoptosis, inflammatory response, and oxidative stress were countered by upregulation of FASN.