Micro-RNA (miR)-155 is a novel gene regulator with important roles in inflammation. Herein, our study aimed to explore the role of miR-155 in LPS-induced acute lung injury(ALI). ALI in mice was induced by intratracheally delivered LPS. Loss-of-function experiments performed on miR-155 knockout mice showed that miR-155 gene inactivation protected mice from LPS-induced ALI, as manifested by preserved lung permeability and reduced lung inflammation compared with wild-type controls. Bone marrow transplantation experiments identified leukocytes, but not lung parenchymal-derived miR-155-promoted acute lung inflammation. Real-time PCR analysis showed that the expression of miR-155 in lung tissue was greatly elevated in wild-type mice after LPS stimulation. In situ hybridization showed that miR-155 was mainly expressed in alveolar macrophages. In vitro experiments performed in isolated alveolar macrophages and polarized bone marrow-derived macrophages confirmed that miR-155 expression in macrophages was increased in response to LPS stimulation. Conversely, miR-155 gain-of-function in alveolar macrophages remarkably exaggerated LPS-induced acute lung injury. Molecular studies identified the inflammation repressor suppressor of cytokine signaling (SOCS-1) as the downstream target of miR-155. By binding to the 3′-UTR of the SOCS-1 mRNA, miR-155 downregulated SOCS-1 expression, thus, permitting the inflammatory response during lung injury. Finally, we generated a novel miR-155 knockout rat strain and showed that the proinflammatory role of miR-155 was conserved in rats. Our study identified miR-155 as a proinflammatory factor after LPS stimulation, and alveolar macrophages-derived miR-155 has an important role in LPS-induced ALI.
Diabetic retinopathy (DR) is a common complication of diabetes. Retinal neuronal degeneration is an early event in DR, indicated by the declined electroretinogram (ERG). Dipeptide alanine-glutamine (Ala-Gln) is widely used as a nutritional supplement in the clinic and has anti-inflammatory effects on the gastrointestinal system. Studies also reported that glutamine has beneficial effects on diabetes. This study aimed to investigate the possible therapeutic effects of Ala-Gln in diabetic retinal neurodegeneration and to delineate its mechanism of action.
Sialic acid is often the distal sugar on glycoconjugates, and sialidases are enzymes that remove this sugar. In fibrotic lesions in human and mouse lungs, there is extensive desialylation of glycoconjugates, and upregulation of sialidases including the extracellular sialidase NEU3. In the bleomycin model of pulmonary fibrosis, mice lacking NEU3 (Neu3-/-) showed strongly attenuated bleomycin-induced weight loss, lung damage, inflammation, and fibrosis. This indicates that NEU3 is necessary for the full spectrum of bleomycin-induced pulmonary fibrosis.To determine if NEU3 is sufficient to induce pulmonary fibrosis, recombinant murine NEU3 and a mutated inactive recombinant murine NEU3 protein were produced. Mice were given recombinant NEU3 proteins by oropharyngeal aspiration, either alone or 10 days after bleomycin challenge. Over the course of 21 days, mice were assessed for weight change, and after euthanasia, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis.Aspiration of recombinant murine NEU3 caused inflammation and fibrosis in the lungs, while inactive NEU3 caused inflammation but not fibrosis. Mice were also treated with recombinant murine NEU3 starting 10 days after bleomycin. In male but not female mice, recombinant murine NEU3 increased inflammation and fibrosis. Inactive NEU3 did not enhance bleomycin-induced lung fibrosis.These results suggest that NEU3 is sufficient to induce fibrosis in the lungs, that aspiration of NEU3 has a greater effect on male mice, and that this effect is mediated by NEU3's enzymic activity.
Although pterostilbene (PTE) has been shown to have potent antitumor activities against various cancer types, the molecular mechanisms of these activities remain unclear. In this study, we investigated the antitumor activity of PTE against human lung adenocarcinoma in vitro and in vivo and explored the role of the Notch1 signaling pathway in this process. PTE treatment resulted in a dose- and time-dependent decrease in the viability of A549 cells. Additionally, PTE exhibited strong antitumor activity, as evidenced not only by a reduced mitochondrial membrane potential (MMP) and a decreased intracellular glutathione content but also by increases in the apoptotic index and the level of reactive oxygen species (ROS). Furthermore, PTE treatment induced the activation of the Notch1 Intracellular Domain (NICD) protein and activated Hes1. DAPT (a gamma secretase inhibitor) and Notch1 siRNA prevented the induction of NICD and Hes1 activation by PTE treatment and sensitized the cells to PTE treatment. The down-regulation of Notch signaling also prevented the activation of pro-survival pathways (most notably the PI3K/Akt pathway) after PTE treatment. In summary, lung adenocarcinoma cells may enhance Notch1 activation as a protective mechanism in response to PTE treatment. Combining a gamma secretase inhibitor with PTE treatment may represent a novel approach for treating lung adenocarcinoma by inhibiting the survival pathways of cancer cells.
Abstract The heart primarily derives its energy through lipid oxidation. In cardiomyocytes, lipids are stored in lipid droplets (LDs) and are utilized in mitochondria, although the structural and functional connections between these two organelles remain largely unknown. In this study, visible evidence have presented indicating that a complex is formed at the mitochondria‐LD membrane contact (MLC) site, involving mitochondrion‐localized Mfn2 and LD‐localized Hsc70. This complex serves to tether mitochondria to LDs, facilitating the transfer of fatty acids (FAs) from LDs to mitochondria for β‐oxidation. Reduction of Mfn2 induced by lipid overload inhibits MLC, hinders FA transfer, and results in lipid accumulation. Restoring Mfn2 reinstates MLC, alleviating myocardial lipotoxicity under lipid overload conditions both in‐vivo and in‐vitro. Additionally, prolonged lipid overload induces Mfn2 degradation through the ubiquitin‐proteasome pathway, following Mfn2 acetylation at the K243 site. This leads to the transition from adaptive lipid utilization to maladaptive lipotoxicity. The experimental findings are supported by clinical data from patients with obesity and age‐matched non‐obese individuals. These translational results make a significant contribution to the molecular understanding of MLC in the heart, and offer new insights into its role in myocardial lipotoxicity.
Objective To inhibit the expression of human protection of telomeres 1 (hPOT1) in gastric cancer cell BGC823 by RNA interference and to investigate the effect of hPOT1 on expression of mutant p53.Methods The 19 bases interference sequence targeting hPOT1 was selected from exon 8. RNA interference eukaryotic expression vector targeting hPOT1 was constructed and transfected into poorly differentiated human gastric cancer cell BGC823 in vitro. The expression of hPOT1 and mutant p53 in mRNA level were detected by semi-determination RT-PCR. Results RNA interference eukaryotic expression vector targeting hPOT1 was identified by DNA sequencing. The mRNA level of hPOT1 was inhibited significantly in cells of hPOT1 siRNA. The efficiency of gene silencing was about 70%. Decrase in mutant p53 expression was observed in cells of hPOT1 siRNA. Conclusion With the expression of hPOT1 in human gastric cancer cell BGC823 inhibited by RNA interference,the expression of mutant p53 decreased, indicating that hPOT1 correlate with mutant p53.
Pulmonary fibrosis involves the formation of inappropriate scar tissue in the lungs, but what drives fibrosis is unclear. Sialidases (also called neuraminidases) cleave terminal sialic acids from glycoconjugates. In humans and mice, pulmonary fibrosis is associated with desialylation of glycoconjugates and upregulation of sialidases. Of the four mammalian sialidases, we previously detected only NEU3 in the bronchoalveolar lavage fluid from mice with bleomycin-induced pulmonary fibrosis. In this report, we show that NEU3 upregulates extracellular accumulation of the profibrotic cytokines IL-6 and IL-1β, and IL-6 upregulates NEU3 in human peripheral blood mononuclear cells, suggesting that NEU3 may be part of a positive feedback loop potentiating fibrosis. To further elucidate the role of NEU3 in fibrosis, we used bleomycin to induce lung fibrosis in wild-type C57BL/6 and Neu3-/- mice. At 21 days after bleomycin, compared with male and female C57BL/6 mice, male and female Neu3-/- mice had significantly less inflammation, less upregulation of other sialidases and the profibrotic cytokine active transforming growth factor β1, and less fibrosis in the lungs. Our results suggest that NEU3 participates in fibrosis and that NEU3 could be a target to develop treatments for fibrosis.
Lung cancer is the leading cause of cancer-related deaths worldwide. Tumor suppressor genes (TSGs) play a critical role in restricting tumorigenesis and impact the therapeutic effect of various treatments. However, TSGs remain to be systemically determined in lung cancer. Here, we identified GATA6 as a potent lung cancer TSG. GATA6 inhibited lung cancer cell growth in vitro and tumorigenesis in vivo. Mechanistically, GATA6 upregulated p53 and p21 mRNA while it inhibited AKT activation to stabilize p21 protein, thus inducing lung cancer cell senescence. Furthermore, we showed that ectopic expression of GATA6 led to dramatic slowdown of growth rate of established lung tumor xenograft in vivo.
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