Mitochondrial ferritin (FtMt) is believed to play an antioxidant role via iron regulation, and FtMt gene mutation has been reported in age-related macular degeneration (AMD). However, little is known about FtMt's functions in the retina and any links to AMD. In this study, we observed age-related increase in FtMt and hypoxia-inducible factor-1α (HIF-1α) in murine retinal pigment epithelium (RPE). FtMt overexpression in ARPE-19 cells stabilized HIF-1α, and increased the secretion of vascular endothelial growth factor. Conversely, HIF-1α stabilization reduced the protein level of the mature, functional form of FtMt. FtMt-overexpressing ARPE-19 cells exhibited less oxidative phosphorylation but unchanged production of adenosine triphosphate, enhanced mitochondrial fission, and triggered mitophagy in a HIF-1α–dependent manner. These findings suggest that increased FtMt in RPE may be protective via triggering mitophagy but cause wet AMD by inducing neovascularization due to increased vascular endothelial growth factor secretion. However, reduced level of functional FtMt in RPE under hypoxia may allow dry AMD through susceptibility to age-related stress.
Objective To transfect glioma cells with constructed lenviral vectors over-expressing full length and ectodomain of leucine-rich repeats and immunoglobulin-like domains-2 (LRIG2) gene,and to investigate the effect of transfected genes on the proliferation of glioma cells.Methods The full length and ectodomain of LRIG2 genes were inserted into lentiviral vectors respectively,and then the constructed vectors were transfected into glioblastoma cell line U87.The expression levels were determined by western blotting and quantitative polymerase chain reaction (PCR).Cell counting kit-8 (CCK-8) was used to test the proliferation rate and flowcytometry was used to detect the cell cycle distribution of transfected cells.Results Compared with the control group,the Flag proteins were successfully expressedand the mRNA expression levels of LRIG2 and LRIG2ecto increased by 8.42 and 29.58,respectively.The proliferation rates of LRIG2 and LRIG2ecto over-expressing cells increased significantly compared to the control cells.Cell cycle distribution analysis revealed the proliferation indexes of LRIG2 and LRIG2ecto groups were (50.63 ± 1.29 ) ％ and ( 48.61 ± 0.55 ) ％,respectively,significantly increased compared to (45.48 ±0.7) ％ of control group.Conclusion LRIG2 and LRIG2ecto over-expressing glioblastoma cell lines were successfully established,and both of the full length of and ectodomain of LRIG2 proteins promote the proliferation of glioma cells.
Key words:
Leucine-rich repeats and immunoglobulin-like domains-2; Glioma; Lentivirus; Proliferation
The human leucine-rich repeats and immunoglobulin-like domains (LRIG) gene family contains LRIG1, 2 and 3, encoding integral membrane proteins with an ectodomain, a transmembrane domain and a cytoplasmic tail. LRIG1 negatively regulates multiple receptor tyrosine kinases signaling including the epidermal growth factor receptor (EGFR) and is a proposed tumor suppressor. The soluble LRIG1 ectodomain is demonstrated to be shed naturally and inhibit the progression of glioma. However, little is known regarding the functions of LRIG2. In oligodendroglioma, LRIG2 expression is associated with poor survival, suggesting that LRIG2 might have different functions compared with LRIG1. Since soluble LRIG1 ectodomain has a similar function to the full-length LRIG1, we hypothesize that the different roles exerted by LRIG2 and LRIG1 result from the difference of their ectodomains. Here, we addressed the functions of LRIG2 and LRIG2 ectodomain in the proliferation and apoptosis of glioma and the possible underlying mechanisms. Firstly, we found that LRIG2 expression levels positively correlated with the grade of glioma. Further, we demonstrated for the first time that soluble LRIG2 ectodomain was capable of being released from glioblastoma cells and exerted a pro-proliferative effect. Overexpression of LRIG2 ectodomain promoted the proliferation and inhibited the apoptosis of glioblastoma cells in vitro and in vivo in a similar manner to the full-length LRIG2. Both full-length LRIG2 and LRIG2 ectodomain were found to physically interact with EGFR, enhance the activation of EGFR and its downstream PI3 K/Akt pathway. To our knowledge, this is the first report demonstrating that soluble LRIG2 ectodomain is capable of being released from glioblastoma cells and exerts a similar role to the full-length LRIG2 in the regulation of EGFR signaling in the progression of glioblastoma. LRIG2 ectodomain, with potent pro-tumor effects, holds promise for providing a new therapeutic target for the treatment of glioblastoma.
Abstract Background: Exercise intolerance was prevalent in people with chronic obstructive pulmonary disease (COPD) and had a detrimental effect on the quality of life. We aimed to evaluate the efficacy and safety of nitrate supplementation in exercise tolerance of people with COPD. Methods: We searched medical databases including Cochrane Library, EMBASE, and PubMed from inception to October 2020 for randomized control trials in treating COPD with nitrate supplementation. Results: Nine trials were identified. Compared with placebo, nitrate supplementation has no significant effect on the following variables: exercise endurance time (standard mean difference [SMD]: 0.06; 95% confidence interval [CI]: –0.39 to 0.52; P = .79), exercise capacity (SMD: 0.30; 95% CI: –0.21 to 0.80; P = .25), oxygen consumption (SMD: –0.04; 95% CI: –0.33 to 0.25; P = .80), resting systolic blood pressure (MD: –2.84; 95% CI: –8.46 to 2.78; P = .32), systolic blood pressure after exercise (MD: –4.66; 95% CI –15.66 to 6.34; P = .41), resting diastolic blood pressure (MD: 0.89; 95% CI: –4.41 to 6.19; P = .74), diastolic blood pressure after exercise (MD: –0.21; 95% CI: –5.51 to 5.10; P = .94), heart rate (MD: –2.52; 95% CI: –7.76 to 2.73; P = .35), and arterial oxygen saturation (MD: –0.44; 95% CI: –2.38 to 1.49; P = .65). No severe adverse effects from nitrate supplementation were reported in the included trails. Conclusion: Current evidence suggests that nitrate supplementation may be safe but ineffective for improving exercise tolerance in people with COPD.
Studies have shown an increased expression of mitochondrial ferritin (FtMt) and an antioxidant role for the protein in the brains of Alzheimer's disease (AD) patients. However, little information is available concerning the role of FtMt in other AD p
Objective To explore the mechanism of RNA interference-mediated leucine-rich repeats and immunoglobulin-like domains 1 ( LRIG1 ) gene silencing promoting invasion of glioblastoma cell line U251.Methods The U6 promoter-driven plasmid pGenesil2-LRIGl-shRNA (siRNA) was transfected into U251 glioma cells by lipofectime 2000,and the cells (siRNA) that stably suppressed LRIG1 expression were selected by G418.The control cells were transfected with negative shRNA (neg).The changes of invasive ability in the U251 cells were measured by cell invasion assay.The activities of the matrix metalloproteinases (MMP)-2,and -9 were detected by gelatin zymography.LRIG1,epidermal growth factor receptor (EGFR) and phosphorylated EGFR proteins were examined by using Western blotting.Results As compared with the negative shRNA-transfected cells,LRIG1 mRNA expression in the U6 promoterdriven plasmid pGenesil2-LRIG1 -shRNA (siRNA) cells was silenced to 35.3％-39.2％ (P ＜0.05),and knocking-down LRIGI increased the mean invasion cell number of per field to ( 159 ± 15 )-( 188 ± 9 ),compared to control group ( P ＜ 0.05 ).Down-regulation of LRIG1 increased MMP-2 activity by ( 1.66 ±0.11)-(1.96 ±0.12) fold,and increased MMP9 activity by (4.82 ±0.27)-(4.47 ±0.29) fold,compared to control group ( P ＜0.01 ).EGFR signaling pathway was activated after knocking down the LRIG1 expression.Conclusion Silencing of LRIG1 promotes invasion of glioblastoma cell line U251 via up-regulating the MMP-2,and -9 (P ＜ 0.O1 ),which is possibly by enhancing activities of EGFR signaling pathway.
Key words:
Glioma; Matrix metalloproteinases; Leucine-rich repeats and immunoglobulin-like domains 1 ; Invasion
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