Loss of protein homeostasis is a hallmark of cellular senescence, and ribosome pausing plays a crucial role in the collapse of proteostasis. However, our understanding of ribosome pausing in senescent cells remains limited. In this study, we utilized ribosome profiling and G-quadruplex RNA immunoprecipitation sequencing techniques to explore the impact of RNA G-quadruplex (rG4) on the translation efficiency in senescent cells. Our results revealed a reduction in the translation efficiency of rG4-rich genes in senescent cells and demonstrated that rG4 structures within coding sequence can impede translation both in vivo and in vitro. Moreover, we observed a significant increase in the abundance of rG4 structures in senescent cells, and the stabilization of the rG4 structures further exacerbated cellular senescence. Mechanistically, the RNA helicase DHX9 functions as a key regulator of rG4 abundance, and its reduced expression in senescent cells contributing to increased ribosome pausing. Additionally, we also observed an increased abundance of rG4, an imbalance in protein homeostasis, and reduced DHX9 expression in aged mice. In summary, our findings reveal a novel biological role for rG4 and DHX9 in the regulation of translation and proteostasis, which may have implications for delaying cellular senescence and the aging process.
G-Quadruplexes ; Cellular Senescence ; Ribosomes/genetics* ; Humans ; Animals ; Mice ; DEAD-box RNA Helicases/genetics* ; Protein Biosynthesis ; RNA/chemistry* ; Neoplasm Proteins

AIM:This study aim to investigate the effects of lipopolysaccharide(LPS)-induced inflammation on the aging phenotype of hematopoietic stem/progenitor cells(HSPCs)in the bone marrow(BM)and spleen of mice.METHODS:(1)Young(2-month old)wild-type(WT)mice were treated with LPS to establish an actue inflammation model.The percentage of HSPCs in the BM and spleen of mice after LPS stimulation,as well as the ratio of mature cells in peripheral blood(PB)and spleen,were analyzed using flow cytometry.The proliferation of HSPCs in the BM and spleen was evaluated by examining the expression of the proliferation marker Ki67.In addition,changes in CD45 expression on HSPCs in the spleen of mice following LPS exposure were investigated by flow cytometry.(2)The percentage of HSPCs in BM and mature cells in PB and spleen of both young(2-month old)and old(24-month old)WT mice were analyzed by flow cytometry.(3)The transcriptome changes of hematopoietic stem cells(HSCs)after LPS stimulation was performed by an in silico analysis.RESULTS:(1)Mice exposed to LPS exhibited a significant increase in the percentage of HSPCs in BM and a marked elevation in the percentages of myeloid cells in PB and spleen compared to the mice in control group(P<0.05).(2)LPS exposure resulted in increased spleen weight and cell counts(P<0.05),along with a higher per-centage of HSPCs in the spleen compared to controls(P<0.05).(3)LPS stimulation promoted the proliferation of HSPCs in the BM and spleen(P<0.05).(4)The expression of CD45 was reduced on HSPCs from spleen of mice after LPS stimu-lation(P<0.01).(5)In comparison to young mice,aged mice showed an increase in spleen weight and a higher percent-age of HSPCs in the spleen(P<0.05).(6)Aged mice,in comparison to young mice,demonstrated a significantly higher percentage of HSPCs in the BM and myeloid skewing in the PB and spleen(P<0.01).(7)The silico analysis revealed up-regualtion of reactive oxygen species(ROS)and apoptosis signaling in HSPCs following LPS stimulation.CONCLU-SION:Young HSPCs stimulated by LPS exhibited an increase in cell number,a bias towards myeloid differentiation,en-hanced extramedullary hematopoiesis,and elevated levels of ROS and apoptosis,all of which collectively manifested the aging phenotype of HSPCs.

AIM:To investigate the role and molecular mechanisms of SMARCA4(SWI/SNF-related,matrix-associated,actin-dependent regulator of chromatin,subfamily A,member 4)in ferroptosis.METHODS:(1)Human fi-brosarcoma HT1080 cells were treated with dimethyl sulfoxide(DMSO)and different concentrations(31.25,62.5 and 125 nmol/L)of Ras-selective lethal small molecule 3(RSL3;ferroptosis inducer).Each treatment had 3 replicate wells of cells.The protein levels of SMARCA4 were detected by Western blot.(2)Two small interfering RNAs(siSMARCA4-1 and siSMARCA4-2)were constructed according to the SMARCA4 gene sequence.After SMARCA4 knockdown,each treat-ment had 3 replicate wells of cells,and the protein levels of SMARCA4 were determined by Western blot.Effects of DMSO,necrostatin 2 racemate(Nec-1s;necroptosis inhibitor),Z-VAD(OMe)-FMK(Z-VAD,pan-caspase inhibitor/apoptosis inhibitor)and ferrostatin-1(Fer-1,ferroptosis inhibitor)on cell viability were assessed using high-content analy-sis.The levels of ferroptosis indicators,including prostaglandin-endoperoxide synthase 2(PTGS2)transcription,lipid peroxidation,reactive oxygen species(ROS),labile iron pool(LIP)and glutathione,were determined by RT-qPCR and flow cytometry.The mRNA expression levels of pivotal iron metabolism genes,ferroptosis-related ROS regulatory genes,and cholesterol synthesis-related genes were measured using RT-qPCR.Impact of cholesterol on the cell viability were as-sessed using high-content analysis.(3)Common differential gene analysis and gene ontology(GO)enrichment analysis were performed on published online data.RESULTS:(1)Treatment with RSL3 significantly reduced the protein level of SMARCA4(P＜0.05).(2)Knockdown of SMARCA4 resulted in ferroptosis.(3)Knockdown of SMARCA4 did not induce ferroptosis by modulating the LIP and the transcription levels of ROS-related genes.(4)Knockdown of SMARCA4 affected the pathways associated with the cell membrane,lipid raft,and cholesterol synthesis.(5)Addition of cholesterol to cell culture medium rescued the ferroptosis induced by SMARCA4 knockdown(P＜0.01).CONCLUSION:Treatment with RSL3 reduces the protein level of SMARCA4 in human fibrosarcoma HT1080 cells,and inhibition of cholesterol synthesis by SMARCA4 knockdown leads to the ferroptosis of HT1080 cells.

The maintenance of hematopoietic stem cells (HSCs) is a complex process involving numerous cell-extrinsic and -intrinsic regulators. The first member of the cyclin-dependent kinase family of inhibitors to be identified, p21, has been reported to perform a wide range of critical biological functions, including cell cycle regulation, transcription, differentiation, and so on. Given the previous inconsistent results regarding the functions of p21 in HSCs in a p21-knockout mouse model, we employed p21-tdTomato (tdT) mice to further elucidate its role in HSCs during homeostasis. The results showed that p21-tdT+ HSCs exhibited increased self-renewal capacity compared to p21-tdT- HSCs. Zbtb18, a transcriptional repressor, was upregulated in p21-tdT+ HSCs, and its knockdown significantly impaired the reconstitution capability of HSCs. Furthermore, p21 interacted with ZBTB18 to co-repress the expression of cKit in HSCs and thus regulated the self-renewal of HSCs. Our data provide novel insights into the physiological role and mechanisms of p21 in HSCs during homeostasis independent of its conventional role as a cell cycle inhibitor.
Animals ; Hematopoietic Stem Cells/cytology* ; Cyclin-Dependent Kinase Inhibitor p21/genetics* ; Mice ; Cell Self Renewal ; Repressor Proteins/genetics* ; Mice, Inbred C57BL ; Mice, Knockout ; Humans ; Gene Expression Regulation

Objective:To investigate the inhibitory effect and molecular mechanism of microRNA-30d (miR-30d) in the process of proliferation, migration and invasion of malignant mesothelioma cell line MSTO-211H.Methods:In April 2017, the human MSTO-211H cells was used to establish miR-30d overexpressed MSTO-211H cell model by transfection of miR-30d mimics. The qRT-PCR was performed to detect the expression level of miR-30d in the cells transfected miR-30d mimics. The effects of miR-30d on the proliferation, apoptosis, migration and invasion of MSTO-211H cells were analyzed by CCK-8 experiment, flow cytometry, cell scratch experiment and Transwell method.Results:After transfection of miR-30d, the expression level of miR-30d in the MSTO-211H+miR-30d cells group was significantly higher than MSTO-211H+miR NC cells group ( P<0.01) . The cell activity of MSTO-211H+miR-30d group (105.13%±2.35%) was significantly lower than MSTO-211H+miR NC cells group (115.40%±1.35%) , and the level of apoptosis (3.97%±0.36%) was significantly higher than MSTO-211H+miR NC cells group (1.47%±0.10%) ( P<0.01) . The relative migration areas at 12 and 24 h of MSTO-211H+miR-30d cells group (9.35±3.16 μm 2 and 58.19±1.82 μm 2) were significantly lower than MSTO-211H+miR NC cells group (54.42 ±5.26 μm 2 and 88.32 ±1.96 μm 2) ( P<0.01) . Compared with the MSTO-211H+miR NC cells group, the numbers of cell migration and cell invasion were reduced in the MSTO-211H+miR-30d cells group ( P<0.01) . Conclusion:miR-30d can regulate the progression of malignant pleural mesothelioma by inhibiting the proliferation, apoptosis, migration and invasion of MSTO-211H cells.

Objective:To explore the chronic toxicity and its potential mechanism of multi-walled carbon nanotube (MWCNT) in human pleural mesothelial cells.Methods:A sustainable exposure of MeT-5A cells to MWCNT at 10 μg/cm 2 for one year was conducted in 2016. During the exposure, the cell images and cell proliferation was recorded every 4 weeks. The cell apoptosis, cell cycle, cell migration and cell invasion were compared between the control cells and the cells after MWCNT exposure. Finally, the gene expression was screened with Affymetrix clariom D assay, and some of the significantly differential expressed genes was verified by RT-PCR. Results:Compared with the control group, the proliferation ability of the cells in the 1-year exposed group was significantly increased, and the rate of proliferation was about 2-3 times as that in the Control Group ( F=481.32, P<0.05) . MeT-5A cells all showed cell cycle arrest effect, which showed the increase of G1 phase and the decrease of s phase and G2 phase ( F=14.94, P<0.05) . The apoptosis rate of cells in the treated group was significantly higher than that in the control group after 6 months ( F=15.12, P<0.05) , but the early apoptosis rate and the total apoptosis rate of cells in the treated group were not significantly different from those in the control group after 1 year ( F=3.97, P<0.05) . The cell migration and invasion were both promoted by MWCNT. Furthermore, the differentially expressed genes was screened, to find 2, 878 genes with more than 2 folds changes. To further verified, RT-PCR was conducted with PIK3R3、WNT2B、VANGL2、ANXA1, and their expression changes were consistent with above. Conclusion:MWCNT might have a carcinogenic potential to MeT-5A cells after the long term exposure.

Objective:To investigate the inhibitory effect and molecular mechanism of microRNA-30d (miR-30d) in the process of proliferation, migration and invasion of malignant mesothelioma cell line MSTO-211H.Methods:In April 2017, the human MSTO-211H cells was used to establish miR-30d overexpressed MSTO-211H cell model by transfection of miR-30d mimics. The qRT-PCR was performed to detect the expression level of miR-30d in the cells transfected miR-30d mimics. The effects of miR-30d on the proliferation, apoptosis, migration and invasion of MSTO-211H cells were analyzed by CCK-8 experiment, flow cytometry, cell scratch experiment and Transwell method.Results:After transfection of miR-30d, the expression level of miR-30d in the MSTO-211H+miR-30d cells group was significantly higher than MSTO-211H+miR NC cells group ( P<0.01) . The cell activity of MSTO-211H+miR-30d group (105.13%±2.35%) was significantly lower than MSTO-211H+miR NC cells group (115.40%±1.35%) , and the level of apoptosis (3.97%±0.36%) was significantly higher than MSTO-211H+miR NC cells group (1.47%±0.10%) ( P<0.01) . The relative migration areas at 12 and 24 h of MSTO-211H+miR-30d cells group (9.35±3.16 μm 2 and 58.19±1.82 μm 2) were significantly lower than MSTO-211H+miR NC cells group (54.42 ±5.26 μm 2 and 88.32 ±1.96 μm 2) ( P<0.01) . Compared with the MSTO-211H+miR NC cells group, the numbers of cell migration and cell invasion were reduced in the MSTO-211H+miR-30d cells group ( P<0.01) . Conclusion:miR-30d can regulate the progression of malignant pleural mesothelioma by inhibiting the proliferation, apoptosis, migration and invasion of MSTO-211H cells.

Objective:To explore the chronic toxicity and its potential mechanism of multi-walled carbon nanotube (MWCNT) in human pleural mesothelial cells.Methods:A sustainable exposure of MeT-5A cells to MWCNT at 10 μg/cm 2 for one year was conducted in 2016. During the exposure, the cell images and cell proliferation was recorded every 4 weeks. The cell apoptosis, cell cycle, cell migration and cell invasion were compared between the control cells and the cells after MWCNT exposure. Finally, the gene expression was screened with Affymetrix clariom D assay, and some of the significantly differential expressed genes was verified by RT-PCR. Results:Compared with the control group, the proliferation ability of the cells in the 1-year exposed group was significantly increased, and the rate of proliferation was about 2-3 times as that in the Control Group ( F=481.32, P<0.05) . MeT-5A cells all showed cell cycle arrest effect, which showed the increase of G1 phase and the decrease of s phase and G2 phase ( F=14.94, P<0.05) . The apoptosis rate of cells in the treated group was significantly higher than that in the control group after 6 months ( F=15.12, P<0.05) , but the early apoptosis rate and the total apoptosis rate of cells in the treated group were not significantly different from those in the control group after 1 year ( F=3.97, P<0.05) . The cell migration and invasion were both promoted by MWCNT. Furthermore, the differentially expressed genes was screened, to find 2, 878 genes with more than 2 folds changes. To further verified, RT-PCR was conducted with PIK3R3、WNT2B、VANGL2、ANXA1, and their expression changes were consistent with above. Conclusion:MWCNT might have a carcinogenic potential to MeT-5A cells after the long term exposure.

Corona Virus Disease 2019 (COVID-19) has seriously affected the treatment of patients and social stability. In the later stage of disease, some COVID-19 patients may develop into acute respiratory distress syndrome or even multiple organ failure. However, one of the most important mechanism underlying the deterioration of disease is cytokine storm. At present, some therapies such as interleukin-6 antibody blocker, stem cell therapy, and transfusion of convalescent plasma have been applied to counteract the cytokine storm and have made some progress. This article reviews the influences of cytokine storm syndrome on the COVID-19 and the corresponding immunotherapies to resist cytokine storm.

Purpose: 5-Fluorouracil (5-Fu) is used as a conventional chemotherapy drug in chemotherapy forpatients with advanced colorectal cancer, but many patients still suffer from treatment failuredue to 5-Fu resistance. Emerging observations revealed the important role of chemokine(C-X-C motif) ligand 13 (CXCL-13) in tumor microenvironment and its relationship with prognosisin patients with colorectal cancer. This study is designed to reveal the important roleof CXCL-13 in causing colorectal cancer resistance to 5-Fu. Materials and Methods: CXCL-13 levels of patient's serum or cell culture supernatants were measured separatelyby enzyme-linked immunosorbent assay. In cell assays, cell viability is detected by Cell CountingKit-8. Therefore, the recombinant human CXCL-13 was used to simulate its high expressionin cells while its antibody and siRNA were used to reduce CXCL-13 expression in cells. Results: In this study, we demonstrated that CXCL-13 is associated with 5-Fu resistance by culturemedium exchange experiments and cytokine arrays of colorectal cancer resistant and nonresistantcells. Clinical studies showed that CXCL-13 is highly expressed in the serum of5-Fu–resistant patients. High levels of serum CXCL-13 also predict a worse clinical outcome.The addition of recombinant CXCL-13 cytokine resulted in 5-Fu resistance, while its antibodyovercame 5-Fu resistance, and knockdown of CXCL-13 expression by siRNA also reduced5-Fu resistance, which can be saved by added recombination CXCL-13. Conclusion These results not only identify a CXCL-13 mediated 5-Fu resistance mechanism but alsoprovide a novel target for 5-Fu–resistant colorectal cancer in prevention and treatmentstrategies.