Objective To identify genetic regulators of ionizing radiation(IR)sensitivity through clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated nuclease 9(Cas9)genome-wide screening.Methods A specialized single guide RNA(sgRNA)library was developed targeting 987 stress-response regulatory genes identified through Kyoto Encyclopedia of Genes and Genomes(KEGG),Reactome and gene ontology(GO)databases,followed by construction of sgRNA plasmids and packaging into a lentiviral library.Using colon adenocarcinoma Caco-2 cells as a model system,the Cas9-stable transgenic line was established via lentiviral transduction and antibiotic selection.Library-transduced cells underwent puromycin selection,followed by γ-irradiation(dose optimized via preliminary experiments).Post-irradiation phenotypic selection was conducted after 14 days,with subsequent next-generation sequencing of surviving cell populations to identify enriched/depleted sgRNAs.Candidate genes were functionally validated through orthogonal assays:cell counting kit-8(CCK-8)proliferation analysis,clonogenic survival assays and flow cytometric quantification of reactive oxygen species(ROS)and apoptotic markers.Results The optimized screening platform identified 281 radiation response genes(165 radiosensitive and 116 radioprotective candidates).Functional validation revealed Bcl2-associated athanogene 3(BAG3)knockdown significantly enhanced radioresistance.Proliferation was increased 1.2-1.5 fold,clonogenic survival improved 1.5-2.0 fold,and ROS was reduced by 13％-25％coupled with 32％-73％apoptosis attenuation compared to control groups.Conclusion The integrated CRISPR/Cas9 screening platform effectively identifies novel radiation response regulators,as evidenced by the discovery of BAG3 as a critical radiosensitivity determinant.This high-throughput functional genomics approach provides a robust methodology for systematically mapping molecular determinants of cellular radiation response,with potential applications in both mechanistic studies and therapeutic target discovery.

Objective To construct nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)knockout mice in order to investigate the effects of NLRP3 knockout on radiation-induced acute pneumonitis and pulmonary fibrosis.Methods Nlrp3+/+and Nlrp3-/-mice were randomly divided into the control group and irradiation group.To induce radiation-caused acute pneumonitis,the control group was exposed to sham irradiation while the irradiation group was exposed to 60Co γ-rays at a dose of 22 Gy at a dose rate of 184.30 R/min.At 14 days post-irradiation,the body weight of each mouse and the wet weight of its lung tissue were measured separately using an analytical balance to calculate the lung coefficient.Quantitative real-time PCR(qPCR)and cytometric bead array(CBA)were used to detect inflammatory responses in lung tissues and serum.Hematoxylin-eosin(HE)staining and F4/80 immunohistochemical staining were used to assess pathological changes and inflammatory cell infiltration in lung tissues.Cysteinyl aspartate specific proteinase-1(caspase-1)activation was analyzed by Western blotting.To establish a model of radiation-induced pulmonary fibrosis,mice were irradiated with 60Co γ-rays at a dose of 18 Gy at a dose rate of 174.67 R/min.At 24 weeks post-irradiation,HE staining and Masson staining were performed to evaluate pulmonary fibrosis.Results NLRP3 knockout inhibited caspase-1 activation,reduced inflammatory responses in lung tissues and serum,suppressed macrophage infiltration,alleviated pulmonary edema,and thereby protected against acute radiation-induced lung injury.Additionally,NLRP3 knockout significantly ameliorated late-stage radiation-induced pulmonary fibrosis.Conclusion NLRP3 knockout can mitigate both early radiation-induced pneumonia and lateradiation-induced pulmonary fibrosis.

Objective To explore the role of dapansutrile(OLT1177)in radiation-induced intestinal injury and the mechanism.Methods C57BL/6J mice were locally irradiated in the abdomen with 60Co to induce a model of radiation-induced intestinal injury.OLT1177 was intraperitoneally injected at a dose of 100 mg/kg 2 hours before irradiation and 6 hours after irradiation before the drug was administered once a day.At 12 hours after irradiation,intestinal tissues were taken for terminal deoxynucleotidyl transferase mediated nick end labeling(TUNEL)staining to detect apoptosis in intestinal tissues.At 4 days after irradiation,mouse serum was collected to detect the levels of inflammatory factors in the serum.Hematoxylin-eosin(HE)stainingwas used for the evaluation of the damage to the intestinal villus structure.Immunohistochemical staining was adopted to detect the changes in crypt proliferation in intestinal tissues.Finally,proteins were isolated from intestinal tissues,and Western blotting was employed to evaluate the activation of nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome.Results After irradiation,the intestinal villi in mice were shortened.Meanwhile,there was a notable declinein the number of cells that were proliferating in the crypts,a surge in the number of apoptotic cells,and a significant spike in the overall inflammatory level.However,administration of OLT1177 inhibited the activation of the NLRP3 inflammasome,reduced apoptosis and pyroptosis,decreased the inflammatory level,and thus improved radiation-induced intestinal injury.Conclusion Administration of OLT1177 can significantly mitigate radiation-induced intestinal injury.

Objective To explore the effect of G-protein pathway suppressor 2(GPS2)on the proliferation and migration of HepG2 cells and the underlying mechanism.Methods GPS2 expression was analyzed via The Cancer Genome Atlas(TCGA)and Clinical Proteomic Tumor Analysis Consortium(CPTAC)online database.HepG2 cells with stable knockdown or overexpression of GPS2 were established with lentivirus.The protein and mRNA expression levels of GPS2 were detected by Western blotting and real-time quantitative PCR(qPCR)while cell proliferation was verified by cell proliferation assay.Cell migration was tested by Transwell and scratch assay.Epithelial-mesenchymal transition(EMT)biomarkers and the expression of matrix metalloproteinase(MMP)were detected by qPCR.Finally,the expressions of phosphorylation of protein kinase B(AKT)(p-AKT)and phosphorylation of extracellular signal-regulated kinase(ERK)(p-ERK)were detected by Western blotting.Results Based on the analysis of TCGA and CPTAC online database,GPS2 was highly expressed in human liver cancer tissues.Knockdown of GPS2 inhibited the proliferation and migration of HepG2 cells,while overexpression of GPS2 promoted the proliferation and migration of HepG2 cells.Silence of GPS2 up-regulated the mRNA level of E-cadherin(E-CAD),down-regulated the mRNA levels of N-cadherin(N-CAD),Vimentin(VIM),MMP2 and MMP9,and reduced the p-AKT and p-ERK.In contrast,overexpression of GPS2 decreased the mRNA level of E-CAD,increased the mRNA levels of N-CAD,VIM,MMP2 and MMP9,and elevated the protein levels of p-AKT and p-ERK.Conclusion GPS2 can promote the proliferation and migration of HepG2 cells,which might be attributed to increased activation of MAPK/ERK and PI3K/AKT signaling pathways and the EMT process.

Objective To investigate the effect of erythroid differentiation associated gene(EDAG)on hematopoietic stem/progenitor cells(HSPCs)under chronic inflammation.Methods In this study,EDAG-/-and wild type(WT)mice were divided into the experiment group and control group.An infectious chronic inflammation model was established via multiple intraperitoneal injections of Listeria monocytogenes(LM),while a sterile chronic inflammation model was generated via multiple intraperitoneal injections of polyinosinic-polycytidylic acid[Poly(I∶C)].The effect of EDAG on HSPCs was explored under chronic inflammation conditions.Results In the LM repeated infection model,EDAG deletion led to a decrease in HSPCs and long-term hematopoietic stem cells(LT-HSCs)in mice as well as a significant bias towards myeloid differentiation in peripheral blood.Similarly,EDAG knockout also resulted in reduced numbers of HSPCs and decreased colony-forming ability in aseptic chronic inflammation models.Conclusion EDAG deficiency accelerates HSPC depletion in young mice under chronic inflammation,indicating strong protection of EDAG against HSPC damage induced by chronic inflammation.

Objective To investigate the role and mechanism of suramin(Sur)in acetaminophen(APAP)-induced acute liver injury in mice.Methods 8-10 weeks old C57BL/6J mice were randomly divided into the APAP group and APAP+Sur group(20 mg/kg suramin was injected 1 h before).After 18 hrs of fasting,400 mg/kg APAP was injected intraperitoneally to establish a mouse model of acute liver failure and the survival rate was recorded.An acute liver injury model of mice was established via intraperitoneal injection of 300 mg/kg APAP(other conditions remained unchanged).A control group was also established,with liver tissues and serum collected at 0,2,and 12 hours post-APAP treatment.ELISA and CBA techniques were adopted to detect the release of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)in serum and the secretion of inflammatory factors.H&E staining and immunohistochemistry were used to detect liver tissue necrosis and inflammatory cell infiltration.DCFA-DH and ELISA techniques were used to detect the levels of reactive oxygen species(ROS),malondialdehyde(MDA)and glutathione(GSH)in liver tissues.Western blotting was employed to assess the activation of the JNK signaling pathway in liver tissues.Results Suramin treatment improved the survival rate of APAP-induced mice,reduced the release of transaminases and inflammatory factors in serum,and alleviated APAP-induced liver cell necrosis and inflammatory cell infiltration in the liver.Suramin treatment delayed APAP-induced GSH depletion in the liver,reduced MDA and ROS levels,and inhibited JNK pathway activation.Conclusion This study has confirmed the protective effect of suramin against acetaminophen-induced acute liver injury in mice.The mechanism is potentially related to oxidative stress and inflammation.

Objective To establish a mouse model of liver aging induced by irradiation combined with hepatectomy.Methods A model was established via single irradiation combined with hepatectomy.The survival rate,body weight,liver index and liver function of the mice were detected.The expressions of senescence-associated secretory phenotype factors in serum were detected with enzyme-linked immunosorbent assay(ELISA)and flow cytometry.The mRNA levels of senescence-associated secretory phenotype factors and telomerase in liver tissue were detected by real-time quantitative PCR(qPCR).The expressions of cyclin dependent kinase inhibitor 1A(CDKN1A)and cyclin dependent kinase inhibitor 2A(CDKN2A)were determined by Western blotting.ELISA was used to calculate senescence-associated β-galactosidase(SA-β-Gal)and lipofuscin levels.Tissue malondialdehyde levels were measured using the thiobarbituric acid(TBA)method.The size of hepatocyte nuclei and lipid accumulation were detected by hematoxylin-eosin(HE)stainingand oil-red-O while triglyceride levels in the liver were studied with the weighing method.Results After irradiation combined with hepatectomy,the body weight of mice was significantly reduced,the liver index was not significantly affected,but the transaminase level was significantly increased.The levels of SA-β-Gal and lipofuscin increased while telomerase activity decreased significantly,and the nucleus size increased.The expressions of cyclin dependent protein kinase inhibitors CDKN1A and CDKN2A increased.The levels of senescence-associated secretory phenotype factors were significantly increased.Hepatic lipid deposition and oxidative damage were aggravated.Conclusion A mouse model of liver aging induced by irradiation combined with hepatectomy has been established.

Objective:To investigate the difference in the radiation sensitivity of hematopoietic stem and progenitor cells (HSPCs) derived from fetal liver and bone marrow.Methods:HSPCs from fetal liver of 14.5 d embryo or bone marrow of 8 week-old mice were isolated to receive a single dose of 5 or 10 Gy irradiation in vitro using a 60Co irradiator. Twelve hours later, the cell apoptosis, mitochondrial reactive oxygen species (ROS) level, colony formation ability and DNA damage in HSPCs were detected. Freshly isolated HSPCs were injected into lethally irradiated CD45.1 + C57BL/6J mice (4.5 Gy+ 5 Gy with an interval of 30 min) Chimerism rate, lineage constitution, and cell cycle were analyzed 12 weeks after transplantation. Results:Compared with bone marrow HSPCs after irradiation, the percentage of apoptosis in fetal liver HSPCs was significantly higher ( t=16.21, 12.27, P<0.05), the level of ROS was dramatically elevated ( t=68.72, 18.89, P<0.05). At 10 Gy, fetal liver HSPCs could not form colonies at all ( t=12.41, 15.67, 9.46, P<0.05). γ-H2AX immunofluorescence staining showed that the DNA damage of fetal liver HSPCs was more severe after irradiation, and the number of Foci formed was significantly higher than that of bone marrow HSPCs ( t=2.27, 2.03, P< 0.05), which indicated that fetal liver HSPCs were more sensitive to radiation. The chimerism rate of transplanted fetal liver HSPCs was lower than that of bone marrow cells ( t=5.84, P<0.05) with a higher proportion of myeloid lineage, suggesting that fetal liver HSPCs had lower in vivo reconstitution capacity than bone marrow HSPCs and were more prone to myeloid differentiation. The cell cycle of bone marrow HSPCs from transplanted chimeric mice was examined, and the proportion of S-phase was significantly higher in the fetal liver group than that in the bone marrow group ( t=2.89, P<0.05). Mitochondrial stress results showed that fetal liver HSPCs had higher basal respiratory capacity ( t=39.19, P<0.05), proton leakage ( t=6.64, P<0.05), ATP production ( t=9.33, P<0.05), and coupling efficiency ( t=7.10, P<0.05) than bone marrow c-Kit + cells, while respiratory reserve capacity ( t=5.53, P< 0.05) was lower than that of bone marrow c-Kit + cells. Conclusions:HSPCs derived from fetal liver display higher radiosensitivty compared with bone marrow HSPCs, laying the foundation for an in-depth illustration of the effects of radiation on hematopoietic stem cells at different developmental stages.

Objective:To study the effect of different doses of 60Co γ-ray ionizing radiation on mitochondrial function in mouse hematopoietic stem and progenitor cells (HSPCs). Methods:C57BL/6 mice were divided into control group, 1 Gy irradiation group and 4.5 Gy irradiation group. The mitochondrial functions were detected at 12 h and 24 h after irradiation, including ROS level, membrane potential, mitochondrial structure, and mitochondrial stress. Bone marrow c-Kit + cells received a single 15 Gy irradiation in vitro, after 24 h, mitochondrial function was detected. Results:It was found that mice leukocytes ( t=12.41, 18.31, 16.48, 14.16, 19.08, 20.25, P<0.05), red blood cells ( t=4.81, 6.62, P<0.05) and platelets ( t=4.33, 6.68, P<0.05) were significantly reduced. The numbers of bone marrow colony formation unit ( t=16.27, 55.66, 17.06, 43.75, P<0.05), and HSPCs ( t=5.16, 11.55, P<0.05) were decreased dose-dependently post-irradiation. Under 1 Gy irradiation, the mitochondrial function and mitochondrial basal metabolic index of HSPCs ( t= 7.36, 3.68, 4.58, 3.15, 3.15, P<0.05) were enhanced at 24 h post-irradiation. Under 4.5 Gy irradiation, mitochondrial number, mitochondrial membrane potential ( t=12.29, 10.46, P<0.05), maximal respiration and spare respiratory capacity were decreased ( t=7.81, 5.78, 6.70, 5.83, P<0.05), ROS level was increased ( t=4.63, 4.12, P<0.05). The basal respiration and oxidative phosphorylated ATP production were reduced at 12 h after irradiation ( t=8.48, 3.80, P<0.05); and the proton leakage was increased ( t=6.57, P<0.05) and coupling efficiency was reduced ( t=11.43, P<0.05) at 24 h after irradiation. In cultured c-Kit + cells, the level of ROS ( t=11.30, P<0.05) and the maximum respiration and spare respiratory capacity were increased ( t=4.25, 3.44, P<0.05) while the mitochondrial membrane potential was decreased ( t=34.92, P<0.05) significantly. Conclusions:A method for systematically assessing mitochondrial function in HSPCs was established, and the effect of ionizing radiation on mitochondrial function of HSPCs was clarified, laying a foundation for further revealing the mechanism of ionizing radiation-induced mitochondrial damage in HSPCs.