eIF4E integrates into stress response.

In this issue, Diamond et al.1 and Kim et al.2 report that depletion of eIF4E leads to translational upregulation of GCN4, a key player in the integrated stress response, in an eIF2α phosphorylation-independent manner, suggesting a new mode of translational adaptation.

Lysosomal cystine governs ferroptosis sensitivity in cancer via cysteine stress response.

The amino acid cysteine and its oxidized dimeric form cystine are commonly believed to be synonymous in metabolic functions. Cyst(e)ine depletion not only induces amino acid response but also triggers ferroptosis, a non-apoptotic cell death. Here, we report that unlike general amino acid starvation, cyst(e)ine deprivation triggers ATF4 induction at the transcriptional level. Unexpectedly, it is the shortage of lysosomal cystine, but not the cytosolic cysteine, that elicits the adaptative ATF4 response. The lysosome-nucleus signaling pathway involves the aryl hydrocarbon receptor (AhR) that senses lysosomal cystine via the kynurenine pathway. A blockade of lysosomal cystine efflux attenuates ATF4 induction and sensitizes ferroptosis. To potentiate ferroptosis in cancer, we develop a synthetic mRNA reagent, CysRx, that converts cytosolic cysteine to lysosomal cystine. CysRx maximizes cancer cell ferroptosis and effectively suppresses tumor growth in vivo. Thus, intracellular nutrient reprogramming has the potential to induce selective ferroptosis in cancer without systematic starvation.

Application of metagenomic next-generation sequencing in optimizing the diagnosis of ascitic infection in patients with liver cirrhosis.

BACKGROUND: Metagenomic next-generation sequencing (mNGS) is an emerging technique for the clinical diagnosis of infectious disease that has rarely been used for the diagnosis of ascites infection in patients with cirrhosis. This study compared mNGS detection with conventional culture methods for the on etiological diagnosis of cirrhotic ascites and evaluated the clinical effect of mNGS. METHODS: A total of 109 patients with ascites due to cirrhosis were included in the study. We compared mNGS with conventional culture detection by analyzing the diagnostic results, pathogen species and clinical effects. The influence of mNGS on the diagnosis and management of ascites infection in patients with cirrhosis was also evaluated. RESULTS: Ascites cases were classified into three types: spontaneous bacterial peritonitis (SBP) (16/109, 14.7%), bacterascites (21/109, 19.3%) and sterile ascites (72/109, 66.1%). In addition, 109 patients were assigned to the ascites mNGS-positive group (80/109, 73.4%) or ascites mNGS-negative group (29/109, 26.6%). The percentage of positive mNGS results was significantly greater than that of traditional methods (73.4% vs. 28.4%, P < 0.001). mNGS detected 43 strains of bacteria, 9 strains of fungi and 8 strains of viruses. Fourteen bacterial strains and 3 fungal strains were detected via culture methods. Mycobacteria, viruses, and pneumocystis were detected only by the mNGS method. The mNGS assay produced a greater polymicrobial infection rate than the culture method (55% vs. 16%). Considering the polymorphonuclear neutrophil (PMN) counts, the overall percentage of pathogens detected by the two methods was comparable, with 87.5% (14/16) in the PMN ≥ 250/mm3 group and 72.0% (67/93) in the PMN < 250/mm3 group (P > 0.05). Based on the ascites PMN counts combined with the mNGS assay, 72 patients (66.1%) were diagnosed with ascitic fluid infection (AFI) (including SBP and bacterascites), whereas based on the ascites PMN counts combined with the culture assay, 37 patients (33.9%) were diagnosed with AFI (P < 0.05). In 60 (55.0%) patients, the mNGS assay produced positive clinical effects; 40 (85.7%) patients had their treatment regimen adjusted, and 48 patients were improved. The coincidence rate of the mNGS results and clinical findings was 75.0% (60/80). CONCLUSIONS: Compared with conventional culture methods, mNGS can improve the detection rate of ascites pathogens, including bacteria, viruses, and fungi, and has significant advantages in the diagnosis of rare pathogens and pathogens that are difficult to culture; moreover, mNGS may be an effective method for improving the diagnosis of ascites infection in patients with cirrhosis, guiding early antibiotic therapy, and for reducing complications related to abdominal infection. In addition, explaining mNGS results will be challenging, especially for guiding the treatment of infectious diseases.

Avicularin alleviates acute liver failure by regulation of the TLR4/MyD88/NF-κB and Nrf2/HO-1/GPX4 pathways to reduce inflammation and ferroptosis.

Acute liver failure (ALF) is an inflammation-mediated hepatocyte death process associated with ferroptosis. Avicularin (AL), a Chinese herbal medicine, exerts anti-inflammatory and antioxidative effects. However, the protective effect of AL and the mechanism on ALF have not been reported. Our in vivo results suggest that AL significantly alleviated lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced hepatic pathological injury, liver enzymes, inflammatory cytokines, reactive oxygen species and iron levels and increased the antioxidant enzyme activities (malondialdehyde and glutathione). Our further in vitro experiments demonstrated that AL suppressed inflammatory response in LPS-stimulated RAW 264.7 cells via blocking the toll-like receptor 4 (TLR4)/myeloid differentiation protein-88 (MyD88)/nuclear factor kappa B (NF-κB) pathway. Moreover, AL attenuated ferroptosis in D-GalN-induced HepG2 cells by activating the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1)/glutathione peroxidase 4 (GPX4) pathway. Therefore, AL can alleviate inflammatory response and ferroptosis in LPS/D-GalN-induced ALF, and its protective effects are associated with blocking TLR4/MyD88/NF-κB pathway and activating Nrf2/HO-1/GPX4 pathway. Moreover, AL is a promising therapeutic option for ALF and should be clinically explored.

[Compound Tinglizi Decoction intervenes COPD-associated pulmonary hypertension through regulation of HMGB1-mediated pyroptosis and immune imbalance].

This paper aimed to investigate the effects of high mobility group box 1(HMGB1)-mediated pulmonary artery smooth muscle cell pyroptosis and immune imbalance on chronic obstructive pulmonary disease-associated pulmonary hypertension(COPD-PH) in rats and the intervening mechanism of Compound Tinglizi Decoction. Ninety rats were randomly divided into a normal group, a model group, low-dose, medium-dose, and high-dose Compound Tinglizi Decoction groups, and a simvastatin group. The rat model of COPD-PH was established by fumigation combined with lipopolysaccharide(LPS) intravascular infusion, which lasted 60 days. Rats in the low, medium, and high-dose Compound Tinglizi Decoction groups were given 4.93, 9.87, and 19.74 g·kg~(-1) Compound Tinglizi Decoction by gavage, respectively. Rats in the simvastatin group were given 1.50 mg·kg~(-1) simvastatin by gavage. After 14 days, the lung function, mean pulmonary artery pressure, and arterial blood gas of rats were analyzed. Lung tissues of rats were collected for hematoxylin-eosin(HE) staining to observe the pathological changes. Real-time fluorescent quantitative polymerase chain reaction(qRT-PCR) was used to determine the expression of related mRNA in lung tissues, Western blot(WB) was used to determine the expression of related proteins in lung tissues, and enzyme linked immunosorbent assay(ELISA) was used to determine the levels of inflammatory factors in the lung tissues of rats. The ultrastructure of lung cells was observed by transmission electron microscope. The forced vital capacity(FVC), forced expiratory volume in 0.3 second(FEV_(0.3)), FEV_(0.3)/FVC, peek expiratory flow(PEF), respiratory dynamic compliance(Cdyn), arterial partial pressure of oxygen(PaO_2), and arterial oxygen saturation(SaO_2) were increased, and resistance of expiration(Re), mean pulmonary arterial pressure(mPAP), right ventricular hypertrophy index(RVHI), and arterial partial pressure of carbon dioxide(PaCO_2) were decreased by Compound Tinglizi Decoction in rats with COPD-PH. Compound Tinglizi Decoction inhibited the protein expression of HMGB1, receptor for advanced glycation end products(RAGE), pro caspase-8, cleaved caspase-8, and gasdermin D(GSDMD) in lung tissues of rats with COPD-PH, as well as the mRNA expression of HMGB1, RAGE, and caspase-8. Pulmonary artery smooth muscle cell pyroptosis was inhibited by Compound Tinglizi Decoction. Interferon-γ(IFN-γ) and interleukin-17(IL-17) were reduced, and interleukin-4(IL-4) and interleukin-10(IL-10) were incresead by Compound Tinglizi Decoction in lung tissues of rats with COPD-PH. In addition, the lesion degree of trachea, alveoli, and pulmonary artery in lung tissues of rats with COPD-PH was improved by Compound Tinglizi Decoction. Compound Tinglizi Decoction had dose-dependent effects. The lung function, pulmonary artery pressure, arterial blood gas, inflammation, trachea, alveoli, and pulmonary artery disease have been improved by Compound Tinglizi Decoction, and its mechanism is related to HMGB1-mediated pulmonary artery smooth muscle cell pyroptosis and helper T cell 1(Th1)/helper T cell 2(Th2), helper T cell 17(Th17)/regulatory T cell(Treg) imbalance.

Bioactive polysaccharides promote gut immunity via different ways.

Numerous kinds of bioactive polysaccharides are identified as having intestinal immunomodulatory activity; however, the ways in which the different polysaccharides work differ. Therefore, we selected nine representative bioactive polysaccharides, including xanthan gum, inulin, guar gum, arabinogalactan, carrageenan, glucomannan, araboxylan, xylan, and fucoidan, and compared their intestinal immunomodulatory mechanisms. A cyclophosphamide (CTX)-induced immunosuppressed model was used in this experiment, and the effects of these polysaccharides on the number of T cells in the intestinal mucosa, expression of transcription factors and inflammatory factors, intestinal metabolome and gut microbiota were compared and discussed. The results revealed that the nine polysaccharides promote intestinal immunity in different ways. In detail, guar gum, inulin and glucomannan better alleviated immune suppression in intestinal mucosal T cells. Inulin improved the intestinal microenvironment by significantly upregulating the abundance of Lactobacillus and Monoglobus and promoted short chain fatty acid (SCFA) production. Fucoidan and carrageenan promoted the colonization of the beneficial bacteria Rikenella and Roseburia. In addition, fucoidan, inulin and carrageenan inhibited the colonization of harmful bacteria Helicobacter, upregulated the abundance of Clostridia_UCG-014 and alleviated the accumulation of amino acids, bile acids and indoles in the large intestine. In conclusion, our study uncovered the different intestinal immunomodulatory mechanisms of the different polysaccharides and provided a guideline for the development of superior intestinal immunomodulatory polysaccharides.

Detection of Klebsiella pneumonia DNA and ESBL positive strains by PCR-based CRISPR-LbCas12a system.

Introduction: Klebsiella pneumonia (K. pneumonia) is a Gram-negative bacterium that opportunistically causes nosocomial infections in the lung, bloodstream, and urinary tract. Extended-spectrum ß-Lactamases (ESBLs)-expressed K. pneumonia strains are widely reported to cause antibiotic resistance and therapy failure. Therefore, early identification of K. pneumonia, especially ESBL-positive strains, is essential in preventing severe infections. However, clinical detection of K. pneumonia requires a time-consuming process in agar disk diffusion. Nucleic acid detection, like qPCR, is precise but requires expensive equipment. Recent research reveals that collateral cleavage activity of CRISPR-LbCas12a has been applied in nucleic acid detection, and the unique testing model can accommodate various testing models. Methods: This study established a system that combined PCR with CRISPR-LbCas12a targeting the K. pneumoniae system. Additionally, this study summarized the antibiotic-resistant information of the past five years' K. pneumoniae clinic cases in Luohu Hospital and found that the ESBL-positive strains were growing. This study then designs a crRNA that targets SHV to detect ESBL-resistant K. pneumoniae. This work is to detect K. pneumoniae and ESBL-positive strains' nucleic acid using CRISPR-Cas12 technology. We compared PCR-LbCas12 workflow with PCR and qPCR techniques. Results and Discussion: This system showed excellent detection specificity and sensitivity in both bench work and clinical samples. Due to its advantages, its application can meet different detection requirements in health centers where qPCR is not accessible. The antibiotic-resistant information is valuable for further research.

Innate immune receptors co-recognition of polysaccharides initiates multi-pathway synergistic immune response.

The law and mechanism of the interaction between polysaccharides and pattern recognition receptors (PRRs) has been unclear. Herein, three glucomannans with different structures were selected to explore the universal mechanism for PRRs to recognize glucomannans. Screening results showed that the silence of TLR4 but not TLR2 severely blocked the production of inflammatory cytokines and the transduction of signal pathways. In-depth results revealed that the participation of myeloid differentiation protein 2 (MD2) and CD14 and the dimerization of the TLR4-MD2 complex were required for glucomannan-activated TLR4 signal transduction. Mannose receptor (MR) was also engaged in glucomannan-induced respiratory burst, endocytosis, and inflammatory signaling pathways in a spleen tyrosine kinase-dependent manner. The internalization of glucomannans into the cytoplasm by MR directly initiated complex intracellular signaling cascades. Finally, molecular docking characterized the binding energy and binding sites between glucomannans and multiple receptors from other perspectives. The essence of glucomannans recognized by PRRs was the non-covalent interaction of multiple receptors and the subsequent transmission of the signal cascade was triggered in a multi-channel and cooperative manner. As a result, the hypothesis that "Innate immune receptors co-recognition of polysaccharides initiates multi-pathway synergistic immune response" was proposed to outline these meaningful phenomena.

Interaction between polysaccharides and toll-like receptor 4: Primary structural role, immune balance perspective, and 3D interaction model hypothesis.

Various structural types of polysaccharides are recognized by toll-like receptor 4 (TLR4). However, the mechanism of interaction between the polysaccharides with different structures and TLR4 is unclarified. This review summarized the primary structure of polysaccharides related to TLR4, mainly including molecular weight, monosaccharide composition, glycosidic bonds, functional groups, and branched-chain structure. The optimal primary structure for interacting with TLR4 was obtained by the statistical analysis. Besides, the dual-directional regulation of TLR4 signaling cascade by polysaccharides was also elucidated from an immune balance perspective. Finally, the 3D interaction model of polysaccharides to TLR4-myeloid differentiation factor 2 (MD2) complex was hypothesized according to the LPS-TLR4-MD2 dimerization model and the polysaccharides solution conformation. The essence of polysaccharides binding to TLR4-MD2 complex is a multivalent non-covalent bond interaction. All the arguments summarized in this review are intended to provide some new insights into the interaction between polysaccharides and TLR4.

Comprehensive characterization of glucomannans from different sources to trigger moderate macrophages immune activation.

Macrophage activation is involved in the outcome of many diseases and is recognized as one of the best targets for disease intervention. Glucomannans had shown promising immunomodulatory potential. Herein, the activation performance of macrophages by glucomannans from different sources was thoroughly investigated. Glucomannans triggered the immune activation of macrophages, which was mainly manifested in increasing the secretion of immune effector molecules, enhancing the endocytosis and phagocytosis of macrophages, and selectively facilitating the expression of M1 phenotype. The participation of NF-κB and MAPK signaling pathways further validated the immune activation of macrophages by glucomannans. Correlation analysis indicated acetyl might be a feasible target for glucomannans to induce immune activation and the molecular weight (Mw) of glucomannans was also inseparable from the performance of immune activation. In conclusion, glucomannans showed a moderate immune activation effect on macrophages, and their difference in immune activation was closely related to the acetyl content and Mw.

Multi-omics analysis of m6A modification-related patterns based on m6A regulators and tumor microenvironment infiltration in lung adenocarcinoma.

Epigenetic modifications, especially N6-methyladenosine (m6A) modification, play a key role in tumor microenvironment (TME) infiltration. However, the regulatory role of m6A modification in the TME of lung adenocarcinoma (LUAD) remains unclear. A total of 2506 patients with LUAD were included in the analysis and divided into different groups according to distinct m6A modification-related patterns based on 23 m6A regulators. A comprehensive analysis was performed to explore TME infiltration in different m6A modification-related patterns. Principal component analysis was performed to obtain the m6Ascore and to quantify m6A modification-related patterns in different individuals. Three distinct m6A modification-related patterns were identified by 23 m6A regulators. The pathway enrichment analysis showed that m6Acluster-A was associated with immune activation; m6Acluster-B was associated with carcinogenic activation; m6Acluster-C was prominently related to substance metabolism. M6Acluster-A was remarkably rich in TME-infiltrating immune cells and patients with this pattern showed a survival advantage. The m6Ascore could predict TME infiltration, tumor mutation burden (TMB), the effect of tumor immunotherapy, and the prognosis of patients in LUAD. High m6Ascore was characterized by increased TME infiltration, reduced TMB, and survival advantage. Patients with a high m6Ascore exhibited significantly improved clinical response to anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA4) immunotherapy. This study explored the regulatory mechanisms of TME infiltration in LUAD. The comprehensive analysis of m6A modification-related patterns may contribute to the development of individualized immunotherapy and the improvement of the overall effectiveness of immunotherapy for LUAD patients.

CRISPR-Act3.0 for highly efficient multiplexed gene activation in plants.

RNA-guided CRISPR activation (CRISPRa) systems have been developed in plants. However, the simultaneous activation of multiple genes remains challenging. Here, we develop a highly robust CRISPRa system working in rice, Arabidopsis and tomato, CRISPR-Act3.0, through systematically exploring different effector recruitment strategies and various transcription activators based on deactivated Streptococcus pyogenes Cas9 (dSpCas9). The CRISPR-Act3.0 system results in fourfold to sixfold higher activation than the state-of-the-art CRISPRa systems. We further develop a tRNA-gR2.0 (single guide RNA 2.0) expression system enabling CRISPR-Act3.0-based robust activation of up to seven genes for metabolic engineering in rice. In addition, CRISPR-Act3.0 allows the simultaneous modification of multiple traits in Arabidopsis, which are stably transmitted to the T3 generations. On the basis of CRISPR-Act3.0, we elucidate guide RNA targeting rules for effective transcriptional activation. To target T-rich protospacer adjacent motifs (PAMs), we transfer this activation strategy to CRISPR-dCas12b and further improve the dAaCas12b-based CRISPRa system. Moreover, we develop a potent near-PAM-less CRISPR-Act3.0 system on the basis of the SpRY dCas9 variant, which outperforms the dCas9-NG system in both activation potency and targeting scope. Altogether, our study has substantially improved the CRISPRa technology in plants and provided plant researchers a powerful toolbox for efficient gene activation in foundational and translational research.

Isoprenaline protects intestinal stem cells from chemotherapy-induced damage.

BACKGROUND AND PURPOSE: Damage to intestinal epithelial cells and mucosa limits the effectiveness of several anti-cancer chemotherapeutic agents but the underlying mechanism (s) remain unknown. Little is known of how enteric nervous system regulates proliferation, differentiation, impairment, and regeneration of intestinal stem cells. Here we have investigated the effects of isoprenaline on the damaged intestinal stem cells induced by chemotherapeutic treatments in mice. EXPERIMENTAL APPROACH: The effects of inhibiting sympathetic and parasympathetic nerves on intestinal stem cells were examined in male C57BL/6J mice. Protection by isoprenaline of intestinal stem cells was assessed in the presence or absence of 5-fluorouracil (5FU) or cisplatin. Cellular apoptosis, cell cycle, PI3K/Akt signalling, and NF-κB signalling in intestinal stem cells were mechanistically evaluated. KEY RESULTS: The sympathetic nerve inhibitor 6-OHDA decreased the number and function of intestinal stem cells. 5FU or cisplatin treatment damaged both intestinal stem cells and sympathetic nerves. Notably, isoprenaline accelerated the recovery of intestinal stem cells after 5FU or cisplatin treatment. This protective effect of isoprenaline on damaged intestinal stem cells was mediated by ß2 -adrenoceptors. The benefits of isoprenaline were mainly mediated by inhibiting cellular apoptosis induced by 5FU treatment, which might contribute to fine-tuning regulating NF-κB signalling pathway by isoprenaline administration. CONCLUSIONS AND IMPLICATIONS: Treatment with isoprenaline is a new approach to ameliorate the damage to intestinal stem cells following exposure to cancer chemotherapeutic agents.

Lack of association between ALOX5AP genetic polymorphisms and risk of ischemic stroke: evidence from meta-analyses.

BACKGROUND: In recent years, there has been substantial research evaluating the relationship between arachidonate 5-lipoxygenase-activating protein (ALOX5AP) polymorphisms and ischemic stroke (IS). The objective of this study was to systematically review and analyze the existing evidence. METHODS: A comprehensive search of major electronic databases for studies published between 1990 and 2018 was carried out. Data were synthesized as OR and 95% CI using fixed-effects and random-effects models. RESULTS: A total of 30 studies were available for analysis. The aggregate sample size across all studies was 32,782 (16,294 cases and 16,488 controls). We found no association of the ALOX5AP rs10507391 (OR=1.03 for A allele vs T allele; 95% CI: 0.93-1.14; P=0.557), rs4769874 (OR=1.13 for A allele vs G allele; 95% CI: 1.00-1.28; P=0.050), rs9551963 (OR=1.03 for A allele vs C allele; 95% CI: 0.96-1.11; P=0.372), rs17222814 (OR=1.09 for A allele vs G allele; 95% CI: 0.96-1.24; P=0.195), rs17222919 (OR=0.89 for G allele vs T allele; 95% CI: 0.75-1.06; P=0.175), and rs4073259 (OR=1.20 for A allele vs G allele; 95% CI: 1.00-1.45; P=0.056) polymorphisms with IS risk. Haplotype analysis also did not yield significant findings for the HapA (rs17222814G-rs10507391T-rs4769874G-rs9551963A; OR=1.20; 95% CI: 0.91-1.56; P=0.192) and HapB (rs17216473A-rs10507391A-rs9315050A-rs17222842G; OR=1.11; 95% CI: 0.90-1.38; P=0.339) haplotypes. CONCLUSION: Current evidence does not support an association of rs10507391, rs4769874, rs9551963, rs17222814, rs17222919, rs4073259, and HapA and HapB with IS risk.

Transient Inhibition of mTORC1 Signaling Ameliorates Irradiation-Induced Liver Damage.

Recurrent liver cancer after surgery is often treated with radiotherapy, which induces liver damage. It has been documented that activation of the TGF-ß and NF-κB signaling pathways plays important roles in irradiation-induced liver pathologies. However, the significance of mTOR signaling remains undefined after irradiation exposure. In the present study, we investigated the effects of inhibiting mTORC1 signaling on irradiated livers. Male C57BL/6J mice were acutely exposed to 8.0 Gy of X-ray total body irradiation and subsequently treated with rapamycin. The effects of rapamycin treatment on irradiated livers were examined at days 1, 3, and 7 after exposure. The results showed that 8.0 Gy of irradiation resulted in hepatocyte edema, hemorrhage, and sinusoidal congestion along with a decrease of ALB expression. Exposure of mice to irradiation significantly activated the mTORC1 signaling pathway determined by pS6 and p-mTOR expression via western blot and immunostaining. Transient inhibition of mTORC1 signaling by rapamycin treatment consistently accelerated liver recovery from irradiation, which was evidenced by decreasing sinusoidal congestion and increasing ALB expression after irradiation. The protective role of rapamycin on irradiated livers might be mediated by decreasing cellular apoptosis and increasing autophagy. These data suggest that transient inhibition of mTORC1 signaling by rapamycin protects livers against irradiation-induced damage.

1,2-Bis[(2-hydr-oxy-3-methoxy-benzyl-idene)hydrazono]-1,2-diphenyl-ethane.

The title compound, C(30)H(26)N(4)O(4), was synthesized by the reaction of benzyl dihydrazone and 2-hydr-oxy-3-methoxy-benzaldehyde in ethanol. In the crystal strucutre, the mol-ecule is centrosymmetric. The structure displays two symmetry-related intra-molecular O-H⋯N hydrogen bonds.

Inhibition of mTORC1 signaling protects kidney from irradiation-induced toxicity via accelerating recovery of renal stem-like cells.

BACKGROUND: Irradiation-induced kidney damage is inevitable during radiotherapeutic practice, which limits effective radiotherapy doses on tumor treatment. In the present study, the role of mTOR complex 1 (mTORC1) signaling was investigated in irradiation-induced renal injuries. METHODS: Mice were exposed to 8.0-Gy X-ray of total body irradiation and subsequently treated with rapamycin. Changes of renal morphology were assessed by hematoxylin and eosin staining. Expression of pS6 and CD133 was detected via immunostaining. Cellular apoptosis and proliferation were measured by TUNEL, caspase-3 and BrdU staining. Activation of mTORC1, TGF-ß and NF-κB signaling pathways was determined through western blot analysis. RESULTS: Our data displayed that irradiation disrupted the structures of renal corpuscles and tubules and decreased the density of CD133+ renal stem-like cells, which were related with increasing cellular apoptosis and decreasing cell proliferation post exposure. Activation of mTORC1, TGF-ß and NF-κB signaling pathways was determined in irradiated renal tissues, which were inhibited by rapamycin treatment. Application of rapamycin after irradiation decreased cellular apoptosis and increased autophagy and cell proliferation in renal tissues. The density of CD133+ renal stem-like cells was significantly increased in irradiated kidneys after rapamycin treatment. The morphology of irradiated renal corpuscles and tubules was gradually recovered upon rapamycin treatment. CONCLUSIONS: These findings indicate that inhibition of mTORC1 signaling by rapamycin ameliorates irradiation-induced renal toxicity mediated by decreasing cellular apoptosis and increasing CD133+ renal stem-like cells.