Effects of RhebL1 silencing on the mTOR pathway

Machine learning and bioinformatics-based insights into the potential targets of saponins in Paris polyphylla smith against non-small cell lung cancer

Background: Lung cancer has the highest mortality rate among cancers worldwide, and non-small cell lung cancer (NSCLC) is the major lethal factor. Saponins in Paris polyphylla smith exhibit antitumor activity against non-small cell lung cancer, but their targets are not fully understood.

Methods: In this study, we used differential gene analysis, lasso regression analysis and support vector machine recursive feature elimination (SVM-RFE) to screen potential key genes for NSCLC by using relevant datasets from the GEO database. The accuracy of the signature genes was verified by using ROC curves and gene expression values. Screening of potential active ingredients for the treatment of NSCLC by molecular docking of the reported active ingredients of saponins in Paris polyphylla Smith with the screened signature genes. The activity of the screened components and their effects on key genes expression were further validated by CCK-8, flow cytometry (apoptosis and cycling) and qPCR.

Results: 204 differential genes and two key genes (RHEBL1, RNPC3) stood out in the bioinformatics analysis. Overall survival (OS), First-progression survival (FP) and post-progression survival (PPS) analysis revealed that low expression of RHEBL1 and high expression of RNPC3 indicated good prognosis. In addition, Polyphyllin VI(PPVI) and Protodioscin (Prot) effectively inhibited the proliferation of non-small cell lung cancer cell line with IC50 of 4.46 μM ± 0.69 μM and 8.09 μM ± 0.67μM, respectively. The number of apoptotic cells increased significantly with increasing concentrations of PPVI and Prot. Prot induces G1/G0 phase cell cycle arrest and PPVI induces G2/M phase cell cycle arrest. After PPVI and Prot acted on this cell line for 48 h, the expression of RHEBL1 and RNPC3 was found to be consistent with the results of bioinformatics analysis.

Conclusion: This study identified two potential key genes (RHEBL1 and RNPC3) in NSCLC. Additionally, PPVI and Prot may act on RHEBL1 and RNPC3 to affect NSCLC. Our findings provide a reference for clinical treatment of NSCLC.

Novel Risk Loci Associated With Genetic Risk for Bipolar Disorder Among Han Chinese Individuals: A Genome-Wide Association Study and Meta-analysis

IMPORTANCE

The genetic basis of bipolar disorder (BD) in Han Chinese individuals is not fully understood.

OBJECTIVE

To explore the genetic basis of BD in the Han Chinese population.

DESIGN, SETTING, AND PARTICIPANTS

A genome-wide association study (GWAS), followed by independent replication, was conducted to identify BD risk loci in Han Chinese individuals. Individuals with BD were diagnosed based on DSM-IV criteria and had no history of schizophrenia, mental retardation, or substance dependence; individuals without any personal or family history of mental illnesses, including BD, were included as control participants. In total, discovery samples from 1822 patients and 4650 control participants passed quality control for the GWAS analysis. Replication analyses of samples from 958 patients and 2050 control participants were conducted. Summary statistics from the European Psychiatric Genomics Consortium 2 (PGC2) BD GWAS (20 352 cases and 31 358 controls) were used for the trans-ancestry genetic correlation analysis, polygenetic risk score analysis, and meta-analysis to compare BD genetic risk between Han Chinese and European individuals. The study was performed in February 2020.

MAIN OUTCOMES AND MEASURES

Single-nucleotide variations with P < 5.00 × 10-8 were considered to show genome-wide significance of statistical association.

RESULTS

The Han Chinese discovery GWAS sample included 1822 cases (mean [SD] age, 35.43 [14.12] years; 838 [46%] male) and 4650 controls (mean [SD] age, 27.48 [5.97] years; 2465 [53%] male), and the replication sample included 958 cases (mean [SD] age, 37.82 [15.54] years; 412 [43%] male) and 2050 controls (mean [SD] age, 27.50 [6.00] years; 1189 [58%] male). A novel BD risk locus in Han Chinese individuals was found near the gene encoding transmembrane protein 108 (TMEM108, rs9863544; P = 2.49 × 10-8; odds ratio [OR], 0.650; 95% CI, 0.559-0.756), which is required for dendritic spine development and glutamatergic transmission in the dentate gyrus. Trans-ancestry genetic correlation estimation (ρge = 0.652, SE = 0.106; P = 7.30 × 10-10) and polygenetic risk score analyses (maximum liability-scaled Nagelkerke pseudo R2 = 1.27%; P = 1.30 × 10-19) showed evidence of shared BD genetic risk between Han Chinese and European populations, and meta-analysis identified 2 new GWAS risk loci near VRK2 (rs41335055; P = 4.98 × 10-9; OR, 0.849; 95% CI, 0.804-0.897) and RHEBL1 (rs7969091; P = 3.12 × 10-8; OR, 0.932; 95% CI, 0.909-0.956).

CONCLUSIONS AND RELEVANCE

This GWAS study identified several loci and genes involved in the heritable risk of BD, providing insights into its genetic architecture and biological basis.

Whole-Genome and RNA Sequencing Reveal Variation and Transcriptomic Coordination in the Developing Human Prefrontal Cortex

Gene expression levels vary across developmental stage, cell type, and region in the brain. Genomic variants also contribute to the variation in expression, and some neuropsychiatric disorder loci may exert their effects through this mechanism. To investigate these relationships, we present BrainVar, a unique resource of paired whole-genome and bulk tissue RNA sequencing from the dorsolateral prefrontal cortex of 176 individuals across prenatal and postnatal development. Here we identify common variants that alter gene expression (expression quantitative trait loci [eQTLs]) constantly across development or predominantly during prenatal or postnatal stages. Both "constant" and "temporal-predominant" eQTLs are enriched for loci associated with neuropsychiatric traits and disorders and colocalize with specific variants. Expression levels of more than 12,000 genes rise or fall in a concerted late-fetal transition, with the transitional genes enriched for cell-type-specific genes and neuropsychiatric risk loci, underscoring the importance of cataloging developmental trajectories in understanding cortical physiology and pathology.

Activation of the mammalian target of rapamycin signaling pathway underlies a novel inhibitory role of ring finger protein 182 in ventricular remodeling after myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a major cause of cardiovascular disease, leading to mortality and disability associated with coronary occlusion worldwide. A correlation of mammalian target of rapamycin (mTOR)/nuclear factor-kappa B (NF-κB) signaling pathway has been observed with brain damage resulting from myocardial ischemia. Therefore, by establishing MIRI rat model, this study aimed to explore whether ring finger protein 182 (RNF182) regulates the mTOR signaling pathway affecting MIRI. Initially, MIRI rat model was successfully established, followed by either treatment of shRNF182 or phosphoesterase (PITE) (inhibitor of the mTOR signaling pathway). Then, the serum levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular systolic pressure (LVSP), and left ventricular end-diastolic pressure (LVEDP) were determined, followed by detection of myocardial infarct sizes and myocardial cell apoptosis. Moreover, the levels of related genes/proteins were determined to further determine the mechanisms of RNF182 in MIRI. First, RNF182 was upregulated in MIRI. Another key observation of this study was that rats with shRNF182 presented with downregulated SOD, GSH-Px, and MDA in serum, accompanied by decreased levels of LVEF, LVFS, LVSP, and LVEDP. In addition, both reduced myocardial infarct sizes and apoptosis of myocardial cells were observed after silencing RNF182. Furthermore, silencing of the RNF182 was observed to downregulate Bcl 2-associated X and cysteine proteinase 3 but upregulate mTOR, ribosome protein subunit 6 kinase 1, eukaryotic elongation factor 2, and B-cell lymphoma-2. Importantly, the effects of RNF182 silencing were reversed after PITE treatment. In conclusion, our study demonstrates that RNF182 silencing can prevent ventricular remodeling in rats after MIRI by activating the mTOR signaling pathway.

TIM-3 Engagement Promotes Effector Memory T Cell Differentiation of Human Antigen-Specific CD8 T Cells by Activating mTORC1

T cell expression of TIM-3 following Ag encounter has been associated with a continuum of functional states ranging from effector memory T cells to exhaustion. We have designed an in vitro culture system to specifically address the impact of anti-TIM-3/TIM-3 engagement on human Ag-specific CD8 T cells during a normal response to Ag and found that anti-TIM-3 treatment enhances T cell function. In our in vitro T cell culture system, MART1-specific CD8 T cells were expanded from healthy donors using artificial APCs. To ensure that the T cells were the only source of TIM-3, cells were rechallenged with peptide-loaded artificial APCs in the presence of anti-TIM-3 Ab. In these conditions, anti-TIM-3 treatment promotes generation of effector T cells as shown by acquisition of an activated phenotype, increased cytokine production, enhanced proliferation, and a transcription program associated with T cell differentiation. Activation of mTORC1 has been previously demonstrated to enhance CD8 T cell effector function and differentiation. Anti-TIM-3 drives CD8 T cell differentiation through activation of the mTORC1 as evidenced by increased levels of phosphorylated S6 protein and rhebl1 transcript. Altogether these findings suggest that anti-TIM-3, together with Ag, drives differentiation in favor of effector T cells via the activation of mTOR pathway. To our knowledge, this is the first report demonstrating that TIM-3 engagement during Ag stimulation directly influences T cell differentiation through mTORC1.

Influence of miR-155 on Cell Apoptosis in Rats with Ischemic Stroke: Role of the Ras Homolog Enriched in Brain (Rheb)/mTOR Pathway

Background

We designed and carried out this study to examine the role of miR-155 and the Rheb/mTOR pathway in ischemic stroke. We also investigated how these two elements interact with each other and contribute to injuries resulting from ischemic stroke.

Material/Methods

We used both a middle cerebral artery occlusion rat model in vivo and an oxygen-glucose deprivation cell model in vitro to simulate the onset of ischemic stroke. miR-155 mimics, miR-155 inhibitors, and Rheb siRNA were transfected to alter the expression of miR-155 and Rheb. Infarct sizes were measured using magnetic resonance imaging (MRI) and triphenyltetrazolium chloride (TTC) staining; cell apoptosis rates were calculated using Annexin V-FITC/PI staining and flow cytometry. Levels of miR-155, Rheb, mTOR, and S6K were examined by RT-PCR, immunofluorescence, and western blot. We performed a luciferase activity assay so that the association between miR-155 and Rheb could be fully assessed.

Results

We demonstrated that miR-155 bound the 3′-UTR of Rheb and suppressed Rheb expression. As suggested by animal models, significant cerebral infarct volumes and cell apoptosis were induced by increased expression of miR-155 and decreased expression of Rheb, mTOR, and p-S6K (P<0.05). miR-155 inhibitors exhibited protective effects on ischemic stroke, including down-regulation of infarction size in cerebral tissues in vivo and reduced apoptosis of BV2 cells in vitro with increased expression of Rheb, mTOR and p-S6K (P<0.05). These protective effects could be substantially antagonized by the transfection of Rheb siRNA (P<0.05).

Conclusions

Inhibition of miR-155 may play protective roles in ischemic stroke by phosphorylating S6K through the Rheb/mTOR pathway.

IFN-γ orchestrates mesenchymal stem cell plasticity through the signal transducer and activator of transcription 1 and 3 and mammalian target of rapamycin pathways

BACKGROUND

Mesenchymal stem cells (MSCs) display a therapeutic plasticity because of their ability to modulate immunity, foster tissue repair, and differentiate into mesodermal cells. IFN-γ has been described to differently affect human mesenchymal stem cell (hMSC) and mouse mesenchymal stem cell (mMSC) immunomodulation and differentiation, depending on the inflammatory milieu.

OBJECTIVE

We aimed at dissecting the relevant intracellular pathways through which IFN-γ affects MSC plasticity and the consequence of their manipulation on MSC functions.

METHODS

Modification of relevant IFN-γ-dependent pathways in mMSCs was carried out in vitro through gene silencing or chemical inhibition of key components. Functional outcomes were assessed by means of Western blotting, real-time PCR, differentiation, and proliferation assays on MSCs. The effect on T cells was addressed by T-cell proliferation assays; the effect of mammalian target of rapamycin (mTOR) manipulation in MSCs was studied in vivo in a mouse model of delayed-type hypersensitivity assay. To address whether similar mechanisms are involved also in hMSCs on IFN-γ stimulation, the effect of chemical inhibition on the same intracellular pathways was assessed by means of Western blotting, and the final outcome on immunomodulatory properties was evaluated based on real-time PCR and T-cell proliferation.

RESULTS

We revealed that in mMSCs IFN-γ-induced immunoregulation is mediated by early phosphorylation of signal transducer and activator of transcription (STAT) 1 and STAT3, which is significantly enhanced by an extracellular signal-regulated kinase 1/2-dependent mTOR inhibition, thereby promoting pSTAT1 nuclear translocation. Accordingly, after intracellular mTOR inhibition, MSCs augmented their ability to inhibit T-cell proliferation and control delayed-type hypersensitivity in vivo. Similarly, on mTOR blockade, hMSCs also enhanced their immunoregulatory features. A sustained exposure to IFN-γ led to inhibition of STAT3 activity, which in mMSCs resulted in an impaired proliferation and differentiation.

CONCLUSION

These results provide new insights about MSC intracellular pathways affected by IFN-γ, demonstrating that pharmacologic or genetic manipulation of MSCs can enhance their immunomodulatory functions, which could be translated into novel therapeutic approaches.

Direct Interaction between Ras Homolog Enriched in Brain and FK506 Binding Protein 38 in Cashmere Goat Fetal Fibroblast Cells

Ras homolog enriched in brain (Rheb) and FK506 binding protein 38 (FKBP38) are two important regulatory proteins in the mammalian target of rapamycin (mTOR) pathway. There are contradictory data on the interaction between Rheb and FKBP38 in human cells, but this association has not been examined in cashmere goat cells. To investigate the interaction between Rheb and FKBP38, we overexpressed goat Rheb and FKBP38 in goat fetal fibroblasts, extracted whole proteins, and performed coimmunoprecipitation to detect them by western blot. We found Rheb binds directly to FKBP38. Then, we constructed bait vectors (pGBKT7-Rheb/FKBP38) and prey vectors (pGADT7-Rheb/FKBP38), and examined their interaction by yeast two-hybrid assay. Their direct interaction was observed, regardless of which plasmid served as the prey or bait vector. These results indicate that the 2 proteins interact directly in vivo. Novel evidence is presented on the mTOR signal pathway in Cashmere goat cells.