Genome-wide profiling of prime editor off-target sites in vitro and in vivo using PE-tag.

Prime editors have a broad range of potential research and clinical applications. However, methods to delineate their genome-wide editing activities have generally relied on indirect genome-wide editing assessments or the computational prediction of near-cognate sequences. Here we describe a genome-wide approach for the identification of potential prime editor off-target sites, which we call PE-tag. This method relies on the attachment or insertion of an amplification tag at sites of prime editor activity to allow their identification. PE-tag enables genome-wide profiling of off-target sites in vitro using extracted genomic DNA, in mammalian cell lines and in the adult mouse liver. PE-tag components can be delivered in a variety of formats for off-target site detection. Our studies are consistent with the high specificity previously described for prime editor systems, but we find that off-target editing rates are influenced by prime editing guide RNA design. PE-tag represents an accessible, rapid and sensitive approach for the genome-wide identification of prime editor activity and the evaluation of prime editor safety.

Transcriptional suppression of sphingolipid catabolism controls pathogen resistance in C. elegans.

Sphingolipids are required for diverse biological functions and are degraded by specific catabolic enzymes. However, the mechanisms that regulate sphingolipid catabolism are not known. Here we characterize a transcriptional axis that regulates sphingolipid breakdown to control resistance against bacterial infection. From an RNAi screen for transcriptional regulators of pathogen resistance in the nematode C. elegans, we identified the nuclear hormone receptor nhr-66, a ligand-gated transcription factor homologous to human hepatocyte nuclear factor 4. Tandem chromatin immunoprecipitation-sequencing and RNA sequencing experiments revealed that NHR-66 is a transcriptional repressor, which directly targets sphingolipid catabolism genes. Transcriptional de-repression of two sphingolipid catabolic enzymes in nhr-66 loss-of-function mutants drives the breakdown of sphingolipids, which enhances host susceptibility to infection with the bacterial pathogen Pseudomonas aeruginosa. These data define transcriptional control of sphingolipid catabolism in the regulation of cellular sphingolipids, a process that is necessary for pathogen resistance.

Precise therapeutic gene correction by a simple nuclease-induced double-stranded break.

Current programmable nuclease-based methods (for example, CRISPR-Cas9) for the precise correction of a disease-causing genetic mutation harness the homology-directed repair pathway. However, this repair process requires the co-delivery of an exogenous DNA donor to recode the sequence and can be inefficient in many cell types. Here we show that disease-causing frameshift mutations that result from microduplications can be efficiently reverted to the wild-type sequence simply by generating a DNA double-stranded break near the centre of the duplication. We demonstrate this in patient-derived cell lines for two diseases: limb-girdle muscular dystrophy type 2G (LGMD2G)1 and Hermansky-Pudlak syndrome type 1 (HPS1)2. Clonal analysis of inducible pluripotent stem (iPS) cells from the LGMD2G cell line, which contains a mutation in TCAP, treated with the Streptococcus pyogenes Cas9 (SpCas9) nuclease revealed that about 80% contained at least one wild-type TCAP allele; this correction also restored TCAP expression in LGMD2G iPS cell-derived myotubes. SpCas9 also efficiently corrected the genotype of an HPS1 patient-derived B-lymphoblastoid cell line. Inhibition of polyADP-ribose polymerase 1 (PARP-1) suppressed the nuclease-mediated collapse of the microduplication to the wild-type sequence, confirming that precise correction is mediated by the microhomology-mediated end joining (MMEJ) pathway. Analysis of editing by SpCas9 and Lachnospiraceae bacterium ND2006 Cas12a (LbCas12a) at non-pathogenic 4-36-base-pair microduplications within the genome indicates that the correction strategy is broadly applicable to a wide range of microduplication lengths and can be initiated by a variety of nucleases. The simplicity, reliability and efficacy of this MMEJ-based therapeutic strategy should permit the development of nuclease-based gene correction therapies for a variety of diseases that are associated with microduplications.

Reducing the inherent auto-inhibitory interaction within the pegRNA enhances prime editing efficiency.

Prime editing systems have enabled the incorporation of precise edits within a genome without introducing double strand breaks. Previous studies defined an optimal primer binding site (PBS) length for the pegRNA of ∼13 nucleotides depending on the sequence composition. However, optimal PBS length characterization has been based on prime editing outcomes using plasmid or lentiviral expression systems. In this study, we demonstrate that for prime editor (PE) ribonucleoprotein complexes, the auto-inhibitory interaction between the PBS and the spacer sequence affects pegRNA binding efficiency and target recognition. Destabilizing this auto-inhibitory interaction by reducing the complementarity between the PBS-spacer region enhances prime editing efficiency in multiple prime editing formats. In the case of end-protected pegRNAs, a shorter PBS length with a PBS-target strand melting temperature near 37°C is optimal in mammalian cells. Additionally, a transient cold shock treatment of the cells post PE-pegRNA delivery further increases prime editing outcomes for pegRNAs with optimized PBS lengths. Finally, we show that prime editor ribonucleoprotein complexes programmed with pegRNAs designed using these refined parameters efficiently correct disease-related genetic mutations in patient-derived fibroblasts and efficiently install precise edits in primary human T cells and zebrafish.

Photomechaelectric Nanogenerators with Different Photoisomers and Dipole Units for Harvesting UV Light Energy.

To date, transforming environmental energy into electricity through a non-mechanical way is challenging. Herein, a series of photomechaelectric (PME) polyurethanes containing azobenzene-based photoisomer units and ionic liquid-based dipole units are synthesized, and corresponding PME nanogenerators (PME-NGs) to harvest electricity are fabricated. The dependence of the output performance of PME-NGs on the structure of the polyurethane is evaluated. The results show that the UV light energy can directly transduce into alternating-current (AC) electricity by PME-NGs via a non-mechanical way. The optimal open-circuit voltage and short-circuit current of PME-NGs under UV illumination reach 17.4 V and 696 µA, respectively. After rectification, the AC electricity can be further transformed into direct-current (DC) electricity and stored in a capacitor to serve as a power system to actuate typical microelectronics. The output performance of PME-NGs is closely related to the hard segment content of the PME polyurethane and the radius of counter anions in the dipole units. Kelvin probe force microscopy is used to confirm the existence of the PME effect and the detailed mechanism about the generation of AC electricity in PME-NGs is proposed, referring to the back and forth drift of induced electrons on the two electrodes in contact with the PME polyurethanes.

MicroRNA-431-5p inhibits angiogenesis, lymphangiogenesis, and lymph node metastasis by affecting TGF-ß1/SMAD2/3 signaling via ZEB1 in gastric cancer.

Accumulating evidence suggests that lymphangiogenesis plays a crucial role in lymphatic metastasis, leading to tumor immune tolerance. However, the specific mechanism remains unclear. In this study, miR-431-5p was markedly downregulated in both gastric cancer (GC) tissues and plasma exosomes, and its expression were correlated negatively with LN metastasis and poor prognosis. Mechanistically, miR-431-5p weakens the TGF-ß1/SMAD2/3 signaling pathway by targeting ZEB1, thereby suppressing the secretion of VEGF-A and ANG2, which in turn hinders angiogenesis, lymphangiogenesis, and lymph node (LN) metastasis in GC. Experiments using a popliteal LN metastasis model in BALB/c nude mice demonstrated that miR-431-5p significantly reduced popliteal LN metastasis. Additionally, miR-431-5p enhances the efficacy of anti-PD1 treatment, particularly when combined with galunisertib, anti-PD1 treatment showing a synergistic effect in inhibiting GC progression in C57BL/6 mice. Collectively, these findings suggest that miR-431-5p may modulate the TGF-ß1/SMAD2/3 pathways by targeting ZEB1 to impede GC progression, angiogenesis, and lymphangiogenesis, making it a promising therapeutic target for GC management.

Prediction of occult peritoneal metastases or positive cytology using CT in gastric cancer.

OBJECTIVE: Accurate prediction of preoperative occult peritoneal metastasis (OPM) is critical to selecting appropriate therapeutic regimen for gastric cancer (GC). Considering the clinical practicability, we develop and validate a visible nomogram that integrates the CT images and clinicopathological parameters for the individual preoperative prediction of OPM in GC. METHODS: This retrospective study included 520 patients who underwent staged laparoscopic exploration or peritoneal lavage cytology (PLC) examination. Univariate and multivariate logistic regression results were used to screen model predictors and construct nomograms of OPM risk. The performance of the model was detected by using ROC, accuracy, and C-index. The bootstrap resampling method was considered internal validation of the model. The Delong test was used to evaluate the difference in AUC between the two models. RESULTS: Grade 2 mural stratification, tumor thickness, and the Lauren classification diffuse were significant predictors of OPM (p < 0.05). The nomogram of these three factors (compared with the original model) showed a higher predictive effect (p < 0.001). The area under the curve (AUC) of the model was 0.830 (95% CI 0.788-0.873), and the internally validated AUC of 1000 bootstrap samples was 0.826 (95% CI 0.756-0.870). The sensitivity, specificity, and accuracy were 76.0%, 78.8%, and 78.3%, respectively. CONCLUSIONS: CT phenotype-based nomogram demonstrates favorable discrimination and calibration, and it can be conveniently used for preoperative individual risk rating of OPM in GC. CLINICAL RELEVANCE STATEMENT: In this study, the preoperative OPM prediction model based on CT images (mural stratification, tumor thickness) combined with pathological parameters (the Lauren classification) showed excellent predictive ability in GC, and it is also suitable for clinicians to use rather than limited to professional radiologists. KEY POINTS: • Nomogram based on CT image analysis can effectively predict occult peritoneal metastasis in gastric cancer (training area under the curve (AUC) = 0.830 and bootstrap AUC = 0.826). • Nomogram model combined with CT features performed better than the original model (established using only clinicopathological parameters) in differentiating occult peritoneal metastasis of gastric cancer.

A flexible split prime editor using truncated reverse transcriptase improves dual-AAV delivery in mouse liver.

Prime editor (PE) has tremendous promise for gene therapy. However, it remains a challenge to deliver PE (>6.3 kb) in vivo. Although PE can be split into two fragments and delivered using dual adeno-associated viruses (AAVs), choice of split sites within Cas9-which affects editing efficiency-is limited due to the large size of PE. Furthermore, overexpressing reverse transcriptase in mammalian cells might disrupt translation termination via its RNase H domain. Here, we developed a compact PE without the RNase H domain that showed editing comparable with full-length PE. With compact PE, we used a Cas9 split site (Glu 573) that supported robust editing in cells (up to 93% of full-length PE) and in mouse liver. We then demonstrated that split-cPE573 delivered by dual-AAV8 efficiently mediated a 3-bp TGA insertion in the Pcsk9 gene in mouse liver. Compact PE without the RNase H domain abolished its binding to peptidyl release factor 1 (eRF1) and mitigated the stop codon readthrough effect observed with full-length PE. This study identifies a compact PE with a flexible split design to advance utility of prime editing in vivo.

LINE-1 promotes tumorigenicity and exacerbates tumor progression via stimulating metabolism reprogramming in non-small cell lung cancer.

BACKGROUND: Long Interspersed Nuclear Element-1 (LINE-1, L1) is increasingly regarded as a genetic risk for lung cancer. Transcriptionally active LINE-1 forms a L1-gene chimeric transcript (LCTs), through somatic L1 retrotransposition (LRT) or L1 antisense promoter (L1-ASP) activation, to play an oncogenic role in cancer progression. METHODS: Here, we developed Retrotransposon-gene fusion estimation program (ReFuse), to identify and quantify LCTs in RNA sequencing data from TCGA lung cancer cohort (n = 1146) and a single cell RNA sequencing dataset then further validated those LCTs in an independent cohort (n = 134). We next examined the functional roles of a cancer specific LCT (L1-FGGY) in cell proliferation and tumor progression in LUSC cell lines and mice. RESULTS: The LCT events correspond with specific metabolic processes and mitochondrial functions and was associated with genomic instability, hypomethylation, tumor stage and tumor immune microenvironment (TIME). Functional analysis of a tumor specific and frequent LCT involving FGGY (L1-FGGY) reveal that the arachidonic acid (AA) metabolic pathway was activated by the loss of FGGY through the L1-FGGY chimeric transcript to promote tumor growth, which was effectively targeted by a combined use of an anti-HIV drug (NVR) and a metabolic inhibitor (ML355). Lastly, we identified a set of transcriptomic signatures to stratify the LUSC patients with a higher risk for poor outcomes who may benefit from treatments using NVR alone or combined with an anti-metabolism drug. CONCLUSIONS: This study is the first to characterize the role of L1 in metabolic reprogramming of lung cancer and provide rationale for L1-specifc prognosis and potential for a therapeutic strategy for treating lung cancer. TRIAL REGISTRATION: Study on the mechanisms of the mobile element L1-FGGY promoting the proliferation, invasion and immune escape of lung squamous cell carcinoma through the 12-LOX/Wnt pathway, Ek2020111. Registered 27 March 2020 - Retrospectively registered.

Nivolumab treatment of relapsed/refractory Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in adults.

Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a life-threatening hyperinflammatory syndrome triggered by EBV infection. It often becomes relapsed or refractory (r/r), given that etoposide-based regimens cannot effectively clear the virus. r/r EBV-HLH is invariably lethal in adults without allogeneic hematopoietic stem cell transplantation. Here, we performed a retrospective analysis of 7 r/r EBV-HLH patients who were treated with nivolumab on a compassionate-use basis at West China Hospital. All 7 patients tolerated the treatment and 6 responded to it. Five of them achieved and remained in clinical complete remission with a median follow-up of 16 months (range, 11.4-18.9 months). Importantly, both plasma and cellular EBV-DNAs were completely eradicated in 4 patients. Single-cell RNA-sequencing analysis showed that HLH syndrome was associated with hyperactive monocytes/macrophages and ineffective CD8 T cells with a defective activation program. Nivolumab treatment expanded programmed death protein-1-positive T cells and restored the expression of HLH-associated degranulation and costimulatory genes in CD8 T cells. Our data suggest that nivolumab, as a monotherapy, provides a potential cure for r/r EBV-HLH, most likely by restoring a defective anti-EBV response.

Combined systemic immune-inflammatory index (SII) and prognostic nutritional index (PNI) predicts chemotherapy response and prognosis in locally advanced gastric cancer patients receiving neoadjuvant chemotherapy with PD-1 antibody sintilimab and XELOX: a prospective study.

BACKGROUND: Previous studies have confirmed that systemic immune-inflammatory index (SII) and prognostic nutritional index (PNI) can predict the prognosis and chemotherapy efficacy of various malignant tumors. However, to the best of our knowledge, no study investigated the SII combined with PNI score to predict the efficacy of anti-programmed death 1 (anti-PD-1) antibody sintilimab and XELOX regimen (capecitabine plus oxaliplatin) in the treatment of locally advanced gastric cancer. This study aims to evaluate the predictive value of pre-treatment SII-PNI score on the sensitivity of sintilimab immunotherapy combined with XELOX chemotherapy in patients with locally advanced gastric cancer. METHODS: We registered a prospective clinical study involving 30 locally advanced gastric cancer patients from March 2020 to July 2021. The pre-treatment SII and PNI were calculated from peripheral blood samples, and the cut-off value was calculated by receiver operating characteristic. The SII-PNI score ranged from 0 to 2 and were categorized into the following: score of 2, high SII (≥ 568.5) and low PNI (≤ 52.7); score of 1, either high SII or low PNI; score of 0, no high SII nor low PNI. RESULTS: All patients were evaluated by RECIST1.1 criteria after four cycles of sintilimab immunotherapy combined with XELOX chemotherapy, including 5 patients with TRG 3 and 25 patients with non-TRG 3. The SII-PNI score of non-TRG 3 patients was significantly lower than that of TRG 3 patients (P = 0.017). The medial progression free survival of patients with low SII-PNI score was significantly better than that of patients with high SII-PNI score (P < 0.001). Multivariate analysis showed that SII-PNI score was an independent prognostic factor for predicting progression-free survival (P = 0.003). CONCLUSION: The pre-treatment SII-PNI score is a significant indicator for predicting chemosensitivity of locally advanced patients after sintilimab immunotherapy combined with XELOX chemotherapy, which can help to identify high-risk groups and predict prognosis. TRIAL REGISTRATION: The registered name of the trial is "Prospective clinical study of sintilimab combined with chemotherapy for neoadjuvant therapy in locally advanced gastric cancer". Its Current Controlled Trials number is ChiCTR2000030414. Its date of registration is 01/03/2020.

Imbalance of TGF-ß1/BMP-7 pathways induced by M2-polarized macrophages promotes hepatocellular carcinoma aggressiveness.

The transforming growth factor-beta (TGF-ß) signaling pathway is the predominant cytokine signaling pathway in the development and progression of hepatocellular carcinoma (HCC). Bone morphogenetic protein (BMP), another member of the TGF-ß superfamily, has been frequently found to participate in crosstalk with the TGF-ß pathway. However, the complex interaction between the TGF-ß and BMP pathways has not been fully elucidated in HCC. We found that the imbalance of TGF-ß1/BMP-7 pathways was associated with aggressive pathological features and poor clinical outcomes in HCC. The induction of the imbalance of TGF-ß1/BMP-7 pathways in HCC cells could significantly promote HCC cell invasion and stemness by increasing inhibitor of differentiation 1 (ID1) expression. We also found that the microRNA (miR)-17-92 cluster, originating from the extracellular vesicles (EVs) of M2-polarized tumor-associated macrophages (M2-TAMs), stimulated the imbalance of TGF-ß1/BMP-7 pathways in HCC cells by inducing TGF-ß type II receptor (TGFBR2) post-transcriptional silencing and inhibiting activin A receptor type 1 (ACVR1) post-translational ubiquitylation by targeting Smad ubiquitylation regulatory factor 1 (Smurf1). In vivo, short hairpin (sh)-MIR17HG and ACVR1 inhibitors profoundly attenuated HCC cell growth and metastasis by rectifying the imbalance of TGF-ß1/BMP-7 pathways. Therefore, we proposed that the imbalance of TGF-ß1/BMP-7 pathways is a feasible prognostic biomarker and recovering the imbalance of TGF-ß1/BMP-7 pathways might be a potential therapeutic strategy for HCC.

Platelet-neutrophil hybrid membrane-coated gelatin nanoparticles for enhanced targeting ability and intelligent release in the treatment of non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is the major form of chronic liver disease in adults; however, there are no approved drugs for NASH. In this study, we designed the PNM-G-PV method, in which gelatin nanoparticles (G) are loaded with pioglitazone and vitamin E (G-PV) and then encapsulated by the surfaces of platelet-neutrophil hybrid membranes (PNM). Inherited from the natural source cells, the PNM show immune evading ability due to the surface marker comprising a number of "do not eat me" signals and has dual inflammatory enrichment capabilities due to specific surface adhesion molecules. By functionalizing the gelatin nanoparticle biomimetic surfaces, PNM-G can enhance the targeting to inflammatory sites and enrich liver tissue. The high expression of matrix metalloproteinase-9 (MMP-9) at the NASH site enables the gelatin nanoparticles to intelligently respond to degradation and then release vitamin E and pioglitazone for drug treatment. We performed an in vivo analysis of these nanoparticles to monitor changes in triacylglycerol metabolism in liver tissues and assessed the therapeutic efficacy of PNM-G-PV in a NASH rat model. The results showed that PNM-G-PV exhibited better therapeutic efficacy than therapies using G-PV or PV alone. This work explores a new biomedical use of PNM-G-PV and a promising NASH treatment protocol based on a new drug delivery system.

The nuclear hormone receptor NHR-86 controls anti-pathogen responses in C. elegans.

Nuclear hormone receptors (NHRs) are ligand-gated transcription factors that control adaptive host responses following recognition of specific endogenous or exogenous ligands. Although NHRs have expanded dramatically in C. elegans compared to other metazoans, the biological function of only a few of these genes has been characterized in detail. Here, we demonstrate that an NHR can activate an anti-pathogen transcriptional program. Using genetic epistasis experiments, transcriptome profiling analyses and chromatin immunoprecipitation-sequencing, we show that, in the presence of an immunostimulatory small molecule, NHR-86 binds to the promoters of immune effectors to activate their transcription. NHR-86 is not required for resistance to the bacterial pathogen Pseudomonas aeruginosa at baseline, but activation of NHR-86 by this compound drives a transcriptional program that provides protection against this pathogen. Interestingly, NHR-86 targets immune effectors whose basal regulation requires the canonical p38 MAPK PMK-1 immune pathway. However, NHR-86 functions independently of PMK-1 and modulates the transcription of these infection response genes directly. These findings characterize a new transcriptional regulator in C. elegans that can induce a protective host response towards a bacterial pathogen.

Ferroptosis is partially responsible for dexamethasone-induced T cell ablation, but not osteoporosis in larval zebrafish.

Glucocorticoids (GCs) have been widely detected in the aquatic system. However, the hazardous effects of GCs on aquatic organisms were underestimated, and the mechanisms of GCs-induced toxic effects in fish were largely unknown. The zebrafish larvae at 3 dpf were exposed to dexamethasone (DEX) for 48 h, and the toxic effects and the underlying mechanisms were investigated in the current study. The T cells were ablated in zebrafish larvae after being treated with 1, 3, 10, 30 and 100 µM of DEX for 48 h. In addition, osteoporosis was induced and the regeneration of the caudal fin was inhibited, by 48 h-exposure to 10, 30 and 100 µM of DEX. The transcriptomic analysis, biochemical parameters and gene expression profiles revealed that ferroptosis possibly contributed to the DEX-induced toxic effects in zebrafish larvae. Finally, Fer-1 treatment partially attenuated the DEX-induced T cell ablation, but not osteoporosis in zebrafish larvae. Taken together, the current study proved the toxic effects of DEX on zebrafish larvae, and elucidated that ferroptosis was involved in DEX-induced toxicity, providing strong evidence for the toxic effects of GCs on aquatic organisms.

Assessment of the Seafloor Topography Accuracy in the Emperor Seamount Chain by Ship-Based Water Depth Data and Satellite-Based Gravity Data.

The seafloor topography estimation is very important, while the bathymetry data and gravity data are scarce and uneven, which results in large errors in the inversion of the seafloor topography. In this paper, in order to reduce the influence of errors and improve the accuracy of seafloor inversion, the influence of different resolution data on the inversion topography in the Emperor Seamount Chain are investigated by combining ship water depth data and satellite gravity anomaly data released by SIO V29.1. Through the comparison of different resolution models, it is found that the choice of resolution affects the accuracy of the inversion terrain model. An external comparison is presented by using the international high-precision topography data and check points observations. The results show that with the increase in resolution, the fitting residuals obtained by the scale factor are optimized, and the precision of the terrain model is gradually approaching the S&S V19.1 and GEBCO-2020 models, but is better than the ETOPO1 and SRTM 30 models. By external validation using the check points, the standard deviation of the difference was reduced from 58.92 m to 47.01 m, and the correlation between the inverted terrain and the NGDC grid model was increased from 0.9545 to 0.9953. For recovering the Emperor Seamount Chain terrain, the relative error was gradually decreased with the improvement of resolution. The maximum relative error is reduced from 1.09 of 2' topography to 0.74 of 10″ topography, and the average error is reduced from 0.04 to 0.01 with an improvement by 32.11%. The terrain error between the inverted terrain model and the NGDC grid model is gradually reduced, while the error percentage is increasing by 25.51% and 21.49% in the range of -50 to 50 m and -100 to 100 m, respectively. Furthermore, the sparse area can effectively reduce the terrain standard deviation and improve the terrain correlation by increasing the resolution through the analysis of different density subsets. The error was decreased most significantly in sparse and dense homogeneous regions with increasing resolution.

Tissue-restricted genome editing in vivo specified by microRNA-repressible anti-CRISPR proteins.

CRISPR-Cas systems are bacterial adaptive immune pathways that have revolutionized biotechnology and biomedical applications. Despite the potential for human therapeutic development, there are many hurdles that must be overcome before its use in clinical settings. Some clinical safety concerns arise from editing activity in unintended cell types or tissues upon in vivo delivery (e.g., by adeno-associated virus (AAV) vectors). Although tissue-specific promoters and serotypes with tissue tropisms can be used, suitably compact promoters are not always available for desired cell types, and AAV tissue tropism specificities are not absolute. To reinforce tissue-specific editing, we exploited anti-CRISPR proteins (Acrs) that have evolved as natural countermeasures against CRISPR immunity. To inhibit Cas9 in all ancillary tissues without compromising editing in the target tissue, we established a flexible platform in which an Acr transgene is repressed by endogenous, tissue-specific microRNAs (miRNAs). We demonstrate that miRNAs regulate the expression of an Acr transgene bearing miRNA-binding sites in its 3'-UTR and control subsequent genome editing outcomes in a cell-type specific manner. We also show that the strategy is applicable to multiple Cas9 orthologs and their respective anti-CRISPRs. Furthermore, we validate this approach in vivo by demonstrating that AAV9 delivery of Nme2Cas9, along with an AcrIIC3 Nme construct that is targeted for repression by liver-specific miR-122, allows editing in the liver while repressing editing in an unintended tissue (heart muscle) in adult mice. This strategy provides safeguards against off-tissue genome editing by confining Cas9 activity to selected cell types.

Enhanced Cas12a editing in mammalian cells and zebrafish.

Type V CRISPR-Cas12a systems provide an alternate nuclease platform to Cas9, with potential advantages for specific genome editing applications. Here we describe improvements to the Cas12a system that facilitate efficient targeted mutagenesis in mammalian cells and zebrafish embryos. We show that engineered variants of Cas12a with two different nuclear localization sequences (NLS) on the C terminus provide increased editing efficiency in mammalian cells. Additionally, we find that pre-crRNAs comprising a full-length direct repeat (full-DR-crRNA) sequence with specific stem-loop G-C base substitutions exhibit increased editing efficiencies compared with the standard mature crRNA framework. Finally, we demonstrate in zebrafish embryos that the improved LbCas12a and FnoCas12a nucleases in combination with these modified crRNAs display high mutagenesis efficiencies and low toxicity when delivered as ribonucleoprotein complexes at high concentration. Together, these results define a set of enhanced Cas12a components with broad utility in vertebrate systems.

A Novel Framework for Anomaly Detection for Satellite Momentum Wheel Based on Optimized SVM and Huffman-Multi-Scale Entropy.

The health status of the momentum wheel is vital for a satellite. Recently, research on anomaly detection for satellites has become more and more extensive. Previous research mostly required simulation models for key components. However, the physical models are difficult to construct, and the simulation data does not match the telemetry data in engineering applications. To overcome the above problem, this paper proposes a new anomaly detection framework based on real telemetry data. First, the time-domain and frequency-domain features of the preprocessed telemetry signal are calculated, and the effective features are selected through evaluation. Second, a new Huffman-multi-scale entropy (HMSE) system is proposed, which can effectively improve the discrimination between different data types. Third, this paper adopts a multi-class SVM model based on the directed acyclic graph (DAG) principle and proposes an improved adaptive particle swarm optimization (APSO) method to train the SVM model. The proposed method is applied to anomaly detection for satellite momentum wheel voltage telemetry data. The recognition accuracy and detection rate of the method proposed in this paper can reach 99.60% and 99.87%. Compared with other methods, the proposed method can effectively improve the recognition accuracy and detection rate, and it can also effectively reduce the false alarm rate and the missed alarm rate.

Exosomal MiR-500a-3p promotes cisplatin resistance and stemness via negatively regulating FBXW7 in gastric cancer.

Chemoresistance has been a major challenge in advanced gastric cancer (GC) therapy. Exosomal transfer of oncogenic miRNAs implicates important effects in mediating recipient cell chemoresistance by transmitting active molecules. In this study, we found that microRNA-500a-3p was highly expressed in cisplatin (DDP) resistant GC cells (MGC803/DDP and MKN45/DDP) and their secreted exosomes than that in the corresponding parental cells. MGC803/DDP-derived exosomes enhance DDP resistance and stemness properties of MGC803 recipient cells via exosomal delivery of miR-500a-3p in vitro and in vivo through targeting FBXW7. However, reintroduction of FBXW7 in MGC803 cells reverses miR-500a-3p-mediated DDP resistance as well as stemness properties. Furthermore, elevated miR-500a-3p in the plasma exosomes of GC patients is correlated with DDP resistance and thereby results in poor progression-free prognosis. Our finding highlights the potential of exosomal miR-500a-3p as an potential modality for the prediction and treatment of GC with chemoresistance.