RNA Constructs Research Articles

Genome-Wide CRISPR Screen Identifies Genes Involved in Metastasis of Pancreatic Ductal Adenocarcinoma

Background/Objectives: Early and aggressive metastasis is a major feature of pancreatic ductal adenocarcinoma. Understanding the processes underlying metastasis is crucial for making a difference to disease outcome. Towards these ends, we looked in a comprehensive manner for genes that are metastasis-specific. Methods: A genome-wide CRISPR-Cas9 gene knockout screen with 259,900 single guide RNA constructs was performed on pancreatic cancer cell lines with very high or very low metastatic capacity, respectively. Functional aspects of some of the identified genes were analysed in vitro. The injection of tumour cells with or without a gene knockout into mice was used to confirm the effect on metastasis. Results: The knockout of 590 genes—and, with higher analysis stringency, 67 genes—affected the viability of metastatic cells substantially, while these genes were not vital to non-metastasizing cells. Further evaluations identified different molecular processes related to this observation. One of the genes was MYBL2, encoding for a well-known transcription factor involved in the regulation of cell survival, proliferation, and differentiation in cancer tissues. In our metastasis-focussed study, no novel functional activity was detected for MYBL2, however. Instead, a metastasis-specific transformation of its genetic interaction with FOXM1 was observed. The interaction was synergistic in cells of low metastatic capacity, while there was a strong switch to a buffering mode in metastatic cells. In vivo analyses confirmed the strong effect of MYBL2 on metastasis. Conclusions: The genes found to be critical for the viability of metastatic cells form a basis for further investigations of the processes responsible for triggering and driving metastasis. As shown for MYBL2, unexpected processes of regulating metastasis might also be involved.

Enhancing RNA-seq bias mitigation with the Gaussian self-benchmarking framework: towards unbiased sequencing data

BackgroundRNA sequencing is a vital technique for analyzing RNA behavior in cells, but it often suffers from various biases that distort the data. Traditional methods to address these biases are typically empirical and handle them individually, limiting their effectiveness. Our study introduces the Gaussian Self-Benchmarking (GSB) framework, a novel approach that leverages the natural distribution patterns of guanine (G) and cytosine (C) content in RNA to mitigate multiple biases simultaneously. This method is grounded in a theoretical model, organizing k-mers based on their GC content and applying a Gaussian model for alignment to ensure empirical sequencing data closely match their theoretical distribution.ResultsThe GSB framework demonstrated superior performance in mitigating sequencing biases compared to existing methods. Testing with synthetic RNA constructs and real human samples showed that the GSB approach not only addresses individual biases more effectively but also manages co-existing biases jointly. The framework’s reliance on accurately pre-determined parameters like mean and standard deviation of GC content distribution allows for a more precise representation of RNA samples. This results in improved accuracy and reliability of RNA sequencing data, enhancing our understanding of RNA behavior in health and disease.ConclusionsThe GSB framework presents a significant advancement in RNA sequencing analysis by providing a well-validated, multi-bias mitigation strategy. It functions independently from previously identified dataset flaws and sets a new standard for unbiased RNA sequencing results. This development enhances the reliability of RNA studies, broadening the potential for scientific breakthroughs in medicine and biology, particularly in genetic disease research and the development of targeted treatments.

Enhancing RNA-seq analysis by addressing all co-existing biases using a self-benchmarking approach with 2D structural insights.

We introduce a groundbreaking approach: the minimum free energy-based Gaussian Self-Benchmarking (MFE-GSB) framework, designed to combat the myriad of biases inherent in RNA-seq data. Central to our methodology is the MFE concept, facilitating the adoption of a Gaussian distribution model tailored to effectively mitigate all co-existing biases within a k-mer counting scheme. The MFE-GSB framework operates on a sophisticated dual-model system, juxtaposing modeling data of uniform k-mer distribution against the real, observed sequencing data characterized by nonuniform k-mer distributions. The framework applies a Gaussian function, guided by the predetermined parameters-mean and SD-derived from modeling data, to fit unknown sequencing data. This dual comparison allows for the accurate prediction of k-mer abundances across MFE categories, enabling simultaneous correction of biases at the single k-mer level. Through validation with both engineered RNA constructs and human tissue RNA samples, its wide-ranging efficacy and applicability are demonstrated.

Investigation of cryptic JAG1 splice variants as a cause of Alagille syndrome and performance evaluation of splice predictor tools

Haploinsufficiency of JAG1 is the primary cause of Alagille syndrome (ALGS), a rare, multisystem disorder. The identification of JAG1 intronic variants outside of the canonical splice region as well as missense variants, both of which lead to uncertain associations with disease, confuses diagnostics. Strategies to determine whether these variants affect splicing include the study of patient RNA or minigene constructs, which are not always available or can be laborious to design, as well as the utilization of computational splice prediction tools. These tools, including SpliceAI and Pangolin, use algorithms to calculate the probability that a variant results in a splice alteration, expressed as a Δ score, with higher Δ scores (>0.2 on a 0-1 scale) positively correlated with aberrant splicing. We studied the consequence of 10 putative splice variants in ALGS patient samples through RNA analysis and compared this to SpliceAI and Pangolin predictions. We identified eight variants with aberrant splicing, seven of which had not been previously validated. Combining these data with non-canonical and missense splice variants reported in the literature, we identified a predictive threshold for SpliceAI and Pangolin with high sensitivity (Δ score >0.6). Moreover, we showed reduced specificity for variants with low Δ scores (<0.2), highlighting a limitation of these tools that results in the misidentification of true splice variants. These results improve genomic diagnostics for ALGS by confirming splice effects for seven variants and suggest that the integration of splice prediction tools with RNA analysis is important to ensure accurate clinical variant classifications.

Improved constructs for bait RNA display in a bacterial three-hybrid assay.

We have previously developed a transcription-based bacterial three-hybrid (B3H) assay as a genetic approach to probe RNA-protein interactions inside of E. coli cells. This system offers a straightforward path to identify and assess the consequences of mutations in RBPs with molecular phenotypes of interest. One limiting factor in detecting RNA-protein interactions in the B3H assay is RNA misfolding arising from incorrect base-pair interactions with neighboring RNA sequences in a hybrid RNA. To support correct folding of hybrid bait RNAs, we have explored the use of a highly stable stem ("GC clamp") to isolate regions of a hybrid RNA as discrete folding units. In this work, we introduce new bait RNA constructs to 1) insulate the folding of individual components of the hybrid RNA with GC clamps and 2) express bait RNAs that do not encode their own intrinsic terminator. We find that short GC clamps (5 or 7 bp long) are more effective than a longer 13bp GC clamp in the B3H assay. These new constructs increase the number of Hfq-sRNA and -5'UTR interactions that are detectable in the B3H system and improve the signal-to-noise ratio of many of these interactions. We therefore recommend the use of constructs containing short GC clamps for the expression of future B3H bait RNAs. With these new constructs, a broader range of RNA-protein interactions are detectable in the B3H assay, expanding the utility and impact of this genetic tool as a platform to search for and interrogate mechanisms of additional RNA-protein interactions.

High-fidelity CRISPR/Cas12a dual-crRNA screening reveals novel synergistic interactions in hepatocellular carcinoma.

: CRISPR/Cas12a-based combinational screening has shown remarkable potential for identifying genetic interactions. Here, we describe an innovative method for combinational genetic screening with rapid construction of a dual-CRISPR RNA (crRNA) library using gene splicing through overlap extension PCR (SOE PCR) and the adoption of CeCas12a, which we previously identified with strict PAM recognition and low off-targeting to guarantee fidelity and efficiency. The custom-pooled SOE crRNA array (SOCA) library for double-knockout screening could be conveniently constructed in the laboratory for widespread use, and the CeCas12a-mediated high-fidelity screen displayed good performance even under a negative selection screen. By designing a SOCA dual-crRNA library that covered most of the kinase and metabolism-associated gene targets of FDA-approved drugs implicated in hepatocellular carcinoma (HCC) tumourigenesis, novel cross-talk between the two gene sets was negatively selected to inhibit HCC cell growth in vitro and in vivo and was validated using virtual double-knockdown screening based on TCGA databases. Thus, this rapid, efficient and high-fidelity double-knockout screening system is promising for systemically identifying potential genetic interactions between multiple gene sets or combinations of FDA- approved drugs for clinical translational medicine in the future.

Host-induced RNA interference targeting the neuromotor gene FMRFamide-like peptide-14 (Mi-flp14) perturbs Meloidogyne incognita parasitic success in eggplant.

The study demonstrates the successful management of Meloidogyne incognita in eggplant using Mi-flp14 RNA interference, showing reduced nematode penetration and reproduction without off-target effects across multiple generations. Root-knot nematode, Meloidogyne incognita, causes huge yield losses worldwide. Neuromotor function in M. incognita governed by 19 neuropeptides is vital for parasitism and parasite biology. The present study establishes the utility of Mi-flp14 for managing M. incognita in eggplant in continuation of our earlier proof of concept in tobacco (US patent US2015/0361445A1). Mi-flp14 hairpin RNA construct was used for generating 19 independent transgenic eggplant events. PCR and Southern hybridization analysis confirmed transgene integration and its orientation, while RT-qPCR and Northern hybridization established the generation of dsRNA and siRNA of Mi-flp14. In vitro and in vivo bio-efficacy analysis of single-copy events against M. incognita showed reduced nematode penetration and development at various intervals that negatively impacted reproduction. Interestingly, M. incognita preferred wild-type plants over the transgenics even when unbiased equal opportunity was provided for the infection. A significant reduction in disease parameters was observed in transgenic plants viz., galls (40-48%), females (40-50%), egg masses (35-40%), eggs/egg mass (50-55%), and derived multiplication factor (60-65%) compared to wild type. A unique demonstration of perturbed expression of Mi-flp14 in partially penetrated juveniles and female nematodes established successful host-mediated RNAi both at the time of penetration even before the nematodes started withdrawing plant nutrients and later stage, respectively. The absence of off-target effects in transgenic plants was supported by the normal growth phenotype of the plants and T-DNA integration loci. Stability in the bio-efficacy against M. incognita across T1- to T4-generation transgenic plants established the utility of silencing Mi-flp14 for nematode management. This study demonstrates the significance of targeting Mi-flp14 in eggplant for nematode management, particularly to address global agricultural challenges posed by M. incognita.

Streamlined Full-Length Total RNA Sequencing of Paraformaldehyde-Fixed Brain Tissues.

Paraformaldehyde (PFA) fixation is the preferred method for preserving tissue architecture for anatomical and pathological observations. Meanwhile, PFA reacts with the amine groups of biomolecules to form chemical cross-linking, which preserves RNA within the tissue. This has great prospects for RNA sequencing to characterize the molecular underpinnings after anatomical and pathological observations. However, RNA is inaccessible due to cross-linked adducts forming between RNA and other biomolecules in prolonged PFA-fixed tissue. It is also difficult to perform reverse transcription and PCR, resulting in low sequencing sensitivity and reduced reproducibility. Here, we developed a method to perform RNA sequencing in PFA-fixed tissue, which is easy to use, cost-effective, and allows efficient sample multiplexing. We employ cross-link reversal to recover RNA and library construction using random primers without artificial fragmentation. The yield and quality of recovered RNA significantly increased through our method, and sequencing quality metrics and detected genes did not show any major differences compared with matched fresh samples. Moreover, we applied our method for gene expression analysis in different regions of the mouse brain and identified unique gene expression profiles with varied functional implications. We also find significant dysregulation of genes involved in Alzheimer's disease (AD) pathogenesis within the medial septum (MS)/vertical diagonal band of Broca (VDB) of the 5×FAD mouse brain. Our method can thus increase the performance of high-throughput RNA sequencing with PFA-fixed samples and allows longitudinal studies of small tissue regions isolated by their in situ context.

Host-Induced Gene Silencing of Effector AGLIP1 Enhanced Resistance of Rice to Rhizoctonia solani AG1-IA

Rice sheath blight, caused by Rhizoctonia solani AG1-IA, is a major disease in rice-growing areas worldwide. Effectors of phytopathogenic fungi play important roles during the infection process of fungal pathogens onto their host plants. However, the molecular mechanisms by which R. solani effectors regulate rice immunity are not well understood. Through prediction, 78 candidate effector molecules were identified. Using the tobacco rattle virus-host induced gene silencing (TRV-HIGS) system, 45 RNAi constructs of effector genes were infiltrated into Nicotiana benthamiana leaves. The results revealed that eight of these constructs resulted in a significant reduction in necrosis caused by infection with the AG1-IA strain GD-118. Additionally, stable rice transformants carrying the double-stranded RNA construct for one of the effector genes, AGLIP1, were generated to further verify the function of this gene. The suppression of the AGLIP1 gene increased the resistance of both N. benthamiana and rice against GD-118, and also affected the growth rate of GD-118, indicating that AGLIP1 is a key pathogenic factor. Small RNA sequencing showed that the HIGS vectors were processed into siRNAs within the plants and then translocated to the fungi, leading to the silencing of the target genes. As a result, AGLIP1 might be an excellent candidate for HIGS, thereby enhancing crop resistance against the pathogen and contributing to the control of R. solani infection.

Expedient production of site specifically nucleobase-labelled or hypermodified RNA with engineered thermophilic DNA polymerases

Innovative approaches to controlled nucleobase-modified RNA synthesis are urgently needed to support RNA biology exploration and to synthesize potential RNA therapeutics. Here we present a strategy for enzymatic construction of nucleobase-modified RNA based on primer-dependent engineered thermophilic DNA polymerases – SFM4-3 and TGK. We demonstrate introduction of one or several different base-modified nucleotides in one strand including hypermodified RNA containing all four modified nucleotides bearing four different substituents, as well as strategy for primer segment removal. We also show facile site-specific or segmented introduction of fluorophores or other functional groups at defined positions in variety of RNA molecules, including structured or long mRNA. Intriguing translation efficacy of single-site modified mRNAs underscores the necessity to study isolated modifications placed at designer positions to disentangle their biological effects and enable development of improved mRNA therapeutics. Our toolbox paves the way for more precise dissecting RNA structures and functions, as well as for construction of diverse types of base-functionalized RNA for therapeutic applications and diagnostics.

RNA Control via Redox‐Responsive Acylation

AbstractIncorporating stimuli‐responsive components into RNA constructs provides precise spatiotemporal control over RNA structures and functions. Despite considerable advancements, the utilization of redox‐responsive stimuli for the activation of caged RNAs remains scarce. In this context, we present a novel strategy that leverages post‐synthetic acylation coupled with redox‐responsive chemistry to exert control over RNA. To achieve this, we design and synthesize a series of acylating reagents specifically tailored for introducing disulfide‐containing acyl adducts into the 2′‐OH groups of RNA (“cloaking”). Our data reveal that these acyl moieties can be readily appended, effectively blocking RNA catalytic activity and folding. We also demonstrate the traceless release and reactivation of caged RNAs (“uncloaking”) through reducing stimuli. By employing this strategy, RNA exhibits rapid cellular uptake, effective distribution and activation in the cytosol without lysosomal entrapment. We anticipate that our methodology will be accessible to laboratories engaged in RNA biology and holds promise as a versatile platform for RNA‐based applications.

RNA Control via Redox-Responsive Acylation.

Incorporating stimuli-responsive components into RNA constructs provides precise spatiotemporal control over RNA structures and functions. Despite considerable advancements, the utilization of redox-responsive stimuli for the activation of caged RNAs remains scarce. In this context, we present a novel strategy that leverages post-synthetic acylation coupled with redox-responsive chemistry to exert control over RNA. To achieve this, we design and synthesize a series of acylating reagents specifically tailored for introducing disulfide-containing acyl adducts into the 2'-OH groups of RNA ("cloaking"). Our data reveal that these acyl moieties can be readily appended, effectively blocking RNA catalytic activity and folding. We also demonstrate the traceless release and reactivation of caged RNAs ("uncloaking") through reducing stimuli. By employing this strategy, RNA exhibits rapid cellular uptake, effective distribution and activation in the cytosol without lysosomal entrapment. We anticipate that our methodology will be accessible to laboratories engaged in RNA biology and holds promise as a versatile platform for RNA-based applications.

A shorter inverted repeat length in a hairpin RNA results in a stronger silencing efficacy

RNA interference (RNAi), particularly hairpin RNA (hpRNA) constructs, is a potent genetic manipulation tool, influencing traits that are crucial for crop improvement. Typical hpRNA constructs consist of inverted repeat sequences derived from the mRNA of the target gene, separated by a non-complementary spacer. This configuration initiates the formation of a double-stranded RNA structure due to the complementary nature of sense and antisense sequences in the transcribed RNA. In this research, two hpRNA constructs, namely hp-TFL1-S and hp-TFL1-L, with distinct lengths of inverted repeats, were designed to target TFL1, a pivotal regulator of both flowering timing and inflorescence structure. hp-TFL1-L construct encompasses all the 150 nucleotide sequences of the hp-TFL1-S construct and an extra 135 nucleotides. These constructs included a chalcone synthase intron as a spacer, resulting in hairpin double-stranded RNA molecules of 150 and 285 base pair after transcription. The PCR and qRT-PCR analysis results confirmed the accurate design of both constructs and their successful suppression of TFL1 mRNA expression in transgenic Arabidopsis. Interestingly, Arabidopsis lines carrying hp-TFL1-S and hp-TFL1-L exhibited distinct phenotypic features. hp-TFL1-S induced more pronounced phenotypic changes, resulting in earlier flowering compared to the hp-TFL1-L and control group. Moreover, hp-TFL1-S had a significant impact on inflorescence architecture, distinguishing it from both hp-TFL1-L and control plants. This study provides an example where inverted repeat length alters the efficacy of silencing, and in this case, surprisingly the shorter construct appears to have a stronger silencing efficacy. This argues multiple sized hpRNAs should be tested in RNAi-based gene silencing experiments.

Abstract 2112: Identification of biomarkers associated with sensitivity to a novel PCNA inhibitor (AOH1996) by CRISPRi screening

Abstract Proliferating cell nuclear antigen (PCNA) plays an essential role in regulating DNA synthesis and repair and is essential for cancer cell growth and survival. We discovered a cancer-associated isoform of PCNA (caPCNA), which is ubiquitously and highly expressed in a broad range of cancer cells and tumor tissues but is not significantly expressed in non-malignant cells. Further studies of this novel caPCNA isoform as an anti-cancer drug target led to the identification of a cancer distinct region of PCNA which is partly delineated by the L126-Y133 peptide sequence and the discovery of a small molecule (AOH1996), which binds to this cancer distinct region as shown by crystallization studies. By targeting caPCNA, AOH1996 selectively kills cancer cells by interfering with the resolution of transcription-replication conflicts (TRC). Importantly, it causes no discernable toxicity at 6 times of its effective dose in mice. AOH1996 is currently in a phase 1 clinical trial for adult solid tumors at City of Hope (IND 138273). To identify genes that may be used as biomarkers for patient selection or potential targets for combination therapies, we screened a CRISPR interference (CRISPRi) library, which targets genes that are involved in cell signaling and cell cycle regulation. After culturing transduced cells in the presence of DMSO or 250 nM AOH1996 (corresponding to IC20) in triplicates for 14 generations, we measured the relative abundance of each guide RNA (gRNA) construct. Significant changes in the abundance of the gRNA constructs in AOH1996-treated cells relative to that in DMSO-treated cells were determined by the MAGeCK method. The target genes of the depleted or enriched gRNAs are predominantly involved in DNA repair, cell cycle regulation, and transcription regulation, which is consistent with the action mechanism of AOH1996. We validated the effect of these genes on sensitivity to AOH1996 and identified a panel of target proteins whose up or down-regulation is associated with sensitivity to AOH1996. Some of these proteins are targets of known chemotherapeutic drugs, which may be used in combination with AOH1996 in the clinic. Citation Format: Long Gu, Ming li, Chun-Wei Chen, Robert J. Hickey, Linda H. Malkas. Identification of biomarkers associated with sensitivity to a novel PCNA inhibitor (AOH1996) by CRISPRi screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2112.

Development of Cell Technologies Based on Dendritic Cells for Immunotherapy of Oncological Diseases.

Immunotherapy using dendritic cell-based vaccination is a natural approach using the capabilities and functions inherent in the patient's immune system to eliminate tumor cells. The development of dendritic cell-based cell technologies evolved as the disorders of dendritic cell differentiation and function in cancer were studied; some of these functions are antigen presentation, priming of cytotoxic T-lymphocytes and induction of antigen-specific immune responses. At the initial stage of technology development, it was necessary to develop protocols for the in vitro generation of functionally mature dendritic cells that were capable of capturing tumor antigens and processing and presenting them in complex with MHC to T-lymphocytes. To achieve this, various forms of tumor-associated antigen delivery systems were tested, including lysates, tumor cell proteins (peptides), and DNA and RNA constructs, and it was shown that the use of DNA and RNA constructs was the most effective method, as it made it possible not only to deliver the most immunogenic epitopes of tumor-associated antigens to dendritic cells, but also to enhance their ability to induce antigen-specific cytotoxic T-lymphocytes. Currently, cell therapy based on dendritic cells is a modern basis for antigen-specific immunotherapy of cancer due to the simplicity of creating DNA and RNA constructs encoding information about both target tumor antigens and regulatory molecules. The potential development of cell technologies based on dendritic cells aims to obtain antigen-specific cytotoxic T-lymphocytes induced by dendritic cells, study their functional activity and develop cell-based therapy.

Development of a transgenic rice line with strong and broad resistance against four devastating rice viruses through expressing a single hairpin RNA construct.

Development of a transgenic rice line with strong and broad resistance against four devastating rice viruses through expressing a single hairpin RNA construct.

(275) IGFBP5 Short Hairpin RNA (shRNA) Constructs Improve Erectile Function in a Mouse Model of Cavernous Nerve Injury

Abstract Introduction Radical prostatectomy for prostate cancer not only induces cavernous nerve injury but also causes cavernous angiopathy, which is responsible for poor responsiveness to phosphodiesterase-5 inhibitors. Insulin-like growth factor-binding protein 5 (IGFBP5) promotes cell death and induces apoptosis in various cell types. Objective To investigate the effectiveness of IGFBP5 knockdown at improving erectile function in a mouse model of cavernous nerve injury. Methods Eight-week-old C57BL/6 mice were used to prepare cavernous nerve injury model. Mice were divided into 4 groups: a sham operation group and three cavernous nerve injury (CNI) groups, which were administered intracavernous injections of phosphate buffered saline, scrambled control shRNA, or shRNA targeting mouse IGFBP5 (shIGFBP5) lentivirus particles. One week later, we measured erectile function by electrically stimulating the bilateral cavernous nerve. Results IGFBP5 expression in cavernous tissues were significantly increased in CNI mice compare to sham mice. CNI mice had reduced erectile function, but shIGFBP5 treatment resulted in significant improvements. Furthermore, in CNI mice, numbers of cavernous endothelial cells, pericytes, and neuronal cells were increased by shIGFBP5 treatment. Conclusions Knockdown of IGFBP5 improved erectile function in CNI mice by enhancing neurovascular regeneration. Local inhibition of IGFBP5 expression may provide a new treatment strategy for the treatment of neurovascular diseases. Disclosure No.

Integrated analysis and validation of ferroptosis-related genes and immune infiltration in acute myocardial infarction

BackgroundAcute myocardial infarction (AMI) is indeed a significant cause of mortality and morbidity in individuals with coronary heart disease. Ferroptosis, an iron-dependent cell death, is characterized by the accumulation of intracellular lipid peroxides, which is implicated in cardiomyocyte injury. This study aims to identify biomarkers that are indicative of ferroptosis in the context of AMI, and to examine their potential roles in immune infiltration.MethodsFirstly, the GSE59867 dataset was used to identify differentially expressed ferroptosis-related genes (DE-FRGs) in AMI. We then performed gene ontology (GO) and functional enrichment analysis on these DE-FRGs. Secondly, we analyzed the GSE76591 dataset and used bioinformatic methods to build ceRNA networks. Thirdly, we identified hub genes in protein–protein interaction (PPI) network. After obtaining the key DE-FRGs through the junction of hub genes with ceRNA and least absolute shrinkage and selection operator (LASSO). ImmucellAI was applied to estimate the immune cell infiltration in each sample and examine the relationship between key DE-FRGs and 24 immunocyte subsets. The diagnostic performance of these genes was further evaluated using the receiver operating characteristic (ROC) curve analysis. Ultimately, we identified an immune-related ceRNA regulatory axis linked to ferroptosis in AMI.ResultsAmong 56 DE-FRGs identified in AMI, 41 of them were integrated into the construction of competitive endogenous RNA (ceRNA) networks. TLR4 and PIK3CA were identified as key DE-FRGs and PIK3CA was confirmed as a diagnostic biomarker for AMI. Moreover, CD4_native cells, nTreg cells, Th2 cells, Th17 cells, central-memory cells, effector-memory cells, and CD8_T cells had higher infiltrates in AMI samples compared to control samples. In contrast, exhausted cells, iTreg cells, and Tfh cells had lower infiltrates in AMI samples. Spearman analysis confirmed the correlation between 24 immune cells and PIK3CA/TLR4. Ultimately, we constructed an immune-related regulatory axis involving XIST and OIP5-AS1/miR-216a/PIK3CA.ConclusionOur comprehensive analysis has identified PIK3CA as a robust and promising biomarker for this condition. Moreover, we have also identified an immune-related regulatory axis involving XIST and OIP5-AS1/miR-216a/PIK3CA, which may play a key role in regulating ferroptosis during AMI progression.

Identification of glycosylated nucleosides in small synthetic glyco-RNAs.

Recently, the post-transcriptional modification of RNA with N-glycans was reported, changing the paradigm that RNAs are not commonly N-glycosylated. Moreover, glycan modifications of RNA are investigated for therapeutic targeting purposes. But the glyco-RNA field is in its infancy with many challenges to overcome. One question is how to accurately characterize glycosylated RNA constructs. Thus, we generated glycosylated forms of Y5 RNA mimics, a short non-coding RNA. The simple glycans lactose and sialyllactose were attached to the RNA backbone using azide-alkyne cycloadditions. Using nuclease digestion followed by LC-MS, we confirmed the presence of the glycosylated nucleosides, and characterized the chemical linkage. Next, we probed if glycosylation would affect the cellular response to Y5 RNA. We treated human foreskin fibroblasts in culture with the generated compounds. Key transcripts in the innate immune response were quantified by RT-qPCR. We found that under our experimental conditions, exposure of cells to the Y5 RNA did not trigger an interferon response, and glycosylation of this RNA did not have an impact. Thus, we have identified a successful approach to chemically characterize synthetic glyco-RNAs, which will be critical for further studies to elucidate how the presence of complex glycans on RNA affects the cellular response.

Construction of a transcription-driven CRISPR RNA auto-generation-mediated CRISPR-Cas12a system for sensitive detection of endogenous repair glycosylase

Base excision repair (BER) plays an essential role in the repair of DNA damage and maintenance of genomic integrity. As a major BER enzyme, human alkyladenine DNA glycosylase (hAAG) acts on various alkylated bases, and its abnormal activity may lead to elevated risks of different cancers. Herein, we develop a transcription-driven CRISPR RNA (crRNAs) auto-generation-mediated CRISPR-Cas12a system for sensitive and simple detection of hAAG. In this strategy, a hairpin probe containing a deoxyinosine base/T (I/T) pairs and a destroyed T7 promoter sequence serves not only as a probe for hAAG recognition but also as a template for transcription, efficiently avoiding nonspecific transcription. Target hAAG induces the hairpin probe cleavage and subsequent unfolding. The unfolded hairpin probe can initiate the KF polymerase-mediated polymerization reaction and subsequent T7 polymerase-mediated transcription reaction for the production of substantial crRNAs. The resultant crRNAs activate the trans-cleavage activity of CRISPR-Cas12a to cleave signal probes, generating an enhanced fluorescence signal. This strategy can measure hAAG with a limit of detection of 9.25 × 10−11 U/μL and a broad linear range of 1 × 10−10–1 × 10-2 U/μL, and it may accurately measure endogenous hAAG at the single-cell level. Furthermore, the assay can be applied for inhibitor screening, kinetic analysis, and the differentiation of tumor cells from healthy cells, with great potential in disease diagnosis.