CRISPR technologies have begun to revolutionize T cell therapies; however, conventional CRISPR-Cas9 genome-editing tools are limited in their safety, efficacy, and scope. To address these challenges, we developed multiplexed effector guide arrays (MEGA), a platform for programmable and scalable regulation of the T cell transcriptome using the RNA-guided, RNA-targeting activity of CRISPR-Cas13d. MEGA enables quantitative, reversible, and massively multiplexed gene knockdown in primary human T cells without targeting or cutting genomic DNA. Applying MEGA to a model of CAR T cell exhaustion, we robustly suppressed inhibitory receptor upregulation and uncovered paired regulators of T cell function through combinatorial CRISPR screening. We additionally implemented druggable regulation of MEGA to control CAR activation in a receptor-independent manner. Lastly, MEGA enabled multiplexed disruption of immunoregulatory metabolic pathways to enhance CAR T cell fitness and anti-tumor activity in vitro and in vivo. MEGA offers a versatile synthetic toolkit for applications in cancer immunotherapy and beyond.

Two reports by Dhuri et al. and Oyaghire et al., respectively, show that, through installing chiral centers at the backbone of the artificial nucleic acid, peptide nucleic acid (PNA), enhanced miRNA targeting and genome modification can be achieved, with important implications in fighting cancers and β-thalassemia.

Messenger RNA (mRNA) has shown tremendous potential in disease prevention and therapy. The clinical application requires mRNA with enhanced stability and high translation efficiency, ensuring it not to be degraded by nucleases and targeting to specific tissues and cells. mRNA immunogenicity can be reduced by nucleotide modification, and translation efficiency can be enhanced by codon optimization. The 5´ capping structure and 3´ poly A increase mRNA stability, and the addition of 5\' and 3\' non-translational regions regulate mRNA translation initiation and protein production. Nanoparticle delivery system protects mRNA from degradation by ubiquitous nucleases, enhances mRNA concentration in circulation and assists it cytoplasmic entrance for the purpose of treatment and prevention. Here, we review the recent advances of mRNA technology, discuss the methods and principles to enhance mRNA stability and translation efficiency; summarize the requirements involved in designing mRNA delivery systems with the potential for industrial translation and biomedical application. Furthermore, we provide insights into future directions of mRNA therapeutics to meet the needs for personalized precision medicine.
信使RNA（mRNA）药物在多种疾病的预防和治疗中展现了巨大的应用价值。最大程度提高mRNA的稳定性和翻译效率，保证mRNA免受核酸酶的降解并靶向特定组织和细胞是临床转化的要求。通过修饰核苷酸降低mRNA免疫原性，密码子优化增加mRNA翻译效率，5´帽结构和3´多聚腺苷酸尾结构增加mRNA稳定性，以及添加5´和3´非翻译区功能调控mRNA稳定性和翻译效率。通过纳米粒递送系统保护mRNA不被核酸酶降解，增加mRNA血液循环，并帮助mRNA进入细胞质发挥治疗和预防作用。本文综述了mRNA药物的制剂工程技术进展，讨论了提高mRNA稳定性和翻译效率的方法及设计原理，总结了具有产业转换潜力的mRNA递送系统的设计要求及其临床应用，并展望了mRNA药物未来可能的研究方向，以满足实现个性化精准医疗的需求。.

Messenger RNA (mRNA) has shown tremendous potential in disease prevention and therapy. The clinical application requires mRNA with enhanced stability and high translation efficiency, ensuring it not to be degraded by nuclease and to target to specific tissues and cells. The mRNA immunogenicity can be reduced by nucleotide modification, and its translation efficiency can be enhanced by codon optimization. The 5´ capping structure and 3´ poly A increase mRNA stability, and the addition of 5\' and 3\' non-translational region regulates mRNA translation initiation and protein production. A nanoparticle delivery system protects mRNA from degradation by ubiquitous nuclease, enhances its circulation concentration and assists it entrancing cytoplasm for the purpose of treatment and prevention. In this article, we review the recent advances of mRNA technology, discuss the methods and principles to enhance mRNA stability and translation efficiency; summarize the requirements involved in designing mRNA delivery systems with the potential of industrial translation and biomedical application. Furthermore, we provide insights into future directions of mRNA therapeutics to meet the need for personalized precision medicine.
信使RNA（mRNA）药物在多种疾病的预防和治疗中展现了巨大的应用价值。最大程度提高mRNA的稳定性和翻译效率，保证mRNA免受核酸酶的降解并靶向特定组织和细胞是临床转化的要求。通过修饰核苷酸降低mRNA免疫原性，密码子优化增加mRNA翻译效率，5´帽结构和3´多聚腺苷酸尾结构增加mRNA稳定性，以及添加5´和3´非翻译区功能调控mRNA稳定性和翻译效率。通过纳米颗粒递送系统保护mRNA不被核酸酶降解，增加mRNA血液循环，并帮助mRNA进入细胞质发挥治疗和预防作用。本文综述了mRNA药物的制剂工程技术进展，讨论了提高mRNA稳定性和翻译效率的方法及设计原理，总结了具有产业转换潜力的mRNA递送系统的设计要求及其临床应用，并展望了mRNA药物未来可能的研究方向，以满足实现个性化精准医疗的需求。.

Prokaryotic clustered regularly interspaced short palindromic repeats and CRISPR associated (CRISPR-Cas) systems provide adaptive immunity by using RNA-guided endonucleases to recognize and eliminate invading foreign nucleic acids. Type II Cas9, type V Cas12, type VI Cas13, and type III Csm/Cmr complexes have been well characterized and developed as programmable platforms for selectively targeting and manipulating RNA molecules of interest in prokaryotic and eukaryotic cells. These Cas effectors exhibit remarkable diversity of ribonucleoprotein (RNP) composition, target recognition and cleavage mechanisms, and self discrimination mechanisms, which are leveraged for various RNA targeting applications. Here, we summarize the current understanding of mechanistic and functional characteristics of these Cas effectors, give an overview on RNA detection and manipulation toolbox established so far including knockdown, editing, imaging, modification, and mapping RNA-protein interactions, and discuss the future directions for CRISPR-based RNA targeting tools. This article is categorized under: RNA Methods > RNA Analyses in Cells RNA Processing > RNA Editing and Modification RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

Neuroblastoma RAS (NRAS) is an oncogene that is deregulated and highly mutated in cancers including melanomas and acute myeloid leukemias. The 5\' untranslated region (UTR) (5\' UTR) of the NRAS mRNA contains a G-quadruplex (G4) that regulates translation. Here we report a novel class of small molecule that binds to the G4 structure located in the 5\' UTR of the NRAS mRNA. We used a small molecule microarray screen to identify molecules that selectively bind to the NRAS-G4 with submicromolar affinity. One compound inhibits the translation of NRAS in vitro but showed only moderate effects on the NRAS levels in cellulo. Rapid Amplification of cDNA Ends and RT-PCR analysis revealed that the predominant NRAS transcript does not possess the G4 structure. Thus, although NRAS transcripts lack a G4 in many cell lines the concept of targeting folded regions within 5\' UTRs to control translation remains a highly attractive strategy.

Cas13 are the only CRISPR/Cas systems found so far, which target RNA strand while preserving chromosomal integrity. Cas13b or Cas13d cleaves RNA by the crRNA guidance. However, the effect of the characteristics of the spacer sequences, such as the length and sequence preference, on the activity of Cas13b and Cas13d remains unclear. Our study shows that neither Cas13b nor Cas13d has a particular preference for the sequence composition of gRNA, including the sequence of crRNA and its flanking sites on target RNA. However, the crRNA, complementary to the middle part of the target RNA, seems to show higher cleavage efficiency for both Cas13b and Cas13d. As for the length of crRNAs, the most appropriate crRNA length for Cas13b is 22-25 nt and crRNA as short as 15 nt is still functional. Whereas, Cas13d requires longer crRNA, and 22-30 nt crRNA can achieve good effect. Both Cas13b and Cas13d show the ability to process precursor crRNAs. Our study suggests that Cas13b may have a stronger precursor processing ability than Cas13d. There are few in vivo studies on the application of Cas13b or Cas13d in mammals. With the methods of transgenic mice and hydrodynamic injection via tail vein, our study showed that both of them had high knock-down efficiency against target RNA in vivo. These results indicate that Cas13b and Cas13d have great potential for in vivo RNA operation and disease treatment without damaging genomic DNA.

Although more than 98% of the human genome is noncoding, nearly all drugs on the market target one of about 700 disease-related proteins. However, an increasing number of diseases are now being attributed to noncoding RNA and the ability to target them would vastly expand the chemical space for drug development. We recently devised a screening strategy based upon affinity-selection mass spectrometry and succeeded in identifying bioactive compounds for the noncoding RNA prototype, Xist. One such compound, termed X1, has drug-like properties and binds specifically to the RepA motif of Xist in vitro and in vivo. Small-angle X-ray scattering analysis reveals that X1 changes the conformation of RepA in solution, thereby explaining the displacement of cognate interacting protein factors (PRC2 and SPEN) and inhibition of X-chromosome inactivation. In this Perspective, we discuss lessons learned from these proof-of-concept experiments and suggest that RNA can be systematically targeted by drug-like compounds to disrupt RNA structure and function.

For more than three decades, RNA has been known to be a relevant and attractive macromolecule to target but figuring out which RNA should be targeted and how remains challenging. Recent years have seen the confluence of approaches for screening, drug optimization, and target validation that have led to the approval of a few RNA-targeting therapeutics for clinical applications. This focused perspective aims to highlight - but not exhaustively review - key factors accounting for these successes while pointing at crucial aspects worth considering for further breakthroughs.

Nonsense mutations, accounting for >20% of disease-associated mutations, lead to premature translation termination. Replacing uridine with pseudouridine in stop codons suppresses translation termination, which could be harnessed to mediate readthrough of premature termination codons (PTCs). Here, we present RESTART, a programmable RNA base editor, to revert PTC-induced translation termination in mammalian cells. RESTART utilizes an engineered guide snoRNA (gsnoRNA) and the endogenous H/ACA box snoRNP machinery to achieve precise pseudouridylation. We also identified and optimized gsnoRNA scaffolds to increase the editing efficiency. Unexpectedly, we found that a minor isoform of pseudouridine synthase DKC1, lacking a C-terminal nuclear localization signal, greatly improved the PTC-readthrough efficiency. Although RESTART induced restricted off-target pseudouridylation, they did not change the coding information nor the expression level of off-targets. Finally, RESTART enables robust pseudouridylation in primary cells and achieves functional PTC readthrough in disease-relevant contexts. Collectively, RESTART is a promising RNA-editing tool for research and therapeutics.