A DddA ortholog-based and transactivator-assisted nuclear and mitochondrial cytosine base editors with expanded target compatibility.

Bacterial double-stranded DNA (dsDNA) cytosine deaminase DddAtox-derived cytosine base editor (DdCBE) and its evolved variant, DddA11, guided by transcription-activator-like effector (TALE) proteins, enable mitochondrial DNA (mtDNA) editing at TC or HC (H = A, C, or T) sequence contexts, while it remains relatively unattainable for GC targets. Here, we identified a dsDNA deaminase originated from a Roseburia intestinalis interbacterial toxin (riDddAtox) and generated CRISPR-mediated nuclear DdCBEs (crDdCBEs) and mitochondrial CBEs (mitoCBEs) using split riDddAtox, which catalyzed C-to-T editing at both HC and GC targets in nuclear and mitochondrial genes. Moreover, transactivator (VP64, P65, or Rta) fusion to the tail of DddAtox- or riDddAtox-mediated crDdCBEs and mitoCBEs substantially improved nuclear and mtDNA editing efficiencies by up to 3.5- and 1.7-fold, respectively. We also used riDddAtox-based and Rta-assisted mitoCBE to efficiently stimulate disease-associated mtDNA mutations in cultured cells and in mouse embryos with conversion frequencies of up to 58% at non-TC targets.

Switch of ELF3 and ATF4 transcriptional axis programs the amino acid insufficiency-linked epithelial-to-mesenchymal transition.

Epithelial-to-mesenchymal transition (EMT) that endows cancer cells with increased invasive and migratory capacity enables cancer dissemination and metastasis. This process is tightly associated with metabolic reprogramming acquired for rewiring cell status and signaling pathways for survival in dietary insufficiency conditions. However, it remains largely unclear how transcription factor (TF)-mediated transcriptional programs are modulated during the EMT process. Here, we reveal that depletion of a key epithelial TF, ELF3 (E74-like factor-3), triggers a transforming growth factor ß (TGF-ß) signaling activation-like mesenchymal transcriptomic profile and metastatic features linked to the aminoacyl-tRNA biogenesis pathway. Moreover, the transcriptome alterations elicited by ELF3 depletion perfectly resemble an ATF4-dependent weak response to amino acid starvation. Intriguingly, we observe an exclusive enrichment of ELF3 and ATF4 in epithelial and TGF-ß-induced or ELF3-depletion-elicited mesenchymal enhancers, respectively, with rare co-binding on altered enhancers. We also find that the upregulation of aminoacyl-tRNA synthetases and some mesenchymal genes upon amino acid deprivation is diminished in ATF4-depleted cells. In sum, the loss of ELF3 binding on epithelial enhancers and the gain of ATF4 binding on the enhancers of mesenchymal factors and amino acid deprivation responsive genes facilitate the loss of epithelial cell features and the gain of TGF-ß-signaling-associated mesenchymal signatures, which further promote lung cancer cell metastasis.

The modification of surface basicity and its role in naphthalene oxidation: The effect of the basic sites introduced by Ce.

A series of V-xCe/Ti catalysts was prepared by a step impregnation method with gradual increased Ce amount. Compared to the commercial V-W/Ti catalysts, the V-xCe/Ti catalysts exhibited considerably higher COx selectivity during the oxidation of naphthalene (Nap), and less intermediates or by-products were detected both in gas phase and on the surface of the catalysts. Through a series of characterizations, it was found that abundance of weak basic sites in the form of OH was introduced by Ce, as well as the oxygen vacancies caused by the redox cycle of V4++Ce4+↔V5++Ce3+. The weak basic sites introduced by Ce could greatly enhance the Nap adsorption, and the Nap adsorbed was quickly converted to naphthol on Ce-OH. Furthermore, V existed at a high valence with the interaction of V and Ce, and the oxygen vacancies also increased the Oads and OOH. It improved the redox ability and the regeneration of Ce-OH on V-xCe/Ti catalysts. The intermediates could be further oxidized, and the Ce-OH consumed in the reaction could recover quickly. Therefore, almost 100% Nap conversion and a high COx selectivity was observed in the V-xCe/Ti catalysts system.

Enhancer Reprogramming within Pre-existing Topologically Associated Domains Promotes TGF-ß-Induced EMT and Cancer Metastasis.

Transcription growth factor ß (TGF-ß) signaling-triggered epithelial-to-mesenchymal transition (EMT) process is associated with tumor stemness, metastasis, and chemotherapy resistance. However, the epigenomic basis for TGF-ß-induced EMT remains largely unknown. Here we reveal that HDAC1-mediated global histone deacetylation and the gain of specific histone H3 lysine 27 acetylation (H3K27ac)-marked enhancers are essential for the TGF-ß-induced EMT process. Enhancers gained upon TGF-ß treatment are linked to gene activation of EMT markers and cancer metastasis. Notably, dynamic enhancer gain or loss mainly occurs within pre-existing topologically associated domains (TADs) in epithelial cells, with minimal three-dimensional (3D) genome architecture reorganization. Through motif enrichment analysis of enhancers that are lost or gained upon TGF-ß stimulation, we identify FOXA2 as a key factor to activate epithelial-specific enhancer activity, and we also find that TEAD4 forms a complex with SMAD2/3 to mediate TGF-ß signaling-triggered mesenchymal enhancer reprogramming. Together, our results implicate that key transcription-factor (TF)-mediated enhancer reprogramming modulates the developmental transition in TGF-ß signaling-associated cancer metastasis.

Optical detection of glucose concentration in samples with scattering particles.

An optical-based method is proposed for measuring the glucose concentration of samples containing scattering particles. In the proposed approach, a Stokes-Mueller reflection-based polarimetry technique is used to solve the Mueller matrices of a turbid glucose sample with circular birefringence and depolarization properties given six incident lights with different polarization states. Using an error function defined as the difference between the simulated output Stokes vectors and the experimental ones, a genetic algorithm is used to inversely derive the optical rotation and depolarization parameters of the experimental sample corresponding to the glucose concentration and scattering depolarization effect, respectively. The validity of the proposed method is demonstrated using glucose samples containing 0.02 ml and 0.04 ml lipofundin, respectively.

[Advances in base editing systems].

Programmable nucleases-based genome editing systems offer several advantages, such as high editing efficiency, high product purity, and fewer editing by-products. They have been widely used in biopharmaceutical research and crop engineering. Given the diverse needs for research and application, developing functional base editors has become a major focus in the field of genome editing. Currently, genome editing systems derived from clustered regularly interspaced short palindromic repeats and CRISPR-associated (CRISPR-Cas) and transcription activator-like effector (TALE) systems include single base editors, dual base editors, mitochondrial base editors, and CRISPR-related transposase systems. This review provides a comprehensive overview of the development of base editing systems, summarizes the characteristics, off-target effects, optimization, and improvement strategies of various base editors, and provides insights for further improvement and application of genome editing systems.

Simultaneous removal of naphthalene and NOx over V-Ce/Ti catalyst: Design of separated active sites for naphthalene degradation and SCR reaction.

V-Ce/Ti catalysts were prepared for the removal of naphthalene and NOx in the flue gas. The adverse effects of NH3 and NO on the naphthalene degradation were weakened on V-Ce/Ti, resulting in a decrease of only 2.5 % in COx selectivity. The formation of high molecular weight byproducts was also reduced. Besides the acid sites on the catalysts, Ce introduced new Brønsted basic sites, which could also adsorb and degrade naphthalene into naphthol effectively. With the separated active sites for naphthalene degradation and NO removal, the reaction between NH3 and the intermediates during the naphthalene degradation was also inhibited, decreasing the formation and accumulation of phthalimide. The oxidation of the intermediates was promoted by active V5+ introduced by Ce, inhibiting the transformation of the intermediates to higher molecular weight byproducts. Nearly 100 % conversion of naphthalene and NO, as well as 40.1 % of the COx selectivity were obtained on V-Ce/Ti.

Cas9-orthologue-mediated cytosine and adenine base editors recognizing NNAAAA PAM sequences.

CRISPR/Cas9 system has been applied as an effective genome-targeting technology. By fusing deaminases with Cas9 nickase (nCas9), various cytosine and adenine base editors (CBEs and ABEs) have been successfully developed that can efficiently induce nucleotide conversions and install pathogenic single nucleotide variants (SNVs) in cultured cells and animal models. However, the applications of BEs are frequently limited by the specific protospacer adjacent motif (PAM) sequences and protein sizes. To expand the toolbox for BEs that can recognize novel PAM sequences, we cloned a Cas9 ortholog from Streptococcus sinensis (named as SsiCas9) with a smaller size and constructed it into APOBEC1- or APOBEC3A-composed CBEs and TadA or TadA*-composed ABEs, which yield high editing efficiencies, low off-targeting activities, and low indel rates in human cells. Compared to PAMless SpRY Cas9-composed BE4max, SsiCas9-mediated BE4max displayed higher editing efficiencies for targets with "NNAAAA" PAM sequences. Moreover, SsiCas9-mediated BE4max induced highly efficient C-to-T conversions in the mouse Ar gene (R841C) to introduce a human androgen resistance syndrome-related mutation (AR R820C) in early mouse embryos. Thus, we developed novel BEs mediated by SsiCas9, expanded the toolbox for base conversions, and broadened the range of editable genomes in vitro and in vivo.

Dual guide RNA-mediated concurrent C&G-to-T&A and A&T-to-G&C conversions using CRISPR base editors.

Base editing tools enable precise genome modifications, disease modeling, and promising gene therapy. However, many human genetic diseases are elicited by multi-nucleotide variants (MNVs) with heterogeneous substitutions at the same genomic locus. Based on the adenine and cytosine base editors, dual base editors that can catalyze concurrent C-to-T and A-to-G editing have been developed, while simultaneous C&G-to-T&A and A&T-to-G&C conversions on the same allele have not been achieved at the desirable site. Here we propose a strategy of combining base editors with dual guide RNAs (gRNAs) that target two overlapped neighboring loci on the opposite strands, which can induce simultaneous C&G-to-T&A and A&T-to-G&C conversions within their overlapping targeting windows. Moreover, one of the paired gRNAs is mutated to perfectly match another gRNA-edited sequence, efficiently facilitating concurrent base conversions on the same allele. To further expand the targeting scopes, PAMless SpRY Cas9-mediated base editors are combined with our optimized dual gRNAs system to induce expected concurrent base editing and to install neighboring pathogenic MNVs in TP53 in cancer cells. In addition, more complex mutation types can be achieved by integrating dual base editors and our dual gRNAs strategy. Thus, we establish a general strategy to efficiently induce MNVs in human genome, helping to dissect the functions of pathogenic MNVs with multifarious types.

Safety and immunogenicity of quadrivalent meningococcal polysaccharide vaccine (MPV ACYW135) compared with quadrivalent meningococcal conjugate vaccine (Menactra®) in Malian children.

Affordable, polyvalent meningococcal vaccines are needed for use in emergency reactive immunization campaigns. A phase IV randomized, observer-blind, controlled study compared the safety and immunogenicity of a quadrivalent meningococcal polysaccharide vaccine (MPV-4, MPV ACYW135) and quadrivalent meningococcal ACWY conjugate vaccine (MCV-4, Menactra®). Healthy, 2- to 10-year-old children in Bamako, Mali, were randomized 1:1 to receive one dose of MPV-4 or MCV-4. Safety outcomes were evaluated for 6 months post-immunization. Immunogenicity for all serogroups was assessed for non-inferiority between MPV-4 and MCV-4 30 days post immunization by serum bactericidal antibody assay using baby rabbit complement (rSBA). From December 2020 to July 2021, 260 healthy subjects were consented and randomized. At Day 30 post-immunization, the proportions of subjects with rSBA titers ≥ 128 for all serogroups in the MPV-4 group were non-inferior to those in MCV-4 group. The proportions of subjects with rSBA ≥ 4-fold increase and rSBA titers ≥ 8 for all serogroups were similar among vaccine groups (P > .05). Geometric Mean Titers and Geometric Mean Fold Increases for all serogroups in both vaccine groups were similar (P > .05). Few local and systemic post-immunization reactions of similar severity and duration were observed within 7 days and were similar in both groups (P > .05). All resolved without sequelae. Unsolicited adverse events were similar in both groups regarding relationship to study vaccine, severity and duration. No serious adverse events were reported during the study period. MPV ACYW135 showed a non-inferior immunogenicity profile and a comparable reactogenicity profile to MCV-4 in Malian children aged 2-10 years.Clinical Trial Registration: NCT04450498.

Functional Phosphoproteomics in Cancer Chemoresistance Using CRISPR-Mediated Base Editors.

Selective inhibition of targeted protein kinases is an effective therapeutic approach for treatment of human malignancies, which interferes phosphorylation of cellular substrates. However, a drug-imposed selection creates pressures for tumor cells to acquire chemoresistance-conferring mutations or activating alternative pathways, which can bypass the inhibitory effects of kinase inhibitors. Thus, identifying downstream phospho-substrates conferring drug resistance is of great importance for developing poly-pharmacological and targeted therapies. To identify functional phosphorylation sites involved in 5-fluorouracil (5-FU) resistance during its treatment of colorectal cancer cells, CRISPR-mediated cytosine base editor (CBE) and adenine base editor (ABE) are utilized for functional screens by mutating phosphorylated amino acids with two libraries specifically targeting 7779 and 10 149 phosphorylation sites. Among the top enriched gRNAs-induced gain-of-function mutants, the target genes are involved in cell cycle and post-translational covalent modifications. Moreover, several substrates of RSK2 and PAK4 kinases are discovered as main effectors in responding to 5-FU chemotherapy, and combinational treatment of colorectal cancer cells with 5-FU and RSK2 inhibitor or PAK4 inhibitor can largely inhibit cell growth and enhance cell apoptosis through a RSK2/TP53BP1/γ-H2AX phosphorylation signaling axis. It is proposed that this screen approach can be used for functional phosphoproteomics in chemotherapy of various human diseases.

Base editing-mediated perturbation of endogenous PKM1/2 splicing facilitates isoform-specific functional analysis in vitro and in vivo.

OBJECTIVES: PKM1 and PKM2, which are generated from the alternative splicing of PKM gene, play important roles in tumourigenesis and embryonic development as rate-limiting enzymes in glycolytic pathway. However, because of the lack of appropriate techniques, the specific functions of the 2 PKM splicing isoforms have not been clarified endogenously yet. MATERIALS AND METHODS: In this study, we used CRISPR-based base editors to perturbate the endogenous alternative splicing of PKM by introducing mutations into the splicing junction sites in HCT116 cells and zebrafish embryos. Sanger sequencing, agarose gel electrophoresis and targeted deep sequencing assays were utilized for identifying mutation efficiencies and detecting PKM1/2 splicing isoforms. Cell proliferation assays and RNA-seq analysis were performed to describe the effects of perturbation of PKM1/2 splicing in tumour cell growth and zebrafish embryo development. RESULTS: The splicing sites of PKM, a 5' donor site of GT and a 3' acceptor site of AG, were efficiently mutated by cytosine base editor (CBE; BE4max) and adenine base editor (ABE; ABEmax-NG) with guide RNAs (gRNAs) targeting the splicing sites flanking exons 9 and 10 in HCT116 cells and/or zebrafish embryos. The mutations of the 5' donor sites of GT flanking exons 9 or 10 into GC resulted in specific loss of PKM1 or PKM2 expression as well as the increase in PKM2 or PKM1 respectively. Specific loss of PKM1 promoted cell proliferation of HCT116 cells and upregulated the expression of cell cycle regulators related to DNA replication and cell cycle phase transition. In contrast, specific loss of PKM2 suppressed cell growth of HCT116 cells and resulted in growth retardation of zebrafish. Meanwhile, we found that mutation of PKM1/2 splicing sites also perturbated the expression of non-canonical PKM isoforms and produced some novel splicing isoforms. CONCLUSIONS: This work proved that CRISPR-based base editing strategy can be used to disrupt the endogenous alternative splicing of genes of interest to study the function of specific splicing isoforms in vitro and in vivo. It also reminded us to notice some novel or undesirable splicing isoforms by targeting the splicing junction sites using base editors. In sum, we establish a platform to perturbate endogenous RNA splicing for functional investigation or genetic correction of abnormal splicing events in human diseases.

Modeling a cataract disorder in mice with prime editing.

Prime editing enables efficient introduction of targeted transversions, insertions, and deletions in mammalian cells and several organisms. However, genetic disease models with base deletions by prime editing have not yet been reported in mice. Here, we successfully generate a mouse model with a cataract disorder through microinjection of prime editor 3 (PE3) plasmids to efficiently induce targeted single-base deletion. Notably, a generated mouse with a high G-deletion rate (38.2%) displays a nuclear cataract phenotype; the PE3-induced deletions in mutant mice achieve high rates of germline transmission to their progenies, with phenotypic inheritance of cataract. Our data propose that modeling a genetic disease with a single nucleotide deletion in mice can be achieved with prime genome editing in vivo.

Oncogenic enhancers drive esophageal squamous cell carcinogenesis and metastasis.

The role of cis-elements and their aberrations remains unclear in esophageal squamous cell carcinoma (ESCC, further abbreviated EC). Here we survey 28 H3K27ac-marked active enhancer profiles and 50 transcriptomes in primary EC, metastatic lymph node cancer (LNC), and adjacent normal (Nor) esophageal tissues. Thousands of gained or lost enhancers and hundreds of altered putative super-enhancers are identified in EC and LNC samples respectively relative to Nor, with a large number of common gained or lost enhancers. Moreover, these differential enhancers contribute to the transcriptomic aberrations in ECs and LNCs. We also reveal putative driver onco-transcription factors, depletion of which diminishes cell proliferation and migration. The administration of chemical inhibitors to suppress the predicted targets of gained super-enhances reveals HSP90AA1 and PDE4B as potential therapeutic targets for ESCC. Thus, our epigenomic profiling reveals a compendium of reprogrammed cis-regulatory elements during ESCC carcinogenesis and metastasis for uncovering promising targets for cancer treatment.

High-resolution annotation of the mouse preimplantation embryo transcriptome using long-read sequencing.

The transcriptome of the preimplantation mouse embryo has been previously annotated by short-read sequencing, with limited coverage and accuracy. Here we utilize a low-cell number transcriptome based on the Smart-seq2 method to perform long-read sequencing. Our analysis describes additional novel transcripts and complexity of the preimplantation transcriptome, identifying 2280 potential novel transcripts from previously unannotated loci and 6289 novel splicing isoforms from previously annotated genes. Notably, these novel transcripts and isoforms with transcription start sites are enriched for an active promoter modification, H3K4me3. Moreover, we generate a more complete and precise transcriptome by combining long-read and short-read data during early embryogenesis. Based on this approach, we identify a previously undescribed isoform of Kdm4dl with a modified mRNA reading frame and a novel noncoding gene designated XLOC_004958. Depletion of Kdm4dl or XLOC_004958 led to abnormal blastocyst development. Thus, our data provide a high-resolution and more precise transcriptome during preimplantation mouse embryogenesis.