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A CRISPR/Cas9 mutant resource for OsSm RNA-binding genes in rice.

Pre-mRNA, produced by eukaryotic DNA transcription, undergoes splicing by the spliceosome, which removes introns and joins exons to form mRNA. The spliceosome is a large and highly dynamic molecular machine. Its core components include five small nuclear ribonucleoproteins (snRNPs) and the various spliceosome-related proteins. The conserved Smith (Sm) complex and the Sm-like proteins (LSm) serve as primary components of the snRNPs. Sm proteins are involved in processes such as pre-mRNA splicing and mRNA degradation, which can regulate gene expression, thereby influencing plant growth, development, and stress responses. While 25 Sm proteins have been identified in rice, their specific roles in regulating rice growth and development remain unclear. In this study, we employed the CRISPR/Cas9 system to edit 15 OsSm genes, and 13 mutants were obtained, with mutation rates ranging from 20.83 to 83.87%. In comparison to the wild type (WT), the mutants exhibited dwarfism, reduced tiller numbers, lower seed-setting rates or sterility, and increased susceptibility to diseases. One Sm mutant, ossmf-2, exhibited dwarfism, delayed flowering, and small grains. Through transcriptome analysis, three target genes, OsMRG702, OsRGG2, and OsLA1, were identified. Mutations of the OsSmF protein may lead to the abnormal splicing of these genes and finally lead to the inhibition of growth and development. Our study first edited the OsSm genes and generated a mutant library in rice. Most of the mutants exhibited abnormal growth and development, underscoring the essential roles of OsSm proteins in rice physiology. Furthermore, this work addresses a critical gap in the functional characterization of Sm proteins in rice. The resulting mutant collection offers valuable germplasm resources and lays a theoretical foundation for elucidating the molecular regulatory networks involving spliceosomal components and their target genes in the control of crop growth, development, and reproduction.

Oryza

Genome-wide CRISPRi screen in human iNeurons identifies novel negative mTOR regulator genes associated with focal cortical dysplasia.

Focal cortical dysplasia (FCD) is a common cause of focal epilepsy that typically results from brain mosaic mutations in the mTOR cell signaling pathway. To identify new potential FCD genes, we developed an in vitro CRISPRi screen in human neurons and used FACS enrichment based on the FCD biomarker, phosphorylated S6 ribosomal protein (pS6). Using whole-genome (110,000 gRNAs) and candidate (129 gRNAs) libraries, we discovered 6 new genes in which loss of function significantly increases pS6 levels: LRRC4, EIF3A, TSN, HIP1, PIK3R3, and URI1. Further analysis of the mTOR pathway showed that only two of the genes, PIK3R3 and HIP1, caused hyperphosphorylation throughout the AKT/mTOR/S6 signaling pathway. Importantly, potential pathogenic variants in these two genes have been reported in resected brain tissue from a single FCD patient each, supporting the predictive validity of our screen. Knocking down each of the 6 genes in iNeurons made mTOR signaling resistant to the loss of neurotrophic factor signaling, specifically GDNF; even without GDNF, pS6 levels remained comparable to GDNF-stimulated controls. Thus, we have identified negative regulators of neuronal mTOR signaling in the context of lost neurotrophic factor support. Our data expand the set of genes that are likely to regulate mTOR pathway signaling in neurons, provide biological confirmation for candidate genes identified in human tissue, and suggest additional targets for investigating somatic gene variants in resected FCD tissues. The identification of novel mTOR regulators using iNeurons also highlights the importance of genetic screening in disease-related cell types.

Brain mosaicism

eVOC: a controlled vocabulary for unifying gene expression data.

Expression data contribute significantly to the biological value of the sequenced human genome, providing extensive information about gene structure and the pattern of gene expression. ESTs, together with SAGE libraries and microarray experiment information, provide a broad and rich view of the transcriptome. However, it is difficult to perform large-scale expression mining of the data generated by these diverse experimental approaches. Not only is the data stored in disparate locations, but there is frequent ambiguity in the meaning of terms used to describe the source of the material used in the experiment. Untangling semantic differences between the data provided by different resources is therefore largely reliant on the domain knowledge of a human expert. We present here eVOC, a system which associates labelled target cDNAs for microarray experiments, or cDNA libraries and their associated transcripts with controlled terms in a set of hierarchical vocabularies. eVOC consists of four orthogonal controlled vocabularies suitable for describing the domains of human gene expression data including Anatomical System, Cell Type, Pathology and Developmental Stage. We have curated and annotated 7016 cDNA libraries represented in dbEST, as well as 104 SAGE libraries,with expression information,and provide this as an integrated, public resource that allows the linking of transcripts and libraries with expression terms. Both the vocabularies and the vocabulary-annotated libraries can be retrieved from http://www.sanbi.ac.za/evoc/. Several groups are involved in developing this resource with the aim of unifying transcript expression information.

Animals

Genes required for Mycobacterium tuberculosis to survive the transition from aerosol to pulmonary alveolar lining fluid and early infection in a model of transmission.

Mycobacterium tuberculosis (Mtb) must withstand physical and chemical stresses during airborne transmission, including during the desiccation of aerosols small enough to reach pulmonary alveoli in a new host. There, Mtb encounters an antimicrobial pulmonary alveolar lining fluid (ALF) before it is engulfed by macrophages. To study the genes involved in Mtb's ability to survive the transition from desiccated droplet to pulmonary alveolus in an in vitro model, we formulated a model alveolar lining fluid (MALF) that mimics the composition of ALF as inferred from human bronchoalveolar lavage fluid (BALF). We compared the transcriptome of log-phase Mtb in MALF to the transcriptome of Mtb in BALF as BALF from the lungs of healthy adults was reconstituted to compensate for the dilution of ALF by lavage (rcBALF). Mtb from log-phase culture in a standard laboratory medium survived quantitatively in MALF and rcBALF for at least 24 hours. In contrast, Mtb that had passed through earlier stages of transmission began to succumb after 3 hours in MALF, past the time when particles have been observed to be phagocytized by alveolar macrophages. Screening of a genome-wide CRISPRi library of Mtb identified 35 genes as uniquely required by Mtb to survive the transition from desiccated microdroplet into rehydration in MALF. Thirty-one of these genes are non-essential under conventional laboratory conditions and seven have unknown functions. Thirteen of the 35 genes were additionally required for Mtb to survive in macrophage-like cells cultured at the air-liquid interface with pulmonary epithelial cells. This study nominates additional members of the transmission survival genome of Mtb, illustrates that different genes may contribute to the survival of Mtb at different stages of transmission, and suggests that modeled transmission can shed light on the functions of Mtb genes whose contributions have been unknown.

Journal Article

Cloning and characterization of H4 (D10S170), a gene involved in RET rearrangements in vivo.

H4(D10S170) is a gene which we isolated because of its frequent rearrangement with the RET proto-oncogene in vivo. Its fusion to RET generates the RET/PTC1 oncogene, which has been detected in about 20% of human thyroid papillary carcinomas. We have cloned and sequenced the cDNA corresponding to the H4(D10S170) gene from a human normal thyroid cDNA library. The nucleotide sequence of the H4(D10S170) 3 kb transcript shows no significant homology to known genes and contains an open reading frame (ORF) of 585 amino acids. H4(D10S170) predicted protein has no transmembrane domain and shows extensive regions in the alpha helical conformation, which are 30% homologous to the alpha-helical domains of several proteins including tropomyosin, vimentin, keratin and the tail region of myosin heavy chain. A putative SH3 binding site is present at the carboxy terminus, which suggests that H4(D10S170) might be a cytoskeletal protein.

Amino Acid Sequence

The gut's hidden arsenal: A genomics-guided atlas of class II bacteriocins.

Unmodified class II bacteriocins promise precision antimicrobials that spare bystander microbes. Zhang and colleagues introduce IIBacFinder, a genomics-guided pipeline that detects precursor and context genes with a curated pHMM library, infers leader-peptide cleavage, and triages candidates by meta-omics signals. The authors apply it across bacterial genomes, including an atlas of ∼280,000 human-gut genomes, and recover a vast reservoir of narrow-spectrum peptides and prioritize gut-resident candidates for synthesis. Of the 26 synthesized, 16 display activity in vitro, largely via membrane perturbation and with additive effects alongside vancomycin, while ex vivo assays show minimal compositional disruption of fecal communities compared with antibiotic controls. These results position unmodified class II bacteriocins as tractable, microbiome-sparing agents and illustrate how genome-scale mining coupled to meta-omics can bridge sequence to function in complex ecosystems.

Bacteriocins

Identification of RBP binding sites using RNA deaminases.

RNA-binding proteins (RBPs) are critical regulators of gene expression and RNA processing. Identification of their binding sites has important implications for their physiological and disease-related functions. Crosslinking and immunoprecipitation, followed by sequencing (CLIP-seq) and its derivatives, are the most commonly used methods to identify RBP binding sites, but are laborious and require a large amount of starting material. Recent advancements harnessing RNA deaminases in fusion to any RBP of interest, allow for the profiling of RBP binding sites from low-input samples in simpler procedures. Among these efforts, we developed STAMP (Surveying Targets by APOBEC-Mediated Profiling), which efficiently detects RBP-RNA interactions. This chapter describes the detailed protocol for the STAMP method, including plasmid construction, delivery and sorting, library preparation and bioinformatic data analysis.

RNA-Binding Proteins

Arrangement of coding and intervening sequences of chicken lysozyme gene.

Hybrid phages that contain chicken lysozyme gene sequences have been isolated from a chicken DNA library. Two overlapping clones covering a region of 22 kilobase pairs around this gene have been studied by restriction mapping. Southern hybridization, and electron microscopic analysis of hybrids between lysozyme mRNA and the cloned cellular DNA. Three intervening sequences interrupt the lysozyme structural gene. The cellular gene is at least 3.9 kilobases long, about 6 times the length of the structural gene.

Animals

Quantitative essentiality in a reduced genome: a functional, regulatory and structural fitness map.

Essentiality studies have traditionally focused on coding regions, often overlooking other small genetic regulatory elements. To address this, we combined transposon libraries containing promoter or terminator sequences to obtain a high-resolution essentiality map of a genome-reduced bacterium, at near-single-nucleotide precision when considering non-essential genes. By integrating temporal transposon-sequencing data by k-means unsupervised clustering, we present a novel essentiality assessment approach, providing dynamic and quantitative information on the fitness contribution of different genomic regions. We compared the insertion tolerance and persistence of the two engineered libraries, assessing the local impact of transcription and termination on cell fitness. Essentiality assessment at the local base-level revealed essential protein domains and small genomic regions that are either essential or inaccessible to transposon insertion. We also identified structural regions within essential genes that tolerate transposon disruptions, resulting in functionally split proteins. Overall, this study presents a nuanced view of gene essentiality, shifting from static and binary models to a more accurate perspective. Additionally, it provides valuable insights for genome engineering and enhances our understanding of the biology of genome-reduced cells.

DNA Transposable Elements

The rat serum albumin gene: analysis of cloned sequences.

The rat serum albumin gene has been isolated from a recombinant library containing the entire rat genome cloned in the lambda phage Charon 4A. Preliminary R-loop and restriction analysis has revealed that this gene is split into at least 14 fragments (exons) by 13 intervening sequences (introns), and that it occupies a minimum of 14.5 kilobases of genomic DNA.

Animals

Directed evolution of adeno-associated virus for glioma cell transduction.

Glioblastoma multiforme (GBM) is a serious form of brain cancer for which there is currently no effective treatment. Alternative strategies such as adeno-associated virus (AAV) vector mediated-genetic modification of brain tumor cells with genes encoding anti-tumor proteins have shown promising results in preclinical models of GBM, although the transduction efficiency of these tumors is often low. As higher transduction efficiency of tumor cells should lead to enhanced therapeutic efficacy, a means to rapidly engineer AAV vectors with improved transduction efficiency for individual tumors is an attractive strategy. Here we tested the possibility of identifying high-efficiency AAV vectors for human U87 glioma cells by selection in culture of a newly constructed chimeric AAV capsid library generated by DNA shuffling of six different AAV cap genes (AAV1, AAV2, AAV5, AAVrh.8, AAV9, AAVrh.10). After seven rounds of selection, we obtained a chimeric AAV capsid that transduces U87 cells at high efficiency (97% at a dose of 10(4) genome copies/cell), and at low doses it was 1.45-1.6-fold better than AAV2, which proved to be the most efficient parental capsid. Interestingly, the new AAV capsid displayed robust gene delivery properties to all glioma cells tested (including primary glioma cells) with relative fluorescence indices ranging from 1- to 14-fold higher than AAV2. The selected vector should be useful for in vitro glioma research when efficient transduction of several cell lines is required, and provides proof-of-concept that an AAV library can be used to generate AAV vectors with enhanced transduction efficiency of glioma cells.

Capsid Proteins

Machine learning-based analysis of the impact of 5' untranslated region on protein expression.

The 5' untranslated region (5'UTR) plays a crucial regulatory role in messenger RNA (mRNA), with modified 5'UTRs extensively utilized in vaccine production, gene therapy, etc. Nevertheless, manually optimizing 5'UTRs may encounter difficulties in balancing the effects of various cis-elements. Consequently, multiple 5'UTR libraries have been created, and machine learning models have been employed to analyze and predict translation efficiency (TE) and protein expression, providing insights into critical regulatory features. On the one hand, these screening libraries, based on TE and mean ribosome load, struggle to accurately quantify protein expression; on the other hand, a precise method for quantifying 5'UTRs necessitates a significantly costlier library. To resolve this dilemma, we constructed a library utilizing firefly luciferase as the reporter to measure accurate protein expression. In addition, we optimized the library construction method by clustering mRNA sequences to reduce redundant data and minimize the size of the dataset. This dual strategy by increasing accuracy and reducing dataset size was found to be effective in predicting the 5'UTRs from the PC3 cell line.

5' Untranslated Regions

Uncovering host transcriptional responses to tilapia lake virus (TiLV) through De novo RNA-seq assembly in Nile tilapia, Oreochromis niloticus.

Tilapia lake virus (TiLV) has emerged as an important pathogen that negatively impacts tilapia farming globally. Using RNA sequencing technology, this study investigated the liver transcriptomic profile of apparently healthy and TiLV-infected Oreochromis niloticus from wild. RNA sequence libraries generated 3,356 differentially expressed genes (DEGs), with 1,726 genes that were upregulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 680 different pathways with differential regulation of the metabolic and immune-related pathways indicating that TiLV may interfere in host metabolism and replicate to establish the infection. This study provides transcriptomic insights into the liver responses of naturally TiLV-infected wild O. niloticus and highlights key immune and metabolic pathways associated with viral infection.

Animals

Comparative metagenomic assessment of Illumina-compatible library preparation methods, short-read lengths, and PacBio HiFi sequencing reveals differences in microbial and functional diversity recovery from a complex environmental sample.

UNLABELLED: Metagenomics enables comprehensive exploration of microbial communities but is influenced by library preparation and sequencing technologies, affecting recovery of microbial genomes and proteins. Here, we benchmarked six Illumina-compatible short-read library preparation conditions in triplicate at 2 × 150 bp and 2 × 250 bp read lengths alongside PacBio HiFi long-read sequencing using a composite environmental sample of marine mangrove sediment and terrestrial palm tree soil. Longer short reads (2 × 250 bp) combined with optimal library preparation approaches improved assembly quality, protein detection, and metagenome-assembled genome (MAG) recovery, achieving results approaching those of long-read sequencing. TruSeq libraries at 2 × 250 bp recovered more than sevenfold more unique proteins than the same kit at 2 × 150 bp (811,701 vs 110,108) using the same number of sequencing reads, while recovering a comparable number of high-quality MAGs to PacBio HiFi long-read sequencing (11 vs 18) and surpassing it in protein discovery by almost 10-fold (811,701 vs 87,745) at less than half of the sequencing cost. Furthermore, biosynthetic gene cluster analysis identified 46 biosynthetic gene clusters in TruSeq-250PE assemblies compared to 38 in PacBio HiFi, with several showing no close match in the MIBiG database. Although long reads yield more contiguity and complete genomes, longer short reads offer a cost-effective, scalable alternative for uncovering microbial and functional diversity. These findings provide critical guidance for metagenomic experimental design, demonstrating that strategic selection of library preparation chemistry and sequencing parameters can reveal more unknown microbial information in complex biomes without requiring additional sequencing depth. IMPORTANCE: Metagenomic outcomes are strongly influenced by library preparation and sequencing strategies, yet their combined effects in complex environmental samples remain poorly defined. Here, we provide the first direct comparison of Illumina NovaSeq short-read metagenomic sequencing at 2 × 150 bp and 2 × 250 bp across multiple library preparation kits, alongside PacBio HiFi long-read sequencing. We show that sequencing read length and library preparation critically shape assembly quality, protein recovery, and metagenome-assembled genome (MAG) reconstruction. These findings demonstrate that short-read sequencing at 2 × 250 bp, with appropriate library preparation, can match long-read technologies in MAG recovery while substantially surpassing them in protein discovery. With less than half of the sequencing price and a 3.5-fold reduction in cost per gigabase of usable data, this method facilitates more accessible large-scale metagenomic analysis within complex environmental systems.

Metagenomics

Synonymous mutations in essential genes infrequently produce fitness effects in human cell lines.

The assumption that synonymous mutations are fitness-neutral is central to many foundational results in the fields of genetics, genomics, evolutionary biology, and medicine. However, recent results suggest synonymous mutations have pervasive and strong fitness effects. These vigorously debated studies in non-human model systems have even suggested that the proportion of synonymous mutations and their fitness effect sizes are similar to non-synonymous mutations. To probe the fitness effect of synonymous mutations, we utilized recent advances in base editing to test 8558 potential synonymous mutations in 128 highly essential genes in human cell lines. Importantly, our library design excluded splice-proximal sites, ensuring a direct test of codon-level synonymous effects independent of splicing disruption. We find that synonymous mutations rarely have fitness effects on growth, occurring around 37.9-fold (95% CI: 22.16-81.48-fold) less frequently than missense mutations. In this experimental context, these findings demonstrate that synonymous mutations impact cellular fitness far less frequently than missense mutations. These results deviate from earlier reports of widespread synonymous fitness effects in yeast, yet they align with recent prime editing data observed in other human cell lines.

Humans

Reversal of cancer gene expression identifies repurposed drugs for diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is an aggressive incurable brainstem tumor that targets young children. Complete resection is not possible, and chemotherapy and radiotherapy are currently only palliative. This study aimed to identify potential therapeutic agents using a computational pipeline to perform an in silico screen for novel drugs. We then tested the identified drugs against a panel of patient-derived DIPG cell lines. Using a systematic computational approach with publicly available databases of gene signature in DIPG patients and cancer cell lines treated with a library of clinically available drugs, we identified drug hits with the ability to reverse a DIPG gene signature to one that matches normal tissue background. The biological and molecular effects of drug treatment was analyzed by cell viability assay and RNA sequence. In vivo DIPG mouse model survival studies were also conducted. As a result, two of three identified drugs showed potency against the DIPG cell lines Triptolide and mycophenolate mofetil (MMF) demonstrated significant inhibition of cell viability in DIPG cell lines. Guanosine rescued reduced cell viability induced by MMF. In vivo, MMF treatment significantly inhibited tumor growth in subcutaneous xenograft mice models. In conclusion, we identified clinically available drugs with the ability to reverse DIPG gene signatures and anti-DIPG activity in vitro and in vivo. This novel approach can repurpose drugs and significantly decrease the cost and time normally required in drug discovery.

Humans

Sites in the AAV5 capsid tolerant to deletions and tandem duplications.

Gene therapy vectors based on adeno-associated virus (AAV) have shown much promise in clinical trials for the treatment of a variety of diseases. However, the ability to manipulate and engineer the viral surface for enhanced efficiency is necessary to overcome such barriers as pre-existing immunity and transduction of non-target cells that currently limit AAV applications. Although single amino acid changes and peptide insertions at select sites have been explored previously, the tolerance of AAV to small deletions and tandem duplications of sequence has not been globally addressed. Here, we have generated a large, diverse library of >10(5) members containing deletions and tandem duplications throughout the viral capsid of AAV5. Four unique mutants were identified that maintain the ability to form viral particles, with one showing improved transduction on both 293T and BEAS-2B cells. This approach may find potential use for the generation of novel variants with improved and altered properties or in the identification of sites that are tolerant to insertions of targeting ligands.

Amino Acid Sequence

Transcriptomic Profiling of Canine Testicular Leydig Cell Tumors Uncovers Key Upregulated Gene Pathways.

Total RNA was isolated from sections of healthy testes and Leydig cell tumors of mixed-breed dogs using TMA Master II device. The RNA-seq libraries were sequenced on the Illumina platform. Following differential expression analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were applied with quality control obtained using FastQC and Trimmomatic. This analysis revealed 1500 transcripts, including 928 upregulated and 168 downregulated genes. The results demonstrated that a significant proportion of these differentially expressed genes are directly involved in the control of sex steroid production (CYP11A1, STAR, and 3β-HSD3B1) or tube formation, angiogenesis, and extracellular matrix remodeling in interstitial cells (ESM1, FGG, and VEGFA). Moreover, we identified the upregulation of transcripts responsible for neurotransmitter or neuroendocrine signaling (SLC6A4, GRIN2C, GABRB3) and cholesterol metabolism and its regulation (GPX3, MSMO1, DHCR24). These genes were strongly associated with the phosphatidylinositol-3-kinase (PI3K)-Protein Kinase B (Akt) cascade and extracellular matrix interactions, features shared with various malignancies. Alterations in estrogen and relaxin signaling appear to be distinctive, understudied mechanisms specific to canine Leydig cell tumors. Concurrently, downregulated genes (e.g., DMRTC2, SEMA3C, ALOX12) were linked with cell differentiation, signaling and immunoregulatory pathway suppression involved in tumorigenesis. A complex transcriptomic profile of canine Leydig cell tumors was developed, revealing a conserved oncogenic core shared in some aspects with human malignancies alongside unique species-specific alterations. Findings seem to be useful for identifying novel diagnostic biomarkers and targeted therapies in veterinary oncology, establishing canine reproductive tissues as a valuable comparative biomedical model for research in human.

Leydig cell tumor