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1.
Sci Adv ; 10(19): eadn1547, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38718117

RESUMEN

Pre-mRNA splicing is a fundamental step in gene expression, conserved across eukaryotes, in which the spliceosome recognizes motifs at the 3' and 5' splice sites (SSs), excises introns, and ligates exons. SS recognition and pairing is often influenced by protein splicing factors (SFs) that bind to splicing regulatory elements (SREs). Here, we describe SMsplice, a fully interpretable model of pre-mRNA splicing that combines models of core SS motifs, SREs, and exonic and intronic length preferences. We learn models that predict SS locations with 83 to 86% accuracy in fish, insects, and plants and about 70% in mammals. Learned SRE motifs include both known SF binding motifs and unfamiliar motifs, and both motif classes are supported by genetic analyses. Our comparisons across species highlight similarities between non-mammals, increased reliance on intronic SREs in plant splicing, and a greater reliance on SREs in mammalian splicing.


Asunto(s)
Exones , Intrones , Precursores del ARN , Sitios de Empalme de ARN , Empalme del ARN , Precursores del ARN/genética , Precursores del ARN/metabolismo , Animales , Intrones/genética , Exones/genética , Genes de Plantas , Modelos Genéticos , Empalmosomas/metabolismo , Empalmosomas/genética , Plantas/genética , Humanos , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo
2.
Nat Commun ; 15(1): 3839, 2024 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-38714659

RESUMEN

Pre-mRNA splicing, a key process in gene expression, can be therapeutically modulated using various drug modalities, including antisense oligonucleotides (ASOs). However, determining promising targets is hampered by the challenge of systematically mapping splicing-regulatory elements (SREs) in their native sequence context. Here, we use the catalytically inactive CRISPR-RfxCas13d RNA-targeting system (dCas13d/gRNA) as a programmable platform to bind SREs and modulate splicing by competing against endogenous splicing factors. SpliceRUSH, a high-throughput screening method, was developed to map SREs in any gene of interest using a lentivirus gRNA library that tiles the genetic region, including distal intronic sequences. When applied to SMN2, a therapeutic target for spinal muscular atrophy, SpliceRUSH robustly identifies not only known SREs but also a previously unknown distal intronic SRE, which can be targeted to alter exon 7 splicing using either dCas13d/gRNA or ASOs. This technology enables a deeper understanding of splicing regulation with applications for RNA-based drug discovery.


Asunto(s)
Sistemas CRISPR-Cas , Exones , Intrones , Empalme del ARN , ARN Guía de Sistemas CRISPR-Cas , Proteína 2 para la Supervivencia de la Neurona Motora , Humanos , Empalme del ARN/genética , Proteína 2 para la Supervivencia de la Neurona Motora/genética , ARN Guía de Sistemas CRISPR-Cas/genética , Intrones/genética , Exones/genética , Células HEK293 , Oligonucleótidos Antisentido/genética , Atrofia Muscular Espinal/genética , Secuencias Reguladoras de Ácidos Nucleicos/genética , Precursores del ARN/genética , Precursores del ARN/metabolismo
3.
Nat Commun ; 15(1): 3786, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38710690

RESUMEN

Expression quantitative trait loci (eQTL) studies typically consider exon expression of genes and discard intronic RNA sequencing reads despite their information on RNA metabolism. Here, we quantify genetic effects on exon and intron levels of genes and their ratio in lymphoblastoid cell lines, revealing thousands of cis-QTLs of each type. While genetic effects are often shared between cis-QTL types, 7814 (47%) are not detected as top cis-QTLs at exon levels. We show that exon levels preferentially capture genetic effects on transcriptional regulation, while exon-intron-ratios better detect those on co- and post-transcriptional processes. Considering all cis-QTL types substantially increases (by 71%) the number of colocalizing variants identified by genome-wide association studies (GWAS). It further allows dissecting the potential gene regulatory processes underlying GWAS associations, suggesting comparable contributions by transcriptional (50%) and co- and post-transcriptional regulation (46%) to complex traits. Overall, integrating intronic RNA sequencing reads in eQTL studies expands our understanding of genetic effects on gene regulatory processes.


Asunto(s)
Exones , Regulación de la Expresión Génica , Estudio de Asociación del Genoma Completo , Intrones , Sitios de Carácter Cuantitativo , Humanos , Intrones/genética , Exones/genética , Transcripción Genética , Línea Celular , Análisis de Secuencia de ARN/métodos , Polimorfismo de Nucleótido Simple
4.
Nat Commun ; 15(1): 3773, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38710738

RESUMEN

Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive chorioretinal degenerative disease without approved therapeutic drugs. It is caused by mutations in CYP4V2 gene, and about 80% of BCD patients carry mutations in exon 7 to 11. Here, we apply CRISPR/Cas9 mediated homology-independent targeted integration (HITI)-based gene editing therapy in HEK293T cells, BCD patient derived iPSCs, and humanized Cyp4v3 mouse model (h-Cyp4v3mut/mut) using two rAAV2/8 vectors via sub-retinal administration. We find that sgRNA-guided Cas9 generates double-strand cleavage on intron 6 of the CYP4V2 gene, and the HITI donor inserts the carried sequence, part of intron 6, exon 7-11, and a stop codon into the DNA break, achieving precise integration, effective transcription and translation both in vitro and in vivo. HITI-based editing restores the viability of iPSC-RPE cells from BCD patient, improves the morphology, number and metabolism of RPE and photoreceptors in h-Cyp4v3mut/mut mice. These results suggest that HITI-based editing could be a promising therapeutic strategy for those BCD patients carrying mutations in exon 7 to 11, and one injection will achieve lifelong effectiveness.


Asunto(s)
Sistemas CRISPR-Cas , Distrofias Hereditarias de la Córnea , Familia 4 del Citocromo P450 , Edición Génica , Terapia Genética , Células Madre Pluripotentes Inducidas , Enfermedades de la Retina , Humanos , Edición Génica/métodos , Animales , Células HEK293 , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/terapia , Distrofias Hereditarias de la Córnea/patología , Distrofias Hereditarias de la Córnea/metabolismo , Ratones , Células Madre Pluripotentes Inducidas/metabolismo , Terapia Genética/métodos , Familia 4 del Citocromo P450/genética , Familia 4 del Citocromo P450/metabolismo , Modelos Animales de Enfermedad , Mutación , Epitelio Pigmentado de la Retina/metabolismo , Epitelio Pigmentado de la Retina/patología , Vectores Genéticos/genética , Intrones/genética , Exones/genética
5.
Infect Dis Poverty ; 13(1): 29, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38622750

RESUMEN

BACKGROUND: Culex pipiens pallens and Culex pipiens quinquefasciatus are the dominant species of Culex mosquitoes in China and important disease vectors. Long-term use of insecticides can cause mutations in the voltage-gated sodium channel (vgsc) gene of mosquitoes, but little is known about the current status and evolutionary origins of vgsc gene in different geographic populations. Therefore, this study aimed to determine the current status of vgsc genes in Cx. p. pallens and Cx. p. quinquefasciatus in China and to investigate the evolutionary inheritance of neighboring downstream introns of the vgsc gene to determine the impact of insecticides on long-term evolution. METHODS: Sampling was conducted from July to September 2021 in representative habitats of 22 provincial-level administrative divisions in China. Genomic DNA was extracted from 1308 mosquitoes, the IIS6 fragment of the vgsc gene on the nerve cell membrane was amplified using polymerase chain reaction, and the sequence was used to evaluate allele frequency and knockdown resistance (kdr) frequency. MEGA 11 was used to construct neighbor-joining (NJ) tree. PopART was used to build a TCS network. RESULTS: There were 6 alleles and 6 genotypes at the L1014 locus, which included the wild-type alleles TTA/L and CTA/L and the mutant alleles TTT/F, TTC/F, TCT/S and TCA/S. The geographic populations with a kdr frequency less than 20.00% were mainly concentrated in the regions north of 38° N, and the geographic populations with a kdr frequency greater than 80.00% were concentrated in the regions south of 30° N. kdr frequency increased with decreasing latitude. And within the same latitude, the frequency of kdr in large cities is relatively high. Mutations were correlated with the number of introns. The mutant allele TCA/S has only one intron, the mutant allele TTT/F has three introns, and the wild-type allele TTA/L has 17 introns. CONCLUSIONS: Cx. p. pallens and Cx. p. quinquefasciatus have developed resistance to insecticides in most regions of China. The neighboring downstream introns of the vgsc gene gradually decreased to one intron with the mutation of the vgsc gene. Mutations may originate from multiple mutation events rather than from a single origin, and populations lacking mutations may be genetically isolated.


Asunto(s)
Culex , Culicidae , Insecticidas , Piretrinas , Canales de Sodio Activados por Voltaje , Animales , Insecticidas/farmacología , Intrones/genética , Mosquitos Vectores/genética , Culex/genética , Mutación , Canales de Sodio Activados por Voltaje/genética , Resistencia a los Insecticidas/genética
6.
Elife ; 122024 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-38577979

RESUMEN

Splicing is the stepwise molecular process by which introns are removed from pre-mRNA and exons are joined together to form mature mRNA sequences. The ordering and spatial distribution of these steps remain controversial, with opposing models suggesting splicing occurs either during or after transcription. We used single-molecule RNA FISH, expansion microscopy, and live-cell imaging to reveal the spatiotemporal distribution of nascent transcripts in mammalian cells. At super-resolution levels, we found that pre-mRNA formed clouds around the transcription site. These clouds indicate the existence of a transcription-site-proximal zone through which RNA move more slowly than in the nucleoplasm. Full-length pre-mRNA undergo continuous splicing as they move through this zone following transcription, suggesting a model in which splicing can occur post-transcriptionally but still within the proximity of the transcription site, thus seeming co-transcriptional by most assays. These results may unify conflicting reports of co-transcriptional versus post-transcriptional splicing.


Asunto(s)
Precursores del ARN , Transcripción Genética , Animales , Precursores del ARN/genética , Precursores del ARN/metabolismo , Empalme del ARN , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN , Intrones/genética , Mamíferos/genética
7.
Microb Biotechnol ; 17(5): e14472, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38683679

RESUMEN

The availability of an alternative and efficient genetic editing technology is critical for fundamental research and strain improvement engineering of Streptomyces species, which are prolific producers of complex secondary metabolites with significant pharmaceutical activities. The mobile group II introns are retrotransposons that employ activities of catalytic intron RNAs and intron-encoded reverse transcriptase to precisely insert into DNA target sites through a mechanism known as retrohoming. We here developed a group II intron-based gene editing tool to achieve precise chromosomal gene insertion in Streptomyces. Moreover, by repressing the potential competition of RecA-dependent homologous recombination, we enhanced site-specific insertion efficiency of this tool to 2.38%. Subsequently, we demonstrated the application of this tool by screening and characterizing the secondary metabolite biosynthetic gene cluster (BGC) responsible for synthesizing the red pigment in Streptomyces roseosporus. Accompanied with identifying and inactivating this BGC, we observed that the impair of this cluster promoted cell growth and daptomycin production. Additionally, we applied this tool to activate silent jadomycin BGC in Streptomyces venezuelae. Overall, this work demonstrates the potential of this method as an alternative tool for genetic engineering and cryptic natural product mining in Streptomyces species.


Asunto(s)
Intrones , Familia de Multigenes , Streptomyces , Streptomyces/genética , Streptomyces/metabolismo , Intrones/genética , Edición Génica/métodos , Mutagénesis Insercional/métodos , Metabolismo Secundario/genética , Vías Biosintéticas/genética , Recombinación Homóloga
8.
Nat Commun ; 15(1): 2837, 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38565566

RESUMEN

The adult mammalian brain retains some capacity to replenish neurons and glia, holding promise for brain regeneration. Thus, understanding the mechanisms controlling adult neural stem cell (NSC) differentiation is crucial. Paradoxically, adult NSCs in the subependymal zone transcribe genes associated with both multipotency maintenance and neural differentiation, but the mechanism that prevents conflicts in fate decisions due to these opposing transcriptional programmes is unknown. Here we describe intron detention as such control mechanism. In NSCs, while multiple mRNAs from stemness genes are spliced and exported to the cytoplasm, transcripts from differentiation genes remain unspliced and detained in the nucleus, and the opposite is true under neural differentiation conditions. We also show that m6A methylation is the mechanism that releases intron detention and triggers nuclear export, enabling rapid and synchronized responses. m6A RNA methylation operates as an on/off switch for transcripts with antagonistic functions, tightly controlling the timing of NSCs commitment to differentiation.


Asunto(s)
Células-Madre Neurales , Animales , Intrones/genética , Diferenciación Celular/genética , Neuronas , Neurogénesis/genética , Mamíferos
9.
Chaos ; 34(4)2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38579148

RESUMEN

Two well-known facets in protein synthesis in eukaryotic cells are transcription of DNA to pre-RNA in the nucleus and the translation of messenger-RNA (mRNA) to proteins in the cytoplasm. A critical intermediate step is the removal of segments (introns) containing ∼97% of the nucleic-acid sites in pre-RNA and sequential alignment of the retained segments (exons) to form mRNA through a process referred to as splicing. Alternative forms of splicing enrich the proteome while abnormal splicing can enhance the likelihood of a cell developing cancer or other diseases. Mechanisms for splicing and origins of splicing errors are only partially deciphered. Our goal is to determine if rules on splicing can be inferred from data analytics on nucleic-acid sequences. Toward that end, we represent a nucleic-acid site as a point in a plane defined in terms of the anterior and posterior sub-sequences of the site. The "point-set" representation expands analytical approaches, including the use of statistical tools, to characterize genome sequences. It is found that point-sets for exons and introns are visually different, and that the differences can be quantified using a family of generalized moments. We design a machine-learning algorithm that can recognize individual exons or introns with 91% accuracy. Point-set distributions and generalized moments are found to differ between organisms.


Asunto(s)
Empalme del ARN , ARN , Intrones/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Exones/genética
10.
BMC Genomics ; 25(1): 410, 2024 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-38664648

RESUMEN

BACKGROUND: Genomic architecture is a key evolutionary trait for living organisms. Due to multiple complex adaptive and neutral forces which impose evolutionary pressures on genomes, there is a huge variability of genomic features. However, their variability and the extent to which genomic content determines the distribution of recovered loci in reduced representation sequencing studies is largely unexplored. RESULTS: Here, by using 80 genome assemblies, we observed that whereas plants primarily increase their genome size by expanding their intergenic regions, animals expand both intergenic and intronic regions, although the expansion patterns differ between deuterostomes and protostomes. Loci mapping in introns, exons, and intergenic categories obtained by in silico digestion using 2b-enzymes are positively correlated with the percentage of these regions in the corresponding genomes, suggesting that loci distribution mostly mirrors genomic architecture of the selected taxon. However, exonic regions showed a significant enrichment of loci in all groups regardless of the used enzyme. Moreover, when using selective adaptors to obtain a secondarily reduced loci dataset, the percentage and distribution of retained loci also varied. Adaptors with G/C terminals recovered a lower percentage of selected loci, with a further enrichment of exonic regions, while adaptors with A/T terminals retained a higher percentage of loci and slightly selected more intronic regions than expected. CONCLUSIONS: Our results highlight how genome composition, genome GC content, RAD enzyme choice and use of base-selective adaptors influence reduced genome representation techniques. This is important to acknowledge in population and conservation genomic studies, as it determines the abundance and distribution of loci.


Asunto(s)
Composición de Base , Genómica , Genómica/métodos , Animales , Intrones/genética , Genoma , Exones/genética , Sitios Genéticos , Tamaño del Genoma , Plantas/genética , ADN Intergénico/genética
11.
Gene ; 915: 148429, 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-38575098

RESUMEN

Bioinformatics is a contemporary interdisciplinary area focused on analyzing the growing number of genome sequences. Gene variants are differences in DNA sequences among individuals within a population. Splice site recognition is a crucial step in the process of gene expression, where the coding sequences of genes are joined together to form mature messenger RNA (mRNA). These genetic variants that disrupt genes are believed to be the primary reason for neuro-developmental disorders like ASD (Autism Spectrum Disorder) is a neuro-developmental disorder that is diagnosed in individuals, families, and society and occurs as the developmental delay in one among the hundred genes that are associated with these disorders. Missense variants, premature stop codons, or deletions alter both the quality and quantity of encoded proteins. Predicting genes within exons and introns presents main challenges, such as dealing with sequencing errors, short reads, incomplete genes, overlapping, and more. Although many traditional techniques have been utilized in creating an exon prediction system, the primary challenge lies in accurately identifying the length and spliced strand location classification of exons in conjunction with introns. From now on, the suggested approach utilizes a Deep Learning algorithm to analyze intricate and extensive genomic datasets. M-LSTM is utilized to categorize three binary combinations (EI as 1, IE as 2, and none as 3) using spliced DNA strands. The M-LSTM system is able to sequence extensive datasets, ensuring that long information can be stored without any impact on the current input or output. This enables it to recognize and address long-term connections and problems with rapidly increasing gradients. The proposed model is compared internally with Naïve Bayes and Random Forest to assess its efficacy. Additionally, the proposed model's performance is forecasted by utilizing probabilistic parameters like recall, F1-score, precision, and accuracy to assess the effectiveness of the proposed system.


Asunto(s)
Exones , Intrones , Sitios de Empalme de ARN , Exones/genética , Humanos , Intrones/genética , Biología Computacional/métodos , Empalme del ARN , Trastorno del Espectro Autista/genética , Algoritmos , Aprendizaje Profundo
12.
Biosystems ; 239: 105215, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38641199

RESUMEN

A massive statistical analysis based on the autocorrelation function of the circular code X observed in genes is performed on the (eukaryotic) introns. Surprisingly, a circular code periodicity 0 modulo 3 is identified in 5 groups of introns: birds, ascomycetes, basidiomycetes, green algae and land plants. This circular code periodicity, which is a property of retrieving the reading frame in (protein coding) genes, may suggest that these introns have a coding property. In a well-known way, a periodicity 1 modulo 2 is observed in 6 groups of introns: amphibians, fishes, mammals, other animals, reptiles and apicomplexans. A mixed periodicity modulo 2 and 3 is found in the introns of insects. Astonishing, a subperiodicity 3 modulo 6 is a common statistical property in these 3 classes of introns. When the particular trinucleotides N1N2N1 of the circular code X are not considered, the circular code periodicity 0 modulo 3, hidden by the periodicity 1 modulo 2, is now retrieved in 5 groups of introns: amphibians, fishes, other animals, reptiles and insects. Thus, 10 groups of introns, taxonomically different, out of 12 have a coding property related to the reading frame retrieval. The trinucleotides N1N2N1 are analysed in the 216 maximal C3 self-complementary trinucleotide circular codes. A hexanucleotide code (words of 6 letters) is proposed to explain the periodicity 3 modulo 6. It could be a trace of more general circular codes at the origin of the circular code X.


Asunto(s)
Código Genético , Intrones , Intrones/genética , Animales , Código Genético/genética , Evolución Molecular
13.
Muscle Nerve ; 69(6): 708-718, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38558464

RESUMEN

INTRODUCTION/AIMS: GNE myopathy is a rare autosomal recessive disorder caused by pathogenic variants in the GNE gene, which is essential for the sialic acid biosynthesis pathway. Although over 300 GNE variants have been reported, some patients remain undiagnosed with monoallelic pathogenic variants. This study aims to analyze the entire GNE genomic region to identify novel pathogenic variants. METHODS: Patients with clinically compatible GNE myopathy and monoallelic pathogenic variants in the GNE gene were enrolled. The other GNE pathogenic variant was verified using comprehensive methods including exon 2 quantitative polymerase chain reaction and nanopore long-read single-molecule sequencing (LRS). RESULTS: A deep intronic GNE variant, c.862+870C>T, was identified in nine patients from eight unrelated families. This variant generates a cryptic splice site, resulting in the activation of a novel pseudoexon between exons 5 and 6. It results in the insertion of an extra 146 nucleotides into the messengerRNA (mRNA), which is predicted to result in a truncated humanGNE1(hGNE1) protein. Peanut agglutinin(PNA) lectin staining of muscle tissues showed reduced sialylation of mucin O-glycans on sarcolemmal glycoproteins. Notably, a third of patients with the c.862+870C>T variant exhibited thrombocytopenia. A common core haplotype harboring the deep intronic GNE variant was found in all these patients. DISCUSSION: The transcript with pseudoexon activation potentially affects sialic acid biosynthesis via nonsense-mediated mRNA decay, or resulting in a truncated hGNE1 protein, which interferes with normal enzyme function. LRS is expected to be more frequently incorporated in genetic analysis given its efficacy in detecting hard-to-find pathogenic variants.


Asunto(s)
Exones , Intrones , Complejos Multienzimáticos , Trombocitopenia , Humanos , Masculino , Femenino , Complejos Multienzimáticos/genética , Exones/genética , Intrones/genética , Adulto , Trombocitopenia/genética , Miopatías Distales/genética , Adulto Joven , Adolescente , Niño , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Linaje , Persona de Mediana Edad
14.
Oncogene ; 43(20): 1565-1578, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38561505

RESUMEN

Accumulating studies suggest that splicing factors play important roles in many diseases including human cancers. Our study revealed that WBP11, a core splicing factor, is highly expressed in ovarian cancer (OC) tissues and associated with a poor prognosis. WBP11 inhibition significantly impaired the proliferation and mobility of ovarian cancer cells in vitro and in vivo. Furthermore, FOXM1 transcriptionally activated WBP11 expression by directly binding to its promoter in OC cells. Importantly, RNA-seq and alternative splicing event analysis revealed that WBP11 silencing decreased the expression of MCM7 by regulating intron 4 retention. MCM7 inhibition attenuated the increase in malignant behaviors of WBP11-overexpressing OC cells. Overall, WBP11 was identified as an oncogenic splicing factor that contributes to malignant progression by repressing intron 4 retention of MCM7 in OC cells. Thus, WBP11 is an oncogenic splicing factor with potential therapeutic and prognostic implications in OC.


Asunto(s)
Proliferación Celular , Progresión de la Enfermedad , Regulación Neoplásica de la Expresión Génica , Intrones , Componente 7 del Complejo de Mantenimiento de Minicromosoma , Neoplasias Ováricas , Humanos , Neoplasias Ováricas/genética , Neoplasias Ováricas/patología , Neoplasias Ováricas/metabolismo , Femenino , Intrones/genética , Componente 7 del Complejo de Mantenimiento de Minicromosoma/genética , Componente 7 del Complejo de Mantenimiento de Minicromosoma/metabolismo , Animales , Línea Celular Tumoral , Ratones , Proliferación Celular/genética , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo , Pronóstico , Proteína Forkhead Box M1/genética , Proteína Forkhead Box M1/metabolismo , Ratones Desnudos , Empalme Alternativo/genética
15.
Nucleic Acid Ther ; 34(2): 73-82, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38466963

RESUMEN

Pathogenic variants in ABCA4 are the underlying molecular cause of Stargardt disease (STGD1), an autosomal recessive macular dystrophy characterized by a progressive loss of central vision. Among intronic ABCA4 variants, c.4253+43G>A is frequently detected in STGD1 cases and is classified as a hypomorphic allele, generally associated with late-onset cases. This variant was previously reported to alter splicing regulatory sequences, but the splicing outcome is not fully understood yet. In this study, we attempted to better understand its effect on splicing and to rescue the aberrant splicing via antisense oligonucleotides (AONs). Wild-type and c.4253+43G>A variant-harboring maxigene vectors revealed additional skipping events, which were not previously detected upon transfection in HEK293T cells. To restore exon inclusion, we designed a set of 27 AONs targeting either splicing silencer motifs or the variant region and screened these in maxigene-transfected HEK293T cells. Candidate AONs able to promote exon inclusion were selected for further testing in patient-derived photoreceptor precursor cells. Surprisingly, no robust splicing modulation was observed in this model system. Overall, this research helped to adequately characterize the splicing alteration caused by the c.4253+43G>A variant, although future development of AON-mediated exon inclusion therapy for ABCA4 is needed.


Asunto(s)
Transportadoras de Casetes de Unión a ATP , Degeneración Macular , Humanos , Enfermedad de Stargardt/genética , Células HEK293 , Intrones/genética , Transportadoras de Casetes de Unión a ATP/genética , Degeneración Macular/genética , Degeneración Macular/terapia , Mutación
16.
J Mol Biol ; 436(8): 168513, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38447889

RESUMEN

Systemic fungal infections are a growing public health threat, and yet viable antifungal drug targets are limited as fungi share a similar proteome with humans. However, features of RNA metabolism and the noncoding transcriptomes in fungi are distinctive. For example, fungi harbor highly structured RNA elements that humans lack, such as self-splicing introns within key housekeeping genes in the mitochondria. However, the location and function of these mitochondrial riboregulatory elements has largely eluded characterization. Here we used an RNA-structure-based bioinformatics pipeline to identify the group I introns interrupting key mitochondrial genes in medically relevant fungi, revealing their fixation within a handful of genetic hotspots and their ubiquitous presence across divergent phylogenies of fungi, including all highest priority pathogens such as Candida albicans, Candida auris, Aspergillus fumigatus and Cryptococcus neoformans. We then biochemically characterized two representative introns from C. albicans and C. auris, demonstrating their exceptionally efficient splicing catalysis relative to previously-characterized group I introns. Indeed, the C. albicans mitochondrial intron displays extremely rapid catalytic turnover, even at ambient temperatures and physiological magnesium ion concentrations. Our results unmask a significant new set of players in the RNA metabolism of pathogenic fungi, suggesting a promising new type of antifungal drug target.


Asunto(s)
Antifúngicos , Candida albicans , Intrones , Humanos , Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Candida albicans/genética , Intrones/genética , Empalme del ARN/genética , ARN de Hongos/metabolismo
17.
Plant Sci ; 342: 112056, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38438082

RESUMEN

Most of mRNAs in Eukaryote were matured after the removal of introns in their pre-mRNA transcripts. Serine/arginine-rich (SR) proteins are a group of splicing regulators regulating the splicing processes globally. Expressions of SR proteins themselves were extensively regulated, at both transcription and splicing levels, under different environmental conditions, specially heat stress conditions. The pine genome is characterized by super-long and easily methylated introns in a large number of genes that derived from the extensive accumulation of transposons (TEs). Here, we identified and analyzed the phylogenetic characteristics of 24 SR proteins and their encoding genes from the pine genome. Then we explored transcription and pre-mRNA splicing expression patterns of SR genes in P. massoniana seedlings under normal and heat stress temperature conditions. Our results showed that the transcription patterns of SR genes in pine exhibited significant changes compared to other plant species, and these changes were not strictly correlated with the intron length and DNA methylation intensity of the SR genes. Interestingly, none of the long introns of SR genes underwent alternative splicing (AS) in our experiment. Furthermore, the intensity of AS regulation may be related to the potential DNA methylation intensity of SR genes. Taken together, this study explores for the first time the characteristics of significant variations in the transcription and splicing patterns of SR proteins in a plant species with an over-accumulation of super-long introns.


Asunto(s)
Arabidopsis , Precursores del ARN , Intrones/genética , Precursores del ARN/genética , Filogenia , Arabidopsis/genética , Empalme del ARN , Empalme Alternativo/genética
18.
Nat Commun ; 15(1): 2583, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38519498

RESUMEN

Alternative polyadenylation can occur in introns, termed intronic polyadenylation (IPA), has been implicated in diverse biological processes and diseases, as it can produce noncoding transcripts or transcripts with truncated coding regions. However, a reliable method is required to accurately characterize IPA. Here, we propose a computational method called InPACT, which allows for the precise characterization of IPA from conventional RNA-seq data. InPACT successfully identifies numerous previously unannotated IPA transcripts in human cells, many of which are translated, as evidenced by ribosome profiling data. We have demonstrated that InPACT outperforms other methods in terms of IPA identification and quantification. Moreover, InPACT applied to monocyte activation reveals temporally coordinated IPA events. Further application on single-cell RNA-seq data of human fetal bone marrow reveals the expression of several IPA isoforms in a context-specific manner. Therefore, InPACT represents a powerful tool for the accurate characterization of IPA from RNA-seq data.


Asunto(s)
Poliadenilación , ARN , Humanos , Poliadenilación/genética , Intrones/genética , Análisis de Secuencia de ARN , RNA-Seq
19.
Nucleic Acids Res ; 52(7): 4037-4052, 2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38499487

RESUMEN

Here, we identify RBM41 as a novel unique protein component of the minor spliceosome. RBM41 has no previously recognized cellular function but has been identified as a paralog of U11/U12-65K, a known unique component of the U11/U12 di-snRNP. Both proteins use their highly similar C-terminal RRMs to bind to 3'-terminal stem-loops in U12 and U6atac snRNAs with comparable affinity. Our BioID data indicate that the unique N-terminal domain of RBM41 is necessary for its association with complexes containing DHX8, an RNA helicase, which in the major spliceosome drives the release of mature mRNA from the spliceosome. Consistently, we show that RBM41 associates with excised U12-type intron lariats, is present in the U12 mono-snRNP, and is enriched in Cajal bodies, together suggesting that RBM41 functions in the post-splicing steps of the minor spliceosome assembly/disassembly cycle. This contrasts with U11/U12-65K, which uses its N-terminal region to interact with U11 snRNP during intron recognition. Finally, while RBM41 knockout cells are viable, they show alterations in U12-type 3' splice site usage. Together, our results highlight the role of the 3'-terminal stem-loop of U12 snRNA as a dynamic binding platform for the U11/U12-65K and RBM41 proteins, which function at distinct stages of the assembly/disassembly cycle.


Asunto(s)
ARN Helicasas DEAD-box , Factores de Empalme de ARN , ARN Nuclear Pequeño , Proteínas de Unión al ARN , Ribonucleoproteínas Nucleares Pequeñas , Empalmosomas , Empalmosomas/metabolismo , Empalmosomas/genética , Ribonucleoproteínas Nucleares Pequeñas/metabolismo , Ribonucleoproteínas Nucleares Pequeñas/genética , Ribonucleoproteínas Nucleares Pequeñas/química , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/química , Humanos , ARN Nuclear Pequeño/metabolismo , ARN Nuclear Pequeño/genética , ARN Nuclear Pequeño/química , ARN Helicasas DEAD-box/metabolismo , ARN Helicasas DEAD-box/genética , Empalme del ARN , Intrones/genética , Células HeLa , Unión Proteica , Cuerpos Enrollados/metabolismo , Células HEK293
20.
Int J Mol Sci ; 25(6)2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38542215

RESUMEN

The market value of tea is largely dependent on the tea species and cultivar. Therefore, it is important to develop efficient molecular markers covering the entire tea genome that can be used for the identification of tea varieties, marker-assisted breeding, and mapping important quantitative trait loci for beneficial traits. In this study, genome-wide molecular markers based on intron length polymorphism (ILP) were developed for tea trees. A total of 479, 1393, and 1342 tea ILP markers were identified using the PCR method in silico from the 'Shuchazao' scaffold genome, the chromosome-level genome of 'Longjing 43', and the ancient tea DASZ chromosome-level genome, respectively. A total of 230 tea ILP markers were used to amplify six tea tree species. Among these, 213 pairs of primers successfully characterize products in all six species, with 112 primer pairs exhibiting polymorphism. The polymorphism rate of primer pairs increased with the improvement in reference genome assembly quality level. The cross-species transferability analysis of 35 primer pairs of tea ILP markers showed an average amplification rate of 85.17% through 11 species in 6 families, with high transferability in Camellia reticulata and tobacco. We also used 40 pairs of tea ILP primers to evaluate the genetic diversity and population structure of C. tetracocca with 176 plants from Puan County, Guizhou Province, China. These genome-wide markers will be a valuable resource for genetic diversity analysis, marker-assisted breeding, and variety identification in tea, providing important information for the tea industry.


Asunto(s)
Camellia sinensis , Humanos , Intrones/genética , Camellia sinensis/genética , Marcadores Genéticos , Genoma de Planta , Fitomejoramiento ,
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