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1.
Nat Commun ; 15(1): 3839, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38714659

RESUMO

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.


Assuntos
Sistemas CRISPR-Cas , Éxons , Íntrons , Splicing de RNA , RNA Guia de Sistemas CRISPR-Cas , Proteína 2 de Sobrevivência do Neurônio Motor , Humanos , Splicing de RNA/genética , Proteína 2 de Sobrevivência do Neurônio Motor/genética , RNA Guia de Sistemas CRISPR-Cas/genética , Íntrons/genética , Éxons/genética , Células HEK293 , Oligonucleotídeos Antissenso/genética , Atrofia Muscular Espinal/genética , Sequências Reguladoras de Ácido Nucleico/genética , Precursores de RNA/genética , Precursores de RNA/metabolismo
2.
Cell Genom ; : 100563, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38772368

RESUMO

Divergence of precursor messenger RNA (pre-mRNA) alternative splicing (AS) is widespread in mammals, including primates, but the underlying mechanisms and functional impact are poorly understood. Here, we modeled cassette exon inclusion in primate brains as a quantitative trait and identified 1,170 (∼3%) exons with lineage-specific splicing shifts under stabilizing selection. Among them, microtubule-associated protein tau (MAPT) exons 2 and 10 underwent anticorrelated, two-step evolutionary shifts in the catarrhine and hominoid lineages, leading to their present inclusion levels in humans. The developmental-stage-specific divergence of exon 10 splicing, whose dysregulation can cause frontotemporal lobar degeneration (FTLD), is mediated by divergent distal intronic MBNL-binding sites. Competitive binding of these sites by CRISPR-dCas13d/gRNAs effectively reduces exon 10 inclusion, potentially providing a therapeutically compatible approach to modulate tau isoform expression. Our data suggest adaptation of MAPT function and, more generally, a role for AS in the evolutionary expansion of the primate brain.

3.
bioRxiv ; 2023 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-37662340

RESUMO

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 impeded by the challenge of systematically mapping splicing-regulatory elements (SREs) in their native sequence context. Here, we use the catalytically dead 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 identified not only known SREs, but also a novel distal intronic splicing enhancer, 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.

4.
Nature ; 617(7960): 395-402, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37046090

RESUMO

Translation is pervasive outside of canonical coding regions, occurring in long noncoding RNAs, canonical untranslated regions and introns1-4, especially in ageing4-6, neurodegeneration5,7 and cancer8-10. Notably, the majority of tumour-specific antigens are results of noncoding translation11-13. Although the resulting polypeptides are often nonfunctional, translation of noncoding regions is nonetheless necessary for the birth of new coding sequences14,15. The mechanisms underlying the surveillance of translation in diverse noncoding regions and how escaped polypeptides evolve new functions remain unclear10,16-19. Functional polypeptides derived from annotated noncoding sequences often localize to membranes20,21. Here we integrate massively parallel analyses of more than 10,000 human genomic sequences and millions of random sequences with genome-wide CRISPR screens, accompanied by in-depth genetic and biochemical characterizations. Our results show that the intrinsic nucleotide bias in the noncoding genome and in the genetic code frequently results in polypeptides with a hydrophobic C-terminal tail, which is captured by the ribosome-associated BAG6 membrane protein triage complex for either proteasomal degradation or membrane targeting. By contrast, canonical proteins have evolved to deplete C-terminal hydrophobic residues. Our results reveal a fail-safe mechanism for the surveillance of unwanted translation from diverse noncoding regions and suggest a possible biochemical route for the preferential membrane localization of newly evolved proteins.


Assuntos
Código Genético , Biossíntese de Proteínas , Proteínas , RNA Longo não Codificante , Ribossomos , Humanos , Chaperonas Moleculares/metabolismo , Peptídeos/química , Peptídeos/genética , Peptídeos/metabolismo , Proteínas/química , Proteínas/genética , Proteínas/metabolismo , Ribossomos/metabolismo , RNA Longo não Codificante/genética , Biossíntese de Proteínas/genética , Genoma Humano , Código Genético/genética , Interações Hidrofóbicas e Hidrofílicas , Íntrons/genética
5.
PLoS Genet ; 18(9): e1010416, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36129965

RESUMO

Control over gene expression is exerted, in multiple stages of spermatogenesis, at the post-transcriptional level by RNA binding proteins (RBPs). We identify here an essential role in mammalian spermatogenesis and male fertility for 'RNA binding protein 46' (RBM46). A highly evolutionarily conserved gene, Rbm46 is also essential for fertility in both flies and fish. We found Rbm46 expression was restricted to the mouse germline, detectable in males in the cytoplasm of premeiotic spermatogonia and meiotic spermatocytes. To define its requirement for spermatogenesis, we generated Rbm46 knockout (KO, Rbm46-/-) mice; although male Rbm46-/- mice were viable and appeared grossly normal, they were infertile. Testes from adult Rbm46-/- mice were small, with seminiferous tubules containing only Sertoli cells and few undifferentiated spermatogonia. Using genome-wide unbiased high throughput assays RNA-seq and 'enhanced crosslinking immunoprecipitation' coupled with RNA-seq (eCLIP-seq), we discovered RBM46 could bind, via a U-rich conserved consensus sequence, to a cohort of mRNAs encoding proteins required for completion of differentiation and subsequent meiotic initiation. In summary, our studies support an essential role for RBM46 in regulating target mRNAs during spermatogonia differentiation prior to the commitment to meiosis in mice.


Assuntos
Proteínas de Ligação a RNA/metabolismo , Espermatogênese , Espermatogônias , Animais , Diferenciação Celular/genética , Masculino , Mamíferos/genética , Meiose/genética , Camundongos , Camundongos Knockout , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Espermatócitos/metabolismo , Espermatogênese/genética , Espermatogônias/metabolismo , Testículo
6.
PLoS Genet ; 17(7): e1009684, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34314424

RESUMO

Functional mechanisms remain unknown for most genetic loci associated to complex human traits and diseases. In this study, we first mapped trans-eQTLs in a data set of primary monocytes stimulated with LPS, and discovered that a risk variant for autoimmune disease, rs17622517 in an intron of C5ORF56, affects the expression of the transcription factor IRF1 20 kb away. The cis-regulatory effect specific to IRF1 is active under early immune stimulus, with a large number of trans-eQTL effects across the genome under late LPS response. Using CRISPRi silencing, we showed that perturbation of the SNP locus downregulates IRF1 and causes widespread transcriptional effects. Genome editing by CRISPR had suggestive recapitulation of the LPS-specific trans-eQTL signal and lent support for the rs17622517 site being functional. Our results suggest that this common genetic variant affects inter-individual response to immune stimuli via regulation of IRF1. For this autoimmune GWAS locus, our work provides evidence of the functional variant, demonstrates a condition-specific enhancer effect, identifies IRF1 as the likely causal gene in cis, and indicates that overactivation of the downstream immune-related pathway may be the cellular mechanism increasing disease risk. This work not only provides rare experimental validation of a master-regulatory trans-eQTL, but also demonstrates the power of eQTL mapping to build mechanistic hypotheses amenable for experimental follow-up using the CRISPR toolkit.


Assuntos
Doenças Autoimunes/genética , Imunidade/genética , Fator Regulador 1 de Interferon/genética , Adulto , Doenças Autoimunes/metabolismo , Mapeamento Cromossômico/métodos , DNA Antissenso/genética , Feminino , Expressão Gênica/genética , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica/genética , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/métodos , Células HEK293 , Humanos , Fator Regulador 1 de Interferon/metabolismo , Masculino , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética , Sequências Reguladoras de Ácido Nucleico/genética , Fatores de Risco
7.
Nat Neurosci ; 24(7): 930-940, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33795885

RESUMO

The neurodegenerative disease spinal muscular atrophy (SMA) is caused by deficiency in the survival motor neuron (SMN) protein. Currently approved SMA treatments aim to restore SMN, but the potential for SMN expression beyond physiological levels is a unique feature of adeno-associated virus serotype 9 (AAV9)-SMN gene therapy. Here, we show that long-term AAV9-mediated SMN overexpression in mouse models induces dose-dependent, late-onset motor dysfunction associated with loss of proprioceptive synapses and neurodegeneration. Mechanistically, aggregation of overexpressed SMN in the cytoplasm of motor circuit neurons sequesters components of small nuclear ribonucleoproteins, leading to splicing dysregulation and widespread transcriptome abnormalities with prominent signatures of neuroinflammation and the innate immune response. Thus, long-term SMN overexpression interferes with RNA regulation and triggers SMA-like pathogenic events through toxic gain-of-function mechanisms. These unanticipated, SMN-dependent and neuron-specific liabilities warrant caution on the long-term safety of treating individuals with SMA with AAV9-SMN and the risks of uncontrolled protein expression by gene therapy.


Assuntos
Neurônios Motores/metabolismo , Neurônios Motores/patologia , Degeneração Neural , Proteína 1 de Sobrevivência do Neurônio Motor/toxicidade , Animais , Dependovirus , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Técnicas de Transferência de Genes , Terapia Genética/efeitos adversos , Vetores Genéticos , Injeções Intraventriculares , Camundongos , Transtornos Motores/genética , Transtornos Motores/metabolismo , Transtornos Motores/patologia , Degeneração Neural/genética , Degeneração Neural/metabolismo , Degeneração Neural/patologia , Proteína 1 de Sobrevivência do Neurônio Motor/genética
8.
Nat Commun ; 11(1): 1927, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317636

RESUMO

Because old age is associated with defects in circadian rhythm, loss of circadian regulation is thought to be pathogenic and contribute to mortality. We show instead that loss of specific circadian clock components Period (Per) and Timeless (Tim) in male Drosophila significantly extends lifespan. This lifespan extension is not mediated by canonical diet-restriction longevity pathways but is due to altered cellular respiration via increased mitochondrial uncoupling. Lifespan extension of per mutants depends on mitochondrial uncoupling in the intestine. Moreover, upregulated uncoupling protein UCP4C in intestinal stem cells and enteroblasts is sufficient to extend lifespan and preserve proliferative homeostasis in the gut with age. Consistent with inducing a metabolic state that prevents overproliferation, mitochondrial uncoupling drugs also extend lifespan and inhibit intestinal stem cell overproliferation due to aging or even tumorigenesis. These results demonstrate that circadian-regulated intestinal mitochondrial uncoupling controls longevity in Drosophila and suggest a new potential anti-aging therapeutic target.


Assuntos
Ritmo Circadiano , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias/metabolismo , Proteínas Circadianas Period/metabolismo , Animais , Sistemas CRISPR-Cas , Carcinogênese , Proliferação de Células , Relógios Circadianos , Homeostase , Intestinos/patologia , Longevidade , Masculino , Potencial da Membrana Mitocondrial , Mutação , Estresse Oxidativo/fisiologia , Consumo de Oxigênio , Proteína Desacopladora 1/metabolismo
9.
J Biol Rhythms ; 34(4): 391-400, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31140349

RESUMO

Short-wavelength light guides many behaviors that are crucial for an insect's survival. In Drosophila melanogaster, short-wavelength light induces both attraction and avoidance behaviors. How light cues evoke two opposite valences of behavioral responses remains unclear. Here, we comprehensively examine the effects of (1) light intensity, (2) timing of light (duration of exposure, circadian time of day), and (3) phototransduction mechanisms processing light information that determine avoidance versus attraction behavior assayed at high spatiotemporal resolution in Drosophila. External opsin-based photoreceptors signal for attraction behavior in response to low-intensity ultraviolet (UV) light. In contrast, the cell-autonomous neuronal photoreceptors, CRYPTOCHROME (CRY) and RHODOPSIN 7 (RH7), signal avoidance responses to high-intensity UV light. In addition to binary attraction versus avoidance behavioral responses to UV light, flies show distinct clock-dependent spatial preference within a light environment coded by different light input channels.


Assuntos
Aprendizagem da Esquiva/efeitos da radiação , Comportamento Animal/efeitos da radiação , Drosophila melanogaster/fisiologia , Transdução de Sinal Luminoso , Raios Ultravioleta , Animais , Drosophila melanogaster/efeitos da radiação
10.
PLoS One ; 13(8): e0201927, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30106957

RESUMO

Many insects show strong behavioral responses to short wavelength light. Drosophila melanogaster exhibit Cryptochrome- and Hyperkinetic-dependent blue and ultraviolet (UV) light avoidance responses that vary by time-of-day, suggesting that these key sensory behaviors are circadian regulated. Here we show mutant flies lacking core clock genes exhibit defects in both time-of-day responses and valence of UV light avoidance/attraction behavior. Non-genetic environmental disruption of the circadian clock by constant UV light exposure leads to complete loss of rhythmic UV light avoidance/attraction behavior. Flies with ablated or electrically silenced circadian lateral ventral neurons have attenuated avoidance response to UV light. We conclude that circadian clock proteins and the circadian lateral ventral neurons regulate both the timing and the valence of UV light avoidance/attraction. These results provide mechanistic support for Pittendrigh's "escape from light" hypothesis regarding the co-evolution of phototransduction and circadian systems.


Assuntos
Comportamento Animal , Ritmo Circadiano , Drosophila/fisiologia , Luz , Animais , Aprendizagem da Esquiva , Relógios Circadianos , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Transdução de Sinal Luminoso , Mutação , Células Fotorreceptoras de Invertebrados/efeitos dos fármacos , Células Fotorreceptoras de Invertebrados/fisiologia , Raios Ultravioleta
11.
Proc Natl Acad Sci U S A ; 114(4): 776-781, 2017 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-28062690

RESUMO

Drosophila melanogaster CRYPTOCHROME (CRY) mediates behavioral and electrophysiological responses to blue light coded by circadian and arousal neurons. However, spectroscopic and biochemical assays of heterologously expressed CRY suggest that CRY may mediate functional responses to UV-A (ultraviolet A) light as well. To determine the relative contributions of distinct phototransduction systems, we tested mutants lacking CRY and mutants with disrupted opsin-based phototransduction for behavioral and electrophysiological responses to UV light. CRY and opsin-based external photoreceptor systems cooperate for UV light-evoked acute responses. CRY mediates behavioral avoidance responses related to executive choice, consistent with its expression in central brain neurons.


Assuntos
Comportamento de Escolha/fisiologia , Criptocromos/metabolismo , Animais , Relógios Biológicos/fisiologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/fisiologia , Ritmo Circadiano/fisiologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Drosophila melanogaster/fisiologia , Proteínas do Olho/metabolismo , Luz , Transdução de Sinal Luminoso/fisiologia , Neurônios/metabolismo , Células Fotorreceptoras de Invertebrados/metabolismo , Raios Ultravioleta
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