RESUMO
Posttranscriptional control of mRNA regulates various biological processes, including inflammatory and immune responses. RNA-binding proteins (RBPs) bind cis-regulatory elements in the 3' untranslated regions (UTRs) of mRNA and regulate mRNA turnover and translation. In particular, eight RBPs (TTP, AUF1, KSRP, TIA-1/TIAR, Roquin, Regnase, HuR, and Arid5a) have been extensively studied and are key posttranscriptional regulators of inflammation and immune responses. These RBPs sometimes collaboratively or competitively bind the same target mRNA to enhance or dampen regulatory activities. These RBPs can also bind their own 3' UTRs to negatively or positively regulate their expression. Both upstream signaling pathways and microRNA regulation shape the interactions between RBPs and target RNA. Dysregulation of RBPs results in chronic inflammation and autoimmunity. Here, we summarize the functional roles of these eight RBPs in immunity and their associated diseases.
Assuntos
MicroRNAs , Estabilidade de RNA , Animais , Regulação da Expressão Gênica , Humanos , MicroRNAs/genética , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismoRESUMO
Cancer cells are featured with uncontrollable activation of cell cycle, and microRNA deficiency drives tumorigenesis. The RNA-dependent RNA polymerase (RDR) is essential for small-RNA-mediated immune response in plants but is absent in vertebrates. Here, we show that ectopic expression of plant RDR1 can generally inhibit cancer cell proliferation. In many human primary tumors, abnormal microRNA isoforms with 1-nt-shorter 3' ends are widely accumulated. RDR1 with nucleotidyltransferase activity can recognize and modify the problematic AGO2-free microRNA duplexes with mononucleotides to restore their 2 nt overhang structure, which eventually rescues AGO2-loading efficiency and elevates global miRNA expression to inhibit cancer cell-cycle specifically. The broad antitumor effects of RDR1, which can be delivered by an adeno-associated virus, are visualized in multiple xenograft tumor models in vivo. Altogether, we reveal the widespread accumulation of aberrant microRNA isoforms in tumors and develop a plant RDR1-mediated antitumor stratagem by editing and repairing defective microRNAs.
Assuntos
MicroRNAs , Animais , Humanos , Imunidade , MicroRNAs/química , Proteínas de Plantas , Plantas/genética , RNA Polimerase Dependente de RNARESUMO
Covalently closed, single-stranded circular RNAs can be produced from viral RNA genomes as well as from the processing of cellular housekeeping noncoding RNAs and precursor messenger RNAs. Recent transcriptomic studies have surprisingly uncovered that many protein-coding genes can be subjected to backsplicing, leading to widespread expression of a specific type of circular RNAs (circRNAs) in eukaryotic cells. Here, we discuss experimental strategies used to discover and characterize diverse circRNAs at both the genome and individual gene scales. We further highlight the current understanding of how circRNAs are generated and how the mature transcripts function. Some circRNAs act as noncoding RNAs to impact gene regulation by serving as decoys or competitors for microRNAs and proteins. Others form extensive networks of ribonucleoprotein complexes or encode functional peptides that are translated in response to certain cellular stresses. Overall, circRNAs have emerged as an important class of RNAmolecules in gene expression regulation that impact many physiological processes, including early development, immune responses, neurogenesis, and tumorigenesis.
Assuntos
MicroRNAs , RNA Circular , Regulação da Expressão Gênica/genética , MicroRNAs/genética , MicroRNAs/metabolismo , RNA/genética , RNA/metabolismo , RNA Circular/genética , RNA não Traduzido , RNA Viral , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismoRESUMO
Metabolic conditions affect the developmental tempo of animals. Developmental gene regulatory networks (GRNs) must therefore synchronize their dynamics with a variable timescale. We find that layered repression of genes couples GRN output with variable metabolism. When repressors of transcription or mRNA and protein stability are lost, fewer errors in Drosophila development occur when metabolism is lowered. We demonstrate the universality of this phenomenon by eliminating the entire microRNA family of repressors and find that development to maturity can be largely rescued when metabolism is reduced. Using a mathematical model that replicates GRN dynamics, we find that lowering metabolism suppresses the emergence of developmental errors by curtailing the influence of auxiliary repressors on GRN output. We experimentally show that gene expression dynamics are less affected by loss of repressors when metabolism is reduced. Thus, layered repression provides robustness through error suppression and may provide an evolutionary route to a shorter reproductive cycle.
Assuntos
Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Neurônios/metabolismo , Animais , Animais Geneticamente Modificados , Encéfalo/citologia , Drosophila melanogaster/crescimento & desenvolvimento , Olho/citologia , Feminino , Insulina/metabolismo , Mutação com Perda de Função , MicroRNAs/metabolismo , Modelos Teóricos , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transcrição GênicaRESUMO
miRISC is a multi-protein assembly that uses microRNAs (miRNAs) to identify mRNAs targeted for repression. Dozens of miRISC-associated proteins have been identified, and interactions between many factors have been examined in detail. However, the physical nature of the complex remains unknown. Here, we show that two core protein components of human miRISC, Argonaute2 (Ago2) and TNRC6B, condense into phase-separated droplets in vitro and in live cells. Phase separation is promoted by multivalent interactions between the glycine/tryptophan (GW)-rich domain of TNRC6B and three evenly spaced tryptophan-binding pockets in the Ago2 PIWI domain. miRISC droplets formed in vitro recruit deadenylation factors and sequester target RNAs from the bulk solution. The condensation of miRISC is accompanied by accelerated deadenylation of target RNAs bound to Ago2. The combined results may explain how miRISC silences mRNAs of varying size and structure and provide experimental evidence that protein-mediated phase separation can facilitate an RNA processing reaction.
Assuntos
Proteínas Argonautas/metabolismo , MicroRNAs/metabolismo , Proteínas de Ligação a RNA/metabolismo , Motivos de Aminoácidos , Proteínas Argonautas/genética , Sítios de Ligação , Recuperação de Fluorescência Após Fotodegradação , Células HEK293 , Humanos , Transição de Fase , Ligação Proteica , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Complexo de Inativação Induzido por RNA/metabolismoRESUMO
Cell fate transitions involve rapid gene expression changes and global chromatin remodeling, yet the underlying regulatory pathways remain incompletely understood. Here, we identified the RNA-processing factor Nudt21 as a novel regulator of cell fate change using transcription-factor-induced reprogramming as a screening assay. Suppression of Nudt21 enhanced the generation of induced pluripotent stem cells, facilitated transdifferentiation into trophoblast stem cells, and impaired differentiation of myeloid precursors and embryonic stem cells, suggesting a broader role for Nudt21 in cell fate change. We show that Nudt21 directs differential polyadenylation of over 1,500 transcripts in cells acquiring pluripotency, although only a fraction changed protein levels. Remarkably, these proteins were strongly enriched for chromatin regulators, and their suppression neutralized the effect of Nudt21 during reprogramming. Collectively, our data uncover Nudt21 as a novel post-transcriptional regulator of cell fate and establish a direct, previously unappreciated link between alternative polyadenylation and chromatin signaling.
Assuntos
Reprogramação Celular , Montagem e Desmontagem da Cromatina , Fator de Especificidade de Clivagem e Poliadenilação/metabolismo , Poliadenilação , Transdução de Sinais , Animais , Células Cultivadas , Cromatina/genética , Cromatina/metabolismo , Fator de Especificidade de Clivagem e Poliadenilação/genética , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Células HEK293 , Humanos , CamundongosRESUMO
A large and significant portion of eukaryotic transcriptomes consists of noncoding RNAs (ncRNAs) that have minimal or no protein-coding capacity but are functional. Diverse ncRNAs, including both small RNAs and long ncRNAs (lncRNAs), play essential regulatory roles in almost all biological processes by modulating gene expression at the transcriptional and posttranscriptional levels. In this review, we summarize the current knowledge of plant small RNAs and lncRNAs, with a focus on their biogenesis, modes of action, local and systemic movement, and functions at the nexus of plant development and environmental responses. The complex connections among small RNAs, lncRNAs, and small peptides in plants are also discussed, along with the challenges of identifying and investigating new classes of ncRNAs.
Assuntos
Desenvolvimento Vegetal/genética , Plantas/genética , RNA Longo não Codificante/metabolismo , RNA de Plantas/metabolismo , Estresse Fisiológico/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , MicroRNAs/genética , MicroRNAs/metabolismo , RNA Circular/genética , RNA Circular/metabolismo , RNA Longo não Codificante/genética , RNA de Plantas/genética , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismoRESUMO
Super-enhancers are an emerging subclass of regulatory regions controlling cell identity and disease genes. However, their biological function and impact on miRNA networks are unclear. Here, we report that super-enhancers drive the biogenesis of master miRNAs crucial for cell identity by enhancing both transcription and Drosha/DGCR8-mediated primary miRNA (pri-miRNA) processing. Super-enhancers, together with broad H3K4me3 domains, shape a tissue-specific and evolutionarily conserved atlas of miRNA expression and function. CRISPR/Cas9 genomics revealed that super-enhancer constituents act cooperatively and facilitate Drosha/DGCR8 recruitment and pri-miRNA processing to boost cell-specific miRNA production. The BET-bromodomain inhibitor JQ1 preferentially inhibits super-enhancer-directed cotranscriptional pri-miRNA processing. Furthermore, super-enhancers are characterized by pervasive interaction with DGCR8/Drosha and DGCR8/Drosha-regulated mRNA stability control, suggesting unique RNA regulation at super-enhancers. Finally, super-enhancers mark multiple miRNAs associated with cancer hallmarks. This study presents principles underlying miRNA biology in health and disease and an unrecognized higher-order property of super-enhancers in RNA processing beyond transcription.
Assuntos
Elementos Facilitadores Genéticos , MicroRNAs/metabolismo , Animais , Azepinas/farmacologia , Regulação da Expressão Gênica , Código das Histonas , Humanos , Camundongos , Neoplasias/genética , Especificidade de Órgãos , Processamento Pós-Transcricional do RNA/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Transcrição Gênica , Triazóis/farmacologiaRESUMO
We report a comprehensive analysis of 412 muscle-invasive bladder cancers characterized by multiple TCGA analytical platforms. Fifty-eight genes were significantly mutated, and the overall mutational load was associated with APOBEC-signature mutagenesis. Clustering by mutation signature identified a high-mutation subset with 75% 5-year survival. mRNA expression clustering refined prior clustering analyses and identified a poor-survival "neuronal" subtype in which the majority of tumors lacked small cell or neuroendocrine histology. Clustering by mRNA, long non-coding RNA (lncRNA), and miRNA expression converged to identify subsets with differential epithelial-mesenchymal transition status, carcinoma in situ scores, histologic features, and survival. Our analyses identified 5 expression subtypes that may stratify response to different treatments.
Assuntos
Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/patologia , Idoso , Análise por Conglomerados , Metilação de DNA , Humanos , MicroRNAs/genética , Pessoa de Meia-Idade , Músculo Liso/patologia , RNA Longo não Codificante/genética , Análise de Sobrevida , Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/epidemiologia , Neoplasias da Bexiga Urinária/terapiaRESUMO
The RNA-induced silencing complex (RISC), which powers RNA interference (RNAi), consists of a guide RNA and an Argonaute protein that slices target RNAs complementary to the guide. We find that, for different guide-RNA sequences, slicing rates of perfectly complementary bound targets can be surprisingly different (>250-fold range), and that faster slicing confers better knockdown in cells. Nucleotide sequence identities at guide-RNA positions 7, 10, and 17 underlie much of this variation in slicing rates. Analysis of one of these determinants implicates a structural distortion at guide nucleotides 6-7 in promoting slicing. Moreover, slicing directed by different guide sequences has an unanticipated, 600-fold range in 3'-mismatch tolerance, attributable to guides with weak (AU-rich) central pairing requiring extensive 3' complementarity (pairing beyond position 16) to more fully populate the slicing-competent conformation. Together, our analyses identify sequence determinants of RISC activity and provide biochemical and conformational rationale for their action.
Assuntos
Proteínas Argonautas , Conformação de Ácido Nucleico , RNA Guia de Sistemas CRISPR-Cas , Complexo de Inativação Induzido por RNA , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Proteínas Argonautas/química , Humanos , Complexo de Inativação Induzido por RNA/metabolismo , Complexo de Inativação Induzido por RNA/genética , Complexo de Inativação Induzido por RNA/química , Cinética , RNA Guia de Sistemas CRISPR-Cas/genética , RNA Guia de Sistemas CRISPR-Cas/metabolismo , Interferência de RNA , Sequência de Bases , Células HEK293RESUMO
We show here that mir-279/996 are absolutely essential for development and function of Johnston's organ (JO), the primary proprioceptive and auditory organ in Drosophila Their deletion results in highly aberrant cell fate determination, including loss of scolopale cells and ectopic neurons, and mutants are electrophysiologically deaf. In vivo activity sensors and mosaic analyses indicate that these seed-related miRNAs function autonomously to suppress neural fate in nonneuronal cells. Finally, genetic interactions pinpoint two neural targets (elav and insensible) that underlie miRNA mutant JO phenotypes. This work uncovers how critical post-transcriptional regulation of specific miRNA targets governs cell specification and function of the auditory system.
Assuntos
Proteínas de Drosophila , MicroRNAs , Animais , MicroRNAs/genética , Audição/genética , Drosophila/genética , Proteínas de Drosophila/genética , Órgãos dos Sentidos/fisiologiaRESUMO
MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play critical roles in development and disease. Target-directed miRNA degradation (TDMD), a pathway in which miRNAs that bind to specialized targets with extensive complementarity are rapidly decayed, has emerged as a potent mechanism of controlling miRNA levels. Nevertheless, the biological role and scope of miRNA regulation by TDMD in mammals remains poorly understood. To address these questions, we generated mice with constitutive or conditional deletion of Zswim8, which encodes an essential TDMD factor. Loss of Zswim8 resulted in developmental defects in the heart and lungs, growth restriction, and perinatal lethality. Small RNA sequencing of embryonic tissues revealed widespread miRNA regulation by TDMD and greatly expanded the known catalog of miRNAs regulated by this pathway. These experiments also uncovered novel features of TDMD-regulated miRNAs, including their enrichment in cotranscribed clusters and examples in which TDMD underlies "arm switching," a phenomenon wherein the dominant strand of a miRNA precursor changes in different tissues or conditions. Importantly, deletion of two miRNAs, miR-322 and miR-503, rescued growth of Zswim8-null embryos, directly implicating the TDMD pathway as a regulator of mammalian body size. These data illuminate the broad landscape and developmental role of TDMD in mammals.
Assuntos
MicroRNAs , Camundongos , Animais , MicroRNAs/genética , MicroRNAs/metabolismo , Mamíferos/genética , Sequência de BasesRESUMO
DROSHA serves as a gatekeeper of the microRNA (miRNA) pathway by processing primary transcripts (pri-miRNAs). While the functions of structured domains of DROSHA have been well documented, the contribution of N-terminal proline-rich disordered domain (PRD) remains elusive. Here we show that the PRD promotes the processing of miRNA hairpins located within introns. We identified a DROSHA isoform (p140) lacking the PRD, which is produced by proteolytic cleavage. Small RNA sequencing revealed that p140 is significantly impaired in the maturation of intronic miRNAs. Consistently, our minigene constructs demonstrated that PRD enhances the processing of intronic hairpins, but not those in exons. Splice site mutations did not affect the PRD's enhancing effect on intronic constructs, suggesting that the PRD acts independently of splicing reaction by interacting with sequences residing within introns. The N-terminal regions from zebrafish and Xenopus DROSHA can replace the human counterpart, indicating functional conservation despite poor sequence alignment. Moreover, we found that rapidly evolving intronic miRNAs are generally more dependent on PRD than conserved ones, suggesting a role of PRD in miRNA evolution. Our study reveals a new layer of miRNA regulation mediated by a low-complexity disordered domain that senses the genomic contexts of miRNA loci.
Assuntos
MicroRNAs , Ribonuclease III , Animais , Humanos , Íntrons/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Prolina/genética , Prolina/metabolismo , Ribonuclease III/genética , Ribonuclease III/metabolismo , Processamento Pós-Transcricional do RNA , Peixe-ZebraRESUMO
In animals and plants, Dicer enzymes collaborate with double-stranded RNA-binding domain (dsRBD) proteins to convert precursor-microRNAs (pre-miRNAs) into miRNA duplexes. We report six cryo-EM structures of Drosophila Dicer-1 that show how Dicer-1 and its partner LoqsPB cooperate (1) before binding pre-miRNA, (2) after binding and in a catalytically competent state, (3) after nicking one arm of the pre-miRNA, and (4) following complete dicing and initial product release. Our reconstructions suggest that pre-miRNA binds a rare, open conformation of the Dicer1â LoqsPB heterodimer. The Dicer-1 dsRBD and three LoqsPB dsRBDs form a tight belt around the pre-miRNA, distorting the RNA helix to place the scissile phosphodiester bonds in the RNase III active sites. Pre-miRNA cleavage shifts the dsRBDs and partially closes Dicer-1, which may promote product release. Our data suggest a model for how the Dicer1â LoqsPB complex affects a complete cycle of pre-miRNA recognition, stepwise endonuclease cleavage, and product release.
Assuntos
Proteínas de Drosophila , MicroRNAs , Animais , Ribonuclease III/genética , Ribonuclease III/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Proteínas de Ligação a RNA/metabolismo , Drosophila/genética , MicroRNAs/genética , MicroRNAs/metabolismoRESUMO
One of the mechanisms by which cancer cells acquire hyperinvasive and migratory properties with progressive loss of epithelial markers is the epithelial-to-mesenchymal transition (EMT). We have previously reported that in different cancer types, including nonsmall cell lung cancer (NSCLC), the microRNA-183/96/182 cluster (m96cl) is highly repressed in cells that have undergone EMT. In the present study, we used a novel conditional m96cl mouse to establish that loss of m96cl accelerated the growth of Kras mutant autochthonous lung adenocarcinomas. In contrast, ectopic expression of the m96cl in NSCLC cells results in a robust suppression of migration and invasion in vitro, and tumor growth and metastasis in vivo. Detailed immune profiling of the tumors revealed a significant enrichment of activated CD8+ cytotoxic T lymphocytes (CD8+ CTLs) in m96cl-expressing tumors, and m96cl-mediated suppression of tumor growth and metastasis was CD8+ CTL-dependent. Using coculture assays with naïve immune cells, we show that m96cl expression drives paracrine stimulation of CD8+ CTL proliferation and function. Using tumor microenvironment-associated gene expression profiling, we identified that m96cl elevates the interleukin-2 (IL2) signaling pathway and results in increased IL2-mediated paracrine stimulation of CD8+ CTLs. Furthermore, we identified that the m96cl modulates the expression of IL2 in cancer cells by regulating the expression of transcriptional repressors Foxf2 and Zeb1, and thereby alters the levels of secreted IL2 in the tumor microenvironment. Last, we show that in vivo depletion of IL2 abrogates m96cl-mediated activation of CD8+ CTLs and results in loss of metastatic suppression. Therefore, we have identified a novel mechanistic role of the m96cl in the suppression of lung cancer growth and metastasis by inducing an IL2-mediated systemic CD8+ CTL immune response.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , MicroRNAs , Animais , Linfócitos T CD8-Positivos , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Linhagem Celular Tumoral , Interleucina-2/genética , Interleucina-2/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Camundongos , MicroRNAs/genética , MicroRNAs/metabolismo , Linfócitos T Citotóxicos , Microambiente TumoralRESUMO
Maturation of canonical microRNA (miRNA) is initiated by DROSHA that cleaves the primary transcript (pri-miRNA). More than 1,800 miRNA loci are annotated in humans, but it remains largely unknown whether and at which sites pri-miRNAs are cleaved by DROSHA. Here, we performed in vitro processing on a full set of human pri-miRNAs (miRBase version 21) followed by sequencing. This comprehensive profiling enabled us to classify miRNAs on the basis of DROSHA dependence and map their cleavage sites with respective processing efficiency measures. Only 758 pri-miRNAs are confidently processed by DROSHA, while the majority may be non-canonical or false entries. Analyses of the DROSHA-dependent pri-miRNAs show key cis-elements for processing. We observe widespread alternative processing and unproductive cleavage events such as "nick" or "inverse" processing. SRSF3 is a broad-acting auxiliary factor modulating alternative processing and suppressing unproductive processing. The profiling data and methods developed in this study will allow systematic analyses of miRNA regulation.
Assuntos
MicroRNAs/genética , Processamento Pós-Transcricional do RNA/genética , Ribonuclease III/genética , Fatores de Processamento de Serina-Arginina/genética , Sítios de Ligação/genética , Genoma Humano/genética , Células HEK293 , Humanos , Interferência de RNARESUMO
In animals, PIWI-interacting RNAs (piRNAs) silence transposons, fight viral infections, and regulate gene expression. piRNA biogenesis concludes with 3' terminal trimming and 2'-O-methylation. Both trimming and methylation influence piRNA stability. Our biochemical data show that multiple mechanisms destabilize unmethylated mouse piRNAs, depending on whether the piRNA 5' or 3' sequence is complementary to a trigger RNA. Unlike target-directed degradation of microRNAs, complementarity-dependent destabilization of piRNAs in mice and flies is blocked by 3' terminal 2'-O-methylation and does not require base pairing to both the piRNA seed and the 3' sequence. In flies, 2'-O-methylation also protects small interfering RNAs (siRNAs) from complementarity-dependent destruction. By contrast, pre-piRNA trimming protects mouse piRNAs from a degradation pathway unaffected by trigger complementarity. In testis lysate and in vivo, internal or 3' terminal uridine- or guanine-rich tracts accelerate pre-piRNA decay. Loss of both trimming and 2'-O-methylation causes the mouse piRNA pathway to collapse, demonstrating that these modifications collaborate to stabilize piRNAs.
Assuntos
Proteínas Argonautas/metabolismo , RNA Interferente Pequeno/metabolismo , Animais , Separação Celular , Drosophila melanogaster , Feminino , Citometria de Fluxo , Expressão Gênica , Inativação Gênica , Técnicas Genéticas , Masculino , Metilação , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Processamento de Proteína Pós-Traducional , RNA de Cadeia Dupla , Espermatócitos/metabolismo , Espermatogônias/metabolismo , Testículo/metabolismoRESUMO
Type I interferons (IFNs) are critical cytokines in the host defense against invading pathogens. Sustained production of IFNs, however, is detrimental to the host, as it provokes autoimmune diseases. Thus, the expression of IFNs is tightly controlled. We report that the mRNA 5' cap-binding protein 4EHP plays a key role in regulating type I IFN concomitant with controlling virus replication, both in vitro and in vivo. Mechanistically, 4EHP suppresses IFN-ß production by effecting the miR-34a-induced translational silencing of Ifnb1 mRNA. miR-34a is upregulated by both RNA virus infection and IFN-ß induction, prompting a negative feedback regulatory mechanism that represses IFN-ß expression via 4EHP. These findings demonstrate the direct involvement of 4EHP in virus-induced host response, underscoring a critical translational silencing mechanism mediated by 4EHP and miR-34a to impede sustained IFN production. This study highlights an intrinsic regulatory function for miRNA and the translation machinery in maintaining host homeostasis.
Assuntos
Fator de Iniciação 4E em Eucariotos/imunologia , Imunidade Inata , MicroRNAs/imunologia , Biossíntese de Proteínas/imunologia , Infecções por Vírus de RNA/imunologia , Vírus de RNA/imunologia , Animais , Fator de Iniciação 4E em Eucariotos/genética , Células HEK293 , Humanos , Interferon beta/genética , Interferon beta/imunologia , Camundongos , Camundongos Transgênicos , MicroRNAs/genética , Infecções por Vírus de RNA/genética , Vírus de RNA/genéticaRESUMO
Binding of microRNAs (miRNAs) to mRNAs normally results in post-transcriptional repression of gene expression. However, extensive base-pairing between miRNAs and target RNAs can trigger miRNA degradation, a phenomenon called target RNA-directed miRNA degradation (TDMD). Here, we systematically analyzed Argonaute-CLASH (cross-linking, ligation, and sequencing of miRNA-target RNA hybrids) data and identified numerous candidate TDMD triggers, focusing on their ability to induce nontemplated nucleotide addition at the miRNA 3' end. When exogenously expressed in various cell lines, eight triggers induce degradation of corresponding miRNAs. Both the TDMD base-pairing and surrounding sequences are essential for TDMD. CRISPR knockout of endogenous trigger or ZSWIM8, a ubiquitin ligase essential for TDMD, reduced miRNA degradation. Furthermore, degradation of miR-221 and miR-222 by a trigger in BCL2L11, which encodes a proapoptotic protein, enhances apoptosis. Therefore, we uncovered widespread TDMD triggers in target RNAs and demonstrated an example that could functionally cooperate with the encoded protein.
Assuntos
MicroRNAs , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Pareamento de Bases , MicroRNAs/genética , MicroRNAs/metabolismo , Estabilidade de RNA/genética , RNA Mensageiro/genéticaRESUMO
Current approaches to the treatment of schizophrenia have mainly focused on the protein-coding part of the genome; in this context, the roles of microRNAs have received less attention. In the present study, we analyze the microRNAome in the blood and postmortem brains of schizophrenia patients, showing that the expression of miR-99b-5p is downregulated in both the prefrontal cortex and blood of patients. Lowering the amount of miR-99b-5p in mice leads to both schizophrenia-like phenotypes and inflammatory processes that are linked to synaptic pruning in microglia. The microglial miR-99b-5p-supressed inflammatory response requires Z-DNA binding protein 1 (Zbp1), which we identify as a novel miR-99b-5p target. Antisense oligonucleotides against Zbp1 ameliorate the pathological effects of miR-99b-5p inhibition. Our findings indicate that a novel miR-99b-5p-Zbp1 pathway in microglia might contribute to the pathogenesis of schizophrenia.