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1.
Cell ; 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39173632

RESUMEN

Horizontal gene transfer is a key driver of bacterial evolution, but it also presents severe risks to bacteria by introducing invasive mobile genetic elements. To counter these threats, bacteria have developed various defense systems, including prokaryotic Argonautes (pAgos) and the DNA defense module DdmDE system. Through biochemical analysis, structural determination, and in vivo plasmid clearance assays, we elucidate the assembly and activation mechanisms of DdmDE, which eliminates small, multicopy plasmids. We demonstrate that DdmE, a pAgo-like protein, acts as a catalytically inactive, DNA-guided, DNA-targeting defense module. In the presence of guide DNA, DdmE targets plasmids and recruits a dimeric DdmD, which contains nuclease and helicase domains. Upon binding to DNA substrates, DdmD transitions from an autoinhibited dimer to an active monomer, which then translocates along and cleaves the plasmids. Together, our findings reveal the intricate mechanisms underlying DdmDE-mediated plasmid clearance, offering fundamental insights into bacterial defense systems against plasmid invasions.

2.
Genes (Basel) ; 15(8)2024 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-39202383

RESUMEN

MicroRNAs (miRNAs) are a class of small regulatory RNA that are generated via core protein machinery. The miRNAs direct gene-silencing mechanisms to mediate an essential role in gene expression regulation. In mollusks, miRNAs have been demonstrated to be required to regulate gene expression in various biological processes, including normal development, immune responses, reproduction, and stress adaptation. In this study, we aimed to establishment the requirement of the miRNA pathway as part of the molecular response of exposure of Biomphalaria glabrata (snail host) to Schistosoma mansoni (trematode parasite). Initially, the core pieces of miRNA pathway protein machinery, i.e., Drosha, DGCR8, Exportin-5, Ran, and Dicer, together with the central RNA-induced silencing complex (RISC) effector protein Argonaute2 (Ago2) were elucidated from the B. glabrata genome. Following exposure of B. glabrata to S. mansoni miracidia, we identified significant expression up-regulation of all identified pieces of miRNA pathway protein machinery, except for Exportin-5, at 16 h post exposure. For Ago2, we went on to show that the Bgl-Ago2 protein was localized to regions surrounding the sporocysts in the digestive gland of infected snails 20 days post parasite exposure. In addition to documenting elevated miRNA pathway protein machinery expression at the early post-exposure time point, a total of 13 known B. glabrata miRNAs were significantly differentially expressed. Of these thirteen B. glabrata miRNAs responsive to S. mansoni miracidia exposure, five were significantly reduced in their abundance, and correspondingly, these five miRNAs were determined to putatively target six genes with significantly elevated expression and that have been previously associated with immune responses in other animal species, including humans. In conclusion, this study demonstrates the central importance of a functional miRNA pathway in snails, which potentially forms a critical component of the immune response of snails to parasite exposure. Further, the data reported in this study provide additional evidence of the complexity of the molecular response of B. glabrata to S. mansoni infection: a molecular response that could be targeted in the future to overcome parasite infection and, in turn, human schistosomiasis.


Asunto(s)
Proteínas Argonautas , Biomphalaria , MicroARNs , Schistosoma mansoni , Animales , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Biomphalaria/parasitología , Biomphalaria/genética , Biomphalaria/metabolismo , Biomphalaria/inmunología , MicroARNs/genética , MicroARNs/metabolismo , Schistosoma mansoni/genética , Oocistos/metabolismo , Interacciones Huésped-Parásitos/genética
3.
Virus Res ; 348: 199436, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-38996815

RESUMEN

RNA silencing is a prominent antiviral defense mechanism in plants. When infected with a virus, RNA silencing-deficient plants tend to show exacerbated symptoms along with increased virus accumulation. However, how symptoms are exacerbated is little understood. Here, we investigated the role of the copper chaperon for superoxide dismutase (CCS) 1, in systemic necrosis observed in Argonaute (AGO)2-silenced tomato plants infected with potato virus X (PVX). While infection with the UK3 strain of PVX induced mosaic symptoms in tomato plants, systemic necrosis occurred when AGO2 was silenced. The CCS1 mRNA level was reduced and micro RNA398 (miR398), which potentially target CCS1, was increased in AGO2-knockdown tomato plants infected with PVX-UK3. Ectopic expression of CCS1 using recombinant PVX attenuated necrosis, suggesting that CCS1 alleviates systemic necrosis by activating superoxide dismutases to scavenge reactive oxygen species. Previous reports have indicated a decrease in the levels of CCS1 and superoxide dismutases along with an increased level of miR398 in plants infected with other viruses and viroids, and thus might represent shared regulatory mechanisms that exacerbate symptoms in these plants.


Asunto(s)
Proteínas Argonautas , Enfermedades de las Plantas , Potexvirus , Solanum lycopersicum , Superóxido Dismutasa , Solanum lycopersicum/virología , Solanum lycopersicum/genética , Potexvirus/genética , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Enfermedades de las Plantas/virología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Silenciador del Gen , Regulación de la Expresión Génica de las Plantas , Interferencia de ARN
4.
Adv Sci (Weinh) ; 11(31): e2307937, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39031551

RESUMEN

Essential amino acids (EAA) and microRNAs (miRs) control biological activity of a cell. Whether EAA regulates the activity of miR has never been demonstrated. Here, as proof-of-concept, a tryptophan (Trp, an EAA) complex containing Argonaute 2 (Ago2) and miRs including miR-193a (Trp/Ago2/miR-193a) is identified. Trp binds miR-193a-3p and interacts with Ago2. Trp/Ago2/miR-193a increases miR-193a-3p activity via enhancing Argonaute 2 (Ago2) RNase activity. Other miRs including miR-103 and miR-107 in the Trp complex enhance miR-193a activity by targeting the same genes. Mechanistically, the Trp/Ago2/miR-193a complex interacts with Trp-binding pockets of the PIWI domain of Ago2 to enhance Ago2 mediated miR activity. This newly formed Ago2/Trp/miR-193a-3p complex is more efficient than miR-193a-3p alone in inhibiting the expression of targeted genes and inhibiting colon cancer liver metastasis. The findings show that Trp regulates miR activity through communication with the RNA-induced silencing complexes (RISC), which provides the basis for tryptophan based miR therapy.


Asunto(s)
Proteínas Argonautas , Neoplasias del Colon , Neoplasias Hepáticas , MicroARNs , Complejo Silenciador Inducido por ARN , Triptófano , Triptófano/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/secundario , Humanos , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Complejo Silenciador Inducido por ARN/metabolismo , Complejo Silenciador Inducido por ARN/genética , Neoplasias del Colon/genética , Neoplasias del Colon/patología , Neoplasias del Colon/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Ratones , Animales , Línea Celular Tumoral , Modelos Animales de Enfermedad
5.
Cells ; 13(13)2024 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-38994969

RESUMEN

During infection, adenoviruses inhibit the cellular RNA interference (RNAi) machinery by saturating the RNA-induced silencing complex (RISC) of the host cells with large amounts of virus-derived microRNAs (mivaRNAs) that bind to the key component of the complex, Argonaute 2 (AGO2). In the present study, we investigated AGO2 as a prominent player at the intersection between human adenovirus 5 (HAdV-5) and host cells because of its ability to interfere with the HAdV-5 life cycle. First, the ectopic expression of AGO2 had a detrimental effect on the ability of the virus to replicate. In addition, in silico and in vitro analyses suggested that endogenous microRNAs (miRNAs), particularly hsa-miR-7-5p, have similar effects. This miRNA was found to be able to target the HAdV-5 DNA polymerase mRNA. The inhibitory effect became more pronounced upon overexpression of AGO2, likely due to elevated AGO2 levels, which abolished the competition between cellular miRNAs and mivaRNAs for RISC incorporation. Collectively, our data suggest that endogenous miRNAs would be capable of significantly inhibiting viral replication if adenoviruses had not developed a mechanism to counteract this function. Eventually, AGO2 overexpression-mediated relief of the RISC-saturating action of mivaRNAs strongly enhanced the effectiveness of artificial miRNAs (amiRNAs) directed against the HAdV-5 preterminal protein (pTP) mRNA, suggesting a substantial benefit of co-expressing amiRNAs and AGO2 in RNAi-based strategies for the therapeutic inhibition of adenoviruses.


Asunto(s)
Adenovirus Humanos , Proteínas Argonautas , MicroARNs , Replicación Viral , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Adenovirus Humanos/genética , Adenovirus Humanos/fisiología , Complejo Silenciador Inducido por ARN/metabolismo , Complejo Silenciador Inducido por ARN/genética , Interferencia de ARN , Células HEK293
6.
PeerJ ; 12: e17737, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39035161

RESUMEN

Mango is a popular tropical fruit that requires quarantine hot water treatment (QHWT) for postharvest sanitation, which can cause abiotic stress. Plants have various defense mechanisms to cope with stress; miRNAs mainly regulate the expression of these defense responses. Proteins involved in the biogenesis of miRNAs include DICER-like (DCL), ARGONAUTE (AGO), HYPONASTIC LEAVES 1 (HYL1), SERRATE (SE), HUA ENHANCER1 (HEN1), HASTY (HST), and HEAT-SHOCK PROTEIN 90 (HSP90), among others. According to our analysis, the mango genome contains five DCL, thirteen AGO, six HYL, two SE, one HEN1, one HST, and five putative HSP90 genes. Gene structure prediction and domain identification indicate that sequences contain key domains for their respective gene families, including the RNase III domain in DCL and PAZ and PIWI domains for AGOs. In addition, phylogenetic analysis indicates the formation of clades that include the mango sequences and their respective orthologs in other flowering plant species, supporting the idea these are functional orthologs. The analysis of cis-regulatory elements of these genes allowed the identification of MYB, ABRE, GARE, MYC, and MeJA-responsive elements involved in stress responses. Gene expression analysis showed that most genes are induced between 3 to 6 h after QHWT, supporting the early role of miRNAs in stress response. Interestingly, our results suggest that mango rapidly induces the production of miRNAs after heat stress. This research will enable us to investigate further the regulation of gene expression and its effects on commercially cultivated fruits, such as mango, while maintaining sanitary standards.


Asunto(s)
Respuesta al Choque Térmico , Mangifera , MicroARNs , Mangifera/genética , Mangifera/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Respuesta al Choque Térmico/genética , Filogenia , Familia de Multigenes/genética , Regulación de la Expresión Génica de las Plantas , Genoma de Planta/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
7.
Mol Cell ; 84(15): 2918-2934.e11, 2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39025072

RESUMEN

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.


Asunto(s)
Proteínas Argonautas , Conformación de Ácido Nucleico , ARN Guía de Sistemas CRISPR-Cas , Complejo Silenciador Inducido por ARN , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Proteínas Argonautas/química , Humanos , Complejo Silenciador Inducido por ARN/metabolismo , Complejo Silenciador Inducido por ARN/genética , Complejo Silenciador Inducido por ARN/química , Cinética , ARN Guía de Sistemas CRISPR-Cas/genética , ARN Guía de Sistemas CRISPR-Cas/metabolismo , Interferencia de ARN , Secuencia de Bases , Células HEK293
8.
Polymers (Basel) ; 16(12)2024 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-38932011

RESUMEN

Nanomaterials have attracted specific consideration due to their specific characteristics and uses in several promising fields. In the present study, Chondrilla juncea was employed as a biological extract to facilitate the reduction of copper and silver ions within garlic peel powders. The resulting garlic-CuO and garlic-AgO nanocomposites were characterized using several analytical methods including FTIR, TGA/DTG, SEM, TEM, and XRD analyses. The garlic peel exhibited a rough surface. The nanoparticles were evenly dispersed across its surface. The incorporation of CuO and AgO nanoparticles affected the crystal structure of garlic peel. The establishment of CuO and AgO nanoparticles was evidenced by the highest residual mass values observed for the prepared nanocomposites. The thermogravimetric analysis showed that the prepared nanocomposites had lower thermal stability compared with garlic peel powders. The prepared nanocomposites were used for catalytic degradation of naphthol blue black B and calmagite. The decolorization process depended on the quantity of H2O2, initial concentration of azo dyes, duration of contact, and temperature of the bath. The calculated activation energy (Ea) values for the garlic-CuO nanocomposites were found to be 18.44 kJ mol-1 and 23.28 kJ mol-1 for calmagite and naphthol solutions, respectively. However, those calculated for garlic-AgO nanocomposites were found to be 50.01 kJ mol-1 and 12.44 kJ mol-1 for calmagite and naphthol, respectively.

9.
Curr Protoc ; 4(6): e1088, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38923271

RESUMEN

The middle (MID) domain of eukaryotic Argonaute (Ago) proteins and archaeal and bacterial homologues mediates the interaction with the 5'-terminal nucleotide of miRNA and siRNA guide strands. The MID domain of human Ago2 (hAgo2) is comprised of 139 amino acids with a molecular weight of 15.56 kDa. MID adopts a Rossman-like beta1-alpha1-beta2-alpha2-beta3-alpha3-beta4-alpha4 fold with a nucleotide specificity loop between beta3 and alpha3. Multiple crystal structures of nucleotides bound to hAgo2 MID have been reported, whereby complexes were obtained by soaking ligands into crystals of MID domain alone. This protocol describes a simplified one-step approach to grow well-diffracting crystals of hAgo2 MID-nucleotide complexes by mixing purified His6-SUMO-MID fusion protein, Ulp1 protease, and excess nucleotide in the presence of buffer and precipitant. The crystal structures of MID complexes with UMP, UTP and 2'-3' linked α-L-threofuranosyl thymidine-3'-triphosphate (tTTP) are presented. This article also describes fluorescence-based assays to measure dissociation constants (Kd) of MID-nucleotide interactions for nucleoside 5'-monophosphates and nucleoside 3',5'-bisphosphates. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Crystallization of Ago2 MID-nucleotide complexes Basic Protocol 2: Measurement of dissociation constant Kd between Ago2 MID and nucleotides.


Asunto(s)
Proteínas Argonautas , Humanos , Proteínas Argonautas/química , Proteínas Argonautas/metabolismo , Cristalografía por Rayos X , Nucleótidos/metabolismo , Nucleótidos/química , Unión Proteica , Histidina/química , Histidina/metabolismo , Cristalización , Dominios Proteicos , Oligopéptidos
10.
Cancers (Basel) ; 16(11)2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38893269

RESUMEN

BACKGROUND: Recurrent ovarian cancer (ROC) significantly challenges gynecological oncology due to its poor outcomes. This study assesses the impact of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) on ROC survival rates. MATERIALS AND METHODS: Conducted at the Medical University of Lublin from April 2011 to November 2022, this retrospective observational study involved 71 patients with histologically confirmed ROC who underwent CRS and subsequent HIPEC. RESULTS: The median overall survival (OS) was 41.1 months, with 3-year and 5-year survival rates post-treatment of 0.50 and 0.33, respectively. Patients undergoing radical surgery for primary ovarian cancer had a median OS of 61.9 months. The key survival-related factors included the Peritoneal Carcinomatosis Index (PCI) score, AGO score, platinum sensitivity, and ECOG status. CONCLUSIONS: The key factors enhancing ROC patients' survival include radical surgery, optimal performance status, platinum sensitivity, a positive AGO score, and a lower PCI. This study highlights the predictive value of the platinum resistance and AGO score in patient outcomes, underlining their role in treatment planning. Further prospective research is needed to confirm these results and improve patient selection for this treatment approach.

11.
Proc Natl Acad Sci U S A ; 121(24): e2321532121, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38830102

RESUMEN

Cannabis sativa is known for its therapeutic benefit in various diseases including pain relief by targeting cannabinoid receptors. The primary component of cannabis, Δ9-tetrahydrocannabinol (THC), and other agonists engage the orthosteric site of CB1, activating both Gi and ß-arrestin signaling pathways. The activation of diverse pathways could result in on-target side effects and cannabis addiction, which may hinder therapeutic potential. A significant challenge in pharmacology is the design of a ligand that can modulate specific signaling of CB1. By leveraging insights from the structure-function selectivity relationship (SFSR), we have identified Gi signaling-biased agonist-allosteric modulators (ago-BAMs). Further, two cryoelectron microscopy (cryo-EM) structures reveal the binding mode of ago-BAM at the extrahelical allosteric site of CB1. Combining mutagenesis and pharmacological studies, we elucidated the detailed mechanism of ago-BAM-mediated biased signaling. Notably, ago-BAM CB-05 demonstrated analgesic efficacy with fewer side effects, minimal drug toxicity and no cannabis addiction in mouse pain models. In summary, our finding not only suggests that ago-BAMs of CB1 provide a potential nonopioid strategy for pain management but also sheds light on BAM identification for GPCRs.


Asunto(s)
Microscopía por Crioelectrón , Receptor Cannabinoide CB1 , Transducción de Señal , Receptor Cannabinoide CB1/metabolismo , Receptor Cannabinoide CB1/genética , Receptor Cannabinoide CB1/química , Animales , Regulación Alostérica/efectos de los fármacos , Ratones , Humanos , Transducción de Señal/efectos de los fármacos , Proteínas de Unión al GTP/metabolismo , Proteínas de Unión al GTP/genética , Células HEK293 , Relación Estructura-Actividad , Dronabinol/farmacología , Dronabinol/química , Dronabinol/análogos & derivados , Cannabis/química , Cannabis/metabolismo
12.
Cell Rep ; 43(6): 114369, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38878288

RESUMEN

Epitranscriptomics represents a further layer of gene expression regulation. Specifically, N6-methyladenosine (m6A) regulates RNA maturation, stability, degradation, and translation. Regarding microRNAs (miRNAs), while it has been reported that m6A impacts their biogenesis, the functional effects on mature miRNAs remain unclear. Here, we show that m6A modification on specific miRNAs weakens their coupling to AGO2, impairs their function on target mRNAs, determines their delivery into extracellular vesicles (EVs), and provides functional information to receiving cells. Mechanistically, the intracellular functional impairment is caused by m6A-mediated inhibition of AGO2/miRNA interaction, the EV loading is favored by m6A-mediated recognition by the RNA-binding protein (RBP) hnRNPA2B1, and the EV-miRNA function in the receiving cell requires their FTO-mediated demethylation. Consequently, cells express specific miRNAs that do not impact endogenous transcripts but provide regulatory information for cell-to-cell communication. This highlights that a further level of complexity should be considered when relating cellular dynamics to specific miRNAs.


Asunto(s)
Adenosina , Proteínas Argonautas , Comunicación Celular , Vesículas Extracelulares , MicroARNs , MicroARNs/metabolismo , MicroARNs/genética , Humanos , Adenosina/análogos & derivados , Adenosina/metabolismo , Vesículas Extracelulares/metabolismo , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Ribonucleoproteína Heterogénea-Nuclear Grupo A-B/metabolismo , ARN Mensajero/metabolismo , ARN Mensajero/genética , Células HEK293 , Animales
13.
Cell Rep ; 43(7): 114391, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-38923459

RESUMEN

Inhibition of nucleic acid targets is mediated by Argonaute (Ago) proteins guided by RNA or DNA. Although the mechanisms underpinning the functions of eukaryotic and "long" prokaryotic Ago proteins (pAgos) are well understood, those for short pAgos remain enigmatic. Here, we determine two cryoelectron microscopy structures of short pAgos in association with the NADase-domain-containing protein Sir2-APAZ from Geobacter sulfurreducens (GsSir2/Ago): the guide RNA-target DNA-loaded GsSir2/Ago quaternary complex (2.58 Å) and the dimer of the quaternary complex (2.93Å). These structures show that the nucleic acid binding causes profound conformational changes that result in disorder or partial dissociation of the Sir2 domain, suggesting that it adopts a NADase-active conformation. Subsequently, two RNA-/DNA-loaded GsSir2/Ago complexes form a dimer through their MID domains, further enhancing NADase activity through synergistic effects. The findings provide a structural basis for short-pAgo-mediated defense against invading nucleic acids.


Asunto(s)
Proteínas Argonautas , Proteínas Argonautas/metabolismo , Proteínas Argonautas/química , Geobacter/metabolismo , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Sirtuina 2/metabolismo , Multimerización de Proteína , Unión Proteica , Microscopía por Crioelectrón , Activación Enzimática , Modelos Moleculares , Ácidos Nucleicos/metabolismo
14.
Cancer Biol Ther ; 25(1): 2361594, 2024 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-38857058

RESUMEN

P4HA2 has been implicated in various malignant tumors; however, its expression and functional role in colorectal cancer (CRC) remain poorly elucidated. This study aims to investigate the involvement of P4HA2 in CRC metastasis and progression, uncovering the underlying mechanisms. In colorectal cancer (CRC), P4HA2 exhibited overexpression, and elevated levels of P4HA2 expression were associated with an unfavorable prognosis. Functional assays demonstrated P4HA2's regulation of cell proliferation, and epithelial-mesenchymal transition (EMT) both in vitro and in vivo. Additionally, the AGO1 expression was correlated with P4HA2, and depletion of AGO1 reversed the proliferation and EMT function induced by P4HA2. Chromatin immunoprecipitation (ChIP) and luciferase assays suggested that the transcription factor SP1 binds to the promoter sequence of P4HA2, activating its expression in CRC. This study unveiled SP1 as a transcriptional regulator of P4HA2 in CRC and AGO1 is a probable target of P4HA2. In conclusion, P4HA2 emerges as a potential prognostic biomarker and promising therapeutic target in colorectal cancer.


Asunto(s)
Neoplasias Colorrectales , Progresión de la Enfermedad , Regulación Neoplásica de la Expresión Génica , Factor de Transcripción Sp1 , Animales , Femenino , Humanos , Masculino , Ratones , Línea Celular Tumoral , Proliferación Celular , Neoplasias Colorrectales/patología , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Transición Epitelial-Mesenquimal/genética , Regulación Neoplásica de la Expresión Génica/genética , Ratones Desnudos , Pronóstico , Factor de Transcripción Sp1/metabolismo , Factor de Transcripción Sp1/genética
15.
bioRxiv ; 2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38766062

RESUMEN

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.

16.
Front Plant Sci ; 15: 1372880, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38576781

RESUMEN

RNA-directed DNA methylation (RdDM) is driven by small RNAs (sRNAs) complementary to the nascent transcript of RNA polymerase V (Pol V). sRNAs associated with ARGONAUTE (AGO) proteins are tethered to Pol V mainly by the AGO-hook domain of its subunit NRPE1. We found, by in silico analyses, that Pol V strongly colocalizes on chromatin with another AGO-hook protein, SPT6-like (SPT6L), which is a known essential transcription elongation factor of Pol II. Our phylogenetic analysis revealed that SPT6L acquired its AGO-binding capacity already in the most basal streptophyte algae, even before the emergence of Pol V, suggesting that SPT6L might be a driving force behind the RdDM evolution. Since its emergence, SPT6L with the AGO-hook represents the only conserved SPT6 homolog in Viridiplantae, implying that the same protein is involved in both Pol II and Pol V complexes. To better understand the role of SPT6L in the Pol V complex, we characterized genomic loci where these two colocalize and uncovered that DNA methylation there is more dynamic, driven by higher levels of sRNAs often from non-canonical RdDM pathways and more dependent on chromatin modifying and remodeling proteins like MORC. Pol V loci with SPT6L are highly depleted in helitrons but enriched in gene promoters for which locally and temporally precise methylation is necessary. In view of these results, we discuss potential roles of multiple AGO-hook domains present in the Pol V complex and speculate that SPT6L mediates de novo methylation of naïve loci by interconnecting Pol II and Pol V activities.

17.
EMBO J ; 43(9): 1843-1869, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38565948

RESUMEN

The RNA-silencing effector ARGONAUTE10 influences cell fate in plant shoot and floral meristems. ARGONAUTE10 also accumulates in the root apical meristem (RAM), yet its function(s) therein remain elusive. Here, we show that ARGONAUTE10 is expressed in the root cell initials where it controls overall RAM activity and length. ARGONAUTE10 is also expressed in the stele, where post-transcriptional regulation confines it to the root tip's pro-vascular region. There, variations in ARGONAUTE10 levels modulate metaxylem-vs-protoxylem specification. Both ARGONAUTE10 functions entail its selective, high-affinity binding to mobile miR165/166 transcribed in the neighboring endodermis. ARGONAUTE10-bound miR165/166 is degraded, likely via SMALL-RNA-DEGRADING-NUCLEASES1/2, thus reducing miR165/166 ability to silence, via ARGONAUTE1, the transcripts of cell fate-influencing transcription factors. These include PHABULOSA (PHB), which controls meristem activity in the initials and xylem differentiation in the pro-vasculature. During early germination, PHB transcription increases while dynamic, spatially-restricted transcriptional and post-transcriptional mechanisms reduce and confine ARGONAUTE10 accumulation to the provascular cells surrounding the newly-forming xylem axis. Adequate miR165/166 concentrations are thereby channeled along the ARGONAUTE10-deficient yet ARGONAUTE1-proficient axis. Consequently, inversely-correlated miR165/166 and PHB gradients form preferentially along the axis despite ubiquitous PHB transcription and widespread miR165/166 delivery inside the whole vascular cylinder.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Proteínas Argonautas , Regulación de la Expresión Génica de las Plantas , Meristema , MicroARNs , Raíces de Plantas , Xilema , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , MicroARNs/metabolismo , MicroARNs/genética , Meristema/metabolismo , Meristema/crecimiento & desarrollo , Meristema/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Xilema/metabolismo , Xilema/crecimiento & desarrollo , Xilema/genética , Raíces de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética
18.
Biomol NMR Assign ; 18(1): 99-104, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38668800

RESUMEN

As sessile organisms, plants need to counteract different biotic and abiotic stresses to survive. RNA interference provides natural immunity against various plant pathogens, especially against viral infections via inhibition of viral genome replication or translation. In plants, DRB3, a multi-domain protein containing two N-terminal dsRNA binding domains (dsRBD), plays a vital role in RNA-directed DNA methylation of the geminiviral genome. Additionally, DRB3 arrests the replication of the viral genome in the viral replication complex of RNA viruses through a mechanism that has yet to be fully deciphered. Therefore, as a first step towards exploring the structural details of DRB3, we present a nearly complete backbone and side chain assignment of the two N-terminal dsRBD domains.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Resonancia Magnética Nuclear Biomolecular , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Interferencia de ARN , Dominios Proteicos , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo
19.
Plant Cell Rep ; 43(4): 96, 2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38480545

RESUMEN

KEY MESSAGE: Barley AGO4 proteins complement expressional changes of epigenetically regulated genes in Arabidopsis ago4-3 mutant and show a distinct affinity for the 5' terminal nucleotide of small RNAs, demonstrating functional conservation and divergence. The function of Argonaute 4 (AGO4) in Arabidopsis thaliana has been extensively characterized; however, its role in monocots, which have large genomes abundantly supplemented with transposable elements (TEs), remains elusive. The study of barley AGO4 proteins can provide insights into the conserved aspects of RNA-directed DNA methylation (RdDM) and could also have further applications in the field of epigenetics or crop improvement. Bioinformatic analysis of RNA sequencing data identified two active AGO4 genes in barley, HvAGO4a and HvAGO4b. These genes function similar to AtAGO4 in an Arabidopsis heterologous complementation system, primarily binding to 24-nucleotide long small RNAs (sRNAs) and triggering methylation at specific target loci. Like AtAGO4, HvAGO4B exhibits a preference for binding sRNAs with 5' adenine residue, while also accepting 5' guanine, uracil, and cytosine residues. In contrast, HvAGO4A selectively binds only sRNAs with a 5' adenine residue. The diverse binding capacity of barley AGO4 proteins is reflected in TE-derived sRNAs and in their varying abundance. Both barley AGO4 proteins effectively restore the levels of extrachromosomal DNA and transcript abundancy of the heat-activated ONSEN retrotransposon to those observed in wild-type Arabidopsis plants. Our study provides insight into the distinct binding specificities and involvement in TE regulation of barley AGO4 proteins in Arabidopsis by heterologous complementation.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Hordeum , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Hordeum/genética , Hordeum/metabolismo , ARN Interferente Pequeño/genética , Nucleótidos/metabolismo , Adenina/metabolismo , Metilación de ADN/genética , ARN de Planta/genética
20.
Mol Ther ; 32(5): 1578-1594, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38475992

RESUMEN

Heart failure (HF) is manifested by transcriptional and posttranscriptional reprogramming of critical genes. Multiple studies have revealed that microRNAs could translocate into subcellular organelles such as the nucleus to modify gene expression. However, the functional property of subcellular Argonaute2 (AGO2), the core member of the microRNA machinery, has remained elusive in HF. AGO2 was found to be localized in both the cytoplasm and nucleus of cardiomyocytes, and robustly increased in the failing hearts of patients and animal models. We demonstrated that nuclear AGO2 rather than cytosolic AGO2 overexpression by recombinant adeno-associated virus (serotype 9) with cardiomyocyte-specific troponin T promoter exacerbated the cardiac dysfunction in transverse aortic constriction (TAC)-operated mice. Mechanistically, nuclear AGO2 activates the transcription of ANKRD1, encoding ankyrin repeat domain-containing protein 1 (ANKRD1), which also has a dual function in the cytoplasm as part of the I-band of the sarcomere and in the nucleus as a transcriptional cofactor. Overexpression of nuclear ANKRD1 recaptured some key features of cardiac remodeling by inducing pathological MYH7 activation, whereas cytosolic ANKRD1 seemed cardioprotective. For clinical practice, we found ivermectin, an antiparasite drug, and ANPep, an ANKRD1 nuclear location signal mimetic peptide, were able to prevent ANKRD1 nuclear import, resulting in the improvement of cardiac performance in TAC-induced HF.


Asunto(s)
Proteínas Argonautas , Modelos Animales de Enfermedad , Insuficiencia Cardíaca , Miocitos Cardíacos , Proteínas Represoras , Animales , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/genética , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/patología , Ratones , Humanos , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Miocitos Cardíacos/metabolismo , Proteínas Represoras/metabolismo , Proteínas Represoras/genética , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Remodelación Ventricular , Núcleo Celular/metabolismo , Proteínas Musculares/metabolismo , Proteínas Musculares/genética , Regulación de la Expresión Génica , Masculino , Dependovirus/genética , Transcripción Genética
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