Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.123
Filtrar
1.
Food Chem ; 366: 130560, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34284183

RESUMO

The colorimetric method can determine the initial results even by the naked eyes, but its main challenge for antibiotics detection in food at present is the relatively low sensitivity. Herein, an ultrasensitive colorimetric biosensor based on G-quadruplex DNAzyme was firstly proposed for the rapid detection of trace tetracycline antibiotics like tetracycline, oxytetracycline, chlortetracycline and doxycycline. DNAzyme composed of hemin and G-quadruplex has peroxidase-like activity, and tetracyclines can combine with hemin to form a stable complex and reduce catalytic activity, making the color of solution changes from yellow to green. The limits of detection (LOD) of the proposed colorimetric biosensor for tetracyclines is determined as low as 3.1 nM, which is lower than most of the other colorimetric methods for antibiotics detection. Moreover, the average recovery range of tetracyclines in actual samples is from 89% to 99%, indicating that such strategy may has bright application prospects for tetracyclines detection in foods.


Assuntos
Técnicas Biossensoriais , DNA Catalítico , Tetraciclinas/análise , Antibacterianos , Colorimetria , Quadruplex G , Hemina , Peroxidase , Peroxidases
2.
Talanta ; 236: 122821, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635211

RESUMO

Well-defined structures and compositions of nucleic acids afford oligonucleotide probes with unique chemical properties and biological functions for various biosensing applications. Herein, a unique and special oligonucleotide probe, named multifunction-integrated linear oligonucleotide probe (MI-LOP), was facile designed and reported for label-free and turn-on fluorescent detection of the codon component of genetically modified organisms (GMOs). The MI-LOP contains four different functional regions including recognition of target, serving as polymerization template, and creating polymerization primer-linked G-quadruplex (PP-G-quadruplex). Without the aid of any other oligonucleotides, the introduction of target DNA can make each function of the MI-LOP executed one-by-one, during which the species of target DNA, target analogue, and PP-G-quadruplex can be cyclically utilized and in turn induce a multiplex signal amplification responsible for substantial collection of the G-quadruplex moieties under isothermal conditions. The stable G-quadruplexes can combine with N-methyl mesoporphyrin IX (NMM) and function as efficient fluorescence light-up probes, rapidly leading to a dramatic increase in the fluorescence intensity for the amplified detection of the target codon component. Our results strongly demonstrate that the developed MI-LOP with multiplex amplification effect confers the sensing strategy a high sensitivity and specificity for quantitative and qualitative detection of the target codon. And it has also been successfully applied for analyzing target codon in the complex extractions of soybean. The achievements highlight the significance of using oligonucleotide probes as promising analytical tools to promote the basic biochemical research and help in food and environmental analysis.


Assuntos
Quadruplex G , DNA/genética , Fluorescência , Sondas de Oligonucleotídeos/genética , Plantas Geneticamente Modificadas
3.
Mol Biol (Mosk) ; 55(5): 772-795, 2021.
Artigo em Russo | MEDLINE | ID: mdl-34671004

RESUMO

Cell metabolism depends, to a large extent, on correct regulation of gene expression. One of the mechanisms of regulation is the formation of nucleic acid secondary structures, among which guanine quadruplexes (G-quadruplexes, or G4) are of particular importance. G-quadruplexes are dynamic structures whose stability is determined by their size, ionic composition, and the nature of the nucleic acids forming them. They are regulated by various protein factors. Guanine quadruplexes play an important role in the regulation of many processes occurring in DNA and RNA, from maintaining telomere homeostasis to determining the ribosome landing site on mRNA. Therefore, these structures are considered a promising target for antitumor therapy, and their detailed study is important to modern biology. This review is focused on the structure and thermodynamic properties of G-quadruplexes together with their interaction with some nuclear proteins.


Assuntos
Quadruplex G , DNA , RNA , Telômero/genética , Termodinâmica
4.
Analyst ; 146(19): 5866-5872, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34570847

RESUMO

DNA-tuned dye assemblies have received considerable attention toward developing various devices. Owing to easy conformation implementation, G-quadruplexes (G4s) have been extensively used as initiators to grow dye assemblies with controllable chiralities. However, programmed chirality regulation of dye assemblies for a given G4 sequence has not been realized in a straightforward manner. In this work, we replaced a middle guanine in the G-tracts of a human telomeric G4 with an apurinic site (AP site) to meet the programmed dye assemblies. Although all of the AP site replacements altered the G4 conformation from the hybrid to the antiparallel folding, the handedness of pinacyanol (PIN) assemblies grown on the AP site-containing G4 was programmably regulated. The G4 with the AP site at the 5'-most G-tract grew right-handed assemblies, while that with the AP site at the 3'-most G-tract grew left-handed assemblies. The handedness of assemblies almost totally mirrored each other within 450-700 nm. Interestingly, we found that the AP site provided a specific binding site for guanosine and guanine, and this binding event sensitively broke the chiral assemblies. Thus, dye assembly-based sensors can be easily established based on the chiral responses with a high selectivity and sensitivity. Our work first demonstrates the AP site programmed chirality regulation of G4-grown dye assemblies and will find wide application in chiral devices.


Assuntos
Quadruplex G , DNA , Guanina , Guanosina , Humanos , Telômero
5.
Int J Mol Sci ; 22(18)2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34576112

RESUMO

G-quadruplexes constitute an important type of nucleic acid structure, which can be found in living cells and applied by cell machinery as pivotal regulatory elements. Importantly, robust development of SELEX technology and modern, nucleic acid-based therapeutic strategies targeted towards various molecules have also revealed a large group of potent aptamers whose structures are grounded in G-quadruplexes. In this review, we analyze further extension of tetraplexes by additional structural elements and investigate whether G-quadruplex junctions with duplex, hairpin, triplex, or second G-quadruplex motifs are favorable for aptamers stability and biological activity. Furthermore, we indicate the specific and pivotal role of the G-quadruplex domain and the additional structural elements in interactions with target molecules. Finally, we consider the potency of G-quadruplex junctions in future applications and indicate the emerging research area that is still waiting for development to obtain highly specific and effective nucleic acid-based molecular tools.


Assuntos
Aptâmeros de Nucleotídeos/genética , Quadruplex G , Motivos de Nucleotídeos/genética , Sequência de Bases , Humanos
6.
Nanoscale ; 13(32): 13795-13808, 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34477654

RESUMO

Light-activated functional materials capable of remote control over duplex and G-quadruplex (G4) nucleic acids formation at the cellular level are still very rare. Herein, we report on the photoinduced macrocyclisation of a helicenoid quinoline derivative of binaphthol that selectively provides easy access to an unprecedented class of extended heteroaromatic structures with remarkable photophysical and DNA/RNA binding properties. Thus, while the native bisquinoline precursor shows no DNA binding activity, the new in situ photochemically generated probe features high association constants to DNA and RNA G4s. The latter inhibits DNA synthesis by selectively stabilizing G4 structures associated with oncogenic promoters and telomere repeat units. Finally, the light sensitive compound is capable of in cellulo photoconversion, localizes primarily in the G4-rich sites of cancer cells, competes with a well-known G4 binder and shows a clear nuclear co-localization with the quadruplex specific antibody BG4. This work provides a benchmark for the future design and development of a brand-new generation of light-activated target-selective G4-binders.


Assuntos
Corantes Fluorescentes , Quadruplex G , DNA , Ligantes , Telômero
7.
Int J Mol Sci ; 22(17)2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34502085

RESUMO

Facile method for the preparation of ß-cyclodextrin-functionalized hydrogels based on guanosine quartet assembly was described. A series of seven hydrogels were prepared by linking ß-cyclodextrin molecules with guanosine moieties in different ratios through benzene-1,4-diboronic acid linker in the presence of potassium hydroxide. The potassium ions acted as a reticulation agent by forming guanosine quartets, leading to the formation of self-sustained transparent hydrogels. The ratios of the ß-cyclodextrin and guanosine components have a significant effect on the internal structuration of the components and, correspondingly, on the mechanical properties of the final gels, offering a tunablity of the system by varying the components ratio. The insights into the hydrogels' structuration were achieved by circular dichroism, scanning electron microscopy, atomic force microscopy, and X-ray diffraction. Rheological measurements revealed self-healing and thixotropic properties of all the investigated samples, which, in combination with available cyclodextrin cavities for active components loading, make them remarkable candidates for specific applications in biomedical and pharmaceutical fields. Moreover, all the prepared samples displayed selective antimicrobial properties against S. aureus in planktonic and biofilm phase, the activity also depending on the guanosine and cyclodextrin ratio within the hydrogel structure.


Assuntos
Anti-Infecciosos/síntese química , Quadruplex G , Hidrogéis/síntese química , beta-Ciclodextrinas/química , Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Candida/efeitos dos fármacos , Hidrogéis/farmacologia , Staphylococcus aureus/efeitos dos fármacos
8.
Cytogenet Genome Res ; 161(6-7): 285-296, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34469893

RESUMO

Unique repetitive elements of the eukaryotic genome can be problematic for cellular DNA replication and transcription and pose a source of genomic instability. Human ribosomal DNA (rDNA) exists as repeating units clustered together on several chromosomes. Understanding the molecular mechanisms whereby rDNA interferes with normal genome homeostasis is the subject of this review. We discuss the instability of rDNA as a driver of senescence and the important roles of helicases to suppress its deleterious effects. The propensity of rDNA that is rich in guanine bases to form G-quadruplexes (G4) is discussed and evaluated in disease pathogenesis. Targeting G4 in the ribosomes and other chromosomal loci may represent a useful synthetic lethal approach to combating cancer.


Assuntos
DNA Ribossômico/genética , Quadruplex G , Genoma Humano/genética , Instabilidade Genômica , Neoplasias/genética , Sequências Repetitivas de Ácido Nucleico/genética , DNA Helicases/genética , DNA Helicases/metabolismo , Replicação do DNA/genética , DNA Ribossômico/química , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias/metabolismo
9.
Talanta ; 235: 122748, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517616

RESUMO

Cancer-derived exosomes have emerged as a valuable biomarker for cancer diagnosis and prognosis. However, the heterogeneity of exosomes often leads to low selectivity based on the single recognition method. Given this, we have developed a dual-aptamer recognition strategy based on G-quadruplex nanowires for selective analysis of exosomes. In this work, target exosomes were first captured by CD63 aptamers modified on magnetic beads (MBs) and then combined with AS1411 aptamer, which shows high binding affinity to nucleolin when forming stable G-quadruplex structure. Then the free myc monomer can spontaneously assemble into higher order G-wire superstructures on the allosteric AS1411, and resulting enhanced fluorescence signal, which can realize sensitive and specific analysis of the target exosomes. This dual-aptamer recognition-based method is simple and universal for different types of exosomes, which is of great significance for clinical cancer diagnosis.


Assuntos
Aptâmeros de Nucleotídeos , Exossomos , Quadruplex G , Nanofios , Neoplasias , Humanos
10.
Talanta ; 235: 122777, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517634

RESUMO

DNA G-quadruplexes (G4s) formed by guanine(G)-rich sequences show diversity of structural topologies. The detection of structural details is of great significance for understanding of their functions and for the target drug design, but is very challenging. Herein, we demonstrate that the surface-enhanced Raman spectroscopy (SERS) via Ag IANPs as substrates is able to identify the numbers of Adenine (A) located on the G-quartet of the G4s. Eight G4s are selected for SERS studies. Besides the detection of series of characteristic bands indicating the formation of G4s, the intensity of the band represented A base ring breath (νA, ~733 cm-1) is observed particularly enhanced when there are A bases coplanar with G-quartet, and which is higher than the intensity of the band corresponding to G base ring breath (νG, ~655 cm-1). Furthermore, the band intensity ratio of νA to νG versus the ratio of the numbers of A on the plane to the sum of numbers of A and G shows very good linear relationship. Thus, based on the band intensities of νA to νG and their ratio in the SERS spectrum, the G-quadruplexes with or without a coplanar A base and numbers of A bases on the plane of G-quartet can be facilely identified. The method is simple, fast, low cost and sensitive to provide particular details of the structure in aqueous solution, therefore, implies widespread applications.


Assuntos
Quadruplex G , Análise Espectral Raman , Adenina , Guanina
11.
Anal Chem ; 93(36): 12383-12390, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34449197

RESUMO

Circulating extracellular vesicles (EVs) are promising biomarkers for the early diagnosis and prognosis of cancer in a non-invasive manner. However, the rapid and accurate identification of EVs in complex biological samples is technically challenging, which is attributed to the requirement of extensive sample purification and unsatisfactory detection accuracy due to the disturbance of interfering proteins. Herein, a simultaneous binding of double-positive EV membrane protein-based recognition mode (DRM) is proposed. By the combination of DRM-mediated toehold activation and G-quadruplex DNAZyme-catalyzed etching of Au@Ag nanorods (Au@Ag NRs), we have developed an accurate, non-purified, low-cost, and visual strategy for EV identification. The synchronous binding of double-positive proteins on EV membranes is validated by confocal laser scanning microscopy analysis. This approach exhibits excellent specificity and sensitivity toward EVs ranging from 1.0 × 105 to 1.0 × 109 particles/mL with a detection limit of 6.31 × 104 particles/mL. Moreover, we have successfully realized non-purified EV quantification in complex biological media. In addition, target-initiated catalyzed hairpin assembly (CHA) is integrated with G-quadruplex DNAZyme-catalyzed color variation of Au@Ag NRs; thus, low-background EV detection can be achieved by the naked eye. Furthermore, our strategy is easy to adapt to high-throughput formats by using an automatic microplate reader, which could be expected to meet the requirements for high-throughput detection of clinical samples. With its capacities of rapidness, portability, affordability, high throughput, non-purification, and visual detection, this strategy could provide a practical tool for accurate identification of EVs and early diagnosis of cancer.


Assuntos
DNA Catalítico , Vesículas Extracelulares , Quadruplex G , Nanotubos , Neoplasias , Humanos
12.
Molecules ; 26(16)2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34443326

RESUMO

This work provides new insights from our team regarding advances in targeting canonical and non-canonical nucleic acid structures. This modality of medical treatment is used as a form of molecular medicine specifically against the growth of cancer cells. Nevertheless, because of increasing concerns about bacterial antibiotic resistance, this medical strategy is also being explored in this field. Up to three strategies for the use of DNA as target have been studied in our research lines during the last few years: (1) the intercalation of phenanthroline derivatives with duplex DNA; (2) the interaction of metal complexes containing phenanthroline with G-quadruplexes; and (3) the activity of Mo polyoxometalates and other Mo-oxo species as artificial phosphoesterases to catalyze the hydrolysis of phosphoester bonds in DNA. We demonstrate some promising computational results concerning the favorable interaction of these small molecules with DNA that could correspond to cytotoxic effects against tumoral cells and microorganisms. Therefore, our results open the door for the pharmaceutical and medical applications of the compounds we propose.


Assuntos
Ânions/química , Complexos de Coordenação/química , DNA/química , Quadruplex G , Fenantrolinas/química , Polieletrólitos/química , Ligantes
13.
Molecules ; 26(16)2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34443603

RESUMO

Abnormal levels of reduced glutathione (GSH) and glutathione reductase (GR) are usually related to a variety of diseases, so it is of great significance to determine the GSH concentration and GR activity. We herein develop a smartphone-assisted colorimetric biosensor for the detection of GSH and GR activity in human serum and mouse liver using hemin/G-quadruplex DNAzyme. Firstly, an obvious color change from colorless to green can be observed, owing to the high peroxidase-like activity of hemin/G-quadruplex DNAzyme toward 2,2'-azino-bis(3-ethylbenzothiozoline-6-sulfonic acid) (ABTS). With the addition of GSH or GR, the H2O2-mediated oxidation of ABTS catalyzed by hemin/G-quadruplex DNAzyme is significantly inhibited, resulting in remarkable color fading. Therefore, the detection of GSH and GR activity can be achieved by observing the color transition or measuring the absorbance at 420 nm. The detection limit was estimated to be as low as 0.1 µM and 10 µU/mL for GSH and GR, respectively. More interestingly, the RGB values of the sensing system can be identified by the smartphone application (APP, color collect), which makes it an ideal format for on-site determination and point-of-care testing (POCT). In addition, the proposed method shows excellent selectivity and acceptable applicability for the determination of GSH concentration and GR activity in human serum samples and mouse liver tissues, which might hold great application potential in clinical diagnosis and drug screening.


Assuntos
Técnicas Biossensoriais/métodos , DNA Catalítico/metabolismo , Glutationa Redutase/sangue , Glutationa/sangue , Hemina/metabolismo , Fígado/metabolismo , Smartphone , Animais , Colorimetria , DNA Catalítico/química , Quadruplex G , Glutationa/metabolismo , Glutationa Redutase/metabolismo , Humanos , Camundongos , Oxirredução
14.
Molecules ; 26(16)2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34443620

RESUMO

G-quadruplexes (G4s) are higher-order supramolecular structures, biologically important in the regulation of many key processes. Among all, the recent discoveries relating to RNA-G4s, including their potential involvement as antiviral targets against COVID-19, have triggered the ever-increasing need to develop selective molecules able to interact with parallel G4s. Naphthalene diimides (NDIs) are widely exploited as G4 ligands, being able to induce and strongly stabilize these structures. Sometimes, a reversible NDI-G4 interaction is also associated with an irreversible one, due to the cleavage and/or modification of G4s by functional-NDIs. This is the case of NDI-Cu-DETA, a copper(II) complex able to cleave G4s in the closest proximity to the target binding site. Herein, we present two original Cu(II)-NDI complexes, inspired by NDI-Cu-DETA, differently functionalized with 2-(2-aminoethoxy)ethanol side-chains, to selectively drive redox-catalyzed activity towards parallel G4s. The selective interaction toward parallel G4 topology, controlled by the presence of 2-(2-aminoethoxy)ethanol side chains, was already firmly demonstrated by us using core-extended NDIs. In the present study, the presence of protonable moieties and the copper(II) cavity, increases the binding affinity and specificity of these two NDIs for a telomeric RNA-G4. Once defined the copper coordination relationship and binding constants by competition titrations, ability in G4 stabilization, and ROS-induced cleavage were analyzed. The propensity in the stabilization of parallel topology was highlighted for both of the new compounds HP2Cu and PE2Cu. The results obtained are particularly promising, paving the way for the development of new selective functional ligands for binding and destructuring parallel G4s.


Assuntos
Complexos de Coordenação/química , Cobre/química , Quadruplex G , Imidas/química , Naftalenos/química , Sítios de Ligação , DEET/química , Ligantes , Oxirredução , Polietilenoglicóis/química , Relação Estrutura-Atividade
15.
Nucleic Acids Res ; 49(15): 8947-8960, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34365512

RESUMO

Several sequences forming G-quadruplex are highly conserved in regulatory regions of genomes of different organisms and affect various biological processes like gene expression. Diverse G-quadruplex properties can be modulated via their interaction with small polyaromatic molecules such as pyrene. To investigate how pyrene interacts with G-rich DNAs, we incorporated deoxyuridine nucleotide(s) with a covalently attached pyrene moiety (Upy) into a model system that forms parallel G-quadruplex structures. We individually substituted terminal positions and positions in the pentaloop of the c-kit2 sequence originating from the KIT proto-oncogene with Upy and performed a detailed NMR structural study accompanied with molecular dynamic simulations. Our results showed that incorporation into the pentaloop leads to structural polymorphism and in some cases also thermal destabilization. In contrast, terminal positions were found to cause a substantial thermodynamic stabilization while preserving topology of the parent c-kit2 G-quadruplex. Thermodynamic stabilization results from π-π stacking between the polyaromatic core of the pyrene moiety and guanine nucleotides of outer G-quartets. Thanks to the prevalent overall conformation, our structures mimic the G-quadruplex found in human KIT proto-oncogene and could potentially have antiproliferative effects on cancer cells.


Assuntos
Quadruplex G , Proteínas Proto-Oncogênicas c-kit/genética , Desoxiuridina/química , Humanos , Modelos Moleculares , Ressonância Magnética Nuclear Biomolecular , Regiões Promotoras Genéticas , Pirenos/química , Termodinâmica
16.
J Phys Chem Lett ; 12(34): 8309-8313, 2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34428044

RESUMO

Guanine quadruplexes are four-stranded DNA/RNA structures composed of a guanine core (vertically stacked guanine tetrads) and peripheral groups (dangling ends and/or loops). Such a dual structural arrangement of the nucleobases favors their photoionization at energies significantly lower than the guanine ionization potential. This effect is important with respect to the oxidative DNA damage and for applications in the field of optoelectronics. Photoionization quantum yields, determined at 266 nm by nanosecond transient absorption spectroscopy, strongly depend on both the type and position of the peripheral nucleobases. The highest value (1.5 × 10-2) is found for the tetramolecular structure (AG4A)4 in which adenines are intermittently stacked on the adjacent guanine tetrads, as determined by nuclear magnetic resonance spectroscopy. Quantum chemistry calculations show that peripheral nucleobases interfere in a key step preceding electron ejection: charge separation, initiated by the population of charge transfer states during the relaxation of electronic excited states.


Assuntos
Quadruplex G , Guanina/química , Raios Ultravioleta , Modelos Moleculares , Teoria Quântica
17.
Biosens Bioelectron ; 192: 113547, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34385013

RESUMO

Herein, a photocurrent polarity switching platform for highly selective assay of mucin 1 (MUC1) was developed based on target-induced hemin transfer from ZrO2 hollow spheres (ZrO2 HSs) to G-quadruplex nanowires (G wires). In this system, SiO2 spheres were used as templates to synthesize the uniform and mesoporous ZrO2 HSs. As nanocontainers, ZrO2 HSs could load hemin in its cavity via pores. Then, the aptamers of MUC1, as bio-gates, blocked the pores of ZrO2 HSs based on the specific binding of Zr4+ and the phosphate groups of aptamer. In the presence of MUC1, the aptamer could specifically recognize and bind with MUC1, and then leave away from the surface of ZrO2 HSs, which resulted in the opening of the bio-gates and releasing of hemin. Assisted with the G wires formed on the Au NPs/In2S3/ITO, the released hemin was captured on the electrode through the formation of hemin/G-quadruplex structure, leading to the switch of the photocurrent polarity of the electrode from anodic photocurrent to cathodic photocurrent. The proposed photoelectrochemical biosensor showed outstanding performance for MUC1 assay with high selectivity, wide linear response range (1 fg mL-1 -10 ng mL-1) and lower detection limit (0.48 fg mL-1). And the strategy could be easily extended to a triple-mode detection of MUC1 because the hemin/G-quadruplex structure was widely used in electrochemical and colorimetric methods as a hydrogen peroxide mimetic enzyme, which might provide wide applications in biological or clinical studies.


Assuntos
Técnicas Biossensoriais , DNA Catalítico , Quadruplex G , Nanofios , DNA Catalítico/metabolismo , Técnicas Eletroquímicas , Hemina , Limite de Detecção , Mucina-1 , Dióxido de Silício
18.
Nat Commun ; 12(1): 5043, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413292

RESUMO

Skeletal muscle has a remarkable ability to regenerate owing to its resident stem cells (also called satellite cells, SCs). SCs are normally quiescent; when stimulated by damage, they activate and expand to form new fibers. The mechanisms underlying SC proliferative progression remain poorly understood. Here we show that DHX36, a helicase that unwinds RNA G-quadruplex (rG4) structures, is essential for muscle regeneration by regulating SC expansion. DHX36 (initially named RHAU) is barely expressed at quiescence but is highly induced during SC activation and proliferation. Inducible deletion of Dhx36 in adult SCs causes defective proliferation and muscle regeneration after damage. System-wide mapping in proliferating SCs reveals DHX36 binding predominantly to rG4 structures at various regions of mRNAs, while integrated polysome profiling shows that DHX36 promotes mRNA translation via 5'-untranslated region (UTR) rG4 binding. Furthermore, we demonstrate that DHX36 specifically regulates the translation of Gnai2 mRNA by unwinding its 5' UTR rG4 structures and identify GNAI2 as a downstream effector of DHX36 for SC expansion. Altogether, our findings uncover DHX36 as an indispensable post-transcriptional regulator of SC function and muscle regeneration acting through binding and unwinding rG4 structures at 5' UTR of target mRNAs.


Assuntos
Regiões 5' não Traduzidas , RNA Helicases DEAD-box/metabolismo , Quadruplex G , Músculos/citologia , Regeneração/fisiologia , Células-Tronco/citologia , Animais , Animais Geneticamente Modificados , Células Cultivadas , Modelos Animais de Doenças , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/metabolismo , Regulação da Expressão Gênica , Humanos , Camundongos , Músculos/metabolismo , Mioblastos/metabolismo , Polirribossomos/metabolismo , Biossíntese de Proteínas , RNA Mensageiro/genética , Células-Tronco/metabolismo
19.
Molecules ; 26(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34361773

RESUMO

The thrombin binding aptamer (TBA) is a promising nucleic acid-based anticoagulant. We studied the effects of chemical modifications, such as dendrimer Trebler and NHS carboxy group, on TBA with respect to its structures and thrombin binding affinity. The two dendrimer modifications were incorporated into the TBA at the 5' end and the NHS carboxy group was added into the thymine residues in the thrombin binding site of the TBA G-quadruplex (at T4, T13 and both T4/T13) using solid phase oligonucleotide synthesis. Circular dichroism (CD) spectroscopy confirmed that all of these modified TBA variants fold into a stable G-quadruplex. The binding affinity of TBA variants with thrombin was measured by surface plasmon resonance (SPR). The binding patterns and equilibrium dissociation constants (KD) of the modified TBAs are very similar to that of the native TBA. Molecular dynamics simulations studies indicate that the additional interactions or stability enhancement introduced by the modifications are minimized either by the disruption of TBA-thrombin interactions or destabilization elsewhere in the aptamer, providing a rational explanation for our experimental data. Overall, this study identifies potential positions on the TBA that can be modified without adversely affecting its structure and thrombin binding preference, which could be useful in the design and development of more functional TBA analogues.


Assuntos
Anticoagulantes/síntese química , Aptâmeros de Nucleotídeos/síntese química , Quadruplex G , Oligonucleotídeos/síntese química , Trombina/química , Anticoagulantes/metabolismo , Anticoagulantes/farmacologia , Aptâmeros de Nucleotídeos/metabolismo , Aptâmeros de Nucleotídeos/farmacologia , Sequência de Bases , Sítios de Ligação , Coagulação Sanguínea/efeitos dos fármacos , Dendrímeros/química , Humanos , Cinética , Simulação de Dinâmica Molecular , Conformação de Ácido Nucleico , Oligonucleotídeos/metabolismo , Ligação Proteica , Termodinâmica , Trombina/antagonistas & inibidores , Trombina/metabolismo
20.
J Phys Chem Lett ; 12(33): 8096-8102, 2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34406777

RESUMO

Nucleic acid sequences rich in guanines can organize into noncanonical DNA G-quadruplexes (G4s) of variable size. The design of small molecules stabilizing the structure of G4s is a rapidly growing area for the development of novel anticancer therapeutic strategies and bottom-up nanotechnologies. Among a multitude of binders, porphyrins are very attractive due to their light activation that can make them valuable conformational regulators of G4s. Here, a structure-based strategy, integrating complementary probes, is employed to study the interaction between TMPyP4 porphyrin and a 22-base human telomeric sequence (Tel22) before and after irradiation with blue light. Porphyrin binding is discovered to promote Tel22 dimerization, while light irradiation of the Tel22-TMPyP4 complex controls dimer fraction. Such a change in quaternary structure is found to be strictly correlated with modifications at the secondary structure level, thus providing an unprecedented link between the degree of dimerization and the underlying conformational changes in G4s.


Assuntos
DNA/química , Quadruplex G , Porfirinas/química , Raios X , Dicroísmo Circular , Dimerização , Estrutura Molecular , Espalhamento de Radiação , Telômero
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...