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1.
Proc Natl Acad Sci U S A ; 119(45): e2207402119, 2022 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-36322752

RESUMEN

The intracellular metabolism of organelles, like lysosomes and mitochondria, is highly coordinated spatiotemporally and functionally. The activities of lysosomal enzymes significantly rely on the cytoplasmic temperature, and heat is constantly released by mitochondria as the byproduct of adenosine triphosphate (ATP) generation during active metabolism. Here, we developed temperature-sensitive LysoDots and MitoDots to monitor the in situ thermal dynamics of lysosomes and mitochondria. The design is based on upconversion nanoparticles (UCNPs) with high-density surface modifications to achieve the exceptionally high sensitivity of 2.7% K-1 and low uncertainty of 0.8 K for nanothermometry to be used in living cells. We show the measurement is independent of the ion concentrations and pH values. With Ca2+ ion shock, the temperatures of both lysosomes and mitochondria increased by ∼2 to 4 °C. Intriguingly, with chloroquine (CQ) treatment, the lysosomal temperature was observed to decrease by up to ∼3 °C, while mitochondria remained relatively stable. Lastly, with oxidative phosphorylation inhibitor treatment, we observed an ∼3 to 7 °C temperature increase and a thermal transition from mitochondria to lysosomes. These observations indicate different metabolic pathways and thermal transitions between lysosomes and mitochondria inside HeLa cells. The nanothermometry probes provide a powerful tool for multimodality functional imaging of subcellular organelles and interactions with high spatial, temporal, and thermal dynamics resolutions.


Asunto(s)
Lisosomas , Nanopartículas , Humanos , Temperatura , Células HeLa , Lisosomas/metabolismo , Orgánulos/metabolismo , Mitocondrias/metabolismo
2.
J Nanobiotechnology ; 22(1): 363, 2024 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-38910248

RESUMEN

Fluorescence nanoscopy, also known as super-resolution microscopy, has transcended the conventional resolution barriers and enabled visualization of biological samples at nanometric resolutions. A series of super-resolution techniques have been developed and applied to investigate the molecular distribution, organization, and interactions in blood cells, as well as the underlying mechanisms of blood-cell-associated diseases. In this review, we provide an overview of various fluorescence nanoscopy technologies, outlining their current development stage and the challenges they are facing in terms of functionality and practicality. We specifically explore how these innovations have propelled forward the analysis of thrombocytes (platelets), erythrocytes (red blood cells) and leukocytes (white blood cells), shedding light on the nanoscale arrangement of subcellular components and molecular interactions. We spotlight novel biomarkers uncovered by fluorescence nanoscopy for disease diagnosis, such as thrombocytopathies, malignancies, and infectious diseases. Furthermore, we discuss the technological hurdles and chart out prospective avenues for future research directions. This review aims to underscore the significant contributions of fluorescence nanoscopy to the field of blood cell analysis and disease diagnosis, poised to revolutionize our approach to exploring, understanding, and managing disease at the molecular level.


Asunto(s)
Microscopía Fluorescente , Humanos , Microscopía Fluorescente/métodos , Eritrocitos , Animales , Plaquetas/metabolismo , Células Sanguíneas , Hematología/métodos , Nanotecnología/métodos , Leucocitos/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(26): 15036-15046, 2020 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-32541019

RESUMEN

Mammalian DNA replication is initiated at numerous replication origins, which are clustered into thousands of replication domains (RDs) across the genome. However, it remains unclear whether the replication origins within each RD are activated stochastically or preferentially near certain chromatin features. To understand how DNA replication in single human cells is regulated at the sub-RD level, we directly visualized and quantitatively characterized the spatiotemporal organization, morphology, and in situ epigenetic signatures of individual replication foci (RFi) across S-phase at superresolution using stochastic optical reconstruction microscopy. Importantly, we revealed a hierarchical radial pattern of RFi propagation dynamics that reverses directionality from early to late S-phase and is diminished upon caffeine treatment or CTCF knockdown. Together with simulation and bioinformatic analyses, our findings point to a "CTCF-organized REplication Propagation" (CoREP) model, which suggests a nonrandom selection mechanism for replication activation at the sub-RD level during early S-phase, mediated by CTCF-organized chromatin structures. Collectively, these findings offer critical insights into the key involvement of local epigenetic environment in coordinating DNA replication across the genome and have broad implications for our conceptualization of the role of multiscale chromatin architecture in regulating diverse cell nuclear dynamics in space and time.


Asunto(s)
Factor de Unión a CCCTC/metabolismo , Cromatina/metabolismo , Replicación del ADN , Factor de Unión a CCCTC/genética , Cromatina/genética , Epigenómica , Humanos , Fase S
4.
Nano Lett ; 22(9): 3761-3769, 2022 05 11.
Artículo en Inglés | MEDLINE | ID: mdl-35500253

RESUMEN

Cancer-derived small extracellular vesicles (sEVs) are potential circulating biomarkers in liquid biopsies. However, their small sizes, low abundance, and heterogeneity in molecular makeups pose major technical challenges for detecting and characterizing them quantitatively. Here, we demonstrate a single-sEV enumeration platform using lanthanide-doped upconversion nanoparticles (UCNPs). Taking advantage of the unique optical properties of UCNPs and the background-eliminating property of total internal reflection fluorescence (TIRF) imaging technique, a single-sEV assay recorded a limit of detection 1.8 × 106 EVs/mL, which was nearly 3 orders of magnitude lower than the standard enzyme-linked immunosorbent assay (ELISA). Its specificity was validated by the difference between EpCAM-positive and EpCAM-negative sEVs. The accuracy of the UCNP-based single-sEV assay was benchmarked with immunomagnetic-beads flow cytometry, showing a high correlation (R2> 0.99). The platform is suitable for evaluating the heterogeneous antigen expression of sEV and can be easily adapted for biomarker discoveries and disease diagnosis.


Asunto(s)
Vesículas Extracelulares , Elementos de la Serie de los Lantanoides , Nanopartículas , Neoplasias , Molécula de Adhesión Celular Epitelial , Humanos , Neoplasias/diagnóstico
5.
Cytometry A ; 101(5): 400-410, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-34585823

RESUMEN

Sensitive and quantitative detection of molecular biomarkers is crucial for the early diagnosis of diseases like metabolic syndrome and cancer. Here we present a single-molecule sandwich immunoassay by imaging the number of single nanoparticles to diagnose aggressive prostate cancer. Our assay employed the photo-stable upconversion nanoparticles (UCNPs) as labels to detect the four types of circulating antigens in blood circulation, including glypican-1 (GPC-1), leptin, osteopontin (OPN), and vascular endothelial growth factor (VEGF), as their serum concentrations indicate aggressive prostate cancer. Under a wide-field microscope, a single UCNP doped with thousands of lanthanide ions can emit sufficiently bright anti-Stokes' luminescence to become quantitatively detectable. By counting every single streptavidin-functionalized UCNP which specifically labeled on each sandwich immune complex across multiple fields of views, we achieved the Limit of Detection (LOD) of 0.0123 ng/ml, 0.2711 ng/ml, 0.1238 ng/ml, and 0.0158 ng/ml for GPC-1, leptin, OPN and VEGF, respectively. The serum circulating level of GPC-1, leptin, OPN, and VEGF in a mixture of 10 healthy normal human serum was 25.17 ng/ml, 18.04 ng/ml, 11.34 ng/ml, and 1.55 ng/ml, which was within the assay dynamic detection range for each analyte. Moreover, a 20% increase of GPC-1 and OPN was observed by spiking the normal human serum with recombinant antigens to confirm the accuracy of the assay. We observed no cross-reactivity among the four biomarker analytes, which eliminates the false positives and enhances the detection accuracy. The developed single upconversion nanoparticle-assisted single-molecule assay suggests its potential in clinical usage for prostate cancer detection by monitoring tiny concentration differences in a panel of serum biomarkers.


Asunto(s)
Nanopartículas , Neoplasias de la Próstata , Biomarcadores , Humanos , Leptina , Masculino , Neoplasias de la Próstata/diagnóstico , Factor A de Crecimiento Endotelial Vascular
6.
Eur Biophys J ; 51(2): 135-146, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35286429

RESUMEN

Mechanical stimuli such as tension, compression, and shear stress play critical roles in the physiological functions of red blood cells (RBCs) and their homeostasis, ATP release, and rheological properties. Intracellular calcium (Ca2+) mobilization reflects RBC mechanosensing as they transverse the complex vasculature. Emerging studies have demonstrated the presence of mechanosensitive Ca2+ permeable ion channels and their function has been implicated in the regulation of RBC volume and deformability. However, how these mechanoreceptors trigger Ca2+ influx and subsequent cellular responses are still unclear. Here, we introduce a fluorescence-coupled micropipette aspiration assay to examine RBC mechanosensing at the single-cell level. To achieve a wide range of cell aspirations, we implemented and compared two negative pressure adjusting apparatuses: a homemade water manometer (- 2.94 to 0 mmH2O) and a pneumatic high-speed pressure clamp (- 25 to 0 mmHg). To visualize Ca2+ influx, RBCs were pre-loaded with an intensiometric probe Cal-520 AM, then imaged under a confocal microscope with concurrent bright-field and fluorescent imaging at acquisition rates of 10 frames per second. Remarkably, we observed the related changes in intracellular Ca2+ levels immediately after aspirating individual RBCs in a pressure-dependent manner. The RBC aspirated by the water manometer only displayed 1.1-fold increase in fluorescence intensity, whereas the RBC aspirated by the pneumatic clamp showed up to threefold increase. These results demonstrated the water manometer as a gentle tool for cell manipulation with minimal pre-activation, while the high-speed pneumatic clamp as a much stronger pressure actuator to examine cell mechanosensing directly. Together, this multimodal platform enables us to precisely control aspiration and membrane tension, and subsequently correlate this with intracellular calcium concentration dynamics in a robust and reproducible manner.


Asunto(s)
Calcio , Deformación Eritrocítica , Calcio/metabolismo , Eritrocitos , Canales Iónicos/metabolismo , Transducción de Señal
7.
EMBO Rep ; 21(3): e48385, 2020 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-31984633

RESUMEN

Microtubules derived from the Golgi (Golgi MTs) have been implicated to play critical roles in persistent cell migration, but the underlying mechanisms remain elusive, partially due to the lack of direct observation of Golgi MT-dependent vesicular trafficking. Here, using super-resolution stochastic optical reconstruction microscopy (STORM), we discovered that post-Golgi cargos are more enriched on Golgi MTs and also surprisingly move much faster than on non-Golgi MTs. We found that, compared to non-Golgi MTs, Golgi MTs are morphologically more polarized toward the cell leading edge with significantly fewer inter-MT intersections. In addition, Golgi MTs are more stable and contain fewer lattice repair sites than non-Golgi MTs. Our STORM/live-cell imaging demonstrates that cargos frequently pause at the sites of both MT intersections and MT defects. Furthermore, by optogenetic maneuvering of cell direction, we demonstrate that Golgi MTs are essential for persistent cell migration but not for cells to change direction. Together, our study unveils the role of Golgi MTs in serving as a group of "fast tracks" for anterograde trafficking of post-Golgi cargos.


Asunto(s)
Aparato de Golgi , Microtúbulos , Movimiento Celular
8.
Nano Lett ; 21(4): 1651-1658, 2021 02 24.
Artículo en Inglés | MEDLINE | ID: mdl-33550807

RESUMEN

Temperature dynamics reflect the physiological conditions of cells and organisms. Mitochondria regulate the temperature dynamics in living cells as they oxidize the respiratory substrates and synthesize ATP, with heat being released as a byproduct of active metabolism. Here, we report an upconversion nanoparticle-based thermometer that allows the in situ thermal dynamics monitoring of mitochondria in living cells. We demonstrate that the upconversion nanothermometers can efficiently target mitochondria, and the temperature-responsive feature is independent of probe concentration and medium conditions. The relative sensing sensitivity of 3.2% K-1 in HeLa cells allows us to measure the mitochondrial temperature difference through the stimulations of high glucose, lipid, Ca2+ shock, and the inhibitor of oxidative phosphorylation. Moreover, cells display distinct response time and thermodynamic profiles under different stimulations, which highlight the potential applications of this thermometer to study in situ vital processes related to mitochondrial metabolism pathways and interactions between organelles.


Asunto(s)
Nanopartículas , Células HeLa , Humanos , Termómetros
9.
Nano Lett ; 20(7): 4775-4781, 2020 07 08.
Artículo en Inglés | MEDLINE | ID: mdl-32208705

RESUMEN

Video-rate super-resolution imaging through biological tissue can visualize and track biomolecule interplays and transportations inside cellular organisms. Structured illumination microscopy allows for wide-field super resolution observation of biological samples but is limited by the strong extinction of light by biological tissues, which restricts the imaging depth and degrades its imaging resolution. Here we report a photon upconversion scheme using lanthanide-doped nanoparticles for wide-field super-resolution imaging through the biological transparent window, featured by near-infrared and low-irradiance nonlinear structured illumination. We demonstrate that the 976 nm excitation and 800 nm upconverted emission can mitigate the aberration. We found that the nonlinear response of upconversion emissions from single nanoparticles can effectively generate the required high spatial frequency components in the Fourier domain. These strategies lead to a new modality in microscopy with a resolution below 131 nm, 1/7th of the excitation wavelength, and an imaging rate of 1 Hz.

10.
Nat Mater ; 18(7): 760-769, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-30911119

RESUMEN

Integrins are membrane receptors that mediate cell adhesion and mechanosensing. The structure-function relationship of integrins remains incompletely understood, despite the extensive studies carried out because of its importance to basic cell biology and translational medicine. Using a fluorescence dual biomembrane force probe, microfluidics and cone-and-plate rheometry, we applied precisely controlled mechanical stimulations to platelets and identified an intermediate state of integrin αIIbß3 that is characterized by an ectodomain conformation, ligand affinity and bond lifetimes that are all intermediate between the well-known inactive and active states. This intermediate state is induced by ligand engagement of glycoprotein (GP) Ibα via a mechanosignalling pathway and potentiates the outside-in mechanosignalling of αIIbß3 for further transition to the active state during integrin mechanical affinity maturation. Our work reveals distinct αIIbß3 state transitions in response to biomechanical and biochemical stimuli, and identifies a role for the αIIbß3 intermediate state in promoting biomechanical platelet aggregation.


Asunto(s)
Fenómenos Mecánicos , Agregación Plaquetaria , Complejo GPIIb-IIIa de Glicoproteína Plaquetaria/metabolismo , Fenómenos Biomecánicos , Humanos , Ligandos , Transducción de Señal
11.
Proc Natl Acad Sci U S A ; 113(40): E5812-E5820, 2016 10 04.
Artículo en Inglés | MEDLINE | ID: mdl-27647889

RESUMEN

The motor function of vertebrate myosin-5a is inhibited by its tail in a Ca2+-dependent manner. We previously demonstrated that the calmodulin (CaM) bound to the first isoleucine-glutamine (IQ) motif (IQ1) of myosin-5a is responsible for the Ca2+-dependent regulation of myosin-5a. We have solved the crystal structure of a truncated myosin-5a containing the motor domain and IQ1 (MD-IQ1) complexed with Ca2+-bound CaM (Ca2+-CaM) at 2.5-Å resolution. Compared with the structure of the MD-IQ1 complexed with essential light chain (an equivalent of apo-CaM), MD-IQ1/Ca2+-CaM displays large conformational differences in IQ1/CaM and little difference in the motor domain. In the MD-IQ1/Ca2+-CaM structure, the N-lobe and the C-lobe of Ca2+-CaM adopt an open conformation and grip the C-terminal and the N-terminal portions of the IQ1, respectively. Remarkably, the interlobe linker of CaM in IQ1/Ca2+-CaM is in a position opposite that in IQ1/apo-CaM, suggesting that CaM flip-flops relative to the IQ1 during the Ca2+ transition. We demonstrated that CaM continuously associates with the IQ1 during the Ca2+ transition and that the binding of CaM to IQ1 increases Ca2+ affinity and substantially changes the kinetics of the Ca2+ transition, suggesting that the IQ1/CaM complex functions as an intact Ca2+ sensor responding to distinct calcium signals.


Asunto(s)
Calcio/metabolismo , Calmodulina/metabolismo , Miosina Tipo V/química , Miosina Tipo V/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Calmodulina/química , Calorimetría , Cristalografía por Rayos X , Cinética , Ratones , Modelos Biológicos , Dominios Proteicos , Conejos , Espectrometría de Fluorescencia , Homología Estructural de Proteína , Triptófano/metabolismo
12.
Adv Mater ; 36(2): e2308844, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37972577

RESUMEN

Optical multiplexing for nanoscale object recognition is of great significance within the intricate domains of biology, medicine, anti-counterfeiting, and microscopic imaging. Traditionally, the multiplexing dimensions of nanoscopy are limited to emission intensity, color, lifetime, and polarization. Here, a novel dimension, optical nonlinearity, is proposed for super-resolved multiplexing microscopy. This optical nonlinearity is attributable to the energy transitions between multiple energy levels of the doped lanthanide ions in upconversion nanoparticles (UCNPs), resulting in unique optical fingerprints for UCNPs with different compositions. A vortex beam is applied to transport the optical nonlinearity onto the imaging point-spread function (PSF), creating a robust super-resolved multiplexing imaging strategy for differentiating UCNPs with distinctive optical nonlinearities. The composition information of the nanoparticles can be retrieved with variations of the corresponding PSF in the obtained image. Four channels multiplexing super-resolved imaging with a single scanning, applying emission color and nonlinearity of two orthogonal imaging dimensions with a spatial resolution higher than 150 nm (1/6.5λ), are demonstrated. This work provides a new and orthogonal dimension - optical nonlinearity - to existing multiplexing dimensions, which shows great potential in bioimaging, anti-counterfeiting, microarray assays, deep tissue multiplexing detection, and high-density data storage.

13.
Nat Commun ; 15(1): 5521, 2024 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-38951553

RESUMEN

The microgeometry of the cellular microenvironment profoundly impacts cellular behaviors, yet the link between it and the ubiquitously expressed mechanosensitive ion channel PIEZO1 remains unclear. Herein, we describe a fluorescent micropipette aspiration assay that allows for simultaneous visualization of intracellular calcium dynamics and cytoskeletal architecture in real-time, under varied micropipette geometries. By integrating elastic shell finite element analysis with fluorescent lifetime imaging microscopy and employing PIEZO1-specific transgenic red blood cells and HEK cell lines, we demonstrate a direct correlation between the microscale geometry of aspiration and PIEZO1-mediated calcium signaling. We reveal that increased micropipette tip angles and physical constrictions lead to a significant reorganization of F-actin, accumulation at the aspirated cell neck, and subsequently amplify the tension stress at the dome of the cell to induce more PIEZO1's activity. Disruption of the F-actin network or inhibition of its mobility leads to a notable decline in PIEZO1 mediated calcium influx, underscoring its critical role in cellular mechanosensing amidst geometrical constraints.


Asunto(s)
Actinas , Calcio , Citoesqueleto , Canales Iónicos , Mecanotransducción Celular , Humanos , Canales Iónicos/metabolismo , Actinas/metabolismo , Células HEK293 , Citoesqueleto/metabolismo , Calcio/metabolismo , Señalización del Calcio/fisiología , Análisis de Elementos Finitos , Animales , Microscopía Fluorescente/métodos
14.
Methods Mol Biol ; 2615: 79-88, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36807785

RESUMEN

Mitochondrial DNA (mtDNA) encodes a variety of rRNAs, tRNAs, and respiratory chain complex proteins. The integrity of mtDNA supports the mitochondrial functions and plays an essential role in numerous physiological and pathological processes. Mutations in mtDNA cause metabolic diseases and aging. The mtDNA within the human cells are packaged into hundreds of nucleoids within the mitochondrial matrix. Knowledge of how the nucleoids are dynamically distributed and organized within mitochondria is key to understanding mtDNA structure and functions. Therefore, visualizing the distribution and dynamics of mtDNA within mitochondria is a powerful approach to gain insights into the regulation of mtDNA replication and transcription. In this chapter, we describe the methods of observing mtDNA and its replication with fluorescence microscopy in both fixed and live cells using different labeling strategies.


Asunto(s)
ADN Mitocondrial , Proteínas Mitocondriales , Humanos , ADN Mitocondrial/genética , Proteínas Mitocondriales/metabolismo , Mitocondrias/metabolismo , Replicación del ADN , Membranas Mitocondriales/metabolismo , Dinámicas Mitocondriales
15.
Sci Signal ; 16(809): eadf8299, 2023 10 31.
Artículo en Inglés | MEDLINE | ID: mdl-37906629

RESUMEN

Mechanical cues sensed by integrins induce cells to produce proteases to remodel the extracellular matrix. Excessive protease production occurs in many degenerative diseases, including osteoarthritis, in which articular cartilage degradation is associated with the genesis of matrix protein fragments that can activate integrins. We investigated the mechanisms by which integrin signals may promote protease production in response to matrix changes in osteoarthritis. Using a fragment of the matrix protein fibronectin (FN) to activate the α5ß1 integrin in primary human chondrocytes, we found that endocytosis of the integrin and FN fragment complex drove the production of the matrix metalloproteinase MMP-13. Activation of α5ß1 by the FN fragment, but not by intact FN, was accompanied by reactive oxygen species (ROS) production initially at the cell surface, then in early endosomes. These ROS-producing endosomes (called redoxosomes) contained the integrin-FN fragment complex, the ROS-producing enzyme NADPH oxidase 2 (NOX2), and SRC, a redox-regulated kinase that promotes MMP-13 production. In contrast, intact FN was endocytosed and trafficked to recycling endosomes without inducing ROS production. Articular cartilage from patients with osteoarthritis showed increased amounts of SRC and the NOX2 complex component p67phox. Furthermore, we observed enhanced localization of SRC and p67phox at early endosomes, suggesting that redoxosomes could transmit and sustain integrin signaling in response to matrix damage. This signaling mechanism not only amplifies the production of matrix-degrading proteases but also establishes a self-perpetuating cycle that contributes to the ongoing degradation of cartilage matrix in osteoarthritis.


Asunto(s)
Cartílago Articular , Osteoartritis , Humanos , Condrocitos , Metaloproteinasa 13 de la Matriz/genética , Metaloproteinasa 13 de la Matriz/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Integrina alfa5beta1/genética , Integrina alfa5beta1/metabolismo , Integrinas/genética , Integrinas/metabolismo , Cartílago Articular/metabolismo , Oxidación-Reducción , Endosomas/metabolismo
16.
Methods Mol Biol ; 2276: 333-341, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34060053

RESUMEN

Mitochondria change their morphologies from small isolated vesicles to large continuous networks across the cell cycles. The mitochondrial network formation (MNF) plays an important role in maintaining mitochondrial DNA integrity and interchanging mitochondrial materials. The disruption of the mitochondrial network affects mitochondrial functions, such as ATP production, integration of metabolism, calcium homeostasis, and regulation of apoptosis, leading to the abnormal development and several human diseases including neurodegenerative disease. In this unit, we describe the method of studying MNF, which is driven by microtubule-dependent motor protein, by in vivo imaging and single-molecule in vitro reconstitution assays.


Asunto(s)
ADN Mitocondrial/metabolismo , Microtúbulos/metabolismo , Mitocondrias/metabolismo , Animales , Células Cultivadas , Técnicas In Vitro/métodos , Cinesinas/metabolismo , Potencial de la Membrana Mitocondrial , Ratones , Microscopía Fluorescente/métodos , Dinámicas Mitocondriales , Ratas
17.
Genome Biol ; 22(1): 206, 2021 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-34253239

RESUMEN

BACKGROUND: Metazoan cells only utilize a small subset of the potential DNA replication origins to duplicate the whole genome in each cell cycle. Origin choice is linked to cell growth, differentiation, and replication stress. Although various genetic and epigenetic signatures have been linked to the replication efficiency of origins, there is no consensus on how the selection of origins is determined. RESULTS: We apply dual-color stochastic optical reconstruction microscopy (STORM) super-resolution imaging to map the spatial distribution of origins within individual topologically associating domains (TADs). We find that multiple replication origins initiate separately at the spatial boundary of a TAD at the beginning of the S phase. Intriguingly, while both high-efficiency and low-efficiency origins are distributed homogeneously in the TAD during the G1 phase, high-efficiency origins relocate to the TAD periphery before the S phase. Origin relocalization is dependent on both transcription and CTCF-mediated chromatin structure. Further, we observe that the replication machinery protein PCNA forms immobile clusters around TADs at the G1/S transition, explaining why origins at the TAD periphery are preferentially fired. CONCLUSION: Our work reveals a new origin selection mechanism that the replication efficiency of origins is determined by their physical distribution in the chromatin domain, which undergoes a transcription-dependent structural re-organization process. Our model explains the complex links between replication origin efficiency and many genetic and epigenetic signatures that mark active transcription. The coordination between DNA replication, transcription, and chromatin organization inside individual TADs also provides new insights into the biological functions of sub-domain chromatin structural dynamics.


Asunto(s)
Cromatina/química , Replicación del ADN , Puntos de Control de la Fase G1 del Ciclo Celular/genética , Antígeno Nuclear de Célula en Proliferación/genética , Origen de Réplica , Transcripción Genética , Factor de Unión a CCCTC/antagonistas & inhibidores , Factor de Unión a CCCTC/genética , Factor de Unión a CCCTC/metabolismo , Proteínas de Ciclo Celular/antagonistas & inhibidores , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular , Línea Celular Tumoral , Ensamble y Desensamble de Cromatina , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Expresión Génica , Células HeLa , Humanos , Hibridación Fluorescente in Situ , Imagen Óptica , Osteoblastos/citología , Osteoblastos/metabolismo , Antígeno Nuclear de Célula en Proliferación/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Epitelio Pigmentado de la Retina/citología , Epitelio Pigmentado de la Retina/metabolismo
18.
J Control Release ; 337: 629-644, 2021 09 10.
Artículo en Inglés | MEDLINE | ID: mdl-34375688

RESUMEN

Nuclear factor κB (NFκB) is a unique protein complex that plays a major role in lung inflammation and respiratory dysfunction. The NFκB signaling pathway, therefore becomes an avenue for the development of potential pharmacological interventions, especially in situations where chronic inflammation is often constitutively active and plays a key role in the pathogenesis and progression of the disease. NFκB decoy oligodeoxynucleotides (ODNs) are double-stranded and carry NFκB binding sequences. They prevent the formation of NFκB-mediated inflammatory cytokines and thus have been employed in the treatment of a variety of chronic inflammatory diseases. However, the systemic administration of naked decoy ODNs restricts their therapeutic effectiveness because of their poor pharmacokinetic profile, instability, degradation by cellular enzymes and their low cellular uptake. Both structural modification and nanotechnology have shown promising results in enhancing the pharmacokinetic profiles of potent therapeutic substances and have also shown great potential in the treatment of respiratory diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. In this review, we examine the contribution of NFκB activation in respiratory diseases and recent advancements in the therapeutic use of decoy ODNs. In addition, we also highlight the limitations and challenges in use of decoy ODNs as therapeutic molecules, cellular uptake of decoy ODNs, and the current need for novel delivery systems to provide efficient delivery of decoy ODNs. Furthermore, this review provides a common platform for discussion on the existence of decoy ODNs, as well as outlining perspectives on the latest generation of delivery systems that encapsulate decoy ODNs and target NFκB in respiratory diseases.


Asunto(s)
FN-kappa B , Neumonía , Citocinas , Humanos , Oligodesoxirribonucleótidos
19.
Front Neurosci ; 14: 642, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32655360

RESUMEN

Psychosis has been considered a disorder of impaired neuronal connectivity. Evidence for excessive formation of dopamine D2 receptor (D2R) - disrupted in schizophrenia 1 (DISC1) complexes has led to a new perspective on molecular mechanisms involved in psychotic symptoms. Here, we investigated how excessive D2R-DISC1 complex formation induced by D2R agonist quinpirole affects neurite growth and dendritic spines in striatal neurons. Fluorescence resonance energy transfer (FRET), stochastic optical reconstruction microscopy (STORM), and cell penetrating-peptide delivery were used to study the cultured striatal neurons from mouse pups. Using these striatal neurons, our study showed that: (1) D2R interacted with DISC1 in dendritic spines, neurites and soma of cultured striatal neurons; (2) D2R and DISC1 complex accumulated in clusters in dendritic spines of striatal neurons and the number of the complex were reduced after application of TAT-D2pep; (3) uncoupling D2R-DISC1 complexes by TAT-D2pep protected neuronal morphology and dendritic spines; and (4) TAT-D2pep prevented neurite and dendritic spine loss, which was associated with restoration of expression levels of synaptophysin and PSD-95. In addition, we found that Neuropeptide Y (NPY) and GSK3ß were involved in the protective effects of TAT-D2pep on the neurite spines of striatal spiny projection neurons. Thus, our results may offer a new strategy for precisely treating neurite spine deficits associated with schizophrenia.

20.
Nat Commun ; 11(1): 4471, 2020 09 08.
Artículo en Inglés | MEDLINE | ID: mdl-32901010

RESUMEN

A human cell contains hundreds to thousands of mitochondrial DNA (mtDNA) packaged into nucleoids. Currently, the segregation and allocation of nucleoids are thought to be passively determined by mitochondrial fusion and division. Here we provide evidence, using live-cell super-resolution imaging, that nucleoids can be actively transported via KIF5B-driven mitochondrial dynamic tubulation (MDT) activities that predominantly occur at the ER-mitochondria contact sites (EMCS). We further demonstrate that a mitochondrial inner membrane protein complex MICOS links nucleoids to Miro1, a KIF5B receptor on mitochondria, at the EMCS. We show that such active transportation is a mechanism essential for the proper distribution of nucleoids in the peripheral zone of the cell. Together, our work identifies an active transportation mechanism of nucleoids, with EMCS serving as a key platform for the interplay of nucleoids, MICOS, Miro1, and KIF5B to coordinate nucleoids segregation and transportation.


Asunto(s)
ADN Mitocondrial/metabolismo , Retículo Endoplásmico/metabolismo , Mitocondrias/metabolismo , Dinámicas Mitocondriales/fisiología , Animales , Transporte Biológico Activo , Células COS , Células Cultivadas , Chlorocebus aethiops , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Células HEK293 , Humanos , Cinesinas/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Ratones , Membranas Mitocondriales/metabolismo , Proteínas del Complejo de Importación de Proteínas Precursoras Mitocondriales , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Modelos Biológicos , Ratas , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transfección , Proteínas de Unión al GTP rho/metabolismo
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