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1.
Commun Biol ; 7(1): 530, 2024 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-38704457

RESUMO

Cell stiffness is regulated by dynamic interaction between ras-related C3 botulinum toxin substrate 1 (Rac1) and p21 protein-activated kinase 1 (PAK1) proteins, besides other biochemical and molecular regulators. In this study, we investigated how the Placental Growth Factor (PlGF) changes endometrial mechanics by modifying the actin cytoskeleton at the maternal interface. We explored the global effects of PlGF in endometrial stromal cells (EnSCs) using the concerted approach of proteomics, atomic force microscopy (AFM), and electrical impedance spectroscopy (EIS). Proteomic analysis shows PlGF upregulated RhoGTPases activating proteins and extracellular matrix organization-associated proteins in EnSCs. Rac1 and PAK1 transcript levels, activity, and actin polymerization were significantly increased with PlGF treatment. AFM further revealed an increase in cell stiffness with PlGF treatment. The additive effect of PlGF on actin polymerization was suppressed with siRNA-mediated inhibition of Rac1, PAK1, and WAVE2. Interestingly, the increase in cell stiffness by PlGF treatment was pharmacologically reversed with pravastatin, resulting in improved trophoblast cell invasion. Taken together, aberrant PlGF levels in the endometrium can contribute to an altered pre-pregnancy maternal microenvironment and offer a unifying explanation for the pathological changes observed in conditions such as pre-eclampsia (PE).


Assuntos
Endométrio , Fator de Crescimento Placentário , Pré-Eclâmpsia , Transdução de Sinais , Proteínas rac1 de Ligação ao GTP , Feminino , Proteínas rac1 de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP/genética , Humanos , Pré-Eclâmpsia/metabolismo , Gravidez , Endométrio/metabolismo , Endométrio/patologia , Fator de Crescimento Placentário/metabolismo , Fator de Crescimento Placentário/genética , Células Estromais/metabolismo , Quinases Ativadas por p21/metabolismo , Quinases Ativadas por p21/genética , Microscopia de Força Atômica
2.
Yakugaku Zasshi ; 144(5): 511-519, 2024.
Artigo em Japonês | MEDLINE | ID: mdl-38692926

RESUMO

Nanoparticles, including liposomes and lipid nanoparticles, have garnered global attention due to their potential applications in pharmaceuticals, vaccines, and gene therapies. These particles enable targeted delivery of new drug modalities such as highly active small molecules and nucleic acids. However, for widespread use of nanoparticle-based formulations, it is crucial to comprehensively analyze their characteristics to ensure both efficacy and safety, as well as enable consistent production. In this context, this review focuses on our research using atomic force microscopy (AFM) to study liposomes and lipid nanoparticles. Our work significantly contributes to the capability of AFM to measure various types of liposomes in an aqueous medium, providing valuable insights into the mechanical properties of these nanoparticles. We discuss the applications of this AFM technique in assessing the quality of nanoparticle-based pharmaceuticals and developing membrane-active peptides.


Assuntos
Lipossomos , Microscopia de Força Atômica , Nanopartículas , Microscopia de Força Atômica/métodos , Lipídeos/química , Sistemas de Liberação de Medicamentos , Sistemas de Liberação de Fármacos por Nanopartículas/química , Peptídeos/química
3.
Biochem Biophys Res Commun ; 712-713: 149938, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38640739

RESUMO

Polymerization of nucleotides under prebiotic conditions simulating the early Earth has been extensively studied. Several independent methods have been used to verify that RNA-like polymers can be produced by hot wet-dry cycling of nucleotides. However, it has not been shown that these RNA-like polymers are similar to biological RNA with 3'-5' phosphodiester bonds. In the results described here, RNA-like polymers were generated from 5'-monophosphate nucleosides AMP and UMP. To confirm that the polymers resemble biological RNA, ribonuclease A should catalyze hydrolysis of the 3'-5' phosphodiester bonds between pyrimidine nucleotides to each other or to purine nucleotides, but not purine-purine nucleotide bonds. Here we show AFM images of specific polymers produced by hot wet-dry cycling of AMP, UMP and AMP/UMP (1:1) solutions on mica surfaces, before and after exposure to ribonuclease A. AMP polymers were unaffected by ribonuclease A but UMP polymers disappeared. This indicates that a major fraction of the bonds in the UMP polymers is indeed 3'-5' phosphodiester bonds. Some of the polymers generated from the AMP/UMP mixture also showed clear signs of cleavage. Because ribonuclease A recognizes the ester bonds in the polymers, we show for the first time that these prebiotically produced polymers are in fact similar to biological RNA but are likely to be linked by a mixture of 3'-5' and 2'-5' phosphodiester bonds.


Assuntos
RNA , Ribonuclease Pancreático , RNA/química , RNA/metabolismo , Ribonuclease Pancreático/química , Ribonuclease Pancreático/metabolismo , Uridina Monofosfato/química , Uridina Monofosfato/metabolismo , Microscopia de Força Atômica , Temperatura Alta , Polímeros/química , Monofosfato de Adenosina/química , Monofosfato de Adenosina/metabolismo , Hidrólise , Polimerização
4.
Nanotheranostics ; 8(3): 330-343, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38577323

RESUMO

Atomic Force Microscopy (AFM) is a very flexible method that can create topographical images from a range of materials and image surfaces. Significantly, AFM has emerged as an invaluable tool for dissecting the morphology and biochemical aspects of body cells and tissues. The high-resolution imaging capabilities of AFM enable researchers to discern alterations in cell morphology and understand the underlying mechanisms of diseases. It contributes to understanding disease etiology and progression. In the context of this review, our focus will be directed towards elucidating the pivotal role of AFM in analysis of blood related disorders. Through detailed comparisons with normal cells, we delve into the alterations in size, shape, and surface characteristics induced by conditions such as cancer, diabetes, anaemia, and infections caused by pathogens. In essence, various work described in this article highlights to bridge the gap between traditional microscopy and in-depth analysis of blood-related pathologies, which in turn offers valuable perspectives for both research and clinical applications in the field.


Assuntos
Doenças Hematológicas , Microscopia de Força Atômica , Microscopia de Força Atômica/métodos , Doenças Hematológicas/diagnóstico por imagem , Humanos
5.
J Colloid Interface Sci ; 668: 293-302, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38678885

RESUMO

Understanding the cytotoxicity of fluorescent carbon dots (CDs) is crucial for their applications, and various biochemical assays have been used to study the effects of CDs on cells. Knowledge on the effects of CDs from a biophysical perspective is integral to the recognition of their cytotoxicity, however the related information is very limited. Here, we report that atomic force microscopy (AFM) can be used as an effective tool for studying the effects of CDs on cells from the biophysical perspective. We achieve this by integrating AFM-based nanomechanics with AFM-based imaging. We demonstrate the performance of this method by measuring the influence of CDs on living human neuroblastoma (SH-SY5Y) cells at the single-cell level. We find that high-dose CDs can mechanically induce elevated normalized hysteresis (energy dissipation during the cell deformation) and structurally impair actin skeleton. The nanomechanical change highly correlates with the alteration of actin filaments, indicating that CDs-induced changes in SH-SY5Y cells are revealed in-depth from the AFM-based biophysical aspect. We validate the reliability of the biophysical observations using conventional biological methods including cell viability test, fluorescent microscopy, and western blot assay. Our work contributes new and significant information on the cytotoxicity of CDs from the biophysical perspective.


Assuntos
Carbono , Sobrevivência Celular , Microscopia de Força Atômica , Pontos Quânticos , Humanos , Carbono/química , Pontos Quânticos/química , Sobrevivência Celular/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/citologia , Neurônios/metabolismo , Linhagem Celular Tumoral , Tamanho da Partícula , Propriedades de Superfície , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/efeitos dos fármacos , Actinas/metabolismo , Actinas/química
6.
Biochem Biophys Res Commun ; 715: 150008, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38685186

RESUMO

In the last decade, much attention was given to the study of physiological amyloid fibrils. These structures include A-bodies, which are the nucleolar fibrillar formations that appear in the response to acidosis and heat shock, and disassemble after the end of stress. One of the proteins involved in the biogenesis of A-bodies, regardless of the type of stress, is Von-Hippel Lindau protein (VHL). Known also as a tumor suppressor, VHL is capable to form amyloid fibrils both in vitro and in vivo in response to the environment acidification. As with most amyloidogenic proteins fusion with various tags is used to increase the solubility of VHL. Here, we first performed AFM-study of fibrils formed by VHL protein and by VHL fused with GST-tag (GST-VHL) at acidic conditions. It was shown that formed by full-length VHL fibrils are short heterogenic structures with persistent length of 2400 nm and average contour length of 409 nm. GST-tag catalyzes VHL amyloid fibril formation, superimpose chirality, increases length and level of hierarchy, but decreases rigidity of amyloid fibrils. The obtained data indicate that tagging can significantly affect the fibrillogenesis of the target protein.


Assuntos
Amiloide , Glutationa Transferase , Proteína Supressora de Tumor Von Hippel-Lindau , Amiloide/metabolismo , Amiloide/química , Glutationa Transferase/metabolismo , Glutationa Transferase/química , Humanos , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/química , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Microscopia de Força Atômica
7.
Analyst ; 149(7): 2122-2130, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38436119

RESUMO

Sensitive mapping of drugs and drug delivery systems is pivotal for the understanding and improvement of treatment options. Since labeling alters the physicochemical and potentially the pharmacological properties of the molecule of interest, its label-free detection by photothermal expansion is investigated. We report on a proof-of-concept study to map the cetuximab distribution by atomic-force microscopy-based infrared spectroscopy (AFM-IR). The monoclonal antibody cetuximab was applied to a human tumor oral mucosa model, consisting of a tumor epithelium on a lamina propria equivalent. Hyperspectral imaging in the wavenumber regime between 903 cm-1 and 1312 cm-1 and a probing distance between the data points down to 10 × 10 nm are used for determining the local drug distribution. The local distinction of cetuximab from the tissue background is gained by linear combination modeling making use of reference spectra of the drug and untreated models. The results from this approach are compared to principal component analyses, yielding comparable results. Even single molecule detection appears feasible. The results indicate that cetuximab penetrates the cytosol of tumor cells but does not bind to structures in the cell membrane. In conclusion, AFM-IR mapping of cetuximab proved to sensitively determine drug concentrations at an unprecedented spatial resolution without the need for drug labeling.


Assuntos
Mucosa Bucal , Neoplasias , Humanos , Cetuximab , Microscopia de Força Atômica/métodos , Anticorpos Monoclonais , Análise Espectral , Espectrofotometria Infravermelho/métodos
8.
J Pharm Biomed Anal ; 243: 116107, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38489959

RESUMO

Hepatocellular carcinoma (HCC) is a highly prevalent cancer with a significant impact on human health. Curcumin, a natural compound, induces cytoskeletal changes in liver cancer cells and modifies the distribution of lipids, proteins, and polysaccharides on plasma membranes, affecting their mechanical and electrical properties. In this study, we used nanomechanical indentation techniques and Kelvin probe force microscopy (KPFM) based on atomic force microscopy (AFM) to investigate the changes in surface nanomechanical and electrical properties of nuclear and cytoplasmic regions of HepG2 cells in response to increasing curcumin concentrations. CCK-8 assays and flow cytometry results demonstrated time- and concentration-dependent inhibition of HepG2 cell proliferation by curcumin. Increasing curcumin concentration led to an initial increase and then decrease in the mechanical properties of nuclear and cytoplasmic regions of HepG2 cells, represented by the Young's modulus (E), as observed through nanoindentation. KPFM measurements indicated decreasing trends in both cell surface potential and height. Fluorescence microscopy results indicated a positive correlation between curcumin concentration and phosphatidylserine translocation from the inner to the outer membrane, which influenced the electrical properties of HepG2 cells. This study provides valuable insights into curcumin's mechanisms against cancer cells and aids nanoscale evaluation of therapeutic efficacy and drug screening.


Assuntos
Carcinoma Hepatocelular , Curcumina , Neoplasias Hepáticas , Humanos , Microscopia de Força Atômica/métodos , Curcumina/farmacologia , Células Hep G2 , Carcinoma Hepatocelular/tratamento farmacológico , Neoplasias Hepáticas/tratamento farmacológico
9.
Int J Mol Sci ; 25(5)2024 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-38474280

RESUMO

Over the past decade, long non-coding RNAs (lncRNAs) have been recognized as key players in gene regulation, influencing genome organization and expression. The locus-specific binding of these non-coding RNAs (ncRNAs) to DNA involves either a non-covalent interaction with DNA-bound proteins or a direct sequence-specific interaction through the formation of RNA:DNA triplexes. In an effort to develop a novel strategy for characterizing a triple-helix formation, we employed atomic force microscopy (AFM) to visualize and study a regulatory RNA:DNA triplex formed between the Khps1 lncRNA and the enhancer of the proto-oncogene SPHK1. The analysis demonstrates the successful formation of RNA:DNA triplexes under various conditions of pH and temperature, indicating the effectiveness of the AFM strategy. Despite challenges in discriminating between the triple-helix and R-loop configurations, this approach opens new perspectives for investigating the role of lncRNAs in gene regulation at the single-molecule level.


Assuntos
RNA Longo não Codificante , Sequência de Bases , Microscopia de Força Atômica , RNA Longo não Codificante/genética , Conformação de Ácido Nucleico , DNA/química
10.
Langmuir ; 40(14): 7733-7746, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38538620

RESUMO

The mechanism of ethanol-induced fibrillation of ß-lactoglobulin (ß-lg) in the acidic aqueous solution upon heating was investigated using various techniques, mainly thioflavin T fluorescence, atomic force microscopy, nonreducing electrophoresis, mass spectrometry, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy. The results showed that fibrillation occurred with a heating time increase, but high ethanol content slowed down the process. At a low ethanol volume fraction, peptides existed after heating for 2 h, with long and straight fibrils formed after 4-6 h, while at a high ethanol volume fraction, the proteins aggregated with very few peptides appeared at the early stage of heating, and short and curved fibrils formed after heating for 8 h. Ethanol weakened the hydrophobic interactions between proteins in the aqueous solution; therefore the latter could not completely balance the electrostatic repulsion, and thus suppressing the fibrillation process. It is believed that the fibrillation of ß-lg in the acidic solution upon heating is mainly dominated by the polypeptide model; however, ethanol inhibited the hydrolysis of proteins, and the self-assembly mechanism changed to the monomer model.


Assuntos
Lactoglobulinas , Água , Solventes/química , Lactoglobulinas/química , Peptídeos , Etanol , Espectroscopia de Infravermelho com Transformada de Fourier , Microscopia de Força Atômica , Dicroísmo Circular
11.
STAR Protoc ; 5(1): 102873, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38427566

RESUMO

Here, we present a protocol to deliver nanoliter volumes of Toll-like receptor (TLR) agonist onto a culture of nuclear factor κB (NF-κB) reporter macrophages using fluidic force microscopy and a micron-scale probe. We describe steps for quantifying the dose of agonist by modeling their diffusion with experimental inputs. We then detail procedures for quantifying and categorizing macrophage responses to individual and varied doses and combining agonist concentration and macrophage response to analyze the NF-κB response to localized TLR stimulation. For complete details on the use and execution of this protocol, please refer to Mulder et al. (2024).1.


Assuntos
NF-kappa B , Receptores Toll-Like , NF-kappa B/fisiologia , Microscopia de Força Atômica , Receptor 4 Toll-Like , Macrófagos
12.
Langmuir ; 40(11): 5651-5662, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38437623

RESUMO

Deviations from the normal physicochemical and functional properties of pulmonary surfactants are associated with the incidence of lung injury and other respiratory disorders. This study aims to evaluate the alteration of the 2D molecular organization and morphology of pulmonary surfactant model membranes by the electronic cigarette additives α-tocopherol (vitamin E) and α-tocopherol acetate (vitamin E acetate), which have been associated with lung injury, termed e-cigarette or vaping-use-associated lung injury (EVALI). The model membranes used contained a 7:3 molar ratio of DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and POPG (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol) to which α-tocopherol and α-tocopherol acetate were added to form mixtures of up to 20 mol % additive. The properties of the neat tocopherol additives and DPPC/POPG (7:3) mixtures with increasing molar proportions of additive were evaluated by surface pressure-area isotherms, excess area calculations, Brewster angle microscopy, grazing incidence X-ray diffraction, X-ray reflectivity, and atomic force microscopy. The addition of either additive alters the essential phase balance of the model pulmonary surfactant membrane by generating a greater proportion of the fluid phase. Despite this net fluidization, both tocopherol additives have space-filling effects on the liquid-expanded and condensed phases, yielding negative excess areas in the liquid-expanded phase and reduced tilt angles in the condensed phase. Both tocopherol additives alter the stability of the fluid phase, pushing the eventual collapse of this phase to higher surface pressures than the model membrane in the absence of an additive.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina , Lesão Pulmonar , Surfactantes Pulmonares , Vaping , Humanos , alfa-Tocoferol/química , Vitamina E , Surfactantes Pulmonares/química , Microscopia de Força Atômica , Pulmão , Tensoativos , Acetatos
13.
Nat Protoc ; 19(5): 1498-1528, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38429517

RESUMO

Mammalian cells sense and react to the mechanics of their immediate microenvironment. Therefore, the characterization of the biomechanical properties of tissues with high spatial resolution provides valuable insights into a broad variety of developmental, homeostatic and pathological processes within living organisms. The biomechanical properties of the basement membrane (BM), an extracellular matrix (ECM) substructure measuring only ∼100-400 nm across, are, among other things, pivotal to tumor progression and metastasis formation. Although the precise assignment of the Young's modulus E of such a thin ECM substructure especially in between two cell layers is still challenging, biomechanical data of the BM can provide information of eminent diagnostic potential. Here we present a detailed protocol to quantify the elastic modulus of the BM in murine and human lung tissue, which is one of the major organs prone to metastasis. This protocol describes a streamlined workflow to determine the Young's modulus E of the BM between the endothelial and epithelial cell layers shaping the alveolar wall in lung tissues using atomic force microscopy (AFM). Our step-by-step protocol provides instructions for murine and human lung tissue extraction, inflation of these tissues with cryogenic cutting medium, freezing and cryosectioning of the tissue samples, and AFM force-map recording. In addition, it guides the reader through a semi-automatic data analysis procedure to identify the pulmonary BM and extract its Young's modulus E using an in-house tailored user-friendly AFM data analysis software, the Center for Applied Tissue Engineering and Regenerative Medicine processing toolbox, which enables automatic loading of the recorded force maps, conversion of the force versus piezo-extension curves to force versus indentation curves, calculation of Young's moduli and generation of Young's modulus maps, where the pulmonary BM can be identified using a semi-automatic spatial filtering tool. The entire protocol takes 1-2 d.


Assuntos
Membrana Basal , Módulo de Elasticidade , Pulmão , Microscopia de Força Atômica , Animais , Microscopia de Força Atômica/métodos , Camundongos , Humanos , Pulmão/citologia , Fenômenos Biomecânicos
14.
Medicina (Kaunas) ; 60(2)2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38399584

RESUMO

Background and Objectives: Atomic force microscopy (AFM) as a type of scanning microscopy (SPM), which has a resolution of fractions of a nanometer on the atomic scale, is widely used in materials science. To date, research using AFM in medicine has focused on neurodegenerative diseases, osteoporosis, cancer tumors, cell receptors, proteins and the DNA mismatch repair (MMR) system. Only a few small studies of hair imaging have been conducted, mostly in biotechnology or cosmetology. Thanks to the possibilities offered by AFM imaging, dermatologists can non-invasively assess the condition of hair and its possible disorders. Our goal was to capture images and microscopically analyze morphological changes in the surface of healthy hair. Materials and Methods: In this study, three to five hairs were collected from each person. Each hair was examined at nine locations (0.5; 1.0; 1.5; 2.0; 3.5; 4.5; 5.5; 6.5 and 7.0 cm from the root). At least 4 images (4-10 images) were taken at each of the 9 locations. A total of 496 photos were taken and analyzed. Metric measurements of hair scales, such as apparent length, width and scale step height, were taken. Results: This publication presents the changes occurring in hair during the natural delamination process. In addition, morphoological changes visualized on the surface of healthy hair (pitting, oval indentations, rod-shaped macro-fibrillar elements, globules, scratches, wavy edge) are presented. A quantitative analysis of the structures found was carried out. Conclusions: The findings of this study can be used in further research and work related to the subject of human hair. They can serve as a reference for research on scalp and hair diseases, as well as hair care.


Assuntos
Doenças do Cabelo , Cabelo , Humanos , Microscopia de Força Atômica/métodos , Couro Cabeludo/patologia , População Branca
15.
J Phys Chem B ; 128(7): 1711-1723, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38348474

RESUMO

Polypeptides often self-assemble to form amyloid fibrils, which contain cross-ß structural motifs and are typically 5-15 nm in width and micrometers in length. In many cases, short segments of longer amyloid-forming protein or peptide sequences also form cross-ß assemblies but with distinctive ribbon-like morphologies that are characterized by a well-defined thickness (on the order of 5 nm) in one lateral dimension and a variable width (typically 10-100 nm) in the other. Here, we use a novel combination of data from solid-state nuclear magnetic resonance (ssNMR), dark-field transmission electron microscopy (TEM), atomic force microscopy (AFM), and cryogenic electron microscopy (cryoEM) to investigate the structures within amyloid ribbons formed by residues 14-23 and residues 11-25 of the Alzheimer's disease-associated amyloid-ß peptide (Aß14-23 and Aß11-25). The ssNMR data indicate antiparallel ß-sheets with specific registries of intermolecular hydrogen bonds. Mass-per-area values are derived from dark-field TEM data. The ribbon thickness is determined from AFM images. For Aß14-23 ribbons, averaged cryoEM images show a periodic spacing of ß-sheets. The combined data support structures in which the amyloid ribbon growth direction is the direction of intermolecular hydrogen bonds between ß-strands, the ribbon thickness corresponds to the width of one ß-sheet (i.e., approximately the length of one molecule), and the variable ribbon width is a variable multiple of the thickness of one ß-sheet (i.e., a multiple of the repeat distance in a stack of ß-sheets). This architecture for a cross-ß assembly may generally exist within amyloid ribbons.


Assuntos
Amiloide , Elétrons , Microscopia de Força Atômica , Estrutura Secundária de Proteína , Ressonância Magnética Nuclear Biomolecular/métodos , Amiloide/química , Proteínas Amiloidogênicas , Peptídeos beta-Amiloides/química
16.
Front Immunol ; 15: 1340384, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38322261

RESUMO

The innate immune system initiates early response to infection by sensing molecular patterns of infection through pattern-recognition receptors (PRRs). Previous work on PRR stimulation of macrophages revealed significant heterogeneity in single cell responses, suggesting the importance of individual macrophage stimulation. Current methods either isolate individual macrophages or stimulate a whole culture and measure individual readouts. We probed single cell NF-κB responses to localized stimuli within a naïve culture with Fluidic Force Microscopy (FluidFM). Individual cells stimulated in naïve culture were more sensitive compared to individual cells in uniformly stimulated cultures. In cluster stimulation, NF-κB activation decreased with increased cell density or decreased stimulation time. Our results support the growing body of evidence for cell-to-cell communication in macrophage activation, and limit potential mechanisms. Such a mechanism might be manipulated to tune macrophage sensitivity, and the density-dependent modulation of sensitivity to PRR signals could have relevance to biological situations where macrophage density increases.


Assuntos
Imunidade Inata , NF-kappa B , Microscopia de Força Atômica , Macrófagos , Receptores de Reconhecimento de Padrão
17.
Analyst ; 149(7): 1988-1997, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38420857

RESUMO

Chromosomal instability (CIN) is a source of genetic variation and is highly linked to the malignance of cancer. Determining the degree of CIN is necessary for understanding the role that it plays in tumor development. There is currently a lack of research on high-resolution characterization of CIN and the relationship between CIN and cell mechanics. Here, a method to determine CIN of breast cancer cells by high resolution imaging with atomic force microscopy (AFM) is explored. The numerical and structural changes of chromosomes in human breast cells (MCF-10A), moderately malignant breast cells (MCF-7) and highly malignant breast cells (MDA-MB-231) were observed and analyzed by AFM. Meanwhile, the nuclei, cytoskeleton and cell mechanics of the three kinds of cells were also investigated. The results showed the differences in CIN between the benign and cancer cells. Also, the degree of structural CIN increased with enhanced malignancy of cancer cells. This was also demonstrated by calculating the probability of micronucleus formation in these three kinds of cells. Meanwhile, we found that the area of the nucleus was related to the number of chromosomes in the nucleus. In addition, reduced or even aggregated actin fibers led to decreased elasticities in MCF-7 and MDA-MB-231 cells. It was found that the rearrangement of actin fibers would affect the nucleus, and then lead to wrong mitosis and CIN. Using AFM to detect chromosomal changes in cells with different malignancy degrees provides a new detection method for the study of cell carcinogenesis with a perspective for targeted therapy of cancer.


Assuntos
Actinas , Neoplasias da Mama , Humanos , Feminino , Microscopia de Força Atômica/métodos , Neoplasias da Mama/genética , Instabilidade Cromossômica , Mama
18.
Biochim Biophys Acta Gen Subj ; 1868(4): 130568, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38242181

RESUMO

BACKGROUND: The gene expression differs in the nuclei of normal and malignant mammalian cells, and transcription is a critical initial step, which defines the difference. The mechanical properties of transcriptionally active chromatin are still poorly understood. Recently we have probed transcriptionally active chromatin of the nuclei subjected to mechanical stress, by Atomic Force Microscopy (AFM) [1]. Nonetheless, a systematic study of the phenomenon is needed. METHODS: Nuclei were deformed and studied by AFM. Non-deformed nuclei were studied by fluorescence confocal microscopy. Their transcriptional activity was studied by RNA electrophoresis. RESULTS: The malignant nuclei under the study were stable to deformation and assembled of 100-300 nm beads-like units, while normal cell nuclei were prone to deformation. The difference in stability to deformation of the nuclei correlated with DNA supercoiling, and transcription-depended units were responsive to supercoils breakage. The inhibitors of the topoisomerases I and II disrupted supercoiling and made the malignant nucleus prone to deformation. Cell nuclei treatment with histone deacetylase inhibitors (HDACIs) preserved the mechanical stability of deformed malignant nuclei and, at the same time, made it possible to observe chromatin decondensation up to 20-60 nm units. The AFM results were supplemented with confocal microscopy and RNA electrophoresis data. CONCLUSIONS: Self-assembly of transcriptionally active chromatin and its decondensation, driven by DNA supercoiling-dependent rigidity, was visualized by AFM in the mechanically deformed nuclei. GENERAL SIGNIFICANCE: We demonstrated that supercoiled DNA defines the transcription mechanics, and hypothesized the nuclear mechanics in vivo should depend on the chromatin architecture.


Assuntos
Núcleo Celular , Cromatina , Animais , Cromatina/metabolismo , Núcleo Celular/metabolismo , Microscopia de Força Atômica/métodos , RNA/metabolismo , DNA/metabolismo , Mamíferos
19.
Anal Methods ; 16(4): 503-514, 2024 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-38167666

RESUMO

The studies of drug-induced apoptosis play a vital role in the identification of potential drugs that could treat diseases such as cancer. Alterations in the native morphology of cancer cells following treatment with anticancer drugs serve as one of the indicators that reveal drug efficacy. Various techniques such as optical microscopy, electron microscopy (EM), and atomic force microscopy (AFM) have been used to map the three dimensional (3D) morphological changes in cells induced with drugs. However, caution should be exercised when interpreting morphological data from techniques that might alter the native morphology of cells, caused by phototoxicity, electron beam invasiveness, intrusive sample preparation, and cell membrane deformation. Herein, we have used scanning ion conductance microscopy (SICM) to study the 3D morphology and roughness of A549 adenocarcinoma cells under physiological conditions before and after cisplatin induced apoptosis, where we observed an increase in height, overall shrinkage of the cells, and irregular features form on the cell membrane. Tracking the morphology of the same single A549 cells exposed to cisplatin unveiled heterogeneity in response to the drug, formation of membrane blebs, and an increase in membrane roughness. We have also demonstrated the use of SICM for studying the effect of cisplatin on the dynamic changes in the volume of A549 cells over days. SICM is demonstrated as a technique for studying the effect of drug induced apoptosis in the same cells over time, and for multiple different single cells.


Assuntos
Adenocarcinoma , Antineoplásicos , Humanos , Cisplatino/farmacologia , Microscopia de Força Atômica/métodos , Adenocarcinoma/tratamento farmacológico , Apoptose , Antineoplásicos/farmacologia
20.
Anal Chem ; 96(4): 1488-1497, 2024 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-38232037

RESUMO

While engineered DNA nanoframeworks have been extensively exploited for delivery of diagnostic and therapeutic regents, DNA tiling-based DNA frameworks amenable to applications in living systems lag much behind. In this contribution, by developing a Y-shaped backbone-based DNA tiling technique, we assemble Y-shaped backbone-rigidified supersized DNA tetrahedrons (RDT) with 100% efficiency for precisely targeted tumor therapy. RDT displays unparalleled rigidness and unmatched resistance to nuclease degradation so that it almost does not deform under the force exerted by the atomic force microscopy tip, and the residual amount is not less than 90% upon incubating in biological media for 24 h, displaying at least 11.6 times enhanced degradation resistance. Without any targeting ligand, RDT enters the cancer cell in a targeted manner, and internalization specificity is up to 15.8. Moreover, 77% of RDT objects remain intact within living cells for 14 h. The drug loading content of RDT is improved by 4-8 times, and RDT almost 100% eliminates the unintended drug leakage in a stimulated physiological medium. Once systemically administrated into HeLa tumor-bearing mouse models, doxorubicin-loaded RDTs preferentially accumulate in tumor sites and efficiently suppress tumor growth without detectable off-target toxicity. The Y-DNA tiling technique offers invaluable insights into the development of structural DNA nanotechnology for precise medicine.


Assuntos
DNA , Neoplasias , Humanos , Animais , Camundongos , Microscopia de Força Atômica , Doxorrubicina/farmacologia , Doxorrubicina/uso terapêutico , Células HeLa , Neoplasias/tratamento farmacológico
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