BMB Reports最新文献

Spondyloarthritis (SpA) is a chronic inflammatory disease that leads to ankylosis of the axial skeleton. Celecoxib (cyclooxygenase-2 inhibitor, COX-2i) inhibited radiographic progression in a clinical study of SpA, but in the following study, diclofenac (COX-2 non-selective) failed to show that inhibition. Our study aimed to investigate whether nonsteroidal anti-inflammatory drugs (NSAIDs) inhibited bone progression in SpA, and whether celecoxib had a unique function (independent of the COX-inhibitor), compared with the other NSAIDs. We investigated the efficacy of various NSAIDs in curdlan-injected SKG mice (SKGc), an animal model of SpA, analyzed by bone micro-CT and immunohistochemistry. We also tested the effect of NSAIDs on osteoblast (OB) differentiation and bone mineralization in primary bone-derived cells (BdCs) from mice, and in ankylosing spondylitis (AS) patients and human osteosarcoma cell line (SaOS2). Celecoxib significantly inhibited clinical arthritis and bone progression in the joints of SKGc, but not etoricoxib (another COX-2i), nor naproxen (COX-2 nonselective). Both DM-celecoxib, not inhibiting COX-2, and celecoxib, inhibited OB differentiation and bone mineralization in the BdCs of mice and AS patients, and in SaOS2, but etoricoxib or naproxen did not. The in silico study indicated that celecoxib and 2,5-dimethyl-celecoxib (DM-celecoxib) would bind to cadherin-11 (CDH11) with higher affinity than etoricoxib and naproxen. Celecoxib suppressed CDH11-mediated β-catenin signaling in the joints of SKGc, primary mice cells, and SaOS2 cells. Of the NSAIDs, only celecoxib inhibited bone progression in SKGc and OB differentiation and bone mineralization in the BdCs of mice and AS patients via CDH11/WNT signaling, independent of the COX-2 inhibition.

Atopic dermatitis (AD) is a chronic, pruritic skin disease characterized by inflammation and skin lesion cornification. While the use of corticosteroids like dexamethasone (DXM), an antiinflammatory drug, improves symptoms temporarily and quickly, this use is not a cure. Thus, we aimed to identify a new therapeutic strategy for AD using quantum molecular resonance (QMR), a novel non-invasive technique with an electromagnetic field-based therapeutic approach as an alternative to pain killers. An AD mouse model presenting AD-like skin lesions was generated by treating BALB/c mice with dinitrochlorobenzene (DNCB), and then DNCB-induced AD mice were administered DXM or QMR, and the change of AD-like skin lesions was observed. QMR ameliorated AD-like skin lesions in DNCB-induced AD mice and reduced the numbers of infiltrated mast cells and macrophages in mouse skin. QMR also alleviated thickening of the epidermis and restored integrity of the epidermal basement membrane. Several genes regulated by DNCB and counterregulated by QMR were identified through transcriptome analysis in mouse skin, and RNA silencing experiments on these genes in TNF-α/IFN-γ- or DNCB-treated human keratinocytes revealed that IL36G and SPRR2B play important roles in inflammation and keratinization. The expression of IL36G and SPRR2B was significantly reduced by QMR in skin of DNCB-induced AD mice. These results underscore the promising role of QMR in ameliorating AD characterized by inflammation and skin lesion hyperkeratosis via targeting IL36G and SPRR2B.

Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD) and its progressive form, Metabolic Dysfunction Associated Steatohepatitis (MASH), represent significant health concerns associated with the metabolic syndrome. These conditions are characterized by excessive hepatic fat accumulation, inflammation, and potential progression to cirrhosis and hepatocellular carcinoma. Neutrophils are innate immune cells that play a pivotal role in the development of MASLD and MASH. They can infiltrate the hepatic microenvironment in response to inflammatory cytokines and damage associated molecular patterns (DAMPs) derived from the liver and exacerbate tissue damage by releasing of reactive oxygen species (ROS), cytokines, and neutrophil extracellular traps (NETs). Moreover, neutrophils can disrupt the metabolism of hepatocytes through key factors such as neutrophil elastase (NE) and human neutrophil peptides-1 (HNP-1), leading to inflammation and fibrosis, while myeloperoxidase (MPO) and lipocalin (LCN2) are involved in inflammatory and fibrotic processes. In contrast, neutrophils contribute to liver protection and repair through mechanisms involving microRNA-223 and matrix metalloproteinase 9 (MMP9). This dual role of neutrophils highlights their significance in the pathogenesis of MASLD and MASH. This review summarizes current understanding from recent studies on the involvement of neutrophils in MASLD and MASH. Understanding complex roles of neutrophils within the liver's unique microenvironment offers insights into novel therapeutic strategies, emphasizing the need for further research to explore neutrophil-targeted interventions for managing MASLD and MASH.

G protein-coupled receptor 40 (GPR40) is gaining recognition as a potential therapeutic target for several metabolic disturbances, such as hyperglycemia and excessive inflammation. GPR40 is expressed in various tissues, including the heart; however, its specific roles in cardiomyocytes remain unknown. The objective of the present study was to investigate whether treatment with AM1638, a GPR40-full agonist, reduces palmitate-mediated cell damage in H9c2 rat cardiomyocytes. AM1638 treatment increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and expression levels of the antioxidant molecules heme oxygenase-1 (HO-1) and nicotinamide adenine dinucleotide phosphate: quinone oxidoreductase-1 (NQO1). Palmitate-mediated superoxide production and levels of 4-hydroxynonenal, a biomarker of oxidative stress, decreased after treatment with AM1638. Notably, palmitate-mediated disruption of mitochondrial membrane potential, lower levels of mitochondrial complex protein, and failure of adenosine triphosphate production were all recovered by treatment with AM1638. Moreover, AM1638 blocked palmitate-mediated caspase-3 cleavage and nuclear fragmentation, thereby improving cell viability. However, these AM1638-mediated beneficial effects were abrogated by treatment with Compound C, an AMPK inhibitor. These results demonstrate that AM1638, a GPR40-full agonist, ameliorates palmitate-mediated oxidative stress in H9c2 cells in an AMPK-dependent manner.

Tau, a microtubule-associated protein, is known for its significant involvement in neurodegenerative diseases. While various molecular and immunohistochemical techniques have confirmed the presence of Tau in podocytes, its precise function within these cells remains elusive. In this study, we investigate the role of Tau in kidney podocytes using Drosophila pericardial nephrocytes as a model. We found that knockdown of Drosophila Tau in nephrocytes resulted in apoptotic cell death and the disruption of nephrocyte structure. Furthermore, we observed that decreased Tau levels induced genomic damage and abnormal distribution of γ-H2Av, altering nuclei architecture in nephrocytes, and affecting the nuclear membrane structure by interfering with lamin with aging. Additionally, Tau knockdown led to a reduction in lipid droplets in Drosophila fat body tissues, suggesting a potential role of Tau in inter-organ communication. These findings underscore the importance of Tau in the nephrocytes of Drosophila, and advocate further research to broaden our understanding of podocyte biology in kidney diseases.

CRISPR/Cas systems have emerged as powerful tools for gene editing, nucleic acid detection, and therapeutic applications. Recent advances in single-molecule techniques have provided new insights into the DNA-targeting mechanisms of CRISPR/ Cas systems, in particular, Types I, II, and V. Here, we review how single-molecule approaches have expanded our understanding of key processes, namely target search, recognition, and cleavage. Furthermore, we focus on the dynamic behavior of Cas proteins, including PAM site recognition and R-loop formation, which are crucial to ensure specificity and efficiency in gene editing. Additionally, we discuss the conformational changes and interactions that drive precise DNA cleavage by different Cas proteins. This mini review provides a comprehensive overview of CRISPR/Cas molecular dynamics, offering conclusive insights into their broader potential for genome editing and biotechnological applications. [BMB Reports 2024; 58(1): 8-16].

The nucleosome is the fundamental structural unit of chromosome fibers. DNA wraps around a histone octamer to form a nucleosome while neighboring nucleosomes interact to form higher-order structures and fit gigabase-long DNAs into a small volume of the nucleus. Nucleosomes interrupt the access of transcription factors to a genomic region and provide regulatory controls of gene expression. Biochemical and physical cues stimulate wrapping-unwrapping and condensation-decondensation dynamics of nucleosomes and nucleosome arrays. Nucleosome dynamics and chromatin fiber organization are influenced by changes in the ionic background within the nucleus, post-translational modifications of histone proteins, and DNA sequence characteristics, such as histone-binding motifs and nucleosome spacing. Biochemical and biophysical measurements, along with in silico simulations, have been extensively used to study the regulatory effects on chromatin dynamics. In particular, single-molecule measurements have revealed novel mechanistic details of nucleosome and chromatin dynamics. This minireview elucidates recent findings on chromatin dynamics from these approaches. [BMB Reports 2024; 58(1): 24-32].

Single-molecule techniques allow researchers to investigate individual molecules and obtain unprecedented details of the heterogeneous nature of biological entities. They play instrumental roles in studying DNA-protein interactions due to the ability to visualize DNA or proteins and to manipulate individual DNA molecules by applying force or torque. Here, we describe single-molecule DNA-flow stretching assays as hybrid tools that combine forces with fluorescence. We also review how widely these assays are utilized in elucidating working mechanisms of DNA-binding proteins. Additionally, we provide a brief explanation of various efforts to prepare DNA substrates with desired internal protein-binding sequences. More complicated needs for DNA-protein interaction research have led to improvements in single-molecule DNA flow-stretching techniques. Several DNA flow-stretching variants such as DNA curtain, DNA motion capture assays, and protein-induced fluorescence enhancement (PIFE) are introduced in this mini review. Singlemolecule DNA flow-stretching assays will keep contributing to our understanding of how DNA-binding proteins function due to their multiplexed, versatile, and robust capabilities. [BMB Reports 2024; 58(1): 41-51].

Model membrane systems have emerged as essential platforms for investigating membrane-associated processes in controlled environments, mimicking biological membranes without the complexity of cellular systems. However, integrating these model systems with single-molecule techniques remains challenging due to the fluidity of lipid membranes, including undulations and the lateral mobility of lipids and proteins. This mini-review explores the evolution of various model membranes ranging from black lipid membranes to nanodiscs and giant unilamellar vesicles as they adapt to accommodate electrophysiology, force spectroscopy, and fluorescence microscopy. We highlight recent advancements, including innovations in force spectroscopy and single-molecule imaging using free-standing lipid bilayers, and the development of membrane platforms with tunable composition and curvature for improving fluorescence-based studies of protein dynamics. These integrated approaches have provided deep insights into ion channel function, membrane fusion, protein mechanics, and protein dynamics. We highlight how the synergy between single-molecule techniques and model membranes enhances our understanding of complex cellular processes, paving the way for future discoveries in membrane biology and biophysics. [BMB Reports 2024; 58(1): 33-40].

Cryo-fixation techniques, including cryo-electron and cryofluorescence microscopy, enable the preservation of biological samples in a near-native state by rapidly freezing them into an amorphous ice phase. These methods prevent the structural distortions often caused by chemical fixation, allowing for high-resolution imaging. At low temperatures, fluorophores exhibit improved properties, such as extended fluorescence lifetimes, reduced photobleaching, and enhanced signal-tonoise ratios, making single-molecule imaging more accurate and insightful. Despite these advantages, challenges remain, including limitations in numerical aperture of objectives and cryo-stage for single-molecule imaging, which can affect photon detection and spatial resolution. Recent advancements at low temperatures have mitigated these issues, achieving resolutions at the nanometer scale. Looking forward, innovations in super-resolution techniques, optimized fluorophores, and Artificial Intelligence (AI)-based data analysis promise to further advance the field, providing deeper insights into biomolecular dynamics and interactions. In this mini-review, we will introduce low-temperature single-molecule fluorescence imaging techniques and discuss future perspectives in this field. [BMB Reports 2024; 58(1): 2-7].