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Cells Apr 2022Steroid-resistant nephrotic syndrome (SRNS) frequently leads to end-stage renal disease, ultimately requiring kidney replacement therapies. SRNS is often caused by...
Steroid-resistant nephrotic syndrome (SRNS) frequently leads to end-stage renal disease, ultimately requiring kidney replacement therapies. SRNS is often caused by hereditary monogenic mutations, specifically affecting specialized epithelial cells (podocytes) of the glomerular filtration barrier. Mutations in several components of the nuclear pore complex, including NUP133 and NUP107, have been recently identified to cause hereditary SRNS. However, underlying pathomechanisms, eliciting podocyte-specific manifestations of these nucleoporopathies, remained largely elusive. Here, we generated an in vitro model of -linked nucleoporopathies using CRISPR/Cas9-mediated genome editing in human podocytes. Transcriptome, nuclear pore assembly, and cytoskeleton regulation of loss-of-function, mutant, and wild-type podocytes were analyzed. Loss of NUP133 translated into a disruption of the nuclear pore, alterations of the podocyte-specific transcriptome, and impaired cellular protrusion generation. Surprisingly, comparative analysis of the described SRNS-related mutations revealed only mild defects. Am impaired protein interaction in the Y-complex and decrease of NUP133 protein levels might be the primary and unifying consequence of mutant variants, leading to a partial loss-of-function phenotype and disease manifestation in susceptible cell types, such as podocytes.
Topics: Cytoskeleton; Humans; Minor Histocompatibility Antigens; Nephrotic Syndrome; Nuclear Pore; Nuclear Pore Complex Proteins; Podocytes; Transcriptome
PubMed: 35455939
DOI: 10.3390/cells11081259 -
Scientific Reports Jan 2021Utilizing methods such as scanning electron microscopy observation and mercury intrusion porosimetry, this paper investigates the basic microstructure and pore structure...
Utilizing methods such as scanning electron microscopy observation and mercury intrusion porosimetry, this paper investigates the basic microstructure and pore structure properties of polymer-cement composite joint sealants for pavements, and analyzes the effects and rules of various material types, ratio parameters and processing conditions. Further, the fractal characteristics and variation rules of pore size distribution are investigated for the joint sealants by introducing the fractal theory. The results show that changes in material type, ratio parameter and processing condition produce insignificant effects on the basic microstructure properties and configuration of joint sealants, with effects reflected primarily in the change of sealant pore structure. Measures like increasing the powder-liquid ratio and cement ratio, blending with sulphoaluminate cement or mica powder, adding latex powder or coupling agent, cold drawing and hot pressing, as well as ultraviolet irradiation treatment are all capable of reducing the total pore volume of joint sealants and refining their pore structure. In contrast, opposite effects are yielded when low-grade cement is used, styrene-acrylic emulsion is blended, or plasticizer is added. Additionally, after blending with talc powder or adding carbon fiber additive, the total pore volume of joint sealants remains basically unchanged or reduced, despite the coarsened pore structure. The total pore volume of joint sealants increases after wet-dry cycling treatment, while no obvious change in the pore size distribution is observed. Pore size distribution of the studied joint sealants presents distinct fractal characteristics, and the corresponding fractal dimension of pore surface area ranges between 2.6 and 2.8.
PubMed: 33446801
DOI: 10.1038/s41598-021-81088-9 -
Biochimica Et Biophysica Acta Mar 2016A number of pore-forming toxins (PFTs) can assemble on lipid membranes through their specific interactions with lipids. The oligomeric assemblies of some PFTs have been... (Review)
Review
A number of pore-forming toxins (PFTs) can assemble on lipid membranes through their specific interactions with lipids. The oligomeric assemblies of some PFTs have been successfully revealed either by electron microscopy (EM) and/or atomic force microscopy (AFM). Unlike EM, AFM imaging can be performed under physiological conditions, enabling the real-time visualization of PFT assembly and the transition from the prepore state, in which the toxin does not span the membrane, to the pore state. In addition to characterizing PFT oligomers, AFM has also been used to examine toxin-induced alterations in membrane organization. In this review, we summarize the contributions of AFM to the understanding of both PFT assembly and PFT-induced membrane reorganization. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
Topics: Animals; Cell Membrane; Humans; Microscopy, Atomic Force; Pore Forming Cytotoxic Proteins; Protein Multimerization; Protein Structure, Quaternary
PubMed: 26577274
DOI: 10.1016/j.bbamem.2015.11.005 -
Frontiers in Cellular Neuroscience Nov 2013The occupancy of the orthosteric ligand binding sites of P2X receptor (P2XR) channels causes the rapid opening of a small cation-permeable pore, followed by a gradual... (Review)
Review
The occupancy of the orthosteric ligand binding sites of P2X receptor (P2XR) channels causes the rapid opening of a small cation-permeable pore, followed by a gradual dilation that renders the pore permeable to large organic cations. Electrophysiologically, this phenomenon was shown using whole-cell current recording on P2X2R-, P2X2/X5R-, P2X4R- and P2X7R-expressing cells that were bathed in N-methyl-D-glucamine (NMDG(+))-containing buffers in the presence and/or absence of small monovalent and divalent cations. The pore dilation of P2X4R and P2X7R caused a secondary current growth, whereas that of P2X2R showed a sustained kinetic coupling of dilation and desensitization, leading to receptor channel closure. The pore size of the P2X7R open and dilated states was estimated to be approximately 0.85 nm and greater than 1 nm, respectively. The P2XR pore dilation was also observed in intact cells by measurement of fluorescent dye uptake/release, application of polyethylene glycols of different sizes, and atomic force microscopy. However, pore dilation was not observed at the single channel level. Structural data describing the dilated state are not available, and the relevance of orthosteric and allosteric ligand interactions to pore dilation was not studied.
PubMed: 24312007
DOI: 10.3389/fncel.2013.00215 -
ACS Omega Mar 2022Pore types and pore structure parameters are the important factors affecting the storage capacity of a shale oil reservoir. Pore morphology and mineralogical composition...
Pore types and pore structure parameters are the important factors affecting the storage capacity of a shale oil reservoir. Pore morphology and mineralogical composition of shales have diverse effects on the upgrading of various phases of shale oil. To interpret the formation and distribution of different pore types and their structure parameters in the lacustrine calcareous shale, a combination of polarizing microscopy, X-ray diffraction, total organic carbon (TOC), field-emission scanning electron microscopy, and low-pressure nitrogen adsorption experiments were conducted on the Es3x shale of the Eocene Shahejie Formation in the Zhanhua Depression. The interpretations regarding pore types, pore structure parameters, and pore size distribution indicate that the pore morphology and pore size distribution in the lacustrine shale are very complicated and demonstrate strong heterogenic behavior. Inorganic pores (interparticle pores, intraparticle pores, intercrystalline pores, dissolution pores, and microfractures) are the most commonly distributed pore types in the studied shale. However, organic matter pores are poorly developed due to the lower thermal maturity of the Es3x shale. The Brunauer-Emmett-Teller specific surface and pore volume range from 0.026 to 1.282 m/g (average 0.697 m/g) and 0.003 to 0.008 cm/g (average 0.005 cm/g), respectively. The shape of the pores varies from slit-like to narrow slit. Different minerals develop different types of pores with various sizes extending from micropores (<2 nm), mesopores (2-50 nm), to macropores (>50 nm). The relationship between mineral components and pore parameters indicates that the carbonate minerals act as the main contributors to the formation and distribution of different pore types in the studied shale. Pore volume and the pore specific surface area did not show a good relationship with mineral composition and TOC due to disordered pores, but pore size shows a good relationship with mineral composition and TOC of the Es3x shale. The whole pore system description showed that the mesopores and macropores are abundantly distributed and are the main contributors to the pore system in the Es3x shale. A comprehensive understanding of the formation mechanism and structural features of various sized pores in a variety of different minerals can provide a good tool for the exploration and development of shale oil reservoirs.
PubMed: 35382284
DOI: 10.1021/acsomega.2c01001 -
Traffic (Copenhagen, Denmark) Feb 2014The nucleus is the defining intracellular organelle of eukaryotic cells and represents a major structural innovation that differentiates the eukaryotic and prokaryotic... (Review)
Review
The nucleus is the defining intracellular organelle of eukaryotic cells and represents a major structural innovation that differentiates the eukaryotic and prokaryotic cellular form. The presence of a nuclear envelope (NE) encapsulating the nucleus necessitates a mechanism for interchange between the contents of the nuclear interior and the cytoplasm, which is mediated via the nuclear pore complex (NPC), a large protein assembly residing in nuclear pores in the NE. Recent advances have begun to map the structure and functions of the NPC in multiple organisms, and to allow reconstruction of some of the evolutionary events that underpin the modern NPC form, highlighting common and differential NPC features across the eukaryotes. Here we discuss some of these advances and the questions being pursued, consider how the evolution of the NPC has been constrained, and finally propose a model for how the NPC evolved.
Topics: Active Transport, Cell Nucleus; Animals; Evolution, Molecular; Humans; Nuclear Pore; Nuclear Pore Complex Proteins
PubMed: 24279500
DOI: 10.1111/tra.12141 -
Frontiers in Bioscience (Landmark... Dec 2023Nuclear pore complexes (NPCs) are intricate intracellular structures composed of approximately 30 nuclear pore proteins (NUPs) that regulate the transport of materials... (Review)
Review
Nuclear pore complexes (NPCs) are intricate intracellular structures composed of approximately 30 nuclear pore proteins (NUPs) that regulate the transport of materials between the nucleus and cytoplasm in eukaryotic cells. The heart is a crucial organ for sustaining the vital functions of the body, pumping blood rich in nutrients and energy to all organs and tissues. Recent studies have shown that NPCs play pivotal roles not only in normal cardiac physiological processes such as myocardial cell proliferation and differentiation but also in various pathological processes such as ischemic and hypoxic myocardial injury. Due to their mass and complicated nature, the structures of NPCs have been challenging to identify by the scientific community. With the development of cryo-electron microscopy and advanced sampling techniques, researchers have made significant progress in understanding the structures of NPCs. This review aims to summarize the latest research on the structural aspects of NPCs and their roles in cardiac physiology and pathology, increase the understanding of the intricate mechanisms of NPC actions, provide valuable insights into the pathogenesis of heart diseases and describe the development of potential novel therapeutic strategies.
Topics: Nuclear Pore Complex Proteins; Active Transport, Cell Nucleus; Cryoelectron Microscopy; Nuclear Pore; Cytoplasm
PubMed: 38179752
DOI: 10.31083/j.fbl2812350 -
Genome Biology 2001Nuclear pore complexes, the conduits for information exchange between the nucleus and cytoplasm, appear broadly similar in eukaryotes from yeast to human. Precisely how... (Review)
Review
Nuclear pore complexes, the conduits for information exchange between the nucleus and cytoplasm, appear broadly similar in eukaryotes from yeast to human. Precisely how nuclear pore complexes regulate macromolecular and ionic traffic remains unknown, but recent advances in the identification and characterization of components of the complex by proteomics and genomics have provided new insights.
Topics: Animals; Genomics; Humans; Nuclear Pore; Nuclear Pore Complex Proteins; Proteome
PubMed: 11574060
DOI: 10.1186/gb-2001-2-9-reviews0007 -
Nature Communications Aug 2022Perforin-2 (PFN2, MPEG1) is a pore-forming protein that acts as a first line of defense in the mammalian immune system, rapidly killing engulfed microbes within the...
Perforin-2 (PFN2, MPEG1) is a pore-forming protein that acts as a first line of defense in the mammalian immune system, rapidly killing engulfed microbes within the phagolysosome in macrophages. PFN2 self-assembles into hexadecameric pre-pore rings that transition upon acidification into pores damaging target cell membranes. Here, using high-speed atomic force microscopy (HS-AFM) imaging and line-scanning and molecular dynamics simulation, we elucidate PFN2 pre-pore to pore transition pathways and dynamics. Upon acidification, the pre-pore rings (pre-pore-I) display frequent, 1.8 s, ring-opening dynamics that eventually, 0.2 s, initiate transition into an intermediate, short-lived, ~75 ms, pre-pore-II state, inducing a clockwise pre-pore-I to pre-pore-II propagation. Concomitantly, the first pre-pore-II subunit, undergoes a major conformational change to the pore state that propagates also clockwise at a rate ~15 s. Thus, the pre-pore to pore transition is a clockwise hand-over-hand mechanism that is accomplished within ~1.3 s. Our findings suggest a clockwise mechanism of membrane insertion that with variations may be general for the MACPF/CDC superfamily.
Topics: Animals; Cell Membrane; Macrophages; Mammals; Microscopy, Atomic Force; Molecular Dynamics Simulation; Perforin; Pore Forming Cytotoxic Proteins
PubMed: 36028507
DOI: 10.1038/s41467-022-32757-4 -
Journal of Contaminant Hydrology Sep 2016Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement,... (Review)
Review
Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement, non-Darcy flow, reactive transport and thermodynamically consistent oil layers. The realism of such modelling, i.e. the credibility of their predictions, depends to a large extent on the quality of the correspondence between the pore space of a given medium and the pore network constructed as its representation. The main experimental techniques for pore space characterisation, including direct imaging, mercury intrusion porosimetry and gas adsorption, are firstly summarised. A review of the main pore network construction techniques is then presented. Particular focus is given on how such constructions are adapted to the data from experimentally characterised pore systems. Current applications of pore network models are considered, with special emphasis on the effects of adsorption, dissolution and precipitation, as well as biomass growth, on transport coefficients. Pore network models are found to be a valuable tool for understanding and predicting meso-scale phenomena, linking single pore processes, where other techniques are more accurate, and the homogenised continuum porous media, used by engineering community.
Topics: Adsorption; Algorithms; Biomass; Environmental Monitoring; Hydrology; Magnetic Resonance Spectroscopy; Mercury; Models, Theoretical; Porosity; X-Ray Microtomography
PubMed: 27442725
DOI: 10.1016/j.jconhyd.2016.07.002