scholarly journals A single molecule localization microscopy method for tissues reveals nonrandom nuclear pore distribution in Drosophila

2021 ◽  
Author(s):  
Jinmei Cheng ◽  
Edward S. Allgeyer ◽  
Jennifer H. Richens ◽  
Edo Dzafic ◽  
Amandine Palandri ◽  
...  
Keyword(s):  
Single Molecule ◽  
Cultured Cells ◽  
Ectopic Expression ◽  
Nuclear Pore ◽  
Optical Sectioning ◽  
Nuclear Pores ◽  
High Background ◽  
Chromatin Organisation ◽  
Microscopy Method ◽  
Localisation Microscopy

Single Molecule Localisation Microscopy (SMLM) can provide nanoscale resolution in thin samples but has rarely been applied to tissues, because of high background from out of focus emitters and optical aberrations. Here we describe a line scanning microscope that provides optical sectioning for SMLM in tissues. Imaging endogenously-tagged nucleoporins and F-actin on this system using DNA- and peptide-PAINT routinely gives 30 nm resolution or better at depths greater than 20 µm. This revealed that the nuclear pores are nonrandomly distributed in most Drosophila tissues, in contrast to cultured cells. Lamin Dm0 shows a complementary localisation to the nuclear pores, suggesting that it corrals the pores. Furthermore, ectopic expression of the tissue-specific Lamin C distributes the nuclear pores more randomly, whereas lamin C mutants enhance nuclear pore clustering, particularly in muscle nuclei. Since nucleoporins interact with specific chromatin domains, nuclear pore clustering could regulate local chromatin organisation and contribute to the disease phenotypes caused by human Lamin A/C laminopathies.

scholarly journals A method for single molecule localization microscopy of tissues reveals nonrandom distribution of nuclear pores in Drosophila

2021 ◽  
Author(s):  
Jinmei Cheng ◽  
Edward S Allgeyer ◽  
Jennifer H Richens ◽  
Edo Dzafic ◽  
Amandine Palandri ◽  
...  
Keyword(s):  
Single Molecule ◽  
Cultured Cells ◽  
Ectopic Expression ◽  
Nuclear Pore ◽  
Optical Sectioning ◽  
Nuclear Pores ◽  
High Background ◽  
Chromatin Organisation ◽  
Localisation Microscopy ◽  
Single Molecule Localization Microscopy

Single Molecule Localisation Microscopy (SMLM) can provide nanoscale resolution in thin samples but has rarely been applied to tissues, because of high background from out of focus emitters. Here we describe a line scanning microscope that provides optical sectioning for SMLM in tissues. Imaging endogenously-tagged nucleoporins and F-actin on this system using DNA- and peptide-PAINT routinely gives 30nm resolution or better at depths greater than 20 μm. This revealed that the nuclear pores are nonrandomly distributed in most Drosophila tissues, in contrast to cultured cells. Lamin Dm0 shows a complementary localisation to the nuclear pores, suggesting that it corrals the pores. Furthermore, ectopic expression of the tissue-specific Lamin C distributes the nuclear pores more randomly, whereas lamin C mutants enhance nuclear pore clustering, particularly in muscle nuclei. Since nucleoporins interact with specific chromatin domains, nuclear pore clustering could regulate chromatin organisation locally and contribute to the disease phenotypes caused by human Lamin A/C laminopathies.

scholarly journals Fluorogenic probe for fast 3D whole-cell DNA-PAINT

2020 ◽  
Author(s):  
Kenny KH Chung ◽  
Zhao Zhang ◽  
Phylicia Kidd ◽  
Yongdeng Zhang ◽  
Nathan D Williams ◽  
...  
Keyword(s):  
3D Imaging ◽  
Super Resolution ◽  
Fold Increase ◽  
High Fidelity ◽  
Optical Sectioning ◽  
High Background ◽  
Fluorogenic Probe ◽  
Microscopy Method ◽  
Super Resolution Microscopy ◽  
Imaging Speed

AbstractDNA-PAINT is an increasingly popular super-resolution microscopy method that can acquire high-fidelity images at nanometer resolution. It suffers, however, from high background and very slow imaging speed, both of which can be attributed to the presence of unbound fluorophores in solution. We present a fluorogenic DNA-PAINT probe that solves these problems and demonstrate 3D imaging without the need for optical sectioning and a 26-fold increase in imaging speed over regular DNA-PAINT.

scholarly journals Virtual-'Light-Sheet' Single-Molecule Localisation Microscopy Enables Quantitative Optical Sectioning for Super-Resolution Imaging

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0125438 ◽  
Author(s):  
Matthieu Palayret ◽  
Helen Armes ◽  
Srinjan Basu ◽  
Adam T. Watson ◽  
Alex Herbert ◽  
...  
Keyword(s):  
Single Molecule ◽  
Super Resolution ◽  
Light Sheet ◽  
Optical Sectioning ◽  
Resolution Imaging ◽  
Localisation Microscopy

scholarly journals Nuclear mRNA metabolism drives selective basket assembly on a subset of nuclear pores in budding yeast

2021 ◽  
Author(s):  
Pierre Bensidoun ◽  
Taylor Reiter ◽  
Ben Montpetit ◽  
Daniel Zenklusen ◽  
Marlene Oeffinger
Keyword(s):  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Protein Complexes ◽  
Budding Yeast ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Mrna Metabolism ◽  
Leakage Factor ◽  
Data Points ◽  
Cleavage And Polyadenylation

To determine which transcripts should reach the cytoplasm for translation, eukaryotic cells have established mechanisms to regulate selective mRNA export through the nuclear pore complex (NPC). The nuclear basket, a substructure of the NPC protruding into the nucleoplasm, is thought to function as a stable platform where mRNA-protein complexes (mRNPs) are rearranged and undergo quality control (QC) prior to export, ensuring that only mature mRNAs reach the cytoplasm. Here, we use proteomic, genetic, live-cell, and single-molecule resolution microscopy approaches in budding yeast to demonstrate that baskets assemble only on a subset of NPCs and that basket formation is dependent on RNA polymerase II (Pol II) transcription and subsequent mRNP processing. Specifically, we observe that the cleavage and polyadenylation machinery, the poly(A)-binding protein Pab1, and pre-mRNA-leakage factor Pml39 are required for basket assembly. We further show that while all nuclear pores can bind Mlp1, baskets assemble only on a subset of nucleoplasmic NPCs and these basket-containing pores associate a distinct protein and RNA interactome. Taken together, our data points towards nuclear pore heterogeneity and an RNA-dependent mechanism for functionalization of nuclear pores in budding yeast through nuclear basket assembly.

The Formation, Structure, Distribution and Frequency of Nuclear Pores

1971 ◽  
Vol 29 ◽  
pp. 518-519
Author(s):  
G. G. Maul
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Dynamic Structure ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Filter Function ◽  
Etching Technique ◽  
Selective Filter ◽  
Membranous Part

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

scholarly journals A simple surface modification to generate atomically-flat and hydrophobic substrates for gliding assays with protein motors

2021 ◽  
Author(s):  
Isadonna Tengganu ◽  
Neil Karerakattil ◽  
Swarup Dey ◽  
Devika Kishnan ◽  
Rizal Hariadi
Keyword(s):  
Single Molecule ◽  
Vapor Deposition ◽  
Glass Capillary ◽  
High Background ◽  
Protein Motors ◽  
Order Of Magnitude ◽  
Protein Motor ◽  
Glass Surfaces ◽  
Atomically Flat

In vitro gliding assay is a well-established assay for determining the activity of protein motors, such as actin-associated myosins and microtubule-associated kinesins and dyneins. In one of the conventional methods, protein motors are immobilized onto a nitrocellulose-coated coverslip and it propels actin filaments in the presence of ATP. Gliding assays also serve as the foundation for protein-motor-based nanotechnological devices such as biosensing and sorting. However, the preparation of nitrocellulose-coated coverslips is time-consuming and produces rough surfaces. Furthermore, the nitrocellulose film exhibits high background autofluorescence, which can be a problem in single-molecule measurements. Here, we investigated the use of hexamethyldisilazane (HMDS) to study actomyosin function and characterized its physical properties on glass coverslips and glass capillary tubes. We showed that the total preparation time to coat a coverslip with HMDS is <30 minutes, which is 1 order of magnitude faster than the >12-hour protocol for coating glass surfaces with nitrocellulose. In contrast to nitrocellulose film, HMDS vapor deposition is effortless and provides an atomically flat surface with low autofluorescence. In addition, HMDS does not interfere with myosin function, which is indicated by the similar actin gliding speed when compared with nitrocellulose. Our results show that HMDS vapor deposition is a more favorable surface treatment to nitrocellulose for in vitro gliding assay.

scholarly journals Methods for protein delivery into cells: from current approaches to future perspectives

2020 ◽  
Vol 48 (2) ◽  
pp. 357-365
Author(s):  
Chalmers Chau ◽  
Paolo Actis ◽  
Eric Hewitt
Keyword(s):  
Single Molecule ◽  
Cell Biology ◽  
Protein Delivery ◽  
Mammalian Cells ◽  
Cultured Cells ◽  
Cellular Damage ◽  
Future Perspectives ◽  
Chemically Modified ◽  
Recent Developments ◽  
Direct Delivery

The manipulation of cultured mammalian cells by the delivery of exogenous macromolecules is one of the cornerstones of experimental cell biology. Although the transfection of cells with DNA expressions constructs that encode proteins is routine and simple to perform, the direct delivery of proteins into cells has many advantages. For example, proteins can be chemically modified, assembled into defined complexes and subject to biophysical analyses prior to their delivery into cells. Here, we review new approaches to the injection and electroporation of proteins into cultured cells. In particular, we focus on how recent developments in nanoscale injection probes and localized electroporation devices enable proteins to be delivered whilst minimizing cellular damage. Moreover, we discuss how nanopore sensing may ultimately enable the quantification of protein delivery at single-molecule resolution.

Sequential degradation of proteins from the nuclear envelope during apoptosis

2001 ◽  
Vol 114 (20) ◽  
pp. 3643-3653 ◽  
Author(s):  
Madeleine Kihlmark ◽  
Gabriela Imreh ◽  
Einar Hallberg
Keyword(s):  
Nuclear Envelope ◽  
Apoptotic Cell ◽  
Nuclear Periphery ◽  
Condensed Chromatin ◽  
Nuclear Pore ◽  
Dependent Manner ◽  
Nuclear Pores ◽  
Double Labeling ◽  
Lamin B ◽  
Nuclear Apoptosis

We have produced new antibodies specific for the integral pore membrane protein POM121. Using these antibodies we show that during apoptosis POM121 becomes proteolytically degraded in a caspase-dependent manner. The POM121 antibodies and antibodies specific for other proteins of the nuclear envelope were used in a comparative study of nuclear apoptosis in staurosporine-treated buffalo rat liver cells. Nuclei from these cells were classified in three different stages of apoptotic progression: stage I, moderately condensed chromatin surrounded by a smooth nuclear periphery; stage II, compact patches of condensed chromatin collapsing against a smooth nuclear periphery; stage III, round compact chromatin bodies surrounded by grape-shaped nuclear periphery. We have performed double labeling immunofluorescence microscopy of individual apoptotic cells and quantitative immunoblotting analysis of total proteins from apoptotic cell cultures. The results showed that degradation of nuclear envelope marker proteins occurred in a specific order. POM121 degradation occurred surprisingly early and was initiated before nucleosomal DNA degradation could be detected using TUNEL assay and completed before clustering of the nuclear pores. POM121 was eliminated significantly more rapid compared with NUP153 (a peripheral protein located in the nucleoplasmic basket of the nuclear pore complex) and lamin B (a component of the nuclear lamina). Disappearance of NUP153 and lamin B was coincident with onset of DNA fragmentation and clustering of nuclear pores. By contrast, the peripheral NPC protein p62 was degraded much later. The results suggest that degradation of POM121 may be an important early step in propagation of nuclear apoptosis.

scholarly journals Optimised insert design for improved single-molecule imaging and quantification through CRISPR-Cas9 mediated knock-in

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Abdullah O. Khan ◽  
Carl W. White ◽  
Jeremy A. Pike ◽  
Jack Yule ◽  
Alexandre Slater ◽  
...  
Keyword(s):  
Genome Editing ◽  
G Protein ◽  
Single Molecule ◽  
Protein Function ◽  
Single Molecule Imaging ◽  
Dependent Effect ◽  
Systematic Comparison ◽  
Selection Strategies ◽  
Localisation Microscopy ◽  
G Protein Coupled

Abstract The use of CRISPR-Cas9 genome editing to introduce endogenously expressed tags has the potential to address a number of the classical limitations of single molecule localisation microscopy. In this work we present the first systematic comparison of inserts introduced through CRISPR-knock in, with the aim of optimising this approach for single molecule imaging. We show that more highly monomeric and codon optimised variants of mEos result in improved expression at the TubA1B locus, despite the use of identical guides, homology templates, and selection strategies. We apply this approach to target the G protein-coupled receptor (GPCR) CXCR4 and show a further insert dependent effect on expression and protein function. Finally, we show that compared to over-expressed CXCR4, endogenously labelled samples allow for accurate single molecule quantification on ligand treatment. This suggests that despite the complications evident in CRISPR mediated labelling, the development of CRISPR-PALM has substantial quantitative benefits.

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