scholarly journals F-pili dynamics by live-cell imaging

2008 ◽  
Vol 105 (46) ◽  
pp. 17978-17981 ◽  
Author(s):  
Margaret Clarke ◽  
Lucinda Maddera ◽  
Robin L. Harris ◽  
Philip M. Silverman
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Recipient Cell ◽  
Cell Communication ◽  
Live Cell ◽  
Cell Contact ◽  
Gram Negative Bacteria ◽  
Donor Cells ◽  
Cell Cell

Bacteria have evolved numerous mechanisms for cell–cell communication, many of which have important consequences for human health. Among these is conjugation, the direct transfer of DNA from one cell to another. For Gram-negative bacteria, conjugation requires thin, flexible filaments (conjugative pili) that are elaborated by DNA donor cells. The structure, function, and especially the dynamics of conjugative pili are poorly understood. Here, we have applied live-cell imaging to characterize the dynamics of F-pili (conjugative pili encoded by the F plasmid of Escherichia coli). We establish that F-pili normally undergo cycles of extension and retraction in the absence of any obvious triggering event, such as contact with a recipient cell. When made, such contacts are able to survive the shear forces felt by bacteria in liquid media. Our data emphasize the role of F-pilus flexibility both in efficiently sampling a large volume surrounding donor cells in liquid culture and in establishing and maintaining cell–cell contact. Additionally and unexpectedly, we infer that extension and retraction are accompanied by rotation about the long axis of the filament.

scholarly journals EB1 binding restricts STIM1 translocation to ER–PM junctions and regulates store-operated Ca2+ entry

2018 ◽  
Vol 217 (6) ◽  
pp. 2047-2058 ◽  
Author(s):  
Chi-Lun Chang ◽  
Yu-Ju Chen ◽  
Carlo Giovanni Quintanilla ◽  
Ting-Sung Hsieh ◽  
Jen Liou
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Cellular Functions ◽  
Binding Ability ◽  
Trapping Mechanism ◽  
Spatiotemporal Regulation

The endoplasmic reticulum (ER) Ca2+ sensor STIM1 forms oligomers and translocates to ER–plasma membrane (PM) junctions to activate store-operated Ca2+ entry (SOCE) after ER Ca2+ depletion. STIM1 also interacts with EB1 and dynamically tracks microtubule (MT) plus ends. Nevertheless, the role of STIM1–EB1 interaction in regulating SOCE remains unresolved. Using live-cell imaging combined with a synthetic construct approach, we found that EB1 binding constitutes a trapping mechanism restricting STIM1 targeting to ER–PM junctions. We further showed that STIM1 oligomers retain EB1 binding ability in ER Ca2+-depleted cells. By trapping STIM1 molecules at dynamic contacts between the ER and MT plus ends, EB1 binding delayed STIM1 translocation to ER–PM junctions during ER Ca2+ depletion and prevented excess SOCE and ER Ca2+ overload. Our study suggests that STIM1–EB1 interaction shapes the kinetics and amplitude of local SOCE in cellular regions with growing MTs and contributes to spatiotemporal regulation of Ca2+ signaling crucial for cellular functions and homeostasis.

Lipid order and molecular assemblies in the plasma membrane of eukaryotic cells

2009 ◽  
Vol 37 (5) ◽  
pp. 1056-1060 ◽  
Author(s):  
Marek Cebecauer ◽  
Dylan M. Owen ◽  
Anna Markiewicz ◽  
Anthony I. Magee
Keyword(s):  
Plasma Membrane ◽  
Physical Properties ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Eukaryotic Cells ◽  
Dynamic Nature ◽  
Membrane Components ◽  
Technological Improvements

Multimolecular assemblies on the plasma membrane exhibit dynamic nature and are often generated during the activation of eukaryotic cells. The role of lipids and their physical properties in helping to control the existence of these structures is discussed. Technological improvements for live cell imaging of membrane components are also reviewed.

scholarly journals A novel live-cell imaging assay reveals regulation of endosome maturation

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maria Podinovskaia ◽  
Cristina Prescianotto-Baschong ◽  
Dominik P Buser ◽  
Anne Spang
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Cell Communication ◽  
Cell Types ◽  
Cellular Systems ◽  
Live Cell ◽  
Recycling Endosome ◽  
Endosomal Acidification ◽  
Turn Over ◽  
Endosome Maturation

Cell-cell communication is an essential process in life, with endosomes acting as key organelles for regulating uptake and secretion of signaling molecules. Endocytosed material is accepted by the sorting endosome where it either is sorted for recycling or remains in the endosome as it matures to be degraded in the lysosome. Investigation of the endosome maturation process has been hampered by the small size and rapid movement of endosomes in most cellular systems. Here, we report an easy versatile live-cell imaging assay to monitor endosome maturation kinetics, which can be applied to a variety of mammalian cell types. Acute ionophore treatment led to enlarged early endosomal compartments that matured into late endosomes and fused with lysosomes to form endolysosomes. Rab5-to-Rab7 conversion and PI(3)P formation and turn over were recapitulated with this assay and could be observed with a standard widefield microscope. We used this approach to show that Snx1 and Rab11-positive recycling endosome recruitment occurred throughout endosome maturation and was uncoupled from Rab conversion. In contrast, efficient endosomal acidification was dependent on Rab conversion. The assay provides a powerful tool to further unravel various aspects of endosome maturation.

Role of Doc2α in dense-core vesicle exocytosis in PC12 cells revealed by live cell imaging

2011 ◽  
Vol 71 ◽  
pp. e213
Author(s):  
Takashi Tsuboi ◽  
Yasunori Mori ◽  
Hideki Matsui ◽  
Ryo Aoki ◽  
Manami Oya ◽  
...  
Keyword(s):  
Pc12 Cells ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Vesicle Exocytosis

scholarly journals Role of cytoplasmic dynein in the axonal transport of microtubules and neurofilaments

2005 ◽  
Vol 168 (5) ◽  
pp. 697-703 ◽  
Author(s):  
Yan He ◽  
Franto Francis ◽  
Kenneth A. Myers ◽  
Wenqian Yu ◽  
Mark M. Black ◽  
...  
Keyword(s):  
Rna Interference ◽  
Axonal Transport ◽  
Heavy Chain ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Sympathetic Neurons ◽  
Cytoplasmic Dynein ◽  
Live Cell ◽  
Cytoskeletal Elements

Recent studies have shown that the transport of microtubules (MTs) and neurofilaments (NFs) within the axon is rapid, infrequent, asynchronous, and bidirectional. Here, we used RNA interference to investigate the role of cytoplasmic dynein in powering these transport events. To reveal transport of MTs and NFs, we expressed EGFP-tagged tubulin or NF proteins in cultured rat sympathetic neurons and performed live-cell imaging of the fluorescent cytoskeletal elements in photobleached regions of the axon. The occurrence of anterograde MT and retrograde NF movements was significantly diminished in neurons that had been depleted of dynein heavy chain, whereas the occurrence of retrograde MT and anterograde NF movements was unaffected. These results support a cargo model for NF transport and a sliding filament model for MT transport.

scholarly journals ARL3 activation requires the co-GEF BART and effector-mediated turnover

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Yasmin ElMaghloob ◽  
Begoña Sot ◽  
Michael J McIlwraith ◽  
Esther Garcia ◽  
Tamas Yelland ◽  
...  
Keyword(s):  
G Protein ◽  
Primary Cilium ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Guanine Exchange Factor ◽  
Bona Fide ◽  
Modified Proteins ◽  
Adp Ribosylation Factor

The ADP-ribosylation factor-like 3 (ARL3) is a ciliopathy G-protein which regulates the ciliary trafficking of several lipid-modified proteins. ARL3 is activated by its guanine exchange factor (GEF) ARL13B via an unresolved mechanism. BART is described as an ARL3 effector which has also been implicated in ciliopathies, although the role of its ARL3 interaction is unknown. Here, we show that, at physiological GTP:GDP levels, human ARL3GDP is weakly activated by ARL13B. However, BART interacts with nucleotide-free ARL3 and, in concert with ARL13B, efficiently activates ARL3. In addition, BART binds ARL3GTP and inhibits GTP dissociation, thereby stabilising the active G-protein; the binding of ARL3 effectors then releases BART. Finally, using live cell imaging, we show that BART accesses the primary cilium and colocalises with ARL13B. We propose a model wherein BART functions as a bona fide co-GEF for ARL3 and maintains the active ARL3GTP, until it is recycled by ARL3 effectors.

The role of hemidesmosomes and focal contacts in the skin visualized by dual-color live cell imaging

2014 ◽  
Vol 47 (4) ◽  
pp. 185-188 ◽  
Author(s):  
Toshiyuki Ozawa ◽  
Sho Hiroyasu ◽  
Daisuke Tsuruta
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Focal Contacts ◽  
Dual Color

scholarly journals Biochemical and structural analysis of α-catenin in cell–cell contacts

2008 ◽  
Vol 36 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Sabine Pokutta ◽  
Frauke Drees ◽  
Soichiro Yamada ◽  
W. James Nelson ◽  
William I. Weis
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Adherens Junction ◽  
Structural Data ◽  
Cell Contact ◽  
Related Protein ◽  
Imaging Studies ◽  
Actin Networks ◽  
Junction Formation ◽  
Cell Cell

Cadherins are transmembrane adhesion molecules that mediate homotypic cell–cell contact. In adherens junctions, the cytoplasmic domain of cadherins is functionally linked to the actin cytoskeleton through a series of proteins known as catenins. E-cadherin binds to β-catenin, which in turn binds to α-catenin to form a ternary complex. α-Catenin also binds to actin, and it was assumed previously that α-catenin links the cadherin–catenin complex to actin. However, biochemical, structural and live-cell imaging studies of the cadherin–catenin complex and its interaction with actin show that binding of β-catenin to α-catenin prevents the latter from binding to actin. Biochemical and structural data indicate that α-catenin acts as an allosteric protein whose conformation and activity changes depending on whether or not it is bound to β-catenin. Initial contacts between cells occur on dynamic lamellipodia formed by polymerization of branched actin networks, a process controlled by the Arp2/3 (actin-related protein 2/3) complex. α-Catenin can suppress the activity of Arp2/3 by competing for actin filaments. These findings lead to a model for adherens junction formation in which clustering of the cadherin–β-catenin complex recruits high levels of α-catenin that can suppress the Arp2/3 complex, leading to cessation of lamellipodial movement and formation of a stable contact. Thus α-catenin appears to play a central role in cell–cell contact formation.

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