scholarly journals Two mechanisms coordinate the recruitment of the chromosomal passenger complex to the plane of cell division

2017 ◽  
Vol 28 (25) ◽  
pp. 3634-3646 ◽  
Author(s):  
Jennifer Landino ◽  
Stephen R. Norris ◽  
Muyi Li ◽  
Edward R. Ballister ◽  
Michael A. Lampson ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Cleavage Plane ◽  
Mitotic Exit ◽  
Actin Binding ◽  
Alternative Mechanism ◽  
Dependent Manner ◽  
Chromosomal Passenger Complex ◽  
Division Plane ◽  
Chromosomal Passenger

During cytokinesis, the chromosomal passenger complex (CPC) promotes midzone organization, specifies the cleavage plane, and regulates furrow contractility. The localizations of the CPC are coupled to its cytokinetic functions. At the metaphase-to-anaphase transition, the CPC dissociates from centromeres and localizes to midzone microtubules and the equatorial cortex. CPC relocalization to the cell middle is thought to depend on MKlp2-driven, plus end–directed transport. In support of this idea, MKlp2 depletion impairs cytokinesis; however, cytokinesis failure stems from furrow regression rather than failed initiation of furrowing. This suggests that an alternative mechanism(s) may concentrate the CPC at the division plane. We show here that direct actin binding, via the inner centromere protein (INCENP), enhances CPC enrichment at the equatorial cortex, thus acting in tandem with MKlp2. INCENP overexpression rescues furrowing in MKlp2-depleted cells in an INCENP-actin binding–dependent manner. Using live-cell imaging, we also find that MKlp2-dependent targeting of the CPC is biphasic. MKlp2 targets the CPC to the anti-parallel microtubule overlap of the midzone, after which the MKlp2-CPC complex moves in a nondirected manner. Collectively, our work suggests that both actin binding and MKlp2-dependent midzone targeting cooperate to precisely position the CPC during mitotic exit, and that these pathways converge to ensure successful cleavage furrow ingression.

scholarly journals Myosin-independent cytokinesis inGiardiautilizes flagella to coordinate force generation and direct membrane trafficking

2017 ◽  
Vol 114 (29) ◽  
pp. E5854-E5863 ◽  
Author(s):  
William R. Hardin ◽  
Renyu Li ◽  
Jason Xu ◽  
Andrew M. Shelton ◽  
Germain C. M. Alas ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Myosin Ii ◽  
Live Cell ◽  
Actin Binding ◽  
Alternative Mechanism ◽  
Membrane Tension ◽  
Contractile Ring

Devoid of all known canonical actin-binding proteins, the prevalent parasiteGiardia lambliauses an alternative mechanism for cytokinesis. Unique aspects of this mechanism can potentially be leveraged for therapeutic development. Here, live-cell imaging methods were developed forGiardiato establish division kinetics and the core division machinery. Surprisingly,Giardiacytokinesis occurred with a median time that is ∼60 times faster than mammalian cells. In contrast to cells that use a contractile ring, actin was not concentrated in the furrow and was not directly required for furrow progression. Live-cell imaging and morpholino depletion of axonemal Paralyzed Flagella 16 indicated that flagella-based forces initiated daughter cell separation and provided a source for membrane tension. Inhibition of membrane partitioning blocked furrow progression, indicating a requirement for membrane trafficking to support furrow advancement. Rab11 was found to load onto the intracytoplasmic axonemes late in mitosis and to accumulate near the ends of nascent axonemes. These developing axonemes were positioned to coordinate trafficking into the furrow and mark the center of the cell in lieu of a midbody/phragmoplast. We show that flagella motility, Rab11, and actin coordination are necessary for proper abscission. Organisms representing three of the five eukaryotic supergroups lack myosin II of the actomyosin contractile ring. These results support an emerging view that flagella play a central role in cell division among protists that lack myosin II and additionally implicate the broad use of membrane tension as a mechanism to drive abscission.

scholarly journals LRRK2 mediates tubulation and vesicle sorting from membrane damaged lysosomes

2020 ◽  
Author(s):  
Luis Bonet-Ponce ◽  
Alexandra Beilina ◽  
Chad D. Williamson ◽  
Eric Lindberg ◽  
Jillian H. Kluss ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Super Resolution ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Leucine Rich Repeat ◽  
Biological Functions ◽  
New Process ◽  
Sporadic Parkinson’S Disease

ABSTRACTMutations in the leucine rich repeat kinase 2 (LRRK2) gene are a cause of familial and sporadic Parkinson’s disease (PD). Nonetheless, the biological functions of LRRK2 remain incompletely understood. Here, we observed that LRRK2 is recruited to lysosomes that have a ruptured membrane. Using unbiased proteomics, we observed that LRRK2 is able to recruit the motor adaptor protein JIP4 to permeabilized lysosomes in a kinase-dependent manner through the phosphorylation of RAB35 and RAB10. Super-resolution live cell imaging microscopy and FIB-SEM revealed that once at the lysosomal membrane, JIP4 promotes the formation of LAMP1-negative lysosomal tubules that release membranous content from ruptured lysosomes. Released vesicular structures are able to interact with other lysosomes. Thus, we described a new process that uses lysosomal tubulation to release vesicular structures from permeabilized lysosomes. LRRK2 orchestrates this process that we name LYTL (LYsosomal Tubulation/sorting driven by LRRK2) that, given the central role of the lysosome in PD, is likely to be disease relevant.

scholarly journals F-Actin Dynamics in Neurospora crassa

2010 ◽  
Vol 9 (4) ◽  
pp. 547-557 ◽  
Author(s):  
Adokiye Berepiki ◽  
Alexander Lichius ◽  
Jun-Ya Shoji ◽  
Jens Tilsner ◽  
Nick D. Read
Keyword(s):  
Neurospora Crassa ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Fluorescent Protein ◽  
Live Cell ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Content Type ◽  
Actin Cables ◽  
Germ Tubes

ABSTRACT This study demonstrates the utility of Lifeact for the investigation of actin dynamics in Neurospora crassa and also represents the first report of simultaneous live-cell imaging of the actin and microtubule cytoskeletons in filamentous fungi. Lifeact is a 17-amino-acid peptide derived from the nonessential Saccharomyces cerevisiae actin-binding protein Abp140p. Fused to green fluorescent protein (GFP) or red fluorescent protein (TagRFP), Lifeact allowed live-cell imaging of actin patches, cables, and rings in N. crassa without interfering with cellular functions. Actin cables and patches localized to sites of active growth during the establishment and maintenance of cell polarity in germ tubes and conidial anastomosis tubes (CATs). Recurrent phases of formation and retrograde movement of complex arrays of actin cables were observed at growing tips of germ tubes and CATs. Two populations of actin patches exhibiting slow and fast movement were distinguished, and rapid (1.2 μm/s) saltatory transport of patches along cables was observed. Actin cables accumulated and subsequently condensed into actin rings associated with septum formation. F-actin organization was markedly different in the tip regions of mature hyphae and in germ tubes. Only mature hyphae displayed a subapical collar of actin patches and a concentration of F-actin within the core of the Spitzenkörper. Coexpression of Lifeact-TagRFP and β-tubulin–GFP revealed distinct but interrelated localization patterns of F-actin and microtubules during the initiation and maintenance of tip growth.

scholarly journals A lateral protrusion latticework connects neuroepithelial cells and is regulated during neurogenesis

2021 ◽  
Author(s):  
Ioannis Kasioulis ◽  
Alwyn Dady ◽  
John James ◽  
Alan R Prescott ◽  
Pamela A Halley ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Cell Signalling ◽  
Actin Binding ◽  
Cell Contact ◽  
Tissue Integrity ◽  
Neuroepithelial Cells ◽  
Membrane Contacts ◽  
New Form

Dynamic contacts between cells within the developing neuroepithelium are poorly understood but play important roles in cell and tissue morphology and cell signalling. Here, using live-cell imaging and electron microscopy we reveal multiple distinct protrusive structures in chicken neuroepithelial apical endfeet, including sub-apical protrusions that extend laterally within the tissue, and observe similar structures in human neuroepithelium. We characterise the dynamics, shape, and cytoskeleton of these lateral protrusions and distinguish these structures from cytonemes/filopodia and tunnelling nanotubes. We demonstrate that lateral protrusions form a latticework of membrane contacts between non-adjacent cells, depend on actin but not microtubule dynamics and provide a lamellipodial-like platform for further extending fine actin-dependent filipodia. We find that lateral protrusions depend on the actin-binding protein WAVE1: mutant-WAVE1 misexpression attenuated protrusion and generated a round-ended apical endfoot morphology. However, this did not alter apico-basal cell polarity nor reduce tissue integrity. During normal neuronal delamination sub-apical protrusions were withdrawn, but mutant-WAVE1-induced precocious protrusion loss was insufficient to trigger neurogenesis. This study uncovers a new form of cell-cell contact within the developing neuroepithelium regulation of which prefigures neuronal delamination.

scholarly journals EB1 enables spindle microtubules to regulate centromeric recruitment of Aurora B

2014 ◽  
Vol 204 (6) ◽  
pp. 947-963 ◽  
Author(s):  
Budhaditya Banerjee ◽  
Cortney A. Kestner ◽  
P. Todd Stukenberg
Keyword(s):  
Mitotic Chromosome ◽  
Histone H3 ◽  
Aurora B ◽  
Dependent Manner ◽  
Histone H2a ◽  
Aurora B Kinase ◽  
Chromosomal Passenger Complex ◽  
Checkpoint Signaling ◽  
Chromosomal Passenger ◽  
Spindle Microtubules

The Aurora B kinase coordinates kinetochore–microtubule attachments with spindle checkpoint signaling on each mitotic chromosome. We find that EB1, a microtubule plus end–tracking protein, is required to enrich Aurora B at inner centromeres in a microtubule-dependent manner. This regulates phosphorylation of both kinetochore and chromatin substrates. EB1 regulates the histone phosphorylation marks (histone H2A phospho-Thr120 and histone H3 phospho-Thr3) that localize Aurora B. The chromosomal passenger complex containing Aurora B can be found on a subset of spindle microtubules that exist near prometaphase kinetochores, known as preformed K-fibers (kinetochore fibers). Our data suggest that EB1 enables the spindle microtubules to regulate the phosphorylation of kinetochores through recruitment of the Aurora B kinase.

scholarly journals The kinesin KIF1C transports APC-dependent mRNAs to cell protrusions

2020 ◽  
Author(s):  
Xavier Pichon ◽  
Konstadinos Moissoglu ◽  
Emeline Coleno ◽  
Tianhong Wang ◽  
Arthur Imbert ◽  
...  
Keyword(s):  
Cell Migration ◽  
Mammalian Cells ◽  
Live Cell Imaging ◽  
Feedback Loop ◽  
Cell Imaging ◽  
Rna Localization ◽  
Dependent Manner ◽  
Rna Transport ◽  
Cellular Functions ◽  
Transport Pathway

AbstractRNA localization and local translation are important for numerous cellular functions. In mammals, a class of mRNAs localize to cytoplasmic protrusions in an APC-dependent manner, with roles during cell migration. Here, we investigated this localization mechanism. We found that the KIF1C motor interacts with APC-dependent mRNAs and is required for their localization. Live cell imaging revealed rapid, active transport of single mRNAs over long distances that requires both microtubules and KIF1C. Two color imaging directly showed single mRNAs transported by single KIF1C motors, with the 3’UTR being sufficient to trigger KIF1C-dependent RNA transport and localization. Moreover, KIF1C remained associated with peripheral, multimeric RNA clusters and was required for their formation. These results reveal an RNA transport pathway in mammalian cells, in which the KIF1C motor has a dual role both in transporting RNAs and in promoting their clustering within cytoplasmic protrusions. Interestingly, KIF1C also transports its own mRNA suggesting a possible feedback loop acting at the level of mRNA transport.

scholarly journals Adipose Stem Cell-Derived Extracellular Vesicles Induce Proliferation of Schwann Cells via Internalization

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 163 ◽  
Author(s):  
Maximilian Haertinger ◽  
Tamara Weiss ◽  
Anda Mann ◽  
Annette Tabi ◽  
Victoria Brandel ◽  
...  
Keyword(s):  
Image Analysis ◽  
Stem Cell ◽  
Extracellular Vesicles ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Automated Image Analysis ◽  
Dependent Manner ◽  
Adipose Stem Cell ◽  
Silica Beads

Recent studies showed a beneficial effect of adipose stem cell-derived extracellular vesicles (ADSC-EVs) on sciatic nerve repair, presumably through Schwann cell (SC) modulation. However, it has not yet been elucidated whether ADSC-EVs exert this supportive effect on SCs by extracellular receptor binding, fusion to the SC membrane, or endocytosis mediated internalization. ADSCs, ADSC-EVs, and SCs were isolated from rats and characterized according to associated marker expression and properties. The proliferation rate of SCs in response to ADSC-EVs was determined using a multicolor immunofluorescence staining panel followed by automated image analysis. SCs treated with ADSC-EVs and silica beads were further investigated by 3-D high resolution confocal microscopy and live cell imaging. Our findings demonstrated that ADSC-EVs significantly enhanced the proliferation of SCs in a time- and dose-dependent manner. 3-D image analysis revealed a perinuclear location of ADSC-EVs and their accumulation in vesicular-like structures within the SC cytoplasm. Upon comparing intracellular localization patterns of silica beads and ADSC-EVs in SCs, we found striking resemblance in size and distribution. Live cell imaging visualized that the uptake of ADSC-EVs preferentially took place at the SC processes from which the EVs were transported towards the nucleus. This study provided first evidence for an endocytosis mediated internalization of ADSC-EVs by SCs and underlines the therapeutic potential of ADSC-EVs in future approaches for nerve regeneration.

scholarly journals KV1.5–KVβ1.3 Recycling Is PKC-Dependent

2021 ◽  
Vol 22 (3) ◽  
pp. 1336
Author(s):  
Alvaro Macias ◽  
Alicia de la Cruz ◽  
Diego A. Peraza ◽  
Angela de Benito-Bueno ◽  
Teresa Gonzalez ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Hek293 Cells ◽  
Dependent Manner ◽  
Fast Inactivation ◽  
Patch Clamp Technique ◽  
Relevant Issue ◽  
Regulatory Subunits

KV1.5 channel function is modified by different regulatory subunits. KVβ1.3 subunits assemble with KV1.5 channels and induce a fast and incomplete inactivation. Inhibition of PKC abolishes the KVβ1.3-induced fast inactivation, decreases the amplitude of the current KV1.5–KVβ1.3 and modifies their pharmacology likely due to changes in the traffic of KV1.5–KVβ1.3 channels in a PKC-dependent manner. In order to analyze this hypothesis, HEK293 cells were transfected with KV1.5–KVβ1.3 channels, and currents were recorded by whole-cell configuration of the patch-clamp technique. The presence of KV1.5 in the membrane was analyzed by biotinylation techniques, live cell imaging and confocal microscopy approaches. PKC inhibition resulted in a decrease of 33 ± 7% of channels in the cell surface due to reduced recycling to the plasma membrane, as was confirmed by confocal microscopy. Live cell imaging indicated that PKC inhibition almost abolished the recycling of the KV1.5–KVβ1.3 channels, generating an accumulation of channels into the cytoplasm. All these results suggest that the trafficking regulation of KV1.5–KVβ1.3 channels is dependent on phosphorylation by PKC and, therefore, they could represent a clinically relevant issue, mainly in those diseases that exhibit modifications in PKC activity.

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