scholarly journals Dynein is regulated by the stability of its microtubule track

2017 ◽  
Vol 216 (7) ◽  
pp. 2047-2058 ◽  
Author(s):  
Cassi Estrem ◽  
Colby P. Fees ◽  
Jeffrey K. Moore
Keyword(s):  
Mitotic Spindle ◽  
Living Cells ◽  
High Resolution Imaging ◽  
Primary Role ◽  
Spindle Positioning ◽  
Rich Domain ◽  
Positioning Errors ◽  
Resolution Imaging ◽  
The Stability ◽  
Dynactin Complex

How dynein motors accurately move cargoes is an important question. In budding yeast, dynein moves the mitotic spindle to the predetermined site of cytokinesis by pulling on astral microtubules. In this study, using high-resolution imaging in living cells, we discover that spindle movement is regulated by changes in microtubule plus-end dynamics that occur when dynein generates force. Mutants that increase plus-end stability increase the frequency and duration of spindle movements, causing positioning errors. We find that dynein plays a primary role in regulating microtubule dynamics by destabilizing microtubules. In contrast, the dynactin complex counteracts dynein and stabilizes microtubules through a mechanism involving the shoulder subcomplex and the cytoskeletal-associated protein glycine-rich domain of Nip100/p150glued. Our results support a model in which dynein destabilizes its microtubule substrate by using its motility to deplete dynactin from the plus end. We propose that interplay among dynein, dynactin, and the stability of the microtubule substrate creates a mechanism that regulates accurate spindle positioning.

4-dimensional, high-resolution imaging of living cells

1992 ◽  
Vol 50 (1) ◽  
pp. 416-417
Author(s):  
Shinya Inoué
Keyword(s):  
Light Microscope ◽  
Living Cells ◽  
Live Cells ◽  
Video Tape ◽  
Active Living ◽  
High Resolution Imaging ◽  
3 Dimensional ◽  
Dynamic Architecture ◽  
Resolution Imaging ◽  
Disk Memory

This paper reports progress of our effort to rapidly capture, and display in time-lapsed mode, the 3-dimensional dynamic architecture of active living cells and developing embryos at the highest resolution of the light microscope. Our approach entails: (A) real-time video tape recording of through-focal, ultrathin optical sections of live cells at the highest resolution of the light microscope; (B) repeat of A at time-lapsed intervals; (C) once each time-lapsed interval, an image at home focus is recorded onto Optical Disk Memory Recorder (OMDR); (D) periods of interest are selected using the OMDR and video tape records; (E) selected stacks of optical sections are converted into plane projections representing different view angles (±4 degrees for stereo view, additional angles when revolving stereos are desired); (F) analysis using A - D.

scholarly journals Reversible Cryo-arrests of Living Cells to Pause Molecular Movements for High-resolution Imaging

BIO-PROTOCOL ◽  
2017 ◽  
Vol 7 (8) ◽  
Author(s):  
Jan Huebinger ◽  
Martin Masip ◽  
Jens Christmann ◽  
Frank Wehner ◽  
Philippe Bastiaens
Keyword(s):  
High Resolution ◽  
Living Cells ◽  
High Resolution Imaging ◽  
Resolution Imaging

scholarly journals Dynein-dependent Movements of the Mitotic Spindle inSaccharomyces cerevisiae Do Not Require Filamentous Actin

2000 ◽  
Vol 11 (3) ◽  
pp. 863-872 ◽  
Author(s):  
Richard A. Heil-Chapdelaine ◽  
Nguyen K. Tran ◽  
John A. Cooper
Keyword(s):  
Mitotic Spindle ◽  
Living Cell ◽  
Living Cells ◽  
Cell Populations ◽  
Cell Analysis ◽  
Mitotic Spindles ◽  
Filamentous Actin ◽  
Spindle Positioning ◽  
Latrunculin A ◽  
Two Phases

In budding yeast, the mitotic spindle is positioned in the neck between the mother and the bud so that both cells inherit one nucleus. The movement of the mitotic spindle into the neck can be divided into two phases: (1) Kip3p-dependent movement of the nucleus to the neck and alignment of the short spindle, followed by (2) dynein-dependent movement of the spindle into the neck and oscillation of the elongating spindle within the neck. Actin has been hypothesized to be involved in all these movements. To test this hypothesis, we disrupted the actin cytoskeleton with the use of mutations and latrunculin A (latrunculin). We assayed nuclear segregation in synchronized cell populations and observed spindle movements in individual living cells. In synchronized cell populations, no actin cytoskeletal mutant segregated nuclei as poorly as cells lacking dynein function. Furthermore, nuclei segregated efficiently in latrunculin-treated cells. Individual living cell analysis revealed that the preanaphase spindle was mispositioned and misaligned in latrunculin-treated cells and that astral microtubules were misoriented, confirming a role for filamentous actin in the early, Kip3p-dependent phase of spindle positioning. Surprisingly, mispositioned and misaligned mitotic spindles moved into the neck in the absence of filamentous actin, albeit less efficiently. Finally, dynein-dependent sliding of astral microtubules along the cortex and oscillation of the elongating mitotic spindle in the neck occurred in the absence of filamentous actin.

Detecting and imaging of SO2 derivatives in living cells with zero cross-talk colorimetric mitochondria-targeted fluorescent probe

2020 ◽  
Vol 98 (1) ◽  
pp. 1-6
Author(s):  
Dan Wu ◽  
Shiqi Rong ◽  
Yi Liu ◽  
Fei Zheng ◽  
Yankun Zhao ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Talk ◽  
High Sensitivity ◽  
Living Cells ◽  
High Resolution Imaging ◽  
Biochemical Processes ◽  
Highly Sensitive ◽  
Resolution Imaging ◽  
Low Cytotoxicity

It is well known that excessive levels of sulfur dioxide and its derivatives are connected to diverse diseases. Therefore, developing highly sensitive probes to detect and monitor sulfite in living cells is important for the diagnosis of disease and the study of biochemical processes in vivo. In this report, two zero cross-talk ratiometric fluorescent probes were synthesized (CA-ID-MC and CA-BI-MC), which were derived from carbazole-indolenine π-conjugated system for effective detection of sulfite in living cells. Observably, CA-BI-MC exhibited the largest emission shift of 157 nm from 617 to 460 nm with the addition of various concentrations of sulfite, which is beneficial for high-resolution imaging of the sulfite. CA-BI-MC also exhibits high sensitivity and low cytotoxicity. More importantly, this probe successfully located mitochondria and sensed the sulfite in HeLa cells caused by exogenous stimulation.

scholarly journals Dynein-Driven Mitotic Spindle Positioning Restricted to Anaphase by She1p Inhibition of Dynactin Recruitment

2009 ◽  
Vol 20 (13) ◽  
pp. 3003-3011 ◽  
Author(s):  
Jeffrey B. Woodruff ◽  
David G. Drubin ◽  
Georjana Barnes
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Cell Cycle Regulation ◽  
Regulatory Mechanism ◽  
Present Evidence ◽  
Spindle Positioning ◽  
Dynein Motor ◽  
Microtubule Motor ◽  
Cycle Regulation ◽  
Dynactin Complex

Dynein is a minus-end–directed microtubule motor important for mitotic spindle positioning. In budding yeast, dynein activity is restricted to anaphase when the nucleus enters the bud neck, yet the nature of the underlying regulatory mechanism is not known. Here, the microtubule-associated protein She1p is identified as a novel regulator of dynein activity. In she1Δ cells, dynein is activated throughout the cell cycle, resulting in aberrant spindle movements that misposition the spindle. We also found that dynactin, a cofactor essential for dynein motor function, is a dynamic complex whose recruitment to astral microtubules (aMTs) increases dramatically during anaphase. Interestingly, loss of She1p eliminates the cell-cycle regulation of dynactin recruitment and permits enhanced dynactin accumulation on aMTs throughout the cell cycle. Furthermore, localization of the dynactin complex to aMTs requires dynein, suggesting that dynactin is recruited to aMTs via interaction with dynein and not the microtubule itself. Lastly, we present evidence supporting the existence of an incomplete dynactin subcomplex localized at the SPB, and a complete complex that is loaded onto aMTs from the cytoplasm. We propose that She1p restricts dynein-dependent spindle positioning to anaphase by inhibiting the association of dynein with the complete dynactin complex.

Clustering, Jamming and Segregation in Cohesive Granular Materials

2002 ◽  
Author(s):  
Azadeh Samadani ◽  
Daniel L. Blair ◽  
A. Kudrolli
Keyword(s):  
High Speed ◽  
Inelastic Collisions ◽  
Angle Of Repose ◽  
High Resolution Imaging ◽  
Magnetic Attraction ◽  
Granular Pile ◽  
Resolution Imaging ◽  
Fluidized System ◽  
Series Of Experiments ◽  
The Stability

We present a series of experiments to investigate the stability, flow and segregation when liquid bridges or magnetic attraction forces between grains are present. Quantitative data is obtained by high speed and high resolution imaging. First, we measure the angle of repose of a granular pile formed by pouring wet grains in to a quasi-two dimensional silo and compare them to existing models. Second, we measure the size separation of bi-disperse grains as a function of size ratio and viscosity of the liquid. Finally, we introduce a vibro-fluidized system of magnetized particles to study the effect of cohesive forces and inelastic collisions on the formation of clusters and velocity distributions.

scholarly journals MISP is a novel Plk1 substrate required for proper spindle orientation and mitotic progression

2013 ◽  
Vol 200 (6) ◽  
pp. 773-787 ◽  
Author(s):  
Mei Zhu ◽  
Florian Settele ◽  
Sachin Kotak ◽  
Luis Sanchez-Pulido ◽  
Lena Ehret ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Cell Cortex ◽  
Mitotic Progression ◽  
Uncharacterized Protein ◽  
Spindle Positioning ◽  
Pulling Forces ◽  
A Subunit ◽  
Division Axis ◽  
Dynactin Complex ◽  
Cortical Distribution

Precise positioning of the mitotic spindle determines the correct cell division axis and is crucial for organism development. Spindle positioning is mediated through a cortical machinery by capturing astral microtubules, thereby generating pushing/pulling forces at the cell cortex. However, the molecular link between these two structures remains elusive. Here we describe a previously uncharacterized protein, MISP (C19orf21), as a substrate of Plk1 that is required for correct mitotic spindle positioning. MISP is an actin-associated protein throughout the cell cycle. MISP depletion led to an impaired metaphase-to-anaphase transition, which depended on phosphorylation by Plk1. Loss of MISP induced mitotic defects including spindle misorientation accompanied by shortened astral microtubules. Furthermore, we find that MISP formed a complex with and regulated the cortical distribution of the +TIP binding protein p150glued, a subunit of the dynein–dynactin complex. We propose that Plk1 phosphorylates MISP, thus stabilizing cortical and astral microtubule attachments required for proper mitotic spindle positioning.

Sign in / Sign up

Export Citation Format

Share Document