scholarly journals Intrinsic polarization cues interfere with pheromone gradient sensing in S. cerevisiae

2018 ◽  
Author(s):  
Gustavo Vasen ◽  
Alejandro Colman Lerner
Keyword(s):  
Spatial Cues ◽  
Gradient Sensing ◽  
Intrinsic Polarization ◽  
Small G Protein ◽  
Complex Functions ◽  
Live Cell Microscopy ◽  
Internal Polarity ◽  
Cell Microscopy ◽  
Mating Projection ◽  
Better Than

Polarity decisions are central to many processes, including mitosis and chemotropism. In S. cerevisiae, budding and mating projection (MP) formation use an overlapping system of cortical landmarks that converge on the small G-protein Cdc42. However, pheromone gradient sensing must override the Rsr1-dependent internal polarity cues used for budding. Using this model system, we asked what happens when intrinsic and extrinsic spatial cues are misaligned. Is there competition, or collaboration? By live cell microscopy and microfluidics technics we uncovered three previously overlooked features of this signaling system. First, the cytokinesis-associated polarization patch serves as a polarity landmark independently of all known cues. Second, the Rax1-Rax2 complex functions as novel pheromone promoted polarity cue in the distal pole of the cells. Finally, we showed that internal cues remain active during pheromone gradient tracking and that they interfere with this process biasing the location of MPs, since yeast defective in internal cue utilization align significantly better than wild- type with artificially generated pheromone gradients.

scholarly journals Mitotic and pheromone-specific intrinsic polarization cues interfere with gradient sensing inSaccharomyces cerevisiae

2020 ◽  
Vol 117 (12) ◽  
pp. 6580-6589 ◽  
Author(s):  
Gustavo Vasen ◽  
Paula Dunayevich ◽  
Alejandro Colman-Lerner
Keyword(s):  
Spatial Cues ◽  
Gradient Sensing ◽  
Intrinsic Polarization ◽  
Small G Protein ◽  
Complex Functions ◽  
Live Cell Microscopy ◽  
Internal Polarity ◽  
Cell Microscopy ◽  
Mating Projection ◽  
Better Than

Polarity decisions are central to many processes, including mitosis and chemotropism. InSaccharomyces cerevisiae, budding and mating projection (MP) formation use an overlapping system of cortical landmarks that converges on the small G protein Cdc42. However, pheromone-gradient sensing must override the Rsr1-dependent internal polarity cues used for budding. Using this model system, we asked what happens when intrinsic and extrinsic spatial cues are not aligned. Is there competition, or collaboration? By live-cell microscopy and microfluidics techniques, we uncovered three previously overlooked features of this signaling system. First, the cytokinesis-associated polarization patch serves as a polarity landmark independently of all known cues. Second, the Rax1-Rax2 complex functions as a pheromone-promoted polarity cue in the distal pole of the cells. Third, internal cues remain active during pheromone-gradient tracking and can interfere with this process, biasing the location of MPs. Yeast defective in internal-cue utilization align significantly better than wild type with artificially generated pheromone gradients.

scholarly journals Cooperative 4Pi Excitation and Detection Yields Sevenfold Sharper Optical Sections in Live-Cell Microscopy

2004 ◽  
Vol 87 (6) ◽  
pp. 4146-4152 ◽  
Author(s):  
Hilmar Gugel ◽  
Jörg Bewersdorf ◽  
Stefan Jakobs ◽  
Johann Engelhardt ◽  
Rafael Storz ◽  
...  
Keyword(s):  
Live Cell ◽  
Live Cell Microscopy ◽  
Cell Microscopy

scholarly journals Live-cell microscopy - tips and tools

2009 ◽  
Vol 122 (6) ◽  
pp. 753-767 ◽  
Author(s):  
M. M. Frigault ◽  
J. Lacoste ◽  
J. L. Swift ◽  
C. M. Brown
Keyword(s):  
Live Cell ◽  
Live Cell Microscopy ◽  
Cell Microscopy

scholarly journals Klp2 and Ase1 synergize to maintain meiotic spindle stability during metaphase I

2020 ◽  
Author(s):  
Fan Zheng ◽  
Fenfen Dong ◽  
Shuo Yu ◽  
Tianpeng Li ◽  
Yanze Jian ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Yeast Cells ◽  
Meiotic Spindle ◽  
Homologous Chromosomes ◽  
Spindle Dynamics ◽  
Live Cell Microscopy ◽  
Spindle Stability ◽  
Cell Microscopy ◽  
Mitosis And Meiosis ◽  
Meiosis I

ABSTRACTThe spindle apparatus segregates bi-oriented sister chromatids during mitosis but mono-oriented homologous chromosomes during meiosis I. It has remained unclear if similar molecular mechanisms operate to regulate spindle dynamics during mitosis and meiosis I. Here, we employed live-cell microscopy to compare the spindle dynamics of mitosis and meiosis I in fission yeast cells and demonstrated that the conserved kinesin-14 motor Klp2 plays a specific role in maintaining metaphase spindle length during meiosis I, but not during mitosis. Moreover, the maintenance of metaphase spindle stability during meiosis I requires the synergism between Klp2 and the conserved microtubule crosslinker Ase1 as the absence of both proteins causes exacerbated defects in metaphase spindle stability. The synergism is not necessary for regulating mitotic spindle dynamics. Hence, our work reveals a new molecular mechanism underlying meiotic spindle dynamics and provides insights into understanding differential regulation of meiotic and mitotic events.

scholarly journals Improved Chemical-Genetic Fluorescent Markers for Live Cell Microscopy

Biochemistry ◽  
2018 ◽  
Vol 57 (39) ◽  
pp. 5648-5653 ◽  
Author(s):  
Alison G. Tebo ◽  
Frederico M. Pimenta ◽  
Yu Zhang ◽  
Arnaud Gautier
Keyword(s):  
Live Cell ◽  
Chemical Genetic ◽  
Fluorescent Markers ◽  
Live Cell Microscopy ◽  
Cell Microscopy

Dynamics and Traffic for Transfecting Exogenous MicroRNA as Studied by Live-Cell Microscopy

2021 ◽  
Vol 17 (8) ◽  
pp. 1647-1653
Author(s):  
Ke Yang ◽  
Yuanyuan Wang ◽  
Bo Sun ◽  
Tian Tian ◽  
Zhu Dai ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Small Region ◽  
Single Particle Tracking ◽  
Live Cell ◽  
Calculation Results ◽  
Long Time ◽  
Live Cell Microscopy ◽  
Cell Microscopy

MicroRNA (miRNA) has emerged as an important gene-regulator that shows great potential in gene therapy because of its unique roles in gene-regulation. However, the knowledge on their function and transportation in vivo is still lacking, and there are limited obvious evidences to define intracellular transportation of miRNA. In this study, the dynamics of exogenous miR-21 transfected into HeLa cells was traced by live-cell microscopy. Their transportation at key time points was recorded and dynamic properties were analyzed by single particle tracking (SPT) and mean square displacement (MSD) calculation. Results showed that the exogenous miRNAs bounded to cells quickly and went through lysosome into cytosol, where they were subsequently recruited into p-body. They finally were degraded, otherwise went back to cytosol in some way. Long time observation and analysis of motion mode showed that the miRNAs were confined in a small region and their motion modes were flexible in different intracellular microenvironment after entering the cells.

scholarly journals Direct lysosome-based autophagy of lipid droplets in hepatocytes

2020 ◽  
Vol 117 (51) ◽  
pp. 32443-32452
Author(s):  
Ryan J. Schulze ◽  
Eugene W. Krueger ◽  
Shaun G. Weller ◽  
Katherine M. Johnson ◽  
Carol A. Casey ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Lipid Droplets ◽  
Critical Role ◽  
Specific Protein ◽  
Lipid Homeostasis ◽  
Dynamic Interactions ◽  
Double Membrane ◽  
Live Cell Microscopy ◽  
Cell Microscopy

Hepatocytes metabolize energy-rich cytoplasmic lipid droplets (LDs) in the lysosome-directed process of autophagy. An organelle-selective form of this process (macrolipophagy) results in the engulfment of LDs within double-membrane delimited structures (autophagosomes) before lysosomal fusion. Whether this is an exclusive autophagic mechanism used by hepatocytes to catabolize LDs is unclear. It is also unknown whether lysosomes alone might be sufficient to mediate LD turnover in the absence of an autophagosomal intermediate. We performed live-cell microscopy of hepatocytes to monitor the dynamic interactions between lysosomes and LDs in real-time. We additionally used a fluorescent variant of the LD-specific protein (PLIN2) that exhibits altered fluorescence in response to LD interactions with the lysosome. We find that mammalian lysosomes and LDs undergo interactions during which proteins and lipids can be transferred from LDs directly into lysosomes. Electron microscopy (EM) of primary hepatocytes or hepatocyte-derived cell lines supports the existence of these interactions. It reveals a dramatic process whereby the lipid contents of the LD can be “extruded” directly into the lysosomal lumen under nutrient-limited conditions. Significantly, these interactions are not affected by perturbations to crucial components of the canonical macroautophagy machinery and can occur in the absence of double-membrane lipoautophagosomes. These findings implicate the existence of an autophagic mechanism used by mammalian cells for the direct transfer of LD components into the lysosome for breakdown. This process further emphasizes the critical role of lysosomes in hepatic LD catabolism and provides insights into the mechanisms underlying lipid homeostasis in the liver.

Sign in / Sign up

Export Citation Format

Share Document