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Full-Text Articles in Physics
Microtubule-Severing Enzymes At The Cutting Edge, Jennifer Ross, David J. Sharp
Microtubule-Severing Enzymes At The Cutting Edge, Jennifer Ross, David J. Sharp
Jennifer Ross
ATP-dependent severing of microtubules was first reported in Xenopus laevis egg extracts in 1991. Two years later this observation led to the purification of the first known microtubule-severing enzyme, katanin. Katanin homologs have now been identified throughout the animal kingdom and in plants. Moreover, members of two closely related enzyme subfamilies, spastin and fidgetin, have been found to sever microtubules and might act alongside katanins in some contexts (Roll-Mecak and McNally, 2010; Yu et al., 2008; Zhang et al., 2007). Over the past few years, it has become clear that microtubule-severing enzymes contribute to a wide range of cellular activities …
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Alyssa Gable, Minhua Qui, Janel Titus, Sai Balchand, Nick P. Ferenz, Nan Ma, Elizabeth S. Collins, Carey Fagersrom, Jennifer Ross, Ge Yang, Patricia Wadsworth
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Alyssa Gable, Minhua Qui, Janel Titus, Sai Balchand, Nick P. Ferenz, Nan Ma, Elizabeth S. Collins, Carey Fagersrom, Jennifer Ross, Ge Yang, Patricia Wadsworth
Jennifer Ross
Kinesin-5 is an essential mitotic motor. However, how its spatial–temporal distribution is regulated in mitosis remains poorly understood. We expressed localization and affinity purification–tagged Eg5 from a mouse bacterial artificial chromosome (this construct was called mEg5) and found its distribution to be tightly regulated throughout mitosis. Fluorescence recovery after photobleaching analysis showed rapid Eg5 turnover throughout mitosis, which cannot be accounted for by microtubule turnover. Total internal reflection fluorescence microscopy and high-resolution, single-particle tracking revealed that mEg5 punctae on both astral and midzone microtubules rapidly bind and unbind. mEg5 punctae on midzone microtubules moved transiently both toward and away from …
The Impacts Of Molecular Motor Traffic Jams, Jennifer Ross
The Impacts Of Molecular Motor Traffic Jams, Jennifer Ross
Jennifer Ross
Much of a modern person's day is spent trying to get from point A to point B. So, too, in the cell, much time and energy is expended on shuttling organelles, protein complexes, and mRNA, called “cargos,” from point A to point B. We know that vehicle traffic slows down when roads get jammed with high-volume congestion. The traffic analogy begs the question: Do cellular highways get jammed? This is the question being probed by Leduc et al. in PNAS (1). Efficient cellular transport is made along “cellular highways” in the form of a cytoskeletal network of proteinacous filaments called …
Tpx2 Regulates The Localization And Activity Of Eg5 In The Mammalian Mitotic Spindle, Nan Ma, Janel Titus, Alyssa Gable, Jennifer Ross, Patricia Wadsworth
Tpx2 Regulates The Localization And Activity Of Eg5 In The Mammalian Mitotic Spindle, Nan Ma, Janel Titus, Alyssa Gable, Jennifer Ross, Patricia Wadsworth
Jennifer Ross
Mitotic spindle assembly requires the regulated activity of numerous spindle-associated proteins. In mammalian cells, the Kinesin-5 motor Eg5 interacts with the spindle assembly factor TPX2, but how this interaction contributes to spindle formation and function is not established. Using bacterial artificial chromosome technology, we generated cells expressing TPX2 lacking the Eg5 interaction domain. Spindles in these cells were highly disorganized with multiple spindle poles. The TPX2-Eg5 interaction was required for kinetochore fiber formation and contributed to Eg5 localization to spindle microtubules but not spindle poles. Microinjection of the Eg5-binding domain of TPX2 resulted in spindle elongation, indicating that the interaction …
Loop Formation Of Microtubules During Gliding At High Density, Lynn Liu, Erkan Tuzel, Jennifer Ross
Loop Formation Of Microtubules During Gliding At High Density, Lynn Liu, Erkan Tuzel, Jennifer Ross
Jennifer Ross
The microtubule cytoskeleton, including the associated proteins, forms a complex network essential to multiple cellular processes. Microtubule-associated motor proteins, such as kinesin-1, travel on microtubules to transport membrane bound vesicles across the crowded cell. Other motors, such as cytoplasmic dynein and kinesin-5, are used to organize the cytoskeleton during mitosis. In order to understand the self-organization processes of motors on microtubules, we performed filament-gliding assays with kinesin-1 motors bound to the cover glass with a high density of microtubules on the surface. To observe microtubule organization, 3% of the microtubules were fluorescently labeled to serve as tracers. We find that …
A Switch In Retrograde Signaling From Survival To Stress In Rapid Onset Neurodegeneration, Jennifer Ross, Erika L.F Holzbaur, Robert G. Kalb, Karen E. Wallace, Ram Dixit, Goo-Bo Jeong, Eran Perlson
A Switch In Retrograde Signaling From Survival To Stress In Rapid Onset Neurodegeneration, Jennifer Ross, Erika L.F Holzbaur, Robert G. Kalb, Karen E. Wallace, Ram Dixit, Goo-Bo Jeong, Eran Perlson
Jennifer Ross
Retrograde axonal transport of cellular signals driven by dynein is vital for neuronal survival. Mouse models with defects in the retrograde transport machinery, including the Loa mouse (point mutation in dynein) and the Tgdynamitin mouse (overexpression of dynamitin), exhibit mild neurodegenerative disease. Transport defects have also been observed in more rapidly progressive neurodegeneration, such as that observed in the SOD1G93A transgenic mouse model for familial amyotrophic lateral sclerosis (ALS). Here, we test the hypothesis that alterations in retrograde signaling lead to neurodegeneration. In vivo, in vitro, and live-cell imaging motility assays show misregulation of transport and inhibition of retrograde signaling …
Complementary Dimerization Of Microtubule-Associated Protein Tau: Implications For Microtubule Bundling And Tau-Mediated Pathogensis, Jennifer Ross, Kenneth J. Rosenberg, H. Eric Feinstein, Stuart C. Feinstein, Jacob Israelachvili
Complementary Dimerization Of Microtubule-Associated Protein Tau: Implications For Microtubule Bundling And Tau-Mediated Pathogensis, Jennifer Ross, Kenneth J. Rosenberg, H. Eric Feinstein, Stuart C. Feinstein, Jacob Israelachvili
Jennifer Ross
Tau is an intrinsically unstructured microtubule (MT)-associated protein capable of binding to and organizing MTs into evenly spaced parallel assemblies known as “MT bundles.” How tau achieves MT bundling is enigmatic because each tau molecule possesses only one MT-binding region. To dissect this complex behavior, we have used a surface forces apparatus to measure the interaction forces of the six CNS tau isoforms when bound to mica substrates in vitro. Two types of measurements were performed for each isoform: symmetric configuration experiments measured the interactions between two tau-coated mica surfaces, whereas “asymmetric” experiments examined tau-coated surfaces interacting with a smooth …
A Role For Huntingtin In Dynein/Dynactin-Mediated Vesicle Trafficking, Jennifer Ross, Juliane P. Caviston, Sheila M. Antony, Mariko Tokito, Erika L.F Holzbaur
A Role For Huntingtin In Dynein/Dynactin-Mediated Vesicle Trafficking, Jennifer Ross, Juliane P. Caviston, Sheila M. Antony, Mariko Tokito, Erika L.F Holzbaur
Jennifer Ross
Cytoplasmic dynein is a multisubunit microtubule motor complex that, together with its activator, dynactin, drives vesicular cargo toward the minus ends of microtubules. Huntingtin (Htt) is a vesicle-associated protein found in both neuronal and nonneuronal cells that is thought to be involved in vesicular transport. In this study, we demonstrate through yeast two-hybrid and affinity chromatography assays that Htt and dynein intermediate chain interact directly; endogenous Htt and dynein coimmunoprecipitate from mouse brain cytosol. Htt RNAi in HeLa cells results in Golgi disruption, similar to the effects of compromising dynein/dynactin function. In vitro studies reveal that Htt and dynein are …
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Jennifer Ross, C. Fagerstrom, G. Yang, E. S. Collins, N. Ma, N. P. Ferenz, S. Balchand, P. Wadsworth, J. Titus, M. Qiu, A. Gabel
Dynamic Reorganization Of Eg5 In The Mammalian Spindle Throughout Mitosis Requires Dynein And Tpx2, Jennifer Ross, C. Fagerstrom, G. Yang, E. S. Collins, N. Ma, N. P. Ferenz, S. Balchand, P. Wadsworth, J. Titus, M. Qiu, A. Gabel
Jennifer Ross
Kinesin-5 is an essential mitotic motor. However, how its spatial-temporal distribution is regulated in mitosis remains poorly understood. We expressed localization and affinity purification-tagged Eg5 from a mouse bacterial artificial chromosome (this construct was called mEg5) and found its distribution to be tightly regulated throughout mitosis. Fluorescence recovery after photobleaching analysis showed rapid Eg5 turnover throughout mitosis, which cannot be accounted for by microtubule turnover. Total internal reflection fluorescence microscopy and high-resolution, single-particle tracking revealed that mEg5 punctae on both astral and midzone microtubules rapidly bind and unbind. mEg5 punctae on midzone microtubules moved transiently both toward and away from …
Mobility Of Taxol In Microtubule Bundles, Jennifer Ross, D. Kuchnir Fygenson
Mobility Of Taxol In Microtubule Bundles, Jennifer Ross, D. Kuchnir Fygenson
Jennifer Ross
Mobility of taxol inside microtubules was investigated using fluorescence recovery after photobleaching on flowaligned bundles. Bundles were made of microtubules with either GMPCPP or GTP at the exchangeable site on the tubulin dimer. Recovery times were sensitive to bundle thickness and packing, indicating that taxol molecules are able to move laterally through the bundle. The density of open binding sites along a microtubule was varied by controlling the concentration of taxol in solution for GMPCPP samples. With [63% sites occupied, recovery times were independent of taxol concentration and, therefore, inversely proportional to the microscopic dissociation rate, koff. It was found …