1
|
Ceglowski J, Hoffman HK, Neumann AJ, Hoff KJ, McCurdy BL, Moore JK, Prekeris R. TTLL12 is required for primary ciliary axoneme formation in polarized epithelial cells. EMBO Rep 2024; 25:198-227. [PMID: 38177908 PMCID: PMC10883266 DOI: 10.1038/s44319-023-00005-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 10/31/2023] [Accepted: 11/09/2023] [Indexed: 01/06/2024] Open
Abstract
The primary cilium is a critical sensory organelle that is built of axonemal microtubules ensheathed by a ciliary membrane. In polarized epithelial cells, primary cilia reside on the apical surface and must extend these microtubules directly into the extracellular space and remain a stable structure. However, the factors regulating cross-talk between ciliation and cell polarization, as well as axonemal microtubule growth and stabilization in polarized epithelia, are not fully understood. In this study, we find TTLL12, a previously uncharacterized member of the Tubulin Tyrosine Ligase-Like (TTLL) family, localizes to the base of primary cilia and is required for cilia formation in polarized renal epithelial cells. We also show that TTLL12 directly binds to the α/β-tubulin heterodimer in vitro and regulates microtubule dynamics, stability, and post-translational modifications (PTMs). While all other TTLLs catalyze the addition of glutamate or glycine to microtubule C-terminal tails, TTLL12 uniquely affects tubulin PTMs by promoting both microtubule lysine acetylation and arginine methylation. Together, this work identifies a novel microtubule regulator and provides insight into the requirements for apical extracellular axoneme formation.
Collapse
Affiliation(s)
- Julia Ceglowski
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Huxley K Hoffman
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Andrew J Neumann
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Katie J Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Bailey L McCurdy
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80015, USA.
| |
Collapse
|
2
|
Wethekam LC, Moore JK. α-tubulin regulation by 5' introns in Saccharomyces cerevisiae. Genetics 2023; 225:iyad163. [PMID: 37675603 PMCID: PMC10697811 DOI: 10.1093/genetics/iyad163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 06/22/2023] [Accepted: 08/21/2023] [Indexed: 09/08/2023] Open
Abstract
Across eukaryotic genomes, multiple α- and β-tubulin genes require regulation to ensure sufficient production of tubulin heterodimers. Features within these gene families that regulate expression remain underexplored. Here, we investigate the role of the 5' intron in regulating α-tubulin expression in Saccharomyces cerevisiae. We find that the intron in the α-tubulin, TUB1, promotes α-tubulin expression and cell fitness during microtubule stress. The role of the TUB1 intron depends on proximity to the TUB1 promoter and sequence features that are distinct from the intron in the alternative α-tubulin isotype, TUB3. These results lead us to perform a screen to identify genes that act with the TUB1 intron. We identified several genes involved in chromatin remodeling, α/β-tubulin heterodimer assembly, and the spindle assembly checkpoint. We propose a model where the TUB1 intron promotes expression from the chromosomal locus and that this may represent a conserved mechanism for tubulin regulation under conditions that require high levels of tubulin production.
Collapse
Affiliation(s)
- Linnea C Wethekam
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| |
Collapse
|
3
|
Ansari S, Gergely ZR, Flynn P, Li G, Moore JK, Betterton MD. Quantifying Yeast Microtubules and Spindles Using the Toolkit for Automated Microtubule Tracking (TAMiT). Biomolecules 2023; 13:939. [PMID: 37371519 DOI: 10.3390/biom13060939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 06/29/2023] Open
Abstract
Fluorescently labeled proteins absorb and emit light, appearing as Gaussian spots in fluorescence imaging. When fluorescent tags are added to cytoskeletal polymers such as microtubules, a line of fluorescence and even non-linear structures results. While much progress has been made in techniques for imaging and microscopy, image analysis is less well-developed. Current analysis of fluorescent microtubules uses either manual tools, such as kymographs, or automated software. As a result, our ability to quantify microtubule dynamics and organization from light microscopy remains limited. Despite the development of automated microtubule analysis tools for in vitro studies, analysis of images from cells often depends heavily on manual analysis. One of the main reasons for this disparity is the low signal-to-noise ratio in cells, where background fluorescence is typically higher than in reconstituted systems. Here, we present the Toolkit for Automated Microtubule Tracking (TAMiT), which automatically detects, optimizes, and tracks fluorescent microtubules in living yeast cells with sub-pixel accuracy. Using basic information about microtubule organization, TAMiT detects linear and curved polymers using a geometrical scanning technique. Images are fit via an optimization problem for the microtubule image parameters that are solved using non-linear least squares in Matlab. We benchmark our software using simulated images and show that it reliably detects microtubules, even at low signal-to-noise ratios. Then, we use TAMiT to measure monopolar spindle microtubule bundle number, length, and lifetime in a large dataset that includes several S. pombe mutants that affect microtubule dynamics and bundling. The results from the automated analysis are consistent with previous work and suggest a direct role for CLASP/Cls1 in bundling spindle microtubules. We also illustrate automated tracking of single curved astral microtubules in S. cerevisiae, with measurement of dynamic instability parameters. The results obtained with our fully-automated software are similar to results using hand-tracked measurements. Therefore, TAMiT can facilitate automated analysis of spindle and microtubule dynamics in yeast cells.
Collapse
Affiliation(s)
- Saad Ansari
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Zachary R Gergely
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Patrick Flynn
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Gabriella Li
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Meredith D Betterton
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| |
Collapse
|
4
|
Wethekam LC, Moore JK. Tubulin isotype regulation maintains asymmetric requirement for α-tubulin over β-tubulin. J Cell Biol 2023; 222:e202202102. [PMID: 36719400 PMCID: PMC9930134 DOI: 10.1083/jcb.202202102] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 07/19/2022] [Accepted: 11/14/2022] [Indexed: 02/01/2023] Open
Abstract
How cells regulate α- and β-tubulin to meet the demand for αβ-heterodimers and avoid consequences of monomer imbalance is not understood. We investigate the role of gene copy number and how shifting expression of α- or β-tubulin genes impacts tubulin proteostasis and microtubule function in Saccharomyces cerevisiae. We find that α-tubulin gene copy number is important for maintaining excess α-tubulin protein compared to β-tubulin protein. Excess α-tubulin prevents accumulation of super-stoichiometric β-tubulin, which leads to loss of microtubules, formation of non-microtubule assemblies of tubulin, and disrupts cell proliferation. In contrast, sub-stoichiometric β-tubulin or overexpression of α-tubulin has minor effects. We provide evidence that yeast cells equilibrate α-tubulin protein concentration when α-tubulin isotype expression is increased. We propose an asymmetric relationship between α- and β-tubulins, in which α-tubulins are maintained in excess to supply αβ-heterodimers and limit the accumulation of β-tubulin monomers.
Collapse
Affiliation(s)
- Linnea C. Wethekam
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| |
Collapse
|
5
|
Ansari S, Gergely ZR, Flynn P, Li G, Moore JK, Betterton MD. Quantifying yeast microtubules and spindles using the Toolkit for Automated Microtubule Tracking (TAMiT). bioRxiv 2023:2023.02.07.527544. [PMID: 36798368 PMCID: PMC9934621 DOI: 10.1101/2023.02.07.527544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Fluorescently labeled proteins absorb and emit light, appearing as Gaussian spots in fluorescence imaging. When fluorescent tags are added to cytoskeletal polymers such as microtubules, a line of fluorescence and even non-linear structures results. While much progress has been made in techniques for imaging and microscopy, image analysis is less well developed. Current analysis of fluorescent microtubules uses either manual tools, such as kymographs, or automated software. As a result, our ability to quantify microtubule dynamics and organization from light microscopy remains limited. Despite development of automated microtubule analysis tools for in vitro studies, analysis of images from cells often depends heavily on manual analysis. One of the main reasons for this disparity is the low signal-to-noise ratio in cells, where background fluorescence is typically higher than in reconstituted systems. Here, we present the Toolkit for Automated Microtubule Tracking (TAMiT), which automatically detects, optimizes and tracks fluorescent microtubules in living yeast cells with sub-pixel accuracy. Using basic information about microtubule organization, TAMiT detects linear and curved polymers using a geometrical scanning technique. Images are fit via an optimization problem for the microtubule image parameters that is solved using non-linear least squares in Matlab. We benchmark our software using simulated images and show that it reliably detects microtubules, even at low signal-to-noise ratios. Then, we use TAMiT to measure monopolar spindle microtubule bundle number, length, and lifetime in a large dataset that includes several S. pombe mutants that affect microtubule dynamics and bundling. The results from the automated analysis are consistent with previous work, and suggest a direct role for CLASP/Cls1 in bundling spindle microtubules. We also illustrate automated tracking of single curved astral microtubules in S. cerevisiae , with measurement of dynamic instability parameters. The results obtained with our fully-automated software are similar to results using hand-tracked measurements. Therefore, TAMiT can facilitate automated analysis of spindle and microtubule dynamics in yeast cells.
Collapse
|
6
|
Hoff KJ, Neumann AJ, Moore JK. The molecular biology of tubulinopathies: Understanding the impact of variants on tubulin structure and microtubule regulation. Front Cell Neurosci 2022; 16:1023267. [PMID: 36406756 PMCID: PMC9666403 DOI: 10.3389/fncel.2022.1023267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 09/30/2022] [Indexed: 11/24/2022] Open
Abstract
Heterozygous, missense mutations in both α- and β-tubulin genes have been linked to an array of neurodevelopment disorders, commonly referred to as "tubulinopathies." To date, tubulinopathy mutations have been identified in three β-tubulin isotypes and one α-tubulin isotype. These mutations occur throughout the different genetic domains and protein structures of these tubulin isotypes, and the field is working to address how this molecular-level diversity results in different cellular and tissue-level pathologies. Studies from many groups have focused on elucidating the consequences of individual mutations; however, the field lacks comprehensive models for the molecular etiology of different types of tubulinopathies, presenting a major gap in diagnosis and treatment. This review highlights recent advances in understanding tubulin structural dynamics, the roles microtubule-associated proteins (MAPs) play in microtubule regulation, and how these are inextricably linked. We emphasize the value of investigating interactions between tubulin structures, microtubules, and MAPs to understand and predict the impact of tubulinopathy mutations at the cell and tissue levels. Microtubule regulation is multifaceted and provides a complex set of controls for generating a functional cytoskeleton at the right place and right time during neurodevelopment. Understanding how tubulinopathy mutations disrupt distinct subsets of those controls, and how that ultimately disrupts neurodevelopment, will be important for establishing mechanistic themes among tubulinopathies that may lead to insights in other neurodevelopment disorders and normal neurodevelopment.
Collapse
Affiliation(s)
| | | | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| |
Collapse
|
7
|
Hoff KJ, Aiken JE, Gutierrez MA, Franco SJ, Moore JK. Tubulinopathy mutations in TUBA1A that disrupt neuronal morphogenesis and migration override XMAP215/Stu2 regulation of microtubule dynamics. eLife 2022; 11:76189. [PMID: 35511030 PMCID: PMC9236607 DOI: 10.7554/elife.76189] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
Heterozygous, missense mutations in α- or β-tubulin genes are associated with a wide range of human brain malformations, known as tubulinopathies. We seek to understand whether a mutation’s impact at the molecular and cellular levels scale with the severity of brain malformation. Here, we focus on two mutations at the valine 409 residue of TUBA1A, V409I, and V409A, identified in patients with pachygyria or lissencephaly, respectively. We find that ectopic expression of TUBA1A-V409I/A mutants disrupt neuronal migration in mice and promote excessive neurite branching and a decrease in the number of neurite retraction events in primary rat neuronal cultures. These neuronal phenotypes are accompanied by increased microtubule acetylation and polymerization rates. To determine the molecular mechanisms, we modeled the V409I/A mutants in budding yeast and found that they promote intrinsically faster microtubule polymerization rates in cells and in reconstitution experiments with purified tubulin. In addition, V409I/A mutants decrease the recruitment of XMAP215/Stu2 to plus ends in budding yeast and ablate tubulin binding to TOG (tumor overexpressed gene) domains. In each assay tested, the TUBA1A-V409I mutant exhibits an intermediate phenotype between wild type and the more severe TUBA1A-V409A, reflecting the severity observed in brain malformations. Together, our data support a model in which the V409I/A mutations disrupt microtubule regulation typically conferred by XMAP215 proteins during neuronal morphogenesis and migration, and this impact on tubulin activity at the molecular level scales with the impact at the cellular and tissue levels. Proteins are molecules made up of long chains of building blocks called amino acids. When a mutation changes one of these amino acids, it can lead to the protein malfunctioning, which can have many effects at the cell and tissue level. Given that human proteins are made up of 20 different amino acids, each building block in a protein could mutate to any of the other 19 amino acids, and each mutations could have different effects. Tubulins are proteins that form microtubules, thin tubes that help give cells their shape and allow them to migrate. These proteins are added or removed to microtubules depending on the cell’s needs, meaning that microtubules can grow or shrink depending on the situation. Mutations in the tubulin proteins have been linked to malformations of varying severities involving the formation of ridges and folds on the surface of the brain, including lissencephaly, pachygyria or polymicrogyria. Hoff et al. wanted to establish links between tubulin mutations and the effects observed at both cell and tissue level in the brain. They focused on two mutations in the tubulin protein TUBA1A that affect the amino acid in position 409 in the protein, which is normally a valine. One of the mutations turns this valine into an amino acid called isoleucine. This mutation is associated with pachygyria, which leads to the brain developing few ridges that are broad and flat. The second mutation turns the valine into an alanine, and is linked to lissencephaly, a more severe condition in which the brain develops no ridges, appearing smooth. Hoff et al. found that both mutations interfere with the development of the brain by stopping neurons from migrating properly, which prevents them from forming the folds in the brain correctly. At the cellular level, the mutations lead to tubulins becoming harder to remove from microtubules, making microtubules more stable than usual. This results in longer microtubules that are harder for the cell to shorten or destroy as needed. Additionally, Hoff et al. showed that the mutant versions of TUBA1A have weaker interactions with a protein called XMAP215, which controls the addition of tubulin to microtubules. This causes the microtubules to grow uncontrollably. Hoff et al. also established that the magnitude of the effects of each mutation on microtubule growth scale with the severity of the disorder they cause. Specifically, cells in which TUBA1A is not mutated have microtubules that grow at a normal rate, and lead to typical brain development. Meanwhile, cells carrying the mutation that turns a valine into an alanine, which is linked to the more severe condition lissencephaly, have microtubules that grow very fast. Finally, cells in which the valine is mutated to an isoleucine – the mutation associated with the less severe malformation pachygyria – have microtubules that grow at an intermediate rate. These findings provide a link between mutations in tubulin proteins and larger effects on cell movement that lead to brain malformations. Additionally, they also link the severity of the malformation to the severity of the microtubule defect caused by each mutation. Further work could examine whether microtubule stabilization is also seen in other similar diseases, which, in the long term, could reveal ways to detect and treat these illnesses.
Collapse
Affiliation(s)
- Katelyn J Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Jayne E Aiken
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Mark A Gutierrez
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Santos J Franco
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Jeffrey K Moore
- University of Colorado School of Medicine, Aurora, United States
| |
Collapse
|
8
|
Park K, Hoff KJ, Wethekam L, Stence N, Saenz M, Moore JK. Kinetically Stabilizing Mutations in Beta Tubulins Create Isotype-Specific Brain Malformations. Front Cell Dev Biol 2021; 9:765992. [PMID: 34869359 PMCID: PMC8637541 DOI: 10.3389/fcell.2021.765992] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/29/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the family of genes encoding the tubulin subunits of microtubules are associated with a spectrum of human brain malformations known as tubulinopathies. How these mutations impact tubulin activity to give rise to distinct developmental consequences is poorly understood. Here we report two patients exhibiting brain malformations characteristic of tubulinopathies and heterozygous T178M missense mutations in different β-tubulin genes, TUBB2A or TUBB3. RNAseq analysis indicates that both TUBB2A and TUBB3 are expressed in the brain during development, but only TUBB2A maintains high expression in neurons into adulthood. The T178 residue is highly conserved in β-tubulins and located in the exchangeable GTP-binding pocket of β-tubulin. To determine the impact of T178M on β-tubulin function we created an analogous mutation in the β-tubulin of budding yeast and show that the substitution acts dominantly to produce kinetically stabilized microtubules that assemble and disassemble slowly, with fewer transitions between these states. In vitro experiments with purified mutant tubulin demonstrate that T178M decreases the intrinsic assembly activity of β-tubulin and forms microtubules that rarely transition to disassembly. We provide evidence that the T178M substitution disrupts GTPase-dependent conformational changes in tubulin, providing a mechanistic explanation for kinetic stabilization. Our findings demonstrate the importance of tubulin’s GTPase activity during brain development, and indicate that tubulin isotypes play different, important roles during brain development.
Collapse
Affiliation(s)
- Kristen Park
- Department of Pediatrics and Neurology, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Katelyn J Hoff
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Linnea Wethekam
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Nicholas Stence
- Section of Pediatric Radiology, Department of Radiology, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Margarita Saenz
- Section of Genetics, Department of Pediatrics, Children's Hospital Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| |
Collapse
|
9
|
Abstract
α- and β-tubulins are encoded by multigene families, but the role of tubulin diversity for microtubule function has been a longstanding mystery. A new study (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202010155) shows that the two budding yeast α-tubulins have distinct roles during mitotic spindle positioning.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Linnea Wethekam
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO
| |
Collapse
|
10
|
Zhang G, Dong Z, Gimple RC, Wolin A, Wu Q, Qiu Z, Wood LM, Shen JZ, Jiang L, Zhao L, Lv D, Prager BC, Kim LJY, Wang X, Zhang L, Anderson RL, Moore JK, Bao S, Keller TH, Lin G, Kang C, Hamerlik P, Zhao R, Ford HL, Rich JN. Targeting EYA2 tyrosine phosphatase activity in glioblastoma stem cells induces mitotic catastrophe. J Exp Med 2021; 218:212685. [PMID: 34617969 PMCID: PMC8504185 DOI: 10.1084/jem.20202669] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 07/11/2021] [Accepted: 08/19/2021] [Indexed: 12/13/2022] Open
Abstract
Glioblastoma ranks among the most lethal of primary brain malignancies, with glioblastoma stem cells (GSCs) at the apex of tumor cellular hierarchies. Here, to discover novel therapeutic GSC targets, we interrogated gene expression profiles from GSCs, differentiated glioblastoma cells (DGCs), and neural stem cells (NSCs), revealing EYA2 as preferentially expressed by GSCs. Targeting EYA2 impaired GSC maintenance and induced cell cycle arrest, apoptosis, and loss of self-renewal. EYA2 displayed novel localization to centrosomes in GSCs, and EYA2 tyrosine (Tyr) phosphatase activity was essential for proper mitotic spindle assembly and survival of GSCs. Inhibition of the EYA2 Tyr phosphatase activity, via genetic or pharmacological means, mimicked EYA2 loss in GSCs in vitro and extended the survival of tumor-bearing mice. Supporting the clinical relevance of these findings, EYA2 portends poor patient prognosis in glioblastoma. Collectively, our data indicate that EYA2 phosphatase function plays selective critical roles in the growth and survival of GSCs, potentially offering a high therapeutic index for EYA2 inhibitors.
Collapse
Affiliation(s)
- Guoxin Zhang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Zhen Dong
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Ryan C Gimple
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA.,Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Arthur Wolin
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Qiulian Wu
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Zhixin Qiu
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Lisa M Wood
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Jia Z Shen
- Tumor Initiation and Maintenance Program, National Cancer Institute-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Li Jiang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Linjie Zhao
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Deguan Lv
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Briana C Prager
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA.,Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Leo J Y Kim
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA.,Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Xiuxing Wang
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Ryan L Anderson
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Shideng Bao
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
| | - Thomas H Keller
- Experimental Drug Development Centre, Agency for Science, Technology and Research, Singapore
| | - Grace Lin
- Experimental Drug Development Centre, Agency for Science, Technology and Research, Singapore
| | - Congbao Kang
- Experimental Drug Development Centre, Agency for Science, Technology and Research, Singapore
| | - Petra Hamerlik
- Danish Cancer Society Research Center, Copenhagen, Denmark.,Department of Drug Design and Pharmacology, Copenhagen University, Copenhagen, Denmark
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Heide L Ford
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jeremy N Rich
- Division of Regenerative Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA.,University of Pittsburgh Medical Center, Hillman Cancer Center, Pittsburgh, PA.,Department of Neurology, University of Pittsburgh, Pittsburgh, PA
| |
Collapse
|
11
|
Robbins CC, Sobrin L, Ma KK, Brouillette KM, Moore JK. Culture-Negative C acnes Endophthalmitis Following Implantation of a Phakic Implantable Collamer Lens. Journal of VitreoRetinal Diseases 2021; 5:258-260. [PMID: 37006510 PMCID: PMC9979035 DOI: 10.1177/2474126420968402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purpose: This work describes a case of Cutibacterium acnes (formerly Propionibacterium acnes) endophthalmitis following a posterior-chamber, phakic, Implantable Collamer Lens (ICL) surgery. Methods: A 34-year-old previously healthy woman presented with chronic unilateral iritis 8 months after bilateral ICL surgery. Original testing revealed no cause for the iritis with normal culture, serology, and autoimmune testing results. Results: Follow-up revealed C acnes by polymerase chain reaction on vitrectomy samples. Complete resolution of symptoms was achieved following removal of the implant, lensectomy, and intravitreal antibiotics. Conclusions: We believe this is the first reported case of postphakic ICL C acnes endophthalmitis. It highlights the utility of polymerase chain reaction in cases of chronic uveitis.
Collapse
Affiliation(s)
| | - Lucia Sobrin
- Department of Ophthalmology, Massachusetts Eye and Ear, Boston, MA, USA
| | - Kevin K. Ma
- Department of Ophthalmology, Massachusetts Eye and Ear, Boston, MA, USA
| | | | - Jeffrey K. Moore
- Department of Ophthalmology, Maine Medical Center, Portland, ME, USA
| |
Collapse
|
12
|
Abstract
How cells regulate microtubule cross-linking activity to control the rate and duration of spindle elongation during anaphase is poorly understood. In this study, we test the hypothesis that PRC1/Ase1 proteins use distinct microtubule-binding domains to control the spindle elongation rate. Using the budding yeast Ase1, we identify unique contributions for the spectrin and carboxy-terminal domains during different phases of spindle elongation. We show that the spectrin domain uses conserved basic residues to promote the recruitment of Ase1 to the midzone before anaphase onset and slow spindle elongation during early anaphase. In contrast, a partial Ase1 carboxy-terminal truncation fails to form a stable midzone in late anaphase, produces higher elongation rates after early anaphase, and exhibits frequent spindle collapses. We find that the carboxy-terminal domain interacts with the plus-end tracking protein EB1/Bim1 and recruits Bim1 to the midzone to maintain midzone length. Overall, our results suggest that the Ase1 domains provide cells with a modular system to tune midzone activity and control elongation rates.
Collapse
Affiliation(s)
- Ezekiel C Thomas
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Amber Ismael
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045.,Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| |
Collapse
|
13
|
Gudimchuk NB, Ulyanov EV, O'Toole E, Page CL, Vinogradov DS, Morgan G, Li G, Moore JK, Szczesna E, Roll-Mecak A, Ataullakhanov FI, Richard McIntosh J. Mechanisms of microtubule dynamics and force generation examined with computational modeling and electron cryotomography. Nat Commun 2020; 11:3765. [PMID: 32724196 PMCID: PMC7387542 DOI: 10.1038/s41467-020-17553-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 07/08/2020] [Indexed: 01/15/2023] Open
Abstract
Microtubules are dynamic tubulin polymers responsible for many cellular processes, including the capture and segregation of chromosomes during mitosis. In contrast to textbook models of tubulin self-assembly, we have recently demonstrated that microtubules elongate by addition of bent guanosine triphosphate tubulin to the tips of curving protofilaments. Here we explore this mechanism of microtubule growth using Brownian dynamics modeling and electron cryotomography. The previously described flaring shapes of growing microtubule tips are remarkably consistent under various assembly conditions, including different tubulin concentrations, the presence or absence of a polymerization catalyst or tubulin-binding drugs. Simulations indicate that development of substantial forces during microtubule growth and shortening requires a high activation energy barrier in lateral tubulin-tubulin interactions. Modeling offers a mechanism to explain kinetochore coupling to growing microtubule tips under assisting force, and it predicts a load-dependent acceleration of microtubule assembly, providing a role for the flared morphology of growing microtubule ends.
Collapse
Affiliation(s)
- Nikita B Gudimchuk
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia.
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia.
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia.
| | - Evgeni V Ulyanov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Eileen O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Cynthia L Page
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Dmitrii S Vinogradov
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Garry Morgan
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Gabriella Li
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ewa Szczesna
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Fazoil I Ataullakhanov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| |
Collapse
|
14
|
Abstract
How temperature specifically affects microtubule dynamics and how these lead to changes in microtubule networks in cells have not been established. We investigated these questions in budding yeast, an organism found in diverse environments and therefore predicted to exhibit dynamic microtubules across a broad temperature range. We measured the dynamics of GFP-labeled microtubules in living cells and found that lowering temperature from 37°C to 10°C decreased the rates of both polymerization and depolymerization, decreased the amount of polymer assembled before catastrophes, and decreased the frequency of microtubule emergence from nucleation sites. Lowering to 4°C caused rapid loss of almost all microtubule polymer. We provide evidence that these effects on microtubule dynamics may be explained in part by changes in the cofactor-dependent conformational dynamics of tubulin proteins. Ablation of tubulin-binding cofactors (TBCs) further sensitizes cells and their microtubules to low temperatures, and we highlight a specific role for TBCB/Alf1 in microtubule maintenance at low temperatures. Finally, we show that inhibiting the maturation cycle of tubulin by using a point mutant in β-tubulin confers hyperstable microtubules at low temperatures and rescues the requirement for TBCB/Alf1 in maintaining microtubule polymer at low temperatures. Together, these results reveal an unappreciated step in the tubulin cycle.
Collapse
Affiliation(s)
- Gabriella Li
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| |
Collapse
|
15
|
Aiken J, Buscaglia G, Aiken AS, Moore JK, Bates EA. Cover Image, Volume 77, Issue 3‐4. Cytoskeleton (Hoboken) 2020. [DOI: 10.1002/cm.21605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental BiologyUniversity of Colorado School of Medicine Aurora Colorado
| | - Georgia Buscaglia
- Department of PediatricsUniversity of Colorado Anschutz Medical Campus Aurora Colorado
| | - A. Sophie Aiken
- Department of Cell and Developmental BiologyUniversity of Colorado School of Medicine Aurora Colorado
| | - Jeffrey K. Moore
- Department of Cell and Developmental BiologyUniversity of Colorado School of Medicine Aurora Colorado
| | - Emily A. Bates
- Department of PediatricsUniversity of Colorado Anschutz Medical Campus Aurora Colorado
| |
Collapse
|
16
|
Rao P, Caunt JN, Wong JWY, Moore JK, Zepf FD. Child and adolescent psychiatry training in Australia and New Zealand. Eur Child Adolesc Psychiatry 2020; 29:95-103. [PMID: 31641901 DOI: 10.1007/s00787-019-01422-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/10/2019] [Indexed: 10/25/2022]
Abstract
The specialty of Child and Adolescent Psychiatry was formally recognised in the 1930s. The Faculty of Child and Adolescent Psychiatry was established in 1964 in Australia, as a subspecialty in The Royal Australian and New Zealand College of Psychiatrists (RANZCP). The aim of the current article is first to provide a brief summary and overview of the current status of Child and Adolescent Psychiatry (CAP), followed by an outline of the requirements of the Training Program for CAP in Australia and New Zealand. The training required to become a fully qualified child and adolescent psychiatrist in Australia and New Zealand consists of different stages and takes the form of competency-based training. Information relating to assessment types, supervision and research requirements is also described. Accreditation procedures for the training program are stipulated by RANZCP to monitor standards and to ensure consistency within the programs delivered across Australia and New Zealand. Employment opportunities for trainees upon completion of the program are discussed. In summary, this article highlights the requirements of the training programs for CAP in Australia and New Zealand.
Collapse
Affiliation(s)
- P Rao
- Centre and Discipline of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Division of Psychiatry and Clinical Neurosciences and Division of Paediatrics and Child Health, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia. .,Child and Adolescent Mental Health Service, Child and Adolescent Health Service, 52-54 Monash Avenue, Nedlands, Perth, WA, 6008, Australia. .,Telethon Kids Institute, 15 Hospital Avenue, Nedlands, Perth, WA, 6008, Australia.
| | - J N Caunt
- Child and Adolescent Mental Health Service, Child and Adolescent Health Service, 52-54 Monash Avenue, Nedlands, Perth, WA, 6008, Australia
| | - J W Y Wong
- Centre and Discipline of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Division of Psychiatry and Clinical Neurosciences and Division of Paediatrics and Child Health, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.,Child and Adolescent Mental Health Service, Child and Adolescent Health Service, 52-54 Monash Avenue, Nedlands, Perth, WA, 6008, Australia.,Telethon Kids Institute, 15 Hospital Avenue, Nedlands, Perth, WA, 6008, Australia
| | - J K Moore
- Centre and Discipline of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Division of Psychiatry and Clinical Neurosciences and Division of Paediatrics and Child Health, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.,Child and Adolescent Mental Health Service, Child and Adolescent Health Service, 52-54 Monash Avenue, Nedlands, Perth, WA, 6008, Australia
| | - F D Zepf
- Centre and Discipline of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Division of Psychiatry and Clinical Neurosciences and Division of Paediatrics and Child Health, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.,Department of Child and Adolescent Psychiatry, Psychosomatic Medicine and Psychotherapy, Jena University Hospital, Friedrich Schiller University, Am Steiger 6, 07743, Jena, Germany.,Telethon Kids Institute, 15 Hospital Avenue, Nedlands, Perth, WA, 6008, Australia
| |
Collapse
|
17
|
Aiken J, Buscaglia G, Aiken AS, Moore JK, Bates EA. Tubulin mutations in brain development disorders: Why haploinsufficiency does not explain TUBA1A tubulinopathies. Cytoskeleton (Hoboken) 2019; 77:40-54. [PMID: 31574570 DOI: 10.1002/cm.21567] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/09/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022]
Abstract
The neuronal cytoskeleton performs incredible feats during nervous system development. Extension of neuronal processes, migration, and synapse formation rely on the proper regulation of microtubules. Mutations that disrupt the primary α-tubulin expressed during brain development, TUBA1A, are associated with a spectrum of human brain malformations. One model posits that TUBA1A mutations lead to a reduction in tubulin subunits available for microtubule polymerization, which represents a haploinsufficiency mechanism. We propose an alternative model for the majority of tubulinopathy mutations, in which the mutant tubulin polymerizes into the microtubule lattice to dominantly "poison" microtubule function. Nine distinct α-tubulin and ten β-tubulin genes have been identified in the human genome. These genes encode similar tubulin proteins, called isotypes. Multiple tubulin isotypes may partially compensate for heterozygous deletion of a tubulin gene, but may not overcome the disruption caused by missense mutations that dominantly alter microtubule function. Here, we describe disorders attributed to haploinsufficiency versus dominant negative mechanisms to demonstrate the hallmark features of each disorder. We summarize literature on mouse models that represent both knockout and point mutants in tubulin genes, with an emphasis on how these mutations might provide insight into the nature of tubulinopathy patient mutations. Finally, we present data from a panel of TUBA1A tubulinopathy mutations generated in yeast α-tubulin that demonstrate that α-tubulin mutants can incorporate into the microtubule network and support viability of yeast growth. This perspective on tubulinopathy mutations draws on previous studies and additional data to provide a fresh perspective on how TUBA1A mutations disrupt neurodevelopment.
Collapse
Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Georgia Buscaglia
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - A Sophie Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Emily A Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| |
Collapse
|
18
|
Estrem C, Moore JK. Help or hindrance: how do microtubule-based forces contribute to genome damage and repair? Curr Genet 2019; 66:303-311. [PMID: 31501990 DOI: 10.1007/s00294-019-01033-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/27/2019] [Accepted: 08/27/2019] [Indexed: 10/26/2022]
Abstract
Forces generated by molecular motors and the cytoskeleton move the nucleus and genome during many cellular processes, including cell migration and division. How these forces impact the genome, and whether cells regulate cytoskeletal forces to preserve genome integrity is unclear. We recently demonstrated that, in budding yeast, mutants that stabilize the microtubule cytoskeleton cause excessive movement of the mitotic spindle and nucleus. We found that increased nuclear movement results in DNA damage and increased time to repair the damage through homology-directed repair. Our results indicate that nuclear movement impairs DNA repair through increased tension on chromosomes and nuclear deformation. However, the previous studies have shown genome mobility, driven by cytoskeleton-based forces, aids in homology-directed DNA repair. This sets up an apparent paradox, where genome mobility may prevent or promote DNA repair. Hence, this review explores how the genome is affected by nuclear movement and how genome mobility could aid or hinder homology-directed repair.
Collapse
Affiliation(s)
- Cassi Estrem
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
| |
Collapse
|
19
|
Aiken J, Moore JK, Bates EA. TUBA1A mutations identified in lissencephaly patients dominantly disrupt neuronal migration and impair dynein activity. Hum Mol Genet 2019; 28:1227-1243. [PMID: 30517687 DOI: 10.1093/hmg/ddy416] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/16/2018] [Accepted: 11/27/2018] [Indexed: 02/06/2023] Open
Abstract
The microtubule cytoskeleton supports diverse cellular morphogenesis and migration processes during brain development. Mutations in tubulin genes are associated with severe human brain malformations known as 'tubulinopathies'; however, it is not understood how molecular-level changes in microtubule subunits lead to brain malformations. In this study, we demonstrate that missense mutations affecting arginine at position 402 (R402) of TUBA1A α-tubulin selectively impair dynein motor activity and severely and dominantly disrupt cortical neuronal migration. TUBA1A is the most commonly affected tubulin gene in tubulinopathy patients, and mutations altering R402 account for 30% of all reported TUBA1A mutations. We show for the first time that ectopic expression of TUBA1A-R402C and TUBA1A-R402H patient alleles is sufficient to dominantly disrupt cortical neuronal migration in the developing mouse brain, strongly supporting a causal role in the pathology of brain malformation. To isolate the precise molecular impact of R402 mutations, we generated analogous R402C and R402H mutations in budding yeast α-tubulin, which exhibit a simplified microtubule cytoskeleton. We find that R402 mutant tubulins assemble into microtubules that support normal kinesin motor activity but fail to support the activity of dynein motors. Importantly, the level of dynein impairment scales with the expression level of the mutant in the cell, suggesting a 'poisoning' mechanism in which R402 mutant α-tubulin acts dominantly by populating microtubules with defective binding sites for dynein. Based on our results, we propose a new model for the molecular pathology of tubulinopathies that may also extend to other tubulin-related neuropathies.
Collapse
Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental Biology
| | | | - Emily A Bates
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| |
Collapse
|
20
|
Abstract
Dividing cells must balance the maintenance of genome integrity with the generation of cytoskeletal forces that control chromosome position. In this study, we investigate how forces on astral microtubules impact the genome during cell division by using live-cell imaging of the cytoskeleton, chromatin, and DNA damage repair in budding yeast. Our results demonstrate that dynein-dependent forces on astral microtubules are propagated through the spindle during nuclear migration and when in excess can increase the frequency of double-stranded breaks (DSBs). Under these conditions, we find that homology-directed repair of DSBs is delayed, indicating antagonism between nuclear migration and the mechanism of homology-directed repair. These effects are partially rescued by mutants that weaken pericentric cohesion or mutants that decrease constriction on the nucleus as it moves through the bud neck. We propose that minimizing nuclear movement aids in finding a donor strand for homologous recombination.
Collapse
Affiliation(s)
- Cassi Estrem
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| |
Collapse
|
21
|
Abstract
How microtubules transition from depolymerization to polymerization, known as rescue, is poorly understood. Here we examine two models for rescue: 1) an "end-driven" model in which the depolymerizing end stochastically switches to a stable state; and 2) a "lattice-driven" model in which rescue sites are integrated into the microtubule before depolymerization. We test these models using a combination of computational simulations and in vitro experiments with purified tubulin. Our findings support the "lattice-driven" model by identifying repeated rescue sites in microtubules. In addition, we discover an important role for divalent cations in determining the frequency and location of rescue sites. We use "wash-in" experiments to show that divalent cations inhibit rescue during depolymerization, but not during polymerization. We propose a unified model in which rescues are driven by embedded rescue sites in microtubules, but the activity of these sites is influenced by changes in the depolymerizing ends.
Collapse
Affiliation(s)
- Colby P. Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| |
Collapse
|
22
|
Abstract
This work examines how the carboxy-terminal tail domain of β-tubulin governs microtubule dynamic instability and the structure of plus ends using complementary in vivo and in vitro experiments. Dynamic instability is an intrinsic property of microtubules; however, we do not understand what domains of αβ-tubulins regulate this activity or how these regulate microtubule networks in cells. Here, we define a role for the negatively charged carboxy-terminal tail (CTT) domain of β-tubulin in regulating dynamic instability. By combining in vitro studies with purified mammalian tubulin and in vivo studies with tubulin mutants in budding yeast, we demonstrate that β-tubulin CTT inhibits microtubule stability and regulates the structure and stability of microtubule plus ends. Tubulin that lacks β-tubulin CTT polymerizes faster and depolymerizes slower in vitro and forms microtubules that are more prone to catastrophe. The ends of these microtubules exhibit a more blunted morphology and rapidly switch to disassembly after tubulin depletion. In addition, we show that β-tubulin CTT is required for magnesium cations to promote depolymerization. We propose that β-tubulin CTT regulates the assembly of stable microtubule ends and provides a tunable mechanism to coordinate dynamic instability with ionic strength in the cell.
Collapse
Affiliation(s)
- Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| |
Collapse
|
23
|
Abstract
Microtubules are dynamic cytoskeletal polymers that mediate numerous, essential functions such as axon and dendrite growth and neuron migration throughout brain development. In recent years, sequencing has revealed dominant mutations that disrupt the tubulin protein building blocks of microtubules. These tubulin mutations lead to a spectrum of devastating brain malformations, complex neurological and physical phenotypes, and even fatality. The most common tubulin gene mutated is the α-tubulin gene TUBA1A, which is the most prevalent α-tubulin gene expressed in post-mitotic neurons. The normal role of TUBA1A during neuronal maturation, and how mutations alter its function to produce the phenotypes observed in patients, remains unclear. This review synthesizes current knowledge of TUBA1A function and expression during brain development, and the brain malformations caused by mutations in TUBA1A.
Collapse
Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, MS8108, 12801 E 17th Ave, Aurora, CO 80045, USA;
| | - Georgia Buscaglia
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (G.B.); (E.A.B.)
| | - Emily A. Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (G.B.); (E.A.B.)
| | - Jeffrey K. Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, MS8108, 12801 E 17th Ave, Aurora, CO 80045, USA;
- Correspondence: ; Tel.: +1-303-724-6198; Fax: +1-303-724-3420
| |
Collapse
|
24
|
Estrem C, Fees CP, Moore JK. Dynein is regulated by the stability of its microtubule track. J Cell Biol 2017; 216:2047-2058. [PMID: 28572117 PMCID: PMC5496616 DOI: 10.1083/jcb.201611105] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/24/2017] [Accepted: 05/04/2017] [Indexed: 12/23/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Cassi Estrem
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO
| |
Collapse
|
25
|
Abstract
Dynamic microtubules are fundamental to many cellular processes, and accurate measurements of microtubule dynamics can provide insight into how cells regulate these processes and how genetic mutations impact regulation. The quantification of microtubule dynamics in metazoan models has a number of associated challenges, including a high microtubule density and limitations on genetic manipulations. In contrast, the budding yeast model offers advantages that overcome these challenges. This protocol describes a method to measure the dynamics of single microtubules in living yeast cells. Cells expressing fluorescently tagged tubulin are adhered to assembled slide chambers, allowing for stable time-lapse image acquisition. A detailed guide for high-speed, four-dimensional image acquisition is also provided, as well as a protocol for quantifying the properties of dynamic microtubules in confocal image stacks. This method, combined with conventional yeast genetics, provides an approach that is uniquely suited for quantitatively assessing the effects of microtubule regulators or mutations that alter the activity of tubulin subunits.
Collapse
Affiliation(s)
- Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine
| | - Cassi Estrem
- Department of Cell and Developmental Biology, University of Colorado School of Medicine
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine;
| |
Collapse
|
26
|
Moore JK, MacKinnon AC, Man TY, Manning JR, Forbes SJ, Simpson KJ. Patients with the worst outcomes after paracetamol (acetaminophen)-induced liver failure have an early monocytopenia. Aliment Pharmacol Ther 2017; 45:443-454. [PMID: 27896824 DOI: 10.1111/apt.13878] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 09/21/2016] [Accepted: 11/04/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND Acute liver failure (ALF) is associated with significant morbidity and mortality. Studies have implicated the immune response, especially monocyte/macrophages as being important in dictating outcome. AIM To investigate changes in the circulating monocytes and other immune cells serially in patients with ALF, relate these with cytokine concentrations, monocyte gene expression and patient outcome. METHODS In a prospective case-control study in the Scottish Liver Transplant Unit, Royal Infirmary Edinburgh, 35 consecutive patients admitted with paracetamol-induced liver failure (POD-ALF), 10 patients with non-paracetamol causes of ALF and 16 controls were recruited. The peripheral blood monocyte phenotype was analysed by flow cytometry, circulating cytokines quantified by protein array and monocyte gene expression array performed and related to outcome. RESULTS On admission, patients with worst outcomes after POD-ALF had a significant monocytopenia, characterised by reduced classical and expanded intermediate monocyte population. This was associated with reduced circulating lymphocytes and natural killer cells, peripheral cytokine patterns suggestive of a 'cytokine storm' and increased concentrations of cytokines associated with monocyte egress from the bone marrow. Gene expression array did not differentiate patient outcome. At day 4, there was no significant difference in monocyte, lymphocyte or natural killer cells between survivors and the patients with adverse outcomes. CONCLUSIONS Severe paracetamol liver failure is associated with profound changes in the peripheral blood compartment, particularly in monocytes, related with worse outcomes. This is not seen in patients with non-paracetamol-induced liver failure. Significant monocytopenia on admission may allow earlier clarification of prognosis, and it highlights a potential target for therapeutic intervention.
Collapse
Affiliation(s)
- J K Moore
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - A C MacKinnon
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - T Y Man
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - J R Manning
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - S J Forbes
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - K J Simpson
- Division of Clinical and Surgical Sciences, University of Edinburgh, Edinburgh, UK
| |
Collapse
|
27
|
Mangan AJ, Sietsema DV, Li D, Moore JK, Citi S, Prekeris R. Cingulin and actin mediate midbody-dependent apical lumen formation during polarization of epithelial cells. Nat Commun 2016; 7:12426. [PMID: 27484926 PMCID: PMC4976216 DOI: 10.1038/ncomms12426] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 07/01/2016] [Indexed: 12/26/2022] Open
Abstract
Coordinated polarization of epithelial cells is a key step during morphogenesis that leads to the formation of an apical lumen. Rab11 and its interacting protein FIP5 are necessary for the targeting of apical endosomes to the midbody and apical membrane initiation site (AMIS) during lumenogenesis. However, the machinery that mediates AMIS establishment and FIP5-endosome targeting remains unknown. Here we identify a FIP5-interacting protein, Cingulin, which localizes to the AMIS and functions as a tether mediating FIP5-endosome targeting. We analysed the machinery mediating AMIS recruitment to the midbody and determined that both branched actin and microtubules are required for establishing the site of the nascent lumen. We demonstrate that the Rac1-WAVE/Scar complex mediates Cingulin recruitment to the AMIS by inducing branched actin formation, and that Cingulin directly binds to microtubule C-terminal tails through electrostatic interactions. We propose a new mechanism for apical endosome targeting and AMIS formation around the midbody during epithelial lumenogenesis. Polarisation of epithelial cells causes lumen formation, which is mediated by apical membrane initiation site (AMIS) and FIP5, but how this is regulated is unclear. Here, the authors identify cingulin as a FIP-5 interacting protein, recruiting the Rac1-WAVE/Scar complex to the AMIS and branched actin formation.
Collapse
Affiliation(s)
- Anthony J Mangan
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA
| | - Daniel V Sietsema
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA
| | - Dongying Li
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA
| | - Sandra Citi
- Cell Biology Department, University of Geneva, CH-1211 GENEVA 4, Switzerland
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045, USA
| |
Collapse
|
28
|
Fees CP, Aiken J, O'Toole ET, Giddings TH, Moore JK. The negatively charged carboxy-terminal tail of β-tubulin promotes proper chromosome segregation. Mol Biol Cell 2016; 27:1786-96. [PMID: 27053662 PMCID: PMC4884069 DOI: 10.1091/mbc.e15-05-0300] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 03/30/2016] [Indexed: 11/11/2022] Open
Abstract
Microtubules are essential for chromosome segregation. A study of the mechanistic contributions of tubulin proteins identifies a specific role for the negatively charged carboxy-terminal tail domain of b-tubulin in positioning kinetochores in the mitotic spindle and ensuring efficient and accurate chromosome segregation. Despite the broadly conserved role of microtubules in chromosome segregation, we have a limited understanding of how molecular features of tubulin proteins contribute to the underlying mechanisms. Here we investigate the negatively charged carboxy-terminal tail domains (CTTs) of α- and β-tubulins, using a series of mutants that alter or ablate CTTs in budding yeast. We find that ablating β-CTT causes elevated rates of chromosome loss and cell cycle delay. Complementary live-cell imaging and electron tomography show that β-CTT is necessary to properly position kinetochores and organize microtubules within the assembling spindle. We identify a minimal region of negatively charged amino acids that is necessary and sufficient for proper chromosome segregation and provide evidence that this function may be conserved across species. Our results provide the first in vivo evidence of a specific role for tubulin CTTs in chromosome segregation. We propose that β-CTT promotes the ordered segregation of chromosomes by stabilizing the spindle and contributing to forces that move chromosomes toward the spindle poles.
Collapse
Affiliation(s)
- Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Eileen T O'Toole
- Boulder Laboratory for 3D Electron Microscopy of Cells, University of Colorado Boulder, Boulder, CO 80309
| | - Thomas H Giddings
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| |
Collapse
|
29
|
Gartz Hanson M, Aiken J, Sietsema DV, Sept D, Bates EA, Niswander L, Moore JK. Novel α-tubulin mutation disrupts neural development and tubulin proteostasis. Dev Biol 2015; 409:406-19. [PMID: 26658218 DOI: 10.1016/j.ydbio.2015.11.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/10/2015] [Accepted: 11/27/2015] [Indexed: 10/22/2022]
Abstract
Mutations in the microtubule cytoskeleton are linked to cognitive and locomotor defects during development, and neurodegeneration in adults. How these mutations impact microtubules, and how this alters function at the level of neurons is an important area of investigation. Using a forward genetic screen in mice, we identified a missense mutation in Tuba1a α-tubulin that disrupts cortical and motor neuron development. Homozygous mutant mice exhibit cortical dysgenesis reminiscent of human tubulinopathies. Motor neurons fail to innervate target muscles in the limbs and show synapse defects at proximal targets. To directly examine effects on tubulin function, we created analogous mutations in the α-tubulin isotypes in budding yeast. These mutations sensitize yeast cells to microtubule stresses including depolymerizing drugs and low temperatures. Furthermore, we find that mutant α-tubulin is depleted from the cell lysate and from microtubules, thereby altering ratios of α-tubulin isotypes. Tubulin-binding cofactors suppress the effects of the mutation, indicating an important role for these cofactors in regulating the quality of the α-tubulin pool. Together, our results give new insights into the functions of Tuba1a, mechanisms for regulating tubulin proteostasis, and how compromising these may lead to neural defects.
Collapse
Affiliation(s)
- M Gartz Hanson
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Daniel V Sietsema
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - David Sept
- Department of Biomedical Engineering and Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Emily A Bates
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Lee Niswander
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
| |
Collapse
|
30
|
Rao P, Moore JK, Stewart R, Hood SD, Runions K, Zepf FD. Diagnostic inexactitude - Reframing and relabelling Disruptive Mood Dysregulation Disorder for ICD-11 does not solve the problem. Med Hypotheses 2015; 85:1035-6. [PMID: 26545314 DOI: 10.1016/j.mehy.2015.10.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/18/2015] [Accepted: 10/11/2015] [Indexed: 11/26/2022]
Affiliation(s)
- P Rao
- Department of Child and Adolescent Psychiatry, School of Psychiatry and Clinical Neurosciences & School of Paediatrics and Child Health, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia (M561), Perth, WA 6009, Australia; Community Child and Adolescent Mental Health Services, Department of Health in Western Australia, Perth, WA, Australia
| | - J K Moore
- Department of Child and Adolescent Psychiatry, School of Psychiatry and Clinical Neurosciences & School of Paediatrics and Child Health, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia (M561), Perth, WA 6009, Australia; Paediatric Consultation-Liaison Program, Child and Adolescent Mental Health Services, Department of Health in Western Australia, Perth, WA, Australia
| | - R Stewart
- Department of Child and Adolescent Psychiatry, School of Psychiatry and Clinical Neurosciences & School of Paediatrics and Child Health, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia (M561), Perth, WA 6009, Australia
| | - S D Hood
- School of Psychiatry and Clinical Neurosciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia, GPO Box D184, Perth, WA 6840, Australia
| | - K Runions
- Telethon Kids Institute, Perth, WA, Australia
| | - F D Zepf
- Department of Child and Adolescent Psychiatry, School of Psychiatry and Clinical Neurosciences & School of Paediatrics and Child Health, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia (M561), Perth, WA 6009, Australia; Specialised Child and Adolescent Mental Health Services (CAMHS), Department of Health in Western Australia, Perth, WA, Australia.
| |
Collapse
|
31
|
Nithianantham S, Le S, Seto E, Jia W, Leary J, Corbett KD, Moore JK, Al-Bassam J. Tubulin cofactors and Arl2 are cage-like chaperones that regulate the soluble αβ-tubulin pool for microtubule dynamics. eLife 2015. [PMID: 26208336 PMCID: PMC4574351 DOI: 10.7554/elife.08811] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Microtubule dynamics and polarity stem from the polymerization of
αβ-tubulin heterodimers. Five conserved tubulin cofactors/chaperones
and the Arl2 GTPase regulate α- and β-tubulin assembly into
heterodimers and maintain the soluble tubulin pool in the cytoplasm, but their
physical mechanisms are unknown. Here, we reconstitute a core tubulin chaperone
consisting of tubulin cofactors TBCD, TBCE, and Arl2, and reveal a cage-like
structure for regulating αβ-tubulin. Biochemical assays and electron
microscopy structures of multiple intermediates show the sequential binding of
αβ-tubulin dimer followed by tubulin cofactor TBCC onto this chaperone,
forming a ternary complex in which Arl2 GTP hydrolysis is activated to alter
αβ-tubulin conformation. A GTP-state locked Arl2 mutant inhibits
ternary complex dissociation in vitro and causes severe defects in microtubule
dynamics in vivo. Our studies suggest a revised paradigm for tubulin cofactors and
Arl2 functions as a catalytic chaperone that regulates soluble
αβ-tubulin assembly and maintenance to support microtubule
dynamics. DOI:http://dx.doi.org/10.7554/eLife.08811.001 Cells contain a network of protein filaments called microtubules. These filaments are
involved in many biological processes; for example, they help cells keep the right
shape, and they help to transport proteins and other materials inside cells. Two proteins called α-tubulin and β-tubulin are the building blocks of
microtubules. The filaments are very dynamic structures that can rapidly change
length as individual tubulin units are either added or removed to the filament ends.
Several proteins known as tubulin cofactors and an enzyme called Arl2 help to build a
vast pool of tubulin units that are able attach to the microtubules. These
units—called αβ-tubulin—are formed by α-tubulin
and β-tubulin binding to each other, but it not clear exactly what roles the
tubulin cofactors and Arl2 play in this process. Nithianantham et al. used a combination of microscopy and biochemical techniques to
study how the tubulin cofactors and Arl2 are organised, and their role in the
assembly of microtubules in yeast. The experiments show that Arl2 and two tubulin
cofactors associate with each other to form a stable ‘complex’ that has
a cage-like structure. A molecule of αβ-tubulin binds to the complex,
followed by another cofactor called TBCC. This activates the enzyme activity of Arl2,
which releases the energy needed to alter the shape of the αβ-tubulin.
Nithianantham et al. also found that yeast cells with a mutant form of Arl2 that
lacked enzyme activity had problems forming microtubules. Together, these findings show that the tubulin cofactors and Arl2 form a complex that
regulates the assembly and maintenance of αβ-tubulin. The next
challenge is to understand how this regulation influences the way that microtubules
grow and shrink inside cells. DOI:http://dx.doi.org/10.7554/eLife.08811.002
Collapse
Affiliation(s)
- Stanley Nithianantham
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Sinh Le
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Elbert Seto
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Weitao Jia
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Julie Leary
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Kevin D Corbett
- Ludwig Institute for Cancer Research, University of California, San Diego, San Diego, United States
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Jawdat Al-Bassam
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| |
Collapse
|
32
|
Portillo F, Nelson RA, Brackmann DE, Hitselberger WE, Shannon RV, Waring MD, Moore JK. Auditory brain stem implant: electrical stimulation of the human cochlear nucleus. Adv Otorhinolaryngol 2015; 48:248-52. [PMID: 8273489 DOI: 10.1159/000422592] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
33
|
Aiken J, Sept D, Costanzo M, Boone C, Cooper JA, Moore JK. Genome-wide analysis reveals novel and discrete functions for tubulin carboxy-terminal tails. Curr Biol 2014; 24:1295-1303. [PMID: 24835459 DOI: 10.1016/j.cub.2014.03.078] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/27/2014] [Accepted: 03/31/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Microtubules (MTs) support diverse transport and force generation processes in cells. Both α- and β-tubulin proteins possess carboxy-terminal tail regions (CTTs) that are negatively charged, intrinsically disordered, and project from the MT surface where they interact with motors and other proteins. Although CTTs are presumed to play important roles in MT networks, these roles have not been determined in vivo. RESULTS We examined the function of CTTs in vivo by using a systematic collection of mutants in budding yeast. We find that CTTs are not essential; however, loss of either α- or β-CTT sensitizes cells to MT-destabilizing drugs. β-CTT, but not α-CTT, regulates MT dynamics by increasing frequencies of catastrophe and rescue events. In addition, β-CTT is critical for the assembly of the mitotic spindle and its elongation during anaphase. We use genome-wide genetic interaction screens to identify roles for α- and β-CTTs, including a specific role for β-CTT in supporting kinesin-5/Cin8. Our genetic screens also identified novel interactions with pathways not related to canonical MT functions. CONCLUSIONS We conclude that α- and β-CTTs play important and largely discrete roles in MT networks. β-CTT promotes MT dynamics. β-CTT also regulates force generation in the mitotic spindle by supporting kinesin-5/Cin8 and dampening dynein. Our genetic screens identify links between α- and β-CTT and additional cellular pathways and suggest novel functions.
Collapse
Affiliation(s)
- Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - David Sept
- Department of Biomedical Engineering and Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Michael Costanzo
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Charles Boone
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - John A Cooper
- Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
| |
Collapse
|
34
|
Moore JK, Stutchfield BM, Forbes SJ. Systematic review: the effects of autologous stem cell therapy for patients with liver disease. Aliment Pharmacol Ther 2014; 39:673-85. [PMID: 24528093 DOI: 10.1111/apt.12645] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 11/24/2013] [Accepted: 01/12/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND As morbidity and mortality from liver disease continues to rise, new strategies are necessary. Liver transplantation is not only an expensive resource committing the patient to lifelong immunosuppression but also suitable donor organs are in short supply. Against this background, autologous stem cell therapy has emerged as a potential treatment option. AIM To evaluate if it is possible to make a judgement on the safety, feasibility and effect of autologous stem cell therapy for patients with liver disease. METHODS MEDLINE and EMBASE were searched up until July 2013 to identify studies where autologous stem cell therapy was administered to patients with liver disease. RESULTS Of 1668 studies identified, 33 were eligible for inclusion evaluating a median sample size of 10 patients for a median follow-up of 6 months. Although there was marked heterogeneity between studies with regards to type, dose and route of delivery of stem cell, the treatment was shown to be safe and feasible largely when a peripheral route of administration was used. Of the studies which also looked at biochemical outcome, statistically significant improvement in liver function tests was seen in 16 studies post-treatment. CONCLUSION Although autologous stem cell therapy is a much needed possibility in the treatment of liver disease, further robust clinical trials and collaborative protocols are required.
Collapse
Affiliation(s)
- J K Moore
- MRC Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh, UK
| | | | | |
Collapse
|
35
|
Moore JK, Craig DG, Pryde EA, Walker SW, Beckett GJ, Hayes PC, Simpson KJ. Persistently elevated troponin I in paracetamol hepatotoxicity: association with liver injury, organ failure, and outcome. Clin Toxicol (Phila) 2013; 51:532-9. [PMID: 23829708 DOI: 10.3109/15563650.2013.816853] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CONTEXT An elevated troponin I (TnI) is associated with a poorer prognosis during critical illness. OBJECTIVE Our aims were to determine whether significant paracetamol-induced hepatotoxicity was associated with an elevated TnI; if this elevation was persistent and was associated with worse clinical outcomes. MATERIALS AND METHODS In this retrospective cohort study, the requirement for orthotopic liver transplantation (OLT) or death and/or the development of multiorgan failure (MOF) was evaluated for 48 consecutive patients admitted to the Royal Infirmary of Edinburgh (a university tertiary referral centre) with acute liver injury or acute liver failure secondary to paracetamol overdose. RESULTS TnI was elevated (≥ 0.05 ng/L) in 13/48 patients (27%). This appeared to be sustained for at least 6 days which has not been shown previously in the context of Acute Liver Injury (ALI). Elevated TnI was strongly associated with MOF, with the requirement for inotropic support being the strongest predictor (p = 0.003, OR 9.00, 95% CI 2.13-37.98). TnI elevations also correlated strongly with Acute Physiology and Chronic Health Evaluation (APACHE) II scores (p = 0.0006, r = 0.482, 95% CI 0.22-0.68) and with interleukin 6 (IL-6) levels (p = 0.0001, r = 0.55, 95% CI 0.29-0.73). Although a raised TnI was associated with a markedly increased risk of death or orthotopic liver transplant (p = 0.005, OR 7.73, 95% CI 1.87-32.05) on univariate analysis, this was primarily seen in the context of MOF (SOFA score p = 0.003, OR 1.23, 95% CI 1.07-1.41) and was not an independent predictor of death. There was no correlation between TnI or outcome with other cardiac biomarkers and markers of cardiovascular risk. DISCUSSION AND CONCLUSION An elevated TnI in the context of acute liver injury or liver failure following paracetamol overdose is associated with a significantly worse patient outcome but it is not an independent prognostic factor. Further studies should be undertaken to investigate the mechanism behind this elevated troponin association.
Collapse
Affiliation(s)
- J K Moore
- Scottish Liver Transplantation Unit, Royal Infirmary of Edinburgh, Little France, Edinburgh EH16 4SA, UK
| | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
How do cells direct the microtubule motor protein dynein to move cellular components to the right place at the right time? Recent studies in budding yeast shed light on a new mechanism for directing dynein, involving the protein She1. She1 restricts where and when dynein moves the nucleus and mitotic spindle. Experiments with purified proteins show that She1 binds to microtubules and inhibits dynein by stalling the motor on its track. Here I describe what we have learned so far about She1, based on a combination of genetic, cell biology, and biophysical approaches. These findings set the stage for further interrogation of the She1 mechanism, and raise the question of whether similar mechanisms exist in other species.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
| |
Collapse
|
37
|
Siglin AE, Sun S, Moore JK, Tan S, Poenie M, Lear JD, Polenova T, Cooper JA, Williams JC. Dynein and dynactin leverage their bivalent character to form a high-affinity interaction. PLoS One 2013; 8:e59453. [PMID: 23577064 PMCID: PMC3618186 DOI: 10.1371/journal.pone.0059453] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 02/14/2013] [Indexed: 11/19/2022] Open
Abstract
Cytoplasmic dynein and dynactin participate in retrograde transport of organelles, checkpoint signaling and cell division. The principal subunits that mediate this interaction are the dynein intermediate chain (IC) and the dynactin p150Glued; however, the interface and mechanism that regulates this interaction remains poorly defined. Herein, we use multiple methods to show the N-terminus of mammalian dynein IC, residues 10–44, is sufficient for binding p150Glued. Consistent with this mapping, monoclonal antibodies that antagonize the dynein-dynactin interaction also bind to this region of the IC. Furthermore, double and triple alanine point mutations spanning residues 6 to 19 in the yeast IC homolog, Pac11, produce significant defects in spindle positioning. Using the same methods we show residues 381 to 530 of p150Glued form a minimal fragment that binds to the dynein IC. Sedimentation equilibrium experiments indicate that these individual fragments are predominantly monomeric, but admixtures of the IC and p150Glued fragments produce a 2:2 complex. This tetrameric complex is sensitive to salt, temperature and pH, suggesting that the binding is dominated by electrostatic interactions. Finally, circular dichroism (CD) experiments indicate that the N-terminus of the IC is disordered and becomes ordered upon binding p150Glued. Taken together, the data indicate that the dynein-dynactin interaction proceeds through a disorder-to-order transition, leveraging its bivalent-bivalent character to form a high affinity, but readily reversible interaction.
Collapse
Affiliation(s)
- Amanda E. Siglin
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Shangjin Sun
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, United States of America
| | - Jeffrey K. Moore
- Department of Cell Biology & Physiology, Washington University in Saint Louis, Saint Louis, Missouri, United States of America
| | - Sarah Tan
- Department of Cell and Molecular Biology, University of Texas, Austin, Texas, United States of America
| | - Martin Poenie
- Department of Cell and Molecular Biology, University of Texas, Austin, Texas, United States of America
| | - James D. Lear
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, United States of America
| | - John A. Cooper
- Department of Cell Biology & Physiology, Washington University in Saint Louis, Saint Louis, Missouri, United States of America
| | - John C. Williams
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Department of Molecular Medicine, Beckman Research Institute at City of Hope, Duarte, California, United States of America
- * E-mail:
| |
Collapse
|
38
|
Stuchell-Brereton MD, Siglin A, Li J, Moore JK, Ahmed S, Williams JC, Cooper JA. Functional interaction between dynein light chain and intermediate chain is required for mitotic spindle positioning. Mol Biol Cell 2011; 22:2690-701. [PMID: 21633107 PMCID: PMC3145545 DOI: 10.1091/mbc.e11-01-0075] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cytoplasmic dynein is a large multisubunit complex involved in retrograde transport and the positioning of various organelles. Dynein light chain (LC) subunits are conserved across species; however, the molecular contribution of LCs to dynein function remains controversial. One model suggests that LCs act as cargo-binding scaffolds. Alternatively, LCs are proposed to stabilize the intermediate chains (ICs) of the dynein complex. To examine the role of LCs in dynein function, we used Saccharomyces cerevisiae, in which the sole function of dynein is to position the spindle during mitosis. We report that the LC8 homologue, Dyn2, localizes with the dynein complex at microtubule ends and interacts directly with the yeast IC, Pac11. We identify two Dyn2-binding sites in Pac11 that exert differential effects on Dyn2-binding and dynein function. Mutations disrupting Dyn2 elicit a partial loss-of-dynein phenotype and impair the recruitment of the dynein activator complex, dynactin. Together these results indicate that the dynein-based function of Dyn2 is via its interaction with the dynein IC and that this interaction is important for the interaction of dynein and dynactin. In addition, these data provide the first direct evidence that LC occupancy in the dynein motor complex is important for function.
Collapse
Affiliation(s)
- Melissa D Stuchell-Brereton
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Elliott RA, Payne K, Davies LM, Moore JK, Moore EW. Children's outcomes and parents' preferences for the induction and maintenance of anaesthesia for day-case surgery. International Journal of Pharmacy Practice 2011. [DOI: 10.1111/j.2042-7174.2002.tb00671.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abstract
Focal points
Collapse
Affiliation(s)
- R A Elliott
- School of Pharmacy and Pharmaceutical Sciences, University of Manchester
| | - K Payne
- School of Pharmacy and Pharmaceutical Sciences, University of Manchester
- Health Economics Research at Manchester, School of Psychiatry and Behavioural Sciences, University of Manchester
| | - L M Davies
- School of Pharmacy and Pharmaceutical Sciences, University of Manchester
- Health Economics Research at Manchester, School of Psychiatry and Behavioural Sciences, University of Manchester
| | | | | |
Collapse
|
40
|
Abstract
Localization and activation of Elm1 at the bud neck coordinates SPC activity with mother–daughter polarity during cell division. How dividing cells monitor the effective transmission of genomes during mitosis is poorly understood. Budding yeast use a signaling pathway known as the spindle position checkpoint (SPC) to ensure the arrival of one end of the mitotic spindle in the nascent daughter cell. An important question is how SPC activity is coordinated with mother–daughter polarity. We sought to identify factors at the bud neck, the junction between mother and bud, which contribute to checkpoint signaling. In this paper, we show that the protein kinase Elm1 is an obligate regulator of the SPC, and this function requires localization of Elm1 to the bud neck. Furthermore, we show that Elm1 promotes the activity of the checkpoint kinase Kin4. These findings reveal a novel function for Elm1 in the SPC and suggest how checkpoint activity may be linked to cellular organization.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110, USA
| | | | | | | |
Collapse
|
41
|
Abstract
A strain of bacteria has been isolated which rapidly and efficiently utilizes the herbicide glyphosate (N-phosphonomethylglycine) as its sole phosphorus source in a synthetic medium. The strain (PG2982) was isolated by subculturing Pseudomonas aeruginosa ATCC 9027 in a synthetic broth medium containing glyphosate as the sole phosphorus source. Strain PG2982 differs from the culture of P. aeruginosa in that it is nonflagellated, does not produce pyocyanin, and has an absolute requirement for thiamine. Strain PG2982 has been tentatively identified as a Pseudomonas sp. strain by its biochemical activities and moles percent guanine plus cytosine. Measurements of glyphosate with an amino acid analyzer show that glyphosate rapidly disappears from the medium during exponential growth of strain PG2982. In batch culture at 30 degrees C, this isolate completely utilized 1.0 mM glyphosate in 96 h and yielded a cell density equal to that obtained with 1.0 mM phosphate as the phosphorus source. However, a longer lag phase and greater generation time were noted in the glyphosate-containing medium. Strain PG2982 can efficiently utilize glyphosate as an alternate phosphorus source.
Collapse
Affiliation(s)
- J K Moore
- Department of Microbiology and Agricultural Experiment Station, Louisiana State University, Baton Rouge, Louisiana 70803
| | | | | |
Collapse
|
42
|
Moore JK, Magidson V, Khodjakov A, Cooper JA. The spindle position checkpoint requires positional feedback from cytoplasmic microtubules. Curr Biol 2009; 19:2026-30. [PMID: 19913426 DOI: 10.1016/j.cub.2009.10.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 10/02/2009] [Accepted: 10/08/2009] [Indexed: 01/16/2023]
Abstract
The objective of mitosis is to provide a copy of the genome to each progeny of a cell division. This requires the separation of duplicate chromatids by the spindle apparatus and the delivery of one set of chromosomes to each of the daughter cells. In budding yeast, the fidelity of chromosome delivery depends on the spindle position checkpoint, which prolongs mitosis until one end of the anaphase spindle arrives in the bud. Here we tested the hypothesis that the activity of the spindle position checkpoint depends on persistent interactions between cytoplasmic microtubules and the mother-bud neck, the future site of cytokinesis. We used laser ablation to disrupt microtubule interactions with the bud neck, and we found that loss of microtubules from the neck leads to mitotic exit in a majority of checkpoint-activated cells. Our findings suggest that cytoplasmic microtubules are used to monitor the location of the spindle in the dividing cell and, in the event of positioning errors, relay a signal to inhibit mitotic exit until the spindle is appropriately positioned.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | | | | | | |
Collapse
|
43
|
Moore JK, Stuchell-Brereton MD, Cooper JA. Function of dynein in budding yeast: mitotic spindle positioning in a polarized cell. ACTA ACUST UNITED AC 2009; 66:546-55. [PMID: 19402153 DOI: 10.1002/cm.20364] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cytoplasmic dynein is a microtubule motor that powers minus-end-directed motility in a variety of biological settings. The budding yeast, Saccharomyces cerevisiae, has been a useful system for the study of dynein, due to its molecular genetics and cell biology capabilities, coupled with the conservation of dynein-pathway proteins. In this review we discuss how budding yeast use dynein to manipulate the position of the mitotic spindle and the nucleus during cell division, using cytoplasmic microtubules, and we describe our current understanding of the genes required for dynein function. Cell Motil. Cytoskeleton 2009. (c) 2009 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA.
| | | | | |
Collapse
|
44
|
Abstract
Dynactin is a multisubunit protein complex necessary for dynein function. Here, we investigated the function of dynactin in budding yeast. Loss of dynactin impaired movement and positioning of the mitotic spindle, similar to loss of dynein. Dynactin subunits required for function included p150(Glued), dynamitin, actin-related protein (Arp) 1 and p24. Arp10 and capping protein were dispensable, even in combination. All dynactin subunits tested localized to dynamic plus ends of cytoplasmic microtubules, to stationary foci on the cell cortex and to spindle pole bodies. The number of molecules of dynactin in those locations was small, less than five. In the absence of dynactin, dynein accumulated at plus ends and did not appear at the cell cortex, consistent with a role for dynactin in offloading dynein from the plus end to the cortex. Dynein at the plus end was necessary for dynactin plus-end targeting. p150(Glued) was the only dynactin subunit sufficient for plus-end targeting. Interactions among the subunits support a molecular model that resembles the current model for brain dynactin in many respects; however, three subunits at the pointed end of brain dynactin appear to be absent from yeast.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Cell Biology and Physiology, Washington University, Saint Louis, MO 63110, USA
| | | | | |
Collapse
|
45
|
Moore JK, Kitchens JW, Smiddy WE, Mavrofrides EC, Gregorio G. Retinal breaks observed during pars plana vitrectomy. Am J Ophthalmol 2007; 144:32-36. [PMID: 17509513 DOI: 10.1016/j.ajo.2007.03.048] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 03/27/2007] [Accepted: 03/30/2007] [Indexed: 11/18/2022]
Abstract
PURPOSE To quantitate the frequency and features of retinal breaks discovered at the time of vitrectomy and to evaluate the outcomes with prophylactic treatment. DESIGN A consecutive, single-surgeon, retrospective, observational case series from a two-year period. METHODS Medical records were reviewed for all patients who underwent primary, standard, three-port pars plana vitrectomy (PPV) between January 1, 2000, and December 31, 2001. Intraoperative findings recorded included the number, location, and categorization of retinal breaks and their method of management. Postoperative features recorded included the presence or absence of a retinal detachment (RD). RESULTS There were 65 retinal breaks found in 48 (11.6%) of 415 eyes and included 30 (7.2%) eyes with definite breaks, nine (2.2%) with suspicious breaks, and nine (2.2%) with probably preexisting breaks. Breaks that were described as being large (n = 5) were more commonly associated with the right-hand sclerotomy (P = .041), although other categories of breaks were not. After surgery, the overall incidence of RD was 2.2% (nine of 415 eyes). The rate of RD among the 48 eyes with retinal breaks (of any category) was also 2.1% (one eye). All RDs in this series occurred more than three months after initial vitrectomy and, accordingly, were probably unrelated to retinal breaks that occurred during surgery. CONCLUSIONS Recognition of retinal breaks and intraoperative treatment with retinopexy and air-fluid exchange during vitrectomy reduces the postoperative risk of RD to that among eyes without observed intraoperative retinal breaks.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida 33101, USA
| | | | | | | | | |
Collapse
|
46
|
Jorizzo J, Dinehart S, Matheson R, Moore JK, Ling M, Fox TL, McRae S, Fielder S, Lee JH. Vehicle-controlled, double-blind, randomized study of imiquimod 5% cream applied 3 days per week in one or two courses of treatment for actinic keratoses on the head. J Am Acad Dermatol 2007; 57:265-8. [PMID: 17512087 DOI: 10.1016/j.jaad.2007.01.047] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 01/18/2007] [Accepted: 01/31/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND A shorter dosing regimen of imiquimod for the treatment of actinic keratosis may be effective, with long-term clinical benefits. OBJECTIVE Imiquimod in one or two shorter courses of treatment was evaluated. METHODS Patients with actinic keratosis lesions on the head applied imiquimod or vehicle cream 3x/wk for 4 weeks (course 1). Patients with remaining lesions received another course of treatment. Complete and partial clearance rates were evaluated after course 1, after course 2 (overall), and 1 year later. RESULTS Complete clearance rates were 26.8% (course 1) and 53.7% (overall). Partial clearance rates were 36.6% (course 1) and 61.0% (overall). One-year follow-up recurrence rates were 39% (imiquimod) and 57% (vehicle). LIMITATIONS Blinded investigators may have been biased toward patients treated with imiquimod identified by treatment site reactions. CONCLUSION Imiquimod 3x/wk in one or two courses of treatment appears to be effective for the treatment of actinic keratoses on the head, providing long-term clinical benefits. Some recurrences do occur, so long-term follow-up is recommended.
Collapse
Affiliation(s)
- Joseph Jorizzo
- Wake Forest University School of Medicine, Department of Dermatology, Medical Center Blvd, Winston-Salem, NC 27157, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Abstract
During mitosis in the yeast Saccharomyces cerevisiae, Kar9p directs one spindle pole body (SPB) toward the incipient daughter cell by linking the associated set of cytoplasmic microtubules (cMTs) to the polarized actin network on the bud cortex. The asymmetric localization of Kar9p to one SPB and attached cMTs is dependent on its interactions with microtubule-associated proteins and is regulated by the yeast Cdk1 Cdc28p. Two phosphorylation sites in Kar9p were previously identified. Here, we propose that the two sites are likely to govern Kar9p function through separate mechanisms, each involving a distinct cyclin. In the first mechanism, phosphorylation at serine 496 recruits Kar9p to one SPB. A phosphomimetic mutation at serine 496 bypasses the requirement of BIK1 and CLB5 in generating Kar9p asymmetry. In the second mechanism, Clb4p may target serine 197 of Kar9p for phosphorylation. This modification is required for Kar9p to direct cMTs to the bud. Two-hybrid analysis suggests that this phosphorylation may attenuate the interaction between Kar9p and the XMAP215-homologue Stu2p. We propose that phosphorylation at serine 197 regulates the release of Kar9p from Stu2p at the SPB, either to clear it from the mother-SPB or to allow it to travel to the plus end.
Collapse
Affiliation(s)
- Jeffrey K. Moore
- Department of Biology, University of Rochester, Rochester, NY 14627
| | - Rita K. Miller
- Department of Biology, University of Rochester, Rochester, NY 14627
| |
Collapse
|
48
|
Abstract
Bik1p is the yeast Saccharomyces cerevisiae representative of the CLIP-170 family of microtubule plus-end tracking proteins. Bik1p shares a number of similarities with its mammalian counterpart CLIP-170, including an important role in dynein function. However, Bik1p and CLIP-170 differ in several significant ways, including the mechanisms utilized to track microtubule plus ends. In addition to presenting functional comparisons between Bik1p and CLIP-170, we provide sequence analyses that reveal previously unrecognized similarities between Bik1p and its animal counterparts. We examine in detail what is known about the functions of Bik1p and consider the various roles that Bik1p plays in positioning the yeast mitotic spindle. This chapter also highlights several recent findings, including the contribution of Bik1p to the yeast mating pathway.
Collapse
Affiliation(s)
- Rita K Miller
- Department of Biology, University of Rochester Rochester, New York 14627, USA
| | | | | | | |
Collapse
|
49
|
Abstract
Accurate positioning of the mitotic spindle in Saccharomyces cerevisiae is coordinated with the asymmetry of the two poles and requires the microtubule-to-actin linker Kar9p. The asymmetric localization of Kar9p to one spindle pole body (SPB) and microtubule (MT) plus ends requires Cdc28p. Here, we show that the CLIP-170 homologue Bik1p binds directly to Kar9p. In the absence of Bik1p, Kar9p localization is not restricted to the daughter-bound SPB, but it is instead found on both SPBs. Kar9p is hypophosphorylated in bik1delta mutants, and Bik1p binds to both phosphorylated and unphosphorylated isoforms of Kar9p. Furthermore, the two-hybrid interaction between full-length KAR9 and the cyclin CLB5 requires BIK1. The binding site of Clb5p on Kar9p maps to a short region within the basic domain of Kar9p that contains a conserved phosphorylation site, serine 496. Consistent with this, Kar9p is found on both SPBs in clb5delta mutants at a frequency comparable with that seen in kar9-S496A strains. Together, these data suggest that Bik1p promotes the phosphorylation of Kar9p on serine 496, which affects its asymmetric localization to one SPB and associated cytoplasmic MTs. These findings provide further insight into a mechanism for directing centrosomal inheritance.
Collapse
Affiliation(s)
- Jeffrey K Moore
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | | | | |
Collapse
|
50
|
Benz MS, Escalona-Benz EM, Murray TG, Eifrig CWG, Yoder DM, Moore JK, Schiffman JC. Immediate Postoperative Use of a Topical Agent to Prevent IntraocularPressure Elevation After Pars Plana Vitrectomy With Gas Tamponade. ACTA ACUST UNITED AC 2004; 122:705-9. [PMID: 15136318 DOI: 10.1001/archopht.122.5.705] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To determine whether a single topical aqueous suppressant applied immediately after pars plana vitrectomy with long-acting gas tamponade prevents intraocular pressure (IOP) elevation. METHODS Fifty patients who met the inclusion criteria and underwent pars plana vitrectomy with long-acting gas tamponade were randomized to receive a combination of timolol maleate and dorzolamide hydrochloride, long-acting timolol alone, dorzolamide alone, or placebo at the conclusion of surgery. The IOP was checked by a portable, handheld tonometer (Tono-Pen) at the conclusion of surgery and at 5 hours, 1 day, and 1 week after surgery. RESULTS There were no significant differences in IOP among the groups at the conclusion of surgery. The IOP at 5 hours after surgery (27.0 vs 17.4 mm Hg; P<.001) and 1 day after surgery (26.1 vs 19.9 mm Hg; P =.01) showed a statistically significant difference between the placebo and timolol-dorzolamide groups. The timolol-dorzolamide group showed greater IOP control than either the timolol alone or the dorzolamide alone groups at 5 hours (P =.04 for both). CONCLUSION The use of a single topical aqueous suppressant (timolol-dorzolamide) given after pars plana vitrectomy with long-acting gas tamponade effectively prevents significant postoperative IOP elevation at 5 hours and 1 day after surgery.
Collapse
Affiliation(s)
- Matthew S Benz
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL, USA
| | | | | | | | | | | | | |
Collapse
|