scholarly journals Cilium structure, assembly, and disassembly regulated by the cytoskeleton

2018 ◽  
Vol 475 (14) ◽  
pp. 2329-2353 ◽  
Author(s):  
Mary Mirvis ◽  
Tim Stearns ◽  
W. James Nelson
Keyword(s):  
Cell Polarity ◽  
Control Cell ◽  
Microtubule Dynamics ◽  
Function Structure ◽  
Post Translational Modifications ◽  
The Core ◽  
Associated Proteins ◽  
Differentiation And Proliferation ◽  
Structure Assembly ◽  
Cilium Function

The cilium, once considered a vestigial structure, is a conserved, microtubule-based organelle critical for transducing extracellular chemical and mechanical signals that control cell polarity, differentiation, and proliferation. The cilium undergoes cycles of assembly and disassembly that are controlled by complex inter-relationships with the cytoskeleton. Microtubules form the core of the cilium, the axoneme, and are regulated by post-translational modifications, associated proteins, and microtubule dynamics. Although actin and septin cytoskeletons are not major components of the axoneme, they also regulate cilium organization and assembly state. Here, we discuss recent advances on how these different cytoskeletal systems­ affect cilium function, structure, and organization.

scholarly journals Stu2p binds tubulin and undergoes an open-to-closed conformational change

2006 ◽  
Vol 172 (7) ◽  
pp. 1009-1022 ◽  
Author(s):  
Jawdat Al-Bassam ◽  
Mark van Breugel ◽  
Stephen C. Harrison ◽  
Anthony Hyman
Keyword(s):  
Conformational Change ◽  
Conformational Transition ◽  
Budding Yeast ◽  
Microtubule Dynamics ◽  
Open Structure ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Common

Stu2p from budding yeast belongs to the conserved Dis1/XMAP215 family of microtubule-associated proteins (MAPs). The common feature of proteins in this family is the presence of HEAT repeat–containing TOG domains near the NH2 terminus. We have investigated the functions of the two TOG domains of Stu2p in vivo and in vitro. Our data suggest that Stu2p regulates microtubule dynamics through two separate activities. First, Stu2p binds to a single free tubulin heterodimer through its first TOG domain. A large conformational transition in homodimeric Stu2p from an open structure to a closed one accompanies the capture of a single free tubulin heterodimer. Second, Stu2p has the capacity to associate directly with microtubule ends, at least in part, through its second TOG domain. These two properties lead to the stabilization of microtubules in vivo, perhaps by the loading of tubulin dimers at microtubule ends. We suggest that this mechanism of microtubule regulation is a conserved feature of the Dis1/XMAP215 family of MAPs.

scholarly journals The core planar cell polarity gene, Vangl2 , maintains apical‐basal organisation of the corneal epithelium

2017 ◽  
Vol 234 (1) ◽  
pp. 106-119 ◽  
Author(s):  
D. Alessio Panzica ◽  
Amy S. Findlay ◽  
Rianne Ladesteijn ◽  
J. Martin Collinson
Keyword(s):  
Cell Polarity ◽  
Corneal Epithelium ◽  
Planar Cell Polarity ◽  
The Core ◽  
Polarity Gene

scholarly journals The core planar cell polarity gene, Vangl2 , directs adult corneal epithelial cell alignment and migration

2016 ◽  
Vol 3 (10) ◽  
pp. 160658 ◽  
Author(s):  
Amy S. Findlay ◽  
D. Alessio Panzica ◽  
Petr Walczysko ◽  
Amy B. Holt ◽  
Deborah J. Henderson ◽  
...  
Keyword(s):  
Cell Migration ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Corneal Epithelium ◽  
Planar Cell Polarity ◽  
Corneal Epithelial Cell ◽  
Corneal Epithelial Cells ◽  
Corneal Epithelial ◽  
The Core

This study shows that the core planar cell polarity (PCP) genes direct the aligned cell migration in the adult corneal epithelium, a stratified squamous epithelium on the outer surface of the vertebrate eye. Expression of multiple core PCP genes was demonstrated in the adult corneal epithelium. PCP components were manipulated genetically and pharmacologically in human and mouse corneal epithelial cells in vivo and in vitro . Knockdown of VANGL2 reduced the directional component of migration of human corneal epithelial (HCE) cells without affecting speed. It was shown that signalling through PCP mediators, dishevelled, dishevelled-associated activator of morphogenesis and Rho-associated protein kinase directs the alignment of HCE cells by affecting cytoskeletal reorganization. Cells in which VANGL2 was disrupted tended to misalign on grooved surfaces and migrate across, rather than parallel to the grooves. Adult corneal epithelial cells in which Vangl2 had been conditionally deleted showed a reduced rate of wound-healing migration. Conditional deletion of Vangl2 in the mouse corneal epithelium ablated the normal highly stereotyped patterns of centripetal cell migration in vivo from the periphery (limbus) to the centre of the cornea. Corneal opacity owing to chronic wounding is a major cause of degenerative blindness across the world, and this study shows that Vangl2 activity is required for directional corneal epithelial migration.

Regulation of Microtubule Assembly: The View From The End

2000 ◽  
Vol 6 (S2) ◽  
pp. 80-81
Author(s):  
L. Cassimeris ◽  
C. Spittle ◽  
M. Kratzer
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Dynamic Instability ◽  
Intrinsic Property ◽  
Microtubule Dynamics ◽  
Microtubule Assembly ◽  
Chromosome Movement ◽  
Spindle Formation ◽  
Associated Proteins

The mitotic spindle is responsible for chromosome movement during mitosis. It is composed of a dynamic array of microtubules and associated proteins whose assembly and constant turnover are required for both spindle formation and chromosome movement. Because microtubule assembly and turnover are necessary for chromosome segregation, we are studying how cells regulate microtubule dynamics. Microtubules are polarized polymers composed of tubulin subunits; they assemble by a process of dynamic instability where individual microtubules exist in persistent phases of elongation or rapid shortening with abrupt transitions between these two states. The switch from elongation to shortening is termed catastrophe, and the switch from shortening to elongation, rescue. Although dynamic instability is an intrinsic property of the tubulin subunits, cells use associated proteins to both speed elongation (∼ 10 fold) and regulate transitions.The only protein isolated to date capable of promoting fast polymerization consistent with rates in vivo is XMAP215, a 215 kD protein from Xenopus eggs.

Post-ovulatory ageing of mouse oocytes affects the distribution of specific spindle-associated proteins and Akt expression levels

2014 ◽  
Vol 26 (4) ◽  
pp. 562 ◽  
Author(s):  
Sandra Cecconi ◽  
Gianna Rossi ◽  
Hamid Deldar ◽  
Valerio Cellini ◽  
Felice Patacchiola ◽  
...  
Keyword(s):  
Histone H3 ◽  
Meiotic Spindle ◽  
Post Translational Modifications ◽  
Expression Levels ◽  
Acetylated Tubulin ◽  
Protein Levels ◽  
Histone 3 ◽  
Phosphorylated Akt ◽  
Associated Proteins

The aim of this study has been to determine the effects of in vivo post-ovulatory ageing (POA) on the distribution of spindle-associated proteins, histone H3/H4 post-translational modifications and on v-akt murine thymoma viral oncogene homolog 1 (Akt) expression levels. To this end, oocytes were retrieved 13, 29 and 33 h after human chorionic gonadotrophin (hCG) treatment. The presence and distribution at the meiotic spindle of acetylated tubulin, γ-tubulin, polo kinase-1 and Ser473/Thr308 phosphorylated Akt (pAkt) as well as histone H3 and H4 acetylation and phosphorylation levels were assayed via immunofluorescence. Akt expression levels were determined via reverse transcription–polymerase chain reaction and western blotting analyses. Spindles from oocytes recovered 13 h and 29 h after hCG treatment showed similar levels of acetylated tubulin but ageing induced: (1) translocation of γ-tubulin from spindle poles to microtubules, (2) absence of Thr308- and Ser473-pAkt in 76% and 30% of oocytes, respectively, and (3) a significant reduction in phosphorylation levels of serine 10 on histone 3. At 29 h, a significant decrease in Akt mRNA, but not in pAkt or Akt protein levels, was recorded. By contrast, protein content significantly decreased 33 h after hCG. We conclude that POA impairs oocyte viability and fertilisability by altering the expression levels and spindle distribution of proteins that are implicated in cell survival and chromosome segregation. Together, these events could play a role in oocyte apoptosis.

scholarly journals Classical cadherins control nucleus and centrosome position and cell polarity

2009 ◽  
Vol 185 (5) ◽  
pp. 779-786 ◽  
Author(s):  
Isabelle Dupin ◽  
Emeline Camand ◽  
Sandrine Etienne-Manneville
Keyword(s):  
Cell Polarity ◽  
Control Cell ◽  
Cell Types ◽  
Free Cell ◽  
Cell Polarization ◽  
Cell Interactions ◽  
Spatial Cues ◽  
Cell Contacts ◽  
Classical Cadherins ◽  
Cell Cell

Control of cell polarity is crucial during tissue morphogenesis and renewal, and depends on spatial cues provided by the extracellular environment. Using micropatterned substrates to impose reproducible cell–cell interactions, we show that in the absence of other polarizing cues, cell–cell contacts are the main regulator of nucleus and centrosome positioning, and intracellular polarized organization. In a variety of cell types, including astrocytes, epithelial cells, and endothelial cells, calcium-dependent cadherin-mediated cell–cell interactions induce nucleus and centrosome off-centering toward cell–cell contacts, and promote orientation of the nucleus–centrosome axis toward free cell edges. Nucleus and centrosome off-centering is controlled by N-cadherin through the regulation of cell interactions with the extracellular matrix, whereas the orientation of the nucleus–centrosome axis is determined by the geometry of N-cadherin–mediated contacts. Our results demonstrate that in addition to the specific function of E-cadherin in regulating baso-apical epithelial polarity, classical cadherins control cell polarization in otherwise nonpolarized cells.

scholarly journals Connexin43 Modulates Cell Polarity and Directional Cell Migration by Regulating Microtubule Dynamics

PLoS ONE ◽  
2011 ◽  
Vol 6 (10) ◽  
pp. e26379 ◽  
Author(s):  
Richard Francis ◽  
Xin Xu ◽  
Hyunsoo Park ◽  
Chin-Jen Wei ◽  
Stephen Chang ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cell Polarity ◽  
Microtubule Dynamics ◽  
Directional Cell Migration
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