Microtubules rich in modified alpha-tubulin characterize the tail processes of motile fibroblasts

1989 ◽  
Vol 94 (2) ◽  
pp. 227-236
Author(s):  
A.R. Prescott ◽  
M. Vestberg ◽  
R.M. Warn
Keyword(s):  
Cell Motility ◽  
Immunofluorescence Microscopy ◽  
Fibroblast Cell ◽  
Microscopy Study ◽  
Post Translational Modifications ◽  
Alpha Tubulin ◽  
Major Species ◽  
Cytoplasmic Tails ◽  
Nih 3T3

The organisation of microtubules rich in post-translationally modified alpha-tubulin has been investigated in a fibroblast cell line (NIH-3T3-T15) that can be reversibly transformed. An immunofluorescence microscopy study of the static non-transformed cells has revealed a central distribution of wavy microtubules showing post-translational modifications. When transformed there is a marked increase in cell motility and the appearance of long thin cytoplasmic ‘tails’. These tails have been found to contain conspicuous bundles of post-translationally modified microtubules that run down the length of the processes and terminate close to the plasmalemma. Both detyrosinated and acetylated alpha-tubulin are present as major species in these modified microtubules. Such a pattern of modified microtubules is only occasionally seen in the untransformed NIH-3T3-T15 cells. We have also found them to be present in other transformed fibroblast lines. The presence of bundles of microtubules rich in modified alpha-tubulin in the cell tails is correlated with a marked reduction in the numbers of F-actin stress fibres. The possible role of these modified stable microtubules in cell motility is discussed.

scholarly journals The distribution of myosin II in Dictyostelium discoideum slug cells.

1991 ◽  
Vol 115 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
S Eliott ◽  
P H Vardy ◽  
K L Williams
Keyword(s):  
Cell Motility ◽  
Dictyostelium Discoideum ◽  
Immunofluorescence Microscopy ◽  
Molecular Genetic ◽  
Myosin Ii ◽  
Three Dimensional ◽  
Homogeneous Distribution ◽  
Multicellular Development ◽  
Insight Into

While the role of myosin II in muscle contraction has been well characterized, less is known about the role of myosin II in non-muscle cells. Recent molecular genetic experiments on Dictyostelium discoideum show that myosin II is necessary for cytokinesis and multicellular development. Here we use immunofluorescence microscopy with monoclonal and polyclonal antimyosin antibodies to visualize myosin II in cells of the multicellular D. discoideum slug. A subpopulation of peripheral and anterior cells label brightly with antimyosin II antibodies, and many of these cells display a polarized intracellular distribution of myosin II. Other cells in the slug label less brightly and their cytoplasm displays a more homogeneous distribution of myosin II. These results provide insight into cell motility within a three-dimensional tissue and they are discussed in relation to the possible roles of myosin II in multicellular development.

scholarly journals The dynamic and structural properties of axonemal tubulins support the high length stability of cilia

2018 ◽  
Author(s):  
Ron Orbach ◽  
Jonthon Howard
Keyword(s):  
Cell Motility ◽  
Structural Properties ◽  
Dynamic Properties ◽  
Post Translational Modifications ◽  
Growth Stability ◽  
Cilia And Flagella ◽  
High Length

Cilia and flagella, which play essential roles in cell motility, sensing and development, contain at their core a microtubule-based structure called axoneme. The axoneme, which contains nine doublet and two central microtubules, is highly stable and its length is precisely-controlled. We have asked whether the axonemal tubulins contribute to this length stability. Towards this end, we used a novel procedure to differentially extract the tubulins from the different axoneme components, and characterized their dynamic properties and post-translational modifications (PTMs). We found that their dynamic properties are consistent with the greater stability of axonemes. Despite the differences in PTMs between the axonemal components, we found no significant differences in their dynamic properties. Unexpectedly, the reconstituted ciliary microtubules exhibit curved protofilaments at their growing tip, that may correspond to the fluctuating GTP-cap hypothesized to exist. Thus, our study provides new insights into the growth, stability and the role of PTMs of ciliary tubulin.

scholarly journals Development and Optimization of Naringenin-Loaded Chitosan-Coated Nanoemulsion for Topical Therapy in Wound Healing

Pharmaceutics ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 893 ◽  
Author(s):  
Sabah H. Akrawi ◽  
Bapi Gorain ◽  
Anroop B. Nair ◽  
Hira Choudhury ◽  
Manisha Pandey ◽  
...  
Keyword(s):  
Wound Healing ◽  
Topical Therapy ◽  
Statistical Design ◽  
Fibroblast Cell ◽  
Tween 20 ◽  
Wound Model ◽  
Globule Size ◽  
Nih 3T3

The potential role of naringenin (NAR), a natural flavonoid, in the treatment of chronic wound has prompted the present research to deliver the drug in nanoemulsion (NE) form, where synergistic role of chitosan was achieved through development of chitosan-coated NAR NE (CNNE). The NE consisted of Capryol 90, Tween 20 and Transcutol P, which was fabricated by low-energy emulsification method to encapsulate NAR within the oil core. The optimization of the formulated NEs was performed using Box–Behnken statistical design to obtain crucial variable parameters that influence globule size, size distribution and surface charge. Finally, the optimized formulation was coated with different concentrations of chitosan and subsequently characterized in vitro. The size of the CNNE was found to be increased when the drug-loaded formulation was coated with chitosan. Controlled release characteristics depicted 67–81% release of NAR from the CNNE, compared to 89% from the NE formulation. Cytotoxicity study of the formulation was performed in vitro using fibroblast cell line (NIH-3T3), where no inhibition in proliferation of the cells was observed with CNNE. Finally, the wound healing potential of the CNNE was evaluated in an abrasion-created wound model in experimental animals where the animals were treated and compared histologically at 0 and 14 days. Significant improvement in construction of the abrasion wound was observed when the animals were treated with formulated CNNE, whereas stimulation of skin regeneration was depicted in the histological examination. Therefore, it could be summarized that the chitosan coating of the developed NAR NE is a potential platform to accelerate healing of wounds.

scholarly journals The Tubulin Code in Mitosis and Cancer

2020 ◽  
Author(s):  
Danilo Lopes ◽  
Helder Maiato
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Chromosomal Instability ◽  
Metaphase Plate ◽  
Post Translational Modifications ◽  
Alpha Tubulin ◽  
Therapeutic Implications ◽  
Human Cancers ◽  
Functional Implications

The “tubulin code” combines different α/β-tubulin isotypes with several post-translational modifications (PTMs) to generate microtubule diversity in cells. During cell division, specific microtubule populations in the mitotic spindle are differentially modified, but only recently has the functional significance of these modifications started to be elucidated. In particular, α-tubulin detyrosination of stable microtubules in the spindle was shown to guide chromosomes during congression to the metaphase plate and allow the discrimination of mitotic errors, whose correction is required to prevent chromosomal instability (CIN), a hallmark of human cancers. Although alterations in certain tubulin PTMs have been reported in human cancers, it remains unclear whether and how tubulin PTMs have any functional implications for cancer cell properties. Here we review the role of the tubulin code in chromosome segregation during mitosis, together with the emerging cancer tubulin code and discuss possible links, as well as the respective diagnostic, prognostic and therapeutic implications for human cancers.

scholarly journals Endocytosis via coated pits mediated by glycoprotein receptor in which the cytoplasmic tail is replaced by unrelated sequences.

1990 ◽  
Vol 1 (6) ◽  
pp. 471-486 ◽  
Author(s):  
F Verrey ◽  
T Gilbert ◽  
T Mellow ◽  
G Proulx ◽  
K Drickamer
Keyword(s):  
High Efficiency ◽  
Cytoplasmic Tail ◽  
Fibroblast Cell ◽  
Alternative Mechanism ◽  
Coated Pits ◽  
Chimeric Receptors ◽  
Receptor Localization ◽  
Cytoplasmic Tails ◽  
Fibroblast Cell Lines

Rat 6 fibroblast cell lines expressing wild-type chicken liver glycoprotein receptor (CHL) or chimeric receptors with alternate cytoplasmic tails were produced to study the role of the cytoplasmic tail in mediating receptor localization in coated pits and endocytosis of ligand. Cells expressing CHL or cells expressing a hybrid receptor that contains the cytoplasmic tail of the asialoglycoprotein receptor display high-efficiency endocytosis of N-acetylglucosamine-conjugated bovine serum albumin in experiments designed to measure an initial internalization step, as well as in studies of continuous uptake and degradation. Substitution of the cytoplasmic tail by the equivalent domain of rat Na,K-ATPase beta subunit or by a stretch of Xenopus laevis globin beta chain does not abolish endocytosis but decreases the endocytosis rate constant from 15%-16%/min to 2.4% and 6.5%/min, respectively. Electron microscopy was used to visualize the glycoprotein binding sites at the surface of Rat 6 cells transfected with the various receptors. The percentage of receptors found in coated areas ranged from 32% for CHL to 9% for the Na,K-ATPase hybrid, indicating that clustering in coated pits correlates with efficiency of endocytosis. We concluded that replacement of the CHL cytoplasmic tail with unrelated sequences does not prevent, but decreases to varying extents, coated-pit localization and endocytosis efficiency. The construct with NH2-terminal globin tail lacks a signal for high-efficiency localization in coated pits but nevertheless is directed to the pits by an alternative mechanism.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

scholarly journals System-wide identification and prioritization of enzyme substrates by thermal analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Amir Ata Saei ◽  
Christian M. Beusch ◽  
Pierre Sabatier ◽  
Juan Astorga Wells ◽  
Hassan Gharibi ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thioredoxin Reductase ◽  
Structural Level ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Enzyme Substrate ◽  
Thioredoxin Reductase 1 ◽  
Enzyme Substrates ◽  
Substrate Proteins

AbstractDespite the immense importance of enzyme–substrate reactions, there is a lack of general and unbiased tools for identifying and prioritizing substrate proteins that are modified by the enzyme on the structural level. Here we describe a high-throughput unbiased proteomics method called System-wide Identification and prioritization of Enzyme Substrates by Thermal Analysis (SIESTA). The approach assumes that the enzymatic post-translational modification of substrate proteins is likely to change their thermal stability. In our proof-of-concept studies, SIESTA successfully identifies several known and novel substrate candidates for selenoprotein thioredoxin reductase 1, protein kinase B (AKT1) and poly-(ADP-ribose) polymerase-10 systems. Wider application of SIESTA can enhance our understanding of the role of enzymes in homeostasis and disease, opening opportunities to investigate the effect of post-translational modifications on signal transduction and facilitate drug discovery.

scholarly journals Phosphorylation of RCC1 on Serine 11 Facilitates G1/S Transition in HPV E7-Expressing Cells

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 995
Author(s):  
Xiaoyan Hou ◽  
Lijun Qiao ◽  
Ruijuan Liu ◽  
Xuechao Han ◽  
Weifang Zhang
Keyword(s):  
Cell Cycle ◽  
Cervical Cancer ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Mtor Pathway ◽  
Cycle Progression ◽  
Post Translational Modifications ◽  
Hpv E7 ◽  
Cycle Regulation

Persistent infection of high-risk human papillomavirus (HR-HPV) plays a causal role in cervical cancer. Regulator of chromosome condensation 1 (RCC1) is a critical cell cycle regulator, which undergoes a few post-translational modifications including phosphorylation. Here, we showed that serine 11 (S11) of RCC1 was phosphorylated in HPV E7-expressing cells. However, S11 phosphorylation was not up-regulated by CDK1 in E7-expressing cells; instead, the PI3K/AKT/mTOR pathway promoted S11 phosphorylation. Knockdown of AKT or inhibition of the PI3K/AKT/mTOR pathway down-regulated phosphorylation of RCC1 S11. Furthermore, S11 phosphorylation occurred throughout the cell cycle, and reached its peak during the mitosis phase. Our previous data proved that RCC1 was necessary for the G1/S cell cycle progression, and in the present study we showed that the RCC1 mutant, in which S11 was mutated to alanine (S11A) to mimic non-phosphorylation status, lost the ability to facilitate G1/S transition in E7-expressing cells. Moreover, RCC1 S11 was phosphorylated by the PI3K/AKT/mTOR pathway in HPV-positive cervical cancer SiHa and HeLa cells. We conclude that S11 of RCC1 is phosphorylated by the PI3K/AKT/mTOR pathway and phosphorylation of RCC1 S11 facilitates the abrogation of G1 checkpoint in HPV E7-expressing cells. In short, our study explores a new role of RCC1 S11 phosphorylation in cell cycle regulation.

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