Tubulin post-translational modifications and the construction of microtubular organelles in Trypanosoma brucei

1988 ◽  
Vol 90 (4) ◽  
pp. 577-589 ◽  
Author(s):  
R. Sasse ◽  
K. Gull
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Mitotic Spindle ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Alpha Tubulin ◽  
Daughter Cells ◽  
A Cell ◽  
Microtubular Organelles ◽  
Tubulin Content

We have used specific monoclonal antibodies to facilitate a study of acetylated and tyrosinated alpha-tubulin in the microtubule (MT) arrays in the Trypanosoma brucei cell. Acetylated alpha-tubulin is not solely located in the stable microtubular arrays but is present even in the ephemeral microtubules of the mitotic spindle. Moreover, there is a uniform distribution of this isoform in all arrays. Studies of flagella complexes show that acetylation is concomitant with assembly of MTs. There is no subsequent major modulation in the content of acetylated alpha-tubulin in MTs. Conversely, polymerizing flagellar MTs have a high tyrosinated alpha-tubulin content, which is subsequently reduced to a basal level at a discrete point in the cell cycle. The MTs of the intranuclear mitotic spindle appear never to contain tyrosinated alpha-tubulin, suggesting that they are actually constructed of detyrosinated alpha-tubulin or that detyrosination is extremely rapid at this time in the cell cycle. T. brucei therefore, represents a cell type with extremely active mechanisms for the post-translational modification of alpha-tubulin. Our analyses of the timing of acquisition and modulation in relation to MT construction in T. brucei, suggest that acetylation and detyrosination of alpha-tubulin are two independently regulated post-translational modifications, that are not uniquely associated with particular subsets of MTs of defined lability, position or function. Post-assembly detyrosination of alpha-tubulin may provide a mechanism whereby the cell could discriminate between new and old MTs, during construction of the cytoskeleton through the cell cycle. However, we also suggest that continuation of detyrosination, allows the cell, at cell division, to partition into daughter cells two equivalent sets of cytoskeletal MTs.

scholarly journals Regulation of the cell cycle and centrosome biology by deubiquitylases

2017 ◽  
Vol 45 (5) ◽  
pp. 1125-1136 ◽  
Author(s):  
Sarah Darling ◽  
Andrew B. Fielding ◽  
Dorota Sabat-Pośpiech ◽  
Ian A. Prior ◽  
Judy M. Coulson
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Mitotic Spindle ◽  
Mammalian Cells ◽  
Genetic Material ◽  
Post Translational Modification ◽  
Cellular Processes ◽  
Daughter Cells ◽  
Damage Response ◽  
A Cell

Post-translational modification of proteins by ubiquitylation is increasingly recognised as a highly complex code that contributes to the regulation of diverse cellular processes. In humans, a family of almost 100 deubiquitylase enzymes (DUBs) are assigned to six subfamilies and many of these DUBs can remove ubiquitin from proteins to reverse signals. Roles for individual DUBs have been delineated within specific cellular processes, including many that are dysregulated in diseases, particularly cancer. As potentially druggable enzymes, disease-associated DUBs are of increasing interest as pharmaceutical targets. The biology, structure and regulation of DUBs have been extensively reviewed elsewhere, so here we focus specifically on roles of DUBs in regulating cell cycle processes in mammalian cells. Over a quarter of all DUBs, representing four different families, have been shown to play roles either in the unidirectional progression of the cell cycle through specific checkpoints, or in the DNA damage response and repair pathways. We catalogue these roles and discuss specific examples. Centrosomes are the major microtubule nucleating centres within a cell and play a key role in forming the bipolar mitotic spindle required to accurately divide genetic material between daughter cells during cell division. To enable this mitotic role, centrosomes undergo a complex replication cycle that is intimately linked to the cell division cycle. Here, we also catalogue and discuss DUBs that have been linked to centrosome replication or function, including centrosome clustering, a mitotic survival strategy unique to cancer cells with supernumerary centrosomes.

scholarly journals Distinct localization and cell cycle dependence of COOH terminally tyrosinolated alpha-tubulin in the microtubules of Trypanosoma brucei brucei.

1987 ◽  
Vol 104 (3) ◽  
pp. 439-446 ◽  
Author(s):  
T Sherwin ◽  
A Schneider ◽  
R Sasse ◽  
T Seebeck ◽  
K Gull
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Temporal Modulation ◽  
Trypanosoma Brucei Brucei ◽  
Alpha Tubulin ◽  
Tubulin Isoforms ◽  
A Cell ◽  
Cell Cycle Dependence ◽  
Microtubular Structures ◽  
Cycle Dependence

alpha-Tubulin can be posttranslationally modified in that its COOH-terminal amino acid residue, tyrosine, can be selectively removed and replaced again. This reaction cycle involves two enzymes, tubulin carboxypeptidase and tubulin tyrosine ligase. The functional significance of this unusual modification is unclear. The present study demonstrates that posttranslational tyrosinolation of alpha-tubulin does occur in the parasitic hemoflagellate Trypanosoma brucei brucei and that posttranslational tyrosinolation can be detected in both alpha-tubulin isoforms found in this organism. Trypanosomes contain a number of microtubular structures: the flagellar axoneme; the subpellicular layer of singlet microtubules which are closely associated with the cell membrane; the basal bodies; and a cytoplasmic pool of soluble tubulin. Tyrosinolated alpha-tubulin is present in all these populations. However, immunofluorescence studies demonstrate a distinct localization of tyrosinolated alpha-tubulin within individual microtubules and organelles. This localization is subject to a temporal modulation that correlates strongly with progress of a cell through the cell cycle. Our results indicate that the presence of tyrosinolated alpha-tubulin is a marker for newly formed microtubules.

scholarly journals The effects of 5α-dihydrotestosterone on the kinetics of cell proliferation in rat prostate

1974 ◽  
Vol 142 (3) ◽  
pp. 483-489 ◽  
Author(s):  
Barry Lesser ◽  
Nicholas Bruchovsky
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cellular Growth ◽  
Velocity Sedimentation ◽  
Growth Fraction ◽  
Subcutaneous Injections ◽  
Daughter Cells ◽  
A Cell ◽  
Rat Prostate ◽  
Kinetics Of

The regenerating rat prostate was used as an experimental model to determine the effects of 5α-dihydrotestosterone on certain parameters of cell proliferation, including the duration of the phases of the cell cycle and the size of the cellular growth fraction. Rats castrated 7 days previously were treated with daily subcutaneous injections of 5α-dihydrotestosterone for 14 days; 48h after the beginning of therapy, cells in the process of DNA synthesis were labelled with a single injection of radioactive thymidine and the progress of these cells through the division cycle was observed. Cell-cycle analysis was performed by fractionating prostatic nuclei according to their position in the cell cycle by using the technique of velocity sedimentation under unit gravity. The results indicate that during regeneration the cell population undergoes 1.8 doublings with a doubling time of 40h, and that the process involves almost four rounds of cell division with a cell-generation time of 20h. The growth fraction at any time is about 0.5, and about half the daughter cells produced do not re-enter the proliferative cycle. All cells present at the start of regeneration eventually undergo at least one division during the course of regeneration, although any given cell can divide from one to four times.

scholarly journals Profiling of Epigenetic Features in Clinical Samples Reveals Novel Widespread Changes in Cancer

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 723 ◽  
Author(s):  
Roberta Noberini ◽  
Camilla Restellini ◽  
Evelyn Oliva Savoia ◽  
Francesco Raimondi ◽  
Lavinia Ghiani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Expression Profiles ◽  
Histone H3 ◽  
Gene Expression Profiles ◽  
Culture Conditions ◽  
Clinical Samples ◽  
Post Translational Modifications ◽  
A Cell ◽  
Cancer Types ◽  
Histone Modifying Enzymes

Aberrations in histone post-translational modifications (PTMs), as well as in the histone modifying enzymes (HMEs) that catalyze their deposition and removal, have been reported in many tumors and many epigenetic inhibitors are currently under investigation for cancer treatment. Therefore, profiling epigenetic features in cancer could have important implications for the discovery of both biomarkers for patient stratification and novel epigenetic targets. In this study, we employed mass spectrometry-based approaches to comprehensively profile histone H3 PTMs in a panel of normal and tumoral tissues for different cancer types, identifying various changes, some of which appear to be a consequence of the increased proliferation rate of tumors, while others are cell-cycle independent. Histone PTM changes found in tumors partially correlate with alterations of the gene expression profiles of HMEs obtained from publicly available data and are generally lost in culture conditions. Through this analysis, we identified tumor- and subtype-specific histone PTM changes, but also widespread changes in the levels of histone H3 K9me3 and K14ac marks. In particular, H3K14ac showed a cell-cycle independent decrease in all the seven tumor/tumor subtype models tested and could represent a novel epigenetic hallmark of cancer.

scholarly journals A role for Sar1 and ARF1 GTPases during Golgi biogenesis in the protozoan parasite Trypanosoma brucei

2017 ◽  
Vol 28 (13) ◽  
pp. 1782-1791 ◽  
Author(s):  
Sevil Yavuz ◽  
Graham Warren
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Protozoan Parasite ◽  
Small Gtpases ◽  
Intact Cells ◽  
Golgi Stack ◽  
Daughter Cells ◽  
Photoactivatable Gfp

A single Golgi stack is duplicated and partitioned into two daughter cells during the cell cycle of the protozoan parasite Trypanosoma brucei. The source of components required to generate the new Golgi and the mechanism by which it forms are poorly understood. Using photoactivatable GFP, we show that the existing Golgi supplies components directly to the newly forming Golgi in both intact and semipermeabilized cells. The movement of a putative glycosyltransferase, GntB, requires the Sar1 and ARF1 GTPases in intact cells. In addition, we show that transfer of GntB from the existing Golgi to the new Golgi can be recapitulated in semipermeabilized cells and is sensitive to the GTP analogue GTPγS. We suggest that the existing Golgi is a key source of components required to form the new Golgi and that this process is regulated by small GTPases.

scholarly journals Mitotic Kinesin-Like Protein 2 Binds and Colocalizes with Papillomavirus E2 during Mitosis

2006 ◽  
Vol 81 (4) ◽  
pp. 1736-1745 ◽  
Author(s):  
Ting Yu ◽  
Yu-Cai Peng ◽  
Elliot J. Androphy
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Chromatin Immunoprecipitation ◽  
Viral Genome ◽  
Motor Protein ◽  
Dna Binding Protein ◽  
E2 Protein ◽  
Viral Genomes ◽  
Daughter Cells ◽  
Transcription And Replication

ABSTRACT MKlp2 is a kinesin-like motor protein of the central mitotic spindle required for completion of cytokinesis. Papillomavirus E2 is a sequence specific DNA binding protein that regulates viral transcription and replication and is responsible for partitioning viral episomes into daughter cells during cell division. We demonstrate that MKlp2 specifically associates with the E2 protein during mitosis. Using chromatin immunoprecipitation, we show viral genomes are in complex with MKlp2 only within this stage of cell cycle. By immunofluorescence, a subpopulation of papillomavirus E2 colocalizes with MKlp2 in the midbody/midplate during late mitosis. We conclude that during specific stages of mitosis, the papillomavirus E2 protein binds to MKlp2, and infer that association with this motor protein ensures viral genome partitioning during cytokinesis.

scholarly journals Alpha-Tubulin Acetylation in Trypanosoma cruzi: A Dynamic Instability of Microtubules Is Required for Replication and Cell Cycle Progression

2021 ◽  
Vol 11 ◽  
Author(s):  
Victoria Lucia Alonso ◽  
Mara Emilia Carloni ◽  
Camila Silva Gonçalves ◽  
Gonzalo Martinez Peralta ◽  
Maria Eugenia Chesta ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Cruzi ◽  
Basal Body ◽  
Mitotic Spindle ◽  
Cell Cycle Progression ◽  
Dynamic Instability ◽  
Cycle Progression ◽  
Alpha Tubulin ◽  
Over Expression ◽  
Tubulin Acetylation

Trypanosomatids have a cytoskeleton arrangement that is simpler than what is found in most eukaryotic cells. However, it is precisely organized and constituted by stable microtubules. Such microtubules compose the mitotic spindle during mitosis, the basal body, the flagellar axoneme and the subpellicular microtubules, which are connected to each other and also to the plasma membrane forming a helical arrangement along the central axis of the parasite cell body. Subpellicular, mitotic and axonemal microtubules are extensively acetylated inTrypanosoma cruzi. Acetylation on lysine (K) 40 of α-tubulin is conserved from lower eukaryotes to mammals and is associated with microtubule stability. It is also known that K40 acetylation occurs significantly on flagella, centrioles, cilia, basal body and the mitotic spindle in eukaryotes. Several tubulin posttranslational modifications, including acetylation of K40, have been cataloged in trypanosomatids, but the functional importance of these modifications for microtubule dynamics and parasite biology remains largely undefined. The primary tubulin acetyltransferase was recently identified in several eukaryotes as Mec-17/ATAT, a Gcn5-related N-acetyltransferase. Here, we report thatT. cruziATAT acetylates α-tubulinin vivoand is capable of auto-acetylation.TcATAT is located in the cytoskeleton and flagella of epimastigotes and colocalizes with acetylated α-tubulin in these structures. We have expressedTcATAT with an HA tag using the inducible vector pTcINDEX-GW inT. cruzi. Over-expression ofTcATAT causes increased levels of the alpha tubulin acetylated species, induces morphological and ultrastructural defects, especially in the mitochondrion, and causes a halt in the cell cycle progression of epimastigotes, which is related to an impairment of the kinetoplast division. Finally, as a result ofTcATAT over-expression we observed that parasites became more resistant to microtubule depolymerizing drugs. These results support the idea that α-tubulin acetylation levels are finely regulated for the normal progression ofT. cruzicell cycle.

scholarly journals The oscillation of mitotic kinase governs cell cycle latches

2021 ◽  
Author(s):  
Bela Novak ◽  
John J Tyson
Keyword(s):  
Cell Cycle ◽  
Negative Feedback ◽  
Molecular Switches ◽  
Feedback Loops ◽  
Yeast Cells ◽  
Cyclin Dependent Kinases ◽  
Mitotic Kinase ◽  
Daughter Cells ◽  
Negative Feedback Loops ◽  
A Cell

SummaryIn order to transmit a eukaryotic cell’s genome accurately from mother cell to daughter cells, it is essential that the basic events of the cell division cycle (DNA synthesis and mitosis) occur once and only once per cycle, i.e., that a cell progresses irreversibly from G1 to S to G2 to M and back to G1. Irreversible progression through the cell cycle is assured by a sequence of ‘latching’ molecular switches, based on molecular interactions among cyclin-dependent kinases and their auxiliary partners. Positive feedback loops (++ or −−) create bistable switches with latching properties, and negative feedback loops drive progression from one stage to the next. In budding yeast (Saccharomyces cerevisiae) these events are coordinated by double-negative feedback loops between Clb-dependent kinases (Clb1-6) and their antagonists (APC:Cdh1 and Sic1). If the coordinating signal is compromised, either by deletion of Clb1-5 proteins or expression of non-degradable Clb2, then irreversibility is lost and yeast cells exhibit multiple rounds of DNA replication or mitotic exit events (Cdc14 endocycles). Using mathematical modelling of a stripped-down control network, we show how endocycles arise because the switches fail to latch, and the gates swing back and forth by the action of the negative feedback loops.

scholarly journals Microtubule polyglutamylation is important for regulating cytoskeletal architecture and motility in Trypanosoma brucei

2020 ◽  
Vol 133 (18) ◽  
pp. jcs248047 ◽  
Author(s):  
Jana Jentzsch ◽  
Adal Sabri ◽  
Konstantin Speckner ◽  
Gertrud Lallinger-Kube ◽  
Matthias Weiss ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Dynamic Behaviour ◽  
Cell Movement ◽  
Post Translational Modifications ◽  
Life Cycle Stages ◽  
Associated Proteins ◽  
Flagellar Axoneme

ABSTRACTThe shape of kinetoplastids, such as Trypanosoma brucei, is precisely defined during the stages of the life cycle and governed by a stable subpellicular microtubule cytoskeleton. During the cell cycle and transitions between life cycle stages, this stability has to transiently give way to a dynamic behaviour to enable cell division and morphological rearrangements. How these opposing requirements of the cytoskeleton are regulated is poorly understood. Two possible levels of regulation are activities of cytoskeleton-associated proteins and microtubule post-translational modifications (PTMs). Here, we investigate the functions of two putative tubulin polyglutamylases in T. brucei, TTLL6A and TTLL12B. Depletion of both proteins leads to a reduction in tubulin polyglutamylation in situ and is associated with disintegration of the posterior cell pole, loss of the microtubule plus-end-binding protein EB1 and alterations of microtubule dynamics. We also observe a reduced polyglutamylation of the flagellar axoneme. Quantitative motility analysis reveals that the PTM imbalance correlates with a transition from directional to diffusive cell movement. These data show that microtubule polyglutamylation has an important role in regulating cytoskeletal architecture and motility in the parasite T. brucei.This article has an associated First Person interview with the first author of the paper.

scholarly journals Cell Cycle-dependent Regulation of Structure of Endoplasmic Reticulum and Inositol 1,4,5-Trisphosphate-induced Ca2+ Release in Mouse Oocytes and Embryos

2003 ◽  
Vol 14 (1) ◽  
pp. 288-301 ◽  
Author(s):  
Greg FitzHarris ◽  
Petros Marangos ◽  
John Carroll
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Mitotic Spindle ◽  
Mitotic Division ◽  
Cyclin B ◽  
Dependent Manner ◽  
Inositol 1,4,5 Trisphosphate ◽  
A Cell ◽  
Cycle Dependent ◽  
Mouse Eggs

The organization of endoplasmic reticulum (ER) was examined in mouse eggs undergoing fertilization and in embryos during the first cell cycle. The ER in meiosis II (MII)-arrested mouse eggs is characterized by accumulations (clusters) that are restricted to the cortex of the vegetal hemisphere of the egg. Monitoring ER structure with DiI18 after egg activation has demonstrated that ER clusters disappear at the completion of meiosis II. The ER clusters can be maintained by inhibiting the decrease in cdk1-cyclin B activity by using the proteasome inhibitor MG132, or by microinjecting excess cyclin B. A role for cdk1-cyclin B in ER organization is further suggested by the finding that the cdk inhibitor roscovitine causes the loss of ER clusters in MII eggs. Cortical clusters are specific to meiosis as they do not return in the first mitotic division; rather, the ER aggregates around the mitotic spindle. Inositol 1,4,5-trisphosphate-induced Ca2+ release is also regulated in a cell cycle-dependent manner where it is increased in MII and in the first mitosis. The cell cycle dependent effects on ER structure and inositol 1,4,5-trisphosphate-induced Ca2+ release have implications for understanding meiotic and mitotic control of ER structure and inheritance, and of the mechanisms regulating mitotic Ca2+signaling.

Sign in / Sign up

Export Citation Format

Share Document