scholarly journals CEP164C regulates flagellum length in stable flagella

2020 ◽  
Vol 220 (1) ◽  
Author(s):  
Madison Atkins ◽  
Jiří Týč ◽  
Shahaan Shafiq ◽  
Manu Ahmed ◽  
Eloïse Bertiaux ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Molecular Mechanisms ◽  
External Environment ◽  
Basal Bodies ◽  
The Third ◽  
Locking Mechanism ◽  
Cilia And Flagella ◽  
Insight Into ◽  
Initial Assembly

Cilia and flagella are required for cell motility and sensing the external environment and can vary in both length and stability. Stable flagella maintain their length without shortening and lengthening and are proposed to “lock” at the end of growth, but molecular mechanisms for this lock are unknown. We show that CEP164C contributes to the locking mechanism at the base of the flagellum in Trypanosoma brucei. CEP164C localizes to mature basal bodies of fully assembled old flagella, but not to growing new flagella, and basal bodies only acquire CEP164C in the third cell cycle after initial assembly. Depletion of CEP164C leads to dysregulation of flagellum growth, with continued growth of the old flagellum, consistent with defects in a flagellum locking mechanism. Inhibiting cytokinesis results in CEP164C acquisition on the new flagellum once it reaches the old flagellum length. These results provide the first insight into the molecular mechanisms regulating flagella growth in cells that must maintain existing flagella while growing new flagella.

scholarly journals A key regulatory protein for flagellum length control in stable flagella

2019 ◽  
Author(s):  
Madison Atkins ◽  
Jiří Týč ◽  
Shahaan Shafiq ◽  
Manu Ahmed ◽  
Eloïse Bertiaux ◽  
...  
Keyword(s):  
Primary Cilia ◽  
Molecular Mechanisms ◽  
Regulatory Protein ◽  
Length Change ◽  
Cell Types ◽  
Basal Bodies ◽  
Locking Mechanism ◽  
Cilia And Flagella ◽  
Eukaryotic Organisms

SummaryCilia and flagella are highly conserved microtubule-based organelles that have important roles in cell motility and sensing [1]. They can be highly dynamic and short lived such as primary cilia or Chlamydomonas [2] or very stable and long lived such as those in spermatozoa [3] photoreceptors [4] or the flagella of many protist cells [3,4]. Although there is a wide variation in length between cell types, there is generally a defined length for a given cell type [1]. Many unicellular flagellated and ciliated organisms have an additional challenge as they must maintain flagella/cilia at a defined length whilst also growing new flagella/cilia in the same cell. It is not currently understood how this is achieved. A grow-and-lock model was proposed for the maintenance of stable flagella where a molecular lock is applied to prevent flagellum length change after assembly [5]. The molecular mechanisms of how this lock operates are unknown, but could be important in cells where an existing flagellum must be maintained whilst a new flagellum assembles. Here we show that Cep164C contributes to the locking mechanism at the base of the flagellum in Trypanosoma brucei. It is only localised on the transition fibres of basal bodies of fully assembled flagella and missing from assembling flagella. In fact, basal bodies only acquire Cep164C in the third cell cycle after they assemble in trypanosomes. Depletion leads to dysregulation of flagellum growth with both longer and shorter flagella; consistent with defects in a flagellum locking mechanism. By controlling delivery of components into the old assembled flagellum, maintenance of stable flagella can occur but limits further growth. This offers an important explanation for how many eukaryotic unicellular cells maintain their existing flagella whilst growing new ones before these cells divide. This work also reveals additional regulatory roles for Cep164 in eukaryotic organisms.

scholarly journals Clinical Candidates Targeting the ATR–CHK1–WEE1 Axis in Cancer

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 795
Author(s):  
Lukas Gorecki ◽  
Martin Andrs ◽  
Jan Korabecny
Keyword(s):  
Cell Cycle ◽  
Cancer Cells ◽  
Molecular Mechanisms ◽  
Patient Survival ◽  
Current Status ◽  
Future Perspectives ◽  
Phase Ii Trials ◽  
Anticancer Treatment ◽  
Positive Outlook ◽  
Insight Into

Selective killing of cancer cells while sparing healthy ones is the principle of the perfect cancer treatment and the primary aim of many oncologists, molecular biologists, and medicinal chemists. To achieve this goal, it is crucial to understand the molecular mechanisms that distinguish cancer cells from healthy ones. Accordingly, several clinical candidates that use particular mutations in cell-cycle progressions have been developed to kill cancer cells. As the majority of cancer cells have defects in G1 control, targeting the subsequent intra‑S or G2/M checkpoints has also been extensively pursued. This review focuses on clinical candidates that target the kinases involved in intra‑S and G2/M checkpoints, namely, ATR, CHK1, and WEE1 inhibitors. It provides insight into their current status and future perspectives for anticancer treatment. Overall, even though CHK1 inhibitors are still far from clinical establishment, promising accomplishments with ATR and WEE1 inhibitors in phase II trials present a positive outlook for patient survival.

scholarly journals Epigenetic Regulation of Apoptosis and Cell Cycle in Osteosarcoma

Sarcoma ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Krithi Rao-Bindal ◽  
Eugenie S. Kleinerman
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Molecular Mechanisms ◽  
Genetic Mutations ◽  
Epigenetic Mechanisms ◽  
Epigenetic Alterations ◽  
Novel Therapeutic Strategies ◽  
Cycle Regulation ◽  
Insight Into

The role of genetic mutations in the development of osteosarcoma, such as alterations in p53 and Rb, is well understood. However, the significance of epigenetic mechanisms in the progression of osteosarcoma remains unclear and is increasingly being investigated. Recent evidence suggests that epigenetic alterations such as methylation and histone modifications of genes involved in cell cycle regulation and apoptosis may contribute to the pathogenesis of this tumor. Importantly, understanding the molecular mechanisms of regulation of these pathways may give insight into novel therapeutic strategies for patients with osteosarcoma. This paper serves to summarize the described epigenetic mechanisms in the tumorigenesis of osteosarcoma, specifically those pertaining to apoptosis and cell cycle regulation.

MicroRNA-1225-5p acts as a tumor-suppressor in laryngeal cancer via targeting CDC14B

2019 ◽  
Vol 400 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Peng Sun ◽  
Dan Zhang ◽  
Haiping Huang ◽  
Yafeng Yu ◽  
Zhendong Yang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Division ◽  
Cell Cycle Arrest ◽  
Molecular Mechanisms ◽  
Normal Tissues ◽  
Cycle Arrest ◽  
Enhanced Expression ◽  
Insight Into

Abstract This study aimed to investigate the role of miRNA-1225-5p (miR-1225) in laryngeal carcinoma (LC). We found that the expression of miR-1225 was suppressed in human LC samples, while CDC14B (cell division cycle 14B) expression was reinforced in comparison with surrounding normal tissues. We also demonstrated that enhanced expression of miR-1225 impaired the proliferation and survival of LC cells, and resulted in G1/S cell cycle arrest. In contrast, reduced expression of miR-1225 promoted cell survival. Moreover, miR-1225 resulted in G1/S cell cycle arrest and enhanced cell death. Further, miR-1225 targets CDC14B 3′-UTR and recovery of CDC14B expression counteracted the suppressive influence of miR-1225 on LC cells. Thus, these findings offer insight into the biological and molecular mechanisms behind the development of LC.

The cell division cycle of Trypanosoma brucei brucei : timing of event markers and cytoskeletal modulations

1989 ◽  
Vol 323 (1218) ◽  
pp. 573-588 ◽  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Trypanosoma Brucei ◽  
Basal Body ◽  
Single Copy ◽  
Cell Division Cycle ◽  
Basal Bodies ◽  
Division Plane ◽  
Transmission Electron ◽  
Single Nucleus

We have analysed the timing and order of events occurring within the cell division cycle of Trypanosoma brucei . Cells in the earliest stages of the cell cycle possess a single copy of three major organelles: the nucleus, the kinetoplast and the flagellum. The first indication of progress through the cell cycle is the elongation of the pro-basal body lying adjacent to the mature basal body subtending the flagellum. This newly elongated basal body occupies a posterior position within the cell when it initiates growth of the new daughter flagellum. Genesis of two new pro-basal bodies occurs only after growth of the new daughter flagellum has been initiated. Extension of the new flagellum, together with the paraflagellar rod, then continues throughout a major portion of the cell cycle. During this period of flagellum elongation, kinetoplast division occurs and the two kinetoplasts, together with the two flagellar basal bodies, then move apart within the cell. Mitosis is then initiated and a complex pattern of organelle positions is achieved whereby a division plane runs longitudinally through the cell such that each daughter ultimately receives a single nucleus, kinetoplast and flagellum. These events have been described from observations of whole cytoskeletons by transmission electron microscopy together with detection of particular organelles by fluorescence microscopy. The order and timing of events within the cell cycle has been derived from analyses of the proportion of a given cell type occurring within an exponentially growing culture.

scholarly journals Microtubule polarity and dynamics in the control of organelle positioning, segregation, and cytokinesis in the trypanosome cell cycle.

1995 ◽  
Vol 128 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
D R Robinson ◽  
T Sherwin ◽  
A Ploubidou ◽  
E H Byard ◽  
K Gull
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Brucei ◽  
Daughter Nucleus ◽  
Basal Bodies ◽  
Cortical Microtubules ◽  
Cell Extension ◽  
Microtubule Polarity ◽  
Check Points ◽  
High Degree ◽  
Attachment Zone

Trypanosoma brucei has a precisely ordered microtubule cytoskeleton whose morphogenesis is central to cell cycle events such as organelle positioning, segregation, mitosis, and cytokinesis. We have defined microtubule polarity and show the + ends of the cortical microtubules to be at the posterior end of the cell. Measurements of organelle positions through the cell cycle reveal a high degree of coordinate movement and a relationship with overall cell extension. Quantitative analysis of the segregation of the replicated mitochondrial genome (the kinetoplast) by the flagellar basal bodies identifies a new G2 cell cycle event marker. The subsequent mitosis then positions one "daughter" nucleus into the gap between the segregated basal bodies/kinetoplasts. The anterior daughter nucleus maintains its position relative to the anterior of the cell, suggesting an effective yet cryptic nuclear positioning mechanism. Inhibition of microtubule dynamics by rhizoxin results in a phenomenon whereby cells, which have segregated their kinetoplasts yet are compromised in mitosis, cleave into a nucleated portion and a flagellated, anucleate, cytoplast. We term these cytoplasts "zoids" and show that they contain the posterior (new) flagellum and associated basal-body/kinetoplast complex. Examination of zoids suggests a role for the flagellum attachment zone (FAZ) in defining the position for the axis of cleavage in trypanosomes. Progression through cytokinesis, (zoid formation) while mitosis is compromised, suggests that the dependency relationships leading to the classical cell cycle check points may be altered in trypanosomes, to take account of the need to segregate two unit genomes (nuclear and mitochondrial) in this cell.

scholarly journals An analogue-sensitive approach identifies basal body rotation and flagellum attachment zone elongation as key functions of PLK in Trypanosoma brucei

2013 ◽  
Vol 24 (9) ◽  
pp. 1321-1333 ◽  
Author(s):  
Ana Lozano-Núñez ◽  
Kyojiro N. Ikeda ◽  
Thomas Sauer ◽  
Christopher L. de Graffenried
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Rna Interference ◽  
Cell Surface ◽  
Trypanosoma Brucei ◽  
Basal Body ◽  
Basal Bodies ◽  
Body Rotation ◽  
The Many ◽  
Attachment Zone

Polo-like kinases are important regulators of cell division, playing diverse roles in mitosis and cytoskeletal inheritance. In the parasite Trypanosoma brucei, the single PLK homologue TbPLK is necessary for the assembly of a series of essential organelles that position and adhere the flagellum to the cell surface. Previous work relied on RNA interference or inhibitors of undefined specificity to inhibit TbPLK, both of which have significant experimental limitations. Here we use an analogue-sensitive approach to selectively and acutely inhibit TbPLK. T. brucei cells expressing only analogue-sensitive TbPLK (TbPLKas) grow normally, but upon treatment with inhibitor develop defects in flagellar attachment and cytokinesis. TbPLK cannot migrate effectively when inhibited and remains trapped in the posterior of the cell throughout the cell cycle. Using synchronized cells, we show that active TbPLK is a direct requirement for the assembly and extension of the flagellum attachment zone, which adheres the flagellum to the cell surface, and for the rotation of the duplicated basal bodies, which positions the new flagellum so that it can extend without impinging on the old flagellum. This approach should be applicable to the many kinases found in the T. brucei genome that lack an ascribed function.

scholarly journals Regulating the transition from centriole to basal body

2011 ◽  
Vol 193 (3) ◽  
pp. 435-444 ◽  
Author(s):  
Tetsuo Kobayashi ◽  
Brian D. Dynlacht
Keyword(s):  
Cell Cycle ◽  
Basal Body ◽  
Primary Cilia ◽  
Molecular Mechanisms ◽  
Basal Bodies ◽  
Spindle Poles ◽  
Shed Light

The role of centrioles changes as a function of the cell cycle. Centrioles promote formation of spindle poles in mitosis and act as basal bodies to assemble primary cilia in interphase. Stringent regulations govern conversion between these two states. Although the molecular mechanisms have not been fully elucidated, recent findings have begun to shed light on pathways that regulate the conversion of centrioles to basal bodies and vice versa. Emerging studies also provide insights into how defects in the balance between centrosome and cilia function could promote ciliopathies and cancer.

scholarly journals Tracing the origins of centrioles, cilia, and flagella

2011 ◽  
Vol 194 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Zita Carvalho-Santos ◽  
Juliette Azimzadeh ◽  
José. B. Pereira-Leal ◽  
Mónica Bettencourt-Dias
Keyword(s):  
Structure And Function ◽  
Core Structure ◽  
Basal Bodies ◽  
Functional Studies ◽  
Cilia And Flagella ◽  
And Function ◽  
Insight Into

Centrioles/basal bodies (CBBs) are microtubule-based cylindrical organelles that nucleate the formation of centrosomes, cilia, and flagella. CBBs, cilia, and flagella are ancestral structures; they are present in all major eukaryotic groups. Despite the conservation of their core structure, there is variability in their architecture, function, and biogenesis. Recent genomic and functional studies have provided insight into the evolution of the structure and function of these organelles.

scholarly journals P27 Promotes TGF-β-Mediated Pulmonary Fibrosis via Interacting with MTORC2

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yu-heng Dai ◽  
Xiao-qing Li ◽  
Da-peng Dong ◽  
Hai-bo Gu ◽  
Cheng-ying Kong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Interstitial Lung Disease ◽  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Therapeutic Strategy ◽  
Molecular Mechanisms ◽  
Rescue Experiment ◽  
Life Threatening ◽  
Effective Therapeutic Strategy ◽  
Insight Into

Pulmonary fibrosis (PF), a progressive and life-threatening pulmonary disease, is the main pathological basis of interstitial lung disease (ILD) which includes the idiopathic pulmonary fibrosis (IPF). No effective therapeutic strategy for pulmonary fibrosis has been established. TGF-β signaling has emerged as the vital regulator of PF; however, the detailed molecular mechanisms of TGF-β in PF were uncertain. In the present study, we proved that inhibition of MTORC2 suppresses the expression of P27 in MRC5 and HLF cells. And in bleomycin-induced PF model, the expression of α-SMA and P27 was upregulated. Moreover, TGF-β application increased the level of α-SMA, vimentin, and P27 in MRC5 and HLF cells. Furthermore, P27 overexpression advanced the cell cycle process and promoted the proliferation of MRC5 and HLF cells. Finally, the rescue experiment showed that MTORC2 knockdown reversed P27 overexpression-induced cell cycle acceleration and proliferation. Thus, our results suggest that P27 is involved in TGF-β-mediated PF, which was regulated by MTORC2, providing a novel insight into the development of PF.

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