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Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
The centrosome produces the microtubules of a cell, a key component of the cytoskeleton. It directs the transport through the ER and the Golgi apparatus. Centrosomes are composed of two centrioles, which separate during cell division and help in the formation of the mitotic spindle. A single centrosome is present in animal cells. They are also found in some fungi and algae cells.
Genes and genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
The centrosome produces the microtubules of a cell—a key component of the cytoskeleton. It directs the transport through the ER and the Golgi apparatus. Centrosomes are composed of two centrioles, which separate during cell division and help in the formation of the mitotic spindle. A single centrosome is present in the animal cells. They are also found in some fungi and algae cells.
Nanotechnology-Mediated Radiation Therapy
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
The high-energy X-rays or gamma rays, and charged particles emitting from radiation therapy target the most important sub-cellular molecule DNA to cause double-strand breaks, followed by the initiation of a chain of events to promote cell death via mitotic catastrophe, apoptosis, necrosis, and autophagy, thus dictate the central dogma of radiobiology [45]. The cell cycle is a tightly regulated process that is divided into two phases: interphase comprising (G1, S, and G2 phases) and mitosis. Cells exposed to radiation, undergo DNA damage, which is sensed by the two protein kinases ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia and Rad3-related protein (ATR) causing the arrest of the cell cycle and repairing the DNA damage. The double-strand DNA breaks are mainly repaired by non-homologous end joining (NHEJ) and homologous recombination (HR) pathways [44]. Mitotic catastrophe takes place when a cell loses its ability to complete mitosis, thus controlling the cells by triggering mitotic arrest and regulated cell death. Mitotic catastrophe in irradiated cells especially solid tumors is a delayed process taking around 2–6 days during which the cells might take several attempts to repair the damage and undergo cell divisions [46]. Though the exact mechanism of the initiation of mitotic catastrophe presents unclear answers requiring further investigation, nonetheless two different ideas have been proposed to shed light on this cellular event. The first idea proposed occurs as a result of DNA damage and dysfunctional cell cycle checkpoints. It is a well-established fact that tumors possess dysfunctional cell cycle checkpoints due to impaired p53 and aberrant apoptotic signaling pathways. The presence of mutated p53 leads to premature entry into the G2/M checkpoint that contains the unrepaired DNA, ultimately leading to cell death [47]. The second idea puts forward the concept of centrosome hyper amplification. Centrosomes are the microtubules organizing centers that facilitate the systematic chromosome segregation into daughter cells during mitosis. In the case of centrosome hyper amplification, it leads to the formation of multipolar mitotic spindle that promotes atypical chromosomal segregation, and the formation of abnormal giant cells with multiple nuclei culminating in cell death [48, 49].
Astral microtubules determine the final division axis of cells confined on anisotropic surface topography
Published in Journal of Experimental Nanoscience, 2020
Kyunghee Lee, Yen Ling Koon, Jaewon Kim, Keng-Hwee Chiam, Sungsu Park
As shown in Figure 3, MTs were more elongated, condensed and aligned along the ridges when RPE-1 cells were treated with 1 μM CD. This result provides a hint that MTs are subjected to geometric constraints, such as depth, and compensate for the actin filament deficiency by fully enforcing more condensation and elongation on aligned MTs. When a cell is elongated, more MT motors, which pull the nucleus and centrosome, accumulate on the long MTs aligned to the long axis of cells than on the other short MTs [3,36]. Therefore, the centrosomes on a cell with a high R value might be more strongly pulled to the long axis of the elongated cell than those on a cell with a lower R value. Our results indicate that centrosomes are located by long MTs along the long axis and the determined division plane during interphase might be maintained by astral MTs throughout mitosis. The mechanism of spindle orientation is finally determined by the interplay between astral MTs and the cell cortex during mitosis [5,6]. We showed that spindle angles of cells on the 1 µm gratings without significant change of R value were increased by low doses of Noc (10 nM) (Figure 4(C,D)). The concentrations of Noc used in this study disrupted the dynamics of astral MTs suggesting that astral MTs have an essential role in maintaining spindle orientation since its positioning is dictated by the MT-dependent cell geometry during interphase.
Atmospheric fine particulate matter and epithelial mesenchymal transition in pulmonary cells: state of the art and critical review of the in vitro studies
Published in Journal of Toxicology and Environmental Health, Part B, 2020
Margaux Cochard, Frédéric Ledoux, Yann Landkocz
A marked cytoskeletal change occurs during EMT, first in the intermediate filaments with epithelial cytokeratin replaced by mesenchymal vimentin (Huang, Guilford, and Thiery 2012; Nalluri, O’Connor, and Gomez 2015). The microtubule dynamic is modified. Epithelial cells exhibit microtubules and a centrosome close to the cell junctions while in mesenchymal cells, microtubules and centrosome possess a central position (Margaron et al. 2019). In mesenchymal cells, microfilaments are reorganized, the actin belt disappears and actin stress fibers are organized toward cell progression, with a rise of α-SMA levels. Another important protein for cell polarization is β-catenin located at the leading edge of mesenchymal cells (Yilmaz and Christofori 2009).