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Potential of Herbal Extracts and Bioactive Compounds for Human Healthcare
Published in Megh R. Goyal, Hafiz Ansar Rasul Suleria, Ramasamy Harikrishnan, The Role of Phytoconstitutents in Health Care, 2020
Ramasamy Harikrishnan, Chellam Balasundaram
TNFR1 and Fas are activation in mammalian cells, a balance between pro-apoptotic and anti-apoptotic Bcl-2 family members [659]. This balance formed from pro-apoptotic homodimers on mitochondrion outer-membrane required to make permeable for the release of caspase activators (cytochrome-c and second mitochondria-derived activator of caspases (SMAC)). The caspases play a major role of ER apoptotic signals transduction that remarkably conserved, cysteine-dependent aspartate-specific proteases. The caspases are divided into: i) initiator caspases, caspase-2, -8, -9, -10, -11, -12; and ii) effector caspases, caspase-3, -6, -7. The caspases activation is initiated by binding with a specific oligomeric activator protein; then, the caspases act as active effector caspases by proteolytic cleavage. Further, it was proteolytically degrade on a host of intracellular proteins to execute apoptosis through caspase-independent apoptotic pathway [910]. However, the destruction of cellular organelles and mRNA decay are started very early, and this mechanism is not yet fully understood [945]. Cell shrinkage and morphological changes occur by retraction lamellipodia, and the breakdown of the cell occurs by the proteinaceous cytoskeleton through caspases [95].
Cytoskeletons (F-actin) and spermatogenesis
Published in C. Yan Cheng, Spermatogenesis, 2018
Liza O’Donnell, Peter G. Stanton
The forces generated by actin filaments and networks, as well as those generated during myosin-mediated movements, create a mechanically-sensitive dynamic state, reviewed in De La Cruz and Gardel 2015.10 This mechanically sensitive state allows the cell to respond to external stimuli, for example to shear stress, but also to respond to internal cues such as forces generated within the cytoskeleton itself. Depending on the type of filament cross-linking and the abundance of myosin motors, the actin network can be arranged into various higher-order structures with different physical properties. For example, cell motility is achieved by the polymerization of branched actin filaments in lamellipodia effectively pushing the leading edge of a migrating cell forward. Actin networks can be contractile; actomyosin (actin + myosin complex)-mediated contractility is involved in many cellular functions such as exo- and endocytosis and cell shape changes. Actin networks can also be organized into ring structures; constricting actomyosin rings create the cleavage furrow between dividing cells and facilitate cytokinesis, and stabilizing actin rings are components of cell adhesion junctions.11
Soft and Hard Tissue Repair
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Sarah Al-Himdani, Ardeshir Bayat
This process involves replication and movement of the epidermal cells from the wound edges in order to reconstitute an organized, keratinized, stratified squamous epithelium. Increased mitotic activity within the basal cells of the wound edges occurs within 12 hours of wounding. Initially, migration of epidermal cells creates a delicate covering over the raw area, a process also known as ‘epiboly’. These cells then migrate, usually as a sheet, by extending lamellipodia (from the Latin lamina – thin sheet, pod – foot) from the free edge of the cut epidermis, across the defect. This process of migration is dependent on the oxygen tension present in the wound and is most rapid in hyperbaric conditions.7 ‘Contact inhibition’ prevents movement when epithelial sheets meet. Gradually, a continuous squamous cell epithelium is restored.
Dual role of E-cadherin in cancer cells
Published in Tissue Barriers, 2022
Svetlana N. Rubtsova, Irina Y. Zhitnyak, Natalya A. Gloushankova
Recently, using live cell imaging, we analyzed EMT induced by EGF in IAR-20 rat liver epithelial cells and observed sequential reorganization of AJs and the cytoskeleton during EMT (Figure 4).176 We detected fragmentation and dissolution of the circumferential actin bundle, a structure crucial for maintenance of stable linear AJs, that was followed by replacement of the stable linear E-cadherin-based AJs by dynamic punctate AJs. Punctate AJs were associated with straight actin bundles and co-localized with a tension-sensitive protein zyxin, which indicated generation of centripetal forces at the cell–cell boundaries during EMT-induced reorganization of actin cytoskeleton. Dissolution of the circumferential actin bundle may result from EGF-induced phosphorylation and degradation of the actin-binding protein EPLIN, which, as was shown earlier, stabilizes the circumferential actin bundle.25 We detected increased phosphorylation of EPLIN within minutes of addition of EGF. Simultaneously with disruption of circumferential actin bundle and linear AJs, we observed formation of dynamic lamellipodia containing branched actin network and appearance of retrograde acto-myosin flow at the cell–cell boundaries. Overall, we demostrated increased structural dynamics at the cell–cell boundaries during early stages of EMT. Of particular importance for the subsequent EMT stages was the appearance of dynamic AJs and actin structures. Cells released from stable cell–cell contacts can acquire front-rear polarity and a migratory phenotype.
Cell biophysical stimuli in lobopodium formation: a computer based approach
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Francisco Serrano-Alcalde, José Manuel García-Aznar, María José Gómez-Benito
However, cell movement mainly occurs in 3D, where cells normally adopt two modes of migration, based on lamellipodia or blebs, depending on the degree of adhesion (Te Boekhorst et al. 2016). Recently, Petrie et al. (2012) proposed a new mode of single cell migration, lobopodia-based migration, which takes place only in 3D matrices. In this migration mode, the nucleus has a relevant role. The effect of the nucleus has been studied in previous works for different situations (Allena et al. 2015; Serrano-Alcalde et al. 2017). In this case, the nucleus acts as a piston dividing the cell into two parts with different pressures. The internal pressure in the leading edge is three times larger in lobopodia-based migration than in lamellipodia-based migration (Petrie et al. 2014). In lamellipodia-based migration, the cell uses different lamellae to move instead of a single large cylindrical protrusion (lobopodium). The possibility of measuring the internal pressure of cells (Petrie and Koo 2014) addresses one of the largest differences found between these two migration modes.
Deletion of the lon gene augments expression of Salmonella Pathogenicity Island (SPI)-1 and metal ion uptake genes leading to the accumulation of bactericidal hydroxyl radicals and host pro-inflammatory cytokine-mediated rapid intracellular clearance
Published in Gut Microbes, 2020
Perumalraja Kirthika, Amal Senevirathne, Vijayakumar Jawalagatti, SungWoo Park, John Hwa Lee
Salmonella induced actin rearrangement in a host cell is essential for Salmonella entry and survival. Such manipulation helps Salmonella in better vacuolization and prevents lysosomal engagement allowing them to thrive in the host. Such phenotypic changes in the host cell induced by JOL 401 and JOL 909 were recorded during the entry phase, characterized by the trigger or zipper mechanisms. In HeLa cells (Figure 1a), both JOL 401 and JOL 909 induced lamellipodia formation characterized by membrane ruffling and formation of appendages engulfing the bacteria. However, in HepG2 cells (Figure 2b), the strains did not induce the formation of membrane extensions most likely due to the engagement of the zipper mechanism. Although no lamellipodia formation was evident in Caco-2 cells, a mild yet distinct membrane ruffling was observed when infected with JOL 401 and JOL 909 (Figure 2c). These results show that the regulation of host actin polymerization is independent of a Lon-mediated regulatory pathway. We hypothesize that this rearrangement is also partly dependent on the host cell type. To further ensure independent behavior on actin rearrangement, microscopic observations were conducted at varying time intervals of 15, 30, 45, 60, 90, and 150 min post-inoculation.