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Nanomagnetic Actuation: Controlling Cell Behavior with Magnetic Nanoparticles
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
The precise methods by which the various cell types monitor and respond to mechanical stimuli are not fully understood. However, the methods by which cells attach and monitor their various extracellular matrices, share numerous commonalities. One such method is by attaching directly to the extracellular matrix via transmembrane glycoproteins known as cell surface integrins. These heterodimeric proteins consist of two distinct subunits known as α and β. There are currently 16α and 9β subunits known to exist, which can combine to form a variety of integrins with distinct binding specificities. The intracellular region of the α chain is physically connected to the cytoskeleton via interaction with talin, vinculin, and α-actinin. It is this connection that enables integrins to transduce mechanical stimuli from the extracellular matrix into the intracellular environment (Burridge et al. 1988).
The logic of living assembly
Published in Martyn Dade-Robertson, Living Construction, 2020
The process illustrated in Figure 3.3 is found in protein assemblies where a number of independent protein molecules will fit together to form protein complexes. These parts might include two different types of protein: ‘heterodimers’, which are fitted together asymmetrically, and ‘homomers’, which are made of two or more identical proteins, often symmetrically arranged. These complexes form through ‘avidity’, which is a weak patterning of forces where multiple points of contact in a protein assembly make up for the fact that the individual forces are weak. The weak forces involved also act as a self-checking mechanism, as the molecules will tend, in energetic conditions, to break apart because they are only stable when they are assembled correctly. Through this assembly method, it is possible to form macro structures, with different assemblies forming linear, cubic and lattice patterns (Norn and André, 2016).
Drug Carrier Systems for Anticancer Agents
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
Hiroyuki Koide, Tomohiro Asai, Kosuke Shimizu, Naoto Oku
Integrins αVβ3 and αVβ5 are also overexpressed on tumor endothelial cells (Varner and Cheresh 1996). Integrins are composed of 8 different types of α-subunit and 18 types of β-subunit that assemble into at least 24 distinct integrins, and this heterodimer composition generally confers ligand specificity (Johnson 1999, Seftor et al. 1999). Integrins play roles in cell–ECM interaction and in cell–cell adhesion (Van Belle et al. 1999). The importance of these integrins in angiogenesis is remarkable. Inhibition of integrin αVβ3 functions such as adhesion and signal transduction by antibody suppressed cancer growth through inhibiting vitronectin binding to endothelial cells during angiogenesis (Brooks et al. 1994, Hodivala-Dilke et al. 2003).
Toxicological sensitivity of Pennisetum americanum (L.) K. Schum to atrazine exposure
Published in International Journal of Phytoremediation, 2018
Zhao Jiang, Guangxia Su, Jinmei Li, Bingbing Ma, Yukun Chen, Dexin Shan, Ying Zhang
However, atrazine has been reported to exhibit biotoxicity toward many non-target organisms, even at ppb (parts per billion, μg/L or μg/kg) concentrations (Hayes et al. 2010; Sanderson et al. 2000, 2001). Therefore, atrazine threshold value in ground and drinking water of Europe and North America must not exceed 0.1 μg/L (Vonberg et al. 2014). In addition, phytotoxicity studies have shown that atrazine can inhibit the elongation and biomass of sensitive plants after being absorbed by the roots (Su and Zhu, 2007; Tang et al. 1997). This toxicity was due in part to damage to photosystem II (PSII) of sensitive plants; atrazine could inhibit photosynthesis by displacing the secondary quinone acceptor of the electron transport chain from its binding site (Gao et al. 2011). As a result, the D1 protein, which forms a heterodimer with the D2 protein in the reaction center of PSII, was degraded rapidly and chlorophyll synthesis was affected accordingly (Sen et al. 2014, Zhang et al. 2014). Therefore, atrazine has been selected as a model toxicant in phytotoxicity studies. In addition, atrazine can cause oxidative stress to cell membranes, resulting in cell damage or death (Akbulut and Yigit, 2010; Liu et al. 2013). Additionally, as it has a long residual period and high mobility, atrazine can be detected in soil, surface water, and groundwater years after its initial application (Stipičević et al. 2015). Therefore, the increasing residual amount of atrazine in both soil and water poses a significant threat to environment safety.
Agrochemical-mediated cardiotoxicity in zebrafish embryos/larvae: What we do and where we go
Published in Critical Reviews in Environmental Science and Technology, 2023
Yang Yang, Yue Tao, Zixu Li, Yunhe Cui, Jinzhu Zhang, Ying Zhang
At the cardiac developmental level, endocardium-specific expression of Notch signaling regulates cardiac morphogenesis by interacting with multiple signals from the myocardium and epicardium. Disturbances in normal Notch signaling expression induce congenital heart disease and cardiomyopathy (Guillermo et al., 2016; Niessen & Karsan, 2008). In contrast to in humans, Notch receptors and ligands are more abundant in zebrafish but the core activation mechanisms and functions of the Notch signaling pathway are highly conserved across species (Masek & Andersson, 2017). Unlike in the general signaling pathway, both the receptor and ligand of the Notch signaling pathway are membrane proteins, which function as contact points between two cells. When the Notch signaling pathway is activated, the Notch receptor is cleaved three times (1: in the cytoplasm, furin protease in the Golgi apparatus converts Notch protein single-chain precursors into heterodimers via calcium-dependent non-covalent bonding by cleaving the s1 site at the extracellular end of the Notch transmembrane region; 2: when the Notch ligand binds to the extracellular domain of a heterodimer translocated to the cell membrane, ADAM metalloproteinase releases part of the extracellular fragment by cleaving the S2 site on the receptor; 3: γ-secretase cleaves the S3 site on the remaining heterodimer adhered to the cell membrane and forms the Notch intracellular domain) and eventually releases this domain, which forms a transcriptional complex with the CSL in the nucleus, thereby activating expression of the relevant genes (Nemir & Pedrazzini, 2008) (Figure 4).
Prediction of protein folding kinetics states using hybrid brainstorm optimization
Published in International Journal of Computers and Applications, 2020
M. Anbarasi, M. A. Saleem Durai
Protein folding type is highly intriguing to recognize the association between essential types of dimeric and monomeric protein. Proteins can undergo the folding process to form a stable construction with stable intermediates (MS or 3S) or without intermediates (2S). To appraise the proportions of folding for different proteins by means of this component, authors initially decided the likelihood of unevenly inspecting an adaptation with the local overlap topology [1]. The 2-State equilibrium folding mechanism has been reported by different groups [2,3], as these studies represent the absence of well-defined intermediate conformations. Monomeric proteins can crinkle by pure 2-State kinetic or via populated stable intermediate state [4]. Dimeric proteins also crinkle toward their built-in state without or with intermediates. Therefore, there are no essential differences between dimers and monomers in folding [5]. Homodimer protein shows the most important role happening as catalysis and instruction of folding and exists as incredibly charming. Purposes of folding done with the current experiments are very time-consuming and tedious. However, it acts as a significant role in the considerate structural plan and folding design of homodimers. Moreover, specific homodimers have been exploited as drug targets and are patented [6,7]. Heterodimer protein enactment plays a leading role in immunity, catalysis, inhibition, guidelines and assembly. Development of two different proteins contains a stable interface. The clustering algorithms are used to construct a model for predicting the protein folding kinetics states based on the structural features.