China 
Africa 
Explore chapters and articles related to this topic
Signal Transduction
Published in Markus W. Covert, Fundamentals of Systems Biology, 2017
Let’s first look at how the signal is initially detected. A cell might sense the presence of food, an enemy such as a virus or microbe, or other friendly cells in its natural environment. The particular molecules that are detected (for example, a molecule found on the virus surface or a protein that is secreted by a cell) are often called ligands, and bind to proteins called receptors on the cell surface (Figure 8.2). Receptor proteins typically span the cell membrane, so a conformational change on one side of the membrane can alter the protein’s binding affinity or kinetic properties on the other side. Active receptor proteins then recruit adaptor proteins, which bind the receptor protein domains inside the cell and recruit still other proteins. As the signal is transduced (moved from protein to protein and from one part of the cell to another), it can be amplified (by one protein activating many others) or integrated (as a protein responds to many signals at once). A common final outcome of signaling involves the movement of certain molecules to another cellular compartment; for example, a transcription factor may move from the cytoplasm into the nucleus and induce the transcription of genes.
Molecular Motors
Published in Yubing Xie, The Nanobiotechnology Handbook, 2012
Timothy D. Riehlman, Zachary T. Olmsted, Janet L. Paluh
The use of motor proteins in nanoengineering design becomes important when active transport over distances is required. For small distances and small particles, passive transport by diffusion is preferable for speed and simplicity (Hess and Vogel, 2001). In cells, the viscous gel-like interior saturated with proteins results in sharply decreased diffusion rates as the size of cargo increases. The need to transport larger particles while navigating an increasingly viscous and complex cell interior likely contributed to the evolution of motor proteins in cells (Luby-Phelps, 1994). Kinesin is highly evolved to handle the cellular environment. It undergoes highly processive 8 nm steps against an opposing force of 6 pN and is able to drag cargo through this gel with a mesh size of roughly 50 nm. The typical chemical efficiency of the kinesin motor is 50%, as measured by the ratio between performed work and free energy of ATP (Kawaguchi and Ishiwata, 2000). In the task of finding cargo, the stalk domain of kinesin is ~50 nm long (Song and Mandekow, 1994) and capable of high rotational flexibility that is ideally suited for capturing cargo when not precisely oriented for transport. Specificity for cargo occurs through associated adaptor proteins. In nanoengineering applications, truncated forms of kinesin or Klps may be warranted but requires that specific parameters of each motor and the role of each domain be carefully considered. Table 4.2 provides a comparison of typical motor parameters. For in vitro applications with motors, the tail and stalk domains are frequently truncated or altered or functionalized to create a “designer motor protein.” Chimeric Klps can be generated by transferring desired functional domains from one motor protein to another (Simeonov et al., 2009). As optimally designed motor proteins are generated, additional features such as protein stability or instability can be engineered in, relying on insights from extremophile organisms.
The polymorphisms in cGAS-STING pathway are associated with mitochondrial DNA copy number in coke oven workers
Published in International Journal of Environmental Health Research, 2022
Xiaohua Liu, Xinling Li, Wan Wei, Yahui Fan, Zhifeng Guo, Xiaoran Duan, Xiaoshan Zhou, Yongli Yang, Wei Wang
The cGAS-STING pathway plays an important role in DNA damage response, transcriptional induction of type I interferons, and nuclear factorκBdependent expression of proinflammatory cytokines (Motwani et al. 2019). When PAHs cause damage to mitochondria, mtDNA can be released into the cytoplasm from mitochondria. The cGAS genes, located on chromosome 6, encode DNA-sensing nucleotidyl transferase enzymes, which can detect damaged DNA that was released into the cytosol. Upon DNA binding, cGAS produces cyclic guanosine monophosphate adenosine monophosphate and then activates the adaptor protein STING (Chen et al. 2016), ultimately promote immunity and influence nuclear DNA repair. STING genes, located on chromosome 5, have a cGAS-independent innate immune response activation in response to DNA damage (Unterholzner and Dunphy 2019). Besides, STING also has been confirmed to maintain cell homeostasis by regulating the cell cycle, whereas loss of STING will cause the cells to enter the S phase and mitosis prematurely, leading to smaller cell size and increased chromosome instability (Ranoa et al. 2019). Thus, it is likely that the STING gene affects mtDNAcn by regulating the cell cycle. Therefore, genetic variations in the cGAS-STING pathway may influence mtDNAcn. In this study, we focused on eight single-nucleotide polymorphisms in the cGAS-STING pathway to explore the effects of PAHs exposure and gene variants on mtDNAcn.
Exenatide promotes the autophagic function in the diabetic hippocampus: a review
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Eman Mohammed Elsaeed, Ahmed Gamal Abdelghafour Hamad, Omnia S. Erfan, Mona A. El-Shahat, Fathy Abd Elghany Ebrahim
Another marker of autophagy is p62, which is located on chromosome 5 and expressed in all tissues. It is an adaptor protein with an LC3-interacting region; thus, it undergoes degradation with LC3 present in the inner membrane of the autophagosome. It has a role in nucleation induction of the autophagosome membrane, followed by recruitment of ubiquitylated proteins and degradation through autophagy [17, 25, 26]. Consequently, autophagy activation is accompanied by a decrease in the p62 level [19]. To sum up, autophagy activation can be detected by analysis of LC3 and p62 in tandem, where it is anticipated to have an increased ratio of LC3-II to LC3-I and a reduction in p62 protein level [27].
Chitosan oligosaccharide promotes osteoclast formation by stimulating the activation of MAPK and AKT signaling pathways
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Bing-Li Bai, Zhong-Jie Xie, She-Ji Weng, Zong-Yi Wu, Hang Li, Zhou-Shan Tao, Viraj Boodhun, De-Yi Yan, Zi-Jian Shen, Jia-Hao Tang, Lei Yang
During the process of osteoclast formation and differentiation, RANKL in osteoclast precursor cells is docked with its receptor, RANK, and interacts with the adaptor protein, TRAF6, triggering rapidly a cascade of signaling events including MAPK, NF-κB, and Src-P13 K-Akt [20,21,25]. It is through the activation of these pathways that extracellular stimuli are transmitted from the cell surface to the nucleus [19]. The mitogen-activated protein kinase (MAPK) pathways, consist of three pathways including p38 MAPK, c-Jun N-terminal kinase (JNK) MAPK, and extracellular signal-regulated kinase (ERK) MAPK, are crucial for the regulation of differentiation, survival and activation of osteoclasts [26–28]. Previous studies reported that activated p38 translocated from the cytoplasm to the nucleus phosphorylates the microphthalmia-associated transcription factor (MITF), which is closely related to the promotion of osteoclast differentiation [29]. And inhibition of the p38 MAPK signaling pathway suppresses osteoclast differentiation and local bone resorption [30]. Similarly, activated JNK translocated from the cytoplasm to the nucleus induces the activation of AP-1 (mainly consisting of Jun and Fos proteins) and activates the coding of genes such as MMPs and alkaline phosphatase to stimulate osteoclast precursor differentiation, survival, fusion and activation of mature osteoclast [26,31,32]. And activated ERK translocated from the cytoplasm to the nucleus regulates c-fos gene transcription that is important for osteoclast differentiation via the binds of the activated transcription factor Elk and the cis-acting element, serum response element (SRE) in c-fos promoter [33]. Here, we demonstrated that MAPK signaling pathway is activated after COS treatment, resulting in the enhanced osteoclast differentiation.