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Serratia
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Naheed S. Kanji, Umesh Narsinghani, Ritu A. Kumar
Infections by Serratia and related microbes secrete a pore-forming toxin hemolysin/cytolysin, which is responsible for its virulence. This hemolysin ShIA is cytotoxic that lyses erythrocytes, leukocytes, and macrophages precipitating a systemic inflammatory response. The S. marcescens hemolysin represents the prototype of a growing family of pore-forming toxins. This cytotoxin is believed to aid in tissue penetration and may be linked to a widespread host invasive pathogenic pathway involving bacterial swarming, quorum sensing, and biofilm production. The hemolysin is determined by two genes, ShlA and shlB, arranged in tandem. ShlA encodes the hemolysin, and ShlB encodes the outer membrane protein that secretes ShlA. Both have proteins with signal sequences for export across the cytoplasmic membrane by the Sec system. ShlB not only secretes ShlA but also activates ShlA. The hemolysin was the first characterized example of a large group of proteins secreted by the two partner secretion system (TPSS) or type V-secretion system.62,63
The rab Gene Family
Published in Juan Carlos Lacal, Frank McCormick, The ras Superfamily of GTPases, 2017
Armand Tavitian, Ahmed Zahraoui
There is strong genetic evidence that SEC4 and YPT1: two small GTP-binding proteins highly related to mammalian rab proteins, are required for intracellular transport in S. cerevisiae. Thermosensitive mutations of the SEC4 gene impair the fusion of post-Golgi vesicles with the PM, suggesting that its product is required for the targeting and/or the fusion of vesicles with PM. In agreement with this, the SEC4p (p for protein) is found associated with the cytoplasmic face of vesicles in transit to the cell surface and the inner face of the PM.46 Further genetic studies have identified at least 10 genes to be essential for post-Golgi secretory events. One of these, SEC 15 localized on secretory vesicles, may be a SEC4 target. This suggests that SEC4 controls the formation of a complex between a docking protein, SEC15, and a PM target.47
Pathophysiology and Management of Shock
Published in Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George, The Scientific Basis of Urology, 2010
While ATP might be the currency of life and DNA the “secret of life, “i proteins are the fabric of life. Proteins that are destined for secretion (hormones, cytokines, neurotransmitters) or expression on the cell surface (receptors, adhesion molecules) are guided through aqueous pores by the Sec61 complex into the lumen of the endoplasmic reticulum (ER) as they are translated by cytosolic ribosomes. In contrast to any other cellular compartment, the ER maintains an oxidizing environment necessary for the formation of disulfide bonds and glycosylation, processes vital to the stabilization of a functional tertiary conformation following protein folding. The correct execution of these post-translational events are mediated and monitored by a repertoire of molecular chaperones that are able to detect misfolded or aggregated proteins, which are then exported to the cytosol for proteasomal degradation. When the capacity for ER processing cannot meet demand, for example, as a consequence of increased protein synthesis or degradation of the ER’s processing capacity (hypoxia, hypoglycemia, oxidative stress), the ER chaperone Grp78 (BiP) is distracted from the lumenal aspect of the ER membrane where it anchors the N-terminal transmembranous portion of three molecules that are then freed to generate the “unfolded protein response’’ (UPR) (43).
Comprehensive bioinformatics analysis reveals the hub genes and pathways associated with multiple myeloma
Published in Hematology, 2022
Shengli Zhao, Xiaoyi Mo, Zhenxing Wen, Lijuan Ren, Zhipeng Chen, Wei Lin, Qi Wang, Shaoxiong Min, Bailing Chen
SEC61A1 encodes the α-subunit of the heteropolymeric SEC61 complex, which is essential in the process of secretion and insertion of polypeptides into the ER [32]. Abnormalities in SEC61A1 have been linked to the progression of kidney disease and liver cancer in humans [33–35]. In a B cell inactivation study, a decrease in the expression of SEC61A1 and the production of IgM and IgG were simultaneously observed, suggesting that the variation in SEC61 may be related to plasma cell deficiency [36]. Further research by Schubert et al. confirmed that B cells of SEC61A1 mutation carriers have an intrinsic deficiency to develop into plasma cells. At the same time, less immunoglobulin secretion was observed in EBV-transformed B cell lines carrying SEC61A1 mutations [37]. In our study, 7 protein-related pathways were enriched in the pathway interrelation analysis of SEC61A1, which indicated that the important regulatory role of SEC61A1 participates in protein metabolism (Figure 6B). Therefore, further studies are necessary and urgent to clarify the roles of SEC61A1 in the pathogenic mechanism of MM.
Targeting endoplasmic reticulum stress—the responder to lipotoxicity and modulator of non-alcoholic fatty liver diseases
Published in Expert Opinion on Therapeutic Targets, 2022
Yu Luo, Qiangqiang Jiao, Yuping Chen
Lipid bilayer stress in hepatocytes also triggers ER stress and activates IRE1α and PERK [20,21]. It was found that obese mice increased their hepatic uptake of free fatty acids (FFAs) and syntheses of triglycerides (TGs), phospholipids, and sphingolipids, elevating the PC/PE ratio in their hepatic ER and activating IRE1α [16,20]. The animals fed with SFAs rather than unsaturated FAs developed severe ER stress and liver injury [13], while raising lipid saturation in ER membranes directly stimulated IRE1α [22]. Notably, lipid bilayer stress was revealed to harm the stability of the β subunit of Sec61 ER translocation complex (Sbh1) in ER membrane and led to chronic ER stress [23]. The recognition of specific sphingolipids (dihydrosphingosine and dihydroceramide) by the transmembrane structural domain of ATF6 could result in its activation [24]. In addition, as a basic component responsible for membrane fluidity, rigidity, and permeability, the abnormal cholesterol homeostasis also elicits ER stress via lipid bilayer stress. The free cholesterol (FC) overload in NAFLD animals and patients directly changes the FC/phospholipid ratio of ER membrane, stimulating IRE1α activation in hepatocytes [25]. In steatotic mice induced by acetylated low-density lipoprotein (LDL) diet, the FC rise due to the disrupted cholesteryl ester production inspired ER stress in hepatocytes, activated IRE1α, the PERK/ATF4/CHOP pathways and autophagy, and marked the NAFLD progression [26].
Cancer Chemopreventive Properties of Sulfated Enterolobium cyclocarpum Extract
Published in Nutrition and Cancer, 2021
Amira M. Gamal-Eldeen, Hassan Amer, Amani A Alrehaili, Ahmed Saleh, Abd El-Rahman Al Ghamdi, Nahed M Hawsawi, Asma Salman, Bassem M. Raafat
Initiation is a key event in carcinogenesis, where it operationally renders a cell prone to clonal growth under the influence of promoters in a persistent process that is passed on to subsequent cell generations (33). Halting the initiation by targeting the inhibition of the carcinogen metabolic activators (eg., CYP1A), the induction of the carcinogen detoxification enzymes (eg., GSTs), and the induction of antioxidant activity are effective strategies. From our results, it was obvious that SEC is a potent tumor anti-initiating agent as it inhibited In Vitro CYP1A activity and inhibited In Vivo DEN-induced CYP1A activity. Cell protection from external damage largely depends on the availability and activity of cellular antioxidants, which maintain homeostatic control of ROS (33). An altered balance of ROS directly affects cellular proliferation, apoptosis, and senescence (31). Unfortunately, SEC was an inactive scavenger against hydroxyl and peroxyl radicals in this study.