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Homeostasis of Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The SNARE complex is formed by members of the synaptosomal-associated protein 25 (SNAP-25), vesicle-associated membrane protein (VAMP) and members of the syntaxins family. Interactions between these proteins create a four-helix bundle, formed by two helices of SNAP-25, one vesicular-transmembrane VAMP and one presynaptic plasma membrane syntaxin that brings together the vesicular and plasmatic membranes. Other proteins that interact with the SNARE complex include Munc-18, complexin, synaptophysin, and synaptotagmin [77]. In addition, synaptotagmin serves as a calcium sensor and regulates the SNARE zipping. The SM proteins are evolutionary conserved cytosolic proteins that serve as essential partners for SNARE proteins in fusion. Among these is Munc 18, which primarily interacts with syntaxin-1 and whose function is tightly regulated by calcium.
Golgi apparatus regulation of differentiation
Published in C. Yan Cheng, Spermatogenesis, 2018
Louis Hermo, Regiana L. Oliveira, Charles E. Smith, Catherine E. Au, John J. M. Bergeron
The enhanced expression of a number of proteins during meiosis (Figure 1.23a) was remarkable. From pachytene spermatocytes (stage I) until the end of meiosis, there was prominent immunoreactivity noted for calnexin, a chaperone participating in the folding and quality control of client proteins (Figure 1.23b) and binding immunoglobulin protein (BIP), an ER HSP70 family member also known as glucose-regulated protein 78 or HSPA5. Vesicle-associated membrane protein 3 (VAMP3), the GTP-binding protein RAB14 (Figure 1.23c), clathrin heavy chain (CHC), elongation factor EF1α, the ubiquitin-directed AAA-ATPase P97, proteasome α 1-7, the GTPase activating protein, sec23, a coat component of COPII vesicles, and ubiquitin were also highly expressed during this time point in meiosis (Figure 1.23a). All of these proteins mark in large part to the period of MG160 expression to these cells (Figure 1.23a). Another coincident pattern is that seen for UBXD8 as a cytoplasmic localized protein (Figure 1.23d) and MG160 (Figure 1.23a) both expressed in spermatocytes and both reveal overlapping expression during meiosis. The meiotic period represents a dramatic size increase of the Golgi apparatus during spermatocyte maturation due to an accumulation of trans Golgi elements83 and corresponding to a significant increase in size of the Golgi apparatus (0.5–1.0 to 2–3 μm in diameter) to produce four haploid daughter cells as a consequence of meiosis.209 These proteins may be related to this event.
A Laboratory Incident Linked to Exposure to Botulinum Toxin
Published in Meera Chand, John Holton, Case Studies in Infection Control, 2018
The molecular weight of the toxin is 150 kDa, and it is composed of an A and B subunit. The A subunit (50 kDa) is a zinc-endopeptidase. It hydrolyses SNARE proteins, such as vesical-associated membrane proteins (VAMP), present on presynaptic vesicles carrying acetylcholine (Ach) and thereby prevents the release of the vesicle contents and thus signal transmission at the neuromuscular junction. The B subunit (100 kDa) targets the toxin to presynaptic receptors and facilitates entry of the active subunit into the nerve.
Circulating mir-21 and mir-146a are associated with increased cytokines and CD36 in Algerian obese male participants
Published in Archives of Physiology and Biochemistry, 2022
Hassiba Benbaibeche, Aziz Hichami, Brahim Oudjit, El Mahdi Haffaf, Ghouti Kacimi, Elhadj Ahmed Koceïr, Naim Akhtar Khan
Decreased expression of miRNAs can lead to different consequences in obesity. For instance, reduced miR-21 in obese participants can promote high insulin secretion. Indeed, secretory granule protein essential for insulin exocytosis, VAMP2 (vesicle associated membrane protein 2), has been shown to be indirectly inhibited by miR-21 (Osmai et al. 2016), thus resulting in decreased insulin secretion. Interestingly, miR-21 could reverse insulin resistance in 3T3-L1 cells and significantly increase insulin-induced glucose uptake by translocating GLUT4 to the cell membrane (Ling et al. 2012). Reduced expression of miR-146a is considered a sign of a pro-inflammatory state. Hence, miR-146a-null mice systematically overproduce TNF-α, and IL-6 in response to an injection with a sub-lethal dose of lipopolysaccharides (Boldin et al. 2011). In human fibroblasts, the overexpression of miR-146a suppressed IL-6 secretion and, thereby, limited inflammation (Bhaumik et al. 2009). Moreover, miR-146a and miR-21 can impair NFkB activity and suppress the expression of NFkB target genes such as IL-6, and TNF-α (Marquez et al. 2010, Pauley et al. 2008).
CD36 as a target for metabolic modulation therapy in cardiac disease
Published in Expert Opinion on Therapeutic Targets, 2021
Jan F.C. Glatz, Fang Wang, Miranda Nabben, Joost J.F.P. Luiken
The subcellular vesicular recycling of membrane proteins and receptors is a highly specific process in which some 50–60 distinct proteins are involved, including coat proteins, adaptor proteins, bilayer destabilizing kinases, vesicle-associated membrane proteins (VAMPs), and motor proteins [53,54]. Particular sets of proteins participate in the intracellular trafficking of specific membrane proteins, such as CD36, thereby providing tissue and cell-type specificity. Although the CD36-dedicated vesicular trafficking machinery has not yet been fully elucidated, a recent study has identified a VAMP isoform (VAMP4) to be specifically participating in myocardial CD36 traffic [55]. Silencing of this VAMP isoform in cardiomyocytes simultaneously decreased stimulus-induced CD36 translocation to the sarcolemma and the rate of cellular fatty acid uptake without affecting GLUT4-mediated glucose uptake [55]. This finding indicates the feasibility of using VAMP4 as target to manipulate specifically CD36-mediated cellular fatty acid uptake without affecting glucose uptake. The latter is crucial to avoid an energy deficit of the heart.
Extracellular vesicles and their role in glioblastoma
Published in Critical Reviews in Clinical Laboratory Sciences, 2020
Clarissa A. Whitehead, Andrew H. Kaye, Katharine J. Drummond, Samuel S. Widodo, Theo Mantamadiotis, Laura J. Vella, Stanley S. Stylli
Once trafficked to the cell periphery, soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) can assist in the fusion of the MVB and plasma membranes. Vesicular SNARES (v-SNAREs) interact with target SNAREs (t-SNAREs) on the cell membrane, and their involvement in Ca2+ regulated exocytosis [55] and exosome secretion has been demonstrated [56,57]. SNARE-related proteins (vesicle associated membrane protein 2 (VAMP2), synaptosome associated protein 25 (SNAP25) and syntaxin-1 (Stx1)) are required for neurotransmitter release from cells of the nervous system [58]. Likewise, Stx1 may be involved in exosome secretion [59], and the knockdown of Stx1 was shown to inhibit cell growth and invasion in GBM, indicating the functional importance of EV release from tumor cells [60]. Although promising, targeting Stx1 may also impact neurotransmission-related processes, and as such, further investigation into the contribution of Stx1 in GBM progression is required.