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Hereditary Multiple Osteochondromas
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Germline loss-of-function mutations (e.g., nonsense, frameshift, splice site, missense variants) in the EXT1 and EXT2 genes leading to premature terminations of the EXT proteins cause HS deficiency and subsequent cytoskeletal abnormalities (e.g., actin accumulation, excessive bundling by alpha-actinin, and abnormal presence of muscle-specific alpha-actin) [1].
Energy Demand of Muscle Machines
Published in Peter W. Hochachka, Muscles as Molecular and Metabolic Machines, 2019
Electron micrographs of cross-sections of myofibrils show that there are two kinds of interacting protein filaments. The thick filaments have diameters of about 150 Å, whereas the thin filaments have diameters of about 70 Å. The thick filaments primarily consist of myosin. Thin filaments contain actin, tropomyosin, and troponin. Alpha-actinin is present in the Z line, whereas an M-protein is located in the M line.
Histology and Pathology of the Human Neuromuscular Junction with a Description of the Clinical Features of the Myasthenic Syndromes
Published in Marc H. De Baets, Hans J.G.H. Oosterhuis, Myasthenia Gravis, 2019
F.G.I. Jennekens, H. Veldman, John Wokke
A complex filamentous meshwork is present in the folds and fulfills at least two functions: to keep the AChRs in place, and to maintain the shape of the folds. The dense lining of the stalks is not only due to the AChRs but also to a submembranous cytoskeletal protein network. A 43 kDa protein at the cytoplasmic side of the postsynaptic membrane has been demonstrated to cluster AChRs and is involved, probably together with actin and a form of spectrin, in anchoring the AChRs.38-40 Dystrophin (430 kd) is also associated with the cytoplasmic side of the postsynaptic membrane and though quantitative studies have not yet been performed, results of immunofluorescence studies indicate a higher density (molecules per μm2) here than in the extrajunctional sarcolemma.41 Dystrophin is tightly linked to a complex of sarcolemma proteins; the dystrophin associated glycoprotein complex has been demonstrated to bind laminin and links the subsarcolemmal cytoskeleton to the extracellular matrix.41a A specific role has been suggested for dystrophin in the elaboration and maintenance of the junctional folds.42 A number of other cytoskeletal proteins (vinculin, alpha-actinin, filamin, and desmin) have been identified in the postsynaptic region but their exact position and role is not yet clear.43,44 The junctional folds contain pinocytotic and other vesicular structures, secondary lysosomes, ribosomes, and glycogen granules, but no mitochondria.
Proteogenomic examination of esophageal squamous cell carcinoma (ESCC): new lines of inquiry
Published in Expert Review of Proteomics, 2020
Shobha Dagamajalu, Manavalan Vijayakumar, Rohan Shetty, D. A. B. Rex, Chinmaya Narayana Kotimoole, T. S. Keshava Prasad
Feng et al. have reported that proteins such as Annexin A2 and Cdc42 were upregulated in several cancers and validated in ESCC [46]. The reduced expression of Annexin II is correlated to the progression of carcinogenesis, which may be a candidate biomarker for early diagnosis of ESCC [47]. Singhal et al. have observed the alteration of cancer-associated lipids and low molecular weight proteins in upper GI tract cancers and proposed that these molecules can be used to detect upper GI-tract cancers [48]. Antibody-based proteomic investigation by Uemura et al. has identified BubR1, Mad2, NF-kappaB-activating kinase (NAK), caspase 10, and activator protein-1 (AP-1) in ESCC [14]. The same group also reported Transglutaminase 3 as a prognostic marker for ESCC [49]. The progressive increase of candidate biomarkers such as alpha-actinin 4 (ACTN4) and 67 kDa laminin receptor (67LR) was identified in the ESCC stage I to III tissues [50]. The downregulated expression of a specific novel protein, beta tropomyosin (TMbeta) was detected in Iranian ESCC patients [51].
Immunopathogenesis and biomarkers of recurrent atrial fibrillation following ablation therapy in patients with preexisting atrial fibrillation
Published in Expert Review of Cardiovascular Therapy, 2019
John H. Rosenberg, John H. Werner, Gilman D. Plitt, Victoria V. Noble, Jordan T. Spring, Brooke A. Stephens, Aleem Siddique, Helenmari L. Merritt-Genore, Michael J. Moulton, Devendra K. Agrawal
HSP27 has been shown to be the most promising HSP marker for post-ablation recurrence of AF. On a molecular level, HSP27 protects the cell against damage and electrophysiological changes through a number of mechanisms. HSP27 helps stabilize the actin cytoskeleton by directly binding to alpha-actinin and F-actin, maintaining the structural and contractile integrity of cardiomyocytes [20]. HSP27 also directly stabilizes L-type calcium channels, promoting normal electrical conduction through the cell. Although the exact mechanism is not fully understood, HSP27 is able to protect contractile proteins and ion channels against degradation from cysteine proteases, known to be activated during AF [20]. In addition, HSP27 is able to impede the proinflammatory TNF-α pathway, as well as increase levels of anti-inflammatory cytokine IL-10, protecting against inflammation induced AF remodeling [17]. Brundel et al [26] . showed that overexpression of HSP27 prior to subjecting human cardiomyocytes to a 10-fold rate increase successfully protected against tachypacing-induced myolysis. This supports that the additive molecular effects of HSP27 convey a significant survival benefit, minimizing cardiac remodeling secondary to myolysis. They also showed patients with paroxysmal AF had significantly higher levels of atrial intracellular HSP27 than in persistent AF patients [26]. All of these findings support the potential ability of HSP27 to protect against the progression of AF from paroxysmal to persistent type.
Quantitative proteomic analysis of trypsin-treated extracellular vesicles to identify the real-vesicular proteins
Published in Journal of Extracellular Vesicles, 2020
Dongsic Choi, Gyeongyun Go, Dae-Kyum Kim, Jaewook Lee, Seon-Min Park, Dolores Di Vizio, Yong Song Gho
Most of the candidate real-vesicular proteins were closely related in EV structure and biogenesis. For example, cytoskeletal proteins such as ACTG1 (Actin, cytoplasmic 2), ACTN4 (Alpha-actinin-4), PFN1 (Profilin-1), CFL1 (Cofilin-1), MSN (Moesin), KRT1 (Keratin, type II cytoskeletal 1), KRT9 (Keratin, type I cytoskeletal 9), KRT10 (Keratin, type I cytoskeletal 10), FLNA (Filamin-A), WDR1 (WD repeat-containing protein 1), COTL1 (Coactosin-like protein) and DSTN (Destrin) are involved in the actin cytoskeleton regulation. For example, cofilin-1 stimulates the generation of EVs via the regulation of actin cytoskeleton depolymerization activated by RhoA signalling [28]. Interestingly, our protein–protein interaction network analyses showed the intravesicular proteins derived from the cytosol are possibly inter-connected with other cytosolic proteins. Among them, 14-3-3 proteins (YWHAB, YWHAE, YWHAH, YWHAQ, YWHAZ and SFN), heat shock proteins (HSPA4, HSPA5, HSPA8 and HSP90AA1), GAPDH and CALM1 (Calmodulin-1) have lots of the interaction partners in EV proteome. It is known that these proteins play a role in intracellular protein trafficking responding to intracellular signalling [29–32], implying their involvement in the protein sorting into EVs. Besides cytoskeletal and cytosolic proteins, there were relatively small number of intravesicular proteins derived from the nucleus, endoplasmic reticulum and Golgi apparatus. However, ARF3 (ADP-ribosylation factor 3), ARF6 (ADP-ribosylation factor 6) and RAB proteins of Golgi apparatus are well known to contribute in intravesicular trafficking and the biogenesis processes of EVs [33,34].