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Actin distribution

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https://www.readbyqxmd.com/read/28548684/origins-of-anterior-posterior-polarity-by-localized-activation-of-disheveled
#1
Jeff Chieh-Fu Peng, Lingyu Wang, Athula H Wikramanayake
Most animal eggs have a primordial polarity, termed the animal-vegetal (AV) axis, that frequently predicts the anterior-posterior (AP) axis of the embryo and adult. Transformation of the AV polarity of the egg to the AP polarity of the embryo in many species is mediated by the localized activation of canonical Wnt (cWnt) signaling in vegetal blastomeres by maternal determinants. In the sea urchin egg, cWnt signal transduction is facilitated by localized "activation" of the Disheveled protein, a central regulator of Wnt signaling...
May 26, 2017: Molecular Reproduction and Development
https://www.readbyqxmd.com/read/28548208/quantification-of-excitation-energy-distribution-between-photosystems-based-on-a-mechanistic-model-of-photosynthetic-electron-transport
#2
Keach Murakami, Ryo Matsuda, Kazuhiro Fujiwara
Absorbed light energy is converted into excitation energy. The excitation energy is distributed to photosystems depending on the wavelength and drives photochemical reactions. A non-destructive, mechanistic, and quantitative method for estimating the fraction of the excitation energy distributed to photosystem II (f) was developed. To estimate the f values for two simultaneously provided actinic lights (ALs) with different spectral distributions, photochemical yields of the photosystems were measured under the ALs and were then fitted to an electron transport model assuming the balance between the electron transport rates through the photosystems...
May 26, 2017: Plant, Cell & Environment
https://www.readbyqxmd.com/read/28542402/evidence-for-pleural-epithelial-mesenchymal-transition-in-murine-compensatory-lung-growth
#3
Alexandra B Ysasi, Willi L Wagner, Cristian D Valenzuela, Arne Kienzle, Andrew B Servais, Robert D Bennett, Akira Tsuda, Maximilian Ackermann, Steven J Mentzer
In many mammals, including rodents and humans, removal of one lung results in the compensatory growth of the remaining lung; however, the mechanism of compensatory lung growth is unknown. Here, we investigated the changes in morphology and phenotype of pleural cells after pneumonectomy. Between days 1 and 3 after pneumonectomy, cells expressing α-smooth muscle actin (SMA), a cytoplasmic marker of myofibroblasts, were significantly increased in the pleura compared to surgical controls (p < .01). Scanning electron microscopy of the pleural surface 3 days post-pneumonectomy demonstrated regions of the pleura with morphologic features consistent with epithelial-mesenchymal transition (EMT); namely, cells with disrupted intercellular junctions and an acquired mesenchymal (rounded and fusiform) morphotype...
2017: PloS One
https://www.readbyqxmd.com/read/28541365/responses-of-human-adipose-derived-stem-cells-to-interstitial-level-of-extremely-low-shear-flows-regarding-differentiation-morphology-and-proliferation
#4
Sung-Hwan Kim, Kihoon Ahn, Joong Yull Park
Human cells encounter a range of shear stress levels in situ and this natural variability in shear stress implies that realistic investigations of cell type characteristics may depend on nontrivial shear stress models. Human adipose-derived stem cells (hASCs) differentiate near the blood capillary vessels where interstitial flows predominate. However, the effects of interstitial levels of shear on hASCs are not fully understood. In this study, we propose a microfluidic shear generation system, in which a gradient distribution of the interstitial level of shear flow is created to investigate the effects of interstitial-level shear flow on hASCs...
May 25, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28536263/axodendritic-sorting-and-pathological-missorting-of-tau-is-isoform-specific-and-determined-by-axon-initial-segment-architecture
#5
Hans Zempel, Frank Dennissen, Yatender Kumar, Julia Luedtke, Jacek Biernat, Eva-Maria Mandelkow, Eckhard Mandelkow
Subcellular mislocalization of the microtubule-associated protein Tau is a hallmark of Alzheimer disease (AD) and other tauopathies. Six Tau isoforms, differentiated by the presence or absence of a second repeat or of N-terminal inserts, exist in the human CNS but their physiological and pathological differences have long remained remain elusive. Here, we investigated the properties and distributions of human and rodent Tau isoforms in primary forebrain rodent neurons. We found that the Tau-Diffusion-Barrier (TDB), located within the Axon-Initial-Segment (AIS), controls retrograde (axon-to-soma) and anterograde (soma-to-axon) traffic of Tau...
May 23, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28533957/pld2-regulates-microtubule-stability-and-spindle-migration-in-mouse-oocytes-during-meiotic-division
#6
Xiaoyu Liu, Xiaoyun Liu, Dandan Chen, Xiuying Jiang, Wei Ma
Phospholipase D2 (PLD2) is involved in cytoskeletal reorganization, cell migration, cell cycle progression, transcriptional control and vesicle trafficking. There is no evidence about PLD2 function in oocytes during meiosis. Herein, we analyzed PLD2 expression and its relationship with spindle formation and positioning in mouse oocyte meiosis. High protein level of PLD2 was revealed in oocytes by Western blot, which remained consistently stable from prophase I with intact germinal vesicle (GV) up to metaphase II (MII) stage...
2017: PeerJ
https://www.readbyqxmd.com/read/28531800/restoration-of-arpin-suppresses-aggressive-phenotype-of-breast-cancer-cells
#7
Yi Li, Jiliang Qiu, Ting Pang, Zhixing Guo, Yonghui Su, Qingan Zeng, Xuexia Zhang
Arpin, a negative regulator of the actin-related protein-2/3 (Arp2/3) complex, is downregulated and predicts poor prognosis in breast cancer patients. However, its biological relevance in breast cancer is still unclear. This study was conducted to investigate the roles of Arpin in breast cancer growth and invasion. We overexpressed Arpin expression in MCF-7 and MDA-MB-231 breast cancer cells and examined the effects of restoration of Arpin on cell proliferation, colony formation, cell cycle distribution, invasion in vitro and tumorigenesis in vivo...
May 19, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28530094/troponin-c-mutations-partially-stabilize-the-active-state-of-regulated-actin-and-fully-stabilize-the-active-state-when-paired-with-%C3%AE-14-tnt
#8
Tamatha Baxley, Dylan Johnson, Jose Renato Pinto, Joseph Michael Chalovich
Striated muscle contraction is regulated by the actin associated proteins tropomyosin and troponin. Activation of myosin ATPase activity is lowest in the absence of both Ca2+ and activating crossbridges (i.e. S1-ADP or rigor S1). Binding of activating species of myosin to actin at saturating Ca2+ stabilizes the most active state (M state) of actin-tropomyosin-troponin (regulated actin). Ca2+ binding alone produces partial stabilization of the active state. The extent of stabilization at saturating Ca2+ depends on the isoform of the troponin subunits, the phosphorylation state of troponin and, in the case of cardiac muscle, the presence of hypertrophic cardiomyopathy producing mutants of troponin T and troponin I...
May 22, 2017: Biochemistry
https://www.readbyqxmd.com/read/28522964/the-differential-organization-of-f-actin-alters-the-distribution-of-organelles-in-cultured-when-compared-to-native-chromaffin-cells
#9
Yolanda Gimenez-Molina, José Villanueva, Carmen Nanclares, Inmaculada Lopez-Font, Salvador Viniegra, Maria Del Mar Francés, Luis Gandia, Amparo Gil, Luis M Gutiérrez
Cultured bovine chromaffin cells have been used extensively as a neuroendocrine model to study regulated secretion. In order to extend such experimental findings to the physiological situation, it is necessary to study mayor cellular structures affecting secretion in cultured cells with their counterparts present in the adrenomedullary tissue. F-actin concentrates in a peripheral ring in cultured cells, as witnessed by phalloidin-rodhamine labeling, while extends throughout the cytoplasm in native cells. This result is also confirmed when studying the localization of α-fodrin, a F-actin-associated protein...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28515328/mechanotransmission-in-endothelial-cells-subjected-to-oscillatory-and-multi-directional-shear-flow
#10
Mahsa Dabagh, Payman Jalali, Peter J Butler, Amanda Randles, John M Tarbell
Local haemodynamics are linked to the non-uniform distribution of atherosclerosic lesions in arteries. Low and oscillatory (reversing in the axial flow direction) wall shear stress (WSS) induce inflammatory responses in endothelial cells (ECs) mediating disease localization. The objective of this study is to investigate computationally how the flow direction (reflected in WSS variation on the EC surface over time) influences the forces experienced by structural components of ECs that are believed to play important roles in mechanotransduction...
May 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28515142/flow-induced-endothelial-cell-alignment-requires-the-rhogef-trio-as-a-scaffold-protein-to-polarize-active-rac1-distribution
#11
Jeffrey Kroon, Niels Heemskerk, Martin J T Kalsbeek, Vivian de Waard, Jos van Rijssel, Jaap D van Buul
Endothelial cells line the lumen of the vessel wall and are exposed to flow. In linear parts of the vessel, the endothelial cells experience laminar flow, resulting in endothelial cell alignment in the direction of flow, thereby protecting the vessel wall from inflammation and permeability. In order for endothelial cells to align, they undergo rapid remodeling of the actin cytoskeleton by local activation of the small GTPase Rac1. However, if sustained and local activation of Rac1 is required for long-term flow-induced cell alignment is not clear...
May 17, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28512223/kinematics-of-the-lever-arm-swing-in-myosin-vi
#12
Mauro L Mugnai, D Thirumalai
Myosin VI (MVI) is the only known member of the myosin superfamily that, upon dimerization, walks processively toward the pointed end of the actin filament. The leading head of the dimer directs the trailing head forward with a power stroke, a conformational change of the motor domain exaggerated by the lever arm. Using a unique coarse-grained model for the power stroke of a single MVI, we provide the molecular basis for its motility. We show that the power stroke occurs in two major steps. First, the motor domain attains the poststroke conformation without directing the lever arm forward; and second, the lever arm reaches the poststroke orientation by undergoing a rotational diffusion...
May 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28508453/tetr-dependent-gene-regulation-in-intracellular-listeria-monocytogenes-demonstrates-the-spatiotemporal-surface-distribution-of-acta
#13
Sibylle Schmitter, Lars Fieseler, Jochen Klumpp, Ralph Bertram, Martin J Loessner
To enable specific and tightly controlled gene expression both in-vitro and during the intracellular lifecycle of the pathogen Listeria monocytogenes, a TetR-dependent genetic induction system was developed. Highest concentration of cytoplasmic TetR and best repression of tetO-controlled genes was obtained by tetR expression from the synthetic promoter Pt17 . Anhydrotetracycline (ATc) as inducer permitted concentration-dependent, fine-tuned expression of genes under control of the tetO operator and a suitable promoter...
May 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28507101/human-myosin-viia-is-a-very-slow-processive-motor-protein-on-various-cellular-actin-structures
#14
Osamu Sato, Satoshi Komatsu, Tsuyoshi Sakai, Yoshikazu Tsukasaki, Ryosuke Tanaka, Takeomi Mizutani, Tomonobu M Watanabe, Reiko Ikebe, Mitsuo Ikebe
Human myosin VIIa (MYO7A) is an actin-linked motor protein associated with human Usher syndrome (USH) type 1B, which causes human congenital hearing and visual loss. While it has been thought that the role of human myosin VIIa is critical for USH1 protein tethering with actin and transportation along actin bundles in inner-ear hair cells, myosin VIIa's motor function remains unclear. Here, we studied the motor function of the tail-truncated human myosin VIIa dimer (HM7AΔTail/LZ) at the single-molecule level...
May 15, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28505295/phylogenetic-distribution-of-tir-cytoskeleton-coupling-protein-tccp-and-tccp2-genes-in-atypical-enteropathogenic-escherichia-coli
#15
Fernando H Martins, Roberto Nepomuceno, Roxane M F Piazza, Waldir P Elias
Enteropathogenic Escherichia coli (EPEC) strains employ the type III secretion system (T3SS) effector Tir to induce actin cytoskeletal rearrangements. While some EPEC require tyrosine phosphorylation (Y-P) of Tir to trigger actin assembling, certain strains whose Tir is not tyrosine phosphorylated utilize the T3SS effector Tir-cytoskeleton coupling protein (TccP/TccP2) for efficient actin polymerization. The presence of tccP/tccP2 in typical EPEC belonging to distinct evolutionary lineages is well established but, in contrast, little is known about the distribution of these genes in atypical EPEC (aEPEC) showing distinct phylogenetic background...
May 15, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28505258/modelling-and-mathematical-analysis-of-the-m-_-2-receptor-dependent-joint-signalling-and-secondary-messenger-network-in-cho-cells
#16
Benjamin Engelhardt, Janine Holze, Christina Elliott, George S Baillie, Maik Kschischo, Holger Fröhlich
The muscarinic M$_{2}$ receptor is a prominent member of the GPCR family and strongly involved in heart diseases. Recently published experimental work explored the cellular response to iperoxo-induced M$_{2}$ receptor stimulation in Chinese hamster ovary (CHO) cells. To better understand these responses, we modelled and analysed the muscarinic M$_{2}$ receptor-dependent signalling pathway combined with relevant secondary messenger molecules using mass action. In our literature-based joint signalling and secondary messenger model, all binding and phosphorylation events are explicitly taken into account in order to enable subsequent stoichiometric matrix analysis...
May 15, 2017: Mathematical Medicine and Biology: a Journal of the IMA
https://www.readbyqxmd.com/read/28505006/myopericytomatosis-clinicopathologic-analysis-of-11-cases-with-molecular-identification-of-recurrent-pdgfrb-alterations-in-myopericytomatosis-and-myopericytoma
#17
Yin P Hung, Christopher D M Fletcher
Myopericytoma is a benign tumor of concentrically distributed perivascular myoid cells. Its molecular basis and relationship with myofibroma/myofibromatosis and other pericytic tumors are not fully understood. In our consultation/surgical files of over 1000 myopericytic lesions, we identified 11 cases with diffuse dermal/subcutaneous involvement by microscopic myopericytomatous nodules, a phenomenon we have termed myopericytomatosis. Myopericytomatosis affected mostly adults (female:male=8:3; median age, 37 y; range, 9 to 63 y) in the lower extremities (foot/ankle, 5; calf, 3; knee, 1; thigh, 1; neck, 1) over months to 25 years, ranging from 1...
May 12, 2017: American Journal of Surgical Pathology
https://www.readbyqxmd.com/read/28504189/ezrin-ser66-phosphorylation-regulates-invasion-and-metastasis-of-esophageal-squamous-cell-carcinoma-cells-by-mediating-filopodia-formation
#18
Li-Yan Li, Ying-Hua Xie, Yang-Min Xie, Lian-Di Liao, Xiu-E Xu, Qiang Zhang, Fa-Min Zeng, Li-Hua Tao, Wen-Ming Xie, Jian-Jun Xie, Li-Yan Xu, En-Min Li
BACKGROUND: Ezrin, links the plasma membrane to the actin cytoskeleton, and plays an important role in the development and progression of human esophageal squamous cell carcinoma (ESCC). However, the roles of ezrin S66 phosphorylation in tumorigenesis of ESCC remain unclear. METHODS: Distribution of ezrin in membrane and cytosol fractions was examined by analysis of detergent-soluble/-insoluble fractions and cytosol/membrane fractionation. Both immunofluorescence and live imaging were used to explore the role of ezrin S66 phosphorylation in the behavior of ezrin and actin in cell filopodia...
May 11, 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/28502709/organizational-innovation-of-apical-actin-filaments-drives-rapid-pollen-tube-growth-and-turning
#19
Xiaolu Qu, Ruihui Zhang, Meng Zhang, Min Diao, Yongbiao Xue, Shanjin Huang
Polarized tip growth is a fundamental cellular process in many eukaryotes. In this study, we examined the dynamic restructuring of the actin cytoskeleton and its relationship to vesicle transport during pollen tip growth in Arabidopsis. We found that actin filaments originating from the apical membrane form a specialized structure consisting of longitudinally aligned actin bundles at the cortex and inner cytoplasmic filaments with a distinct distribution. Using actin-based pharmacological treatments and genetic mutants in combination with FRAP (fluorescence recovery after photobleaching) technology to visualize the transport of vesicles within the growth domain of pollen tubes, we demonstrate that cortical actin filaments facilitate tip-ward vesicle transport...
May 10, 2017: Molecular Plant
https://www.readbyqxmd.com/read/28500298/zbp1-phosphorylation-at-serine-181-regulates-its-dendritic-transport-and-the-development-of-dendritic-trees-of-hippocampal-neurons
#20
Anna S Urbanska, Aleksandra Janusz-Kaminska, Katarzyna Switon, Alicia L Hawthorne, Malgorzata Perycz, Malgorzata Urbanska, Gary J Bassell, Jacek Jaworski
Local protein synthesis occurs in axons and dendrites of neurons, enabling fast and spatially restricted responses to a dynamically changing extracellular environment. Prior to local translation, mRNA that is to be translated is packed into ribonucleoprotein particles (RNPs) where RNA binding proteins ensure mRNA silencing and provide a link to molecular motors. ZBP1 is a component of RNP transport particles and is known for its role in the local translation of β-actin mRNA. Its binding to mRNA is regulated by tyrosine 396 phosphorylation, and this particular modification was shown to be vital for axonal growth and dendritic branching...
May 12, 2017: Scientific Reports
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