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Cell Cycle Dependent Association of EBP50 with Protein Phosphatase 2A in Endothelial Cells
Anita Boratkó, Pál Gergely, Csilla Csortos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035595
Abstract: Ezrin-radixin-moesin (ERM)-binding phosphoprotein 50 (EBP50) is a phosphorylatable PDZ domain-containing adaptor protein that is abundantly expressed in epithelium but was not yet studied in the endothelium. We report unusual nuclear localization of EBP50 in bovine pulmonary artery endothelial cells (BPAEC). Immunofluorescent staining and cellular fractionation demonstrated that EBP50 is present in the nuclear and perinuclear region in interphase cells. In the prophase of mitosis EBP50 redistributes to the cytoplasmic region in a phosphorylation dependent manner and during mitosis EBP50 co-localizes with protein phosphatase 2A (PP2A). Furthermore, in vitro wound healing of BPAEC expressing phospho-mimic mutant of EBP50 was accelerated indicating that EBP50 is involved in the regulation of the cell division. Cell cycle dependent specific interactions were detected between EBP50 and the subunits of PP2A (A, C, and Bα) with immunoprecipitation and pull-down experiments. The interaction of EBP50 with the Bα containing form of PP2A suggests that this holoenzyme of PP2A can be responsible for the dephosphorylation of EBP50 in cytokinesis. Moreover, the results underline the significance of EBP50 in cell division via reversible phosphorylation of the protein with cyclin dependent kinase and PP2A in normal cells.
RACK1 is involved in endothelial barrier regulation via its two novel interacting partners
Anita Boratkó, Pál Gergely, Csilla Csortos
Cell Communication and Signaling , 2013, DOI: 10.1186/1478-811x-11-2
Abstract: We identified two novel interacting partners of RACK1, namely, TGF-β inhibited membrane-associated protein, TIMAP, and farnesyl transferase. TIMAP is most abundant in endothelial cells where it is involved in the regulation of the barrier function. WD1-4 repeats of RACK1 were identified as critical regions of the interaction both with TIMAP and farnesyl transferase. Phosphorylation of TIMAP by activation of the cAMP/PKA pathway reduced the amount of TIMAP-RACK1 complex and enhanced translocation of TIMAP to the cell membrane in vascular endothelial cells. However, both membrane localization of TIMAP and transendothelial resistance were attenuated after RACK1 depletion. Farnesyl transferase, the enzyme responsible for prenylation and consequent membrane localization of TIMAP, is present in the RACK1-TIMAP complex in control cells, but it does not co-immunoprecipitate with TIMAP after RACK1 depletion.Transient parallel linkage of TIMAP and farnesyl transferase to RACK1 could ensure prenylation and transport of TIMAP to the plasma membrane where it may attend in maintaining the endothelial barrier as a phosphatase regulator.The vascular endothelium functions as a semi-permeable barrier between blood and the interstitium. Endothelial cell (EC) barrier regulation is under intense investigation, since EC barrier dysfunction is a well-known feature of acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) [1]. Barrier enhancing or protecting processes are not explored in details yet, however, several studies indicate the significance of dephosphorylation of key cytoskeletal/membrane associated targets by specific protein phosphatases [2]. TIMAP (TGF-β inhibited membrane-associated protein) protein has been considered as a member of the MYPT (myosin phosphatase targeting) family of the regulatory subunits of protein phosphatase 1 (PP1) based on its structural features [3]. TIMAP and MYPT3 are the most closely related members within the
Asymmetric Swiss-cheese brane-worlds
László á. Gergely,Ibolya Képíró
Physics , 2006, DOI: 10.1088/1475-7516/2007/07/007
Abstract: We study a brane-world cosmological scenario with local inhomogeneities represented by black holes. The brane is asymmetrically embedded into the bulk. The black strings/cigars penetrating the Friedmann brane generate a Swiss-cheese type structure. This universe forever expands and decelerates, as its general relativistic analogue. The evolution of the cosmological fluid however can proceed along four branches, two allowed to have positive energy density, one of them having the symmetric embedding limit. On this branch a future pressure singularity can arise for either (a) a difference in the cosmological constants of the cosmological and black hole brane regions (b) a difference in the left and right bulk cosmological constants. While the behaviour (a) can be avoided by a redefinition of the fluid variables, (b) establishes a critical value of the asymmetry over which the pressure singularity occurs. We introduce the pressure singularity censorship which bounds the degree of asymmetry in the bulk cosmological constant. We also show as a model independent generic feature that the asymmetry source term due to the bulk cosmological constant increases in the early universe. In order to obey the nucleosynthesis constraints, the brane tension should be constrained therefore both from below and from above. With the maximal degree of asymmetry obeying the pressure singularity censorship, the higher limit is 10 times the lower limit. The degree of asymmetry allowed by present cosmological observations is however much less, pushing the upper limit to infinity.
Observations on the breeding habits, shell development, decollation, and reproductive anatomy of Pontophaedusa funiculum (Mousson 1856) (Gastropoda, Pulmonata, Clausiliidae, Phaedusinae)
Barna Páll-Gergely,László Németh
Malacologica Bohemoslovaca , 2008,
Abstract: The internal and external egg morphology, shell development, decollation process, mating behaviour and reproductive anatomy (genital structure, inner structure of the penis, fine structure of the retractor muscle and the spermatophore) of the clausiliid Pontophaedusa funiculum (Mousson 1856) are described, and illustrated by photographs of the laid eggs, their inner structure, juvenile, young adult and old individuals, as well as a schematic drawing of the mating. P. funiculum is the only known clausiliid species with hard shelled eggs and the only known example of the family Clausiliidae which mates face to face. The taxonomic position within the Phaedusinae subfamily is mentioned.
Insoluble glycogen, a metabolizable internal adsorbent, decreases the lethality of endotoxin shock in rats
S. Sipka,G. Bot,P. Gergely,L. Bertók
Mediators of Inflammation , 1997, DOI: 10.1080/09629359791442
Abstract:
Regular and Singular Fermi Liquid fixed points in quantum impurity models
Pankaj Mehta,L. Borda,Gergely Zarand,Natan Andrei,P. Coleman
Physics , 2004, DOI: 10.1103/PhysRevB.72.014430
Abstract: We show that thermodynamics is insufficient to probe the nature of the low energy dynamics of quantum impurity models and a more subtle analysis based on scattering theory is required. Traditionally, quantum impurity models are classified into one of two categories: Fermi liquids and non-Fermi liquids, depending on the analytic properties of the various thermodynamic quntities. We show, however, that even when a quantum impurity model is a Fermi liquid (an incoming electron at the Fermi level scatters elastically off the impurity), one may find singular thermodynamic behavior if characteristics of quasiparticles are not analytic near the Fermi surface. Prompted by this observation, we divide Fermi liquids into two categories: regular Fermi liquids and singular Fermi Liquids. The difference between regular Fermi liquids, singular Fermi liquids, and non-Fermi liquids fixed points is explained using properties of the many-body S-matrix for impurity quasiparticle scattering. Using the Bethe-Ansatz and numerical RG, we show that whereas the ordinary Kondo Model is a regular Fermi liquid the underscreened Kondo model is a a singular Fermi liquid. This results in a breakdown of Nozieres' Fermi liquid picture for the underscreened and explains the singular thermodynamic behavior noticed in Bethe Ansatz and large-N calculations. Furthermore, we show that conventional regular Fermi liquid behavior is re-established in an external magnetic field H, but with a density of states which diverges as 1/H. Possible connections with the field-tuned quantum criticality recently observed in heavy electron materials are also discussed.
Semi-transparent brane-worlds
Zoltán Keresztes,Ibolya Képíró,László á. Gergely
Physics , 2006, DOI: 10.1088/1475-7516/2006/05/020
Abstract: We study the evolution of a closed Friedmann brane perturbed by the Hawking radiation escaping a bulk black hole. The semi-transparent brane absorbes some of the infalling radiation, the rest being transmitted across the brane to the other bulk region. We characterize the cosmological evolution in terms of the transmission rate $\epsilon$. For small values of $\epsilon $ a critical-like behaviour could be observed, when the acceleration due to radiation pressure and the deceleration induced by the increasing self-gravity of the brane roughly compensate each other, and cosmological evolution is approximately the same as without radiation. Lighter (heavier) branes than those with the critical energy density will recollapse slower (faster). This feature is obstructed at high values of $\epsilon $, where the overall effect of the radiation is to speed-up the recollapse. We determine the maximal value of the transmission rate for which the critical-like behaviour is observed. We also study the effect of transmission on the evolution of different source terms of the Friedmann equation. We conclude that among all semi-transparent branes the slowest recollapse occurs for light branes with total absorption.
Supermassive black hole mergers as dual sources for electromagnetic flares in the jet emission and gravitational waves
M. Tápai,L. á. Gergely,Z. Keresztes,P. J. Wiita,Gopal-Krishna,P. L. Biermann
Physics , 2013, DOI: 10.1002/asna.201211988
Abstract: We present a new type of observation relating the gravitational wave emission of supermassive black hole mergers to their electromagnetic counterparts. This dual emission involves variability of a relativistic jet arising from the spin-orbit precession of the supermassive black hole binary at its base.
Constraints on supermassive black hole spins from observations of active galaxy jets
E. Kun,P. J. Wiita,L. á. Gergely,Z. Keresztes,Gopal-Krishna,P. L. Biermann
Physics , 2013, DOI: 10.1002/asna.201211986
Abstract: We discuss the origin of the low-energy cutoff, or LEC, seen in the radio spectra of many extragalactic jets and relate this to the spin of the supermassive black holes that presumably power them. Pion decay via proton-proton collisions is a possible mechanism to supply a secondary positron population with a low energy limit. We expect that pion production would occur in advection dominated accretion flows or ADAFs. In radiatively inefficient ADAFs the heat energy of the accreting gas is unable to radiate in less than the accretion time and the particle temperature could be high enough so that thermal protons can yield such pion production. Strong starbursts are another option for the injection of a truncated particle population into the jet. The role of both mechanisms is discussed with respect to the black hole spin estimate. The energy demanded to produce the pion decay process involves a minimum threshold for kinetic energy of the interacting protons. Therefore the mean proton speed in the flow can determine whether a LEC is generated. In ADAFs the random velocity of the protons can exceed the minimum speed limit of pion production around the jet launching region in the innermost part of the flow. Finally we summarize the additional work needed to put the model assumptions on a more rigorous basis.
Accurate Telescope Mount Positioning with MEMS Accelerometers
László Mészáros,Attila Jaskó,András Pál,Gergely Csépány
Physics , 2014, DOI: 10.1086/677943
Abstract: This paper describes the advantages and challenges of applying microelectromechanical accelerometer systems (MEMS accelerometers) in order to attain precise, accurate and stateless positioning of telescope mounts. This provides a completely independent method from other forms of electronic, optical, mechanical or magnetic feedback or real-time astrometry. Our goal is to reach the sub-arcminute range which is well smaller than the field-of-view of conventional imaging telescope systems. Here we present how this sub-arcminute accuracy can be achieved with very cheap MEMS sensors and we also detail how our procedures can be extended in order to attain even finer measurements. In addition, our paper discusses how can a complete system design be implemented in order to be a part of a telescope control system.
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