90 research outputs found
Improving a Natural CaMKII Inhibitor by Random and Rational Design
CaM-KIIN has evolved to inhibit stimulated and autonomous activity of the Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII) efficiently, selectively, and potently (IC50 âŒ100 nM). The CN class of peptides, derived from the inhibitory region of CaM-KIIN, provides powerful new tools to study CaMKII functions. The goal of this study was to identify the residues required for CaMKII inhibition, and to assess if artificial mutations could further improve the potency achieved during evolution.First, the minimal region with full inhibitory potency was identified (CN19) by determining the effect of truncated peptides on CaMKII activity in biochemical assays. Then, individual residues of CN19 were mutated. Most individual Ala substitutions decreased potency of CaMKII inhibition, however, P3A, K13A, and R14A increased potency. Importantly, this initial Ala scan suggested a specific interaction of the region around R11 with the CaMKII substrate binding site, which was exploited for further rational mutagenesis to generate an optimized pseudo-substrate sequence. Indeed, the potency of the optimized peptide CN19o was >250fold improved (IC50 <0.4 nM), and CN19o has characteristics of a tight-binding inhibitor. The selectivity for CaMKII versus CaMKI was similarly improved (to almost 100,000fold for CN19o). A phospho-mimetic S12D mutation decreased potency, indicating potential for regulation by cellular signaling. Consistent with importance of this residue in inhibition, most other S12 mutations also significantly decreased potency, however, mutation to V or Q did not.These results provide improved research tools for studying CaMKII function, and indicate that evolution fine-tuned CaM-KIIN not for maximal potency of CaMKII inhibition, but for lower potency that may be optimal for dynamic regulation of signal transduction
Atorvastatin prevents Plasmodium falciparum cytoadherence and endothelial damage
<p>Abstract</p> <p>Background</p> <p>The adhesion of <it>Plasmodium falciparum </it>parasitized red blood cell (PRBC) to human endothelial cells (EC) induces inflammatory processes, coagulation cascades, oxidative stress and apoptosis. These pathological processes are suspected to be responsible for the blood-brain-barrier and other organs' endothelial dysfunctions observed in fatal cases of malaria. Atorvastatin, a drug that belongs to the lowering cholesterol molecule family of statins, has been shown to ameliorate endothelial functions and is widely used in patients with cardiovascular disorders.</p> <p>Methods</p> <p>The effect of this compound on PRBC induced endothelial impairments was assessed using endothelial co-culture models.</p> <p>Results</p> <p>Atorvastatin pre-treatment of EC was found to reduce the expression of adhesion molecules and <it>P. falciparum </it>cytoadherence, to protect cells against PRBC-induced apoptosis and to enhance endothelial monolayer integrity during co-incubation with parasites.</p> <p>Conclusions</p> <p>These results might suggest a potential interest use of atorvastatin as a protective treatment to interfere with the pathophysiological cascades leading to severe malaria.</p
The restorative role of annexin A1 at the bloodâbrain barrier
Annexin A1 is a potent anti-inflammatory molecule that has been extensively studied in the peripheral immune
system, but has not as yet been exploited as a therapeutic target/agent. In the last decade, we have undertaken the
study of this molecule in the central nervous system (CNS), focusing particularly on the primary interface between the
peripheral body and CNS: the bloodâbrain barrier. In this review, we provide an overview of the role of this molecule
in the brain, with a particular emphasis on its functions in the endothelium of the bloodâbrain barrier, and the protective
actions the molecule may exert in neuroinflammatory, neurovascular and metabolic disease. We focus on the
possible new therapeutic avenues opened up by an increased understanding of the role of annexin A1 in the CNS
vasculature, and its potential for repairing bloodâbrain barrier damage in disease and aging
OGLE-2017-BLG-0406: Spitzer microlens parallax reveals Saturn-mass planet orbiting M-dwarf host in the inner galactic disk
Funding: Work by Y.H. was supported by JSPS KAKENHI Grant Number 17J02146. DPB, AB, and CR were supported by NASA through grant NASA-80NSSC18K0274. Work by N.K. is supported by JSPS KAKENHI Grant Number JP18J00897. Work by AG was supported by AST-1516842 from the US NSF and by JPL grant 1500811. AG received support from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC Grant Agreement n.[321035]. Work by C.H. was supported by the grants of the National Research Foundation of Korea (2017R1A4A1015178 and 2019R1A2C2085965). YT acknowledges the support of DFG priority program SPP 1992 âExploring the Diversity of Extrasolar Planetsâ (WA 1047/11-1).We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the Spitzer satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of q = 7.0 x 10-4 from the light-curve modeling. The ground-only and Spitzer-"only" data each provide very strong one-dimensional (1-D) constraints on the 2-D microlens parallax vector ÏE. When combined, these yield a precise measurement of ÏE, and so of the masses of the host Mhost = 0.56 ± 0.07 Mâ and planet Mplanet = 0.41 ± 0.05 MJup. The system lies at a distance DL = 5.2 ± 0.5 kpc from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is aâ„ = 3.5 ± 0.3 au, i.e., just over twice the snow line. The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the Gaia proper-motion measurement of the source suffers from a catastrophic 10Ï error.PostprintPeer reviewe
OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing
We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically bright and variable, which makes it possible to perform an asteroseismic analysis using ground-based data. We find that the source star is an oscillating red giant with average timescale of âŒ9 days. The asteroseismic analysis also provides us source properties including the source angular size (âŒ27ÎŒas) and distance (âŒ11.5 kpc), which are essential for inferring the properties of the lens. When fitting the light curve, we test the feasibility of Gaussian Processes (GPs) in handling the correlated noise caused by the variable source. We find that the parameters from the GP model are generally more loosely constrained than those from the traditional Ï2 minimization method. We note that this event is the first microlensing system for which asteroseismology and GPs have been used to account for the variable source. With both finite-source effect and microlens parallax measured, we find that the lens is likely a âŒ0.045 Mâ brown dwarf at distance âŒ9.0 kpc, or a âŒ0.073 Mâ ultracool dwarf at distance âŒ9.8 kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a 35% probability for the lens to be a bulge object and 65% to be a background disk object
Faint-source-star planetary microlensing: the discovery of the cold gas-giant planet OGLE-2014-BLG-0676Lb
We report the discovery of a planet â OGLE-2014-BLG-0676Lbâ via gravitational microlensing. Observations for the lensing event were made by the following groups: Microlensing Observations in Astrophysics; Optical Gravitational Lensing Experiment; Wise Observatory; RoboNET/Las Cumbres Observatory Global Telescope; Microlensing Network for the Detection of Small Terrestrial Exoplanets; and ÎŒ-FUN. All analyses of the light-curve data favour a lens system comprising a planetary mass orbiting a host star. The most-favoured binary lens model has a mass ratio between the two lens masses of (4.78 ± 0.13) Ă 10â3. Subject to some important assumptions, a Bayesian probability density analysis suggests the lens system comprises a 3.09+1.02 â1.12 MJ planet orbiting a 0.62+0.20 â0.22 M host star at a deprojected orbital separation of 4.40+2.16 â1.46 au. The distance to the lens system is 2.22+0.96 â0.83 kpc. Planet OGLE- 2014-BLG-0676Lb provides additional data to the growing number of cool planets discovered using gravitational microlensing against which planetary formation theories may be tested. Most of the light in the baseline of this event is expected to come from the lens and thus high-resolution imaging observations could confirm our planetary model interpretation
OGLE-2016-BLG-1003: First Resolved Caustic-crossing Binary-source Event Discovered by Second-generation Microlensing Surveys
We report the analysis of the first resolved caustic-crossing binary-source
microlensing event OGLE-2016-BLG-1003. The event is densely covered by the
round-the-clock observations of three surveys. The light curve is characterized
by two nested caustic-crossing features, which is unusual for typical
caustic-crossing perturbations. From the modeling of the light curve, we find
that the anomaly is produced by a binary source passing over a caustic formed
by a binary lens. The result proves the importance of high-cadence and
continuous observations, and the capability of second-generation microlensing
experiments to identify such complex perturbations that are previously unknown.
However, the result also raises the issues of the limitations of current
analysis techniques for understanding lens systems beyond two masses and of
determining the appropriate multiband observing strategy of survey experiments
Receptor Tyrosine Kinases in Osteosarcoma: 2019 Update
The primary conclusions of our 2014 contribution to this series were as follows:
Multiple receptor tyrosine kinases (RTKs) likely contribute to aggressive phenotypes in osteosarcoma and, therefore, inhibition of multiple RTKs is likely necessary for successful clinical outcomes.
Inhibition of multiple RTKs may also be useful to overcome resistance to inhibitors of individual RTKs as well as resistance to conventional chemotherapies.
Different combinations of RTKs are likely important in individual patients.
AXL, EPHB2, FGFR2, IGF1R, and RET were identified as promising therapeutic targets by our in vitro phosphoproteomic/siRNA screen of 42 RTKs in the highly metastatic LM7 and 143B human osteosarcoma cell lines.
This chapter is intended to provide an update on these topics as well as the large number of osteosarcoma clinical studies of inhibitors of multiple tyrosine kinases (multi-TKIs) that were recently published
An Isolated Stellar-Mass Black Hole Detected Through Astrometric Microlensing
We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (t_E ~ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462, in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of six years, reveals a clear relativistic astrometric deflection of the background star's apparent position. Ground-based photometry shows a parallactic signature of the effect of the Earth's motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 +/- 1.3 M_Sun and a distance of 1.58 +/- 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic-disk stars at similar distances by an amount corresponding to a transverse space velocity of ~45 km/s, suggesting that the BH received a modest natal 'kick' from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial-velocity measurements of Galactic X-ray binaries, and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first ever for an isolated stellar-mass BH using any technique
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