Post-translational modifications of proteins have emerged as a major mechanism for regulating gene expression. However, our understanding of how histone modifications directly affect chromatin ...function remains limited. In this study, we investigate acetylation of histone H3 at lysine 64 (H3K64ac), a previously uncharacterized acetylation on the lateral surface of the histone octamer. We show that H3K64ac regulates nucleosome stability and facilitates nucleosome eviction and hence gene expression in vivo. In line with this, we demonstrate that H3K64ac is enriched in vivo at the transcriptional start sites of active genes and it defines transcriptionally active chromatin. Moreover, we find that the p300 co-activator acetylates H3K64, and consistent with a transcriptional activation function, H3K64ac opposes its repressive counterpart H3K64me3. Our findings reveal an important role for a histone modification within the nucleosome core as a regulator of chromatin function and they demonstrate that lateral surface modifications can define functionally opposing chromatin states. DOI: http://dx.doi.org/10.7554/eLife.01632.001.
BACKGROUND:The angiogenic function of endothelial cells is regulated by numerous mechanisms, but the impact of long noncoding RNAs (lncRNAs) has hardly been studied. We set out to identify novel and ...functionally important endothelial lncRNAs.
METHODS:Epigenetically controlled lncRNAs in human umbilical vein endothelial cells were searched by exon-array analysis after knockdown of the histone demethylase JARID1B. Molecular mechanisms were investigated by RNA pulldown and immunoprecipitation, mass spectrometry, microarray, several knockdown approaches, CRISPR-Cas9, assay for transposase-accessible chromatin sequencing, and chromatin immunoprecipitation in human umbilical vein endothelial cells. Patient samples from lung and tumors were studied for MANTIS expression.
RESULTS:A search for epigenetically controlled endothelial lncRNAs yielded lncRNA n342419, here termed MANTIS, as the most strongly regulated lncRNA. Controlled by the histone demethylase JARID1B, MANTIS was downregulated in patients with idiopathic pulmonary arterial hypertension and in rats treated with monocrotaline, whereas it was upregulated in carotid arteries of Macaca fascicularis subjected to atherosclerosis regression diet, and in endothelial cells isolated from human glioblastoma patients. CRISPR/Cas9-mediated deletion or silencing of MANTIS with small interfering RNAs or GapmeRs inhibited angiogenic sprouting and alignment of endothelial cells in response to shear stress. Mechanistically, the nuclear-localized MANTIS lncRNA interacted with BRG1, the catalytic subunit of the switch/sucrose nonfermentable chromatin-remodeling complex. This interaction was required for nucleosome remodeling by keeping the ATPase function of BRG1 active. Thereby, the transcription of key endothelial genes such as SOX18, SMAD6, and COUP-TFII was regulated by ensuring efficient RNA polymerase II machinery binding.
CONCLUSION:MANTIS is a differentially regulated novel lncRNA facilitating endothelial angiogenic function.
Today's spectrum of research in literary studies is characterized by a sense of openness to the methods of comparative literature and cultural studies, along with a wide range of interdisciplinary ...crossover. The spectrum Literaturwissenschaft series is intended to be a forum for this pluralistic new model of literary studies. It presents papers that are informed by methodologically innovative, frequently comparative approaches, and whose findings are of importance well beyond the narrow boundaries of national philological horizons.
Abstract
Recent oncological studies identified beneficial properties of radiation applied at ultrahigh dose rates, several orders of magnitude higher than the clinical standard of the order of Gy min
...–1
. Sources capable of providing these ultrahigh dose rates are under investigation. Here we show that a stable, compact laser-driven proton source with energies greater than 60 MeV enables radiobiological in vivo studies. We performed a pilot irradiation study on human tumours in a mouse model, showing the concerted preparation of mice and laser accelerator, dose-controlled, tumour-conform irradiation using a laser-driven as well as a clinical reference proton source, and the radiobiological evaluation of irradiated and unirradiated mice for radiation-induced tumour growth delay. The prescribed homogeneous dose of 4 Gy was precisely delivered at the laser-driven source. The results demonstrate a complete laser-driven proton research platform for diverse user-specific small animal models, able to deliver tunable single-shot doses up to around 20 Gy to millimetre-scale volumes on nanosecond timescales, equivalent to around 10
9
Gy s
–1
, spatially homogenized and tailored to the sample. The platform provides a unique infrastructure for translational research with protons at ultrahigh dose rates.
Hsp90 couples ATP hydrolysis to large conformational changes essential for activation of client proteins. The structural transitions involve dimerization of the N-terminal domains and formation of ...'closed states' involving the N-terminal and middle domains. Here, we used Hsp90 mutants that modulate ATPase activity and biological function as probes to address the importance of conformational cycling for Hsp90 activity. We found no correlation between the speed of ATP turnover and the in vivo activity of Hsp90: some mutants with almost normal ATPase activity were lethal, and some mutants with lower or undetectable ATPase activity were viable. Our analysis showed that it is crucial for Hsp90 to attain and spend time in certain conformational states: a certain dwell time in open states is required for optimal processing of client proteins, whereas a prolonged population of closed states has negative effects. Thus, the timing of conformational transitions is crucial for Hsp90 function and not cycle speed.
In the absence of any global positioning infrastructure for indoor environments, research on supporting human indoor localization and navigation trails decades behind research on outdoor localization ...and navigation. The major barrier to broader progress has been the dependency of indoor positioning on environment-specific infrastructure and resulting tailored technical solutions. Combined with the fragmentation and compartmentalization of indoor environments, this poses significant challenges to widespread adoption of indoor location-based services. This article puts aside all approaches of infrastructure-based support for human indoor localization and navigation and instead reviews technical concepts that are
independent
of sensors embedded in the environment. The reviewed concepts rely on a mobile computing platform with sensing capability and a human interaction interface (“smartphone”). This platform may or may not carry a stored map of the environment, but does not require
in situ
internet access. In this regard, the presented approaches are more challenging than any localization and navigation solutions specific to a particular, infrastructure-equipped indoor space, since they are not adapted to local context, and they may lack some of the accuracy achievable with those tailored solutions. However, only these approaches have the potential to be universally applicable.
The receptor tyrosine kinase HER2 acts as oncogenic driver in numerous cancers. Usually, the gene is amplified, resulting in receptor overexpression, massively increased signaling and unchecked ...proliferation. However, tumors become frequently addicted to oncogenes and hence are druggable by targeted interventions. Here, we design an anti-HER2 biparatopic and tetravalent IgG fusion with a multimodal mechanism of action. The molecule first induces HER2 clustering into inactive complexes, evidenced by reduced mobility of surface HER2. However, in contrast to our earlier binders based on DARPins, clusters of HER2 are thereafter robustly internalized and quantitatively degraded. This multimodal mechanism of action is found only in few of the tetravalent constructs investigated, which must target specific epitopes on HER2 in a defined geometric arrangement. The inhibitory effect of our antibody as single agent surpasses the combination of trastuzumab and pertuzumab as well as its parental mAbs in vitro and it is effective in a xenograft model.
Quantum particles can penetrate potential barriers by tunnelling1. If that barrier is rotating, the tunnelling process is modified2,3. This is typical for electrons in atoms, molecules or solids ...exposed to strong circularly polarized laser pulses4–6. Here we measure how the transmission probability through a rotating tunnel depends on the sign of the magnetic quantum number m of the electron and thus on the initial direction of rotation of its quantum phase. We further show that our findings agree with a semiclassical picture, in which the electron keeps part of that rotary motion on its way through the tunnel by measuring m-dependent modification of the electron emission pattern. These findings are relevant for attosecond metrology as well as for interpretation of strong-field electron emission from atoms and molecules7–14 and directly demonstrate the creation of ring currents in bound states of ions with attosecond precision. In solids, this could open a way to inducing and controlling ring-current-related topological phenomena15.
Silicon solar cells featuring the highest conversion efficiencies are made from monocrystalline n-type silicon. The superior crystal quality of high-performance multicrystalline silicon (HP mc) in ...combination with the inherent benefits of n-type doping (higher tolerance to common impurities) should allow the fabrication of high-efficiency solar cells also on mc silicon. In this paper, we address high-efficiency n-type HP mc solar cells with diffused boron front emitter and full-area passivating rear contact (TOPCon). n-type HP mc silicon was crystallized at Fraunhofer ISE featuring a very high average lifetime in the range of 600 μs (i.e., diffusion length >800 μm) after application of all high-temperature steps necessary for cell fabrication. Using a "black silicon" front texture we have achieved a weighted reflectance of ~1% and simultaneously a very good electrical performance, i.e., J 0e values of ≤ 60 fA/cm 2 for a 90 Ω/sq emitter. The resulting n-type mc silicon solar cells show certified conversion efficiencies up to 21.9%, representing the current world record for mc silicon solar cells.
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