537 research outputs found
The long non-coding RNA Kcnq1ot1 controls maternal p57 expression in muscle cells by promoting H3K27me3 accumulation to an intragenic MyoD-binding region
BACKGROUND:
The cell-cycle inhibitor p57kip2 plays a critical role in mammalian development by coordinating cell proliferation and differentiation in many cell types. p57kip2 expression is finely regulated by several epigenetic mechanisms, including paternal imprinting. Kcnq1ot1, a long non-coding RNA (LncRNA), whose gene maps to the p57Kip2 imprinting domain, is expressed exclusively from the paternal allele and participates in the cis-silencing of the neighboring imprinted genes through chromatin-level regulation. In light of our previous evidence of a functional interaction between myogenic factors and imprinting control elements in the regulation of the maternal p57Kip2 allele during muscle differentiation, we examined the possibility that also Kcnq1ot1 could play an imprinting-independent role in the control of p57Kip2 expression in muscle cells.
RESULTS:
We found that Kcnq1ot1 depletion by siRNA causes the upregulation of the maternal and functional p57Kip2 allele during differentiation, suggesting a previously undisclosed role for this LncRNA. Consistently, Chromatin Oligo-affinity Precipitation assays showed that Kcnq1ot1 physically interacts not only with the paternal imprinting control region of the locus, as already known, but also with both maternal and paternal alleles of a novel p57Kip2 regulatory region, located intragenically and containing two binding sites for the muscle-specific factor MyoD. Moreover, chromatin immunoprecipitation assays after Kcnq1ot1 depletion demonstrated that the LncRNA is required for the accumulation of H3K27me3, a chromatin modification catalyzed by the histone-methyl-transferase EZH2, at the maternal p57kip2 intragenic region. Finally, upon differentiation, the binding of MyoD to this region and its physical interaction with Kcnq1ot1, analyzed by ChIP and RNA immunoprecipitation assays, correlate with the loss of EZH2 and H3K27me3 from chromatin and with p57Kip2 de-repression.
CONCLUSIONS:
These findings highlight the existence of an imprinting-independent role of Kcnq1ot1, adding new insights into the biology of a still mysterious LncRNA. Moreover, they expand our knowledge about the molecular mechanisms underlying the tight and fine regulation of p57Kip2 during differentiation and, possibly, its aberrant silencing observed in several pathologic conditions
Ventricular Tachyarrhythmias in Implantable Cardioverter Defibrillator Recipients: Differences Between Ischemic and Dilated Cardiomyopathies
Circ-ZNF609 regulates G1-S progression in rhabdomyosarcoma
Circular RNAs (circRNAs) represent a class of covalently closed RNAs, derived from non-canonical splicing events, which are expressed in all eukaryotes and often conserved among different species. We previously showed that the circRNA originating from the ZNF609 locus (circ-ZNF609) acts as a crucial regulator of human primary myoblast growth: indeed, the downregulation of the circRNA, and not of its linear counterpart, strongly reduced the proliferation rate of in vitro cultured myoblasts. To deepen our knowledge about circ-ZNF609 role in cell cycle regulation, we studied its expression and function in rhabdomyosarcoma (RMS), a pediatric skeletal muscle malignancy. We found that circ-ZNF609 is upregulated in biopsies from the two major RMS subtypes, embryonal (ERMS) and alveolar (ARMS). Moreover, we discovered that in an ERMS-derived cell line circ-ZNF609 knock-down induced a specific block at the G1-S transition, a strong decrease of p-Akt protein level and an alteration of the pRb/Rb ratio. Regarding p-Akt, we were able to show that circ-ZNF609 acts by counteracting p-Akt proteasome-dependent degradation, thus working as a new regulator of cell proliferation-related pathways. As opposed to ERMS-derived cells, the circRNA depletion had no cell cycle effects in ARMS-derived cells. Since in these cells the p53 gene resulted downregulated, with a concomitant upregulation of its cell cycle-related target genes, we suggest that this could account for the lack of circ-ZNF609 effect in ARMS
Breathing New Life into Historical Instruments. How to Monitor Corrosion
‘To play or to display’ is the dilemma that museums have to face, given the increasing trend towards historically informed performance. Brass instruments can suffer corrosion both during and after playing due to the high humidity inside them. To forestall or at least reduce corrosion, drying with a fan has been chosen as a preventive measure. The state of corrosion inside the tuning slides of the instruments was determined with a specially developed electrochemical sensor. The results of the project show that drying with a fan indeed reduces ongoing corrosion, when compared to a group of instruments played without preventive measures that showed an increasing corrosion rate over time
Minimum-energy broadcast in random-grid ad-hoc networks: approximation and distributed algorithms
The Min Energy broadcast problem consists in assigning transmission ranges to
the nodes of an ad-hoc network in order to guarantee a directed spanning tree
from a given source node and, at the same time, to minimize the energy
consumption (i.e. the energy cost) yielded by the range assignment. Min energy
broadcast is known to be NP-hard.
We consider random-grid networks where nodes are chosen independently at
random from the points of a square grid in the
plane. The probability of the existence of a node at a given point of the grid
does depend on that point, that is, the probability distribution can be
non-uniform.
By using information-theoretic arguments, we prove a lower bound
on the energy cost of any feasible solution for
this problem. Then, we provide an efficient solution of energy cost not larger
than .
Finally, we present a fully-distributed protocol that constructs a broadcast
range assignment of energy cost not larger than ,thus still yielding
constant approximation. The energy load is well balanced and, at the same time,
the work complexity (i.e. the energy due to all message transmissions of the
protocol) is asymptotically optimal. The completion time of the protocol is
only an factor slower than the optimum. The approximation quality
of our distributed solution is also experimentally evaluated.
All bounds hold with probability at least .Comment: 13 pages, 3 figures, 1 tabl
TetraPh-Tol-BITIOPO: a new atropisomeric 3,3’-bithiophene based phosphine oxide as organocatalyst in Lewis Base-catalyzed Lewis Acid mediated reactions
A new chiral phosphine oxide based on 3,3’-bithiophene scaffold (tetraPh-Tol-BITIOPO) was synthesized, fully characterized
and separated into antipodes through chiral HPLC. This new compound was successfully employed as organocatalyst in Lewis
base-catalyzed Lewis acid mediated reactions involving trichlorosilyl compounds. The new atropisomeric catalyst was able
to promote the allylation of aldehydes with allyltrichlorosilane in up to 98% yield and up to 96% enantiomeric excess (ee),
and the direct aldol reaction to afford β-hydroxy ketones and β-hydroxy thioesters, with good chemical yields and modest
stereochemical efficiency. Computational studies helped to elucidate and to rationalize the stereochemical outcome of the
reactions catalyzed by TetraPh-Tol-BITIOPO, that was found to favour the formation of the isomer with the opposite absolute
configuration in comparison with the products obtained with the previously reported 3,3’-bithiophene-based catalyst
Changes in inflammatory biomarkers in HCV-infected patients undergoing direct acting antiviral-containing regimens with or without interferon
Background and aims
Increased levels of chemokine interferon-gamma (IFN-γ)-inducible protein-10 (CXCL10),
soluble CD163 (sCD163) and soluble CD14 (sCD14) have been reported in HCV infection.
The aim of this study was to compare, sCD163 and sCD14 levels in HCV-infected patients
undergoing direct acting antiviral (DAA)-containing regimens with or without interferon
(IFN).
Methods
sCD163, sCD14 and CXCL10 were longitudinally measured by ELISA in 159 plasma samples from 25 HCV-infected patients undergoing IFN-based treatment plus telaprevir or
boceprevir and 28 HCV infected subjects treated with DAA IFN-free regimens. Twenty-five
healthy donors (HD) were included as controls.
Results
At baseline CXCL10, sCD163 and sCD14 levels were higher in HCV-infected patients than
in HD. CXCL10 and sCD163 levels were significantly decreased in responder (R) patients
who achieved sustained virological response (SVR), with both IFN-based and IFN-free regimens, while they were persistently elevated in non-responders (NR) patients who stopped
IFN-based treatments because of failure or adverse events. Conversely, sCD14 levels
were apparently unchanged during therapy, but at the end of treatment the levels reached
normal ranges. Comparing the two regimens, the extent of CXCL10 reduction was more
pronounced in patients undergoing DAA IFN-free therapies, whereas sCD163 and sCD14
reduction was similar in the two groups.
Interestingly, only in IFN-based regimens baseline sCD163 levels were significantly
higher in NR than in R patients, while in the IFN-free treatment group also patients with highsCD163 plasma levels obtained SVR. At the end of therapy, even if the biomarkers were
largely decreased, their levels remained significantly higher compared to HD. Only in the
early fibrosis stages, sCD163 values tended to normalize.
Conclusions
These results indicate that IFN-free regimens including newer DAA induce an early and
marked decrease in circulating inflammatory biomarkers. However, the full normalization of
biomarkers was not obtained, especially in patients with advanced fibrosis, thus underlying
the need for a treatment in the early stages of HCV infection
Circ-ZNF609 Is a Circular RNA that Can Be Translated and Functions in Myogenesis
Circular RNAs (circRNAs) constitute a family of transcripts with unique structures and still largely unknown functions. Their biogenesis, which proceeds via a back-splicing reaction, is fairly well characterized, whereas their role in the modulation of physiologically relevant processes is still unclear. Here we performed expression profiling of circRNAs during in vitro differentiation of murine and human myoblasts, and we identified conserved species regulated in myogenesis and altered in Duchenne muscular dystrophy. A high-content functional genomic screen allowed the study of their functional role in muscle differentiation. One of them, circ-ZNF609, resulted in specifically controlling myoblast proliferation. Circ-ZNF609 contains an open reading frame spanning from the start codon, in common with the linear transcript, and terminating at an in-frame STOP codon, created upon circularization. Circ-ZNF609 is associated with heavy polysomes, and it is translated into a protein in a splicing-dependent and cap-independent manner, providing an example of a protein-coding circRNA in eukaryotes
A new generation photodetector for astroparticle physics: the VSiPMT
The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design we
proposed for a revolutionary photon detector. The main idea is to replace the
classical dynode chain of a PMT with a SiPM (G-APD), the latter acting as an
electron detector and amplifier. The aim is to match the large sensitive area
of a photocathode with the performance of the SiPM technology. The VSiPMT has
many attractive features. In particular, a low power consumption and an
excellent photon counting capability. To prove the feasibility of the idea we
first tested the performance of a special non-windowed SiPM by Hamamatsu (MPPC)
as electron detector and current amplifier. Thanks to this result Hamamatsu
realized two VSiPMT industrial prototypes. In this work, we present the results
of a full characterization of the VSiPMT prototype
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