623 research outputs found
Prion infection impairs cholesterol metabolism in neuronal cells
Conversion of prion protein (PrPC) into a pathological isoform (PrPSc) during prion infection occurs in lipid rafts and is dependent on cholesterol. Here, we show that prion infection increases the abundance of cholesterol transporter, ATP-binding cassette transporter type A1 (ATP-binding cassette transporter type A1), but reduces cholesterol efflux from neuronal cells leading to the accumulation of cellular cholesterol. Increased abundance of ABCA1 in prion disease was confirmed in prion-infected mice. Mechanistically, conversion of PrPC to the pathological isoform led to PrPSc accumulation in rafts, displacement of ABCA1 from rafts and the cell surface, and enhanced internalization of ABCA1. These effects were abolished with reversal of prion infection or by loading cells with cholesterol. Stimulation of ABCA1 expression with liver X receptor agonist or overexpression of heterologous ABCA1 reduced the conversion of prion protein into the pathological form upon infection. These findings demonstrate a reciprocal connection between prion infection and cellular cholesterol metabolism, which plays an important role in the pathogenesis of prion infection in neuronal cells
MicroRNA-223 coordinates cholesterol homeostasis
Results from this study represent a breakthrough in our understanding of posttranscriptional control of cholesterol metabolism and how microRNAs (miRNAs) are at the heart of cholesterol regulatory circuitry and homeostasis. Although cells are adept at maintaining proper cholesterol levels, it was unknown how cells posttranscriptionally coordinate cholesterol uptake, efflux, and synthesis. MicroRNA-223 (miR-223) transcription and expression are maintained by cholesterol, and, as a feedback network, miR-223 inhibits cholesterol biosynthesis and uptake and increases cholesterol efflux. This study clearly demonstrates the extensive role that miRNAs play in coordinating metabolic adaptation to disease and general homeostasis. This work highlights a unique regulatory control point for cholesterol homeostasis and illustrates how important the study of miRNAs is to the greater understanding of dyslipidemia and cardiovascular disease
First observations of hadrons
Based on events collected with
the BESIII detector, five hadronic decays are searched for via process
. Three of them, ,
, and are observed for the first
time, with statistical significances of 7.4, , and
9.1, and branching fractions of ,
, and ,
respectively, where the first uncertainties are statistical and the second
systematic. No significant signal is observed for the other two decay modes,
and the corresponding upper limits of the branching fractions are determined to
be and at 90% confidence level.Comment: 17 pages, 16 figure
Search for the decay
We search for radiative decays into a weakly interacting neutral
particle, namely an invisible particle, using the produced through the
process in a data sample of
decays collected by the BESIII detector
at BEPCII. No significant signal is observed. Using a modified frequentist
method, upper limits on the branching fractions are set under different
assumptions of invisible particle masses up to 1.2 . The upper limit corresponding to an invisible particle with zero mass
is 7.0 at the 90\% confidence level
Measurements of Weak Decay Asymmetries of , , , and
Using production from a 567 pb
data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried
out simultaneously on the four decay modes of , , , and . For the first time, the
transverse polarization is studied in unpolarized
collisions, where a non-zero effect is observed with a statistical significance
of 2.1. The decay asymmetry parameters of the weak
hadronic decays into , , and
are measured to be ,
,
, and
, respectively. In comparison with
previous results, the measurements for the and
modes are consistent but with improved precision, while the parameters for the
and modes are measured for the first time
Observation of a structure in at from 2.05 to 3.08 GeV
The process has been studied for the
first time in detail using data sample collected with the BESIII detector at
the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A
resonance with quantum numbers is observed with mass =
(2177.5 4.8 (stat) 19.5 (syst)) MeV/ and
width = (149.0 15.6 (stat) 8.9 (syst)) MeV with a
statistical significance larger than 10. The observed structure could
be identified with the , then the ratio of partial width between
the by BESIII and by BABAR is
( = 0.23 0.10 (stat) 0.18 (syst),
which is smaller than the prediction of the hybrid models by
several orders of magnitude
Search for the reaction channel e+e−→ηcηπ+π− at center-of-mass energies from 4.23 to 4.60 GeV
Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider, we search for the process e+e-→ηcηπ+π-. The search is performed using five large datasets recorded at center-of-mass energies of 4.23, 4.26, 4.36, 4.42, and 4.60 GeV. The ηc meson is reconstructed in 16 exclusive decay modes. No signal is observed in the ηc mass region at any center-of-mass energy. The upper limits on the reaction cross sections are determined to be 6.2, 10.8, 27.6, 22.6 and 23.7 pb at the 90% confidence level at the center-of-mass energies listed above
Model-independent determination of the relative strong-phase difference between and and its impact on the measurement of the CKM angle
Crucial inputs for a variety of -violation studies can be determined
through the analysis of pairs of quantum-entangled neutral mesons, which
are produced in the decay of the resonance. The relative
strong-phase parameters between and in the decays
are studied using 2.93~ of
annihilation data delivered by the BEPCII collider and collected by
the BESIII detector at a center-of-mass energy of 3.773 GeV. Results are
presented in regions of the phase space of the decay. These are the most
precise measurements to date of the strong-phase parameters in decays. Using these parameters, the associated uncertainty
on the Cabibbo-Kobayashi-Maskawa angle is expected to be
between and , for an analysis using the decay
, , where
represents a superposition of and states. This is a factor of
three smaller than that achievable with previous measurements. Furthermore,
these results provide valuable input for charm-mixing studies, other
measurements of violation, and the measurement of strong-phase parameters
for other -decay modes.Comment: 34 pages, 10 figure
Search for the decay
A search for the rare radiative leptonic decay is
performed for the first time using electron-positron collision data
corresponding to an integrated luminosity of 3.19 fb, collected with the
BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the
decay is seen and an upper limit of is set on the partial branching
fraction at a 90\% confidence level for radiative photon energies
~GeV.Comment: 9 pages, 7 figure
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