705 research outputs found
Coupled Reversible and Irreversible Bistable Switches Underlying TGF-\beta-induced Epithelial to Mesenchymal Transition
Epithelial to mesenchymal transition (EMT) plays important roles in embryonic
development, tissue regeneration and cancer metastasis. While several feedback
loops have been shown to regulate EMT, it remains elusive how they coordinately
modulate EMT response to TGF-\beta treatment. We construct a mathematical model
for the core regulatory network controlling TGF-\beta-induced EMT. Through
deterministic analyses and stochastic simulations, we show that EMT is a
sequential two-step program that an epithelial cell first transits to partial
EMT then to the mesenchymal state, depending on the strength and duration of
TGF-\beta stimulation. Mechanistically the system is governed by coupled
reversible and irreversible bistable switches. The SNAIL1/miR-34 double
negative feedback loop is responsible for the reversible switch and regulates
the initiation of EMT, while the ZEB/miR-200 feedback loop is accountable for
the irreversible switch and controls the establishment of the mesenchymal
state. Furthermore, an autocrine TGF-\beta/miR-200 feedback loop makes the
second switch irreversible, modulating the maintenance of EMT. Such coupled
bistable switches are robust to parameter variation and molecular noise. We
provide a mechanistic explanation on multiple experimental observations. The
model makes several explicit predictions on hysteretic dynamic behaviors,
system response to pulsed stimulation and various perturbations, which can be
straightforwardly tested.Comment: 32 pages, 8 figures, accepted by Biophysical Journa
Sequential Wnt Agonist then Antagonist Treatment Accelerates Tissue Repair and Minimizes Fibrosis
Tissue fibrosis compromises organ function and occurs as a potential
long-term outcome in response to acute tissue injuries. Currently, lack of
mechanistic understanding prevents effective prevention and treatment of the
progression from acute injury to fibrosis. Here, we combined quantitative
experimental studies with a mouse kidney injury model and a computational
approach to determine how the physiological consequences are determined by the
severity of ischemia injury, and to identify how to manipulate Wnt signaling to
accelerate repair of ischemic tissue damage while minimizing fibrosis. The
study reveals that Wnt-mediated memory of prior injury contributes to fibrosis
progression, and ischemic preconditioning reduces the risk of death but
increases the risk of fibrosis. Furthermore, we validated the prediction that
sequential combination therapy of initial treatment with a Wnt agonist followed
by treatment with a Wnt antagonist can reduce both the risk of death and
fibrosis in response to acute injuries
Classical-driving-assisted quantum synchronization in non-Markovian environments
We study the quantum phase synchronization of a driven two-level system (TLS)
coupled to a structured environment and demonstrate that quantum
synchronization can be enhanced by the classical driving field. We use the
Husimi -function to characterize the phase preference and find the in-phase
and anti-phase locking phenomenon in the phase diagram. Remarkably, we show
that the classical driving enables a TLS to reach stable anti-phase locking in
the Markovian regime. However, we find that the synergistic action of classical
driving and non-Markovian effects significantly enhances the in-phase locking.
By introducing the -function and its maximal value to quantify the strength
of synchronization and sketch the synchronization regions, we observe the
typical signatures of the hollowed Arnold tongue in the parameter regions of
synchronization. In the hollowed Arnold tongue, the synchronization regions
exist both inside and outside the tongue while unsynchronized regions only lie
on the boundary line. We also provide an intuitive interpretation of the above
results by using the quasimode theory.Comment: 10 pages, 5 figures, revised versio
Phase evolution of Ce-based heavy-fermion superconductors under pressure: a combined DFT+DMFT and effective-model description
In typical Ce-based heavy-fermion superconductors, superconducting (SC)
phases emerge or can be tuned in proximity to the antiferromagnetic (AF)
quantum critical point (QCP), but so far the explicit phase-evolution process
and the coexistence of superconductivity and AF order near the QCP remain lack
of understanding. Here, by combing DFT+DMFT with effective-model calculations,
we provide a theoretical description for Ce-based SC compounds under pressure.
Firstly, DFT+DMFT calculations for the normal states reveal that the Kondo
hybridizations are significantly enhanced, while the initially localized
electrons eventually become fully itinerant via a localized-itinerant
crossover. In this context, we construct an effective model with tunable
parameters under pressure, and show that the interplay of magnetic correlation
and Kondo hybridization can drive successive transitions, from AF phase to
AF+SC coexisting phase, then to paramagnetic SC phase via an AF transition
which corresponds to the QCP, and finally to Kondo paramagnetic phase through a
SC transition driven by localized-itinerant crossover. Our study gives a proper
explanation for the pressure-induced magnetic QCP and SC transition, and for
the phase-evolution process under pressure in typical Ce-based superconductors,
and may also help to understand the SC states emerging around the ferromagnetic
quantum transition points in uranium-based superconductors.Comment: 13 pages, 11 figure
Global fitness profiling of fission yeast deletion strains by barcode sequencing
A genome-wide deletion library is a powerful tool for probing gene functions and one has recently become available for the fission yeast Schizosaccharomyces pombe. Here we use deep sequencing to accurately characterize the barcode sequences in the deletion library, thus enabling the quantitative measurement of the fitness of fission yeast deletion strains by barcode sequencing
Node-line Dirac semimetal manipulated by Kondo mechanism in nonsymmorphic CePtSi
Dirac node lines (DNLs) are characterized by Dirac-type linear crossings
between valence and conduction bands along one-dimensional node lines in the
Brillouin zone (BZ). Spin-orbit coupling (SOC) usually shifts the degeneracy at
the crossings thus destroys DNLs, and so far the reported DNLs in a few
materials are non-interacting type, making the search for robust interacting
DNLs in real materials appealing. Here, via first-principle calculations, we
reveal that Kondo interaction together with nonsymmorphic lattice symmetries
can drive a robust interacting DNLs in a Kondo semimetal CePt_2Si_2, and the
feature of DNLs can be significantly manipulated by Kondo behavior in different
temperature regions. Based on the density function theory combining dynamical
mean-field theory (DFT+DMFT), we predict a transition to Kondo-coherent state
at coherent temperature T_coh= 80 K upon cooling, verified by temperature
dependence of Ce-4f self-energy, Kondo resonance peak, magnetic susceptibility
and momentum-resolved spectral. Below T_coh, well-resolved narrow heavy-fermion
bands emerge near the Fermi level, constructing clearly visualized interacting
DNLs locating at the BZ boundary, in which the Dirac fermions have strongly
enhanced effective mass and reduced velocity. In contrast, above a crossover
temperature T_KS =600 K, the destruction of local Kondo screening drives
non-interacting DNLs which are comprised by light conduction electrons at the
same location. These DNLs are protected by lattice nonsymmorphic symmetries
thus robust under intrinsic strong SOC. Our proposal of DNLs which can be
significantly manipulated according to Kondo behavior provides an unique
realization of interacting Dirac semimetals in real strongly correlated
materials, and serves as a convenient platform to investigate the effect of
electronic correlations on topological materials.Comment: 9 pages, 9 figure
The multitasking Fasciola gigantica Cathepsin B interferes with various functions of goat peripheral blood mononuclear cells in vitro
Cathepsin B, a lysosomal cysteine protease, is thought to be involved in the pathogenesis of Fasciola gigantica infection, but its exact role remains unclear. In the present study, a recombinant F. gigantica cathepsin B (rFgCatB) protein was expressed in the methylotrophic yeast Pichia pastoris. Western blot analysis confirmed the reactivity of the purified rFgCatB protein to serum from F. gigantica-infected goats. The effects of serial concentrations (10, 20, 40, 80, and 160 μg/ml) of rFgCatB on various functions of goat peripheral blood mononuclear cells (PBMCs) were examined. We demonstrated that rFgCatB protein can specifically bind to the surface of PBMCs. In addition, rFgCatB increased the expression of cytokines (IL-2, IL-4, IL-10, IL-17, TGF-β, and IFN-γ), and increased nitric oxide production and cell apoptosis, but reduced cell viability. These data show that rFgCatB can influence cellular and immunological functions of goat PBMCs. Further characterization of the posttranslational modification and assessment of rFgCatB in immunogenicity studies is warranted
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