8,026 research outputs found
TIFA, an inflammatory signaling adaptor, is tumor suppressive for liver cancer.
TIFA (TNF receptor associated factor (TRAF)-interacting protein with a Forkhead-associated (FHA) domain), also called T2BP, was first identified using a yeast two-hybrid screening. TIFA contains a FHA domain, which directly binds phosphothreonine and phosphoserine, and a consensus TRAF6-binding motif. TIFA-mediated oligomerization and poly-ubiquitinylation of TRAF6 mediates signaling downstream of the Tumor necrosis factor alpha receptor 1 (TNFaR-I) and interleukin-1/Toll-like receptor 4 (TLR4) pathways. Examining TIFA expression in hepatocellular carcinoma (HCC) tissues microarrays, we noted marked decreases TIFA reactivity in tumor versus control samples. In agreement, we found that HCC cell lines show reduced TIFA expression levels versus normal liver controls. Reconstituting TIFA expression in HCC cell lines promoted two independent apoptosis signaling pathways: the induction of p53 and cell cycle arrest, and the activation of caspase-8 and caspase-3. In contrast, the expression of a non-oligomerizing mutant of TIFA impacted cells minimally, and suppression of TIFA expression protected cells from apoptosis. Mice bearing TIFA overexpression hepatocellular xenografts develop smaller tumors versus TIFA mutant tumors; terminal deoxynucleotidyl transferase dUTP nick end labeling staining demonstrates increased cell apoptosis, and decreased proliferation, reflecting cell cycle arrest. Interestingly, p53 has a greater role in decreased proliferation than cell death, as it appeared dispensable for TIFA-induced cell killing. The findings demonstrate a novel suppressive role of TIFA in HCC progression via promotion of cell death independent of p53
State transition and electrocaloric effect of BaZrTiO: simulation and experiment
The electrocaloric effect (ECE) of BaZrTiO (BZT) is closely
related to the relaxor state transition of the materials. This work presents a
systematic study on the ECE and the state transition of the BZT, using a
combined canonical and microcanonical Monte Carlo simulations based a
lattice-based on a Ginzburg-Landau-type Hamiltonian. For comparison and
verification, experimental measurements have been carried on BTO and BZT
( and ) samples, including the ECE at various temperatures, domain
patterns by Piezoresponse Force Microscopy at room temperature, and the P-E
loops at various temperatures. Results show that the dependency of BZT behavior
of the Zr-concentration can be classified into three different stages. In the
composition range of , ferroelectric domains are visible,
but ECE peak drops with increasing Zr-concentration harshly. In the range of , relaxor features become prominent, and the decrease of
ECE with Zr-concentration is moderate. In the high concentration range of , the material is almost nonpolar, and there is no ECE peak visible.
Results suggest that BZT with certain low range of Zr-concentration around
can be a good candidate with relatively high ECE and
simutaneously wide temperature application range at rather low temperature
Type-II Topological Dirac Semimetals: Theory and Materials Prediction (VAl3 family)
The discoveries of Dirac and Weyl semimetal states in spin-orbit compounds
led to the realizations of elementary particle analogs in table-top
experiments. In this paper, we propose the concept of a three-dimensional
type-II Dirac fermion and identify a new topological semimetal state in the
large family of transition-metal icosagenides, MA3 (M=V, Nb, Ta; A=Al, Ga, In).
We show that the VAl3 family features a pair of strongly Lorentz-violating
type-II Dirac nodes and that each Dirac node consists of four type-II Weyl
nodes with chiral charge +/-1 via symmetry breaking. Furthermore, we predict
the Landau level spectrum arising from the type-II Dirac fermions in VAl3 that
is distinct from that of known Dirac semimetals. We also show a topological
phase transition from a type-II Dirac semimetal to a quadratic Weyl semimetal
or a topological crystalline insulator via crystalline distortions. The new
type-II Dirac fermions, their novel magneto-transport response, the topological
tunability and the large number of compounds make VAl3 an exciting platform to
explore the wide-ranging topological phenomena associated with
Lorentz-violating Dirac fermions in electrical and optical transport,
spectroscopic and device-based experiments.Comment: 28 pages, 7 Figure
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