We demonstrate a silicone damping elastomer with a constant high damping performance (tan δ ) E′′/E′ ≈ 0.3 where E′ and E′′ are the storage and loss Young's moduli, respectively) over a broad temperature range of 180 °C (-30 °C < T < 150 °C) utilizing a slow viscoelastic relaxation of an irregular network structure with many pendant chains. In addition to tan δ, E′ is almost unaltered in the corresponding temperature range. These are in contrast to the markedly temperature-dependent damping and modulus of conventional damping elastomers using the glass transition as the energy dissipation. The temperature-and frequency-insensitive damping and elasticity are of significance to extend the availability in the industrial uses. The irregular networks have been prepared by end-linking a mixture of bi-and monofunctional end-reactive precursor linear poly(dimethylsiloxane) (PDMS) chains with trifunctional cross-linker, or end-linking the bifunctional precursor chains with trifunctional cross-linker at off-stoichiometric ratios. Independently of mechanical testing, the fractions of pendant (W pen ) and elastic chains (W el ) in the irregular networks have been evaluated using a nonlinear polymerization model. It has been demonstrated that tan δ increases with increasing W pen ; the pendant chain whose one end is free to move significantly contributes to the dissipation of deformation energy via the viscoelastic relaxation. The temperature-and frequency-insensitive damping originates from a broad relaxation spectrum of the irregular networks comprising the pendant branched chains with various shapes and a wide size distribution.

Diaphanous-related formin, mDia, is an actin nucleation/polymerization factor functioning downstream of the small GTPase Rho. Although Rho is critically involved in cytokinesis, it remains elusive how Rho effectors and other regulators of cytoskeletons work together to accomplish this process. Here we focused on mDia2, an mDia isoform involved in cytokinesis of NIH 3T3 cells, and analyzed mechanisms of its localization in cytokinesis. We found that targeting of mDia2 to the cleavage furrow requires not only its binding to RhoA but also its diaphanous-inhibitory domain (DID). We then performed pulldown assays using a fragment containing the latter domain as a bait and identified anillin as a novel mDia2 interaction partner. The anillin-binding is competitive with the diaphanous autoregulatory domain (DAD) of mDia2 in its autoinhibitory interaction. A series of RNA interference and functional rescue experiments has revealed that, in addition to the Rho GTPase-mediated activation, the interaction between mDia2 and anillin is required for the localization and function of mDia2 in cytokinesis.

Trafficking of immune cells is controlled by directed migration of relevant cells toward chemotactic signals. Actin cytoskeleton undergoes continuous remodeling and serves as machinery for cell migration. The mDia family of formins and the Wiskott-Aldrich syndrome protein (WASP)–Arp2/3 system are two major actin nucleating–polymerizing systems in mammalian cells, with the former producing long straight actin filaments and the latter producing branched actin meshwork. Although much is known about the latter, the physiological functions of mDia proteins are unclear. We generated mice deficient in one mDia isoform, mDia1. Although mDia1−/− mice were born and developed without apparent abnormality, mDia1−/− T lymphocytes exhibited impaired trafficking to secondary lymphoid organs in vivo and showed reduced chemotaxis, little actin filament formation, and impaired polarity in response to chemotactic stimuli in vitro. Similarly, mDia1−/− thymocytes showed reduced chemotaxis and impaired egression from the thymus. These results suggest that mDia1 plays a distinct role in chemotaxis in T lymphocyte trafficking.

We have successfully developed a 1020MHz (24.0T) NMR magnet, establishing the world's highest magnetic field in high resolution NMR superconducting magnets. The magnet is a series connection of LTS (low-Tc superconductors NbTi and Nb3Sn) outer coils and an HTS (high-Tc superconductor, Bi-2223) innermost coil, being operated at superfluid liquid helium temperature such as around 1.8K and in a driven-mode by an external DC power supply. The drift of the magnetic field was initially ±0.8ppm/10h without the (2)H lock operation; it was then stabilized to be less than 1ppb/10h by using an NMR internal lock operation. The full-width at half maximum of a (1)H spectrum taken for 1% CHCl3 in acetone-d6 was as low as 0.7Hz (0.7ppb), which was sufficient for solution NMR. On the contrary, the temporal field stability under the external lock operation for solid-state NMR was 170ppb/10h, sufficient for NMR measurements for quadrupolar nuclei such as (17)O; a (17)O NMR measurement for labeled tri-peptide clearly demonstrated the effect of high magnetic field on solid-state NMR spectra.

Exportin-5, an evolutionarily conserved nuclear export factor belonging to the importin-β family of proteins, is known to play a role in the nuclear export of small noncoding RNAs such as precursors of microRNA, viral minihelix RNA and a subset of tRNAs in mammalian cells. In this study, we show that the exportin-5 orthologues from different species such as human, fruit fly and yeast exhibit diverged functions. We found that Msn5p, a yeast exportin-5 orthologue, binds double-stranded RNAs and that it prefers a shorter 22 nt, double-stranded RNA to ∼80 nt pre-miRNA, even though both of these RNAs share a similar terminal structure. Furthermore, we found that Drosophila exportin-5 binds pre-miRNAs and that amongst the exportin-5 orthologues tested, it shows the highest affinity for tRNAs. The knockdown of Drosophila exportin-5 in cultured cells decreased the amounts of tRNA as well as miRNA, whereas the knock down of human exportin-5 in cultured cells affected only miRNA but not tRNA levels. These results indicate that double-stranded RNA binding ability is an inherited functional characteristic of the exportin-5 orthologues and that Drosophila exportin-5 functions as an exporter of tRNAs as well as pre-miRNAs in the fruit fly that lacks the orthologous gene for exportin-t.

XRN2 is an essential eukaryotic exoribonuclease that processes and degrades various substrates. Here we identify the previously uncharacterized protein R05D11.6/PAXT-1 as a subunit of an XRN2 complex in C. elegans. Targeted paxt-1 inactivation through TALEN-mediated genome editing reduces XRN2 levels, decreases miRNA turnover activity, and results in worm death, which can be averted by overexpressing xrn-2. Hence, stabilization of XRN2 is a major function of PAXT-1. A truncated PAXT-1 protein retaining a predicted domain of unknown function (DUF3469) suffices to restore viability to paxt-1 mutant animals, elevates XRN2 levels, and binds to XRN2. This domain occurs in additional metazoan proteins and mediates interaction of human CDKN2AIP/CARF and NKRF/NRF with XRN2. Thus, we have identified a bona fide XRN2-binding domain (XTBD) that can link different proteins, and possibly functionalities, to XRN2.

NCT02179658.

Modification of the carboxyl group at the 3-position and introduction of protective groups to the hydroxy group of the 4,1-benzoxazepine derivative 2 (metabolite of 1) were carried out, and the inhibitory activity for squalene synthase and cholesterol synthesis in the liver was investigated. Among these compounds, the glycine derivative 3a and beta-alanine derivative 3f exhibited the most potent inhibition of squalene synthase prepared from HepG2 cells (IC(50) = 15 nM). On the other hand, the piperidine-4-acetic acid derivative 4a, which was prepared by acetylation of 3j, was the most effective inhibitor of cholesterol synthesis in rat liver (ED(50) = 2.9 mg/kg, po). After oral administration, 4a was absorbed and rapidly hydrolyzed to deacylated 3j. Compound 3j was detected mainly in the liver, but the plasma level of 3j was found to be low. Compounds 3j and 4a were found to be competitive inhibitors with respect to farnesyl pyrophosphate. Further evaluation of 4a as a cholesterol-lowering and antiatherosclerotic agent is underway.