K. Ueda

PGRP-LC and PGRP-LE have essential yet distinct functions in the drosophila immune response to monomeric DAP-type peptidoglycan.

Drosophila rely entirely on an innate immune response to combat microbial infection. Diaminopimelic acid–containing peptidoglycan, produced by Gram-negative bacteria, is recognized by two receptors, PGRP-LC and PGRP-LE, and activates a homolog of transcription factor NF-κB through the Imd signaling pathway. Here we show that full-length PGRP-LE acted as an intracellular receptor for monomeric peptidoglycan, whereas a version of PGRP-LE containing only the PGRP domain functioned extracellularly, like the mammalian CD14 molecule, to enhance PGRP-LC-mediated peptidoglycan recognition on the cell surface. Interaction with the imd signaling protein was not required for PGRP-LC signaling. Instead, PGRP-LC and PGRP-LE signaled through a receptor-interacting protein homotypic interaction motif–like motif. These data demonstrate that like mammals, drosophila use both extracellular and intracellular receptors, which have conserved signaling mechanisms, for innate immune recognition.

Design and synthesis of a dimeric derivative of RK-682 with increased inhibitory activity against VHR, a dual-specificity ERK phosphatase: implications for the molecular mechanism of the inhibition

BACKGROUND VHR is a dual-specificity phosphatase, which dephosphorylates activated ERK1/2 and weakens the ERK signaling cascade in mammalian cells. A selective inhibitor is expected to be useful for revealing the physiological function of VHR. RESULTS First, we investigated the molecular mechanism of VHR inhibition by a known natural product, RK-682. Kinetic analysis indicated that inhibition was competitive toward the substrate, and two molecules of RK-682 were required to inhibit one molecule of VHR. Based on the structure-activity relationships for VHR inhibition by RK-682 derivatives, we constructed a binding model using molecular dynamics calculation. Based on this model, we designed and synthesized a novel dimeric derivative. As expected, the dimeric derivative showed increased inhibition of VHR, supporting our proposed mechanism of VHR inhibition by RK-682. CONCLUSION We have developed a novel inhibitor of VHR based on the results of kinetic analysis and docking simulation.

4-Isoavenaciolide covalently binds and inhibits VHR, a dual-specificity phosphatase

A potent inhibitor of a dual‐specificity protein phosphatase, VHR (vaccinia H1 related), was isolated during a screening of microbial metabolites. This inhibitor was identified as 4‐isoavenaciolide (4‐iA), and was determined to irreversibly inhibit VHR phosphatase activity with a 50% inhibitory concentration of 1.2 μM. Detailed tandem mass spectrometry analyses of proteolysed fragments revealed that two molecules of 4‐iA bound a molecule of VHR at the two different fragments: one containing the catalytic domain and the other containing the α6 helix positioned surface domain. As 4‐iA possesses a reactive exo‐methylene moiety, it is possible that 4‐iA inhibits VHR through the direct binding to the cysteine residue in the catalytic site (Cys124). Furthermore, 4‐iA inhibited dual‐specificity protein phosphatases and tyrosine phosphatases, but did not inhibit serine/threonine phosphatases. These results suggest that 4‐iA is a cysteine‐targeting inhibitor of protein phosphatases with a common HCX5RS/T motif in the catalytic site.

Structures of the dimeric and monomeric chromanones, gonytolides A-C, isolated from the fungus Gonytrichum sp. and their promoting activities of innate immune responses.

Innate immunity is the front line of self-defense against microbial infection. After searching for natural substances that regulate innate immunity using an ex vivo Drosophila culture system, we identified a novel dimeric chromanone, gonytolide A, as an innate immune promoter from the fungus Gonytrichum sp. along with gonytolides B and C. Gonytolide A also increased TNF-α-stimulated production of IL-8 in human umbilical vein endothelial cells.

Symmetry-dependent vibrational excitation in N 1s photoionization of N2 : Experiment and theory

We have measured the vibrational structures of the N 1s photoelectron mainline and satellites of the gaseous N2 molecule with the resolution better than 75 meV. The gerade and ungerade symmetries of the core-ionized (mainline) states are resolved energetically, and symmetry-dependent angular distributions for the satellite emission allow us to resolve the Sigma and Pi symmetries of the shake-up (satellite) states. Symmetry-adapted cluster-expansion configuration-interaction calculations of the potential energy curves for the mainline and satellite states along with a Franck-Condon analysis well reproduce the observed vibrational excitation of the bands, illustrating that the theoretical calculations well predict the symmetry-dependent geometry relaxation effects. The energies of both mainline states and satellite states, as well as the splitting between the mainline gerade and ungerade states, are also well reproduced by the calculation: the splitting between the satellite gerade and ungerade states is calculated to be smaller than the experimental detection limit.

DISSOCIATION DYNAMICS OF CORE-EXCITED BF3 PROBED BY THE PHOTOELECTRON-PHOTOION-PHOTOION COINCIDENCE

Abstract The present photoelectron—photoion—photoion coincidence measurement indicates that the dynamics of ion-pair production following the discrete resonance excitation B 1s → 2a″ 2 are completely different from those following the B 1s ionization and the direct double photoionization. The difference is attributed to deformation of the core-excited 2a″ 2 state with the help of ab initio SCF calculation.

KSRP/FUBP2 Is a Binding Protein of GO-Y086, a Cytotoxic Curcumin Analogue

Bis(arylmethylidene)acetone derivatives are an important class of curcumin analogues that exhibit various biological and pharmacological activities. We herein report that GO-Y086, a biotinylated bis(arylmethylidene)acetone, inhibits cancer cell growth. We also show that GO-Y086 specifically interacts with the nuclear protein KSRP/FUBP2 by covalent modification. GO-Y086 markedly suppresses the expression of the c-Myc protein, which plays an important role in cellular proliferation and whose expression is regulated by KSRP/FUBP2.

Revised structure and synthesis of celastramycin a, a potent innate immune suppressor.

After searching for natural substances that regulate innate immunity using the ex vivo Drosophila culture system, a benzoyl pyrrole-type compound, celastramycin A, was identified and isolated as a potent suppressor. By synthesizing the previously reported structure 1 and another benzoyl pyrrole-type compound 2 reported in a Japanese patent, the correct structure of celastramycin A was confirmed to be 2. Compound 2 suppressed the production of IL-8 (IC(50) 0.06 microg/mL) in human umbilical vein endothelial cells (HUVECs).

Auger-electron—photoion and photoion—photoion coincidence studies on ionic fragmentation of SF6 following the S L-shell excitation

Abstract Auger-electron—photoion coincidence study of SF 6 excited by 196 eV photons shows that the dications having two holes in the outer-valence bands dissociate into various ionic fragments, while those having one hole in the outer-valence and one hole in the inner-valence (F 2s) bands mostly dissociate into atomic ionic fragments F + and S + . Measurement of photoion—photoion coincidence efficiency curves in the S 2p threshold region reveals that not only the S 2p→t 2g and e g excitation above the S 2p threshold but also the S 2p→a 1g excitation below the S 2p threshold enhance the ion-pair formation, suggesting that a considerable part of the resonance-Auger-final states are subject to autoionization.

Threshold behaviour of the multiply-charged photoion yields near the Ar K edge

The authors have measured yield curves of the multiply-charged ions produced by the photoexcitation in the vicinity of the Ar K-shell ionization threshold using monochromatized undulator radiation and a time-of-flight mass spectrometer. The charge distribution of the multiply-charged Ar ions produced by the K-shell excitation suggests that both the electron in the outer shell and the excited Rydberg electron are shaken off with high probability during successive electronic relaxation processes. Post-collision interaction effects are also seen at the photon energies just above the K threshold. The fluorescence yield for the K hole is estimated to be 0.135+or-0.03 from the charge distribution above the K threshold.