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Present condition and activities of Jeddah Endoscopy Center managed in cooperation with Saudian and Japanese doctors are reported. Total number of patients examined are 1,183 cases; 73% of which were subjected to endoscopy and 27% were to fluoroscopy. With respect to the stomach diseases, gastric cancer and ulcer were found in 16% and 14.7%, respectively. On the other hand, high incidences of severe atrophic gastritis and haemorrhagic or erosive gastritis accounted totally 64.7% of all stomach diseases were noted. Out of 264 cases of duodenal diseases, duodenal ulcer was diagnosed in number of 202 cases (76%). The ratio between gastric and duodenal ulcer was, therefore, approximately 1:6. It was further noted that most of patients with esophagus cancer were found in males having the local habit of taking green tobacco. From the results obtained, discussions were made on the statistical differences of gastrointestinal diseases between Saudi Arabia and Japan. [ABSTRACT FROM AUTHOR]

Orexin neuropeptides have many physiological roles in the sleep-wake cycle, feeding behavior, reward demands, and stress responses by activating cognitive receptors, the orexin receptors (OX1R and OX2R), distributed in the brain. There are only subtle differences between OX1R and OX2R in the orthosteric site, which has hindered the rational development of subtype-selective antagonists. In this study, we utilized solution-state NMR to capture the structural plasticity of OX2R labeled with 13 CH 3 -ε-methionine in complex with antagonists. Mutations in the orthosteric site allosterically affected the intracellular tip of TM6. Ligand exchange experiments with the subtype-selective EMPA and the nonselective suvorexant identified three methionine residues that were substantially perturbed. The NMR spectra suggested that the suvorexant-bound state exhibited more structural plasticity than the EMPA-bound state, which has not been foreseen from the close similarity of their crystal structures, providing insights into dynamic features to be considered in understanding the ligand recognition mode., Competing Interests: Declaration of interests The authors declare no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Membraneless organelles formed via the self-assembly of intrinsically disordered proteins (IDPs) play a crucial role in regulating various physiological functions. Elucidating the mechanisms behind IDP self-assembly is of great interest not only from a biological perspective but also for understanding how amino acid mutations in IDPs contribute to the development of neurodegenerative diseases and other disorders. Currently, two proposed mechanisms explain IDP self-assembly: (1) the sticker-and-spacer framework, which considers amino acid residues as beads to simulate the intermolecular interactions, and (2) the cross-β hypothesis, which focuses on the β-sheet interactions between the molecular surfaces constructed by multiple residues. This review explores the advancement of new models that provide higher resolution insights into the IDP self-assembly mechanism based on new findings obtained from structural studies of IDPs., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.)

T cell intracellular antigen-1 (TIA-1) plays a central role in stress granule (SG) formation by self-assembly via the prion-like domain (PLD). In the TIA-1 PLD, amino acid mutations associated with neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) or Welander distal myopathy (WDM), have been identified. However, how these mutations affect PLD self-assembly properties has remained elusive. In this study, we uncovered the implicit pathogenic structures caused by the mutations. NMR analysis indicated that the dynamic structures of the PLD are synergistically determined by the physicochemical properties of amino acids in units of five residues. Molecular dynamics simulations and three-dimensional electron crystallography, together with biochemical assays, revealed that the WDM mutation E384K attenuated the sticky properties, whereas the ALS mutations P362L and A381T enhanced the self-assembly by inducing β-sheet interactions and highly condensed assembly, respectively. These results suggest that the P362L and A381T mutations increase the likelihood of irreversible amyloid fibrillization after phase-separated droplet formation, and this process may lead to pathogenicity.

Linear polyubiquitin chains regulate diverse signaling proteins, in which the chains adopt various conformations to recognize different target proteins. Thus, the structural plasticity of the chains plays an important role in controlling the binding events. Herein, paramagnetic NMR spectroscopy is employed to explore the conformational space sampled by linear diubiquitin, a minimal unit of linear polyubiquitin, in its free state. Rigorous analysis of the data suggests that, regarding the relative positions of the ubiquitin units, particular regions of conformational space are preferentially sampled by the molecule. By combining these results with further data collected for charge-reversal derivatives of linear diubiquitin, structural insights into the factors underlying the binding events of linear diubiquitin are obtained., (© 2021 Wiley-VCH GmbH.)

The eukaryotic translational initiation factor 4G (eIF4G) interacts with the cap-binding protein eIF4E through a consensus binding motif, Y(X) 4 LΦ (where X is any amino acid and Φ is a hydrophobic residue). 4E binding proteins (4E-BPs), which also contain a Y(X) 4 LΦ motif, regulate the eIF4E/eIF4G interaction. The non- or minimally-phosphorylated form of 4E-BP1 binds eIF4E, preventing eIF4E from interacting with eIF4G, thus inhibiting translation initiation. 4EGI-1, a small molecule inhibitor of the eIF4E/eIF4G interaction that is under investigation as a novel anti-cancer drug, has a dual activity; it disrupts the eIF4E/eIF4G interaction and stabilizes the binding of 4E-BP1 to eIF4E. Here, we report the complete backbone NMR resonance assignment of an unliganded 4E-BP1 fragment (4E-BP1 44-87 ). We also report the near complete backbone assignment of the same fragment in complex to eIF4E/m 7 GTP (excluding the assignment of the last C-terminus residue, D87). The chemical shift data constitute a prerequisite to understanding the mechanism of action of translation initiation inhibitors, including 4EGI-1, that modulate the eIF4E/4E-BP1 interaction.

The eIF4E-binding protein (4E-BP) is a phosphorylation-dependent regulator of protein synthesis. The nonphosphorylated or minimally phosphorylated form binds translation initiation factor 4E (eIF4E), preventing binding of eIF4G and the recruitment of the small ribosomal subunit. Signaling events stimulate serial phosphorylation of 4E-BP, primarily by mammalian target of rapamycin complex 1 (mTORC1) at residues T37/T46, followed by T70 and S65. Hyperphosphorylated 4E-BP dissociates from eIF4E, allowing eIF4E to interact with eIF4G and translation initiation to resume. Because overexpression of eIF4E is linked to cellular transformation, 4E-BP is a tumor suppressor, and up-regulation of its activity is a goal of interest for cancer therapy. A recently discovered small molecule, eIF4E/eIF4G interaction inhibitor 1 (4EGI-1), disrupts the eIF4E/eIF4G interaction and promotes binding of 4E-BP1 to eIF4E. Structures of 14- to 16-residue 4E-BP fragments bound to eIF4E contain the eIF4E consensus binding motif, (54)YXXXXLΦ(60) (motif 1) but lack known phosphorylation sites. We report here a 2.1-Å crystal structure of mouse eIF4E in complex with m(7)GTP and with a fragment of human 4E-BP1, extended C-terminally from the consensus-binding motif (4E-BP150-84). The extension, which includes a proline-turn-helix segment (motif 2) followed by a loop of irregular structure, reveals the location of two phosphorylation sites (S65 and T70). Our major finding is that the C-terminal extension (motif 3) is critical to 4E-BP1-mediated cell cycle arrest and that it partially overlaps with the binding site of 4EGI-1. The binding of 4E-BP1 and 4EGI-1 to eIF4E is therefore not mutually exclusive, and both ligands contribute to shift the equilibrium toward the inhibition of translation initiation.

To elucidate the effects of ring structure and a substituent on the glutathione peroxidase- (GPx-) like antioxidant activities of aliphatic selenides, series of water-soluble cyclic selenides with variable ring size and polar functional groups were synthesized, and their antioxidant activities were evaluated by NADPH-coupled assay using H2O2 and glutathione (GSH) in water and also by NMR spectroscopy using H2O2 and dithiothreitol (DTT(red)) in methanol. Strong correlations were found among the GPx-like activity in water, the second-order rate constants for the oxidation of the selenides, and the HOMO energy levels calculated in water. The results support the conclusion that the oxidation process is the rate-determining step of the catalytic cycle. On the other hand, such correlations were not obtained for the activity observed in methanol. The optimal ring size was determined to be five. The type of substituent (NH2 < OH < CO2H) and the number can also control the activity, whereas the stereoconfiguration has only marginal effects on the activity in water. In methanol, however, the activity rank could not be explained by the simple scenarios applicable in water.

Multiple covalent modifications on a histone tail are often recognized by linked histone reader modules. UHRF1 [ubiquitin-like, containing plant homeodomain (PHD) and really interesting new gene (RING) finger domains 1], an essential factor for maintenance of DNA methylation, contains linked two-histone reader modules, a tandem Tudor domain and a PHD finger, tethered by a 17-aa linker, and has been implicated to link histone modifications and DNA methylation. Here, we present the crystal structure of the linked histone reader modules of UHRF1 in complex with the amino-terminal tail of histone H3. Our structural and biochemical data provide the basis for combinatorial readout of unmodified Arg-2 (H3-R2) and methylated Lys-9 (H3-K9) by the tandem tudor domain and the PHD finger. The structure reveals that the intermodule linker plays an essential role in the formation of a histone H3-binding hole between the reader modules by making extended contacts with the tandem tudor domain. The histone H3 tail fits into the hole by adopting a compact fold harboring a central helix, which allows both of the reader modules to simultaneously recognize the modification states at H3-R2 and H3-K9. Our data also suggest that phosphorylation of a linker residue can modulate the relative position of the reader modules, thereby altering the histone H3-binding mode. This finding implies that the linker region plays a role as a functional switch of UHRF1 involved in multiple regulatory pathways such as maintenance of DNA methylation and transcriptional repression.

Ubiquitin is a post-translational modifier that is involved in cellular functions through its covalent attachment to target proteins. Ubiquitin can also be conjugated to itself at seven lysine residues and at its amino terminus to form eight linkage-specific polyubiquitin chains for individual cellular processes. The Lys63-linked polyubiquitin chain is recognized by tandem ubiquitin-interacting motifs (tUIMs) of Rap80 for the regulation of DNA repair. To understand the recognition mechanism between the Lys63-linked diubiquitin (K63-Ub(2)) and the tUIMs in solution, we determined the solution structure of the K63-Ub(2):tUIMs complex by using NOE restraints and RDC data derived from NMR spectroscopy. The structure showed that the tUIMs adopts a nearly straight and single continuous α-helix, and the two ubiquitin units of the K63-Ub(2) separately bind to each UIM motif. The interfaces are formed between Ile44-centered patches of the two ubiquitin units and the hydrophobic residues of the tUIMs. We also showed that the linker region between the two UIM motifs possesses a random-coil conformation in the free state, but undergoes the coil-to-helix transition upon complex formation, which simultaneously fixes the relative position of ubiquitin subunits. These data suggest that the relative position of ubiquitin subunits in the K63-Ub(2):tUIMs complex is essential for linkage-specific binding of Rap80 tUIMs.

Post-translational modification by small ubiquitin-like modifier (SUMO) provides an important regulatory mechanism in diverse cellular processes. Modification of SUMO has been shown to target proteins involved in systems ranging from DNA repair pathways to the ubiquitin-proteasome degradation system by the action of SUMO-targeted ubiquitin ligases (STUbLs). STUbLs recognize target proteins modified with a poly-SUMO chain through their SUMO-interacting motifs (SIMs). STUbLs are also associated with RENi family proteins, which commonly have two SUMO-like domains (SLD1 and SLD2) at their C terminus. We have determined the crystal structures of SLD2 of mouse RENi protein, Nip45, in a free form and in complex with a mouse E2 sumoylation enzyme, Ubc9. While Nip45 SLD2 shares a beta-grasp fold with SUMO, the SIM interaction surface conserved in SUMO paralogues does not exist in SLD2. Biochemical data indicates that neither tandem SLDs or SLD2 of Nip45 bind to either tandem SIMs from either mouse STUbL, RNF4 or to those from SUMO-binding proteins, whose interactions with SUMO have been well characterized. On the other hand, Nip45 SLD2 binds to Ubc9 in an almost identical manner to that of SUMO and thereby inhibits elongation of poly-SUMO chains. This finding highlights a possible role of the RENi proteins in the modulation of Ubc9-mediated poly-SUMO formation., (2009 Wiley-Liss, Inc.)

Post-translational modification by small ubiquitin-like modifier (SUMO) proteins has been implicated in the regulation of a variety of cellular events. The functions of sumoylation are often mediated by downstream effector proteins harboring SUMO-interacting motifs (SIMs) that are composed of a hydrophobic core and a stretch of acidic residues. MBD1-containing chromatin-associated factor 1 (MCAF1), a transcription repressor, interacts with SUMO-2/3 and SUMO-1, with a preference for SUMO-2/3. We used NMR spectroscopy to solve the solution structure of the SIM of MCAF1 bound to SUMO-3. The hydrophobic core of the SIM forms a parallel beta-sheet pairing with strand beta2 of SUMO-3, whereas its C-terminal acidic stretch seems to mediate electrostatic interactions with a surface area formed by basic residues of SUMO-3. The significance of these electrostatic interactions was shown by mutations of both SUMO-3 and MCAF1. The present structural and biochemical data suggest that the acidic stretch of the SIM of MCAF1 plays an important role in the binding to SUMO-3.

Accumulating evidence indicates that neutrophils are crucially involved in the pathogenesis of inflammatory bowel diseases and rheumatoid arthritis. We therefore investigated the effect of sulfasalazine (SSZ), which is widely used in the treatment of these diseases, on neutrophil apoptosis in vitro. The apoptosis of neutrophils was determined by morphology, a DNA histogram of propidium iodide-stained nuclei, and DNA fragmentation. SSZ rapidly accelerated the rate of spontaneous neutrophil apoptosis within clinically relevant concentrations. This effect is unique to neutrophils because other types of leukocytes and a number of leukocyte cell lines are resistant to SSZ. Neutrophil apoptosis caused by SSZ was abrogated by a tyrosine kinase inhibitor, a protein kinase A inhibitor, and antioxidants. The subsequent results provided pharmacological evidence that the phosphorylation of tyrosine kinase and protein kinase A and generation of reactive oxygen species are involved in SSZ-mediated neutrophil apoptosis. These data suggest that SSZ-induced neutrophil apoptosis may account, in part, for the clinical benefits of SSZ on inflammatory bowel diseases and rheumatoid arthritis.

Various receptors coupled to the heterotrimeric guanine nucleotide-binding protein Gq/11 stimulate formation of inositol-1,4,5-trisphosphate (IP3). Activation of these receptors also induces protein tyrosine phosphorylation. Formation of IP3 in response to stimulated receptors that couple to Gq/11 was blocked by protein tyrosine kinase inhibitors. These inhibitors appeared to act before activation of Gq/11. Moreover, stimulation of receptors coupled to Gq/11 induced phosphorylation on a tyrosine residue (Tyr356) of the Galphaq/11 subunit, and this tyrosine phosphorylation event was essential for Gq/11 activation. Tyrosine phosphorylation of Galphaq/11 induced changes in its interaction with receptors. Therefore, tyrosine phosphorylation of Galphaq/11 appears to regulate the activation of Gq/11 protein.

Liver disease in 193 patients (17 male and 176 female) with systemic lupus erythematosus (SLE) at Kawasaki Municipal Hospital were analyzed. Abnormal transaminase levels were found in 78 case (40.4%). Among them, there were 35 patients whose liver disease were identified. There were 12 patients whom no cause could be found other than SLE. Other liver disease were as follows: fatty liver in 9 cases, virus infection in 5 cases, gall stone and/or cholecystitis in 3 cases, drug allergy in 2 cases, autoimmune hepatitis 2 cases, primary biliary cirrhoses in 1 case. Liver disease with systemic lupus erythematosus was frequent, but there was no severe case.

A 74-year-old female patient with cutaneous ulcerations and typical dermatomyositis (DM) skin rash had no muscle disease for a 1-year and 5 months period. Histological examination of the skin ulceration indicated vascular occlusion without cellular infiltration. Cutaneous ulceration is a very rare manifestation of adult-onset DM patients without inflammatory myopathy.

We report on two cases of rheumatoid arthritis (RA) presenting autoimmune hepatic diseases. The first patient, who had been diagnosed as RA at the age of 63, was hospitalized in order to undergo surgery for total left knee replacement at the age of 69. She acquired acute serum hepatitis as a result of blood transfusion she received during the operation. Five years later, she visited our clinic suffering from polyarthritis. She was found to have hyper-alkaline phosphatase (ALP) and hyper rGTP, but no AMA. The second patient, a 60-year-old female whose onset of RA was at the age of 45, complained of general fatigue, and was admitted to the hospital because of persistent liver dysfunction. When corticosteroid was administered to these patients, ALP and rGTP levels in the first case, and AST and ALT levels in the second case were reduced to values in the normal range. ANA in the first case continued to register negative, but ANA in the second case became positive after the patient developed acute hepatitis. Both patients were found to have anti-p25 triplet liver/kidney microsome antibody. We discuss the clinical significance of this antibody.

Changes of distribution of immunoreactive gastrin (IRG) and molecular forms of intra-tissue gastrin in the growth course of rats were examined. The results obtained were as follows; 1) IRG concentrations and G cell counts were extremely low in the fetal antral mucosa. However, a gradual increase of the above was observed during the neonatal suckling period, accompanied by a rapid increase at the commencement of feeding. 2) IRG concentrations in the duodenal mucosa of the fetal and neonatal period were markedly higher than that of adult rat. 3) Jejunal IRG concentration was negligible in the fetal period. The value obtained from the postnatal rats was equal to or higher than that of adult rat. 4) The major form of antral gastrin was G-17 throughout the fetal and adult age. No qualitative change of antral IRG in the growth course of rats was seen. 5) The major form of the duodeno-jejunal mucosa was G-17 in the fetal period and thereafter G-34 increased gradually in the growth course of rats. These results suggested that, (1) suckling and feeding appeared to be a trigger of the production and release of antral gastrin in the growth course of rats. (2) In the initial stage of the growth, G cells distributed in the duodeno-jejunal mucosa as well as in the antral mucosa may participated in the production and release mechanism of gastrin.

Studies were carried out in a case of achalasia. Administration of secretin caused relaxation of the spastic condition of LES, and high levels of serum gastrin and lower levels of plasma secretin are suggested to be related with the abnormally spastic condition of LES in the patient.

Serum gastrin concentration became became detectable in rats at one week after birth (56 pg/ml), and a rapid rise to 198 pg/ml was seen at two weeks after birth. Gradual decreases were seen again at three weeks and four weeks, and thereafter it attained the adult level of 132 +/- 17.6 pg/ml. In regards to the gastrin-like immunoreactivity (GLI) in the gastrointestinal mucosa during the fetal period, the values were extremely low even in the antral mucosa. However, the GLI showed an increase during the neonatal suckling period, and was accompanied by a remarkable increase at the commencement of feeding. This GLI coincided with so-called little gastrin, and while an increase accompanied by the development of growth was seen, no qualitative changes were evident. GLI values were high in the duodenal mucosa followed by the antrum, and positive evidence was also seen in the corpus of the stomach and jejunum. High values of GLI in the mucosae were gradually seen at two weeks after birth coinciding with the rise in serum gastrin levels, and the significance of the increases was discussed from the anlge of the trophic effect of gastrin.