The mammalian endoplasmic reticulum (ER) harbors more than 20 members of the protein disulfide isomerase (PDI) family that act to maintain proteostasis. Herein, we developed an in vitro system for ...directly monitoring PDI- or ERp46-catalyzed disulfide bond formation in ribosome-associated nascent chains of human serum albumin. The results indicated that ERp46 more efficiently introduced disulfide bonds into nascent chains with a short segment exposed outside the ribosome exit site than PDI. Single-molecule analysis by high-speed atomic force microscopy further revealed that PDI binds nascent chains persistently, forming a stable face-to-face homodimer, whereas ERp46 binds for a shorter time in monomeric form, indicating their different mechanisms for substrate recognition and disulfide bond introduction. Thus, ERp46 serves as a more potent disulfide introducer especially during the early stages of translation, whereas PDI can catalyze disulfide formation when longer nascent chains emerge out from ribosome.
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•We developed an in vitro system for monitoring nascent-chain disulfide formation•High-speed AFM visualized PDI and ERp46 molecules acting on nascent chains•PDI persistently holds nascent chains via dimerization for disulfide introduction•ERp46 rapidly introduces disulfide bonds to nascent chains via short-time binding
Cell Biology; Molecular Biology; Structural Biology
P5, also known as PDIA6, is a PDI family member involved in the ER quality control. Here, we revealed that P5 dimerizes via a unique adhesive motif contained in the N-terminal thioredoxin-like ...domain. Unlike conventional leucine zipper motifs with leucine residues every two helical turns on ∼30-residue parallel α helices, this adhesive motif includes periodic repeats of leucine/valine residues at the third or fourth position spanning five helical turns on 15-residue anti-parallel α helices. The P5 dimerization interface is further stabilized by several reciprocal salt bridges and C-capping interactions between protomers. A monomeric P5 mutant with the impaired adhesive motif showed structural instability and local unfolding, and behaved as aberrant proteins that induce the ER stress response. Disassembly of P5 to monomers compromised its ability to inactivate IRE1α via intermolecular disulfide bond reduction and its Ca2+-dependent regulation of chaperone function in vitro. Thus, the leucine-valine adhesive motif supports structure and function of P5.
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•P5 dimerizes via a unique leucine-valine adhesive motif in the first Trx-like domain•The adhesive motif is radically different from conventional coiled-coil motifs•The dimeric structure serves to promote P5-mediated inactivation of IRE1α•Ca2+-binding regions and Ca2+-dependent functional regulation were clarified for P5
Using SAXS and X-ray crystallography, Okumura et al. determined the structure of a protein disulfide isomerase P5, in which the N-terminal thioredoxin-like domain dimerizes via a unique leucine-valine adhesive motif. A monomeric P5 mutant displayed structural instability and compromised functions, indicating the structural and functional essentiality of this motif.
Endoscopic submucosal dissection(ESD) has become widely accepted as a standard method of treatment for superficial gastrointestinal neoplasms because it enables en block resection even for large ...lesions or fibrotic lesions with minimal invasiveness, and decreases the local recurrence rate. Moreover, specimens resected in an en block fashion enable accurate histological assessment. Taking these factors into consideration, ESD seems to be more advantageous than conventional endoscopic mucosal resection(EMR), but the associated risks of perioperative adverse events are higher than in EMR. Bleeding after ESD is the most frequent among these adverse events. Although post-ESD bleeding can be controlled by endoscopic hemostasis in most cases, it may lead to serious conditions including hemorrhagic shock. Even with preventive methods including administration of acid secretion inhibitors and preventive hemostasis, post-ESD bleeding cannot be completely prevented. In addition high-risk cases for post-ESD bleeding, which include cases with the use of antithrombotic agents or which require large resection, are increasing. Although there have been many reports about associated risk factors and methods of preventing post-ESD bleeding, many issues remain unsolved. Therefore, in this review, we have overviewed risk factors and methods of preventing post-ESD bleeding from previous studies. Endoscopists should have sufficient knowledge of these risk factors and preventive methods when performing ESD.
AIM:To evaluate the discomfort associated with esophagogastroduodenoscopy(EGD)using an ultrathin endoscope through different insertion routes.METHODS:This study(January 2012-March 2013)included 1971 ...consecutive patientsmale/female(M/F),1158/813,57.5±11.9 yearswho visited a single institute for annual health checkups.Transnasal EGD was performed in 1394 patients and transoral EGD in 577.EGD-associated discomfort was assessed using a visual analog scale score(VAS score:0-10).RESULTS:Multivariate analysis revealed gender(M vs F:4.02±2.15 vs 5.06±2.43)as the only independent predictor of the VAS score in 180 patients who underwent EGD for the first time;whereas it revealed gender(M vs F 3.60±2.20 vs 4.84±2.37),operator,age group(A:<39 years;B:40-49 years;C:50-59years;D:60-69 years;E:>70 years;A/B/C/D/E:4.99±2.32/4.34±2.49/4.19±2.31/3.99±2.27/3.63±2.31),and type of insertion as independent predictors in the remaining patients.Subanalysis for gender,age group,and insertion route revealed that the VAS score decreased with age regardless of gender and insertion route,was high in female patients regardless of age and insertion route,and was low in males aged over60 years who underwent transoral insertion.CONCLUSION:Although comprehensive analysis revealed that the insertion route may not be an independent predictor of the VAS score,transoral insertion may reduce EGD-associated discomfort in elderly patients.
From the viewpoints of environmental protection, support for the aged and ensuring the right to mobility, there is a need to develop a new type of mobility vehicle that provides more effective ...transportation. The authors propose an inverted pendulum vehicle with pedals as one of the forms of personal mobility vehicles (PMVs). In this paper, the steering performance of the inverted pendulum vehicle with pedals is discussed based on experiments on a prototype. From the experimental results, it was confirmed that the errors from the five subjects for the target trajectory and the five-grade evaluation of the maneuverability were similar. Finally, we created an inverted pendulum vehicle with pedals to which was added a reaction actuator for the steering system. From the experimental results, it was found that setting appropriate feedback gains for the handle steering angle and its rate of rotation, which control the right and left wheel driving torques, resulted in greatly improved maneuverability.
Gastroesophageal reflux disease (GERD) is a very common disorder worldwide, comprised of reflux esophagitis (RE) and non-erosive reflux disease (NERD). As more than half of GERD patients are ...classified into the NERD group, precise evaluation of bothersome epigastric symptoms is essential. Nevertheless, compared with many reports targeting endoscopic reflux esophagitis, large-scale studies focusing on GERD symptoms have been very scarce.
To elucidate lifestyle factors affecting GERD symptoms, 19,864 healthy adults in Japan were analyzed. Sub-analyses of 371 proton pump inhibitor (PPI) users and 539 histamine H₂-receptor antagonist (H₂RA) users were also performed. Using the FSSG (Frequency Scale for the Symptoms of GERD) score as a response variable, 25 lifestyle-related factors were univariately evaluated by Student's t-test or Pearson's correlation coefficient, and were further analyzed with multiple linear regression modelling.
Average FSSG scores were 4.8 ± 5.2 for total subjects, 9.0 ± 7.3 for PPI users, and 8.2 ± 6.6 for H₂RA users. Among the total population, positively correlated factors and standardized coefficients (β) for FSSG scores are inadequate sleep (β = 0.158), digestive drug users (β = 0.0972 for PPI, β = 0.0903 for H₂RA, and β = 0.104 for others), increased body weight in adulthood (β = 0.081), dinner just before bedtime (β = 0.061), the habit of midnight snack (β = 0.055), lower body mass index (β = 0.054), NSAID users (β = 0.051), female gender (β = 0.048), lack of breakfast (β = 0.045), lack of physical exercise (β = 0.035), younger age (β = 0.033), antihyperglycemic agents non-users (β = 0.026), the habit of quick eating (β = 0.025), alcohol drinking (β = 0.025), history of gastrectomy (β = 0.024), history of cardiovascular disease (β = 0.020), and smoking (β = 0.018). Positively correlated factors for PPI users are female gender (β = 0.198), inadequate sleep (β = 0.150), lack of breakfast (β = 0.146), antihypertensive agent non-users (β = 0.134), and dinner just before bedtime (β = 0.129), whereas those for H₂RA users are inadequate sleep (β = 0.248), habit of midnight snack (β = 0.160), anticoagulants non-users (β = 0.106), and antihypertensive agents non-users (β = 0.095).
Among many lifestyle-related factors correlated with GERD symptoms, poor quality of sleep and irregular dietary habits are strong risk factors for high FSSG scores. At present, usual dose of PPI or H₂RA in Japan cannot fully relieve GERD symptoms.
Background The prevention of bleeding after endoscopic submucosal dissection (ESD) for gastric neoplasms is still an important problem. Objective To investigate the efficacy and safety of a shielding ...method that uses polyglycolic acid (PGA) sheets and fibrin glue to prevent post-ESD bleeding in high-risk patients. Design A nonrandomized trial with historical control subjects. Setting A single academic hospital in Japan. Patients From July 2013 to February 2014, 45 ESD-induced ulcers in 41 patients with a high risk of bleeding were enrolled in a study group. Forty-one consecutive ESD-induced ulcers in 37 control subjects with a high risk of bleeding were treated in 2013 before the first enrollment. Interventions We placed PGA sheets on the mucosal defect and fixed with fibrin glue in the study group. Main Outcome Measurements The post-ESD bleeding rate. Results The post-ESD bleeding occurred at a rate of 6.7% in the study group (3/45 lesions) and 22.0% in the historical control group (9/41 lesions). There was a significant difference in the post-ESD bleeding rate between the 2 groups ( P = .041). Limitations A nonrandomized trial with historical control subjects; a single-center analysis; small sample size. Conclusions The endoscopic tissue shielding method with PGA sheets and fibrin glue appears to be promising for the prevention of post-ESD bleeding. (Clinical trial registration number: UMIN000011058 .)
Despite the marked increase of diverticulosis, its risk factors have not been adequately elucidated. We therefore aim to identify significantly associated factors with diverticulosis. We also aim to ...investigate the present state of diverticulosis in Japan.
We reviewed the medical records from 1990 to 2010 that included the data of consecutive 62,503 asymptomatic colonoscopy examinees from the general population in Japan. Most recent 3,327 examinees were analyzed with 16 background factors.
Among the 62,503 subjects (47,325 men and 15,178 women; 52.1 ± 9.2 years old), diverticulosis was detected in 11,771 subjects (18.8%; 10,023 men and 1,748 women). The incidences of diverticulosis in 1990-2000 and 2001-2010 were respectively 13.0% (3,771 of 29,071) and 23.9% (8,000 of 33,432): the latter was much higher than the former in all age groups and for both genders. Considering the anatomical locations of colorectal diverticula, left-sided ones have markedly increased with age but not significantly changed with times. Univariate analyses of the 3,327 subjects showed significant association of diverticulosis with four basic factors (age, sex, body mass index, blood pressure), three life style-related factor (smoking, drinking, severe weight increase in adulthood), and two blood test values (triglyceride, HbA1c). The multiple logistic analysis calculating standardized coefficients (β) and odds ratio (OR) demonstrated that age (β = 0.217-0.674, OR = 1.24-1.96), male gender (β = 0.185, OR = 1.20), smoking (β = 0.142-0.200, OR = 1.15-1.22), severe weight increase in adulthood (β = 0.153, OR = 1.17), HbA1c (β = 0.136, OR = 1.15), drinking (β = 0.109, OR = 1.11), and serum triglyceride (β = 0.098, OR = 1.10) showed significantly positive association with diverticulosis whereas body mass index and blood pressure did not.
The large-scale data of asymptomatic colonoscopy examinees from the general population from 1990 to 2010 indicated that the prevalence of diverticulosis is still increasing in Japan. Age, male gender, smoking, severe weight increase in adulthood, serum HbA1c, drinking, and serum triglyceride showed significant positive association with diverticulosis.
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