Autophagy adaptors mediate Parkin-dependent mitophagy by forming sheet-like liquid condensates.

During PINK1- and Parkin-mediated mitophagy, autophagy adaptors are recruited to damaged mitochondria to promote their selective degradation. Autophagy adaptors such as optineurin (OPTN) and NDP52 facilitate mitophagy by recruiting the autophagy-initiation machinery, and assisting engulfment of damaged mitochondria through binding to ubiquitinated mitochondrial proteins and autophagosomal ATG8 family proteins. Here, we demonstrate that OPTN and NDP52 form sheet-like phase-separated condensates with liquid-like properties on the surface of ubiquitinated mitochondria. The dynamic and liquid-like nature of OPTN condensates is important for mitophagy activity, because reducing the fluidity of OPTN-ubiquitin condensates suppresses the recruitment of ATG9 vesicles and impairs mitophagy. Based on these results, we propose a dynamic liquid-like, rather than a stoichiometric, model of autophagy adaptors to explain the interactions between autophagic membranes (i.e., ATG9 vesicles and isolation membranes) and mitochondrial membranes during Parkin-mediated mitophagy. This model underscores the importance of liquid-liquid phase separation in facilitating membrane-membrane contacts, likely through the generation of capillary forces.

Identity of the numerous bloodstains at the murder scene: molecular identification of fly artifacts and fly species by CO1 analysis.

Crime scenes may contain insect artifacts as well as samples of human origin. While the presence of insects can be important evidence in forensic medicine and forensic entomology, the insect artifacts sometimes interfere with the interpretation of bloodstain pattern analysis (BPA) which can be critical for accurate crime reconstruction. Fly artifacts are especially complicated to distinguish from true bloodstains. Indeed, we encountered a murder scene with numerous bloodstains inconsistent with the cause of death and had trouble interpreting them. The morphological method has been developed to distinguish them, but this method has to rely on the analyst's experience and opinion. This study aims not only to distinguish fly artifacts from true bloodstains but also to identify fly species by detecting fly DNA in small amounts of bloodstains at the scenes. Melt curve analysis of real-time PCR (qPCR) targeting cytochrome c oxidase subunit 1 (CO1) of mitochondrial DNA (mtDNA) was able to detect fly DNA in bloodstains from a murder scene. The fly DNA was sequenced from the qPCR product, and the fly species were identified by BLAST search. Fluorescence-labeled specific primers for four species of necrophagous flies were designed based on the sequences of the CO1 region, and differences in the length of the amplification products were used to identify fly species from trace amounts of fly DNA in the artifacts.

Covered versus uncovered metal stent for endoscopic drainage of a malignant distal biliary obstruction: Meta-analysis.

OBJECTIVES: The role of a covered vs. an uncovered self-expandable metal stent (SEMS) for malignant distal biliary obstruction (MDBO) is not clear. This meta-analysis compared the efficacy of covered vs. uncovered SEMS for patients with MDBO after endoscopic insertion. METHODS: A systematic meta-analysis of all relevant articles listed in PubMed, the Cochrane Library, and Google Scholar databases was performed. Fixed effects or random effects models were used to investigate pooled effects with 95% confidence intervals (CIs). RESULTS: The meta-analysis included 2358 patients from 12 eligible studies. Time to recurrent biliary obstruction (RBO) was significantly longer for covered SEMS (mean difference, 45.51 days; 95% CI 11.79-79.24). Although there was no significant difference in the RBO rate, subgroup analysis in pancreatic cancer occupying more than 90% (PC) revealed that the RBO rates were significantly lower for covered SEMS (odds ratio [OR] 0.43, 95% CI 0.25-0.74). Stent migration, sludge formation, and overgrowth were significantly more common with a covered SEMS (OR 7.92, 95% CI 4.01-15.64; OR 3.25, 95% CI 1.89-5.59; OR 2.03, 95% CI 1.20-3.43, respectively). The rate of ingrowth was significantly lower for covered SEMS. There was no significant difference in total procedure-related adverse events between the two types of SEMS. CONCLUSIONS: A covered SEMS is superior to an uncovered SEMS with respect to prevention of RBO in patients with MDBO, particularly those caused by PC.

Uncovered versus covered metallic stents for the management of unresectable malignant distal biliary obstruction: a randomized multicenter trial.

OBJECTIVE: The treatment result of the uncovered metallic stent (uncovered MS) and covered metallic stent (covered MS) for unresectable malignant distal biliary obstruction is controversial. This time, we conducted this study to compare the efficacies and complication rates of uncovered MS and covered MS in unresectable malignant distal biliary obstructions at a prospective randomized multicenter trial. MATERIALS AND METHODS: From April 2014 to September 2018, patients with unresectable malignant distal biliary obstruction were randomly assigned to 2 groups: the uncovered MS group and the covered MS group. RESULTS: 92 treatment results patients were discussed. 48 patients were assigned to the uncovered MS group and 44 cases were assigned to the covered MS group. Both groups showed a drainage effect. No significant difference was found in the drainage effect between the 2 groups. The number of stent occlusion was significantly greater (p = .0467) in uncovered MS (43.8%) comparing with those in covered MS (22.7%). As the cause of stent occlusion, tumor ingrowth was significantly greater (p < .001) in the uncovered MS group (35.4%) than in the covered MS group (2.3%). The median stent patency period was significantly longer (p = .0112) in the covered MS group (455 days) than that of the uncovered MS group (301 days). A significant difference in the median survival period was not found between the 2 groups. CONCLUSIONS: Covered MS showed the possibility of extending the stent patency period by suppressing tumor ingrowth more than uncovered MS does. The UMIN Clinical Trial Registry number is UMIN000015093.

Modeling the functions of condensin in chromosome shaping and segregation.

The mechanistic details underlying the assembly of rod-shaped chromosomes during mitosis and how they segregate from each other to act as individually mobile units remain largely unknown. Here, we construct a coarse-grained physical model of chromosomal DNA and condensins, a class of large protein complexes that plays key roles in these processes. We assume that condensins have two molecular activities: consecutive loop formation in DNA and inter-condensin attractions. Our simulation demonstrates that both of these activities and their balancing acts are essential for the efficient shaping and segregation of mitotic chromosomes. Our results also demonstrate that the shaping and segregation processes are strongly correlated, implying their mechanistic coupling during mitotic chromosome assembly. Our results highlight the functional importance of inter-condensin attractions in chromosome shaping and segregation.

Transpancreatic precut papillotomy versus double-guidewire technique in difficult biliary cannulation: prospective randomized study.

BACKGROUND AND STUDY AIMS: Difficult biliary cannulation and unintentional pancreatic duct cannulation are thought to be important contributors to pancreatitis occurring after endoscopic retrograde cholangiopancreatography. Our aim was to compare and evaluate the rates of success and complications of transpancreatic precut papillotomy (TPPP) and the double-guidewire technique (DGT), both with prophylactic pancreatic stenting. PATIENTS AND METHODS: From April 2011 to March 2014, patients with difficult biliary cannulation, in whom we planned to first position a guidewire in the pancreatic duct, were enrolled, and 68 patients were prospectively randomly allocated to two groups (TPPP 34, DGT 34). We evaluated the rates of success and complications for each group. RESULTS: TPPP had a significantly higher success rate (94.1 %) than DGT (58.8 %). The rate of post-ERCP pancreatitis was 2.9 % in both groups. There was no significant difference between the two groups in the overall rate of complications related to cannulation. CONCLUSION : If biliary cannulation cannot be achieved, TPPP should be selected first after unintentional pancreatic duct cannulation.

Multicenter study of endoscopic preoperative biliary drainage for malignant hilar biliary obstruction: E-POD hilar study.

BACKGROUND AND AIM: Endoscopic nasobiliary drainage (ENBD) is often recommended in preoperative biliary drainage (PBD) for hilar malignant biliary obstruction (MBO), but endoscopic biliary stent (EBS) is also used in the clinical practice. We conducted this large-scale multicenter study to compare ENBD and EBS in this setting. METHODS: A total of 374 cases undergoing PBD including 281 ENBD and 76 EBS for hilar MBO in 29 centers were retrospectively studied. RESULTS: Extrahepatic cholangiocarcinoma (ECC) accounted for 69.8% and Bismuth-Corlette classification was III or more in 58.8% of the study population. Endoscopic PBD was technically successful in 94.6%, and adverse event rate was 21.9%. The rate of post-endoscopic retrograde cholangiopancreatography pancreatitis was 16.0%, and non-endoscopic sphincterotomy was the only risk factor (odds ratio [OR] 2.51). Preoperative re-intervention was performed in 61.5%: planned re-interventions in 48.4% and unplanned re-interventions in 31.0%. Percutaneous transhepatic biliary drainage was placed in 6.4% at the time of surgery. The risk factors for unplanned procedures were ECC (OR 2.64) and total bilirubin ≥ 10 mg/dL (OR 2.18). In surgically resected cases, prognostic factors were ECC (hazard ratio [HR] 0.57), predraiange magnetic resonance cholangiopancreatography (HR 1.62) and unplanned re-interventions (HR 1.81). EBS was not associated with increased adverse events, unplanned re-interventions, or a poor prognosis. CONCLUSIONS: Our retrospective analysis did not demonstrate the advantage of ENBD over EBS as the initial PBD for resectable hilar MBO. Although the technical success rate of endoscopic PBD was high, its re-intervention rate was not negligible, and unplanned re-intervention was associated with a poor prognosis in resected hilar MBO.

Secondary ion yields for vacuum-type electrospray droplet beams measured with a triple focus time-of-flight analyzer.

RATIONALE: We previously developed a massive cluster ion beam gun for secondary ion mass spectrometry (SIMS) in which the primary beam source is a vacuum electrospray. The secondary ion yields produced by this method had not yet been measured with a commercial time-of-flight (TOF) secondary ion mass spectrometer, and the ionization performance was unknown. METHODS: A vacuum-type electrospray droplet ion gun was connected to a triple-focus TOF analyzer. The flight time of the secondary ions was measured using a sample-bias pulsing method, because a short pulse of the electrospray droplet beam could not be obtained. The secondary ion yields of an amino acid sample produced by the electrospray droplet beams and atomic Ga ion beams were compared. RESULTS: TOF secondary ion spectra were measured for the amino acid and peptide samples with a mass resolution of ~500 using the sample-bias pulsing method. The secondary ion yield of the amino acid sample produced with the 10 kV vacuum-type electrospray droplet beams was much higher than that produced by 10 kV Ga ion beams. In addition, the secondary ion yields for the peptide sample and amino acid samples were almost similar. CONCLUSIONS: This is the first report on secondary ion yields produced with vacuum-type electrospray droplet ion beams and measured with a semi-commercial TOF analyzer. The enhancement of secondary ion yields, in particular for relatively high-mass molecules, would be very useful in the SIMS analysis of a wide variety of biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

Old age is associated with increased severity of complications in endoscopic biliary stone removal.

BACKGROUND AND AIM: Various techniques are required in endoscopic biliary stone removal. Because the presence of biliary stones is a benign disease, it is essential to minimize procedure-related complications. Having a sound knowledge of the risk factors can help reduce the number and severity of complications. We determined the risk factors for complications in patients undergoing endoscopic biliary stone removal. METHODS: This was a retrospective observational cohort study. We analyzed 743 consecutive patients with biliary stones who were treated with endoscopic retrograde cholangiopancreatography and identified the independent risk factors for complications. RESULTS: Complications occurred in 66 patients (8.9%). Pancreatitis occurred in 26 patients (3.5%), cholangitis in 16 (2.2%), bleeding in 12 (1.6%) and other in 12 (1.6%). Independent risk factors for overall complications were multiple biliary stones (P = 0.0480) and anti-thrombotic drugs (P = 0.0186).Independent risk factors for moderate or severe complications were old age (P = 0.0201), multiple biliary stones (P = 0.0300), anti-thrombotic drugs (P = 0.0131), and cirrhosis of the liver (P = 0.0013). The respective risk factors for pancreatitis, cholangitis, and bleeding were precut technique (P = 0.0005), endoscopic mechanical lithotripsy (P = 0.0421), and both anti-thrombotic drugs (P = 0.0228) and cirrhosis of the liver (P = 0.0115). CONCLUSIONS: Old age was associated with a similar complication rate to younger age but increased the severity of complications following endoscopic biliary stone removal. Improved awareness of the severity of complications may be of benefit during periprocedural management. Further studies are warranted.

Preoperative assessment of longitudinal extension of cholangiocarcinoma with peroral video-cholangioscopy: a prospective study.

BACKGROUND AND AIM: Preoperative assessment of longitudinal extension of cholangiocarcinoma (CCA) is essential for making decisions concerning surgical resection and selecting operative procedures. We evaluated the accuracy of peroral video-cholangioscopy (PVCS) in diagnosing longitudinal extension of CCA. METHODS: Patients with CCA who underwent preoperative PVCS were considered for this study. We evaluated the accuracy of PVCS in diagnosing longitudinal extension of perihilar cholangiocarcinoma (PCCA) and distal extrahepatic cholangiocarcinoma (DCCA) to the secondary biliary radicles and confluence of the hepatic ducts, respectively, on the hepatic side and to the intrapancreatic common bile duct on the papillary side. Diagnostic accuracy was determined by comparing the results with those of histopathological analyses of surgical specimens. RESULTS: Forty-three consecutive patients were enrolled. The cholangioscope could not be advanced into the hepatic side in eight of the 25 patients with PCCA and in five of the 18 patients with DCCA. The accuracy of PVCS in diagnosing longitudinal extension of CCA on the hepatic and papillary sides was 82.4% and 92.0%, respectively, in patients with PCCA and 92.3% and 100%, respectively, in patients with DCCA. PVCS accurately detected longitudinal extension of CCA to the hepatic and papillary sides that was not detected previously by endoscopic retrograde cholangiography in 20.0% and 11.6% patients, respectively. CONCLUSIONS: PVCS proved useful for the preoperative assessment of longitudinal extension of CCA. Therefore, it can aid surgeons in deciding surgical resectability and selecting operative procedures. This, in turn, may impact overall patient prognosis.

Factors affecting the accuracy of endoscopic transpapillary sampling methods for bile duct cancer.

BACKGROUND AND AIM: Various methods for endoscopic transpapillary sampling have been developed. However, the factors affecting the accuracy of these methods for bile duct cancer are unknown. The aim of the present study was to determine the factors affecting the accuracy of endoscopic transpapillary sampling methods. METHODS: We reviewed the results from 101 patients with bile duct cancer who underwent transpapillary sampling by aspiration bile cytology, brushing cytology, and fluoroscopic forceps biopsy. The final diagnosis of bile duct cancer was made on the basis of pathological evaluation of specimens obtained at surgery and the clinical course over at least 1 year in patients not operated on. We carried out subgroup analyses for the factors affecting the accuracy of each transpapillary sampling method. RESULTS: Aspiration bile cytology was carried out 238 times in 77 patients, brushing cytology was carried out 67 times in 60patients, and fluoroscopic forceps biopsy was carried out 64 times in 53 patients. Accuracies of aspiration bile cytology were significantly higher for longer (≥15 mm) biliary cancerous lesions than for shorter (<15 mm) lesions (30% vs 18%, respectively, P = 0.049). Accuracies of brushing cytology and fluoroscopic forceps biopsy were significantly higher for non-flat than for flat-type biliary cancerous lesions (brushing: 58% vs 38%, respectively, P = 0.032; forceps biopsy: 60% vs 33%, respectively, P = 0.043). CONCLUSION: Endoscopic transpapillary sampling methods are more accurate for longer or elevated (non-flat) biliary cancerous lesions than for shorter or flat lesions.

Experimental determination and mathematical modeling of standard shapes of forming autophagosomes.

The formation of autophagosomes involves dynamic morphological changes of a phagophore from a flat membrane cisterna into a cup-shaped intermediate and a spherical autophagosome. However, the physical mechanism behind these morphological changes remains elusive. Here, we determine the average shapes of phagophores by statistically investigating three-dimensional electron micrographs of more than 100 phagophores. The results show that the cup-shaped structures adopt a characteristic morphology; they are longitudinally elongated, and the rim is catenoidal with an outwardly recurved shape. To understand these characteristic shapes, we establish a theoretical model of the shape of entire phagophores. The model quantitatively reproduces the average morphology and reveals that the characteristic shape of phagophores is primarily determined by the relative size of the open rim to the total surface area. These results suggest that the seemingly complex morphological changes during autophagosome formation follow a stable path determined by elastic bending energy minimization.

PdPt/SrTiO3:Al-catalysed redox-selective photoreduction of unsaturated carboxylic acids using minimal electron-donor and water.

We developed a semiconductor photocatalyst, Pd-Pt alloy nanoparticle-loaded, Al-doped SrTiO3 (PdPt/STO:Al), for photoreduction of unsaturated carboxylic acids. Due to the cooperative STO:Al surface and Pd-Pt alloy nanoparticles, the catalyst dispersed in water provided highly redox-selective photoreduction against oxidative degradation of starting materials/products and against reductive evolution of H2, where minimal glycolic acid worked as an efficient electron-donating fuel.

Usefulness of Elobixibat in Patients With Chronic Constipation After Cholecystectomy.

BACKGROUND: There have been reports that elobixibat improves bowel movements in patients with chronic constipation. However, no studies have been conducted to date to examine bowel movements after the administration of elobixibat in patients with chronic constipation in terms of the presence or absence of the gallbladder. In this study, we examined the frequency of bowel movements and stool forms in patients with gallbladders and post-cholecystectomy patients before and after the administration of elobixibat for chronic constipation. METHODS: Elobixibat 10 mg was administered to treat chronic constipation in 40 patients with gallbladders and 18 patients who underwent cholecystectomy. The frequencies of bowel movements one week before and after elobixibat administration were compared between the two groups, using the Bristol Stool Form Scale (BSFS). RESULTS: No significant difference in patient background with or without cholecystectomy was noted between the groups. In patients with gallbladders, the pre-dosing mean frequency of bowel movements was 2.389 ± 0.502 with BSFS of 2.179 ± 0.721 and the post-dosing mean frequency of bowel movements was 4.308 ± 1.151 with BSFS of 3.718 ± 1.521, indicating significant improvement in bowel movements (p < 0.001). In post-cholecystectomy patients, the pre-dosing mean frequency of bowel movements was 2.389 ± 0.502 with BSFS of 2.222 ± 0.647 and the post-dosing mean frequency of bowel movements was 4.222 ± 1.734 with BSFS of 3.333±1.237, indicating significant improvement in bowel movements (p < 0.001). No significant difference in bowel movements was noted between patients with or without the gallbladder. CONCLUSIONS: Elobixibat is useful in improving the bowel movements of patients with chronic constipation. No significant difference was noted in the improvement of bowel movements due to cholecystectomy. It was suggested that even post-cholecystectomy patients could obtain therapeutic effects similar to patients with gallbladders.

Usefulness of Endoscopic Retrograde Cholangiopancreatography (ERCP)-Related Procedures for Gallstone Pancreatitis.

INTRODUCTION: Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (EST) are said to be useful procedures for gallstone pancreatitis. However, there have been few reports on a large number of patients to whom they were used. The clinical usefulness of ERCP and EST is herein examined retrospectively. METHODS: ERCP and EST were performed to evaluate their clinical usefulness and safety in 108 patients who had gallbladder stones from December 1985 to October 2017 and were diagnosed as having gallstone pancreatitis. Of 108 patients, 83 were mild, and 25 were severe. Following the procedures, clinical courses were observed for three years in 108 patients who underwent the treatments. RESULTS: Cholangiogram was successfully conducted in 108 patients. Bile duct stones were noted in 90 patients, and the stones were removed after EST. Of 18 patients who did not show bile duct stone in cholangiogram, 13 patients underwent EST, while five patients taking anticoagulants completed procedures only with cholangiogram. Accidental symptom was hemorrhage in three patients (2.7%; 3/108), but it was mild and conservatively resolving. During the three-year observation period, acute cholangitis was noted in three patients (2.7%; 3/108), but no relapsing pancreatitis was noted. CONCLUSIONS: It was suggested that ERCP and EST could be useful therapies for gallstone pancreatitis.

Involvement of porcine and human carbonyl reductases in the metabolism of epiandrosterone, 11-oxygenated steroids, neurosteroids, and corticosteroids.

Porcine carbonyl reductases (pCBR1 and pCBR-N1) and aldo-keto reductases (pAKR1C1 and pAKR1C4) exhibit hydroxysteroid dehydrogenase (HSD) activity. However, their roles in the metabolism of porcine-specific androgens (19-nortestosterone and epiandrosterone), 11-oxygenated androgens, neurosteroids, and corticosteroids remain unclear. Here, we compared the steroid specificity of the four recombinant enzymes by kinetic and product analyses. In C18/C19-steroids,11-keto- and 11ß-hydroxy-5α-androstane-3,17-diones were reduced by all the enzymes, whereas 5α-dihydronandrolone (19-nortestosterone metabolite) and 11-ketodihydrotestosterone were reduced by pCBR1, pCBR-N1, and pAKR1C1, of which pCBR1 exhibited the lowest (submicromolar) Km values. Product analysis showed that pCBR1 and pCBR-N1 function as 3α/ß-HSDs, in contrast to pAKR1C1 and pAKR1C4 (acting as 3ß-HSD and 3α-HSD, respectively). Additionally, 17ß-HSD activity was observed in pCBR1 and pCBR-N1 (toward epiandrosterone and its 11-oxygenated derivatives) and in pAKR1C1 (toward androsterone, 4-androstene-3,17-dione and their 11-oxygenated derivatives). The four enzymes also showed different substrate specificity for 3-keto-5α/ß-dihydro-C21-steroids, including GABAergic neurosteroid precursors and corticosteroid metabolites. 5ß-Dihydroprogesterone was reduced by all the enzymes, whereas 5α-dihydroprogesterone was reduced only by pCBR1, and 5α/ß-dihydrodeoxycorticosterones by pCBR1 and pCBR-N1. The two pCBRs also reduced the 5α/ß-dihydro-metabolites of cortisol, 11-deoxycortisol, cortisone, and corticosterone. pCBR1 exhibited lower Km values (0.3-2.9 µM) for the 3-keto-C21-steroids than pCBR-N1 (Km=10-36 µM). The reduced products of the 3-keto-C21-steroids by pCBR1 and pCBR-N1 were their 3α-hydroxy-metabolites. Finally, we found that human CBR1 has similar substrate specificity for the C18/C19/C21-steroids to pCBR-N1. Based on these results, it was concluded that porcine and human CBRs can be involved in the metabolism of the aforementioned steroids as 3α/ß,17ß-HSDs.

Natural history of asymptomatic gallbladder stones in clinic without beds: A long-term prognosis over 10 years.

BACKGROUND: Several studies have explored the long-term prognosis of patients with asymptomatic gallbladder stones. These reports were primarily conducted in facilities equipped with beds for addressing symptomatic cases. AIM: To report the long-term prognosis of patients with asymptomatic gallbladder stones in clinics without bed facilities. METHODS: We investigated the prognoses of 237 patients diagnosed with asymptomatic gallbladder stones in clinics without beds between March 2010 and October 2022. When symptoms developed, patients were transferred to hospitals where appropriate treatment was possible. We investigated the asymptomatic and survival periods during the follow-up. RESULTS: Among the 237 patients, 214 (90.3%) remained asymptomatic, with a mean asymptomatic period of 3898.9279 ± 46.871 d (50-4111 d, 10.7 years on average). Biliary complications developed in 23 patients (9.7%), with a mean survival period of 4010.0285 ± 31.2788 d (53-4112 d, 10.9 years on average). No patient died of biliary complications. CONCLUSION: The long-term prognosis of asymptomatic gallbladder stones in clinics without beds was favorable. When the condition became symptomatic, the patients were transferred to hospitals with beds that could address it; thus, no deaths related to biliary complications were reported. This finding suggests that follow-up care in clinics without beds is possible.

α-Pyrrolidinononanophenone derivatives induce differentiated SH-SY5Y neuroblastoma cell apoptosis via reduction of antioxidant capacity: Involvement of NO depletion and inactivation of Nrf2/HO1 signaling pathway.

α-Pyrrolidinononanophenone (α-PNP) derivatives are known to be one of the hazardous new psychoactive substances due to the most extended hydrocarbon chains of any pyrrolidinophenones on the illicit drug market. Our previous report showed that 4'-iodo-α-PNP (I-α-PNP) is the most potent cytotoxic compound among α-PNP derivatives and induces apoptosis due to mitochondrial dysfunction and suppression of nitric oxide (NO) production in differentiated human neuronal SH-SY5Y cells. In this study, to clarify the detailed action mechanisms by I-α-PNP, we investigated the mechanism of reactive oxygen species (ROS) -dependent apoptosis by I-α-PNP in differentiated SH-SY5Y with a focus on the antioxidant activities. Treatment with I-α-PNP elicits overproduction of ROS such as H2O2, hydroxyl radical, and 4-hydroxy-2-nonenal, and pretreatment with antioxidant N-acetyl-L-cysteine is attenuated the SH-SY5Y cells apoptosis by I-α-PNP. These results suggested that the overproduction of ROS is related to SH-SY5Y cell apoptosis by I-α-PNP. In addition, I-α-PNP markedly decreased antioxidant capacity in differentiated cells than in undifferentiated cells and inhibited the upregulation of hemeoxygenase 1 (HO1) and glutathione peroxidase 4 (GPX4) expression caused by induction of differentiation. Furthermore, the treatment with I-α-PNP increased the nuclear expression level of BTB Domain And CNC Homolog 1 (Bach1), a transcriptional repressor of Nrf2, only in differentiated cells, suggesting that the marked decrease in antioxidant capacity in differentiated cells was due to suppression of Nrf2/HO1 signaling by Bach1. Additionally, pretreatment with an NO donor suppresses the I-α-PNP-evoked ROS overproduction, HO1 down-regulation, increased nuclear Bach1 expression and reduced antioxidant activity in the differentiated cells. These findings suggest that the ROS-dependent apoptosis by I-α-PNP in differentiated cells is attributed to the inactivation of the Nrf2/HO1 signaling pathway triggered by NO depletion.

Syntaxin 17 recruitment to mature autophagosomes is temporally regulated by PI4P accumulation.

During macroautophagy, cytoplasmic constituents are engulfed by autophagosomes. Lysosomes fuse with closed autophagosomes but not with unclosed intermediate structures. This is achieved in part by the late recruitment of the autophagosomal SNARE syntaxin 17 (STX17) to mature autophagosomes. However, how STX17 recognizes autophagosome maturation is not known. Here, we show that this temporally regulated recruitment of STX17 depends on the positively charged C-terminal region of STX17. Consistent with this finding, mature autophagosomes are more negatively charged compared with unclosed intermediate structures. This electrostatic maturation of autophagosomes is likely driven by the accumulation of phosphatidylinositol 4-phosphate (PI4P) in the autophagosomal membrane. Accordingly, dephosphorylation of autophagosomal PI4P prevents the association of STX17 to autophagosomes. Furthermore, molecular dynamics simulations support PI4P-dependent membrane insertion of the transmembrane helices of STX17. Based on these findings, we propose a model in which STX17 recruitment to mature autophagosomes is temporally regulated by a PI4P-driven change in the surface charge of autophagosomes.

Single-nucleosome imaging unveils that condensins and nucleosome-nucleosome interactions differentially constrain chromatin to organize mitotic chromosomes.

For accurate mitotic cell division, replicated chromatin must be assembled into chromosomes and faithfully segregated into daughter cells. While protein factors like condensin play key roles in this process, it is unclear how chromosome assembly proceeds as molecular events of nucleosomes in living cells and how condensins act on nucleosomes to organize chromosomes. To approach these questions, we investigate nucleosome behavior during mitosis of living human cells using single-nucleosome tracking, combined with rapid-protein depletion technology and computational modeling. Our results show that local nucleosome motion becomes increasingly constrained during mitotic chromosome assembly, which is functionally distinct from condensed apoptotic chromatin. Condensins act as molecular crosslinkers, locally constraining nucleosomes to organize chromosomes. Additionally, nucleosome-nucleosome interactions via histone tails constrain and compact whole chromosomes. Our findings elucidate the physical nature of the chromosome assembly process during mitosis.