Structural Basis of Wnt Recognition by Frizzled Janda, Claudia Y.; Waghray, Deepa; Levin, Aron M. ...
Science (American Association for the Advancement of Science),
07/2012, Letnik:
337, Številka:
6090
Journal Article
Recenzirano
Odprti dostop
Wnts are lipid-modified morphogens that play critical roles in development principally through engagement of Frizzled receptors. The 3.25 angstrom structure of Xenopus Wnt8 (XWnt8) in complex with ...mouse Frizzled-8 (Fz8) cysteine-rich domain (CRD) reveals an unusual two-domain Wnt structure, not obviously related to known protein folds, resembling a "hand" with "thumb" and "index" fingers extended to grasp the Fz8-CRD at two distinct binding sites. One site is dominated by a palmitoleic acid lipid group projecting from serine 187 at the tip of Wnt's thumb into a deep groove in the Fz8-CRD. In the second binding site, the conserved tip of Wnt's "index finger" forms hydrophobic amino acid contacts with a depression on the opposite side of the Fz8-CRD. The conservation of amino acids in both interfaces appears to facilitate ligand-receptor cross-reactivity, which has important implications for understanding Wnt's functional pleiotropy and for developing Wnt-based drugs for cancer and regenerative medicine.
Tumours depend on altered rates of protein synthesis for growth and survival, which suggests that mechanisms controlling mRNA translation may be exploitable for therapy. Here, we show that loss of ...APC, which occurs almost universally in colorectal tumours, strongly enhances the dependence on the translation initiation factor eIF2B5. Depletion of eIF2B5 induces an integrated stress response and enhances translation of MYC via an internal ribosomal entry site. This perturbs cellular amino acid and nucleotide pools, strains energy resources and causes MYC-dependent apoptosis. eIF2B5 limits MYC expression and prevents apoptosis in APC-deficient murine and patient-derived organoids and in APC-deficient murine intestinal epithelia in vivo. Conversely, the high MYC levels present in APC-deficient cells induce phosphorylation of eIF2α via the kinases GCN2 and PKR. Pharmacological inhibition of GCN2 phenocopies eIF2B5 depletion and has therapeutic efficacy in tumour organoids, which demonstrates that a negative MYC-eIF2α feedback loop constitutes a targetable vulnerability of colorectal tumours.
Background
ENETS guidelines recommend parenchyma-sparing procedures without formal lymphadenectomy, ideally with a minimally invasive laparoscopic approach for sporadic small pNENs (≤2 cm). ...Non-functioning (NF) small pNENs can also be observed. The aim of the study was to evaluate how these recommendations are implemented in the German surgical community.
Methods
Data from the prospective StuDoQ|Pancreas registry of the German Society of General and Visceral Surgery were analyzed regarding patient’s demographics, tumor characteristics, surgical procedures, histology and perioperative outcomes.
Results
Eighty-four (29.2%) of 287 patients had sporadic pNENs ≤2 cm. Forty-three (51.2%) patients were male, and the mean age at diagnosis was 58.8 ± 15.6 years. Twenty-five (29.8%) pNENs were located in the pancreatic head. The diagnosis pNEN was preoperatively established in 53 (65%) of 84 patients. Sixty-two (73.8%) patients had formal pancreatic resections, including partial pancreaticoduodenectomy or total pancreatectomy (21.4%). Only 22 (26.2%) patients underwent parenchyma-sparing resections and 23 (27.4%) patients had minimally invasive procedures. A lymphadenectomy was performed in 63 (75.4%) patients, and lymph node metastases were diagnosed in 6 (7.2%) patients. Eighty-two (97.7%) patients had an R0 resection. Sixty (72%) tumors were classified G1, 24 (28%) tumors G2. Twenty-seven (32.2%) of 84 patients had postoperative relevant Clavien–Dindo grade ≥3 complications. Thirty- and 90-day mortalities were 2.4% and 3.6%.
Conclusions
ENETS guidelines for surgery of small pNENs are yet not well accepted in the German surgical community, since the rate of formal resections with standard lymphadenectomy is high and the minimally invasive approach is underused. The attitude to operate small NF tumors seems to be rather aggressive.
Cryo-electron microscopy (cryo-EM) has the capacity to capture molecular machines in action
. ATP-binding cassette (ABC) exporters are highly dynamic membrane proteins that extrude a wide range of ...substances from the cytosol
and thereby contribute to essential cellular processes, adaptive immunity and multidrug resistance
. Despite their importance, the coupling of nucleotide binding, hydrolysis and release to the conformational dynamics of these proteins remains poorly resolved, especially for heterodimeric and/or asymmetric ABC exporters that are abundant in humans. Here we present eight high-resolution cryo-EM structures that delineate the full functional cycle of an asymmetric ABC exporter in a lipid environment. Cryo-EM analysis under active turnover conditions reveals distinct inward-facing (IF) conformations-one of them with a bound peptide substrate-and previously undescribed asymmetric post-hydrolysis states with dimerized nucleotide-binding domains and a closed extracellular gate. By decreasing the rate of ATP hydrolysis, we could capture an outward-facing (OF) open conformation-an otherwise transient state vulnerable to substrate re-entry. The ATP-bound pre-hydrolysis and vanadate-trapped states are conformationally equivalent; both comprise co-existing OF conformations with open and closed extracellular gates. By contrast, the post-hydrolysis states from the turnover experiment exhibit asymmetric ATP and ADP occlusion after phosphate release from the canonical site and display a progressive separation of the nucleotide-binding domains and unlocking of the intracellular gate. Our findings reveal that phosphate release, not ATP hydrolysis, triggers the return of the exporter to the IF conformation. By mapping the conformational landscape during active turnover, aided by mutational and chemical modulation of kinetic rates to trap the key intermediates, we resolved fundamental steps of the substrate translocation cycle of asymmetric ABC transporters.
During the COVID-19 pandemic in 2020 a decrease of emergency consultations and modification in treatment of numerous medical conditions were observed. Aim of this paper was to evaluate the effect of ...the COVID-19 pandemic on incidence, treatment strategies, severity, length of hospital stay and time of presentation in adults and children with acute appendicitis.
A systematic literature search of Pubmed, Embase and Cochrane databases was performed, and eligible studies used to perform a meta-analysis.
46 suitable studies were identified with an overall reduction of appendicitis cases by 20.9% in adults and an increase of 13.4% in children. The rate of open appendectomies increased without statistical significance in both groups (adults: 8.5% vs. 7.1%, P = 0.32; children: 7.1% vs. 5.3%, P = 0.13), whereas the rate of antibiotic treatment increased significantly (P = 0.007; P = 0.03). Higher rates of complicated appendicitis were observed in adults (adults: OR 2.00, P < 0.0001; children: OR 1.64, P = 0.12). Time to first consultation did not change significantly (adults: 52.3 vs. 38.5 h – P = 0.057; children: 51.5 vs. 32.0 h – P = 0.062) and length of stay was also not lengthened during the pandemic (adults: 2.9 vs. 2.7 days, P = 0.057; children: 4.2 vs. 3.7 days, P = 0.062).
The COVID-19 pandemic of 2020 had major impact on incidence and treatment strategies of acute appendicitis. Results of this meta-analysis might be another hint to support the theory that appendicitis is not a progressive disease and surgeons can safely consider antibiotic therapy for acute uncomplicated appendicitis.
•The overall incidence of acute appendicitis decreased by 20.9% in adults and increased by 13.4% in children.•Instead of appendectomy, antibiotic therapy was administered more frequently during the pandemic.•There was an significant increase of complicated appendicitis including perforation and abscess in adults.•Rate of open surgery, length of stay and time from start of symptoms to presentation in the emergency room did not change.
The prognostic value of the local immune phenotype in patients with colorectal cancer has been extensively studied. Neoadjuvant radiotherapy and/or chemotherapy may potentially influence these immune ...responses. In this study, we examined the prognostic role of indoleamine-2,3-Dioxygenase (IDO1) and infiltrating cytotoxic T lymphocytes (CD8+) in locally advanced rectal carcinomas after neoadjuvant treatment. Expression of IDO1 and CD8 was evaluated by immunohistochemistry in 106 archival tumour tissue samples from patients following neoadjuvant chemoradiation and radical resection. The average infiltration of IDO1+ and CD8+ cells was calculated along the tumour invasive front, in the tumour centre and within the neoplastic cells and expressed as total scores. Of the tumour specimens evaluable for immunohistochemistry, 100% showed CD8+ lymphocyte infiltration and 93.4% stained positive for IDO1. Total IDO1 score positively correlated with total CD8 score for all three subsites (
p
= 0.002, Kendall-tau-b 0.357). A high total CD8 score was positively correlated with lower ypUICC-stages (
p
= 0.047) and lower ypT-categories (
p
= 0.032). Total IDO1 expression showed a clear trend towards a lower risk of recurrence (
p
= 0.078). A high total IDO1 score was an independent prognostic marker for prolonged disease-free survival (HR 0.38,
p
= 0.046) and a high total CD8 score for favourable overall survival (HR 0.16,
p
= 0.029). Analysis of the local CD8 and IDO1 expression profile may be a helpful tool in predicting prognosis for patients with locally advanced rectal cancer following neoadjuvant chemoradiation.
We present a novel technique to simultaneously measure wind speed (U) at thousands of locations continuously in time based on measurement of velocity‐dependent heat transfer from a heated surface. ...Measuring temperature differences between paired passive and actively heated fiber‐optic (AHFO) cables with a distributed temperature sensing system allowed estimation of U at over 2000 sections along the 230 m transect (resolution of 0.375 m and 5.5 s). The underlying concept is similar to that of a hot wire anemometer extended in space. The correlation coefficient between U measured by two colocated sonic anemometers and the AHFO were 0.91 during the day and 0.87 at night. The combination of classical passive and novel AHFO provides unprecedented dynamic observations of both air temperature and wind speed spanning 4 orders of magnitude in spatial scale (0.1–1000 m) while resolving individual turbulent motions, opening new opportunities for testing basic theories for near‐surface geophysical flows.
Key Points
Actively heated fiber optics distributed temperature sensing can measure wind speed
Wind speed was measured simultaneously at >2000 locations with 0.375 m and 5.5 s resolutions
Excellent agreement with independent sonic anemometers point measurements
Robotic-assisted colon surgery may contain advantages over the laparoscopic approach, but clear evidence is sparse. This study aimed to analyze postoperative inflammation status, short-term outcome ...and cost-effectiveness of robotic-assisted versus laparoscopic left hemicolectomy. All consecutive patients who received minimal-invasive left hemicolectomy at the Department of Surgery I at the University Hospital of Wuerzburg in 2021 were prospectively included. Importantly, no patient selection for either procedure was carried out. The robotic-assisted versus laparoscopic approaches were compared head to head for postoperative short-term outcomes as well as cost-effectiveness. A total of 61 patients were included, with 26 patients having received a robotic-assisted approach. Baseline characteristics did not differ among the groups. Patients receiving a robotic-assisted approach had a significantly decreased length of hospital stay as well as lower rates of complications in comparison to patients who received laparoscopic surgery (n = 35). In addition, C-reactive protein as a marker of systemic stress response was significantly reduced postoperatively in patients who were operated on in a robotic-assisted manner. Consequently, robotic-assisted surgery could be performed in a cost-effective manner. Thus, robotic-assisted left hemicolectomy represents a safe and cost-effective procedure and might improve patient outcomes in comparison to laparoscopic surgery.
Abstract
Optogenetics has become a key tool to manipulate biological processes with high spatio-temporal resolution. Recently, a number of commercial and open-source multi-well illumination devices ...have been developed to provide throughput in optogenetics experiments. However, available commercial devices remain expensive and lack flexibility, while open-source solutions require programming knowledge and/or include complex assembly processes. We present a LED Illumination Tool for Optogenetic Stimulation (LITOS) based on an assembled printed circuit board controlling a commercially available 32 × 64 LED matrix as illumination source. LITOS can be quickly assembled without any soldering, and includes an easy-to-use interface, accessible via a website hosted on the device itself. Complex light stimulation patterns can easily be programmed without coding expertise. LITOS can be used with different formats of multi-well plates, petri dishes, and flasks. We validated LITOS by measuring the activity of the MAPK/ERK signaling pathway in response to different dynamic light stimulation regimes using FGFR1 and Raf optogenetic actuators. LITOS can uniformly stimulate all the cells in a well and allows for flexible temporal stimulation schemes. LITOS’s affordability and ease of use aims at democratizing optogenetics in any laboratory.
•DSRCT is a neoplasm of young men, long term survival is reserved to a minority.•There are no standards of diagnostics and clinical management.•Multimodal therapy is frequently used with limited ...benefit.•Sufficient targeted therapies are missing.•Patients should be treated at centers and included in clinical trials and registers.
Desmoplastic Small Round Cell Tumors (DSRCTs) are an entity of rare, aggressive soft tissue sarcomas described by Gerald and Rosai in 1989. It predominantly affects male adolescents and young adults, with a peak incidence between an age of 20 and 30 years. Typically, DSRCT demonstrate as multiple small tumor nodules within the abdominal cave, retroperitoneum and pelvis. In more than 50% of the cases, the neoplasm presents metastatic at the timepoint of diagnosis.
Histologically, DSRCTs have a characteristic morphology with sharply demarcated islands of uniform small round cells in abundant desmoplastic stroma organized in loose extracellular matrix. Immunohistochemistry reveals a polyphenotypic differentiation with co-expression of epithelial, myogenic, mesenchymal and neural markers. The morphology is highly variable and can hinder diagnosis. The most consistent molecular characteristic of DSRCT is the reciprocal t(11;22)(p13q12) translocation. This mutation leads to a formation of the EWSR1-WT1 fusion oncogene, which encodes for a chimeric protein with transcriptional regulatory activity and is regarded as driving source of the disease.
To date, there is no standardized concept for clinical management, staging and treatment. Patients receive an aggressive multimodal therapeutic approach consisting of chemotherapy, radical surgical procedures, hyperthermic, intraperitoneal chemotherapy (HIPEC) and radiation. New targeted therapies are used in experimental settings as salvage therapy. So far, none of these therapies showed significant long-term success.
This review gives an overview of diagnostic difficulties and pitfalls, discusses therapeutic strategies and highlights options for clinical management.
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