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Compartmentalization of GTPase regulators into signaling nodules dictates specific GTPase signaling pathway selection. Rac and Cdc42 are synchronized at the cell edge for effective protrusion in motile cells, but how their activity is coordinated remains elusive. Here, we report that ARHGAP39, a Rac and Cdc42 GTPase-activating protein, sequentially interacts with WAVE and mDia2 to control lamellipodia and filopodia protrusions, respectively. Mechanistically, ARHGAP39 binds WAVE, whereupon phosphorylation by Src promotes Rac inactivation and leads to Cdc42-induced filopodia formation. Using an optimized FRET biosensor, we detected active Cdc42 at the filopodia tips that controls filopodia extension. ARHGAP39 is transported to filopodia tips by Myosin-X where it binds mDia2 and inactivates Cdc42, leading to filopodia retraction. Failure in lamellipodia-to-filopodia switch by defective ARHGAP39 impairs cell invasion and metastasis. Our study reveals that compartmentalization of ARHGAP39 within Rac/Cdc42 signaling nodules orchestrates the synchronization of lamellipodia and filopodia and highlights the intricate regulation of leading edge dynamics in migrating cells.

Understanding the relationship between host and pathogen is key to combatting disease. SMAD transcription factors, which transmit TGF-β superfamily signalling, mediate an array of outcomes during embryogenesis, inflammation, cancer, and immunity. Surprisingly, these activities can sometimes be directly opposed; for example, SMAD3 has been reported as tumour suppressor by arresting cell cycle progression but conversely promotes cancer metastasis. A growing body of literature has identified SMADs as prominent targets during viral and bacterial infection for modulating host signalling. During infection, the activity of SMAD-containing transcriptional complexes can be finely tuned by pathogens to enhance infectivity and spread. SMAD signalling can be modulated at many levels, such as upstream at the ligand and receptor, or by direct interactions with SMADs. These alterations can increase pathogen dissemination, induce fibrosis, over-activate, or attenuate the host immune response. Here, we summarise the diverse mechanisms by which pathogens have evolved to sway SMAD signalling in their favour. Understanding the intricacies of host-pathogen interactions through this lens may elucidate aspects of SMAD function in cancer development, homoeostasis, and immune signalling previously overlooked. These insights are an opportunity to identify novel TGF-β or BMP-targeted therapeutics for applications to infectious disease contexts.

Two-sided oxidation experiments were recently conducted at 900°C–1200 °C in flowing steam with samples of sponge-based Zr-1Nb alloy E110. Although the old electrolytic E110 tubing exhibited a high degree of susceptibility to nodular corrosion and experienced breakaway oxidation rates in a relatively short time, the new sponge-based E110 demonstrated steam oxidation behavior comparable to Zircaloy-4. Sample weight gain and oxide layer thickness measurements were performed on oxidized E110 specimens and compared to oxygen pickup and oxide layer thickness calculations using the Cathcart-Pawel correlation. Our study shows that the sponge-based E110 follows the parabolic law at temperatures above 1015 °C. At or below 1015 °C, the oxidation rate was very low when compared to Zircaloy-4 and can be represented by a cubic expression. No breakaway oxidation was observed at 1000 °C for oxidation times up to 10,000 s. Arrhenius expressions are given to describe the parabolic rate constants at temperatures above 1015 °C and cubic rate constants are provided for temperatures below 1015 °C. The weight gains calculated by our equations are in excellent agreement with the measured sample weight gains at all test temperatures. In addition to the as-fabricated E110 cladding sample, prehydrided E110 cladding with hydrogen concentrations in the 100–150 wppm range was also investigated. The effect of hydrogen content on sponge-based E110 oxidation kinetics was minimal. No significant difference was found between as-fabricated and hydrided samples with regard to oxygen pickup and oxide layer thickness for hydrogen contents below 150 wppm.

Background: Patients with cancer are at increased risk of severe outcomes from COVID-19. Understanding the impact of SARS-CoV-2 infection and vaccination induced-immunity is an area of unmet need. Methods: CAPTURE (NCT03226886) is a prospective longitudinal cohort study of COVID-19 vaccine or SARS-CoV-2 infection-induced immunity. SARS-CoV-2 infections were confirmed by RT-PCR and ELISA. Neutralising antibody titres (NAbT) against wild-type (WT) SARS-CoV-2 and variants of concern (VOC;Alpha, Beta, Delta) and SARS-CoV-2 specific T-cells (SsT-cells) were quantified. Results: 118 patients (89% solid malignancy, [SM]) were SARS-CoV-2-positive (median follow-up: 154 days). 85% patients were symptomatic;2 died of COVID-19. 82% had S1-reactive antibodies, of whom 89% had neutralising antibodies (NAbs);NAbT were lower against all VOCs. While S1-reactive antibody levels declined over time, NAbT remained stable up to 329 days. Most patients had detectable SsT-cells (76% CD4+, 52% CD8+). Haematological malignancy (HM) patients had impaired immune responses that were disease and treatment-specific (anti-CD20), but with evidence suggestive of compensation from T-cells. 585 patients were evaluated following 2 doses of BNT162b2 or AZD1222 vaccines, administered 12 weeks apart. Seroconversion rates after 2 doses were 85% and 54% in patients with SM and HM, respectively. A lower proportion of patients had detectable NAbs against SARS-CoV-2 VOC (Alpha 62%, Beta 54%, Delta 49%) vs WT (84%), with corresponding significantly lower NAbT. Patients with HM were more likely to have an undetectable NAb and had lower NAbT vs solid malignancies to both WT and VOCs. Seroconversion showed poor concordance with NAbTs against VOCs. Prior SARS-CoV-2 infection boosted NAbT including against VOCs. Anti-CD20 treatment was associated with severely diminished NAbTs. Vaccine-induced T-cell responses were detected in 80% of patients, with no differences between vaccines or cancer types. Conclusions: Patients with HM had blunted humoural responses to infection and vaccination, particularly against VOCs, but preserved cellular responses might contribute to protection. Our results lend support to prioritisation of all cancer patients for further booster vaccination. Clinical trial identification: NCT03226886. Legal entity responsible for the study: The Royal Marsden NHS Foundation Trust. Funding: The Royal Marsden Charity;The National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) at the Royal Marsden Hospital and Institute for Cancer Research (ICR). Disclosure: All authors have declared no conflicts of interest.

Summary In contrast to most DNA viruses, poxviruses replicate their genomes in the cytoplasm without host involvement. We find that vaccinia virus induces cytoplasmic activation of ATR early during infection, before genome uncoating, which is unexpected because ATR plays a fundamental nuclear role in maintaining host genome integrity. ATR, RPA, INTS7, and Chk1 are recruited to cytoplasmic DNA viral factories, suggesting canonical ATR pathway activation. Consistent with this, pharmacological and RNAi-mediated inhibition of canonical ATR signaling suppresses genome replication. RPA and the sliding clamp PCNA interact with the viral polymerase E9 and are required for DNA replication. Moreover, the ATR activator TOPBP1 promotes genome replication and associates with the viral replisome component H5. Our study suggests that, in contrast to long-held beliefs, vaccinia recruits conserved components of the eukaryote DNA replication and repair machinery to amplify its genome in the host cytoplasm., Graphical Abstract, Highlights • Vaccinia activates cytoplasmic ATR early during infection and before genome uncoating • Canonical ATR pathway activation promotes viral genome replication • RPA is recruited to the viral genome • PCNA, RPA, and TOPBP1 associate with the viral polymerase to promote DNA replication, Postigo et al. suggest that, in contrast to long-held beliefs, vaccinia recruits conserved components of the eukaryote DNA replication and repair machinery to amplify its genome in the host cytoplasm.

Summary During early development, extrinsic triggers prompt pluripotent cells to begin the process of differentiation. When and how human embryonic stem cells (hESCs) irreversibly commit to differentiation is a fundamental yet unanswered question. By combining single-cell imaging, genomic approaches, and mathematical modeling, we find that hESCs commit to exiting pluripotency unexpectedly early. We show that bone morphogenetic protein 4 (BMP4), an important differentiation trigger, induces a subset of early genes to mirror the sustained, bistable dynamics of upstream signaling. Induction of one of these genes, GATA3, drives differentiation in the absence of BMP4. Conversely, GATA3 knockout delays differentiation and prevents fast commitment to differentiation. We show that positive feedback at the level of the GATA3-BMP4 axis induces fast, irreversible commitment to differentiation. We propose that early commitment may be a feature of BMP-driven fate choices and that interlinked feedback is the molecular basis for an irreversible transition from pluripotency to differentiation., Graphical Abstract, Highlights • Irreversible commitment to BMP4-driven hESC differentiation is fast • SMAD activation is sustained, bistable, and irreversible due to positive feedback • GATA3 mirrors SMAD dynamics and mediates fast commitment to differentiation • GATA3 is an early commitment gene, Gunne-Braden et al. show that GATA3 is an early commitment gene that mediates fast commitment to BMP4-driven differentiation in human embryonic stem cells (hESCs). Interlinked feedback regulation at the level of the GATA3-BMP4 axis allows for an irreversible exit from pluripotency and an early commitment to differentiation.

An important purpose of integrating computer use into everyday classroom instruction is to help students approach technology as a learning tool. Effective classroom integration is dependent not only on access to computers but also teachers' implementation of computing into learning. Successful implementation, in turn, depends largely on teachers' beliefs about classroom computing. The purpose of this study is to examine the effects of a teacher-focused technology intervention on students' attitudes toward and use of computers as learning tools. Teachers' attitudes, anxiety, and classroom computer use are explored as mediators of this relationship. Data were collected during a technology intervention in fourth and fifth grade classrooms in an urban public school district. Results suggest that the technology intervention itself had a positive effect on students' attitudes toward and use of computers for educational purposes. There was no evidence, however, that teachers' use or attitudes had any mediating effect on this relationship. These results suggest that it is possible to increase students' attitudes toward computer use through intense interventions aimed at their teachers. Future research should further investigate the mechanisms through which this relationship exits.

Summary Background Type 1 diabetes results from autoimmune targeting of the pancreatic β cells, likely mediated by effector memory T (Tem) cells. CD2, a T cell surface protein highly expressed on Tem cells, is targeted by the fusion protein alefacept, depleting Tem cells and central memory T (Tcm) cells. We postulated that alefacept would arrest autoimmunity and preserve residual β cells in patients newly diagnosed with type 1 diabetes. Methods The T1DAL study is a phase 2, double-blind, placebo-controlled trial in patients with type 1 diabetes, aged 12–35 years who, within 100 days of diagnosis, were enrolled at 14 US sites. Patients were randomly assigned (2:1) to receive alefacept (two 12-week courses of 15 mg intramuscularly per week, separated by a 12-week pause) or a placebo. Randomisation was stratified by site, and was computer-generated with permuted blocks of three patients per block. All participants and site personnel were masked to treatment assignment. The primary endpoint was the change from baseline in mean 2 h C-peptide area under the curve (AUC) at 12 months. Secondary endpoints at 12 months were the change from baseline in the 4 h C-peptide AUC, insulin use, major hypoglycaemic events, and HbA 1c concentrations. This trial is registered with ClinicalTrials.gov, number NCT00965458. Findings Of 73 patients assessed for eligibility, 33 were randomly assigned to receive alefacept and 16 to receive placebo. The mean 2 h C-peptide AUC at 12 months increased by 0·015 nmol/L (95% CI −0·080 to 0·110) in the alefacept group and decreased by 0·115 nmol/L (–0·278 to 0·047) in the placebo group, and the difference between groups was not significant (p=0·065). However, key secondary endpoints were met: the mean 4 h C-peptide AUC was significantly higher (mean increase of 0·015 nmol/L [95% CI −0·076 to 0·106] vs decrease of −0·156 nmol/L [–0·305 to −0·006]; p=0·019), and daily insulin use (0·48 units per kg per day for placebo vs 0·36 units per kg per day for alefacept; p=0·02) and the rate of hypoglycaemic events (mean of 10·9 events per person per year for alefacept vs 17·3 events for placebo; p 1c concentrations at week 52 were not different between treatment groups (p=0·75). So far, no serious adverse events were reported and all patients had at least one adverse event. In the alefacept group, 29 (88%) participants had an adverse event related to study drug versus 15 (94%) participants in the placebo group. In the alefacept group, 14 (42%) participants had grade 3 or 4 adverse events compared with nine (56%) participants in the placebo group; no deaths occurred. Interpretation Although the primary outcome was not met, at 12 months, alefacept preserved the 4 h C-peptide AUC, lowered insulin use, and reduced hypoglycaemic events, suggesting efficacy. Safety and tolerability were similar in the alefacept and placebo groups. Alefacept could be useful to preserve β-cell function in patients with new-onset type 1 diabetes. Funding US National Institutes of Health and the Juvenile Diabetes Research Foundation.

The firefly luciferase gene is commonly used in cell-based reporter assays. Convenient luciferase assay reagents for use in high-throughput screening (HTS) are commercially available. However, the high cost of these reagents is not within the means of some academic laboratories. Therefore, we set out to develop an affordable luciferase assay reagent applicable in an HTS format using simple liquid-handling steps. The reagent was homemade from individual chemical components and optimized for luminescence intensity and stability. We determined the minimal concentrations of the most expensive components, dithiothreitol (DTT) and D-luciferin, resulting in a total assay reagent cost of less than 1 cent per sample. Signal stability was maximized by omission of coenzyme A and reduction of DTT concentration. The assay was validated in a high-throughput setting using two cancer cell lines carrying a p53-dependent luciferase reporter construct and siRNAs modulating p53 transcriptional activity. Induction of p53 activity by silencing PPM1D or SYVN1 and reduction of p53 activity by silencing p53 remained constant over a 2-h measurement period, with good assay quality (Z' factors mostly above 0.5). Hence, the luciferase assay described herein can be used for affordable reporter readout in cell-based HTS.

SummaryThe exocyst complex plays a critical role in targeting and tethering vesicles to specific sites of the plasma membrane. These events are crucial for polarized delivery of membrane components to the cell surface, which is critical for cell motility and division. Though Rho GTPases are involved in regulating actin dynamics and membrane trafficking, their role in exocyst-mediated vesicle targeting is not very clear. Herein, we present evidence that depletion of GEF-H1, a guanine nucleotide exchange factor for Rho proteins, affects vesicle trafficking. Interestingly, we found that GEF-H1 directly binds to exocyst component Sec5 in a Ral GTPase-dependent manner. This interaction promotes RhoA activation, which then regulates exocyst assembly/localization and exocytosis. Taken together, our work defines a mechanism for RhoA activation in response to RalA-Sec5 signaling and involvement of GEF-H1/RhoA pathway in the regulation of vesicle trafficking.

Conduct an experiment with flowing Li in a thermal gradient to determine the compatibility of V-4Cr-4Ti and a multi-layer electrically-insulating coating needed to reduce the magneto hydrodynamic (MHD) force in the first wall of a lithium cooled blanket. A mono-metallic V-4Cr-4Ti thermal convection loop was operated in vacuum ({approx}10{sup -5}Pa) at a maximum Li temperature of 700 C for 2,355h and Li flow rate of 2-3 cm/s. Two-layer, physical vapor deposited Y{sub 2}O{sub 3}-vanadium, electrically-insulating coatings on V-4Cr-4Ti substrates as well as uncoated tensile and sheet specimens were located in the flow path in the hot and cold legs. After exposure, specimens at the top of the hot leg showed a maximum mass loss equivalent to {approx}1.3 {micro}m of uniform metal loss. Elsewhere, small mass gains were observed on the majority of specimens that also showed an increase in hardness and room temperature yield stress and a decrease in ductility consistent with interstitial uptake. Specimens that lost mass showed a decrease in yield stress and hardness. Profilometry showed no significant thickness loss from the coatings.

Summary During vertebrate development, Activin/Nodal-related ligands signal through Smad2, leading to its activation and accumulation in the nucleus. Here, we demonstrate that Smad2 constantly shuttles between the cytoplasm and nucleus both in early Xenopus embryo explants and in living zebrafish embryos, providing a mechanism whereby the intracellular components of the pathway constantly monitor receptor activity. We have gone on to demonstrate that an intact microtubule network and kinesin ATPase activity are required for Smad2 phosphorylation and nuclear accumulation in response to Activin/Nodal in early vertebrate embryos and TGF-β in mammalian cells. The kinesin involved is kinesin-1, and Smad2 interacts with the kinesin-1 light chain subunit. Interfering with kinesin activity in Xenopus and zebrafish embryos phenocopies loss of Nodal signaling. Our results reveal that kinesin-mediated transport of Smad2 along microtubules to the receptors is an essential step in ligand-induced Smad2 activation.

At early stages of tumorigenesis, the transforming growth factor-beta (TGF-beta) signaling pathway is thought to have tumor suppressor activity as a result of its ability to arrest the growth of epithelial cells. Smad4 plays a pivotal role in the TGF-beta signaling pathway and has been identified as a tumor suppressor, being mutated or deleted in approximately 50% of pancreatic carcinomas and 15% of colorectal cancers. A nonsense mutation generating a C-terminal truncation of 38 amino acids in the Smad4 protein has been identified in a pancreatic adenocarcinoma (Hahn, S. A., Schutte, M., Hoque, A. T., Moskaluk, C. A., da Costa, L. T., Rozenblum, E., Weinstein, C. L., Fischer, A., Yeo, C. J., Hruban, R. H., and Kern, S. E. (1996) Science 271, 350-353), and here we investigate the functional consequences of this mutation. We demonstrate that the C-terminal truncation prevents Smad4 homomeric complex formation and heteromeric complex formation with activated Smad2. Furthermore, the mutant protein is unable to be recruited to DNA by transcription factors and hence cannot form transcriptionally active DNA-binding complexes. These observations are supported by molecular modeling, which indicates that the truncation removes residues critical for homomeric and heteromeric Smad complex formation. We go on to show that the mutant Smad4 is highly unstable compared with wild type Smad4 and is rapidly degraded through the ubiquitin-proteasome pathway. Consistent with this, we demonstrate that the pancreatic adenocarcinoma harboring this mutated allele, in conjunction with loss of the other allele, expresses no Smad4 protein. Thus we conclude that these tumors completely lack Smad4 activity.

The origin recognition complex (ORC) binds to origins of replication in budding yeast. We have cloned a Xenopus homolog of the largest ORC polypeptide (XORC1). Immunodepletion of XOrc1 from Xenopus egg extracts blocks the initiation of DNA replication. We have purified Xenopus ORC, consisting of a protein complex similar to yeast ORC. In Xenopus egg extracts, ORC associates with chromatin throughout G1 and S phases. RLF-M, a component of the replication licensing system, also associates with chromatin early in the cell cycle but dissociates during S phase. We show that the assembly of RLF-M onto chromatin is dependent on the presence of chromatin-bound ORC, leading to sequential assembly of initiation proteins onto replication origins during the cell cycle.

Picornavirus 3C proteases are substrate-specific cysteine proteases, proposed to be homologous to the trypsin/chymotrypsin-like serine proteases on the basis of structural predictions. Substitutions at the putative active site residues (Glu71 and Cys147) of the poliovirus 3C protease did not completely abolish proteolytic processing in vitro. The activity of mutated 3C proteases was in the following hierarchy: Glu71-Cys147 (wild type) > Asp-Cys147 > Glu71 Ser147 > Gln71-Cys147 > Asp71-Ser147 > Gln71-Ser147 (inactive at all sites). Such mutations had differential effects on cleavage at different sites of the poliovirus polyprotein. Cleavage within the P1 region of the polyprotein was the most defective, at the 1ABC/VP1 junction and particularly at the VP0/VP3 junction. Cleavage at the 3AB/3CD and 2B/2C junctions was less affected by the mutations, and the P2/P3 and 2A/2BC junctions were cleaved efficiently by all mutants except Gln71-Ser147. All the 3C mutants gave negative results in infectivity and replication assays after transfection, indicating that mutation of Glu71 or Cys147 virtually abolishes viral replication, irrespective of the efficiency of processing of the nonstructural part of the polyprotein.

The comorbidities, operative details, complications, and results were reviewed. Results: A total of 310 patients underwent laparoscopic BPD-DS. Of these, 293 were primary procedures, 5 were revisions to BPDDS, and 12 were second-stage procedures. The hospital length of stay for those undergoing nonrevision procedures was 2.3 days. The mortality rate was 0%, the conversion rate was 0.3%, and the leak rate was 1%. The early major complication rate was 3.7%, and the late major complication rate was 2%. Malnutrition requiring hospitalization or reversal occurred in 3 patients (1%). The average preoperative body mass index was 47.8 kg/m (range 36–60). The excess body weight loss at 1 year was 78%, at 2 years was 81%, and at 3 years was 86%. Conclusions: Laparoscopic BPD-DS is as safe as open BPD-DS and open and laparoscopic gastric bypass. The effectiveness to date has been comparable to the results of open BPD-DS. PII: S1550-7289(05)00163-2