A phosphatidylinositol (4,5)-bisphosphate binding site within μ2-adaptin regulates clathrin-mediated endocytosis

The clathrin adaptor complex AP-2 serves to coordinate clathrin-coated pit assembly with the sorting of transmembrane cargo proteins at the plasmalemma. How precisely AP-2 assembly and cargo protein recognition at sites of endocytosis are regulated has remained unclear, but recent evidence implicates phosphoinositides, in particular phosphatidylinositol (4,5)-bisphosphate (PI[4,5]P2), in these processes. Here we have identified and functionally characterized a conserved binding site for PI(4,5)P2 within μ2-adaptin, the medium chain of the clathrin adaptor complex AP-2. Mutant μ2 lacking a cluster of conserved lysine residues fails to bind PI(4,5)P2 and to compete the recruitment of native clathrin/AP-2 to PI(4,5)P2-containing liposomes or to presynaptic membranes. Moreover, we show that expression of mutant μ2 inhibits receptor-mediated endocytosis in living cells. We suggest that PI(4,5)P2 binding to μ2-adaptin regulates clathrin-mediated endocytosis and thereby may contribute to structurally linking cargo recognition to coat formation

Ein Protein für neue Aufgaben: die cytosolische PH-Domäne des Cytohesin-1 als Paratop und als Substrat für Translokationen

6.1. Die PH-Domäne als Paratop Die Pleckstrin-homologe (PH-) Domäne des humanen Cytohesin-1 besteht aus einem Proteingerüst sowie vier längeren Loops. Von diesen weisen drei in eine Richtung und bilden eine komplexe, flexible Oberflächenstruktur aus. Sollte man diese Oberflächenstruktur durch Mutation der Loops als Bindungstasche (Paratop) für Epitope von Schlüsselmolekülen etablieren können, wäre ein breiter Einsatz der PH-Domäne als Wirkstoff oder spezifisches Nachweisreagenz interessant, zumal sie sich in E. coli mit hohen Ausbeuten cytoplasmatisch löslich exprimieren läßt. In dieser Arbeit konnte gezeigt werden, daß sich die drei Loops verändern lassen, ohne daß die PH-Domäne ihre Struktur verliert; von daher eignet sich die PH-Domäne als Proteingerüst. Sie wurde insgesamt in 29 Aminosäurepositionen mit einem neuartigen Verfahren gewichtet randomisiert, indem an jeder Position die Wildtyp-Aminosäure bevorzugt wird. In Anbetracht der Zahl randomisierter Positionen sollte damit gegenüber einer ungewichteten Randomisierung kein Verlust an Komplexität für die Bibliothek zu befürchten sein, durch den möglichen Erhalt lokaler und nicht lokaler Wechselwirkungen aber die Zahl stabiler (damit exprimierbarer und selektierbarer) Mutanten deutlich erhöht werden. Die Randomisierung erfolgte dabei mit drei Oligodesoxynukleotiden, die in den randomisierten Positionen jeweils eine definierte Basenverteilung aufweisen. Zur Klonierung einer Bibliothek wurden sie im dazu entwickelten Verfahren der „asymmetrischen PCR-Reaktion“ eingesetzt und daraufhin zu einem in drei Segmenten randomisierten DNA-Fragment assembliert. Mit dieser Strategie konnten 6 · 107 Mutanten erzeugt werden. (Aus deutlich kleineren Bibliotheken anderer Proteine ließen sich bereits bindende Mutanten isolieren.) Die randomisierten Mutanten der PH-Domäne wurden im phage-display-Verfahren zur Selektion gegen drei Zielsubstanzen eingesetzt. Danach konnten ausschließlich Deletionsmutanten und Mutanten mit stop-Codons nachgewiesen werden, die keine Expression von PH-Domänen erlauben. Zurückgeführt wird dieses Ergebnis auf die schlechten Transporteigenschaften der PH-Domäne bei der Translokation in das Periplasma von E. coli, weshalb nicht auf bindende Paratope aus der Bibliothek selektiert werden konnte. Nach Verbesserung der Translokationseigenschaften von PH-Domänen sollte sich das phage-display-Verfahren zur Selektion bindender Mutanten fortsetzen lassen. 6.2. Die PH-Domäne als Substrat für Translokationen Die im phage-display-Verfahren eingesetzten M13-Bakteriophagen assemblieren in der inneren Membran von E. coli. Dies setzt die Translokation der mit dem g3-Protein fusionierten PH-Domäne in das Periplasma voraus. Die geringe periplasmatische Expression bei mehrheitlich aberranten Prozessierungen im Bereich des Signalpeptids und die geringe Darstellung auf der Phagenoberfläche veranlaßten zur Translokationsoptimierung der PH-Domäne. Während der allgemeine sekretorische Transportmechanismus von E. coli durch die beteiligten Membranproteine strukturell und funktionell gut verstanden ist, sind die Eigenschaften und Voraussetzungen für die Translokation von Substratproteinen (mit Signalpeptid als Präprotein bezeichnet) bislang weniger gut charakterisiert. Der „translokationskompetente“ Zustand beschreibt die Präproteine nur phänomenologisch. Für die schlechte Translokation wurden mehrere biochemische und biophysikalische Eigenschaften der PH-Domäne in Betracht gezogen und verschiedene Mutanten hergestellt, die demzufolge eine verbesserte Translokationseigenschaft aufweisen sollten. Dabei erwies sich weder die Verringerung der thermodynamischen Stabilität noch das engineering ausgewählter, spezifischer Sequenzelemente als translokationsbegünstigend. Wird dagegen durch Einführung neuer N- und C-Termini sowie der Verbrükkung der ursprünglichen Termini mit einem Linker die Topologie verändert, können bei zwei dieser sogenannten Circularpermutanten bis zu 30-fach höhere Expressionsausbeuten im Periplasma erzielt werden. Die Circularpermutation wurde damit erstmalig erfolgreich im rationalen Proteindesign angewendet. Die vorliegenden Ergebnisse legen nahe, daß die Mutanten der PH-Domäne vor der Translokation in einem nativ-ähnlichen Zustand gefaltet vorliegen und zur Translokation entfaltet werden müssen. Das in dieser Arbeit vorgeschlagene „Kräftemodell“ erklärt die verbesserte Translokation der Circularpermutanten CP X.6. gegenüber dem Wildtyp. Danach ist die maximale Kraft zur Entfaltung des Proteins die translokationslimitierende Größe, was sich mit Hilfe von Einzelmolekül-Kraft-Spektroskopie weiter untersuchen ließe. Wie sich die Mutationen an der PH-Domäne bei weiteren Transportprozessen auswirken, wurde beim mitochondrialen Import analysiert. Die untersuchten Mutanten zeigten unabhängig von ihrer thermodynamischen Stabilität und ihrer periplasmatischen Expression eine Unterbrechung des Imports. Ursache dafür ist eine Peptidsequenz von 27 Aminosäuren, die sich mit Hilfe der Circularpermutanten eindeutig identifizieren läßt. Sie führt bei der Circularpermutante CP 2.6. zu einer stabilen Expression im Intermembranraum und beim Wildtyp sowie bei der Circularpermutante CP 2.7. zu einem Verharren in der inneren Membran. Bei Mitochondrien konnte zuvor noch nie eine importunterbrechende Peptidsequenz nachgewiesen werden. Sie sollte sich zur stabilen Expression von Proteinen im Intermembranraum einsetzen lassen. In der (modellierten) Raumstruktur der PH-Domäne interagieren 19 der 27 Aminosäuren in einem Faltblatt/turn/Faltblatt-Motiv. Sie könnten als stabile Subdomäne den Import unterbrechen. Diese Interpretation ergänzt ein Modell zur Translokation von Präproteinen, wonach das Präprotein vom Intermembranraum schrittweise durch die innere Membran (bzw. den TIM-Komplex) in die Matrix diffundiert und dort arretiert wird. Dadurch wird die Rückdiffusion verhindert. Die Unterbrechung des weiteren Imports währt solange, bis aufgrund des thermodyamischen Gleichgewichts die Peptidsequenz vor der Membran entfaltet vorliegt und dann in die Matrix diffundieren kann. Ergänzende Experimente zum mitochondrialen Import sind in Vorbereitung. In dieser Arbeit konnte die PH-Domäne mit ihren Mutanten somit als Substrat für die Untersuchung von Transportprozessen etabliert werden. Die zukünftige Anwendung dieser Mutanten auf weitere Transportsysteme liegt dabei auf der Hand. Die Bibliothek randomisierter PH-Domäne wird in Kooperation mit anderen Arbeitskreisen zur Selektion spezifisch bindender und inhibierender Mutanten eingesetzt

NMDA receptor-dependent metaplasticity by high-frequency magnetic stimulation

High-frequency magnetic stimulation (HFMS) can elicit N-methyl-D-aspartate (NMDA) receptor-dependent long-termpotentiation (LTP) at Schaffer collateral-CA1 pyramidal cell synapses. Here, we investigated the priming effect of HFMS on the subsequent magnitude of electrically induced LTP in the CA1 region of rat hippocampal slices using field excitatory postsynaptic potential (fEPSP) recordings. In control slices, electrical high-frequency conditioning stimulation (CS) could reliably induce LTP. In contrast, the same CS protocol resulted in long-term depression when HFMS was delivered to the slice 30 min prior to the electrical stimulation. HFMS-primingwas diminishedwhen applied in the presence of themetabotropic glutamate receptor antagonists (RS)- -methylserine-O-phosphate (MSOP) and (RS)--methyl-4-carboxyphenylglycine (MCPG).Moreover,whenHFMSwas delivered in the presence of the NMDA receptor-antagonist D-2-amino-5-phosphonovalerate (50 M), CS-induced electrical LTP was again as high as under control conditions in slices without priming. These results demonstrate that HFMS significantly reduced the propensity of subsequent electrical LTP and show that both metabotropic glutamate and NMDA receptor activation were involved in this form of HFMS-induced metaplasticity

Orchiectomy versus medical therapy with LH-RH analogues for the treatment of advanced prostatic carcinoma

Background: In Germany prostatic cancer is the most frequent cancer in men. The therapy of advanced prostatic cancer has changed significantly from the sub capsulate and / or total orchiectomy to the medical LH-RH analogues therapy during the last ten years, which has considerable effects on results and on costs. Both treatment procedures are based on a slowing down regulation of the growth of the hormone sensitive, neoplastic prostatic cells by the withdrawal of testosterone, which is clinically accompanied by a slowed tumor progression. Objectives: This health technology assessment depicts and evaluates international data of medical effectiveness and efficiency of orchiectomy and medical therapy with LH-RH-analogues in patients with advanced prostate cancer. Methods: A systematic, diversified literature analysis in the common medical, economic and HTA data bases and further media was conducted. Results: Five identified, randomized and controlled studies concerning the application of LH-RH analogues showed the same medical effectiveness of orchiectomy and treatment with LH-RH analogues. Four different studies regarding the quality of life revealed no significant difference between the treatment with LH-RH analogues and the therapy with orchiectomy. Dealing with health economic aspects seven cost-minimizing studies and one cost effectiveness study could be identified. All cost-minimizing studies show methodological restrictions. In general all studies draw the conclusion that the treatment of advanced prostatic cancer with orchiectomy is the most cost effective method, if one assumes a remaining life expectancy of more than one year. Conclusions: According to available studies, there is clear evidence for the equivalent effectiveness of LH-RH analogues and orchiectomy. Until now the studies - due to immense methodological restrictions - could not supply sufficient scientific evidence concerning the aspects of quality of life. In cases of a remaining life expectancy of more than one year, the orchiectomy is the more cost-effective alternative of therapy

NMDA receptor-dependent metaplasticity by high-frequency magnetic stimulation

High-frequency magnetic stimulation (HFMS) can elicit N-methyl-D-aspartate (NMDA) receptor-dependent long-termpotentiation (LTP) at Schaffer collateral-CA1 pyramidal cell synapses. Here, we investigated the priming effect of HFMS on the subsequent magnitude of electrically induced LTP in the CA1 region of rat hippocampal slices using field excitatory postsynaptic potential (fEPSP) recordings. In control slices, electrical high-frequency conditioning stimulation (CS) could reliably induce LTP. In contrast, the same CS protocol resulted in long-term depression when HFMS was delivered to the slice 30 min prior to the electrical stimulation. HFMS-primingwas diminishedwhen applied in the presence of themetabotropic glutamate receptor antagonists (RS)- -methylserine-O-phosphate (MSOP) and (RS)--methyl-4-carboxyphenylglycine (MCPG).Moreover,whenHFMSwas delivered in the presence of the NMDA receptor-antagonist D-2-amino-5-phosphonovalerate (50 M), CS-induced electrical LTP was again as high as under control conditions in slices without priming. These results demonstrate that HFMS significantly reduced the propensity of subsequent electrical LTP and show that both metabotropic glutamate and NMDA receptor activation were involved in this form of HFMS-induced metaplasticity

Early diagenesis of redox-sensitive trace metals in the Peru upwelling area – Response to ENSO-related oxygen fluctuations in the water column

Pore water and solid phase data for redox-sensitive metals (Mn, Fe, V, Mo and U) were collected on a transect across the Peru upwelling area (11°S) at water depths between 78 and 2025 m and bottom water oxygen concentrations ranging from ~0 to 93 µM. By comparing authigenic mass accumulation rates and diffusive benthic fluxes, we evaluate the respective mechanisms of trace metal accumulation, retention and remobilization across the oxygen minimum zone (OMZ) and with respect to oxygen fluctuations in the water column related to the El Nino Southern Oscillation (ENSO). Sediments within the permanent OMZ are characterized by diffusive uptake and authigenic fixation of U, V and Mo as well as diffusive loss of Mn and Fe across the benthic boundary. Some of the dissolved Mn and Fe in the water column re-precipitate at the oxycline and shuttle particle-reactive trace metals to the sediment surface at the lower and upper boundary of the OMZ. At the lower boundary, pore waters are not sufficiently sulfidic as to enable an efficient authigenic V and Mo fixation. As a consequence, sediments below the OMZ are preferentially enriched in U which is delivered via both in situ pre-cipitation and lateral supply of U-rich phosphorites from further upslope. Trace metal cycling on the Peruvian shelf is strongly affected by ENSO-related oxygen fluctuations in bottom water. During periods of shelf oxygenation, surface sediments receive particulate V and Mo with metal (oxyhydr)oxides that derive from both terrigenous sources and precipitation at the retreating oxycline. After the recurrence of anoxic conditions, metal (oxyhydr)oxides are reductively dissolved and the hereby liberated V and Mo are authigenically removed. This alternation between supply of particle-reactive trace metals during oxic periods and fixation during anoxic periods leads to a preferential accumulation of V and Mo compared to U on the Peruvian shelf. The decoupling of V, Mo and U accumulation is further accentuated by the varying susceptibility to re-oxidation of the different authigenic metal phases. While authigenic U and V are readily re-oxidized and recycled during periods of shelf oxygenation, the sequestration of Mo by authigenic pyrite is favored by the transient occurrence of oxidizing conditions.Our findings reveal that redox-sensitive trace metals respond in specific manner to short-term oxygen fluctuations in the water column. The relative enrichment patterns identified might be useful for the reconstruction of past OMZ extension and large-scale redox oscillations in the geological record

quality of life outcomes of prostate cancer patients after radiotherapy or radical prostatectomy in a cohort study

Background This study describes and compares health-related quality of life (HRQOL) of prostate cancer patients who received either radical prostatectomy (nerve-sparing, nsRP, or non-nerve-sparing, nnsRP) or radiotherapy (external RT, brachytherapy, or both combined) for treatment of localised prostate cancer. Methods The prospective, multicenter cohort study included 529 patients. Questionnaires included the IIEF, QLQ-C30, and PORPUS-P. Data were collected before (baseline), three, six, twelve, and twenty-four months after treatment. Differences between groups’ baseline characteristics were assessed; changes over time were analysed with generalised estimating equations (GEE). Missing values were treated with multiple imputation. Further, scores at baseline and end of follow-up were compared to German reference data. Results The typical time trend was a decrease of average HRQOL three months after treatment followed by (partial) recovery. RP patients experienced considerable impairment in sexual functioning. The covariate-adjusted GEE identified a significant - but not clinically relevant - treatment effect for diarrhoea (b = 7.0 for RT, p = 0.006) and PORPUS-P (b = 2.3 for nsRP, b = 2.2 for RT, p = 0.045) compared to the reference nnsRP. Most of the HRQOL scores were comparable to German norm values. Conclusions Findings from previous research were reproduced in a specific setting of a patient cohort in the German health care system. According to the principle of evidence-based medicine, this strengthens the messages regarding treatment in prostate cancer and its impacts on patients’ health-related quality of life. After adjustment for baseline HRQOL and other covariates, RT patients reported increased symptoms of diarrhoea, and nnsRP patients decreased prostate-specific HRQOL. RP patients experienced considerable impairment in sexual functioning. These differences should be taken into account by physicians when choosing the best therapy for a patient

Measuring prostate-specific quality of life in prostate cancer patients scheduled for radiotherapy or radical prostatectomy and reference men in Germany and Canada using the Patient Oriented Prostate Utility Scale-Psychometric (PORPUS-P)

<p>Abstract</p> <p>Background</p> <p>The PORPUS-P is a short questionnaire for measuring prostate-specific quality of life (QoL), which was designed in Canada for use in prostate cancer (PC) patients. We aimed to generate a German version and compare PORPUS-P scores of German reference men from the general population, and German and Canadian patients with newly diagnosed PC who were scheduled to receive radical prostatectomy (RP) or radiotherapy (RT).</p> <p>Methods</p> <p>The study sample consisted of 988 reference men, 121 German and 66 Canadian PC patients scheduled for RT, and 371 German and 68 Canadian PC patients scheduled for RP. All men completed the PORPUS-P (German postal questionnaire, Canada personal interview). Data were gathered from PC patients before the start of therapy.</p> <p>Results</p> <p>Canadian patients were better educated than the German patients, and fewer were retired. Patients scheduled to receive RT were older and more were retired. German RT patients had lower D'Amico risk scores and pre-treatment Gleason scores than RP patients, and Canadian RT patients had higher pre-treatment PSA than RP patients. Urinary and sexual dysfunction were seen in PC patients (especially RT patients), but were also common in the German reference men. Crude mean PORPUS-P scores differed statistically significant between German RT and RP and Canadian RP and RT patients, with RT patients having higher QoL scores. The differences in age-adjusted mean PORPUS-P scores between reference men and RP patients were not clinically significant, while RT patients had (clinically) significantly lower scores than the reference men.</p> <p>Conclusion</p> <p>The German translation of the PORPUS-P appears to be a short and feasible tool for assessing prostate-specific QoL. Although we found a similar response pattern, Canadian and German PC patients scheduled to receive RT or RP rated their pre-treatment quality of life on different levels, which reveals the need for national reference data. Problems in several QoL domains exist before treatment, and differ between PC patients scheduled for RT and RP.</p

Rurality and Tourism in Transition: How Digitalization Transforms the Character and Landscape of the Tourist Economy in Rural Morocco

The character of rural Morocco is changing due to increasing tourism and social media usage. This paper outlines the different consequences of ICT usage among people working in the tourism sector as part of the transitional economy in a remote area. In this region, tourism has grown into one major income sources for a few valley inhabitants – mostly men with a school education, digital and language skills, and who are financially stable. As this transitional economy evolves alongside digitalization and ICT usage and therefore a change of the region’s rural character, it leads to challenges and concerns for the local population. This ethnographic study analyzes the interdependence of increasing tourism through digitalization and the notion of rurality as a resource from a sociotechnical perspective

Systematics and evolution of Carmichaelia, Chordospartium, Corallospartium, and Notospartium (Fabaceae) from New Zealand

All names in Carmichaelia, Chordospartium, Corallospartium, and Notospartium were typified, with many names requiring the selection of a lectotype. A taxonomic revision was undertaken of Carmichaelia, with seventeen species accepted as indigenous to New Zealand. A major taxonomic problem in Notospartium was resolved using morphological and habitat data. Two species of Notospartium are indigenous to Marlborough, these being separated by fault lines and each is associated with different parent materials. Wood anatomy of most species of Carmichaelia, Chordospartium, Corallospartium, and Notospartium was described to provide phylogenetically informative characters. The wood is characterised by vessels with helical thickenings and simple perforations; vessels, axial parenchyma, and short rays arranged in storied structure; predominantly fusiform parenchyma; and rays up to 20 cells wide. Developmental studies showed that Carmichaelia, Chordospartium, Corallospartium, and Notospartium exhibit habit- and leaf-heteroblastic development. A phylogenetic analysis using 47 mainly anatomical and morphological characters was undertaken using parsimony analysis. This analysis provided evidence that Carmichaelia is paraphyletic if Chordospartium, Corallospartium, and Notospartium are excluded, but monophyletic if these taxa are included in Carmichaelia. It is recommended that Carmichaelia be recircumscribed to include Chordospartium, Corallospartium, and Notospartium. Among the outgroup species Swainsona novae-zelandiae is shown to differ from Australian Swainsona by significant anatomical characters. To more accurately reflect its evolutionary history it is recommended that it be placed in a new and monotypic New Zealand genus