Induction and Regulation of Plasma Membrane Blebbing by SH4-Domains and the Diaphanous Related Formin FHOD1

Die Plasmamembran (PM) tierischer Zellen besteht aus einer dynamischen, lipidhaltigen Doppelschicht, die beispielsweise bei der Bildung von Zellausläufern wie Lamellipodien, Filopodien oder Membranfalten abhängig von zellulären Bedürfnissen konstant umgestaltet wird. Die ballonartigen PM "blebs" stellen ebenfalls einen solchen Typ Zellausläufer dar und können zum Beispiel während Apoptose, Sekretion und Zellbeweglichkeit auftreten. Dabei werden Ausdehnung, Stabilisierung und Rückbildung der "blebs" vermutlich durch eine gemeinsame zelluläre Maschinerie kontrolliert, die sowohl die Organisation und Integrität des Zytoskeletts als auch dessen Interaktion mit der PM beeinflusst. Eine wichtige Rolle spielt dabei die Rho Kinase ROCK, deren Aktivität notwendig für PM "blebbing" ist. In dieser Studie wurden SH4-Domänen als neuartiger Auslöser für PM "blebbing" identifiziert. SH4-Domänen sind die Ankerdomänen bestimmter peripherer PM Proteine wie der protoonkogenen Src Kinasen und des Oberflächenproteins HASPB des Leishmania Parasiten. Sie werden durch acetylierte und gesättigte Kohlenwasserstoffketten, teils unterstützt durch basische Bereiche in der Aminosäuresequenz an die PM gebunden. Es stellte sich heraus, dass diese Assoziation an die PM notwendig für die Induktion von SH4-Domänen vermitteltem PM "blebbing" war, welches Kinetiken aufwies, die vergleichbar mit beschriebenen PM "blebbing" Phänotypen waren. Darüber hinaus stand dieser dynamische Prozess allein unter der Kontrolle eines auf Rho, jedoch nicht auf Rac oder Cdc42 basierenden GTPase Signalweges, wurde durch ROCK Aktivität und Myosin II ATPase reguliert und benötigte sowohl F-Aktin- als auch Mikrotubuli-Integrität. Als neuer regulierender Faktor wurden Src Kinasen bestimmt, da endogene Src Kinase Aktivität essentiell für SH4-Domänen induziertes PM "blebbing" war. Darüber hinaus waren SH4-Domänen induzierte PM "blebs" sowohl mit aktivem c-Src als auch mit aktivem ROCK angereichert. Es bestand eine funktionelle Korrelation von SH4-Domänen induziertem PM "blebbing" sowohl mit einer erhöhten zellulären Aufnahme flüssiger Bestandteile als auch mit einer erhöhten Zellinvasion in 3D Matrizen, welche in direktem Zusammenhang mit der amöboiden Form der Zellwanderung metastasierender Tumorzellen steht. Tatsächlich zeigten SH4-Domänen exprimierende CHO Zellen auch in 3D Umgebungen eine ähnliche "bleb" Morphologie und ihre Invasivität war vergleichbar mit der von MDA-MB-435 Brustkrebszellen, was auf eine neue zelluläre Funktion dieser Ankerdomänen hinweist. Auch das "diaphanous related formin" FHOD1 konnte, basierend auf RNAi vermittelter Herunterregulierung, als Faktor für SH4-Domänen induziertes PM "blebbing" identifiziert werden. In Koexpression mit ROCK1 war FHOD1 in Abhängigkeit von seiner Fähigkeit zur F-Aktin-Nukleierung und möglicherweise durch direkte Interaktion mit ROCK1 an der Induktion von nicht-apoptotischem PM "blebbing" beteiligt. Dabei war Src Kinase Aktivität sowohl für die Induktion von PM "blebs" als auch für Interaktion von FHOD1 mit ROCK1 notwendig, was auf ein direktes Zusammenspiel dieser Faktoren hinweist. In einem in dieser Studie aufgestellten hypothetischen Modell sind c-Src und ROCK1 verantwortlich für PM Assoziation und Regulation der "blebbing" Maschinerie. FHOD1 vermittelte F-Aktin Polymerisierung ist hingegen notwendig für die Organisation des Zytoskeletts während des "blebbing" Vorganges, möglicherweise mit Unterstützung anderer Formine. Schließlich konnte unter Verwendung eines neuen FHOD1 spezifischen Antikörpers gezeigt werden, dass endogenes FHOD1 in tierischen Zellen in perinukleären, Golgi ähnlichen Bereichen lokalisierte. Zusätzlich zu seiner Rolle in SH4-Domänen vermitteltem PM "blebbing" war es jedoch durch RNAi vermittelte Herunterregulierung nicht möglich, weitere Funktionen für FHOD1 zu ermitteln, weder in Bezug auf seine Golgi Assoziation noch auf seine postulierten Funktion für F-Aktin-Organisation. Zusammenfassend wurden sowohl Src Kinasen als auch FHOD1 als neue Bestandteile einer zellulären Maschinerie identifiziert, die von Rho-ROCK Aktivität abhängig war und von SH4-Domänen gesteuert wurde. Ferner weisen die hier beschriebenen Ergebnisse auf ein neuartiges Zusammenspiel von SH4-Domänen, Src Aktivität, ROCK Signalwirkung und FHOD1 vermittelte Zytoskelett Umgestaltung hin. Da PM "blebbing" mit erhöhter zellulärer Aufnahme flüssiger Bestandteile und erhöhter Zellwanderung in 3D Umgebungen korrelierte, könnte SH4-Domänen vermittelte PM Dynamik einen Mechanismus darstellen, der die Invasivität von Zellen beeinflusst, die durch SH4-Domänen-haltige Onkoproteine transformiert wurden

Generic test case to understand cryogenic methane combustion dynamics

The accurate numerical simulation of high-pressure rocket combustion chambers is a key element for the design of future space transportation vehicles. In recent years investigations focus more and more on methane-based combustion chambers for which many thermodynamic and combustion issues are still unknown. Experimental investigations indicate that we might have to deal with a close interaction of non-ideal equation-of-state effects together with complex kinetic schemes. On the numerical side the main challenges include the consistent approximation of thermodynamic effects within a broad temperature range from cryogenic injection up to high temperature effects at combustion. Nowadays simple numerical test cases are missing to study and understand the basic effects during the injection and combustion process especially with methane as propellant. This open question is addressed by the definition of a simple test case for cryogenic methane combustion and its analysis by applying a range of thermodynamic and kinetic models

A Mendelian randomization study on the effect of 25‐hydroxyvitamin D levels on periodontitis

Abstract Background Twenty five‐hydroxy vitamin D (25OHD) levels have been proposed to protect against periodontitis based on in vitro and observational studies but evidence from long‐term randomized controlled trials (RCTs) is lacking. This study tested whether genetically proxied 25OHD is associated with periodontitis using Mendelian randomization (MR). Methods Genetic variants strongly associated with 25OHD in a genome‐wide association study (GWAS) of 417,580 participants of European ancestry were used as instrumental variables, and linked to GWAS summary data of 17,353 periodontitis cases and 28,210 controls. In addition to the main analysis using an inverse variance weighted (IVW) model, we applied additional robust methods to control for pleiotropy. We also undertook sensitivity analyses excluding single nucleotide polymorphisms (SNPs) used as instruments with potential pleiotropic effects and used a second 25OHD GWAS for replication. We identified 288 SNPs to be genome‐wide significant for 25OHD, explaining 7.0% of the variance of 25OHD levels and providing ≥90% power to detect an odds ratio (OR) of ≤ 0.97. Results MR analysis suggested that a 1 standard deviation increase in natural log‐transformed 25OHD was not associated with periodontitis risk (IVW OR = 1.04; 95% confidence interval (CI): 0.97–1.12; P‐value = 0.297). The robust models, replication, and sensitivity analyses were coherent with the primary analysis. Conclusions Collectively, our findings suggest that 25OHD levels are unlikely to have a substantial effect on the risk of periodontitis, but large long‐term RCTs are needed to derive definitive evidence on the causal role of 25OHD in periodontitis

HIV-1 Nef Interferes with Host Cell Motility by Deregulation of Cofilin

SummaryHIV-1 Nef is a key factor in AIDS pathogenesis. Here, we report that Nef potently inhibits motility of fibroblasts and chemotaxis of HIV-1-infected primary human T lymphocytes toward the chemokines SDF-1α, CCL-19, and CCL-21 ex vivo. Furthermore, Nef inhibits guided motility of zebrafish primordial germ cells toward endogenous SDF-1a in vivo. These migration defects result from Nef-mediated inhibition of the actin remodeling normally triggered by migratory stimuli. Nef strongly induces phosphorylation of cofilin, inactivating this evolutionarily conserved actin-depolymerizing factor that promotes cell motility when unphosphorylated. Nef-dependent cofilin deregulation requires association of Nef with the cellular kinase Pak2. Disruption of Nef-Pak2 association restores the cofilin phosphorylation levels and actin remodeling that facilitate cell motility. We conclude that HIV-1 Nef alters Pak2 function, which directly or indirectly inactivates cofilin, thereby restricting migration of infected T lymphocytes as part of a strategy to optimize immune evasion and HIV-1 replication

Patterns of seafloor morphology as a response to tectonic- and sedimentary processes south of the Messina Strait, Italy

The Ionian Sea between Sicily and Calabria is known for its complex geological setting, as it is located at the convergence zone of the African and Eurasian plates. The seismogenic potential in this region is manifested by several high magnitude and disastrous earthquakes like the 1908 Messina Earthquake. Furthermore, the area is affected by intense volcanism like the Aeolian Island volcanos in the Tyrrhenian Sea and Europe’s largest active volcano, Mt Etna, sitting directly at the eastern coast of Sicily. During the last years, the possible presence of Subduction Tear Edge Propagator faults (STEP-faults) has been heavily debated. The main candidates for these faults are the Ionian Fault in the Northeast and the Alfeo-Etna Fault in the Southwest of the working area between Sicily and Calabria. Nevertheless, only little is known about near seafloor deformation zones and sedimentary processes in the Ionian Sea directly south of the Messina Strait.peer-reviewe

Resource-aware Research on Universe and Matter: Call-to-Action in Digital Transformation

Given the urgency to reduce fossil fuel energy production to make climate tipping points less likely, we call for resource-aware knowledge gain in the research areas on Universe and Matter with emphasis on the digital transformation. A portfolio of measures is described in detail and then summarized according to the timescales required for their implementation. The measures will both contribute to sustainable research and accelerate scientific progress through increased awareness of resource usage. This work is based on a three-days workshop on sustainability in digital transformation held in May 2023.Comment: 20 pages, 2 figures, publication following workshop 'Sustainability in the Digital Transformation of Basic Research on Universe & Matter', 30 May to 2 June 2023, Meinerzhagen, Germany, https://indico.desy.de/event/3748

Salmonella Typhimurium Type III Secretion Effectors Stimulate Innate Immune Responses in Cultured Epithelial Cells

Recognition of conserved bacterial products by innate immune receptors leads to inflammatory responses that control pathogen spread but that can also result in pathology. Intestinal epithelial cells are exposed to bacterial products and therefore must prevent signaling through innate immune receptors to avoid pathology. However, enteric pathogens are able to stimulate intestinal inflammation. We show here that the enteric pathogen Salmonella Typhimurium can stimulate innate immune responses in cultured epithelial cells by mechanisms that do not involve receptors of the innate immune system. Instead, S. Typhimurium stimulates these responses by delivering through its type III secretion system the bacterial effector proteins SopE, SopE2, and SopB, which in a redundant fashion stimulate Rho-family GTPases leading to the activation of mitogen-activated protein (MAP) kinase and NF-κB signaling. These observations have implications for the understanding of the mechanisms by which Salmonella Typhimurium induces intestinal inflammation as well as other intestinal inflammatory pathologies

Mortality differences by partnership status in England and Wales : the effect of living arrangements or health selection?

Sebastian Franke’s research was supported by the Economic and Social Research Council [ES/J500094/1] through the North West Doctoral Training Centre Social Statistics pathway (Ph.D. project: “Health, Mortality and Partnership Status: Protection or Selection”). The permission of the Office for National Statistics to use the Longitudinal Study is gratefully acknowledged, as is the help provided by staff of the Centre for Longitudinal Study Information and User Support (CeLSIUS). CeLSIUS is supported by the ESRC Census of Population Programme (Award Ref: ES/K000365/1).This paper investigates the relationship between partnership status and mortality in England and Wales. Using data from the Office for National Statistics Longitudinal Study (ONS LS) for the period between 2001 and 2011, we examine whether married people have lower mortality levels than unmarried individuals; whether individuals who cohabit have mortality levels similar to those of married or single persons; and how much the fact that married couples live with someone rather than alone explains their low mortality. Our analysis shows first that married individuals have lower mortality than unmarried persons. Second, men and women in pre-marital unions exhibit mortality levels similar to those of married men and women, whereas mortality levels are elevated for post-marital cohabitants. Third, controlling for household size and the presence of children reduces mortality differences between married and unmarried non-partnered individuals, but significant differences persist. The study supports both protection and selection theory. The increase in mortality differences by age group between never-married cohabitants and married couples is likely a sign of the long-term accumulation of health and wealth benefits of marriage. Similar mortality levels of cohabiting and married couples at younger ages suggest that healthier individuals are more likely to find a partner.PostprintPeer reviewe