Recruitment of the Major Vault Protein by InlK: A Listeria monocytogenes Strategy to Avoid Autophagy

L. monocytogenes is a facultative intracellular bacterium responsible for listeriosis. It is able to invade, survive and replicate in phagocytic and non-phagocytic cells. The infectious process at the cellular level has been extensively studied and many virulence factors have been identified. Yet, the role of InlK, a member of the internalin family specific to L. monocytogenes, remains unknown. Here, we first show using deletion analysis and in vivo infection, that InlK is a bona fide virulence factor, poorly expressed in vitro and well expressed in vivo, and that it is anchored to the bacterial surface by sortase A. We then demonstrate by a yeast two hybrid screen using InlK as a bait, validated by pulldown experiments and immunofluorescence analysis that intracytosolic bacteria via an interaction with the protein InlK interact with the Major Vault Protein (MVP), the main component of cytoplasmic ribonucleoproteic particules named vaults. Although vaults have been implicated in several cellular processes, their role has remained elusive. Our analysis demonstrates that MVP recruitment disguises intracytosolic bacteria from autophagic recognition, leading to an increased survival rate of InlK over-expressing bacteria compared to InlK− bacteria. Together these results reveal that MVP is hijacked by L. monocytogenes in order to counteract the autophagy process, a finding that could have major implications in deciphering the cellular role of vault particles

Cognitieve revalidatie voor kinderen en jongeren met niet-aangeboren hersenletsel:wat zijn de effectieve componenten?

Veel kinderen en jongeren met niet-aangeboren hersenletsel (nah) ervaren problemen met cognitief functioneren, zoals een verminderd geheugen of slechtere concentratie. Dit artikel is gebaseerd op bevindingen en inzichten uit het proefschrift ‘executive functions of children and adolescents: novel perspectives on assessment and intervention’. Een belangrijk doel van het promotietraject was beter inzicht te krijgen in hoe we cognitieve functies en bijbehorende problemen bij kinderen en jongeren met nah kunnen verbeteren. Cognitieve problemen bij kinderen en jongeren kunnen mogelijk worden behandeld met cognitieve revalidatie. Interventies voor cognitieve revalidatie kunnen worden gecategoriseerd op basis van hun hoofdcomponenten: 1) strategiegebruik en/of metacognitie, 2) herhaald oefenen, en 3) externe hulpmiddelen. Resultaten van een literatuurstudie naar cognitieve revalidatie laten zien dat door interventies die zijn gebaseerd op metacognitie en/of strategiegebruik vooral adaptief gedrag en sociaal functioneren verbeteren. Interventies op basis van herhaald oefenen verbeterden de prestaties op taken die vergelijkbaar zijn met de geoefende taken. Multi-componenten-interventies die deze twee componenten combineren, leken te leiden tot verbeteringen in zowel cognitief als adaptief gedrag en sociaal functioneren. Externe hulpmiddelen verbeterden het functioneren in het specifieke gebied waarop het hulpmiddel was gericht, bijvoorbeeld het geheugen. De beschikbare gegevens suggereren dat interventies bestaande uit meerdere componenten, zoals een combinatie van metacognitie- en/of strategiegebruik en herhaald oefenen, veelbelovend zijn, omdat deze kunnen leiden tot verbeteringen in zowel het cognitieve als psychosociale functioneren van kinderen en adolescenten met nah

Intersection of phosphate transport, oxidative stress and TOR signalling in Candida albicans virulence

Phosphate is an essential macronutrient required for cell growth and division. Pho84 is the major high-affinity cell-surface phosphate importer of Saccharomyces cerevisiae and a crucial element in the phosphate homeostatic system of this model yeast. We found that loss of Candida albicans Pho84 attenuated virulence in Drosophila and murine oropharyngeal and disseminated models of invasive infection, and conferred hypersensitivity to neutrophil killing. Susceptibility of cells lacking Pho84 to neutrophil attack depended on reactive oxygen species (ROS): pho84-/- cells were no more susceptible than wild type C. albicans to neutrophils from a patient with chronic granulomatous disease, or to those whose oxidative burst was pharmacologically inhibited or neutralized. pho84-/- mutants hyperactivated oxidative stress signalling. They accumulated intracellular ROS in the absence of extrinsic oxidative stress, in high as well as low ambient phosphate conditions. ROS accumulation correlated with diminished levels of the unique superoxide dismutase Sod3 in pho84-/- cells, while SOD3 overexpression from a conditional promoter substantially restored these cells’ oxidative stress resistance in vitro. Repression of SOD3 expression sharply increased their oxidative stress hypersensitivity. Neither of these oxidative stress management effects of manipulating SOD3 transcription was observed in PHO84 wild type cells. Sod3 levels were not the only factor driving oxidative stress effects on pho84-/- cells, though, because overexpressing SOD3 did not ameliorate these cells’ hypersensitivity to neutrophil killing ex vivo, indicating Pho84 has further roles in oxidative stress resistance and virulence. Measurement of cellular metal concentrations demonstrated that diminished Sod3 expression was not due to decreased import of its metal cofactor manganese, as predicted from the function of S. cerevisiae Pho84 as a low-affinity manganese transporter. Instead of a role of Pho84 in metal transport, we found its role in TORC1 activation to impact oxidative stress management: overexpression of the TORC1-activating GTPase Gtr1 relieved the Sod3 deficit and ROS excess in pho84-/- null mutant cells, though it did not suppress their hypersensitivity to neutrophil killing or hyphal growth defect. Pharmacologic inhibition of Pho84 by small molecules including the FDA-approved drug foscarnet also induced ROS accumulation. Inhibiting Pho84 could hence support host defenses by sensitizing C. albicans to oxidative stress

NMR-based metabolomics: quality and authenticity of plant-based foods

Nowadays metabolomics is a widely accepted approach in several scientific disciplines, especially in food science. The possibility to identify a wide range of metabolites (untargeted analysis) allowed to evaluate various food characteristics, regarding quality, adulteration, geographical origin, as well as secondary species-specific metabolites endowed with nutraceutical properties. In the present chapter, latest findings of plant-based foods investigated by NMR-based metabolomics are presented. Almost all of the recent studies were focused on quality assessment and authenticity; different aspects such as geographical origin, metabolic modifications upon stress, nutraceutical properties, and fraud detection are described as well. The here reported plant-based foods are balsamic and traditional balsamic vinegars, cereals, cocoa, coffee, fruits, legumes, spices, vegetables and vegetable oils, wine, beer, and spirits. A brief paragraph is concerning organic and conventional foods, which is a new growing scientific field of interest for researchers encouraged by the increasing consumers’ demand. The results here reported testify the capability and the power of this approach thus endorsing NMR spectroscopy as a valid alternative or complement to the chemical and physical analysis nowadays routinely applied for the quality assessment