Hormone-stimulated modulation of endocytic trafficking in osteoclasts

Copyright @ 2012 Stenbeck, Lawrence and Albert. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc. This article has been made available through the Brunel Open Access Publishing Fund.A precise control of vesicular trafficking is crucial not only for osteoclastic bone resorption, but also for the crosstalk between osteoclasts and osteoblasts, which regulates bone homeostasis. In addition to the release of growth factors and modulators, such as glutamate, flux through the intracellular trafficking routes could also provide the osteoclast with a monitoring function of its resorption activity. To establish the signaling pathways regulating trafficking events in resorbing osteoclasts, we used the bone conserving hormone calcitonin, which has the unique property of inducing osteoclast quiescence. Calcitonin acts through the calcitonin receptor and activates multiple signaling pathways. By monitoring trafficking of a fluorescent low molecular weight probe in mature, bone resorbing osteoclasts we show for the first time that calcitonin blocks endocytosis from the ruffled border by phospholipase C (PLC) activation. Furthermore, we identify a requirement for polyunsaturated fatty acids in endocytic trafficking in osteoclasts. Inhibition of PLC prior to calcitonin treatment restores endocytosis to 75% of untreated rates. This effect is independent of protein kinase C activation and can be mimicked by an increase in intracellular calcium. We thus define an essential role for intracellular calcium levels in the maintenance of endocytosis in osteoclasts.Arthritis Research UK Grant (18197)

Internalisation of membrane progesterone receptor-α after treatment with progesterone: Potential involvement of a clathrin-dependent pathway

This article has been made available through the Brunel Open Access Publishing Fund.Internalisation and recycling of seven trans-membrane domain receptors is a critical regulatory event for their signalling. The mechanism(s) by which membrane progesterone receptor-α (mPRα) number is regulated on the cell surface is unclear. In this study, we investigated the cellular distribution of mPRα and mechanisms of mPRα trafficking using a cell line derived from a primary culture of human myometrial cells (M11) as an experimental model. RT-PCR and immunofluorescent analysis demonstrated expression of mPRα in M11 cells with mPRα primarily distributed on the cell surface under basal conditions. For the first time, plasma membrane localisation of mPRα was confirmed using immuno-gold transmission electron microscopy. Stimulation of M11 cells with progesterone (P4, 100 nM) resulted in internalisation of mPRα from the plasma membrane to the cytoplasm (10 min) and subsequent partial translocation back to the cell surface (20 min). We investigated potential endocytotic pathways involved in trafficking of mPRα after its internalisation. Partial co-localisation of clathrin with mPRα was obvious after 10 min of P4 treatment. Of note, chlorpromazine (inhibitor of clathrin-mediated pathway) inhibited the endocytosis of mPRα, whereas treatment with nystatin (inhibitor of caveolae-mediated pathway) did not affect internalisation. Collectively, these data suggest that mPRα is expressed on the cell surface of M11 cells and undergoes endocytosis after P4 stimulation primarily via a clathrin-mediated pathway.This article is available through the Brunel Open Access Publishing Fun

Architecture of coatomer: Molecular characterization of delta-COP and protein interactions within the complex

Copyright © 2011 by The Rockefeller University Press.Coatomer is a cytosolic protein complex that forms the coat of COP I-coated transport vesicles. In our attempt to analyze the physical and functional interactions between its seven subunits (coat proteins, [COPs] alpha-zeta), we engaged in a program to clone and characterize the individual coatomer subunits. We have now cloned, sequenced, and overexpressed bovine alpha-COP, the 135-kD subunit of coatomer as well as delta-COP, the 57-kD subunit and have identified a yeast homolog of delta-COP by cDNA sequence comparison and by NH2-terminal peptide sequencing. delta-COP shows homologies to subunits of the clathrin adaptor complexes AP1 and AP2. We show that in Golgi-enriched membrane fractions, the protein is predominantly found in COP I-coated transport vesicles and in the budding regions of the Golgi membranes. A knock-out of the delta-COP gene in yeast is lethal. Immunoprecipitation, as well as analysis exploiting the two-hybrid system in a complete COP screen, showed physical interactions between alpha- and epsilon-COPs and between beta- and delta-COPs. Moreover, the two-hybrid system indicates interactions between gamma- and zeta-COPs as well as between alpha- and beta' COPs. We propose that these interactions reflect in vivo associations of those subunits and thus play a functional role in the assembly of coatomer and/or serve to maintain the molecular architecture of the complex.This work was supported by The Deutsche Forschungsgemeinschaft (SFB 352), the Human Frontier Science Program, and the Swiss National Science Foundation No. 31-43366.95

Intressenternas syn på den enskilda skogsägarens Corporate Responsibility

Drygt hälften av den svenska landarealen täcks av skog. Av denna areal ägs hälften av privata skogsägare och övrig areal av skogsbolag och det allmänna. Alla som brukar skogen har ett ansvar att värna om den på ett hållbart och uthålligt sätt, detta för att kommande generationer ska kunna ha fortsatt glädje av skogen. Ett viktigt begrepp gällande hållbar utveckling är CR (Corporate Responsibility). Med detta menas att det är viktigt att intressenter tar mer ansvar inom aspekterna: miljö, socialt och ekonomi än den miniminivå som lager kräver. Vad har intressenter inom skogsnäringen för krav på skogsägarna inom ramen för CR, och kan det uppstå eventuella konflikter mellan intressenter och skogsägare? Detta är en explorativ studie där syftet är att undersöka vilka förväntningar intressenter har på enskilda skogsägares ansvarstagande inom CR. Avgränsningar kommer geografiskt sett sträcka sig inom Stockholmsområdet. Eftersom studien är explorativ och ämnet är begränsat utforskat måste ny information införskaffas. Både myndigheter och företag kommer att bidra till den empiriska studien. Syftet är att undersöka vilka faktorer och krav intressenterna anser att den enskilda skogsägaren bör sträva efter inom CR. I resultatet påvisas att trots att de olika myndigheterna är centralt styrda av staten kan deras syn på ansvar skilja sig åt. Utifrån de olika intervjuerna har kopplingar mellan hållbart skogsbruk och långsiktigt ekonomiskt vinning varit genomgående. Konflikter kan dock uppstå mellan intressenter och skogsägare när aspekter i form av makt, ändringar av skogsvårdslagen och ekonomiska intressen ställas mot varandra.More than half of the Swedish land area is covered by forest. About 50 percent is owned by forestry companies, and the other 50 percent is owned by private forest owners. All users of the forest have a responsibility to manage the forest in a sustainable manner. This is so that future generations can enjoy the same pleasure from the woods we do. An important concept on forest sustainable development is CR (corporate responsibility). This means that it is important that the owner and manager take more responsibility for the environmental, social and economic perspectives than the law requires. What does stakeholders in the forestry sector require from a CR perspective, may there be potential conflicts between stakeholders and forest owners? This is an exploratory study that aims to examine factors and requirements that individual owners should strive for in their CR. Since the study is exploratory and the subject is not studied before, new information must be gathered. This will be done through interviews with stakeholders. Both authorities and public companies will contribute to the empirical study. The results demonstrate that although the various authorities are centrally controlled by the government, their views on CR are different. From the various interviews, the link between sustainable forest management and long-term financial gain has been consistent. The results also show that conflicts may arise between stakeholders and owners, when elements such as power, changes to the Forestry Act and economic interests are put together

Förenkling, inte alltid så enkelt - En studie om Bokföringsnämndens K-projekt

Syfte: Att identifiera problematik med K-projektet i praktiken. Metod: Studien använder en induktiv ansats och en kvalitativ forskningsmetod. Arbetsprocessen baseras på grundad teori. Teoretiskt perspektiv:Enligt American Accounting Association är redovisning ett ämne som är svårt att fånga i teoretiska modeller. Denna uppsats använder istället samhällsutvecklande teorier av Sten Jönsson och Anthony Puxty et al. för att beskriva viktiga faktorer som påverkar reglering av redovisning. Empiri:Studiens empiri består av primärdata insamlad genom semistrukturerade intervjuer med revisorer och redovisningsexperter, samt av sekundärdata från litteratur och offentliga debatt. Resultat:Studien intar en ifrågasättande hållning till K-projektet och presenterar ett kritiskt perspektiv till det sätt som redovisning regleras i Sverige. Ett av de största problemen är att K-projektet är politiskt initierat och inte tar nog hänsyn till de behov som finns ute hos företagen. Samtidigt är Bokföringsnämnden tilldelade för lite resurser för att på ett tillfredsställande sätt kunna kommunicera med omvärlden. Det har heller inte kunnat påvisas att K-projektet faktiskt kommer att leda till en förenklad redovisning. Dock är det ännu för tidigt för att helt utvärdera projektet

Avoidable cancers in the Nordic countries-the potential impact of increased physical activity on postmenopausal breast, colon and endometrial cancer

Background: Physical activity has been shown to reduce the risk of colon, endometrial and postmenopausal breast cancer. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to insufficient levels of leisure time physical activity and estimate the potential for cancer prevention for these three sites by increasing physical activity levels. Methods: Using the Prevent macrosimulation model, the number of cancer cases in the Nordic countries over a 30-year period (2016-2045) was modelled, under different scenarios of increasing physical activity levels in the population, and compared with the projected number of cases if constant physical activity prevailed. Physical activity (moderate and vigorous) was categorised according to metabolic equivalents (MET) hours in groups with sufficient physical activity (15+ MET-hours/week), low deficit (9 to Results: If no one had insufficient levels of physical activity, about 11,000 colon, endometrial and postmenopausal breast cancer cases could be avoided in the Nordic countries in a 30-year period, which is 1% of the expected cases for the three cancer types. With a 50% reduction in all deficit groups by 2025 or a 100% reduction in the group of high deficit, approximately 0.5% of the expected cases for the three cancer types could be avoided. The number and percentage of avoidable cases was highest for colon cancer. Conclusion: 11,000 cancer cases could be avoided in the Nordic countries in a 30-year period, if deficit in physical activity was eliminated. (C) 2019 Elsevier Ltd. All rights reserved.Peer reviewe