Combining chemical genomics screens in yeast to reveal spectrum of effects of chemical inhibition of sphingolipid biosynthesis

Background: Single genome-wide screens for the effect of altered gene dosage on drug sensitivity in the model organism Saccharomyces cerevisiae provide only a partial picture of the mechanism of action of a drug. Results Using the example of the tumor cell invasion inhibitor dihydromotuporamine C, we show that a more complete picture of drug action can be obtained by combining different chemical genomics approaches - analysis of the sensitivity of ρ 0 cells lacking mitochondrial DNA, drug-induced haploinsufficiency, suppression of drug sensitivity by gene overexpression and chemical-genetic synthetic lethality screening using strains deleted of nonessential genes. Killing of yeast by this chemical requires a functional mitochondrial electron-transport chain and cytochrome c heme lyase function. However, we find that it does not require genes associated with programmed cell death in yeast. The chemical also inhibits endocytosis and intracellular vesicle trafficking and interferes with vacuolar acidification in yeast and in human cancer cells. These effects can all be ascribed to inhibition of sphingolipid biosynthesis by dihydromotuporamine C. Conclusion Despite their similar conceptual basis, namely altering drug sensitivity by modifying gene dosage, each of the screening approaches provided a distinct set of information that, when integrated, revealed a more complete picture of the mechanism of action of a drug on cells.Biochemistry and Molecular Biology, Department ofCellular and Physiological Sciences, Department ofMedicine, Faculty ofNon UBCReviewedFacult

European Socialists and the State: A Comparative and Transnational Approach

Many political observers in Western democratic countries equate socialism with statism. From the late 1970s onwards, numerous socialist elites and experts have helped to nurture this widespread belief. This chapter aims to dispel this reductive, indeed incorrect, account of the relationship between West European socialism and the idea, form, and use of the state. It challenges what remains a dominant interpretation of the left’s propensity for state intervention in political and journalistic debates. It promotes a comparative and transnational approach over the longue durée, which is likely to produce a better understanding of West European socialism. In so doing, it also casts an original light on the history of the contemporary state in Europe