A pathological feature of Parkinson's disease is the presence of Lewy bodies within selectively vulnerable neurons. These are ubiquitinated cytoplasmic inclusions containing ␣-synuclein, an abundant protein normally associated with presynaptic terminals. Point mutations in the ␣-synuclein gene (A30P and A53T), as well as triplication of the wild-type (WT) locus, have been linked to autosomal dominant Parkinson's. How these alterations might contribute to disease progression is unclear. Using the genetically tractable yeast Saccharomyces cerevisiae as a model system, we find that both the WT and the A53T isoforms of ␣-synuclein initially localize to the plasma membrane, to which they are delivered via the classical secretory pathway. In contrast, the A30P mutant protein disperses within the cytoplasm and does not associate with the plasma membrane, and its intracellular distribution is unaffected by mutations in the secretory pathway. When their expression is elevated, WT and A53T, but not A30P, are toxic to cells. At moderate levels of expression, WT and A53T induce the cellular stress (heat-shock) response and are toxic to cells bearing mutations in the 20S proteasome. Our results reveal a link between plasma membrane targeting of ␣-synuclein and its toxicity in yeast and suggest a role for the quality control (QC) system in the cell's effort to deal with this natively unfolded protein.

We report the results of a genetic screen designed to identify transcriptional coregulators of yeast heatshock factor (HSF). This sequence-specific activator is required to stimulate both basal and induced transcription; however, the identity of factors that collaborate with HSF in governing noninduced heatshock gene expression is unknown. In an effort to identify these factors, we isolated spontaneous extragenic suppressors of hsp82-DHSE1, an allele of HSP82 that bears a 32-bp deletion of its high-affinity HSF-binding site, yet retains its two low-affinity HSF sites. Nearly 200 suppressors of the null phenotype of hsp82-DHSE1 were isolated and characterized, and they sorted into six expression without heat-shock element (EWE) complementation groups. Strikingly, all six groups contain alleles of genes that encode subunits of Mediator. Three of the six subunits, Med7, Med10/Nut2, and Med21/Srb7, map to Mediator's middle domain; two subunits, Med14/Rgr1 and Med16/Sin4, to its tail domain; and one subunit, Med19/Rox3, to its head domain. Mutations in genes encoding these factors enhance not only the basal transcription of hsp82-DHSE1, but also that of wild-type heat-shock genes. In contrast to their effect on basal transcription, the more severe ewe mutations strongly reduce activated transcription, drastically diminishing the dynamic range of heat-shock gene expression. Notably, targeted deletion of other Mediator subunits, including the negative regulators Cdk8/Srb10, Med5/Nut1, and Med15/Gal11 fail to derepress hsp82-DHSE1. Taken together, our data suggest that the Ewe subunits constitute a distinct functional module within Mediator that modulates both basal and induced heat-shock gene transcription. W HEN exposed to thermal or chemical stress, organisms respond by vigorously transcribing genes encoding heat-shock proteins (HSPs). HSPs function as molecular chaperones and protect the cellalong with ubiquitin, proteases, metallothioneins, and antioxidant enzymes-from damage caused by the expression of misfolded proteins. In the yeast Saccharomyces cerevisiae, the expression of heat-responsive genes is stimulated by the sequence-specific transcriptional activator heat-shock factor (HSF) Hsf1 (ScHSF) (Sorger and Pelham 1988;Nieto-Sotelo et al. 1990;Sorger 1990). In response to metabolic, oxidative, or osmotic stress, the transcription of a number of HSP genes is additionally enhanced by the gene-specific activators Msn2/Msn4 and Skn7 (Boy-Marcotte et al. 1998;Treger et al. 1998;Gasch et al. 2000;Raitt et al. 2000;Amoros and Estruch 2001;Kandror et al. 2004). Nonetheless, the only activator known to promote basal heat-shock gene transcription is HSF (McDaniel et al. 1989;Park and Craig 1989;Erkine et al. 1996). Whether this basal expression is an indirect consequence of HSF's role in establishing and maintaining a nucleosomeremodeled (''nucleosome-free'') structure over the transcription start site Erkine et al. 1996), or whether HSF plays a more direct role in recruiting transcriptional coactivators under n...

Background Whether percutaneous coronary intervention (PCI) improves clinical outcomes in patients with chronic angina and stable coronary artery disease (CAD) has been a continuing area of investigation for more than two decades. The recently reported results of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches, the largest prospective trial of optimal medical therapy (OMT) with or without myocardial revascularization, provides a unique opportunity to determine whether there is an incremental benefit of revascularization in stable CAD patients.Methods Scientific databases and websites were searched to find randomized clinical trials (RCTs). Pooled risk ratios were calculated using the random-effects model. ResultsData from 10 RCTs comprising 12 125 patients showed that PCI, when added to OMT, were not associated with lower all-cause mortality (risk ratios, 0.96; 95% CI, 0.87-1.08), cardiovascular mortality (risk ratios, 0.91; 95% CI, 0.79-1.05) or myocardial infarction (MI) (risk ratios, 0.90; 95% CI, 0.78-1.04) as compared with OMT alone. However, OMT+PCI was associated with improved anginal symptoms and a lower risk for revascularization (risk ratios, 0.52; 95% CI, 0.37-0.75). ConclusionsIn patient with chronic stable CAD (without left main disease or reduced ejection fraction), PCI in addition to OMT did not improve mortality or MI compared to OMT alone. However, this strategy is associated with a lower rate of revascularization and improved anginal symptoms.

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