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The dynamic nature of the actin cytoskeleton controls many cellular processes and a loss of its plasticity has been linked to accelerated cell ageing. Cofilin is an actin-binding protein that controls actin dynamics and is linked to mitochondrial signalling pathways that control drug resistance and cell death. Here we show that cofilin driven stabilisation of actin dynamics leads to a loss in cell wall integrity, vacuole fragmentation and disruption of lipid homeostasis, lipid droplet accumulation and the promotion of necrosis. Our data suggest that these phenotypes are triggered by the inappropriate activation of Protein Kinase C (PKC) which leads to constitutive MAPK signalling. Cofilin-driven activation of the MAPK Slt2 requires the presence of the voltage dependent anion channel (VDAC), which resides in the mitochondrial outer membrane, referred to as Porin 1 (Por1) in yeast. This provides further evidence for a link between actin regulation and mitochondrial signalling. Porin has recently been implicated in lipid transport and we find that prevention of excessive lipid droplet accumulation, achieved by deleting the LRO1 and DGA1 genes, was sufficient to prevent Slt2 activation and restore cellular homeostasis in actin stabilised cells. These data suggest that the integrity of the actin cytoskeleton is essential to maintain the fidelity of MAPK signalling and that this in turn is crucial for the maintenance of lipid homeostasis and cell health in S. cerevisiae. Our data also suggest that chronic actin stabilisation leads to mitochondrial VDAC-dependent Slt2 activation and altered, pro-death, cell fate in yeast cells.

Farnesyltransferase inhibitors (FTIs) are focus for the treatment of several diseases, particularly in the field of cancer therapy. Their potential, however, goes even further, as a number of studies have evaluated FTIs for the treatment of infectious diseases such as malaria, African sleeping sickness, leishmaniosis, and hepatitis D virus infection. Little is known about protein prenylation mechanisms in human pathogens. However, disruption of IspA, a gene encoding the geranyltranstransferase of Staphylococcus aureus (S. aureus) leads to reprogramming of cellular behavior as well as impaired growth and decreased resistance to cell wall-targeting antibiotics. We used an agar well diffusion assay and a time kill assay and determined the minimum inhibitory concentrations of the FTIs lonafarnib and tipifarnib. Additionally, we conducted cell viability assays. We aimed to characterize the effect of these FTIs on S. aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis (S. epidermidis), Escherichia coli (E. coli), Enterococcus faecium (E. faecium), Klebsiella pneumoniae (K. pneumoniae), Pseudomonas aeruginosa (P. aeruginosa), and Streptococcus pneumoniae (S. pneumoniae). Both the FTIs lonafarnib and tipifarnib were capable of inhibiting the growth of the Gram-positive bacteria S. aureus, MRSA, S. epidermidis, and S. pneumoniae, whereas no effect was observed on Gram-negative bacteria. The analysis of the impact of lonafarnib and tipifarnib on common human pathogens might lead to novel insights into their defense mechanisms and therefore provide new therapeutic targets for antibiotic-resistant bacterial infections.

Hereditary spastic paraplegias, a group of neurodegenerative disorders, can be caused by loss-of-function mutations in the protein spartin. However, the physiological role of spartin remains largely elusive. Here we show that heterologous expression of human or Drosophila spartin extends chronological lifespan of yeast, reducing age-associated ROS production, apoptosis, and necrosis. We demonstrate that spartin localizes to the proximity of mitochondria and physically interacts with proteins related to mitochondrial and respiratory metabolism. Interestingly, Nde1, the mitochondrial external NADH dehydrogenase, and Pda1, the core enzyme of the pyruvate dehydrogenase complex, are required for spartin-mediated cytoprotection. Furthermore, spartin interacts with the glycolysis enhancer phospo-fructo-kinase-2,6 (Pfk26) and is sufficient to complement for PFK26-deficiency at least in early aging. We conclude that mitochondria-related energy metabolism is crucial for spartin’s vital function during aging and uncover a network of specific interactors required for this function.

The loss of lipid homeostasis can lead to lipid overload and is associated with a variety of disease states. However, little is known as to how the disruption of lipid regulation or lipid overload affects cell survival. In this study we investigated how excess diacylglycerol (DG), a cardinal metabolite suspected to mediate lipotoxicity, compromises the survival of yeast cells. We reveal that increased DG achieved by either genetic manipulation or pharmacological administration of 1,2-dioctanoyl-sn-glycerol (DOG) triggers necrotic cell death. The toxic effects of DG are linked to glucose metabolism and require a functional Rim101 signaling cascade involving the Rim21-dependent sensing complex and the activation of a calpain-like protease. The Rim101 cascade is an established pathway that triggers a transcriptional response to alkaline or lipid stress. We propose that the Rim101 pathway senses DG-induced lipid perturbation and conducts a signaling response that either facilitates cellular adaptation or triggers lipotoxic cell death. Using established models of lipotoxicity, i.e., high-fat diet in Drosophila and palmitic acid administration in cultured human endothelial cells, we present evidence that the core mechanism underlying this calpain-dependent lipotoxic cell death pathway is phylogenetically conserved.

Lipotoxicity is a pathophysiological process triggered by lipid overload. In metazoans, lipotoxicity is characterised by the ectopic deposition of lipids on organs other than adipose tissue. This leads to organ dysfunction, cell death, and is intimately linked to lipid-associated diseases such as cardiac dysfunction, atherosclerosis, stroke, hepatosteatosis, cancer and the metabolic syndrome. The molecules involved in eliciting lipotoxicity include FAs and their acyl-CoA derivatives, triacylglycerol (TG), diacylglycerol (DG), ceramides, acyl-carnitines and phospholipids. However, the cellular transport of toxic lipids through membrane contact sites (MCS) and vesicular mechanisms as well as lipid metabolism that progress lipotoxicity to the onset of disease are not entirely understood. Yeast has proven a useful model organism to study the molecular mechanisms of lipotoxicity. Recently, the Rim101 pathway, which senses alkaline pH and the lipid status at the plasmamembrane, has been connected to lipotoxicity. In this review article, we summarise recent research advances on the Rim101 pathway and MCS in the context of lipotoxicity in yeast and present a perspective for future research directions., In this review article, we summarise recent research advances on the topic of lipotoxicity in yeast and present a perspective for future research directions.

Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cel-lular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the defi-nition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differ-ential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death rou-tines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the au-thors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the pro-gress of this vibrant field of research., info:eu-repo/semantics/published

To obtain mechanistic insights into the cross talk between lipolysis and autophagy, two key metabolic responses to starvation, we screened the autophagy-inducing potential of a panel of fatty acids in human cancer cells. Both saturated and unsaturated fatty acids such as palmitate and oleate, respectively, triggered autophagy, but the underlying molecular mechanisms differed. Oleate, but not palmitate, stimulated an autophagic response that required an intact Golgi apparatus. Conversely, autophagy triggered by palmitate, but not oleate, required AMPK, PKR and JNK1 and involved the activation of the BECN1/PIK3C3 lipid kinase complex. Accordingly, the downregulation of BECN1 and PIK3C3 abolished palmitate-induced, but not oleate-induced, autophagy in human cancer cells. Moreover, Becn1(+/-) mice as well as yeast cells and nematodes lacking the ortholog of human BECN1 mounted an autophagic response to oleate, but not palmitate. Thus, unsaturated fatty acids induce a non-canonical, phylogenetically conserved, autophagic response that in mammalian cells relies on the Golgi apparatus.

Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.

Background: Accumulation of palmitic acid in endothelial cells induces cellular dysfunction and death. Results: Palmitic acid triggers Ca2+-dependent autophagy, which results in programmed necrotic death (necroptosis) of endothelial cells. Conclusion: Autophagy promotes lipotoxic signaling of palmitic acid in endothelial cells leading to necroptosis. Significance: Showing a new molecular mechanism of palmitic acid-induced cytotoxicity may reveal novel strategies in the treatment of diseases related to lipid overload., Accumulation of palmitic acid (PA) in cells from nonadipose tissues is known to induce lipotoxicity resulting in cellular dysfunction and death. The exact molecular pathways of PA-induced cell death are still mysterious. Here, we show that PA triggers autophagy, which did not counteract but in contrast promoted endothelial cell death. The PA-induced cell death was predominantly necrotic as indicated by annexin V and propidium iodide (PI) staining, absence of caspase activity, low levels of DNA hypoploidy, and an early ATP depletion. In addition PA induced a strong elevation of mRNA levels of ubiquitin carboxyl-terminal hydrolase (CYLD), a known mediator of necroptosis. Moreover, siRNA-mediated knockdown of CYLD significantly antagonized PA-induced necrosis of endothelial cells. In contrast, inhibition and knockdown of receptor interacting protein kinase 1 (RIPK1) had no effect on PA-induced necrosis, indicating the induction of a CYLD-dependent but RIPK1-independent cell death pathway. PA was recognized as a strong and early inducer of autophagy. The inhibition of autophagy by both pharmacological inhibitors and genetic knockdown of the autophagy-specific genes, vacuolar protein sorting 34 (VPS34), and autophagy-related protein 7 (ATG7), could rescue the PA-induced death of endothelial cells. Moreover, the initiation of autophagy and cell death by PA was reduced in endothelial cells loaded with the Ca2+ chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid-(acetoxymethyl) ester (BAPTA-AM), indicating that Ca2+ triggers the fatal signaling of PA. In summary, we introduce an unexpected mechanism of lipotoxicity in endothelial cells and provide several novel strategies to counteract the lipotoxic signaling of PA.

The activation of ceramide-generating enzymes, the blockade of ceramide degradation, or the addition of ceramide analogues can trigger apoptosis or necrosis in human cancer cells. Moreover, endogenous ceramide plays a decisive role in the killing of neoplastic cells by conventional anticancer chemotherapeutics. Here, we explored the possibility that membrane-permeable C2-ceramide might kill budding yeast (Saccharomyces cerevisiae) cells under fermentative conditions, where they exhibit rapid proliferation and a Warburg-like metabolism that is reminiscent of cancer cells. C2-ceramide efficiently induced the generation of reactive oxygen species (ROS), as well as apoptotic and necrotic cell death, and this effect was not influenced by deletion of the sole yeast metacaspase. However, C2-ceramide largely failed to cause ROS hypergeneration and cell death upon deletion of the mitochondrial genome. Thus, mitochondrial function is strictly required for C2-ceramide-induced yeast lethality. Accordingly, mitochondria from C2-ceramide-treated yeast cells exhibited major morphological alterations including organelle fragmentation and aggregation. Altogether, our results point to a pivotal role of mitochondria in ceramide-induced yeast cell death.

Mitochondrial outer membrane permeabilization is a watershed event in the process of apoptosis, which is tightly regulated by a series of pro- and anti-apoptotic proteins belonging to the BCL-2 family, each characteristically possessing a BCL-2 homology domain 3 (BH3). Here, we identify a yeast protein (Ybh3p) that interacts with BCL-XL and harbours a functional BH3 domain. Upon lethal insult, Ybh3p translocates to mitochondria and triggers BH3 domain-dependent apoptosis. Ybh3p induces cell death and disruption of the mitochondrial transmembrane potential via the mitochondrial phosphate carrier Mir1p. Deletion of Mir1p and depletion of its human orthologue (SLC25A3/PHC) abolish stress-induced mitochondrial targeting of Ybh3p in yeast and that of BAX in human cells, respectively. Yeast cells lacking YBH3 display prolonged chronological and replicative lifespans and resistance to apoptosis induction. Thus, the yeast genome encodes a functional BH3 domain that induces cell death through phylogenetically conserved mechanisms.

Obesity is characterised by lipid accumulation in non-adipose tissues, leading to organ degeneration and a wide range of diseases, including diabetes, heart attack and liver cirrhosis. Free fatty acids (FFA) are believed to be the principal toxic triggers mediating the adverse cellular effects of lipids. Here, we show that various cooking oils used in human nutrition cause cell death in yeast in the presence of a triacylglycerol lipase, mimicking the physiological microenvironment of the small intestine. Combining genetic and cell death assays, we demonstrate that elevated FFA concentrations lead to necrotic cell death, as evidenced by loss of membrane integrity and release of nuclear HMGB1. FFA-mediated necrosis depends on functional mitochondria and leads to the accumulation of reactive oxygen species. We conclude that lipotoxicity is executed via a mitochondrial necrotic pathway, challenging the dogma that the adverse effects of lipid stress are exclusively apoptotic.

Epidemiological studies propose that extension of the human lifespan or the reduction of age associated diseases may be achieved by physical exercise, caloric restriction, and by consumption of certain substances such as resveratrol, selenium, flavonoids, zinc, omega 3 unsaturated fatty acids, vitamins E and C, Ginkgo biloba extracts, aspirin, green tea catechins, antioxidants in general, and even by light caffeine or alcohol consumption. Though intriguing, these studies only show correlative (not causative) effects between the application of the particular substance and longevity. On the other hand, obesity is yet a strong menace to the western society and it will emerge even more so throughout the next decades according to the prediction of the WHO. Although obesity is considered a severe problem, very little is known about the molecular mechanisms causing the associated degeneration of organs and finally death. Nutrient related adverse consequences for health and thus ageing may be due to a high sugar or high fat diet, excessive alcohol consumption and cigarette smoke amongst others. In this article we examine the interdependencies of eating and ageing and suggest yeast, one of the most successful ageing models, as an easy tool to elucidate the molecular pathways from eating to ageing. The conservation of most ageing pathways in yeast and their easy genetic tractability may provide a chance to discriminate between the correlative and causative effects of nutrition on ageing.

Spermidine is a natural polyamine involved in many important cellular functions, whose supplementation in food or water increases life span and stress resistance in several model organisms. In this work, we expand spermidine's range of age-related beneficial effects by demonstrating that it is also able to improve locomotor performance in aged flies. Spermidine's mechanism of action on aging has been primarily related to general protein hypoacetylation that subsequently induces autophagy. Here, we suggest that the molecular targets of spermidine also include lipid metabolism: Spermidine-fed flies contain more triglycerides and show altered fatty acid and phospholipid profiles. We further determine that most of these metabolic changes are regulated through autophagy. Collectively, our data suggests an additional and novel lipid-mediated mechanism of action for spermidine-induced autophagy. Publisher PDF

Mitochondrial outer membrane permeabilization is a watershed event in the process of apoptosis, which is tightly regulated by a series of pro- and anti-apoptotic proteins belonging to the BCL-2 family, each characteristically possessing a BCL-2 homology domain 3 (BH3). Here, we identify a yeast protein (Ybh3p) that interacts with BCL-X(L) and harbours a functional BH3 domain. Upon lethal insult, Ybh3p translocates to mitochondria and triggers BH3 domain-dependent apoptosis. Ybh3p induces cell death and disruption of the mitochondrial transmembrane potential via the mitochondrial phosphate carrier Mir1p. Deletion of Mir1p and depletion of its human orthologue (SLC25A3/PHC) abolish stress-induced mitochondrial targeting of Ybh3p in yeast and that of BAX in human cells, respectively. Yeast cells lacking YBH3 display prolonged chronological and replicative lifespans and resistance to apoptosis induction. Thus, the yeast genome encodes a functional BH3 domain that induces cell death through phylogenetically conserved mechanisms.

Cell cycle control plays a central role in the development and homeostasis of multicellular organisms. Mis-regulation of cell cycles often leads to abnormal tissue sizes and functions in development and can cause various diseases.1 Even though many pathways controlling the cell cycle machinery have been characterized, the signals regulating the cell cycle during development remain poorly understood. The stereotyped nuclear division pattern in the early Drosophila embryonic development has been a good model system to study how development and cell cycle are co-regulated.2 Drosophila embryos develop as a syncytium and undergo thirteen rounds of synchronous mitosis without cytokinesis generating about six thousand nuclei in a common cytoplasm. Subsequently, embryos pause in the interphase of cycle 14 for approximately 1 hour when cellularization, a specialized form of cytokinesis, encloses nuclei into cell membranes. After cellularization, embryos undergo rapid morphogenetic changes (gastrulation) and individual cells resume mitosis asynchronously forming different mitotic domains. The transition from the early synchronous division to cell cycle pause, onset of morphogenetic change and asynchronous cell cycle is similar to the transition observed in other metazoa and is known as “mid-blastula transition” (MBT). The mechanism controlling the onset of the MBT seems to monitor the nucleocytoplasmic (N/C) ratio,3,4 i.e., the ratio of DNA content to unknown cytoplasmic factor(s). During the early syncytial cycles, this ratio is low enough to allow the next nuclear division, such that the DNA content of the embryo continues to double with each cycle. It has been proposed that when this ratio passes a pre-set threshold, all the phenomena of MBT, including cell cycle arrest, take place. However, how nuclei sense or measure the N/C ratio and how they achieve the synchronous divisions preceding the MBT remain unknown. To address these questions, we have used a series of compound fly stocks to generate embryos with different amount of DNA, thus different values of N/C ratio during early divisions.5 We found that the threshold for the N/C ratio to trigger MBT is about 70% of wild-type DNA (Fig. 1A): above this threshold, embryos behave like wild-type embryo, pausing at interphase of cycle 14; below the threshold, embryos undergo one extra mitosis and pause in the interphase of cycle 15. We were intrigued to observe that embryos with N/C values close to the threshold frequently form mitotic patches, with one part pausing in one cycle and the rest undergoing an extra mitosis and pausing in the next cycle. Embryos from cross C(3R);F(3L) × C(3)EN, which gave highest percentage of patchy embryos, were collected, stained with Hoechst dye to visualize DNA and examined for geometric characteristics of the mitotic patches. Cycle 15 patches occupy on average 74.5% of the whole c14/c15 embryo area with standard deviation of ±12.7% (n = 12) while the position of the patches is variable (Fig. 1B). To explain the formation of the mitotic patches, we consider three possible models. First, in what we refer to as the “independence model,” individual nuclei make independent decisions for whether entering next division cycle. If the N/C ratio is measured and the decision to pause is made immediately at the MBT, the nuclear distributions in patchy embryos with threshold DNA contents should show a salt and pepper pattern. However the large mitotic patches actually observed are not compatible with such a model. Using a statistical mechanics model to analyze the distribution of random cluster sizes on a lattice,6 we show that the observed pattern of nuclear density is incompatible with the independent decisions made at cycle 14 (p value < 10^–240). An alternative explanation for the large patch size is that the N/C ratio is measured at an earlier stage and “remembered” in all the progeny of a given nucleus, resulting in a large patch of coherent lineage-related nuclei. To test this possibility, we introduced the Histone-GFP transgene into the compound stocks used to produce embryos with threshold DNA content and used live-imaging to determine if two sister nuclei descending from the same mother nucleus immediately prior to the MBT cell cycle decision always divide in the same way as would be predicted in the lineage model. We monitored the dynamics of patch formation in five embryos and focused our analysis on the nuclei at the boundary between the patches, since these nuclei can provide the required information to link lineage and different division behaviors. As shown in Figure 1C and Supplementary Movie 1, the mother nucleus labeled with a red dot divides into two daughter nuclei. Subsequently, one of the daughter nuclei divides again while the other arrests in interphase. This is the case for 4 out of 11 boundary nuclei we tracked. This observation argues that the decision to divide is made immediately before the MBT and that the coherent behavior of adjacent nuclei cannot be attributed to their common lineage. Instead, the coherent behavior suggests that the decision to arrest the cell cycle may be made collectively by neighboring nuclei through the exchange of some unknown molecule(s). Alternatively, it may reflect subtle local inhomogeneities in the cytoplasmic component of the N/C ratio that only impact the cell cycle decision when DNA content is close to threshold values. Figure 1 Patchy cell cycle pause during Drosophila mid-blastula transition. (A) Cell cycle behaviors of embryos with different amount of DNA compared with wild-type. Below the threshold of 70%, embryos undergo one extra division. Above the threshold, embryos pause ... We favor the communication model because it provides the embryo with a mechanism ensuring coherent behavior across all nuclei during MBT even if individual nuclei make errors in the measurement of the N/C ratio or if the level of the cytoplasmic component is subject to local fluctuations. Communication between nuclei would dampen this randomness and may also synchronize the behavior of individual nuclei during the earlier stage of embryonic development, when nuclei undergo synchronous wave-like cleavage divisions. Similar community effects have also been suggested to generate homogeneity during Xenopus embryonic development and organismal level organization for cell cycle regulation may be a general feature of many organisms.7 It would be interesting to know the molecular nature of the exchanged information and if such inter-nuclear or inter-cellular signaling pathways are conserved. We suggest that molecular and genetic approaches might reveal the nature of the exchange molecules.

Yeast has been a valuable model to study replicative and chronological ageing processes. Replicative ageing is defined by the number of daughter cells a mother can give birth to and hence reflects the ageing situation in proliferating cells, whereas chronological ageing is widely accepted as a model for postmitotic tissue ageing. Since both ageing forms end in yeast programmed death (necrotic and apoptotic), and abrogation of cell death by deletion of the apoptotic machinery or diminishment of oxidative radicals leads to longevity, apoptosis and ageing seem closely connected. This review focuses on ageing as a physiological way to induce yeast apoptosis, which unexpectedly defines apoptosis as a pro- and not an anti-ageing mechanism.

Ethanolamine (Etn) is a naturally occurring aminoalcohol necessary for synthesis of the phospholipid phosphatidylethanolamine (PE), a major component of biological membranes. We recently reported that Etn treatment increases cellular PE levels, thereby inducing cytoprotective autophagy and protecting against aging across species.

Understanding the mechanisms of Salmonella virulence is an important challenge. The capacity of this intracellular bacterial pathogen to cause diseases depends on the expression of virulence factors including the second type III secretion system (TTSS-2), which is used to translocate into the eukaryotic cytosol a set of effector proteins that divert the biology of the host cell and shape the bacterial replicative niche. Yet little is known about the eukaryotic functions affected by individual Salmonella effectors. Here we report that the TTSS-2 effector PipB2 interacts with the kinesin light chain, a subunit of the kinesin-1 motor complex that drives anterograde transport along microtubules. Translocation of PipB2 is both necessary and sufficient for the recruitment of kinesin-1 to the membrane of the Salmonella -containing vacuole. In vivo , PipB2 contributes to the attenuation of Salmonella mutant strains in mice. Taken together, our data indicate that the TTSS-2-mediated fine-tuning of kinesin-1 activity associated with the bacterial vacuole is crucial for the virulence of Salmonella .

This spring, more than a hundred scientists from around the world gathered in Canterbury, the historic city in the county of Kent in South East England, to attend the eighth International Meeting on Yeast Apoptosis (IMYA). As with every IMYA conference since its inception in 2002, the feeling of being part of a community that is almost a family was evident. In addition, this year's meeting has shown that the field of yeast programmed cell death (PCD) is growing, not only in numbers, but also in its thematic scope.

The naturally occurring polyamine spermidine (Spd) has recently been shown to promote longevity across species in an autophagy-dependent manner. Here, we demonstrate that Spd improves both survival and locomotor activity of the fruit fly Drosophila melanogaster upon exposure to the superoxide generator and neurotoxic agent paraquat. Although survival to a high paraquat concentration (20mM) was specifically increased in female flies only, locomotor activity and survival could be rescued in both male and female animals when exposed to lower paraquat levels (5 mM). These effects are dependent on the autophagic machinery, as Spd failed to confer resistance to paraquat-induced toxicity and locomotor impairment in flies deleted for the essential autophagic regulator ATG7 (autophagy-related gene 7). Spd treatment did also protect against mild doses of another oxidative stressor, hydrogen peroxide, but in this case in an autophagy-independent manner. Altogether, this study establishes that the protective effects of Spd can be exerted through different pathways that depending on the oxidative stress scenario do or do not involve autophagy. © 2012 Macmillan Publishers Limited. All rights reserved.