Publications from researchers at the Buck Institute for Research on Aging http://www.buckinstitute.org/kapahiLab © 2011 Buck Institute, All Rights Reserved Cellular senescence suppresses cancer by arresting the proliferation of cells at risk for malignant transformation. Recently, senescent cells were shown to secrete numerous cytokines, growth factors and proteases that can alter the tissue microenvironment and may promote agerelated pathology. To identify small molecules that suppress the senescenceassociated secretory phenotype (SASP), we developed a screening protocol using normal human fibroblasts and a library of compounds that are approved for human use. Among the promising library constituents was the glucocorticoid corticosterone. Both corticosterone and the related glucocorticoid cortisol decreased the production and secretion of selected SASP components, including several proinflammatory cytokines. Importantly, the glucocorticoids suppressed the SASP without reverting the tumor suppressive growth arrest, and were efficacious whether cells were induced to senesce by ionizing radiation or strong mitogenic signals delivered by oncogenic RAS or MAP kinase kinase 6 overexpression. Suppression of the prototypical SASP component IL6 required the glucocorticoid receptor, which, in the presence of ligand, inhibited IL1 signaling and NFB transactivation activity. Accordingly, cotreatments combining glucocorticoids with the glucocorticoid antagonist RU486 or recombinant IL1 efficiently reestablished NFB transcriptional activity and IL6 secretion. Our findings demonstrate feasibility of screening for compounds that inhibit the effects of senescent cells. They further show that glucocorticoids inhibit selected components of the SASP, and suggest that corticosterone and cortisol, two FDAapproved drugs, might exert their effects in part by suppressing senescenceassociated inflammation. 2012 The Authors Aging Cell 2012 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland. http://www.ncbi.nlm.nih.gov/pubmed/22404905 Sat, 31 Dec 2011 00:00:00 -0800 Reducing protein synthesis slows growth and development but can increase adult life span. We demonstrate that knockdown of eukaryotic translation initiation factor 4G (eIF4G), which is downregulated during starvation and dauer state, results in differential translation of genes important for growth and longevity in C.elegans. Genomewide mRNA translation state analysis showed that inhibition of IFG1, the C.elegans ortholog of eIF4G, results in a relative increase in ribosomal loading and translation of stress response genes. Some of these genes are required for life span extension when IFG1 is inhibited. Furthermore, enhanced ribosomal loading of certain mRNAs upon IFG1 inhibition was correlated with increased mRNA length. This association was supported by changes in the proteome assayed via quantitative mass spectrometry. Our results suggest that IFG1 mediates the antagonistic effects on growth and somatic maintenance by regulating mRNA translation of particular mRNAs based, in part, on transcript length. http://www.ncbi.nlm.nih.gov/pubmed/21723504 Fri, 31 Dec 2010 00:00:00 -0800 Cellular senescence is an established cellular stress response that acts primarily to prevent the proliferation of cells that experience potentially oncogenic stress. In recent years, it has become increasingly apparent that the senescence response is a complex phenotype, which has a variety of cell nonautonomous effects. The senescenceassociated secretory phenotype, or SASP, entails the secretion of numerous cytokines, growth factors and proteases. The SASP can have beneficial or detrimental effects, depending on the physiological context. One recently described beneficial effect is to aid tissue repair. Among the detrimental effects, the SASP can disrupt normal tissue structures and function, and, ironically, can promote malignant phenotypes in nearby cells. These detrimental effects in many ways recapitulate the degenerative and hyperplastic pathologies that develop during aging. Because the SASP is largely a response to genomic or epigenomic damage, we suggest it may be a model for a cellular damage response that can propagate damage signals both within and among tissues. We propose that both the degenerative and hyperplastic diseases of aging may be fueled by such damage signals. http://www.ncbi.nlm.nih.gov/pubmed/21925603 Fri, 31 Dec 2010 00:00:00 -0800 This study also provides an interesting insight for the possible use of Rapamycin in preventive medicine. Rapamycin could be given to people predisposed to cancer based on genetic and family history and may also be useful to treat cancer patients to prevent relapses and metastasis. http://www.ncbi.nlm.nih.gov/pubmed/22170738 Fri, 31 Dec 2010 00:00:00 -0800 Compounds that delay aging might also postpone agerelated diseases and extend healthspan in humans. Icariin is a flavonol extracted from several plant species of the Epimedium family. The icariin and its metabolic derivatives have been shown to exert wide protective effects in agerelated diseases. However, whether icariin and its derivatives have the potency of delaying aging remains unclear. Here, we report that icariin and its derivative icariside II extend C. elegans lifespan. Using HPLC, we found high level of icariside II in the animals treated with icariin, suggesting icariside II is the bioactive form in vivo of icariin. Icariside II also increased the thermo and oxidative stress tolerance, slowed locomotion decline in late adulthood and delayed the onset of paralysis mediated by polyQ and A(142) proteotoxicity. The lifespan extension effect of icariside II is dependent on the insulin/IGF1 signaling (IIS) since the daf16(mu86) and daf2(e1370) failed to show any lifespan extension upon icariside II treatment. Consistently, icariside II treatment upregulates the expression of DAF16 targets in the wildtype. Moreover, our data suggests that the heat shock transcription factor HSF1 has a role in icariside IIdependent lifespan extension further implicating the IIS pathway. In conclusion, we demonstrate a novel natural compound, icariside II as the bioactive form of icariin, extends the healthspan via IIS pathway in C. elegans. http://www.ncbi.nlm.nih.gov/pubmed/22216122 Fri, 31 Dec 2010 00:00:00 -0800 Extensive studies in model organisms in the last few decades have revealed that aging is subject to profound genetic influence. The conserved nutrient sensing TOR (Target Of Rapamycin) pathway is emerging as a key regulator of lifespan and healthspan in various species from yeast to mammals. The TOR signaling pathway plays a critical role in determining how an eukaryotic cell or a cellular system coordinates its growth, development and aging in response to constant changes in its surrounding environment TOR integrates signals originating from changes in growth factors, nutrient availability, energy status and various physiological stresses. Each of these inputs is specialized to sense particular signal(s), and conveys it to the TOR complex which in turn relays the signal to downstream outputs to appropriately respond to the environmental changes. These outputs include mRNA translation, autophagy, transcription, metabolism, cell survival, proliferation and growth amongst a number of other cellular processes, some of which influence organismal lifespan. Here we review the contribution of the model organism Drosophila in the understanding of TOR signaling and the various biological processes it modulates that may impact on aging. Drosophila was the first organism where the nutrient dependent effects of the TOR pathway on lifespan were first uncovered. We also discuss how the nutrientsensing TOR pathway appears to be critically important for mediating the longevity effects of dietary restriction (DR), a potent environmental method of lifespan extension by nutrient limitation. Identifying the molecular mechanisms that modulate lifespan downstream of TOR is being intensely investigated and there is hope that these are likely to serve as a potential targets for amelioration of agerelated diseases and enhance healthful lifespan extension in humans. http://www.ncbi.nlm.nih.gov/pubmed/21130151 Tue, 30 Nov 2010 00:00:00 -0800 Growth and somatic maintenance are thought to be antagonistic piciotropic traits, but the molecular basis for this tradeoff is poorly understood. Here it is proposed that changes in protein synthesis mediate the tradeoffs that take place upon genetic and environmental manipulation in various model systems including yeast, worms, flies and mice. This hypothesis is supported by evidence that inhibition of the TOR (target of rapamycin) pathway and various translation factors that inhibit protein synthesis lead to slowing of growth and development but extend lifespan. Furthermore, dietary restriction (DR) that leads to antagonistic changes in growth and lifespan, also mediates this change by inhibiting protein synthesis. Direct screens to identify genes that extend lifespan from a subset of genes that are essential for growth and development have also uncovered a number of genes involved in protein synthesis. Given the conserved mechanisms of protein synthesis across species, I discuss potential mechanisms that mediate the lifespan extension by inhibition of protein synthesis that are likely to be important for aging and agerelated disorders in humans. http://www.ncbi.nlm.nih.gov/pubmed/20886754 Thu, 30 Sep 2010 00:00:00 -0700 The insulinlike signaling (ILS) pathway regulates metabolism and is known to modulate adult life span in C. elegans. Altered stress responses and resistance to a wide range of stressors are also associated with changes in ILS and contribute to enhanced longevity. The transcription factors DAF16 and HSF1 are key effectors of the longevity phenotype. We demonstrate that increased intrinsic thermotolerance, due to lower ILS, is not dependent on stressinduced transcriptional responses but instead requires active protein translation. Translation profiling experiments reveal genes that are posttranscriptionally regulated in response to altered ILS during heat shock in a DAF16dependent manner. Furthermore, several novel proteins are specifically required for ILS effects on thermotolerance. We propose that lowered ILS results in metabolic and physiological changes. These DAF16induced changes precondition a translational response under acute stress to modulate survival. http://www.ncbi.nlm.nih.gov/pubmed/20816092 Tue, 31 Aug 2010 00:00:00 -0700 How do organisms sense metabolic and nutrient status to set their biological clocks The significance of recent work showing that nutrientsensing pathways influence central circadian clocks in Drosophila is discussed. http://www.ncbi.nlm.nih.gov/pubmed/20656206 Wed, 30 Jun 2010 00:00:00 -0700 Target of rapamycin (TOR) is an evolutionarily conserved nutrientsensing protein kinase that regulates growth and metabolism in all eukaryotic cells. Studies in flies, worms, yeast, and mice support the notion that the TOR signaling network modulates aging. TOR is also emerging as a robust mediator of the protective effects of various forms of dietary restriction (DR), which can extend life span and slow the onset of certain agerelated diseases across species. Here we discuss how modulating TOR signaling slows aging through downstream processes including mRNA translation, autophagy, endoplasmic reticulum (ER) stress signaling, stress responses, and metabolism. Identifying the mechanisms by which the TOR signaling network works as a pacemaker of aging is a major challenge and may help identify potential drug targets for agerelated diseases, thereby facilitating healthful life span extension in humans. http://www.ncbi.nlm.nih.gov/pubmed/20519118 Mon, 31 May 2010 00:00:00 -0700 Balancing intake of diverse nutrients is important for organismal growth, reproduction, and survival. A shift in an organism's optimal diet due to changes in nutritional requirements after developmental or environmental changes is referred to as dietary switch and has been observed in several species. Here we demonstrate that female Drosophila melanogaster also undergo a dietary switch following mating that leads to an increased preference for yeast, the major source of protein in their diet. We also demonstrate that S6 kinase (S6K) and serotonin production are involved in the postmating dietary switch. To further investigate the ability of D. melanogaster to balance nutrient intake, we examined the dietary preferences of adult flies following deprivation of yeast or sucrose. We observe that following conditioning on a diet deficient in either carbohydrates or yeast, D. melanogaster show a strong preference for the deficient nutrient. Furthermore, flies with activated dS6K or flies fed a serotonin precursor exhibit enhanced preference for yeast in this assay. Our results suggest that TOR signaling and serotonin may play an important role in maintaining nutrient balance in D. melanogaster. These studies may contribute to our understanding of metabolic disorders such as obesity and diabetes. http://www.ncbi.nlm.nih.gov/pubmed/20471266 Mon, 31 May 2010 00:00:00 -0700 The target of rapamycin (TOR) signal transduction network monitors intra and extracellular conditions that favor cell growth. Research during the last decade has revealed a modular structure of the TOR signaling network. Each signaling module senses a particular set of signals from the cellular milieu and exerts regulatory control towards TOR activity. The TOR pathway responds to growth factor signals, nutrient availability, and cellular stresses like hypoxia and energy stress. The signaling modules and their molecular components constituting the TOR network are remarkably conserved in both sequence and function across species. In yeast, roundworms, flies, and mice, the TOR pathway has been shown to regulate lifespan. Correspondingly, genetic, dietary or pharmacological manipulation of individual signaling modules as well as TOR activity itself extends lifespan in these model organisms. We discuss the potential impact of manipulating TOR activity for human health and lifespan. http://www.ncbi.nlm.nih.gov/pubmed/20385253 Mon, 31 May 2010 00:00:00 -0700 Using a transgenic mouse model harboring a mutation reporter gene that can be efficiently recovered from genomic DNA, we previously demonstrated that mutations accumulate in aging mice in a tissuespecific manner. Applying a recently developed, similar reporterbased assay in Drosophila melanogaster, we now show that the mutation frequency at the lacZ locus in somatic tissue of flies is about three times as high as in mouse tissues, with a much higher fraction of large genome rearrangements. Similar to mice, somatic mutations in the fly also accumulate as a function of age, but they do so much more quickly at higher temperature, a condition which in invertebrates is associated with decreased life span. Most mutations were found to accumulate in the thorax and less in abdomen, suggesting the highly oxidative flight muscles as a possible source of genotoxic stress. These results show that somatic mutation loads in shortlived flies are much more severe than in the much longerlived mice, with the mutation rate in flies proportional to biological rather than chronological aging. http://www.ncbi.nlm.nih.gov/pubmed/20485564 Fri, 30 Apr 2010 00:00:00 -0700 Dietary restriction (DR) is a robust nongenetic, nonpharmacological intervention that is known to increase active and healthy lifespan in a variety of species. Despite a variety of differences in the protocols and the way DR is carried out in different species, conserved relationships are emerging among multiple species. 2009 saw the field of DR mature with important mechanistic insights from multiple species. A report of lifespan extension in rapamycintreated mice suggested that the TOR pathway, a conserved mediator of DR in invertebrates, may also be critical to DR effects in mammals. 2009 also saw exciting discoveries related to DR in various organisms including yeast, worms, flies, mice, monkeys and humans. These studies complement each other and together aim to deliver the promise of postponing aging and agerelated diseases by revealing the underlying mechanisms of the protective effects of DR. Here, we summarize a few of the reports published in 2009 that we believe provide novel directions and an improved understanding of dietary restriction. http://www.ncbi.nlm.nih.gov/pubmed/20096035 Wed, 31 Mar 2010 00:00:00 -0700 http://www.ncbi.nlm.nih.gov/pubmed/20157562 Sun, 31 Jan 2010 00:00:00 -0800 http://www.ncbi.nlm.nih.gov/pubmed/20042759 Mon, 30 Nov 2009 00:00:00 -0800 Dietary restriction (DR) extends lifespan in multiple species. To examine the mechanisms of lifespan extension upon DR, we assayed genomewide translational changes in Drosophila. A number of nuclear encoded mitochondrial genes, including those in Complex I and IV of the electron transport chain, showed increased ribosomal loading and enhanced overall activity upon DR. We found that various mitochondrial genes possessed shorter and less structured 5'UTRs, which were important for their enhanced mRNA translation. The translational repressor 4EBP, the eukaryotic translation initiation factor 4E binding protein, was upregulated upon DR and mediated DR dependent changes in mitochondrial activity and lifespan extension. Inhibition of individual mitochondrial subunits from Complex I and IV diminished the lifespan extension obtained upon DR, reflecting the importance of enhanced mitochondrial function during DR. Our results imply that translational regulation of nuclearencoded mitochondrial gene expression by 4EBP plays an important role in lifespan extension upon DR. For a video summary of this article, see the PaperFlick file with the Supplemental Data available online. http://www.ncbi.nlm.nih.gov/pubmed/19804760 Wed, 30 Sep 2009 00:00:00 -0700 http://www.ncbi.nlm.nih.gov/pubmed/19797648 Wed, 30 Sep 2009 00:00:00 -0700 http://www.ncbi.nlm.nih.gov/pubmed/19633411 Fri, 31 Jul 2009 00:00:00 -0700 Dietary restriction (DR) has been shown to robustly extend lifespan in multiple species tested so far. The prolongevity effect of DR is often ascribed to an increase in cellular defense against somatic damage, most notably damage by reactive oxygen species (ROS), considered a major cause of aging. Especially irreversible damage to DNA, the carrier of genetic information, is considered a critical causal factor in aging. Using a recently developed transgenic Drosophila melanogaster model system harboring a lacZplasmid construct that can be recovered in E. coli, spontaneous DNA mutation frequency in flies under DR and ad libitum conditions are measured. Three different DR conditions, imposed by manipulating levels of different types of yeast sources, were tested in females and males of two lacZ reporter gene lines. Feeding with the ROS producer paraquat at 1 mM resulted in a rapid accumulation of somatic mutations, indicating that the frequency of mutations at the lacZ locus is a reliable marker for increased oxidative stress. However, none of the DR conditions altered the accumulation of spontaneous mutations with age. These results suggest that the beneficial effects of DR are unlikely to be linked to protection against oxidative somatic DNA damage. http://www.ncbi.nlm.nih.gov/pubmed/19627272 Tue, 30 Jun 2009 00:00:00 -0700 Dietary restriction (DR) extends lifespan in various species and also slows the onset of agerelated diseases. Previous studies from flies and yeast have demonstrated that the target of rapamycin (TOR) pathway is essential for longevity phenotypes resulting from DR. TOR is a conserved protein kinase that regulates growth and metabolism in response to nutrients and growth factors. While some of the downstream targets of TOR have been implicated in regulating lifespan, it is still unclear whether additional targets of this pathway also modulate lifespan. It has been shown that the hypoxia inducible factor1 (HIF1) is one of the targets of the TOR pathway in mammalian cells. HIF1 is a transcription factor complex that plays key roles in oxygen homeostasis, tumor formation, glucose metabolism, cell survival, and inflammatory response. Here, we describe a novel role for HIF1 in modulating lifespan extension by DR in Caenorhabditis elegans. We find that HIF1 deficiency results in extended lifespan, which overlaps with that by inhibition of the RSKS1/S6 kinase, a key component of the TOR pathway. Using a modified DR method based on variation of bacterial food concentrations on solid agar plates, we find that HIF1 modulates longevity in a nutrientdependent manner. The hif1 lossoffunction mutant extends lifespan under rich nutrient conditions but fails to show lifespan extension under DR. Conversely, a mutation in egl9, which increases HIF1 activity, diminishes the lifespan extension under DR. This deficiency is rescued by tissuespecific expression of egl9 in specific neurons and muscles. Increased lifespan by hif1 or DR is dependent on the endoplasmic reticulum (ER) stress regulator inositolrequiring protein1 (IRE1) and is associated with lower levels of ER stress. Therefore, our results demonstrate a tissuespecific role for HIF1 in the lifespan extension by DR involving the IRE1 ER stress pathway. http://www.ncbi.nlm.nih.gov/pubmed/19461873 Thu, 30 Apr 2009 00:00:00 -0700 We have mapped a protein interaction network of human homologs of proteins that modify longevity in invertebrate species. This network is derived from a proteomescale human protein interaction Core Network generated through unbiased highthroughput yeast twohybrid searches. The longevity network is composed of 175 human homologs of proteins known to confer increased longevity through loss of function in yeast, nematode, or fly, and 2,163 additional human proteins that interact with these homologs. Overall, the network consists of 3,271 binary interactions among 2,338 unique proteins. A comparison of the average node degree of the human longevity homologs with random sets of proteins in the Core Network indicates that human homologs of longevity proteins are highly connected hubs with a mean node degree of 18.8 partners. Shortest path length analysis shows that proteins in this network are significantly more connected than would be expected by chance. To examine the relationship of this network to human aging phenotypes, we compared the genes encoding longevity network proteins to genes known to be changed transcriptionally during aging in human muscle. In the case of both the longevity protein homologs and their interactors, we observed enrichments for differentially expressed genes in the network. To determine whether homologs of human longevity interacting proteins can modulate life span in invertebrates, homologs of 18 human FRAP1 interacting proteins showing significant changes in human aging muscle were tested for effects on nematode life span using RNAi. Of 18 genes tested, 33 extended life span when knockeddown in Caenorhabditis elegans. These observations indicate that a broad class of longevity genes identified in invertebrate models of aging have relevance to human aging. They also indicate that the longevity protein interaction network presented here is enriched for novel conserved longevity proteins. http://www.ncbi.nlm.nih.gov/pubmed/19293945 Sat, 28 Feb 2009 00:00:00 -0800 Recently, a mutation in the mitochondrial protease Omi/HtrA2, G399S, was found in sporadic Parkinson's disease (PD) patients, leading to the designation of Omi/HtrA2 as PD locus 13 (PARK13). G399S reportedly results in reduced Omi protease activity. In vitro studies have suggested that Omi/HtrA2 acts downstream of PINK1, mutations in which mediate recessive forms of PD. We, as well as other, have previously shown that the Drosophila homologs of the familial PD genes, PINK1 (PARK6) and PARKIN (PARK2), function in a common genetic pathway to regulate mitochondrial integrity and dynamics. Whether Omi/HtrA2 regulates mitochondrial integrity and whether it acts downstream of PINK1 in vivo remain to be explored. Here, we show that Omi/HtrA2 null mutants in Drosophila, in contrast to pink1 or parkin null mutants, do not show mitochondrial morphological defects. Extensive genetic interaction studies do not provide support for models in which Omi/HtrA2 functions in the same genetic pathway as pink1, or carries out partially redundant functions with pink1, at least with respect to regulation of mitochondrial integrity and dynamics. Furthermore, Omi/HtrA2 G399S retains significant, if not full, function of Omi/HtrA2, compared with expression of proteasecompromised versions of the protein. In light of recent findings showing that G399S can be found at comparable frequencies in PD patients and healthy controls, we do not favor a hypothesis in which Omi/HtrA2 plays an essential role in PD pathogenesis, at least with respect to regulation of mitochondrial integrity in the pink1/parkin pathway. http://www.ncbi.nlm.nih.gov/pubmed/19118185 Wed, 31 Dec 2008 00:00:00 -0800 The antagonistic pleiotropy theory of aging proposes that aging takes place because natural selection favors genes that confer benefit early on life at the cost of deterioration later in life. This theory predicts that genes that impact development would play a key role in shaping adult lifespan. To better understand the link between development and adult lifespan, we examined the genes previously known to be essential for development. From a pool of 57 genes that cause developmental arrest after inhibition using RNA interference, we have identified 24 genes that extend lifespan in Caenorhabditis elegans when inactivated during adulthood. Many of these genes are involved in regulation of mRNA translation and mitochondrial functions. Genetic epistasis experiments indicate that the mechanisms of lifespan extension by inactivating the identified genes may be different from those of the insulin/insulinlike growth factor 1 (IGF1) and dietary restriction pathways. Inhibition of many of these genes also results in increased stress resistance and decreased fecundity, suggesting that they may mediate the tradeoffs between somatic maintenance and reproduction. We have isolated novel lifespanextension genes, which may help understand the intrinsic link between organism development and adult lifespan. http://www.ncbi.nlm.nih.gov/pubmed/17521386 Sat, 30 Jun 2007 00:00:00 -0700 Protein synthesis is a regulated cellular process that links nutrients in the environment to organismal growth and development. Here we examine the role of genes that regulate mRNA translation in determining growth, reproduction, stress resistance and lifespan. Translational control of protein synthesis by regulators such as the capbinding complex and S6 kinase play an important role during growth. We observe that inhibition of various genes in the translation initiation complex including ifg1, the worm homologue of eIF4G, which is a scaffold protein in the capbinding complex and rsks1, the worm homologue of S6 kinase, results in lifespan extension in Caenorhabditis elegans. Inhibition of ifg1 or rsks1 also slows development, reduces fecundity and increases resistance to starvation. A reduction in ifg1 expression in dauers was also observed, suggesting an inhibition of protein translation during the dauer state. Thus, mRNA translation exerts pleiotropic effects on growth, reproduction, stress resistance and lifespan in C. elegans. http://www.ncbi.nlm.nih.gov/pubmed/17266680 Wed, 31 Jan 2007 00:00:00 -0800 Mating elicits a dramatic reprogramming of female behavior in numerous insect species. In Drosophila, this postmating response (PMR) comprises increased egglaying rate and reduced sexual receptivity and is controlled by the products of the male accessory glands, a family of approximately 80 small peptides transferred in the male seminal fluid . Here, we show that copulation strongly stimulates female food intake. Remarkably, this change is abolished if the males lack a single, small seminal protein, the Sex Peptide (SP). Ectopic expression of SP in virgin females mimics the effect of mating on feeding behavior, demonstrating that SP is the main agent controlling this behavioral paradigm. Our observations identify enhanced feeding behavior as a novel component of the Drosophila PMR and suggest that SP represents a molecular link between energy acquisition and reproductive investment. http://www.ncbi.nlm.nih.gov/pubmed/16581515 Fri, 31 Mar 2006 00:00:00 -0800 Dietary restriction extends the lifespan of numerous, evolutionarily diverse species. In D. melanogaster, a prominent model for research on the interaction between nutrition and longevity, dietary restriction is typically based on medium dilution, with possible compensatory ingestion commonly being neglected. Possible problems with this approach are revealed by using a method for direct monitoring of D. melanogaster feeding behavior. This demonstrates that dietary restriction elicits robust compensatory changes in food consumption. As a result, the effect of medium dilution is overestimated and, in certain cases, even fully compensated for. Our results strongly indicate that feeding behavior and nutritional composition act concertedly to determine fly lifespan. Feeding behavior thus emerges as a central element in D. melanogaster aging. http://www.ncbi.nlm.nih.gov/pubmed/16278649 Mon, 31 Oct 2005 00:00:00 -0800 Recent studies point to an emerging role for the TOR (target of rapamycin) pathway in the regulation of life span. In this Perspective, we discuss the possibility that this pathway is an important modulator of nutrientdependent changes in life span. Additionally, we discuss the interactions between the TOR and insulinlike signaling pathways as well as the key downstream processes that TOR regulates. http://www.ncbi.nlm.nih.gov/pubmed/15356349 Tue, 31 Aug 2004 00:00:00 -0700 In many species, reducing nutrient intake without causing malnutrition extends lifespan. Like DR (dietary restriction), modulation of genes in the insulinsignaling pathway, known to alter nutrient sensing, has been shown to extend lifespan in various species. In Drosophila, the target of rapamycin (TOR) and the insulin pathways have emerged as major regulators of growth and size. Hence we examined the role of TOR pathway genes in regulating lifespan by using Drosophila. We show that inhibition of TOR signaling pathway by alteration of the expression of genes in this nutrientsensing pathway, which is conserved from yeast to human, extends lifespan in a manner that may overlap with known effects of dietary restriction on longevity. In Drosophila, TSC1 and TSC2 (tuberous sclerosis complex genes 1 and 2) act together to inhibit TOR (target of rapamycin), which mediates a signaling pathway that couples amino acid availability to S6 kinase, translation initiation, and growth. We find that overexpression of dTsc1, dTsc2, or dominantnegative forms of dTOR or dS6K all cause lifespan extension. Modulation of expression in the fat is sufficient for the lifespanextension effects. The lifespan extensions are dependent on nutritional condition, suggesting a possible link between the TOR pathway and dietary restriction. http://www.ncbi.nlm.nih.gov/pubmed/15186745 Mon, 31 May 2004 00:00:00 -0700 The relationship between gene expression and the regulation of longevity is poorly understood. Previous studies focusing on microarray or tissuespecific changes in gene expression as a function of age have provided evidence that gene expression is a dynamic process which is regulated, even late in an organism's lifespan. Using the enhancertrap technique, a systematic analysis of the spatiotemporal regulation of gene expression in tissues of adult Drosophila is presented. As many as 80 of enhancer traps analysed displayed (some form of) transcriptional change with age. In some cases the rate of change in expression was found to correlate with changes in longevity under various conditions, suggesting that they may be indicators of 'physiological age' and therefore valuable markers for dissecting the aging process. Molecular analysis of enhancer traps that showed increased activity with age was performed to identify candidate genes that may be important in the regulation of longevity we identified changes in reporters associated with immunity, microtubule organization and muscle function. http://www.ncbi.nlm.nih.gov/pubmed/12882353 Mon, 30 Jun 2003 00:00:00 -0700 http://www.ncbi.nlm.nih.gov/pubmed/12016332 Tue, 30 Apr 2002 00:00:00 -0700 Most inflammatory agents activate nuclear factorkappaB (NFkappaB), resulting in induction of genes coding for cytokines, chemokines, and enzymes involved in amplification and perpetuation of inflammation. Hypoestoxide (a bicyclo 9,3,1 pentadecane) is a diterpene from Hypoestes rosea, a tropical shrub in the family Acanthacea, several members of which are used in folk medicine in Nigeria. Here, we demonstrate that hypoestoxide (HE) abrogates the production of proinflammatory cytokines (IL1beta, IL6, and TNFalpha) in lipopolysaccharide (LPS)activated normal human peripheral blood mononuclear cells. Moreover, HE inhibits the production of nitric oxide (NO) by IL1beta or IL17stimulated normal human chondrocytes. In vivo, oral administration of HE to mice significantly ameliorated hind paw edema induced by antibodies to type II collagen plus LPS. Furthermore, topical administration of HE to mice also significantly inhibited phorbol esterinduced ear inflammation. The antiinflammatory activity of HE may be due in part to its ability to inhibit NFkappaB activation through direct inhibition of IkappaB kinase (IKK) activity. Thus, HE could be useful in treating various inflammatory diseases and may represent a prototype of a novel class of IKK inhibitors. http://www.ncbi.nlm.nih.gov/pubmed/11446747 Sat, 30 Jun 2001 00:00:00 -0700 The disposable soma theory suggests that longevity is determined through the setting of longevity assurance mechanisms so as to provide an optimal compromise between investments in somatic maintenance (including stress resistance) and in reproduction. A corollary is that species with low extrinsic mortality are predicted to invest relatively more effort in maintenance, resulting in slower intrinsic ageing, than species with high extrinsic mortality. We tested this prediction in a comparative study of stress resistance in primary skin fibroblasts and confirmed that cells from longlived species are indeed more resistant to a variant of stressors. A widely studied example of withinspecies variation in lifespan is the rodent calorie restriction model. Foodrestricted animals show elevations in a range of stress response mechanisms, and it has been suggested that this is an outcome of natural selection for life history plasticity. We have developed a theoretical model for dynamic optimisation of the allocation of effort to maintenance and reproduction in response to fluctuations in food availability. The model supports the suggestion that the response to calorie restriction may be an evolutionary adaptation, raising interesting questions about the hierarchy of genetic control of multiple stress response systems. The model identifies ecological factors likely to support such an adaptation that may be relevant in considering the likely relevance of a similar response to calorie restriction in other species. Comparative and theoretical studies support the role of somatic maintenance and stress response systems in controlling the rate of ageing. http://www.ncbi.nlm.nih.gov/pubmed/11197532 Sun, 31 Dec 2000 00:00:00 -0800 Arsenite is a potent environmental toxin that causes various pathologies including cancers and skin disorders. Arsenite is believed to exert its biological effects through reaction with exposed sulfhydryl groups, especially pairs of adjacent thiols. Here, we describe the mechanism by which arsenite affects the NFkappaB signaling pathway. Activation of transcription factor NFkappaB depends on the integrity of the IkappaB kinase (IKK) complex. We found that arsenite potently inhibits NFkappaB and IKK activation by binding to Cys179 in the activation loop of the IKK catalytic subunits, IKKalpha/beta. The affinity of IKKbeta for trivalent arsenic was verified in vitro by the ability of IKKbeta to enhance the fluorescence of an arsenicsubstituted fluorescein dye. The addition of 1,2dithiol antidotes or replacement of Cys179 with an alanine residue abolished dye binding to and arsenite inhibition of IKKbeta. Overexpression of IKKbeta (C179A) protects NFkappaB from inhibition by arsenite, indicating that despite the involvement of a large number of distinct gene products in this activation pathway, the critical target for inhibition by arsenite is on the IKK catalytic subunits. http://www.ncbi.nlm.nih.gov/pubmed/10967126 Thu, 30 Nov 2000 00:00:00 -0800 NFkappaB is a critical activator of genes involved in inflammation and immunity. Proinflammatory cytokines activate the IkappaB kinase (IKK) complex that phosphorylates the NFkappaB inhibitors, triggering their conjugation with ubiquitin and subsequent degradation. Freed NFkappaB dimers translocate to the nucleus and induce target genes, including the one for cyclooxygenase 2 (COX2), which catalyses the synthesis of proinflammatory prostaglandins, in particular PGE. At late stages of inflammatory episodes, however, COX2 directs the synthesis of antiinflammatory cyclopentenone prostaglandins, suggesting a role for these molecules in the resolution of inflammation. Cyclopentenone prostaglandins have been suggested to exert antiinflammatory activity through the activation of peroxisome proliferatoractivated receptorgamma. Here we demonstrate a novel mechanism of antiinflammatory activity which is based on the direct inhibition and modification of the IKKbeta subunit of IKK. As IKKbeta is responsible for the activation of NFkappaB by proinflammatory stimuli, our findings explain how cyclopentenone prostaglandins function and can be used to improve the utility of COX2 inhibitors. http://www.ncbi.nlm.nih.gov/pubmed/10638762 Fri, 31 Dec 1999 00:00:00 -0800 Identifying the mechanisms determining speciesspecific life spans is a central challenge in understanding the biology of aging. Cellular stresses produce damage, that may accumulate and cause aging. Evolution theory predicts that longlived species secure their longevity through investment in a more durable soma, including enhanced cellular resistance to stress. To investigate whether cells from longlived species have better mechanisms to cope with oxidative and nonoxidative stress, we compared cellular resistance of primary skin fibroblasts from eight mammalian species with a range of life spans. Cell survival was measured by the thymidine incorporation assay following stresses induced by paraquat, hydrogen peroxide, tertbutyl hydroperoxide, sodium arsenite and alkaline pH (sodium hydroxide). Significant positive correlations between cell LD90 and maximum life span were found for all these stresses. Similar results were obtained when cell survival was measured by the MTT assay, and when lymphocytes from different species were compared. Cellular resistance to a variety of oxidative and nonoxidative stresses was positively correlated with mammalian longevity. Our results support the concept that the gene network regulating the cellular response to stress is functionally important in aging and longevity. http://www.ncbi.nlm.nih.gov/pubmed/10218637 Mon, 31 May 1999 00:00:00 -0700 http://www.ncbi.nlm.nih.gov/pubmed/7533441 Fri, 31 Mar 1995 00:00:00 -0800 BACKGROUND: Diagnosis of the underlying dermatosis in erythroderma is often difficult. The cause of increased mortality in erythroderma, particularly in relation to infection, is incompletely understood. OBJECTIVE: We investigated the potential diagnostic use of circulating intercellular adhesion molecule1 (cICAM1), vascular cell adhesion molecule1 (cVCAM1), and Eselectin (cEselectin) levels in erythroderma. METHODS: cICAM1, cVCAM1, and cEselectin were measured by enzymelinked immunosorbent assay in 14 patients with erythroderma of known cause and in 17 control subjects. Levels were correlated with other markers of the inflammatory response. RESULTS: In erythroderma median cICAM1, cVCAM1, and cEselectin levels were significantly elevated, but no difference was found between values in patients with eczema and values in those with psoriasis. Circulating adhesion molecule levels did not correlate with erythrocyte sedimentation rate or total white blood cell count. CONCLUSION: cICAM1, cVCAM1, and cEselectin were detectable in patients with erythroderma but were not differential diagnostic use in this study. Because in vitro these molecules may interfere with normal cell adhesion mechanisms, we speculate that they may contribute to the immunosuppressive state in these patients. http://www.ncbi.nlm.nih.gov/pubmed/7529777 Tue, 31 Jan 1995 00:00:00 -0800 http://www.ncbi.nlm.nih.gov/pubmed/7520609 Wed, 31 Aug 1994 00:00:00 -0700 Sarcoidosis is a disease of unknown etiology characterized by noncaseating granulomata together with a number of systemic abnormalities. We have recently shown these include increased expression of the integrins CD11/CD18 on peripheral blood leucocytes. Here we have measured serum levels of the adhesion molecules intercellular adhesion molecule1 (ICAM1), Eselectin and vascular cell adhesion molecule1 (VCAM1) in 23 patients and 14 normal controls using antigen capture sandwich ELISAs. Median circulating Eselectin levels in the patients were nearly three times those of the controls (P 0.0001, MannWhitney Utest), whilst ICAM1 but not VCAM1 levels were only slightly elevated. These results show that endothelial cell activation and shedding of Eselectin into the circulation are additional features of the pathology of sarcoidosis. http://www.ncbi.nlm.nih.gov/pubmed/7514516 Tue, 31 May 1994 00:00:00 -0700 There is increasing evidence that leukocyteendothelial adhesion molecules are important in inflammatory airway disease because of their involvement in the primary steps of entrapment and migration of leukocytes to the site of inflammation. Recently, circulating forms of these adhesion molecules have been described, although their origin, fate, and function are still unknown. We have used an antigen capture ELISA to measure the concentrations of circulating intercellular adhesion molecule1 (cICAM1), Eselectin (cEselectin), and vascular cell adhesion molecule1 (cVCAM1) in the peripheral blood of 13 atopic and 16 nonatopic normal subjects, 29 patients with stable asthma, and inpatients with acute asthma on Day 1 (n = 38), Day 3 (n = 29), and Day 28 (n = 13) of an asthmatic episode. Circulating ICAM1 and Eselectin levels were significantly raised in acute asthma on all three study days when compared with those observed in stable asthma, atopic normal, or nonatopic normal volunteers with no significant differences among the latter three groups. Circulating VCAM1 was not significantly increased in any of the groups studied. There were no correlations among the concentrations of these three circulating adhesion molecules. The elevated concentrations of cICAM1 and cEselectin in acute asthma may reflect the extensive inflammatory response occurring in the airways during acute exacerbations of the disease with airway obstruction. It is possible that the cytokine and mediator profiles in acute asthma lead to the preferential synthesis and expression of these two circulating adhesion molecules in comparison with cVCAM1. http://www.ncbi.nlm.nih.gov/pubmed/7513593 Tue, 31 May 1994 00:00:00 -0700 We have developed a panel of MoAbs against four separate but overlapping epitopes on endothelial cell (EC) vascular cell adhesion molecule1 (VCAM1). Two of the MoAbs (1G11 and 1E5) inhibited T cell adhesion to tumour necrosis factor (TNF)activated EC, whilst two MoAbs (1.4C3 and 6D9) did not. Using these MoAbs we have identified a circulating form of VCAM1 (cVCAM1) which has identical epitope distribution to the EC form, and which is able to support the adhesion of the human lymphoblastoid cell line Jurkat J6 by a VLA4 and VCAM1dependent mechanism when immobilized from plasma. cVCAM1 isolated by immunoaffinity and sizeexclusion chromatographies was shown by SDSPAGE to have an apparent mol. wt of 8590 kD. Levels of cVCAM1 were significantly raised (P 0.001) in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) compared with normal individuals. It is possible that cVCAM1 may be a useful plasma marker for the diagnosis and management of patients with inflammatory diseases. Furthermore, detection of elevated cVCAM1 levels may act as a guide to the importance of VCAM1dependent cell adhesion in different pathological settings. http://www.ncbi.nlm.nih.gov/pubmed/7685670 Wed, 30 Jun 1993 00:00:00 -0700 OBJECTIVE: To compare the levels of circulating intercellular adhesion molecule 1 (cICAM1) and vascular cell adhesion molecule 1 (cVCAM1) in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). METHODS: Levels of cICAM1 and cVCAM1 were measured in both plasma and synovial fluid using monoclonal antibody sandwich enzymelinked immunoassays. RESULTS: Levels of both cICAM1 and cVCAM1 were significantly increased (P 0.001) in RA patients compared with normal controls. In contrast, only cVCAM1, and not cICAM1, was increased in patients with SLE. Levels of cICAM1 and cVCAM1 were significantly elevated in synovial fluid compared with plasma in paired samples from patients with RA. There was no correlation between levels of cICAM1 and levels of cVCAM1, in either plasma or synovial fluid. Whereas levels of cVCAM1 correlated significantly with the erythrocyte sedimentation rate (ESR) and Creactive protein level in RA patients and with the ESR in SLE patients, no significant correlations were found between cICAM1 and either of these indices of disease activity. CONCLUSION: These observations indicate that levels of cICAM1 and cVCAM1 reflect separate pathophysiologic processes. Both may be useful markers for the diagnosis and management of patients with rheumatic diseases. http://www.ncbi.nlm.nih.gov/pubmed/7681283 Wed, 31 Mar 1993 00:00:00 -0800