Search

Programmed cell death or apoptosis of infected host cells is an important defense mechanism in response to viral infections. This process is regulated by pro-apoptotic and pro-survival members of the B-cell lymphoma 2 (Bcl-2) protein family. To counter premature death of a virus-infected cell, poxviruses use a range of different molecular strategies, including the mimicry of pro-survival Bcl-2 proteins. One such viral pro-survival protein is the fowlpox virus protein FPV039, which is a potent apoptosis inhibitor, but the precise molecular mechanism by which FPV039 inhibits apoptosis is unknown. To understand how fowlpox virus inhibits apoptosis we examined FPV039 using isothermal titration calorimetry, small-angle X-ray scattering and X-ray crystallography. Here, we report that the fowlpox virus pro-survival protein FPV039 promiscuously binds to cellular pro-apoptotic Bcl-2, and engages all major pro-apoptotic Bcl-2 proteins. Unlike other identified viral Bcl-2 proteins to date, FPV039 engaged with cellular pro-apoptotic Bcl-2 with affinities comparable to those of Bcl-2's endogenous cellular counterparts. Structural studies revealed that FPV039 adopts the conserved Bcl-2 fold observed in cellular pro-survival Bcl-2 proteins, and closely mimics the structure of the pro-survival Bcl-2 family protein Mcl-1. Our findings suggest that FPV039 is a pan Bcl-2 protein inhibitor that can engage all host BH3-only proteins as well as Bcl-2 associated X, apoptosis regulator (Bax) and Bcl-2 antagonist/killer (Bak) proteins to inhibit premature apoptosis of an infected host cell. This work therefore provides a mechanistic platform to better understand FPV039-mediated apoptosis inhibition.

We propose that relationships between the synthesis rate and in vivo concentration of these metabolites go beyond being mere ontogenic and phenological coincidences; rather, they are directly or indirectly (i.e. by quenching presence of ROS) involved in regulating senescence. We propose that leaves do not enter senescence as long as their total cytokinin content (total = synthesized de novo+ imported from extra-chloroplastic and extra-foliar sources) remains high, and volatile isoprenoid emission remains high. Isoprene emission is a feature of chloroplasts of some plants, especially trees, whereas cytokinins and monoterpenes are synthesized in all types of plastids, in all plants. Co-occurrence of isoprene emission with deciduousness in trees (short life of leaves, Dani et al. 2014b; Loreto & Fineschi 2015) may suggest that isoprene emission is a drain on the MEP pathway, essentially opposing the positive effect of cytokinins and carotenoids in delaying senescence. However, considering available experimental proofs showing antioxidant and thermal protectant activity of isoprene and non-stored monoterpenes, we maintain possible that volatile isoprenoids supplement carotenoids in quenching ROS and help maintain plastome and thylakoid membrane integrity to delay senescence.

[EN] Nitric oxide (NO) regulates plant growth and development as well as responses to stress that enhanced its endogenous production. Arabidopsis plants exposed to a pulse of exogenous NO gas were used for untargeted global metabolomic analyses thus allowing the identification of metabolic processes affected by NO. At early time points after treatment, NO scavenged superoxide anion and induced the nitration and the S-nitrosylation of proteins. These events preceded an extensive though transient metabolic reprogramming at 6 h after NO treatment, which included enhanced levels of polyamines, lipid catabolism and accumulation of phospholipids, chlorophyll breakdown, protein and nucleic acid turnover and increased content of sugars. Accordingly, lipid-related structures such as root cell membranes and leaf cuticle altered their permeability upon NO treatment. Besides, NO-treated plants displayed degradation of starch granules, which is consistent with the increased sugar content observed in the metabolomic survey. The metabolic profile was restored to baseline levels at 24 h post-treatment, thus pointing up the plasticity of plant metabolism in response to nitroxidative stress conditions., This work was supported by grants BIO2011-27526 and BIO2014-56067-P from the Spanish Ministry of Economy and Competitiveness and FEDER funds. We thank support and comments from Danny Alexander (Metabolon Inc., USA) on metabolomic analyses.

International audience; In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

31 p.-11 fig.-2 tab.+ Erratum (2 p.) Papanikolaou, Alexie et al., Background: The Mediterranean fruit fly (medfly), Ceratitis capitata, is a major destructive insect pest due to its broad host range, which includes hundreds of fruits and vegetables. It exhibits a unique ability to invade and adapt to ecological niches throughout tropical and subtropical regions of the world, though medfly infestations have been prevented and controlled by the sterile insect technique (SIT) as part of integrated pest management programs (IPMs). The genetic analysis and manipulation of medfly has been subject to intensive study in an effort to improve SIT efficacy and other aspects of IPM control., Results: The 479 Mb medfly genome is sequenced from adult flies from lines inbred for 20 generations. A highquality assembly is achieved having a contig N50 of 45.7 kb and scaffold N50 of 4.06 Mb. In-depth curation of more than 1800 messenger RNAs shows specific gene expansions that can be related to invasiveness and host adaptation, including gene families for chemoreception, toxin and insecticide metabolism, cuticle proteins, opsins, and aquaporins. We identify genes relevant to IPM control, including those required to improve SIT., Conclusions: The medfly genome sequence provides critical insights into the biology of one of the most serious and widespread agricultural pests. This knowledge should significantly advance the means of controlling the size and invasive potential of medfly populations. Its close relationship to Drosophila, and other insect species important to agriculture and human health, will further comparative functional and structural studies of insect genomes that should broaden our understanding of gene family evolution, Support of this project was provided by the U.S. Department of Agriculture(USDA), Agricultural Research Service (ARS), Animal and Plant Health Inspection Service (APHIS), and National Institute of Food and Agriculture(NIFA)-Biotechnology Risk Assessment Grants Program (grant #2011-39211-30769 to AMH) for funding the initial phase of this project, and to the National Institutes of Health (NIH)-National Human Genome Research Institute (NHGRI) for funding the medfly genome sequencing, assembly and Maker 2.0 automated annotation as part of the i5K 30 genome pilot project (grant #U54 HG003273 to RAG). The NIH Intramural Research Program, National Library of Medicine funded the NCBI Gnomon annotation and the USDA-National Agricultural Library (NAL) provided support for the WebApollo curation website, with support for manual curation training (to MM-T) provided by NIGMS (grant #5R01GM080203),NHGRI (grant #5R01HG004483), and the U.S. Department of Energy(contract #DE-AC02-05CH11231). Support was provided for: toxin metabolism and insecticide resistance gene studies from MINECO,Spain (AGL2013-42632-R to FO and PH-C); microRNAs, horizontal gene transfer and bacterial contaminant studies from the European Social Fund and National Strategic Reference Framework-THALES (MIS375869 to KB, GT, AGH, and KM) and the U.S. National Science Foundation(DEB 1257053 to JHW); cuticle protein gene studies from USDA-NIFA(grant #2016-67012-24652 to AJR); sex-determination studies from L.R. Campania (grant 5/02, 2008 to GS); male reproduction and sexual differentiation studies from the FAO/IAEA (Technical Contract No: 16966 to GGa) and Cariplo IMPROVE (to FS); and programmed cell death gene studies and genomic data analysis (to MFS) from the Emmy Noether program, DFG(SCHE 1833/1-1) and the LOEWE Center for Insect Biotechnology & Bioresources grant of the Hessen State Ministry of Higher Education, Research and the Arts(HMWK), Germany and from the USDA-NIFA-Biotechnology Risk Assessment Grants Program (grant #2015-33522-24094 to AMH).

The Arabidopsis thaliana atr7 mutant is tolerant to oxidative stress induced by paraquat (PQ) or the catalase inhibitor aminotriazole (AT), while its original background loh2 and wild-type plants are sensitive. Both, AT and PQ which stimulate the intracellular formation of H2O2 or superoxide anions, respectively, trigger cell death in loh2 but do not lead to visible damage in atr7. To study gene expression during oxidative stress and ROS-induced programmed cell death, two platforms for multi-parallel quantitative real-time PCR (qRT-PCR) analysis of 217 antioxidant and 180 ROS marker genes were employed. The qRT-PCR analyses revealed AT- and PQ-induced expression of many ROS-responsive genes mainly in loh2, confirming that an oxidative burst plays a role in the activation of the cell death in this mutant. Some of the genes were specifically regulated by either AT or PQ serving as markers for particular types of ROS. Genes significantly induced by both AT and PQ in loh2 included transcription factors (ANAC042/JUB1, ANAC102, DREB19, HSFA2, RRTF1, ZAT10, ZAT12, ethylene-responsive factors), signaling compounds, ferritins, alternative oxidases, and antioxidant enzymes. Many of these genes were upregulated in atr7 compared to loh2 under non-stress conditions at the first time point, indicating that higher basal levels of ROS and higher antioxidant capacity in atr7 are responsible for the enhanced tolerance to oxidative stress and suggesting a possible tolerance against multiple stresses of this mutant. (c) 2012 Elsevier Masson SAS. All rights reserved.

Baculoviruses induce apoptotic responses in cultured insect cells, which can severely limit viral replication. To overcome this host response baculoviruses carry anti-apoptotic genes, including members of the p35 and inhibitor of apoptosis (iap) gene families. The baculovirus Helicoverpa armigera nucleopolyhedrovirus (HearNPV) carries two putative apoptosis suppressor genes (iap2 and iap3), which we studied in more detail. IAPs are believed to be functional in the cytoplasm, but surprisingly, when transiently expressed as EGFP fusions, IAP2 was evenly distributed throughout the cell, while IAP3 was mainly found in the nucleus. The latter became evenly distributed in both compartments in HearNPV infected cells. When iap2 was deleted, HearNPV could be propagated in Hz2e5 cells, while an iap3 deletion was lethal. The HearNPV Δiap3 mutant could be rescued by reinsertion of the HearNPV iap3 gene and by the well-studied anti-apoptotic genes Autographa californica (Ac)MNPV p35 or Orgyia pseudotsugata (Op)MNPV iap3. RNAi analysis showed that HearNPV induced apoptosis in Hz2e5 cells transfected with iap3 dsRNA, while silencing of iap2 did not lead to apoptosis. Finally, IAP3 was able to inhibit actinomycin-D induced apoptosis when transiently expressed in Sf21 cells. These results together indicate that HearNPV IAP3 is a functional apoptosis suppressor, while the function of IAP2 remains elusive.

International audience; Sphingolipids are emerging as important mediators of cellular and developmental processes in plants, and advances in lipidomics have yielded a wealth of information on the composition of plant sphingolipidomes. Studies using Arabidopsis thaliana showed that the dihydroxy long-chain base (LCB) is desaturated at carbon position 8 (d18:1?8). This raised important questions on the role(s) of sphingosine (d18:1?4) and sphingosine-1-phosphate (d18:1?4-P) in plants, as these LCBs appear to be absent in A.similar to thaliana. Here, we surveyed 21 species from various phylogenetic groups to ascertain the position of desaturation of the d18:1 LCB, in order to gain further insights into the prevalence of d18:1?4 and d18:1?8 in plants. Our results showed that d18:1?8 is common in gymnosperms, whereas d18:1?4 is widespread within nonseed land plants and the Poales, suggesting that d18:1?4 is evolutionarily more ancient than d18:1?8 in Viridiplantae. Additionally, phylogenetic analysis indicated that the sphingolipid ?4-desaturases from Viridiplantae form a monophyletic group, with Angiosperm sequences falling into two distinct clades, the Eudicots and the Poales. We propose that efforts to elucidate the role(s) of d18:1?4 and d18:1?4-P should focus on genetically tractable Viridiplantae species where the d18:1 LCB is desaturated at carbon position 4.

Autophagy (macroautophagy) is a bulk degradative pathway by which cytoplasmic components are delivered to the vacuole for recycling. This process is conserved from yeast to human, where it is implicated in cancer and neurodegenerative diseases. During the last decade, many ATG genes involved in autophagy have been identified, initially in Saccharomyces cerevisiae. This review summarizes the knowledge on the molecular mechanisms of autophagy using yeast as model system. Although many of the core components involved in autophagy are conserved from yeast to human, there are, nevertheless, significant differences between these organisms, for example, during autophagy initiation. Autophagy also plays an essential role in filamentous fungi especially during differentiation. Remarkably, in these species autophagy may reflect features of both yeast and mammals. This is exemplified by the finding that filamentous fungi lack the S. cerevisiae clade-specific Atg31 protein, but contain Atg101, which is absent in this clade. A reappraisal of genome data further suggests that, similar to yeast and mammals, filamentous fungi probably also contain two distinct phosphatidylinositol 3-kinase complexes. This review also summarizes the state of knowledge on the role of autophagy in filamentous fungi during differentiation, such as pathogenic development, programmed cell death during heteroincompatibility, and spore formation. Antioxid. Redox Signal. 14, 2271-2287.

We have previously reported a method for isolation of mutants with enhanced tolerance to the fungal AAL toxin and given a detailed characterization of atr1 (AAL toxin resistant, Gechev et al. in Biochem Biophys Res Commun 375:639–644, 2008). Herewith, we report eight more mutants with enhanced tolerance to the AAL toxin. Phenotypic analysis showed that six of the mutants were reduced in size compared with their original background loh2. Furthermore, atr2 showed delayed flowering and senescence. The mutants were also evaluated for oxidative stress tolerance by growing them on ROS-inducing media supplemented with either aminotriazole or paraquat, generating, respectively, H2O2 or superoxide radicals. Oxidative stress, confirmed by induction of the marker genes, HIGH AFFINITY NITRATE TRANSPORTER At1G08090 and HEAT SHOCK PROTEIN 17 At3G46230, inhibited growth of all lines. However, while the original background loh2 developed necrotic lesions and died rapidly on ROS-inducing plant growth media, atr1, atr2, atr7 and atr9 remained green and viable. The tolerance against oxidative stress-induced cell death was confirmed by fresh weight and chlorophyll measurements. Real-time PCR analysis revealed that the expression of the EXTENSIN gene At5G46890, previously shown to be downregulated by aminotriazole in atr1, was repressed in all lines, consistent with the growth inhibition induced by oxidative stress. Taken together, the data indicate a complex link between growth, development and oxidative stress tolerance and indicates that growth inhibition can be uncoupled from oxidative stress-induced cell death.

The liver plays a central role in the transformation and degradation of endogenous and exogenous chemicals, and in the removal of unwanted cells such as damaged, genetically mutated and virus-infected cells. Because of this function, the liver is susceptible to toxicity caused by the products generated during these natural occurrences. Hepatocyte death is the major feature of liver injury. In response to liver injury, specific intracellular processes are initiated to maintain liver integrity. Inflammatory cytokines including tumor necrosis factor (TNF)α and interleukin-6 (IL-6) are key mediators of these processes and activate different cellular response such as proliferation, survival and death. TNFα induces specific signaling pathways in hepatocytes that lead to activation of either pro-survival mediators or effectors of cell death. Whereas activation of transcription factor NF-κB promotes survival, c-Jun N-terminal kinases (JNKs) and caspases are strategic effectors of cell death in the TNFα-mediated signaling pathway. This review summarizes recent advances in the mechanisms of TNFα-induced hepatotoxicity and suggests that NF-κB plays a protective role against JNK-induced hepatocyte death. Identification of the mechanisms regulating interplay between the NF-κB and JNK pathways is required in the search for novel targets for the treatment of liver disease, including hepatitis and hepatocellular carcinoma.

The mitochondrial pathway to apoptosis is a major pathway of physiological cell death in vertebrates. The mitochondrial cell death pathway commences when apoptogenic molecules present between the outer and inner mitochondrial membranes are released into the cytosol by mitochondrial outer membrane permeabilization ( MOMP). BCL-2 family members are the sentinels of MOMP in the mitochondrial apoptotic pathway; the pro-apoptotic B cell lymphoma (BCL)-2 proteins, BCL-2 associated x protein and BCL-2 antagonist killer 1 induce MOMP whereas the anti-apoptotic BCL-2 proteins, BCL-2, BCL-x(L) and myeloid cell leukaemia 1 prevent MOMP from occurring. The release of pro-apoptotic factors such as cytochrome c from mitochondria leads to formation of a multimeric complex known as the apoptosome and initiates caspase activation cascades. These pathways are important for normal cellular homeostasis and play key roles in the pathogenesis of many diseases. In this review, we will provide a brief overview of the mitochondrial death pathway and focus on a selection of diseases whose pathogenesis involves the mitochondrial death pathway and we will examine the various pharmacological approaches that target this pathway.

The widespread potential for somatic fusion among different conspecific multicellular individuals suggests that such fusion is adaptive. However, because recognition of non-kin (allorecognition) usually leads to a rejection response, successful somatic fusion is limited to close kin. This is consistent with kin-selection theory, which predicts that the potential cost of fusion and the potential for somatic parasitism decrease with increasing relatedness. Paradoxically, however, Crozier found that, in the short term, positive-frequency-dependent selection eliminates the required genetic polymorphism at allorecognition loci. The 'Crozier paradox' may be solved if allorecognition is based on extrinsically balanced polymorphisms, for example at immune loci. Alternatively, the assumption of most models that self fusion is mutually beneficial is wrong. If fusion is on average harmful, selection will promote unconditional rejection. However, we propose that fusion within individuals is beneficial, selecting for the ability to fuse, but fusion between individuals on average costly, selecting for non-self recognition (rather than non-kin recognition). We discuss experimental data on fungi that are consistent with this hypothesis.

Leaf senescence in Arabidopsis thaliana is a strict, genetically controlled nutrient recovery program, which typically progresses in an age-dependent manner. Leaves of the Arabidopsis onset of leaf death5 ( old5) mutant exhibit early developmental senescence. Here, we show that OLD5 encodes quinolinate synthase ( QS), a key enzyme in the de novo synthesis of NAD. The Arabidopsis QS was previously shown to carry a Cys desulfurase domain that stimulates reconstitution of the oxygen-sensitive Fe-S cluster that is required for QS activity. The old5 lesion in this enzyme does not affect QS activity but it decreases its Cys desulfurase activity and thereby the long-term catalytic competence of the enzyme. The old5 mutation causes increased NAD steady state levels that coincide with increased activity of enzymes in the NAD salvage pathway. NAD plays a key role in cellular redox reactions, including those of the tricarboxylic acid cycle. Broad-range metabolite profiling of the old5 mutant revealed that it contains higher levels of tricarboxylic acid cycle intermediates and nitrogen-containing amino acids. The mutant displays a higher respiration rate concomitant with increased expression of oxidative stress markers. We postulate that the alteration in the oxidative state is integrated into the plant developmental program, causing early ageing of the mutant.

Leaf senescence in Arabidopsis thaliana is a strict, genetically controlled nutrient recovery program, which typically progresses in an age-dependent manner. Leaves of the Arabidopsis onset of leaf death5 (old5) mutant exhibit early developmental senescence. Here, we show that OLD5 encodes quinolinate synthase (QS), a key enzyme in the de novo synthesis of NAD. The Arabidopsis QS was previously shown to carry a Cys desulfurase domain that stimulates reconstitution of the oxygen-sensitive Fe-S cluster that is required for QS activity. The old5 lesion in this enzyme does not affect QS activity but it decreases its Cys desulfurase activity and thereby the long-term catalytic competence of the enzyme. The old5 mutation causes increased NAD steady state levels that coincide with increased activity of enzymes in the NAD salvage pathway. NAD plays a key role in cellular redox reactions, including those of the tricarboxylic acid cycle. Broad-range metabolite profiling of the old5 mutant revealed that it contains higher levels of tricarboxylic acid cycle intermediates and nitrogen-containing amino acids. The mutant displays a higher respiration rate concomitant with increased expression of oxidative stress markers. We postulate that the alteration in the oxidative state is integrated into the plant developmental program, causing early ageing of the mutant.

The development of small molecules to modulate caspase activity offers a novel therapeutic strategy in the treatment of apoptosis-related and inflammatory diseases. Caspases are key mediators of apoptosis and inflammation; deregulation of their activation or expression can lead to the development of conditions such as neurodegenerative and autoinflammatory disorders. This review details the different caspase-associated disorders while focusing on caspase-1 inhibition as a potential therapeutic strategy. Problems facing the development of effective and safe caspase therapeutics will also be addressed.

Microbial plant pathogens impose a continuous threat to global food production. Similar to animals, an innate immune system allows plants to recognize pathogens and swiftly activate defence. To activate a rapid response, receptor-mediated pathogen perception and subsequent downstream signalling depends on post-translational modification (PTM) of components essential for defence signalling. We discuss different types of PTMs that play a role in mounting plant immunity, which include phosphorylation, glycosylation, ubiquitination, sumoylation, nitrosylation, myristoylation, palmitoylation and glycosylphosphatidylinositol (GPI)-anchoring. PTMs are rapid, reversible, controlled and highly specific, and provide a tool to regulate protein stability, activity and localization. Here, we give an overview of PTMs that modify components essential for defence signalling at the site of signal perception, during secondary messenger production and during signalling in the cytoplasm. In addition, we discuss effectors from pathogens that suppress plant defence responses by interfering with host PTMs.

Programmed cell death or apoptosis is a major defense mechanism in insects in response to viral infections. The genome of Chilo iridescent virus (CIV) has three ORFs with homology to baculovirus inhibitor of apoptosis (iap) genes. The proteins encoded by the 157L, 193R, and 332L ORFs contain 152, 208 and 234 amino acids, respectively. While all three proteins contain C-terminal RING domains, only the protein encoded by ORF 193R contains a baculoviral iap repeat (BIR) domain, indicative of a putative IAP protein. The 193R protein has 28 and 27% similarity in amino acid sequence to the Orgyia pseudotsugata MNPV and Cydia pomonella granulovirus IAP-3 proteins, respectively. ORF 193R from CIV is the only gene known to exist among the Iridoviridae that encodes a BIR domain. 193R is transcribed early during CIV infection, and its transcription is not dependent on the synthesis of early viral proteins. When this putative CIV IAP was transiently expressed in SPC-BM-36 and Sf21 cells under the control of an immediate early baculovirus promoter it significantly reduced apoptosis induced by actinomycin-D. Silencing of the CIV iap gene (193R) in CIV infected SPC-BM-36 cells with 193R-specific dsRNA resulted in apoptosis. Thus, CIV ORF 193R is the first iap gene identified in an iridovirus, which encodes a functional IAP protein.

The tropical legume Sesbania rostrata provides its microsymbiont Azorhizobium caulinodans with versatile invasion strategies to allow nodule formation in temporarily flooded habitats. In aerated soils, the bacteria enter via the root hair curling mechanism. Submergence prevents this epidermal invasion by accumulation of inhibiting concentrations of ethylene and, under these conditions, the bacterial colonization occurs via intercellular cortical infection at lateral root bases. The transcriptome of both invasion ways was compared by cDNA-amplified fragment length polymorphism analysis. Clusters of gene tags were identified that were specific for either epidermal or cortical invasion or were shared by both. The data provide insight into mechanisms that control infection and illustrate that entry via the epidermis adds a layer of complexity to rhizobial invasion.

It is common knowledge that pathogenic viruses can change hosts, with avian influenza, the HIV, and the causal agent of variant Creutzfeldt-Jacob encephalitis as well-known examples. Less well known, however, is that host jumps also occur with more complex pathogenic microorganisms such as bacteria and fungi. In extreme cases, these host jumps even cross kingdom of life barriers. A number of requirements need to be met to enable a microorganism to cross such kingdom barriers. Potential cross-kingdom pathogenic microorganisms must be able to come into close and frequent contact with potential hosts, and must be able to overcome or evade host defences. Reproduction on, in, or near the new host will ensure the transmission or release of successful genotypes. An unexpectedly high number of cross-kingdom host shifts of bacterial and fungal pathogens are described in the literature. Interestingly, the molecular mechanisms underlying these shifts show commonalities. The evolution of pathogenicity towards novel hosts may be based on traits that were originally developed to ensure survival in the microorganism's original habitat, including former hosts.

Humans resist infection by the African parasite Trypanosoma brucei owing to the trypanolytic activity of the serum apolipoprotein L1 (APOL1). Following uptake by endocytosis in the parasite, APOL1 forms pores in endolysosomal membranes and triggers lysosome swelling. Here we show that APOL1 induces both lysosomal and mitochondrial membrane permeabilization (LMP and MMP). Trypanolysis coincides with MMP and consecutive release of the mitochondrial TbEndoG endonuclease to the nucleus. APOL1 is associated with the kinesin TbKIFC1, of which both the motor and vesicular trafficking VHS domains are required for MMP, but not for LMP. The presence of APOL1 in the mitochondrion is accompanied by mitochondrial membrane fenestration, which can be mimicked by knockdown of a mitochondrial mitofusin-like protein (TbMFNL). The BH3-like peptide of APOL1 is required for LMP, MMP and trypanolysis. Thus, trypanolysis by APOL1 is linked to apoptosis-like MMP occurring together with TbKIFC1-mediated transport of APOL1 from endolysosomal membranes to the mitochondrion., SCOPUS: ar.j, info:eu-repo/semantics/published

Ethylene is a gaseous plant hormone that most likely became a functional hormone during the evolution of charophyte green algae, prior to land colonization. From this ancient origin, ethylene evolved into an important growth regulator that is essential for myriad plant developmental processes. In vegetative growth, ethylene appears to have a dual role, stimulating and inhibiting growth, depending on the species, tissue, and cell type, developmental stage, hormonal status, and environmental conditions. Moreover, ethylene signaling and response are part of an intricate network in cross talk with internal and external cues. Besides being a crucial factor in the growth control of roots and shoots, ethylene can promote flowering, fruit ripening and abscission, as well as leaf and petal senescence and abscission and, hence, plays a role in virtually every phase of plant life. Last but not least, together with jasmonates, salicylate, and abscisic acid, ethylene is important in steering stress responses.

Caspases provide vital links in non-apoptotic regulatory networks controlling inflammation, compensatory proliferation, morphology and cell migration. How caspases are activated under non-apoptotic conditions and process a selective set of substrates without killing the cell remain enigmatic. Here we find that the Drosophila unconventional myosin CRINKLED (CK) selectively interacts with the initiator caspase DRONC and regulates some of its non-apoptotic functions. Loss of CK in the arista, border cells or proneural clusters of the wing imaginal discs affects DRONC-dependent patterning. Our data indicate that CK acts as substrate adaptor, recruiting SHAGGY46/GSK3-β to DRONC, thereby facilitating caspase-mediated cleavage and localized modulation of kinase activity. Similarly, the mammalian CK counterpart, MYO7A, binds to and impinges on CASPASE-8, revealing a new regulatory axis affecting receptor interacting protein kinase-1 (RIPK1)>CASPASE-8 signalling. Together, our results expose a conserved role for unconventional myosins in transducing caspase-dependent regulation of kinases, allowing them to take part in specific signalling events., Nature Communications, 7, ISSN:2041-1723

Most bacterial infections induce the activation of polymorphonuclear neutrophils (PMNs), enhance their microbicidal function, and promote the survival of these leukocytes for protracted periods of time. Brucella abortus is a stealthy pathogen that evades innate immunity, barely activates PMNs, and resists the killing mechanisms of these phagocytes. Intriguing clinical signs observed during brucellosis are the low numbers of Brucella infected PMNs in the target organs and neutropenia in a proportion of the patients; features that deserve further attention. Here we demonstrate that B. abortus prematurely kills human PMNs in a dose-dependent and cell-specific manner. Death of PMNs is concomitant with the intracellular Brucella lipopolysaccharide (Br-LPS) release within vacuoles. This molecule and its lipid A reproduce the premature cell death of PMNs, a phenomenon associated to the low production of proinflammatory cytokines. Blocking of CD14 but not TLR4 prevents the Br-LPS-induced cell death. The PMNs cell death departs from necrosis, NETosis and classical apoptosis. The mechanism of PMN cell death is linked to the activation of NADPH-oxidase and a modest but steadily increase of ROS mediators. These effectors generate DNA damage, recruitments of check point kinase 1, caspases 5 and to minor extent of caspase 4, RIP1 and Ca++ release. The production of IL-1β by PMNs was barely stimulated by B. abortus infection or Br-LPS treatment. Likewise, inhibition of caspase 1 did not hamper the Br-LPS induced PMN cell death, suggesting that the inflammasome pathway was not involved. Although activation of caspases 8 and 9 was observed, they did not seem to participate in the initial triggering mechanisms, since inhibition of these caspases scarcely blocked PMN cell death. These findings suggest a mechanism for neutropenia in chronic brucellosis and reveal a novel Brucella-host cross-talk through which B. abortus is able to hinder the innate function of PMN., Author Summary The absence of obvious clinical symptoms during the early stages of brucellosis is linked to the Brucella stealthy strategy and its non-canonical PAMPs, which are low PRRs agonists. Still, there are clinical profiles that require explanation. For instance ‒despite the fact that neutrophils readily ingest Brucella during the onset of infection, brucellosis courses without neutrophilia, and just a low number of infected neutrophils are present in target organs. In the chronic phases, a significant proportion of the patients display absolute neutropenia and bone marrow pancytopenia linked to the myeloid cell linage. Examination of the Brucella infected bone marrow reveals granulomas and phagocytosis of myeloid cells. Based on these observations we explored the fate of native neutrophils during their interaction with Brucella. We found that the bacterium induces the premature cell death of neutrophils without inducing proinflammatory phenotypic changes. This event was reproduced by the lipid A of the Brucella LPS and depends on NADPH-oxidase activation and low ROS formation. We believe that this phenomenon explains ‒at least in part‒ the hematological and histological profiles observed during brucellosis. In addition, it may be that dying Brucella-infected neutrophils serve as “Trojan horse” vehicles for infecting phagocytic cells without promoting activation.

International audience; Nitric oxide (NO) has many functions in plants. Here, we investigated its interplays with reactive oxygen species (ROS) in the defence responses triggered by the elicitin cryptogein. The production of NO induced by cryptogein in tobacco cells was partly regulated through a ROS-dependent pathway involving the NADPH oxidase NtRBOHD. In turn, NO down-regulated the level of H2O2. Both NO and ROS synthesis appeared to be under the control of type-2 histone deacetylases acting as negative regulators of cell death. Occurrence of an interplay between NO and ROS was further supported by the finding that cryptogein triggered a production of peroxynitrite (ONOO-). Next, we showed that ROS, but not NO, negatively regulate the intensity of activity of the cryptogein-induced protein kinase NtOSAK. Furthermore, using a DNA microarray approach, we identified 15 genes early induced by cryptogein via NO. A part of these genes was also modulated by ROS and encoded proteins showing sequence identity to ubiquitin ligases. Their expression appeared to be negatively regulated by ONOO-, suggesting that ONOO- mitigates the effects of NO and ROS. Finally, we provided evidence that NO required NtRBOHD activity for inducing cell death, thus confirming previous assumption that ROS channel NO through cell death pathways. The interplays between nitric oxide ( NO ) and reactive oxygen species ( ROS ) in the defense responses triggered by the elicitin cryptogein in tobacco cells were investigated. Both NO and ROS resulting from NADPH oxidase activity contribute to cryptogein-induced cell death and regulate the expression of genes encoding ubiquitine ligases. In turn, peroxynitrite mitigates the effects of NO and ROS .

As a source of bioactive ingredients, lettuce is a preferable component of a healthy diet. In recent years the production of fresh-cut produce has become a fast growing business. However, the shreds are highly sensitive to wound-induced browning and premature senescence that substantially reduces the visual and sensory qualities and shortens the shelf life. To improve the fresh-cut quality, in this work, short pre-storage exposure of shreds from butterhead and iceberg lettuce to nitric oxide (NO) gas was applied. It was found that fumigation with 100 and 200 ppm NO for 1 or 2 h remarkably inhibited the browning of the cut surface and of other injured leaf areas; NO treatment delayed the senescence and substantially prolonged the shelf life upon storage at 4 °C and 12 °C. To obtain information on the physiological processes involved in the wound response, the generation of hydrogen peroxide (H2O2) and the occurrence of cell death were analyzed. The results revealed that the wounding stimulated the accumulation of H2O2 thus generating oxidative stress leading to cell death. A correlation between elevated H2O2 levels, cut surface browning, senescence and storability of the fresh-cuts was established. In comparison to mature leaves, younger leaves expressed a lesser susceptibility to wound-induced browning and the associated oxidative stress. Applied NO strongly inhibited the H2O2 accumulation which may explain its beneficial effects.

Few diagnostic procedures are available to determine the degree of bone marrow cellularity and the numbers of cycling cells in patients with bone marrow disorders. Noninvasive imaging of the bone marrow compartment may be helpful. The PET tracer 3'-fluoro-3'-deoxy-L-thymidine (F-18-FLT) has been developed recently. F-18-FLT uptake is related to the rate of DNA synthesis and increases with higher proliferation rates in many types of cancer. Background uptake of F-18-FLT in bone marrow is common. F-18-FLT PET might, therefore, visualize the high cycling activity of hematopoietic cells in the bone marrow compartment. Therefore, we investigated the feasibility of visualization and quantification of the activity of the bone marrow compartment with F-18-FLT PET to distinguish different hematologic disorders. Methods: Clinical and laboratory data of 18 patients with myelodysplasia (MDS), chronic myeloproliferative disorders, myelofibrosis, aplastic anemia, or multiple myeloma were correlated with the results of F-18-FLT PET using visual analysis and the standardized uptake value (SUV). Findings were compared with those of healthy control subjects (n = 14). Results: With SUV and visual analysis, a distinction could be made between MDS (n = 9), chronic myeloproliferative disorders In = 3), and myelofibrosis (n = 3) compared with healthy control subjects. A significant increase in F-18-FLT uptake was observed in all of the studied patients with MDS and myeloproliferative disorders. In contrast, patients with myelofibrosis and aplastic anemia (n = 1) demonstrated a decline in bone marrow F-18-FLT uptake compared with healthy control subjects. Comparable results were observed in osteolytic lesions of patients with multiple myeloma (n = 2). Conclusion: F-18-FLT PET can be used to visualize the proliferative activity of the bone marrow compartment and may be helpful to distinguish separate hematologic disorders.

To identify genes required for the hypersensitive response (HR), we performed expression profiling of tomato plants mounting a synchronized HR, followed by functional analysis of differentially expressed genes. By cDNA-AFLP analysis, the expression profile of tomato plants containing both the Cf-4 resistance gene against Cladosporium fulvum and the matching Avr4 avirulence gene of this fungus was compared with that of control plants. About 1% of the transcript-derived fragments (442 out of 50,000) were derived from a differentially expressed gene. Based on their sequence and expression, 192 fragments, referred to as Avr4responsive tomato (ART) fragments, were selected for VIGS (virus-induced gene silencing) in Cf-4-transgenic Nicotiana benthamiana. Inoculated plants were analyzed for compromised HR by agroinfiltration of either the C. fulvum Avr4 gene or the Inf1 gene of Phytophthora infestans, which invokes a HR in wild-type N. benthamiana. VIGS using 15 of the ART fragments resulted in a compromised HR, whereas VIGS with fragments of ART genes encoding HSP90, a nuclear GTPase, an L19 ribosomal protein, and most interestingly, a nucleotide binding-leucine rich repeat (NB-LRR)-type protein severely suppressed the HR induced both by Avr4 and Inf1. Requirement of an NB-LRR protein (designated NRC1, for NB-LRR protein required for HR-associated cell death 1) for Cf resistance protein function as well as Inf1-mediated HR suggests a convergence of signaling pathways and supports the recent observation that NB-LRR proteins play a role in signal transduction cascades downstream of resistance proteins. Additional keywords: CC-NB-LRR, defense.

International audience; Desiccation tolerance (DT) in orthodox seeds is acquired during seed development and lost upon imbibition/germination, purportedly upon the resumption of DNA synthesis in the radicle cells. In the present study, flow cytometric analyses and visualization of microtubules (MTs) in radicle cells of seedlings of Medicago truncatula showed that up to a radicle length of 2 mm, there is neither DNA synthesis nor cell division, which were first detected in radicles with a length of 3 mm. However, DT started to be lost well before the resumption of DNA synthesis, when germinating seeds were dried back. By applying an osmotic treatment with polyethylene glycol (PEG) before dehydration, it was possible to re-establish DT in seedlings with a radicle up to 2 mm long. Dehydration of seedlings with a 2 mm radicle, with or without PEG treatment, caused disassembly of MTs and appearance of tubulin granules. Subsequent pre-humidification led to an almost complete disappearance of both MTs and tubulin granules. Upon rehydration, neither MTs nor tubulin granules were detected in radicle cells of untreated seedlings, while PEG-treated seedlings were able to reconstitute the microtubular cytoskeleton and continue their normal development. Dehydration of untreated seedlings also led to an apoptotic-like DNA fragmentation in radicle cells, while in PEG-treated seedlingss DNA integrity was maintained. The results showed that for different cellular components, desiccation-tolerant seedlings may apply distinct strategies to survive dehydration, either by avoidance or further repair of the damages

Repinotan HCl (repinotan, BAY x 3702), a highly selective 5-HT1A receptor agonist with a good record of safety was found to have pronounced neuroprotective effects in experimental models that mimic various aspects of brain injury. Repinotan caused strong, dose-dependent infarct reductions in permanent middle cerebral artery occlusion, transient middle cerebral artery occlusion, and traumatic brain injury paradigms. The specific 5-HT1A receptor antagonist WAY 100635 blocked these effects, indicating that the neuroprotective properties of repinotan are mediated through the 5-HT1A receptor.The proposed neuroprotective mechanisms of repinotan are thought to be the result of neuronal hyperpolarization via the activation of G protein-coupled inwardly rectifying K+ channels upon binding to both pre- and post-synaptic 5-HT1A receptors. Hyperpolarization results in inhibition of neuron firing and reduction of glutamate release. These mechanisms, leading to protection of neurons against overexcitation, could explain the neuroprotective efficacy of repinotan per se, but not necessarily the efficacy by delayed administration. The therapeutic time window of repinotan appeared to be at least 5 h in in vivo animal models, but may be even longer at higher doses of the drug.Experimental studies indicate that repinotan affects various mechanisms involved in the pathogenesis of brain injury. In addition to the direct effect of repinotan on neuronal hyperpolarization and suppression of glutamate release this compound affects the death,inhibiting protein Bcl-2, serotonergic glial growth factor S-100 beta and Nerve Growth Factor. It also suppresses the activity of caspase-3 through MAPK and PKC alpha; this effect may contribute to its neuroprotective efficacy. The dose- and time-dependent neuroprotective efficacy of repinotan indicates that the drug is a promising candidate for prevention of secondary brain damage in brain-injured patients suffering from acute ischemic stroke. Unfortunately, however, the first, randomized, double blind, placebo-controlled clinical trial did not demonstrate the efficacy of repinotan in acute ischemic stroke.

Visible symptoms of tepal senescence in cut Iris x hollandica (cv. Blue Magic) flowers were delayed by placing one cut daffodil flower (Narcissus pseudonarcissus, cv. Carlton) in the same vase. Addition of mucilage, exuded by daffodil stems, to the vase water had the same effect as the flowering daffodil stem. The active compound in the mucilage was identified as narciclasine (using LC/MS, GC/MS, H-1 and C-13-NMR, and comparison with an authentic sample of narciclasine). The delay of senescence, either by mucilage or purified narciclasine, was correlated with a delayed increase in protease activity, and with a considerable reduction of maximum protease activity. Narciclasine did not affect in vitro protease activity, but is known to inhibit protein synthesis at the ribosomal level. Its effects on senescence and protease activity were similar to those of cycloheximide (CHX), another inhibitor of protein synthesis, but the effective narciclasine concentration was about 100 times lower than that of CHX. It is concluded that the delay of Iris tepal senescence by daffodil stems is due to narciclasine in daffodil mucilage, which apparently inhibits the synthesis of proteins involved in senescence. (C) 2003 Elsevier Ltd. All rights reserved.

Transcriptomic and proteomic technologies are generating a wealth of data that are frequently used by scientists to predict the function of proteins based on their expression or presence. However, activity of many proteins, such as transcription factors, kinases, and proteases, depends on posttranslational modifications that frequently are not detected by these technologies. Therefore, to monitor activity of proteases rather than their abundance, we introduce protease activity profiling in plants. This technology is based on the use of biotinylated, irreversible protease inhibitors that react with active proteases in a mechanism-based manner. Using a biotinylated derivative of the Cys protease inhibitor E-64, we display simultaneous activities of many papain-like Cys proteases in extracts from various tissues and from different plant species. Labeling is pH dependent, stimulated with reducing agents, and inhibited specifically by Cys protease inhibitors but not by inhibitors of other protease classes. Using one-step affinity capture of biotinylated proteases followed by sequencing mass spectrometry, we identified proteases that include xylem-specific XCP2, desiccation-induced RD21, and cathepsin B- and aleurain-like proteases. Together, these results demonstrate that this technology can identify differentially activated proteases and/or characterize the activity of a particular protease within complex mixtures.

The availability of a noninvasive method to detect and quantify apoptosis in tumours will enable tumour response to several cancer therapies to be assessed. We have synthesised two radiotracers, annexin V and the N-succinimidyl-3-iodobenzoic acid (SIB) derivative of annexin V, labelled with radio-iodine ((124)I and (125)I) and provided proof of the concept by assessing specific binding and biodistribution of these probes to apoptotic cells and tumours. We have also assessed the tumour uptake of [(124)I]annexin V in a mouse model of apoptosis. RIF-1 cells induced to undergo apoptosis in vitro showed a drug concentration-dependent increased binding of [(125)I]annexin V and [(125)I]SIB-annexin V. In the same model system, there was an increase in terminal deoxynucleotidyl transferase-mediated nick end labelling (TUNEL)-positive cells and a decrease in clonogenic survival. Radiotracer binding was completely inhibited by preincubation with unlabelled annexin V. In RIF-1 tumour-bearing mice, rapid distribution of [(125)I]SIB-annexin V-derived radioactivity to kidneys was observed and the radiotracer accumulated in urine. The binding of [(125)I]SIB-annexin V to RIF-1 tumours increased by 2.3-fold at 48 h after a single intraperitoneal injection of 5-fluorouracil (165 mg kg(-1) body weight), compared to a 4.4-fold increase in TUNEL-positive cells measured by immunostaining. Positron emission tomography images with both radiotracers demonstrated intense localisation in the kidneys and bladder. Unlike [(124)I]SIB-annexin V, [(124)I]annexin V also showed localisation in the thyroid region presumably due to deiodination of the radiolabel. [(124)I]SIB-annexin V is an attractive candidate for in vivo imaging of apoptosis by PET.

Sphingolipids are a diverse group of lipids found in all eukaryotes and some bacteria, consisting of a hydrophobic ceramide and a hydrophilic head group. We have summarised the contemporary understanding of the structure of plant sphingolipids with an emphasis on glucosylceramides and inositolphosphorylceramides. Plant glucosylceramides are important structural components of plasma and vacuole membranes. inositolphosphorylceramides have been identified as moieties of the glycosylphosphorylinositol (GPI) anchors of plant proteins targeted to the plasma membrane. in the last few years, progress has been made in the cloning of plant genes coding for enzymes involved in sphingolipid metabolism. As found in yeast and mammals, the plant sphingolipid pathway is a potential generator of powerful cell signals. The role of plant sphingolipid metabolites in programmed cell death and calcium influx is discussed.

Objectives of this study are to describe the biological basis for multiphasic milk production and to propose a new empirical model for the lactation curve. To illustrate this model, we used data on 3573 first-lactation Holsteins having lactations of various lengths (285, 345, 405, 465, and 525 d) and with various days open (45, 105, 165, 225, and 285 d). The model describes an increasing first phase of milk yield and a series of decreasing phases of yield. The increasing phase, described by an increasing logistic function of time, is associated with increase in number of active mammary gland cells and increase in yield per cell. The decreasing phases, described by three decreasing logistic functions of time, are associated with decreases in cell number due to apoptosis and in yield per cell due to pregnancy. The new model is [GRAPHICS] where Y-DIM is milk yield at each day in milk (DIM), a, is upper level for the increasing first phase, and p(2), p(3), and p(4) = (1 - p(2) - p(3)) are proportions of a(1) for the decreasing second, third, and fourth phases; b's are proportional to duration of each phase; and c's are time of maximum increase or decrease. Nonlinear regression was used to fit average milk yield for each of nine datasets, four with 180 d carried calf and five with 240 d carried calf. Average results indicated that for the first phase, upper level of milk yield was about 22 kg. Duration was about 120 d, centered on time of maximum increase, which was about 11 d before calving. For the second phase (first phase of apoptosis), decrease in yield was relatively large (about 20%) and duration was relatively long (about 375 d). Time of maximum decrease was about 107 d after calving. For the third phase (pregnancy), decrease in yield was relatively small (about 6%) and duration was relatively short (about 200 d). Time of maximum decrease was about 300 d after calving. For each additional day open, time of maximum decrease increased about 1 d. For the fourth phase (second phase of apoptosis), decrease in yield was relatively large (about 74%) and duration was relatively long (about 765 d). Duration for the lactation length of 525 d was exceptionally long. Time of maximum decrease was about 382 d after calving. For each additional day of lactation, duration increased about 5.4 d and day of maximum decrease increased about 0.82 d. We believe that it is possible to model empirically standard and extended lactation curves of dairy cows, based on biological theory and predicated on the multiphasic approach. Further research to understand better the biology of extended lactations, using the proposed multiphasic model, should use planned extended lactations that are at least 525 d in milk and have at least 240 d carried calf.

The development of colorectal cancer is characterised by an accumulation of molecular genetic alterations causing disorders in cell growth, differentiation and apoptosis. Although changes in apoptosis with colorectal cancer development have been studied extensively, a clear consensus of opinion has not yet emerged. In this review, the literature about changes in the frequency and distribution of apoptosis in tissue sections of normal and neoplastic colorectal tissues was reviewed systematically. Using a PUBMED search, 53 relevant articles were identified. Data from these studies are discussed with respect to the following aspects: methods used to detect apoptotic cell death; frequency and locoregional distribution of apoptosis in normal mucosa, adenomas and carcinomas; the correlation between levels of apoptosis and proliferation and the prognostic significance of the degree of apoptosis in colorectal cancer. Possible underlying mechanisms of dysregulation of apoptosis are discussed briefly. Finally, possible therapeutic implications of knowledge of the molecular regulation of apoptosis are discussed and potential options for further research are suggested. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Alternaria species are mainly saprophytic fungi. However, some species have acquired pathogenic capacities collectively causing disease over a broad host range. This review summarizes the knowledge on pathogenic strategies employed by the fungus to plunder the host. Furthermore, strategies employed by potential host plants in order to ward off an attack are discussed. Taxonomy: Alternaria spp. kingdom Fungi, subkingdom Eumycotera, phylum Fungi Imperfecti (a non-phylogenetic or artificial phylum of fungi without known sexual stages whose members may or may not be related; taxonomy does not reflect relationships), form class Hypomycetes, Form order Moniliales, form family Dematiaceae, genus Alternaria. Some species of Alternaria are the asexual anamorph of the ascomycete Pleospora while others are speculated to be anamorphs of Leptosphaeria.. Host range: Most Alternaria species are common saprophytes that derive energy as a result of cellulytic activity and are found in a variety of habitats as ubiquitous agents of decay. Some species are plant pathogens that cause a range of economically important diseases like stem cancer, leaf blight or leaf spot on a large variety of crops. Latent infections can occur and result in post-harvest diseases or damping-off in case of infected seed. Useful website: .

Cardiovascular disease is a leading cause of death worldwide. In recent years it has emerged that loss of myocardial cells may be a major pathogenic factor. Cell death can occur in a destructive, uncontrolled manner via necrosis or by a highly regulated programmed cell suicide mechanism termed apoptosis. As cell death in conditions such as heart failure and myocardial infarction does not always follow a typically apoptotic pathway, it remains to be established whether it occurs by apoptosis, necrosis, or a novel uncharacterized mechanism combining aspects of both types of cell death. Apoptotic pathways have been well studied in nonmyocytes and it is thought that similar pathways exist in cardiomyocytes. These pathways include death initiated by ligation of membrane-bound death receptors or death initiated by release of cytochrome c from mitochondria. Increasing evidence supports the existence of these pathways and their regulators in the heart. These regulators include inhibitors of caspases, which are the key enzymes of apoptosis, the Bcl-2 family of proteins, growth factors, stress proteins, calcium, and oxidants. It is hoped that a better understanding of the pathways of apoptosis and their regulation may yield novel therapeutic targets for cardiovascular disease.

Cytosolic spermidine/spermine acetyltransferase (SSAT) catalyzes the acetylation of the N 1 -propylamino groups of spermine and spermidine. The enzyme has a very short half-life and is rapidly induced by various stimuli. Once acetylated, these polyamines are subjected to the action of polyamine oxidase, which, besides initiating polyamine catabolism, may produce reactive oxygen species that in turn trigger modifications in subcellular compartments such as mitochondria. The present work evaluates the ability of the cAMP-independent Ser/Thr-protein kinase CK1 to phosphorylate SSAT. Results demonstrate that SSAT is phosphorylated by CK1, in sites distinct from those phosphorylated by CK2. Moreover, both phosphorylation processes are involved in the uptake of SSAT into rat liver mitochondria. Although CK2 is less effective than CK1 in phosphorylating SSAT, CK2 phosphorylation is much more powerful in preventing binding of SSAT to mitochondrial structures. These results suggest the involvement of CK1- and CK2-mediated SSAT phosphorylation in regulating the contents of polyamines and SSAT itself within subcellular compartments and implicate SSAT and polyamines as indirect modulators of progression through the cell cycle.

Due to the key role of the lung in efficient transfer of oxygen in exchange for carbon dioxide, a controlled inflammatory response is essential for restoration of tissue homeostasis following airway exposure to bacterial pathogens or environmental toxins. Unregulated or prolonged inflammatory responses in the lungs can lead to tissue damage, disrupting normal tissue architecture, and consequently compromising efficient gaseous exchange. Failure to resolve inflammation underlies the development and/or progression of a number of inflammatory lung diseases including asthma. Eosinophils, granulocytic cells of the innate immune system, are primarily involved in defense against parasitic infections. However, the propagation of the allergic inflammatory response in chronic asthma is thought to involve excessive recruitment and impaired apoptosis of eosinophils together with defective phagocytic clearance of apoptotic cells (efferocytosis). In terms of therapeutic approaches for the treatment of asthma, the widespread use of glucocorticoids is associated with a number of adverse health consequences after long-term use, while some patients suffer from steroid-resistant disease. A new approach for therapeutic intervention would be to promote the resolution of inflammation via modulation of eosinophil apoptosis and the phagocytic clearance of apoptotic cells. This review focuses on the mechanisms underpinning eosinophil-mediated lung damage, currently available treatments and therapeutic targets that might in future be harnessed to facilitate inflammation resolution by the manipulation of cell survival and clearance pathways.

Plants growing in their natural habitats are often challenged simultaneously by multiple stress factors, both abiotic and biotic. Research has so far been limited to responses to individual stresses, and understanding of adaptation to combinatorial stress is limited, but indicative of non-additive interactions. Omics data analysis and functional characterization of individual genes has revealed a convergence of signaling pathways for abiotic and biotic stress adaptation. Taking into account that most data originate from imposition of individual stress factors, this review summarizes these findings in a physiological context, following the pathogenesis timeline and highlighting potential differential interactions occurring between abiotic and biotic stress signaling across the different cellular compartments and at the whole plant level. Potential effects of abiotic stress on resistance components such as extracellular receptor proteins, R-genes and systemic acquired resistance will be elaborated, as well as crosstalk at the levels of hormone, reactive oxygen species, and redox signaling. Breeding targets and strategies are proposed focusing on either manipulation and deployment of individual common regulators such as transcription factors or pyramiding of non- (negatively) interacting components such as R-genes with abiotic stress resistance genes. We propose that dissection of broad spectrum stress tolerance conferred by priming chemicals may provide an insight on stress cross regulation and additional candidate genes for improving crop performance under combined stress. Validation of the proposed strategies in lab and field experiments is a first step toward the goal of achieving tolerance to combinatorial stress in crops.

When the glucose supply is high, despite the presence of oxygen Saccharomyces cerevisiae uses fermentation as its main metabolic pathway and switches to oxidative metabolism only when this carbon source is limited. There are similarities between glucose-induced repression of oxidative metabolism of yeast and metabolic reprogramming of tumor cells. The glucose-induced repression of oxidative metabolism is regulated by oncogene homologues in yeast, such as Ras and Sch9p, the yeast homologue of Akt. Yeast also undergoes an apoptosis-like programmed cell death process sharing several features with mammalian apoptosis, including oxidative stress and a major role played by mitochondria. Evasion of apoptosis and sustained proliferative signalling are hallmarks of cancer. This, together with the possibility of heterologous expression of human genes in yeast, has allowed new insights to be obtained into the function of mammalian oncogenes/oncosuppressors. Here we elaborate on the similarities between tumor and yeast cells underpinning the use of this model organism in cancer research. We also review the achievements obtained through heterologous expression in yeast of p53, BRCA1 and BRCA2 which are among the best known cancer susceptibility genes, with the aim of understanding their role in tumorigenesis. Yeast cell-based functional assays for cancer genetic testing will also be dealt with. This article is protected by copyright. All rights reserved.

International audience; PIRIN (PRN) is a member of the functionally diverse cupin protein superfamily. There are four members of the Arabidopsis thaliana PRN family, but the roles of these proteins are largely unknown. Here we describe a function of the Arabidopsis PIRIN2 (PRN2) that is related to susceptibility to the bacterial plant pathogen Ralstonia solanacearum. Two prn2 mutant alleles displayed decreased disease development and bacterial growth in response to R. solanacearum infection. We elucidated the underlying molecular mechanism by analyzing PRN2 interactions with the papain-like cysteine proteases (PLCPs) XCP2, RD21A, and RD21B, all of which bound to PRN2 in yeast two-hybrid assays and in Arabidopsis protoplast co-immunoprecipitation assays. We show that XCP2 is stabilized by PRN2 through inhibition of its autolysis on the basis of PLCP activity profiling assays and enzymatic assays with recombinant protein. The stabilization of XCP2 by PRN2 was also confirmed in planta. Like prn2 mutants, an xcp2 single knockout mutant and xcp2 prn2 double knockout mutant displayed decreased susceptibility to R.solanacearum, suggesting that stabilization of XCP2 by PRN2 underlies susceptibility to R.solanacearum in Arabidopsis.

Administration of most chemotherapeutic agents eventually results in the onset of apoptosis, despite the agents' variety in structure and molecular targets. Ceramide, the central molecule in cellular glycosphingolipid metabolism, has recently been identified as an important mediator of this process. Indeed, one of the events elicited by application of many cytotoxic drugs is an accumulation of this lipid. Treatment failure in cancer chemotherapy is largely attributable to multidrug resistance, in which tumor cells are typically cross-resistant to multiple chemotherapeutic agents. Different cellular mechanisms underlying this phenomenon have been described. Of these the drug efflux pump activity of P-glycoprotein and the multidrug resistance-associated proteins are the most extensively studied examples. Recently, an increased cellular capacity for ceramide glycosylation has been recognized as a novel multidrug resistance mechanism. Indeed, virtually all multidrug-resistant cells exhibit a deviating sphingolipid composition, most typically, increased levels of glucosylceramide. On the other hand, several direct molecular interactions between sphingolipids and drug efflux proteins have been described. Therefore, in addition to a role in the multidrug resistance phenotype by which ceramide accumulation and, thus, the onset of apoptosis are prevented, an indirect role for sphingolipids might be envisaged, by which the activity of these efflux proteins is modulated. In this review, we present an overview of the current understanding of the interesting relations that exist between sphingolipid metabolism and multidrug resistance.

Administration of most chemotherapeutic agents eventually results in the onset of apoptosis, despite the agents variety in structure and molecular targets. Ceramide, the central molecule in cellular glycosphingolipid metabolism, has recently been identified as an important mediator of this process. Indeed. one of the events elicited by application of many cytotoxic drugs is an accumulation of this lipid. Treatment failure in cancer chemotherapy is largely attributable to multidrug resistance, in which tumor cells are typically cross-resistant to multiple chemotherapeutic agents. Different cellular mechanisms underlying this phenomenon have been described. Of these the drug efflux pump activity of P-glycoprotein and the multidrug resistance-associated proteins are the most extensively studied examples, Recently, an increased cellular capacity for ceramide glycosylation has been recognized as a novel multidrug resistance mechanism. Indeed, virtually all multidrug-resistant cells exhibit a deviating sphingolipid composition, most typically, increased levels of glucosylceramide, On the other hand, several direct molecular interactions between sphingolipids and drug efflux proteins have been described. Therefore, in addition to a role in the multidrug resistance phenotype by which ceramide accumulation and, thus, the onset of apoptosis are prevented, an indirect role for sphingolipids might be envisaged, by which the activity of these efflux proteins is modulated. In this review, we present an overview of the current understanding of the interesting relations that exist between sphingolipid metabolism and multidrug resistance.

Background: Chronic use of sennoside laxatives often causes pseudomelanosis coli. A recent study suggested that pseudomelanosis coli is associated with an increased colorectal cancer risk. A single high dose of highly purified senna extract increased proliferation rate and reduced crypt length in the sigmoid colon compared to historical controls. Aims: To evaluate in a controlled study the effects of highly purified senna extract on cell proliferation and crypt length in the entire colon and on p53 and bcl-2 expression. Methods: Addition of a senna extract to colonic lavage was studied in 184 consecutive outpatients. From 32 randomised patients, 15 with sennosides (Sen), 17 without (NSen), biopsies were taken. Proliferative activity was studied in 4 areas of the colon, using 5-bromo-2′-deoxyuridine labelling and immunohistochemistry (labelling index, LI). Expression of p53 and bcl-2 in the sigmoid colon was determined immunohistochemically. Results: Crypts were shorter in Sen than in NSen in the transverse and sigmoid colon. LI was higher in Sen than in NSen in the entire colon. No difference in p53 expression was seen. Bcl-2 expression was higher in both groups when crypts were shorter and/or proliferation was increased. Conclusion: Sennosides induce acute massive cell loss probably by apoptosis, causing shorter crypts, and increased cell proliferation and inhibition of apoptosis to restore cellularity. These effects may reflect the mechanism for the suggested cancer-promoting effect of chronic sennoside use.