Effect of sequential heat and cold shocks on nuclear phenotypes of the blood-sucking insect, Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae)

Thermal shocks induce changes in the nuclear phenotypes that correspond to survival (heterochromatin decondensation, nuclear fusion) or death (apoptosis, necrosis) responses in the Malpighian tubules of Panstrongylus megistus. Since thermal tolerance increased survival and molting rate in this species following sequential shocks, we investigated whether changes in nuclear phenotypes accompanied the insect survival response to sequential thermal shocks. Fifth instar nymphs were subjected to a single heat (35 or 40°C, 1 h) or cold (5 or 0°C, 1 h) shock and then subjected to a second shock for 12 h at 40 or 0°C, respectively, after 8, 18, 24 and 72 h at 28°C (control temperature). As with specimen survival, sequential heat and cold shocks induced changes in frequency of the mentioned nuclear phenotypes although their patterns differed. The heat shock tolerance involved decrease in apoptosis simultaneous to increase in cell survival responses. Sequential cold shocks did not involve cell/nuclear fusion and even elicited increase in necrosis with advancing time after shocks. The temperatures of 40 and 0ºC were more effective than the temperatures of 35 and 5ºC in eliciting the heat and cold shock tolerances, respectively, as shown by cytological analysis of the nuclear phenotypes. It is concluded that different sequential thermal shocks can trigger different mechanisms of cellular protection against stress in P. megistus, favoring the insect to adapt to various ecotopes.

Characterization of TcSTI-1, a homologue of stress-induced protein-1, in Trypanosoma cruzi

The life cycle of the protozoan Trypanosoma cruzi exposes it to several environmental stresses in its invertebrate and vertebrate hosts. Stress conditions are involved in parasite differentiation, but little is known about the stress response proteins involved. We report here the first characterization of stress-induced protein-1 (STI-1) in T. cruzi (TcSTI-1). This co-chaperone is produced in response to stress and mediates the formation of a complex between the stress proteins HSP70 and HSP90 in other organisms. Despite the similarity of TcSTI-1 to STI-1 proteins in other organisms, its expression profile in response to various stress conditions, such as heat shock, acidic pH or nutrient starvation, is quite different. Neither polysomal mRNA nor protein levels changed in exponentially growing epimastigotes cultured under any of the stress conditions studied. Increased levels of TcSTI-1 were observed in epimastigotes subjected to nutritional stress in the late growth phase. Co-immunoprecipitation assays revealed an association between TcSTI-1 and TcHSP70 in T. cruzi epimastigotes. Immunolocalization demonstrated that TcSTI-1 was distributed throughout the cytoplasm and there was some colocalization of TcSTI-1 and TcHSP70 around the nucleus. Thus, TcSTI-1 associates with TcHSP70 and TcSTI-1 expression is induced when the parasites are subjected to stress conditions during specific growth phase.

Mapping the proteome of Leishmania Viannia parasites using two-dimensional polyacrylamide gel electrophoresis and associated technologies.

In this study we have demonstrated the potential of two-dimensional electrophoresis (2DE)-based technologies as tools for characterization of the Leishmania proteome (the expressed protein complement of the genome). Standardized neutral range (pH 5-7) proteome maps of Leishmania (Viannia) guyanensis and Leishmania (Viannia) panamensis promastigotes were reproducibly generated by 2DE of soluble parasite extracts, which were prepared using lysis buffer containing urea and nonidet P-40 detergent. The Coomassie blue and silver nitrate staining systems both yielded good resolution and representation of protein spots, enabling the detection of approximately 800 and 1,500 distinct proteins, respectively. Several reference protein spots common to the proteomes of all parasite species/strains studied were isolated and identified by peptide mass spectrometry (LC-ES-MS/MS), and bioinformatics approaches as members of the heat shock protein family, ribosomal protein S12, kinetoplast membrane protein 11 and a hypothetical Leishmania-specific 13 kDa protein of unknown function. Immunoblotting of Leishmania protein maps using a monoclonal antibody resulted in the specific detection of the 81.4 kDa and 77.5 kDa subunits of paraflagellar rod proteins 1 and 2, respectively. Moreover, differences in protein expression profiles between distinct parasite clones were reproducibly detected through comparative proteome analyses of paired maps using image analysis software. These data illustrate the resolving power of 2DE-based proteome analysis. The production and basic characterization of good quality Leishmania proteome maps provides an essential first step towards comparative protein expression studies aimed at identifying the molecular determinants of parasite drug resistance and virulence, as well as discovering new drug and vaccine targets.

The JNK binding domain of islet-brain 1 inhibits IL-1 induced JNK activity and apoptosis but not the transcription of key proapoptotic or protective genes in insulin-secreting cell lines.

The stress-activated protein kinase c-Jun NH2-terminal kinase (JNK) is a central signal for interleukin-1beta (IL-1beta)-induced apoptosis in insulin-producing beta-cells. The cell-permeable peptide inhibitor of JNK (JNKI1), that introduces the JNK binding domain (JBD) of the scaffold protein islet-brain 1 (IB1) inside cells, effectively prevents beta-cell death caused by this cytokine. To define the molecular targets of JNK involved in cytokine-induced beta-cell apoptosis we investigated whether JNKI1 or stable expression of JBD affected the expression of selected pro- and anti-apoptotic genes induced in rat (RIN-5AH-T2B) and mouse (betaTC3) insulinoma cells exposed to IL-1beta. Inhibition of JNK significantly reduced phosphorylation of the specific JNK substrate c-Jun (p<0.05), IL-1beta-induced apoptosis (p<0.001), and IL-1beta-mediated c-fos gene expression. However, neither JNKI1 nor JBD did influence IL-1beta-induced NO synthesis or iNOS expression or the transcription of the genes encoding mitochondrial manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase rho (GSTrho), heat shock protein (HSP) 70, IL-1beta-converting enzyme (ICE), caspase-3, apoptosis-inducing factor (AIF), Bcl-2 or Bcl-xL. We suggest that the anti-apoptotic effect of JNK inhibition by JBD is independent of the transcription of major pro- and anti-apoptotic genes, but may be exerted at the translational or posttranslational level.

Magnetic and in vitro heating properties of implants formed in situ from injectable formulations and containing superparamagnetic iron oxide nanoparticles (SPIONs) embedded in silica microparticles for magnetically induced local hyperthermia

The biological and therapeutic responses to hyperthermia, when it is envisaged as an anti-tumor treatment modality, are complex and variable. Heat delivery plays a critical role and is counteracted by more or less efficient body cooling, which is largely mediated by blood flow. In the case of magnetically mediated modality, the delivery of the magnetic particles, most often superparamagnetic iron oxide nanoparticles (SPIONs), is also critically involved. We focus here on the magnetic characterization of two injectable formulations able to gel in situ and entrap silica microparticles embedding SPIONs. These formulations have previously shown suitable syringeability and intratumoral distribution in vivo. The first formulation is based on alginate, and the second on a poly(ethylene-co-vinyl alcohol) (EVAL). Here we investigated the magnetic properties and heating capacities in an alternating magnetic field (141 kHz, 12 mT) for implants with increasing concentrations of magnetic microparticles. We found that the magnetic properties of the magnetic microparticles were preserved using the formulation and in the wet implant at 37 degrees C, as in vivo. Using two orthogonal methods, a common SLP (20 Wg(-1)) was found after weighting by magnetic microparticle fraction, suggesting that both formulations are able to properly carry the magnetic microparticles in situ while preserving their magnetic properties and heating capacities. (C) 2010 Elsevier B.V. All rights reserved.

Molecular chaperones and associated cellular clearance mechanisms against toxic protein conformers in Parkinson's disease.

Parkinson's disease (PD) is a slowly progressive neurodegenerative disorder marked by the loss of dopaminergic neurons (in particular in the substantia nigra) causing severe impairment of movement coordination and locomotion, associated with the accumulation of aggregated α-synuclein (α-Syn) into proteinaceous inclusions named Lewy bodies. Various early forms of misfolded α-Syn oligomers are cytotoxic. Their formation is favored by mutations and external factors, such as heavy metals, pesticides, trauma-related oxidative stress and heat shock. Here, we discuss the role of several complementing cellular defense mechanisms that may counteract PD pathogenesis, especially in youth, and whose effectiveness decreases with age. Particular emphasis is given to the 'holdase' and 'unfoldase' molecular chaperones that provide cells with potent means to neutralize and scavenge toxic protein conformers. Because chaperones can specifically recognize misfolded proteins, they are key specificity factors for other cellular defenses, such as proteolysis by the proteasome and autophagy. The efficiency of the cellular defenses decreases in stressed or aging neurons, leading to neuroinflammation, apoptosis and tissue loss. Thus, drugs that can upregulate the molecular chaperones, the ubiquitin-proteasome system and autophagy in brain tissues are promising avenues for therapies against PD and other mutation-, stress- or age-dependent protein-misfolding diseases.

In vitro effect of malachite green on Candida albicans involves multiple pathways and transcriptional regulators UPC2 and STP2.

In this study, we show that a chemical dye, malachite green (MG), which is commonly used in the fish industry as an antifungal, antiparasitic, and antibacterial agent, could effectively kill Candida albicans and non-C. albicans species. We have demonstrated that Candida cells are susceptible to MG at a very low concentration (MIC that reduces growth by 50% [MIC(50)], 100 ng ml(-1)) and that the effect of MG is independent of known antifungal targets, such as ergosterol metabolism and major drug efflux pump proteins. Transcriptional profiling in response to MG treatment of C. albicans cells revealed that of a total of 207 responsive genes, 167 genes involved in oxidative stress, virulence, carbohydrate metabolism, heat shock, amino acid metabolism, etc., were upregulated, while 37 genes involved in iron acquisition, filamentous growth, mitochondrial respiration, etc., were downregulated. We confirmed experimentally that Candida cells exposed to MG resort to a fermentative mode of metabolism, perhaps due to defective respiration. In addition, we showed that MG triggers depletion of intracellular iron pools and enhances reactive oxygen species (ROS) levels. These effects could be reversed by the addition of iron or antioxidants, respectively. We provided evidence that the antifungal effect of MG is exerted through the transcription regulators UPC2 (regulating ergosterol biosynthesis and azole resistance) and STP2 (regulating amino acid permease genes). Taken together, our transcriptome, genetic, and biochemical results allowed us to decipher the multiple mechanisms by which MG exerts its anti-Candida effects, leading to a metabolic shift toward fermentation, increased generation of ROS, labile iron deprivation, and cell necrosis.

The CaMV 35S promoter has a weak expression activity in dark grown tissues of moss Physcomitrella patens.

The constitutive Cauliflower Mosaic Virus 35S promoter (CaMV 35S) is widely used as a tool to express recombinant proteins in plants, but with different success. We previously showed that the expression of an F-actin marker, GFP-talin, in Physcomitrella patens using the CaMV 35S promoter failed to homogenously label moss tissues. Here, we show a significant diminution of the GFP fluorescence in dark grown old moss cells and complete lack of labelling in newly differentiated cells. Furthermore, we demonstrate that stable moss lines harbouring a resistance cassette driven by the CaMV 35S are unable to grow in darkness in the presence of the antibiotic. In contrast to the CaMV 35S, the heat inducible promoter, hsp17.3B showed uniform expression pattern in all cells and tissues following a mild heat shock.

Study of protein complexes

Summary : A lot of information can be obtained on proteins when proteomics methods are used. In our study, we aimed to characterize complexes containing pro-apoptotic proteins by different proteomics methods and finally focused on PIDD (p53-induced protein with a death domain), for which the most interesting results were obtained. PIDD has been shown to function as a molecular switch between genotoxic stress-induced apoptotis and genotoxic stress-induced cell survival through NF-κB activation. To exert these two functions, PIDD forms alternate complexes respectively with caspase2 and CRADD on one hand and RIP 1 and NEMO on the other hand. The first part of our study focuses on the processing of PIDD. PIDD full length (FL) is constitutively cleaved into three fragments, an N-terminal one (PIDD-N) and two fragments containing the C-terminus (PIDD-C and PIDD-CC). Localization of the two PIDD cleavage sites by mass spectrometry (MS) allowed to understand that PIDD is probably not cleaved by proteases but is subject to protein (self-)splicing and also to map the PIDD-N, PIDD-C and PIDD-CC fragments exactly. Further characterization of these three fragments by Tinel et al. (Tinel et al., 2007) showed that PIDD-C is involved in activation of an apoptotic pathway while PIDD-CC is involved in NF-κB activation. We also found that PIDD is subject to proline-directed phosphorylation at two serine residues in PIDD-N, the regulatory fragment of PIDD. The second part of the study aimed at identifying by proteomics techniques proteins that co-purify with PIDD and therefore are putative cellular interaction partners. In this respect we analyzed samples obtained in different conditions or with different PIDD constructs corresponding to processed fragments. This allowed us to identify a large number of potential interactors for PIDD. For example, by comparing data obtained from PIDD-C and PIDD-FL affinity purifications, we found that the Hsp90 chaperone system interacts strongly with PIDD-N. In the third part of this study, we developed methods to selectively and rapidly quantify by MS proteins of interest in PIDD affinity purifications or negative controls. Using these tools we detected significant changes in PIDD-FL-copurifying proteins treated by heat shock. Overall, our studies provide informative data on the processing of PIDD and its possible involvement in several molecular pathways.

Reactivation of protein aggregates by mortalin and Tid1-the human mitochondrial Hsp70 chaperone system.

The mitochondrial 70-kDa heat shock protein (mtHsp70), also known in humans as mortalin, is a central component of the mitochondrial protein import motor and plays a key role in the folding of matrix-localized mitochondrial proteins. MtHsp70 is assisted by a member of the 40-kDa heat shock protein co-chaperone family named Tid1 and a nucleotide exchange factor. Whereas, yeast mtHsp70 has been extensively studied in the context of protein import in the mitochondria, and the bacterial 70-kDa heat shock protein was recently shown to act as an ATP-fuelled unfolding enzyme capable of detoxifying stably misfolded polypeptides into harmless natively refolded proteins, little is known about the molecular functions of the human mortalin in protein homeostasis. Here, we developed novel and efficient purification protocols for mortalin and the two spliced versions of Tid1, Tid1-S, and Tid1-L and showed that mortalin can mediate the in vitro ATP-dependent reactivation of stable-preformed heat-denatured model aggregates, with the assistance of Mge1 and either Tid1-L or Tid1-S co-chaperones or yeast Mdj1. Thus, in addition of being a central component of the protein import machinery, human mortalin together with Tid1, may serve as a protein disaggregating machine which, for lack of Hsp100/ClpB disaggregating co-chaperones, may carry alone the scavenging of toxic protein aggregates in stressed, diseased, or aging human mitochondria.

Tumor necrosis factor-alpha and alphaB-crystallin up-regulation during antibody-mediated demyelination in vitro: a putative protective mechanism in oligodendrocytes.

By using an in vitro model of antibody-mediated demyelination, we investigated the relationship between tumor necrosis factor-alpha (TNF-alpha) and heat shock protein (HSP) induction with respect to oligodendrocyte survival. Differentiated aggregate cultures of rat telencephalon were subjected to demyelination by exposure to antibodies against myelin oligodendrocyte glycoprotein (MOG) and complement. Cultures were analyzed 48 hr after exposure. Myelin basic protein (MBP) expression was greatly decreased, but no evidence was found for either necrosis or apoptosis. TNF-alpha was significantly up-regulated. It was localized predominantly in neurons and to a lesser extent in astrocytes and oligodendrocytes, and it was not detectable in microglial cells. Among the different HSPs examined, HSP32 and alphaB-crystallin were up-regulated; they may confer protection from oxidative stress and from apoptotic death, respectively. These results suggest that TNF-alpha, often regarded as a promoter of oligodendroglial death, could alternatively mediate a protective pathway through alphaB-crystallin up-regulation.

Organisation and role of actin microfilaments during cellular growth and morphogenesis in the moss Physcomitrella patens

ABSTRACT The network of actin cytoskeleton is composed of actin filaments (F-actin) that are made by polymerisation of actin monomers and actin binding proteins. It is required for growth and morphogenesis of eukaryotic cells. The labelling of F-actin with constitutively expressed GFP-Talin (Kost et al., 1998) reveals the organisation of cellular actin networks in plants. Due to the lack of information on actin cytoskeleton through gametophytic development of the model moss plant Physcornitrella patens, stable transgenic lines overexpressing GFP-Talin were generated to detect F-actin structures. It is shown that the 35S promoter driven expression is not suitable for F-actin labelling in all cells. When it is replaced by the inducible heat-shock promoter Gmhsp17.3 from soybean, one hour mild heat stress at 37°C followed by recovery at 25°C is enough to induce efficient and transient labelling in all tissues without altering cellular morphology. The optimal observations of F-actin structures at different stages of moss development can be done between 12-18 hours after the induction. By using confocal microscopy, we demonstrate that stellated actin arrays were densely accumulated at the growing tip in regenerating protoplasts, apical protonemal cells and rhizoids and connected with a fine dispersed F-actin mesh. Following three-dimensional growth, the cortical star-like structures are widespread in the meristematic cells of developing bud and young gametophores. On the contrary, undulating networks of actin cables are found at the final stage of cell differentiation. During redifferentiation of mature leaf cells into protonemal filaments the rather stagnant web of actin cables is replaced by diffuse actin meshwork. In eukaryotes, nucleation of the actin monomers prior to their polymerization is driven by the seven-subunit ARP2/3 complex and formins. We cloned the gene encoding the ARP3 subunit of P. patens and generated arp3 mutants of the moss through gene disruption. The knockout of ARP3 affects the elongation of chloronemal cells and blocks further differentiation of caulonemal cells and rhizoids, and the gametophores are slightly stunted compared to wild-type. The arp mutants were created in the heat-shock inducible GFP-Talin strains allowing us to visualise a disorganised actin network and a lack of star-like actin cytoskeleton arrays. We conclude that ARP2/3 dependent nucleation of actin filaments is critical for the growth of filamentous cells, which in turn influences moss colonization. In complementation assays, the overexpression of Physcomitrella and Arab idopsis ARP3 genes in the moss arp3 mutant results in full recovery of wild type phenotype. In contrast the ARP3 subunit of fission yeast is not able to complement the moss arp3 mutant of moss indicating that regulation of the ARP2/3 dependent actin nucleation diverged in different kingdoms. RESUME Le réseau d'actine est composé de filaments de F-actine et d'un ensemble de protéines s'y attachant (Actin binding proteins). Le réseau d'actine est nécessaire à la croissance et à la morphogenèse de toutes les cellules eucaryotes. Chez les plantes, le marquage ainsi que l'étude de l'organisation du réseau d'actine ont été réalisés en utilisant une fusion GFP-Talin (Kost et al., 1998) exprimée sous le control d'un promoteur constitutif. Afin d'étudier les structures F-actine dans les cellules de Physcomitrella Patens et pour combler le manque d'information sur le développement des gamétophores, des lignées transgéniques stables surexprimant GFP-Talin ont été crées. Nous avons démontré que l'utilisation du promoteur 35S est inadéquate pour le marquage complet et homogène des filaments d'actine dans toutes les cellules de P. patens. Par contre, l'utilisation du promoteur inductible Gmhsp17.3 nous a permis de réaliser un marquage transitoire et général dans tous les tissus de la mousse. Une heure de choc thermique à 37°C suivis d'un temps de récupération de 12-18h à 25°C sont les conditions optimales (sans dommages cellulaires) pour l'observation des structures F-actine à différentes étapes de développement de la mousse. En utilisant la microscopie confocale, nous avons observé l'existence de structures F-actine accumulées en forme d'étoiles. Ces structures, qui sont liées au réseau de microfilaments d'actine, ont été observées dans les protoplastes en régénération, les cellules des protonema apicales ainsi que dans les rhizoïdes. En suivant la croissance tridimensionnelle, ces structures en étoiles ont été observées dans les cellules meristématiques des bourgeons et des jeunes gamétophores. Par contre, dans les cellules différentiées ces structures laissent place à des réseaux de câbles épais. Nous avons également remarqué que durant la redifferentiation des cellules foliaires le réseau de câbles de F-actine est remplacé par un réseau de F-actine diffus. Dans les cellules eucaryotes, la nucléation des filaments d'actirie précédant leur polymérisation est contrôlé par sept sous unités du complexe ARP2/3 et par des formines. Nous avons isolé le gène codant pour la sous unité ARP3 de P. patens et nous avons crée des mutants arp3 par intégration ciblée (Knockout). L'élongation des cellules chloronema est clairement affectée dans les mutants arp3. La différentiation des caulonemata et des rhizoïdes est bloquée et les gametophores sont légèrement plus courts comparé au type sauvage. A fin d'étudier l'organisation des filaments d'actines dans les mutants arp3, nous avons aussi réalisé un arp3-knockout dans la lignée Hsp-GFP-Talin. La nouvelle lignée générée nous a permis de visualiser une désorganisation du réseau d'actine et une absence complète de structures de F-actine accumulée en forme d'étoiles. Les résultats obtenus nous amènent à conclure que la nucléation (ARP2/3 dépendante) des filaments d'actine est indispensable à la croissance des cellules filamenteuses. Par conséquent, les filaments d'actine semblent avoir un rôle dans la colonisation des milieux par les mousses. Nous avons également procédé à des essais de complémentation du mutant arp3. La surexpression des gènes ARP3 de Physcomitrella et d'Arabidopsis dans les cellules du mutant arp3 rétabli complètement le phénotype WT. Par contre, le gène ARP3 des levures n'est pas suffisant pour complémenter la même mutation dans les cellules de mousses. Ce résultat démontre que les mécanismes de régulation de la nucléation des filaments d'actine (ARP2/3 dépendante) sont différents entre les différents groupes d'eucaryotes.

Microtubule-associated protein 1B binds glyceraldehyde-3-phosphate dehydrogenase.

Microtubule-associated protein 1B, MAP1B, is a major cytoskeletal protein during brain development and one of the largest brain MAPs associated with microtubules and microfilaments. Here, we identified several proteins that bind to MAP1B via immunoprecipitation with a MAP1B-specific antibody, by one and two-dimensional gel electrophoresis and subsequent mass spectrometry identification of precipitated proteins. In addition to tubulin and actin, a variety of proteins were identified. Among these proteins were glyceraldehyde-3-phosphate dehydrogenase (GAPDH), heat shock protein 8, dihydropyrimidinase related proteins 2 and 3, protein-L-isoaspartate O-methyltransferase, beta-spectrin, and clathrin protein MKIAA0034, linking either directly or indirectly to MAP1B. In particular, GAPDH, a key glycolytic enzyme, was bound in large quantity to the heavy chain of MAP1B in adult brain tissue. In vitro binding studies confirmed a direct binding of GAPDH to MAP1B. In PC12 cells, GAPDH was found in cytoplasm and nuclei and partially co-localized with MAP1B. It disappeared from the cytoplasm under oxidative stress or after a disruption of cytoskeletal elements after colcemid or cytochalasin exposure. GAPDH may be essential in the local energy provision of cytoskeletal structures and MAP1B may help to keep this key enzyme close to the cytoskeleton.

Analysis of the Cytoprotective Role of α-Crystallins in Cell Survival and Implication of the αA-Crystallin C-Terminal Extension Domain in Preventing Bax-Induced Apoptosis.

α-Crystallins, initially described as the major structural proteins of the lens, belong to the small heat shock protein family. Apart from their function as chaperones, α-crystallins are involved in the regulation of intracellular apoptotic signals. αA- and αB-crystallins have been shown to interfere with the mitochondrial apoptotic pathway triggering Bax pro-apoptotic activity and downstream activation of effector caspases. Differential regulation of α-crystallins has been observed in several eye diseases such as age-related macular degeneration and stress-induced and inherited retinal degenerations. Although the function of α-crystallins in healthy and diseased retina remains poorly understood, their altered expression in pathological conditions argue in favor of a role in cellular defensive response. In the Rpe65(-/-) mouse model of Leber's congenital amaurosis, we previously observed decreased expression of αA- and αB-crystallins during disease progression, which was correlated with Bax pro-death activity and photoreceptor apoptosis. In the present study, we demonstrated that α-crystallins interacted with pro-apoptotic Bax and displayed cytoprotective action against Bax-triggered apoptosis, as assessed by TUNEL and caspase assays. We further observed in staurosporine-treated photoreceptor-like 661W cells stably overexpressing αA- or αB-crystallin that Bax-dependent apoptosis and caspase activation were inhibited. Finally, we reported that the C-terminal extension domain of αA-crystallin was sufficient to provide protection against Bax-triggered apoptosis. Altogether, these data suggest that α-crystallins interfere with Bax-induced apoptosis in several cell types, including the cone-derived 661W cells. They further suggest that αA-crystallin-derived peptides might be sufficient to promote cytoprotective action in response to apoptotic cell death.

Histone deacetylase inhibition as an alternative strategy against invasive aspergillosis.

Invasive aspergillosis (IA) is a life-threatening infection due to Aspergillus fumigatus and other Aspergillus spp. Drugs targeting the fungal cell membrane (triazoles, amphotericin B) or cell wall (echinocandins) are currently the sole therapeutic options against IA. Their limited efficacy and the emergence of resistance warrant the identification of new antifungal targets. Histone deacetylases (HDACs) are enzymes responsible of the deacetylation of lysine residues of core histones, thus controlling chromatin remodeling and transcriptional activation. HDACs also control the acetylation and activation status of multiple non-histone proteins, including the heat shock protein 90 (Hsp90), an essential molecular chaperone for fungal virulence and antifungal resistance. This review provides an overview of the different HDACs in Aspergillus spp. as well as their respective contribution to total HDAC activity, fungal growth, stress responses, and virulence. The potential of HDAC inhibitors, currently under development for cancer therapy, as novel alternative antifungal agents against IA is discussed.