THBS1 and THBS2 Enhance the In Vitro Proliferation, Adhesion, Migration and Invasion of Intrahepatic Cholangiocarcinoma Cells.

In intrahepatic cholangiocarcinoma (iCCA), thrombospondin 1 (THBS1) and 2 (THBS2) are soluble mediators released in the tumor microenvironment (TME) that contribute to the metastatic spreading of iCCA cells via a lymphatic network by the trans-differentiation of vascular endothelial cells to a lymphatic-like phenotype. To study the direct role of THBS1 and THBS2 on the iCCA cells, well-established epithelial (HuCCT-1) and mesenchymal (CCLP1) iCCA cell lines were subjected to recombinant human THBS1 and THBS2 (rhTHBS1, rhTHBS2) for cellular function assays. Cell growth, cell adhesion, migration, and invasion were all enhanced in both CCLP1 and HuCCT-1 cells by the treatment with either rhTHBS1 or rhTHBS2, although they showed some variability in their intensity of speeding up cellular processes. rhTHBS2 was more intense in inducing invasiveness and in committing the HuCCT-1 cells to a mesenchymal-like phenotype and was therefore a stronger enhancer of the malignant behavior of iCCA cells compared to rhTHBS1. Our data extend the role of THBS1 and THBS2, which are not only able to hinder the vascular network and promote tumor-associated lymphangiogenesis but also exacerbate the malignant behavior of the iCCA cells.

Proteomic characterization of extracellular vesicles released by third stage larvae of the zoonotic parasite Anisakis pegreffii (Nematoda: Anisakidae).

Introduction: Anisakis pegreffii is a sibling species within the A. simplex (s.l.) complex requiring marine homeothermic (mainly cetaceans) and heterothermic (crustaceans, fish, and cephalopods) organisms to complete its life cycle. It is also a zoonotic species, able to accidentally infect humans (anisakiasis). To investigate the molecular signals involved in this host-parasite interaction and pathogenesis, the proteomic composition of the extracellular vesicles (EVs) released by the third-stage larvae (L3) of A. pegreffii, was characterized. Methods: Genetically identified L3 of A. pegreffii were maintained for 24 h at 37°C and EVs were isolated by serial centrifugation and ultracentrifugation of culture media. Proteomic analysis was performed by Shotgun Analysis. Results and discussion: EVs showed spherical shaped structure (size 65-295 nm). Proteomic results were blasted against the A. pegreffii specific transcriptomic database, and 153 unique proteins were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis predicted several proteins belonging to distinct metabolic pathways. The similarity search employing selected parasitic nematodes database revealed that proteins associated with A. pegreffii EVs might be involved in parasite survival and adaptation, as well as in pathogenic processes. Further, a possible link between the A. pegreffii EVs proteins versus those of human and cetaceans' hosts, were predicted by using HPIDB database. The results, herein described, expand knowledge concerning the proteins possibly implied in the host-parasite interactions between this parasite and its natural and accidental hosts.

Rab11A Depletion in Microglia-Derived Extracellular Vesicle Proteome upon Beta-Amyloid Treatment.

Microglia, the macrophage-like glial cells, behave as sentinels against exogenous pathogens invading the neural tissue. Their commitment is not only confined to the defensive function, but they also perform balancing trophic activities such as neuronal postnatal development, remodeling and pruning of synapses. Likewise, microglia-derived extracellular vesicles (EVs) can play strategic roles in maintaining a healthy brain by modulating neuronal activity and by controlling neurite outgrowth as well as innate immune response. Nevertheless, strong evidence also points to their role in the development of neurodegenerative pathologies such as Alzheimer's disease (AD). Here, we explored EV protein content released by BV2 microglial cells in a resting state and after stimulation with beta-amyloid peptides (Aß), mimicking conditions occurring in AD. In the resting BV2 cells, we extended the list of proteins present in mouse microglia EV cargo with respect to those reported in the Vesiclepedia exosome database while, in amyloid-triggered microglia, we highlighted a pronounced drop in EV protein content. Focusing on Rab11A, a key factor in the recycling routes of amyloid species, we observed a dramatic decrease of this protein in Aß-treated microglia EV cargo with respect to the EVs from the untreated sample. This decrease might affect the delivery of Rab11A to neurons thus increasing the harmful amyloid burden in neuronal cells that eventually may lead to their death. We tentatively proposed that alterations observed in EVs derived from Aß-treated microglia may represent molecular features that, among others, shape the disease-associated microglial phenotype, a recently proposed subset of microglial population, present in neurodegenerative pathologies.

Hyperexpression of CDRs and HWP1 genes negatively impacts on Candida albicans virulence.

C. albicans is a commensal organism present in the human microbiome of more than 60% of the healthy population. Transition from commensalism to invasive candidiasis may occur after a local or a general failure of host's immune system. This transition to a more virulent phenotype may reside either on the capacity to form hyphae or on an acquired resistance to antifungal drugs. Indeed, overexpression of genes coding drug efflux pumps or adhesins, cell wall proteins facilitating the contact between the fungus and the host, usually marks the virulence profile of invasive Candida spp. In this paper, we compare virulence of two clinical isolates of C. albicans with that of laboratory-induced resistant strains by challenging G. mellonella larvae with these pathogens along with monitoring transcriptional profiles of drug efflux pumps genes CDR1, CDR2, MDR1 and the adhesin genes ALS1 and HWP1. Although both clinical isolates were found resistant to both fluconazole and micafungin they were found less virulent than laboratory-induced resistant strains. An unexpected behavior emerged for the former clinical isolate in which three genes, CDR1, CDR2 and HWP1, usually correlated with virulence, although hyperexpressed, conferred a less aggressive phenotype. On the contrary, in the other isolate, we observed a decreased expression of CDR1, CDR2 and HWP1as well as of MDR1 and ALS1 that may be consistent with the less aggressive performance observed in this strain. These altered gene expressions might directly influence Candida virulence or they might be an epiphenomenon of a vaster rearrangement occurred in these strains during the challenge with the host's environment. An in-deepth comprehension of this scenario could be crucial for developing interventions able to counteract C. albicans invasiveness and lethality.

Glucagon-Like Peptide-1: A Focus on Neurodegenerative Diseases.

Diabetes mellitus is one of the major risk factors for cognitive dysfunction. The pathogenesis of brain impairment caused by chronic hyperglycemia is complex and includes mitochondrial dysfunction, neuroinflammation, neurotransmitters' alteration, and vascular disease, which lead to cognitive impairment, neurodegeneration, loss of synaptic plasticity, brain aging, and dementia. Glucagon-like peptide-1 (GLP-1), a gut released hormone, is attracting attention as a possible link between metabolic and brain impairment. Several studies have shown the influence of GPL-1 on neuronal functions such as thermogenesis, blood pressure control, neurogenesis, neurodegeneration, retinal repair, and energy homeostasis. Moreover, modulation of GLP-1 activity can influence amyloid ß peptide aggregation in Alzheimer's disease (AD) and dopamine (DA) levels in Parkinson's disease (PD). GLP-1 receptor agonists (GLP-1RAs) showed beneficial actions on brain ischemia in animal models, such as the reduction of cerebral infarct area and the improvement of neurological deficit, acting mainly through inhibition of oxidative stress, inflammation, and apoptosis. They might also exert a beneficial effect on the cognitive impairment induced by diabetes or obesity improving learning and memory by modulating synaptic plasticity. Moreover, GLP-1RAs reduced hippocampal neurodegeneration. Besides this, there are growing evidences on neuroprotective effects of these agonists in animal models of neurodegenerative diseases, regardless of diabetes. In PD animal models, GPL-1RAs were able to protect motor activity and dopaminergic neurons whereas in AD models, they seemed to improve nearly all neuropathological features and cognitive functions. Although further clinical studies of GPL-1RAs in humans are needed, they seem to be a promising therapy for diabetes-associated cognitive decline.

Shmt2: A Stat3 Signaling New Player in Prostate Cancer Energy Metabolism.

Prostate cancer (PCa) is a multifactorial disease characterized by the aberrant activity of different regulatory pathways. STAT3 protein mediates some of these pathways and its activation is implicated in the modulation of several metabolic enzymes. A bioinformatic analysis indicated a STAT3 binding site in the upstream region of SHMT2 gene. We demonstrated that in LNCaP, PCa cells' SHMT2 expression is upregulated by the JAK2/STAT3 canonical pathway upon IL-6 stimulation. Activation of SHTM2 leads to a decrease in serine levels, pushing PKM2 towards the nuclear compartment where it can activate STAT3 in a non-canonical fashion that in turn promotes a transient shift toward anaerobic metabolism. These results were also confirmed on FFPE prostate tissue sections at different Gleason scores. STAT3/SHMT2/PKM2 loop in LNCaP cells can modulate a metabolic shift in response to inflammation at early stages of cancer progression, whereas a non-canonical STAT3 activation involving the STAT3/HIF-1α/PKM2 loop is responsible for the maintenance of Warburg effect distinctive of more aggressive PCa cells. Chronic inflammation might thus prime the transition of PCa cells towards more advanced stages, and SHMT2 could represent a missing factor to further understand the molecular mechanisms responsible for the transition of prostate cancer towards a more aggressive phenotype.

Poly(ADP-ribosylated) proteins in ß-amyloid peptide-stimulated microglial cells.

Amyloid-treated microglia prime and sustain neuroinflammatory processes in the central nervous system activating different signalling pathways inside the cells. Since a key role for PARP-1 has been demonstrated in inflammation and in neurodegeneration, we investigated PARylated proteins in resting and in ß-amyloid peptide treated BV2 microglial cells. A total of 1158 proteins were identified by mass spectrometry with 117 specifically modified in the amyloid-treated cells. Intervention of PARylation on the proteome of microglia showed to be widespread in different cellular districts and to affect various cellular pathways, highlighting the role of this dynamic post-translational modification in cellular regulation. Ubiquitination is one of the more enriched pathways, encompassing PARylated proteins like NEDD4, an E3 ubiquitine ligase and USP10, a de-ubiquitinase, both associated with intracellular responses induced by ß-amyloid peptide challenge. PARylation of NEDD4 may be involved in the recruiting of this protein to the plasma membrane where it regulates the endocytosis of AMPA receptors, whereas USP10 may be responsible for the increase of p53 levels in amyloid stimulated microglia. Unfolded protein response and Endoplasmic Reticulum Stress pathways, strictly correlated with the Ubiquitination process, also showed enrichment in PARylated proteins. PARylation may thus represent one of the molecular switches responsible for the transition of microglia towards the inflammatory microglia phenotype, a pivotal player in brain diseases including neurodegenerative processes. The establishment of trials with PARP inhibitors to test their efficacy in the containment of neurodegenerative diseases may be envisaged.

Structural Properties of Macrodontain I, a Cysteine Protease from Pseudananas macrodontes (Morr.) Harms (Bromeliaceae).

The primary structure of macrodontain I, a peptidase from Pseudananas macrodontes fruits, was determined using Edman's degradation. The enzyme is a non-glycosylated peptidase composed by 213 amino acids with a calculated molecular weight of 23,486.18 Da, pI value 6.99, and a molar extinction coefficient at 280 nm of 61,685 M-1 cm-1. The alignment of the sequence of macrodontain I with those cysteine peptidases from species belonging to the family Bromeliaceae showed the highest identity degree (87.74%) against fruit bromelain. A remarkable fact is that all these peptidase sequences show two Met contiguous residues (Met121 and 122) and the nonapeptide VPQSIDWRD located in the mature N-terminal region. Residues Cys26 and His159, which constitute the catalytic dyad in all cysteine peptidases, as well as active site residues Gln20 and Asn176, characteristic of Clan C1A, are conserved in macrodontain I. The 3-D model suggests that the enzyme belongs to the α + ß class of proteins, with two disulfide bridges (Cys23-Cys63 and Cys57-Cys96) in the α domain, while the ß domain is stabilized by another disulfide bridge (Cys153-Cys201). Further, we were able to establish that the cysteine peptidases from P. macrodontes are involved in the anti-inflammatory activity.

Plasma Membrane Protein Profiling in Beta-Amyloid-Treated Microglia Cell Line.

In the responsiveness of microglia to toxic stimuli, plasma membrane proteins play a key role. In this study we treated with a synthetic beta amyloid peptide murine microglial cells metabolically differently labelled with stable isotope amino acids (SILAC). The plasma membrane was selectively enriched by a multi-stage aqueous two-phase partition system. We were able to identify by 1D-LC-MS/MS analyses 1577 proteins, most of them are plasma membrane proteins according to the Gene Ontology annotation. An unchanged level of amyloid receptors in this data set suggests that microglia preserve their responsiveness capability to the environment even after 24-h challenge with amyloid peptides. On the other hand, 14 proteins were observed to change their plasma membrane abundance to a statistically significant extent. Among these, we proposed as reliable biomarkers of the inflammatory microglia phenotype in AD damaged tissues MAP/microtubule affinity-regulating kinase 3 (MARK3), Interferon-induced transmembrane protein 3 (IFITM3), Annexins A5 and A7 (ANXA5, ANXA7) and Neuropilin-1 (NRP1), all proteins known to be involved in the inflammation processes and in microtubule network assembly rate.

Poly(ADP-ribosylated) proteins in mononuclear cells from patients with type 2 diabetes identified by proteomic studies.

AIMS: In diabetes, hyperglycemia increases reactive oxygen species that induce DNA damage and poly(ADP-ribose)polymerase activation. The aim of this study is to characterize the proteomic profile and the role of poly(ADP-ribosylation) in patients with type 2 diabetes. METHODS: A proteomic platform based on 2DE and MALDI-ToF spectrometry was applied to peripheral blood mononuclear cells obtained from two different cohorts in which diabetic (n = 14) and normoglycemic patients (n = 11) were enrolled. RESULTS: Proteomic maps identified WD repeat protein, 78-kDa glucose-regulated protein precursor and myosin regulatory light chain 2, as unique proteins in diabetic patients; vimentin, elongation factor 2, annexin A1, glutathione S-transferase P, moesin and cofilin-1 as unique in the normoglycemic; and calreticulin, rho GDP-dissociation inhibitor 2, protein disulfide isomerase and tropomyosin alpha-4-chain as differentially expressed between the two cohorts. An enrichment in PARylation in diabetic patients was observed in particular, affecting GAPDH and α-Enolase leading to a decrease in their enzymatic activity. CONCLUSIONS: As the GAPDH and α-Enolase are involved in energy metabolism, protein synthesis and DNA repair, loss of their function or change in their activity can significantly contribute to the molecular mechanisms responsible for the development of type 2 diabetes. These data along with the proteomic profile associated with the disease may provide new insight into the pathophysiology of type 2 diabetes.

PAR1 activation affects the neurotrophic properties of Schwann cells.

Protease-activated receptor-1 (PAR1) is the prototypic member of a family of four G-protein-coupled receptors that signal in response to extracellular proteases. In the peripheral nervous system, the expression and/or the role of PARs are still poorly investigated. High PAR1 mRNA expression was found in the rat dorsal root ganglia and the signal intensity of PAR1 mRNA increased in response to sciatic nerve transection. In the sciatic nerve, functional PAR1 receptor was reported at the level of non-compacted Schwann cell myelin microvilli of the nodes of Ranvier. Schwann cells are the principal population of glial cells of the peripheral nervous system which myelinate axons playing an important role during axonal regeneration and remyelination. The present study was undertaken in order to determine if the activation of PAR1 affects the neurotrophic properties of Schwann cells. Our results suggest that the stimulation of PAR1 could potentiate the Schwann cell ability to favour nerve regeneration. In fact, the conditioned medium obtained from Schwann cell cultures challenged with a specific PAR1 activating peptide (PAR1 AP) displays increased neuroprotective and neurotrophic properties with respect to the culture medium from untreated Schwann cells. The proteomic analysis of secreted proteins in untreated and PAR1 AP-treated Schwann cells allowed the identification of factors differentially expressed in the two samples. Some of them (such as macrophage migration inhibitory factor, matrix metalloproteinase-2, decorin, syndecan 4, complement C1r subcomponent, angiogenic factor with G patch and FHA domains 1) appear to be transcriptionally regulated after PAR1 AP treatment as shown by RT-PCR.

Bioenergetic Impairment in Animal and Cellular Models of Alzheimer's Disease: PARP-1 Inhibition Rescues Metabolic Dysfunctions.

Amyloid-beta peptide accumulation in the brain is one of the main hallmarks of Alzheimer's disease. The amyloid aggregation process is associated with the generation of free radical species responsible for mitochondrial impairment and DNA damage that in turn activates poly(ADP-ribose)polymerase 1 (PARP-1). PARP-1 catalyzes the poly(ADP-ribosylation), a post-translational modification of proteins, cleaving the substrate NAD+ and transferring the ADP-ribose moieties to the enzyme itself or to an acceptor protein to form branched polymers of ADP-ribose. In this paper, we demonstrate that a mitochondrial dysfunction occurs in Alzheimer's transgenic mice TgCRND8, in SH-SY5Y treated with amyloid-beta and in 7PA2 cells. Moreover, PARP-1 activation contributes to the functional energetic decline affecting cytochrome oxidase IV protein levels, oxygen consumption rates, and membrane potential, resulting in cellular bioenergetic deficit. We also observed, for the first time, an increase of pyruvate kinase 2 expression, suggesting a modulation of the glycolytic pathway by PARP-1. PARP-1 inhibitors are able to restore both mitochondrial impairment and pyruvate kinase 2 expression. The overall data here presented indicate a pivotal role for this enzyme in the bioenergetic network of neuronal cells and open new perspectives for investigating molecular mechanisms underlying energy charge decline in Alzheimer's disease. In this scenario, PARP-1 inhibitors might represent a novel therapeutic intervention to rescue cellular energetic metabolism.

Differential 3-bromopyruvate inhibition of cytosolic and mitochondrial human serine hydroxymethyltransferase isoforms, key enzymes in cancer metabolic reprogramming.

The cytosolic and mitochondrial isoforms of serine hydroxymethyltransferase (SHMT1 and SHMT2, respectively) are well-recognized targets of cancer research, since their activity is critical for purine and pyrimidine biosynthesis and because of their prominent role in the metabolic reprogramming of cancer cells. Here we show that 3-bromopyruvate (3BP), a potent novel anti-tumour agent believed to function primarily by blocking energy metabolism, differentially inactivates human SHMT1 and SHMT2. SHMT1 is completely inhibited by 3BP, whereas SHMT2 retains a significant fraction of activity. Site directed mutagenesis experiments on SHMT1 demonstrate that selective inhibition relies on the presence of a cysteine residue at the active site of SHMT1 (Cys204) that is absent in SHMT2. Our results show that 3BP binds to SHMT1 active site, forming an enzyme-3BP complex, before reacting with Cys204. The physiological substrate l-serine is still able to bind at the active site of the inhibited enzyme, although catalysis does not occur. Modelling studies suggest that alkylation of Cys204 prevents a productive binding of l-serine, hampering interaction between substrate and Arg402. Conversely, the partial inactivation of SHMT2 takes place without the formation of a 3BP-enzyme complex. The introduction of a cysteine residue in the active site of SHMT2 by site directed mutagenesis (A206C mutation), at a location corresponding to that of Cys204 in SHMT1, yields an enzyme that forms a 3BP-enzyme complex and is completely inactivated. This work sets the basis for the development of selective SHMT1 inhibitors that target Cys204, starting from the structure and reactivity of 3BP.

Extracellular Matrix Molecular Remodeling in Human Liver Fibrosis Evolution.

Chronic liver damage leads to pathological accumulation of ECM proteins (liver fibrosis). Comprehensive characterization of the human ECM molecular composition is essential for gaining insights into the mechanisms of liver disease. To date, studies of ECM remodeling in human liver diseases have been hampered by the unavailability of purified ECM. Here, we developed a decellularization method to purify ECM scaffolds from human liver tissues. Histological and electron microscopy analyses demonstrated that the ECM scaffolds, devoid of plasma and cellular components, preserved the three-dimensional ECM structure and zonal distribution of ECM components. This method has been then applied on 57 liver biopsies of HCV-infected patients at different stages of liver fibrosis according to METAVIR classification. Label-free nLC-MS/MS proteomics and computation biology were performed to analyze the ECM molecular composition in liver fibrosis progression, thus unveiling protein expression signatures specific for the HCV-related liver fibrotic stages. In particular, the ECM molecular composition of liver fibrosis was found to involve dynamic changes in matrix stiffness, flexibility and density related to the dysregulation of predominant collagen, elastic fibers and minor components with both structural and signaling properties. This study contributes to the understanding of the molecular bases underlying ECM remodeling in liver fibrosis and suggests new molecular targets for fibrolytic strategies.

Reversible redox modifications in the microglial proteome challenged by beta amyloid.

Microglia are resident macrophages in the central nervous system, whose participation against exogenous injuries and infections is mainly marked by an immediate release of inflammatory cytokines along with a toxic efflux of superoxide radicals. Indeed, many lines of evidence indicate that persistent activation of these cells turns their neuroprotective phenotype into a neurotoxic one, which contributes to destroy neuronal activity and induces neuronal loss in several neurodegeneration processes, such as Alzheimer's disease. In this study we attempted to fill-in the gap in our knowledge about redox regulation of amyloid activated microglia. With this aim, we carried out a robust and comprehensive characterization of the reversibly redox modified proteome both at the level of resting and amyloid-activated BV2 cells, an immortalised cell line of murine microglia. The approach we used combined the selective enrichment of reversible redox modified proteins through a biotin bait with nanoscale liquid chromatography tandem mass spectrometry of their proteolytic peptides. By this reliable approach, we identified 60 proteins changing the redox status of their selective cysteine residues upon treatment with the amyloidogenic Aß25-35 peptide. These results assessed that in microglia stimulated by amyloids, redox modifications of the proteome specifically target proteins involved in crucial cell processes, i.e. those involved in the protein synthesis. In particular, for peroxiredoxin-6 (Prdx6) and Ras-related C3 botulinum toxin substrate 1 (Rac1) we suggest mechanisms through which reversible redox modifications could affect the peculiar role of microglia in amyloidogenic injury, which at the same time reinforce the oxidative burst and resist toward it. Moreover, the redox modulation we observed on chloride intracellular channel protein 1 (CLIC1) strengthens the structural and functional relationship between the oxidative stress and the metamorphic transition of this protein from a soluble form to an integral membrane form. The redox signatures we determined might also provide neurologists with more specific and reliable biomarkers to distinguish the diverse microglia status in neurodegeneration and then to drive targeted drug design.

Acetylation and phosphorylation of STAT3 are involved in the responsiveness of microglia to beta amyloid.

Microglia are macrophages within the central nervous system playing a central role in neurodegenerative disorders. Although the initial engagement of microglia seems to be neuroprotective, many lines of evidence indicate that its persistent activation contributes to dismantle neuronal activity and to induce neuronal loss. The molecular pathways that lead from amyloid interaction with membrane receptors to the microglial activation have been extensively investigated, although a definitive picture is not yet at hand. In this work, primary and immortalized microglial cells were treated with a synthetic form of Aß peptides, and relative abundance of acetylated and phosphorylated STAT3 were assayed. Results highlight, for the first time, three distinctive sequential events: i) an earlier event marked by the increase in the level of STAT3 acetylated species, followed by ii) a later increase in the level of STAT3 phosphorylated form, and finally iii) an involvement of phosphorylated STAT3 in the increase in expression of the 14-3-3 epsilon, a protein frequently associated with neurodegenerative diseases and known to be a marker of Aß-activated microglia. These data outline a complex, time-dependent modification of STAT3 signalling triggered by amyloid in the microglial compartments, that once confirmed by in vivo experiments will broaden the knowledge of the molecular basis of amyloid neurotoxicity.

Mutant PrPCJD prevails over wild-type PrPCJD in the brain of V210I and R208H genetic Creutzfeldt-Jakob disease patients.

Creutzfeldt-Jakob disease (CJD) is a neurodegenerative disorder characterized by the deposition of the pathological conformer (PrP(CJD)) of the host encoded cellular prion protein (PrP(C)). In genetic CJD associated with V210I or R208H PrP substitutions, the pathogenic role of mutant residues is still poorly understood. To understand how V210I or R208H PrP mutations facilitate the development of the disease, we determined by mass spectrometry the quantitative ratio of mutant/wild-type PrP(CJD) allotypes in brains from affected subjects. We found that the mutant PrP(CJD) allotypes moderately exceeds of 2- or 3-fold the amount of the wild-type counterpart suggesting that these mutations mainly exert their pathogenic effect on the onset of the pathogenic cascade. Different mechanisms can be hypothesized to explain the pathogenic role of mutant residues: V210I and R208H substitutions can increase the concentration of PrP(C) and the probability to form insoluble aggregates, or they may facilitate the formation of pathological intermediates, or, alternatively, they may increase the affinity for ligands that are involved in the initial phases of PrP(CJD) formation and aggregation. Whatever the mechanism, the enrichment found for the mutated PrP(CJD) species indicates that these altered structures are more prone, with respect to the non-mutated ones, to be captured in the polymerization process either at the onset or during the development of the disease.

Glutathione metabolism in Candida albicans resistant strains to fluconazole and micafungin.

Currently available therapies for candidiasis are based on antifungal drugs belonging to azole and echinocandin families that interfere with different aspects of fungal metabolism. These drugs, beyond their specific effects, elicit also a cellular stress including an unbalance of redox state that is counteracted not only utilizing antioxidant species but also increasing the outcome export by transporters to detoxify the internal environment. These cellular actions are both based on the cytosolic concentration of reduced glutathione (GSH). In this paper we investigated the effects of two antifungal drugs fluconazole and micafungin on the redox state of the cell in C. albicans to understand if the resistance to these drugs is accompanied by variation of glutathione metabolism. Analyses of resistant strains showed a marked difference in glutathione contents in strains resistant to fluconazole (CO23RFLC) or micafungin (CO23RFK). In CO23RFLC, the total amount of glutathione was more than doubled with respect to CO23RFK thanks to the increased activity of γ-glutamilcysteine synthetase, the key enzyme involved in GSH synthesis. We demonstrated that the GSH increase in CO23RFLC conferred to this strain a clear advantage in counteracting oxidative toxic agents while assignment of other roles, such as a more efficient elimination of the drug from the cell, should be considered more speculative. As far as MCFG resistance is concerned, from our data a role of glutathione metabolism in supporting this condition is not evident. Overall our data indicate that glutathione metabolism is differently affected in the two resistant strains and that glutathione system may play an important role in the global organization of C.albicans cells for resistance to fluconazole. Such scenario may pave the way to hypothesize the use of oxidant drugs or inhibitors able to deplete reduced glutathione level as a novel approach, for counteracting the resistance to this specific antifungal drug.

PARP-1 modulates amyloid beta peptide-induced neuronal damage.

Amyloid beta peptide (Aß) causes neurodegeneration by several mechanisms including oxidative stress, which is known to induce DNA damage with the consequent activation of poly (ADP-ribose) polymerase (PARP-1). To elucidate the role of PARP-1 in the neurodegenerative process, SH-SY5Y neuroblastoma cells were treated with Aß25-35 fragment in the presence or absence of MC2050, a new PARP-1 inhibitor. Aß25-35 induces an enhancement of PARP activity which is prevented by cell pre-treatment with MC2050. These data were confirmed by measuring PARP-1 activity in CHO cells transfected with amylod precursor protein and in vivo in brains specimens of TgCRND8 transgenic mice overproducing the amyloid peptide. Following Aß25-35 exposure a significant increase in intracellular ROS was observed. These data were supported by the finding that Aß25-35 induces DNA damage which in turn activates PARP-1. Challenge with Aß25-35 is also able to activate NF-kB via PARP-1, as demonstrated by NF-kB impairment upon MC2050 treatment. Moreover, Aß25-35 via PARP-1 induces a significant increase in the p53 protein level and a parallel decrease in the anti-apoptotic Bcl-2 protein. These overall data support the hypothesis of PARP-1 involvment in cellular responses induced by Aß and hence a possible rationale for the implication of PARP-1 in neurodegeneration is discussed.

The cell wall protein Rhd3/Pga29 is over-expressed in Candida albicans upon micafungin treatment.

Candida albicans cell wall constitutes a sensitive boundary that undergoes molecular changes upon environmental injuries. Antimycotics exert an intense action on cell wall eliciting both qualitative and quantitative changes of resident proteins. The emergence of drug resistance is marked by a modulation of cell wall proteomic profile. In this study, we monitored, at the proteome level through a two-dimensional gel electrophoresis-based approach, differences of cell wall proteins in sensitive and resistant strains of C. albicans, and variations occurring upon treatment of these strains with antifungal drugs. We identified Rhd3/Pga29, a glycophosphatidylinositol (GPI)-anchored protein, as the main over-expressed protein in micafungin resistant strain with respect to the sensitive control cells. A further increase of Rhd3/Pga29 took place when these resistant strains were treated with sub-lethal dose of micafungin. These results were also confirmed in other two clinical isolates resistant to caspofungin. Results were validated by Western blot analyses and RT-PCR and immunoelectron microscopy images confirmed the increase of the Rhd3/Pga29 on the cell wall as well as in the cytosolic compartment of the micafungin-treated resistant cells. Rhd3/Pga29 over-expression upon echinocandin treatment could represent a strategy of C. albicans to counteract the toxic action of this drug. A role of this protein has also been claimed in the virulence of the fungus, suggesting an involvement of Rhd3/Pga29 in the relationship between C. albicans and the host.