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Inhaled siRNA therapy has a unique potential for treatment of severe lung diseases, such as cystic fibrosis (CF). Nevertheless, a drug delivery system tackling lung barriers is mandatory to enhance gene silencing efficacy in the airway epithelium. We recently demonstrated that lipid-polymer hybrid nanoparticles (hNPs), comprising a poly(lactic-co-glycolic) acid (PLGA) core and a lipid shell of dipalmitoyl phosphatidylcholine (DPPC), may assist the transport of the nucleic acid cargo through mucus-covered human airway epithelium. To study in depth the potential of hNPs for siRNA delivery to the lungs and to investigate the hypothesized benefit of PEGylation, here, an siRNA pool against the nuclear factor-kappa B (siNF kappa B) was encapsulated inside hNPs, endowed with a non-PEGylated (DPPC) or a PEGylated (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) or DSPE-PEG) lipid shell. Resulting hNPs were tested for their stability profiles and transport properties in artificial CF mucus, mucus collected from CF cells, and sputum samples from a heterogeneous and representative set of CF patients. Initial information on hNP properties governing their interaction with airway mucus was acquired by small-angle X-ray scattering (SAXS) studies in artificial and cellular CF mucus. The diffusion profiles of hNPs through CF sputa suggested a crucial role of lung colonization of the corresponding donor patient, affecting the mucin type and content of the sample. Noteworthy, PEGylation did not boost mucus penetration in complex and sticky samples, such as CF sputa from patients with polymicrobial colonization. In parallel, in vitro cell uptake studies performed on mucus-lined Calu-3 cells grown at the air-liquid interface (ALI) confirmed the improved ability of non-PEGylated hNPs to overcome mucus and cellular lung barriers. Furthermore, effective in vitro NF kappa B gene silencing was achieved in LPS-stimulated 16HBE14o-cells. Overall, the results highlight the potential of non-PEGylated hNPs as carriers for pulmonary delivery of siRNA for local treatment of CF lung disease. Furthermore, this study provides a detailed understanding of how distinct models may provide different information on nanoparticle interaction with the mucus barrier.

β-glucocerebrosidase is a lysosomal hydrolase involved in the catabolism of the sphingolipid glucosylceramide. Biallelic loss of function mutations in this enzyme are responsible for the onset of Gaucher disease, while monoallelic β-glucocerebrosidase mutations represent the first genetic risk factor for Parkinson’s disease. Despite this evidence, the molecular mechanism linking the impairment in β-glucocerebrosidase activity with the onset of neurodegeneration in still unknown. In this frame, we developed two in vitro neuronal models of β-glucocerebrosidase deficiency, represented by mouse cerebellar granule neurons and human-induced pluripotent stem cells-derived dopaminergic neurons treated with the specific β-glucocerebrosidase inhibitor conduritol B epoxide. Neurons deficient for β-glucocerebrosidase activity showed a lysosomal accumulation of glucosylceramide and the onset of neuronal damage. Moreover, we found that neurons react to the lysosomal impairment by the induction of their biogenesis and exocytosis. This latter event was responsible for glucosylceramide accumulation also at the plasma membrane level, with an alteration in lipid and protein composition of specific signaling microdomains. Collectively, our data suggest that β-glucocerebrosidase loss of function impairs the lysosomal compartment, establishing a lysosome–plasma membrane axis responsible for modifications in the plasma membrane architecture and possible alterations of intracellular signaling pathways, leading to neuronal damage.

Niemann-Pick type A disease (NPA) is a rare lysosomal storage disorder caused by mutations in the gene coding for the lysosomal enzyme acid sphingomyelinase (ASM). ASM deficiency leads to the consequent accumulation of its uncatabolized substrate, the sphingolipid sphingomyelin (SM), causing severe progressive brain disease. To study the effect of the aberrant lysosomal accumulation of SM on cell homeostasis, we loaded skin fibroblasts derived from a NPA patient with exogenous SM to mimic the levels of accumulation characteristic of the pathological neurons. In SM-loaded NPA fibroblasts, we found the blockage of the autophagy flux and the impairment of the mitochondrial compartment paralleled by the altered transcription of several genes, mainly belonging to the electron transport chain machinery and to the cholesterol biosynthesis pathway. In addition, SM loading induces the nuclear translocation of the transcription factor EB that promotes the lysosomal biogenesis and exocytosis. Interestingly, we obtained similar biochemical findings in the brain of the NPA mouse model lacking ASM (ASMKO mouse) at the neurodegenerative stage. Our work provides a new in vitro model to study NPA etiopathology and suggests the existence of a pathogenic lysosome-plasma membrane axis that with an impairment in the mitochondrial activity is responsible for the cell death.

Malaria during pregnancy is a major global health problem caused by infection with Plasmodium falciparum parasites. Severe effects arise from the accumulation of infected erythrocytes in the placenta. Here, erythrocytes infected by late blood-stage parasites adhere to placental chondroitin sulphate A (CS) via VAR2CSA-type P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion proteins. Immunity to placental malaria is acquired through exposure and mediated through antibodies to VAR2CSA. Through evolution, the VAR2CSA proteins have diversified in sequence to escape immune recognition but retained their overall macromolecular structure to maintain CS binding affinity. This structural conservation may also have allowed development of broadly reactive antibodies to VAR2CSA in immune women. Here we show the negative stain and cryo-EM structure of the only known broadly reactive human monoclonal antibody, PAM1.4, in complex with VAR2CSA. The data shows how PAM1.4’s broad VAR2CSA reactivity is achieved through interactions with multiple conserved residues of different sub-domains forming conformational epitope distant from the CS binding site on the VAR2CSA core structure. Thus, while PAM1.4 may represent a class of antibodies mediating placental malaria immunity by inducing phagocytosis or NK cell-mediated cytotoxicity, it is likely that broadly CS binding-inhibitory antibodies target other epitopes at the CS binding site. Insights on both types of broadly reactive monoclonal antibodies may aid the development of a vaccine against placental malaria.

The delivery of a dexamethasone formulation directly into the lung appears as an appropriate strategy to strengthen the systemic administration, reducing the dosage in the treatment of lung severe inflammations. For this purpose, a hyaluronic acid-dexamethasone formulation was developed, affording an inhalable reconstituted nanosuspension suitable to be aerosolized. The physico-chemical and biopharmaceutical properties of the formulation were tested: size, stability, loading of the spray-dried dry powder, reconstitution capability upon redispersion in aqueous media. Detailed structural insights on nanoparticles after reconstitution were obtained by light and X-ray scattering techniques. (1) The size of the nanoparticles, around 200 nm, is in the proper range for a possible engulfment by macrophages. (2) Their structure is of the core-shell type, hosting dexamethasone nanocrystals inside and carrying hyaluronic acid chains on the surface. This specific structure allows for nanosuspension stability and provides nanoparticles with muco-inert properties. (3) The nanosuspension can be efficiently aerosolized, allowing for a high drug fraction potentially reaching the deep lung. Thus, this formulation represents a promising tool for the lung administration via nebulization directly in the pipe of ventilators, to be used as such or as adjunct therapy for severe lung inflammation.

Sphingosine-1-phosphate (S1P) is a crucial mediator involved in the progression of different cancers, including glioblastoma multiforme (GBM), the most frequent and deadly human brain tumor, characterized by extensive invasiveness and rapid cell growth. Most of GBMs overexpress the epidermal growth factor receptor (EGFR), and we investigated the possible link between S1P and EGFR signaling pathways, focusing on its role in GBM survival, using the U87MG human cell line overexpressing EGFR (EGFR+). We previously demonstrated that EGFR+ cells have higher levels of extracellular S1P and increased sphingosine kinase-1 (SK1) activity than empty vector expressing cells. Notably, we demonstrated that EGFR+ cells are resistant to temozolomide (TMZ), the standard chemotherapeutic drug in GBM treatment, and the inhibition of SK1 or S1P receptors made EGFR+ cells sensitive to TMZ, moreover, exogenous S1P reverted this effect, thus involving extracellular S1P as a survival signal in TMZ resistance in GBM cells. In addition, both PI3K/AKT and MAPK inhibitors markedly reduced cell survival, suggesting that the enhanced resistance to TMZ of EGFR+ cells is dependent on the increased S1P secretion, downstream of the EGFR-ERK-SK1-S1P pathway. Altogether, our study provides evidence of a functional link between S1P and EGFR signaling pathways enhancing the survival properties of GBM cells.

The highly conserved Plasmodium falciparum cysteine-rich protective antigen (PfCyRPA) is a key target for next-generation vaccines against blood-stage malaria. PfCyRPA constitute the core of a ternary complex, including the reticulocyte binding-like homologous protein 5 (PfRh5) and the Rh5-interacting protein (PfRipr), and is fundamental for merozoite invasion of erythrocytes. In this study, we show that monoclonal antibodies (mAbs) specific to PfCyRPA neutralize the in vitro growth of Ghanaian field isolates as well as numerous laboratory-adapted parasite lines. We identified subsets of mAbs with neutralizing activity that bind to distinct sites on PfCyRPA and that in combination potentiate the neutralizing effect. As antibody responses against multiple merozoite invasion proteins are thought to improve the efficacy of blood-stage vaccines, we also demonstrated that combinations of PfCyRPA- and PfRh5 specific mAbs act synergistically to neutralize parasite growth. Yet, we identified prominent strain-dependent neutralization potencies, which our results suggest is independent of PfCyRPA expression level and polymorphism, demonstrating the importance of addressing functional converseness when evaluating blood-stage vaccine candidates. Finally, our results suggest that blood-stage vaccine efficacy can be improved by directing the antibody response towards defined protective epitopes on multiple parasite antigens.

Zika virus (ZIKV), a mosquito-borne flavivirus, came into the spotlight in 2016 when it was found to be associated with an increased rate of microcephalic newborns in Brazil. The virus has further been recognized to cause neurologic complications in children and adults in the form of myelitis, encephalitis, acute disseminated encephalomyelitis (ADEM) and Guillain Barre Syndrome in a fraction of infected individuals. With the ultimate goal of identifying correlates of protection to guide the design of an effective vaccine, the study of the immune response to ZIKV infection has become the focus of research worldwide. Both innate and adaptive immune responses seem to be essential for controlling the infection. Induction of sufficient levels of neutralizing antibodies has been strongly correlated with protection against reinfection in various models, while the role of CD8 T cells as antiviral effectors in the CNS has been controversial. In an attempt to improve our understanding regarding the role of ZIKV-induced CD8 T cells in protective immunity inside the CNS, we have expanded on previous studies in intracranially infected mice. In a recent study, we have demonstrated that, peripheral ZIKV infection in adult C57BL/6 mice induces a robust CD8 T cell response that peaks within a week. In the present study, we used B cell deficient as well as wild-type mice to show that there is a race between CXCR3-dependent recruitment of the effector CD8 T cells and local ZIKV replication, and that CD8 T cells are capable of local viral control if they arrive in the brain early after viral invasion, in appropriate numbers and differentiation state. Our data highlight the benefits of considering this subset when designing vaccines against Zika virus.

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein is expressed at the apical plasma membrane (PM) of different epithelial cells. The most common mutation responsible for the onset of cystic fibrosis (CF), F508del, inhibits the biosynthesis and transport of the protein at PM, and also presents gating and stability defects of the membrane anion channel upon its rescue by the use of correctors and potentiators. This prompted a multiple drug strategy for F508delCFTR aimed simultaneously at its rescue, functional potentiation and PM stabilization. Since ganglioside GM1 is involved in the functional stabilization of transmembrane proteins, we investigated its role as an adjuvant to increase the effectiveness of CFTR modulators. According to our results, we found that GM1 resides in the same PM microenvironment as CFTR. In CF cells, the expression of the mutated channel is accompanied by a decrease in the PM GM1 content. Interestingly, by the exogenous administration of GM1, it becomes a component of the PM, reducing the destabilizing effect of the potentiator VX-770 on rescued CFTR protein expression/function and improving its stabilization. This evidence could represent a starting point for developing innovative therapeutic strategies based on the co-administration of GM1, correctors and potentiators, with the aim of improving F508del CFTR function.

Human primary bronchial epithelial cells differentiated in vitro represent a valuable tool to study lung diseases such as cystic fibrosis (CF), an inherited disorder caused by mutations in the gene coding for the Cystic Fibrosis Transmembrane Conductance Regulator. In CF, sphingolipids, a ubiquitous class of bioactive lipids mainly associated with the outer layer of the plasma membrane, seem to play a crucial role in the establishment of the severe lung complications. Nevertheless, no information on the involvement of sphingolipids and their metabolism in the differentiation of primary bronchial epithelial cells are available so far. Here we show that ceramide and globotriaosylceramide increased during cell differentiation, whereas glucosylceramide and gangliosides content decreased. In addition, we found that apical plasma membrane of differentiated bronchial cells is characterized by a higher content of sphingolipids in comparison to the other cell membranes and that activity of sphingolipids catabolic enzymes associated with this membrane results altered with respect to the total cell activities. In particular, the apical membrane of CF cells was characterized by high levels of ceramide and glucosylceramide, known to have proinflammatory activity. On this basis, our data further support the role of sphingolipids in the onset of CF lung pathology. Electronic supplementary material The online version of this article (10.1007/s10719-020-09935-x) contains supplementary material, which is available to authorized users.

We show that glioblastoma multiform (GBM) cells overexpressing the constitutively active form of the epidermal growth factor receptor [epidermal growth factor receptor variant III (EGFRvIII) and U87MG human GBM cell line overexpressing EGFRvIII (EGFR+) cells] possess greater invasive properties and have higher levels of extracellular sphingosine-1-phosphate (S1P) and increased sphingosine kinase-1 (SK1) activity than the empty vector-expressing cells. Notably, the inhibition of SK1 or S1P receptors decreases the invasiveness of EGFR+ cells. Moreover, EGFR and MEK1 inhibitors reduce both SK1 activation and cell invasion, suggesting that the enhanced invasiveness observed in the EGFR+ cells depends on the increased S1P secretion, downstream of the EGFRvIII-ERK-SK1-S1P pathway. Altogether, the results of the present study indicate that, in GBM cells, EGFRvIII is connected with the S1P signaling pathway to enhance cell invasiveness and tumor progression.

// Jinfei Xu 1, * , Salvatore Cortellino 1, * , Rossella Tricarico 1 , Wen-Chi Chang 2 , Gabrielle Scher 1 , Karthik Devarajan 3 , Michael Slifker 3 , Robert Moore 1 , Maria Rosaria Bassi 1 , Elena Caretti 1 , Margie Clapper 2 , Harry Cooper 4 and Alfonso Bellacosa 1 1 Cancer Epigenetics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA 2 Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA 3 Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA 4 Department of Pathology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA * These authors have contributed equally to this work Correspondence to: Alfonso Bellacosa, email: Alfonso.Bellacosa@fccc.edu Keywords: TDG, APC, colorectal cancer, intestinal cancer Received: July 17, 2017 Accepted: August 21, 2017 Published: September 23, 2017 ABSTRACT Thymine DNA Glycosylase (TDG) is a base excision repair enzyme that acts as a thymine and uracil DNA N-glycosylase on G:T and G:U mismatches, thus protecting CpG sites in the genome from mutagenesis by deamination. In addition, TDG has an epigenomic function by removing the novel cytosine derivatives 5-formylcytosine and 5-carboxylcytosine (5caC) generated by Ten-Eleven Translocation (TET) enzymes during active DNA demethylation. We and others previously reported that TDG is essential for mammalian development. However, its involvement in tumor formation is unknown. To study the role of TDG in tumorigenesis, we analyzed the effects of its inactivation in a well-characterized model of tumor predisposition, the Apc Min mouse strain. Mice bearing a conditional Tdg flox allele were crossed with Fabpl ::Cre transgenic mice, in the context of the Apc Min mutation, in order to inactivate Tdg in the small intestinal and colonic epithelium. We observed an approximately 2-fold increase in the number of small intestinal adenomas in the test Tdg -mutant Apc Min mice in comparison to control genotypes (p=0.0001). This increase occurred in female mice, and is similar to the known increase in intestinal adenoma formation due to oophorectomy. In the human colorectal cancer (CRC) TCGA database, the subset of patients with TDG and APC expression in the lowest quartile exhibits an excess of female cases. We conclude that TDG inactivation plays a role in intestinal tumorigenesis initiated by mutation/underexpression of APC . Our results also indicate that TDG may be involved in sex-specific protection from CRC.

Human and mouse chronic lymphocytic leukemia (CLL) develops from CD5+ B cells that in mice and macaques are known to define the distinct B1a B-cell lineage. B1a cells are characterized by lack of germinal center (GC) development, and the B1a cell population is increased in mice with reduced GC formation. As a major mediator of follicular B-cell migration, the G protein-coupled receptor Epstein-Barr virus-induced gene 2 (EBI2 or GPR183) directs B-cell migration in the lymphoid follicles in response to its endogenous ligands, oxysterols. Thus, upregulation of EBI2 drives the B cells toward the extrafollicular area, whereas downregulation is essential for GC formation. We therefore speculated whether increased expression of EBI2 would lead to an expanded B1 cell subset and, ultimately, progression to CLL. Here, we demonstrate that B-cell-targeted expression of human EBI2 (hEBI2) in mice reduces GC-dependent immune responses, reduces total immunoglobulin M (IgM) and IgG levels, and leads to increased proliferation and upregulation of cellular oncogenes. Furthermore, hEBI2 overexpression leads to an abnormally expanded CD5+ B1a B-cell subset (present as early as 4 days after birth), late-onset lymphoid cancer development, and premature death. These findings are highly similar to those observed in CLL patients and identify EBI2 as a promoter of B-cell malignancies.

In the frame of a research program aimed to explore the relationship between chirality of iminosugars and their therapeutic potential, herein we report the synthesis of N-akyl l -deoxyiminosugars and the evaluation of the anti-inflammatory properties of selected candidates for the treatment of Pseudomonas aeruginosa infections in Cystic Fibrosis (CF) lung disease. Target glycomimetics were prepared by the shortest and most convenient approach reported to date, relying on the use of the well-known PS-TPP/I2 reagent system to prepare reactive alkoxyalkyl iodides, acting as key intermediates. Iminosugars ent-1-3 demonstrated to efficiently reduce the inflammatory response induced by P. aeruginosa in CuFi cells, either alone or in synergistic combination with their d -enantiomers, by selectively inhibiting NLGase. Surprisingly, the evaluation in murine models of lung disease showed that the amount of ent -1 required to reduce the recruitment of neutrophils was 40-fold lower than that of the corresponding d -enantiomer. The remarkably low dosage of the l -iminosugar, combined with its inability to act as inhibitor for most glycosidases, is expected to limit the onset of undesired effects, which are typically associated with the administration of its d -counterpart. Biological results herein obtained place ent -1 and congeners among the earliest examples of l -iminosugars acting as anti-inflammatory agents for therapeutic applications in Cystic Fibrosis.

Developing a vaccine againstPlasmodium falciparummalaria has been challenging, primarily due to high levels of antigen polymorphism and a complex parasite lifecycle. Immunization with theP.falciparummerozoite antigens PfMSRP5, PfSERA9, PfRAMA, PfCyRPA and PfRH5 has been shown to give rise to growth inhibitory and synergistic antisera. Therefore, these five merozoite proteins are considered to be promising candidates for a second-generation multivalent malaria vaccine. Nevertheless, little is known about IgG and IgM responses to these antigens in populations that are naturally exposed toP.falciparum. In this study, serum samples from clinically immune adults and malaria exposed children from Ghana were studied to compare levels of IgG and IgM specific for PfMSRP5, PfSERA9, PfRAMA, PfCyRPA and PfRH5. All five antigens were found to be specifically recognized by both IgM and IgG in serum from clinically immune adults and from children with malaria. Longitudinal analysis of the latter group showed an early, transient IgM response that was followed by IgG, which peaked 14 days after the initial diagnosis. IgG levels and parasitemia did not correlate, whereas parasitemia was weakly positively correlated with IgM levels. These findings show that IgG and IgM specific for merozoite antigens PfMSRP5, PfSERA9, PfRAMA, PfCyRPA and PfRH5 are high in children duringP.falciparummalaria, but that the IgM induction and decline occurs earlier in infection than that of IgG.

Flaviviruses constitute an increasing source of public health concern, with growing numbers of pathogens causing disease and geographic spread to temperate climates. Despite a large body of evidence supporting mutagenesis as a conceivable antiviral strategy, there are currently no data on the sensitivity to increased mutagenesis for Zika virus (ZIKV) and Usutu virus (USUV), two emerging flaviviral threats. In this study, we demonstrate that both viruses are sensitive to three ribonucleosides, favipiravir, ribavirin, and 5-fluorouracil, that have shown mutagenic activity against other RNA viruses while remaining unaffected by a mutagenic deoxyribonucleoside. Serial cell culture passages of ZIKV in the presence of these compounds resulted in the rapid extinction of infectivity, suggesting elevated sensitivity to mutagenesis. USUV extinction was achieved when a 10-fold dilution was applied between every passage, but not in experiments involving undiluted virus, indicating an overall lower susceptibility than ZIKV. Although the two viruses are inhibited by the same three drugs, ZIKV is relatively more susceptive to serial passage in the presence of purine analogues (favipiravir and ribavirin), while USUV replication is suppressed more efficiently by 5-fluorouracil. These differences in sensitivity typically correlate with the increases in the mutation frequencies observed in each nucleoside treatment. These results are relevant to the development of efficient therapies based on lethal mutagenesis and support the rational selection of different mutagenic nucleosides for each pathogen. We will discuss the implications of these results to the fidelity of flavivirus replication and the design of antiviral therapies based on lethal mutagenesis.

Lysosomal accumulation of undegraded materials is a common feature of lysosomal storage diseases, neurodegenerative disorders, and the aging process. To better understand the role of lysosomal storage in the onset of cell damage, we used human fibroblasts loaded with sucrose as a model of lysosomal accumulation. Sucrose-loaded fibroblasts displayed increased lysosomal biogenesis followed by arrested cell proliferation. Notably, we found that reduced lysosomal catabolism and autophagy impairment led to an increase in sphingolipids ( i.e., sphingomyelin, glucosylceramide, ceramide, and the gangliosides GM3 and GD3), at both intracellular and plasma membrane (PM) levels. In addition, we observed an increase in the lysosomal membrane protein Lamp-1 on the PM of sucrose-loaded fibroblasts and a greater release of the soluble lysosomal protein cathepsin D in their extracellular medium compared with controls. These results indicate increased fusion between lysosomes and the PM, as also suggested by the increased activity of lysosomal glycosphingolipid hydrolases on the PM of sucrose-loaded fibroblasts. The inhibition of β-glucocerebrosidase and nonlysosomal glucosylceramidase, both involved in ceramide production resulting from glycosphingolipid catabolism on the PM, partially restored cell proliferation. Our findings indicate the existence of a new molecular mechanism underlying cell damage triggered by lysosomal impairment.-Samarani, M., Loberto, N., Solda, G., Straniero, L., Asselta, R., Duga, S., Lunghi, G., Zucca, F. A., Mauri, L., Ciampa, M. G., Schiumarini, D., Bassi, R., Giussani, P., Chiricozzi, E., Prinetti, A., Aureli, M., Sonnino, S. A lysosome-plasma membrane-sphingolipid axis linking lysosomal storage to cell growth arrest.

Sphingolipids (SLs) are amphiphilic molecules mainly associated with the external leaflet of eukaryotic plasma membrane, and are structural membrane components with key signaling properties. Since the beginning of the last century, a large number of papers described the involvement of these molecules in several aspects of cell physiology and pathology. Several lines of evidence support the critical role of SLs in inflammatory diseases, by acting as anti- or pro-inflammatory mediators. They are involved in control of leukocyte activation and migration, and are recognized as essential players in host response to pathogenic infection. We propose here a critical overview of current knowledge on involvement of different classes of SLs in inflammation, focusing on the role of simple and complex SLs in pathogen-mediated inflammatory response.

Prostate cancer (PC) is one of the most common leading causes of cancer-related death in men. Currently, the main therapeutic approaches available for PC are based on the androgen deprivation and on radiotherapy. However, despite these treatments being initially effective in cancer remission, several patients undergo recurrence, developing a most aggressive and resistant PC. Emerging evidence showed that abiraterone acetate drug will reduce PC recurrence by a mechanism independent of the inhibition of Cytochrome P450 17α-hydroxylase/17,20-lyase. Here we describe the involvement in the abiraterone-mediated PC cell death of a particular class of bioactive lipids called sphingolipids (SL). Sphingolipids are components of plasma membrane (PM) that organize macromolecular complexes involved in the control of several signaling pathways including the tumor cell death induced by radiotherapy. Here, we show for the first time that bothin androgen-sensitive and insensitive PC cells abiraterone and ionizing radiation induce a reorganization of the plasma membrane SL composition. This event is triggered by activation of the PM-associated glycohydrolases that induce the production of cytotoxic ceramide by the in situ hydrolyses of glycosphingolipids. Taken together our data open a new scenario on the SL involvement in the therapy of PC.

The inhibitory effects demonstrated by activation of cannabinoid receptors (CB) on cancer proliferation and migration may also play critical roles in controlling bladder cancer (BC). CB expression on human normal and BC specimens was tested by immunohistochemistry. Human BC cells RT4 and RT112 were challenged with CB agonists and assessed for proliferation, apoptosis, and motility. Cellular sphingolipids (SL) constitution and metabolism were evaluated after metabolic labelling. CB1-2 were detected in BC specimens, but only CB2 was more expressed in the tumour. Both cell lines expressed similar CB2. Exposure to CB2 agonists inhibited BC growth, down-modulated Akt, induced caspase 3-activation and modified SL metabolism. Baseline SL analysis in cell lines showed differences linked to unique migratory behaviours and cytoskeletal re-arrangements. CB2 activation changed the SL composition of more aggressive RT112 cells by reducing (p amp;lt; 0.01) Gb3 ganglioside (-50 +/- 3%) and sphingosine 1-phosphate (S1P, -40 +/- 4%), which ended up to reduction in cell motility (-46 +/- 5%) with inhibition of p-SRC. CB2-selective antagonists, gene silencing and an inhibitor of SL biosynthesis partially prevented CB2 agonist-induced effects on cell viability and motility. CB2 activation led to ceramide-mediated BC cell apoptosis independently of SL constitutive composition, which instead was modulated by CB2 agonists to reduce cell motility. Funding Agencies|Lions Club Milano ai Cenacoli

Cystic fibrosis (CF) is the most common autosomal genetic recessive disease caused by mutations of gene encoding for the cystic fibrosis transmembrane conductance regulator. Patients with CF display a wide spectrum of symptoms, the most severe being chronic lung infection and inflammation, which lead to onset of cystic fibrosis lung disease. Several studies indicate that sphingolipids play a regulatory role in airway inflammation. The inhibition and downregulation of GBA2, the enzyme catabolizing glucosylceramide to ceramide, are associated with a significant reduction of IL-8 production in CF bronchial epithelial cells. Herein, we demonstrate that GBA2 plays a role in the proinflammatory state characterizing CF cells. We also report for the first time that Pseudomonas aeruginosa infection causes a recruitment of plasma membrane-associated glycosphingolipid hydrolases into lipid rafts of CuFi-1-infected cells. This reorganization of cell membrane may be responsible for activation of a signaling cascade, culminating in aberrant inflammatory response in CF bronchial epithelial cells upon bacterial infection. Taken together, the presented data further support the role of sphingolipids and their metabolic enzymes in controlling the inflammatory response in CF.

Outbreaks of Yellow Fever occur regularly in endemic areas of Africa and South America frequently leading to mass vaccination campaigns straining the availability of the attenuated Yellow Fever vaccine, YF-17D. The WHO has recently decided to discontinue regular booster-vaccinations since a single vaccination is deemed to confer life-long immune protection. Here, we have examined humoral (neutralizing antibody) and cellular (CD8 and CD4 T cell) immune responses in primary and booster vaccinees (the latter spanning 8 to 36 years after primary vaccination). After primary vaccination, we observed strong cellular immune responses with T cell activation peaking ≈2 weeks and subsiding to background levels ≈ 4 weeks post-vaccination. The number of antigen-specific CD8+ T cells declined over the following years. In >90% of vaccinees, in vitro expandable T cells could still be detected >10 years post-vaccination. Although most vaccinees responded to a booster vaccination, both the humoral and cellular immune responses observed following booster vaccination were strikingly reduced compared to primary responses. This suggests that pre-existing immunity efficiently controls booster inoculums of YF-17D. In a situation with epidemic outbreaks, one could argue that a more efficient use of a limited supply of the vaccine would be to focus on primary vaccinations.

Intracellular pathogens represent a serious threat during early life. Importantly, even though the immune system of newborns may be characterized as developmentally immature, with a propensity to develop Th2 immunity, significant CD8+ T-cell responses may still be elicited in the context of optimal priming. Replication deficient adenoviral vectors have been demonstrated to induce potent CD8+ T-cell response in mice, primates and humans. The aim of the present study was therefore to assess whether replication-deficient adenovectors could overcome the risk of overwhelming antigen stimulation during the first period of life and provide a pertinent alternative in infant vaccinology. To address this, infant mice were vaccinated with three different adenoviral vectors and the CD8+ T-cell response after early life vaccination was explored. We assessed the frequency, polyfunctionality and in vivo cytotoxicity of the elicited memory CD8+ T cells, as well as the potential of these cells to respond to secondary infections and confer protection. We further tested the impact of maternal immunity against our replication-deficient adenoviral vector during early life vaccination. Overall, our results indicate that memory CD8+ T cells induced by adenoviral vectors in infant mice are of good quality and match those elicited in the adult host.

The base excision repair DNA N-glycosylase MBD4 (also known as MED1), an interactor of the DNA mismatch repair protein MLH1, plays a central role in the maintenance of genomic stability of CpG sites by removing thymine and uracil from G:T and G:U mismatches, respectively. MBD4 is also involved in DNA damage response and transcriptional regulation. The interaction with other proteins is likely critical for understanding MBD4 functions. To identify novel proteins that interact with MBD4, we used tandem affinity purification (TAP) from HEK-293 cells. The MBD4-TAP fusion and its co-associated proteins were purified sequentially on IgG and calmodulin affinity columns; the final eluate was shown to contain MLH1 by western blotting, and MBD4-associated proteins were identified by mass spectrometry. Bands with molecular weight higher than that expected for MBD4 (˜66 kD) yielded peptides corresponding to MBD4 itself and the small ubiquitin-like molecule-1 (SUMO1), suggesting that MBD4 is sumoylated in vivo. MBD4 sumoylation was validated by co-immunoprecipitation in HEK-293 and MCF7 cells, and by an in vitro sumoylation assay. Sequence and mutation analysis identified three main sumoylation sites: MBD4 is sumoylated preferentially on K137, with additional sumoylation at K215 and K377. Patterns of MBD4 sumoylation were altered, in a DNA damage-specific way, by the anti-metabolite 5-fluorouracil, the alkylating agent N-Nitroso-N-methylurea and the crosslinking agent cisplatin. MCF7 extract expressing sumoylated MBD4 displays higher thymine glycosylase activity than the unmodified species. Of the 67 MBD4 missense mutations reported in The Cancer Genome Atlas, 14 (20.9%) map near sumoylation sites. These results indicate that MBD4 is sumoylated in vivo in a DNA damage-specific manner, and suggest that sumoylation serves to regulate its repair activity and could be compromised in cancer. This study expands the role played by sumoylation in fine-tuning DNA damage response and repair.

The live attenuated yellow fever vaccine (YF-17D) has been successfully used for more than 70 years. It is generally considered a safe vaccine, however, recent reports of serious adverse events following vaccination have raised concerns and led to suggestions that even safer YF vaccines should be developed. Replication deficient adenoviruses (Ad) have been widely evaluated as recombinant vectors, particularly in the context of prophylactic vaccination against viral infections in which induction of CD8+ T-cell mediated immunity is crucial, but potent antibody responses may also be elicited using these vectors. In this study, we present two adenobased vectors targeting non-structural and structural YF antigens and characterize their immunological properties. We report that a single immunization with an Ad-vector encoding the non-structural protein 3 from YF-17D could elicit a strong CD8+ T-cell response, which afforded a high degree of protection from subsequent intracranial challenge of vaccinated mice. However, full protection was only observed using a vector encoding the structural proteins from YF-17D. This vector elicited virus-specific CD8+ T cells as well as neutralizing antibodies, and both components were shown to be important for protection thus mimicking the situation recently uncovered in YF-17D vaccinated mice. Considering that Ad-vectors are very safe, easy to produce and highly immunogenic in humans, our data indicate that a replication deficient adenovector-based YF vaccine may represent a safe and efficient alternative to the classical live attenuated YF vaccine and should be further tested., Author Summary Live attenuated yellow fever vaccine (YF-17D) is an efficient and generally safe vaccine. Nevertheless, in recent years the reporting of serious adverse effects together with the given limitations in the use of this live vaccine in certain risk groups has spurred an interest in developing a more generally applicable and safer alternative. Using an adenovector platform and recombinant vaccines targeting both structural and non-structural YF antigens, we now demonstrate that non-replicating adenobased vaccines may be used to induce a state of host immunity, which like YF-17D vaccination encompasses both major arms of the adaptive immune system. Furthermore, in a murine challenge model, adenovector induced protection fully matched that induced by the current vaccine. Taken together our results strongly suggest that adenovectored vaccines targeting structural and non-structural viral antigens represent a viable and safe alternative to the existing live, attenuated YF vaccine.

SummaryDNA methylation is a major epigenetic mechanism for gene silencing. Whereas methyltransferases mediate cytosine methylation, it is less clear how unmethylated regions in mammalian genomes are protected from de novo methylation and whether an active demethylating activity is involved. Here, we show that either knockout or catalytic inactivation of the DNA repair enzyme thymine DNA glycosylase (TDG) leads to embryonic lethality in mice. TDG is necessary for recruiting p300 to retinoic acid (RA)-regulated promoters, protection of CpG islands from hypermethylation, and active demethylation of tissue-specific developmentally and hormonally regulated promoters and enhancers. TDG interacts with the deaminase AID and the damage response protein GADD45a. These findings highlight a dual role for TDG in promoting proper epigenetic states during development and suggest a two-step mechanism for DNA demethylation in mammals, whereby 5-methylcytosine and 5-hydroxymethylcytosine are first deaminated by AID to thymine and 5-hydroxymethyluracil, respectively, followed by TDG-mediated thymine and 5-hydroxymethyluracil excision repair.PaperClip

Different lines of evidence indicate that both aberrant activation of the phosphatidylinositol 3-OH kinase (PI3K)/Akt survival pathway and down-regulation of the death mediator ceramide play a critical role in the aggressive behavior, apoptosis resistance, and adverse clinical outcome of glioblastoma multiforme. Furthermore, the inhibition of the PI3K/Akt pathway and the up-regulation of ceramide have been found functional to the activity of many cytotoxic treatments against glioma cell lines and glioblastomas as well. A reciprocal control between PI3K/Akt and ceramide signaling in glioma cell survival/death is suggested by data demonstrating a protective role of PI3K/Akt on ceramide-induced cell death in glial cells. In this study we investigated the role of the PI3K/Akt pathway in the regulation of the ceramide metabolism in C6 glioma cells, a cell line in which the PI3K/Akt pathway is constitutively activated. Metabolic experiments performed with different radioactive metabolic precursors of sphingolipids and microscopy studies with fluorescent ceramides demonstrated that the chemical inhibition of PI3K and the transfection with a dominant negative Akt strongly inhibited ceramide utilization for the biosynthesis of complex sphingolipids by controlling the endoplasmic reticulum (ER) to Golgi vesicular transport of ceramide. These findings constitute the first evidence for a PI3K/Akt-dependent regulation of vesicle-mediated movements of ceramide in the ER-Golgi district. Moreover, the findings also suggest the activation of the PI3K/Akt pathway as crucial to coordinate the biosynthesis of membrane complex sphingolipids with cell proliferation and growth and/or to maintain low ceramide levels, especially as concerns those treatments that promote ceramide biosynthesis in the ER.

Primary cilia are assembled and maintained by evolutionarily conserved intraflagellar transport (IFT) proteins that are involved in the coordinated movement of macromolecular cargo from the basal body to the cilium tip and back. The IFT machinery is organized in two structural complexes named complex A and complex B. Recently, inactivation in the mouse germline of Ift genes belonging to complex B revealed a requirement of ciliogenesis, or proteins involved in ciliogenesis, for Sonic Hedgehog (Shh) signaling in mammals. Here we report on a complex A mutant mouse, defective for the Ift122 gene. Ift122-null embryos show multiple developmental defects (exencephaly, situs viscerum inversus, delay in turning, hemorrhage and defects in limb development) that result in lethality. In the node, primary cilia were absent or malformed in homozygous mutant and heterozygous embryos, respectively. Impairment of the Shh pathway was apparent in both neural tube patterning (expansion of motoneurons and rostro-caudal level-dependent contraction or expansion of the dorso-lateral interneurons), and limb patterning (ectrosyndactyly). These phenotypes are distinct from both complex B IFT mutant embryos and embryos defective for the ciliary protein hennin/Arl13b, and suggest reduced levels of both Gli2/Gli3 activator and Gli3 repressor functions. We conclude that complex A and complex B factors play similar but distinct roles in ciliogenesis and Shh/Gli3 signaling.

The attenuated yellow fever (YF) vaccine (YF-17D) was developed in the 1930s, yet little is known about the protective mechanisms underlying its efficiency. In this study, we analyzed the relative contribution of cell-mediated and humoral immunity to the vaccine-induced protection in a murine model of YF-17D infection. Using different strains of knockout mice, we found that CD4+ T cells, B cells, and Abs are required for full clinical protection of vaccinated mice, whereas CD8+ T cells are dispensable for long-term survival after intracerebral challenge. However, by analyzing the immune response inside the infected CNS, we observed an accelerated T cell influx into the brain after intracerebral challenge of vaccinated mice, and this T cell recruitment correlated with improved virus control in the brain. Using mice deficient in B cells we found that, in the absence of Abs, YF vaccination can still induce some antiviral protection, and in vivo depletion of CD8+ T cells from these animals revealed a pivotal role for CD8+ T cells in controlling virus replication in the absence of a humoral response. Finally, we demonstrated that effector CD8+ T cells also contribute to viral control in the presence of circulating YF-specific Abs. To our knowledge, this is the first time that YF-specific CD8+ T cells have been demonstrated to possess antiviral activity in vivo.

Suppressors of cytokine signaling (SOCS) proteins are intracellular proteins that inhibit cytokine signaling in a variety of cell types. A number of viral infections have been associated with SOCS upregulation; however, not much is known about the mechanisms regulating SOCS expression during viral infection. In this study, we used two pathologically distinct intracerebral (i.c.) infection models to characterize temporal and spatial aspects of SOCS expression in the virus-infected central nervous system (CNS), and by employing various knockout mouse models, we sought to identify regulatory mechanisms that may underlie a virus induced upregulation of SOCS in the CNS. We found that i.c. infection with either lymphocytic choriomeningitis virus (LCMV) or yellow fever virus (YF) results in gradual upregulation of SOCS1/3 mRNA expression peaking at day 7 postinfection (p.i.). In the LCMV model, SOCS mRNA was expressed in brain resident cells, including astrocytes and some neurons, and for SOCS1 in particular this upregulation was almost entirely mediated by gamma interferon (IFN-γ) produced by infiltrating T cells. After infection with YF, we also found SOCS expression to be upregulated in brain resident cells with a peak on day 7 p.i., but in this model, the upregulation was only partially dependent on IFN-γ and T cells, indicating that at least one other mediator was involved in the upregulation of SOCS following YF infection. We conclude that virus-induced inflammation of the CNS is associated with upregulation of SOCS1/3 mRNA expression in brain resident cells and that at least two distinctive pathways can lead to this upregulation. IMPORTANCE In the present report, we have studied the induction of SOCS1 and SOCS3 expression in the context of virus-induced CNS infection. We found that both a noncytolytic and a cytolytic virus induce marked upregulation of SOCS1 and -3 expression. Notably, the kinetics of the observed upregulation follows that of activity within proinflammatory signaling pathways and, interestingly, type II interferon (IFN), which is also a key inducer of inflammatory mediators, seems to be essential in initiating this counterinflammatory response. Another key observation is that not only cells of the immune system but also CNS resident cells are actively involved in both the pro- and the counterinflammatory immune circuits; thus, for example, astrocytes upregulate both C-X-C-motif chemokine 10 (CXCL10) and SOCS when exposed to type II IFN in vivo .

Sphingosine-1-phosphate (S1P) is a potent biomediator that can act as either an intracellular or an intercellular messenger. In the nervous system it exerts a wide range of actions, and specific membrane receptors for it have been identified in various regions. However, the physiological origin of extracellular S1P in the nervous system is largely unknown. We investigated cerebellar granule cells at different stages of differentiation and astrocytes in primary cultures as possible origins of extracellular S1P. Although these cells show marked differences in S1P metabolism, we found that they can all release S1P and express mRNAs for S1P specific receptors. Extracellular S1P derives from the export of newly synthesized intracellular S1P, and not from the action of a released sphingosine kinase. S1P release is rapid, efficient, and can be regulated by exogenous stimuli. Phorbol ester treatment resulted in an increase in sphingosine kinase 1 activity in the membranes, accompanied by a significant increase in extracellular S1P. S1P release in cells from the cerebellum emerges as a regulated mechanism, possibly related to a specific pool of newly synthesized S1P. To our knowledge, this is the first evidence of the extracellular release of S1P by primary cells from the CNS, which supports a role of S1P as autocrine/paracrine physiological messenger in the cerebellum.

We recently reported that the marked decrease in cellular ceramide in primary astrocytes is an early event associated with the mitogenic activity of basic fibroblast growth factor (bFGF) (Riboni, L., Viani, P., Bassi, R., Stabieini, A., and Tettamanti, G. (2000) GLIA 32, 137–145). Here we show that a rapid activation of sphingomyelin biosynthesis appears to be the major mechanism responsible for the fall in ceramide levels induced by bFGF. When quiescent astrocytes were treated with bFGF, an increased amount of newly synthesized ceramide (from eitherl-[3H]serine or [3H]sphingosine) was directed toward the biosynthesis of sphingomyelin. Conversely, bFGF did not appear to affect ceramide levels by other metabolic pathways involved in ceramide turnover such as sphingomyelin degradation and ceramide biosynthesis, degradation, and glucosylation. Enzymatic studies demonstrating a relevant and rapid increase in sphingomyelin synthase activity after bFGF treatment have provided a convincing explanation for the activation of sphingomyelin biosynthesis. The bFGF-induced increase in sphingomyelin synthase appears to depend on a post-translational activation mechanism. Moreover, in the presence of brefeldin A, the activation of sphingomyelin biosynthesis was abolished, suggesting that the enzyme is located in a compartment other than the Golgi apparatus. Also the phosphatidylcholine-specific phospholipase C inhibitor D609 exerted a potent inhibitory effect on sphingomyelin biosynthesis. Finally, we demonstrate that inhibition of sphingomyelin biosynthesis by brefeldin A or D609 led to a significant inhibition of bFGF-stimulated mitogenesis. All this supports that, in primary astrocytes, the early activation of sphingomyelin synthase is involved in the bFGF signaling pathway leading to proliferation.

The effects of different bioactive sphingoid molecules on NOS activity of differentiated cerebellar granule cells were investigated by measuring the conversion of [ 3 H]arginine to [ 3 H]citrulline. Cytosolic Ca 2+ -dependent NOS activity was strongly inhibited in a dose-dependent manner by sphingosine in concentrations of 1–40 μM. This inhibition seems to be peculiar to sphingosine in that ceramide, N -acetylsphingosine, sphingosine-1P, sphinganine and tetradecylamine have no effect on the cytosolic enzyme at the considered concentrations, suggesting that it is the bulk of the sphingosine hydrophilic portion that is critical for cytosolic NOS inhibition. This inhibition of cytosolic NOS is not reversed by increasing the arginine concentration, so a competitive mechanism can be excluded. Instead, increasing the concentrations of calmodulin led to loss of sphingosine inhibition, suggesting that sphingosine interferes with the calmodulin-dependent activation of the enzyme by a competitive mechanism. Sphingosine and related compounds had no effect on the particulate Ca 2+ -independent NOS activity. The data obtained suggest that sphingosine could be involved in the regulation of NO production in neurons.

Current studies indicate that ceramide is involved in the regulation of important cell functions, namely cell growth, differentiation, and apoptosis. In the present study, the possible role of ceramide in the differentiation of neuroblastoma Neuro2a cells was investigated. The following results were obtained. (a) Ceramide content of Neuro2a cells, induced to differentiate by retinoic acid (RA) treatment rapidly increased after addition of RA, was maintained at high levels in RA-differentiated cells and returned to the starting levels with removal of RA and reversal of differentiation; under the same conditions, the sphingosine content remained unchanged. (b) After a short pulse with [3H]sphingomyelin or [3H]sphingosine or L-[3H]serine, the metabolic formation of ceramide was markedly higher and more rapid in RA-differentiated than undifferentiated cells. (c) Inhibitors of ceramide biosynthesis (Fumonisin B1, beta-chloroalanine and L-cycloserine) diminished the extent of the differentiating effect of RA and concomitantly Cer content decreased. (d) The activity of neutral sphingomyelinase increased after addition of RA, maintained high levels in RA-differentiated cells, and returned to the initial levels with removal of RA. (e) Experimental conditions that cause an elevation of ceramide content (treatment with sphingosine or ceramide or C2-ceramide or bacterial sphingomyelinase) inhibited cell proliferation and stimulated neurite outgrowth; dihydro-analogues of sphingosine, ceramide, and C2-ceramide had no effect on differentiation. (f) treatment with Fumonisin B1 completely inhibited sphingosine-induced differentiation. These data suggest a specific bioregulatory function of ceramide in the control of Neuro2a cell growth and differentiation and pose the general hypothesis of a mediator role of ceramide in the differentiation of cells of neural origin.

The glucose-dependent insulinotropic polypeptide receptor (GIPr) has been implicated in high fat diet-induced obesity and is proposed as an anti-obesity target despite an uncertainty regarding the mechanism of action. To independently investigate the contribution of the insulinotropic effects and the direct effects on adipose tissue, we generated transgenic mice with targeted expression of the human GIPr to white adipose tissue or beta-cells, respectively. These mice were then cross-bred with the GIPr knock-out strain. The central findings of the study are that mice with GIPr expression targeted to adipose tissue have a similar high fat diet -induced body weight gain as control mice, significantly greater than the weight gain in mice with a general ablation of the receptor. Surprisingly, this difference was due to an increase in total lean body mass rather than a gain in total fat mass that was similar between the groups. In contrast, glucose-dependent insulinotropic polypeptide-mediated insulin secretion does not seem to be important for regulation of body weight after high fat feeding. The study supports a role of the adipocyte GIPr in nutrient-dependent regulation of body weight and lean mass, but it does not support a direct and independent role for the adipocyte or beta-cell GIPr in promoting adipogenesis.

Cerebellar granule cells, differentiated in vitro, were parallelly fed with [Sph-3H]GM1 and [stearoyl-14C]GM1, under identical conditions (10−6 M ganglioside; pulse, from 1–4 h; chase, up to 24 h after 4 h pulse) and the salvage pathways of sphingosine and stearic acid were investigated. It was observed that both sphingosine and stearic acid, liberated during the intralysosomal degradation of ganglioside, are metabolically recycled, along distinct pathways. Sphingosine is used for the biosynthesis of a number of sphingolipids, particularly ceramide, glucosyl-ceramide, gangliosides and sphingomyelin; stearic acid is utilized for the biosynthesis of sphingolipids, and to a greater extent, glycero-phospholipids, especially those endogenously richer in stearic acid (phosphatidyl-ethanolamine and phosphatidyl-choline). No evidence was provided for a salvage pathway for ceramide.

Cerebellar granule cells differentiated in culture were incubated with ganglioside [3H-Sph]GM1 in order to have it inserted into the plasma membrane and metabolized. Among the formed metabolites radioactive sphingosine and ceramide were identified. [3H]Ceramide started to be measurable after 10 min of incubation (pulse), and [3H]sphingosine after 15 min. Their concentrations increased with pulse time, and after a 1-hour pulse, with chase time. After a 1-hour pulse with 2 × 10−6 M [3H-Sph]GM1 followed by a 4-hour chase, the amount of [3H]sphingosine and [3H]ceramide formed were 0.04 and 0.4 pmol/106 cells, respectively. Particularly the ability to produce sphingosine was higher in differentiated than in undifferentiated cells. It is concluded that ganglioside turnover contributes to the maintenance of the intracellular levels of free sphingosine and ceramide.

As the majority of gliomas arise through malignant transformation of astrocytes, we aimed at investigating the interaction between malignant glioma cells and astrocytes in a co-culture experimental model. For this purpose we analyzed the expression of genes and proteins involved in tumor promotion and invasion, such as glial fibrillary acidic protein (GFAP), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of MMP-2 (TIMP-2), transforming growth factor-beta1 (TGF-beta1), secreted protein acidic and rich in cysteine (SPARC), and connexin 43 (CX43). Co-cultures of human neural stem cell-derived astrocytes and U87 MG astrocytoma cells were performed in a transwell system. Gene expression was evaluated by real-time RT-PCR, and protein analysis was performed by Western blotting, SDS-zymography, and immunofluorescence. GFAP tended to be up-regulated in astrocytes co-cultivated with U87, suggesting a reactive response induced by glioma cells. CX43 mRNA tended to be down- regulated in co-cultured astrocytes, as well as the non-phosphorylated isoform at the protein level. MMP-2 mRNA tended to be up-regulated, and MMP-2 protein levels were significantly increased in astrocytes co-cultivated with U87. TIMP-2 and SPARC mRNA decreased in astrocytes co-cultivated with U87, showing lower expression in glioma cells. By contrast, SPARC protein expression was strongly induced in supernatants of co-cultured astrocytes. TGF-beta1 was not modified. Our results suggest that U87 cells elicit phenotype modifications in the neighbouring resident astrocytes very likely mediated by soluble factors. Glioma/astrocyte interaction could possibly trigger an astrocyte phenotype modification consistent with a malignant transformation, and favouring a more permissive environment for glioma cells invasion.

Different lines of evidence indicate that both aberrant activation of the phosphatidylinositol 3-OH kinase (PI3K)/Akt survival pathway and down-regulation of the death mediator ceramide play a critical role in the aggressive behavior, apoptosis resistance, and adverse clinical outcome of glioblastoma multiforme. Furthermore, the inhibition of the PI3K/Akt pathway and the up-regulation of ceramide have been found functional to the activity of many cytotoxic treatments against glioma cell lines and glioblastomas as well. A reciprocal control between PI3K/Akt and ceramide signaling in glioma cell survival/death is suggested by data demonstrating a protective role of PI3K/Akt on ceramide-induced cell death in glial cells. In this study we investigated the role of the PI3K/Akt pathway in the regulation of the ceramide metabolism in C6 glioma cells, a cell line in which the PI3K/Akt pathway is constitutively activated. Metabolic experiments performed with different radioactive metabolic precursors of sphingolipids and microscopy studies with fluorescent ceramides demonstrated that the chemical inhibition of PI3K and the transfection with a dominant negative Akt strongly inhibited ceramide utilization for the biosynthesis of complex sphingolipids by controlling the endoplasmic reticulum (ER) to Golgi vesicular transport of ceramide. These findings constitute the first evidence for a PI3K/Akt-dependent regulation of vesicle-mediated movements of ceramide in the ER-Golgi district. Moreover, the findings also suggest the activation of the PI3K/Akt pathway as crucial to coordinate the biosynthesis of membrane complex sphingolipids with cell proliferation and growth and/or to maintain low ceramide levels, especially as concerns those treatments that promote ceramide biosynthesis in the ER.

S1P is involved in the regulation of multiple biological processes (cell survival, growth, migration and differentiation) both in neurons and glial cells. The study was aimed at investigating the possible effects of S1P on calcium signaling in cerebellar astrocytes and differentiated granule cells. In cerebellar astrocytes S1P is able to mediate calcium signaling mainly through Gi protein coupled receptors, whereas in differentiated neurons it failed to evoke any calcium signaling, despite acting both extracellularly and intracellularly. The data indicate strict cell specificity in S1P-evoked calcium response, which could be relevant to communication between neurons and glial cells in the cerebellum.