Dexamethasone improves redox state in ataxia telangiectasia cells by promoting an NRF2-mediated antioxidant response

partially_open10noAtaxia telangiectasia (A-T) is a rare incurable neurodegenerative disease caused by biallelic mutations in the gene for ataxia-telangiectasia mutated (ATM). The lack of a functional ATM kinase leads to a pleiotropic phenotype, and oxidative stress is considered to have a crucial role in the complex physiopathology. Recently, steroids have been shown to reduce the neurological symptoms of the disease, although the molecular mechanism of this effect is largely unknown. In the present study, we have demonstrated that dexamethasone treatment of A-T lymphoblastoid cells increases the content of two of the most abundant antioxidants [glutathione (GSH) and NADPH] by up to 30%. Dexamethasone promoted the nuclear accumulation of the transcription factor nuclear factor (erythroid-derived 2)-like 2 to drive expression of antioxidant pathways involved in GSH synthesis and NADPH production. The latter effect was via glucose 6-phosphate dehydrogenase activation, as confirmed by increased enzyme activity and enhancement of the pentose phosphate pathway rate. This evidence indicates that glucocorticoids are able to potentiate antioxidant defenses to counteract oxidative stress in ataxia telangiectasia, and also reveals an unexpected role for dexamethasone in redox homeostasis and cellular antioxidant activity.openBiagiotti, Sara; Menotta, Michele; Orazi, Sara; Spapperi, Chiara; Brundu, Serena; Fraternale, Alessandra; Bianchi, Marzia; Rossi, Luigia; Chessa, Luciana; Magnani, MauroBiagiotti, Sara; Menotta, Michele; Orazi, Sara; Spapperi, Chiara; Brundu, Serena; Fraternale, Alessandra; Bianchi, Marzia; Rossi, Luigia; Chessa, Luciana; Magnani, Maur

Expression of the IRTA1 receptor identifies intraepithelial and subepithelial marginal zone B cells of the mucosa-associated lymphoid tissue (MALT)

AbstractIRTA1 (immunoglobulin superfamily receptor translocation-associated 1) is a novel surface B-cell receptor related to Fc receptors, inhibitory receptor superfamily (IRS), and cell adhesion molecule (CAM) family members and we mapped for the first time its distribution in human lymphoid tissues, using newly generated specific antibodies. IRTA1 was selectively and consistently expressed by a B-cell population located underneath and within the tonsil epithelium and dome epithelium of Peyer patches (regarded as the anatomic equivalents of marginal zone). Similarly, in mucosa-associated lymphoid tissue (MALT) lymphomas IRTA1 was mainly expressed by tumor cells involved in lympho-epithelial lesions. In contrast, no or a low number of IRTA1+ cells was usually observed in the marginal zone of mesenteric lymph nodes and spleen. Interestingly, monocytoid B cells in reactive lymph nodes were strongly IRTA1+. Tonsil IRTA1+ cells expressed the memory B-cell marker CD27 but not mantle cell-, germinal center-, and plasma cell-associated molecules. Polymerase chain reaction (PCR) analysis of single tonsil IRTA1+ cells showed they represent a mixed B-cell population carrying mostly mutated, but also unmutated, IgV genes. The immunohistochemical finding in the tonsil epithelial areas of aggregates of IRTA1+ B cells closely adjacent to plasma cells surrounding small vessels suggests antigen-triggered in situ proliferation/differentiation of memory IRTA1+ cells into plasma cells. Collectively, these results suggest a role of IRTA1 in the immune function of B cells within epithelia. (Blood. 2003;102: 3684-3692

Digging the New York City Skyline: Soil Fungal Communities in Green Roofs and City Parks

In urban environments, green roofs provide a number of benefits, including decreased urban heat island effects and reduced energy costs for buildings. However, little research has been done on the non-plant biota associated with green roofs, which likely affect their functionality. For the current study, we evaluated whether or not green roofs planted with two native plant communities in New York City functioned as habitats for soil fungal communities, and compared fungal communities in green roof growing media to soil microbial composition in five city parks, including Central Park and the High Line. Ten replicate roofs were sampled one year after planting; three of these roofs were more intensively sampled and compared to nearby city parks. Using Illumina sequencing of the fungal ITS region we found that green roofs supported a diverse fungal community, with numerous taxa belonging to fungal groups capable of surviving in disturbed and polluted habitats. Across roofs, there was significant biogeographical clustering of fungal communities, indicating that community assembly of roof microbes across the greater New York City area is locally variable. Green roof fungal communities were compositionally distinct from city parks and only 54% of the green roof taxa were also found in the park soils. Phospholipid fatty acid analysis revealed that park soils had greater microbial biomass and higher bacterial to fungal ratios than green roof substrates. City park soils were also more enriched with heavy metals, had lower pH, and lower quantities of total bases (Ca, K, and Mg) compared to green roof substrates. While fungal communities were compositionally distinct across green roofs, they did not differentiate by plant community. Together, these results suggest that fungi living in the growing medium of green roofs may be an underestimated component of these biotic systems functioning to support some of the valued ecological services of green roofs

Nano-Mechanical Characterization of Ataxia Telangiectasia Cells Treated with Dexamethasone

Ataxia telangiectasia is a rare genetic disease and no therapy is currently available. Glucocorticoid analogues have been shown to improve the neurological symptoms of treated patients. In the present study ataxia telangiectasia and wild type cells were used as a cellular model and treated with dexamethasone. The cells were subsequently investigated for membrane and whole cell mechanical properties by atomic force microscopy. In addition, cytoskeleton protein dynamics and nuclear shapes were assayed by fluorescence microscopy, while western blots were used to assess actin and tubulin content. At the macro level, dexamethasone directly modified the cell shape, Young's modulus and cytoskeleton protein dynamics. At the nano level, the roughness of the cell surface and the local nano-mechanical proprieties were found to be affected by Dexa. Our results show that ataxia telangiectasia and wild type cells are affected by Dexa, although there are dissimilarities in some macro-level and nano-level features between the tested cell lines. The Young's modulus of the cells appears to depend mainly on nuclear shape, with a slight contribution from the tested cytoskeleton proteins. The current study proposes that dexamethasone influences ataxia telangiectasia cell membranes contents, cell components and cell shape

Proteomics and transcriptomics analyses of ataxia telangiectasia cells treated with Dexamethasone

Ataxia telangiectasia (A-T) is an incurable and rare hereditary syndrome. In recent times, treatment with glucocorticoid analogues has been shown to improve the neurological symptoms that characterize this condition, but the molecular mechanism of action of these analogues remains unknown. Hence, the aim of this study was to gain insight into the molecular mechanism of action of glucocorticoid analogues in the treatment of A-T by investigating the role of Dexamethasone (Dexa) in A-T lymphoblastoid cell lines. We used 2DE and tandem MS to identify proteins that were influenced by the drug in A-T cells but not in healthy cells. Thirty-four proteins were defined out of a total of 746±63. Transcriptome analysis was performed by microarray and showed the differential expression of 599 A-T and 362 wild type (WT) genes and a healthy un-matching between protein abundance and the corresponding gene expression variation. The proteomic and transcriptomic profiles allowed the network pathway analysis to pinpoint the biological and molecular functions affected by Dexamethasone in Dexa-treated cells. The present integrated study provides evidence of the molecular mechanism of action of Dexamethasone in an A-T cellular model but also the broader effects of the drug in other tested cell lines

In vivo effects of dexamethasone on blood gene expression in ataxia telangiectasia

Ataxia telangiectasia (AT) is a rare incurable genetic disease caused by biallelic mutations in the Ataxia telangiectasia-mutated gene. Intra-erythrocyte infusion of dexamethasone improves clinical outcomes in AT patients; however, the molecular mechanisms that lead to this improvement remain unknown. Hence, to gain a better understanding of these mechanisms, we assessed the effects of glucocorticoid administration on gene expression in the blood of AT patients. Whole blood was obtained from nine children enrolled in a phase two clinical trial, who were being treated with dexamethasone (AT Dexa), from six untreated AT patients (AT) and from six healthy volunteers (WT). CodeLink Whole Genome Bioarrays were used to assess transcript expression. The reliability of the differentially expressed genes (DEGs) was verified by qRT-PCR analysis. The enriched Gene Ontology (GO) terms and the pathways of the Kyoto Encyclopedia of Genes and Genomes (KEGG) of DEGs obtained by group comparisons were achieved using the Database for Annotation, Visualization and Integrated Discovery (DAVID). Functional network analyses were computed by Reactome FI. The likely involved transcription factors were revealed by iRegulon. Among the identified DEGs influenced by the pathology and restored by dexamethasone, we detected 522 upregulated probes coding for known proteins, while 22 probes were downregulated, as they were in healthy subjects. These results provide useful information and represent a first step towards gaining a better understanding of the underlying mechanisms of the effects of dexamethasone on AT patients

ATM splicing variants as biomarkers for low dose dexamethasone treatment of A-T

Ataxia Telangiectasia (AT) is a rare incurable genetic disease, caused by biallelic mutations in the Ataxia Telangiectasia-Mutated (ATM) gene. Treatment with glucocorticoid analogues has been shown to improve the neurological symptoms that characterize this syndrome. Nevertheless, the molecular mechanism underlying the glucocorticoid action in AT patients is not yet understood. Recently, we have demonstrated that Dexamethasone treatment may partly restore ATM activity in AT lymphoblastoid cells by a new ATM transcript, namely ATMdexa1