BACKGROUND: Ionizing radiation (IR) can be extremely harmful for human cells since an improper DNA-damage response (DDR) to IR can contribute to carcinogenesis initiation. Perturbations in DDR pathway can originate from alteration in the functionality of the microRNA-mediated gene regulation being microRNAs (miRNAs) small noncoding RNA that act as post-transcriptional regulators of gene expression. In this study we gained insight into the role of miRNAs in the regulation of DDR to IR under microgravity a condition of weightlessness experienced by astronauts during space missions which could have a synergistic action on cells increasing the risk of radiation exposure. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed miRNA expression profile of human peripheral blood lymphocytes (PBL) incubated for 4 and 24 h in normal gravity (1 g) and in modeled microgravity (MMG) during the repair time after irradiation with 0.2 and 2Gy of gamma-rays. Our results show that MMG alters miRNA expression signature of irradiated PBL by decreasing the number of radio-responsive miRNAs. Moreover let-7i* miR-7 miR-7-1* miR-27a miR-144 miR-200a miR-598 miR-650 are deregulated by the combined action of radiation and MMG. Integrated analyses of miRNA and mRNA expression profiles carried out on PBL of the same donors identified significant miRNA-mRNA anti-correlations of DDR pathway. Gene Ontology analysis reports that the biological category of Response to DNA damage is enriched when PBL are incubated in 1 g but not in MMG. Moreover some anti-correlated genes of p53-pathway show a different expression level between 1 g and MMG. Functional validation assays using luciferase reporter constructs confirmed miRNA-mRNA interactions derived from target prediction analyses. CONCLUSIONS/SIGNIFICANCE: On the whole by integrating the transcriptome and microRNome we provide evidence that modeled microgravity can affects the DNA-damage response to IR in human PBL.

Space radiations and microgravity both could cause DNA damage in cells but the effects of microgravity on DNA damage response to space radiations are still controversial. A mRNA microarray and microRNA microarray in dauer larvae of Caenorhabditis elegans (C. elegans) that endured space xef xac x82ight environment and space radiations environment during 16.5-day Shenzhou-8 space mission were performed. In our study wild type and dys-1 mutant strains of C.elegans endured four conditions during shenzhou-8 spaceflight mission including spaceflight static condition(ss) spaceflight 1-g centrifugal condition(sc) ground control condition(gc) and no-transport control. Limited to the quantity of worm samples we performed technical-repeat test but not sample-repeat test. Accordingly eight miRNA microarrays were performed.

Space radiations and microgravity both could cause DNA damage in cells but the effects of microgravity on DNA damage response to space radiations are still controversial. A mRNA microarray and microRNA microarray in dauer larvae of Caenorhabditis elegans (C. elegans) that endured space xef xac x82ight environment and space radiations environment during 16.5-day Shenzhou-8 space mission were performed. In our study wild type and ced-1 mutant strains of C.elegans endured three conditions during shenzhou-8 spaceflight mission including spaceflight static condition(ss) spaceflight 1-g centrifugal condition(sc) and ground control condition(gc). Limited to the quantity of worm samples we performed technical-repeat test but not sample-repeat test.Accordingly xef xbc x8csix miRNA microarrays were performed.

Here in this study we systematically examined the patterns of DNA methylation and hydroxy-methylation with its functional implications in gene regulation for the cultured TK6 lymphoblastoid cells upon exposure to micro-gravity conditions. The results reported here indicate that simulated microgravity alters methylation patterns in a limited way and subsequently the expression of genes involved in stress response like ATF3 FBXO17 MAP3K13 and VCL in TK6 cells. Overall design: Examination of RNA-seq with 2 replicates each for 1 cell type

In the present study we analyzed miRNA and mRNA expression profiles in human peripheral blood lymphocytes (PBLs) incubated in microgravity condition simulated by a ground-based Rotating Wall Vessel (RWV) bioreactor. Our results show that 42 miRNAs were differentially expressed in MMG-incubated PBLs compared with 1g-incubated ones. Among these miR-9-5p miR-9-3p miR-155-5p miR-150-3p and miR-378-3p were the most dysregulated. To improve the detection of functional miRNA-mRNA pairs we performed gene expression profiles on the same samples assayed for miRNA profiling and we integrated miRNA and mRNA expression data. The functional classification of miRNA-correlated genes evidenced significant enrichments in the biological processes of immune/inflammatory response signal transduction regulation of response to stress regulation of programmed cell death and regulation of cell proliferation. We identified the correlation between miR-9-3p miR-155-5p miR-150-3p and miR-378-3p expression with that of genes involved in immune/inflammatory response (eg. IFNG and IL17F) apoptosis (eg. PDCD4 and PTEN) and cell proliferation (eg. NKX3-1 and GADD45A). Experimental assays of cell viability and apoptosis induction validated the results obtained by bioinformatics analyses demonstrating that in human PBLs the exposure to reduced gravitational force increases the frequency of apoptosis and decreases cell proliferation. Gene expression profiling was carried out in MMG-incubated PBLs vs. 1g-incubated PBLs on total RNA extracted from the same PBL samples assayed for miRNA profiling. We used the Whole Human Genome Oligo Microarray (Agilent) consisting of ~41.000 (60-mer) oligonucleotide probes which span conserved exons across the transcripts of the targeted full-length genes.

['Cancer-causing genome instability is a major concern during space travel due to exposure of astronauts to potent sources of high-linear energy transfer (LET) ionizing radiation. Hematopoietic stem cells (HSCs) are particularly susceptible to genotoxic stress, and accumulation of damage can lead to HSC dysfunction and oncogenesis. Our group recently demonstrated that aging human HSCs accumulate microsatellite instability coincident with loss of MLH1, a DNA Mismatch Repair (MMR) protein, which could reasonably predispose to radiation-induced HSC malignancies. Therefore, in an effort to reduce risk uncertainty for cancer development during deep space travel, we employed an Mlh1+/- mouse model to study the effects high-LET 56Fe ion space-like radiation. Irradiated Mlh1+/- mice showed a significantly higher incidence of lymphomagenesis with 56Fe ions compared to γ-rays and unirradiated mice, and malignancy correlated with increased MSI in the tumors. In addition, whole-exome sequencing analysis revealed high SNVs and INDELs in lymphomas being driven by loss of Mlh1 and frequently mutated genes had a strong correlation with human leukemias. Therefore, the data suggest that age-related MMR deficiencies could lead to HSC malignancies after space radiation, and that countermeasure strategies will be required to adequately protect the astronaut population on the journey to Mars.']

Transforming growth factor beta-1 (TGFbeta) is a tumor suppressor during the initial stage of tumorigenesis but it can switch to a tumor promoter during neoplastic progression. Ionizing radiation (IR) both a carcinogen and a therapeutic agent induces TGFbeta activation in vivo. We now show that IR sensitizes human mammary epithelial cells (HMEC) to undergo TGFbeta-mediated epithelial to mesenchymal transition (EMT). Non-malignant HMEC (MCF10A HMT3522 S1 and 184v) were irradiated with 2 Gy shortly after attachment in monolayer culture or treated with a low concentration of TGFbeta (0.4 ng/ml) or double-treated. All double-treated (IR+TGFbeta) HMEC underwent a morphological shift from cuboidal to spindle-shaped. This phenotype was accompanied by decreased expression of epithelial markers E-cadherin beta-catenin and ZO-1 remodeling of the actin cytoskeleton and increased expression of mesenchymal markers N-cadherin fibronectin and vimentin. Furthermore double-treatment increased cell motility promoted invasion and disrupted acinar morphogenesis of cells subsequently plated in Matrigel. Neither radiation nor TGFbeta alone elicited EMT even though IR increased chronic TGFbeta signaling and activity. Gene expression profiling revealed that double treated cells exhibit a specific 10-gene signature associated with Erk/MAPK signaling. We hypothesized that IR-induced MAPK activation primes non-malignant HMEC to undergo TGFbeta-mediated EMT. Consistent with this Erk phosphorylation were transiently induced by irradiation persisted in irradiated cells treated with TGFbeta and treatment with U0126 a Mek inhibitor blocked the EMT phenotype. Together these data demonstrate that the interactions between radiation-induced signaling pathways elicit heritable phenotypes that could contribute to neoplastic progression. Experiment Overall Design: Nonmalignant human mammary epithelial MCF10A cells (passages 106 and 108) were seeded at cloning density in 35mm dishes (10^5 cells/dish). Cell culture medium consisted of 3ml/dish of MGEM serum free medium (Cambrex Inc.) supplemented or not with 400pg/ml recombinant Transforming Growth Factor-beta. Cells were irradiated or not 5h post plating using 160 KV X-ray with a total dose of 2Gy. Sham IR-treated TGFbeta-treated and double-treated (IR+TGFbeta) MCF10A cells were harvested 8 days post-IR. Briefly cells were washed with PBS denatured in Trizol scraped off the dish and subjected to chloroform extraction. After centrifugation the upper phase was precipitated with an equal volume of isopropanol. RNA precipitates were resuspended in RNase free water and further purified on RNeasy columns (Qiagen Germany). RNA quality was assessed on an Agilent Bio-Analyzer. The dataset analyzed by microarray included biological duplicates for each treatment in two independent experiments and three sham treated samples. Microarray data were generated at the Lawrence Berkeley National Laboratory Molecular Profiling Laboratory (http://hta.lbl.gov) using a high-throughput automated GeneChip system (Affymetrix). Briefly target preparation HT_HG-U133A array plate hybridization setup washing and staining were performed on an Affymetrix robotic system (GCAS) using version 2.1 protocols. Scanning (protocol version 2.2.09) was performed on a CCD-based high throughput scanner (Affymetrix). Samples were analyzed and clustered with the (UNO) One Color GenetrafficTM software version 3.2-12 (Iobion Informatics LLC Stratagene La Jolla CA). Genes whose expression was specifically altered by treatment were defined as those in which dye ratio was more than 1.75-fold ( mean log2ratio >0.8) from baseline in at least three out of the four treated samples compared to the three sham samples. Significance analysis tests (p<0.05) were performed using Excel between sham samples and either IR TGFbeta or TGFbeta+IR samples.

Cell cycle and cell proliferation are decoupled under altered gravity conditions. We have previously shown that semisolid cell cultures of Arabidopsis suffer overall genome changes in response to altered gravity and also that cell cycle stages duration is altered. By using synchronized cell cultures we will demonstrate the precise alterations in cell cycle duration and also the transcriptional signature in any of them. Experiments consists on exposures of Arabidopsis cell cultures to 1g control/simulated microgravity (RPM) conditions. Asynchronous cells exposed for 14 h + Syncronous populations choosen to have an enrichment of cell cycle phases were used (being T7/T10 samples on G2 phase T14/T16 samples on G1 phase). 6 dye-swap - time course treated vs untreated comparison.

['Microgravity is one of the most important features in spaceflight. Previous evidence has shown that significant changes to the musculoskeletal and immune systems occurred under microgravity. The present study was undertaken to explore the change in protein abundance in human colon colorectal cells that were incubated for 48 or 72 h either in normal conditions and µG simulated conditions. The comparative proteomic method based on the 18O labeling technique was applied to investigate the up-regulated proteins and down-regulated proteins in SH-SY5Y under simulated microgravity.']

Articular and sterno-costal cartilages were isolated from skeletally-mature mice flown for 30 days on the BION-M1 mission. Samples were characterized histologically for proteoglycan loss and at the gene expression levels using Affymetrix gene arrays.