Project description:The mechanism by which chondrocytes respond to reduced mechanical loading environments and the subsequent risk of developing osteoarthritis remains unclear. This is of particular concern for astronauts. In space the reduced joint loading forces during prolonged microgravity (10-6 g) exposure could lead to osteoarthritis (OA), compromising quality of life post-spaceflight. In this study, we encapsulated human chondrocytes in an agarose gel of similar stiffness to the pericellular matrix to mimic the cartilage microenvironment. We then exposed agarose-chondrocyte constructs to simulated microgravity (SM) for four days using a rotating wall vessel (RWV) bioreactor to better assess the cartilage health risks associated with spaceflight. Metabolites extracted from media and agarose gel constructs were analyzed on liquid chromatography-mass spectrometry. Global metabolomic profiling detected a total of 1205 metabolite features, with 497 significant metabolite features identified by ANOVA (FDR-corrected p-value < 0.05). Specific metabolic shifts detected in response to SM exposure resulted in clusters of co-regulated metabolites, with glutathione, nitrogen, histidine, vitamin B3, and aminosugars metabolism identified by variable importance in projection scores. Microgravity-induced metabolic shifts in gel constructs and media were indicative of protein synthesis, energy and nucleotide metabolism, and oxidative catabolism. Microgravity associated-metabolic shifts were consistent with our previously published early osteoarthritic metabolomic profiles in human synovial fluid, suggesting that even short-term exposure to microgravity (or other reduced mechanical loading environments) may lead to the development of OA. This work further suggests the potential to detect these metabolic perturbations in synovial fluid in vivo to ascertain osteoarthritis risk in astronauts.
Project description:The mechanism by which chondrocytes respond to reduced mechanical loading environments and the subsequent risk of developing osteoarthritis remains unclear. This is of particular concern for astronauts. In space the reduced joint loading forces during prolonged microgravity (10-6 g) exposure could lead to osteoarthritis (OA), compromising quality of life post-spaceflight. In this study, we encapsulated human chondrocytes in an agarose gel of similar stiffness to the pericellular matrix to mimic the cartilage microenvironment. We then exposed agarose-chondrocyte constructs to simulated microgravity (SM) using a rotating wall vessel (RWV) bioreactor to better assess the cartilage health risks associated with spaceflight. Global metabolomic profiling detected a total of 1205 metabolite features across all samples, with 497 significant metabolite features identified by ANOVA (FDR-corrected p-value < 0.05). Specific metabolic shifts detected in response to SM exposure resulted in clusters of co-regulated metabolites, as well as key metabolites identified by variable importance in projection scores. Microgravity-induced metabolic shifts in gel constructs and media were indicative of protein synthesis, energy metabolism, nucleotide metabolism, and oxidative catabolism. The microgravity associated-metabolic shifts were consistent with early osteoarthritic metabolomic profiles in human synovial fluid, which suggests that even short-term exposure to microgravity (or other reduced mechanical loading environments) may lead to the development of OA.
Project description:Consumption of a diet rich in saturated fatty acids and carbohydrates contributes to the accumulation of fat in the liver and development of non-alcoholic steatohepatitis (NASH). Herein we investigated the hypothesis that short-term consumption of a high fat/sucrose Western diet (WD) alters the genomic and translatomic profile of the liver in association with changes in signaling through the protein kinase mTORC1, and that such alterations contribute to development of NAFLD. The results identify a plethora of mRNAs that exhibit altered expression and/or translation in the liver of rats consuming a WD compared to a CD. In particular, consumption of a WD altered the abundance and ribosome association of mRNAs involved in lipid and fatty acid metabolism, as well as those involved in glucose metabolism and insulin signaling. Hepatic mTORC1 signaling was enhanced when rats were fasted overnight and then refed in the morning; however, this effect was blunted in rats fed a WD as compared to a CD. Despite similar plasma insulin concentrations, fatty acid content was elevated in the liver of rats fed a WD as compared to a CD. We found that feeding had a significant positive effect on ribosome occupancy of 49 mRNAs associated with hepatic steatosis (e.g., LIPE, LPL), but this effect was blunted in the liver of rats fed a WD. In many cases, changes in ribosome association were independent of alterations in mRNA abundance, suggesting a critical role for diet-induced changes in mRNA translation in the expression of proteins encoded by those mRNAs. Overall, the findings demonstrate that short-term consumption of a WD impacts hepatic gene expression by altering the abundance of many mRNAs, but also causes wide-spread variation in mRNA translation that potentially contribute to development of hepatic steatosis.
Project description:Effect of "Sensory Protection" on the transcriptome of Gastrocnemius muscle denervated by Tibial nerve transection in the rat. Comparison is made between the muscle transcriptome in denervated muscle (D), muscle undergoing surgical repair with a motor nerve (immediate repair, or IR) and muscle undergoing surgical repair with a pure sensory nerve (sensory protection, or SP). There are 6 cohorts of rats with 4 to 6 rats in each cohort:<br><br>1 Month Denervated, 1 Month Immediate Repair, 1 Month Sensory Protection, 3 Month Denervated, 3 Month Immediate Repair, 3 Month Sensory Protection. <br><br>For each animal RNA was extracted from both the experimental operated (right) gastrocnemius muscle and the contralateral control unoperated (left) gastrocnemius. Samples were run in duplicate with fluorophor reversal experiments (i.e experimental limb RNA labelled with Cy3 and control limb RNA labelled with Cy5 and vice versa) to control for possible unequal incorporation of the dyes in the reverse transcription reaction.
Project description:Microgravity acts on cellular systems on several levels. Cells of the immune system especially react rapidly to changes in gravity. In this study, we performed a correlative metabolomics analysis on short-term and long-term microgravity effects on primary human macrophages. We could detect an increased amino acid concentration after five minutes of altered gravity, that was inverted after 11 days of microgravity. The amino acids that reacted the most to changes in gravity were tightly clustered. The observed effects indicated protein degradation processes in microgravity. Further, glucogenic and ketogenic amino acids were further degraded to Glucose and Ketoleucine. The latter is robustly accumulated in short-term and long-term microgravity but not in hypergravity. We detected highly dynamic and also robust adaptative metabolic changes in altered gravity. Metabolomic studies could contribute significantly to the understanding of gravity-induced integrative effects in human cells.
Project description:In this study, we evaluated cell proliferation and gene expression of hepatic stellate cells (HSCs) in simulated microgravity (SMG) and hypergravity (5 G).
Project description:Space flight missions last for a long time so bacterial infection during missions is considered a potential risk for astronauts. Studies of bacterial antibiotic resistance under spaceflight and simulated microgravity (SMG) have shown contrary results. To better understand the antibiotic stress resistance of K. pneumoniae in the microgravity environment, the original strain of K. pneumoniae (CGMCC 1.839), designated the KPO strain, was cultured under SMG conditions combined with background antibiotic exposure (SMGA) as the experimental group, while the control group was cultured in a NG environment without antibiotic exposure. After 20 cycles of incubation, the growth rate, antibiotic susceptibility, genomic , transcriptomic, and proteomic tests were conducted on the experimental and control groups designated the SMGA and NG strains, respectively.
Project description:Adaptation of humans in low gravity conditions is a matter of utmost importance when efforts are on to a gigantic leap in human space expeditions for tourism and formation of space colonies. In this connection, cardiovascular adaptation in low gravity is a critical component of human space exploration. Deep high-throughput sequencing approach allowed us to analyze the miRNA and mRNA expression profiles in human umbilical cord vein endothelial cells (HUVEC), cultured under gravity (G), and stimulated microgravity (MG) achieved with a clinostat. The present study identified totally 1870 miRNAs differentially expressed in HUVEC under MG condition when compared to the cells subjected to unitary G conditions. The functional association of identified miRNAs targeting specific mRNAs revealed that miRNAs, hsa-mir-496, hsa-mir-151a, hsa-miR-296-3p, hsa-mir-148a, hsa-miR-365b-5p, hsa-miR-3687, hsa-mir-454, hsa-miR-155-5p, and hsa-miR-145-5p differentially regulated the genes involved in cell adhesion, angiogenesis, cell cycle, JAK-STAT signaling, MAPK signaling, nitric oxide signaling, VEGF signaling, and wound healing pathways. Further, the q-PCR based experimental studies of upregulated and downregulated miRNA and mRNAs demonstrate that the above reported miRNAs influence the cell proliferation and vascular functions of the HUVEC in MG conditions effectively. Consensus on the interactome results indicates restricted fluctuations in the transcriptome of the HUVEC exposed to short-term MG that could lead to higher levels of endothelial functions like angiogenesis and vascular patterning.
Project description:The spaceflight experiment was carried out using male C57BL/10J mice (8 weeks old at launch). Wild type mice (n=3) were launched by Space Shuttle Discovery and housed on the International Space Station (ISS) for 91 days. They returned to the Earth by Space Shuttle Atlantis. But only one mouse returned to the Earth alive. Whole brain was sampled from the mouse killed by inhalation of carbon dioxide at the Life Sciences Support Facility of Kennedy Space Center within 3-4 hours after landing. After the spaceflight experiment, the on-ground experiment was also carried out at the Advanced Biotechnology Center in Genova, Italy. A mouse with the same species, sex, and age was housed in mice drawer system (MDS), which was utilized for the spaceflight (SF) mice, for 3 months as the ground control (GC). Another mouse was housed in normal vivarium cage as the laboratory control (LC). Amount of food and water supplementation and environmental conditions were simulated as the flight group. After 3 months, brain was sampled from one mouse in group GC and LC, respectively. Comprehensive analyses of gene expression were performed in the right brain. Total of 4,000 genes were analyzed. The expression levels of 60 genes significantly changed in response to SF compared with LC and/or GC. The 15 and 16 genes were up- (> 2 folds) and down-regulated (< 0.5 folds), respectively, following SF vs. GC. The levels of 58 genes were significantly altered by housing in MDS in space and/or on the ground. Forty seven and 11 genes were significantly up- and down-regulated vs. LC. Twenty seven out of these genes responded to caging in MDS both in space and on the ground. Further, 31 genes were influenced by housing in MDS on the Earth. Responses of the characteristics of brain to long-term gravitational unloading were investigated in mice.
Project description:Spaceflight poses many challenges for humans. Ground-based analogs typically focus on single parameters of spaceflight and their associated acute effects. This study assesses the long-term transcriptional effects following single and combination spaceflight analog conditions using the mouse model: simulated microgravity via hindlimb unloading (HLU) and/or low-dose γ-ray irradiation (LDR) for 21 days, followed by 4 months of readaptation. Changes in gene expression and epigenetic modifications in brain samples during readaptation were analyzed by whole transcriptome shotgun sequencing (RNA-seq) and reduced representation bisulfite sequencing (RRBS). The results showed minimal gene expression and cytosine methylation alterations at 4 months readaptation within single treatment conditions of HLU or LDR. In contrast, following combined HLU+LDR, gene expression and promoter methylation analyses showed multiple altered pathways involved in neurogenesis and neuroplasticity, the regulation of neuropeptides, and cellular signaling. In brief, neurological readaptation following combined chronic LDR and HLU is a dynamic process that involves pathways that regulate neuronal function and structure and may lead to late onset neurological sequelae.