Project description:Exposure to microgravity causes bone loss in humans, and the underlying mechanism is believed to be at least partially due to a decrease in bone formation by osteoblasts. Here, we examined the hypothesis that microgravity changes osteoblast gene expression profiles, resulting in bone loss. For this study, we developed an in vitro system that simulates microgravity using the Random Positioning Machine (RPM) to study the effects of microgravity on 2T3 pre-osteoblast cells grown in gas-permeable culture disks. Exposure of 2T3 cells to simulated microgravity using RPM for up to 9 days significantly inhibited alkaline phosphatase activity, recapitulating an expected bone loss response, without altering cell proliferation and shape. Next, we carried out a DNA microarray analysis to determine the gene expression profile of 2T3 cells exposed to 3 days of simulated microgravity. Among 10,000 genes examined with the microarray, 88 were downregulated while 52 were upregulated significantly by simulated microgravity by more than two-fold in comparison to the static 1g condition. By using real-time PCR assays, we verified the microarray data using some of the expected genes. For example, we confirmed that microgravity induced downregulation of alkaline phosphatase, runt related transcription factor 2 (runx2), osteomodulin, and parathyroid hormone 1 receptor, while confirming upregulation of cathepsin K mRNAs. In addition to the changes of the expected genes, the microarray data identified many more genes. The identification of these gravisensitive genes provide an useful insight in generating further hypotheses regarding their roles not only in microgravity-induced bone loss, but also in general population of patients with similar pathologic conditions such as osteoporosis. Keywords: other
Project description:In space, multiple unique environmental factors, particularly microgravity and space radiation, pose constant threat to the astronaut’s health. To gain insight into the role of miRNAs and lncRNAs in response to radiation and microgravity, we analyzed RNA expression profiles in human lymphoblastoid TK6 cells incubated for 24 h in static condition or in rotating condition to stimulate microgravity in space after 2 Gy γ-ray irradiation. Expression of 14 lncRNAs and 17 mRNAs was found to be significantly down-regulated in the simulated microgravity condition. In contrast, irradiation up-regulated the expression of 55 lncRNAs and 56 mRNAs, while only one lncRNA, but no mRNA, was down-regulated. Furthermore, 2 miRNAs, 70 lncRNAs, and 87 mRNAs showed significantly altered expression under simulated microgravity after irradiation, and these changes were independently induced by irradiation and simulated microgravity. Together, our results indicate that simulated microgravity and irradiation additively and independently alter the expression of RNAs and their target genes in human lymphoblastoid cells.
Project description:A multidisciplinary approach was employed to characterize morphological, biochemical and molecular changes underlying the human BMSCs response to simulated microgravity exposure during osteogenic differentiation.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:Methods: RNA-seq libraries were prepared using the Illumina TruSeq RNA kit and the TrueSeq method was employed for mRNA enrichment. The libraries were quantified and samples were multiplexed in each lane of the flowcell. Cluster generation was performed and then sequenced on the Illumina HiSeq1000 system. Reads were mapped on the Human Genome Reference and normalized expression table was generated. Results: Among differentially expressed genes, 53 of them were up-regulated and 75 were down-regulated. Conclusions: Data demonstrate increased expression of genes associated with growth, development, and pro-survival in cardiac progenitors cultured under simulated microgravity compared with those cultured under standard gravity. RNA-sequencing analysis was performed to compare global gene expression profiles of cells at differentiation day 8 under simulated microgravity vs. standard gravity.
Project description:Prolonged skeletal unloading through bedrest results in bone loss similar to that observed in elderly osteoporotic patients, but with an accelerated timeframe. This rapid effect on weight-bearing bones is also observed in astronauts who lose up to 2% of their bone mass per month spent in Space. Despite important implications for Spaceflight travellers and bedridden patients on Earth, the exact mechanisms involved in disuse osteoporosis have not been elucidated. Parathyroid hormone-related protein (PTHrP) regulates many physiological processes including skeletal development, and has been proposed as a gravisensor. To investigate the role of PTHrP in microgravity-induced bone loss, trabecular osteoblasts (TOs) from Pthrp+/+ and -/- mice were exposed to simulated microgravity for 6 days. Viability of TOs decreased in inverse proportion to PTHrP expression levels. Microarray analysis of Pthrp+/+ TOs after 6 days at 0g revealed expression changes in genes encoding prolactins,apoptosis and survival molecules, bone metabolism and extra-cellular matrix composition proteins, chemokines, IGF family and Wnt-related signalling molecules. Importantly, 88% of 0g-induced expression changes in Pthrp+/+ cells overlap those observed in Pthrp-/- cells in normal gravity. Pulsatile treatment with PTHrP1-36 peptide during microgravity exposure reversed a large proportion of 0g-induced changes in Pthrp+/+ TOs. Our results confirm PTHrP efficacy as an anabolic agent to prevent microgravity-induced cell death in TOs. Total RNA samples extracted from Pthrp+/+and -/- trabecular osteoblasts (TOs) exposed for 6 days to simulated 0g in Synthecon rotating cell, or left 6 days in culture at 1g. Cells had either been treated with a pulsatile treatment (2 h/day) of PTHrP1-36 peptide (10-8M) or received a change in growth medium. In total: 8 different conditions with 2 replicates each, i.e. Pthrp+/+ TOs at 0g or 1g with or without PTHrP1-36 treatment, and Pthrp-/- TOs at 0g or 1 g,with or without PTHrP1-36 treatment.
Project description:Microgravity accelerates the aging of various physiological systems, and it is well acknowledged that aged individuals and astronauts both have increased susceptibility to infections and poor response to vaccination. Immunologically, dendritic cells (DCs) are the key players in linking the innate and adaptive immune responses. Their distinct and optimized differentiation and maturation phases play a critical role in presenting antigens and mounting effective lymphocyte responses for long-term immunity. Despite their importance, no studies to date have effectively investigated the effects of microgravity on DCs in their native microenvironment, which is primarily located within tissues. Here, we address a significantly outstanding research gap by examining the effects of simulated microgravity via a random positioning machine on both immature and mature DCs cultured in biomimetic collagen hydrogels, a surrogate for tissue matrices. Furthermore, we explored the effects of loose and dense tissues via differences in collagen concentration. Under these various environmental conditions, the DC phenotype was characterized using surface markers, cytokines, function, and transcriptomic profiles. Our data indicate that aged or loose tissue and exposure to RPM-induced simulated microgravity both independently alter the immunogenicity of immature and mature DCs. Interestingly, cells cultured in denser matrices experience fewer effects of simulated microgravity at the transcriptome level. Our findings are a step forward to better facilitate healthier future space travel and enhance our understanding of the aging immune system on Earth.