Hypergravity promotes osteoclast differentiation via UPR signaling pathway
Ontology highlight
ABSTRACT: To investigate the effect of hypergravity stress on osteogenesis and osteoclast, we put the BMDM and BMSCs of mice treated with hypergravity perform transcriptome analysis.
Project description:This study investigates the impact of hypergravity (4g for 14 days) on the transcriptomic and electrophysiological profiles of rat ventricular cardiomyocytes. Using RNA sequencing, we identified significant changes in the expression of mechanically gated and mechanosensitive ion channel genes. Electrophysiological analyses revealed increased sensitivity of stretch-activated currents (ISAC) to mechanical stimuli in hypergravity-exposed cardiomyocytes. These findings highlight how altered gravitational conditions modulate cardiac cellular responses, with implications for understanding mechanoelectric feedback in both physiological and extreme environments.
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:Physical forces greatly influence the growth and function of an organism. Altered gravity can perturb normal development and induce corresponding changes in gene expression. Understanding this relationship between the physical and biological realms is important for NASA’s space travel goals. We use combined RNA-Seq and qRT-PCR to profile changes in early Drosophila melanogaster pupae exposed to chronic hypergravity (3 g, three times Earth’s gravity) to highlight gravity-dependent pathways and gene products. Robust transcriptional response was evident among the pupae developed in a hypergravity environment compared to control. 1,513 genes showed significantly (p < 0.05) altered gene expression in the 3 g samples. These findings were supported with qRT-PCR data. Major biological processes affected include ion transport, redox homeostasis, immune and humoral stress response, proteolysis, and cuticle development.
Project description:Bone remodeling is characterized by the sequential, local tethering of osteoclasts and osteoblasts, and is key to the maintenance of bone integrity. While bone matrix-mobilized growth factors, such as TGF-β, are proposed to regulate remodeling, no in vivo evidence exists that an osteoclast-produced molecule is the enigmatic coupling factor. We have identified Cthrc1, a protein secreted by mature bone-resorbing osteoclasts, that targets stromal cells so as to stimulate osteogenesis. The expression of Cthrc1 is robustly induced when mature osteoclasts are placed on dentin or hydroxyapatite, and also by increasing extracellular calcium. Cthrc1 expression in bone increases in a high turnover state, such as that which is induced by RANKL injections in vivo, whereas it decreases with aging or following alendronate treatment, conditions associated with suppressed bone turnover. The targeted deletion of the Cthrc1 gene eliminates Cthrc1 expression in bone, whereas its deficiency in osteoblasts does not exert any significant effect. Osteoclast-specific deletion of the Cthrc1 gene results in osteopenia due to reduced bone formation: it also impairs the coupling process following resorption induced by RANKL injections, with a resultant impairment of bone mass recovery. Thus, Cthrc1 is an osteoclast-secreted “coupling factor” that regulates bone remodeling and hence, skeletal integrity. Total bone marrow cells were prepared from the femurs and tibias of 8-10-week-old C57BL/6 mice and cultured in the presence of M-CSF (100ng/ml) for 3 days as described previously (Takeshita et al., 2000 JBMR 15:1477-1488). Cells were harvested with 0.02% EDTA/PBS and used as bone marrow macrophages (BMMs). These BMMs were cultured in the presence of M-CSF (100 ng/ml) and RANKL (100ng/ml) for 2 days. TRAP positive mononuclear cells were harvested and used as pre-osteoclasts (pOC). These pOC cells were further cultured in the presence of M-CSF and RANKL for 2 days in normal plastic plate or on dentin slices. After 2 days, multinucleated TRAP positive mature osteoclasts were generated as mature osteoclasts on plate (mOCp) and mature resorbing osteoclasts on dentin (mOCd), respectively. RNAs were extracted from four different stages of osteoclast lineage cells; BMMs, pOC, mOCp and mOCd, and used for microarray analysis.
Project description:Jurkat T cells have been exposed to 9g hypergravity in a custom-built pipette centrifuge for different times (GBF2021). Additionally, Jurkat T cells have been exposed to 300g for 5 minutes in a standard benchtop centrifuge, and waited for different times until adding lysis buffer. For comparison, Jurkat T cells have been exposed to 5 minutes of 42°C.
Project description:Jurkat T cells have been lysed after exposure to 3 or 15 minutes of 9g hypergravity in a ground-based pipette centrifuge. The RNA samples were analyzed with RNA-Seq transcriptomics.
Project description:We investigated differentially regulated and stably expressed genes in human Jurkat T lymphocytic cells in 5min simulated microgravity and hypergravity and compared expression profiles to identify gravity-regulated and unaffected genes as well as adaptation processes.
Project description:Osteogenesis imperfecta (OI) is a group of diseases caused by defects in type I collagen processing which result in skeletal fragility. While these disorders have traditionally been regarded as defects in osteoblast function, the role of matrix-embedded osteocytes, descendants of osteoblasts, in OI pathogenesis remains unknown. The homozygous human SP7 (c.946C > T, R316C) mutation results in a recessive form of osteogenesis imperfecta characterized by short stature, fragility fractures, low bone mineral density, and osteocyte dendrite defects. To better understand how the osteogenesis imperfecta-causingSP7 R316Cmutation affects the function of this transcription factor in different osteoblast lineage cells in bone, we generatedSp7 R342Cknock-in mice. Homozygous mutantSp7 R342C/R342Cmice demonstrate increased cortical porosity and reduced cortical bone mineral density, findings consistent with phenotypes observed in patients with this mutation. Sp7 R342Cmice show osteocyte dendrite defects, increased osteocyte apoptosis, and intracortical bone remodeling characterized by ectopic intracortical osteoclasts and elevated Tnfsf11 expression by osteocytes. Remarkably, these overt defects in osteocyte function contrast to preserved osteoblast function, suggesting that this Sp7 point mutation selectively interferes with the function of this transcription factor in osteocytes but not osteoblasts. Osteocyte morphology changes in Sp7 R342C/R342Cmice were not restored by inhibiting osteoclast formation, indicating that dendrite defects lie upstream of high intra-cortical osteoclast activity in this model. Moreover, transcriptomic profiling reveals that the expression of a core set osteocyte-enriched genes is highly dysregulated by the R342C mutation. Thus, this model supports a model in which osteocyte dysfunction can drive osteogenesis imperfecta pathogenesis, and provides a valuable resource to test novel therapeutic approaches and to understand the osteocyte-specific role of SP7 in bone homeostasis and remodeling.
Project description:We used microarrays to understand the effect miR-155 has on osteoclast differentiation. RAW264.7 cells were grown in a-MEM supplemented with 10% FBS and antibiotics. mRNA extracted from wild-type RAW264.7 cells and miR-155 mis-expressing cells either before or after 72 hr of stimulation with 20ng/ml RANKL and M-CSF to induce osteoclast differentiation.