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Recent studies have confirmed that melatonin and N6-methyladenosine (m6A) modification can influence bone cell differentiation and bone formation. Melatonin can also regulate a variety of biological processes through m6A modification. Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1) serves as a reader of m6A modification. In this study, we used the hindlimb unloading model as an animal model of bone loss induced by simulated microgravity and used 2D clinorotation to simulate a microgravity environment for cells on the ground. We found that hnRNPA2B1 was downregulated both in vitro and in vivo during simulated microgravity. Further investigations showed that hnRNPA2B1 could promote osteoblast differentiation and that overexpression of hnRNPA2B1 attenuated the suppression of osteoblast differentiation induced by simulated microgravity. We also discovered that melatonin could promote the expression of hnRNPA2B1 under simulated microgravity. Moreover, we found that promotion of osteoblast differentiation by melatonin was partially dependent on hnRNPA2B1. Therefore, this research revealed, for the first time, the role of the melatonin/hnRNPA2B1 axis in osteoblast differentiation under simulated microgravity. Targeting this axis may be a potential protective strategy against microgravity-induced bone loss and osteoporosis.
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http://dx.doi.org/10.3390/cimb46090572 | DOI Listing |
NPJ Microgravity
September 2025
Department of Mechanical Engineering, UC Santa Barbara, Santa Barbara, CA, USA.
Microgravity experiments on board the International Space Station, combined with particle-resolved direct numerical simulations, were conducted to investigate the long-term flocculation behavior of clay suspensions in saline water in the absence of gravity. After an initial homogenization of the suspensions, different clay compositions were continuously monitored for 99 days, allowing a detailed analysis of aggregate growth through image processing. The results indicate that the onboard oscillations (g-jitter) may have accelerated the aggregation process.
View Article and Find Full Text PDFReprod Sci
September 2025
Department of Pathology, School of Basic Medical Sciences, Health Science Center, Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
Background And Objective: As space exploration advances, the effects of the microgravity environment on testicular injury and spermatogenic function in astronauts have attracted widespread attention, but the underlying mechanisms remain unclear.
Methods: In this study, testicular morphometry and Johnsen score were used to evaluate the degree of testicular injury. Then the upstream transcription factors of MeCP2 were verified using the dual-luciferase reporter assay.
Bone Rep
September 2025
Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
Spaceflight (SF) and disuse result in decreases in bone and skeletal muscle volume that increase fracture risk. Hindlimb unloading (HLU) has been widely used to model the effects of microgravity. However, the effects of SF and HLU on bone and skeletal muscle have not been directly compared during long-duration SF.
View Article and Find Full Text PDFFASEB J
September 2025
UR SIMPA, Stress Immunity Pathogens Laboratory, Faculty of Medicine, University of Lorraine, Vandœuvre-lès-Nancy, France.
With future manned space projects involving missions of unprecedented duration, multisystem deconditioning induced by spaceflight could seriously affect the well-being and health of astronauts. Safe and easily determined in-flight biomarkers are therefore needed to monitor health status. In this study, we simulated space deconditioning with a 5-day dry immersion (DI) of 18 healthy women and 19 healthy men and evaluated the effects of this protocol on three biomarkers: the neutrophil-to-lymphocyte ratio (NLR), the granulocyte-to-lymphocyte ratio (GLR) and the platelet-to-lymphocyte ratio (PLR).
View Article and Find Full Text PDFInt J Radiat Biol
September 2025
NASA Space Radiation Laboratory, Collider-Accelerator Dept., Brookhaven National Laboratory, Upton, NY, USA.
Purpose: Human space exploration is on an upward trajectory with new space stations being manufactured for scientific experiments, industrial development, and space tourism. These spacecraft in LEO and MEO will take advantage of Earth's magnetic field for radiation protection. Astronauts on the International Space Station receive an average radiation dose of 25 µSV/hour; around 250 times greater than the average sea level dose rate.
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