Osteocytes transcriptome is altered during spaceflight

Bone loss is one of the major health problems for astronauts during long-term spaceflight and for patients during prolonged bed rest or paralysis. Growing evidence suggests that osteocytes, the most abundant cells in the mineralized bone matrix, play a key role in sensing mechanical forces applied to the skeleton and in transducing them into subcellular biochemical signals to modulate bone homeostasis. However, the precise molecular mechanisms underlying both mechanosensation and mechanotransduction in osteocytes under the real microgravity (µG) condition are poorly understood. To unravel the mechanisms by which osteocyte, sense and responds to mechanical unloading, we exposed murine osteocytic cell line, Ocy454, seeded on a highly porous polystyrene 3D scaffold, to 2, 4, or 6 days of µG on board the International Space Station (ISS) and compared their gene expression with cells at 1G on Earth. Bioinformatics analysis of cells exposed to µG revealed several pathways differentially regulated upon exposure to microgravity.

骨质流失是宇航员在长期太空飞行期间以及病患在长期卧床或瘫痪状态下的主要健康问题。日益增长的证据表明，成骨细胞，作为矿化骨基质中最丰富的细胞，在感知作用于骨骼的机械力以及将这些力转化为亚细胞生化信号以调节骨稳态方面发挥着关键作用。然而，在真实微重力（µG）条件下，成骨细胞中机械感觉和机械转导的精确分子机制尚不明确。为了揭示成骨细胞感知和响应机械卸载的机制，我们将小鼠成骨细胞系Ocy454接种于高孔隙率聚苯乙烯3D支架上，在搭载于国际空间站（ISS）上经过2、4或6天的微重力处理后，将其与地球上的1G条件下的细胞进行基因表达比较。对暴露于微重力的细胞进行的生物信息学分析揭示了在微重力作用下，多个信号通路发生差异调控。