Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States.
Front Endocrinol (Lausanne). 2021 May 18;12:649994. doi: 10.3389/fendo.2021.649994. eCollection 2021.
Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as "fatty acyls" and "carboxylic acids and derivatives", could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.
骨细胞可以通过缝隙连接和半通道将一些小分子(≤1 kDa)释放到细胞外环境中,如前列腺素 E2(PGE2)、一氧化氮(NO)和三磷酸腺苷(ATP),它们在骨细胞与其他组织细胞之间传递信号中起着关键作用。连接蛋白(Cx)43 是骨细胞中最丰富的连接蛋白。为了进一步发现骨细胞通过 Cx43 通道释放的分子,并更好地理解 Cx43 通道在骨细胞中的调节功能,我们使用液相色谱-串联质谱(LC-MS/MS)对来自两种转基因小鼠模型的条件培养基进行了非靶向全局代谢组学分析,这两种模型的 Cx43 显性负突变体由 10 kb-DMP1 启动子驱动:R76W(缝隙连接被阻断,而半通道被促进)和 Δ130-136(缝隙连接和半通道均被阻断)。结果表明,几种新的分子类别,如“脂肪酸”和“羧酸及其衍生物”,可以通过骨细胞 Cx43 通道释放。此外,Cx43 通道功能的改变影响了与炎症反应和氧化应激相关的代谢物的释放。通路分析进一步表明,柠檬酸循环是受 Cx43 通道调节的差异最大的代谢通路。总之,这些结果分离出了骨细胞通过 Cx43 通道释放的新的潜在代谢物,为理解骨细胞对自身和其他细胞的调节机制提供了新的视角。