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The mechanistic target of rapamycin pathway downregulates bone morphogenetic protein signaling to promote oligodendrocyte differentiation.
Glia ( IF 5.4 ) Pub Date : 2020-01-06 , DOI: 10.1002/glia.23776
Isis M Ornelas 1 , Luipa Khandker 1 , Stacey E Wahl 1 , Hirokazu Hashimoto 2 , Wendy B Macklin 2 , Teresa L Wood 1
Affiliation  

Oligodendrocyte precursor cells (OPCs) differentiate and mature into oligodendrocytes, which produce myelin in the central nervous system. Prior studies have shown that the mechanistic target of rapamycin (mTOR) is necessary for proper myelination of the mouse spinal cord and that bone morphogenetic protein (BMP) signaling inhibits oligodendrocyte differentiation, in part by promoting expression of inhibitor of DNA binding 2 (Id2). Here we provide evidence that mTOR functions specifically in the transition from early stage OPC to immature oligodendrocyte by downregulating BMP signaling during postnatal spinal cord development. When mTOR is deleted from the oligodendrocyte lineage, expression of the FK506 binding protein 1A (FKBP12), a suppressor of BMP receptor activity, is reduced, downstream Smad activity is increased and Id2 expression is elevated. Additionally, mTOR inhibition with rapamycin in differentiating OPCs alters the transcriptional complex present at the Id2 promoter. Deletion of mTOR in oligodendroglia in vivo resulted in fewer late stage OPCs and fewer newly formed oligodendrocytes in the spinal cord with no effect on OPC proliferation or cell cycle exit. Finally, we demonstrate that inhibiting BMP signaling rescues the rapamycin-induced deficit in myelin protein expression. We conclude that mTOR promotes early oligodendrocyte differentiation by suppressing BMP signaling in OPCs.

中文翻译:

雷帕霉素通路的机制靶点下调骨形态发生蛋白信号传导以促进少突胶质细胞分化。

少突胶质细胞前体细胞 (OPC) 分化并成熟为少突胶质细胞,后者在中枢神经系统中产生髓鞘。先前的研究表明,雷帕霉素 (mTOR) 的机制靶点是小鼠脊髓适当髓鞘形成所必需的,并且骨形态发生蛋白 (BMP) 信号抑制少突胶质细胞分化,部分是通过促进 DNA 结合抑制剂 2 (Id2) 的表达. 在这里,我们提供的证据表明,mTOR 通过在出生后脊髓发育过程中下调 BMP 信号,在从早期 OPC 到未成熟少突胶质细胞的过渡中发挥特殊作用。当 mTOR 从少突胶质细胞谱系中删除时,FK506 结合蛋白 1A (FKBP12)(BMP 受体活性的抑制因子)的表达降低,下游 Smad 活性增加,Id2 表达升高。此外,雷帕霉素在分化 OPCs 中抑制 mTOR 会改变存在于 Id2 启动子的转录复合物。体内少突胶质细胞中 mTOR 的缺失导致脊髓中晚期 OPC 和新形成的少突胶质细胞减少,而对 OPC 增殖或细胞周期退出没有影响。最后,我们证明抑制 BMP 信号可以挽救雷帕霉素诱导的髓鞘蛋白表达缺陷。我们得出结论,mTOR 通过抑制 OPC 中的 BMP 信号传导促进早期少突胶质细胞分化。体内少突胶质细胞中 mTOR 的缺失导致脊髓中晚期 OPC 和新形成的少突胶质细胞减少,而对 OPC 增殖或细胞周期退出没有影响。最后,我们证明抑制 BMP 信号可以挽救雷帕霉素诱导的髓鞘蛋白表达缺陷。我们得出结论,mTOR 通过抑制 OPC 中的 BMP 信号传导促进早期少突胶质细胞分化。体内少突胶质细胞中 mTOR 的缺失导致脊髓中晚期 OPC 和新形成的少突胶质细胞减少,而对 OPC 增殖或细胞周期退出没有影响。最后,我们证明抑制 BMP 信号可以挽救雷帕霉素诱导的髓鞘蛋白表达缺陷。我们得出结论,mTOR 通过抑制 OPC 中的 BMP 信号传导促进早期少突胶质细胞分化。
更新日期:2020-01-06
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