Department of Pediatrics, Ganzhou People's Hospital, Ganzhou 341000, China.
Department of Pediatrics, Ganzhou People's Hospital, Ganzhou 341000, China.
Biophys Chem. 2020 Dec;267:106483. doi: 10.1016/j.bpc.2020.106483. Epub 2020 Sep 25.
Based on the osteogenic effect, triiodothyronine (T3) plays an important role in bone growth and development. Autophagy contributes to osteoblast formation and subsequent osteogenesis. Our study aims to explore the relationship among T3, autophagy and osteogenesis. In this study, cranial primary osteoblasts were obtained from 2 to 3 weeks-old Sprague Dawley (SD) rat fetuses. Osteoblasts were treated with T3, and then the autophagic parameters of Osteoblasts (including autophagic proteins, LC3 conversion rate and autophagosome formation) were observed through Western Blotting and Transmission Electron Microscopy. Next, after using autophagic pharmacological inhibitors (3-MA and chloroquine) and silencing vectors of autophagic genes (BECN1, Atg5 and Atg7) to downregulate autophagic activity, osteoblast proliferation and osteoblastic gene expression were detected using cell counting kit-8 (CCK-8) and quantitative real-time PCR (qRT-PCR) assays, respectively. Ultimately, the mice treated with partial thyroidectomy (PTx mice) were used to further observe the effect of T3 on the formation and autophagy of osteoblasts in trabecular bone in vivo. Our results show that T3 enhances osteoblast autophagy. Autophagy suppression with 3-MA, chloroquine or autophagy-genes knockdown reverses T3-promoted osteoblast formation. In vivo assays showed that the formation and autophagy of osteoblasts in bone tissue were reduced in T3-deficient young mice. Overall, T3 can promote osteoblast formation by activation of autophagy.
基于成骨作用，三碘甲状腺原氨酸（T3）在骨生长和发育中起着重要作用。自噬有助于成骨细胞的形成和随后的成骨作用。我们的研究旨在探讨 T3、自噬和成骨作用之间的关系。在这项研究中，我们从 2 至 3 周龄的 Sprague Dawley（SD）大鼠胎儿中获得颅骨原代成骨细胞。用 T3 处理成骨细胞，然后通过 Western Blotting 和透射电子显微镜观察成骨细胞的自噬参数（包括自噬蛋白、LC3 转化率和自噬体形成）。接下来，使用自噬药理学抑制剂（3-MA 和氯喹）和自噬基因沉默载体（BECN1、Atg5 和 Atg7）下调自噬活性后，分别使用细胞计数试剂盒-8（CCK-8）和定量实时 PCR（qRT-PCR）检测成骨细胞增殖和成骨细胞基因表达。最后，使用部分甲状腺切除术（PTx 小鼠）处理的小鼠进一步观察 T3 对体内小梁骨中成骨细胞形成和自噬的影响。我们的结果表明，T3 增强成骨细胞自噬。用 3-MA、氯喹或自噬基因敲低抑制自噬会逆转 T3 促进成骨细胞形成的作用。体内实验表明，T3 缺乏的年轻小鼠骨组织中成骨细胞的形成和自噬减少。总的来说，T3 可以通过激活自噬来促进成骨细胞的形成。
