Department of Anatomy, Guilin Medical University, 541004, Guilin, China.
Center of Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, 541004, Guilin, China.
Endocrine. 2019 Dec;66(3):585-595. doi: 10.1007/s12020-019-02048-y. Epub 2019 Sep 14.
Whether autophagy plays a key role in thyroxine-induced cardiomyocyte hypertrophy, and whether the role of autophagy in thyroxine-induced cardiomyocyte hypertrophy is related to targeting of Beclin-1 by miR-762 remains unclear. This research focused on testing these two hypotheses. Importantly, the results of this study will help us better understand the molecular mechanisms of thyroxine-induced cardiomyocyte hypertrophy.
In vivo and in vitro, RT-PCR, western blot, and dual luciferase reporter assay were performed to understand the molecular mechanism of thyroxine-induced cardiomyocyte hypertrophy. HE staining, Masson staining, transmission electron microscopy, and immunofluorescence were used to observe intuitively changes of hearts and cardiomyocytes.
Our results showed that in vivo, serum TT3, TT4, and heart rate were significantly upregulated in the T4 group compared with the control group. Moreover, the surface area of cardiomyocytes was significantly increased in the T4 group, and the structural disorder was accompanied by obvious hyperplasia of collagen fibers. The expression of ANP, and β-MHC was significantly upregulated in the T4 group. In addition, LC3 II/LC3 I, Beclin-1 and the count of autophagic vacuoles were significantly upregulated, but miR-762 was significantly downregulated in the T4 group compared to the control group. Subsequently, a dual luciferase reporter assay suggested that Beclin-1 was the target gene of miR-762. In vitro, the results for the T3 group were consistent with the results for the T4 group. Furthermore, cardiomyocyte hypertrophy and autophagic activity were attenuated in the T3 + miR-762 mimic group compared with the T3 group. In contrast, cardiomyocyte hypertrophy and autophagic activity were aggravated in the T3 + miR-762 inhibitor group compared with the T3 group.
miR-762 modulates thyroxine-induced cardiomyocyte hypertrophy by inhibiting Beclin-1.
尚不清楚自噬是否在甲状腺素诱导的心肌细胞肥大中起关键作用，以及自噬在甲状腺素诱导的心肌细胞肥大中的作用是否与 miR-762 靶向 Beclin-1 有关。本研究旨在检验这两个假设。重要的是，本研究的结果将帮助我们更好地理解甲状腺素诱导的心肌细胞肥大的分子机制。
通过 RT-PCR、western blot 和双荧光素酶报告基因检测，在体内和体外研究甲状腺素诱导的心肌细胞肥大的分子机制。采用 HE 染色、Masson 染色、透射电镜和免疫荧光观察心脏和心肌细胞的变化。
我们的结果表明，在体内，与对照组相比，T4 组血清 TT3、TT4 和心率明显升高。此外，T4 组心肌细胞表面积明显增大，结构紊乱伴胶原纤维明显增生。T4 组 ANP 和β-MHC 的表达明显上调。此外，与对照组相比，T4 组 LC3 II/LC3 I、Beclin-1 和自噬小体计数明显上调，而 miR-762 明显下调。随后，双荧光素酶报告基因检测表明 Beclin-1 是 miR-762 的靶基因。在体外，T3 组的结果与 T4 组的结果一致。此外，与 T3 组相比，T3+miR-762 模拟物组的心肌细胞肥大和自噬活性减弱。相反，与 T3 组相比，T3+miR-762 抑制剂组的心肌细胞肥大和自噬活性加重。
miR-762 通过抑制 Beclin-1 调节甲状腺素诱导的心肌细胞肥大。
