Departments of Endocrinology and Metabolism (S.L., T.W., Z.-X.D.), Geriatrics (H.-Y.Z.), and Biochemistry and Molecular Biology (X.M., Z.-H.Z., D.-H.K., H.-Q.W.), the First Affiliated Hospital, China Medical University, Shenyang 110001, China.
J Clin Endocrinol Metab. 2014 Nov;99(11):E2298-307. doi: 10.1210/jc.2014-1779. Epub 2014 Jul 25.
BAG3 plays a regulatory role in a number of cellular processes. Recent studies have attracted much attention on its role in activation of selective autophagy. In addition, we have very recently reported that BAG3 is implicated in a BECN1-independent autophagy, namely noncanonical autophagy.
The current study aimed to investigate the potential involvement of BAG3 in canonical autophagy triggered by Earle's Balanced Salt Solution (EBSS) starvation.
Replacement of complete medium with EBSS was used to trigger canonical autophagy. BAG3 expression was measured using real-time RT-PCR and Western blot. Autophagy was monitored using LC3-II transition and p62/SQSTM1 accumulation by Western blot, as well as punctate distribution of LC3 by immunofluorescence staining. Cell growth and apoptotic cell death was investigated using real-time cell analyzer and flowcytometry, respectively.
BAG3 expression was potently reduced by EBSS starvation. Forced expression of BAG3 suppressed autophagy and promoted apoptotic cell death of thyroid cancer cells elicited by starvation. In addition, in the presence of autophagy inhibitor, the enhancing effect of BAG3 on apoptotic cell death was attenuated.
These results suggest that BAG3 promotes apoptotic cell death in starved thyroid cancer cells, at least in part by autophagy attenuation.
BAG3 在许多细胞过程中发挥调节作用。最近的研究引起了人们对其在选择性自噬激活中的作用的极大关注。此外，我们最近非常报告称，BAG3 参与了 BECN1 独立的自噬，即非典型自噬。
本研究旨在研究 BAG3 是否参与 Earle 的平衡盐溶液 (EBSS) 饥饿引发的经典自噬。
用 EBSS 替代完全培养基以触发经典自噬。使用实时 RT-PCR 和 Western blot 测量 BAG3 的表达。通过 Western blot 监测自噬，通过 LC3-II 转化和 p62/SQSTM1 积累以及通过免疫荧光染色检测 LC3 的点状分布来监测自噬。使用实时细胞分析仪和流式细胞术分别研究细胞生长和凋亡细胞死亡。
EBSS 饥饿强烈降低了 BAG3 的表达。BAG3 的强制表达抑制了自噬并促进了饥饿引起的甲状腺癌细胞的凋亡细胞死亡。此外，在存在自噬抑制剂的情况下，BAG3 对凋亡细胞死亡的增强作用减弱。
这些结果表明，BAG3 通过自噬衰减促进饥饿的甲状腺癌细胞的凋亡细胞死亡，至少部分是这样。
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