Department of Nephrology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
Int J Biol Sci. 2011 Mar 16;7(3):269-78. doi: 10.7150/ijbs.7.269.
Numb was originally discovered as an intrinsic cell fate determinant in Drosophila by antagonizing Notch signaling. The present study is to characterize the role of Numb in oxidative stress-induced apoptosis of renal proximal tubular cells. Exposure of NRK52E cells to puromycin aminonucleoside (PA) resulted in caspase 3-dependent apoptosis. Numb expression was downregulated by PA in a time- and dose-dependent manner. Knocking down endogenous Numb by siRNA sensitized NRK52E cells to PA-induced apoptosis, whereas overexpressing Numb protected NRK52E cells from PA-induced apoptosis. Moreover, PA activated Notch signaling in a time- and dose-dependent manner as indicated by increased expression of the intracellular domain of Notch and Hes-1. Notch signaling inhibitor DAPT significantly attenuated Numb siRNA-augmented apoptosis. On the other hand, overexpression of intracellular domain of Notch1 could reverse the protective effect of Numb on PA-induced apoptosis. Taken together, our data demonstrated that, in renal proximal tubular cells, Numb functions as a protective molecule on PA-induced apoptosis through antagonizing Notch signaling activity.
Numb 最初在果蝇中被发现是一种内在的细胞命运决定因子，通过拮抗 Notch 信号通路。本研究旨在表征 Numb 在肾近端小管细胞氧化应激诱导的细胞凋亡中的作用。暴露于嘌呤霉素氨基核苷 (PA) 的 NRK52E 细胞导致 caspase 3 依赖性细胞凋亡。PA 以时间和剂量依赖的方式下调 Numb 的表达。通过 siRNA 敲低内源性 Numb 使 NRK52E 细胞对 PA 诱导的细胞凋亡敏感，而过表达 Numb 则保护 NRK52E 细胞免受 PA 诱导的细胞凋亡。此外，PA 以时间和剂量依赖的方式激活 Notch 信号通路，如 Notch 的细胞内结构域和 Hes-1 的表达增加所示。Notch 信号通路抑制剂 DAPT 显著减弱了 Numb siRNA 增强的细胞凋亡。另一方面，过表达 Notch1 的细胞内结构域可以逆转 Numb 对 PA 诱导的细胞凋亡的保护作用。总之，我们的数据表明，在肾近端小管细胞中，Numb 通过拮抗 Notch 信号通路活性，作为一种对 PA 诱导的细胞凋亡的保护分子发挥作用。
