College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, South Korea.
College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, Gyeonggi-do, 16419, South Korea.
Biochem Biophys Res Commun. 2019 May 28;513(2):392-397. doi: 10.1016/j.bbrc.2019.04.010. Epub 2019 Apr 6.
The protein activator of protein kinase R (PKR) (PACT) is known to play important roles in PKR regulation and microRNA biogenesis. Based on the observation that PACT is specifically expressed in the ventricular zone (VZ) at the mid-neurogenic period, we examine the role of PACT in this embryonic neural stem cell niche. Here, we provide the first evidence that PACT increases neurosphere formation, as well as expression of Notch target genes and the neural stem cell marker Sox2 in primary neural stem cells in vitro. Consistently, introduction of PACT into the mouse embryonic brain in utero increased the fraction of cells localizing to the VZ. We also show that the PACT-enhanced stemness of neural stem cells is PKR-independent. At the molecular level, PACT was revealed to physically interact with C promoter binding factor 1 (CBF1) and dramatically strengthen the association between CBF1 and Notch intracellular domain (NICD), which indicates stabilization of the Notch transcriptional coactivation complex responsible for Notch target gene expression. Taken together, our study indicates that PACT is a novel transcriptional coactivator of the Notch pathway playing a pivotal role during mammalian brain development.
蛋白激酶 R（PKR）的蛋白激活剂（PACT）已知在 PKR 调节和 microRNA 生物发生中发挥重要作用。基于 PACT 在中神经发生期的室区（VZ）中特异性表达的观察，我们研究了 PACT 在这个胚胎神经干细胞龛中的作用。在这里，我们首次提供证据表明，PACT 在体外原代神经干细胞中增加神经球形成以及 Notch 靶基因和神经干细胞标记物 Sox2 的表达。一致地，将 PACT 引入体内的小鼠胚胎脑中增加了定位于 VZ 的细胞分数。我们还表明，PACT 增强的神经干细胞干性与 PKR 无关。在分子水平上，揭示 PACT 与 C 启动子结合因子 1（CBF1）物理相互作用，并显著增强 CBF1 与 Notch 细胞内结构域（NICD）之间的关联，这表明负责 Notch 靶基因表达的 Notch 转录共激活复合物的稳定。总之，我们的研究表明，PACT 是 Notch 通路的新型转录共激活因子，在哺乳动物大脑发育中发挥关键作用。
