Department of Medical Biochemistry, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
J Biochem. 2011 Aug;150(2):199-208. doi: 10.1093/jb/mvr063. Epub 2011 May 17.
The mammalian Hippo pathway is composed of mammalian Ste20-like (MST) kinases and large tumour suppressor (LATS) kinases. Upon the activation of the pathway, MST kinases phosphorylate and activate LATS kinases, which in turn phosphorylate transcriptional co-activators, yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), recruit them to the cytosol from the nucleus and turn off cell cycle-promoting and anti-apoptotic gene transcriptions. Thus, the pathway restricts cell overgrowth and prevents tumourigenesis. Although a high cell density and stress signallings are known to activate the pathway, no specific stimulators are so far reported. As the dysfunction of the pathway is frequent in human cancers and correlates with poor prognosis, it is important to find out reagents that stimulate the pathway for not only basic research but also clinical medicine. We here developed a cell-based method of screening reagents that induce the recruitment of YAP to the cytosol. Using this method, we found that dobutamine inhibits the YAP-dependent gene transcription. Contrary to our expectations, the effect of dobutamine is independent of the Hippo pathway but our method opens the possibility to discover Hippo pathway stimulators or Hippo-independent YAP inhibitors.
哺乳动物 Hippo 通路由哺乳动物 Ste20 样（MST）激酶和大肿瘤抑制因子（LATS）激酶组成。通路激活后，MST 激酶磷酸化并激活 LATS 激酶，后者转而磷酸化转录共激活因子 yes 相关蛋白（YAP）和 PDZ 结合基序转录共激活因子（TAZ），将它们从细胞核招募到细胞质，并关闭促进细胞周期和抗细胞凋亡的基因转录。因此，该通路限制细胞过度生长并防止肿瘤发生。尽管已知高细胞密度和应激信号可激活该通路，但目前尚无特定的激动剂被报道。由于该通路的功能障碍在人类癌症中很常见，并与预后不良相关，因此找到可刺激该通路的试剂不仅对基础研究而且对临床医学都很重要。我们在此开发了一种基于细胞的筛选试剂的方法，该方法可诱导 YAP 向细胞质募集。使用该方法，我们发现多巴酚丁胺抑制了 YAP 依赖性基因转录。与我们的预期相反，多巴酚丁胺的作用不依赖 Hippo 通路，但我们的方法为发现 Hippo 通路激动剂或 Hippo 非依赖性 YAP 抑制剂开辟了可能性。
