Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8510, Japan.
J Biol Chem. 2010 Feb 12;285(7):4909-19. doi: 10.1074/jbc.M109.042341. Epub 2009 Dec 4.
The tumor suppressor p53 is a transcription factor that regulates cell cycle, DNA repair, senescence, and apoptosis in response to DNA damage. Phosphorylation of p53 at Ser-46 is indispensable for the commitment to apoptotic cell death. A previous study has shown that upon exposure to genotoxic stress, DYRK2 translocates into the nucleus and phosphorylates p53 at Ser-46, thereby inducing apoptosis. However, less is known about mechanisms responsible for intracellular control of DYRK2. Here we show the functional nuclear localization signal at N-terminal domain of DYRK2. Under normal conditions, nuclear and not cytoplasmic DYRK2 is ubiquitinated by MDM2, resulting in its constitutive degradation. In the presence of proteasome inhibitors, we detected a stable complex of DYRK2 with MDM2 at the nucleus. Upon exposure to genotoxic stress, ATM phosphorylates DYRK2 at Thr-33 and Ser-369, which enables DYRK2 to escape from degradation by dissociation from MDM2 and to induce the kinase activity toward p53 at Ser-46 in the nucleus. These findings indicate that ATM controls stability and pro-apoptotic function of DYRK2 in response to DNA damage.
肿瘤抑制因子 p53 是一种转录因子，可响应 DNA 损伤调节细胞周期、DNA 修复、衰老和细胞凋亡。p53 在丝氨酸 46 位的磷酸化对于细胞凋亡的启动是必不可少的。先前的研究表明，在暴露于遗传毒性应激下，DYRK2 易位到细胞核并磷酸化 p53 的丝氨酸 46 位，从而诱导细胞凋亡。然而，对于负责 DYRK2 细胞内控制的机制知之甚少。在这里，我们展示了 DYRK2 氨基端结构域的功能性核定位信号。在正常情况下，核内而非细胞质内的 DYRK2 被 MDM2 泛素化，导致其持续降解。在蛋白酶体抑制剂存在的情况下，我们在细胞核中检测到 DYRK2 与 MDM2 的稳定复合物。在暴露于遗传毒性应激下，ATM 在 Thr-33 和 Ser-369 位点磷酸化 DYRK2，使 DYRK2 能够通过与 MDM2 解离而免于降解，并在细胞核中诱导激酶活性使 p53 的丝氨酸 46 位磷酸化。这些发现表明 ATM 控制 DYRK2 的稳定性和促凋亡功能，以响应 DNA 损伤。
