Guo Xing, Wang Xiaorong, Wang Zhiping, Banerjee Sourav, Yang Jing, Huang Lan, Dixon Jack E
Department of Pharmacology, University of California-San Diego, La Jolla, California 92093, USA.
Departments of Physiology and Biophysics and of Developmental and Cell Biology, University of California, Irvine, California 92697, USA.
Nat Cell Biol. 2016 Feb;18(2):202-12. doi: 10.1038/ncb3289. Epub 2015 Dec 14.
Despite the fundamental importance of proteasomal degradation in cells, little is known about whether and how the 26S proteasome itself is regulated in coordination with various physiological processes. Here we show that the proteasome is dynamically phosphorylated during the cell cycle at Thr 25 of the 19S subunit Rpt3. CRISPR/Cas9-mediated genome editing, RNA interference and biochemical studies demonstrate that blocking Rpt3-Thr25 phosphorylation markedly impairs proteasome activity and impedes cell proliferation. Through a kinome-wide screen, we have identified dual-specificity tyrosine-regulated kinase 2 (DYRK2) as the primary kinase that phosphorylates Rpt3-Thr25, leading to enhanced substrate translocation and degradation. Importantly, loss of the single phosphorylation of Rpt3-Thr25 or knockout of DYRK2 significantly inhibits tumour formation by proteasome-addicted human breast cancer cells in mice. These findings define an important mechanism for proteasome regulation and demonstrate the biological significance of proteasome phosphorylation in regulating cell proliferation and tumorigenesis.
尽管蛋白酶体降解在细胞中具有根本重要性，但对于26S蛋白酶体本身是否以及如何与各种生理过程协调调节，人们了解甚少。在这里，我们表明蛋白酶体在细胞周期中于19S亚基Rpt3的苏氨酸25处发生动态磷酸化。CRISPR/Cas9介导的基因组编辑、RNA干扰和生化研究表明，阻断Rpt3-苏氨酸25磷酸化会显著损害蛋白酶体活性并阻碍细胞增殖。通过全激酶组筛选，我们确定双特异性酪氨酸调节激酶2（DYRK2）为使Rpt3-苏氨酸25磷酸化的主要激酶，从而导致底物转运和降解增强。重要的是，Rpt3-苏氨酸25的单磷酸化缺失或DYRK2基因敲除显著抑制蛋白酶体依赖的人乳腺癌细胞在小鼠体内的肿瘤形成。这些发现定义了蛋白酶体调节的一种重要机制，并证明了蛋白酶体磷酸化在调节细胞增殖和肿瘤发生中的生物学意义。
