Kuo Hsu-Ping, Lee Dung-Fang, Xia Weiya, Lai Chien-Chen, Li Long-Yuan, Hung Mien-Chie
Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Biochem Biophys Res Commun. 2009 Nov 6;389(1):156-61. doi: 10.1016/j.bbrc.2009.08.127. Epub 2009 Aug 28.
IkappaB kinase beta (IKKbeta), a major kinase downstream of various proinflammatory signals, mediates multiple cellular functions through phosphorylation and regulation of its substrates. On the basis of protein sequence analysis, we identified arrest-defective protein 1 (ARD1), a protein involved in apoptosis and cell proliferation processes in many human cancer cells, as a new IKKbeta substrate. We provided evidence showing that ARD1 is indeed a bona fide substrate of IKKbeta. IKKbeta physically associated with ARD1 and phosphorylated it at Ser209. Phosphorylation by IKKbeta destabilized ARD1 and induced its proteasome-mediated degradation. Impaired growth suppression was observed in ARD1 phosphorylation-mimic mutant (S209E)-transfected cells as compared with ARD1 non-phosphorylatable mutant (S209A)-transfected cells. Our findings of molecular interactions between ARD1 and IKKbeta may enable further understanding of the upstream regulation mechanisms of ARD1 and of the diverse functions of IKKbeta.
IκB激酶β（IKKβ）是多种促炎信号下游的主要激酶，通过对其底物的磷酸化和调控介导多种细胞功能。基于蛋白质序列分析，我们鉴定出阻滞缺陷蛋白1（ARD1）是一种新的IKKβ底物，ARD1参与多种人类癌细胞的凋亡和细胞增殖过程。我们提供的证据表明，ARD1确实是IKKβ的真正底物。IKKβ与ARD1发生物理结合，并在Ser209位点使其磷酸化。IKKβ介导的磷酸化使ARD1不稳定，并诱导其通过蛋白酶体介导的降解。与转染ARD1非磷酸化突变体（S209A）的细胞相比，在转染ARD1磷酸化模拟突变体（S209E）的细胞中观察到生长抑制受损。我们对ARD1与IKKβ之间分子相互作用的研究结果可能有助于进一步了解ARD1的上游调控机制以及IKKβ的多种功能。
