Ivanov A A, Gonzalez-Pecchi V, Khuri L F, Niu Q, Wang Y, Xu Y, Bai Y, Mo X, Prochownik E V, Johns M A, Du Y, Khuri F R, Fu H
Department of Pharmacology and Emory Chemical Biology Discovery Center, Emory University, Atlanta, GA, USA.
Section of Hematology/Oncology, Children's Hospital of Pittsburgh of UPMC and The University of Pittsburgh Cancer Institute, Pittsburg, PA, USA.
Oncogene. 2017 Oct 19;36(42):5852-5860. doi: 10.1038/onc.2017.180. Epub 2017 Jun 19.
Mitogen-activated protein kinase kinase 3 (MKK3) is a dual threonine/tyrosine protein kinase that regulates inflammation, proliferation and apoptosis through specific phosphorylation and activation of the p38 mitogen-activated protein kinase. However, the role of MKK3 beyond p38-signaling remains elusive. Recently, we reported a protein-protein interaction (PPI) network of cancer-associated genes, termed OncoPPi, as a resource for the scientific community to generate new biological models. Analysis of the OncoPPi connectivity identified MKK3 as one of the major hub proteins in the network. Here, we show that MKK3 interacts with a large number of proteins critical for cell growth and metabolism, including the major oncogenic driver MYC. Multiple complementary approaches were used to demonstrate the direct interaction of MKK3 with MYC in vitro and in vivo. Computational modeling and experimental studies mapped the interaction interface to the MYC helix-loop-helix domain and a novel 15-residue MYC-binding motif in MKK3 (MBM). The MBM in MKK3 is distinct from the known binding sites for p38 or upstream kinases. Functionally, MKK3 stabilized MYC protein, enhanced its transcriptional activity and increased expression of MYC-regulated genes. The defined MBM peptide mimicked the MKK3 effect in promoting MYC activity. Together, the exploration of OncoPPi led to a new biological model in which MKK3 operates by two distinct mechanisms in cellular regulation through its phosphorylation of p38 and its activation of MYC through PPI.
丝裂原活化蛋白激酶激酶3（MKK3）是一种双特异性苏氨酸/酪氨酸蛋白激酶，它通过对p38丝裂原活化蛋白激酶的特异性磷酸化和激活来调节炎症、增殖和细胞凋亡。然而，MKK3在p38信号通路之外的作用仍不清楚。最近，我们报道了一个癌症相关基因的蛋白质-蛋白质相互作用（PPI）网络，称为OncoPPi，作为科学界生成新生物模型的资源。对OncoPPi连通性的分析确定MKK3是该网络中的主要枢纽蛋白之一。在这里，我们表明MKK3与大量对细胞生长和代谢至关重要的蛋白质相互作用，包括主要的致癌驱动因子MYC。我们使用了多种互补方法来证明MKK3与MYC在体外和体内的直接相互作用。计算建模和实验研究将相互作用界面定位到MYC的螺旋-环-螺旋结构域和MKK3中一个新的15个残基的MYC结合基序（MBM）。MKK3中的MBM与已知的p38或上游激酶的结合位点不同。在功能上，MKK3稳定了MYC蛋白，增强了其转录活性，并增加了MYC调控基因的表达。确定的MBM肽模拟了MKK3在促进MYC活性方面的作用。总之，对OncoPPi的探索导致了一种新的生物模型，其中MKK3通过其对p38的磷酸化和通过PPI对MYC的激活，在细胞调节中通过两种不同的机制发挥作用。
