Structural Studies of the Tumor M2 Isoform of Pyruvate Kinase

癌细胞保持一种改变的代谢状态， 营养素转化为合成细胞构建块，这是细胞快速生长和分裂所必需的。一 这种增殖代谢所需的关键酶是丙酮酸激酶的M2亚型，称为PKM2。 PKM2主要以二聚体形式存在，在多种癌症类型中高度表达， 表达水平与肿瘤侵袭性之间存在明显的相关性。PKM2的敲除或 已显示用成人PKM1同种型取代可减少癌细胞增殖， PKM2是更好地了解癌症发展、诊断和治疗的重要靶点。 最近的工作揭示了PKM2的新的和意想不到的活动和相互作用， 对促进细胞增殖很重要。PKM2与SAICAR结合并受其刺激，SAICAR是一种嘌呤 生物合成中间体，这种相互作用对于癌细胞在营养不良环境中的存活是重要的。 环境. PKM2也被证明与含磷酸酪氨酸的蛋白质结合， 稳定二聚体状态PKM2。有趣的是，PKM2的这种二聚体状态已被证明具有 蛋白激酶活性，通过磷酸化靶点，如 组蛋白H1和H3、胸腺素原和STAT3。 该提案旨在揭示PKM2调节和底物特异性的结构基础。 我们将使用X射线晶体学来捕获PKM2与SAICAR和磷酸化靶点的复合物 揭示这些配体如何变构影响PKM2的结构和功能。的结果 研究将有助于提供一个结构框架，了解PKM2如何参与刺激 正常和病变细胞中的细胞增殖。

Cancerous cells maintain an altered metabolic state that dramatically increases the flux of nutrients into synthesizing cellular building blocks, which is essential for rapid cell growth and division. A key enzyme required for this proliferative metabolism is the M2 isoform of pyruvate kinase, called PKM2. PKM2 is found predominantly as a dimer and highly expressed in a multitude of cancer types, with a clear correlation between expression levels and tumor aggressiveness. Knock-down of PKM2 or substitution with the adult PKM1 isoform has been shown to reduce cancer cell proliferation, making PKM2 an important target for better understanding the development, diagnosis, and treatment of cancer. Recent work has revealed new and unexpected activities and interactions of PKM2 that are important for promoting cell proliferation. PKM2 binds to and is stimulated by SAICAR, a purine biosynthesis intermediate, and this interaction is important for cancer cell survival in nutrient-poor environments. PKM2 has also been shown to bind to phosphotyrosine-containing proteins, which stabilize PKM2 in a dimeric state. Interestingly, this dimeric state of PKM2 has been shown to have protein kinase activity, inducing altered transcriptional programs by phosphorylating targets such as histone H1 and H3, prothymosin ¿, and STAT3. This proposal aims to uncover the structural basis of PKM2 regulation and substrate specificity. We will use X-ray crystallography to capture PKM2 in complex with SAICAR and phosphorylation targets to reveal how these ligands allosterically influence PKM2 structure and function. The results of this research will help provide a structural framework for understanding how PKM2 participates in stimulating cell proliferation in normal and diseased cells.