Structural Studies of the Tumor M2 Isoform of Pyruvate Kinase

癌细胞维持着一种改变的代谢状态，这种状态显著增加了 营养物质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。一个 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主要以二聚体的形式被发现，并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。击倒PKM2或 用成年的PKM1亚型替代已经被证明可以减少癌细胞的增殖，使 PKM2是更好地了解癌症的发展、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与嘌呤类化合物SAICAR结合并受其刺激 生物合成中间体，这种相互作用对于营养贫乏的癌细胞的生存是重要的 环境。PKM2还被证明与含有磷酸酪氨酸的蛋白质结合，这种蛋白质 将PKM2稳定在二聚体状态。有趣的是，PKM2的这种二聚态已经被证明具有 蛋白激酶活性，通过磷酸化靶标诱导转录程序改变，如 组蛋白H1和H3、胸腺素原和STAT3。 这一建议旨在揭示PKM2调控和底物特异性的结构基础。 我们将使用X射线晶体学来捕获与SAICAR和磷酸化靶标形成的复合体中的PKM2 揭示这些配体如何通过变构作用影响PKM2的结构和功能。这样做的结果 研究将有助于为理解PKM2如何参与刺激提供一个结构框架 正常细胞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.