M2型丙酮酸激酶（M2 pyruvate kinase，PKM2）是导致肿瘤细胞发生Warburg效应的关键因子。越来越多的证据表明高表达的PKM2通过重新编译代谢进程及调节信号转导过程促进肿瘤细胞的增殖。高丙酮酸激酶活性的四聚体PKM2具有代谢调节作用；而二聚体PKM2作为转录共因子，或蛋白激酶发挥非代谢调节作用。最近，本课题组利用相互作用蛋白质组学技术，发现在DNA损伤的过程中，PKM2可以和一系列DNA损伤相关蛋白形成复合体。进一步研究发现，核内PKM2可以直接磷酸化组蛋白2的139位丝氨酸位点，从而提示了PKM2作为蛋白激酶在应对DNA损伤中的新功能。基于上述重要发现，本项目试图利用定量磷酸化蛋白质组学技术，高通量的识别在不同刺激因素作用下非经典蛋白激酶-PKM2的特异磷酸化底物，以期从一个全新的角度为深入研究PKM2在肿瘤发生发展的作用机制提供重要线索，推动新的学科生长点的形成。

PKM2 (M2 pyruvate kinase) is a critical factor that contributes to aerobic glycolysis (Warburg effect). Increasing evidence demonstrates that aberrated expression of PKM2 is involved in reprogramming metabolic process and promoting tumor cell proliferation. PKM2 undergoes conformational conversion between tetramer and dimer. The tetrameric form possesses high pyruvate kinase activity and plays a crucial metabolic role in shifting glucose metabolism in favor of growth of cancer cells. In contrast, the dimeric form of PKM2 contributes to tumorigenesis in a "non-metabolic" way. It acts as a transcriptional co-factor to regulate gene transcription, or functions as a protein kinase to directly phosphorylate substrates involved in different signaling pathways. Recently, using protein-protein interaction proteomics to study the role of PKM2 in response to DNA damage, we found that PKM2 forms complex with some proteins related to DNA damage response (DDR). Moreover, we showed that PKM2 acts as a protein kinase to promote DNA damage signaling by directly binding and phohsphorylating histone H2AX at serine 139 in the nucleus. These findings reveal the new role of PKM2 in DDR. Based on these original findings, we plan to systematically identify substrates phosphorylated by non-canonical protein kinase-M2 pyruvate kinase in response to different stimuli using quantitative phosphoproteomics. These studies will shed new insights for the mechanism by which PKM2 modulates tumorigenicity and malignancy.