The cysteine residue at 424th of pyruvate kinase M2 is crucial for tetramerization and responsiveness to oxidative stress
The cysteine residue at 424th of pyruvate kinase M2 is crucial for tetramerization and responsiveness to oxidative stress
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DOI：
10.1016/j.bbrc.2020.03.182
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发表时间：
2020-06-11
影响因子：
3.1
通讯作者：
Suzuki, Kenji
中科院分区：
文献类型：
--
作者：
Masaki, So;Hashimoto, Kozue;Suzuki, Kenji
丙酮酸激酶 M (PKM) 前体 mRNA 的选择性剪接产生两种亚型：PKM1 和 PKM2。 PKM 在糖酵解途径中催化磷酸烯醇丙酮酸转化为丙酮酸。 PKM1以稳定的四聚体形式存在，处于活性酶状态，而PKM2在其变构激活剂的调节下处于单体、二聚体和四聚体之间的平衡。尽管有氧气可用，许多癌细胞仍表现出较高的葡萄糖摄取和乳酸产生的特征，这被称为瓦尔堡效应。 PKM2 在大多数癌症类型中表达上调，失活的 PKM2 会导致癌症代谢。此外，二聚体 PKM2 通过翻译后修饰诱导其核转位，并充当癌基因表达的转录共激活因子。因此，阐明 PKM2 活性或非活性状态的调节机制（即四聚体到二聚体转变）非常重要。 PKM1 和 PKM2 之间的决定性区别在于是否在细胞质中组成型形成四聚体，这归因于源自外显子 9 (PKM1) 或外显子 10 (PKM2) 的 22 个氨基酸。在本研究中，我们生成了 22 个不同的 PKM2 的 PKM1 模拟点突变体，并证明用 PKM1 (C424L) 中保守的亮氨酸 424 替换 PKM2 的半胱氨酸 424 残基可促进其四聚化。 PKM2(C424L)在没有变构激活剂的情况下形成四聚体，并且像PKM1一样逃脱氧化应激的抑制作用。我们的研究结果强烈表明，C424 或 L424 决定了 PKM 剪接异构体之间不同的催化和调节特性。 (C) 2020 Elsevier Inc. 保留所有权利。
Alternative splicing of the pyruvate kinase M (PKM) pre-mRNA generates two isoforms, PKM1 and PKM2. PKM catalyzes the conversion of phosphoenol-pyruvate to pyruvate in glycolytic pathway. PKM1 exist as a stable tetramer that is at an active enzyme state, while PKM2 is in equilibrium among monomer, dimer and tetramer under the regulation of its allosteric activators. Many cancer cells show the feature of higher glucose uptake and lactate production in spite of oxygen availability, which is known as the Warburg effect. PKM2 is upregulated in most cancer types and the inactive PKM2 lead to the cancer metabolism. In addition, dimeric PKM2 induces its nuclear translocation through posttranslational modification and acts as a transcriptional co-activator for the expression of oncogenes. Therefore, it is important to elucidate mechanisms for modulation of an active or inactive state of PKM2, namely the tetramer-to-dimer-transition. The definitive difference between PKM1 and PKM2 is to constitutively form tetramer or not in the cytoplasm, which is ascribed to 22 amino acids derived from exon 9 (PKM1) or exon 10 (PKM2). In this study, we generated 22 different PKM1-mimetic point mutants of PKM2, and demonstrated that replacement of cysteine424 residue of PKM2 with leucine424 conserved in PKM1 (C424L) promote its tetramerization. PKM2(C424L) formed a tetramer without allosteric activator, and escaped the inhibitory effects by oxidative stress, like PKM1. Our findings intensely suggest that C424 or L424 determines the different catalytic and modulatory properties between PKM splicing isoforms. (C) 2020 Elsevier Inc. All rights reserved.