Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona (UB), 08028 Barcelona, Spain.
Institute of Biomedicine of University of Barcelona (IBUB), University of Barcelona (UB), 08028 Barcelona, Spain.
Int J Mol Sci. 2022 Mar 25;23(7):3574. doi: 10.3390/ijms23073574.
Increased expression of transketolase (TKT) and its isoform transketolase-like-1 (TKTL1) has been related to the malignant leukemia phenotype through promoting an increase in the non-oxidative branch of the pentose phosphate pathway (PPP). Recently, it has also been described that TKTL1 can have a role in survival under hypoxic conditions and in the acquisition of radio resistance. However, TKTL1's role in triggering metabolic reprogramming under hypoxia in leukemia cells has never been characterized. Using THP-1 AML cells, and by combining metabolomics and transcriptomics techniques, we characterized the impact of TKTL1 knockdown on the metabolic reprogramming triggered by hypoxia. Results demonstrated that TKTL1 knockdown results in a decrease in TKT, glucose-6-phosphate dehydrogenase (G6PD) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activities and impairs the hypoxia-induced overexpression of G6PD and GAPDH, all having significant impacts on the redox capacity of NADPH- and NADH-related cells. Moreover, TKTL1 knockdown impedes hypoxia-induced transcription of genes encoding key enzymes and transporters involved in glucose, PPP and amino acid metabolism, rendering cells unable to switch to enhanced glycolysis under hypoxia. Altogether, our results show that TKTL1 plays a key role in the metabolic adaptation to hypoxia in THP-1 AML cells through modulation of G6PD and GAPDH activities, both regulating glucose/glutamine consumption and the transcriptomic overexpression of key players of PPP, glucose and amino acids metabolism.
转酮醇酶（TKT）及其同工酶转酮醇酶样-1（TKTL1）的表达增加与恶性白血病表型有关，通过促进戊糖磷酸途径（PPP）的非氧化分支增加。最近，也有人描述说，TKTL1 在缺氧条件下的生存和获得放射抗性方面可能具有作用。然而，TKTL1 在白血病细胞缺氧下触发代谢重编程的作用从未被描述过。使用 THP-1 AML 细胞，并结合代谢组学和转录组学技术，我们描述了 TKTL1 敲低对缺氧触发的代谢重编程的影响。结果表明，TKTL1 敲低导致 TKT、葡萄糖-6-磷酸脱氢酶（G6PD）和甘油醛-3-磷酸脱氢酶（GAPDH）活性降低，并损害缺氧诱导的 G6PD 和 GAPDH 过表达，这对 NADPH 和 NADH 相关细胞的还原能力有重大影响。此外，TKTL1 敲低阻碍了缺氧诱导的编码参与葡萄糖、PPP 和氨基酸代谢的关键酶和转运体的基因转录，使细胞无法在缺氧下切换到增强的糖酵解。总之，我们的结果表明，TKTL1 通过调节 G6PD 和 GAPDH 的活性，在 THP-1 AML 细胞对缺氧的代谢适应中发挥关键作用，这两种酶都调节葡萄糖/谷氨酰胺的消耗和 PPP、葡萄糖和氨基酸代谢的关键参与者的转录组过表达。
