背景:人己糖激酶2(HK2)在调节Warburg效应中起重要作用,即使在充足的氧气存在下,它也能将葡萄糖代谢为乳酸,并提供中间代谢物以支持癌细胞增殖和肿瘤生长。已经在各种类型的癌症中观察到HK2过表达,并且已经提出靶向HK2驱动的Warburg效应作为潜在的癌症治疗策略。鉴于表观遗传酶利用代谢中间体作为底物或辅因子进行细胞中组蛋白和核酸修饰的翻译后修饰,我们假设改变HK2表达可能会影响表观基因组,因此,染色质在酵母中的稳定性。为了检验这个假设,我们建立了酿酒酵母酵母细胞中不同酵母己糖激酶2(HXK2)表达的遗传模型,并研究了HXK2依赖性代谢对亲本核小体转移的影响,一个关键的DNA复制耦合表观遗传过程,和染色质稳定性。
结果:通过比较携带hxk1Δ单个缺失的突变酵母细胞的生长,hxk2Δ,或野生型细胞双损失hxk1Δhxk2Δ,我们首先证实HXK2是酵母细胞生长中的优势HXK。令人惊讶的是,在酵母中操纵XK2表达,无论是通过过表达还是缺失,对亲本核小体组装只有边际影响,但染色质不稳定性降低的趋势明显。然而,用2-脱氧-D-葡萄糖(2-DG)靶向酵母细胞,一种被提议作为抗癌治疗的临床糖酵解抑制剂,显著增加染色质不稳定性。
结论:我们的发现表明,在缺乏HXK2的酵母细胞中,替代的HXKs如HXK1或葡萄糖激酶1(GLK1)在足够维持表观基因组稳定性的水平上支持糖酵解。虽然我们的研究表明2-DG治疗的表观遗传不稳定性增加,观察到的效果似乎取决于Hxk2的非糖酵解功能。因此,需要进一步的研究来确定2-DG影响染色质稳定性的分子机制。
BACKGROUND: Human hexokinase 2 (HK2) plays an important role in regulating Warburg effect, which metabolizes glucose to lactate acid even in the presence of ample oxygen and provides intermediate metabolites to support cancer cell proliferation and tumor growth. HK2 overexpression has been observed in various types of cancers and targeting HK2-driven Warburg effect has been suggested as a potential cancer therapeutic strategy. Given that epigenetic enzymes utilize metabolic intermediates as substrates or co-factors to carry out post-translational modification of histones and nucleic acids modifications in cells, we hypothesized that altering HK2 expression could impact the epigenome and, consequently, chromatin stability in yeast. To test this hypothesis, we established genetic models with different yeast hexokinase 2 (HXK2) expression in Saccharomyces cerevisiae yeast cells and investigated the effect of HXK2-dependent metabolism on parental nucleosome transfer, a key DNA replication-coupled epigenetic inheritance process, and chromatin stability.
RESULTS: By comparing the growth of mutant yeast cells carrying single deletion of hxk1Δ, hxk2Δ, or double-loss of hxk1Δ hxk2Δ to wild-type cells, we firstly confirmed that HXK2 is the dominant HXK in yeast cell growth. Surprisingly, manipulating HXK2 expression in yeast, whether through overexpression or deletion, had only a marginal impact on parental nucleosome assembly, but a noticeable trend with decrease chromatin instability. However, targeting yeast cells with 2-deoxy-D-glucose (2-DG), a clinical glycolysis inhibitor that has been proposed as an anti-cancer treatment, significantly increased chromatin instability.
CONCLUSIONS: Our findings suggest that in yeast cells lacking HXK2, alternative HXKs such as HXK1 or glucokinase 1 (GLK1) play a role in supporting glycolysis at a level that adequately maintains epigenomic stability. While our study demonstrated an increase in epigenetic instability with 2-DG treatment, the observed effect seemed to occur dependent on non-glycolytic function of Hxk2. Thus, additional research is needed to identify the molecular mechanism through which 2-DG influences chromatin stability.