PGK1在肿瘤自噬中的作用及机制研究

Autophagy is often upregulated in cancer cells to support their metabolism, growth, and survival. The Beclin1/VPS34 complex plays a central role in the initiation of autophagosome formation. However, the precise regulation of Beclin1/VPS34 complex activity remains unclear. Our preliminary data revealed that nutrient glutamine deprivation-induced Beclin1/VPS34 activation and autophagy were blocked by the depletion of PGK1, which is a glycolytic enzyme. Of note, glutamine deprivation resulted in PGK1 acetylation, which led to the binding of PGK1 to the Beclin1/VPS34/ATG14L complex. Importantly, PGK1 directly interacted with and phosphorylated Beclin1. We hypothesize that PGK1 functions as a protein kinase and plays a critical role in the initiation of autophagy by activating the Beclin1/VPS34 complex. We will test our hypothesis with the following specific aims:（1）To determine the role of PGK1 acetylation in autophagy regulation. To determine the role of PGK1-dependent Beclin1 phosphorylation in （2）autophagy regulation and（3） tumor cell proliferation and brain tumorigenesis. The proposed research is significant because it could lead to pharmaceutical approaches to interrupt tumor growth by blocking PGK1-dependent autophagy and this would, in turn, improve the efficacy of human cancer treatment.

癌细胞经常通过上调自噬来支持细胞的代谢，生长和存活。Beclin1/VPS34复合物在自噬体形成初始具有关键作用。然而，调节此复合物活性的具体机制尚不清楚。我们前期研究表明，谷氨酰胺缺乏诱导Beclin1/VPS34激活和自噬，这一过程能被糖酵解酶PGK1敲减所拮抗。重要的是，谷氨酰胺缺乏导致PGK1乙酰化，促使PGK1结合到Beclin1/VPS34/ATG14L复合物上。PGK1直接作用并且磷酸化Beclin1。因此，我们提出假说：PGK1作为蛋白激酶激活Beclin1/VPS34复合物，从而在自噬体形成初始具有重要作用。要验证这一假说，我们提出以下目标：（1）明确PGK1乙酰化在调节自噬当中的作用。明确PGK1介导的Beclin1磷酸化在（2）调节自噬和（3）肿瘤细胞增殖及脑肿瘤形成中的作用。这项研究有助于开发抗肿瘤药物，通过阻断依赖PGK1的自噬干扰肿瘤生长，从而有助于肿瘤治疗。

自噬是维持细胞内稳态的关键。然而，自噬启动的确切机制仍有待确定。在这里，我们证明谷氨酰胺缺乏和缺氧导致mTOR介导的乙酰基转移酶ARD1 S228磷酸化的抑制，导致依赖ARD1的磷酸甘油酸激酶1(PGK1) K388乙酰化，随后PGK1介导的Beclin1 S30磷酸化。 这种磷酸化通过增加磷脂酰肌醇与VPS34的结合，增强ATG14L相关的Ⅲ类磷脂酰肌醇3-激酶VPS34的活性。我们还发现，依赖ARD1的PGK1乙酰化及其介导的PGK1 Beclin1S30磷酸化是谷氨酰胺剥夺和缺氧诱导的自噬和脑肿瘤发生所必需的。此外，胶质母细胞瘤患者PGK1 K388乙酰化水平与Beclin1 S30磷酸化水平及预后不良相关。我们的研究揭示了代谢酶PGK1的蛋白激酶活性在细胞应激诱导自噬启动中起着重要作用，并揭示了自噬和细胞代谢相互调节在维持细胞内稳态中的重要意义。.这些研究主要由负责人主持的国自然面上基金 (PGK1在肿瘤自噬中的作用及机制研究，81672710) 支持，成果以申请人作为第五作者以article发表在国际知名杂志Molecular Cell。.另外，本项目还支持申请人另一个关于代谢酶Fumarase的O-GlcNAcylation糖基化在葡萄糖缺乏的肿瘤微环境下维持肿瘤生长机制的研究，申请者作为共同第一作者以article发表在国际知名杂志 Nature Cell Biology。