a Centre for DNA Fingerprinting and Diagnostics , Survey Nos. 728, 729, 730 & 734, Opposite Uppal Water Tank, Beside BSNL T E Building, Uppal, Hyderabad 500039 , Ranga Reddy District , India.
b Graduate Studies , Manipal University , Manipal , India.
Cell Cycle. 2018;17(1):110-123. doi: 10.1080/15384101.2017.1404207. Epub 2018 Jan 8.
Metabolic reprogramming is a hallmark of cancer cells, but the mechanisms are not well understood. The mammalian target of rapamycin complex 2 (mTORC2) controls cell growth and proliferation and plays a critical role in metabolic reprogramming in glioma. mTORC2 regulates cellular processes such as cell survival, metabolism, and proliferation by phosphorylation of AGC kinases. Components of mTORC2 are shown to localize to the nucleus, but whether mTORC2 modulates epigenetic modifications to regulate gene expression is not known. Here, we identified histone H3 lysine 56 acetylation (H3K56Ac) is regulated by mTORC2 and show that global H3K56Ac levels were downregulated on mTORC2 knockdown but not on mTORC1 knockdown. mTORC2 promotes H3K56Ac in a tuberous sclerosis complex 1/2 (TSC1/2) mediated signaling pathway. We show that knockdown of sirtuin6 (SIRT6) prevented H3K56 deacetylation in mTORC2 depleted cells. Using glioma model consisting of U87EGFRvIII cells, we established that mTORC2 promotes H3K56Ac in glioma. Finally, we show that mTORC2 regulates the expression of glycolytic genes by regulating H3K56Ac levels at the promoters of these genes in glioma cells and depletion of mTOR leads to increased recruitment of SIRT6 to these promoters. Collectively, these results identify mTORC2 signaling pathway positively promotes H3K56Ac through which it may mediate metabolic reprogramming in glioma.
代谢重编程是癌细胞的一个标志,但机制尚不清楚。雷帕霉素哺乳动物靶标复合物 2(mTORC2)控制细胞生长和增殖,在神经胶质瘤的代谢重编程中发挥关键作用。mTORC2 通过磷酸化 AGC 激酶来调节细胞存活、代谢和增殖等细胞过程。mTORC2 的成分被证明定位于细胞核,但 mTORC2 是否调节表观遗传修饰来调节基因表达尚不清楚。在这里,我们确定组蛋白 H3 赖氨酸 56 乙酰化(H3K56Ac)受 mTORC2 调节,并表明 mTORC2 敲低而非 mTORC1 敲低下调了全局 H3K56Ac 水平。mTORC2 通过结节性硬化复合物 1/2(TSC1/2)介导的信号通路促进 H3K56Ac。我们表明,沉默 6 号沉默调节蛋白(SIRT6)可防止 mTORC2 耗竭细胞中的 H3K56 去乙酰化。使用包含 U87EGFRvIII 细胞的神经胶质瘤模型,我们确定 mTORC2 在神经胶质瘤中促进 H3K56Ac。最后,我们表明 mTORC2 通过调节这些基因启动子上的 H3K56Ac 水平来调节糖酵解基因的表达,并且 mTOR 的耗竭导致 SIRT6 更大量地募集到这些启动子。总之,这些结果表明 mTORC2 信号通路通过调节这些基因启动子上的 H3K56Ac 水平正向促进 H3K56Ac,从而可能介导神经胶质瘤中的代谢重编程。