Department of Bioengineering, Institute of Engineering in Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0435, United States.
ACS Sens. 2021 Dec 24;6(12):4369-4378. doi: 10.1021/acssensors.1c01670. Epub 2021 Dec 8.
Histone methylations play a crucial role in chromatin remodeling and genome regulations. However, there is a lack of tools to visualize these histone modifications with high spatiotemporal resolutions in live cells. We have developed a biosensor based on fluorescence resonance energy transfer (FRET) and incorporated it into nucleosomes, capable of monitoring the trimethylation of H3K27 (H3K27me3) in live cells. We also revealed that the performance of the FRET biosensor can be significantly improved by adjusting the linkers within the biosensor. An improved biosensor enables the live-cell imaging of different histone methylation status, induced by the suppressive H3.3K27M or existing in breast cancer cells with varying genetic backgrounds. We have further applied the biosensor to reveal the dynamic coupling between H3K27me3 changes and caspase activity representing the initiation of apoptosis in cancer cells by imaging both H3K27me3 and caspase activity simultaneously in the same live cells. Thus, this new FRET biosensor can provide a powerful tool to visualize the epigenetic regulation in live cells with high spatial temporal resolutions.
组蛋白甲基化在染色质重塑和基因组调控中起着至关重要的作用。然而，目前缺乏能够在活细胞中以高时空分辨率可视化这些组蛋白修饰的工具。我们开发了一种基于荧光共振能量转移（FRET）的生物传感器，并将其整合到核小体中，能够监测活细胞中 H3K27 的三甲基化（H3K27me3）。我们还揭示了通过调整生物传感器内的连接子，可以显著提高 FRET 生物传感器的性能。改进后的生物传感器能够对由抑制性 H3.3K27M 诱导或存在于具有不同遗传背景的乳腺癌细胞中的不同组蛋白甲基化状态进行活细胞成像。我们进一步将该生物传感器应用于揭示 H3K27me3 变化与 caspase 活性之间的动态偶联，通过同时在同一活细胞中对 H3K27me3 和 caspase 活性进行成像，揭示了 caspase 活性代表癌细胞凋亡的起始。因此，这种新的 FRET 生物传感器可以为以高时空分辨率可视化活细胞中的表观遗传调控提供有力工具。
