Department of Bioengineering, University of Illinois at Urbana-Champaign, 1102 Everitt Lab, 1406 W. Green Street, Urbana, Illinois 61801, United States.
Biomedical Research Center, Mills Breast Cancer Institute, Cancer Center at Illinois, Micro and Nanotechnology Laboratory, Beckman Institute, Carl Woese Institute for Genomic Biology, Urbana, Illinois 61801, United States.
ACS Nano. 2022 Jul 26;16(7):10754-10767. doi: 10.1021/acsnano.2c02660. Epub 2022 Jul 8.
The cancer cell nucleus deforms as it invades the interstitial spaces in tissues and the tumor microenvironment. While alteration of the chromatin structure in a deformed nucleus is expected and documented, the chromatin structure in the nuclei of cells on aligned matrices has not been elucidated. In this work we elucidate the spatiotemporal organization of heterochromatin in the elongated nuclei of cells on aligned nanofibers with stimulated emission depletion nanoscopy and fluorescence correlation spectroscopy. We show that the anisotropy of nuclei is sufficient to drive H3K9me3-heterochromatin alterations, with enhanced H3K9me3 nanocluster compaction and aggregation states that otherwise are indistinguishable from diffraction-limited microscopy. We interrogated the higher-order heterochromatin structures within major chromatin compartments in anisotropic nuclei and discovered a wider spatial dispersion of nanodomain clusters in the nucleoplasm and condensed larger nanoclusters near the periphery and pericentromeric heterochromatin. Upon examining the spatiotemporal dynamics of heterochromatin in anisotropic nuclei, we observed reduced mobility of the constitutive heterochromatin mark H3K9me3 and the associated heterochromatin protein 1 (HP1α) at the nucleoplasm and periphery regions, correlating with increased viscosity and changes in gene expression. Since heterochromatin remodeling is crucial to genome integrity, our results reveal an unconventional H3K9me3 heterochromatin distribution, providing cues to an altered chromatin state due to perturbations of the nuclei in aligned fiber configurations.
癌细胞核在侵袭组织间隙和肿瘤微环境时会发生变形。虽然已预期并记录了变形核中染色质结构的改变，但排列在基质上的细胞核中的染色质结构尚未阐明。在这项工作中，我们使用受激发射损耗纳米显微镜和荧光相关光谱法阐明了排列在纳米纤维上的细胞的拉长核中异染色质的时空组织。我们表明，核的各向异性足以驱动 H3K9me3-异染色质改变，增强了 H3K9me3 纳米团簇的紧凑性和聚集状态，否则与衍射极限显微镜无法区分。我们在各向异性核中的主要染色质隔室中检测了更高阶的异染色质结构，并发现核质中纳米域簇的空间分布更广泛，而在核周和着丝粒异染色质附近则有较大的凝聚纳米簇。在研究各向异性核中异染色质的时空动力学时，我们观察到组成型异染色质标记 H3K9me3 及其相关异染色质蛋白 1（HP1α）在核质和核周区域的流动性降低，这与粘度增加和基因表达变化相关。由于异染色质重塑对于基因组完整性至关重要，因此我们的结果揭示了一种非常规的 H3K9me3 异染色质分布，这为由于核在排列纤维结构中的扰动而导致的染色质状态改变提供了线索。
