Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
Department of Immunology, Moffitt Cancer Centre, Tampa, FL, USA.
Sci Rep. 2024 Sep 19;14(1):21912. doi: 10.1038/s41598-024-71634-6.
The Notch receptor is a pleiotropic signaling protein that translates intercellular ligand interactions into changes in gene expression via the nuclear localization of the Notch intracellular Domain (NICD). Using a combination of immunohistochemistry, RNA in situ, Optogenetics and super-resolution live imaging of transcription in human cells, we show that the N1ICD can form condensates that positively facilitate Notch target gene expression. We determined that N1ICD undergoes Phase Separation Coupled Percolation (PSCP) into transcriptional condensates, which recruit, enrich, and encapsulate a broad set of core transcriptional proteins. We show that the capacity for condensation is due to the intrinsically disordered transcriptional activation domain of the N1ICD. In addition, the formation of such transcriptional condensates acts to promote Notch-mediated super enhancer-looping and concomitant activation of the MYC protooncogene expression. Overall, we introduce a novel mechanism of Notch1 activity in which discrete changes in nuclear N1ICD abundance are translated into the assembly of transcriptional condensates that facilitate gene expression by enriching essential transcriptional machineries at target genomic loci.
Notch 受体是一种多功能的信号蛋白，它通过 Notch 细胞内结构域（NICD）的核定位，将细胞间配体相互作用转化为基因表达的变化。我们使用免疫组织化学、RNA 原位杂交、光遗传学和人类细胞中转录的超分辨率活细胞成像的组合，表明 N1ICD 可以形成凝聚物，从而积极促进 Notch 靶基因的表达。我们确定 N1ICD 通过相分离偶联渗透（PSCP）进入转录凝聚物，该凝聚物招募、富集和封装了广泛的核心转录蛋白。我们表明，凝聚的能力归因于 N1ICD 的固有无序转录激活结构域。此外，这种转录凝聚物的形成作用促进了 Notch 介导的超级增强子环化，以及随之而来的 MYC 原癌基因表达的激活。总的来说，我们提出了 Notch1 活性的一种新机制，其中核 N1ICD 丰度的离散变化被转化为转录凝聚物的组装，通过在靶基因座富集必需的转录机制来促进基因表达。
