Notch1 Phase Separation Coupled Percolation facilitates target gene expression and enhancer looping

Area of Science:

• Cell Biology
• Molecular Biology
• Gene Regulation

Background:

• The Notch receptor is a key signaling protein mediating cell-cell communication.
• Notch signaling regulates gene expression through the nuclear translocation of its intracellular domain (NICD).

Purpose of the Study:

• To elucidate the mechanism by which Notch intracellular Domain (NICD) regulates gene expression.
• To investigate the role of NICD in forming nuclear condensates and their impact on transcription.

Main Methods:

• Immunohistochemistry
• RNA in situ hybridization
• Optogenetics
• Super-resolution live imaging of transcription in human cells

Main Results:

• Notch1 intracellular Domain (N1ICD) forms nuclear condensates via Phase Separation Coupled Percolation (PSCP).
• These condensates recruit and enrich core transcriptional proteins, facilitating gene expression.
• The intrinsically disordered transcriptional activation domain of N1ICD drives condensate formation.
• Transcriptional condensate formation promotes Notch-mediated super enhancer-looping and MYC protooncogene expression.

Conclusions:

• N1ICD forms transcriptional condensates that enhance gene expression by concentrating transcriptional machinery.
• This study reveals a novel mechanism for Notch1 activity involving phase separation and condensate assembly at target gene loci.