NCoR1 limits angiogenic capacity by altering Notch signaling

Area of Science:

• Molecular Biology
• Cell Biology
• Angiogenesis Research

Background:

• Corepressors regulate gene expression through chromatin compaction.
• Targeting endothelial cell phenotype is crucial for controlling angiogenic function.
• Nuclear corepressors are key regulators of gene expression in endothelial cells.

Purpose of the Study:

• To investigate the role of nuclear corepressors in human umbilical vein endothelial cells (HUVECs).
• To determine if targeting corepressor proteins can improve endothelial angiogenic function.
• To elucidate the molecular mechanisms underlying NCoR1's effect on angiogenesis.

Main Methods:

• RNA-sequencing (RNA-seq) to identify highly expressed corepressors in HUVECs.
• Gene knockout and knockdown strategies to assess corepressor function.
• RNA-seq and ATAC-seq for gene expression and chromatin accessibility analysis.
• Spheroid sprouting assays and confrontation assays.
• Proximity ligation assays and luciferase assays to study protein interactions and transcriptional activity.

Main Results:

• Nuclear receptor corepressor 1 (NCoR1), SMRT, and REST were highly expressed in HUVECs.
• NCoR1 depletion significantly increased endothelial angiogenic capacity, unlike SMRT or REST depletion.
• NCoR1 knockdown upregulated angiogenesis-associated genes, particularly tip cell genes (e.g., ESM1, DLL4, NOTCH4), independent of VEGF signaling.
• Loss of NCoR1 promoted tip cell positioning in spheroid sprouting.
• NCoR1 directly binds to RBPJk, and its depletion enhances RBPJk activity and Notch signaling.
• NOTCH4 downregulation abrogated the pro-angiogenic effect of NCoR1 knockdown.

Conclusions:

• Decreasing NCoR1 expression is a promising strategy to enhance endothelial angiogenic function.
• NCoR1 regulates angiogenesis via the Notch signaling pathway, independent of VEGF.
• Targeting NCoR1 offers a novel therapeutic approach for promoting blood vessel formation.