Notch1 activates angiogenic regulator Netrin4 in endothelial cells

Area of Science:

• Molecular Biology
• Cell Biology
• Developmental Biology

Background:

• Netrin4 (NTN4) is a secreted protein crucial for angiogenesis.
• The Notch signalling pathway plays a significant role in vascular development.

Purpose of the Study:

• To investigate the regulatory relationship between Notch signalling and Netrin4 expression in endothelial cells.
• To elucidate the molecular mechanisms underlying Notch-mediated Netrin4 regulation.

Main Methods:

• Utilized transgenic mice and human umbilical vein endothelial cells (HUVECs).
• Assessed NTN4 mRNA and protein levels following Notch1 activation.
• Performed chromatin immunoprecipitation (ChIP) assays to identify transcription factor binding sites.
• Conducted promoter-luciferase assays to confirm functional promoter elements.

Main Results:

• Endothelial expression of activated Notch1 intracellular domain (NICD1) significantly upregulated NTN4 mRNA and intracellular protein.
• Notch1 activation increased NTN4 secretion from HUVECs.
• NICD1 directly bound to the -53 element of the human NTN4 gene promoter via the CSL complex.
• Deletion of the -53 element abolished NICD1-induced NTN4 expression.

Conclusions:

• Notch signalling transcriptionally regulates Netrin4 expression in endothelial cells.
• The -53 element in the NTN4 promoter is essential for NICD1-mediated transcriptional activation.
• This finding reveals a conserved mechanism for Notch in controlling endothelial NTN4 levels, impacting angiogenesis.