Modulation of the Receptor Tyrosine Kinase TIE2/Tek Pathway by NRF2 Activation in Neurovascular Endothelial Cells

Area of Science:

• Endothelial biology
• Molecular mechanisms of angiogenesis
• Cellular homeostasis

Background:

• The transcription factor NRF2 regulates cellular responses to stress and maintains homeostasis.
• NRF2's specific role in angiogenesis, the formation of new blood vessels, is not well-defined.
• Endothelial cells form the inner lining of blood vessels and are crucial for vascular integrity and development.

Purpose of the Study:

• To investigate the role of the transcription factor NRF2 in regulating genes involved in endothelial cell biology.
• To determine the effect of NRF2 modulation on the expression of the TIE2/Tek receptor, a key regulator of angiogenesis.
• To elucidate the molecular mechanisms by which NRF2 influences TIE2/Tek expression.

Main Methods:

• Genetic and pharmacological manipulation of NRF2 in mouse neuroendothelial cells.
• Analysis of gene expression changes, including adherens and tight junction genes.
• Investigation of TIE2/Tek regulation using hemin treatment, BACH1 knockdown, mRNA stability assays, and ChIP analysis.

Main Results:

• NRF2 activation led to the downregulation of the TIE2/Tek receptor in mouse neuroendothelial cells.
• Changes in the expression of genes associated with adherens and tight junctions were observed.
• TIE2/Tek repression by NRF2 was found to be independent of the NRF2 repressor BACH1.
• Post-transcriptional or direct transcriptional repression by NRF2 was ruled out through mRNA stability and ChIP analyses.

Conclusions:

• NRF2 activation influences angiogenesis by downregulating the TIE2/Tek receptor.
• The mechanism of NRF2-mediated TIE2/Tek regulation is not direct transcriptional or post-transcriptional.
• These findings suggest an alternative NRF2-dependent pathway affecting TIE2/Tek levels, impacting angiogenic processes.