Prox1 is a master control gene in the program specifying lymphatic endothelial cell fate

Area of Science:

• Developmental Biology
• Molecular Biology
• Vascular Biology

Background:

• Lymphangiogenesis, the formation of lymphatic vessels, is initiated by Prox1 expression in venous endothelial cells.
• Prox1 is crucial for promoting and maintaining lymphatic endothelial cell development.
• Prox1-deficient mice lack lymphatic vasculature, with endothelial cells retaining a blood vascular phenotype.

Purpose of the Study:

• To determine if Prox1 is sufficient to induce a lymphatic fate in blood vascular endothelium.
• To investigate the role of Prox1 as a master regulator of lymphatic endothelial cell specification.

Main Methods:

• Ectopic expression of Prox1 cDNA in primary human blood vascular endothelial cells using adenoviral gene transfer.
• Transient plasmid cDNA transfection in immortalized microvascular endothelial cells.
• Transcriptional profiling, quantitative real-time reverse transcription-polymerase chain reaction, and Western blotting.
• Immunohistochemical validation using specific antibodies in tissue sections.

Main Results:

• Prox1 expression up-regulated lymphatic markers: podoplanin and vascular endothelial growth factor receptor-3.
• Prox1 expression down-regulated blood vascular markers: laminin, vascular endothelial growth factor-C, neuropilin-1, and intercellular adhesion molecule-1.
• These molecular changes were confirmed in embryonic and adult tissues.

Conclusions:

• Prox1 is sufficient to reprogram blood vascular endothelium to a lymphatic phenotype.
• Prox1 acts as a master switch controlling the specification of lymphatic endothelial cell fate.
• The lymphatic vasculature likely evolved from the blood vasculature through the expression of key genes like Prox1.