Endothelial pyruvate kinase M2 maintains vascular integrity

Area of Science:

• Biochemistry
• Cell Biology
• Oncology

Background:

• Pyruvate kinase M2 (PKM2) is a key metabolic enzyme highly expressed in cancer cells, driving oncogenic metabolism.
• The function of PKM2 in non-transformed and quiescent cells remains largely uncharacterized.
• Endothelial cells predominantly express PKM2 over PKM1.

Purpose of the Study:

• To investigate the role of PKM2 in quiescent endothelial cells.
• To elucidate the mechanisms by which PKM2 regulates endothelial cell function.
• To assess the in vivo consequences of PKM2 loss in endothelial cells.

Main Methods:

• Cell culture of endothelial cells
• PKM2 inhibition studies
• Analysis of tight junctions and barrier function
• NF-kB and angiopoietin 2 pathway analysis
• In vivo mouse models (VEGF-induced vascular leak, sepsis)

Main Results:

• PKM2 is essential for suppressing p53 and maintaining cell cycle progression in proliferating endothelial cells.
• In quiescent endothelial cells, PKM2 inhibition disrupts tight junctions and barrier integrity.
• PKM2 regulates barrier function independently of its canonical enzymatic activity, by suppressing NF-kB and angiopoietin 2.
• Loss of endothelial PKM2 in vivo increases susceptibility to vascular leak and sepsis.

Conclusions:

• PKM2 plays critical, non-metabolic roles in maintaining endothelial barrier function in quiescent cells.
• Targeting PKM2 in cancer therapy requires careful consideration due to its vital functions in non-transformed endothelial cells.
• These findings reveal novel functions of PKM2 in quiescent cell biology and vascular integrity.