Senescence-associated metabolic shift impedes endothelial angiogenic functions
F Ito, A Katayama, E Yamazaki, D Ueno, R Urata, T Kitani, K Ikeda, s MatobaAbstract
Background
Aging is closely associated with increased morbidity and mortality of various diseases such as cardiovascular diseases. Cellular senescence is primarily involved in aging process. P53, which plays an important role in cellular senescence, regulates energy metabolism by inducing the transcription of TIGAR, a negative regulator of glycolysis. Endothelial cells (ECs) rely on glycolysis for energy production, and glycolysis is closely associated with their angiogenic functions.
Purpose
We investigated a potential role of the metabolic shift mediated by p53-TIGAR axis in senescence-associated EC dysfunction.
Methods/Results
Angiogenic capacities, such as migration and tube formation were impaired in senescent ECs. We found that the expression of p53 and TIGAR was substantially increased and that glycolytic capacity was significantly reduced in senescent ECs comparing to those in young cells. Silencing TIGAR recovered glycolytic capacity, and notably improved angiogenic functions in senescent ECs. To analyze the effect of EC senescence on angiogenesis in vivo, we generated mice in which ECs are specifically senescent by overexpressing the dominant negative form of telomere repeat-binding factor 2 using the Tie2-promter. When ischemia-induced angiogenesis was assessed using the hindlimb ischemia model, EC-specific progeroid mice showed worsened blood flow recovery in the ischemic limb compared with wild-type mice. Of note, knockout of TIGAR completely reversed the impaired angiogenesis in EC-specific progeroid mice. These data strongly suggest the therapeutic potential of TIGAR inhibitor in ischemic diseases, especially in elderly people. Therefore, we searched for compounds that inhibit TIGAR. We performed in silico screening using the core library of 9600 compounds selected from the library containing 210 thousand compounds. We identified 271 candidate compounds predicted to bind to the enzymatic active site of TIGAR. Employing a cell-free assay that directly measures TIGAR enzymatic activity, we selected the top 20 compounds with the highest inhibitory activity against TIGAR among them. We chose the top 3 compounds that restored the glycolytic capacity in senescent ECs, assessed by flux analyzer. Finally, we selected a single compound that recovered the impaired migratory and angiogenic capacities in senescent ECs. Now, we are investigating whether continuous administration of this compound via osmotic pump could rescue the impaired ischemia-induced neovascularization in aged mice.
Conclusion
In the current study, we identified that the senescence-associated metabolic shift mediated through p53–TIGAR axis is critically involved in impaired angiogenic capacities in senescent ECs. Pharmacological inhibition of TIGAR may offer a promising therapeutic strategy for the treatment of ischemic diseases, especially in elderly population.