P4500Cellular senescence of endothelial cells impairs angiogenesis by altering energy metabolism through p53-tigar axis

Abstract Background Ischemic disease is prevalent in elderly population due to impaired angiogenesis. Endothelial cell (EC) generates energy largely via glycolysis, which is further activated when angiogenesis actively occurs. PFK-1 is one of the most important regulatory enzymes for glycolysis, which is activated by PFKFB3. On the other hand, TIGAR inhibits PFK-1 under the control of p53. Crucial roles of PFKFB3 in EC functions under physiological and pathological conditions have been reported; however, a role of TIGAR in EC angiogenic functions remains to be elucidated. Furthermore, it remains unknown whether and how cellular senescence affect the energy metabolism in EC. Purpose The purpose of this study is to investigate molecular mechanisms underlying EC dysfunction associated with ageing, especially by focusing on endothelial energy metabolism. Method and result Senescent EC showed reduced glucose consumption assessed by [U-13C]-glucose tracer assay in association with increased expression of p53 and TIGAR. Angiogenic capacity assessed by tube-formation assay was reduced in senescent EC. Of note, either silencing of TIGAR by siRNA or lentivirus-mediated overexpression of PFKFB3 improved angiogenic capacity in senescent EC. These results collectively suggest that senescence impairs glycolysis in EC by activating p53-TIGAR axis, which leads to senescence-associated endothelial dysfunction. To analyze an impact of EC senescence in angiogenesis in vivo, we generated EC-specific progeroid mice in which dominant negative form of telomere repeat-binding factor 2 (TRF2) was overexpressed in EC under the control of the TIE2 promoter. After confirming EC-specific senescence in these endothelial progeroid mice, we generated hind-limb ischemia model. Recovery of blood flow assessed by laser doppler velocimeter was significantly impaired in endothelial progeroid mice, indicating that EC senescence is directly and causally implicated in age-related angiogenic dysfunction. Of note, genetic inactivation of TIGAR completely rescued the impaired ischemia-induced neovessel formation in EC-specific progeroid mice. Conclusion Using unique endothelial progeroid mice, we revealed that EC senescence is a bona fide risk for ischemic disease, largely by reducing glycolysis in EC through p53-TIGAR axis. Our data suggest that endothelial energy metabolism is an attracting therapeutic target for the prevention and/or treatment of ischemic diseases, especially in elderly population.