Disrupted Binding of Cystathionine γ-Lyase to p53 Promotes Endothelial Senescence

Abstract

Background: Advanced age is unequivocally linked to the development of cardiovascular disease; however, the mechanisms resulting in reduced endothelial cell regeneration remain poorly understood. Here, we investigated novel mechanisms involved in endothelial cell senescence that impact endothelial cell transcription and vascular repair after injury. Methods: Native endothelial cells were isolated from young (20±3.4 years) and aged (80±2.3 years) individuals and subjected to molecular analyses to assess global transcriptional and metabolic changes. in vitro studies were conducted using primary human and murine endothelial cells. A murine aortic reendothelialization model was used to examine endothelial cell regenerative capacity in vivo. Results: RNA sequencing of native endothelial cells revealed that aging resulted in p53-mediated reprogramming to express senescence-associated genes and suppress glycolysis. Reduced glucose uptake and ATP contributed to attenuated assembly of the telomerase complex, which was required for endothelial cell proliferation. Enhanced p53 activity in aging was linked to its acetylation on K120 due to enhanced activity of the acetyltransferase MOZ (monocytic leukemic zinc finger). Mechanistically, p53 acetylation and translocation were, at least partially, attributed to the loss of the vasoprotective enzyme, CSE (cystathionine γ-lyase). CSE physically anchored p53 in the cytosol to prevent its nuclear translocation and in its absence inhibited Akt-mediated MOZ phosphorylation, which in turn increased MOZ activity and subsequently p53 acetylation. In mice, the endothelial cell–specific deletion of CSE activated p53, induced premature endothelial senescence, and arrested vascular repair after injury. In contrast, the adeno-associated virus 9–mediated reexpression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in native endothelial cells from aged individuals maintained low p53 activity and reactivated telomerase to revert endothelial cell senescence. Conclusions: Aging-associated impairment of vascular repair is partly determined by the vasoprotective enzyme CSE.

Impaired glycolysis in aged endothelial cells is associated with reduced neovascularisation upon tissue ischemia

“…This finding is recapitulated in the RNASeq analyses, where we do not observe upregulation of classical markers of cellular senescence p16 and p21 expression. These findings are in opposition to a previous study which described distinct changes in expression of genes regulating cell cycle control and p53-mediated transcription in endothelial cells harvested from 80-year old mesenteric arteries 20 . These differences could be attributed to age differences (our use of 18-months old mice, equivalent to a 56 year old human), or to a difference in EC subtype (our use of ECs harvested from gastrocnemius muscle, which consists mainly of capillary ECs, whereas the described study looked at arterial ECs), or even due to species-related factors that we have not accounted for.…”

“…Another key observation is the decline of the neovascularisation potential with age, as previously shown in murine models of ischemic injury 16–18 . This age-associated decline in neovascularisation has been attributed to changes in EC migration and proliferation capacity, changes in EC metabolism 19 , and increased EC senescence and apoptosis 20–23 .…”

Transcriptional Control of Endothelial Senescence and Vascular Repair

“…Reduced endothelial regeneration closely corresponds with senescent cell accumulation, and nowhere is this more prevalent than in cardiovascular disease. 3,4 Infact, it turned out that a recent study by the lead author Jiong Hu 5 supported by the group of Sofia-Iris Bibli and Ingrid Fleming revealed some surprising results on transcriptional control associated with senescence. When researchers isolated CD144 + endothelial cells derived from the mesenteric artery from 38 young (20±3.4 years) and 34 aged (80±2.3 years) individuals, they observed expected reduction in telomere length correlating with elevated senescenceassociated β-galactosidase and increased p53 transcriptional activity.…”