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yan shao, Jianglei Chen, Xiaorong Li, Jian-Xing (Jay) Ma; Diabetes-induced down-regulation of PPARα plays a key role in the deficiency of endothelial progenitor cells and mitochondrial function. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6425. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Deficiency of endothelial progenitor cells (EPC) plays an important role in retinal vascular degeneration in diabetic retinopathy (DR). Fenofibrate, an agonist of peroxisome proliferator-activated receptor-α (PPARα), has shown therapeutic effects on DR both in patients and in animal models. The molecular mechanism for diabetes-induced EPC deficiency has not been fully understood. The purpose of this study was to determine the role of PPARα in EPC protection from diabetic stress through regulation of EPC metabolism.
EPC in the bone marrow, blood and retinas of db/db, non-diabetic control mice, PPARα knockout (PPARα-/-) and wild-type (WT) mice were quantified using flow cytometry. PPARα levels were measured in the bone marrow from db/db and non-diabetic mice and in primary EPC isolated from the bone marrow under diabetic conditions. Mitochondrial function and glycolysis in primary EPC were measured using XFe96 Seahorse Flux Analyzer in isolated EPC. EPC function was evaluated by migration, proliferation and tube formation assays.
EPC numbers and their mitochondrial function were decreased in the bone marrow, circulation and retina of db/db mice, correlating with PPARα down-regulation in EPC. Activation of PPARα by fenofibrate normalized EPC numbers and mitochondrial function in db/db mice. On the other hand, PPARα KO exacerbated decreases in EPC numbers and mitochondrial dysfunction in diabetic mice. Primary EPC from PPARα-/- mice displayed impaired migration, proliferation and tube formation compared to WT EPC. Furthermore, PPARα-/- EPC showed reduced levels of mitochondrial oxidation and glycolysis, compared to WT EPC. In primary EPC, PPARα KO down-regulated Akt phosphorylation and downstream genes Nrf2, Nrf1, Sirt1, Glut4 and Cyclin D1 which are important for EPC cell fate and EPC metabolism.
PPARα is an endogenous regulator of EPC metabolism and plays a key role in the regulation of EPC function and cell fate. Diabetes-induced down-regulation of PPARα in EPC contributes to EPC deficiency and represents a new therapeutic target for DR.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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