Characterization of autophagy as a mechanism mediating renal and vascular protective effects of the mitocondrial Uncoupling Protein 2
Uncoupling protein 2 (UCP2), belonging to the uncoupling protein family, is involved in the regulation of ATP, mitochondrial membrane potential, cellular calcium homeostasis, cell survival, lipid metabolism, generation of ROS. Its lack leads to mitochondrial dysfunction, ROS accumulation, cell death in vitro and organ damage in vivo. In fact, UCP2 downregulation favors cerebral and renal vascular damage in an animal model of hypertension, the high-salt fed stroke-prone spontaneously hypertensive rat (SHRSP). On the other hand, UCP2 overexpression leads to vascular protection and reduction of atherosclerotic plaque formation.
In the present study we aim to assess the involvement of autophagy, an intracellular self-digestion mechanism that removes dysfunctional proteins and organelles, into the beneficial effects of UCP2 in the vasculature and renal compartments. We will investigate the expression of autophagic markers (LC3 and p62) in the kidneys of high-salt fed SHRSP, without or with a parallel administration of substances able to induce UCP2 expression (Brassica Oleracea, fenofibrate). To confirm the in vivo evidence, primary renal and cerebral endothelial cells derived from SHRSP and exposed to high-salt concentrations will be used to characterize the role of autophagy in the protective effects of UCP2.
The autophagic pathway will be investigated in further details by using commercially available renal and vascular cells, where to test the autophagic flux and the role of ATG7 as a key player of the autophagic machinery. Specifically, ATG7 will be overexpressed in UCP2 gene silenced cells exposed to cellular stresses. The reactivation of autophagy through the synthetic peptide TAT-Beclin 1 will be also performed in these experimental conditions. We expect to identify a decrease of autophagy and of cell viability, in parallel with increased organ damage, in the presence of UCP2 gene silencing, with a prompt recovery of viability upon induction of autophagy.