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The age-associated loss of ischemic preconditioning in the kidney is accompanied by mitochondrial dysfunction, increased protein acetylation and decreased autophagy.

ABSTRACT: In young rats, ischemic preconditioning (IPC), which consists of 4 cycles of ischemia and reperfusion alleviated kidney injury caused by 40-min ischemia. However,old rats lost their ability to protect the ischemic kidney by IPC. A similar aged phenotype was demonstrated in 6-month-old OXYS rats having signs of premature aging. In the kidney of old and OXYS rats, the levels of acetylated nuclear proteins were higher than in young rats, however, unlike in young rats, acetylation levels in old and OXYS rats were further increased after IPC. In contrast to Wistar rats, age-matched OXYS demonstrated no increase in lysosome abundance and LC3 content in the kidney after ischemia/reperfusion. The kidney LC3 levels were also lower in OXYS, even under basal conditions, and mitochondrial PINK1 and ubiquitin levels were higher, suggesting impaired mitophagy. The kidney mitochondria from old rats contained a population with diminished membrane potential and this fraction was expanded by IPC. Apparently, oxidative changes with aging result in the appearance of malfunctioning renal mitochondria due to a low efficiency of autophagy. Elevated protein acetylation might be a hallmark of aging which is associated with a decreased autophagy, accumulation of dysfunctional mitochondria, and loss of protection against ischemia by IPC.

SUBMITTER: Jankauskas SS

PROVIDER: S-EPMC5353572 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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The age-associated loss of ischemic preconditioning in the kidney is accompanied by mitochondrial dysfunction, increased protein acetylation and decreased autophagy.

Jankauskas Stanislovas S SS Pevzner Irina B IB Andrianova Nadezda V NV Zorova Ljubava D LD Popkov Vasily A VA Silachev Denis N DN Kolosova Nataliya G NG Plotnikov Egor Y EY Zorov Dmitry B DB

Scientific reports 20170315

In young rats, ischemic preconditioning (IPC), which consists of 4 cycles of ischemia and reperfusion alleviated kidney injury caused by 40-min ischemia. However,old rats lost their ability to protect the ischemic kidney by IPC. A similar aged phenotype was demonstrated in 6-month-old OXYS rats having signs of premature aging. In the kidney of old and OXYS rats, the levels of acetylated nuclear proteins were higher than in young rats, however, unlike in young rats, acetylation levels in old and ...[more]

PMID: 28294175

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Project description:Ischemic preconditioning (IPC) has a strong renoprotective effect during renal ischemia/reperfusion (I/R) injury that is thought to relate to autophagy. However, the role of autophagy during IPC-afforded renoprotection and the precise mechanisms involved are unknown. In this study, an in vitro hypoxia/reoxygenation (H/R) model was established in which oxygen and glucose deprivation (OGD) was applied to renal cells for 15 h followed by reoxygenation under normal conditions for 30 min, 2 h or 6 h; transient OGD and subsequent reoxygenation were implemented before prolonged H/R injury to achieve hypoxic preconditioning (HPC). 3-Methyladenine (3-MA) was used to inhibit autophagy. In a renal I/R injury model, rats were subjected to 40 min of renal ischemia followed by 6 h, 12 h or 24 h of reperfusion. IPC was produced by four cycles of ischemia (8 min each) followed by 5 min of reperfusion prior to sustained ischemia. We found that IPC increased LC3II and Beclin-1 levels and decreased SQSTM/p62 and cleaved caspase-3 levels in a time-dependent manner during renal I/R injury, as well as increased the number of intracellular double-membrane vesicles in injured renal cells. IPC-induced renal protection was efficiently attenuated by pretreatment with 5 mM 3-MA. Pretreatment with IPC also dynamically affected the expression of SGK1/FOXO3a/HIF-1α signaling components. Moreover, knocking down SGK1 expression significantly downregulated phosphorylated-FOXO3a (p-FOXO3a)/FOXO3 and HIF-1α, suppressed LC3II and Beclin-1 levels, increased SQSTM/p62 and cleaved caspase-3 levels, and abolished the protective effect of IPC against I/R-induced renal damage. SGK1 overexpression efficiently increased p-FOXO3a/FOXO3 and HIF-1α levels, promoted the autophagy flux and enhanced the protective effect mediated by HPC. Furthermore, FOXO3a overexpression decreased HIF-1α protein levels, inhibited HIF-1α transcriptional activity and reduced the protective effect of IPC. Our study indicates that IPC can ameliorate renal I/R injury by promoting autophagy through the SGK1 pathway.

Project description:Sepsis is a common and life-threatening systemic disorder, often leading to acute injury of multiple organs. Here, we show that remote ischemic preconditioning (rIPC), elicited by brief episodes of ischemia and reperfusion in femoral arteries, provides protective effects against sepsis-induced acute kidney injury (AKI). Methods: Limb rIPC was conducted on mice in vivo 24 h before the onset of cecal ligation and puncture (CLP), and serum exosomes derived from rIPC mice were infused into CLP-challenged recipients. In vitro, we extracted and identified exosomes from differentiated C2C12 cells (myotubes) subjected to hypoxia and reoxygenation (H/R) preconditioning, and the exosomes were administered to lipopolysaccharide (LPS)-treated mouse tubular epithelial cells (mTECs) or intravenously injected into CLP-challenged miR-21 knockout mice for rescue experiments. Results: Limb rIPC protected polymicrobial septic mice from multiple organ dysfunction, systemic accumulation of inflammatory cytokines and accelerated parenchymal cell apoptosis through upregulation of miR-21 in a hypoxia-inducible factor 1? (HIF-1?)-dependent manner in the ischemic limbs of mice. However, in miR-21 knockout mice or mice that received HIF-1? siRNA injection into hind limb muscles, the organ protection conferred by limb rIPC was abolished. Mechanistically, we discovered that miR-21 was transported from preischemic limbs to remote organs via serum exosomes. In kidneys, the enhanced exosomal miR-21 derived from cultured myotubes with H/R or the serum of mice treated with rIPC integrated into renal tubular epithelial cells and then targeted the downstream PDCD4/NF-?B and PTEN/AKT pathways, exerting anti-inflammatory and anti-apoptotic effects and consequently attenuating sepsis-induced renal injury both in vivo and in vitro. Conclusion: This study demonstrates a critical role for exosomal miR-21 in renoprotection conferred by limb rIPC against sepsis and suggests that rIPC and exosomes might serve as the possible therapeutic strategies for sepsis-induced kidney injury.

Dataset Information

The age-associated loss of ischemic preconditioning in the kidney is accompanied by mitochondrial dysfunction, increased protein acetylation and decreased autophagy.

Publications

The age-associated loss of ischemic preconditioning in the kidney is accompanied by mitochondrial dysfunction, increased protein acetylation and decreased autophagy.

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