The Nrf2–Keap1 cellular defense pathway and heat shock protein 70 (Hsp70) response. Role in protection against oxidative stress in early neonatal unilateral ureteral obstruction (UUO)

Abstract

Perturbation of renal tubular antioxidants and overproduction of reactive oxygen species may amplify the proinflammatory state of renal obstruction, culminating in oxidative stress and tubular loss. Here, we analyzed the heat shock protein 70 (Hsp70) response and the function and signal transduction of NF-E2-related protein 2 (Nrf2) transcription factor on oxidative stress modulation in obstruction. Rats were subjected to unilateral ureteral obstruction or sham operation and kidneys harvested at 5, 7, 10, and 14 days after obstruction. Hsp70 expression and Nrf2 activity and its downstream target gene products were assessed. After 10 and 14 days of obstruction, enhanced lipid peroxidation through higher thiobarbituric acid reactive substances levels and increased oxidative stress resulted in reduced total antioxidant activity and enhanced nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase activity were demonstrated. This was accompanied by decreased inducible Hsp70 expression and a progressive reduction of nuclear Nrf2 and its target gene products glutathione S-transferase A2 (GSTA2) and NADPH/quinone oxidoreductase 1 (NQO1), whereas the Nrf2 repressor Kelch-like ECH-associated protein-1 (Keap1) was upregulated. By contrast, on early obstruction for 7 days, lack of increased oxidative markers associated with higher inducible Hsp70 protein levels and a rapid nuclear accumulation of Nrf2, Keap1 downregulation, and mRNA induction of the identified Nrf2-dependent genes, NQO1 and GSTA2, were shown. For these results, we suggest that the magnitude of cytoprotection in early obstruction depends on the combined contribution of induced activation of Nrf2 upregulating its downstream gene products and Hsp70 response. Impaired ability to mount the biological response to the prevailing oxidative stress leading to renal injury was shown in prolonged obstruction.Keywords Hsp70/72 . Nrf2-Keap1 . Oxidative stress . Unilateral ureteral obstruction Abbreviations ABTS 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid AEBSF 4-(2 Aminoethyl)-benzenesulfonyl fluoride ARE

Urinary Proteomics Yield Pathological Insights for Ureteropelvic Junction Obstruction

“…A total of 24 statistically significant proteins were associated with oxidative stress, of which 13 are represented in the putative biomarker panel (Table III). For example, in accordance with the literature, HSP70 was significantly up-regulated in HUK, indicating a potential antioxidant protective effect during obstruction but conversely down-regulated in HUB (bladder), suggesting a different role in the compensatory mechanism of the contralateral kidney (25). Similar changes in HSP70 have been demonstrated with immunohistochemistry and Western blot analysis of the obstructed renal cortex from UUO rodent models (25), but this is the first human demonstration of quantitative changes of urinary HSP70 highlighting its position as a protein of interest in UPJO.…”

Transcriptional control of glyoxalase 1 by Nrf2 provides a stress-responsive defence against dicarbonyl glycation

“…In these cases of increased cell dysfunction and damage and physiological morbidity, Glo1 induction was insufficient to prevent increased protein damage by MG. The mechanism of induction was unknown but can now be linked to the endogenous Nrf2-mediated antistress gene response known to be activated in these conditions [33][34][35][36]. Studies with Glo1 overexpressing transgenic animals have indicated that increased expression of Glo1 has beneficial effect -maintenance of vascular cell responses, prevention of myocardial cell death when oxygenated after ischaemia and delay of ageing and senescence [13;37;38].…”

Mediators and mechanisms of heat shock protein 70 based cytoprotection in obstructive nephropathy

“…In turn, they play an important role for cellular signal transduction; however, an excess may cause oxidative stress, currently known as a major cause of renal inflammation and subsequent damage (Joshi et al 2013). The proinflammatory state would be amplified by changes in renal antioxidants and ROS levels (Rinaldi Tosi et al 2011). In this context, both the oxidative stress and the induction of the Fig.…”

“…More importantly, rotenone moderately but significantly restored the reduction of mitochondrial DNA copy number and mitochondrial NADH dehydrogenase subunit 1 (mtND1) expression in obstructed kidneys, suggesting an amelioration of mitochondrial injury (Sun et al 2014). Originally, and of particular interest to the present review, we evaluated that the pro-inflammatory state would be amplified by changes in renal antioxidants and ROS levels (Rinaldi Tosi et al 2011). In this context, both the oxidative stress and the induction of mitochondrial apoptosis could be prevented by Hsp70 expression ).…”