Oxidative stress induces inactivation of protein phosphatase 2A, promoting proinflammatory NF-κB in aged rat kidney

The molecular inflammation hypothesis of aging proposes that redox dysregulation causes an age-related activation of NF-κB and its signaling to upregulate various proinflammatory genes. In the present study, we focused on the inactive form of the protein phosphastase 2A (PP2A). More specifically, we...

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Published in:Free radical biology & medicine 2013-08, Vol.61, p.206-217
Main Authors: Jin Jung, Kyung, Hyun Kim, Dae, Kyeong Lee, Eun, Woo Song, Chang, Pal Yu, Byung, Young Chung, Hae
Format: Article
Language:English
Subjects:
Aging
Aging - metabolism
Animals
anti-aging properties
food intake
Free radicals
gene expression regulation
genes
HEK293 Cells
Humans
inflammation
Kidney - metabolism
kidneys
Male
Mice
Mice, Inbred C57BL
mitogen-activated protein kinase
Molecular inflammation
NF-kappa B - metabolism
NF-κB
Oxazoles - pharmacology
oxidation
Oxidative Stress
phosphoprotein phosphatase
phosphorylation
PP2A
Protein Phosphatase 2 - physiology
protein subunits
Protein-Tyrosine Kinases - physiology
Rats
Rats, Inbred F344
small interfering RNA
transcription factor NF-kappa B
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Summary:The molecular inflammation hypothesis of aging proposes that redox dysregulation causes an age-related activation of NF-κB and its signaling to upregulate various proinflammatory genes. In the present study, we focused on the inactive form of the protein phosphastase 2A (PP2A). More specifically, we aimed to define the correlation between PP2A inactivation and NF-κB activation by age-related oxidative stress. Experimentations were designed to determine the effect of oxidative stress-induced PP2A inactivation on NF-κB activity, utilizing prooxidants t-BHP and AAPH, the PTP inhibitor Na3VO4, and the PP2A inhibitor Calyculin A and PP2A siRNA, in HEK293T cells. We also assessed the phosphorylation of PP2A catalytic subunit (PP2Ac) and the activities of PP2A and NF-κB in aged rat kidney, utilizing aging-retarding 40% calorie restriction (CR) −60% of food intake and inflammation-triggering LPS paradigms. Results revealed that an oxidative stress-induced PTK/PTP imbalance led to phosphorylation of PP2Ac, following exposures to t-BHP, AAPH, and Na3VO4 in HEK293T cells. Subsequently, we found that Calyculin A and PP2A siRNA activates NIK/IKK and MAPKs, leading to upregulation of NF-κB and its dependent oxidative stress. Also, the contrasting relation between PP2A inactivation and NF-κB activation was confirmed by AAPH-induced oxidative status in mice, and non-induced normal status or LPS-induced inflammatory status in aged rats while the antioxidative, anti-inflammatory, anti-aging effects of CR significantly blunted these actions. Thus, we present evidence that PP2A inactivation via PTK/PTP imbalance provoked by oxidative stress causes NF-κB activation, which contributes to the accumulation of oxidative stress in aged rat kidney. •Oxidative stress induces phosphorylation of PP2Ac (Tyr307), leading to PP2A inactivation.•PP2A inactivation is mediated by oxidative stress-induced PTK/PTP imbalance.•PP2A inactivation causes activation of NF-κB and its signaling.•PP2A inactivation promotes and accumulates NF-κB-dependent oxidative stress and inflammatory process during aging.
ISSN:0891-5849
1873-4596
DOI:10.1016/j.freeradbiomed.2013.04.005