Sumoylation-deficient Prdx6 repairs aberrant Sumoylation-mediated Sp1 dysregulation-dependent Prdx6 repression and cell injury in aging and oxidative stress

Abstract

Progressive deterioration of antioxidant response in aging is a major culprit in the initiation of age-related pathobiology induced by oxidative stress. We previously reported that oxidative stress leads to a marked reduction in transcription factor Sp1 and its mediated Prdx6 expression in lens epithelial cells (LECs) leading to cell death. Herein, we examined how Sp1 activity goes awry during oxidative stress/aging, and whether it is remediable. We found that Sp1 is hyper-Sumoylated at lysine (K) 16 residue in aging LECs. DNA binding and promoter assays revealed, in aging and oxidative stress, a significant reduction in Sp1 overall binding, and specifically to Prdx6 promoter. Expression/overexpression assay revealed that the observed reduction in Sp1-DNA binding activity was connected to its hyper-Sumoylation due to increased reactive oxygen species (ROS) and Sumo1 levels, and reduced levels of Senp1, Prdx6 and Sp1. Mutagenesis of Sp1 at K16R (arginine) residue restored steady-state, and improved Sp1-DNA binding activity and transactivation potential. Extrinsic expression of Sp1K16R increased cell survival and reduced ROS levels by upregulating Prdx6 expression in LECs under aging/oxidative stress, demonstrating that Sp1K16R escapes the aberrant Sumoylation processes. Intriguingly, the deleterious processes are reversible by the delivery of Sumoylation-deficient Prdx6, an antioxidant, which would be a candidate molecule to restrict aging pathobiology.

Sulforaphane-Induced Klf9/Prdx6 Axis Acts as a Molecular Switch to Control Redox Signaling and Determines Fate of Cells

“…Intracellular ROS level was measured by use of fluorescent dye dichlorofluorescin diacetate (H2DCFDA), a nonpolar compound that is converted into a polar derivative (dichlorofluorescein) by cellular esterase after incorporation into cells [7,52,72,73]. On the day of the experiment, the medium was replaced with Hank′s solution containing 10 µM H2DCFDA dye and cells were incubated at 37 °C.…”

“…Prdx6 is a cytosolic protein and is abundantly expressed in lung, eye lens, keratinocytes, skin and brain [43,44,45,46]. It is also localized in ROS-producing organelles, such as endoplasmic reticulum, plasma membrane, lysosomes, mitochondria and cerebrospinal fluid [47,48,49,50,51], suggesting its importance in controlling redox-homeostasis for cell survival [1,48,52,53,54]. Prdx6 protects many cell types from lipid peroxidation-mediated damage to membrane, DNA and protein [1,6,7,49,52,55,56,57,58].…”

The Role of Peroxiredoxin 6 in Cell Signaling

“…Prdx6 can also be aberrantly Sumoylated by Sumo1 at lysines 122 and 142 during oxidative stress. Aberrant sumoylation of Prdx6 reduces its gene expression and protein abundance [24,25,26].…”

“…The role of Prdx6 in ocular oxidative damage has been extensively investigated [91,92]. Prdx6 expression in the eye declines with age, increasing the risk of cataract formation [26,93,94]. Moreover, Prdx6 prevents oxidative stress in human retinal pigment epithelial cells by activating the Phosphoinositide 3-kinase/Protein kinase B (PI3K/AKT) pathway [95] and blunting transforming growth factor beta (TGF-β) signaling [96].…”

Dentate Gyrus Peroxiredoxin 6 Levels Discriminate Aged Unimpaired From Impaired Rats in a Spatial Memory Task

“…The role of PRDX6 in oxidative stress was described above in the introduction section. Decline of PRDX6 during aging has been associated with ocular pathobiology induced by age-related oxidative stress (Kubo et al, 2017; Chhunchha et al, 2018). Chhunchha et al (2017) proposed PRDX6 as a potential therapeutic target to protect the trabecular meshwork from age-dependent oxidative stress and accumulation of ROS by balancing redox-homeostasis to prevent ocular disorders.…”