Interaction of AR and iNOS in lens epithelial cell: A new pathogenesis and potential therapeutic targets of diabetic cataract

Abstract

Although there is significant interest in revealing the role of aldose reductase (AR) and inducible nitric oxide synthase (iNOS) in diabetic cataract (DC), the interaction of AR and iNOS remains unknown. The aim of this study is to investigate the pathogenesis mechanisms and explore as a new potential therapeutic targets for DC. This study investigated the interaction of AR-iNOS through the methods of enzyme kinetics, molecular docking and molecular dynamics simulation, co-immunoprecipitation and fluorescence resonance energy transfer (FRET). The IC50 of AR for inhibition of iNOS activity is 0.04 μM, and the IC50 of iNOS for inhibition of AR activity is 0.042 μM through enzyme kinetics; the interface showed that ARG99 on AR and GLU317 on iNOS played the key roles in the interaction of AR-iNOS predicted by molecular docking and molecular dynamics simulation. Co-immunoprecipitation of protein complexes in human lens epithelial cell (HLEC) demonstrated that AR could association with iNOS in cell; and the interaction distance of AR-iNOS was 6.50 ± 0.22 nm detected by FRET. This study exhibited a direct inhibition interaction between AR and iNOS in HLECs. It is the first report of inhibition interaction between AR and iNOS, suggesting a new pathophysiological mechanism and providing a new insight into the therapeutic mechanism of DC.

A comparative clinical study on the generation of nitrosative stress in cataractous lenses of smokers and non-smoker tobacco patients

“…This has been concomitant with the previous reports that clearly revealed the levels of iNOS, 3-NT, and NO to be higher in cataractous lenses than in normal lenses. 3,8,14,19 Interestingly, in this study, the levels of NO and its derived metabolites were found to significantly increased in smokers who chewed tobacco when compared with those in non-smokers who chewed tobacco (p < 0.05). Smoking habit along with tobacco consumption can increase the levels of NO and CO. NO alone is a highly reactive molecule which can be rapidly oxidized and react with other biomolecules such as superoxide and catalase.…”

“…19–21 Smoking is considered as one of the factors that implicate to increase the level of nitrous oxide in cataractous lenses. 8 Therefore, in this study, a comparative effect of nitrosative stress metabolites such as NO, iNOS, and 3-NT has been evaluated in cataractous lenses from different groups, namely, non-smokers, smokers, non-smokers who chewed tobacco, and smokers who chewed tobacco.…”

“…Furthermore, this nitrosative stress leads to the damage of LECs. 8–10 It has been reported that the levels of NO play an important role in controlling the ocular blood flow. 11 Peroxynitrite is a highly oxidative species that has the capability of nitrating tyrosine residues, that is, 3-nitrotyrosine (3-NT) of crystalline proteins which has the potency to induce opacification in the lenses.…”

Medicinal Plants and Natural Products Used in Cataract Management

“…Excessive glucose level induces the glycation of proteins, generating superoxide radicals and AGEs in the process. Recent studies suggest that there is interdependence between the oxidative stress and polyol pathway, through AR and iNOS, responsible for the nitric oxide production during oxidation (Snow et al, 2015; Li et al, 2017) (Figure 1).…”

Effectiveness of Magnolol, a Lignan from Magnolia Bark, in Diabetes, Its Complications and Comorbidities—A Review

“…Under physiological conditions, nitric oxide (NO) is responsible for neurotransmission or vasodilation; it is a specific signaling molecule. However, its excessive production associated with the activation of iNOS by cytokines, NF-κB [ 77 ] or AGEs, leads to pathological changes within the eye [ 53 , 74 ]. The in vitro hyperglycemia-induced cataract model showed that the use of NOS inhibitors improved the condition of the eye cells [ 78 ].…”