Environmental stress and a decline in cellular defense during aging are major factors in etiopathogenesis of many age-linked disorders including cataract. Since local antioxidant capacity determines the susceptibility of a cellular target to oxidative stress, it will be crucial to determine the impact of regulation of a protectiv molecule like Peroxiredoxin6 (Prdx6) on oxidative stress and vice versa. Using targeted inactivation of Prdx6 gene, we have shown that aging lens epithelial cells (LECs) and Prdx6-deficient LECs or eye lenses are vulnerable to cell death or cataractogenesis, suggesting that Prdx6 plays a pivotal role in lens defense. However, mechanisms underlying the reduced activity of Prdx6 are not known. Recently, very intriguing links have been found among oxidative stress levels and a posttranslational modification, Sumoylation of protein(s) and thereby the modulation of protein expression, activity and stability. Ocular lens is constantly exposed to environmental stress. ROS are constantly produced intracellularly, if not removed, leads to deregulation of cellular redox status. Initial studies revealed that Prdx6 expression and activity are deregulated by Sumoylation, leading to loss of Prdx6's protective activity. The rationale for the present proposal is derived from our initial studies showing that (a) Prdx6 is a target for Sumo (Small Ubiqitin-like Modifier)1, and Sumoylation of Prdx6 reduces its activity and cell injury, as evidenced by Prdx6-deficent cells overexpressing Sumo1 and Prdx6 facing oxidative stress;(b) Sumo1-specific protease (Senp)1 is inactivated and Sumo1 is increased in LECs facing oxidative stress and aging LECs;(c) Sumoylation of Sp1, activator of Prdx6, attenuates its activation potential;(d) Delivery of protein transduction domain (TAT)-linked Prdx6K122R/K142R mutant at Sumo1 sites to LECs/lenses provides enhanced cytoprotection against oxidative stress. We hypothesize that aberrant Sumoylation process deregulates Prdx6 function(s) during oxidative stress/aging, and that with aberrant Sumoylation of Prdx6 and its transactivator Sp1, Prdx6 functions go awry, leading to cell malfunction and, in turn, may lead to cataract formation. The overall goal of this proposal is to delineate Sumoylation-mediated-aberrant signaling that causes reduced expression and activity of Prdx6, as well as to uncover the pathogenic processes initiated by loss of Prdx6 activity through three specific aims: (1) Document and examine the effect of oxidative stress and aging on Prdx6 Sumoylation and on Prdx6 protein integrity and protective activity;(2) Determine the effect of Sumoylation/deSumoylation of Sp1 on Prdx6 gene transcription in cells facing oxidative stress or aging cell and Prdx6-/--deficient LECs as a model for aging;(3) Evaluate the potential of TAT-linked Prdx6 mutated at Sumo1 sites in protecting cells/lenses facing oxidative stress in vitro. The Shumiya cataract rat will be used to test TAT-linked Prdx6 in preventing/delaying the progression of cataract formation. The studies should allow us to design new therapies to attenuate the deleterious signaling that causes insults in the elderly and in situations involving physiological and environmental stress, and ultimately to prevent diseases associated with oxidative stress or aging, in general.
Outcomes of current study showing that inactivation and reduced expression of cytoprotective molecules due to aberrant Sumoylation process during aging/environmental stress involved in the initiation and progression of age related degenerated diseases including cataract, should lead in turn formulating ideal and acceptable way(s) to reinforce the antioxidant defense based therapeutics by means of delivering naturally occurring protective molecules directly to target tissues to counteracting oxidative injury of cells. The promising results from these experiments can be readily translated into therapeutic protocol for treating cataractogenesis and other oxidative stress-evoked degenerative diseases in general.
|Hays, Cassandra L; Okafor, Kingsley C; Fan, Shan et al. (2018) Consequences of Puberty on Efficacy of Intraocular Pressure-Lowering Drugs in Male Dutch-Belted Rabbits. J Ocul Pharmacol Ther 34:76-84|
|Kubo, Eri; Shibata, Teppei; Singh, Dhirendra P et al. (2018) Roles of TGF ? and FGF Signals in the Lens: Tropomyosin Regulation for Posterior Capsule Opacity. Int J Mol Sci 19:|
|Shibata, Teppei; Shibata, Shinsuke; Ishigaki, Yasuhito et al. (2018) Tropomyosin 2 heterozygous knockout in mice using CRISPR-Cas9 system displays the inhibition of injury-induced epithelial-mesenchymal transition, and lens opacity. Mech Ageing Dev 171:24-30|
|Chhunchha, Bhavana; Singh, Prerna; Stamer, W Daniel et al. (2017) Prdx6 retards senescence and restores trabecular meshwork cell health by regulating reactive oxygen species. Cell Death Discov 3:17060|
|Chhunchha, Bhavana; Kubo, Eri; Fatma, Nigar et al. (2017) Sumoylation-deficient Prdx6 gains protective function by amplifying enzymatic activity and stability and escapes oxidative stress-induced aberrant Sumoylation. Cell Death Dis 8:e2525|
|Kubo, Eri; Shibata, Shinsuke; Shibata, Teppei et al. (2017) FGF2 antagonizes aberrant TGF? regulation of tropomyosin: role for posterior capsule opacity. J Cell Mol Med 21:916-928|
|Kubo, Eri; Chhunchha, Bhavana; Singh, Prerna et al. (2017) Sulforaphane reactivates cellular antioxidant defense by inducing Nrf2/ARE/Prdx6 activity during aging and oxidative stress. Sci Rep 7:14130|
|Singh, Shatrunjai P; Chhunchha, Bhavana; Fatma, Nigar et al. (2016) Delivery of a protein transduction domain-mediated Prdx6 protein ameliorates oxidative stress-induced injury in human and mouse neuronal cells. Am J Physiol Cell Physiol 310:C1-16|
|Shibata, Teppei; Shibata, Shinsuke; Shibata, Naoko et al. (2016) Propolis, a Constituent of Honey, Inhibits the Development of Sugar Cataracts and High-Glucose-Induced Reactive Oxygen Species in Rat Lenses. J Ophthalmol 2016:1917093|
|Shibata, Shinsuke; Shibata, Naoko; Shibata, Teppei et al. (2016) The role of Prdx6 in the protection of cells of the crystalline lens from oxidative stress induced by UV exposure. Jpn J Ophthalmol 60:408-18|
Showing the most recent 10 out of 11 publications