Mechanistic Insights and Therapeutic Potential of the Glutaredoxin (Grx) System in the Lens

Summary The most common cause of vision loss among the elderly is cataract. Oxidative stress is well known to cause cellular and tissue damage, resulting in age-associated ocular diseases, including cataract. Protein glutathionylation, the reversible formation of a mixed-disulfide between glutathione and protein thiols, is one of the major oxidative protein modifications in response to oxidative stress. The glutaredoxin (Grx) system repairs protein thiols and maintains cellular redox balance. The Grx system has two isoforms, the cytosolic Grx1 (also known as thioltransferase) and the mitochondrial Grx2. The purpose of this proposal is to study how Grx system dysfunction may affect the lens redox signaling and its transparency. We hypothesize that Grx1/Grx2 double deletion may increase the lens susceptibility to ultraviolet (UV) radiation and aging by inhibiting nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent antioxidant response. We also propose that Grx- activating compounds could protect the lens from UV-induced cataract formation. To prove our hypotheses, the following Specific Aims are proposed: 1) To identify the role of the Grx system in protecting the lens from UV radiation and aging using the Grx1/Grx2 DKO mouse as a model. 2) To examine the crosstalk between the Grx system and the Nrf2-antioxidant pathway. 3) To test if Grx activating compounds could protect the lens from UV-induced cataract formation. Successful completion of these aims will introduce the Grx system as a drug target and may lead to the development of Grx-activating compounds as a potential therapeutic for cataract and other oxidative stress-associated eye diseases.