Targeted disruption of the glutaredoxin 1 gene does not sensitize adult mice to tissue injury induced by ischemia/reperfusion and hyperoxia

Abstract

To understand the physiological function of glutaredoxin, a thiotransferase catalyzing the reduction of mixed disulfides of protein and glutathione (protein-SSG), we generated a line of knockout mice deficient in the cytosolic glutaredoxin 1 (Grx1). To our surprise, mice deficient in Grx1 were not more susceptible to acute oxidative insults in models of heart and lung injury induced by ischemia/ reperfusion and hyperoxia, respectively; suggesting that changes in S-glutathionylation status of cytosolic proteins are not the major cause of such tissue injury. On the other hand, mouse embryonic fibroblasts (MEFs) isolated from Grx1-deficient mice displayed an increased vulnerability to diquat and paraquat, but they were not more susceptible to cell death induced by hydrogen peroxide (H 2 O 2 ) and diamide. A deficiency in Grx1 also sensitized MEFs to protein S-glutathionylation in response to H 2 O 2 treatment and retarded deglatuthionylation of the S-glutathionylated proteins, especially evident for an unspecified protein of approximately 44 kDa. Additional experiments showed that MEFs lacking Grx1 were more tolerant to apoptosis induced by tumor necrosis factor α plus actinomycin D. These findings suggest that different oxidants may damage the cells via distinct mechanisms in which Grx1-dependent de-glutathionylation may or may not be protective, and Grx1 may exert its function on specific target proteins.

Glutathionylation of the Active Site Cysteines of Peroxiredoxin 2 and Recycling by Glutaredoxin

“…Glrx1-deficient mice, generated as described (29), were backcrossed with the C57Bl/6J mouse (stock number 00664, The Jackson Laboratory, Bar Harbor, ME) until all progeny were homozygous for mutant nicotinamide nucleotide transhydrogenase. Female homozygous Glrx Ϫ/Ϫ mice (4 -5 months old) and age-matched WT mice (Glrx ϩ/ϩ ) were euthanized by exsanguination under isoflurane anesthesia.…”

Mechanistic and Kinetic Details of Catalysis of Thiol-Disulfide Exchange by Glutaredoxins and Potential Mechanisms of Regulation

“…46). In mammalian cells, it appears that the Trx system may play the more prominent role in the reduction of RNR for several reasons: (a) in mice, Grx1 knockout is not embryonic lethal and appears to confer no developmental defects (52), whereas Trx knockout is lethal, indicating its importance in development and necessity for RNR function (78); (b) depletion of GSH (a co-substrate for Grx in the proposed RNR reduction mechanism) does not impair RNR activity or DNA synthesis in cultured cells (52,121).…”

“…23,80). Grx is the primary intracellular deglutathionylating enzyme in mammalian cells (21,52), and manipulation of Grx levels has been shown to affect protein glutathionylation status and, subsequently, downstream signaling events (1,2,22,98,137). Thus, understanding mechanisms of deglutathionylation by glutaredoxin enzymes, as well as the ways in which the deglutathionylation activity is regulated in vivo, is of great interest to the field of redox homeostasis.…”

Glutaredoxin-1 Deficiency Causes Fatty Liver and Dyslipidemia by Inhibiting Sirtuin-1

“…Owing to abundant intracellular glutathione (GSH), protein GSH adducts are a key modification (referred to as protein S-glutathionylation [Prot-SG]) that is reversed by the enzyme glutaredoxin-1 (Glrx). Although Glrx has reactive thiols, deficient mice exhibited no aggravated oxidative damage upon angiotensin II infusion, ischemia-reperfusion, or hyperoxia (7,34). Recent studies have demonstrated that GSH adducts, controlled by Glrx, participate in various processes, including cellular growth, apoptosis, cytoskeletal regulation, angiogenesis, and inflammation (1,3,4,51,68,74).…”