Transgenic Mice Overexpressing Glutathione Peroxidase 4 Are Protected against Oxidative Stress-induced Apoptosis

Abstract

Glutathione peroxidase 4 (Gpx4) is uniquely involved in the detoxification of oxidative damage to membrane lipids. Our previous studies showed that Gpx4 is essential for mouse survival and that Gpx4 deficiency makes cells vulnerable to oxidative injury. In the present study, we generated two lines of transgenic mice overexpressing Gpx4 (Tg(GPX4) mice) using a genomic clone containing the human GPX4 gene. Both lines of Tg-(GPX4) mice, Tg5 and Tg6, had elevated levels of Gpx4 (mRNA and protein) in all tissues investigated, and overexpression of Gpx4 did not cause alterations in activities of glutathione peroxidase 1, catalase, Cu/Zn superoxide dismutase, and manganese superoxide dismutase. The human GPX4 transgene rescued the lethal phenotype of null mutation of the mouse Gpx4 gene, indicating that the transgene can replace the essential role of mouse Gpx4 in mouse development. Cell death induced by t-butylhydroperoxide and diquat was significantly less in murine embryonic fibroblasts from Tg(GPX4) mice compared with wild type mice. Liver damage and lipid peroxidation induced by diquat were reduced significantly in Tg(GPX4) mice. In addition, diquat-induced apoptosis was decreased in Tg(GPX4) mice, as evidenced by attenuated caspase-3 activation and reduced cytochrome c release from mitochondria. These data demonstrate that Gpx4 plays a role in vivo in the mechanism of apoptosis induced by oxidative stress that most likely occurs through oxidative damage to mitochondrial phospholipids such as cardiolipin.Reactive oxygen species (ROS), 1 such as superoxide and hydrogen peroxide, are constantly generated in aerobic organisms during normal respiration. In addition, environmental factors (such as ionizing radiation) and pathological compounds (such as ␤-amyloid in Alzheimer's disease) can generate ROS. Although ROS at physiological concentrations may be required for normal cell function, excessive production of ROS can be detrimental to cells, because ROS can cause oxidative damage to lipids, protein, and DNA. Polyunsaturated fatty acids, which are found predominantly in cellular membranes, are especially vulnerable to attack by ROS because of the high concentration of allylic hydrogens in their structure (1). The resulting lipid hydroperoxides can affect membrane fluidity and the function of membrane proteins. In addition, lipid hydroperoxides can undergo iron-mediated, one-electron reduction and oxygenation to form epoxyallylic peroxyl radicals, which trigger a chain reaction of free radical-mediated lipid peroxidation (2). The end-products of lipid peroxidation are reactive aldehydes such as 4-hydroxyl nonenal and malondialdehyde, many of which are highly toxic to cells (3). In addition, reactive aldehydes generated by lipid peroxidation can attack other cellular targets, such as proteins and DNA, thereby propagating the initial damage in cellular membranes to other macromolecules. Because lipid hydroperoxides formed in membranes are an important component of ROS generation in vivo, their detoxification appears to ...

Molecular biology of glutathione peroxidase 4: from genomic structure to developmental expression and neural function

“…Such increases in ROS levels have been found in neuropathological conditions such as trauma, seizures, and ischemia, as well as when neurons are exposed to b-amyloid (Ab) peptides (Andersen, 2004). In fact, mice with transgenic overexpression of GPx4 in neurons of the cerebral cortex, hippocampus and in cerebellum are protected from oxidative injury (Ran et al, 2004). More importantly, Ab peptide toxicity is decreased and neurons survive upon expression of high levels of GPx4 (Ran et al, 2006).…”

Apoptosis and glutathione: beyond an antioxidant

“…87 GPX4 (also known as phospholipid hydroperoxide glutathione peroxidase, PHGPX) overexpression has been reported to protect against oxidative stress-induced apoptosis. 88 GPX4 also protects against oxidative stress and amyloid-induced apoptosis. 89 More recently, GPX4 downregulation has been shown to induce 12/15 lipoxygenase-dependent lipid peroxidation and apoptosis-inducing-factor-mediated cell death.…”

Ablation of the Ferroptosis Inhibitor Glutathione Peroxidase 4 in Neurons Results in Rapid Motor Neuron Degeneration and Paralysis

“…In somatic cells, GPX4 is important in the protection against lipid peroxidation because of its ability to reduce hydroperoxides in lipids such as phospholipids, cholesterol, and cholesterol ester (1). GPX4 has been shown previously to suppress apoptosis (2)(3)(4). However, Yang et al (5,6) recently identified GPX4 as a key inhibitor of ferroptosis, an oxidative, iron-dependent type of cell death that exhibits features different from other cell death mechanisms, and ferroptosis-inducing compounds were shown to inhibit GPX4 enzyme activity directly by binding to GPX4 protein (e.g.…”