Reduced oxidative-stress response in red blood cells from p45NFE2-deficient mice

Abstract

p45NF-E2 is a member of the cap 'n' collar (CNC)-basic leucine zipper family of transcriptional activators that is expressed at high levels in various types of blood cells. Mice deficient in p45NF-E2 that were generated by gene targeting have high mortality from bleeding resulting from severe thrombocytopenia. Surviving p45nf-e2 ؊/؊ adults have mild anemia characterized by hypochromic red blood cells (RBCs), reticulocytosis, and splenomegaly. Erythroid abnormalities in p45nf-e2 ؊/؊ animals were previously attributed to stress erythropoiesis caused by chronic bleeding and, possibly, ineffective erythropoiesis. Previous studies suggested that CNC factors might play essential roles in regulating expression of genes that protect cells against oxidative stress. In this study, we found that p45NF-E2-deficient RBCs have increased levels of reactive oxygen species and an increased susceptibility to oxidative-stress-induced damage. Deformability of p45NF-E2-deficient RBCs was markedly reduced with oxidative stress, and mutant cells had a reduced life span. One possible reason for increased sensitivity to oxidative stress is that catalase levels were reduced in mutant RBCs. These findings suggest a role for p45NF-E2 in the oxidative-stress response in RBCs and indicate that p45NF-E2 deficiency contributes to the anemia in p45nf-e2 ؊/؊ mice. IntroductionEukaryotic cells have a battery of mechanisms to defend against the harmful effects of reactive oxygen molecules, 1,2 including antioxidant molecules that function by directly inactivating reactive oxygen molecules and enzymes that metabolically convert toxic compounds to forms that are readily excreted by cells. In many cases, transcriptional activation of genes that play a role in detoxification of xenobiotics and defense against oxidative stress is mediated partly by the antioxidant response element (ARE). For example, AREs were found in promoter sequences of genes including nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase, heme oxygenase, glutathione-S-transferases (GST), and glutamylcysteine synthetase. [3][4][5][6][7] Several different transcription factors, including basic leucine zipper (bZIP) proteins, activator protein 1 (AP-1), and other novel factors, were shown to bind the ARE. 4,8 The ARE consensus sequence is very similar to the NF-E2/AP1-like sequence of the ␤-globin locus control region, which was found to be essential for globin gene expression. Multiple proteins can interact with the NF-E2 consensus sequence. The cap 'n' collar (CNC)-bZIP factor family of proteins was identified from searches for proteins that bind and activate the NF-E2/AP1 site of the ␤-globin locus control region. This multiple-protein family includes p45NF-E2, NF-E2-related factor (Nrf) 1, Nrf2, Nrf3, and the more distantly related Bach1 and Bach2. [9][10][11][12][13][14][15] The similarities among CNC family members are most notable in the basic-DNA binding region and another homology domain spanning 43 amino acids immediately N-terminal to the basic domain. 16 Thi...

Expression of the Aflatoxin B1-8,9-Epoxide-Metabolizing Murine GlutathioneS-Transferase A3 Subunit Is Regulated by the Nrf2 Transcription Factor through an Antioxidant Response Element

“…Because certain of these genes are probably regulated through an ARE, these observations are consistent with a role for Nrf1 in regulating ARE-dependent gene expression. Furthermore, loss of NF-E2 p45 is associated with abrogated expression of mGSTA3 in murine red blood cells (Chan et al, 2001). Figure 11 shows that although loss of Nrf2 is consistently associated with a reduction in mGSTA3 expression levels, the magnitude of this reduction varies between mouse tissues.…”

“…Of particular relevance to the selective toxicity of AFB 1 is the observation that expression of mGSTA3 is reduced in mouse lines with targeted disruption of CNC bZIP genes. Specifically, red blood cells from NF-E2 p45-nulled mice show a marked reduction in mGSTA3 (Chan et al, 2001). Also, liver and small intestine from nrf2 Ϫ/Ϫ mice express less mGSTA3 than nrf2 ϩ/ϩ mice Chanas et al, 2002;Thimmulappa et al, 2002).…”

Biomechanical properties of red blood cells in health and disease towards microfluidics

“…182 However, abnormal response of cells to oxidative stress can cause toxic effects through the production of peroxides and free radicals, leading to damages in RBC skeleton, in normal mechanisms of cellular signaling, in membrane fluidity, and, consequently, it can affect the passage through the microcirculatory network. Thus, impaired RBCs deformability caused by the damages to the structural components of the membrane worsen some pathological situations related to high oxidative stress, such as diabetes, and to microcirculation, such as heart failure and myocardial infarction.…”

The application of mesenchymal progenitor stem cells for the reduction of oxidative stress in animals

“…In the case of mice, deficiency transcription factor was observed (p53, JunD, Foxos, and HIF-2alpha), which is responsible for the regulation mechanisms involved in antioxidant secretion (Pouyet and Carrier, 2010). However, Chan et al (2001) showed deficiency of the p45NF-E2 gene, which causes an accumulation of elevated levels of reactive oxygen intermediates in red blood cells. According to Nocchi et al (2014), one of the main symptoms of oxidative stress in mice is impaired bladder activity associated with the deterioration of contractile response.…”