Expression and regulation of antioxidant enzymes in the developing limb support a function of ROS in interdigital cell death

Abstract

Vertebrate limb development is a well-studied model of apoptosis; however, little is known about the intracellular molecules involved in activating the cell death machinery. We have shown that high levels of reactive oxygen species (ROS) are present in the interdigital 'necrotic' tissue of mouse autopod, and that antioxidants can reduce cell death. Here, we determined the expression pattern of several antioxidant enzymes in order to establish their role in defining the areas with high ROS levels. We found that the genes encoding the superoxide dismutases and catalase are expressed in autopod, but they are downregulated in the interdigital regions at the time ROS levels increased and cell death was first detected. The possible role of superoxide and/or peroxide in activating cell death is supported by the protective effect of a superoxide dismutase/catalase mimetic. Interestingly, we found that peroxidase activity and glutathione peroxidase-4 gene (Gpx4) expression were restricted to the non-apoptotic tissue (e.g., digits) of the developing autopod. Induction of cell death with retinoic acid caused an increase in ROS and decrease in peroxidase activity. Even more inhibition of glutathione peroxidase activity leads to cell death in the digits, suggesting that a decrease in antioxidant activity, likely due to Gpx4, caused an increase in ROS levels, thus triggering apoptosis.

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

“…Thus, GPx4 may specifically impact the signaling of mitochondrial apoptosis. This mechanistic evidence is supported by findings reported on the role of GPx4 during limb development, where expression of GPx4 is restricted to non-apoptotic tissue and manipulation of expression alters apoptosis patterns in tissues (Schnabel et al, 2006). Despite these data linking GPx4 to developmental processes, there appears to be room for GPx4 activity independent of its anti-apoptotic character.…”

Detoxifying effect of fermented black ginseng on H2O2-induced oxidative stress in HepG2 cells

“…These include antioxidant enzymes, such as superoxide dismutase (SOD), which catalyzes the dismutation of superoxide anions to hydrogen peroxide; catalase (CAT), which converts H 2 O 2 into molecular oxygen and water; glutathione peroxidase (GPx), which catalyzes the degradation of H 2 O 2 and hydroperoxides. On the non-enzymatic level, certain vitamins and other antioxidant compounds scavenge free radicals and delay the oxidation of molecules (4,5). Phytochemicals provide further protection against oxidative damage from free radicals.…”

Interdigital tissue regression in the developing limb of vertebrates

“…In addition to the activation of apoptosis and lysosomes, oxidative stress might exert an important role in the establishment of the areas of interdigital cell death (Schnabel et al, 2006). The interdigital tissue, at difference of the digital regions, express low levels of genes encoding antioxidant enzymes such as superoxide dismutases, catalase and peroxidases (Schnabel et al, 2006;Shan et al, 2005), and reactive oxygen species increase in the interdigital tissue at the onset of cell death (Salas-Vidal et al, 1998).…”

“…The interdigital tissue, at difference of the digital regions, express low levels of genes encoding antioxidant enzymes such as superoxide dismutases, catalase and peroxidases (Schnabel et al, 2006;Shan et al, 2005), and reactive oxygen species increase in the interdigital tissue at the onset of cell death (Salas-Vidal et al, 1998). Furthermore, cell death is inhibited in vitro by antioxidant treatments (Salas-Vidal et al, 1998;Schnabel et al, 2006). Oxidative stress can damage most cell components, including mitochondrial and lysosomal membranes.…”