Controlling Redox Status for Stem Cell Survival, Expansion, and Differentiation

Figure 1

ROS generation and scavenging in stem cells. (a) ROS generation. ROS generation is initiated with the electron transfer to molecular O₂, leading to the formation superoxide radicals (), a precursor of the various ROS. Hydroxyl radicals (OH^•) are generated from through a Fenton reaction. Alternatively, SOD catalyzes the formation of hydrogen peroxide (H₂O₂). (b) ROS are mainly generated at various complex of the respiratory chain, located in the inter-membrane space of the mitochondria. (c) ROS scavenging. The degradation of ROS is catalyzed by scavenging proteins, that is, glutathione peroxidases, catalase, and peroxiredoxin (Prx). Prx are dimers, which contain cysteine (–SH groups) (1). In the presence of H₂O₂, the cysteine –SH groups are oxidized to –SOH (2), which then condensed to form disulfide groups (S–S) (3). The S–S groups of Prx are reduced by thioredoxin (Trx) to return to the initial –SH form (1). PRX-SOH can be overoxidized by H₂O₂ to form Prx-SO₂H groups (4).

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