The role of NRF2 antioxidant genes in the embryonic development of Xenopus laevis

Embryonic development is a complex process through which a single cell gives rise to a fully formed organism, relying on tightly regulated cellular events such as proliferation, differentiation, and programmed cell death. Proper regulation of these processes depends on maintaining physiological levels of reactive oxygen species (ROS). ROS levels are controlled by antioxidant genes, many of which are regulated by the Nrf2 antioxidant pathway, a conserved defense mechanism against oxidative stress in both invertebrates and vertebrates. Although the Nrf2 pathway has been widely studied in cancer biology, its role in embryonic development remains less understood. Nrf2 is negatively regulated by Kelch-like ECH-associated protein 1 (keap1), which targets Nrf2 for degradation under normal conditions. Upon oxidative stress, Nrf2 is stabilized and induces the expression of various antioxidant genes, including oxidative stress-induced growth inhibitor 1 (Osgin1). To explore the role of the Nrf2 pathway during development, we performed whole mount in situ hybridization to examine the spatiotemporal expression of keap1 and Osgin1 in Xenopus laevis embryos. We found that Osgin1 is expressed in the notochord and prechordal plate during neurulation, and in the brain and spinal cord during tailbud stages, suggesting it may link oxidative stress regulation to neural tissue induction and differentiation. Previous studies also implicate Osgin1 in apoptosis and autophagy, indicating that it may influence these processes in the notochord and prechordal plate. Keap1 was ubiquitously expressed from neurulation through later development, supporting its essential role in sensing ROS and regulating Nrf2 activity throughout the embryo. These findings offer new insights into the expression of Nrf2 pathway genes and provide a foundation for further research into their roles in embryonic development.