Changes in redox network expression during Caco-2 cell differentiation into enterocytes

Objective: This work characterized fluctuations in cell components involved in the regulation of cell redox homeostasis during Caco-2 cell differentiation into enterocytes. Methods: Caco-2 cells were differentiated for 10 days. Gene expression of NADPH oxidases; enzymes that metabolize superoxide anion and hydrogen peroxide, proteins involved in the production and/or regeneration of glutathione, thioredoxin, and in NADPH production, and Nrf2-dependent genes were measured by qPCR at 0, 1, 4, 7, and 10 days post-confluence. Results: NADPH oxidase 1 mRNA levels decreased with Caco-2 cell differentiation, in agreement with its role in regulating cell proliferation. NADPH oxidase 4, DUOX2, superoxide dismutase 1 and catalase mRNA levels increased with differentiation. Nrf2 mRNA levels increased with differentiation up to day 4 post-confluence, reaching a plateau until day 10. A similar pattern was observed for the Nrf2-regulated genes: NAD(P)H quinone dehydrogenase 1, glutathione reductase 1, and thioredoxin reductase 1. On the contrary, glutamate-cysteine ligase catalytic subunit mRNA levels decreased after reaching a maximum 4 days post-confluence. This and the finding of a correlation between glutathione reductase 1 and thioredoxin reductase 1 mRNA levels, suggest that recycling of glutathione and thioredoxin is more relevant than their synthesis during Caco-2 cell differentiation. Conclusion: Results support the relevance of redox homeostasis for cell fate decisions and in preparing enterocytes to interact with their environment. Significance statement: Current findings resemble changes in redox components previously characterized in vivo. This stresses the concept that Caco-2 cells are an appropriate model to be used to evaluate redox-regulated mechanisms in human enterocytes.