Exosome-Mediated Protection Against Oxidative Stress: A Connection Between NRF2 And Exosomes

Abstract

The nuclear factor erythroid 2 (NF-E2)-related factor 2 (NRF2) transcription factor has been widely studied for its role as the master regulator of the response to oxidative stress. NRF2 has many mechanisms for protection including upregulation of antioxidant genes, metabolism genes, and proteolysis genes. Furthermore, it was found that a deeply conserved set of NRF2 target genes encode for proteins loaded into exosomes [1]. Exosomes are extracellular microvesicles that are secreted by cells in response to a variety of stimuli, including many stressors. Exosomes serve as a transport mechanism for proteins, RNA, DNA, and other molecules. Therefore, we hypothesized that exosome loading and release is a mechanism used by NRF2 to protect neighboring cells from stress in a non-autonomous manner. In an effort to validate that NRF2 regulates exosomes, I explored the following: (1) exosome release before and after NRF2 activation, (2) the RNA and protein content of NRF2-induced exosomes, and (3) the cytoprotective potential of NRF2-induced exosomes. Overall, based on these studies, we concluded that NRF2 activation induces exosome release, and exosomes are generally enriched for cytoprotective protein SQSTM1. However, although NRF2-induced exosomes were cytoprotective in some assays, this response was not robust enough for me to conclude that NRF2-induced exosomes can protect naïve cells from oxidative stress. Thus, exosomes provide a potential mechanism for NRF2 to provide nearby cells with resources to combat oxidative stress, but further research is necessary to determine whether this mechanism is used in vivo.