Role of Nrf2 in Regulation of Expression of CYP 2C11 and CYP 4X1 Epoxygenases and Production of Epoxyeicosatrienoic Acids (EETs) in the Rat Brain

Abstract

Nuclear factor (erythroid‐derived 2)‐like‐2 (Nrf2) is the master antioxidant and cell‐protective transcription factor native in the rat brain. The CYP epoxygenases 2C11 and 4X1 are expressed in the brain and metabolize arachidonic acid to epoxyeicosatrienoic acids (EETs) that are known to induce cerebral vasodilation and increase nutritive blood flow to areas of heightened neuronal activity and also provide antioxidant and anti‐inflammatory actions. The influence of Nrf2 gene deletion on CYP 2C11 and 4X1 epoxygenase expression and activity in the rat brain is not known. In this study we used isoform specific antibodies and Western blotting to determine the effect of Nrf2 gene knockout (KO) on the expression of proteins for CYP 2C11 and CYP 4X1 epoxygenases in whole brain and isolated cerebral arteries. We also measured the production of epoxyeicosatrienoic acids (EETs) in homogenates of whole brain and isolated cerebral arteries of Nrf2 wild type (WT) and Nrf2 KO rats. CYP epoxygenase expression and EETs production were reduced in whole brain and arteries of the NRF2 KO rats compared to WT controls. These findings indicate that knockout of the Nrf2 gene leads to a marked reduction in the expression of proteins for CYP 2C11 and CYP 4X1 epoxygenases and in the production of 8, 9‐, 11,12‐ and 14,15‐EETs compared to those measured in the Nrf2 WT rat brain issues and cerebral arteries. The results of the current study suggest that CYP 2C11 and 4X1 epoxygenases may be components of the Nrf2‐induced phase 2 genes that are known to limit oxidative stress and provide cellular defense in the brain. We postulate that Nrf2 may regulate functions of the cerebral circulation and provide protection against oxidative stress, in part, via modulation of the expression level of CYP 2C11 and 4X1 epoxygenase proteins and the production of EETs.Support or Funding InformationNIH R01 #HL‐128242 and NIH #R21‐OD018309