The aryl hydrocarbon receptor (AHR) and NF-E2 p45-related factor (NRF2) are two distinct transcription factors involved in the regulation of drug-metabolizing enzymes. Increasing evidence from several studies implies that AHR and NRF2 have direct links, but the molecular mechanism remains unknown. In this work we demonstrate for the first time that Nrf2 gene transcription is directly modulated by AHR activation. DNA sequence analyses of the mouse Nrf2 promoter revealed one xenobiotic response element (XRE)-like element (XREL1) located at ؊712 and two additional XRE-like elements located at ؉755 (XREL2) and ؉850 (XREL3). Functional analysis using luciferase assay showed that XREL1, XREL2, and XREL3 are all inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment, with XREL2 being the most potent. The functionality of these XRE-like elements was further confirmed by mutagenesis and gel shift experiments. Finally, we used chromatin immunoprecipitation assay to show a direct binding of AHR to the Nrf2 promoter. Cells with silenced AHR expression using siRNA also lost NRF2 mRNA induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin. These new data position NRF2-antioxidant response element downstream in the AHR-XRE pathway. Moreover, direct regulation of NRF2 by AHR contributes to couple phase I and II enzymes into an integrated system facilitating more effective xenobiotic and carcinogen detoxification.

Oxidative stress plays an important role in cerebral ischemia–reperfusion injury. Dimethyl fumarate (DMF) and its primary metabolite monomethyl fumarate (MMF) are antioxidant agents that can activate the nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and induce the expression of antioxidant proteins. Here, we evaluated the impact of DMF and MMF on ischemia-induced brain injury and whether the Nrf2 pathway mediates the effects provided by DMF and MMF in cerebral ischemia–reperfusion injury. Using a mouse model of transient focal brain ischemia, we show that DMF and MMF significantly reduce neurological deficits, infarct volume, brain edema, and cell death. Further, DMF and MMF suppress glial activation following brain ischemia. Importantly, the protection of DMF and MMF was mostly evident during the subacute stage and was abolished in Nrf2−/− mice, indicating that the Nrf2 pathway is required for the beneficial effects of DMF and MMF. Together, our data indicate that DMF and MMF have therapeutic potential in cerebral ischemia–reperfusion injury and their protective role is likely mediated by the Nrf2 pathway.Electronic supplementary materialThe online version of this article (doi:10.1007/s12975-016-0496-0) contains supplementary material, which is available to authorized users.

The membrane glycoprotein CD36 is involved in platelet aggregation, inhibition of angiogenesis, atherosclerosis, and sequestration of malaria-parasitized erythrocytes. In this study, immunoprecipitations with anti-CD36 antibodies were performed to identify proteins that associate with CD36 in the platelet membrane. Platelets were solubilized in 1% Triton X-100, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), Brij 96, or Brij 99, and the proteins that coprecipitated with CD36 were identified by peptide mass spectrometry and Western blotting. The tetraspanin protein CD9 and the integrins ␣IIb␤3 and ␣6␤1 specifically coprecipitated with CD36 from platelets that were solubilized in CHAPS and Brij 99 but not from platelets that were solubilized in Triton X-100. Only CD9 is coprecipitated with CD36 from platelets that were solubilized in Brij 96. Reciprocal immunoprecipitations with antibodies to CD9, ␣6, ␣IIb, or ␤3 from Brij 99-solubilized platelets coprecipitated CD36. Coprecipitation of CD36, CD9, and ␣6␤1 was also observed on platelets from a patient with Glanzmann thrombasthenia, indicating that ␣IIb␤3 is not required for the other proteins to associate. Colocalization of ␣6 and CD36, of CD9 and CD36, and of ␣6 and CD9 was observed on intact platelets prior to solubilization, using double immunofluorescence microscopy. These data indicate that CD36 associates with CD9 and integrins on human blood platelets. These associated proteins may mediate or participate in some of the diverse biological functions of CD36. ( IntroductionCD36 is a transmembrane glycoprotein that has been shown to participate in multiple biological functions, including platelet aggregation, inhibition of angiogenesis, uptake of oxidized lowdensity lipoprotein and long-chain fatty acids, cell adhesion, and the sequestration of Plasmodium falciparum-infected erythrocytes. 1 As a scavenger receptor, CD36 is involved in the uptake of oxidized low-density lipoprotein by macrophages and the formation of foam cells during arterial atherogenesis. [2][3][4] As a thrombospondin 1 (TSP-1) receptor on platelets, CD36 is involved in reinforcing the molecular bridge that is formed between platelets by fibrinogen and the ␣IIb␤3 integrin during aggregation. [5][6][7] This model is supported by observations that antibodies to TSP-1 inhibit platelet aggregation (for review see Lawler 8 ). As a TSP-1 receptor on endothelial cells, CD36 reportedly mediates the antiangiogenic effect of TSP-1. 9 The effect of TSP-1 on angiogenesis involves the inhibition of endothelial cell migration and the induction of apoptosis. The latter effect reportedly involves the activation of p38 mitogen-activated protein kinase and caspases. 9 The original fluid mosaic model of the plasma membrane visualized membrane proteins as free-floating entities in a sea of lipids. 10 Data indicate that the plasma membrane is far less homogeneous than this model implies. [10][11][12][13][14] Membrane proteins and lipids associate to form functional domains in the plasma membra...