Nrf2 regulates the alternative first exons of CD36 in macrophages through specific antioxidant response elements.
We previously demonstrated that Nrf2 regulates oxidized LDL-mediated CD36 expression in macrophages. The current study aimed to determine the mechanism of Nrf2-mediated macrophage CD36 induction. Treatment with the Nrf2 activator diethylmaleate, but not PPARgamma specific ligands, caused marked upregulation of CD36 in mouse macrophage RAW264.7 cells. Similarly, Nrf2 activators induced CD36 expression in bone marrow-derived macrophages in a Nrf2-dependent manner. Induced expression of the three alternative first exons of mouse CD36, deemed 1A, 1B, and 1C, occurred upon Nrf2 activation with exon1A mainly contributing to the CD36 expression. Four antioxidant response elements (AREs) lie within close proximity to these three exons, and chromatin immunoprecipitation assays demonstrated that two AREs upstream of exon1A, the distal 1A-ARE1, and the proximal 1A-ARE2, were Nrf2-responsive. Luciferase reporter assays conclusively demonstrated that 1A-ARE2 is the critical regulatory element for the Nrf2-mediated gene expression. Thus Nrf2 directly regulates CD36 gene expression by binding to 1A-ARE2.
Maruyama
Atsushi
A
Department of Stress Response Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan.
Tsukamoto
Saho
S
Nishikawa
Keizo
K
Yoshida
Aruto
A
Harada
Nobuhiko
N
Motojima
Kiyoto
K
Ishii
Tetsuro
T
Nakane
Akio
A
Yamamoto
Masayuki
M
Itoh
Ken
K
D000818:Animals; D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology; D015153:Blotting, Western; D018955:CD36 Antigens / Q000235:genetics*; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D005091:Exons; D005786:Gene Expression Regulation; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000502:physiology*; D020218:Response Elements / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000975:Antioxidants; D018955:CD36 Antigens; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse