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The RelA/ cR el nuclear factor‐ κ B ( NF ‐ κ B) dimer, crucial for inflammation resolution, mediates the transcription of the key enzyme in melatonin synthesis in RAW 264.7 macrophages
Author(s) -
Muxel Sandra Marcia,
LaranjeiraSilva Maria Fernanda,
CarvalhoSousa Claudia Emanuelle,
FloeterWinter Lucile Maria,
Markus Regina P
Publication year - 2016
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/jpi.12321
Subject(s) - transcription factor , electrophoretic mobility shift assay , microbiology and biotechnology , nat , activator (genetics) , transcription (linguistics) , nf κb , biology , enhancer , chemistry , promoter , stat protein , gene expression , signal transduction , stat3 , biochemistry , gene , computer network , linguistics , philosophy , computer science
Lipopolysaccharide ( LPS ) modulates the transcription of the gene that codifies the enzyme arylalkylamine‐N‐acetyltransferase ( AA ‐ NAT ) through nuclear translocation of the transcription factor nuclear factor‐ κ ‐light‐chain‐enhancer of activated B cells ( NF ‐ κ B). AA ‐ NAT converts serotonin to N‐acetylserotonin, the ultimate precursor of melatonin. Activation of kappa B elements (aa‐nat‐ κ B), localized in the promoter (nat‐ κ B1 and nat‐ κ B2), leads to Aa‐nat transcription in RAW 264.7 macrophages. Competitive electrophoretic mobility shift assay ( EMSA ) with oligonucleotide probes corresponding to each of the two elements, as well as a NF ‐ κ B consensus corresponding probe, revealed different specificities for each κ B element. In addition, activator protein‐1 ( AP ‐1) as well as signal transducers and activator of transcription‐1 and 3 ( STAT ‐1; STAT ‐3) competed with NF ‐ κ B for binding to nat‐ κ B1, while only STAT ‐3 competed with NF ‐ κ B for binding to nat‐ κ B2. According to co‐immunoprecipitation (ChiP) assays, these two sites are able to distinguish NF ‐ κ B subunits. The sequence nat‐ κ B1 bound dimers containing p52, RelA, and cR el, while nat‐ κ B2 bound preferentially p50, p52, and RelA, and did not bind cR el. The expression of RelA and cR el is essential for the induction of Aa‐nat expression and melatonin synthesis. Considering that the expression of cR el is induced by the earlier expressed p50/RelA, the differential effects of NF ‐ κ B dimers may be intimately associated with the temporal regulation of inflammatory responses, with the resolution phase being associated with paracrine and autocrine melatonin effects. Such data suggest that the proven effects of exogenous melatonin in the resolution phase of inflammation are paralleled by the effects of locally synthesized melatonin in immune cells.