Ikaros negatively regulates inducible nitric oxide synthase expression in macrophages: Involvement of Ikaros phosphorylation by casein kinase 2

• Published in: Cellular and molecular life sciences : CMLS 2008-10, Vol.65 (20), p.3290-3303
• Main Authors: Cho, S.-J, Huh, J.-E, Song, J, Rhee, D.-K, Pyo, S
• Format: Article
• Language: English
• Subjects: Acetylation - drug effects; Animals; Binding Sites; Biochemistry; Biomedical and Life Sciences; Biomedicine; Casein Kinase II - metabolism; Cell Biology; Cell Line; Cell Nucleus - drug effects; Cell Nucleus - enzymology; Deoxyribonucleic acid; DNA; Down-Regulation - drug effects; Enzyme Induction - drug effects; Enzymes; Histones - metabolism; Ikaros Transcription Factor - metabolism; Interferon-gamma - pharmacology; Kinases; Life Sciences; Lipopolysaccharides - pharmacology; Lymphocytes; Macrophages - drug effects; Macrophages - enzymology; Mice; Molecular biology; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide Synthase Type II - biosynthesis; Nitric Oxide Synthase Type II - genetics; Nitric Oxide Synthase Type II - metabolism; Phosphorylation - drug effects; Promoter Regions, Genetic; Protein Binding - drug effects; Protein Transport - drug effects; Recombinant Proteins; Research Article
• ISSN: 1420-682X; 1420-9071
• DOI: 10.1007/s00018-008-8332-7

Ikaros is known as a critical regulator of lymphocyte development. We examined the regulatory role of Ikaros in LPS/IFN-γ-induced inducible nitric oxide synthase (iNOS) expression by macrophages. Our results showed that IK6 (Ikaros dominant negative isoform) induction increases the iNOS expression. Ikaros DNA binding activity on the iNOS promoter was decreased, and a mutation of the Ikaros-binding site on the iNOS promoter resulted in an increase in LPS/IFN-γ-induced iNOS expression. LPS/IFN-γ increased the histone (H3) acetylation on the Ikaros DNA binding site. These results suggest that Ikaros acts as a negative regulator on iNOS expression. Treatment with a casein kinase 2 (CK2) inhibitor reversed LPS/IFN-γ-induced decrease in Ikaros DNA binding activity. Moreover, overexpression of kinase-inactive CK2 decreased iNOS expression and a significant amount of CK2α1 translocated into the nucleus in LPS/IFN-γ-treated cells. Overall, these data indicate that LPS/IFN-γ decreases the Ikaros DNA binding activity via the CK2 pathway, resulting in an increase of iNOS expression.