Riboflavin kinase couples TNF receptor 1 to NADPH oxidase

• Published in: Nature (London) Vol. 460; no. 7259; pp. 1159 - 1163
• Main Authors: Yazdanpanah, Benjamin, Wiegmann, Katja, Tchikov, Vladimir, Krut, Oleg, Pongratz, Carola, Schramm, Michael, Kleinridders, Andre, Wunderlich, Thomas, Kashkar, Hamid, Utermöhlen, Olaf, Brüning, Jens C., Schütze, Stefan, Krönke, Martin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.08.2009; Nature Publishing Group
• Subjects: Animals; Apoptosis; Binding sites; Biological and medical sciences; Cell Line; Cells; Cytochrome b Group - metabolism; E coli; Enzyme Activation; Fibroblasts; Flavin Mononucleotide - metabolism; Flavin-Adenine Dinucleotide - biosynthesis; Flavin-Adenine Dinucleotide - metabolism; Fundamental and applied biological sciences. Psychology; Fundamental immunology; General aspects. Ontogeny. Phylogeny; HeLa Cells; Humanities and Social Sciences; Humans; Immunobiology; Isoenzymes - chemistry; Isoenzymes - metabolism; Kinases; letter; Membrane Glycoproteins - metabolism; Mice; multidisciplinary; NADH, NADPH Oxidoreductases - metabolism; NADPH Oxidase 1; NADPH Oxidase 2; NADPH Oxidases - chemistry; NADPH Oxidases - metabolism; Neurons; Nitric oxide; Oxidases; Phosphotransferases; Phosphotransferases (Alcohol Group Acceptor) - deficiency; Phosphotransferases (Alcohol Group Acceptor) - genetics; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Physiological aspects; Protein Binding; Protein Structure, Tertiary; Reactive Oxygen Species - metabolism; Receptors, Tumor Necrosis Factor, Type I - chemistry; Receptors, Tumor Necrosis Factor, Type I - metabolism; Science; Science (multidisciplinary); Translocation; Tumor necrosis factor; Vitamin B2
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature08206

Riboflavin kinase: linking TNF receptor to NAPDH oxidation Riboflavin kinase has been identified as a novel interacting partner for the death domain of receptor-1 for tumour necrosis factor (TNF-R1). It is required to recruit to and functionally couple p22 phox to TNF-R1. As p22 phox is the catalytic subunit of NADPH oxidases Nox1–4, this has general implications for TNF-induced NADPH oxidase activation and reactive oxygen species (ROS) production by many cell types and tissues. These findings may also be of relevance to the role of ROS in host defence and in the pathogenesis of many diseases including inflammation or atherosclerosis. Riboflavin kinase is shown to couple TNF receptor 1 to reactive oxygen production by the FAD-dependent NADPH oxidase. Reactive oxygen species (ROS) produced by NADPH oxidase function as defence and signalling molecules related to innate immunity and various cellular responses 1 , 2 . The activation of NADPH oxidase in response to plasma membrane receptor activation depends on the phosphorylation of cytoplasmic oxidase subunits, their translocation to membranes and the assembly of all NADPH oxidase components 3 . Tumour necrosis factor (TNF) is a prominent stimulus of ROS production, but the molecular mechanisms by which TNF activates NADPH oxidase are poorly understood. Here we identify riboflavin kinase (RFK, formerly known as flavokinase 4 ) as a previously unrecognized TNF-receptor-1 (TNFR1)-binding protein that physically and functionally couples TNFR1 to NADPH oxidase. In mouse and human cells, RFK binds to both the TNFR1-death domain and to p22 phox , the common subunit of NADPH oxidase isoforms. RFK-mediated bridging of TNFR1 and p22 phox is a prerequisite for TNF-induced but not for Toll-like-receptor-induced ROS production. Exogenous flavin mononucleotide or FAD was able to substitute fully for TNF stimulation of NADPH oxidase in RFK-deficient cells. RFK is rate-limiting in the synthesis of FAD, an essential prosthetic group of NADPH oxidase. The results suggest that TNF, through the activation of RFK, enhances the incorporation of FAD in NADPH oxidase enzymes, a critical step for the assembly and activation of NADPH oxidase.