Molecular basis for the action of a dietary flavonoid revealed by the comprehensive identification of apigenin human targets

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 24; pp. E2153 - E2162
• Main Authors: Arango, Daniel, Morohashi, Kengo, Yilmaz, Alper, Kuramochi, Kouji, Parihar, Arti, Brahimaj, Bledi, Grotewold, Erich, Doseff, Andrea I
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 11-06-2013; National Acad Sciences
• Series: PNAS Plus
• Subjects: Alternative Splicing - drug effects; Amino Acid Sequence; Apigenin - metabolism; Apigenin - pharmacology; Base Sequence; Biological Sciences; Biological Transport - drug effects; Cell Line, Tumor; Cell Membrane - metabolism; Diet; Dietary supplements; Enzyme Activation - drug effects; Flavonoids - metabolism; Flavonoids - pharmacology; Genes; GTP Phosphohydrolases - genetics; GTP Phosphohydrolases - metabolism; HeLa Cells; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - chemistry; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - genetics; Heterogeneous-Nuclear Ribonucleoprotein Group A-B - metabolism; Humans; Metabolism; Molecular Sequence Data; Molecules; Peptide Library; Phytochemicals; PNAS Plus; Protein Binding; Protein Multimerization - drug effects; Ribonucleic acid; RNA; RNA Stability - drug effects; RNA Transport - drug effects; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Analysis, DNA; FRET; cancer; inflammation; nanosensor
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1303726110

Flavonoids constitute the largest class of dietary phytochemicals, adding essential health value to our diet, and are emerging as key nutraceuticals. Cellular targets for dietary phytochemicals remain largely unknown, posing significant challenges for the regulation of dietary supplements and the understanding of how nutraceuticals provide health value. Here, we describe the identification of human cellular targets of apigenin, a flavonoid abundantly present in fruits and vegetables, using an innovative high-throughput approach that combines phage display with second generation sequencing. The 160 identified high-confidence candidate apigenin targets are significantly enriched in three main functional categories: GTPase activation, membrane transport, and mRNA metabolism/alternative splicing. This last category includes the heterogeneous nuclear ribonucleoprotein A2 (hnRNPA2), a factor involved in splicing regulation, mRNA stability, and mRNA transport. Apigenin binds to the C-terminal glycine-rich domain of hnRNPA2, preventing hnRNPA2 from forming homodimers, and therefore, it perturbs the alternative splicing of several human hnRNPA2 targets. Our results provide a framework to understand how dietary phytochemicals exert their actions by binding to many functionally diverse cellular targets. In turn, some of them may modulate the activity of a large number of downstream genes, which is exemplified here by the effects of apigenin on the alternative splicing activity of hnRNPA2. Hence, in contrast to small-molecule pharmaceuticals designed for defined target specificity, dietary phytochemicals affect a large number of cellular targets with varied affinities that, combined, result in their recognized health benefits.