Structural relationships of the flavonoid apigenin and hnRNPA2 define the role of plant phytochemicals in the regulation of alternative splicing

• Grant number: 13/50362-6
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2013
• End date: September 30, 2014
• Field of knowledge: Biological Sciences - Biophysics - Molecular Biophysics
• Agreement: Ohio State University
• Principal Investigator: Roberto Kopke Salinas
• Grantee: Roberto Kopke Salinas
• Principal researcher abroad: Andrea I. Doseff
• Institution abroad: Ohio State University, Columbus, United States
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 11/07777-5 - Cyclic di-GMP signaling and the Type IV macromolecule secretion system in Xanthomonas citri, AP.TEM

Abstract

Flavonoids are emerging as potential dietary anti-carcinogenic and anti-inflammatory compounds as illustrated in vitro in several systems and in vivo in animal models1. Yet, their mechanisms of action remain poorly characterized. Recently, we describe the identification of human cellular targets of apigenin, a flavonoid abundantly present in fruits and vegetables. We found that apigenin binds to the Heterogeneous Nuclear RiboNucleoProtein A2 (hnRNPA2), a protein involved in splicing regulation, mRNA stability, and mRNA transport2. In addition, high leveis of HnRNPA2 have been associated with carcinogenesis and hnRNPA2 is a cellular markerfor cancer progression3-6. Our studies showed that apigenin alters the splicing isoforms present in cancer cells making them to resemble non-carcinogeneic cells (Arango et al, 2013. PNAS). In addition, we found that apigenin binds to the C- terminal Glycine Rich Domain (GRD) of hnRNPA2, preventing hnRNPA2 from forming homodimers, but has no interactions with the N-terminal RNA binding domain. Previous studies showed that homodimer formation is necessary for the binding of hnRNPA2 to RNA7. However, what is lacking is the understanding on how apigenin regulates hnRNPA2 structurally, altering its function. In order to answer this question we propose to use high- resolution Nuclear Magnetic Resonance (NMR) spectroscopy in order to evaluate how apigenin recognizes hnRNPA2 at the atomic level. (AU)