Insights into binding of S100 proteins to scavenger receptors: class B scavenger receptor CD36 binds S100A12 with high affinity

Abstract

The EF-hand type calcium-binding protein S100A12 exerts numerous intra- and extracellular functions of (patho)physiological relevance. Therefore, receptors of S100A12 are of high interest for research and clinical applications. Beside the extensively studied receptor for advanced glycation endproducts (RAGE), G-protein coupled receptors and more recently, scavenger receptors are suggested to be putative S100A12 receptors. Own findings and further information from the literature predestined CD36, a class B scavenger receptor, as promising candidate. To substantiate or prove against this hypothesis, this study aimed at investigation of interaction of S100A12 and CD36 on molecular and cellular level by the use of surface plasmon resonance (SPR), radio- and fluorescence-tracer-based cell binding, and cell activation experiments. S100A12 revealed binding affinity to CD36 in the low nanomolar range, essentially, at the CD36 thrombospondin-1 binding site. Additionally, S100A12-mediated translocation of CD36 to the membrane and elevation of both CD36 and peroxisome proliferator-activated receptor γ (PPARγ) expression was observed, which suggest a potential regulatory function of S100A12–CD36 interaction.