iHuman Team At ShanghaiTech University Deciphers The First Human Frizzled Receptor Structure

Shanghai /PRNewswire/ - The Xu Laboratory at the iHuman Institute of ShanghaiTech University has deciphered the high-resolution crystal structure of the first human Frizzled receptor. As a gatekeeping protein in regulating the fundamental Wnt signaling in embryonic development and tumorigenesis, the Frizzled receptors (FZDs) have been cancer drug targets for decades without success. However, these results, which illustrate the unique architecture of Frizzled-4 in ligand-free state and explain the long-standing hurdle of identifying potent ligand for this family of receptors, will benefit basic and therapeutic research that could lead to important new drug discoveries. These new findings are published today in the advanced online edition of the journal Nature, titled "Crystal structure of Frizzled 4 receptor in ligand-free state" by Yang et al.

"In order to understand why no one has been able to develop good tool ligands or drug molecules for FZDs, we solved the intact transmembrane domain structure of Frizzled4 receptor (FZD4) at 2.4 angstrom resolution," said Fei Xu, Assistant Professor at iHuman Institute and the School of Life Science and Technology, ShanghaiTech University, and corresponding author of the study.

Surprising to the authors was the observation that the traditional orthosteric ligand binding site is very narrow and hydrophilic making it hard for small molecules to enter or bind. "These findings improve our understanding of the FZD ligand and signaling, and show that ligand design for this pocket may require special considerations that could be inspired by this crystal structure," said Fei Xu.

"To generate a more stable human FZD4 protein amenable for structure determination in the absence of a ligand, the team spent four years and screened hundreds of constructs, optimized purification procedures, and tried thousands of possible crystallization conditions," said Shifan Yang, postdoctoral fellow at iHuman Institute, and first author of the paper.

In addition to the discovery of a vacant pocket, this work also provides insight into a unique activation mechanism of the Frizzled family. "Such a remarkable structure provides a more accurate template to redirect the efforts on Frizzled drug discovery", said Raymond Stevens, Director of iHuman Institute, ShanghaiTech University.

Other co-authors of this paper come from ShanghaiTech University, the Van Andel Research Institute, and the University of Southern California.

Link to the full text: http://dx.doi.org/10.1038/s41586-018-0447-x