A systematic dissection of sequence elements determining β-Klotho and FGF interaction and signaling

• Published in: Scientific reports Vol. 8; no. 1; pp. 11045 - 15
• Main Authors: Shi, Sally Yu, Lu, Ya-Wen, Richardson, Jason, Min, Xiaoshan, Weiszmann, Jennifer, Richards, William G., Wang, Zhulun, Zhang, Zhongqi, Zhang, Jun, Li, Yang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23-07-2018; Nature Publishing Group
• Subjects: 13; 13/106; 38/70; 631/45/612/1237; 631/80/86; 82/103; 82/58; 82/80; 82/83; 96/109; 96/95; Alanine; Arginine; Binding sites; Deuterium; Fibroblast growth factor receptors; Glucose metabolism; Growth factors; Humanities and Social Sciences; Klotho protein; Ligands; Lipid metabolism; Mass spectrometry; Mass spectroscopy; Membrane proteins; multidisciplinary; Mutagenesis; Proteins; Science; Science (multidisciplinary); Signal transduction
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-29396-5

Endocrine fibroblast growth factors (FGFs) require Klotho transmembrane proteins as necessary co-receptors to activate FGF receptor (FGFR) signaling. In particular, FGF19 and FGF21 function through β-Klotho to regulate glucose and lipid metabolism. Recent research has focused on elucidating how these two FGFs interact with β-Klotho and FGFRs to activate downstream signaling. In this study, using hydrogen deuterium exchange coupled to mass spectrometry (HDX-MS), we identified regions on the β-Klotho protein that likely participate in ligand interaction, and vice versa. Alanine and arginine mutagenesis were carried out to further probe the contributions of individual residues to receptor/ligand interactions. Using biochemical and cell-based signaling assays with full-length proteins, we show that both the KL1 and KL2 domains of β-Klotho participate in ligand interaction, and these binding sites on β-Klotho are shared by FGF19 and FGF21. In addition, we show that two highly conserved regions in the C-terminal tail of FGF19 and FGF21 are responsible for interaction with the co-receptor. Our results are consistent with recent publications on the crystal structures of the Klotho proteins and provide insight into how endocrine FGFs interact with co-receptors for signal transduction.