title: Understanding the physical interactions in the FGF21/FGFR/β-Klotho complex: structural requirements and implications in FGF21 signaling.
abstract: The endocrine fibroblast growth factor 21 (FGF21) requires both fibroblast growth factor receptor (FGFR) and β-Klotho for signaling. In this study, we sought to understand the inter-molecular physical interactions in the FGF21/FGFR/β-Klotho complex by deleting key regions in FGFR1c or FGF21. Deletion of the D1 and the D1-D2 linker (the D1/linker region) from FGFR1c led to β-Klotho-independent receptor activation by FGF21, suggesting that there may be a direct interaction between FGF21 and the D1/linker region-deficient FGFR1c. Consistent with this, the extracellular portion of FGFR1c lacking the D1/linker region blocked FGF21 action in a reporter assay, presumably by binding to and sequestering FGF21 from acting on cell surface receptor complex. In addition, the D1/linker region-deficient FGFR1c had enhanced interaction with β-Klotho. Further, we demonstrated that deletion of the D1/linker region enhanced the formation of the FGF21/β-Klotho/FGFR1c ternary complex in both Biacore and asymmetrical flow field flow fractionation studies. Finally, we found that the N-terminus of FGF21 is involved in the interaction with FGFR1c and FGF21/β-Klotho/FGFR1c ternary complex formation. Taken together, our data suggest that the D1/linker region regulates both the FGF21/FGFR1c and FGFR1c/β-Klotho interaction, and a direct interaction of FGF21 with FGFR1c may be an important step in receptor-mediated FGF21 signaling.
authors.affiliation: Department of Metabolic Disorders, Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, USA. jyie@amgen.com
authors.forename: Junming
authors.initials: J
authors.lastname: Yie
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Liying
authors.initials: L
authors.lastname: Deng
authors.forename: Lei-Ting
authors.initials: LT
authors.lastname: Tam
authors.forename: Jennitte
authors.initials: J
authors.lastname: Stevens
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Richard
authors.initials: R
authors.lastname: Lindberg
authors.forename: Randy
authors.initials: R
authors.lastname: Hecht
authors.forename: Murielle
authors.initials: M
authors.lastname: Véniant
authors.forename: Ching
authors.initials: C
authors.lastname: Chen
authors.forename: Minghan
authors.initials: M
authors.lastname: Wang
mesh_terms: D002460:Cell Line; D005346:Fibroblast Growth Factors / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D000090265:Klotho Proteins; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C538995:KLB protein, human; D008565:Membrane Proteins; C414620:fibroblast growth factor 21; D005346:Fibroblast Growth Factors; D051496:Receptor, Fibroblast Growth Factor, Type 1; D000090265:Klotho Proteins