Dissecting the Interaction of FGF8 with Receptor FGFRL1.

Lei Zhuang,Monique Vogel,Beat Trueb,Peter M Villiger

doi:10.3390/biom10101399

Lei Zhuang, Monique Vogel + Show 2 more

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https://doi.org/10.3390/biom10101399

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Journal: Biomolecules	Publication Date: Oct 1, 2020
Citations: 8	License type: CC BY 4.0

Affiliation: University of Bern, University Hospital of Bern

Abstract

In mammals, the novel protein fibroblast growth factor receptor-like 1 (FGFRL1) is involved in the development of metanephric kidneys. It appears that this receptor controls a crucial transition of the induced metanephric mesenchyme to epithelial renal vesicles, which further develop into functional nephrons. FGFRL1 knockout mice lack metanephric kidneys and do not express any fibroblast growth factor (FGF) 8 in the metanephric mesenchyme, suggesting that FGFRL1 and FGF8 play a decisive role during kidney formation. FGFRL1 consists of three extracellular immunoglobulin (Ig) domains (Ig1-Ig2-Ig3), a transmembrane domain and a short intracellular domain. We have prepared the extracellular domain (Ig123), the three individual Ig domains (Ig1, Ig2, Ig3) as well as all combinations containing two Ig domains (Ig12, Ig23, Ig13) in recombinant form in human cells. All polypeptides that contain the Ig2 domain (Ig123, Ig12, Ig23, Ig2) were found to interact with FGF8 with very high affinity, whereas all constructs that lack the Ig2 domain (Ig1, Ig3, Ig13) poorly interacted with FGF8 as shown by ELISA and surface plasmon resonance. It is therefore likely that FGFRL1 represents a physiological receptor for FGF8 in the kidney and that the ligand primarily binds to the Ig2 domain of the receptor. With Biacore experiments, we also measured the affinity of FGF8 for the different constructs. All constructs containing the Ig2 domain showed a rapid association and a slow dissociation phase, from which a KD of 2–3 × 10−9 M was calculated. Our data support the hypothesis that binding of FGF8 to FGFRL1 could play an important role in driving the formation of nephrons in the developing kidney.

Highlights

The fibroblast growth factor (FGF) signaling system controls many vital processes of our bodies, such as development, organogenesis, angiogenesis and wound healing [1,2,3,4]
Seven different constructs were prepared to study the interaction of the individual domains from fibroblast growth factor receptor-like 1 (FGFRL1) with FGF8 (Figure 1): The complete extracellular domain of FGFRL1 (Ig123), all combinations containing two Ig domains (Ig12, Ig23, Ig13) and all three individual Ig domains (Ig1, Ig2, Ig3)
It was confirmed and quantitated in this publication by enzyme-linked immunosorbent assay (ELISA) where FGFRL1 bound to FGF8 immobilized on a microtiter plate (Figure 3), and by surface plasmon resonance where FGFRL1 interacted with FGF8, which had been covalently attached to the surface of a Biosensor chip (Figure 4)

Summary

Introduction

The fibroblast growth factor (FGF) signaling system controls many vital processes of our bodies, such as development, organogenesis, angiogenesis and wound healing [1,2,3,4]. The system consists of 22 different FGF ligands and 4 different fibroblast growth factor receptors (FGFRs). Together with the heparan sulfate, they interact with the receptors and induce their dimerization. A complex of two FGFs, two FGFRs and two heparan sulfate chains appears to be the active signaling complex at the cell membrane [4]. Once activated the receptors use at least four pathways to transmit the signal, namely the MAP kinase pathway, the PI3K/Akt pathway, the Jak/Stat pathway and the PLCγ pathway [1,2,3,4]

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