FGF23 and Fetuin-A Interaction and Mesenchymal Osteogenic Transformation.

Deborah Mattinzoli,Francesca Elli,Mario Barilani,Paola Andreetta,Giovanna Mantovani,Masami Ikehata,Piergiorgio Messa,Koji Tsugawa,Carlo Alfieri,Lorenza Lazzari

doi:10.3390/ijms20040915

Abstract

Recently, we found a strict bone association between Fibroblast growth factor 23 (FGF23) and Fetuin-A, both involved in cardiovascular and mineral bone disorders. In this study, an uninvestigated bone marrow positivity for both was found. Though the role of exogenous FGF23 on mesenchymal cells (MSCs) was reported, no information is as yet available on the possible production of this hormone by MSCs. To further analyze these uninvestigated aspects, we studied human primary cells and mouse and human cell lines by means of immunostaining, qRT-PCR, enzyme linked immunosorbent assays, chromatin immunoprecipitation, transfection, and a streamlined approach for the FGF23–Fetuin-A interaction called Duolink proximity ligation assay. Mesenchymal cells produce but do not secrete FGF23 and its expression increases during osteo-differentiation. Fibroblast growth factor 23 is also involved in the regulation of Fetuin-A by binding directly to the Fetuin-A promoter and then activating its transcription. Both FGF23 overexpression and addition induced an upregulation of Fetuin-A in the absence of osteo-inducer factors. Fibroblast growth factor 23 and Fetuin-A promoter were increased by osteo-inducer factors with this effect being abolished after FGF23 silencing. In conclusion, both FGF23 and Fetuin-A are present and strictly linked to each other in MSCs with FGF23 driving Fetuin-A production. This mechanism suggests a role for these two proteins in the osteoblast differentiation.

Highlights

Over the last decade, research has increasingly focused on mesenchymal cells (MSCs) as potentially useful tools in medicine
Fetuin-A and Fibroblast growth factor 23 (FGF23) Interaction in Mouse, in Primary Human Cells and Tibial Mouse Tissue We explored if FGF23/Fetuin-A co-localization in MSCs is characterized by a strict interaction either in conditions without osteo-induction or during osteogenic differentiation
Our study suggests that FGF23 is produced by MSCs cells, though not released

Summary

Introduction

Research has increasingly focused on mesenchymal cells (MSCs) as potentially useful tools in medicine. MSCs have manifold activities, including the capacity for migration to injury sites for tissue regeneration, the self-renewal aptitude, and both the high ability for cell differentiation and modulatory regulation of the inflammatory system [1,2,3,4,5]. Osteoblasts are defined by their ability to synthesize mineralized matrix proteins such as collagen Type I (COLIαI), osteocalcin (BGLAP), and alkaline phosphatase activity (ALP) by their responsiveness to specific hormones and growth factors and their position in the bone tissue [7,8]. Osteocytes (OS), derived from OBs, are trapped in the bone matrix and characterized by several long processes creating a complex network with the other bone cells. Osteocytes play the role of the orchestrator of the bone remodeling events, organizing both resorption and formation, representing the major cells responding to mechanical stimuli [9,10,11,12]

Objectives

Methods

Results

Conclusion