Meclozine Attenuates the MARK Pathway in Mammalian Chondrocytes and Ameliorates FGF2-Induced Bone Hyperossification in Larval Zebrafish.

Genta Takemoto,Shiro Imagama,Takaaki Okamoto,Toyofumi Fengshi Chen-Yoshikawa,Toshinari Ito,Hiromichi Ebi,Yasuyuki Hosono,Yuki Matsuura,Hiroshi Kitoh,Kinji Ohno,Masaki Matsushita,Chieko Takashima

doi:10.3389/fcell.2021.694018

Abstract

Meclozine has been developed as an inhibitor of fibroblast growth factor receptor 3 (FGFR3) to treat achondroplasia (ACH). Extracellular signal regulated kinase (ERK) phosphorylation was attenuated by meclozine in FGF2-treated chondrocyte cell line, but the site of its action has not been elucidated. Although orally administered meclozine promoted longitudinal bone growth in a mouse model of ACH, its effect on craniofacial bone development during the early stage remains unknown. Herein, RNA-sequencing analysis was performed using murine chondrocytes from FGF2-treated cultured tibiae, which was significantly elongated by meclozine treatment. Gene set enrichment analysis demonstrated that FGF2 significantly increased the enrichment score of mitogen-activated protein kinase (MAPK) family signaling cascades in chondrocytes; however, meclozine reduced this enrichment. Next, we administered meclozine to FGF2-treated larval zebrafish from 8 h post-fertilization (hpf). We observed that FGF2 significantly increased the number of ossified vertebrae in larval zebrafish at 7 days post-fertilization (dpf), while meclozine delayed vertebral ossification in FGF2-induced zebrafish. Meclozine also reversed the FGF2-induced upregulation of ossified craniofacial bone area, including ceratohyal, hyomandibular, and quadrate. The current study provided additional evidence regarding the inhibitory effect of meclozine on the FGF2-induced upregulation of MAPK signaling in chondrocytes and FGF2-induced development of craniofacial and vertebral bones.

Highlights

Achondroplasia (ACH) is a common skeletal dysplasia with shortlimbed short stature caused by gain-of-function mutations in fibroblast growth factor receptor 3 (FGFR3) (Rousseau et al, 1994; Shiang et al, 1994)
We revealed that meclozine counteracted growth retardation in FGF2-induced embryonic tibiae by attenuating the mitogen-activated protein kinase (MAPK) family signaling cascades activated by FGF2 treatment in chondrocytes
A recent study reported that Fgfr3-deficient zebrafish showed craniofacial malformations associated with bone mineralization defects, abnormal hypertrophy, and disarrangement in the growth plate, similar to human CATSHL syndrome (Sun et al, 2020)

Summary

Introduction

Achondroplasia (ACH) is a common skeletal dysplasia with shortlimbed short stature caused by gain-of-function mutations in fibroblast growth factor receptor 3 (FGFR3) (Rousseau et al, 1994; Shiang et al, 1994). Most adult patients with ACH exhibit spinal canal stenosis (Fredwall et al, 2020). Stenoses of the foramen magnum and spinal canal can develop owing to the premature closure of the synchondroses of the cranial base and vertebral arch (Hecht et al, 1989; Horton et al, 2007). Loss-of-function mutations in FGFR3 cause camptodactyly, tall stature, scoliosis, and hearing loss syndrome (Toydemir et al, 2006). FGFR3 is a negative regulator of endochondral bone growth

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