EFTUD2 gene deficiency disrupts osteoblast maturation and inhibits chondrocyte differentiation via activation of the p53 signaling pathway

Jing Wu,Lishun Wang,Yu An,You He,Feihong Luo,Qiang Li,Yi Yang,Xu Wang,Chengjun Sun

doi:10.1186/s40246-019-0238-y

Abstract

BackgroundMandibulofacial dysostosis with microcephaly (MFDM) is characteristic of multiple skeletal anomalies comprising craniofacial anomalies/dysplasia, microcephaly, dysplastic ears, choanal atresia, and short stature. Heterozygous loss of function variants of EFTUD2 was previously reported in MFDM; however, the mechanism underlying EFTUD2-associated skeletal dysplasia remains unclear.ResultsWe identified a novel frameshift variant of EFTUD2 (c.1030_1031delTG, p.Trp344fs*2) in an MFDM Chinese patient with craniofacial dysmorphism including ear canal structures and microcephaly, mild intellectual disability, and developmental delay. We generated a zebrafish model of eftud2 deficiency, and a consistent phenotype consisting of mandibular bone dysplasia and otolith loss was observed. We also showed that EFTUD2 deficiency significantly inhibited proliferation, differentiation, and maturation in human calvarial osteoblast (HCO) and human articular chondrocyte (HC-a) cells. RNA-Seq analysis uncovered activated TP53 signaling with increased phosphorylation of the TP53 protein and upregulation of five TP53 downstream target genes (FAS, STEAP3, CASP3, P21, and SESN1) both in HCO and in eftud2−/− zebrafish. Additionally, inhibition of p53 by morpholino significantly reduced the mortality of eftud2−/− larvae.ConclusionsOur results confirm a novel de novo variant of the EFTUD2 gene and suggest that EFTUD2 may participate in the maturation and differentiation of osteoblasts and chondrocytes, possibly via activation of the TP53 signaling pathway. Thus, mutations in this gene may lead to skeletal anomalies in vertebrates.

Highlights

Mandibulofacial dysostosis with microcephaly (MFDM) is characteristic of multiple skeletal anomalies comprising craniofacial anomalies/dysplasia, microcephaly, dysplastic ears, choanal atresia, and short stature
Adenotonsillectomy was performed, and he received surgical operation due to poorly formed structures of the external and middle ear, with external auditory canal stenosis on the left (Fig. 1b); by the age of 57 months, boundary developmental delay was confirmed with an intelligence quotient of 61 via the Wechsler Intelligence Scale for Children (WISC) test
A mental development abnormality related to a 214.11-kb duplication in the chromosomal region Xq28 (151,557,556-151,771,66 5(hg19)) involving the GABRA3, MIR105-1, MIR767, and MIR105-2 genes was found both in the proband and his normal mother using Array-CGH, while his father did not carry this variant

Summary

Introduction

Mandibulofacial dysostosis with microcephaly (MFDM) is characteristic of multiple skeletal anomalies comprising craniofacial anomalies/dysplasia, microcephaly, dysplastic ears, choanal atresia, and short stature. Heterozygous loss of function variants of EFTUD2 was previously reported in MFDM; the mechanism underlying EFTUD2-associated skeletal dysplasia remains unclear. The main clinical features are characteristic facial features and associated craniofacial malformations comprising malar and mandibular hypoplasia, micrognathia, dysplastic ears, cleft palate, choanal atresia, and microcephaly, which are consequences of. 95 EFTUD2 variants have been reported previously in MFDM patients, and most. We identified a novel de novo EFTUD2 null variant in a Chinese patient by whole-exome sequencing (WES) analysis. We generated a zebrafish line with eftud disruption to investigate the facial morphology, which presents mandibulofacial anomalies in patients, and more importantly, to determine the molecular mechanism of bone dysplasia

Methods

Results

Discussion

Conclusion