Bmper And MicroRNA-23a Act In The Development Of Craniofacial Cartilage And The Construction Of Nkx2.3 Transgenic Zebrafish

Craniofacial malformation is a common congenital birth defect usually associated with craniofacial cartilage and bone. BMP signaling pathway and microRNAs play a critical role in the development of zebrafish embryos. Although some regulators in BMP signaling pathway and microRNAs have been found to be implicated in the process of chondrogenesis, we know little about their function in the cartilage development.Bmper is an extracellular modulator in BMP signaling pathway. Diaphonospondylodysostosis (DSD) is a rare, recessively inherited, lethal skeletal dysplasia, which is related to the mutation of bmper gene, characterized by severe spinal ossification, segmentation defects, and renal cystic dysplasia with nephrogenic rests. We showed that bmper is highly enriched in the pharyngeal region of zebrafish, and its inactivation results in severe loss of craniofacial cartilage elements. We then constructed the bmper mutant using Cas9/gRNA technology, and hoped that similar phenotypes can be observed in the bmper mutant.miR-23a is a member of miR-23a-27a-24-2 cluster. We report that the knockdown of miR-23a results in severe defects of craniofacial cartilage elements. Further research demonstrates that miR-23a is required for the migration of neural crest cells and the differentiation of the pharyngeal chondrogenic progenitors. In addition, pharyngeal pouches is essential for the development of craniofacial cartilage elements. To study the development of pharyngeal pouches deeply, the tg(nkx2.3:CreERT2) and tg(nkx2.3:EGFP-CAAX) transgenic zebrafish lines are constructed.Taken together, we demonstrate that both bmper and miR-23a is essential for craniofacial skeleton development in zebrafish embryos. The subsequent studies reveal the mechanism, by which the two genes act during craniofacial cartilage formation, and provide scientific basis for the diagnosis and analysis of related diseases. We have successfully constructed the two transgenic lines, which are important tools for the study to pharyngeal pouch development.