Nucleoporin 62-Like Protein Is Required for the Development of Pharyngeal Arches through Regulation of Wnt/β-Catenin Signaling and Apoptotic Homeostasis in Zebrafish

We have previously observed the predominant expression of nucleoporin 62-like (Nup62l) mRNA in the pharyngeal region of zebrafish, which raises the question whether Nup62l has important implications in governing the morphogenesis of pharyngeal arches (PA) in zebrafish. Herein, we explored the functions of Nup62l in PA development. The disruption of Nup62l with a CRISPR/Cas9-dependent gene knockout approach led to defective PA, which was characterized by a thinned and shortened pharyngeal region and a significant loss of pharyngeal cartilages. During pharyngeal cartilage formation, prechondrogenic condensation and chondrogenic differentiation were disrupted in homozygous nup62l-mutants, while the specification and migration of cranial neural crest cells (CNCCs) were unaffected. Mechanistically, the impaired PA region of nup62l-mutants underwent extensive apoptosis, which was mainly dependent on activation of p53-dependent apoptotic pathway. Moreover, aberrant activation of a series of apoptotic pathways in nup62l-mutants is closely associated with the inactivation of Wnt/β-catenin signaling. Thus, these findings suggest that the regulation of Wnt/β-catenin activity by Nup62l is crucial for PA formation in zebrafish.