RNA-Seq analysis on ets1 mutant embryos of Xenopus tropicalis identifies microseminoprotein beta gene 3 as an essential regulator of neural crest migration.

The proto-oncogeneets1is highly expressed in the pre-migratory and migratory neural crest (NC), and has been implicated in the delamination and migration of the NC cells. To identify the downstream target genes of Ets1 in this process, we did RNA sequencing (RNA-Seq) on wild-type andets1mutantX. tropicalisembryos. A list of genes with significantly differential expression was obtained by analyzing the RNA-Seq data. We validated the RNA-Seq data by quantitative PCR, and examined the expression pattern of the genes identified from this assay with whole mount in situ hybridization. A majority of the identified genes showed expression in migrating NC. Among them, the expression ofmicroseminoprotein beta gene 3(msmb3) was positively regulated by Ets1 in bothX. laevisandX. tropicalis. Knockdown ofmsmb3with antisense morpholino oligonucleotides or disruption ofmsmb3by CRISPR/Cas9 both impaired the migratory streams of NC. Our study identifiedmsmb3as an Ets1 target gene and uncovered its function in maintaining neural crest migration pattern.