CHD7 regulates definitive endodermal and mesodermal development from human embryonic stem cells

CHD7 encodes an ATP-dependent chromodomain helicase DNA binding protein; mutations in this gene lead to multiple developmental disorders, including CHARGE (Coloboma, Heart defects, Atresia of the choanae, Retardation of growth and development, Genital hypoplasia, and Ear anomalies) syndrome. How the mutations cause multiple defects remains largely unclear. Embryonic definitive endoderm (DE) generates the epithelial compartment of vital organs such as the thymus, liver, pancreas, and intestine.

In this study, we used the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technique to delete the CHD7 gene in human embryonic stem cells (hESCs) to generate CHD7 homozygous mutant (CHD7^-/-), heterozygous mutant (CHD7^+/-), and control wild-type (CHD7^+/+) cells. We then investigated the ability of the hESCs to develop into DE and the other two germ layers, mesoderm and ectoderm in vitro. We also compared global gene expression and chromatin accessibility among the hESC-DE cells by RNA sequencing (RNA-seq) and the assay for transposase-accessible chromatin with sequencing (ATAC-seq).

We found that deletion of CHD7 led to reduced capacity to develop into DE and mesoderm in a dose-dependent manner. Loss of CHD7 led to significant changes in the expression and chromatin accessibility of genes associated with several pathways. We identified 40 genes that were highly down-regulated in both the expression and chromatin accessibility in CHD7 deleted hESC-DE cells.

CHD7 is critical for DE and mesodermal development from hESCs. Our results provide new insights into the mechanisms by which CHD7 mutations cause multiple congenital anomalies.