Abstract
DNA damage response (DDR) genes orchestrating the network of DNA repair, cell cycle control, are essential for the rapid proliferation of neural progenitor cells. To date, the potential association between specific DDR genes and the risk of human neural tube defects (NTDs) has not been investigated. Using whole-genome sequencing and targeted sequencing, we identified significant enrichment of rare deleterious
RAD9B
variants in spina bifida cases compared to controls (8/409 vs. 0/298;
p
= .0241). Among the eight identified variants, the two frameshift mutants and p.Gln146Glu affected
RAD9B
nuclear localization. The two frameshift mutants also decreased the protein level of
RAD9B
. p.Ser354Gly, as well as the two frameshifts, affected the cell proliferation rate. Finally, p.Ser354Gly, p.Ser10Gly, p.Ile112Met, p.Gln146Glu, and the two frameshift variants showed a decreased ability for activating JNK phosphorylation.
RAD9B
knockdowns in human embryonic stem cells profoundly affected early differentiation through impairing
PAX6
and
OCT4
expression.
RAD9B
deficiency impeded in vitro formation of neural organoids, a 3D cell culture model for human neural development. Furthermore, the RNA-seq data revealed that loss of
RAD9B
dysregulates cell adhesion genes during organoid formation. These results represent the first demonstration of a DDR gene as an NTD risk factor in humans.
