The epigenetic regulator BAP1 is required before birth for differentiation and maintenance of the postnatal enteric nervous system in mice.

Epigenetic regulatory mechanisms are underappreciated but critical for enteric nervous system (ENS) development and maintenance. We discovered that fetal loss of the epigenetic regulator Bap1 in the ENS lineage causes severe postnatal bowel dysfunction and early death in Tyrosinase-Cre; Bap1fl/fl mice. Bap1-depleted ENS appears normal in neonates, however, by postnatal day 15 (P15), Bap1-deficient enteric neurons are largely absent from the small and large intestine of Tyrosinase-Cre; Bap1fl/fl mice. Bowel motility becomes markedly abnormal with disproportionate loss of cholinergic neurons. Single-cell RNA sequencing at P5 shows that fetal Bap1 loss inTyrosinase-Cre; Bap1fl/fl mice markedly alters the composition and relative proportions of enteric neuron subtypes. In contrast, postnatal deletion of Bap1 did not cause enteric neuron loss or impaired bowel motility. These findings suggest that BAP1 is critical for postnatal enteric neuron differentiation and for enteric neuron survival. Overall design: Whole cell enteric neuron isolation from P5 mouse colon was performed by extracting the muscularis layer from full-length colons from P5 Bap1 fl/fl; Tyr-Cre +; R26 TdT/TdT and Bap1 wt/wt; Tyr-Cre +; R26 TdT/TdT pups. P5 Tyr-Cre lineage cells from the colon muscularis were sorted using fluorescence-activated cell sorting (FACS) for presence of TdTomato signal and analyzed using scRNAseq.