The Murine Enteric Nervous System from a Genetics and Omics Perspective

Abstract

The enteric nervous system (ENS), otherwise known as the “gut brain”, resides in layers of the gut to sense and activate the passing of stool. Proper ENS development requires coordination of gene expression for ENS progenitor cells to migrate while cells left behind differentiate into neurons and glia. Perturbation in development of the ENS can cause gastrointestinal motility disorders such as Hirschsprung disease (HSCR), in which a variable length of the distal large intestine lacks enteric ganglia (aganglionosis). In addition, some HSCR patients have an atypical balance of enteric neuronal (EN) subtypes in their ganglionic intestine, which is thought to cause dysmotility after surgical resection of aganglionic colon. The Sox10Dom mouse model of HSCR has been shown to both replicate the variable length of aganglionosis that is seen among HSCR patients and the imbalance of EN subtypes in ganglionic intestine. In this dissertation, I utilize genetics and single cell omics techniques to: understand the diversity of murine ENs across adult and juvenile stages; identify loci and candidate genes that modify Sox10Dom aganglionosis length; and understand how deficits in Sox10 change chromatin accessibility and gene expression in the developing ENS to coordinate EN diversification. I first integrated single cell RNA-seq datasets of mouse ENs to gain consensus of EN subtypes across juvenile and adult stages. Through this analysis, I found novel putative subtypes of Nmu+ type two intrinsic primary afferent neurons. Second, I conducted a genome-wide SNP association analysis for aganglionic length on an extended pedigree of Sox10Dom mice followed by bulk and single cell omics analysis in relevant gut cell types to identify candidate genes Phox2b and Dach1 as putative modifiers of Sox10Dom aganglionosis. Third, I used single nucleus multiomics to capture wild type and Sox10Dom fetal gut ENS to identify a Sox10 gene regulatory network controlling EN diversification. These studies shed light on how gene expression controls ENS development, important knowledge for cell therapy treatments of HSCR disease.