385 Conditional Genomic Deletion of Ano1 in Kit-Expressing Cells of Adult Mice Results in Loss of Slow Waves and Reduced Coordination of Ca2+ Transients in Myenteric Interstitial Cells of Cajal of the Small Intestine

In the enteric nervous system (ENS), glia outnumber neurons by 4 to 6-fold and form an extensive network throughout the gastrointestinal tract. Enteric glia are essential for normal gastrointestinal function and play roles in regulating epithelial barrier integrity, epithelial cell proliferation and neuronal support. While glial subtypes can be clearly distinguished in the central and peripheral nervous systems (CNS and PNS), it remains unknown whether similar glial diversity exists in the ENS. Because of their morphology and expression of Glial Fibrillary Acidic Protein (GFAP), until recently, enteric glia were thought to resemble astrocytes. We tested the hypothesis that enteric glia instead constitute a unique and heterogeneous group of glial cells. To define the level of heterogeneity, we first analyzed expression of the markers S100β, Sox10, GFAP, and proteolipid protein 1 (PLP1) in the small and large intestine of adult mice. Sox10 and S100β are widely expressed by enteric glia throughout the intestine. GFAP expression, however, is more restricted. Marker expression in combination with cellular location reproducibly distinguished subpopulations of enteric glia, suggesting that functional subtypes are likely to exist. Unexpectedly, we found that PLP1 is widely expressed by enteric glia, although they do not myelinate axons. We then performed RNA sequencing analysis (RNA-Seq) on PLP1-expressing cells in the mouse intestine and compared their gene expression to that of other types of glia in the CNS and PNS. This showed that enteric glia are transcriptionally distinct from other glial classes, and share the greatest similarity to myelinating glia. The gene expression database generated by this study will facilitate future studies of glial function in gastrointestinal physiology.