Age-dependent replacement of neural-crest derived enteric neurons by a novel mesodermal lineage and its functional consequences

During fetal development, neural crest precursors give rise to neurons of the enteric nervoussystem (ENS). However, given our evolving understanding of the dynamic nature of the ENS, itis not clear whether this developmental paradigm holds true at different post-natal stages. Here,we show that due to loss of GDNF-RET signaling with age, neural crest-derived neurons un-dergo a progressive decline in numbers. They are replaced by neurons derived from the embry-onic mesoderm which, with increasing age, become the dominant form of neurons in the ENS,and this is associated with functional deficits in intestinal motility. Using single cell transcrip-tomics and immunochemical approaches, we characterize these mesoderm-derived neuronsand show that this novel lineage of neurons expresses MET and is dependent on HGF for itsexpansion. Normal intestinal function in the adult gastrointestinal tract therefore appears to re-quire an optimal balance between these two distinct lineages within the ENS. Two replicate samples of dissociated, postnatal day P180, mouse small intestinal longitudinal muscle-myenteric plexus were prepared and run through the 10x Chromium 3' Single Cell Gene Expression platform (V2.0).