Exploring neural crest stem cell-derived enteric neurogenesis in post-embryonic development and regeneration

PROJECT SUMMARY/ABSTRACT I am a gastroenterologist at UCLA, and I am committed to studying enteric neurogenesis to better inform development of therapies for enteric neuropathies such as Hirschsprung disease, esophageal achalasia, and gastroparesis. Historically, the enteric nervous system (ENS) was thought to be composed of a

finite pool of terminally differentiated neurons. This conception of the ENS supported therapeutic approaches for enteric neuropathies that largely seek to ameliorate symptoms but do not correct the underlying pathophysiology. Recently, this concept has been challenged by the identification of a novel source of enteric

neuronal progenitors that reside outside of the intestine, termed neural crest stem cells (NCSCs). This proposal outlines a 5-year research and career development plan that will prepare me to become an independent physician-scientist engaged in high-level scientific research. My aims are to elucidate the

origin, migration dynamics, and molecular signaling of NCSC-mediated enteric neurogenesis in development and regeneration. I will employ the zebrafish as my model organism as it overcomes several limitations faced by other models and is amenable to innovative techniques. Aim 1 will survey the post-embryonic intestine for

resident ENS progenitors using in situ hybridization and single cell RNA sequencing. My preliminary work supports the absence of ENS progenitors in the intestine. Aim 2 will employ an inducible Cre transgenic line and time-lapse confocal microscopy to determine the origin and migration dynamics of NCSCs that give rise to

enteric neurons. This Aim will assess persistence of NCSC contributions to the ENS through development and adulthood. My preliminary data provides evidence of NCSC-mediated enteric neurogenesis and supports the basis of this Aim. Lastly, Aim 3 will explore the role of 5HT4 receptor agonists in the promotion of NCSC-

mediated enteric neurogenesis in development and regeneration. Zebrafish are amenable to two-photon laser cell ablation, allowing ENS-specific injury by ablating individual enteric neurons. My preliminary work demonstrates increased enteric neurogenesis with 5HT4 receptor agonists, supporting the pursuit of this Aim.

Along with strong preliminary work and a well-conceived research plan, this proposal also includes an outstanding and multidisciplinary team of mentors and advisors, a crucial aspect to a successful transition to independence. My mentors, Dr. Bronner and Dr. Pothoulakis, are leaders in their respective fields of

developmental biology and cellular biology, and they are renowned mentors with a long history of successfully training young investigators. I will also receive critical guidance from advisors with widely recognized expertise in ENS development (Dr. Gershon), transcriptomics (Dr. Pachter), neurogenesis (Dr. Kornblum), and advanced

microscopy (Dr. Collazo). Together, with my extraordinary research environment, coursework and seminars, and the institutional support from my Division, this plan will ensure a robust training that will prepare me to transition into a high-impact independent investigator in neurogastroenterology.