Heuckeroth Lab Research Overview

The Enteric Nervous System (ENS) is a beautiful and complex network of neurons and supporting glial cells that is distributed along the length of the bowel in two interconnected networks called the myenteric and submucosal plexus. These neurons control intestinal motility, respond to sensory stimuli from the bowel wall and bowel lumen, regulate intestinal epithelial secretion and control intestinal blood flow. To perform these functions there are at least 20 different types of neuron including excitatory motor neurons, inhibitory motor neurons, interneurons, sensory neurons, and secretomotor neurons. Collectively, these neurons express every neurotransmitter found in the brain.

To learn more, here are our reviews about the enteric nervous system review about ENS development.

Schneider S, Wright CM, Heuckeroth RO. Unexpected Roles for the Second Brain: Enteric Nervous System as Master Regulator of Bowel Function. Annu Rev Physiol. 2019 Feb 10;81:235-259. doi: 10.1146/annurev-physiol-021317-121515. Epub 2018 Oct 31. PMID: 30379617.

Heuckeroth RO, Schäfer KH. Gene-environment interactions and the enteric nervous system: Neural plasticity and Hirschsprung disease prevention. Dev Biol. 2016 Sep 15;417(2):188-97. doi: 10.1016/j.ydbio.2016.03.017. Epub 2016 Mar 17. PMID: 26997034; PMCID: PMC5026873.

Avetisyan M, Schill EM, Heuckeroth RO. Building a second brain in the bowel. J Clin Invest. 2015 Mar 2;125(3):899-907. doi: 10.1172/JCI76307. Epub 2015 Feb 9. PMID: 25664848; PMCID: PMC4362233.

Lake JI, Heuckeroth RO. Enteric nervous system development: migration, differentiation, and disease. Am J Physiol Gastrointest Liver Physiol. 2013 Jul 1;305(1):G1-24. doi: 10.1152/ajpgi.00452.2012. Epub 2013 May 2. PMID: 23639815; PMCID: PMC3725693.

Our research team is interested in determining molecular mechanisms that control ENS development and ENS function. This is important because ENS defects cause serious problems with intestinal function. This includes Hirschsprung disease, intestinal pseudo-obstruction syndrome, and probably some forms of irritable bowel syndrome. Symptoms may include constipation, vomiting, and growth failure. Some of the more severe forms of intestinal motility disorder may be fatal. By defining the molecules that are critical for ENS development and function, the Heuckeroth Lab hopes to find new ways to prevent and treat intestinal motility disorders.

The Heuckeroth Lab has shown that retinoids (vitamin A metabolites) are critical for ENS precursor migration into the distal bowel and that retinoids influence ENS precursor proliferation and differentiation. In part, the effect of retinoids in the developing ENS is mediated via retinoid acid induced reductions in PTEN protein in the most actively migrating ENS precursors. The Lab's work with an animal model with mutations in Raldh1, Raldh2, and Raldh3 suggests complex roles for retinoids within the ENS and within other cells of the bowel wall.

Ongoing studies are focused on determining the relative importance or retinoic acid signaling within ENS precursors or in other cells of the bowel wall. Defining the signaling pathways that cause the profound effects of retinoids on the developing ENS is already leading to new insight into how the ENS forms.

Related Publications

Gao T, Wright-Jin EC, Sengupta R, Anderson JB, Heuckeroth RO. Cell-autonomous retinoic acid receptor signaling has stage-specific effects on mouse enteric nervous system. JCI Insight. 2021;6(10):e145854. PMID: 33848271

Fu M, Sato Y, Lyons-Warren A, Zhang B, Kane MA, Napoli JL, Heuckeroth RO. Vitamin A facilitates enteric nervous system precursor migration by reducing Pten accumulation. Development. 2010 Feb;137(4):631-640. PMID: 20110328

Sato Y, Heuckeroth RO. Retinoic acid regulates murine enteric nervous system precursor proliferation, enhances neuronal precursor differentiation, and reduces neurite growth in vitro. Dev Biol. 2008 Aug 1;320(1):185-98. PMID: 18561907

Wright-Jin EC, Grider JR, Duester G, Heuckeroth RO. Retinaldehyde dehydrogenase enzymes regulate colon enteric nervous system structure and function. Dev Biol. 2013 Sep 1;381(1):28-37. PMID: 23806210

After more than a decade studying signaling pathways that control ENS development, the Heuckeroth Lab recognized that many of the molecules they were investigating are influenced by non-genetic factors. The research team's work led to the identification of several medicines that affect ENS development. Ongoing studies examine how some of these medicines affect the developing ENS suggest that some human intestinal motility disorders, including Hirschsprung disease, may be preventable by avoiding specific medicines during early pregnancy.

Related Publications

Schill EM, Lake JI, Tusheva OA, et al. Ibuprofen slows migration and inhibits bowel colonization by enteric nervous system precursors in zebrafish, chick and mouse. Dev Biol. 2016;409(2):473-488. PMID: 26586201

Lake JI, Tusheva OA, Graham BL, Heuckeroth RO. Hirshsprung-like disease is exacerbated by reduce de novo GMP synthesis. J Clin Invest. 2013 Nov; 123(11):4875-4887. PMID: 24216510

Development of the ENS requires coordinated cell migration and proliferation of precursors followed by differentiation into neurons and glia. This process is guided and supported by a wide array of molecules. There are well established roles for tyrosine kinase receptors and co-receptors (RET, GFRalpha1, GFRalpha1, TRKC) and their ligands (GDNF, NRTN, NT3), the G-protein coupled receptors (EDNRB), the ligand EDN3, and protease ECE1, morphogens and differentiation factors (BMP2/4, SHH, IHH, RA), transcription factors (SOX10, ZFHX1B, PHOX2B), and many additional intracellular, extracellular and transmembrane proteins (GSK3, PKCzeta, RAC, RHO, SMURF1, KBP, laminin, fibronectin, etc.). These proteins have additional roles during development and in postnatal life. Because diverse cell types respond differently to the same protein, essentially all of our studies are performed in vitro or in vivo using ENS precursors and surrounding cells.

Ret is a growth factor receptor that transduces signals from four ligands (GDNF, neurturin, artemin and persephin) via four glycosylphosphatidyl inositol linked co-receptors (GFRalpha1, GFRalpha2, GFRalpha3 and GFRalpha4 respectively). Inactivating Ret mutations occur on one chromosome in 50% of people with familial Hirschsprung disease and in 15% of people "sporadic" disease. However, most people with Hirschsprung disease have either an inactivating Ret mutation or changes in their DNA that reduce Ret expression. The Heuckeroth Lab has been studying Ret since 1994, but many investigators around the world also study this protein.

What have we learned about Ret? The research team's ongoing work has demonstrated that Ret signaling is important for ENS precursor survival, proliferation, migration, neuronal differentiation and neurite growth. These diverse roles for Ret explain why inactivating Ret mutations predispose to Hirschsprung disease. Less severe Ret mutations may also cause defective intestinal motility without causing aganglionosis. Working with mutant mice, the Heuckeroth Lab has demonstrated a wide array of structural and functional defects.

Ongoing studies suggest that hundreds of molecules influence ENS development and function. Given all of the features of the ENS that must be specified and directed, it is likely that we still only know a fraction of the molecules required to make a functioning ENS. For example, very little is known about the molecular mechanisms that determine what type of neuron an ENS precursor will become. Mechanisms that guide enteric neuron axons or that influence regional patterns of intestinal innervation remain poorly understood. Mechanisms that cause adjacent cells to adopt different fates are essentially unknown. To approach these problems, it is essential to know more about patterns of gene expression in the developing bowel.

The Heuckeroth Lab has used a wide variety of approaches to identify genes expressed within the ENS and in cells surrounding developing ENS precursors. Using these methods, the research team has identified many "candidate" molecules that may influence ENS development and functional roles for many of these proteins.