Hepatocyte Growth Factor and MET Support Mouse Enteric Nervous System Development, the Peristaltic Response, and Intestinal Epithelial Proliferation in Response to Injury.
Factors providing trophic support to diverse enteric neuron subtypes remain poorly understood. We tested the hypothesis that hepatocyte growth factor (HGF) and the HGF receptor MET might support some types of enteric neurons. HGF and MET are expressed in fetal and adult enteric nervous system. In vitro, HGF increased enteric neuron differentiation and neurite length, but only if vanishingly small amounts (1 pg/ml) of glial cell line-derived neurotrophic factor were included in culture media. HGF effects were blocked by phosphatidylinositol-3 kinase inhibitor and by MET-blocking antibody. Both of these inhibitors and MEK inhibition reduced neurite length. In adult mice, MET was restricted to a subset of calcitonin gene-related peptide-immunoreactive (IR) myenteric plexus neurons thought to be intrinsic primary afferent neurons (IPANs). Conditional MET kinase domain inactivation (Met(fl/fl); Wnt1Cre+) caused a dramatic loss of myenteric plexus MET-IR neurites and 1-1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyamine perchlorate (DiI) labeling suggested reduced MET-IR neurite length. In vitro, Met(fl/fl); Wnt1Cre+ mouse bowel had markedly reduced peristalsis in response to mucosal deformation, but normal response to radial muscle stretch. However, whole-bowel transit, small-bowel transit, and colonic-bead expulsion were normal in Met(fl/fl); Wnt1Cre+ mice. Finally, Met(fl/fl); Wnt1Cre+ mice had more bowel injury and reduced epithelial cell proliferation compared with WT animals after dextran sodium sulfate treatment. These results suggest that HGF/MET signaling is important for development and function of a subset IPANs and that these cells regulate intestinal motility and epithelial cell proliferation in response to bowel injury.


CONCLUSIONS
The enteric nervous system has many neuronal subtypes that coordinate and control intestinal activity. Trophic factors that support these neuron types and enhance neurite growth after fetal development are not well understood. We show that a subset of adult calcitonin gene-related peptide (CGRP)-expressing myenteric neurons produce MET, the receptor for hepatocyte growth factor, and that loss of MET activity affects peristalsis in response to mucosal stroking, reduces MET-immunoreactive neurites, and increases susceptibility to dextran sodium sulfate-induced bowel injury. These observations may be relevant for understanding and treating intestinal motility disorders and also suggest that enhancing the activity of MET-expressing CGRP neurons might be a useful strategy to reduce bowel inflammation.
Departments of Pediatrics, Developmental Regenerative and Stem Cell Biology, and.
Marina
http://orcid.org/0000-0001-9836-5005
M
Avetisyan
Departments of Pediatrics, Developmental Regenerative and Stem Cell Biology, and.
Hongtao
H
Wang
Departments of Pediatrics, Developmental Regenerative and Stem Cell Biology, and.
Ellen Merrick
http://orcid.org/0000-0003-2803-0132
EM
Schill
Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania and The Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania 19104.
Saya
http://orcid.org/0000-0003-3834-0417
S
Bery
Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, and.
John R
JR
Grider
Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
John A
JA
Hassell
Developmental Regenerative and Stem Cell Biology, and Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110.
Thaddeus
http://orcid.org/0000-0002-6023-3901
T
Stappenbeck
Departments of Pediatrics, Developmental Regenerative and Stem Cell Biology, and Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania and The Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania 19104, Heuckerothr@email.chop.edu.
Robert O
http://orcid.org/0000-0002-3282-1765
RO
Heuckeroth
D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D003092:Colitis / Q000503:physiopathology*; D017615:Enteric Nervous System / Q000473:pathology / Q000503:physiopathology; D017228:Hepatocyte Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010528:Peristalsis; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism* / Q000494:pharmacology
C553307:HGF protein, mouse; D017228:Hepatocyte Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met
MET; calcitonin gene-related peptide; dextran sodium sulfate (DSS); enteric nervous system; hepatocyte growth factor; intrinsic primary afferent neurons