Hepatocyte Growth Factor and MET Support Mouse Enteric Nervous System Development, the Peristaltic Response, and Intestinal Epithelial Proliferation in Response to Injury
Bibliographic record
Abstract
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. SIGNIFICANCE STATEMENT: 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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".