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Smad3-null mice lack interstitial cells of Cajal in the colonic wall
A Vetuschi1, R Sferra, G Latella
1Università degli Studi di L'Aquila, L'Aquila, Italy.
Background:
Transforming growth factor-beta (TGF-beta)/Smad's signalling pathway plays a pivotal role in organogenesis, oncogenesis, inflammation, repair and fibrosis. The aim of this study was to evaluate the morphology of muscle layers and the density and distribution of interstitial cells of Cajal (ICC) in the colon of Smad3 knockout mice.
Materials And Methods:
Eighteen Smad3 wild-type mice and 12 null mice were sacrificed at age 4 months and the colons were collected for histology (Haematoxilin-Eosin, Masson thrichrome and Gomori silver staining), morphometry and immunohistochemistry (IHC) analysis. For IHC we used the c-Kit, alpha-smooth muscle actine (alpha-SMA), vimentin, desmin and neuronal cocktail (S-100, NSE, neurofilament 200) antibodies.
Results:
When sacrificed, 40% of the null mice showed different degrees of colon dilatation when compared with the wild-type. Histological and morphometric evaluation revealed a significant reduction in muscle layer thickness of the colon in all the null mice when compared with the wild-type. Immunohistochemistry evaluation showed a marked reduction, or even absence, of c-Kit immunoreactivity, which identifies ICC, in the colon of all the null mice, compared with the wild-type.
Conclusions:
Smad3 null mice showed a marked reduction, or even absence, of ICC in the colon together with a concomitant reduction of intestinal smooth muscle layer thickness. This data could account for the colonic dilation observed in approximately 40% of the Smad3 null mice. Alteration of intestinal smooth muscle layers and ICC could also be involved in the resistance of the Smad3 null mice to develop colonic fibrosis.
Insights
Smad3 knockout mice exhibit reduced interstitial cells of Cajal (ICC) and thinner colon muscle layers, leading to colonic dilation. This suggests ICC and muscle layer integrity are crucial for normal colon function.
Area of Science:
- Gastroenterology
- Developmental Biology
- Cell Biology
Background:
- The Transforming Growth Factor-beta (TGF-beta)/Smad signaling pathway is vital for organ development, cancer, inflammation, and tissue repair.
- Smad3 plays a critical role in this pathway.
Purpose of the Study:
- To investigate the impact of Smad3 deficiency on colon morphology, specifically muscle layer structure and interstitial cells of Cajal (ICC) distribution.
- To correlate observed morphological changes with functional consequences like colonic dilation.
Main Methods:
- Comparison of Smad3 wild-type and knockout mice colons using histological staining (H&E, Masson trichrome, Gomori silver).
- Morphometric analysis of muscle layer thickness.
- Immunohistochemistry (IHC) for c-Kit (identifies ICC), alpha-SMA, vimentin, desmin, and neuronal markers.
Main Results:
- Smad3 knockout mice showed a higher incidence of colonic dilation (40%) compared to wild-types.
- Significant reduction in colon muscle layer thickness was observed in all Smad3 knockout mice.
- A marked decrease or absence of c-Kit positive ICC was found in the colons of Smad3 knockout mice.
Conclusions:
- Smad3 deficiency leads to a significant reduction in colonic ICC and thinner intestinal smooth muscle layers.
- These alterations likely explain the observed colonic dilation in Smad3 knockout mice.
- Dysregulation of smooth muscle layers and ICC may influence resistance to colonic fibrosis in Smad3 null mice.
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