Proliferation in the Gastrointestinal Epithelium

2020

Cells

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The human intestine is covered by epithelium, which is continuously replaced by new cells provided by stem cells located at the bottom of the glands. The maintenance of intestinal stem cells is supported by a niche which is composed of several signaling proteins including the Hippo pathway effectors YAP1/TAZ. The role of YAP1/TAZ in cell proliferation and regeneration is well documented but their involvement on the differentiation of intestinal epithelial cells is unclear. In the present study, the role of YAP1/TAZ on the differentiation of intestinal epithelial cells was investigated using the HT29 cell line, the only multipotent intestinal cell line available, with a combination of knockdown approaches. The expression of intestinal differentiation cell markers was tested by qPCR, Western blot, indirect immunofluorescence and electron microscopy analyses. The results show that TAZ is not expressed while the abolition of YAP1 expression led to a sharp increase in goblet and absorptive cell differentiation and reduction of some stem cell markers. Further studies using double knockdown experiments revealed that most of these effects resulting from YAP1 abolition are mediated by CDX2, a key intestinal cell transcription factor. In conclusion, our results indicate that YAP1/TAZ negatively regulate the differentiation of intestinal epithelial cells through the inhibition of CDX2 expression.

Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Hippo Pathway Effector YAP1 Regulates Intestinal Epithelial Cell Differentiation

2020

Cells

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Differential influence of YAP1 and TAZ on differentiation of intestinal epithelial cell: A review

2022

The Anatomical Record

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Intestinal cell stemness, proliferation and differentiation are complex processes all occurring in distinct compartments of the crypt that need to be closely regulated to ensure proper epithelial renewal. The involvement of the Hippo pathway in intestinal epithelial proliferation and regeneration after injury via the regulation of its effectors YAP1 and TAZ has been well-documented over the last decade. The implication of YAP1 and TAZ on intestinal epithelial cell differentiation is less clear. Using intestinal cell models in which the expression of YAP1 and TAZ can be modulated, our group showed that YAP1 inhibits differentiation of the two main intestinal epithelial cell types, goblet and absorptive cells through a specific mechanism involving the repression of prodifferentiation transcription factor CDX2 expression. Further analysis provided evidence that the repressive effect of YAP1 on intestinal differentiation is mediated by regulation of the Hippo pathway by Src family kinase activity. Interestingly, the TAZ paralog does not seem to be involved in this process, which provides another example of the lack of perfect complementarity of the two main Hippo effectors.

Src family kinases inhibit differentiation of intestinal epithelial cells through the Hippo effector YAP1

2021

Biology Open

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Intestinal cell lineage differentiation is a tightly regulated mechanism that involves several intracellular signaling pathways affecting the expression of a variety of transcription factors, which ultimately regulate cell specific gene expression. Absorptive and goblet cells are the two main epithelial cell types of the intestine. Previous studies from our group using an shRNA knockdown approach have shown that YAP1, one of the main Hippo pathway effectors, inhibits the differentiation of these two cell types. In the present study, we show that YAP1 activity is regulated by Src family kinases (SFKs) in these cells. Inhibition of SFKs led to a sharp reduction in YAP1 expression at the protein level, an increase in CDX2 and the P1 forms of HNF4α and of absorptive and goblet cell differentiation specific markers. Interestingly, in Caco-2/15 cells which express both YAP1 and its paralog TAZ, TAZ was not reduced by the inhibition of SFKs and its specific knockdown rather impaired absorptive cell differentiation indicating that YAP1 and TAZ are not always interchangeable for regulating cell functions.